\input texinfo @setfilename microhttpd.info @include version.texi @settitle The GNU libmicrohttpd Reference Manual @copying This manual documents GNU libmicrohttpd version @value{VERSION}, last updated @value{UPDATED}. It is built upon the documentation in the header file @file{microhttpd.h}. @noindent Copyright @copyright{} 2007, 2008, 2009, 2010, 2011 Christian Grothoff @quotation Permission is granted to copy, distribute and/or modify this document under the terms of the GNU Free Documentation License, Version 1.3 or any later version published by the Free Software Foundation; with no Invariant Sections, no Front-Cover Texts, and no Back-Cover Texts. A copy of the license is included in the section entitled "GNU Free Documentation License". @end quotation GNU libmicrohttpd is a GNU package. @end copying @dircategory GNU Libraries @direntry * libmicrohttpd: (microhttpd). Embedded HTTP server library. @end direntry @c @c Titlepage @c @titlepage @title The GNU libmicrohttpd Reference Manual @subtitle Version @value{VERSION} @subtitle @value{UPDATED} @author Marco Maggi (@email{marco.maggi-ipsu@@poste.it}) @author Christian Grothoff (@email{christian@@grothoff.org}) @page @vskip 0pt plus 1filll @insertcopying @end titlepage @summarycontents @contents @macro gnu{} @acronym{GNU} @end macro @macro gpl{} @acronym{LGPL} @end macro @macro http{} @acronym{HTTP} @end macro @macro tcp{} @acronym{TCP} @end macro @macro api{} @acronym{API} @end macro @macro urloc{} @acronym{URL} @end macro @macro uri{} @acronym{URI} @end macro @macro ascii{} @acronym{ASCII} @end macro @c ............................................................ @macro cfunction{arg} @code{\arg\()} @end macro @macro mynull{} @code{NULL} @end macro @macro mhd{} @acronym{MHD} @end macro @c ............................................................ @macro glibcref{NODE, NODE} @pxref{\NODE\, \NODE\, \NODE\, libc} @end macro @c ++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++ @c ------------------------------------------------------------ @ifnottex @node Top @top The GNU libmicrohttpd Library @insertcopying @end ifnottex @menu * microhttpd-intro:: Introduction. * microhttpd-const:: Constants. * microhttpd-struct:: Structures type definition. * microhttpd-cb:: Callback functions definition. * microhttpd-init:: Starting and stopping the server. * microhttpd-inspect:: Implementing external @code{select}. * microhttpd-requests:: Handling requests. * microhttpd-responses:: Building responses to requests. * microhttpd-dauth:: Utilizing Authentication. * microhttpd-post:: Adding a @code{POST} processor. * microhttpd-info:: Obtaining status information. Appendices * GNU-LGPL:: The GNU Lesser General Public License says how you can copy and share almost all of `libmicrohttpd'. * GNU GPL with eCos Extension:: The GNU General Public License with eCos extension says how you can copy and share some parts of `libmicrohttpd'. * GNU-FDL:: The GNU Free Documentation License says how you can copy and share the documentation of `libmicrohttpd'. Indices * Concept Index:: Index of concepts and programs. * Function and Data Index:: Index of functions, variables and data types. * Type Index:: Index of data types. @end menu @c ++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++ @c ------------------------------------------------------------ @node microhttpd-intro @chapter Introduction @noindent All symbols defined in the public @api{} start with @code{MHD_}. @mhd{} is a small @http{} daemon library. As such, it does not have any @api{} for logging errors (you can only enable or disable logging to stderr). Also, it may not support all of the @http{} features directly, where applicable, portions of @http{} may have to be handled by clients of the library. The library is supposed to handle everything that it must handle (because the @api{} would not allow clients to do this), such as basic connection management; however, detailed interpretations of headers --- such as range requests --- and @http{} methods are left to clients. The library does understand @code{HEAD} and will only send the headers of the response and not the body, even if the client supplied a body. The library also understands headers that control connection management (specifically, @code{Connection: close} and @code{Expect: 100 continue} are understood and handled automatically). @mhd{} understands @code{POST} data and is able to decode certain formats (at the moment only @code{application/x-www-form-urlencoded} and @code{multipart/form-data}) using the post processor API. The data stream of a POST is also provided directly to the main application, so unsupported encodings could still be processed, just not conveniently by @mhd{}. The header file defines various constants used by the @http{} protocol. This does not mean that @mhd{} actually interprets all of these values. The provided constants are exported as a convenience for users of the library. @mhd{} does not verify that transmitted @http{} headers are part of the standard specification; users of the library are free to define their own extensions of the @http{} standard and use those with @mhd{}. All functions are guaranteed to be completely reentrant and thread-safe. @mhd{} checks for allocation failures and tries to recover gracefully (for example, by closing the connection). Additionally, clients can specify resource limits on the overall number of connections, number of connections per IP address and memory used per connection to avoid resource exhaustion. @section Including the microhttpd.h header @cindex portability @cindex microhttpd.h Ideally, before including "microhttpd.h" you should add the necessary includes to define the @code{uint64_t}, @code{size_t}, @code{fd_set}, @code{socklen_t} and @code{struct sockaddr} data types. Which specific headers are needed may depend on your platform and your build system might include some tests to provide you with the necessary conditional operations. For possible suggestions consult @code{platform.h} and @code{configure.ac} in the MHD distribution. Once you have ensured that you manually (!) included the right headers for your platform before "microhttpd.h", you should also add a line with @code{#define MHD_PLATFORM_H} which will prevent the "microhttpd.h" header from trying (and, depending on your platform, failing) to include the right headers. If you do not define MHD_PLATFORM_H, the "microhttpd.h" header will automatically include headers needed on GNU/Linux systems (possibly causing problems when porting to other platforms). @section SIGPIPE @cindex signals @mhd{} does not install a signal handler for SIGPIPE. On platforms where this is possible (such as GNU/Linux), it disables SIGPIPE for its I/O operations (by passing MSG_NOSIGNAL). On other platforms, SIGPIPE signals may be generated from network operations by @mhd{} and will cause the process to die unless the developer explicitly installs a signal handler for SIGPIPE. Hence portable code using MHD must install a SIGPIPE handler or explicitly block the SIGPIPE signal. MHD does not do so in order to avoid messing with other parts of the application that may need to handle SIGPIPE in a particular way. You can make your application handle SIGPIPE by calling the following function in @code{main}: @verbatim static void catcher (int sig) { } static void ignore_sigpipe () { struct sigaction oldsig; struct sigaction sig; sig.sa_handler = &catcher; sigemptyset (&sig.sa_mask); #ifdef SA_INTERRUPT sig.sa_flags = SA_INTERRUPT; /* SunOS */ #else sig.sa_flags = SA_RESTART; #endif if (0 != sigaction (SIGPIPE, &sig, &oldsig)) fprintf (stderr, "Failed to install SIGPIPE handler: %s\n", strerror (errno)); } @end verbatim @section MHD_LONG_LONG @cindex long long @cindex IAR @cindex ARM @cindex cortex m3 Some platforms do not support @code{long long}. Hence MHD defines a macro @code{MHD_LONG_LONG} which will default to @code{long long}. If your platform does not support @code{long long}, you should change "platform.h" to define @code{MHD_LONG_LONG} to an appropriate alternative type and also define @code{MHD_LONG_LONG_PRINTF} to the corresponding format string for printing such a data type (without the percent sign). @c ++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++ @c ------------------------------------------------------------ @node microhttpd-const @chapter Constants @deftp {Enumeration} MHD_FLAG Options for the @mhd{} daemon. Note that if neither @code{MHD_USE_THREAD_PER_CONNECTION} nor @code{MHD_USE_SELECT_INTERNALLY} is used, the client wants control over the process and will call the appropriate microhttpd callbacks. Starting