add explicit nonnull declarations to function arguments

7 files changed, 525 insertions, 84 deletions

diff --git a/src/include/microhttpd2.h b/src/include/microhttpd2.h
index 2fae90b1..2ec39acb 100644
--- a/src/include/microhttpd2.h
+++ b/src/include/microhttpd2.h
@@ -267,6 +267,16 @@ typedef SOCKET MHD_socket;
 #define _MHD_DEPR_FUNC(msg)
 #endif /* !_MHD_DEPR_FUNC */
 
+
+/* Define MHD_NONNULL attribute */
+
+/**
+ * Macro to indicate that certain parameters must be
+ * non-null.  Todo: port to non-gcc platforms.
+ */
+#define MHD_NONNULL(...) __THROW __nonnull((__VA_ARGS__))
+
+  
 /**
  * Not all architectures and `printf()`'s support the `long long` type.
  * This gives the ability to replace `long long` with just a `long`,
@@ -541,6 +551,17 @@ enum MHD_StatusCode
    */
   MHD_SC_EPOLL_CTL_CONFIGURE_NOINHERIT_FAILED = 50035,
 
+  /**
+   * We failed to build the FD set because a socket was
+   * outside of the permitted range.
+   */
+  MHD_SC_SOCKET_OUTSIDE_OF_FDSET_RANGE = 50036,
+
+  /**
+   * This daemon was not configured with options that
+   * would allow us to build an FD set for select().
+   */
+  MHD_SC_CONFIGURATION_MISSMATCH_FOR_GET_FDSET = 50037,
 
 };
 
@@ -1148,7 +1169,8 @@ typedef struct MHD_Action *
  */
 _MHD_EXTERN struct MHD_Daemon *
 MHD_daemon_create (MHD_RequestCallback cb,
-                   void *cb_cls);
+                   void *cb_cls)
+  MHD_NONNULL(1);
 
 
 /**
@@ -1160,7 +1182,8 @@ MHD_daemon_create (MHD_RequestCallback cb,
  * @ingroup event
  */
 _MHD_EXTERN enum MHD_StatusCode
-MHD_daemon_start (struct MHD_Daemon *daemon);
+MHD_daemon_start (struct MHD_Daemon *daemon)
+  MHD_NONNULL(1);
 
 
 /**
@@ -1184,7 +1207,8 @@ MHD_daemon_start (struct MHD_Daemon *daemon);
  * @ingroup specialized
  */
 _MHD_EXTERN MHD_socket
-MHD_daemon_quiesce (struct MHD_Daemon *daemon);
+MHD_daemon_quiesce (struct MHD_Daemon *daemon)
+  MHD_NONNULL(1);
 
 
 /**
@@ -1194,7 +1218,8 @@ MHD_daemon_quiesce (struct MHD_Daemon *daemon);
  * @ingroup event
  */
 _MHD_EXTERN void
-MHD_daemon_destroy (struct MHD_Daemon *daemon);
+MHD_daemon_destroy (struct MHD_Daemon *daemon)
+  MHD_NONNULL(1);
 
 
 /**
@@ -1226,7 +1251,8 @@ _MHD_EXTERN enum MHD_StatusCode
 MHD_daemon_add_connection (struct MHD_Daemon *daemon,
                            MHD_socket client_socket,
                            const struct sockaddr *addr,
-                           socklen_t addrlen);
+                           socklen_t addrlen)
+  MHD_NONNULL(1);
 
 
 /**
@@ -1258,7 +1284,8 @@ MHD_daemon_get_fdset (struct MHD_Daemon *daemon,
                       fd_set *read_fd_set,
                       fd_set *write_fd_set,
                       fd_set *except_fd_set,
-                      MHD_socket *max_fd);
+                      MHD_socket *max_fd)
+  MHD_NONNULL(1,2,3,4);
 
 
 /**
@@ -1294,7 +1321,8 @@ MHD_daemon_get_fdset2 (struct MHD_Daemon *daemon,
                        fd_set *write_fd_set,
                        fd_set *except_fd_set,
                        MHD_socket *max_fd,
-                       unsigned int fd_setsize);
+                       unsigned int fd_setsize)
+  MHD_NONNULL(1,2,3,4);
 
 
 /**
@@ -1344,7 +1372,8 @@ MHD_daemon_get_fdset2 (struct MHD_Daemon *daemon,
  */
 _MHD_EXTERN enum MHD_StatusCode
 MHD_daemon_get_timeout (struct MHD_Daemon *daemon,
-                        MHD_UNSIGNED_LONG_LONG *timeout);
+                        MHD_UNSIGNED_LONG_LONG *timeout)
+  MHD_NONNULL(1,2);
 
