libmicrohttpd2

microhttpd2_main.h.in (227722B)

---

 /**
  * Create parameter for #MHD_daemon_set_options() for work mode with
  * no internal threads.
  * The application periodically calls #MHD_daemon_process_blocking(), where
  * MHD internally checks all sockets automatically.
  * This is the default mode.
  * @return the object of struct MHD_DaemonOptionAndValue with requested values
  */
 #define MHD_D_OPTION_WM_EXTERNAL_PERIODIC() \
         MHD_D_OPTION_WORK_MODE (MHD_WM_OPTION_EXTERNAL_PERIODIC ())
 
 /**
 * Create parameter for #MHD_daemon_set_options() for work mode with
 * an external event loop with level triggers.
 * Application uses #MHD_SocketRegistrationUpdateCallback, level triggered
 * sockets polling (like select() or poll()) and #MHD_daemon_event_update().
 * @param cb_val the callback for sockets registration
 * @param cb_cls_val the closure for the @a cv_val callback
 * @return the object of struct MHD_DaemonOptionAndValue with requested values
 */
 #define MHD_D_OPTION_WM_EXTERNAL_EVENT_LOOP_CB_LEVEL(cb_val,cb_cls_val) \
         MHD_D_OPTION_WORK_MODE ( \
           MHD_WM_OPTION_EXTERNAL_EVENT_LOOP_CB_LEVEL ((cb_val),(cb_cls_val)))
 
 /**
  * Create parameter for #MHD_daemon_set_options() for work mode with
  * an external event loop with edge triggers.
  * Application uses #MHD_SocketRegistrationUpdateCallback, edge triggered
  * sockets polling (like epoll with EPOLLET) and #MHD_daemon_event_update().
  * @param cb_val the callback for sockets registration
  * @param cb_cls_val the closure for the @a cv_val callback
  * @return the object of struct MHD_DaemonOptionAndValue with requested values
  */
 #define MHD_D_OPTION_WM_EXTERNAL_EVENT_LOOP_CB_EDGE(cb_val,cb_cls_val) \
         MHD_D_OPTION_WORK_MODE ( \
           MHD_WM_OPTION_EXTERNAL_EVENT_LOOP_CB_EDGE ((cb_val),(cb_cls_val)))
 
 /**
  * Create parameter for #MHD_daemon_set_options() for work mode with
  * no internal threads and aggregate watch FD.
  * Application uses #MHD_DAEMON_INFO_FIXED_AGGREAGATE_FD to get single FD
  * that gets triggered by any MHD event.
  * This FD can be watched as an aggregate indicator for all MHD events.
  * This mode is available only on selected platforms (currently
  * GNU/Linux only), see #MHD_LIB_INFO_FIXED_HAS_AGGREGATE_FD.
  * When the FD is triggered, #MHD_daemon_process_nonblocking() should
  * be called.
  * @return the object of struct MHD_DaemonOptionAndValue with requested values
  */
 #define MHD_D_OPTION_WM_EXTERNAL_SINGLE_FD_WATCH() \
         MHD_D_OPTION_WORK_MODE (MHD_WM_OPTION_EXTERNAL_SINGLE_FD_WATCH ())
 
 /**
  * Create parameter for #MHD_daemon_set_options() for work mode with
  * one or more worker threads.
  * If number of threads is one, then daemon starts with single worker thread
  * that handles all connections.
  * If number of threads is larger than one, then that number of worker threads,
  * and handling of connection is distributed among the workers.
  * @param num_workers the number of worker threads, zero is treated as one
  * @return the object of struct MHD_DaemonOptionAndValue with requested values
  */
 #define MHD_D_OPTION_WM_WORKER_THREADS(num_workers) \
         MHD_D_OPTION_WORK_MODE (MHD_WM_OPTION_WORKER_THREADS (num_workers))
 
 /**
  * Create parameter for #MHD_daemon_set_options() for work mode with
  * one internal thread for listening and additional threads per every
  * connection.  Use this if handling requests is CPU-intensive or blocking,
  * your application is thread-safe and you have plenty of memory (per
  * connection).
  * @return the object of struct MHD_DaemonOptionAndValue with requested values
  */
 #define MHD_D_OPTION_WM_THREAD_PER_CONNECTION() \
         MHD_D_OPTION_WORK_MODE (MHD_WM_OPTION_THREAD_PER_CONNECTION ())
 
 /**
  * Set the requested options for the daemon.
  *
  * If any option fail other options may be or may be not applied.
  * @param daemon the daemon to set the options
  * @param[in] options the pointer to the array with the options;
  *                    the array processing stops at the first ::MHD_D_O_END
  *                    option, but not later than after processing
  *                    @a options_max_num entries
  * @param options_max_num the maximum number of entries in the @a options,
  *                        use #MHD_OPTIONS_ARRAY_MAX_SIZE if options processing
  *                        must stop only at zero-termination option
  * @return ::MHD_SC_OK on success,
  *         error code otherwise
  */
 MHD_EXTERN_ enum MHD_StatusCode
 MHD_daemon_set_options (
   struct MHD_Daemon *MHD_RESTRICT daemon,
   const struct MHD_DaemonOptionAndValue *MHD_RESTRICT options,
   size_t options_max_num)
 MHD_FN_PAR_NONNULL_ALL_;
 
 
 /**
  * Set the requested single option for the daemon.
  *
  * @param daemon the daemon to set the option
  * @param[in] option_ptr the pointer to the option
  * @return ::MHD_SC_OK on success,
  *         error code otherwise
  */
 #define MHD_daemon_set_option(daemon, option_ptr) \
         MHD_daemon_set_options (daemon, option_ptr, 1)
 
 
 /* *INDENT-OFF* */
 #ifdef MHD_USE_VARARG_MACROS
 MHD_NOWARN_VARIADIC_MACROS_
 #  if defined(MHD_USE_COMPOUND_LITERALS) && \
   defined(MHD_USE_COMP_LIT_FUNC_PARAMS)
 /**
  * Set the requested options for the daemon.
  *
  * If any option fail other options may be or may be not applied.
  *
  * It should be used with helpers that creates required options, for example:
  *
  * MHD_DAEMON_SET_OPTIONS(d, MHD_D_OPTION_SUPPRESS_DATE_HEADER(MHD_YES),
  *                        MHD_D_OPTION_SOCK_ADDR(sa_len, sa))
  *
  * @param daemon the daemon to set the options
  * @param ... the list of the options, each option must be created
  *            by helpers MHD_D_OPTION_NameOfOption(option_value)
  * @return ::MHD_SC_OK on success,
  *         error code otherwise
  */
 #    define MHD_DAEMON_SET_OPTIONS(daemon,...)          \
         MHD_NOWARN_COMPOUND_LITERALS_                   \
         MHD_NOWARN_AGGR_DYN_INIT_                       \
         MHD_daemon_set_options (                        \
           daemon,                                       \
           ((const struct MHD_DaemonOptionAndValue[])    \
            {__VA_ARGS__, MHD_D_OPTION_TERMINATE ()}),   \
           MHD_OPTIONS_ARRAY_MAX_SIZE)                   \
         MHD_RESTORE_WARN_AGGR_DYN_INIT_                 \
         MHD_RESTORE_WARN_COMPOUND_LITERALS_
 #  elif defined(MHD_USE_CPP_INIT_LIST)
 MHD_C_DECLRATIONS_FINISH_HERE_
 #    include <vector>
 MHD_C_DECLRATIONS_START_HERE_
 /**
  * Set the requested options for the daemon.
  *
  * If any option fail other options may be or may be not applied.
  *
  * It should be used with helpers that creates required options, for example:
  *
  * MHD_DAEMON_SET_OPTIONS(d, MHD_D_OPTION_SUPPRESS_DATE_HEADER(MHD_YES),
  *                        MHD_D_OPTION_SOCK_ADDR(sa_len, sa))
  *
  * @param daemon the daemon to set the options
  * @param ... the list of the options, each option must be created
  *            by helpers MHD_D_OPTION_NameOfOption(option_value)
  * @return ::MHD_SC_OK on success,
  *         error code otherwise
  */
 #    define MHD_DAEMON_SET_OPTIONS(daemon,...)                  \
         MHD_NOWARN_CPP_INIT_LIST_                               \
         MHD_daemon_set_options (                                \
           daemon,                                               \
           (std::vector<struct MHD_DaemonOptionAndValue>         \
            {__VA_ARGS__,MHD_D_OPTION_TERMINATE ()}).data (),    \
           MHD_OPTIONS_ARRAY_MAX_SIZE)                           \
         MHD_RESTORE_WARN_CPP_INIT_LIST_
 #  endif
 MHD_RESTORE_WARN_VARIADIC_MACROS_
 #endif /* MHD_USE_VARARG_MACROS && MHD_USE_COMP_LIT_FUNC_PARAMS */
 /* *INDENT-ON* */
 
 
 /* ******************* Event loop ************************ */
 
 
 /**
  * Run websever operation with possible blocking.
  *
  * Supported only in #MHD_WM_EXTERNAL_PERIODIC and
  * #MHD_WM_EXTERNAL_SINGLE_FD_WATCH modes.
  *
  * This function does the following: waits for any network event not more than
  * specified number of microseconds, processes all incoming and outgoing data,
  * processes new connections, processes any timed-out connection, and does
  * other things required to run webserver.
  * Once all connections are processed, function returns.
  *
  * This function is useful for quick and simple (lazy) webserver implementation
  * if application needs to run a single thread only and does not have any other
  * network activity.
  *
  * In #MHD_WM_EXTERNAL_PERIODIC mode if @a microsec parameter is not zero
  * this function determines the internal daemon timeout and use returned value
  * as maximum wait time if it less than value of @a microsec parameter.
  *
  * @param daemon the daemon to run
  * @param microsec the maximum time in microseconds to wait for network and
  *                 other events. Note: there is no guarantee that function
  *                 blocks for the specified amount of time. The real processing
  *                 time can be shorter (if some data or connection timeout
  *                 comes earlier) or longer (if data processing requires more
  *                 time, especially in user callbacks).
  *                 If set to '0' then function does not block and processes
  *                 only already available data (if any). Zero value is
  *                 recommended when used in #MHD_WM_EXTERNAL_SINGLE_FD_WATCH
  *                 and the watched FD has been triggered.
  *                 If set to #MHD_WAIT_INDEFINITELY then function waits
  *                 for events indefinitely (blocks until next network activity
  *                 or connection timeout).
  *                 Always used as zero value in
  *                 #MHD_WM_EXTERNAL_SINGLE_FD_WATCH mode.
  * @return #MHD_SC_OK on success, otherwise
  *         an error code
  * @ingroup event
  */
 MHD_EXTERN_ enum MHD_StatusCode
 MHD_daemon_process_blocking (struct MHD_Daemon *daemon,
                              uint_fast64_t microsec)
 MHD_FN_PAR_NONNULL_ (1);
 
 /**
  * Run webserver operations (without blocking unless in client
  * callbacks).
  *
  * Supported only in #MHD_WM_EXTERNAL_SINGLE_FD_WATCH mode.
  *
  * This function does the following: processes all incoming and outgoing data,
  * processes new connections, processes any timed-out connection, and does
  * other things required to run webserver.
  * Once all connections are processed, function returns.
  *
  * @param daemon the daemon to run
  * @return #MHD_SC_OK on success, otherwise
  *         an error code
  * @ingroup event
  */
 #define MHD_daemon_process_nonblocking(daemon) \
         MHD_daemon_process_blocking (daemon, 0)
 
 
 /**
  * Add another client connection to the set of connections managed by
  * MHD.  This API is usually not needed (since MHD will accept inbound
  * connections on the server socket).  Use this API in special cases,
  * for example if your HTTP server is behind NAT and needs to connect
  * out to the HTTP client, or if you are building a proxy.
  *
  * The given client socket will be managed (and closed!) by MHD after
  * this call and must no longer be used directly by the application
  * afterwards.
  * The client socket will be closed by MHD even if error returned.
  *
  * @param daemon daemon that manages the connection
  * @param client_socket socket to manage (MHD will expect
  *        to receive an HTTP request from this socket next).
  * @param[in] addr IP address of the client
  * @param addrlen number of bytes in @a addr
  * @param connection_cntx meta data the application wants to
  *        associate with the new connection object
  * @return #MHD_SC_OK on success,
  *         error on failure (the @a client_socket is closed)
  * @ingroup specialized
  */
 MHD_EXTERN_ enum MHD_StatusCode
 MHD_daemon_add_connection (struct MHD_Daemon *MHD_RESTRICT daemon,
                            MHD_Socket client_socket,
                            size_t addrlen,
                            const struct sockaddr *MHD_RESTRICT addr,
                            void *connection_cntx)
 MHD_FN_PAR_NONNULL_ (1)
 MHD_FN_PAR_IN_ (4);
 
 
 /* ********************* connection options ************** */
 
 enum MHD_FIXED_ENUM_APP_SET_ MHD_ConnectionOption
 {
   /**
    * Not a real option.
    * Should not be used directly.
    * This value indicates the end of the list of the options.
    */
   MHD_C_O_END = 0
   ,
   /**
    * Set custom timeout for the given connection.
    * Specified as the number of seconds.  Use zero for no timeout.
    * Setting this option resets connection timeout timer.
    */
   MHD_C_O_TIMEOUT = 1
   ,
 
 
   /* * Sentinel * */
   /**
    * The sentinel value.
    * This value enforces specific underlying integer type for the enum.
    * Do not use.
    */
   MHD_C_O_SENTINEL = 65535
 };
 
 
 /**
  * Dummy-struct for space allocation.
  * Do not use in application logic.
  */
 struct MHD_ReservedStruct
 {
   uint_fast64_t reserved1;
   void *reserved2;
 };
 
 
 /**
  * Parameters for MHD connection options
  */
 union MHD_ConnectionOptionValue
 {
   /**
    * Value for #MHD_C_O_TIMEOUT
    */
   unsigned int v_timeout;
   /**
    * Reserved member. Do not use.
    */
   struct MHD_ReservedStruct reserved;
 };
 
 /**
  * Combination of MHD connection option with parameters values
  */
 struct MHD_ConnectionOptionAndValue
 {
   /**
    * The connection configuration option
    */
   enum MHD_ConnectionOption opt;
   /**
    * The value for the @a opt option
    */
   union MHD_ConnectionOptionValue val;
 };
 
 #if defined(MHD_USE_COMPOUND_LITERALS) && defined(MHD_USE_DESIG_NEST_INIT)
 /**
  * Set custom timeout for the given connection.
  * Specified as the number of seconds.  Use zero for no timeout.
  * Setting this option resets connection timeout timer.
  * @param timeout the in seconds, zero for no timeout
  * @return the object of struct MHD_ConnectionOptionAndValue with the requested
  *         values
  */
 #  define MHD_C_OPTION_TIMEOUT(timeout)         \
         MHD_NOWARN_COMPOUND_LITERALS_                 \
           (const struct MHD_ConnectionOptionAndValue) \
         {                                             \
           .opt = (MHD_C_O_TIMEOUT),                   \
           .val.v_timeout = (timeout)                  \
         }                                             \
         MHD_RESTORE_WARN_COMPOUND_LITERALS_
 
 /**
  * Terminate the list of the options
  * @return the terminating object of struct MHD_ConnectionOptionAndValue
  */
 #  define MHD_C_OPTION_TERMINATE()              \
         MHD_NOWARN_COMPOUND_LITERALS_                 \
           (const struct MHD_ConnectionOptionAndValue) \
         {                                             \
           .opt = (MHD_C_O_END)                        \
         }                                             \
         MHD_RESTORE_WARN_COMPOUND_LITERALS_
 
 #else  /* !MHD_USE_COMPOUND_LITERALS || !MHD_USE_DESIG_NEST_INIT */
 MHD_NOWARN_UNUSED_FUNC_
 
 /**
  * Set custom timeout for the given connection.
  * Specified as the number of seconds.  Use zero for no timeout.
  * Setting this option resets connection timeout timer.
  * @param timeout the in seconds, zero for no timeout
  * @return the object of struct MHD_ConnectionOptionAndValue with the requested
  *         values
  */
 static MHD_INLINE struct MHD_ConnectionOptionAndValue
 MHD_C_OPTION_TIMEOUT (unsigned int timeout)
 {
   struct MHD_ConnectionOptionAndValue opt_val;
 
   opt_val.opt = MHD_C_O_TIMEOUT;
   opt_val.val.v_timeout = timeout;
 
   return opt_val;
 }
 
 
 /**
  * Terminate the list of the options
  * @return the terminating object of struct MHD_ConnectionOptionAndValue
  */
 static MHD_INLINE struct MHD_ConnectionOptionAndValue
 MHD_C_OPTION_TERMINATE (void)
 {
   struct MHD_ConnectionOptionAndValue opt_val;
 
   opt_val.opt = MHD_C_O_END;
 
   return opt_val;
 }
 
 
 MHD_RESTORE_WARN_UNUSED_FUNC_
 #endif /* !MHD_USE_COMPOUND_LITERALS || !MHD_USE_DESIG_NEST_INIT */
 
 /**
  * Set the requested options for the connection.
  *
  * If any option fail other options may be or may be not applied.
  * @param connection the connection to set the options
  * @param[in] options the pointer to the array with the options;
  *                    the array processing stops at the first ::MHD_D_O_END
  *                    option, but not later than after processing
  *                    @a options_max_num entries
  * @param options_max_num the maximum number of entries in the @a options,
  *                        use #MHD_OPTIONS_ARRAY_MAX_SIZE if options processing
  *                        must stop only at zero-termination option
  * @return ::MHD_SC_OK on success,
  *         error code otherwise
  */
 MHD_EXTERN_ enum MHD_StatusCode
 MHD_connection_set_options (
   struct MHD_Connection *MHD_RESTRICT connection,
   const struct MHD_ConnectionOptionAndValue *MHD_RESTRICT options,
   size_t options_max_num)
 MHD_FN_PAR_NONNULL_ALL_;
 
 
 /**
  * Set the requested single option for the connection.
  *
  * @param connection the connection to set the options
  * @param[in] option_ptr the pointer to the option
  * @return ::MHD_SC_OK on success,
  *         error code otherwise
  */
 #define MHD_connection_set_option(connection, option_ptr) \
         MHD_connection_set_options (connection, options_ptr, 1)
 
 
 /* *INDENT-OFF* */
 #ifdef MHD_USE_VARARG_MACROS
 MHD_NOWARN_VARIADIC_MACROS_
 #  if defined(MHD_USE_COMPOUND_LITERALS) && defined(MHD_USE_COMP_LIT_FUNC_PARAMS \
                                                     )
 /**
  * Set the requested options for the connection.
  *
  * If any option fail other options may be or may be not applied.
  *
  * It should be used with helpers that creates required options, for example:
  *
  * MHD_CONNECTION_SET_OPTIONS(d, MHD_C_OPTION_TIMEOUT(30))
  *
  * @param connection the connection to set the options
  * @param ... the list of the options, each option must be created
  *            by helpers MHD_C_OPTION_NameOfOption(option_value)
  * @return ::MHD_SC_OK on success,
  *         error code otherwise
  */
 #    define MHD_CONNECTION_SET_OPTIONS(connection,...)          \
         MHD_NOWARN_COMPOUND_LITERALS_                           \
         MHD_connection_set_options (                            \
           daemon,                                               \
           ((const struct MHD_ConnectionOptionAndValue [])       \
            {__VA_ARGS__, MHD_C_OPTION_TERMINATE ()}),           \
           MHD_OPTIONS_ARRAY_MAX_SIZE)                           \
         MHD_RESTORE_WARN_COMPOUND_LITERALS_
 #  elif defined(MHD_USE_CPP_INIT_LIST)
 MHD_C_DECLRATIONS_FINISH_HERE_
 #    include <vector>
 MHD_C_DECLRATIONS_START_HERE_
 /**
  * Set the requested options for the connection.
  *
  * If any option fail other options may be or may be not applied.
  *
  * It should be used with helpers that creates required options, for example:
  *
  * MHD_CONNECTION_SET_OPTIONS(d, MHD_C_OPTION_TIMEOUT(30))
  *
  * @param connection the connection to set the options
  * @param ... the list of the options, each option must be created
  *            by helpers MHD_C_OPTION_NameOfOption(option_value)
  * @return ::MHD_SC_OK on success,
  *         error code otherwise
  */
 #    define MHD_CONNECTION_SET_OPTIONS(daemon,...)              \
         MHD_NOWARN_CPP_INIT_LIST_                               \
         MHD_daemon_set_options (                                \
           daemon,                                               \
           (std::vector<struct MHD_ConnectionOptionAndValue>     \
            {__VA_ARGS__,MHD_C_OPTION_TERMINATE ()}).data (),    \
           MHD_OPTIONS_ARRAY_MAX_SIZE)                           \
         MHD_RESTORE_WARN_CPP_INIT_LIST_
 #  endif
 MHD_RESTORE_WARN_VARIADIC_MACROS_
 #endif /* MHD_USE_VARARG_MACROS && MHD_USE_COMP_LIT_FUNC_PARAMS */
 /* *INDENT-ON* */
 
 
 /* **************** Request handling functions ***************** */
 
 
 /**
  * The `enum MHD_ValueKind` specifies the source of
  * the name-value pairs in the HTTP protocol.
  */
 enum MHD_FLAGS_ENUM_ MHD_ValueKind
 {
 
   /**
    * HTTP header.
    * The 'value' for this kind is mandatory.
    */
   MHD_VK_HEADER = (1u << 0)
   ,
   /**
    * Cookies.  Note that the original HTTP header containing
    * the cookie(s) will still be available and intact.
    * The 'value' for this kind is optional.
    */
   MHD_VK_COOKIE = (1u << 1)
   ,
   /**
    * URI query parameter.
    * The 'value' for this kind is optional.
    */
   MHD_VK_URI_QUERY_PARAM = (1u << 2)
   ,
   /**
    * POST data.
    * This is available only if #MHD_action_parse_post() action is used,
    * a content encoding is supported by MHD, and only if the posted content
    * fits within the specified memory buffers.
    *
    * @warning The encoding "multipart/form-data" has more fields than just
    * "name" and "value". See #MHD_request_get_post_data_cb() and
    * #MHD_request_get_post_data_list(). In particular it could be important
    * to check used "Transfer-Encoding". While it is deprecated and not used
    * by modern clients, formally it can be used.
    */
   MHD_VK_POSTDATA = (1u << 3)
   ,
   /**
    * HTTP trailer (only for HTTP 1.1 chunked encodings, "footer").
    * The 'value' for this kind is mandatory.
    */
   MHD_VK_TRAILER = (1u << 4)
   ,
   /**
    * Header and trailer values.
    */
   MHD_VK_HEADER_TRAILER = MHD_VK_HEADER | MHD_VK_TRAILER
   ,
   /**
    * Values from URI query parameters or post data.
    */
   MHD_VK_URI_QUERY_POST = MHD_VK_POSTDATA | MHD_VK_URI_QUERY_PARAM
 };
 
 /**
  * Name with value pair
  */
 struct MHD_NameAndValue
 {
   /**
    * The name (key) of the field.
    * The pointer to the C string must never be NULL.
    * Some types (kinds) allow empty strings.
    */
   struct MHD_String name;
   /**
    * The value of the field.
    * Some types (kinds) allow absence of the value. The absence is indicated
    * by NULL pointer to the C string.
    */
   struct MHD_StringNullable value;
 };
 
 /**
  * Name, value and kind (type) of data
  */
 struct MHD_NameValueKind
 {
   /**
    * The name and the value of the field
    */
   struct MHD_NameAndValue nv;
   /**
    * The kind (type) of the field
    */
   enum MHD_ValueKind kind;
 };
 
 /**
  * Iterator over name-value pairs.  This iterator can be used to
  * iterate over all of the cookies, headers, footers or POST-data fields
  * of a request.
  *
  * The @a nv pointer is valid only until return from this function.
  *
  * The strings in @a nv are valid until any MHD_Action or MHD_UploadAction
  * is provided.
  * If the data is needed beyond this point, it should be copied.
  *
  * @param cls closure
  * @param nv the name and the value of the element, the pointer is valid only until
  *           return from this function
  * @param kind the type (kind) of the element
  * @return #MHD_YES to continue iterating,
  *         #MHD_NO to abort the iteration
  * @ingroup request
  */
 typedef enum MHD_Bool
 (MHD_FN_PAR_NONNULL_ (3)
  *MHD_NameValueIterator)(void *cls,
                          enum MHD_ValueKind kind,
                          const struct MHD_NameAndValue *nv);
 
 
 /**
  * Get all of the headers (or other kind of request data) via callback.
  *
  * @param[in,out] request request to get values from
  * @param kind types of values to iterate over, can be a bitmask
  * @param iterator callback to call on each header;
  *        maybe NULL (then just count headers)
  * @param iterator_cls extra argument to @a iterator
  * @return number of entries iterated over
  * @ingroup request
  */
 MHD_EXTERN_ size_t
 MHD_request_get_values_cb (struct MHD_Request *request,
                            enum MHD_ValueKind kind,
                            MHD_NameValueIterator iterator,
                            void *iterator_cls)
 MHD_FN_PAR_NONNULL_ (1);
 
 
 /**
  * Get all of the headers (or other kind of request data) from the request.
  *
  * The pointers to the strings in @a elements are valid until any
  * MHD_Action or MHD_UploadAction is provided. If the data is needed beyond
  * this point, it should be copied.
  *
  * @param[in] request request to get values from
  * @param kind the types of values to get, can be a bitmask
  * @param num_elements the number of elements in @a elements array
  * @param[out] elements the array of @a num_elements strings to be filled with
  *                      the key-value pairs; if @a request has more elements
  *                      than @a num_elements than any @a num_elements are
  *                      stored
  * @return the number of elements stored in @a elements, the
  *         number cannot be larger then @a num_elements,
  *         zero if there is no such values or any error occurs
  */
 MHD_EXTERN_ size_t
 MHD_request_get_values_list (
   struct MHD_Request *request,
   enum MHD_ValueKind kind,
   size_t num_elements,
   struct MHD_NameValueKind elements[MHD_FN_PAR_DYN_ARR_SIZE_ (num_elements)])
 MHD_FN_PAR_NONNULL_ (1)
 MHD_FN_PAR_NONNULL_ (4) MHD_FN_PAR_OUT_SIZE_ (4,3);
 
 
 /**
  * Get a particular header (or other kind of request data) value.
  * If multiple values match the kind, return any one of them.
  *
  * The data in the @a value_out is valid until any MHD_Action or
  * MHD_UploadAction is provided. If the data is needed beyond this point,
  * it should be copied.
  *
  * @param request request to get values from
  * @param kind what kind of value are we looking for
  * @param key the name of the value looking for (used for case-insensetive
  *            match), empty to lookup 'trailing' value without a key
  * @param[out] value_out set to the value of the header if succeed,
  *                       the @a cstr pointer could be NULL even if succeed
  *                       if the requested item found, but has no value
  * @return #MHD_YES if succeed, the @a value_out is set;
  *         #MHD_NO if no such item was found, the @a value_out string pointer
  *                 set to NULL
  * @ingroup request
  */
 MHD_EXTERN_ enum MHD_Bool
 MHD_request_get_value (struct MHD_Request *MHD_RESTRICT request,
                        enum MHD_ValueKind kind,
                        const char *MHD_RESTRICT key,
                        struct MHD_StringNullable *MHD_RESTRICT value_out)
 MHD_FN_PAR_NONNULL_ (1)
 MHD_FN_PAR_NONNULL_ (3) MHD_FN_PAR_CSTR_ (3)
 MHD_FN_PAR_OUT_ (4);
 
 
 /**
  * @brief Status codes defined for HTTP responses.
  *
  * @defgroup httpcode HTTP response codes
  * @{
  */
 /* Registry export date: 2023-09-29 */
 /* See http://www.iana.org/assignments/http-status-codes/http-status-codes.xhtml */
 enum MHD_FIXED_ENUM_APP_SET_ MHD_HTTP_StatusCode
 {
   /* 100 "Continue".            RFC9110, Section 15.2.1. */
   MHD_HTTP_STATUS_CONTINUE =                    100
   ,
   /* 101 "Switching Protocols". RFC9110, Section 15.2.2. */
   MHD_HTTP_STATUS_SWITCHING_PROTOCOLS =         101
   ,
   /* 102 "Processing".          RFC2518. */
   MHD_HTTP_STATUS_PROCESSING =                  102
   ,
   /* 103 "Early Hints".         RFC8297. */
   MHD_HTTP_STATUS_EARLY_HINTS =                 103
   ,
 
   /* 200 "OK".                  RFC9110, Section 15.3.1. */
   MHD_HTTP_STATUS_OK =                          200
   ,
   /* 201 "Created".             RFC9110, Section 15.3.2. */
   MHD_HTTP_STATUS_CREATED =                     201
   ,
   /* 202 "Accepted".            RFC9110, Section 15.3.3. */
   MHD_HTTP_STATUS_ACCEPTED =                    202
   ,
   /* 203 "Non-Authoritative Information". RFC9110, Section 15.3.4. */
   MHD_HTTP_STATUS_NON_AUTHORITATIVE_INFORMATION = 203
   ,
   /* 204 "No Content".          RFC9110, Section 15.3.5. */
   MHD_HTTP_STATUS_NO_CONTENT =                  204
   ,
   /* 205 "Reset Content".       RFC9110, Section 15.3.6. */
   MHD_HTTP_STATUS_RESET_CONTENT =               205
   ,
   /* 206 "Partial Content".     RFC9110, Section 15.3.7. */
   MHD_HTTP_STATUS_PARTIAL_CONTENT =             206
   ,
   /* 207 "Multi-Status".        RFC4918. */
   MHD_HTTP_STATUS_MULTI_STATUS =                207
   ,
   /* 208 "Already Reported".    RFC5842. */
   MHD_HTTP_STATUS_ALREADY_REPORTED =            208
   ,
 