the daemon may also fail if a particular option is not implemented or not supported on the target platform (i.e. no support for @acronym{SSL}, threads or IPv6). SSL support generally depends on options given during @mhd{} compilation. Threaded operations (including @code{MHD_USE_SELECT_INTERNALLY}) are not supported on Symbian. @table @code @item MHD_NO_FLAG No options selected. @item MHD_USE_DEBUG @cindex debugging Run in debug mode. If this flag is used, the library should print error messages and warnings to stderr. Note that for this run-time option to have any effect, @mhd{} needs to be compiled with messages enabled. This is done by default except you ran configure with the @code{--disable-messages} flag set. @item MHD_USE_SSL Run in https mode (this option may not work with all threading modes yet). @item MHD_USE_THREAD_PER_CONNECTION Run using one thread per connection. @item MHD_USE_SELECT_INTERNALLY Run using an internal thread doing @code{SELECT}. @item MHD_USE_IPv6 @cindex IPv6 Run using the IPv6 protocol (otherwise, @mhd{} will just support IPv4). @item MHD_USE_PEDANTIC_CHECKS Be pedantic about the protocol (as opposed to as tolerant as possible). Specifically, at the moment, this flag causes @mhd{} to reject @http{} 1.1 connections without a @code{Host} header. This is required by the standard, but of course in violation of the ``be as liberal as possible in what you accept'' norm. It is recommended to turn this @strong{ON} if you are testing clients against @mhd{}, and @strong{OFF} in production. @item MHD_USE_POLL @cindex FD_SETSIZE @cindex poll @cindex select Use poll instead of select. This allows sockets with descriptors @code{>= FD_SETSIZE}. This option only works in conjunction with @code{MHD_USE_THREAD_PER_CONNECTION} (at this point). @end table @end deftp @deftp {Enumeration} MHD_OPTION @mhd{} options. Passed in the varargs portion of @cfunction{MHD_start_daemon}. @table @code @item MHD_OPTION_END No more options / last option. This is used to terminate the VARARGs list. @item MHD_OPTION_CONNECTION_MEMORY_LIMIT @cindex memory, limiting memory utilization Maximum memory size per connection (followed by a @code{size_t}). The default is 32 kB (32*1024 bytes) as defined by the internal constant @code{MHD_POOL_SIZE_DEFAULT}. @item MHD_OPTION_CONNECTION_LIMIT @cindex connection, limiting number of connections Maximum number of concurrent connections to accept (followed by an @code{unsigned int}). The default is @code{FD_SETSIZE - 4} (the maximum number of file descriptors supported by @code{select} minus four for @code{stdin}, @code{stdout}, @code{stderr} and the server socket). In other words, the default is as large as possible. Note that if you set a low connection limit, you can easily get into trouble with browsers doing request pipelining. For example, if your connection limit is ``1'', a browser may open a first connection to access your ``index.html'' file, keep it open but use a second connection to retrieve CSS files, images and the like. In fact, modern browsers are typically by default configured for up to 15 parallel connections to a single server. If this happens, MHD will refuse to even accept the second connection until the first connection is closed --- which does not happen until timeout. As a result, the browser will fail to render the page and seem to hang. If you expect your server to operate close to the connection limit, you should first consider using a lower timeout value and also possibly add a ``Connection: close'' header to your response to ensure that request pipelining is not used and connections are closed immediately after the request has completed: @example MHD_add_response_header (response, MHD_HTTP_HEADER_CONNECTION, "close"); @end example @item MHD_OPTION_CONNECTION_TIMEOUT @cindex timeout After how many seconds of inactivity should a connection automatically be timed out? (followed by an @code{unsigned int}; use zero for no timeout). The default is zero (no timeout). @item MHD_OPTION_NOTIFY_COMPLETED Register a function that should be called whenever a request has been completed (this can be used for application-specific clean up). Requests that have never been presented to the application (via @cfunction{MHD_AccessHandlerCallback}) will not result in notifications. This option should be followed by @strong{TWO} pointers. First a pointer to a function of type @cfunction{MHD_RequestCompletedCallback} and second a pointer to a closure to pass to the request completed callback. The second pointer maybe @mynull{}. @item MHD_OPTION_PER_IP_CONNECTION_LIMIT Limit on the number of (concurrent) connections made to the server from the same IP address. Can be used to prevent one IP from taking over all of the allowed connections. If the same IP tries to establish more than the specified number of connections, they will be immediately rejected. The option should be followed by an @code{unsigned int}. The default is zero, which means no limit on the number of connections from the same IP address. @item MHD_OPTION_SOCK_ADDR @cindex bind, restricting bind Bind daemon to the supplied socket address. This option should be followed by a @code{struct sockaddr *}. If @code{MHD_USE_IPv6} is specified, the @code{struct sockaddr*} should point to a @code{struct sockaddr_in6}, otherwise to a @code{struct sockaddr_in}. If this option is not specified, the daemon will listen to incoming connections from anywhere. @item MHD_OPTION_URI_LOG_CALLBACK @cindex debugging @cindex logging @cindex query string Specify a function that should be called before parsing the URI from the client. The specified callback function can be used for processing the URI (including the options) before it is parsed. The URI after parsing will no longer contain the options, which maybe inconvenient for logging. This option should be followed by two arguments, the first one must be of the form @example void * my_logger(void * cls, const char * uri) @end example where the return value will be passed as @code{*con_cls} in calls to the @code{MHD_AccessHandlerCallback} when this request is processed later; returning a value of NULL has no special significance; (however, note that if you return non-NULL, you can no longer rely on the first call to the access handler having @code{NULL == *con_cls} on entry) @code{cls} will be set to the second argument following MHD_OPTION_URI_LOG_CALLBACK. Finally, @code{uri} will be the 0-terminated URI of the request. @item MHD_OPTION_HTTPS_MEM_KEY @cindex SSL @cindex TLS Memory pointer to the private key to be used by the HTTPS daemon. This option should be followed by an "const char*" argument. This should be used in conjunction with 'MHD_OPTION_HTTPS_MEM_CERT'. @item MHD_OPTION_HTTPS_MEM_CERT @cindex SSL @cindex TLS Memory pointer to the certificate to be used by the HTTPS daemon. This option should be followed by an "const char*" argument. This should be used in conjunction with 'MHD_OPTION_HTTPS_MEM_KEY'. @item MHD_OPTION_HTTPS_MEM_TRUST @cindex SSL @cindex TLS Memory pointer to the CA certificate to be used by the HTTPS daemon to authenticate and trust clients certificates. This option should be followed by an "const char*" argument. The presence of this option activates the request of certificate to the client. The request to the client is marked optional, and it is the responsibility of the server to check the presence of the certificate if needed. Note that most browsers will only present a client certificate only if they have one matching the specified CA, not sending any certificate otherwise. @item MHD_OPTION_HTTPS_CRED_TYPE @cindex SSL @cindex TLS Daemon credentials type. Either certificate or anonymous, this option should be followed by one of the values listed in "enum gnutls_credentials_type_t". @item MHD_OPTION_HTTPS_PRIORITIES @cindex SSL @cindex TLS @cindex cipher SSL/TLS protocol version and ciphers. This option must be followed by an "const char *" argument specifying the SSL/TLS protocol versions and ciphers that are acceptable for the application. The string is passed unchanged to gnutls_priority_init. If this option is not specified, ``NORMAL'' is used. @item MHD_OPTION_DIGEST_AUTH_RANDOM @cindex digest auth @cindex random Digest Authentication nonce's seed. This option should be followed by two arguments. First an integer of type "size_t" which specifies the size of the buffer pointed to by the second argument in bytes. Note that the application must ensure that the buffer of the second argument remains allocated and unmodified while the daemon is running. For security, you SHOULD provide a fresh random nonce when using MHD with Digest