 
 /**
@@ -1366,7 +1395,8 @@ MHD_daemon_get_timeout (struct MHD_Daemon *daemon,
  * @ingroup event
  */
 _MHD_EXTERN enum MHD_StatusCode
-MHD_daemon_run (struct MHD_Daemon *daemon);
+MHD_daemon_run (struct MHD_Daemon *daemon)
+  MHD_NONNULL(1);
 
 
 /**
@@ -1395,9 +1425,8 @@ _MHD_EXTERN enum MHD_StatusCode
 MHD_daemon_run_from_select (struct MHD_Daemon *daemon,
                             const fd_set *read_fd_set,
                             const fd_set *write_fd_set,
-                            const fd_set *except_fd_set);
-
-
+                            const fd_set *except_fd_set)
+  MHD_NONNULL(1,2,3,4);
 
 
 /* ********************* daemon options ************** */
@@ -1431,7 +1460,8 @@ typedef void
 _MHD_EXTERN void
 MHD_daemon_set_logger (struct MHD_Daemon *daemon,
                        MHD_LoggingCallback logger,
-                       void *logger_cls);
+                       void *logger_cls)
+  MHD_NONNULL(1);
 
 
 /**
@@ -1448,7 +1478,8 @@ MHD_daemon_set_logger (struct MHD_Daemon *daemon,
  * @param daemon which instance to disable clock for.
  */
 _MHD_EXTERN void
-MHD_daemon_suppress_date_no_clock (struct MHD_Daemon *daemon);
+MHD_daemon_suppress_date_no_clock (struct MHD_Daemon *daemon)
+  MHD_NONNULL(1);
 
 
 /**
@@ -1469,7 +1500,8 @@ MHD_daemon_suppress_date_no_clock (struct MHD_Daemon *daemon);
  * @param daemon which instance to disable itc for
  */
 _MHD_EXTERN void
-MHD_daemon_disable_itc (struct MHD_Daemon *daemon);
+MHD_daemon_disable_itc (struct MHD_Daemon *daemon)
+  MHD_NONNULL(1);
 
 
 /**
@@ -1481,7 +1513,8 @@ MHD_daemon_disable_itc (struct MHD_Daemon *daemon);
  * @param daemon which instance to enable turbo for
  */
 _MHD_EXTERN void
-MHD_daemon_enable_turbo (struct MHD_Daemon *daemon);
+MHD_daemon_enable_turbo (struct MHD_Daemon *daemon)
+  MHD_NONNULL(1);
 
 
 /**
@@ -1494,7 +1527,8 @@ MHD_daemon_enable_turbo (struct MHD_Daemon *daemon);
  * @param daemon which instance to disable suspend for
  */
 _MHD_EXTERN void
-MHD_daemon_disallow_suspend_resume (struct MHD_Daemon *daemon);
+MHD_daemon_disallow_suspend_resume (struct MHD_Daemon *daemon)
+  MHD_NONNULL(1);
 
 
 /**
@@ -1509,7 +1543,8 @@ MHD_daemon_disallow_suspend_resume (struct MHD_Daemon *daemon);
  * @param daemon which instance to enable suspend/resume for
  */
 _MHD_EXTERN void
-MHD_daemon_disallow_upgrade (struct MHD_Daemon *daemon);
+MHD_daemon_disallow_upgrade (struct MHD_Daemon *daemon)
+  MHD_NONNULL(1);
 
 
 /**
@@ -1555,7 +1590,8 @@ enum MHD_FastOpenMethod
 _MHD_EXTERN enum MHD_Bool
 MHD_daemon_tcp_fastopen (struct MHD_Daemon *daemon,
                          enum MHD_FastOpenMethod fom,
-                         unsigned int queue_length);
+                         unsigned int queue_length)
+  MHD_NONNULL(1);
 
 
 /**
@@ -1608,7 +1644,8 @@ enum MHD_AddressFamily
 _MHD_EXTERN void
 MHD_daemon_bind_port (struct MHD_Daemon *daemon,
                       enum MHD_AddressFamily af,
-                      uint16_t port);
+                      uint16_t port)
+  MHD_NONNULL(1);
 
 
 /**
@@ -1623,7 +1660,8 @@ MHD_daemon_bind_port (struct MHD_Daemon *daemon,
 _MHD_EXTERN void
 MHD_daemon_bind_socket_address (struct MHD_Daemon *daemon,
                                 const struct sockaddr *sa,
-                                size_t sa_len);
+                                size_t sa_len)
+  MHD_NONNULL(1);
 