   /* 226 "IM Used".             RFC3229. */
   MHD_HTTP_STATUS_IM_USED =                     226
   ,
 
   /* 300 "Multiple Choices".    RFC9110, Section 15.4.1. */
   MHD_HTTP_STATUS_MULTIPLE_CHOICES =            300
   ,
   /* 301 "Moved Permanently".   RFC9110, Section 15.4.2. */
   MHD_HTTP_STATUS_MOVED_PERMANENTLY =           301
   ,
   /* 302 "Found".               RFC9110, Section 15.4.3. */
   MHD_HTTP_STATUS_FOUND =                       302
   ,
   /* 303 "See Other".           RFC9110, Section 15.4.4. */
   MHD_HTTP_STATUS_SEE_OTHER =                   303
   ,
   /* 304 "Not Modified".        RFC9110, Section 15.4.5. */
   MHD_HTTP_STATUS_NOT_MODIFIED =                304
   ,
   /* 305 "Use Proxy".           RFC9110, Section 15.4.6. */
   MHD_HTTP_STATUS_USE_PROXY =                   305
   ,
   /* 306 "Switch Proxy".        Not used! RFC9110, Section 15.4.7. */
   MHD_HTTP_STATUS_SWITCH_PROXY =                306
   ,
   /* 307 "Temporary Redirect".  RFC9110, Section 15.4.8. */
   MHD_HTTP_STATUS_TEMPORARY_REDIRECT =          307
   ,
   /* 308 "Permanent Redirect".  RFC9110, Section 15.4.9. */
   MHD_HTTP_STATUS_PERMANENT_REDIRECT =          308
   ,
 
   /* 400 "Bad Request".         RFC9110, Section 15.5.1. */
   MHD_HTTP_STATUS_BAD_REQUEST =                 400
   ,
   /* 401 "Unauthorized".        RFC9110, Section 15.5.2. */
   MHD_HTTP_STATUS_UNAUTHORIZED =                401
   ,
   /* 402 "Payment Required".    RFC9110, Section 15.5.3. */
   MHD_HTTP_STATUS_PAYMENT_REQUIRED =            402
   ,
   /* 403 "Forbidden".           RFC9110, Section 15.5.4. */
   MHD_HTTP_STATUS_FORBIDDEN =                   403
   ,
   /* 404 "Not Found".           RFC9110, Section 15.5.5. */
   MHD_HTTP_STATUS_NOT_FOUND =                   404
   ,
   /* 405 "Method Not Allowed".  RFC9110, Section 15.5.6. */
   MHD_HTTP_STATUS_METHOD_NOT_ALLOWED =          405
   ,
   /* 406 "Not Acceptable".      RFC9110, Section 15.5.7. */
   MHD_HTTP_STATUS_NOT_ACCEPTABLE =              406
   ,
   /* 407 "Proxy Authentication Required". RFC9110, Section 15.5.8. */
   MHD_HTTP_STATUS_PROXY_AUTHENTICATION_REQUIRED = 407
   ,
   /* 408 "Request Timeout".     RFC9110, Section 15.5.9. */
   MHD_HTTP_STATUS_REQUEST_TIMEOUT =             408
   ,
   /* 409 "Conflict".            RFC9110, Section 15.5.10. */
   MHD_HTTP_STATUS_CONFLICT =                    409
   ,
   /* 410 "Gone".                RFC9110, Section 15.5.11. */
   MHD_HTTP_STATUS_GONE =                        410
   ,
   /* 411 "Length Required".     RFC9110, Section 15.5.12. */
   MHD_HTTP_STATUS_LENGTH_REQUIRED =             411
   ,
   /* 412 "Precondition Failed". RFC9110, Section 15.5.13. */
   MHD_HTTP_STATUS_PRECONDITION_FAILED =         412
   ,
   /* 413 "Content Too Large".   RFC9110, Section 15.5.14. */
   MHD_HTTP_STATUS_CONTENT_TOO_LARGE =           413
   ,
   /* 414 "URI Too Long".        RFC9110, Section 15.5.15. */
   MHD_HTTP_STATUS_URI_TOO_LONG =                414
   ,
   /* 415 "Unsupported Media Type". RFC9110, Section 15.5.16. */
   MHD_HTTP_STATUS_UNSUPPORTED_MEDIA_TYPE =      415
   ,
   /* 416 "Range Not Satisfiable". RFC9110, Section 15.5.17. */
   MHD_HTTP_STATUS_RANGE_NOT_SATISFIABLE =       416
   ,
   /* 417 "Expectation Failed".  RFC9110, Section 15.5.18. */
   MHD_HTTP_STATUS_EXPECTATION_FAILED =          417
   ,
 
 
   /* 421 "Misdirected Request". RFC9110, Section 15.5.20. */
   MHD_HTTP_STATUS_MISDIRECTED_REQUEST =         421
   ,
   /* 422 "Unprocessable Content". RFC9110, Section 15.5.21. */
   MHD_HTTP_STATUS_UNPROCESSABLE_CONTENT =       422
   ,
   /* 423 "Locked".              RFC4918. */
   MHD_HTTP_STATUS_LOCKED =                      423
   ,
   /* 424 "Failed Dependency".   RFC4918. */
   MHD_HTTP_STATUS_FAILED_DEPENDENCY =           424
   ,
   /* 425 "Too Early".           RFC8470. */
   MHD_HTTP_STATUS_TOO_EARLY =                   425
   ,
   /* 426 "Upgrade Required".    RFC9110, Section 15.5.22. */
   MHD_HTTP_STATUS_UPGRADE_REQUIRED =            426
   ,
 
   /* 428 "Precondition Required". RFC6585. */
   MHD_HTTP_STATUS_PRECONDITION_REQUIRED =       428
   ,
   /* 429 "Too Many Requests".   RFC6585. */
   MHD_HTTP_STATUS_TOO_MANY_REQUESTS =           429
   ,
 
   /* 431 "Request Header Fields Too Large". RFC6585. */
   MHD_HTTP_STATUS_REQUEST_HEADER_FIELDS_TOO_LARGE = 431
   ,
 
   /* 451 "Unavailable For Legal Reasons". RFC7725. */
   MHD_HTTP_STATUS_UNAVAILABLE_FOR_LEGAL_REASONS = 451
   ,
 
   /* 500 "Internal Server Error". RFC9110, Section 15.6.1. */
   MHD_HTTP_STATUS_INTERNAL_SERVER_ERROR =       500
   ,
   /* 501 "Not Implemented".     RFC9110, Section 15.6.2. */
   MHD_HTTP_STATUS_NOT_IMPLEMENTED =             501
   ,
   /* 502 "Bad Gateway".         RFC9110, Section 15.6.3. */
   MHD_HTTP_STATUS_BAD_GATEWAY =                 502
   ,
   /* 503 "Service Unavailable". RFC9110, Section 15.6.4. */
   MHD_HTTP_STATUS_SERVICE_UNAVAILABLE =         503
   ,
   /* 504 "Gateway Timeout".     RFC9110, Section 15.6.5. */
   MHD_HTTP_STATUS_GATEWAY_TIMEOUT =             504
   ,
   /* 505 "HTTP Version Not Supported". RFC9110, Section 15.6.6. */
   MHD_HTTP_STATUS_HTTP_VERSION_NOT_SUPPORTED =  505
   ,
   /* 506 "Variant Also Negotiates". RFC2295. */
   MHD_HTTP_STATUS_VARIANT_ALSO_NEGOTIATES =     506
   ,
   /* 507 "Insufficient Storage". RFC4918. */
   MHD_HTTP_STATUS_INSUFFICIENT_STORAGE =        507
   ,
   /* 508 "Loop Detected".       RFC5842. */
   MHD_HTTP_STATUS_LOOP_DETECTED =               508
   ,
 
   /* 510 "Not Extended".        (OBSOLETED) RFC2774; status-change-http-experiments-to-historic. */
   MHD_HTTP_STATUS_NOT_EXTENDED =                510
   ,
   /* 511 "Network Authentication Required". RFC6585. */
   MHD_HTTP_STATUS_NETWORK_AUTHENTICATION_REQUIRED = 511
   ,
 
 
   /* Not registered non-standard codes */
   /* 449 "Reply With".          MS IIS extension. */
   MHD_HTTP_STATUS_RETRY_WITH =                  449
   ,
 
   /* 450 "Blocked by Windows Parental Controls". MS extension. */
   MHD_HTTP_STATUS_BLOCKED_BY_WINDOWS_PARENTAL_CONTROLS = 450
   ,
 
   /* 509 "Bandwidth Limit Exceeded". Apache extension. */
   MHD_HTTP_STATUS_BANDWIDTH_LIMIT_EXCEEDED =    509
 };
 
 
 /**
  * Returns the string status for a response code.
  *
  * This function works for @b HTTP status code, not for @b MHD error codes/
  * @param code the HTTP code to get text representation for
  * @return the pointer to the text representation,
  *         NULL if HTTP status code in not known.
  */
 MHD_EXTERN_ const struct MHD_String *
 MHD_HTTP_status_code_to_string (enum MHD_HTTP_StatusCode code)
 MHD_FN_CONST_;
 
 /**
  * Get the pointer to the C string for the HTTP response code, never NULL.
  */
 #define MHD_HTTP_status_code_to_string_lazy(code) \
         (MHD_HTTP_status_code_to_string ((code)) ? \
          ((MHD_HTTP_status_code_to_string (code))->cstr) : ("[No status]") )
 
 
 /** @} */ /* end of group httpcode */
 
 #ifndef MHD_HTTP_PROTOCOL_VER_DEFINED
 
 /**
  * @brief HTTP protocol versions
  * @defgroup versions HTTP versions
  * @{
  */
 enum MHD_FIXED_ENUM_MHD_SET_ MHD_HTTP_ProtocolVersion
 {
   MHD_HTTP_VERSION_INVALID = 0
   ,
   MHD_HTTP_VERSION_1_0 = 1
   ,
   MHD_HTTP_VERSION_1_1 = 2
   ,
   MHD_HTTP_VERSION_2 = 3
   ,
   MHD_HTTP_VERSION_3 = 4
   ,
   MHD_HTTP_VERSION_FUTURE = 255
 };
 
 #define MHD_HTTP_PROTOCOL_VER_DEFINED 1
 #endif /* ! MHD_HTTP_PROTOCOL_VER_DEFINED */
 
 /**
  * Return the string representation of the requested HTTP version.
  * Note: this is suitable mainly for logging and similar proposes as
  * HTTP/2 (and later) is not used inside the HTTP protocol.
  * @param pv the protocol version
  * @return the string representation of the protocol version,
  *         NULL for invalid values
  */
 MHD_EXTERN_ const struct MHD_String *
 MHD_protocol_version_to_string (enum MHD_HTTP_ProtocolVersion pv)
 MHD_FN_CONST_;
 
 /**
  * HTTP/1.0 identification string
  */
 #define MHD_HTTP_VERSION_1_0_STR "HTTP/1.0"
 /**
  * HTTP/1.1 identification string
  */
 #define MHD_HTTP_VERSION_1_1_STR "HTTP/1.1"
 /**
  * HTTP/2 identification string.
  * Not used by the HTTP protocol (except non-TLS handshake), useful for logs and
  * similar proposes.
  */
 #define MHD_HTTP_VERSION_2_STR "HTTP/2"
 /**
  * HTTP/3 identification string.
  * Not used by the HTTP protocol, useful for logs and similar proposes.
  */
 #define MHD_HTTP_VERSION_3_STR "HTTP/3"
 
 /** @} */ /* end of group versions */
 
 
 /**
  * Resume handling of network data for suspended request.
  * It is safe to resume a suspended request at any time.
  * Calling this function on a request that was not previously suspended will
  * result in undefined behaviour.
  *
  * @param[in,out] request the request to resume
  */
 MHD_EXTERN_ void
 MHD_request_resume (struct MHD_Request *request)
 MHD_FN_PAR_NONNULL_ALL_;
 
 
 /* ************** Action and Response manipulation functions **************** */
 
 /**
  * @defgroup response Response objects control
  */
 
 
 /**
  * Name with value pair as C strings
  */
 struct MHD_NameValueCStr
 {
   /**
    * The name (key) of the field.
    * Must never be NULL.
    * Some types (kinds) allow empty strings.
    */
   const char *name;
   /**
    * The value of the field.
    * Some types (kinds) allow absence of the value. The absence is indicated
    * by NULL pointer.
    */
   const char *value;
 };
 
 /**
  * Data transmitted in response to an HTTP request.
  * Usually the final action taken in response to
  * receiving a request.
  */
 struct MHD_Response;
 
 
 /**
  * Suspend handling of network data for a given request.  This can
  * be used to dequeue a request from MHD's event loop for a while.
  *
  * Suspended requests continue to count against the total number of
  * requests allowed (per daemon, as well as per IP, if such limits
  * are set).  Suspended requests will NOT time out; timeouts will
  * restart when the request handling is resumed.  While a
  * request is suspended, MHD may not detect disconnects by the
  * client.
  *
  * At most one action can be created for any request.
  *
  * @param[in,out] request the request for which the action is generated
  * @return action to cause a request to be suspended,
  *         NULL if any action has been already created for the @a request
  * @ingroup action
  */
 MHD_EXTERN_ const struct MHD_Action *
 MHD_action_suspend (struct MHD_Request *request)
 MHD_FN_PAR_NONNULL_ALL_;
 
 
 /**
  * Converts a @a response to an action.  If #MHD_R_O_REUSABLE
  * is not set, the reference to the @a response is consumed
  * by the conversion. If #MHD_R_O_REUSABLE is #MHD_YES,
  * then the @a response can be used again to create actions in
  * the future.
  * However, the @a response is frozen by this step and
  * must no longer be modified (i.e. by setting headers).
  *
  * At most one action can be created for any request.
  *
  * @param request the request to create the action for
  * @param[in] response the response to convert,
  *                     if NULL then this function is equivalent to
  *                     #MHD_action_abort_connection() call
  * @return pointer to the action, the action must be consumed
  *         otherwise response object may leak;
  *         NULL if failed (no memory) or if any action has been already
  *         created for the @a request;
  *         when failed the response object is consumed and need not
  *         to be "destroyed"
  * @ingroup action
  */
 MHD_EXTERN_ const struct MHD_Action *
 MHD_action_from_response (struct MHD_Request *MHD_RESTRICT request,
                           struct MHD_Response *MHD_RESTRICT response)
 MHD_FN_PAR_NONNULL_ (1);
 
 
 /**
  * Action telling MHD to close the connection hard
  * (kind-of breaking HTTP specification).
  *
  * @param req the request to make an action
  * @return action operation, always NULL
  * @ingroup action
  */
 #define MHD_action_abort_request(req) \
         MHD_STATIC_CAST_ (const struct MHD_Action *, NULL)
 
 
 /**
  * Set the requested options for the response.
  *
  * If any option fail other options may be or may be not applied.
  * @param response the response to set the options
  * @param[in] options the pointer to the array with the options;
  *                    the array processing stops at the first ::MHD_D_O_END
  *                    option, but not later than after processing
  *                    @a options_max_num entries
  * @param options_max_num the maximum number of entries in the @a options,
  *                        use #MHD_OPTIONS_ARRAY_MAX_SIZE if options processing
  *                        must stop only at zero-termination option
  * @return ::MHD_SC_OK on success,
  *         error code otherwise
  */
 MHD_EXTERN_ enum MHD_StatusCode
 MHD_response_set_options (
   struct MHD_Response *MHD_RESTRICT response,
   const struct MHD_ResponseOptionAndValue *MHD_RESTRICT options,
   size_t options_max_num)
 MHD_FN_PAR_NONNULL_ALL_;
 
 
 /**
  * Set the requested single option for the response.
  *
  * @param response the response to set the option
  * @param[in] option_ptr the pointer to the option
  * @return ::MHD_SC_OK on success,
  *         error code otherwise
  * @ingroup response
  */
 #define MHD_response_set_option(response,option_ptr) \
         MHD_response_set_options (response,option_ptr,1)
 
 
 /* *INDENT-OFF* */
 #ifdef MHD_USE_VARARG_MACROS
 MHD_NOWARN_VARIADIC_MACROS_
 #  if defined(MHD_USE_COMPOUND_LITERALS) && \
   defined(MHD_USE_COMP_LIT_FUNC_PARAMS)
 /**
  * Set the requested options for the response.
  *
  * If any option fail other options may be or may be not applied.
  *
  * It should be used with helpers that creates required options, for example:
  *
  * MHD_RESPONE_SET_OPTIONS(d, MHD_R_OPTION_REUSABLE(MHD_YES),
  *                         MHD_R_OPTION_TERMINATION_CALLBACK(func, cls))
  *
  * @param response the response to set the option
  * @param ... the list of the options, each option must be created
  *            by helpers MHD_RESPONSE_OPTION_NameOfOption(option_value)
  * @return ::MHD_SC_OK on success,
  *         error code otherwise
  */
 #    define MHD_RESPONSE_SET_OPTIONS(response,...)              \
         MHD_NOWARN_COMPOUND_LITERALS_                           \
         MHD_response_set_options (                              \
           response,                                             \
           ((const struct MHD_ResponseOptionAndValue[])          \
            {__VA_ARGS__, MHD_R_OPTION_TERMINATE ()}),           \
           MHD_OPTIONS_ARRAY_MAX_SIZE)                           \
         MHD_RESTORE_WARN_COMPOUND_LITERALS_
 #  elif defined(MHD_USE_CPP_INIT_LIST)
 MHD_C_DECLRATIONS_FINISH_HERE_
 #    include <vector>
 MHD_C_DECLRATIONS_START_HERE_
 /**
  * Set the requested options for the response.
  *
  * If any option fail other options may be or may be not applied.
  *
  * It should be used with helpers that creates required options, for example:
  *
  * MHD_RESPONE_SET_OPTIONS(d, MHD_R_OPTION_REUSABLE(MHD_YES),
  *                         MHD_R_OPTION_TERMINATION_CALLBACK(func, cls))
  *
  * @param response the response to set the option
  * @param ... the list of the options, each option must be created
  *            by helpers MHD_RESPONSE_OPTION_NameOfOption(option_value)
  * @return ::MHD_SC_OK on success,
  *         error code otherwise
  */
 #    define MHD_RESPONSE_SET_OPTIONS(response,...)              \
         MHD_NOWARN_CPP_INIT_LIST_                               \
         MHD_response_set_options (                              \
           response,                                             \
           (std::vector<struct MHD_ResponseOptionAndValue>       \
            {__VA_ARGS__,MHD_R_OPTION_TERMINATE ()}).data (),    \
           MHD_OPTIONS_ARRAY_MAX_SIZE)                           \
         MHD_RESTORE_WARN_CPP_INIT_LIST_
 #  endif
 MHD_RESTORE_WARN_VARIADIC_MACROS_
 #endif /* MHD_USE_VARARG_MACROS && MHD_USE_COMP_LIT_FUNC_PARAMS */
 /* *INDENT-ON* */
 
 #ifndef MHD_FREECALLBACK_DEFINED
 
 /**
  * This method is called by libmicrohttpd when response with dynamic content
  * is being destroyed.  It should be used to free resources associated
  * with the dynamic content.
  *
  * @param[in] free_cls closure
  * @ingroup response
  */
 typedef void
 (*MHD_FreeCallback) (void *free_cls);
 
 #define MHD_FREECALLBACK_DEFINED 1
 #endif /* ! MHD_FREECALLBACK_DEFINED */
 #ifndef MHD_DYNCONTENTZCIOVEC_DEFINED
 
 
 /**
  * Structure for iov type of the response.
  * Used for zero-copy response content data.
  */
 struct MHD_DynContentZCIoVec
 {
   /**
    * The number of elements in @a iov
    */
   unsigned int iov_count;
   /**
    * The pointer to the array with @a iov_count elements.
    */
   const struct MHD_IoVec *iov;
   /**
    * The callback to free resources.
    * It is called once the full array of iov elements is sent.
    * No callback is called if NULL.
    */
   MHD_FreeCallback iov_fcb;
   /**
    * The parameter for @a iov_fcb
    */
   void *iov_fcb_cls;
 };
 
 #define MHD_DYNCONTENTZCIOVEC_DEFINED 1
 #endif /* ! MHD_DYNCONTENTZCIOVEC_DEFINED */
 
 /**
  * The action type returned by Dynamic Content Creator callback
  */
 struct MHD_DynamicContentCreatorAction;
 
 /**
  * The context used for Dynamic Content Creator callback
  */
 struct MHD_DynamicContentCreatorContext;
 
 
 /**
  * Create "continue processing" action with optional chunk-extension.
  * The data is provided in the buffer and/or in the zero-copy @a iov_data.
  *
  * If data is provided both in the buffer and @a ivo_data then
  * data in the buffer sent first, following the iov data.
  * The total size of the data in the buffer and in @a iov_data must
  * be non-zero.
  * If response content size is known and total size of content provided earlier
  * for this request combined with the size provided by this action is larger
  * then known response content size, then NULL is returned.
  *
  * At most one DCC action can be created for one content callback.
  *
  * @param[in,out] ctx the pointer the context as provided to the callback
  * @param data_size the amount of the data placed to the provided buffer,
  *                  cannot be larger than provided buffer size,
  *                  must be non-zero if @a iov_data is NULL or has no data,
  * @param iov_data the optional pointer to the iov data,
  *                 must not be NULL and have non-zero size data if @a data_size
  *                 is zero,
  * @param chunk_ext the optional pointer to chunk extension string,
  *                  can be NULL to not use chunk extension,
  *                  ignored if chunked encoding is not used
  * @return the pointer to the action if succeed,
  *         NULL (equivalent of MHD_DCC_action_abort())in case of any error
  */
 MHD_EXTERN_ const struct MHD_DynamicContentCreatorAction *
 MHD_DCC_action_continue_zc (
   struct MHD_DynamicContentCreatorContext *ctx,
   size_t data_size,
   const struct MHD_DynContentZCIoVec *iov_data,
   const char *MHD_RESTRICT chunk_ext)
 MHD_FN_PAR_NONNULL_ (1)
 MHD_FN_PAR_CSTR_ (4);
 
 
 /**
  * Create "continue processing" action with optional chunk-extension.
  * The data is provided in the buffer.
  *
  * At most one DCC action can be created for one content callback.
  *
  * @param[in,out] ctx the pointer the context as provided to the callback
  * @param data_size the amount of the data placed to the provided buffer (not @a iov_data),
  *                  cannot be larger than provided buffer size,
  *                  must be non-zero.
  * @param chunk_ext the optional pointer to chunk extension string,
  *                  can be NULL to not use chunk extension,
  *                  ignored if chunked encoding is not used
  * @return the pointer to the action if succeed,
  *         NULL (equivalent of MHD_DCC_action_abort())in case of any error
  */
 #define MHD_DCC_action_continue_ce(ctx,data_size,chunk_ext) \
         MHD_DCC_action_continue_zc ((ctx), (data_size), NULL, (chunk_ext))
 
 
 /**
  * Create "continue processing" action, the data is provided in the buffer.
  *
  * At most one DCC action can be created for one content callback.
  *
  * @param[in,out] ctx the pointer the context as provided to the callback
  * @param data_size the amount of the data placed to the provided buffer;
  *                  cannot be larger than provided buffer size,
  *                  must be non-zero.
  *
  * @return the pointer to the action if succeed,
  *         NULL (equivalent of MHD_DCC_action_abort())in case of any error
  */
 #define MHD_DCC_action_continue(ctx,data_size) \
         MHD_DCC_action_continue_ce ((ctx), (data_size), NULL)
 
 
 /**
  * Create "finished" action with optional footers.
  * If function failed for any reason, the action is automatically
  * set to "stop with error".
  *
  * At most one DCC action can be created for one content callback.
  *
  * @param[in,out] ctx the pointer the context as provided to the callback
  * @param num_footers number of elements in the @a footers array,
  *                    must be zero if @a footers is NULL
  * @param footers the optional pointer to the array of the footers (the strings
  *                are copied and does not need to be valid after return from
  *                this function),
  *                can be NULL if @a num_footers is zero
  * @return the pointer to the action if succeed,
  *         NULL (equivalent of MHD_DCC_action_abort())in case of any error
  */
 MHD_EXTERN_ const struct MHD_DynamicContentCreatorAction *
 MHD_DCC_action_finish_with_footer (
   struct MHD_DynamicContentCreatorContext *ctx,
   size_t num_footers,
   const struct MHD_NameValueCStr *MHD_RESTRICT footers)
 MHD_FN_PAR_NONNULL_ (1);
 
 
 /**
  * Create "finished" action.
  * If function failed for any reason, the action is automatically
  * set to "stop with error".
  *
  * At most one DCC action can be created for one content callback.
  *
  * @param[in,out] ctx the pointer the context as provided to the callback
  * @return the pointer to the action if succeed,
  *         NULL (equivalent of MHD_DCC_action_abort())in case of any error
  */
 #define MHD_DCC_action_finish(ctx) \
         MHD_DCC_action_finish_with_footer ((ctx), 0, NULL)
 
 
 /**
  * Create "suspend" action.
  * If function failed for any reason, the action is automatically
  * set to "stop with error".
  *
  * At most one DCC action can be created for one content callback.
  *
  * @param[in,out] ctx the pointer the context as provided to the callback
  * @return the pointer to the action if succeed,
  *         NULL (equivalent of MHD_DCC_action_abort())in case of any error
  */
 MHD_EXTERN_ const struct MHD_DynamicContentCreatorAction *
 MHD_DCC_action_suspend (struct MHD_DynamicContentCreatorContext *ctx)
 MHD_FN_PAR_NONNULL_ (1);
 
 /**
  * Create "stop with error" action.
  * @param[in,out] ctx the pointer the context as provided to the callback
  * @return always NULL (the action "stop with error")
  */
 #define MHD_DCC_action_abort(ctx) \
         MHD_STATIC_CAST_ (const struct MHD_DynamicContentCreatorAction *, NULL)
 
 /**
  * Callback used by libmicrohttpd in order to obtain content.  The
  * callback is to copy at most @a max bytes of content into @a buf or
  * provide zero-copy data for #MHD_DCC_action_continue_zc().
  *
  * @param dyn_cont_cls closure argument to the callback
  * @param ctx the context to produce the action to return,
  *            the pointer is only valid until the callback returns
  * @param pos position in the datastream to access;
  *        note that if a `struct MHD_Response` object is re-used,
  *        it is possible for the same content reader to
  *        be queried multiple times for the same data;
  *        however, if a `struct MHD_Response` is not re-used,
  *        libmicrohttpd guarantees that "pos" will be
  *        the sum of all data sizes provided by this callback
  * @param[out] buf where to copy the data
  * @param max maximum number of bytes to copy to @a buf (size of @a buf),
               if the size of the content of the response is known then size
               of the buffer is never larger than amount of the content left
  * @return action to use,
  *         NULL in case of any error (the response will be aborted)
  */
 typedef const struct MHD_DynamicContentCreatorAction *
 (MHD_FN_PAR_NONNULL_ (2) MHD_FN_PAR_NONNULL_ (4)
  *MHD_DynamicContentCreator)(void *dyn_cont_cls,
                              struct MHD_DynamicContentCreatorContext *ctx,
                              uint_fast64_t pos,
                              void *buf,
                              size_t max);
 
 
 /**
  * Create a response.  The response object can be extended with
  * header information.
  *
  * @param sc status code to return
  * @param size size of the data portion of the response, #MHD_SIZE_UNKNOWN for unknown
  * @param dyn_cont callback to use to obtain response data
  * @param dyn_cont_cls extra argument to @a crc
  * @param dyn_cont_fc callback to call to free @a dyn_cont_cls resources
  * @return NULL on error (i.e. invalid arguments, out of memory)
  * FIXME: Call free callback on error?
  * @ingroup response
  */
 MHD_EXTERN_ struct MHD_Response *
 MHD_response_from_callback (enum MHD_HTTP_StatusCode sc,
                             uint_fast64_t size,
                             MHD_DynamicContentCreator dyn_cont,
                             void *dyn_cont_cls,
                             MHD_FreeCallback dyn_cont_fc);
 
 
 /**
  * Create a response object.  The response object can be extended with
  * header information.
  *
  * @param sc status code to use for the response;
  *           #MHD_HTTP_STATUS_NO_CONTENT is only valid if @a size is 0;
  * @param buffer_size the size of the data portion of the response
  * @param buffer the @a size bytes containing the response's data portion,
  *               needs to be valid while the response is used
  * @param free_cb the callback to free any allocated data, called
  *                when response is being destroyed, can be NULL
  *                to skip the free/cleanup callback;
  * @param free_cb_cls the parameter for @a free_cb
  * @return NULL on error (i.e. invalid arguments, out of memory)
  *   on error, @a free_cb is NOT called
  * @ingroup response
  */
 MHD_EXTERN_ struct MHD_Response *
 MHD_response_from_buffer (
   enum MHD_HTTP_StatusCode sc,
   size_t buffer_size,
   const char *buffer,
   MHD_FreeCallback free_cb,
   void *free_cb_cls)
 MHD_FN_PAR_IN_SIZE_ (3,2);
 
 
 /**
  * Create a response object with body that is a
  * statically allocated buffer that never needs to
  * be freed as its lifetime exceeds that of the
  * daemon.
  *
  * The response object can be extended with header information and then be used
  * any number of times.
  * @param sc status code to use for the response
  * @param len number of bytes in @a buf
  * @param buf buffer with response payload
  */
 #define MHD_response_from_buffer_static(sc, len, buf)       \
         MHD_response_from_buffer (sc, len, buf, NULL, NULL)
 
 
 /**
  * Create a response object with empty (zero size) body.
  *
  * The response object can be extended with header information and then be used
  * any number of times.
  * @param sc status code to use for the response
  */
 #define MHD_response_from_empty(sc) \
         MHD_response_from_buffer_static (sc, 0, "")
 
 
 /**
  * Create a response object.  The response object can be extended with
  * header information.
  *
  * @param sc status code to use for the response
  * @param buffer_size the size of the data portion of the response
  * @param buffer the @a size bytes containing the response's data portion,
  *               an internal copy will be made, there is no need to
  *               keep this data after return from this function
  * @return NULL on error (i.e. invalid arguments, out of memory)
  * FIXME: Call free callback on error?
  * @ingroup response
  */
 MHD_EXTERN_ struct MHD_Response *
 MHD_response_from_buffer_copy (
   enum MHD_HTTP_StatusCode sc,
   size_t buffer_size,
   const char buffer[MHD_FN_PAR_DYN_ARR_SIZE_ (buffer_size)])
 MHD_FN_PAR_IN_SIZE_ (3,2);
 