Authentication. @item MHD_OPTION_NONCE_NC_SIZE @cindex digest auth @cindex replay attack Size of an array of nonce and nonce counter map. This option must be followed by an "unsigned int" argument that have the size (number of elements) of a map of a nonce and a nonce-counter. If this option is not specified, a default value of 4 will be used (which might be too small for servers handling many requests). If you do not use digest authentication at all, you can specify a value of zero to save some memory. You should calculate the value of NC_SIZE based on the number of connections per second multiplied by your expected session duration plus a factor of about two for hash table collisions. For example, if you expect 100 digest-authenticated connections per second and the average user to stay on your site for 5 minutes, then you likely need a value of about 60000. On the other hand, if you can only expect only 10 digest-authenticated connections per second, tolerate browsers getting a fresh nonce for each request and expect a HTTP request latency of 250 ms, then a value of about 5 should be fine. @item MHD_OPTION_LISTEN_SOCKET @cindex systemd Listen socket to use. Pass a listen socket for MHD to use (systemd-style). If this option is used, MHD will not open its own listen socket(s). The argument passed must be of type "int" and refer to an existing socket that has been bound to a port and is listening. @item MHD_OPTION_EXTERNAL_LOGGER @cindex logging Use the given function for logging error messages. This option must be followed by two arguments; the first must be a pointer to a function of type 'void fun(void * arg, const char * fmt, va_list ap)' and the second a pointer of type 'void*' which will be passed as the "arg" argument to "fun". Note that MHD will not generate any log messages without the MHD_USE_DEBUG flag set and if MHD was compiled with the "--disable-messages" flag. @item MHD_OPTION_THREAD_POOL_SIZE @cindex performance Number (unsigned int) of threads in thread pool. Enable thread pooling by setting this value to to something greater than 1. Currently, thread model must be MHD_USE_SELECT_INTERNALLY if thread pooling is enabled (MHD_start_daemon returns NULL for an unsupported thread model). @item MHD_OPTION_ARRAY @cindex options @cindex foreign-function interface This option can be used for initializing MHD using options from an array. A common use for this is writing an FFI for MHD. The actual options given are in an array of 'struct MHD_OptionItem', so this option requires a single argument of type 'struct MHD_OptionItem'. The array must be terminated with an entry @code{MHD_OPTION_END}. An example for code using MHD_OPTION_ARRAY is: @example struct MHD_OptionItem ops[] = @{ @{ MHD_OPTION_CONNECTION_LIMIT, 100, NULL @}, @{ MHD_OPTION_CONNECTION_TIMEOUT, 10, NULL @}, @{ MHD_OPTION_END, 0, NULL @} @}; d = MHD_start_daemon(0, 8080, NULL, NULL, dh, NULL, MHD_OPTION_ARRAY, ops, MHD_OPTION_END); @end example For options that expect a single pointer argument, the second member of the @code{struct MHD_OptionItem} is ignored. For options that expect two pointer arguments, the first argument must be cast to @code{intptr_t}. @item MHD_OPTION_UNESCAPE_CALLBACK @cindex internationalization @cindex escaping Specify a function that should be called for unescaping escape sequences in URIs and URI arguments. Note that this function will NOT be used by the MHD_PostProcessor. If this option is not specified, the default method will be used which decodes escape sequences of the form "%HH". This option should be followed by two arguments, the first one must be of the form @example size_t my_unescaper(void * cls, struct MHD_Connection *c, char *s) @end example where the return value must be @code{strlen(s)} and @code{s} should be updated. Note that the unescape function must not lengthen @code{s} (the result must be shorter than the input and still be 0-terminated). @code{cls} will be set to the second argument following MHD_OPTION_UNESCAPE_CALLBACK. @item MHD_OPTION_THREAD_STACK_SIZE @cindex stack, thread, pthread Maximum stack size for threads created by MHD. This option must be followed by a @code{size_t}). Not specifying this option or using a value of zero means using the system default (which is likely to differ based on your platform). @end table @end deftp @deftp {C Struct} MHD_OptionItem Entry in an MHD_OPTION_ARRAY. See the @code{MHD_OPTION_ARRAY} option argument for its use. The @code{option} member is used to specify which option is specified in the array. The other members specify the respective argument. Note that for options taking only a single pointer, the @code{ptr_value} member should be set. For options taking two pointer arguments, the first pointer must be cast to @code{intptr_t} and both the @code{value} and the @code{ptr_value} members should be used to pass the two pointers. @end deftp @deftp {Enumeration} MHD_ValueKind The @code{MHD_ValueKind} specifies the source of the key-value pairs in the @http{} protocol. @table @code @item MHD_RESPONSE_HEADER_KIND Response header. @item MHD_HEADER_KIND @http{} header. @item MHD_COOKIE_KIND @cindex cookie Cookies. Note that the original @http{} header containing the cookie(s) will still be available and intact. @item MHD_POSTDATA_KIND @cindex POST method @code{POST} data. This is available only if a content encoding supported by @mhd{} is used (currently only @acronym{URL} encoding), and only if the posted content fits within the available memory pool. Note that in that case, the upload data given to the @cfunction{MHD_AccessHandlerCallback} will be empty (since it has already been processed). @item MHD_GET_ARGUMENT_KIND @code{GET} (@uri{}) arguments. @item MHD_FOOTER_KIND @http{} footer (only for http 1.1 chunked encodings). @end table @end deftp @deftp {Enumeration} MHD_RequestTerminationCode The @code{MHD_RequestTerminationCode} specifies reasons why a request has been terminated (or completed). @table @code @item MHD_REQUEST_TERMINATED_COMPLETED_OK We finished sending the response. @item MHD_REQUEST_TERMINATED_WITH_ERROR Error handling the connection (resources exhausted, other side closed connection, application error accepting request, etc.) @item MHD_REQUEST_TERMINATED_TIMEOUT_REACHED No activity on the connection for the number of seconds specified using @code{MHD_OPTION_CONNECTION_TIMEOUT}. @item MHD_REQUEST_TERMINATED_DAEMON_SHUTDOWN We had to close the session since @mhd{} was being shut down. @end table @end deftp @deftp {Enumeration} MHD_ResponseMemoryMode The @code{MHD_ResponeMemoryMode} specifies how MHD should treat the memory buffer given for the response in @code{MHD_create_response_from_buffer}. @table @code @item MHD_RESPMEM_PERSISTENT Buffer is a persistent (static/global) buffer that won't change for at least the lifetime of the response, MHD should just use it, not free it, not copy it, just keep an alias to it. @item MHD_RESPMEM_MUST_FREE Buffer is heap-allocated with @code{malloc} (or equivalent) and should be freed by MHD after processing the response has concluded (response reference counter reaches zero). @item MHD_RESPMEM_MUST_COPY Buffer is in transient memory, but not on the heap (for example, on the stack or non-malloc allocated) and only valid during the call to @code{MHD_create_response_from_buffer}. MHD must make its own private copy of the data for processing. @end table @end deftp @deftp {Enumeration} MHD_ConnectionInfoType Values of this enum are used to specify what information about a connection is desired. @table @code @item MHD_CONNECTION_INFO_CIPHER_ALGO What cipher algorithm is being used (HTTPS connections only). Takes no extra arguments. NULL is returned for non-HTTPS connections. @item MHD_CONNECTION_INFO_PROTOCOL, Takes no extra arguments. Allows finding out the TLS/SSL protocol used (HTTPS connections only). NULL is returned for non-HTTPS connections. @item MHD_CONNECTION_INFO_CLIENT_ADDRESS Returns information about the address of the client. Returns essentially a @code{struct sockaddr **} (since the API returns a @code{union MHD_ConnectionInfo *} and that union contains a @code{struct sockaddr *}). @item MHD_CONNECTION_INFO_GNUTLS_SESSION, Takes no extra arguments. Allows access to the underlying GNUtls session, including access to the underlying GNUtls client certificate (HTTPS connections only). Takes no extra arguments. NULL is returned for non-HTTPS connections. @item MHD_CONNECTION_INFO_GNUTLS_CLIENT_CERT, Takes no extra arguments. Allows access to the client certificate including access to the underlying GNUtls client certificate (HTTPS connections only). Takes no extra arguments. @item