 
 /**
@@ -1635,7 +1673,8 @@ MHD_daemon_bind_socket_address (struct MHD_Daemon *daemon,
  */
 _MHD_EXTERN void
 MHD_daemon_listen_backlog (struct MHD_Daemon *daemon,
-                           int listen_backlog);
+                           int listen_backlog)
+  MHD_NONNULL(1);
 
 
 /**
@@ -1649,7 +1688,8 @@ MHD_daemon_listen_backlog (struct MHD_Daemon *daemon,
  * @param daemon daemon to configure address reuse for
  */
 _MHD_EXTERN void
-MHD_daemon_listen_allow_address_reuse (struct MHD_Daemon *daemon);
+MHD_daemon_listen_allow_address_reuse (struct MHD_Daemon *daemon)
+  MHD_NONNULL(1);
 
 
 /**
@@ -1668,7 +1708,8 @@ MHD_daemon_listen_allow_address_reuse (struct MHD_Daemon *daemon);
  */
 _MHD_EXTERN void
 MHD_daemon_listen_socket (struct MHD_Daemon *daemon,
-                          MHD_socket listen_socket);
+                          MHD_socket listen_socket)
+  MHD_NONNULL(1);
 
 
 /**
@@ -1708,7 +1749,8 @@ enum MHD_EventLoopSyscall
  */
 _MHD_EXTERN enum MHD_Bool
 MHD_daemon_event_loop (struct MHD_Daemon *daemon,
-                       enum MHD_EventLoopSyscall els);
+                       enum MHD_EventLoopSyscall els)
+  MHD_NONNULL(1);
 
 
 /**
@@ -1752,7 +1794,8 @@ enum MHD_ProtocolStrictLevel
  */
 _MHD_EXTERN void
 MHD_daemon_protocol_strict_level (struct MHD_Daemon *daemon,
-                                  enum MHD_ProtocolStrictLevel sl);
+                                  enum MHD_ProtocolStrictLevel sl)
+  MHD_NONNULL(1);
 
 
 /**
@@ -1762,7 +1805,8 @@ MHD_daemon_protocol_strict_level (struct MHD_Daemon *daemon,
  * @param daemon daemon to set SHOUTcast option for
  */
 _MHD_EXTERN void
-MHD_daemon_enable_shoutcast (struct MHD_Daemon *daemon);
+MHD_daemon_enable_shoutcast (struct MHD_Daemon *daemon)
+  MHD_NONNULL(1);
 
 
 /**
@@ -1783,7 +1827,8 @@ MHD_daemon_enable_shoutcast (struct MHD_Daemon *daemon);
 _MHD_EXTERN enum MHD_StatusCode
 MHD_daemon_set_tls_backend (struct MHD_Daemon *daemon,
                             const char *tls_backend,
-                            const char *ciphers);
+                            const char *ciphers)
+  MHD_NONNULL(1);
 
 
 /**
@@ -1802,7 +1847,8 @@ _MHD_EXTERN enum MHD_StatusCode
 MHD_daemon_tls_key_and_cert_from_memory (struct MHD_Daemon *daemon,
                                          const char *mem_key,
                                          const char *mem_cert,
-                                         const char *pass);
+                                         const char *pass)
+  MHD_NONNULL(1,2,3);
 
 
 /**
@@ -1815,7 +1861,8 @@ MHD_daemon_tls_key_and_cert_from_memory (struct MHD_Daemon *daemon,
  */
 _MHD_EXTERN enum MHD_StatusCode
 MHD_daemon_tls_mem_dhparams (struct MHD_Daemon *daemon,
-                             const char *dh);
+                             const char *dh)
+  MHD_NONNULL(1);
 
 
 /**
@@ -1828,7 +1875,8 @@ MHD_daemon_tls_mem_dhparams (struct MHD_Daemon *daemon,
  */
 _MHD_EXTERN enum MHD_StatusCode
 MHD_daemon_tls_mem_trust (struct MHD_Daemon *daemon,
-                          const char *mem_trust);
+                          const char *mem_trust)
+  MHD_NONNULL(1);
 
 
 /**
@@ -1840,7 +1888,8 @@ MHD_daemon_tls_mem_trust (struct MHD_Daemon *daemon,
  */
 _MHD_EXTERN enum MHD_StatusCode
 MHD_daemon_gnutls_credentials (struct MHD_Daemon *daemon,
-                               int gnutls_credentials);
+                               int gnutls_credentials)
+  MHD_NONNULL(1);
 