 
 /**
  * I/O vector type. Provided for use with #MHD_response_from_iovec().
  * @ingroup response
  */
 struct MHD_IoVec
 {
   /**
    * The pointer to the memory region for I/O.
    */
   const void *iov_base;
 
   /**
    * The size in bytes of the memory region for I/O.
    */
   size_t iov_len;
 };
 
 
 /**
  * Create a response object with an array of memory buffers
  * used as the response body.
  *
  * The response object can be extended with header information.
  *
  * If response object is used to answer HEAD request then the body
  * of the response is not used, while all headers (including automatic
  * headers) are used.
  *
  * @param sc status code to use for the response
  * @param iov_count the number of elements in @a iov
  * @param iov the array for response data buffers, an internal copy of this
  *        will be made
  * @param free_cb the callback to clean up any data associated with @a iov when
  *        the response is destroyed.
  * @param free_cb_cls the argument passed to @a free_cb
  * @return NULL on error (i.e. invalid arguments, out of memory)
  * FIXME: Call free callback on error?
  * @ingroup response
  */
 MHD_EXTERN_ struct MHD_Response *
 MHD_response_from_iovec (
   enum MHD_HTTP_StatusCode sc,
   unsigned int iov_count,
   const struct MHD_IoVec iov[MHD_FN_PAR_DYN_ARR_SIZE_ (iov_count)],
   MHD_FreeCallback free_cb,
   void *free_cb_cls);
 
 
 /**
  * Create a response object based on an @a fd from which
  * data is read.  The response object can be extended with
  * header information.
  *
  * @param sc status code to return
  * @param fd file descriptor referring to a file on disk with the
  *        data; will be closed when response is destroyed;
  *        fd should be in 'blocking' mode
  * @param offset offset to start reading from in the file;
  *        reading file beyond 2 GiB may be not supported by OS or
  *        MHD build; see #MHD_LIB_INFO_FIXED_HAS_LARGE_FILE
  * @param size size of the data portion of the response;
  *        sizes larger than 2 GiB may be not supported by OS or
  *        MHD build; see #MHD_LIB_INFO_FIXED_HAS_LARGE_FILE
  * @return NULL on error (i.e. invalid arguments, out of memory)
  * FIXME: Close FD on error?
  * @ingroup response
  */
 MHD_EXTERN_ struct MHD_Response *
 MHD_response_from_fd (enum MHD_HTTP_StatusCode sc,
                       int fd,
                       uint_fast64_t offset,
                       uint_fast64_t size)
 MHD_FN_PAR_FD_READ_ (2);
 
 /**
  * Create a response object with the response body created by reading
  * the provided pipe.
  *
  * The response object can be extended with header information and
  * then be used ONLY ONCE.
  *
  * If response object is used to answer HEAD request then the body
  * of the response is not used, while all headers (including automatic
  * headers) are used.
  *
  * @param sc status code to use for the response
  * @param fd file descriptor referring to a read-end of a pipe with the
  *        data; will be closed when response is destroyed;
  *        fd should be in 'blocking' mode
  * @return NULL on error (i.e. invalid arguments, out of memory)
  * FIXME: Close pipe FD on error?
  * @ingroup response
  */
 MHD_EXTERN_ struct MHD_Response *
 MHD_response_from_pipe (enum MHD_HTTP_StatusCode sc,
                         int fd)
 MHD_FN_PAR_FD_READ_ (2);
 
 
 /**
  * Destroy response.
  * Should be called if response was created but not consumed.
  * Also must be called if response has #MHD_R_O_REUSABLE set.
  * The actual destroy can be happen later, if the response
  * is still being used in any request.
  * The function does not block.
  *
  * @param[in] response the response to destroy
  * @ingroup response
  */
 MHD_EXTERN_ void
 MHD_response_destroy (struct MHD_Response *response)
 MHD_FN_PAR_NONNULL_ (1);
 
 
 /**
  * Add a header line to the response.
  *
  * @param response response to add a header to, NULL is tolerated
  * @param name the name of the header to add,
  *             an internal copy of the string will be made
  * @param value the value of the header to add,
  *              an internal copy of the string will be made
  * @return #MHD_SC_OK on success,
  *         error code otherwise
  * @ingroup response
  */
 MHD_EXTERN_ enum MHD_StatusCode
 MHD_response_add_header (struct MHD_Response *MHD_RESTRICT response,
                          const char *MHD_RESTRICT name,
                          const char *MHD_RESTRICT value)
 MHD_FN_PAR_NONNULL_ (2) MHD_FN_PAR_CSTR_ (2)
 MHD_FN_PAR_NONNULL_ (3) MHD_FN_PAR_CSTR_ (3);
 
 
 /**
  * Add a header with predefined (standard) name to the response.
  *
  * @param response response to add a header to
  * @param stk the code of the predefined header
  * @param content the value of the header to add,
  *              an internal copy of the string will be made
  * @return #MHD_SC_OK on success,
  *         error code otherwise
  * @ingroup response
  */
 MHD_EXTERN_ enum MHD_StatusCode
 MHD_response_add_predef_header (struct MHD_Response *MHD_RESTRICT response,
                                 enum MHD_PredefinedHeader stk,
                                 const char *MHD_RESTRICT content)
 MHD_FN_PAR_NONNULL_ (1)
 MHD_FN_PAR_NONNULL_ (3) MHD_FN_PAR_CSTR_ (3);
 
 
 /* ************ (b) Upload and PostProcessor functions ********************** */
 
 
 /**
  * Suspend handling of network data for a given request.  This can
  * be used to dequeue a request from MHD's event loop for a while.
  *
  * Suspended requests continue to count against the total number of
  * requests allowed (per daemon, as well as per IP, if such limits
  * are set).  Suspended requests will NOT time out; timeouts will
  * restart when the request handling is resumed.  While a
  * request is suspended, MHD may not detect disconnects by the
  * client.
  *
  * At most one upload action can be created for one upload callback.
  *
  * @param[in,out] request the request for which the action is generated
  * @return action to cause a request to be suspended,
  *         NULL if any action has been already created for the @a request
  * @ingroup action
  */
 MHD_EXTERN_ const struct MHD_UploadAction *
 MHD_upload_action_suspend (struct MHD_Request *request)
 MHD_FN_PAR_NONNULL_ALL_;
 
 /**
  * Converts a @a response to an action.  If #MHD_R_O_REUSABLE
  * is not set, the reference to the @a response is consumed
  * by the conversion. If #MHD_R_O_REUSABLE is #MHD_YES,
  * then the @a response can be used again to create actions in
  * the future.
  * However, the @a response is frozen by this step and
  * must no longer be modified (i.e. by setting headers).
  *
  * At most one upload action can be created for one upload callback.
  *
  * @param request the request to create the action for
  * @param[in] response the response to convert,
  *                     if NULL then this function is equivalent to
  *                     #MHD_upload_action_abort_request() call
  * @return pointer to the action, the action must be consumed
  *         otherwise response object may leak;
  *         NULL if failed (no memory) or if any action has been already
  *         created for the @a request;
  *         when failed the response object is consumed and need not
  *         to be "destroyed"
  * @ingroup action
  */
 MHD_EXTERN_ const struct MHD_UploadAction *
 MHD_upload_action_from_response (struct MHD_Request *MHD_RESTRICT request,
                                  struct MHD_Response *MHD_RESTRICT response)
 MHD_FN_PAR_NONNULL_ (1);
 
 /**
  * Action telling MHD to continue processing the upload.
  * Valid only for incremental upload processing.
  * Works as #MHD_upload_action_abort_request() if used for full upload callback
  * or for the final (with zero data) incremental callback.
  *
  * At most one upload action can be created for one upload callback.
  *
  * @param request the request to make an action
  * @return action operation,
  *         NULL if any action has been already created for the @a request
  * @ingroup action
  */
 MHD_EXTERN_ const struct MHD_UploadAction *
 MHD_upload_action_continue (struct MHD_Request *request)
 MHD_FN_PAR_NONNULL_ (1);
 
 
 /**
  * Action telling MHD to close the connection hard
  * (kind-of breaking HTTP specification).
  *
  * @param req the request to make an action
  * @return action operation, always NULL
  * @ingroup action
  */
 #define MHD_upload_action_abort_request(req) \
         MHD_STATIC_CAST_ (const struct MHD_UploadAction *, NULL)
 
 #ifndef MHD_UPLOADCALLBACK_DEFINED
 
 /**
  * Function to process data uploaded by a client.
  *
  * @param upload_cls the argument given together with the function
  *                   pointer when the handler was registered with MHD
  * @param request the request is being processed
  * @param content_data_size the size of the @a content_data,
  *                          zero when all data have been processed
  * @param[in] content_data the uploaded content data,
  *                         may be modified in the callback,
  *                         valid only until return from the callback,
  *                         NULL when all data have been processed
  * @return action specifying how to proceed:
  *         #MHD_upload_action_continue() to continue upload (for incremental
  *         upload processing only),
  *         #MHD_upload_action_suspend() to stop reading the upload until
  *         the request is resumed,
  *         #MHD_upload_action_abort_request() to close the socket,
  *         or a response to discard the rest of the upload and transmit
  *         the response
  * @ingroup action
  */
 typedef const struct MHD_UploadAction *
 (MHD_FN_PAR_NONNULL_ (2)  MHD_FN_PAR_INOUT_SIZE_ (4,3)
  *MHD_UploadCallback)(void *upload_cls,
                       struct MHD_Request *request,
                       size_t content_data_size,
                       void *content_data);
 
 #define MHD_UPLOADCALLBACK_DEFINED 1
 #endif /* ! MHD_UPLOADCALLBACK_DEFINED */
 
 /**
  * Create an action that handles an upload.
  *
  * If @a uc_inc is NULL and upload cannot fit the allocated buffer
  * then request is aborted without response.
  *
  * At most one action can be created for any request.
  *
  * @param request the request to create action for
  * @param large_buffer_size how large should the upload buffer be.
  *                          May allocate memory from the shared "large"
  *                          memory pool if necessary and non-zero is given.
  *                          Must be zero if @a uc_full is NULL.
  * @param uc_full the function to call when complete upload
  *                is received (only if fit @a upload_buffer_size),
  *                can be NULL if uc_inc is not NULL,
  *                must be NULL is @a upload_buffer_size is zero.
  * @param uc_full_cls closure for @a uc_full
  * @param uc_inc the function to incrementally process the upload data
  *               if the upload if larger than @a upload_buffer_size or
  *               @a upload_buffer_size cannot be allocated or
  *               @a uc_full is NULL,
  *               can be NULL if uc_full is not NULL
  * @param uc_inc_cls closure for @a uc_inc
  * @return NULL on error (out of memory, invalid parameters)
  * @return pointer to the action,
  *         NULL if failed (no memory) or if any action has been already
  *         created for the @a request.
  * @sa #MHD_D_OPTION_LARGE_POOL_SIZE()
  * @ingroup action
  */
 MHD_EXTERN_ const struct MHD_Action *
 MHD_action_process_upload (
   struct MHD_Request *request,
   size_t large_buffer_size,
   MHD_UploadCallback uc_full,
   void *uc_full_cls,
   MHD_UploadCallback uc_inc,
   void *uc_inc_cls)
 MHD_FN_PAR_NONNULL_ (1);
 
 /**
  * Create an action that handles an upload as full upload data.
  *
  * @param request the request to create action for
  * @param buff_size how large should the upload buffer be. May allocate memory
  *                  from the large memory pool if necessary. Must not be zero.
  * @param uc the function to call when complete upload
  *           is received (only if fit @a upload_buffer_size)
  * @param uc_cls closure for @a uc
  * @return NULL on error (out of memory. both @a uc is NULL)
  * @ingroup action
  */
 #define MHD_action_process_upload_full(request,buff_size,uc,uc_cls) \
         MHD_action_process_upload (request, buff_size, uc, uc_cls, NULL, NULL)
 
 /**
  * Create an action that handles an upload incrementally.
  *
  * @param request the request to create action for
  * @param uc the function to incrementally process the upload data
  * @param uc_cls closure for @a uc
  * @return NULL on error (out of memory. both @a uc is NULL)
  * @ingroup action
  */
 #define MHD_action_process_upload_inc(request,uc,uc_cls) \
         MHD_action_process_upload (request, 0, NULL, NULL, uc, uc_cls)
 
 #ifndef MHD_POST_PARSE_RESULT_DEFINED
 
 /**
  * The result of POST data parsing
  */
 enum MHD_FIXED_ENUM_MHD_SET_ MHD_PostParseResult
 {
   /**
    * The POST data parsed successfully and completely.
    */
   MHD_POST_PARSE_RES_OK = 0
   ,
   /**
    * The POST request has no content or zero-length content.
    */
   MHD_POST_PARSE_RES_REQUEST_EMPTY = 1
   ,
   /**
    * The POST data parsed successfully, but has missing or incorrect
    * termination.
    * The last parsed field may have incorrect data.
    */
   MHD_POST_PARSE_RES_OK_BAD_TERMINATION = 2
   ,
   /**
    * Parsing of the POST data is incomplete because client used incorrect
    * format of POST encoding.
    * The last parsed field may have incorrect data.
    * Some POST data is available or has been provided via callback.
    */
   MHD_POST_PARSE_RES_PARTIAL_INVALID_POST_FORMAT = 3
   ,
   /**
    * The POST data cannot be parsed completely because the stream has
    * no free pool memory.
    * Some POST data may be parsed.
    */
   MHD_POST_PARSE_RES_FAILED_NO_POOL_MEM = 60
   ,
   /**
    * The POST data cannot be parsed completely because no "large shared buffer"
    * space is available.
    * Some POST data may be parsed.
    */
   MHD_POST_PARSE_RES_FAILED_NO_LARGE_BUF_MEM = 61
   ,
   /**
    * The POST data cannot be parsed because 'Content-Type:' is unknown.
    */
   MHD_POST_PARSE_RES_FAILED_UNKNOWN_CNTN_TYPE = 80
   ,
   /**
    * The POST data cannot be parsed because 'Content-Type:' header is not set.
    */
   MHD_POST_PARSE_RES_FAILED_NO_CNTN_TYPE = 81
   ,
   /**
    * The POST data cannot be parsed because "Content-Type:" request header has
    * no "boundary" parameter for "multipart/form-data"
    */
   MHD_POST_PARSE_RES_FAILED_HEADER_NO_BOUNDARY = 82
   ,
   /**
    * The POST data cannot be parsed because "Content-Type: multipart/form-data"
    * request header is misformed
    */
   MHD_POST_PARSE_RES_FAILED_HEADER_MISFORMED = 83
   ,
   /**
    * The application set POST encoding to "multipart/form-data", but the request
    * has no "Content-Type: multipart/form-data" header which is required
    * to find "boundary" used in this encoding
    */
   MHD_POST_PARSE_RES_FAILED_HEADER_NOT_MPART = 84
   ,
   /**
    * The POST data cannot be parsed because client used incorrect format
    * of POST encoding.
    */
   MHD_POST_PARSE_RES_FAILED_INVALID_POST_FORMAT = 90
 
 };
 
 #define MHD_POST_PARSE_RESULT_DEFINED 1
 #endif /* ! MHD_POST_PARSE_RESULT_DEFINED */
 
 #ifndef MHD_POST_DATA_READER_DEFINED
 
 /**
  * "Stream" reader for POST data.
  * This callback is called to incrementally process parsed POST data sent by
  * the client.
  * The pointers to the MHD_String and MHD_StringNullable are valid only until
  * return from this callback.
  * The pointers to the strings and the @a data are valid only until return from
  * this callback.
  *
  * @param req the request
  * @param cls user-specified closure
  * @param name the name of the POST field
  * @param filename the name of the uploaded file, @a cstr member is NULL if not
  *                 known / not provided
  * @param content_type the mime-type of the data, cstr member is NULL if not
  *                     known / not provided
  * @param encoding the encoding of the data, cstr member is NULL if not known /
  *                 not provided
  * @param size the number of bytes in @a data available, may be zero if
  *             the @a final_data is #MHD_YES
  * @param data the pointer to @a size bytes of data at the specified
  *             @a off offset, NOT zero-terminated
  * @param off the offset of @a data in the overall value, always equal to
  *            the sum of sizes of previous calls for the same field / file;
  *            client may provide more than one field with the same name and
  *            the same filename, the new filed (or file) is indicated by zero
  *            value of @a off (and the end is indicated by @a final_data)
  * @param final_data if set to #MHD_YES then full field data is provided,
  *                   if set to #MHD_NO then more field data may be provided
  * @return action specifying how to proceed:
  *         #MHD_upload_action_continue() if all is well,
  *         #MHD_upload_action_suspend() to stop reading the upload until
  *         the request is resumed,
  *         #MHD_upload_action_abort_request() to close the socket,
  *         or a response to discard the rest of the upload and transmit
  *         the response
  * @ingroup action
  */
 typedef const struct MHD_UploadAction *
 (MHD_FN_PAR_NONNULL_ (1) MHD_FN_PAR_NONNULL_ (3) MHD_FN_PAR_NONNULL_ (4)
  MHD_FN_PAR_NONNULL_ (5) MHD_FN_PAR_NONNULL_ (6)
  *MHD_PostDataReader) (struct MHD_Request *req,
                        void *cls,
                        const struct MHD_String *name,
                        const struct MHD_StringNullable *filename,
                        const struct MHD_StringNullable *content_type,
                        const struct MHD_StringNullable *encoding,
                        size_t size,
                        const void *data,
                        uint_fast64_t off,
                        enum MHD_Bool final_data);
 
 
 /**
  * The callback to be called when finished with processing
  * of the postprocessor upload data.
  * @param req the request
  * @param cls the closure
  * @param parsing_result the result of POST data parsing
  * @return the action to proceed
  */
 typedef const struct MHD_UploadAction *
 (MHD_FN_PAR_NONNULL_ (1)
  *MHD_PostDataFinished) (struct MHD_Request *req,
                          void *cls,
                          enum MHD_PostParseResult parsing_result);
 
 #define MHD_POST_DATA_READER_DEFINED 1
 #endif /* ! MHD_POST_DATA_READER_DEFINED */
 
 /**
  * Create an action to parse the POSTed content from the client.
  *
  * The action starts parsing of the POST data. Any value that does not fit
  * @a buffer_size or larger that @a auto_stream_size is given to
  * @a stream_reader (if it is not NULL).
  *
  * If @a buffer_size is zero, then buffers will be limited to the connection's
  * memory pool. To force all POST data process via @a stream_reader
  * set @a auto_stream_size to zero.
  *
  * At most one action can be created for any request.
  *
  * @param request the request to create action for
  * @param buffer_size the maximum size allowed for the buffers to parse this
  *                    request POST data. Within the set limit the buffer is
  *                    allocated automatically from the "large" shared memory
  *                    pool if necessary.
  * @param max_nonstream_size the size of the field (in encoded form) above which
  *                           values are not buffered and provided for
  *                           the @a steam_reader automatically;
  *                           useful to have large data (like file uploads)
  *                           processed incrementally, while keeping buffer space
  *                           for small fields only;
  *                           ignored if @a stream_reader is NULL
  * @param enc the data encoding to use,
  *            use #MHD_HTTP_POST_ENCODING_OTHER to detect automatically
  * @param stream_reader the function to call for "oversize" values in
  *                      the stream; can be NULL if @a auto_stream_size is
  *                      not zero
  * @param reader_cls the closure for the @a stream_reader
  * @param done_cb called once all data has been processed for
  *   the final action; values smaller than @a auto_stream_size that
  *   fit into @a buffer_size will be available via
  *   #MHD_request_get_values_cb(), #MHD_request_get_values_list() and
  *   #MHD_request_get_post_data_cb(), #MHD_request_get_post_data_list()
  * @param done_cb_cls the closure for the @a done_cb
  * @return pointer to the action,
  *         NULL if failed (no memory) or if any action has been already
  *         created for the @a request.
  * @sa #MHD_D_OPTION_LARGE_POOL_SIZE()
  * @ingroup action
  */
 MHD_EXTERN_ const struct MHD_Action *
 MHD_action_parse_post (struct MHD_Request *request,
                        size_t buffer_size,
                        size_t max_nonstream_size,
                        enum MHD_HTTP_PostEncoding enc,
                        MHD_PostDataReader stream_reader,
                        void *reader_cls,
                        MHD_PostDataFinished done_cb,
                        void *done_cb_cls)
 MHD_FN_PAR_NONNULL_ (1);
 
 
 #ifndef MHD_POSTFILED_DEFINED
 
 /**
  * Post data element.
  * If any member is not provided/set then pointer to C string is NULL.
  * If any member is set to empty string then pointer to C string not NULL,
  * but the length is zero.
  */
 struct MHD_PostField
 {
   /**
    * The name of the field
    */
   struct MHD_String name;
   /**
    * The field data
    * If not set or defined then to C string is NULL.
    * If set to empty string then pointer to C string not NULL,
    * but the length is zero.
    */
   struct MHD_StringNullable value;
   /**
    * The filename if provided (only for "multipart/form-data")
    * If not set or defined then to C string is NULL.
    * If set to empty string then pointer to C string not NULL,
    * but the length is zero.
    */
   struct MHD_StringNullable filename;
   /**
    * The Content-Type if provided (only for "multipart/form-data")
    * If not set or defined then to C string is NULL.
    * If set to empty string then pointer to C string not NULL,
    * but the length is zero.
    */
   struct MHD_StringNullable content_type;
   /**
    * The Transfer-Encoding if provided (only for "multipart/form-data")
    * If not set or defined then to C string is NULL.
    * If set to empty string then pointer to C string not NULL,
    * but the length is zero.
    */
   struct MHD_StringNullable transfer_encoding;
 };
 
 #define MHD_POSTFILED_DEFINED 1
 #endif /* ! MHD_POSTFILED_DEFINED */
 
 
 /**
  * Iterator over POST data.
  *
  * The @a data pointer is valid only until return from this function.
  *
  * The pointers to the strings in @a data are valid until any MHD_UploadAction
  * is provided. If the data is needed beyond this point, it should be copied.
  *
  * @param cls closure
  * @param data the element of the post data, the pointer is valid only until
  *             return from this function
  * @return #MHD_YES to continue iterating,
  *         #MHD_NO to abort the iteration
  * @ingroup request
  */
 typedef enum MHD_Bool
 (MHD_FN_PAR_NONNULL_ (2)
  *MHD_PostDataIterator)(void *cls,
                         const struct MHD_PostField *data);
 
 /**
  * Get all of the post data from the request via request.
  *
  * @param request the request to get data for
  * @param iterator callback to call on each header;
  *        maybe NULL (then just count headers)
  * @param iterator_cls extra argument to @a iterator
  * @return number of entries iterated over
  * @ingroup request
  */
 MHD_EXTERN_ size_t
 MHD_request_get_post_data_cb (struct MHD_Request *request,
                               MHD_PostDataIterator iterator,
                               void *iterator_cls)
 MHD_FN_PAR_NONNULL_ (1);
 
 /**
  * Get all of the post data from the request.
  *
  * The pointers to the strings in @a elements are valid until any
  * MHD_UploadAction is provided. If the data is needed beyond this point,
  * it should be copied.
  * @param request the request to get data for
  * @param num_elements the number of elements in @a elements array
  * @param[out] elements the array of @a num_elements to get the data
  * @return the number of elements stored in @a elements,
  *         zero if no data or postprocessor was not used.
  * @ingroup request
  */
 MHD_EXTERN_ size_t
 MHD_request_get_post_data_list (
   struct MHD_Request *request,
   size_t num_elements,
   struct MHD_PostField elements[MHD_FN_PAR_DYN_ARR_SIZE_ (num_elements)])
 MHD_FN_PAR_NONNULL_ (1)
 MHD_FN_PAR_NONNULL_ (3) MHD_FN_PAR_OUT_SIZE_ (3,2);
 
 /* ***************** (c) WebSocket support ********** */
 
 /**
  * Handle given to the application to manage special
  * actions relating to MHD responses that "upgrade"
  * the HTTP protocol (i.e. to WebSockets).
  */
 struct MHD_UpgradedHandle;
 
 
 #ifndef MHD_UPGRADEHANDLER_DEFINED
 
 /**
  * Function called after a protocol "upgrade" response was sent successfully
  * and the connection is being switched to other protocol.
  *
  * The newly provided handle @a urh can be used to send and receive the data
  * by #MHD_upgraded_send() and #MHD_upgraded_recv(). The handle must be closed
  * by #MHD_upgraded_close() before destroying the daemon.
  *
  * "Upgraded" connection will not time out, but still counted for daemon
  * global connections limit and for per-IP limit (if set).
  *
  * Except when in 'thread-per-connection' mode, implementations
  * of this function should never block (as it will still be called
  * from within the main event loop).
  *
  * @param cls closure, whatever was given to #MHD_action_upgrade().
  * @param request original HTTP request handle,
  *                giving the function a last chance
  *                to inspect the original HTTP request
  * @param urh argument for #MHD_upgrade_operation() on this @a response.
  *        Applications must eventually use this callback to (indirectly)
  *        perform the close() action on the @a sock.
  */
 typedef void
 (MHD_FN_PAR_NONNULL_ (2) MHD_FN_PAR_NONNULL_ (3)
  *MHD_UpgradeHandler)(void *cls,
                       struct MHD_Request *MHD_RESTRICT request,
                       struct MHD_UpgradedHandle *MHD_RESTRICT urh);
 
 #define MHD_UPGRADEHANDLER_DEFINED 1
 #endif /* ! MHD_UPGRADEHANDLER_DEFINED */
 
 
 /**
  * Create a action object that can be used for 101 Upgrade
  * responses, for example to implement WebSockets.  After sending the
  * response, control over the data stream is given to the callback (which
  * can then, for example, start some bi-directional communication).
  * The callback will ONLY be called after the response header was successfully
  * passed to the OS; if there are communication errors before, the usual MHD
  * connection error handling code will be performed.
  *
  * At most one action can be created for any request.
  *
  * @param request the request to create action for
  * @param upgrade_hdr_value the value of the "Upgrade:" header, mandatory
                             string
  * @param upgrade_handler function to call with the "upgraded" socket
  * @param upgrade_handler_cls closure for @a upgrade_handler
  * @param num_headers number of elements in the @a headers array,
  *                    must be zero if @a headers is NULL
  * @param headers the optional pointer to the array of the headers (the strings
  *                are copied and does not need to be valid after return from
  *                this function),
  *                can be NULL if @a num_headers is zero
  * @return NULL on error (i.e. invalid arguments, out of memory)
  * @ingroup action
  */
 MHD_EXTERN_ const struct MHD_Action *
 MHD_action_upgrade (struct MHD_Request *MHD_RESTRICT request,
                     const char *MHD_RESTRICT upgrade_hdr_value,
                     MHD_UpgradeHandler upgrade_handler,
                     void *upgrade_handler_cls,
                     size_t num_headers,
                     const struct MHD_NameValueCStr *MHD_RESTRICT headers)
 MHD_FN_PAR_NONNULL_ (1) MHD_FN_PAR_NONNULL_ (2) MHD_FN_PAR_CSTR_ (2)
 MHD_FN_PAR_IN_SIZE_ (6,5);
 
 
 /**
  * Create a action object that can be used for 101 Upgrade
  * responses, for example to implement WebSockets.  After sending the
  * response, control over the data stream is given to the callback (which
  * can then, for example, start some bi-directional communication).
  * The callback will ONLY be called after the response header was successfully
  * passed to the OS; if there are communication errors before, the usual MHD
  * connection error handling code will be performed.
  *
  * At most one action can be created for any request.
  *
  * @param request the request to create action for
  * @param upgrade_hdr_value the value of the "Upgrade:" header, mandatory
                             string
  * @param upgrade_handler function to call with the "upgraded" socket
  * @param upgrade_handler_cls closure for @a upgrade_handler
  * @param num_headers number of elements in the @a headers array,
  *                    must be zero if @a headers is NULL
  * @param headers the optional pointer to the array of the headers (the strings
  *                are copied and does not need to be valid after return from
  *                this function),
  *                can be NULL if @a num_headers is zero
  * @return NULL on error (i.e. invalid arguments, out of memory)
  * @ingroup action
  */
 MHD_EXTERN_ const struct MHD_UploadAction *
 MHD_upload_action_upgrade (
   struct MHD_Request *MHD_RESTRICT request,
   const char *MHD_RESTRICT upgrade_hdr_value,
   MHD_UpgradeHandler upgrade_handler,
   void *upgrade_handler_cls,
   size_t num_headers,
   const struct MHD_NameValueCStr *MHD_RESTRICT headers)
 MHD_FN_PAR_NONNULL_ (1) MHD_FN_PAR_NONNULL_ (2) MHD_FN_PAR_CSTR_ (2)
 MHD_FN_PAR_IN_SIZE_ (6,5);
 