MHD_CONNECTION_INFO_DAEMON Returns information about @code{struct MHD_Daemon} which manages this connection. @end table @end deftp @deftp {Enumeration} MHD_DaemonInfoType Values of this enum are used to specify what information about a daemon is desired. @table @code @item MHD_DAEMON_INFO_KEY_SIZE Request information about the key size for a particular cipher algorithm. The cipher algorithm should be passed as an extra argument (of type 'enum MHD_GNUTLS_CipherAlgorithm'). @item MHD_DAEMON_INFO_MAC_KEY_SIZE Request information about the key size for a particular cipher algorithm. The cipher algorithm should be passed as an extra argument (of type 'enum MHD_GNUTLS_HashAlgorithm'). @item MHD_DAEMON_INFO_LISTEN_FD @cindex listen Request the file-descriptor number that MHD is using to listen to the server socket. This can be useful if no port was specified and a client needs to learn what port is actually being used by MHD. No extra arguments should be passed. @end table @end deftp @c ++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++ @c ------------------------------------------------------------ @node microhttpd-struct @chapter Structures type definition @deftp {C Struct} MHD_Daemon Handle for the daemon (listening on a socket for @http{} traffic). @end deftp @deftp {C Struct} MHD_Connection Handle for a connection / @http{} request. With @http{}/1.1, multiple requests can be run over the same connection. However, @mhd{} will only show one request per @tcp{} connection to the client at any given time. @end deftp @deftp {C Struct} MHD_Response Handle for a response. @end deftp @deftp {C Struct} MHD_PostProcessor @cindex POST method Handle for @code{POST} processing. @end deftp @deftp {C Union} MHD_ConnectionInfo Information about a connection. @end deftp @deftp {C Union} MHD_DaemonInfo Information about an MHD daemon. @end deftp @c ++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++ @c ------------------------------------------------------------ @node microhttpd-cb @chapter Callback functions definition @deftypefn {Function Pointer} int {*MHD_AcceptPolicyCallback} (void *cls, const struct sockaddr * addr, socklen_t addrlen) Invoked in the context of a connection to allow or deny a client to connect. This callback return @code{MHD_YES} if connection is allowed, @code{MHD_NO} if not. @table @var @item cls custom value selected at callback registration time; @item addr address information from the client; @item addrlen length of the address information. @end table @end deftypefn @deftypefn {Function Pointer} int {*MHD_AccessHandlerCallback} (void *cls, struct MHD_Connection * connection, const char *url, const char *method, const char *version, const char *upload_data, size_t *upload_data_size, void **con_cls) Invoked in the context of a connection to answer a request from the client. This callback must call @mhd{} functions (example: the @code{MHD_Response} ones) to provide content to give back to the client and return an @http{} status code (i.e. @code{200} for OK, @code{404}, etc.). @ref{microhttpd-post}, for details on how to code this callback. Must return @code{MHD_YES} if the connection was handled successfully, @code{MHD_NO} if the socket must be closed due to a serious error while handling the request @table @var @item cls custom value selected at callback registration time; @item url the @urloc{} requested by the client; @item method the @http{} method used by the client (@code{GET}, @code{PUT}, @code{DELETE}, @code{POST}, etc.); @item version the @http{} version string (i.e. @code{HTTP/1.1}); @item upload_data the data being uploaded (excluding headers): @cindex POST method @cindex PUT method @itemize @item for a @code{POST} that fits into memory and that is encoded with a supported encoding, the @code{POST} data will @strong{NOT} be given in @var{upload_data} and is instead available as part of @cfunction{MHD_get_connection_values}; @item very large @code{POST} data @strong{will} be made available incrementally in @var{upload_data}; @end itemize @item upload_data_size set initially to the size of the @var{upload_data} provided; this callback must update this value to the number of bytes @strong{NOT} processed; unless external select is used, the callback maybe required to process at least some data. If the callback fails to process data in multi-threaded or internal-select mode and if the read-buffer is already at the maximum size that MHD is willing to use for reading (about half of the maximum amount of memory allowed for the connection), then MHD will abort handling the connection and return an internal server error to the client. In order to avoid this, clients must be able to process upload data incrementally and reduce the value of @code{upload_data_size}. @item con_cls reference to a pointer, initially set to @mynull{}, that this callback can set to some address and that will be preserved by @mhd{} for future calls for this request; since the access handler may be called many times (i.e., for a @code{PUT}/@code{POST} operation with plenty of upload data) this allows the application to easily associate some request-specific state; if necessary, this state can be cleaned up in the global @code{MHD_RequestCompletedCallback} (which can be set with the @code{MHD_OPTION_NOTIFY_COMPLETED}). @end table @end deftypefn @deftypefn {Function Pointer} void {*MHD_RequestCompletedCallback} (void *cls, struct MHD_Connectionconnection, void **con_cls, enum MHD_RequestTerminationCode toe) Signature of the callback used by @mhd{} to notify the application about completed requests. @table @var @item cls custom value selected at callback registration time; @item connection connection handle; @item con_cls value as set by the last call to the @code{MHD_AccessHandlerCallback}; @item toe reason for request termination see @code{MHD_OPTION_NOTIFY_COMPLETED}. @end table @end deftypefn @deftypefn {Function Pointer} int {*MHD_KeyValueIterator} (void *cls, enum MHD_ValueKind kind, const char *key, const char *value) Iterator over key-value pairs. This iterator can be used to iterate over all of the cookies, headers, or @code{POST}-data fields of a request, and also to iterate over the headers that have been added to a response. Return @code{MHD_YES} to continue iterating, @code{MHD_NO} to abort the iteration. @end deftypefn @deftypefn {Function Pointer} int {*MHD_ContentReaderCallback} (void *cls, uint64_t pos, char *buf, size_t max) Callback used by @mhd{} in order to obtain content. The callback has to copy at most @var{max} bytes of content into @var{buf}. The total number of bytes that has been placed into @var{buf} should be returned. Note that returning zero will cause @mhd{} to try again, either ``immediately'' if in multi-threaded mode (in which case the callback may want to do blocking operations to avoid busy waiting) or in the next round if @code{MHD_run} is used. Returning zero for a daemon that runs in internal @cfunction{select} mode is an error (since it would result in busy waiting) and cause the program to be aborted (@cfunction{abort}). While usually the callback simply returns the number of bytes written into @var{buf}, there are two special return value: @code{MHD_CONTENT_READER_END_OF_STREAM} (-1) should be returned for the regular end of transmission (with chunked encoding, MHD will then terminate the chunk and send any HTTP footers that might be present; without chunked encoding and given an unknown response size, @mhd{} will simply close the connection; note that while returning @code{MHD_CONTENT_READER_END_OF_STREAM} is not technically legal if a response size was specified, MHD accepts this and treats it just as @code{MHD_CONTENT_READER_END_WITH_ERROR}. @code{MHD_CONTENT_READER_END_WITH_ERROR} (-2) is used to indicate a server error generating the response; this will cause @mhd{} to simply close the connection immediately. If a response size was given or if chunked encoding is in use, this will indicate an error to the client. Note, however, that if the client does not know a response size and chunked encoding is not in use, then clients will not be able to tell the difference between @code{MHD_CONTENT_READER_END_WITH_ERROR} and @code{MHD_CONTENT_READER_END_OF_STREAM}. This is not a limitation of @mhd{} but rather of the HTTP protocol. @table @var @item cls custom value selected at callback registration time; @item pos position in the datastream to access; note that if an @code{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 an @code{MHD_Response} is not re-used, @mhd{} guarantees that @var{pos} will be the sum of all non-negative return values obtained from the content