 
 /**
@@ -1862,7 +1911,8 @@ MHD_daemon_gnutls_credentials (struct MHD_Daemon *daemon,
  */
 _MHD_EXTERN enum MHD_StatusCode
 MHD_daemon_gnutls_key_and_cert_from_callback (struct MHD_Daemon *daemon,
-                                              void *cb);
+                                              void *cb)
+  MHD_NONNULL(1);
 
 
 /**
@@ -1920,7 +1970,8 @@ enum MHD_ThreadingModel
  */
 _MHD_EXTERN void
 MHD_daemon_threading_model (struct MHD_Daemon *daemon,
-                            enum MHD_ThreadingModel tm);
+                            enum MHD_ThreadingModel tm)
+  MHD_NONNULL(1);
 
 
 /**
@@ -1950,7 +2001,8 @@ typedef enum MHD_Bool
 _MHD_EXTERN void
 MHD_daemon_accept_policy (struct MHD_Daemon *daemon,
                           MHD_AcceptPolicyCallback apc,
-                          void *apc_cls);
+                          void *apc_cls)
+  MHD_NONNULL(1);
 
 
 /**
@@ -1981,7 +2033,8 @@ typedef void *
 _MHD_EXTERN void
 MHD_daemon_set_early_uri_logger (struct MHD_Daemon *daemon,
                                  MHD_EarlyUriLogCallback cb,
-                                 void *cb_cls);
+                                 void *cb_cls)
+  MHD_NONNULL(1);
 
 
 /**
@@ -2043,7 +2096,8 @@ typedef void
 _MHD_EXTERN void
 MHD_daemon_set_notify_connection (struct MHD_Daemon *daemon,
                                   MHD_NotifyConnectionCallback ncc,
-                                  void *ncc_cls);
+                                  void *ncc_cls)
+  MHD_NONNULL(1);
 
 
 /**
@@ -2060,7 +2114,8 @@ MHD_daemon_set_notify_connection (struct MHD_Daemon *daemon,
 _MHD_EXTERN void
 MHD_daemon_connection_memory_limit (struct MHD_Daemon *daemon,
                                     size_t memory_limit_b,
-                                    size_t memory_increment_b);
+                                    size_t memory_increment_b)
+  MHD_NONNULL(1);
 
 
 /**
@@ -2073,7 +2128,8 @@ MHD_daemon_connection_memory_limit (struct MHD_Daemon *daemon,
  */
 _MHD_EXTERN void
 MHD_daemon_thread_stack_size (struct MHD_Daemon *daemon,
-                              size_t stack_limit_b);
+                              size_t stack_limit_b)
+  MHD_NONNULL(1);
 
 
 /**
@@ -2094,7 +2150,8 @@ MHD_daemon_thread_stack_size (struct MHD_Daemon *daemon,
 _MHD_EXTERN void
 MHD_daemon_connection_limits (struct MHD_Daemon *daemon,
                               unsigned int global_connection_limit,
-                              unsigned int ip_connection_limit);
+                              unsigned int ip_connection_limit)
+  MHD_NONNULL(1);
 
 
 /**
@@ -2107,7 +2164,8 @@ MHD_daemon_connection_limits (struct MHD_Daemon *daemon,
  */
 _MHD_EXTERN void
 MHD_daemon_connection_default_timeout (struct MHD_Daemon *daemon,
-                                       unsigned int timeout_s);
+                                       unsigned int timeout_s)
+  MHD_NONNULL(1);
 
 
 /**
@@ -2142,7 +2200,8 @@ typedef size_t
 _MHD_EXTERN void
 MHD_daemon_unescape_cb (struct MHD_Daemon *daemon,
                         MHD_UnescapeCallback unescape_cb,
-                        void *unescape_cb_cls);
+                        void *unescape_cb_cls)
+  MHD_NONNULL(1);
 
 
 /**
@@ -2157,7 +2216,8 @@ MHD_daemon_unescape_cb (struct MHD_Daemon *daemon,
 _MHD_EXTERN void
 MHD_daemon_digest_auth_random (struct MHD_Daemon *daemon,
                                size_t buf_size,
-                               const void *buf);
+                               const void *buf)
+  MHD_NONNULL(1,3);
 
 
 /**
@@ -2169,7 +2229,8 @@ MHD_daemon_digest_auth_random (struct MHD_Daemon *daemon,
  */
 _MHD_EXTERN enum MHD_StatusCode
 MHD_daemon_digest_auth_nc_length (struct MHD_Daemon *daemon,
-                                  size_t nc_length);
+                                  size_t nc_length)
+  MHD_NONNULL(1);
 