 
 /**
  * Receive data on the HTTP-Upgraded connection.
  *
  * The function finished if one of the following happens:
  * + ANY amount of data has been received,
  * + timeout reached,
  * + network error occurs
  *
  * @param urh the HTTP-Upgraded handle
  * @param recv_buf_size the size of the @a recv_buf
  * @param recv_buf the buffer to receive the data
  * @param received_size the pointer to variable to get amount of received data
  * @param max_wait_millisec the maximum wait time for the data,
  *                          non-blocking operation if set to zero,
  *                          wait indefinitely if larger or equal to
  *                          #MHD_WAIT_INDEFINITELY,
  *                          the function may return earlier if waiting is
  *                          interrupted or by other reasons
  * @return #MHD_SC_OK if ANY data received (check the @a received_size) or
  *                    remote shut down send side (indicated by @a received_size
  *                    set to zero),
  *         #MHD_SC_UPGRADED_NET_TIMEOUT if NO data received but timeout expired,
  *         #MHD_SC_UPGRADED_NET_CONN_CLOSED if network connection has been
  *                                          closed,
  *         #MHD_SC_UPGRADED_NET_CONN_BROKEN if broken network connection has
  *                                          been detected,
  *         #MHD_SC_UPGRADED_TLS_ERROR if TLS error occurs (only for TLS),
  *         #MHD_SC_UPGRADED_NET_HARD_ERROR if any other network or sockets
  *                                         unrecoverable error occurs,
  *         #MHD_SC_UPGRADED_HANDLE_INVALID if @a urh is invalid,
  *         #MHD_SC_UPGRADED_WAITING_NOT_SUPPORTED if timed wait is not supported
  *                                                by this MHD build or platform
  */
 MHD_EXTERN_ enum MHD_StatusCode
 MHD_upgraded_recv (struct MHD_UpgradedHandle *MHD_RESTRICT urh,
                    size_t recv_buf_size,
                    void *MHD_RESTRICT recv_buf,
                    size_t *MHD_RESTRICT received_size,
                    uint_fast64_t max_wait_millisec)
 MHD_FN_PAR_NONNULL_ALL_ MHD_FN_PAR_OUT_SIZE_ (3,2)
 MHD_FN_PAR_OUT_ (4);
 
 
 /**
  * Send data on the HTTP-Upgraded connection.
  *
  * The function finished if one of the following happens:
  * + ALL provided data has been sent,
  * + timeout reached,
  * + network error occurs
  *
  * Parameter @a more_data_to_come controls network buffering. When set to
  * #MHD_YES, the OS waits shortly for additional data and tries to use
  * the network more effeciently delaying the last network packet, if it is
  * incomplete, to combine it with the next data provided.
  *
  * @param urh the HTTP-Upgraded handle
  * @param send_buf_size the amount of data in the @a send_buf
  * @param send_buf the buffer with the data to send
  * @param sent_size the pointer to get the amout of sent data
  * @param max_wait_millisec the maximum wait time for the data,
  *                          non-blocking operation if set to zero,
  *                          wait indefinitely if larger or equal to
  *                          #MHD_WAIT_INDEFINITELY
  * @param more_data_to_come set to #MHD_YES if the provided data in
  *                          the @a send_buf is part of a larger data package,
  *                          like an incomplete message or streamed
  *                          (not the final) part of some file, and more data
  *                          expected to be sent soon over the same connection,
  *                          set to #MHD_NO the data in the @a send_buf is
  *                          the complete message or the final part of
  *                          the message (or file) and it should be pushed
  *                          to the network (and to the client) as soon
  *                          as possible
  * @return #MHD_SC_OK if ANY data sent (check the @a sent_size),
  *         #MHD_SC_UPGRADED_NET_TIMEOUT if NO data sent but timeout expired,
  *         #MHD_SC_UPGRADED_NET_CONN_CLOSED if network connection has been
  *                                          closed,
  *         #MHD_SC_UPGRADED_NET_CONN_BROKEN if broken network connection has
  *                                          been detected,
  *         #MHD_SC_UPGRADED_TLS_ERROR if TLS error occurs (only for TLS),
  *         #MHD_SC_UPGRADED_NET_HARD_ERROR if any other network or sockets
  *                                         unrecoverable error occurs,
  *         #MHD_SC_UPGRADED_HANDLE_INVALID if @a urh is invalid,
  *         #MHD_SC_UPGRADED_WAITING_NOT_SUPPORTED if timed wait is not supported
  *                                                by this MHD build or platform
  */
 MHD_EXTERN_ enum MHD_StatusCode
 MHD_upgraded_send (struct MHD_UpgradedHandle *MHD_RESTRICT urh,
                    size_t send_buf_size,
                    const void *MHD_RESTRICT send_buf,
                    size_t *MHD_RESTRICT sent_size,
                    uint_fast64_t max_wait_millisec,
                    enum MHD_Bool more_data_to_come)
 MHD_FN_PAR_NONNULL_ALL_ MHD_FN_PAR_IN_SIZE_ (3,2)
 MHD_FN_PAR_OUT_ (4);
 
 
 /**
  * Close HTTP-Upgraded connection handle.
  *
  * The handle cannot be used after successful return from this function.
  *
  * The function cannot fail if called correctly (the daemon is not destroyed
  * and the upgraded connection has not been closed yet).
  *
  * @param urh the handle to close
  * @return #MHD_SC_OK on success,
  *         error code otherwise
  */
 MHD_EXTERN_ enum MHD_StatusCode
 MHD_upgraded_close (struct MHD_UpgradedHandle *urh)
 MHD_FN_PAR_NONNULL_ (1);
 
 
 /* ********************** (e) Client auth ********************** */
 
 
 /**
  * Length of the binary output of the MD5 hash function.
  * @sa #MHD_digest_get_hash_size()
  * @ingroup authentication
  */
 #define MHD_MD5_DIGEST_SIZE 16
 
 /**
  * Length of the binary output of the SHA-256 hash function.
  * @sa #MHD_digest_get_hash_size()
  * @ingroup authentication
  */
 #define MHD_SHA256_DIGEST_SIZE 32
 
 /**
  * Length of the binary output of the SHA-512/256 hash function.
  * @warning While this value is the same as the #MHD_SHA256_DIGEST_SIZE,
  *          the calculated digests for SHA-256 and SHA-512/256 are different.
  * @sa #MHD_digest_get_hash_size()
  * @ingroup authentication
  */
 #define MHD_SHA512_256_DIGEST_SIZE 32
 
 /**
  * Base type of hash calculation.
  * Used as part of #MHD_DigestAuthAlgo values.
  *
  * @warning Not used directly by MHD API.
  */
 enum MHD_FIXED_ENUM_MHD_APP_SET_ MHD_DigestBaseAlgo
 {
   /**
    * Invalid hash algorithm value
    */
   MHD_DIGEST_BASE_ALGO_INVALID = 0
   ,
   /**
    * MD5 hash algorithm.
    * As specified by RFC1321
    */
   MHD_DIGEST_BASE_ALGO_MD5 = (1u << 0)
   ,
   /**
    * SHA-256 hash algorithm.
    * As specified by FIPS PUB 180-4
    */
   MHD_DIGEST_BASE_ALGO_SHA256 = (1u << 1)
   ,
   /**
    * SHA-512/256 hash algorithm.
    * As specified by FIPS PUB 180-4
    */
   MHD_DIGEST_BASE_ALGO_SHA512_256 = (1u << 2)
 };
 
 /**
  * The flag indicating non-session algorithm types,
  * like 'MD5', 'SHA-256' or 'SHA-512-256'.
  */
 #define MHD_DIGEST_AUTH_ALGO_NON_SESSION    (1u << 6)
 
 /**
  * The flag indicating session algorithm types,
  * like 'MD5-sess', 'SHA-256-sess' or 'SHA-512-256-sess'.
  */
 #define MHD_DIGEST_AUTH_ALGO_SESSION        (1u << 7)
 
 /**
  * Digest algorithm identification
  */
 enum MHD_FIXED_ENUM_MHD_APP_SET_ MHD_DigestAuthAlgo
 {
   /**
    * Unknown or wrong algorithm type.
    * Used in struct MHD_AuthDigestInfo to indicate client value that
    * cannot by identified.
    */
   MHD_DIGEST_AUTH_ALGO_INVALID = 0
   ,
   /**
    * The 'MD5' algorithm, non-session version.
    */
   MHD_DIGEST_AUTH_ALGO_MD5 =
     MHD_DIGEST_BASE_ALGO_MD5 | MHD_DIGEST_AUTH_ALGO_NON_SESSION
   ,
   /**
    * The 'MD5-sess' algorithm.
    * Not supported by MHD for authentication.
    */
   MHD_DIGEST_AUTH_ALGO_MD5_SESSION =
     MHD_DIGEST_BASE_ALGO_MD5 | MHD_DIGEST_AUTH_ALGO_SESSION
   ,
   /**
    * The 'SHA-256' algorithm, non-session version.
    */
   MHD_DIGEST_AUTH_ALGO_SHA256 =
     MHD_DIGEST_BASE_ALGO_SHA256 | MHD_DIGEST_AUTH_ALGO_NON_SESSION
   ,
   /**
    * The 'SHA-256-sess' algorithm.
    * Not supported by MHD for authentication.
    */
   MHD_DIGEST_AUTH_ALGO_SHA256_SESSION =
     MHD_DIGEST_BASE_ALGO_SHA256 | MHD_DIGEST_AUTH_ALGO_SESSION
   ,
   /**
    * The 'SHA-512-256' (SHA-512/256) algorithm.
    */
   MHD_DIGEST_AUTH_ALGO_SHA512_256 =
     MHD_DIGEST_BASE_ALGO_SHA512_256 | MHD_DIGEST_AUTH_ALGO_NON_SESSION
   ,
   /**
    * The 'SHA-512-256-sess' (SHA-512/256 session) algorithm.
    * Not supported by MHD for authentication.
    */
   MHD_DIGEST_AUTH_ALGO_SHA512_256_SESSION =
     MHD_DIGEST_BASE_ALGO_SHA512_256 | MHD_DIGEST_AUTH_ALGO_SESSION
 };
 
 
 /**
  * Get digest size in bytes for specified algorithm.
  *
  * The size of the digest specifies the size of the userhash, userdigest
  * and other parameters which size depends on used hash algorithm.
  * @param algo the algorithm to check
  * @return the size (in bytes) of the digest (either #MHD_MD5_DIGEST_SIZE or
  *         #MHD_SHA256_DIGEST_SIZE/MHD_SHA512_256_DIGEST_SIZE)
  *         or zero if the input value is not supported or not valid
  * @sa #MHD_digest_auth_calc_userdigest()
  * @sa #MHD_digest_auth_calc_userhash(), #MHD_digest_auth_calc_userhash_hex()
  * @ingroup authentication
  */
 MHD_EXTERN_ size_t
 MHD_digest_get_hash_size (enum MHD_DigestAuthAlgo algo)
 MHD_FN_CONST_;
 
 /**
  * Digest algorithm identification, allow multiple selection.
  *
  * #MHD_DigestAuthAlgo always can be casted to #MHD_DigestAuthMultiAlgo, but
  * not vice versa.
  */
 enum MHD_FIXED_ENUM_MHD_APP_SET_ MHD_DigestAuthMultiAlgo
 {
   /**
    * Unknown or wrong algorithm type.
    */
   MHD_DIGEST_AUTH_MULT_ALGO_INVALID = MHD_DIGEST_AUTH_ALGO_INVALID
   ,
   /**
    * The 'MD5' algorithm, non-session version.
    */
   MHD_DIGEST_AUTH_MULT_ALGO_MD5 = MHD_DIGEST_AUTH_ALGO_MD5
   ,
   /**
    * The 'MD5-sess' algorithm.
    * Not supported by MHD for authentication.
    * Reserved value.
    */
   MHD_DIGEST_AUTH_MULT_ALGO_MD5_SESSION = MHD_DIGEST_AUTH_ALGO_MD5_SESSION
   ,
   /**
    * The 'SHA-256' algorithm, non-session version.
    */
   MHD_DIGEST_AUTH_MULT_ALGO_SHA256 = MHD_DIGEST_AUTH_ALGO_SHA256
   ,
   /**
    * The 'SHA-256-sess' algorithm.
    * Not supported by MHD for authentication.
    * Reserved value.
    */
   MHD_DIGEST_AUTH_MULT_ALGO_SHA256_SESSION =
     MHD_DIGEST_AUTH_ALGO_SHA256_SESSION
   ,
   /**
    * The 'SHA-512-256' (SHA-512/256) algorithm, non-session version.
    */
   MHD_DIGEST_AUTH_MULT_ALGO_SHA512_256 = MHD_DIGEST_AUTH_ALGO_SHA512_256
   ,
   /**
    * The 'SHA-512-256-sess' (SHA-512/256 session) algorithm.
    * Not supported by MHD for authentication.
    * Reserved value.
    */
   MHD_DIGEST_AUTH_MULT_ALGO_SHA512_256_SESSION =
     MHD_DIGEST_AUTH_ALGO_SHA512_256_SESSION
   ,
   /**
    * SHA-256 or SHA-512/256 non-session algorithm, MHD will choose
    * the preferred or the matching one.
    */
   MHD_DIGEST_AUTH_MULT_ALGO_SHA_ANY_NON_SESSION =
     MHD_DIGEST_AUTH_ALGO_SHA256 | MHD_DIGEST_AUTH_ALGO_SHA512_256
   ,
   /**
    * Any non-session algorithm, MHD will choose the preferred or
    * the matching one.
    */
   MHD_DIGEST_AUTH_MULT_ALGO_ANY_NON_SESSION =
     (0x3F) | MHD_DIGEST_AUTH_ALGO_NON_SESSION
   ,
   /**
    * The SHA-256 or SHA-512/256 session algorithm.
    * Not supported by MHD.
    * Reserved value.
    */
   MHD_DIGEST_AUTH_MULT_ALGO_SHA_ANY_SESSION =
     MHD_DIGEST_AUTH_ALGO_SHA256_SESSION
     | MHD_DIGEST_AUTH_ALGO_SHA512_256_SESSION
   ,
   /**
    * Any session algorithm.
    * Not supported by MHD.
    * Reserved value.
    */
   MHD_DIGEST_AUTH_MULT_ALGO_ANY_SESSION =
     (0x3F) | MHD_DIGEST_AUTH_ALGO_SESSION
   ,
   /**
    * The MD5 algorithm, session or non-session.
    * Currently supported as non-session only.
    */
   MHD_DIGEST_AUTH_MULT_ALGO_MD5_ANY =
     MHD_DIGEST_AUTH_MULT_ALGO_MD5 | MHD_DIGEST_AUTH_MULT_ALGO_MD5_SESSION
   ,
   /**
    * The SHA-256 algorithm, session or non-session.
    * Currently supported as non-session only.
    */
   MHD_DIGEST_AUTH_MULT_ALGO_SHA256_ANY =
     MHD_DIGEST_AUTH_MULT_ALGO_SHA256
     | MHD_DIGEST_AUTH_MULT_ALGO_SHA256_SESSION
   ,
   /**
    * The SHA-512/256 algorithm, session or non-session.
    * Currently supported as non-session only.
    */
   MHD_DIGEST_AUTH_MULT_ALGO_SHA512_256_ANY =
     MHD_DIGEST_AUTH_MULT_ALGO_SHA512_256
     | MHD_DIGEST_AUTH_MULT_ALGO_SHA512_256_SESSION
   ,
   /**
    * The SHA-256 or SHA-512/256 algorithm, session or non-session.
    * Currently supported as non-session only.
    */
   MHD_DIGEST_AUTH_MULT_ALGO_SHA_ANY_ANY =
     MHD_DIGEST_AUTH_MULT_ALGO_SHA_ANY_NON_SESSION
     | MHD_DIGEST_AUTH_MULT_ALGO_SHA_ANY_SESSION
   ,
   /**
    * Any algorithm, MHD will choose the preferred or the matching one.
    */
   MHD_DIGEST_AUTH_MULT_ALGO_ANY =
     (0x3F) | MHD_DIGEST_AUTH_ALGO_NON_SESSION | MHD_DIGEST_AUTH_ALGO_SESSION
 };
 
 
 /**
  * Calculate "userhash", return it as binary data.
  *
  * The "userhash" is the hash of the string "username:realm".
  *
  * The "userhash" could be used to avoid sending username in cleartext in Digest
  * Authorization client's header.
  *
  * Userhash is not designed to hide the username in local database or files,
  * as username in cleartext is required for #MHD_digest_auth_check() function
  * to check the response, but it can be used to hide username in HTTP headers.
  *
  * This function could be used when the new username is added to the username
  * database to save the "userhash" alongside with the username (preferably) or
  * when loading list of the usernames to generate the userhash for every loaded
  * username (this will cause delays at the start with the long lists).
  *
  * Once "userhash" is generated it could be used to identify users by clients
  * with "userhash" support.
  * Avoid repetitive usage of this function for the same username/realm
  * combination as it will cause excessive CPU load; save and reuse the result
  * instead.
  *
  * @param algo the algorithm for userhash calculations
  * @param username the username
  * @param realm the realm
  * @param[out] userhash_bin the output buffer for userhash as binary data;
  *                          if this function succeeds, then this buffer has
  *                          #MHD_digest_get_hash_size() bytes of userhash
  *                          upon return
  * @param bin_buf_size the size of the @a userhash_bin buffer, must be
  *                     at least #MHD_digest_get_hash_size() bytes long
  * @return #MHD_SC_OK on success,
  *         #MHD_SC_OUT_BUFF_TOO_SMALL if @a bin_buf_size is too small,
  *         #MHD_SC_HASH_FAILED if hashing failed,
  *         #MHD_SC_AUTH_DIGEST_ALGO_NOT_SUPPORTED if requested @a algo is
  *                                                unknown or unsupported.
  * @sa #MHD_digest_auth_calc_userhash_hex()
  * @ingroup authentication
  */
 MHD_EXTERN_ enum MHD_StatusCode
 MHD_digest_auth_calc_userhash (enum MHD_DigestAuthAlgo algo,
                                const char *MHD_RESTRICT username,
                                const char *MHD_RESTRICT realm,
                                size_t bin_buf_size,
                                void *MHD_RESTRICT userhash_bin)
 MHD_FN_PURE_ MHD_FN_PAR_NONNULL_ALL_ MHD_FN_PAR_CSTR_ (2)
 MHD_FN_PAR_CSTR_ (3) MHD_FN_PAR_OUT_SIZE_ (5,4);
 
 
 /**
  * Calculate "userhash", return it as hexadecimal string.
  *
  * The "userhash" is the hash of the string "username:realm".
  *
  * The "userhash" could be used to avoid sending username in cleartext in Digest
  * Authorization client's header.
  *
  * Userhash is not designed to hide the username in local database or files,
  * as username in cleartext is required for #MHD_digest_auth_check() function
  * to check the response, but it can be used to hide username in HTTP headers.
  *
  * This function could be used when the new username is added to the username
  * database to save the "userhash" alongside with the username (preferably) or
  * when loading list of the usernames to generate the userhash for every loaded
  * username (this will cause delays at the start with the long lists).
  *
  * Once "userhash" is generated it could be used to identify users by clients
  * with "userhash" support.
  * Avoid repetitive usage of this function for the same username/realm
  * combination as it will cause excessive CPU load; save and reuse the result
  * instead.
  *
  * @param algo the algorithm for userhash calculations
  * @param username the username
  * @param realm the realm
  * @param hex_buf_size the size of the @a userhash_hex buffer, must be
  *                     at least #MHD_digest_get_hash_size()*2+1 chars long
  * @param[out] userhash_hex the output buffer for userhash as hex string;
  *                          if this function succeeds, then this buffer has
  *                          #MHD_digest_get_hash_size()*2 chars long
  *                          userhash string plus one zero-termination char
  * @return #MHD_SC_OK on success,
  *         #MHD_SC_OUT_BUFF_TOO_SMALL if @a bin_buf_size is too small,
  *         #MHD_SC_HASH_FAILED if hashing failed,
  *         #MHD_SC_AUTH_DIGEST_ALGO_NOT_SUPPORTED if requested @a algo is
  *                                                unknown or unsupported.
  * @sa #MHD_digest_auth_calc_userhash()
  * @ingroup authentication
  */
 MHD_EXTERN_ enum MHD_StatusCode
 MHD_digest_auth_calc_userhash_hex (
   enum MHD_DigestAuthAlgo algo,
   const char *MHD_RESTRICT username,
   const char *MHD_RESTRICT realm,
   size_t hex_buf_size,
   char userhash_hex[MHD_FN_PAR_DYN_ARR_SIZE_ (hex_buf_size)])
 MHD_FN_PURE_ MHD_FN_PAR_NONNULL_ALL_ MHD_FN_PAR_CSTR_ (2)
 MHD_FN_PAR_CSTR_ (3) MHD_FN_PAR_OUT_SIZE_ (5,4);
 
 
 /**
  * The type of username used by client in Digest Authorization header
  *
  * Values are sorted so simplified checks could be used.
  * For example:
  * * (value <= MHD_DIGEST_AUTH_UNAME_TYPE_INVALID) is true if no valid username
  *   is provided by the client (not used currently)
  * * (value >= MHD_DIGEST_AUTH_UNAME_TYPE_USERHASH) is true if username is
  *   provided in any form
  * * (value >= MHD_DIGEST_AUTH_UNAME_TYPE_STANDARD) is true if username is
  *   provided in clear text (no userhash matching is needed)
  */
 enum MHD_FIXED_ENUM_MHD_SET_ MHD_DigestAuthUsernameType
 {
   /**
    * No username parameter is in Digest Authorization header.
    * Not used currently. Value #MHD_SC_REQ_AUTH_DATA_BROKEN is returned
    * by #MHD_request_get_info_dynamic_sz() if the request has no username.
    */
   MHD_DIGEST_AUTH_UNAME_TYPE_MISSING = 0
   ,
   /**
    * The 'username' parameter is used to specify the username.
    */
   MHD_DIGEST_AUTH_UNAME_TYPE_STANDARD = (1u << 2)
   ,
   /**
    * The username is specified by 'username*' parameter with
    * the extended notation (see RFC 5987, section-3.2.1).
    * The only difference between standard and extended types is
    * the way how username value is encoded in the header.
    */
   MHD_DIGEST_AUTH_UNAME_TYPE_EXTENDED = (1u << 3)
   ,
   /**
    * The username provided in form of 'userhash' as
    * specified by RFC 7616, section-3.4.4.
    * @sa #MHD_digest_auth_calc_userhash_hex(), #MHD_digest_auth_calc_userhash()
    */
   MHD_DIGEST_AUTH_UNAME_TYPE_USERHASH = (1u << 1)
   ,
   /**
    * The invalid combination of username parameters are used by client.
    * Either:
    * + both 'username' and 'username*' are used
    * + 'username*' is used with 'userhash=true'
    * + 'username*' used with invalid extended notation
    * + 'username' is not hexadecimal string, while 'userhash' set to 'true'
    * Not used currently. Value #MHD_SC_REQ_AUTH_DATA_BROKEN is returned
    * by #MHD_request_get_info_dynamic_sz() if the request has broken username.
    */
   MHD_DIGEST_AUTH_UNAME_TYPE_INVALID = (1u << 0)
 };
 
 /**
  * The QOP ('quality of protection') types.
  */
 enum MHD_FIXED_ENUM_MHD_APP_SET_ MHD_DigestAuthQOP
 {
   /**
    * Invalid/unknown QOP.
    * Used in struct MHD_AuthDigestInfo to indicate client value that
    * cannot by identified.
    */
   MHD_DIGEST_AUTH_QOP_INVALID = 0
   ,
   /**
    * No QOP parameter.
    * As described in old RFC 2069 original specification.
    * This mode is not allowed by latest RFCs and should be used only to
    * communicate with clients that do not support more modern modes (with QOP
    * parameter).
    * This mode is less secure than other modes and inefficient.
    */
   MHD_DIGEST_AUTH_QOP_NONE = (1u << 0)
   ,
   /**
    * The 'auth' QOP type.
    */
   MHD_DIGEST_AUTH_QOP_AUTH = (1u << 1)
   ,
   /**
    * The 'auth-int' QOP type.
    * Not supported by MHD for authentication.
    */
   MHD_DIGEST_AUTH_QOP_AUTH_INT = (1u << 2)
 };
 
 /**
  * The QOP ('quality of protection') types, multiple selection.
  *
  * #MHD_DigestAuthQOP always can be casted to #MHD_DigestAuthMultiQOP, but
  * not vice versa.
  */
 enum MHD_FIXED_ENUM_MHD_APP_SET_ MHD_DigestAuthMultiQOP
 {
   /**
    * Invalid/unknown QOP.
    */
   MHD_DIGEST_AUTH_MULT_QOP_INVALID = MHD_DIGEST_AUTH_QOP_INVALID
   ,
   /**
    * No QOP parameter.
    * As described in old RFC 2069 original specification.
    * This mode is not allowed by latest RFCs and should be used only to
    * communicate with clients that do not support more modern modes (with QOP
    * parameter).
    * This mode is less secure than other modes and inefficient.
    */
   MHD_DIGEST_AUTH_MULT_QOP_NONE = MHD_DIGEST_AUTH_QOP_NONE
   ,
   /**
    * The 'auth' QOP type.
    */
   MHD_DIGEST_AUTH_MULT_QOP_AUTH = MHD_DIGEST_AUTH_QOP_AUTH
   ,
   /**
    * The 'auth-int' QOP type.
    * Not supported by MHD.
    * Reserved value.
    */
   MHD_DIGEST_AUTH_MULT_QOP_AUTH_INT = MHD_DIGEST_AUTH_QOP_AUTH_INT
   ,
   /**
    * The 'auth' QOP type OR the old RFC2069 (no QOP) type.
    * In other words: any types except 'auth-int'.
    * RFC2069-compatible mode is allowed, thus this value should be used only
    * when it is really necessary.
    */
   MHD_DIGEST_AUTH_MULT_QOP_ANY_NON_INT =
     MHD_DIGEST_AUTH_QOP_NONE | MHD_DIGEST_AUTH_QOP_AUTH
   ,
   /**
    * Any 'auth' QOP type ('auth' or 'auth-int').
    * Currently supported as 'auth' QOP type only.
    */
   MHD_DIGEST_AUTH_MULT_QOP_AUTH_ANY =
     MHD_DIGEST_AUTH_QOP_AUTH | MHD_DIGEST_AUTH_QOP_AUTH_INT
 };
 
 /**
  * The type of 'nc' (nonce count) value provided in the request
  */
 enum MHD_FIXED_ENUM_MHD_SET_ MHD_DigestAuthNC
 {
   /**
    * Readable hexdecimal non-zero number.
    * The decoded value is placed in @a nc member of struct MHD_AuthDigestInfo
    */
   MHD_DIGEST_AUTH_NC_NUMBER = 1
   ,
   /**
    * Readable zero number.
    * Compliant clients should not use such values.
    * Can be treated as invalid request.
    */
   MHD_DIGEST_AUTH_NC_ZERO = 2
   ,
   /**
    * 'nc' value is not provided by the client.
    * Unless old RFC 2069 mode is allowed, this should be treated as invalid
    * request.
    */
   MHD_DIGEST_AUTH_NC_NONE = 3
   ,
   /**
    * 'nc' value is too long to be decoded.
    * Compliant clients should not use such values.
    * Can be treated as invalid request.
    */
   MHD_DIGEST_AUTH_NC_TOO_LONG = 4
   ,
   /**
    * 'nc' value is too large for uint32_t.
    * Compliant clients should not use such values.
    * Can be treated as request with a stale nonce or as invalid request.
    */
   MHD_DIGEST_AUTH_NC_TOO_LARGE = 5
 };
 
 
 /**
  * Information from Digest Authorization client's header.
  *
  * @see #MHD_REQUEST_INFO_DYNAMIC_AUTH_DIGEST_INFO
  */
 struct MHD_AuthDigestInfo
 {
   /**
    * The algorithm as defined by client.
    * Set automatically to MD5 if not specified by client.
    */
   enum MHD_DigestAuthAlgo algo;
 
   /**
    * The type of username used by client.
    */
   enum MHD_DigestAuthUsernameType uname_type;
 
   /**
    * The username string.
    * Used only if username type is standard or extended, always NULL otherwise.
    * If extended notation is used, this string is pct-decoded string
    * with charset and language tag removed (i.e. it is original username
    * extracted from the extended notation).
    * When userhash is used by the client, the string pointer is NULL and
    * @a userhash_hex and @a userhash_bin are set.
    */
   struct MHD_StringNullable username;
 
   /**
    * The userhash string.
    * Valid only if username type is userhash.
    * This is unqoted string without decoding of the hexadecimal
    * digits (as provided by the client).
    * @sa #MHD_digest_auth_calc_userhash_hex()
    */
   struct MHD_StringNullable userhash_hex;
 
   /**
    * The userhash decoded to binary form.
    * Used only if username type is userhash, always NULL otherwise.
    * When not NULL, this points to binary sequence @a userhash_bin_size bytes
    * long.
    * The valid size should be #MHD_digest_get_hash_size() bytes.
    * @warning This is a binary data, no zero termination.
    * @warning To avoid buffer overruns, always check the size of the data before
    *          use, because @a userhash_bin can point even to zero-sized
    *          data.
    * @sa #MHD_digest_auth_calc_userhash()
    */
   const uint8_t *userhash_bin;
 
   /**
    * The size of the data pointed by @a userhash_bin.
    * Always zero when @a userhash_bin is NULL.
    */
   size_t userhash_bin_size;
 
   /**
    * The 'opaque' parameter value, as specified by client.
    * If not specified by client then string pointer is NULL.
    */
   struct MHD_StringNullable opaque;
 
   /**
    * The 'realm' parameter value, as specified by client.
    * If not specified by client then string pointer is NULL.
    */
   struct MHD_StringNullable realm;
 
   /**
    * The 'qop' parameter value.
    */
   enum MHD_DigestAuthQOP qop;
 
   /**
    * The length of the 'cnonce' parameter value, including possible
    * backslash-escape characters.
    * 'cnonce' is used in hash calculation, which is CPU-intensive procedure.
    * An application may want to reject too large cnonces to limit the CPU load.
    * A few kilobytes is a reasonable limit, typically cnonce is just 32-160
    * characters long.
    */
   size_t cnonce_len;
 
   /**
    * The type of 'nc' (nonce count) value provided in the request.
    */
   enum MHD_DigestAuthNC nc_type;
 
   /**
    * The nc (nonce count) parameter value.
    * Can be used by application to limit the number of nonce re-uses. If @a nc
    * is higher than application wants to allow, then "auth required" response
    * with 'stale=true' could be used to force client to retry with the fresh
    * 'nonce'.
    * Set to zero when @a nc_type is not set to #MHD_DIGEST_AUTH_NC_NUMBER.
    */
   uint_fast32_t nc;
 };
 