reader so far. @end table Return @code{-1} on error (@mhd{} will no longer try to read content and instead close the connection with the client). @end deftypefn @deftypefn {Function Pointer} void {*MHD_ContentReaderFreeCallback} (void *cls) This method is called by @mhd{} if we are done with a content reader. It should be used to free resources associated with the content reader. @end deftypefn @deftypefn {Function Pointer} int {*MHD_PostDataIterator} (void *cls, enum MHD_ValueKind kind, const char *key, const char *filename, const char *content_type, const char *transfer_encoding, const char *data, uint64_t off, size_t size) Iterator over key-value pairs where the value maybe made available in increments and/or may not be zero-terminated. Used for processing @code{POST} data. @table @var @item cls custom value selected at callback registration time; @item kind type of the value; @item key zero-terminated key for the value; @item filename name of the uploaded file, @mynull{} if not known; @item content_type mime-type of the data, @mynull{} if not known; @item transfer_encoding encoding of the data, @mynull{} if not known; @item data pointer to size bytes of data at the specified offset; @item off offset of data in the overall value; @item size number of bytes in data available. @end table Return @code{MHD_YES} to continue iterating, @code{MHD_NO} to abort the iteration. @end deftypefn @c ++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++ @c ------------------------------------------------------------ @node microhttpd-init @chapter Starting and stopping the server @deftypefun {void} MHD_set_panic_func (MHD_PanicCallback cb, void *cls) Set a handler for fatal errors. @table @var @item cb function to call if MHD encounters a fatal internal error. If no handler was set explicitly, MHD will call @code{abort}. @item cls closure argument for cb; the other arguments are the name of the source file, line number and a string describing the nature of the fatal error (which can be NULL) @end table @end deftypefun @deftypefun {struct MHD_Daemon *} MHD_start_daemon (unsigned int flags, unsigned short port, MHD_AcceptPolicyCallback apc, void *apc_cls, MHD_AccessHandlerCallback dh, void *dh_cls, ...) Start a webserver on the given port. @table @var @item flags OR-ed combination of @code{MHD_FLAG} values; @item port port to bind to; @item apc callback to call to check which clients will be allowed to connect; you can pass @mynull{} in which case connections from any @acronym{IP} will be accepted; @item apc_cls extra argument to @var{apc}; @item dh default handler for all @uri{}s; @item dh_cls extra argument to @var{dh}. @end table Additional arguments are a list of options (type-value pairs, terminated with @code{MHD_OPTION_END}). It is mandatory to use @code{MHD_OPTION_END} as last argument, even when there are no additional arguments. Return @mynull{} on error, handle to daemon on success. @end deftypefun @deftypefun void MHD_stop_daemon (struct MHD_Daemon *daemon) Shutdown an @http{} daemon. @end deftypefun @deftypefun int MHD_run (struct MHD_Daemon *daemon) Run webserver operations (without blocking unless in client callbacks). This method should be called by clients in combination with @cfunction{MHD_get_fdset} if the client-controlled @cfunction{select} method is used. Return @code{MHD_YES} on success, @code{MHD_NO} if this daemon was not started with the right options for this call. @end deftypefun @deftypefun void MHD_add_connection (struct MHD_Daemon *daemon, int client_socket, const struct sockaddr *addr, socklen_t addrlen) 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. 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. @table @var @item daemon daemon that manages the connection @item client_socket socket to manage (MHD will expect to receive an HTTP request from this socket next). @item addr IP address of the client @item addrlen number of bytes in addr @end table This function will return @code{MHD_YES} on success, @code{MHD_NO} if this daemon could not handle the connection (i.e. malloc failed, etc). The socket will be closed in any case. @end deftypefun @c ++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++ @c ----------------------------------------------------------- @node microhttpd-inspect @chapter Implementing external @code{select} @deftypefun int MHD_get_fdset (struct MHD_Daemon *daemon, fd_set * read_fd_set, fd_set * write_fd_set, fd_set * except_fd_set, int *max_fd) Obtain the @cfunction{select} sets for this daemon. The daemon's socket is added to @var{read_fd_set}. The list of currently existent connections is scanned and their file descriptors added to the correct set. @glibcref{Waiting for I/O}, for details on file descriptor sets. After the call completed successfully: the variable referenced by @var{max_fd} references the file descriptor with highest integer identifier. The variable must be set to zero before invoking this function. Return @code{MHD_YES} on success, @code{MHD_NO} if: the arguments are invalid (example: @mynull{} pointers); this daemon was not started with the right options for this call. @end deftypefun @deftypefun int MHD_get_timeout (struct MHD_Daemon *daemon, unsigned long long *timeout) @cindex timeout Obtain timeout value for select for this daemon (only needed if connection timeout is used). The returned value is how long @cfunction{select} should at most block, not the timeout value set for connections. @table @var @cindex timeout set to the timeout (in milliseconds). @end table Return @code{MHD_YES} on success, @code{MHD_NO} if timeouts are not used (or no connections exist that would necessiate the use of a timeout right now). @end deftypefun @c ++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++ @c ----------------------------------------------------------- @node microhttpd-requests @chapter Handling requests @deftypefun int MHD_get_connection_values (struct MHD_Connection *connection, enum MHD_ValueKind kind, MHD_KeyValueIterator iterator, void *iterator_cls) Get all the headers matching @var{kind} from the request. The @var{iterator} callback is invoked once for each header, with @var{iterator_cls} as first argument. Return the number of entries iterated over; this can be less than the number of headers if, while iterating, @var{iterator} returns @code{MHD_NO}. @var{iterator} can be @mynull{}: in this case this function just counts and returns the number of headers. @end deftypefun @deftypefun int MHD_set_connection_value (struct MHD_Connection *connection, enum MHD_ValueKind kind, const char * key, const char * value) This function can be used to add an entry to the HTTP headers of a connection (so that the MHD_get_connection_values function will return them -- and the MHD PostProcessor will also see them). This maybe required in certain situations (see Mantis #1399) where (broken) HTTP implementations fail to supply values needed by the post processor (or other parts of the application). This function MUST only be called from within the MHD_AccessHandlerCallback (otherwise, access maybe improperly synchronized). Furthermore, the client must guarantee that the key and value arguments are 0-terminated strings that are NOT freed until the connection is closed. (The easiest way to do this is by passing only arguments to permanently allocated strings.). @var{connection} is the connection for which the entry for @var{key} of the given @var{kind} should be set to the given @var{value}. The function returns @code{MHD_NO} if the operation could not be performed due to insufficient memory and @code{MHD_YES} on success. @end deftypefun @deftypefun {const char *} MHD_lookup_connection_value (struct MHD_Connection *connection, enum MHD_ValueKind kind, const char *key) Get a particular header value. If multiple values match the @var{kind}, return one of them (the ``first'', whatever that means). @var{key} must reference a zero-terminated @ascii{}-coded string representing the header to look for: it is compared against the headers using @cfunction{strcasecmp}, so case is ignored. Return @mynull{} if no such item was found. @end deftypefun @c ++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++ @c ------------------------------------------------------------ @node microhttpd-responses @chapter Building answers to responses @noindent Response objects handling by @mhd{} is asynchronous with respect to the application execution flow. Instances of the @code{MHD_Response} structure are not associated to a daemon and neither to a client connection: they are managed with reference counting. In the simplest case: we allocate a new @code{MHD_Response} structure for each response, we use it once and finally we destroy it. @mhd{} allows more efficient resources usages. Example: we allocate a new @code{MHD_Response} structure for each response @strong{kind}, we use it every time we have to give that response and we finally destroy it only when the daemon shuts down. @menu * microhttpd-response enqueue:: Enqueuing a response. * microhttpd-response create:: Creating a response object. * microhttpd-response headers:: Adding headers to a response. * microhttpd-response inspect:: Inspecting a response object. @end menu @c ++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++ @c ------------------------------------------------------------ @node microhttpd-response enqueue @section Enqueuing a response @deftypefun int MHD_queue_response (struct MHD_Connection *connection, unsigned int status_code, struct MHD_Response *response) Queue a response to be transmitted to the client as soon as possible but only after MHD_AccessHandlerCallback returns. This function checks that it is legal to queue a response at this time for the given connection. It also increments the internal reference counter for the response object (the counter will be decremented automatically once the response has been transmitted). @table @var @item connection the connection identifying the client; @item status_code @http{} status code (i.e. @code{200} for OK); @item response response to transmit. @end table Return @code{MHD_YES} on success or if message has been queued. Return @code{MHD_NO}: if arguments are invalid (example: @mynull{} pointer); on error (i.e. reply already sent). @end deftypefun @deftypefun void MHD_destroy_response (struct MHD_Response *response) Destroy a response object and associated resources (decrement the reference counter). Note that @mhd{} may keep some of the resources around if the response is still in the queue for some clients, so the memory may not necessarily be freed immediately. @end deftypefun An explanation of reference counting@footnote{Note to readers acquainted to the Tcl @api{}: reference counting on @code{MHD_Connection} structures is handled in the same way as Tcl handles @code{Tcl_Obj} structures through @cfunction{Tcl_IncrRefCount} and @cfunction{Tcl_DecrRefCount}.}: @enumerate @item a @code{MHD_Response} object is allocated: @example struct MHD_Response * response = MHD_create_response_from_buffer(...); /* here: reference counter = 1 */ @end example @item the @code{MHD_Response} object is enqueued in a @code{MHD_Connection}: @example MHD_queue_response(connection, , response); /* here: reference counter = 2 */ @end example @item the creator of the response object discharges responsibility for it: @example MHD_destroy_response(response); /* here: reference counter = 1 */ @end example @item the daemon handles the connection sending the response's data to the client then decrements the reference counter by calling @cfunction{MHD_destroy_response}: the counter's value drops to zero and the @code{MHD_Response} object is released. @end enumerate @c ++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++ @c ------------------------------------------------------------ @node microhttpd-response create @section Creating a response object @deftypefun {struct MHD_Response *} MHD_create_response_from_callback (uint64_t size, size_t block_size, MHD_ContentReaderCallback crc, void *crc_cls, MHD_ContentReaderFreeCallback crfc) Create a response object. The response object can be extended with header information and then it can be used any number of times. @table @var @item size size of the data portion of the response, @code{-1} for unknown; @item block_size preferred block size for querying @var{crc} (advisory only, @mhd{} may still call @var{crc} using smaller chunks); this is essentially the buffer size used for @acronym{IO}, clients should pick a value that is appropriate for @acronym{IO} and memory performance requirements; @item crc callback to use to obtain response data; @item crc_cls extra argument to @var{crc}; @item crfc callback to call to free @var{crc_cls} resources. @end table Return @mynull{} on error (i.e. invalid arguments, out of memory). @end deftypefun @deftypefun {struct MHD_Response *} MHD_create_response_from_fd (uint64_t size, int fd) Create a response object. The response object can be extended with header information and then it can be used any number of times. Function is deprecated, use @code{MHD_create_response_from_fd_at_offset} instead (with an offset of zero). @table @var @item size size of the data portion of the response (should be smaller or equal to the size of the file) @item fd file descriptor referring to a file on disk with the data; will be closed when response is destroyed; note that 'fd' must be an actual file descriptor (not a pipe or socket) since MHD might use 'sendfile' or 'seek' on it. The descriptor should be in blocking-IO mode. @end table Return @mynull{} on error (i.e. invalid arguments, out of memory). @end deftypefun @deftypefun {struct MHD_Response *} MHD_create_response_from_fd_at_offset (uint64_t size, int fd, off_t offset) Create a response object. The response object can be extended with header information and then it can be used any number of times. Note that you need to be a bit careful about @code{off_t} when writing this code. Depending on your platform, @mhd{} is likely to have been compiled with support for 64-bit files. When you compile your own application, you must make sure that @code{off_t} is also a 64-bit value. If not, your compiler may pass a 32-bit value as @code{off_t}, which will result in 32-bits of garbage. If you use the autotools, use the @code{AC_SYS_LARGEFILE} autoconf macro and make sure to include the generated @file{config.h} file before @file{microhttpd.h} to avoid problems. If you do not have a build system and only want to run on a GNU/Linux system, you could also use @verbatim #define _FILE_OFFSET_BITS 64 #include #include #include #include @end verbatim to ensure 64-bit @code{off_t}. Note that if your operating system does not support 64-bit files, @mhd{} will be compiled with a 32-bit @code{off_t} (in which case the above would be wrong...). @table @var @item size size of the data portion of the response (number of bytes to transmit from the file starting at offset). @item fd file descriptor referring to a file on disk with the data; will be closed when response is destroyed; note that 'fd' must be an actual file descriptor (not a pipe or socket) since MHD might use 'sendfile' or 'seek' on it. The descriptor should be in blocking-IO mode. @item offset offset to start reading from in the file @end table Return @mynull{} on error (i.e. invalid arguments, out of memory). @end deftypefun @deftypefun {struct MHD_Response *} MHD_create_response_from_buffer (size_t size, void *data, enum MHD_ResponseMemoryMode mode) Create a response object. The response object can be extended with header information and then it can be used any number of times. @table @var @item size size of the data portion of the response; @item buffer the data itself; @item mode memory management options for buffer; use MHD_RESPMEM_PERSISTENT if the buffer is static/global memory, use MHD_RESPMEM_MUST_FREE if the buffer is heap-allocated and should be freed by @mhd{} and MHD_RESPMEM_MUST_COPY if the buffer is in transient memory (i.e. on the stack) and must be copied by @mhd{}; @end table Return @mynull{} on error (i.e. invalid arguments, out of memory). @end deftypefun @deftypefun {struct MHD_Response *} MHD_create_response_from_data (size_t size, void *data, int must_free, int must_copy) Create a response object. The response object can be extended with header information and then it can be used any number of times. This function is deprecated, use @code{MHD_create_response_from_buffer} instead. @table @var @item size size of the data portion of the response; @item data the data itself; @item must_free if true: @mhd{} should free data when done; @item must_copy if true: @mhd{} allocates a block of memory and use it to make a copy of @var{data} embedded in the returned @code{MHD_Response} structure; handling of the embedded memory is responsibility of @mhd{}; @var{data} can be released anytime after this call returns. @end table Return @mynull{} on error (i.e. invalid arguments, out of memory). @end deftypefun Example: create a response from a statically allocated string: @example const char * data = "

Error!