 /**
  * The result of digest authentication of the client.
  *
  * All error values are zero or negative.
  */
 enum MHD_FIXED_ENUM_MHD_SET_ MHD_DigestAuthResult
 {
   /**
    * Authentication OK.
    */
   MHD_DAUTH_OK = 1
   ,
   /**
    * General error, like "out of memory".
    * Authentication may be valid, but cannot be checked.
    */
   MHD_DAUTH_ERROR = 0
   ,
   /**
    * No "Authorization" header for Digest Authentication.
    */
   MHD_DAUTH_HEADER_MISSING = -1
   ,
   /**
    * Wrong format of the header.
    * Also returned if required parameters in Authorization header are missing
    * or broken (in invalid format).
    */
   MHD_DAUTH_HEADER_BROKEN = -9
   ,
   /**
    * Unsupported algorithm.
    */
   MHD_DAUTH_UNSUPPORTED_ALGO = -10
   ,
   /**
    * Unsupported 'qop'.
    */
   MHD_DAUTH_UNSUPPORTED_QOP = -11
   ,
   /**
    * Incorrect userdigest size.
    */
   MHD_DAUTH_INVALID_USERDIGEST_SIZE = -15
   ,
   /**
    * Wrong 'username'.
    */
   MHD_DAUTH_WRONG_USERNAME = -17
   ,
   /**
    * Wrong 'realm'.
    */
   MHD_DAUTH_WRONG_REALM = -18
   ,
   /**
    * Wrong 'URI' (or URI parameters).
    */
   MHD_DAUTH_WRONG_URI = -19
   ,
   /**
    * Wrong 'qop'.
    */
   MHD_DAUTH_WRONG_QOP = -20
   ,
   /**
    * Wrong 'algorithm'.
    */
   MHD_DAUTH_WRONG_ALGO = -21
   ,
   /**
    * Too large (>64 KiB) Authorization parameter value.
    */
   MHD_DAUTH_TOO_LARGE = -22
   ,
   /* The different form of naming is intentionally used for the results below,
    * as they are more important */
 
   /**
    * The 'nonce' is too old. Suggest the client to retry with the same
    * username and password to get the fresh 'nonce'.
    * The validity of the 'nonce' may be not checked.
    */
   MHD_DAUTH_NONCE_STALE = -25
   ,
   /**
    * The 'nonce' is wrong. May indicate an attack attempt.
    */
   MHD_DAUTH_NONCE_WRONG = -33
   ,
   /**
    * The 'response' is wrong. May indicate a wrong password used or
    * an attack attempt.
    */
   MHD_DAUTH_RESPONSE_WRONG = -34
 };
 
 
 /**
  * Authenticates the authorization header sent by the client.
  *
  * If RFC2069 mode is allowed by setting bit #MHD_DIGEST_AUTH_QOP_NONE in
  * @a mqop and the client uses this mode, then server generated nonces are
  * used as one-time nonces because nonce-count is not supported in this old RFC.
  * Communication in this mode is very inefficient, especially if the client
  * requests several resources one-by-one as for every request a new nonce must
  * be generated and client repeats all requests twice (first time to get a new
  * nonce and second time to perform an authorised request).
  *
  * @param request the request
  * @param realm the realm for authorization of the client
  * @param username the username to be authenticated, must be in clear text
  *                 even if userhash is used by the client
  * @param password the password matching the @a username (and the @a realm)
  * @param max_nc the maximum allowed nc (Nonce Count) value, if client's nc
  *               exceeds the specified value then MHD_DAUTH_NONCE_STALE is
  *               returned;
  *               if zero is specified then daemon default value is used.
  * @param mqop the QOP to use
  * @param malgo digest algorithms allowed to use, fail if algorithm used
  *               by the client is not allowed by this parameter
  * @return #MHD_DAUTH_OK if authenticated,
  *         the error code otherwise
  * @ingroup authentication
  */
 MHD_EXTERN_ enum MHD_DigestAuthResult
 MHD_digest_auth_check (struct MHD_Request *MHD_RESTRICT request,
                        const char *MHD_RESTRICT realm,
                        const char *MHD_RESTRICT username,
                        const char *MHD_RESTRICT password,
                        uint_fast32_t max_nc,
                        enum MHD_DigestAuthMultiQOP mqop,
                        enum MHD_DigestAuthMultiAlgo malgo)
 MHD_FN_PAR_NONNULL_ALL_
 MHD_FN_PAR_CSTR_ (2) MHD_FN_PAR_CSTR_ (3) MHD_FN_PAR_CSTR_ (4);
 
 
 /**
  * Calculate userdigest, return it as a binary data.
  *
  * The "userdigest" is the hash of the "username:realm:password" string.
  *
  * The "userdigest" can be used to avoid storing the password in clear text
  * in database/files
  *
  * This function is designed to improve security of stored credentials,
  * the "userdigest" does not improve security of the authentication process.
  *
  * The results can be used to store username & userdigest pairs instead of
  * username & password pairs. To further improve security, application may
  * store username & userhash & userdigest triplets.
  *
  * @param algo the digest algorithm
  * @param username the username
  * @param realm the realm
  * @param password the password
  * @param bin_buf_size the size of the @a userdigest_bin buffer, must be
  *                     at least #MHD_digest_get_hash_size() bytes long
  * @param[out] userdigest_bin the output buffer for userdigest;
  *                            if this function succeeds, then this buffer has
  *                            #MHD_digest_get_hash_size() bytes of
  *                            userdigest upon return
  * @return #MHD_SC_OK on success,
  *         #MHD_SC_OUT_BUFF_TOO_SMALL if @a bin_buf_size is too small,
  *         #MHD_SC_HASH_FAILED if hashing failed,
  *         #MHD_SC_AUTH_DIGEST_ALGO_NOT_SUPPORTED if requested @a algo is
  *                                                unknown or unsupported.
  * @sa #MHD_digest_auth_check_digest()
  * @ingroup authentication
  */
 MHD_EXTERN_ enum MHD_StatusCode
 MHD_digest_auth_calc_userdigest (enum MHD_DigestAuthAlgo algo,
                                  const char *MHD_RESTRICT username,
                                  const char *MHD_RESTRICT realm,
                                  const char *MHD_RESTRICT password,
                                  size_t bin_buf_size,
                                  void *MHD_RESTRICT userdigest_bin)
 MHD_FN_PURE_ MHD_FN_PAR_NONNULL_ALL_
 MHD_FN_PAR_CSTR_ (2)
 MHD_FN_PAR_CSTR_ (3)
 MHD_FN_PAR_CSTR_ (4)
 MHD_FN_PAR_OUT_SIZE_ (6,5);
 
 
 /**
  * Authenticates the authorization header sent by the client by using
  * hash of "username:realm:password".
  *
  * If RFC2069 mode is allowed by setting bit #MHD_DIGEST_AUTH_QOP_NONE in
  * @a mqop and the client uses this mode, then server generated nonces are
  * used as one-time nonces because nonce-count is not supported in this old RFC.
  * Communication in this mode is very inefficient, especially if the client
  * requests several resources one-by-one as for every request a new nonce must
  * be generated and client repeats all requests twice (first time to get a new
  * nonce and second time to perform an authorised request).
  *
  * @param request the request
  * @param realm the realm for authorization of the client
  * @param username the username to be authenticated, must be in clear text
  *                 even if userhash is used by the client
  * @param userdigest_size the size of the @a userdigest in bytes, must match the
  *                        hashing algorithm (see #MHD_MD5_DIGEST_SIZE,
  *                        #MHD_SHA256_DIGEST_SIZE, #MHD_SHA512_256_DIGEST_SIZE,
  *                        #MHD_digest_get_hash_size())
  * @param userdigest the precalculated binary hash of the string
  *                   "username:realm:password",
  *                   see #MHD_digest_auth_calc_userdigest()
  * @param max_nc the maximum allowed nc (Nonce Count) value, if client's nc
  *               exceeds the specified value then MHD_DAUTH_NONCE_STALE is
  *               returned;
  *               if zero is specified then daemon default value is used.
  * @param mqop the QOP to use
  * @param malgo digest algorithms allowed to use, fail if algorithm used
  *              by the client is not allowed by this parameter;
  *              more than one base algorithms (MD5, SHA-256, SHA-512/256)
  *              cannot be used at the same time for this function
  *              as @a userdigest must match specified algorithm
  * @return #MHD_DAUTH_OK if authenticated,
  *         the error code otherwise
  * @sa #MHD_digest_auth_calc_userdigest()
  * @ingroup authentication
  */
 MHD_EXTERN_ enum MHD_DigestAuthResult
 MHD_digest_auth_check_digest (struct MHD_Request *MHD_RESTRICT request,
                               const char *MHD_RESTRICT realm,
                               const char *MHD_RESTRICT username,
                               size_t userdigest_size,
                               const void *MHD_RESTRICT userdigest,
                               uint_fast32_t max_nc,
                               enum MHD_DigestAuthMultiQOP mqop,
                               enum MHD_DigestAuthMultiAlgo malgo)
 MHD_FN_PAR_NONNULL_ALL_
 MHD_FN_PAR_CSTR_ (2)
 MHD_FN_PAR_CSTR_ (3)
 MHD_FN_PAR_IN_SIZE_ (5, 4);
 
 
 /**
  * Add Digest Authentication "challenge" to the response.
  *
  * The response must have #MHD_HTTP_STATUS_UNAUTHORIZED status code.
  *
  * If @a mqop allows both RFC 2069 (#MHD_DIGEST_AUTH_QOP_NONE) and other QOP
  * values, then the "challenge" is formed like if MHD_DIGEST_AUTH_QOP_NONE bit
  * was not set, because such "challenge" should be backward-compatible with
  * RFC 2069.
  *
  * If @a mqop allows only MHD_DIGEST_AUTH_MULT_QOP_NONE, then the response is
  * formed in strict accordance with RFC 2069 (no 'qop', no 'userhash', no
  * 'charset'). For better compatibility with clients, it is recommended (but
  * not required) to set @a domain to NULL in this mode.
  *
  * New nonces are generated each time when the resulting response is used.
  *
  * See RFC 7616, section 3.3 for details.
  *
  * @param response the response to update; should contain the "access denied"
  *                 body;
  *                 note: this function sets the "WWW Authenticate" header and
  *                 the caller should not set this header;
  *                 the response must have #MHD_HTTP_STATUS_UNAUTHORIZED status
  *                 code;
  *                 the NULL is tolerated (the result is
  *                 #MHD_SC_RESP_POINTER_NULL)
  * @param realm the realm presented to the client
  * @param opaque the string for opaque value, can be NULL, but NULL is
  *               not recommended for better compatibility with clients;
  *               the recommended format is hex or Base64 encoded string
  * @param domain the optional space-separated list of URIs for which the
  *               same authorisation could be used, URIs can be in form
  *               "path-absolute" (the path for the same host with initial slash)
  *               or in form "absolute-URI" (the full path with protocol), in
  *               any case client may assume that URI is in the same "protection
  *               space" if it starts with any of values specified here;
  *               could be NULL (clients typically assume that the same
  *               credentials could be used for any URI on the same host);
  *               this list provides information for the client only and does
  *               not actually restrict anything on the server side
  * @param indicate_stale if set to #MHD_YES then indication of stale nonce used
  *                       in the client's request is indicated by adding
  *                       'stale=true' to the authentication header, this
  *                       instructs the client to retry immediately with the new
  *                       nonce and the same credentials, without asking user
  *                       for the new password
  * @param mqop the QOP to use
  * @param malgo digest algorithm to use; if several algorithms are allowed
  *              then one challenge for each allowed algorithm is added
  * @param userhash_support if set to #MHD_YES then support of userhash is
  *                         indicated, allowing client to provide
  *                         hash("username:realm") instead of the username in
  *                         clear text;
  *                         note that clients are allowed to provide the username
  *                         in cleartext even if this parameter set to non-zero;
  *                         when userhash is used, application must be ready to
  *                         identify users by provided userhash value instead of
  *                         username; see #MHD_digest_auth_calc_userhash() and
  *                         #MHD_digest_auth_calc_userhash_hex()
  * @param prefer_utf8 if not set to #MHD_NO, parameter 'charset=UTF-8' is
  *                    added, indicating for the client that UTF-8 encoding for
  *                    the username is preferred
  * @return #MHD_SC_OK if succeed,
  *         #MHD_SC_TOO_LATE if the response has been already "frozen" (used to
  *         create an action),
  *         #MHD_SC_RESP_HEADERS_CONFLICT if Digest Authentication "challenge"
  *         has been added already,
  *         #MHD_SC_RESP_POINTER_NULL if @a response is NULL,
  *         #MHD_SC_RESP_HTTP_CODE_NOT_SUITABLE is response status code is wrong,
  *         #MHD_SC_RESP_HEADER_VALUE_INVALID if @a realm, @a opaque or @a domain
  *         have wrong characters or zero length (for @a realm),
  *         #MHD_SC_RESPONSE_HEADER_MEM_ALLOC_FAILED if memory allocation failed,
  *         or other error code if failed
  * @ingroup authentication
  */
 MHD_EXTERN_ enum MHD_StatusCode
 MHD_response_add_auth_digest_challenge (
   struct MHD_Response *MHD_RESTRICT response,
   const char *MHD_RESTRICT realm,
   const char *MHD_RESTRICT opaque,
   const char *MHD_RESTRICT domain,
   enum MHD_Bool indicate_stale,
   enum MHD_DigestAuthMultiQOP mqop,
   enum MHD_DigestAuthMultiAlgo malgo,
   enum MHD_Bool userhash_support,
   enum MHD_Bool prefer_utf8)
 MHD_FN_PAR_NONNULL_ (2) MHD_FN_PAR_CSTR_ (2)
 MHD_FN_PAR_CSTR_ (3) MHD_FN_PAR_CSTR_ (4);
 
 
 /* Application may define MHD_NO_STATIC_INLINE macro before including
    libmicrohttpd headers to disable static inline functions in the headers. */
 #ifndef MHD_NO_STATIC_INLINE
 
 /**
  * Create action to reply with Digest Authentication "challenge".
  *
  * The @a response must have #MHD_HTTP_STATUS_UNAUTHORIZED status code.
  *
  * See RFC 7616, section 3.3 for details.
  *
  * @param request the request to create the action for
  * @param realm the realm presented to the client
  * @param opaque the string for opaque value, can be NULL, but NULL is
  *               not recommended for better compatibility with clients;
  *               the recommended format is hex or Base64 encoded string
  * @param domain the optional space-separated list of URIs for which the
  *               same authorisation could be used, URIs can be in form
  *               "path-absolute" (the path for the same host with initial slash)
  *               or in form "absolute-URI" (the full path with protocol), in
  *               any case client may assume that URI is in the same "protection
  *               space" if it starts with any of values specified here;
  *               could be NULL (clients typically assume that the same
  *               credentials could be used for any URI on the same host);
  *               this list provides information for the client only and does
  *               not actually restrict anything on the server side
  * @param indicate_stale if set to #MHD_YES then indication of stale nonce used
  *                       in the client's request is indicated by adding
  *                       'stale=true' to the authentication header, this
  *                       instructs the client to retry immediately with the new
  *                       nonce and the same credentials, without asking user
  *                       for the new password
  * @param mqop the QOP to use
  * @param malgo digest algorithm to use; if several algorithms are allowed
  *              then one challenge for each allowed algorithm is added
  * @param userhash_support if set to #MHD_YES then support of userhash is
  *                         indicated, allowing client to provide
  *                         hash("username:realm") instead of the username in
  *                         clear text;
  *                         note that clients are allowed to provide the username
  *                         in cleartext even if this parameter set to non-zero;
  *                         when userhash is used, application must be ready to
  *                         identify users by provided userhash value instead of
  *                         username; see #MHD_digest_auth_calc_userhash() and
  *                         #MHD_digest_auth_calc_userhash_hex()
  * @param prefer_utf8 if not set to #MHD_NO, parameter 'charset=UTF-8' is
  *                    added, indicating for the client that UTF-8 encoding for
  *                    the username is preferred
  * @param response the response to update; should contain the "access denied"
  *                 body;
  *                 note: this function sets the "WWW Authenticate" header and
  *                 the caller should not set this header;
  *                 the response must have #MHD_HTTP_STATUS_UNAUTHORIZED status
  *                 code;
  *                 the NULL is tolerated (the result is
  *                 #MHD_SC_RESP_POINTER_NULL)
  * @param abort_if_failed if set to #MHD_NO the response will be used even if
  *                        failed to add Basic Authentication "challenge",
  *                        if not set to #MHD_NO the request will be aborted
  *                        if the "challenge" could not be added.
  * @return pointer to the action, the action must be consumed
  *         otherwise response object may leak;
  *         NULL if failed or if any action has been already created for
  *         the @a request;
  *         when failed the response object is consumed and need not
  *         to be "destroyed"
  * @ingroup authentication
  */
 MHD_STATIC_INLINE_
 MHD_FN_PAR_NONNULL_ (1)
 MHD_FN_PAR_NONNULL_ (2) MHD_FN_PAR_CSTR_ (2)
 const struct MHD_Action *
 MHD_action_digest_auth_challenge (struct MHD_Request *MHD_RESTRICT request,
                                   const char *MHD_RESTRICT realm,
                                   const char *MHD_RESTRICT opaque,
                                   const char *MHD_RESTRICT domain,
                                   enum MHD_Bool indicate_stale,
                                   enum MHD_DigestAuthMultiQOP mqop,
                                   enum MHD_DigestAuthMultiAlgo malgo,
                                   enum MHD_Bool userhash_support,
                                   enum MHD_Bool prefer_utf8,
                                   struct MHD_Response *MHD_RESTRICT response,
                                   enum MHD_Bool abort_if_failed)
 {
   if ((MHD_SC_OK !=
        MHD_response_add_auth_digest_challenge (response, realm, opaque, domain,
                                                indicate_stale, mqop, malgo,
                                                userhash_support, prefer_utf8))
       && (MHD_NO != abort_if_failed))
   {
     MHD_response_destroy (response);
     return MHD_action_abort_request (request);
   }
   return MHD_action_from_response (request, response);
 }
 
 
 MHD_STATIC_INLINE_END_
 
 /**
  * Create action to reply with Digest Authentication "challenge".
  *
  * The @a response must have #MHD_HTTP_STATUS_UNAUTHORIZED status code.
  *
  * If the @a response object cannot be extended with the "challenge",
  * the @a response is used to reply without the "challenge".
  *
  * @param request the request to create the action for
  * @param realm the realm presented to the client
  * @param opaque the string for opaque value, can be NULL, but NULL is
  *               not recommended for better compatibility with clients;
  *               the recommended format is hex or Base64 encoded string
  * @param domain the optional space-separated list of URIs for which the
  *               same authorisation could be used, URIs can be in form
  *               "path-absolute" (the path for the same host with initial slash)
  *               or in form "absolute-URI" (the full path with protocol), in
  *               any case client may assume that URI is in the same "protection
  *               space" if it starts with any of values specified here;
  *               could be NULL (clients typically assume that the same
  *               credentials could be used for any URI on the same host);
  *               this list provides information for the client only and does
  *               not actually restrict anything on the server side
  * @param indicate_stale if set to #MHD_YES then indication of stale nonce used
  *                       in the client's request is indicated by adding
  *                       'stale=true' to the authentication header, this
  *                       instructs the client to retry immediately with the new
  *                       nonce and the same credentials, without asking user
  *                       for the new password
  * @param mqop the QOP to use
  * @param algo digest algorithm to use; if several algorithms are allowed
  *             then one challenge for each allowed algorithm is added
  * @param userhash_support if set to #MHD_YES then support of userhash is
  *                         indicated, allowing client to provide
  *                         hash("username:realm") instead of the username in
  *                         clear text;
  *                         note that clients are allowed to provide the username
  *                         in cleartext even if this parameter set to non-zero;
  *                         when userhash is used, application must be ready to
  *                         identify users by provided userhash value instead of
  *                         username; see #MHD_digest_auth_calc_userhash() and
  *                         #MHD_digest_auth_calc_userhash_hex()
  * @param prefer_utf8 if not set to #MHD_NO, parameter 'charset=UTF-8' is
  *                    added, indicating for the client that UTF-8 encoding for
  *                    the username is preferred
  * @param response the response to update; should contain the "access denied"
  *                 body;
  *                 note: this function sets the "WWW Authenticate" header and
  *                 the caller should not set this header;
  *                 the response must have #MHD_HTTP_STATUS_UNAUTHORIZED status
  *                 code;
  *                 the NULL is tolerated (the result is
  *                 #MHD_SC_RESP_POINTER_NULL)
  * @return pointer to the action, the action must be consumed
  *         otherwise response object may leak;
  *         NULL if failed or if any action has been already created for
  *         the @a request;
  *         when failed the response object is consumed and need not
  *         to be "destroyed"
  * @ingroup authentication
  */
 #define MHD_action_digest_auth_challenge_p(rq,rlm,opq,dmn,stl,mqop,malgo, \
                                            uh,utf,resp) \
         MHD_action_digest_auth_challenge ((rq),(rlm),(opq),(dmn),(stl),(mqop), \
                                           (malgo),(uh),(utf),(resp),MHD_NO)
 
 
 /**
  * Create action to reply with Digest Authentication "challenge".
  *
  * The @a response must have #MHD_HTTP_STATUS_UNAUTHORIZED status code.
  *
  * If the @a response object cannot be extended with the "challenge",
  * the @a response is aborted.
  *
  * @param request the request to create the action for
  * @param realm the realm presented to the client
  * @param opaque the string for opaque value, can be NULL, but NULL is
  *               not recommended for better compatibility with clients;
  *               the recommended format is hex or Base64 encoded string
  * @param domain the optional space-separated list of URIs for which the
  *               same authorisation could be used, URIs can be in form
  *               "path-absolute" (the path for the same host with initial slash)
  *               or in form "absolute-URI" (the full path with protocol), in
  *               any case client may assume that URI is in the same "protection
  *               space" if it starts with any of values specified here;
  *               could be NULL (clients typically assume that the same
  *               credentials could be used for any URI on the same host);
  *               this list provides information for the client only and does
  *               not actually restrict anything on the server side
  * @param indicate_stale if set to #MHD_YES then indication of stale nonce used
  *                       in the client's request is indicated by adding
  *                       'stale=true' to the authentication header, this
  *                       instructs the client to retry immediately with the new
  *                       nonce and the same credentials, without asking user
  *                       for the new password
  * @param mqop the QOP to use
  * @param algo digest algorithm to use; if several algorithms are allowed
  *             then one challenge for each allowed algorithm is added
  * @param userhash_support if set to #MHD_YES then support of userhash is
  *                         indicated, allowing client to provide
  *                         hash("username:realm") instead of the username in
  *                         clear text;
  *                         note that clients are allowed to provide the username
  *                         in cleartext even if this parameter set to non-zero;
  *                         when userhash is used, application must be ready to
  *                         identify users by provided userhash value instead of
  *                         username; see #MHD_digest_auth_calc_userhash() and
  *                         #MHD_digest_auth_calc_userhash_hex()
  * @param prefer_utf8 if not set to #MHD_NO, parameter 'charset=UTF-8' is
  *                    added, indicating for the client that UTF-8 encoding for
  *                    the username is preferred
  * @param response the response to update; should contain the "access denied"
  *                 body;
  *                 note: this function sets the "WWW Authenticate" header and
  *                 the caller should not set this header;
  *                 the response must have #MHD_HTTP_STATUS_UNAUTHORIZED status
  *                 code;
  *                 the NULL is tolerated (the result is
  *                 #MHD_SC_RESP_POINTER_NULL)
  * @return pointer to the action, the action must be consumed
  *         otherwise response object may leak;
  *         NULL if failed or if any action has been already created for
  *         the @a request;
  *         when failed the response object is consumed and need not
  *         to be "destroyed"
  * @ingroup authentication
  */
 #define MHD_action_digest_auth_challenge_a(rq,rlm,opq,dmn,stl,mqop,malgo, \
                                            uh,utf,resp) \
         MHD_action_digest_auth_challenge ((rq),(rlm),(opq),(dmn),(stl),(mqop), \
                                           (malgo),(uh),(utf),(resp),MHD_YES)
 
 #endif /* ! MHD_NO_STATIC_INLINE */
 
 
 /**
  * Add Basic Authentication "challenge" to the response.
  *
  * The response must have #MHD_HTTP_STATUS_UNAUTHORIZED status code.
  *
  * If access to any resource should be limited to specific users, authenticated
  * by Basic Authentication mechanism, and the request for this resource does not
  * have Basic Authentication information (see #MHD_AuthBasicCreds), then response
  * with Basic Authentication "challenge" should be sent. This works as
  * an indication that Basic Authentication should be used for the access.
  *
  * See RFC 7617, section-2 for details.
  *
  * @param response the reply to send; should contain the "access denied"
  *                 body;
  *                 note: this function sets the "WWW Authenticate" header and
  *                 the caller should not set this header;
  *                 the response must have #MHD_HTTP_STATUS_UNAUTHORIZED status
  *                 code;
  *                 the NULL is tolerated (the result is
  *                 #MHD_SC_RESP_POINTER_NULL)
  * @param realm the realm presented to the client
  * @param prefer_utf8 if not set to #MHD_NO, parameter'charset="UTF-8"' will
  *                    be added, indicating for client that UTF-8 encoding
  *                    is preferred
  * @return #MHD_SC_OK if succeed,
  *         #MHD_SC_TOO_LATE if the response has been already "frozen" (used to
  *         create an action),
  *         #MHD_SC_RESP_HEADERS_CONFLICT if Basic Authentication "challenge"
  *         has been added already,
  *         #MHD_SC_RESP_POINTER_NULL if @a response is NULL,
  *         #MHD_SC_RESP_HTTP_CODE_NOT_SUITABLE is response status code is wrong,
  *         #MHD_SC_RESP_HEADER_VALUE_INVALID if realm is zero-length or has CR
  *         or LF characters,
  *         #MHD_SC_RESPONSE_HEADER_MEM_ALLOC_FAILED if memory allocation failed,
  *         or other error code if failed
  * @ingroup authentication
  */
 MHD_EXTERN_ enum MHD_StatusCode
 MHD_response_add_auth_basic_challenge (
   struct MHD_Response *MHD_RESTRICT response,
   const char *MHD_RESTRICT realm,
   enum MHD_Bool prefer_utf8)
 MHD_FN_PAR_NONNULL_ (2) MHD_FN_PAR_CSTR_ (2);
 
 /* Application may define MHD_NO_STATIC_INLINE macro before including
    libmicrohttpd headers to disable static inline functions in the headers. */
 #ifndef MHD_NO_STATIC_INLINE
 
 /**
  * Create action to reply with Basic Authentication "challenge".
  *
  * The @a response must have #MHD_HTTP_STATUS_UNAUTHORIZED status code.
  *
  * If access to any resource should be limited to specific users, authenticated
  * by Basic Authentication mechanism, and the request for this resource does not
  * have Basic Authentication information (see #MHD_AuthBasicCreds), then response
  * with Basic Authentication "challenge" should be sent. This works as
  * an indication that Basic Authentication should be used for the access.
  *
  * See RFC 7617, section-2 for details.
  *
  * @param request the request to create the action for
  * @param realm the realm presented to the client
  * @param prefer_utf8 if not set to #MHD_NO, parameter'charset="UTF-8"' will
  *                    be added, indicating for client that UTF-8 encoding
  *                    is preferred
  * @param response the reply to send; should contain the "access denied"
  *                 body;
  *                 note: this function adds the "WWW Authenticate" header in
  *                 the response and the caller should not set this header;
  *                 the response must have #MHD_HTTP_STATUS_UNAUTHORIZED status
  *                 code;
  *                 the NULL is tolerated (the result is
  *                 #MHD_action_abort_request())
  * @param abort_if_failed if set to #MHD_NO the response will be used even if
  *                        failed to add Basic Authentication "challenge",
  *                        if not set to #MHD_NO the request will be aborted
  *                        if the "challenge" could not be added.
  * @return pointer to the action, the action must be consumed
  *         otherwise response object may leak;
  *         NULL if failed or if any action has been already created for
  *         the @a request;
  *         when failed the response object is consumed and need not
  *         to be "destroyed"
  * @ingroup authentication
  */
 MHD_STATIC_INLINE_
 MHD_FN_PAR_NONNULL_ (1)
 MHD_FN_PAR_NONNULL_ (2) MHD_FN_PAR_CSTR_ (2)
 const struct MHD_Action *
 MHD_action_basic_auth_challenge (struct MHD_Request *MHD_RESTRICT request,
                                  const char *MHD_RESTRICT realm,
                                  enum MHD_Bool prefer_utf8,
                                  struct MHD_Response *MHD_RESTRICT response,
                                  enum MHD_Bool abort_if_failed)
 {
   if ((MHD_SC_OK !=
        MHD_response_add_auth_basic_challenge (response, realm, prefer_utf8))
       && (MHD_NO != abort_if_failed))
   {
     MHD_response_destroy (response);
     return MHD_action_abort_request (request);
   }
   return MHD_action_from_response (request, response);
 }
 
 
 MHD_STATIC_INLINE_END_
 
 
 /**
  * Create action to reply with Basic Authentication "challenge".
  *
  * The @a response must have #MHD_HTTP_STATUS_UNAUTHORIZED status code.
  *
  * If the @a response object cannot be extended with the "challenge",
  * the @a response will be used to reply without the "challenge".
  *
  * @param request the request to create the action for
  * @param realm the realm presented to the client
  * @param prefer_utf8 if not set to #MHD_NO, parameter'charset="UTF-8"' will
  *                    be added, indicating for client that UTF-8 encoding
  *                    is preferred
  * @param response the reply to send; should contain the "access denied"
  *                 body;
  *                 note: this function adds the "WWW Authenticate" header in
  *                 the response and the caller should not set this header;
  *                 the response must have #MHD_HTTP_STATUS_UNAUTHORIZED status
  *                 code;
  *                 the NULL is tolerated (the result is
  *                 #MHD_action_abort_request())
  * @return pointer to the action, the action must be consumed
  *         otherwise response object may leak;
  *         NULL if failed or if any action has been already created for
  *         the @a request;
  *         when failed the response object is consumed and need not
  *         to be "destroyed"
  * @ingroup authentication
  */
 #define MHD_action_basic_auth_challenge_p(request,realm,prefer_utf8,response) \
         MHD_action_basic_auth_challenge ((request), (realm), (prefer_utf8), \
                                          (response), MHD_NO)
 
 /**
  * Create action to reply with Basic Authentication "challenge".
  *
  * The @a response must have #MHD_HTTP_STATUS_UNAUTHORIZED status code.
  *
  * If the @a response object cannot be extended with the "challenge",
  * the request will be aborted.
  *
  * @param request the request to create the action for
  * @param realm the realm presented to the client
  * @param prefer_utf8 if not set to #MHD_NO, parameter'charset="UTF-8"' will
  *                    be added, indicating for client that UTF-8 encoding
  *                    is preferred
  * @param response the reply to send; should contain the "access denied"
  *                 body;
  *                 note: this function adds the "WWW Authenticate" header in
  *                 the response and the caller should not set this header;
  *                 the response must have #MHD_HTTP_STATUS_UNAUTHORIZED status
  *                 code;
  *                 the NULL is tolerated (the result is
  *                 #MHD_action_abort_request())
  * @return pointer to the action, the action must be consumed
  *         otherwise response object may leak;
  *         NULL if failed or if any action has been already created for
  *         the @a request;
  *         when failed the response object is consumed and need not
  *         to be "destroyed"
  * @ingroup authentication
  */
 #define MHD_action_basic_auth_challenge_a(request,realm,prefer_utf8,response) \
         MHD_action_basic_auth_challenge ((request), (realm), (prefer_utf8), \
                                          (response), MHD_YES)
 
 #endif /* ! MHD_NO_STATIC_INLINE */
 
 
 /**
  * Information decoded from Basic Authentication client's header.
  *
  * @see #MHD_REQUEST_INFO_DYNAMIC_AUTH_BASIC_CREDS
  */
 struct MHD_AuthBasicCreds
 {
   /**
    * The username
    */
   struct MHD_String username;
 
   /**
    * The password, string pointer may be NULL if password is not encoded
    * by the client.
    */
   struct MHD_StringNullable password;
 };
 
 /* ********************** (f) Introspection ********************** */
 
 
 /**
  * Types of information about MHD, used by #MHD_lib_get_info_fixed_sz().
  * This information is not changed at run-time.
  */
 enum MHD_FIXED_ENUM_APP_SET_ MHD_LibInfoFixed
 {
   /* * Basic MHD information * */
 
   /**
    * Get the MHD version as a number.
    * The result is placed in @a v_version_num_uint32 member.
    */
   MHD_LIB_INFO_FIXED_VERSION_NUM = 0
   ,
   /**
    * Get the MHD version as a string.
    * The result is placed in @a v_version_string member.
    */
   MHD_LIB_INFO_FIXED_VERSION_STRING = 1
   ,
 
   /* * Basic MHD features, buid-time configurable * */
   /* These features should be always available unless the library was
    * not compiled specifically for some embedded project.
    * Exceptions are marked explicitly in the description. */
 
   /**
    * Get whether messages are supported. If supported then messages can be
    * printed to stderr or to an external logger.
    * The result is placed in @a v_support_log_messages_bool member.
    */
   MHD_LIB_INFO_FIXED_SUPPORT_LOG_MESSAGES = 11
   ,
   /**
    * Get whether detailed automatic HTTP reply messages are supported.
    * If supported then automatic responses have bodies with text explaining
    * the error details.
    * Automatic responses are sent by MHD automatically when client is violating
    * HTTP specification, for example, the request header has whitespace in
    * header name or request's "Content-Length" header has non-number value.
    * The result is placed in @a v_support_auto_replies_bodies_bool member.
    */
   MHD_LIB_INFO_FIXED_SUPPORT_AUTO_REPLIES_BODIES = 12
   ,
   /**
    * Get whether MHD was built with debug asserts disabled.
    * These asserts enabled only on special debug builds.
    * For debug builds the error log is always enabled.
    * The result is placed in @a v_is_non_debug_bool member.
    */
   MHD_LIB_INFO_FIXED_IS_NON_DEBUG = 13
   ,
   /**
    * Get whether MHD supports threads.
    * The result is placed in @a v_support_threads_bool member.
    */
   MHD_LIB_INFO_FIXED_SUPPORT_THREADS = 14
   ,
   /**
    * Get whether automatic parsing of HTTP Cookie header is supported.
    * If disabled, no #MHD_VK_COOKIE will be generated by MHD.
    * The result is placed in @a v_support_cookie_parser_bool member.
    */
   MHD_LIB_INFO_FIXED_SUPPORT_COOKIE_PARSER = 15
   ,
   /**
    * Get whether postprocessor is supported. If supported then
    * #MHD_action_post_processor() can be used.
    * The result is placed in @a v_support_post_parser_bool member.
    */
   MHD_LIB_INFO_FIXED_SUPPORT_POST_PARSER = 16
   ,
   /**
    * Get whether HTTP "Upgrade" is supported.
    * If supported then #MHD_action_upgrade() can be used.
    * The result is placed in @a v_support_upgrade_bool member.
    */
   MHD_LIB_INFO_FIXED_SUPPORT_UPGRADE = 17
   ,
   /**
    * Get whether HTTP Basic authorization is supported. If supported
    * then functions #MHD_action_basic_auth_required_response ()
    * and #MHD_REQUEST_INFO_DYNAMIC_AUTH_BASIC_CREDS can be used.
    * The result is placed in @a v_support_auth_basic_bool member.
    */
   MHD_LIB_INFO_FIXED_SUPPORT_AUTH_BASIC = 20
   ,
   /**
    * Get whether HTTP Digest authorization is supported. If
    * supported then options #MHD_D_O_RANDOM_ENTROPY,
    * #MHD_D_O_DAUTH_MAP_SIZE and functions
    * #MHD_action_digest_auth_required_response () and
    * #MHD_digest_auth_check() can be used.
    * The result is placed in @a v_support_auth_digest_bool member.
    */
   MHD_LIB_INFO_FIXED_SUPPORT_AUTH_DIGEST = 21
   ,
   /**
    * Get whether the early version the Digest Authorization (RFC 2069) is
    * supported (digest authorisation without QOP parameter).
    * Currently it is always supported if Digest Auth module is built.
    * The result is placed in @a v_support_digest_auth_rfc2069_bool member.
    */
   MHD_LIB_INFO_FIXED_SUPPORT_DIGEST_AUTH_RFC2069 = 22
   ,
   /**
    * Get whether the MD5-based hashing algorithms are supported for Digest
    * Authorization and the type of the implementation if supported.
    * Currently it is always supported if Digest Auth module is built
    * unless manually disabled in a custom build.
    * The result is placed in @a v_type_digest_auth_md5_algo_type member.
    */
   MHD_LIB_INFO_FIXED_TYPE_DIGEST_AUTH_MD5 = 23
   ,
   /**
    * Get whether the SHA-256-based hashing algorithms are supported for Digest
    * Authorization and the type of the implementation if supported.
    * Currently it is always supported if Digest Auth module is built
    * unless manually disabled in a custom build.
    * The result is placed in @a v_type_digest_auth_sha256_algo_type member.
    */
   MHD_LIB_INFO_FIXED_TYPE_DIGEST_AUTH_SHA256 = 24
   ,
   /**
    * Get whether the SHA-512/256-based hashing algorithms are supported
    * Authorization and the type of the implementation if supported.
    * Currently it is always supported if Digest Auth module is built
    * unless manually disabled in a custom build.
    * The result is placed in @a v_type_digest_auth_sha512_256_algo_type member.
    */
   MHD_LIB_INFO_FIXED_TYPE_DIGEST_AUTH_SHA512_256 = 25
   ,
   /**
    * Get whether QOP with value 'auth-int' (authentication with integrity
    * protection) is supported for Digest Authorization.
    * Currently it is always not supported.
    * The result is placed in @a v_support_digest_auth_auth_int_bool member.
    */
   MHD_LIB_INFO_FIXED_SUPPORT_DIGEST_AUTH_AUTH_INT = 28
   ,
   /**
    * Get whether 'session' algorithms (like 'MD5-sess') are supported for Digest
    * Authorization.
    * Currently it is always not supported.
    * The result is placed in @a v_support_digest_auth_algo_session_bool member.
    */
   MHD_LIB_INFO_FIXED_SUPPORT_DIGEST_AUTH_ALGO_SESSION = 29
   ,
   /**
    * Get whether 'userhash' is supported for Digest Authorization.
    * Currently it is always supported if Digest Auth module is built.
    * The result is placed in @a v_support_digest_auth_userhash_bool member.
    */
   MHD_LIB_INFO_FIXED_SUPPORT_DIGEST_AUTH_USERHASH = 30
   ,
 
   /* * Platform-dependent features, some are configurable at build-time * */
   /* These features depends on the platform, third-party libraries and
    * the toolchain.
    * Some of the features can be disabled or selected at build-time. */
   /**
    * Get sockets polling functions/techniques supported by this MHD build.
    * Some functions can be disabled (like epoll) in kernel, this is not
    * checked.
    * The result is placed in @a v_types_sockets_polling member.
    */
   MHD_LIB_INFO_FIXED_TYPES_SOCKETS_POLLING = 60
   ,
   /**
    * Get whether aggregate FD external polling is supported.
    * The result is placed in @a v_support_aggregate_fd_bool member.
    */
   MHD_LIB_INFO_FIXED_SUPPORT_AGGREGATE_FD = 61
   ,
   /**
    * Get whether IPv6 is supported on the platform and IPv6-only listen socket
    * can be used.
    * The result is placed in @a v_ipv6 member.
    * @note The platform may have disabled IPv6 at run-time, it is not checked
    *       by this information type.
    */
   MHD_LIB_INFO_FIXED_TYPE_IPV6 = 62
   ,
   /**
    * Get whether TCP Fast Open is supported by MHD build.
    * If supported then option #MHD_D_O_TCP_FASTOPEN can be used.
    * The result is placed in @a v_support_tcp_fastopen_bool member.
    */
   MHD_LIB_INFO_FIXED_SUPPORT_TCP_FASTOPEN = 64
   ,
   /**
    * Get whether MHD support automatic detection of bind port number.
    * @sa #MHD_D_O_BIND_PORT
    * The result is placed in @a v_has_autodetect_bind_port_bool member.
    */
   MHD_LIB_INFO_FIXED_HAS_AUTODETECT_BIND_PORT = 65
   ,
   /**
    * Get whether MHD use system's sendfile() function to send
    * file-FD based responses over non-TLS connections.
    * The result is placed in @a v_has_sendfile_bool member.
    */
   MHD_LIB_INFO_FIXED_HAS_SENDFILE = 66
   ,
   /**
    * Get whether MHD supports automatic SIGPIPE suppression within internal
    * events loop (MHD's managed threads).
    * If SIGPIPE suppression is not supported, application must handle
    * SIGPIPE signal by itself whem using MHD with internal events loop.
    * If the platform does not have SIGPIPE the result is #MHD_YES.
    * The result is placed in @a v_has_autosuppress_sigpipe_int_bool member.
    */
   MHD_LIB_INFO_FIXED_HAS_AUTOSUPPRESS_SIGPIPE_INT = 80
   ,
   /**
    * Get whether MHD supports automatic SIGPIPE suppression when used with
    * extenal events loop (in application thread).
    * If SIGPIPE suppression is not supported, application must handle
    * SIGPIPE signal by itself whem using MHD with external events loop.
    * If the platform does not have SIGPIPE the result is #MHD_YES.
    * The result is placed in @a v_has_autosuppress_sigpipe_ext_bool member.
    */
   MHD_LIB_INFO_FIXED_HAS_AUTOSUPPRESS_SIGPIPE_EXT = 81
   ,
   /**
    * Get whether MHD sets names on generated threads.
    * The result is placed in @a v_has_thread_names_bool member.
    */
   MHD_LIB_INFO_FIXED_HAS_THREAD_NAMES = 82
   ,
   /**
    * Get the type of supported inter-thread communication.
    * The result is placed in @a v_type_itc member.
    */
   MHD_LIB_INFO_FIXED_TYPE_ITC = 83
   ,
   /**
    * Get whether reading files beyond 2 GiB boundary is supported.
    * If supported then #MHD_response_from_fd() can be used with sizes and
    * offsets larger than 2 GiB. If not supported value of size+offset could be
    * limited to 2 GiB.
    * The result is placed in @a v_support_large_file_bool member.
    */
   MHD_LIB_INFO_FIXED_SUPPORT_LARGE_FILE = 84
   ,
 
   /* * Platform-dependent features, some set on startup and some are
    *   configurable at build-time * */
   /* These features depends on the platform, third-party libraries availability
    * and configuration. The features can be enabled/disabled during startup
    * of the library depending on conditions.
    * Some of the features can be disabled or selected at build-time. */
   /**
    * Get whether HTTPS and which types of TLS backend(s) supported by
    * this build.
    * The result is placed in @a v_tls_backends member.
    */
   MHD_LIB_INFO_FIXED_TLS_BACKENDS = 100
   ,
   /**
   * Get whether password encrypted private key for HTTPS daemon is
   * supported by TLS backends.
   * If supported then option #MHD_D_OPTION_TLS_KEY_CERT can be used with
   * non-NULL @a mem_pass.
   * The result is placed in @a v_tls_key_password_backends member.
   */
   MHD_LIB_INFO_FIXED_TLS_KEY_PASSWORD_BACKENDS = 102
   ,
 
   /* * Sentinel * */
   /**
    * The sentinel value.
    * This value enforces specific underlying integer type for the enum.
    * Do not use.
    */
   MHD_LIB_INFO_FIXED_SENTINEL = 65535
 };
 
 /**
  * The type of the data for digest algorithm implementations.
  */
 enum MHD_FIXED_ENUM_MHD_SET_ MHD_LibInfoFixedDigestAlgoType
 {
   /**
    * The algorithm is not implemented or disabled at the build time.
    */
   MHD_LIB_INFO_FIXED_DIGEST_ALGO_TYPE_NOT_AVAILABLE = 0
   ,
   /**
    * The algorithm is implemented by MHD internal code.
    * MHD implementation of hashing can never fail.
    */
   MHD_LIB_INFO_FIXED_DIGEST_ALGO_TYPE_BUILT_IN = 1
   ,
   /**
    * The algorithm is implemented by external code that never fails.
    */
   MHD_LIB_INFO_FIXED_DIGEST_ALGO_TYPE_EXTERNAL_NEVER_FAIL = 2
   ,
   /**
    * The algorithm is implemented by external code that may hypothetically fail.
    */
   MHD_LIB_INFO_FIXED_DIGEST_ALGO_TYPE_EXTERNAL_MAY_FAIL = 3
 };
 
 /**
  * The types of the sockets polling functions/techniques supported
  */
 struct MHD_LibInfoFixedPollingFunc
 {
   /**
    * select() function for sockets polling
    */
   enum MHD_Bool func_select;
   /**
    * poll() function for sockets polling
    */
   enum MHD_Bool func_poll;
   /**
    * epoll technique for sockets polling
    */
   enum MHD_Bool tech_epoll;
 };
 
 /**
  * The types of IPv6 supported
  */
 enum MHD_FIXED_ENUM_MHD_SET_ MHD_LibInfoFixedIPv6Type
 {
   /**
    * IPv6 is not supported by this MHD build
    */
   MHD_LIB_INFO_FIXED_IPV6_TYPE_NONE = 0
   ,
   /**
    * IPv6 is supported only as "dual stack".
    * IPv4 connections can be received by IPv6 listen socket.
    */
   MHD_LIB_INFO_FIXED_IPV6_TYPE_DUAL_ONLY = 1
   ,
   /**
    * IPv6 can be used as IPv6-only (without getting IPv4 incoming connections).
    * The platform may support "dual stack" too.
    */
   MHD_LIB_INFO_FIXED_IPV6_TYPE_IPV6_PURE = 2
 };
 
 /**
  * The types of inter-thread communication
  * @note the enum can be extended in future versions with new values
  */
 enum MHD_FIXED_ENUM_MHD_SET_ MHD_LibInfoFixedITCType
 {
   /**
    * No ITC used.
    * This value is returned if MHD is built without threads support
    */
   MHD_LIB_INFO_FIXED_ITC_TYPE_NONE = 0
   ,
   /**
    * The pair of sockets are used as inter-thread communication.
    * The is the least efficient method of communication.
    */
   MHD_LIB_INFO_FIXED_ITC_TYPE_SOCKETPAIR = 1
   ,
   /**
    * The pipe is used as inter-thread communication.
    */
   MHD_LIB_INFO_FIXED_ITC_TYPE_PIPE = 2
   ,
   /**
    * The EventFD is used as inter-thread communication.
    * This is the most efficient method of communication.
    */
   MHD_LIB_INFO_FIXED_ITC_TYPE_EVENTFD = 3
 };
 
 
 /**
  * The types of the TLS (or TLS feature) backend supported/available/enabled
  * @note the enum can be extended in future versions with new members
  */
 struct MHD_LibInfoTLSType
 {
   /**
    * The TLS (or TLS feature) is supported/enabled.
    * Set to #MHD_YES if any other member is #MHD_YES.
    */
   enum MHD_Bool tls_supported;
   /**
    * The GnuTLS backend is supported/available/enabled.
    */
   enum MHD_Bool backend_gnutls;
   /**
    * The OpenSSL backend is supported/available/enabled.
    */
   enum MHD_Bool backend_openssl;
   /**
    * The MbedTLS backend is supported/available/enabled.
    */
   enum MHD_Bool backend_mbedtls;
 };
 
 /**
  * The data provided by #MHD_lib_get_info_fixed_sz()
  */
 union MHD_LibInfoFixedData
 {
   /**
    * The data for the #MHD_LIB_INFO_FIXED_VERSION_NUM query
    */
   uint_fast32_t v_version_num_uint32;
   /**
    * The data for the #MHD_LIB_INFO_FIXED_VERSION_STR query
    */
   struct MHD_String v_version_string;
   /**
    * The data for the #MHD_LIB_INFO_FIXED_SUPPORT_LOG_MESSAGES query
    */
   enum MHD_Bool v_support_log_messages_bool;
   /**
    * The data for the #MHD_LIB_INFO_FIXED_SUPPORT_AUTO_REPLIES_BODIES query
    */
   enum MHD_Bool v_support_auto_replies_bodies_bool;
   /**
    * The data for the #MHD_LIB_INFO_FIXED_IS_NON_DEBUG query
    */
   enum MHD_Bool v_is_non_debug_bool;
   /**
    * The data for the #MHD_LIB_INFO_FIXED_SUPPORT_THREADS query
    */
   enum MHD_Bool v_support_threads_bool;
   /**
    * The data for the #MHD_LIB_INFO_FIXED_SUPPORT_COOKIE_PARSER query
    */
   enum MHD_Bool v_support_cookie_parser_bool;
   /**
    * The data for the #MHD_LIB_INFO_FIXED_SUPPORT_POST_PARSER query
    */
   enum MHD_Bool v_support_post_parser_bool;
   /**
    * The data for the #MHD_LIB_INFO_FIXED_SUPPORT_UPGRADE query
    */
   enum MHD_Bool v_support_upgrade_bool;
   /**
    * The data for the #MHD_LIB_INFO_FIXED_SUPPORT_AUTH_BASIC query
    */
   enum MHD_Bool v_support_auth_basic_bool;
   /**
    * The data for the #MHD_LIB_INFO_FIXED_SUPPORT_AUTH_DIGEST query
    */
   enum MHD_Bool v_support_auth_digest_bool;
   /**
    * The data for the #MHD_LIB_INFO_FIXED_SUPPORT_DIGEST_AUTH_RFC2069 query
    */
   enum MHD_Bool v_support_digest_auth_rfc2069_bool;
   /**
    * The data for the #MHD_LIB_INFO_FIXED_TYPE_DIGEST_AUTH_MD5 query
    */
   enum MHD_LibInfoFixedDigestAlgoType v_type_digest_auth_md5_algo_type;
   /**
    * The data for the #MHD_LIB_INFO_FIXED_TYPE_DIGEST_AUTH_SHA256 query
    */
   enum MHD_LibInfoFixedDigestAlgoType v_type_digest_auth_sha256_algo_type;
   /**
    * The data for the #MHD_LIB_INFO_FIXED_TYPE_DIGEST_AUTH_SHA512_256 query
    */
   enum MHD_LibInfoFixedDigestAlgoType v_type_digest_auth_sha512_256_algo_type;
   /**
    * The data for the #MHD_LIB_INFO_FIXED_SUPPORT_DIGEST_AUTH_AUTH_INT query
    */
   enum MHD_Bool v_support_digest_auth_auth_int_bool;
   /**
    * The data for the #MHD_LIB_INFO_FIXED_SUPPORT_DIGEST_AUTH_ALGO_SESSION query
    */
   enum MHD_Bool v_support_digest_auth_algo_session_bool;
   /**
    * The data for the #MHD_LIB_INFO_FIXED_SUPPORT_DIGEST_AUTH_USERHASH query
    */
   enum MHD_Bool v_support_digest_auth_userhash_bool;
   /**
    * The data for the #MHD_LIB_INFO_FIXED_TYPES_SOCKETS_POLLING query
    */
   struct MHD_LibInfoFixedPollingFunc v_types_sockets_polling;
   /**
    * The data for the #MHD_LIB_INFO_FIXED_SUPPORT_AGGREGATE_FD query
    */
   enum MHD_Bool v_support_aggregate_fd_bool;
   /**
    * The data for the #MHD_LIB_INFO_FIXED_TYPE_IPV6 query
    */
   enum MHD_LibInfoFixedIPv6Type v_ipv6;
   /**
    * The data for the #MHD_LIB_INFO_FIXED_SUPPORT_TCP_FASTOPEN query
    */
   enum MHD_Bool v_support_tcp_fastopen_bool;
   /**
    * The data for the #MHD_LIB_INFO_FIXED_HAS_AUTODETECT_BIND_PORT query
    */
   enum MHD_Bool v_has_autodetect_bind_port_bool;
   /**
    * The data for the #MHD_LIB_INFO_FIXED_HAS_SENDFILE query
    */
   enum MHD_Bool v_has_sendfile_bool;
   /**
    * The data for the #MHD_LIB_INFO_FIXED_HAS_AUTOSUPPRESS_SIGPIPE_INT query
    */
   enum MHD_Bool v_has_autosuppress_sigpipe_int_bool;
   /**
    * The data for the #MHD_LIB_INFO_FIXED_HAS_AUTOSUPPRESS_SIGPIPE_EXT query
    */
   enum MHD_Bool v_has_autosuppress_sigpipe_ext_bool;
   /**
    * The data for the #MHD_LIB_INFO_FIXED_HAS_THREAD_NAMES query
    */
   enum MHD_Bool v_has_thread_names_bool;
   /**
    * The data for the #MHD_LIB_INFO_FIXED_TYPE_ITC query
    */
   enum MHD_LibInfoFixedITCType v_type_itc;
   /**
    * The data for the #MHD_LIB_INFO_FIXED_SUPPORT_LARGE_FILE query
    */
   enum MHD_Bool v_support_large_file_bool;
   /**
    * The data for the #MHD_LIB_INFO_FIXED_TLS_BACKENDS query
    */
   struct MHD_LibInfoTLSType v_tls_backends;
   /**
    * The data for the #MHD_LIB_INFO_FIXED_TLS_KEY_PASSWORD_BACKENDS query
    */
   struct MHD_LibInfoTLSType v_tls_key_password_backends;
 };
 
 /**
  * Get fixed information about MHD that is not changed at run-time.
  * The returned information can be cached by application as it will be not
  * changed at run-time.
  *
  * For any valid @a info_type the only possible returned error value is
  * #MHD_SC_INFO_GET_BUFF_TOO_SMALL. If the buffer is large enough and
  * the requested type of information is valid, the function always succeeds
  * and returns #MHD_SC_OK.
  *
  * The wrapper macro #MHD_lib_get_info_fixed() may be more convenient.
  *
  * @param info_type the type of requested information
  * @param[out] output_buf the pointer to union to be set to the requested
  *                        information
  * @param output_buf_size the size of the memory area pointed by @a output_buf
  *                        (provided by the caller for storing the requested
  *                        information), in bytes
  * @return #MHD_SC_OK if succeed,
  *         #MHD_SC_INFO_GET_TYPE_UNKNOWN if @a info_type value is unknown,
  *         #MHD_SC_INFO_GET_BUFF_TOO_SMALL if @a output_buf_size is too small
  * @ingroup specialized
  */
 MHD_EXTERN_ enum MHD_StatusCode
 MHD_lib_get_info_fixed_sz (enum MHD_LibInfoFixed info_type,
                            union MHD_LibInfoFixedData *MHD_RESTRICT output_buf,
                            size_t output_buf_size)
 MHD_FN_PAR_NONNULL_ (2) MHD_FN_PAR_OUT_ (2);
 
 /**
  * Get fixed information about MHD that is not changed at run-time.
  * The returned information can be cached by application as it will be not
  * changed at run-time.
  *
  * @param info the type of requested information
  * @param[out] output_buf the pointer to union to be set to the requested
  *                        information
  * @return #MHD_SC_OK if succeed,
  *         #MHD_SC_INFO_GET_TYPE_UNKNOWN if @a info_type value is unknown,
  *         or other error code
  * @ingroup specialized
  */
 #define MHD_lib_get_info_fixed(info,output_buf) \
         MHD_lib_get_info_fixed_sz ((info),(output_buf),sizeof(*(output_buf)))
 
 /* Application may define MHD_NO_STATIC_INLINE macro before including
    libmicrohttpd headers to disable static inline functions in the headers. */
 #ifndef MHD_NO_STATIC_INLINE
 
 /*
  * A helper below can be used in a simple check preventing use of downgraded
  * library version.
  * As new library version may introduce new functionality, and the application
  * may detect some functionality available at application build-time, use of
  * previous versions may lead to run-time failures.
  * To prevent run-time failures, application may use a check like:
 
  if (MHD_lib_get_info_ver_num() < ((uint_fast32_t) MHD_VERSION))
    handle_init_failure();
 
  */
 /**
  * Get the library version number.
  * @return the library version number.
  */
 MHD_STATIC_INLINE_ MHD_FN_PURE_ uint_fast32_t
 MHD_lib_get_info_ver_num (void)
 {
   union MHD_LibInfoFixedData data;
   data.v_version_num_uint32 = 0; /* Not really necessary */
   (void) MHD_lib_get_info_fixed (MHD_LIB_INFO_FIXED_VERSION_NUM, \
                                  &data); /* Never fail */
   return data.v_version_num_uint32;
 }
 
 
 MHD_STATIC_INLINE_END_
 
 #endif /* ! MHD_NO_STATIC_INLINE */
 
 /**
  * Types of information about MHD, used by #MHD_lib_get_info_dynamic_sz().
  * This information may vary over time.
  */
 enum MHD_FIXED_ENUM_APP_SET_ MHD_LibInfoDynamic
 {
   /* * Basic MHD information * */
 
   /**
    * Get whether MHD has been successfully fully initialised.
    * MHD uses lazy initialisation: a minimal initialisation is performed at
    * startup, complete initialisation is performed when any daemon is created
    * (or when called some function which requires full initialisation).
    * The result is #MHD_NO when the library has been not yet initialised
    * completely since startup.
    * The result is placed in @a v_inited_fully_once_bool member.
    */
   MHD_LIB_INFO_DYNAMIC_INITED_FULLY_ONCE = 0
   ,
   /**
    * Get whether MHD is fully initialised.
    * MHD uses lazy initialisation: a minimal initialisation is performed at
    * startup, complete initialisation is perfromed when any daemon is created
    * (or when called some function which requires full initialisation).
    * The result is #MHD_YES if library is initialised state now (meaning
    * that at least one daemon is created and not destroyed or some function
    * required full initialisation is running).
    * The result is placed in @a v_inited_fully_now_bool member.
    */
   MHD_LIB_INFO_DYNAMIC_INITED_FULLY_NOW = 1
   ,
 
   /**
    * Get whether HTTPS and which types of TLS backend(s) currently available.
    * If any MHD daemons active (created and not destroyed, not necessary
    * running) the result reflects the current backends availability.
    * If no MHD daemon is active, then this function would try to temporarily
    * enable backends to check for their availability.
    * If global library initialisation failed, the function returns
    * #MHD_SC_INFO_GET_TYPE_UNOBTAINABLE error code.
    * The result is placed in @a v_tls_backends member.
    */
   MHD_LIB_INFO_DYNAMIC_TYPE_TLS = 100
   ,
 
   /* * Sentinel * */
   /**
    * The sentinel value.
    * This value enforces specific underlying integer type for the enum.
    * Do not use.
    */
   MHD_LIB_INFO_DYNAMIC_SENTINEL = 65535
 };
 
 
 /**
  * The data provided by #MHD_lib_get_info_dynamic_sz().
  * The resulting value may vary over time.
  */
 union MHD_LibInfoDynamicData
 {
   /**
    * The data for the #MHD_LIB_INFO_DYNAMIC_INITED_FULLY_ONCE query
    */
   enum MHD_Bool v_inited_fully_once_bool;
 
   /**
    * The data for the #MHD_LIB_INFO_DYNAMIC_INITED_FULLY_NOW query
    */
   enum MHD_Bool v_inited_fully_now_bool;
 
   /**
    * The data for the #MHD_LIB_INFO_DYNAMIC_TYPE_TLS query
    */
   struct MHD_LibInfoTLSType v_tls_backends;
 
   /**
    * Unused member.
    * Help enforcing future-proof alignment of the union.
    * Do not use.
    */
   void *reserved;
 };
 