"; struct MHD_Connection * connection = ...; struct MHD_Response * response; response = MHD_create_response_from_buffer (strlen(data), data, MHD_RESPMEM_PERSISTENT); MHD_queue_response(connection, 404, response); MHD_destroy_response(response); @end example @c ++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++ @c ------------------------------------------------------------ @node microhttpd-response headers @section Adding headers to a response @deftypefun int MHD_add_response_header (struct MHD_Response *response, const char *header, const char *content) Add a header line to the response. The strings referenced by @var{header} and @var{content} must be zero-terminated and they are duplicated into memory blocks embedded in @var{response}. Notice that the strings must not hold newlines, carriage returns or tab chars. Return @code{MHD_NO} on error (i.e. invalid header or content format or memory allocation error). @end deftypefun @deftypefun int MHD_add_response_footer (struct MHD_Response *response, const char *footer, const char *content) Add a footer line to the response. The strings referenced by @var{footer} and @var{content} must be zero-terminated and they are duplicated into memory blocks embedded in @var{response}. Notice that the strings must not hold newlines, carriage returns or tab chars. You can add response footers at any time before signalling the end of the response to MHD (not just before calling 'MHD_queue_response'). Footers are useful for adding cryptographic checksums to the reply or to signal errors encountered during data generation. This call was introduced in MHD 0.9.3. Return @code{MHD_NO} on error (i.e. invalid header or content format or memory allocation error). @end deftypefun @deftypefun int MHD_del_response_header (struct MHD_Response *response, const char *header, const char *content) Delete a header (or footer) line from the response. Return @code{MHD_NO} on error (arguments are invalid or no such header known). @end deftypefun @c ++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++ @c ------------------------------------------------------------ @node microhttpd-response inspect @section Inspecting a response object @deftypefun int MHD_get_response_headers (struct MHD_Response *response, MHD_KeyValueIterator iterator, void *iterator_cls) Get all of the headers added to a response. Invoke the @var{iterator} callback for each header in the response, using @var{iterator_cls} as first argument. Return number of entries iterated over. @var{iterator} can be @mynull{}: in this case the function just counts headers. @var{iterator} should not modify the its key and value arguments, unless we know what we are doing. @end deftypefun @deftypefun {const char *} MHD_get_response_header (struct MHD_Response *response, const char *key) Find and return a pointer to the value of a particular header from the response. @var{key} must reference a zero-terminated string representing the header to look for. The search is case sensitive. Return @mynull{} if header does not exist or @var{key} is @mynull{}. We should not modify the value, unless we know what we are doing. @end deftypefun @c ++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++ @c ------------------------------------------------------------ @node microhttpd-dauth @chapter Utilizing Authentication @noindent @mhd{} support three types of client authentication. Basic authentication uses a simple authentication method based on BASE64 algorithm. Username and password are exchanged in clear between the client and the server, so this method must only be used for non-sensitive content or when the session is protected with https. When using basic authentication @mhd{} will have access to the clear password, possibly allowing to create a chained authentication toward an external authentication server. Digest authentication uses a one-way authentication method based on MD5 hash algorithm. Only the hash will transit over the network, hence protecting the user password. The nonce will prevent replay attacks. This method is appropriate for general use, especially when https is not used to encrypt the session. Client certificate authentication uses a X.509 certificate from the client. This is the strongest authentication mechanism but it requires the use of HTTPS. Client certificate authentication can be used simultaneously with Basic or Digest Authentication in order to provide a two levels authentication (like for instance separate machine and user authentication). A code example for using client certificates is presented in the @mhd{} tutorial. @menu * microhttpd-dauth basic:: Using Basic Authentication. * microhttpd-dauth digest:: Using Digest Authentication. @end menu @c ++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++ @c ------------------------------------------------------------ @node microhttpd-dauth basic @section Using Basic Authentication @deftypefun {char *} MHD_basic_auth_get_username_password (struct MHD_Connection *connection, char** password) Get the username and password from the basic authorization header sent by the client. Return @mynull{} if no username could be found, a pointer to the username if found. If returned value is not @mynull{}, the value must be @code{free()}'ed. @var{password} reference a buffer to store the password. It can be @mynull{}. If returned value is not @mynull{}, the value must be @code{free()}'ed. @end deftypefun @deftypefun {int} MHD_queue_basic_auth_fail_response (struct MHD_Connection *connection, const char *realm, struct MHD_Response *response) Queues a response to request basic authentication from the client. Return @code{MHD_YES} if successful, otherwise @code{MHD_NO}. @var{realm} must reference to a zero-terminated string representing the realm. @var{response} a response structure to specify what shall be presented to the client with a 401 HTTP status. @end deftypefun @c ++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++ @c ------------------------------------------------------------ @node microhttpd-dauth digest @section Using Digest Authentication @deftypefun {char *} MHD_digest_auth_get_username (struct MHD_Connection *connection) Find and return a pointer to the username value from the request header. Return @mynull{} if the value is not found or header does not exist. If returned value is not @mynull{}, the value must be @code{free()}'ed. @end deftypefun @deftypefun int MHD_digest_auth_check (struct MHD_Connection *connection, const char *realm, const char *username, const char *password, unsigned int nonce_timeout) Checks if the provided values in the WWW-Authenticate header are valid and sound according to RFC2716. If valid return @code{MHD_YES}, otherwise return @code{MHD_NO}. @var{realm} must reference to a zero-terminated string representing the realm. @var{username} must reference to a zero-terminated string representing the username, it is usually the returned value from MHD_digest_auth_get_username. @var{password} must reference to a zero-terminated string representing the password, most probably it will be the result of a lookup of the username against a local database. @var{nonce_timeout} is the amount of time in seconds for a nonce to be invalid. Most of the time it is sound to specify 300 seconds as its values. @end deftypefun @deftypefun int MHD_queue_auth_fail_response (struct MHD_Connection *connection, const char *realm, const char *opaque, struct MHD_Response *response, int signal_stale) Queues a response to request authentication from the client, return @code{MHD_YES} if successful, otherwise @code{MHD_NO}. @var{realm} must reference to a zero-terminated string representing the realm. @var{opaque} must reference to a zero-terminated string representing a value that gets passed to the client and expected to be passed again to the server as-is. This value can be a hexadecimal or base64 string. @var{response} a response structure to specify what shall be presented to the client with a 401 HTTP status. @var{signal_stale} a value that signals "stale=true" in the response header to indicate the invalidity of the nonce and no need to ask for authentication parameters and only a new nonce gets generated. @code{MHD_YES} to generate a new nonce, @code{MHD_NO} to ask for authentication parameters. @end deftypefun Example: handling digest authentication requests and responses. @example #define PAGE "libmicrohttpd demoAccess granted" #define DENIED "libmicrohttpd demoAccess denied" #define OPAQUE "11733b200778ce33060f31c9af70a870ba96ddd4" static int ahc_echo (void *cls, struct MHD_Connection *connection, const char *url, const char *method, const char *version, const char *upload_data, size_t *upload_data_size, void **ptr) @{ struct MHD_Response *response; char *username; const char *password = "testpass"; const char *realm = "test@@example.com"; int ret; username = MHD_digest_auth_get_username(connection); if (username == NULL) @{ response = MHD_create_response_from_buffer(strlen (DENIED), DENIED, MHD_RESPMEM_PERSISTENT); ret = MHD_queue_auth_fail_response(connection, realm, OPAQUE, response, MHD_NO); MHD_destroy_response(response); return ret; @} ret = MHD_digest_auth_check(connection, realm, username, password, 300); free(username); if ( (ret == MHD_INVALID_NONCE) || (ret == MHD_NO) ) @{ response = MHD_create_response_from_buffer(strlen (DENIED), DENIED, MHD_RESPMEM_PERSISTENT); if (NULL == response) return MHD_NO; ret = MHD_queue_auth_fail_response(connection, realm, OPAQUE, response, (ret == MHD_INVALID_NONCE) ? MHD_YES : MHD_NO); MHD_destroy_response(response); return ret; @} response = MHD_create_response_from_buffer (strlen(PAGE), PAGE, MHD_RESPMEM_PERSISTENT); ret = MHD_queue_response(connection, MHD_HTTP_OK, response); MHD_destroy_response(response); return ret; @} @end example @c ++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++ @c ------------------------------------------------------------ @node microhttpd-post @chapter Adding a @code{POST} processor @cindex POST method @menu * microhttpd-post api:: Programming interface for the @code{POST} processor. @end menu @noindent @mhd{} provides the post processor API to make it easier for applications to parse the data of a client's @code{POST} request: the @code{MHD_AccessHandlerCallback} will be invoked multiple times to process data as it arrives; at each invocation a new chunk of data must be processed. The arguments @var{upload_data} and @var{upload_data_size} are used to reference the chunk of data. When @code{MHD_AccessHandlerCallback} is invoked for a new connection: its @code{*@var{con_cls}} argument is set to @mynull{}. When @code{POST} data comes in the upload buffer it is @strong{mandatory} to use the @var{con_cls} to store a reference to per-connection data. The fact that the pointer was initially @mynull{} can be used to detect that this is a new request. One method to detect that a new connection was established is to set @code{*con_cls} to an unused integer: @example int access_handler (void *cls, struct MHD_Connection * connection, const char *url, const char *method, const char *version, const char *upload_data, size_t *upload_data_size, void **con_cls) @{ static int old_connection_marker; int new_connection = (MYNULL == *con_cls); if (new_connection) @{ /* new connection with POST */ *con_cls = &old_connection_marker; @} ... @} @end example @noindent In contrast to the previous example, for @code{POST} requests in particular, it is more common to use the value of @code{*con_cls} to keep track of actual state used during processing, such as the post processor (or a struct containing a post processor): @example int access_handler (void *cls, struct MHD_Connection * connection, const char *url, const char *method, const char *version, const char *upload_data, size_t *upload_data_size, void **con_cls) @{ struct MHD_PostProcessor * pp = *con_cls; if (pp == NULL) @{ pp = MHD_create_post_processor(connection, ...); *con_cls = pp; return MHD_YES; @} if (*upload_data_size) @{ MHD_post_process(pp, upload_data, *upload_data_size); *upload_data_size = 0; return MHD_YES; @} else @{ MHD_destroy_post_processor(pp); return MHD_queue_response(...); @} @} @end example Note that the callback from @code{MHD_OPTION_NOTIFY_COMPLETED} should be used to destroy the post processor. This cannot be done inside of the access handler since the connection may not always terminate normally. @c ++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++ @c ------------------------------------------------------------ @node microhttpd-post api @section Programming interface for the @code{POST} processor @cindex POST method @deftypefun {struct MHD_PostProcessor *} MHD_create_post_processor (struct MHD_Connection *connection, size_t buffer_size, MHD_PostDataIterator iterator, void *iterator_cls) Create a PostProcessor. A PostProcessor can be used to (incrementally) parse the data portion of a @code{POST} request. @table @var @item connection the connection on which the @code{POST} is happening (used to determine the @code{POST} format); @item buffer_size maximum number of bytes to use for internal buffering (used only for the parsing, specifically the parsing of the keys). A tiny value (256-1024) should be sufficient; do @strong{NOT} use a value smaller than 256; @item iterator iterator to be called with the parsed data; must @strong{NOT} be @mynull{}; @item iterator_cls custom value to be used as first argument to @var{iterator}. @end table Return @mynull{} on error (out of memory, unsupported encoding), otherwise a PP handle. @end deftypefun @deftypefun int MHD_post_process (struct MHD_PostProcessor *pp, const char *post_data, size_t post_data_len) Parse and process @code{POST} data. Call this function when @code{POST} data is available (usually during an @code{MHD_AccessHandlerCallback}) with the @var{upload_data} and @var{upload_data_size}. Whenever possible, this will then cause calls to the @code{MHD_IncrementalKeyValueIterator}. @table @var @item pp the post processor; @item post_data @var{post_data_len} bytes of @code{POST} data; @item post_data_len length of @var{post_data}. @end table Return @code{MHD_YES} on success, @code{MHD_NO} on error (out-of-memory, iterator aborted, parse error). @end deftypefun @deftypefun int MHD_destroy_post_processor (struct MHD_PostProcessor *pp) Release PostProcessor resources. After this function is being called, the PostProcessor is guaranteed to no longer call its iterator. There is no special call to the iterator to indicate the end of the post processing stream. After destroying the PostProcessor, the programmer should perform any necessary work to complete the processing of the iterator. Return @code{MHD_YES} if processing completed nicely, @code{MHD_NO} if there were spurious characters or formatting problems with the post request. It is common to ignore the return value of this function. @end deftypefun @c ++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++ @c ------------------------------------------------------------ @node microhttpd-info @chapter Obtaining status information. @menu * microhttpd-info daemon:: State information about an MHD daemon * microhttpd-info conn:: State information about a connection @end menu @c ------------------------------------------------------------ @node microhttpd-info daemon @section Obtaining state information about an MHD daemon @deftypefun {const union MHD_DaemonInfo *} MHD_get_daemon_info (struct MHD_Daemon *daemon, enum MHD_DaemonInfoType infoType, ...) Obtain information about the given daemon. This function is currently not fully implemented. @table @var @item daemon the daemon about which information is desired; @item infoType type of information that is desired @item ... additional arguments about the desired information (depending on infoType) @end table Returns a union with the respective member (depending on infoType) set to the desired information), or NULL in case the desired information is not available or applicable. @end deftypefun @c ------------------------------------------------------------ @node microhttpd-info conn @section Obtaining state information about a connection @deftypefun {const union MHD_ConnectionInfo *} MHD_get_connection_info (struct MHD_Connection *daemon, enum MHD_ConnectionInfoType infoType, ...) Obtain information about the given connection. @table @var @item connection the connection about which information is desired; @item infoType type of information that is desired @item ... additional arguments about the desired information (depending on infoType) @end table Returns a union with the respective member (depending on infoType) set to the desired information), or NULL in case the desired information is not available or applicable. @end deftypefun @c ++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++ @c ********************************************************** @c ******************* Appendices ************************* @c ********************************************************** @node GNU-LGPL @unnumbered GNU-LGPL @cindex license @include lgpl.texi @node GNU GPL with eCos Extension @unnumbered GNU GPL with eCos Extension @cindex license @include ecos.texi @node GNU-FDL @unnumbered GNU-FDL @cindex license @include fdl-1.3.texi @node Concept Index @unnumbered Concept Index @printindex cp @node Function and Data Index @unnumbered Function and Data Index @printindex fn @node Type Index @unnumbered Type Index @printindex tp @bye