 /**
  * Get dynamic information about MHD that may be changed at run-time.
  * The wrapper macro #MHD_lib_get_info_dynamic() could be more convenient.
  *
  * @param info_type the type of requested information
  * @param[out] output_buf the pointer to union to be set to the requested
  *                        information
  * @param output_buf_size the size of the memory area pointed by @a output_buf
  *                        (provided by the caller for storing the requested
  *                        information), in bytes
  * @return #MHD_SC_OK if succeed,
  *         #MHD_SC_INFO_GET_TYPE_UNKNOWN if @a info_type value is unknown,
  *         #MHD_SC_INFO_GET_BUFF_TOO_SMALL if @a output_buf_size is too small,
  *         or other error code
  * @ingroup specialized
  */
 MHD_EXTERN_ enum MHD_StatusCode
 MHD_lib_get_info_dynamic_sz (
   enum MHD_LibInfoDynamic info_type,
   union MHD_LibInfoDynamicData *MHD_RESTRICT output_buf,
   size_t output_buf_size)
 MHD_FN_MUST_CHECK_RESULT_ MHD_FN_PAR_NONNULL_ (2) MHD_FN_PAR_OUT_ (2);
 
 /**
  * Get dynamic information about MHD that may be changed at run-time.
  *
  * @param info the type of requested information
  * @param[out] output_buf the pointer to union to be set to the requested
  *                        information
  * @return #MHD_SC_OK if succeed,
  *         #MHD_SC_INFO_GET_TYPE_UNKNOWN if @a info_type value is unknown,
  *         or other error code
  * @ingroup specialized
  */
 #define MHD_lib_get_info_dynamic(info,output_buf) \
         MHD_lib_get_info_dynamic_sz ((info),(output_buf),sizeof(*(output_buf)))
 
 
 /**
  * Values of this enum are used to specify what information about a daemon is
  * requested.
  * These types of information do not change after the start of the daemon
  * until the daemon is destroyed.
  */
 enum MHD_DaemonInfoFixedType
 {
 
   /**
    * Get the type of system call used for sockets polling.
    * The value #MHD_SPS_AUTO is never set in the returned data.
    * The function returns #MHD_SC_INFO_GET_TYPE_NOT_APPLICABLE if the daemon
    * does not use internal sockets polling.
    * The result is placed in @a v_poll_syscall member.
    */
   MHD_DAEMON_INFO_FIXED_POLL_SYSCALL = 41
   ,
   /**
    * Get the file descriptor for the single FD that triggered when
    * any MHD event happens.
    * This FD can be watched as aggregate indicator for all MHD events.
    * The provided socket must be used as 'read-only': only select() or similar
    * functions should be used. Any modifications (changing socket attributes,
    * calling accept(), closing it etc.) will lead to undefined behaviour.
    * The function returns #MHD_SC_INFO_GET_TYPE_NOT_SUPP_BY_BUILD if the library
    * does not support mode with agregate FD.
    * The function returns #MHD_SC_INFO_GET_TYPE_NOT_APPLICABLE if the daemon
    * is not configured to use this mode.
    * The result is placed in @a v_aggreagate_fd member.
    */
   MHD_DAEMON_INFO_FIXED_AGGREAGATE_FD = 46
   ,
   /**
    * Get the number of worker threads when used in MHD_WM_WORKER_THREADS mode.
    * The function returns #MHD_SC_INFO_GET_TYPE_NOT_APPLICABLE if the daemon
    * does not use worker threads mode.
    * The result is placed in @a v_num_work_threads_uint member.
    */
   MHD_DAEMON_INFO_FIXED_NUM_WORK_THREADS = 47
   ,
   /**
    * Get the port number of daemon's listen socket.
    * Note: if port '0' (auto port) was specified for #MHD_D_OPTION_BIND_PORT(),
    * returned value will be the real port number.
    * The function returns #MHD_SC_INFO_GET_TYPE_NOT_APPLICABLE if the daemon
    * does not have listening socket or if listening socket is non-IP.
    * The function returns #MHD_SC_INFO_GET_TYPE_UNOBTAINABLE if the port number
    * detection failed or not supported by the platform.
    * If the function succeed, the returned port number is never zero.
    * The result is placed in @a v_bind_port_uint16 member.
    */
   MHD_DAEMON_INFO_FIXED_BIND_PORT = 80
   ,
   /**
    * Get the file descriptor for the listening socket.
    * The provided socket must be used as 'read-only': only select() or similar
    * functions should be used. Any modifications (changing socket attributes,
    * calling accept(), closing it etc.) will lead to undefined behaviour.
    * The function returns #MHD_SC_INFO_GET_TYPE_NOT_APPLICABLE if the daemon
    * does not have listening socket.
    * The result is placed in @a v_listen_socket member.
    */
   MHD_DAEMON_INFO_FIXED_LISTEN_SOCKET = 82
   ,
   /**
    * Get the TLS backend used by the daemon.
    * The value #MHD_TLS_BACKEND_ANY is never set in the returned data.
    * The value #MHD_TLS_BACKEND_NONE is set if the daemon does not use TLS.
    * If MHD built without TLS support then #MHD_TLS_BACKEND_NONE is always set.
    * The result is placed in @a v_tls_backend member.
    */
   MHD_DAEMON_INFO_FIXED_TLS_BACKEND = 120
   ,
   /**
    * Get the default inactivity timeout for connections.
    * The result is placed in @a v_default_timeout_uint member.
    */
   MHD_DAEMON_INFO_FIXED_DEFAULT_TIMEOUT = 160
   ,
   /**
    * Get the limit of number of simutaneous network connections served by
    * the daemon.
    * The result is placed in @a v_global_connection_limit_uint member.
    */
   MHD_DAEMON_INFO_FIXED_GLOBAL_CONNECTION_LIMIT = 161
   ,
   /**
    * Get the limit of number of simutaneous network connections served by
    * the daemon for any single IP address.
    * The result is placed in @a v_per_ip_limit_uint member.
    */
   MHD_DAEMON_INFO_FIXED_PER_IP_LIMIT = 162
   ,
   /**
    * Get the setting for suppression of the 'Date:' header in replies.
    * The result is placed in @a v_suppress_date_header_bool member.
    */
   MHD_DAEMON_INFO_FIXED_SUPPRESS_DATE_HEADER = 240
   ,
   /**
    * Get the size of buffer unsed per connection.
    * The result is placed in @a v_conn_memory_limit_sizet member.
    */
   MHD_DAEMON_INFO_FIXED_CONN_MEMORY_LIMIT = 280
   ,
   /**
    * Get the limit of maximum FD value for the daemon.
    * The daemon rejects (closes) any sockets with FD equal or higher
    * the resulting number.
    * The function returns #MHD_SC_INFO_GET_TYPE_NOT_APPLICABLE if the daemon
    * is built for W32.
    * The result is placed in @a v_fd_number_limit_uint member.
    */
   MHD_DAEMON_INFO_FIXED_FD_NUMBER_LIMIT = 283
   ,
 
   /* * Sentinel * */
   /**
    * The sentinel value.
    * This value enforces specific underlying integer type for the enum.
    * Do not use.
    */
   MHD_DAEMON_INFO_FIXED_SENTINEL = 65535
 
 };
 
 
 /**
  * Information about an MHD daemon.
  */
 union MHD_DaemonInfoFixedData
 {
   /**
    * The data for the #MHD_DAEMON_INFO_FIXED_POLL_SYSCALL query
    */
   enum MHD_SockPollSyscall v_poll_syscall;
 
   /**
    * The data for the #MHD_DAEMON_INFO_FIXED_NUM_WORK_THREADS query
    */
   unsigned int v_num_work_threads_uint;
 
   /**
    * The data for the #MHD_DAEMON_INFO_FIXED_BIND_PORT query
    */
   uint_least16_t v_bind_port_uint16;
 
   /**
    * The data for the #MHD_DAEMON_INFO_FIXED_LISTEN_SOCKET query
    */
   MHD_Socket v_listen_socket;
 
   /**
    * The data for the #MHD_DAEMON_INFO_FIXED_AGGREAGATE_FD query
    */
   int v_aggreagate_fd;
 
   /**
    * The data for the #MHD_DAEMON_INFO_FIXED_TLS_BACKEND query
    */
   enum MHD_TlsBackend v_tls_backend;
 
   /**
    * The data for the #MHD_DAEMON_INFO_FIXED_DEFAULT_TIMEOUT query
    */
   unsigned int v_default_timeout_uint;
 
   /**
    * The data for the #MHD_DAEMON_INFO_FIXED_GLOBAL_CONNECTION_LIMIT query
    */
   unsigned int v_global_connection_limit_uint;
 
   /**
    * The data for the #MHD_DAEMON_INFO_FIXED_PER_IP_LIMIT query
    */
   unsigned int v_per_ip_limit_uint;
 
   /**
    * The data for the #MHD_DAEMON_INFO_FIXED_SUPPRESS_DATE_HEADER query
    */
   enum MHD_Bool v_suppress_date_header_bool;
 
   /**
    * The data for the #MHD_DAEMON_INFO_FIXED_CONN_MEMORY_LIMIT query
    */
   size_t v_conn_memory_limit_sizet;
 
   /**
    * The data for the #MHD_DAEMON_INFO_FIXED_FD_NUMBER_LIMIT query
    */
   MHD_Socket v_fd_number_limit_socket;
 
   /**
    * Unused member.
    * Help enforcing future-proof alignment of the union.
    * Do not use.
    */
   void *reserved;
 };
 
 
 /**
  * Obtain fixed information about the given daemon.
  * This information is not changed at after start of the daemon until
  * the daemon is destroyed.
  * The wrapper macro #MHD_daemon_get_info_fixed() may be more convenient.
  *
  * @param daemon the daemon to get information about
  * @param info_type the type of information requested
  * @param[out] output_buf pointer to union where requested information will
  *                        be stored
  * @param output_buf_size the size of the memory area pointed by @a output_buf
  *                        (provided by the caller for storing the requested
  *                        information), in bytes
  * @return #MHD_SC_OK if succeed,
  *         #MHD_SC_TOO_EARLY if the daemon has not been started yet,
  *         #MHD_SC_TOO_LATE if the daemon is being stopped or has failed,
  *         #MHD_SC_INFO_GET_TYPE_UNKNOWN if @a info_type value is unknown,
  *         #MHD_SC_INFO_GET_TYPE_NOT_APPLICABLE if the requested information
  *                                              is not available for this
  *                                              daemon due to the daemon
  *                                              configuration/mode,
  *         #MHD_SC_INFO_GET_TYPE_UNOBTAINABLE if the requested information
  *                                            should be available for
  *                                            the daemon, but cannot be provided
  *                                            due to some error or other
  *                                            reasons,
  *         #MHD_SC_INFO_GET_BUFF_TOO_SMALL if @a output_buf_size is too small,
  *         other error codes in case of other errors
  * @ingroup specialized
  */
 MHD_EXTERN_ enum MHD_StatusCode
 MHD_daemon_get_info_fixed_sz (
   struct MHD_Daemon *MHD_RESTRICT daemon,
   enum MHD_DaemonInfoFixedType info_type,
   union MHD_DaemonInfoFixedData *MHD_RESTRICT output_buf,
   size_t output_buf_size)
 MHD_FN_MUST_CHECK_RESULT_ MHD_FN_PAR_NONNULL_ (1)
 MHD_FN_PAR_NONNULL_ (3) MHD_FN_PAR_OUT_ (3);
 
 /**
  * Obtain fixed information about the given daemon.
  * This types of information are not changed at after start of the daemon until
  * the daemon is destroyed.
  *
  * @param daemon the daemon to get information about
  * @param info_type the type of information requested
  * @param[out] output_buf pointer to union where requested information will
  *                          be stored
  * @return #MHD_SC_OK if succeed,
  *         #MHD_SC_TOO_EARLY if the daemon has not been started yet,
  *         #MHD_SC_TOO_LATE if the daemon is being stopped or has failed,
  *         #MHD_SC_INFO_GET_TYPE_UNKNOWN if @a info_type value is unknown,
  *         #MHD_SC_INFO_GET_TYPE_NOT_APPLICABLE if the requested information
  *                                              is not available for this
  *                                              daemon due to the daemon
  *                                              configuration/mode,
  *         #MHD_SC_INFO_GET_TYPE_UNOBTAINABLE if the requested information
  *                                            should be available for
  *                                            the daemon, but cannot be provided
  *                                            due to some error or other
  *                                            reasons,
  *         other error codes in case of other errors
  * @ingroup specialized
  */
 #define MHD_daemon_get_info_fixed(daemon,info_type,output_buf) \
         MHD_daemon_get_info_fixed_sz ((daemon), (info_type), (output_buf), \
                                       sizeof(*(output_buf)))
 
 
 /**
  * Values of this enum are used to specify what
  * information about a daemon is desired.
  * This types of information may be changed after the start of the daemon.
  */
 enum MHD_DaemonInfoDynamicType
 {
   /**
    * The the maximum number of millisecond from the current moment until
    * the mandatory call of the daemon data processing function (like
    * #MHD_daemon_process_reg_events(), #MHD_daemon_process_blocking()).
    * If resulting value is zero then daemon data processing function should be
    * called as soon as possible as some data processing is already pending.
    * The data processing function can also be called earlier as well.
    * Available only for daemons stated in #MHD_WM_EXTERNAL_PERIODIC,
    * #MHD_WM_EXTERNAL_EVENT_LOOP_CB_LEVEL, #MHD_WM_EXTERNAL_EVENT_LOOP_CB_EDGE
    * or #MHD_WM_EXTERNAL_SINGLE_FD_WATCH modes.
    * The function returns #MHD_SC_INFO_GET_TYPE_NOT_APPLICABLE if the daemon has
    * internal handling of events (internal threads).
    * The result is placed in @a v_max_time_to_wait_uint64 member.
    */
   MHD_DAEMON_INFO_DYNAMIC_MAX_TIME_TO_WAIT = 1
   ,
   /**
    * Check whether the daemon has any connected network clients.
    * The result is placed in @a v_has_connections_bool member.
    */
   MHD_DAEMON_INFO_DYNAMIC_HAS_CONNECTIONS = 20
   ,
   /* * Sentinel * */
   /**
    * The sentinel value.
    * This value enforces specific underlying integer type for the enum.
    * Do not use.
    */
   MHD_DAEMON_INFO_DYNAMIC_SENTINEL = 65535
 };
 
 
 /**
  * Information about an MHD daemon.
  */
 union MHD_DaemonInfoDynamicData
 {
   /**
    * The data for the #MHD_DAEMON_INFO_DYNAMIC_MAX_TIME_TO_WAIT query
    */
   uint_fast64_t v_max_time_to_wait_uint64;
 
   /**
    * The data for the #MHD_DAEMON_INFO_DYNAMIC_HAS_CONNECTIONS query
    */
   enum MHD_Bool v_has_connections_bool;
 
   /**
    * Unused member.
    * Help enforcing future-proof alignment of the union.
    * Do not use.
    */
   void *reserved;
 };
 
 
 /**
  * Obtain dynamic information about the given daemon.
  * This information may be changed after the start of the daemon.
  * The wrapper macro #MHD_daemon_get_info_dynamic() could be more convenient.
  *
  * @param daemon the daemon to get information about
  * @param info_type the type of information requested
  * @param[out] output_buf the pointer to union to be set to the requested
  *                        information
  * @param output_buf_size the size of the memory area pointed by @a output_buf
  *                        (provided by the caller for storing the requested
  *                        information), in bytes
  * @return #MHD_SC_OK if succeed,
  *         #MHD_SC_TOO_EARLY if the daemon has not been started yet,
  *         #MHD_SC_TOO_LATE if the daemon is being stopped or has failed,
  *         #MHD_SC_INFO_GET_TYPE_UNKNOWN if @a info_type value is unknown,
  *         #MHD_SC_INFO_GET_TYPE_NOT_APPLICABLE if the requested information
  *                                              is not available for this
  *                                              daemon due to the daemon
  *                                              configuration/mode,
  *         #MHD_SC_INFO_GET_TYPE_UNOBTAINABLE if the requested information
  *                                            should be available for
  *                                            the daemon, but cannot be provided
  *                                            due to some error or other
  *                                            reasons,
  *         #MHD_SC_INFO_GET_BUFF_TOO_SMALL if @a output_buf_size is too small,
  *         other error codes in case of other errors
  * @ingroup specialized
  */
 MHD_EXTERN_ enum MHD_StatusCode
 MHD_daemon_get_info_dynamic_sz (
   struct MHD_Daemon *MHD_RESTRICT daemon,
   enum MHD_DaemonInfoDynamicType info_type,
   union MHD_DaemonInfoDynamicData *MHD_RESTRICT output_buf,
   size_t output_buf_size)
 MHD_FN_MUST_CHECK_RESULT_ MHD_FN_PAR_NONNULL_ (1)
 MHD_FN_PAR_NONNULL_ (3) MHD_FN_PAR_OUT_ (3);
 
 /**
  * Obtain dynamic information about the given daemon.
  * This types of information may be changed after the start of the daemon.
  *
  * @param daemon the daemon to get information about
  * @param info_type the type of information requested
  * @param[out] output_buf the pointer to union to be set to the requested
  *                        information
  * @return #MHD_SC_OK if succeed,
  *         #MHD_SC_TOO_EARLY if the daemon has not been started yet,
  *         #MHD_SC_TOO_LATE if the daemon is being stopped or has failed,
  *         #MHD_SC_INFO_GET_TYPE_UNKNOWN if @a info_type value is unknown,
  *         #MHD_SC_INFO_GET_TYPE_NOT_APPLICABLE if the requested information
  *                                              is not available for this
  *                                              daemon due to the daemon
  *                                              configuration/mode,
  *         #MHD_SC_INFO_GET_TYPE_UNOBTAINABLE if the requested information
  *                                            should be available for
  *                                            the daemon, but cannot be provided
  *                                            due to some error or other
  *                                            reasons,
  *         other error codes in case of other errors
  * @ingroup specialized
  */
 #define MHD_daemon_get_info_dynamic(daemon,info_type,output_buf) \
         MHD_daemon_get_info_dynamic_sz ((daemon), (info_type), (output_buf), \
                                         sizeof(*(output_buf)))
 
 
 /**
  * Select which fixed information about connection is desired.
  * This information is not changed during the lifetime of the connection.
  */
 enum MHD_ConnectionInfoFixedType
 {
   /**
    * Get the network address of the client.
    * If the connection does not have known remote address (was not provided
    * by the system or by the application in case of externally added
    * connection) then error code #MHD_SC_INFO_GET_TYPE_UNOBTAINABLE is
    * returned if connection is IP type or unknown type or error code
    * #MHD_SC_INFO_GET_TYPE_NOT_APPLICABLE if connection type is non-IP.
    * The @a sa pointer is never NULL if the function succeed (#MHD_SC_OK
    * returned).
    * The result is placed in @a v_client_address_sa_info member.
    * @ingroup request
    */
   MHD_CONNECTION_INFO_FIXED_CLIENT_ADDRESS = 1
   ,
   /**
    * Get the file descriptor for the connection socket.
    * The provided socket must be used as 'read-only': only select() or similar
    * functions should be used. Any modifications (changing socket attributes,
    * calling send() or recv(), closing it etc.) will lead to undefined
    * behaviour.
    * The result is placed in @a v_connection_socket member.
    * @ingroup request
    */
   MHD_CONNECTION_INFO_FIXED_CONNECTION_SOCKET = 2
   ,
   /**
    * Get the `struct MHD_Daemon *` responsible for managing this connection.
    * The result is placed in @a v_daemon member.
    * @ingroup request
    */
   MHD_CONNECTION_INFO_FIXED_DAEMON = 20
   ,
   /**
    * Returns the pointer to a variable pointing to connection-specific
    * application context data that was (possibly) set during
    * a #MHD_NotifyConnectionCallback or provided via @a connection_cntx
    * parameter of #MHD_daemon_add_connection().
    * By using provided pointer application may get or set the pointer to
    * any data specific for the particular connection.
    * Note: resulting data is NOT the context pointer itself.
    * The result is placed in @a v_app_context_ppvoid member.
    * @ingroup request
    */
   MHD_CONNECTION_INFO_FIXED_APP_CONTEXT = 30
   ,
 
   /* * Sentinel * */
   /**
    * The sentinel value.
    * This value enforces specific underlying integer type for the enum.
    * Do not use.
    */
   MHD_CONNECTION_INFO_FIXED_SENTINEL = 65535
 };
 
 /**
  * Socket address information data
  */
 struct MHD_ConnInfoFixedSockAddr
 {
   /**
    * The size of the @a sa
    */
   size_t sa_size;
 
   /**
    * Socket Address type
    */
   const struct sockaddr *sa;
 };
 
 /**
  * Information about a connection.
  */
 union MHD_ConnectionInfoFixedData
 {
 
   /**
    * The data for the #MHD_CONNECTION_INFO_FIXED_CLIENT_ADDRESS query
    */
   struct MHD_ConnInfoFixedSockAddr v_client_address_sa_info;
 
   /**
    * The data for the #MHD_CONNECTION_INFO_FIXED_CONNECTION_SOCKET query
    */
   MHD_Socket v_connection_socket;
 
   /**
    * The data for the #MHD_CONNECTION_INFO_FIXED_DAEMON query
    */
   struct MHD_Daemon *v_daemon;
 
   /**
    * The data for the #MHD_CONNECTION_INFO_FIXED_APP_CONTEXT query
    */
   void **v_app_context_ppvoid;
 };
 
 
 /**
  * Obtain fixed information about the given connection.
  * This information is not changed for the lifetime of the connection.
  * The wrapper macro #MHD_connection_get_info_fixed() may be more convenient.
  *
  * @param connection the connection to get information about
  * @param info_type the type of information requested
  * @param[out] output_buf the pointer to union to be set to the requested
  *                        information
  * @param output_buf_size the size of the memory area pointed by @a output_buf
  *                        (provided by the caller for storing the requested
  *                        information), in bytes
  * @return #MHD_SC_OK if succeed,
  *         #MHD_SC_INFO_GET_TYPE_UNKNOWN if @a info_type value is unknown,
  *         #MHD_SC_INFO_GET_TYPE_NOT_APPLICABLE if the requested information
  *                                              is not available for this
  *                                              connection due to the connection
  *                                              configuration/mode,
  *         #MHD_SC_INFO_GET_TYPE_UNOBTAINABLE if the requested information
  *                                            should be available for
  *                                            the connection, but cannot be
  *                                            provided due to some error or
  *                                            other reasons,
  *         #MHD_SC_INFO_GET_BUFF_TOO_SMALL if @a output_buf_size is too small,
  *         other error codes in case of other errors
  * @ingroup specialized
  */
 MHD_EXTERN_ enum MHD_StatusCode
 MHD_connection_get_info_fixed_sz (
   struct MHD_Connection *MHD_RESTRICT connection,
   enum MHD_ConnectionInfoFixedType info_type,
   union MHD_ConnectionInfoFixedData *MHD_RESTRICT output_buf,
   size_t output_buf_size)
 MHD_FN_MUST_CHECK_RESULT_ MHD_FN_PAR_NONNULL_ (1)
 MHD_FN_PAR_NONNULL_ (3) MHD_FN_PAR_OUT_ (3);
 
 
 /**
  * Obtain fixed information about the given connection.
  * This information is not changed for the lifetime of the connection.
  *
  * @param connection the connection to get information about
  * @param info_type the type of information requested
  * @param[out] output_buf the pointer to union to be set to the requested
  *                        information
  * @return #MHD_SC_OK if succeed,
  *         #MHD_SC_INFO_GET_TYPE_UNKNOWN if @a info_type value is unknown,
  *         #MHD_SC_INFO_GET_TYPE_NOT_APPLICABLE if the requested information
  *                                              is not available for this
  *                                              connection due to the connection
  *                                              configuration/mode,
  *         #MHD_SC_INFO_GET_TYPE_UNOBTAINABLE if the requested information
  *                                            should be available for
  *                                            the connection, but cannot be
  *                                            provided due to some error or
  *                                            other reasons,
  *         other error codes in case of other errors
  * @ingroup specialized
  */
 #define MHD_connection_get_info_fixed(connection,info_type,output_buf) \
         MHD_connection_get_info_fixed_sz ((connection),(info_type), \
                                           (output_buf), sizeof(*(output_buf)))
 
 
 /**
  * Select which dynamic information about connection is desired.
  * This information may be changed during the lifetime of the connection.
  */
 enum MHD_ConnectionInfoDynamicType
 {
   /**
    * Get current version of HTTP protocol used for connection.
    * If connection is handling HTTP/1.x requests the function may return
    * error code #MHD_SC_TOO_EARLY if the full request line has not been received
    * yet for the current request.
    * The result is placed in @a v_http_ver member.
    * @ingroup request
    */
   MHD_CONNECTION_INFO_DYNAMIC_HTTP_VER = 1
   ,
   /**
    * Get connection timeout value.
    * This is the total number of seconds after which the idle connection is
    * automatically disconnected.
    * Note: the value set is NOT the number of seconds left before automatic
    * disconnection.
    * The result is placed in @a v_connection_timeout_uint member.
    * @ingroup request
    */
   MHD_CONNECTION_INFO_DYNAMIC_CONNECTION_TIMEOUT = 10
   ,
   /**
    * Check whether the connection is suspended.
    * The result is placed in @a v_connection_suspended_bool member.
    * @ingroup request
    */
   MHD_CONNECTION_INFO_DYNAMIC_CONNECTION_SUSPENDED = 11
   ,
   /**
    * Get current version of TLS transport protocol used for connection
    * If plain TCP connection is used then #MHD_TLS_VERSION_NO_TLS set in
    * the data.
    * It TLS handshake is not yet finished then error code #MHD_SC_TOO_EARLY is
    * returned. If TLS has failed or being closed then #MHD_SC_TOO_LATE error
    * code is returned.
    * If TLS version cannot be detected for any reason then error code
    * #MHD_SC_INFO_GET_TYPE_UNOBTAINABLE is returned.
    * The result is placed in @a v_tls_ver member.
    * @ingroup request
    */
   MHD_CONNECTION_INFO_DYNAMIC_TLS_VER = 105
   ,
   /**
    * Get the TLS backend session handle.
    * If plain TCP connection is used then the function returns error code
    * #MHD_SC_INFO_GET_TYPE_NOT_APPLICABLE.
    * The resulting union has only one valid member.
    * The result is placed in @a v_tls_session member.
    * @ingroup request
    */
   MHD_CONNECTION_INFO_DYNAMIC_TLS_SESSION = 140
   ,
 
   /* * Sentinel * */
   /**
    * The sentinel value.
    * This value enforces specific underlying integer type for the enum.
    * Do not use.
    */
   MHD_CONNECTION_INFO_DYNAMIC_SENTINEL = 65535
 };
 
 
 /**
  * The versions of TLS protocol
  */
 enum MHD_FIXED_ENUM_MHD_SET_ MHD_TlsVersion
 {
 
   /**
    * No TLS / plain socket connection
    */
   MHD_TLS_VERSION_NO_TLS = 0
   ,
   /**
    * Not supported/failed to negotiate/failed to handshake TLS
    */
   MHD_TLS_VERSION_BROKEN = 1
   ,
   /**
    * TLS version 1.0
    */
   MHD_TLS_VERSION_1_0 = 2
   ,
   /**
    * TLS version 1.1
    */
   MHD_TLS_VERSION_1_1 = 3
   ,
   /**
    * TLS version 1.2
    */
   MHD_TLS_VERSION_1_2 = 4
   ,
   /**
    * TLS version 1.3
    */
   MHD_TLS_VERSION_1_3 = 5
   ,
   /**
    * Some unknown TLS version.
    * The TLS version is supported by TLS backend, but unknown to MHD.
    */
   MHD_TLS_VERSION_UNKNOWN = 1999
 };
 
 /**
  * Connection TLS session information.
  * Only one member is valid. Use #MHD_DAEMON_INFO_FIXED_TLS_TYPE to find out
  * which member should be used.
  */
 union MHD_ConnInfoDynamicTlsSess
 {
   /* Include <gnutls/gnutls.h> before this header to get a better type safety */
   /**
    * GnuTLS session handle, of type "gnutls_session_t".
    */
 #if defined(GNUTLS_VERSION_MAJOR) && GNUTLS_VERSION_MAJOR >= 3
   gnutls_session_t v_gnutls_session;
 #else
   void * /* gnutls_session_t */ v_gnutls_session;
 #endif
 
   /* Include <openssl/types.h> or <openssl/crypto.h> before this header to get
      a better type safety */
   /**
    * OpenSSL session handle, of type "SSL*".
    */
 #if defined(OPENSSL_TYPES_H) && OPENSSL_VERSION_MAJOR >= 3
   SSL *v_openssl_session;
 #else
   void /* SSL */ *v_openssl_session;
 #endif
 
   /* Include <mbedtls/ssl.h> before this header to get a better type safety */
   /**
    * MbedTLS session handle, of type "mbedtls_ssl_context*".
    */
 #if defined(MBEDTLS_SSL_H)
   mbedtls_ssl_context *v_mbedtls_session;
 #else
   void /* mbedtls_ssl_context */ *v_mbedtls_session;
 #endif
 };
 
 /**
  * Information about a connection.
  */
 union MHD_ConnectionInfoDynamicData
 {
   /**
    * The data for the #MHD_CONNECTION_INFO_DYNAMIC_HTTP_VER query
    */
   enum MHD_HTTP_ProtocolVersion v_http_ver;
 
   /**
    * The data for the #MHD_CONNECTION_INFO_DYNAMIC_CONNECTION_TIMEOUT query
    */
   unsigned int v_connection_timeout_uint;
 
   /**
    * The data for the #MHD_CONNECTION_INFO_DYNAMIC_CONNECTION_SUSPENDED query
    */
   enum MHD_Bool v_connection_suspended_bool;
 
   /**
    * The data for the #MHD_CONNECTION_INFO_DYNAMIC_CONNECTION_SUSPENDED query
    */
   enum MHD_TlsVersion v_tls_ver;
 
   /**
    * Connection TLS session information.
    * Only one member is valid. Use #MHD_DAEMON_INFO_FIXED_TLS_TYPE to find out
    * which member should be used.
    */
   union MHD_ConnInfoDynamicTlsSess v_tls_session;
 };
 
 /**
  * Obtain dynamic information about the given connection.
  * This information may be changed during the lifetime of the connection.
  *
  * The wrapper macro #MHD_connection_get_info_dynamic() may be more convenient.
  *
  * @param connection the connection to get information about
  * @param info_type the type of information requested
  * @param[out] output_buf the pointer to union to be set to the requested
  *                        information
  * @param output_buf_size the size of the memory area pointed by @a output_buf
  *                        (provided by the caller for storing the requested
  *                        information), in bytes
  * @return #MHD_SC_OK if succeed,
  *         #MHD_SC_INFO_GET_TYPE_UNKNOWN if @a info_type value is unknown,
  *         #MHD_SC_TOO_EARLY if the connection has not reached yet required
  *                           state,
  *         #MHD_SC_TOO_LATE if the connection is already in state where
  *                          the requested information is not available,
  *         #MHD_SC_INFO_GET_TYPE_NOT_APPLICABLE if the requested information
  *                                              is not available for this
  *                                              connection due to the connection
  *                                              configuration/mode,
  *         #MHD_SC_INFO_GET_BUFF_TOO_SMALL if @a output_buf_size is too small,
  *         #MHD_SC_INFO_GET_TYPE_UNOBTAINABLE if the requested information
  *                                            should be available for
  *                                            the connection, but cannot be
  *                                            provided due to some error or
  *                                            other reasons,
  *         other error codes in case of other errors
  * @ingroup specialized
  */
 MHD_EXTERN_ enum MHD_StatusCode
 MHD_connection_get_info_dynamic_sz (
   struct MHD_Connection *MHD_RESTRICT connection,
   enum MHD_ConnectionInfoDynamicType info_type,
   union MHD_ConnectionInfoDynamicData *MHD_RESTRICT output_buf,
   size_t output_buf_size)
 MHD_FN_MUST_CHECK_RESULT_ MHD_FN_PAR_NONNULL_ (1)
 MHD_FN_PAR_NONNULL_ (3) MHD_FN_PAR_OUT_ (3);
 
 
 /**
  * Obtain dynamic information about the given connection.
  * This information may be changed during the lifetime of the connection.
  *
  * @param connection the connection to get information about
  * @param info_type the type of information requested
  * @param[out] output_buf the pointer to union to be set to the requested
  *                        information
  * @return #MHD_SC_OK if succeed,
  *         #MHD_SC_INFO_GET_TYPE_UNKNOWN if @a info_type value is unknown,
  *         #MHD_SC_TOO_EARLY if the connection has not reached yet required
  *                           state,
  *         #MHD_SC_TOO_LATE if the connection is already in state where
  *                          the requested information is not available,
  *         #MHD_SC_INFO_GET_TYPE_NOT_APPLICABLE if the requested information
  *                                              is not available for this
  *                                              connection due to the connection
  *                                              configuration/mode,
  *         #MHD_SC_INFO_GET_TYPE_UNOBTAINABLE if the requested information
  *                                            should be available for
  *                                            the connection, but cannot be
  *                                            provided due to some error or
  *                                            other reasons,
  *         other error codes in case of other errors
  * @ingroup specialized
  */
 #define MHD_connection_get_info_dynamic(connection,info_type,output_buf) \
         MHD_connection_get_info_dynamic_sz ((connection),(info_type), \
                                             (output_buf),sizeof(*(output_buf)))
 
 
 /**
  * Select which fixed information about stream is desired.
  * This information is not changed during the lifetime of the connection.
  */
 enum MHD_FIXED_ENUM_APP_SET_ MHD_StreamInfoFixedType
 {
   /**
    * Get the `struct MHD_Daemon *` responsible for managing connection which
    * is responsible for this stream.
    * The result is placed in @a v_daemon member.
    * @ingroup request
    */
   MHD_STREAM_INFO_FIXED_DAEMON = 20
   ,
   /**
    * Get the `struct MHD_Connection *` responsible for managing this stream.
    * The result is placed in @a v_connection member.
    * @ingroup request
    */
   MHD_STREAM_INFO_FIXED_CONNECTION = 21
   ,
 
   /* * Sentinel * */
   /**
    * The sentinel value.
    * This value enforces specific underlying integer type for the enum.
    * Do not use.
    */
   MHD_STREAM_INFO_FIXED_SENTINEL = 65535
 };
 
 
 /**
  * Fixed information about a stream.
  */
 union MHD_StreamInfoFixedData
 {
   /**
    * The data for the #MHD_STREAM_INFO_FIXED_DAEMON query
    */
   struct MHD_Daemon *v_daemon;
   /**
    * The data for the #MHD_STREAM_INFO_FIXED_CONNECTION query
    */
   struct MHD_Connection *v_connection;
 };
 
 
 /**
  * Obtain fixed information about the given stream.
  * This information is not changed for the lifetime of the stream.
  *
  * The wrapper macro #MHD_stream_get_info_fixed() may be more convenient.
  *
  * @param stream the stream to get information about
  * @param info_type the type of information requested
  * @param[out] output_buf the pointer to union to be set to the requested
  *                        information
  * @param output_buf_size the size of the memory area pointed by @a output_buf
  *                        (provided by the caller for storing the requested
  *                        information), in bytes
  * @return #MHD_SC_OK if succeed,
  *         #MHD_SC_INFO_GET_TYPE_UNKNOWN if @a info_type value is unknown,
  *         #MHD_SC_INFO_GET_BUFF_TOO_SMALL if @a output_buf_size is too small,
  *         other error codes in case of other errors
  * @ingroup specialized
  */
 MHD_EXTERN_ enum MHD_StatusCode
 MHD_stream_get_info_fixed_sz (
   struct MHD_Stream *MHD_RESTRICT stream,
   enum MHD_StreamInfoFixedType info_type,
   union MHD_StreamInfoFixedData *MHD_RESTRICT output_buf,
   size_t output_buf_size)
 MHD_FN_MUST_CHECK_RESULT_ MHD_FN_PAR_NONNULL_ (1)
 MHD_FN_PAR_NONNULL_ (3) MHD_FN_PAR_OUT_ (3);
 
 
 /**
  * Obtain fixed information about the given stream.
  * This information is not changed for the lifetime of the tream.
  *
  * @param stream the stream to get information about
  * @param info_type the type of information requested
  * @param[out] output_buf the pointer to union to be set to the requested
  *                        information
  * @return #MHD_SC_OK if succeed,
  *         #MHD_SC_INFO_GET_TYPE_UNKNOWN if @a info_type value is unknown,
  *         other error codes in case of other errors
  * @ingroup specialized
  */
 #define MHD_stream_get_info_fixed(stream,info_type,output_buf) \
         MHD_stream_get_info_fixed_sz ((stream),(info_type),(output_buf), \
                                       sizeof(*(output_buf)))
 
 
 /**
  * Select which fixed information about stream is desired.
  * This information may be changed during the lifetime of the stream.
  */
 enum MHD_FIXED_ENUM_APP_SET_ MHD_StreamInfoDynamicType
 {
   /**
    * Get the `struct MHD_Request *` for current request processed by the stream.
    * If no request is being processed, the error code #MHD_SC_TOO_EARLY is
    * returned.
    * The result is placed in @a v_request member.
    * @ingroup request
    */
   MHD_STREAM_INFO_DYNAMIC_REQUEST = 20
   ,
 
   /* * Sentinel * */
   /**
    * The sentinel value.
    * This value enforces specific underlying integer type for the enum.
    * Do not use.
    */
   MHD_STREAM_INFO_DYNAMIC_SENTINEL = 65535
 };
 
 
 /**
  * Dynamic information about stream.
  * This information may be changed during the lifetime of the connection.
  */
 union MHD_StreamInfoDynamicData
 {
   /**
    * The data for the #MHD_STREAM_INFO_DYNAMIC_REQUEST query
    */
   struct MHD_Request *v_request;
 };
 
 /**
  * Obtain dynamic information about the given stream.
  * This information may be changed during the lifetime of the stream.
  *
  * The wrapper macro #MHD_stream_get_info_dynamic() may be more convenient.
  *
  * @param stream the stream to get information about
  * @param info_type the type of information requested
  * @param[out] output_buf the pointer to union to be set to the requested
  *                        information
  * @param output_buf_size the size of the memory area pointed by @a output_buf
  *                        (provided by the caller for storing the requested
  *                        information), in bytes
  * @return #MHD_SC_OK if succeed,
  *         #MHD_SC_INFO_GET_TYPE_UNKNOWN if @a info_type value is unknown,
  *         #MHD_SC_TOO_EARLY if the stream has not reached yet required state,
  *         #MHD_SC_INFO_GET_BUFF_TOO_SMALL if @a output_buf_size is too small,
  *         other error codes in case of other errors
  * @ingroup specialized
  */
 MHD_EXTERN_ enum MHD_StatusCode
 MHD_stream_get_info_dynamic_sz (
   struct MHD_Stream *MHD_RESTRICT stream,
   enum MHD_StreamInfoDynamicType info_type,
   union MHD_StreamInfoDynamicData *MHD_RESTRICT output_buf,
   size_t output_buf_size)
 MHD_FN_MUST_CHECK_RESULT_ MHD_FN_PAR_NONNULL_ (1)
 MHD_FN_PAR_NONNULL_ (3) MHD_FN_PAR_OUT_ (3);
 
 
 /**
  * Obtain dynamic information about the given stream.
  * This information may be changed during the lifetime of the stream.
  *
  * @param stream the stream to get information about
  * @param info_type the type of information requested
  * @param[out] output_buf the pointer to union to be set to the requested
  *                        information
  * @return #MHD_SC_OK if succeed,
  *         #MHD_SC_INFO_GET_TYPE_UNKNOWN if @a info_type value is unknown,
  *         #MHD_SC_TOO_EARLY if the stream has not reached yet required state,
  *         other error codes in case of other errors
  * @ingroup specialized
  */
 #define MHD_stream_get_info_dynamic(stream,info_type,output_buf) \
         MHD_stream_get_info_dynamic_sz ((stream),(info_type),(output_buf), \
                                         sizeof(*(output_buf)))
 
 
 /**
  * Select which fixed information about request is desired.
  * This information is not changed during the lifetime of the request.
  */
 enum MHD_FIXED_ENUM_APP_SET_ MHD_RequestInfoFixedType
 {
   /**
    * Get the version of HTTP protocol used for the request.
    * If request line has not been fully received yet then #MHD_SC_TOO_EARLY
    * error code is returned.
    * The result is placed in @a v_http_ver member.
    * @ingroup request
    */
   MHD_REQUEST_INFO_FIXED_HTTP_VER = 1
   ,
   /**
    * Get the HTTP method used for the request (as a enum).
    * The result is placed in @a v_http_method member.
    * @sa #MHD_REQUEST_INFO_DYNAMIC_HTTP_METHOD_STR
    * @ingroup request
    */
   MHD_REQUEST_INFO_FIXED_HTTP_METHOD = 2
   ,
   /**
    * Return MHD daemon to which the request belongs to.
    * The result is placed in @a v_daemon member.
    */
   MHD_REQUEST_INFO_FIXED_DAEMON = 20
   ,
   /**
    * Return which connection is associated with the stream which is associated
    * with the request.
    * The result is placed in @a v_connection member.
    */
   MHD_REQUEST_INFO_FIXED_CONNECTION = 21
   ,
   /**
    * Return which stream the request is associated with.
    * The result is placed in @a v_stream member.
    */
   MHD_REQUEST_INFO_FIXED_STREAM = 22
   ,
   /**
    * Returns the pointer to a variable pointing to request-specific
    * application context data. The same data is provided for
    * #MHD_EarlyUriLogCallback and #MHD_RequestTerminationCallback.
    * By using provided pointer application may get or set the pointer to
    * any data specific for the particular request.
    * Note: resulting data is NOT the context pointer itself.
    * The result is placed in @a v_app_context_ppvoid member.
    * @ingroup request
    */
   MHD_REQUEST_INFO_FIXED_APP_CONTEXT = 30
   ,
 
   /* * Sentinel * */
   /**
    * The sentinel value.
    * This value enforces specific underlying integer type for the enum.
    * Do not use.
    */
   MHD_REQUEST_INFO_FIXED_SENTINEL = 65535
 };
 
 
 /**
  * Fixed information about a request.
  */
 union MHD_RequestInfoFixedData
 {
 
   /**
    * The data for the #MHD_REQUEST_INFO_FIXED_HTTP_VER query
    */
   enum MHD_HTTP_ProtocolVersion v_http_ver;
 
   /**
    * The data for the #MHD_REQUEST_INFO_FIXED_HTTP_METHOD query
    */
   enum MHD_HTTP_Method v_http_method;
 
   /**
    * The data for the #MHD_REQUEST_INFO_FIXED_DAEMON query
    */
   struct MHD_Daemon *v_daemon;
 
   /**
    * The data for the #MHD_REQUEST_INFO_FIXED_CONNECTION query
    */
   struct MHD_Connection *v_connection;
 
   /**
    * The data for the #MHD_REQUEST_INFO_FIXED_STREAM query
    */
   struct MHD_Stream *v_stream;
 
   /**
    * The data for the #MHD_REQUEST_INFO_FIXED_APP_CONTEXT query
    */
   void **v_app_context_ppvoid;
 };
 
 /**
  * Obtain fixed information about the given request.
  * This information is not changed for the lifetime of the request.
  *
  * The wrapper macro #MHD_request_get_info_fixed() may be more convenient.
  *
  * @param request the request to get information about
  * @param info_type the type of information requested
  * @param[out] output_buf the pointer to union to be set to the requested
  *                        information
  * @param output_buf_size the size of the memory area pointed by @a output_buf
  *                        (provided by the caller for storing the requested
  *                        information), in bytes
  * @return #MHD_SC_OK if succeed,
  *         #MHD_SC_INFO_GET_TYPE_UNKNOWN if @a info_type value is unknown,
  *         #MHD_SC_TOO_EARLY if the request processing has not reached yet
  *                           the required state,
  *         #MHD_SC_INFO_GET_BUFF_TOO_SMALL if @a output_buf_size is too small,
  *         other error codes in case of other errors
  * @ingroup specialized
  */
 MHD_EXTERN_ enum MHD_StatusCode
 MHD_request_get_info_fixed_sz (
   struct MHD_Request *MHD_RESTRICT request,
   enum MHD_RequestInfoFixedType info_type,
   union MHD_RequestInfoFixedData *MHD_RESTRICT output_buf,
   size_t output_buf_size)
 MHD_FN_MUST_CHECK_RESULT_ MHD_FN_PAR_NONNULL_ (1)
 MHD_FN_PAR_NONNULL_ (3) MHD_FN_PAR_OUT_ (3);
 
 
 /**
  * Obtain fixed information about the given request.
  * This information is not changed for the lifetime of the request.
  *
  * @param request the request to get information about
  * @param info_type the type of information requested
  * @param[out] output_buf the pointer to union to be set to the requested
  *                        information
  * @return #MHD_SC_OK if succeed,
  *         #MHD_SC_INFO_GET_TYPE_UNKNOWN if @a info_type value is unknown,
  *         #MHD_SC_TOO_EARLY if the request processing has not reached yet
  *                           the required state,
  *         other error codes in case of other errors
  * @ingroup specialized
  */
 #define MHD_request_get_info_fixed(request,info_type,output_buf) \
         MHD_request_get_info_fixed_sz ((request), (info_type), (output_buf), \
                                        sizeof(*(output_buf)))
 
 
 /**
  * Select which dynamic information about request is desired.
  * This information may be changed during the lifetime of the request.
  * Any returned string pointers are valid only until a response is provided.
  */
 enum MHD_FIXED_ENUM_APP_SET_ MHD_RequestInfoDynamicType
 {
   /**
    * Get the HTTP method used for the request (as a MHD_String).
    * The resulting string pointer in valid only until a response is provided.
    * The result is placed in @a v_http_method_string member.
    * @sa #MHD_REQUEST_INFO_FIXED_HTTP_METHOD
    * @ingroup request
    */
   MHD_REQUEST_INFO_DYNAMIC_HTTP_METHOD_STRING = 1
   ,
   /**
    * Get the URI used for the request (as a MHD_String), excluding
    * the parameter part (anything after '?').
    * The resulting string pointer in valid only until a response is provided.
    * The result is placed in @a v_uri_string member.
    * @ingroup request
    */
   MHD_REQUEST_INFO_DYNAMIC_URI = 2
   ,
   /**
    * Get the number of URI parameters (the decoded part of the original
    * URI string after '?'). Sometimes it is called "GET parameters".
    * The result is placed in @a v_number_uri_params_sizet member.
    * @ingroup request
    */
   MHD_REQUEST_INFO_DYNAMIC_NUMBER_URI_PARAMS = 3
   ,
   /**
    * Get the number of cookies in the request.
    * The result is placed in @a v_number_cookies_sizet member.
    * If cookies parsing is disabled in MHD build then the function returns
    * error code #MHD_SC_FEATURE_DISABLED.
    * If cookies parsing is disabled this daemon then the function returns
    * error code #MHD_SC_INFO_GET_TYPE_NOT_APPLICABLE.
    * @ingroup request
    */
   MHD_REQUEST_INFO_DYNAMIC_NUMBER_COOKIES = 4
   ,
   /**
    * Return length of the client's HTTP request header.
    * This is a total raw size of the header (after TLS decipher if any)
    * The result is placed in @a v_header_size_sizet member.
    * @ingroup request
    */
   MHD_REQUEST_INFO_DYNAMIC_HEADER_SIZE = 5
   ,
   /**
    * Get the number of decoded POST entries in the request.
    * The result is placed in @a v_number_post_params_sizet member.
    * @ingroup request
    */
   MHD_REQUEST_INFO_DYNAMIC_NUMBER_POST_PARAMS = 6
   ,
   /**
    * Get whether the upload content is present in the request.
    * The result is #MHD_YES if any upload content is present, even
    * if the upload content size is zero.
    * The result is placed in @a v_upload_present_bool member.
    * @ingroup request
    */
   MHD_REQUEST_INFO_DYNAMIC_UPLOAD_PRESENT = 10
   ,
   /**
    * Get whether the chunked upload content is present in the request.
    * The result is #MHD_YES if chunked upload content is present.
    * The result is placed in @a v_upload_chunked_bool member.
    * @ingroup request
    */
   MHD_REQUEST_INFO_DYNAMIC_UPLOAD_CHUNKED = 11
   ,
   /**
    * Get the total content upload size.
    * Resulted in zero if no content upload or upload content size is zero,
    * #MHD_SIZE_UNKNOWN if size is not known (chunked upload).
    * The result is placed in @a v_upload_size_total_uint64 member.
    * @ingroup request
    */
   MHD_REQUEST_INFO_DYNAMIC_UPLOAD_SIZE_TOTAL = 12
   ,
   /**
    * Get the total size of the content upload already received from the client.
    * This is the total size received, could be not yet fully processed by the
    * application.
    * The result is placed in @a v_upload_size_recieved_uint64 member.
    * @ingroup request
    */
   MHD_REQUEST_INFO_DYNAMIC_UPLOAD_SIZE_RECIEVED = 13
   ,
   /**
    * Get the total size of the content upload left to be received from
    * the client.
    * Resulted in #MHD_SIZE_UNKNOWN if total size is not known (chunked upload).
    * The result is placed in @a v_upload_size_to_recieve_uint64 member.
    * @ingroup request
    */
   MHD_REQUEST_INFO_DYNAMIC_UPLOAD_SIZE_TO_RECIEVE = 14
   ,
   /**
    * Get the total size of the content upload already processed (upload callback
    * called and completed (if any)).
    * If the value is requested from #MHD_UploadCallback, then result does NOT
    * include the current data being processed by the callback.
    * The result is placed in @a v_upload_size_processed_uint64 member.
    * @ingroup request
    */
   MHD_REQUEST_INFO_DYNAMIC_UPLOAD_SIZE_PROCESSED = 15
   ,
   /**
    * Get the total size of the content upload left to be processed.
    * The resulting value includes the size of the data not yet received from
    * the client.
    * If the value is requested from #MHD_UploadCallback, then result includes
    * the current data being processed by the callback.
    * Resulted in #MHD_SIZE_UNKNOWN if total size is not known (chunked upload).
    * The result is placed in @a v_upload_size_to_process_uint64 member.
    * @ingroup request
    */
   MHD_REQUEST_INFO_DYNAMIC_UPLOAD_SIZE_TO_PROCESS = 16
   ,
   /**
    * Returns pointer to information about digest auth in client request.
    * The resulting pointer is NULL if no digest auth header is set by
    * the client or the format of the digest auth header is broken.
    * Pointers in the returned structure (if any) are valid until response
    * is provided for the request.
    * The result is placed in @a v_auth_digest_info member.
    */
   MHD_REQUEST_INFO_DYNAMIC_AUTH_DIGEST_INFO = 42
   ,
   /**
    * Returns information about Basic Authentication credentials in the request.
    * Pointers in the returned structure (if any) are valid until any MHD_Action
    * or MHD_UploadAction is provided. If the data is needed beyond this point,
    * it should be copied.
    * If #MHD_request_get_info_dynamic_sz() returns #MHD_SC_OK then
    * @a v_auth_basic_creds is NOT NULL and at least the username data
    * is provided.
    * The result is placed in @a v_auth_basic_creds member.
    */
   MHD_REQUEST_INFO_DYNAMIC_AUTH_BASIC_CREDS = 51
   ,
   /* * Sentinel * */
   /**
    * The sentinel value.
    * This value enforces specific underlying integer type for the enum.
    * Do not use.
    */
   MHD_REQUEST_INFO_DYNAMIC_SENTINEL = 65535
 };
 
 
 /**
  * Dynamic information about a request.
  */
 union MHD_RequestInfoDynamicData
 {
 
   /**
    * The data for the #MHD_REQUEST_INFO_DYNAMIC_HTTP_METHOD_STRING query
    */
   struct MHD_String v_http_method_string;
 
   /**
    * The data for the #MHD_REQUEST_INFO_DYNAMIC_URI query
    */
   struct MHD_String v_uri_string;
 
   /**
    * The data for the #MHD_REQUEST_INFO_DYNAMIC_NUMBER_URI_PARAMS query
    */
   size_t v_number_uri_params_sizet;
 
   /**
    * The data for the #MHD_REQUEST_INFO_DYNAMIC_NUMBER_COOKIES query
    */
   size_t v_number_cookies_sizet;
 
   /**
    * The data for the #MHD_REQUEST_INFO_DYNAMIC_HEADER_SIZE query
    */
   size_t v_header_size_sizet;
 
   /**
    * The data for the #MHD_REQUEST_INFO_DYNAMIC_NUMBER_POST_PARAMS query
    */
   size_t v_number_post_params_sizet;
 
   /**
    * The data for the #MHD_REQUEST_INFO_DYNAMIC_UPLOAD_PRESENT query
    */
   enum MHD_Bool v_upload_present_bool;
 
   /**
    * The data for the #MHD_REQUEST_INFO_DYNAMIC_UPLOAD_CHUNKED query
    */
   enum MHD_Bool v_upload_chunked_bool;
 
   /**
    * The data for the #MHD_REQUEST_INFO_DYNAMIC_UPLOAD_SIZE_TOTAL query
    */
   uint_fast64_t v_upload_size_total_uint64;
 
   /**
    * The data for the #MHD_REQUEST_INFO_DYNAMIC_UPLOAD_SIZE_RECIEVED query
    */
   uint_fast64_t v_upload_size_recieved_uint64;
 
   /**
    * The data for the #MHD_REQUEST_INFO_DYNAMIC_UPLOAD_SIZE_TO_RECIEVE query
    */
   uint_fast64_t v_upload_size_to_recieve_uint64;
 
   /**
    * The data for the #MHD_REQUEST_INFO_DYNAMIC_UPLOAD_SIZE_PROCESSED query
    */
   uint_fast64_t v_upload_size_processed_uint64;
 
   /**
    * The data for the #MHD_REQUEST_INFO_DYNAMIC_UPLOAD_SIZE_TO_PROCESS query
    */
   uint_fast64_t v_upload_size_to_process_uint64;
 
   /**
    * The data for the #MHD_REQUEST_INFO_DYNAMIC_AUTH_DIGEST_INFO query
    */
   const struct MHD_AuthDigestInfo *v_auth_digest_info;
 
   /**
    * The data for the #MHD_REQUEST_INFO_DYNAMIC_AUTH_BASIC_CREDS query
    */
   const struct MHD_AuthBasicCreds *v_auth_basic_creds;
 };
 
 
 /**
  * Obtain dynamic information about the given request.
  * This information may be changed during the lifetime of the request.
  * Most of the data provided is available only when the request line or complete
  * request headers are processed and not available if responding has been
  * started.
  *
  * The wrapper macro #MHD_request_get_info_dynamic() may be more convenient.
  *
  * Any pointers in the returned data are valid until any MHD_Action or
  * MHD_UploadAction is provided. If the data is needed beyond this point,
  * it should be copied.
  *
  * @param request the request to get information about
  * @param info_type the type of information requested
  * @param[out] output_buf the pointer to union to be set to the requested
  *                        information
  * @param output_buf_size the size of the memory area pointed by @a output_buf
  *                        (provided by the caller for storing the requested
  *                        information), in bytes
  * @return #MHD_SC_OK if succeed,
  *         #MHD_SC_INFO_GET_TYPE_UNKNOWN if requested information type is
  *                                       not recognized by MHD,
  *         #MHD_SC_TOO_LATE if request is already being closed or the response
  *                          is being sent
  *         #MHD_SC_TOO_EARLY if requested data is not yet ready (for example,
  *                           headers are not yet received),
  *         #MHD_SC_INFO_GET_TYPE_NOT_APPLICABLE if the requested information is
  *                                              not available for this request
  *                                              due to used configuration/mode,
  *         #MHD_SC_FEATURE_DISABLED if requested functionality is not supported
  *                                  by this MHD build,
  *         #MHD_SC_INFO_GET_BUFF_TOO_SMALL if @a output_buf_size is too small,
  *         #MHD_SC_AUTH_ABSENT if request does not have particular Auth data,
  *         #MHD_SC_CONNECTION_POOL_NO_MEM_AUTH_DATA if connection memory pool
  *                                                  has no space to put decoded
  *                                                  authentication data,
  *         #MHD_SC_REQ_AUTH_DATA_BROKEN if the format of authentication data is
  *                                      incorrect or broken,
  *         other error codes in case of other errors
  * @ingroup specialized
  */
 MHD_EXTERN_ enum MHD_StatusCode
 MHD_request_get_info_dynamic_sz (
   struct MHD_Request *MHD_RESTRICT request,
   enum MHD_RequestInfoDynamicType info_type,
   union MHD_RequestInfoDynamicData *MHD_RESTRICT output_buf,
   size_t output_buf_size)
 MHD_FN_MUST_CHECK_RESULT_ MHD_FN_PAR_NONNULL_ (1)
 MHD_FN_PAR_NONNULL_ (3) MHD_FN_PAR_OUT_ (3);
 
 
 /**
  * Obtain dynamic information about the given request.
  * This information may be changed during the lifetime of the request.
  * Most of the data provided is available only when the request line or complete
  * request headers are processed and not available if responding has been
  * started.
  *
  * Any pointers in the returned data are valid until any MHD_Action or
  * MHD_UploadAction is provided. If the data is needed beyond this point,
  * it should be copied.
  *
  * @param request the request to get information about
  * @param info_type the type of information requested
  * @param[out] output_buf the pointer to union to be set to the requested
  *                        information
  * @return #MHD_SC_OK if succeed,
  *         #MHD_SC_INFO_GET_TYPE_UNKNOWN if requested information type is
  *                                       not recognized by MHD,
  *         #MHD_SC_TOO_LATE if request is already being closed or the response
  *                          is being sent
  *         #MHD_SC_TOO_EARLY if requested data is not yet ready (for example,
  *                           headers are not yet received),
  *         #MHD_SC_INFO_GET_TYPE_NOT_APPLICABLE if the requested information is
  *                                              not available for this request
  *                                              due to used configuration/mode,
  *         #MHD_SC_FEATURE_DISABLED if requested functionality is not supported
  *                                  by this MHD build,
  *         #MHD_SC_AUTH_ABSENT if request does not have particular Auth data,
  *         #MHD_SC_CONNECTION_POOL_NO_MEM_AUTH_DATA if connection memory pool
  *                                                  has no space to put decoded
  *                                                  authentication data,
  *         #MHD_SC_REQ_AUTH_DATA_BROKEN if the format of authentication data is
  *                                      incorrect or broken,
  *         other error codes in case of other errors
  * @ingroup specialized
  */
 #define MHD_request_get_info_dynamic(request,info_type,output_buf) \
         MHD_request_get_info_dynamic_sz ((request), (info_type), \
                                          (output_buf), \
                                          sizeof(*(output_buf)))
 
 /**
  * Callback for serious error condition. The default action is to print
  * an error message and `abort()`.
  * The callback should not return.
  * Some parameters could be empty strings (the strings with zero-termination at
  * zero position) if MHD built without log messages (only for embedded
  * projects).
  *
  * @param cls user specified value
  * @param file where the error occurred, could be empty
  * @param func the name of the function, where the error occurred, may be empty
  * @param line where the error occurred
  * @param message the error details, could be empty
  * @ingroup logging
  */
 typedef void
 (*MHD_PanicCallback) (void *cls,
                       const char *file,
                       const char *func,
                       unsigned int line,
                       const char *message);
 
 
 /**
  * Sets the global error handler to a different implementation.
  * The @a cb will only be called in the case of typically fatal, serious
  * internal consistency issues.
  * These issues should only arise in the case of serious memory corruption or
  * similar problems with the architecture.
  * The @a cb should not return.
  *
  * The default implementation that is used if no panic function is set
  * simply prints an error message and calls `abort()`.  Alternative
  * implementations might call `exit()` or other similar functions.
  *
  * @param cb new error handler, NULL to reset to default handler
  * @param cls passed to @a cb
  * @ingroup logging
  */
 MHD_EXTERN_ void
 MHD_lib_set_panic_func (MHD_PanicCallback cb,
                         void *cls);
 
 #define MHD_lib_set_panic_func_default() \
         MHD_lib_set_panic_func (MHD_STATIC_CAST_ (MHD_PanicCallback,NULL),NULL)