 
 /* ********************* connection options ************** */
@@ -2185,7 +2246,8 @@ MHD_daemon_digest_auth_nc_length (struct MHD_Daemon *daemon,
  */
 _MHD_EXTERN void
 MHD_connection_set_timeout (struct MHD_Connection *connection,
-                            unsigned int timeout_s);
+                            unsigned int timeout_s)
+  MHD_NONNULL(1);
 
 
 /* **************** Request handling functions ***************** */
@@ -2268,7 +2330,8 @@ _MHD_EXTERN unsigned int
 MHD_request_get_values (struct MHD_Request *request,
                         enum MHD_ValueKind kind,
                         MHD_KeyValueIterator iterator,
-                        void *iterator_cls);
+                        void *iterator_cls)
+  MHD_NONNULL(1);
 
 
 /**
@@ -2300,7 +2363,8 @@ _MHD_EXTERN enum MHD_Bool
 MHD_request_set_value (struct MHD_Request *request,
                        enum MHD_ValueKind kind,
                        const char *key,
-                       const char *value);
+                       const char *value)
+  MHD_NONNULL(1,3,4);
 
 
 /**
@@ -2316,7 +2380,8 @@ MHD_request_set_value (struct MHD_Request *request,
 _MHD_EXTERN const char *
 MHD_request_lookup_value (struct MHD_Request *request,
                           enum MHD_ValueKind kind,
-                          const char *key);
+                          const char *key)
+  MHD_NONNULL(1);
 
 
 
@@ -2487,7 +2552,8 @@ MHD_action_suspend (void);
  * @param request the request to resume
  */
 _MHD_EXTERN void
-MHD_request_resume (struct MHD_Request *request);
+MHD_request_resume (struct MHD_Request *request)
+  MHD_NONNULL(1);
 
 
 /* **************** Response manipulation functions ***************** */
@@ -2520,7 +2586,8 @@ struct MHD_Response;
  */
 _MHD_EXTERN struct MHD_Action *
 MHD_action_from_response (struct MHD_Response *response,
-                          enum MHD_Bool destroy_after_use);
+                          enum MHD_Bool destroy_after_use)
+  MHD_NONNULL(1);
 
 
 /**
@@ -2531,7 +2598,8 @@ MHD_action_from_response (struct MHD_Response *response,
  * @param request the request for which we force HTTP 1.0 to be used
  */
 _MHD_EXTERN void
-MHD_response_option_v10_only (struct MHD_Response *response);
+MHD_response_option_v10_only (struct MHD_Response *response)
+  MHD_NONNULL(1);
 
 
 /**
@@ -2620,7 +2688,8 @@ typedef void
 _MHD_EXTERN void
 MHD_response_option_termination_callback (struct MHD_Response *response,
                                           MHD_RequestTerminationCallback termination_cb,
-                                          void *termination_cb_cls);
+                                          void *termination_cb_cls)
+  MHD_NONNULL(1);
 
 
 /**
@@ -2837,7 +2906,8 @@ struct MHD_UpgradeResponseHandle;
 _MHD_EXTERN enum MHD_Bool
 MHD_upgrade_operation (struct MHD_UpgradeResponseHandle *urh,
                        enum MHD_UpgradeOperation operation,
-                       ...);
+                       ...)
+  MHD_NONNULL(1);
 
 
 /**
@@ -2929,7 +2999,8 @@ typedef void
  */
 _MHD_EXTERN struct MHD_Response *
 MHD_response_for_upgrade (MHD_UpgradeHandler upgrade_handler,
-                          void *upgrade_handler_cls);
+                          void *upgrade_handler_cls)
+  MHD_NONNULL(1);
 
 
 /**
@@ -2942,7 +3013,8 @@ MHD_response_for_upgrade (MHD_UpgradeHandler upgrade_handler,
  * @ingroup response
  */
 _MHD_EXTERN void
-MHD_response_queue_for_destroy (struct MHD_Response *response);
+MHD_response_queue_for_destroy (struct MHD_Response *response)
+  MHD_NONNULL(1);
 
 
 /**
@@ -2958,7 +3030,8 @@ MHD_response_queue_for_destroy (struct MHD_Response *response);
 _MHD_EXTERN enum MHD_Bool
 MHD_response_add_header (struct MHD_Response *response,
                          const char *header,
-                         const char *content);
+                         const char *content)
+  MHD_NONNULL(1,2,3);
 
 
 /**
@@ -2974,7 +3047,8 @@ MHD_response_add_header (struct MHD_Response *response,
 _MHD_EXTERN enum MHD_Bool
 MHD_response_add_trailer (struct MHD_Response *response,
                           const char *footer,
-                          const char *content);
+                          const char *content)
+  MHD_NONNULL(1,2,3);
 
 
 /**
@@ -2989,7 +3063,8 @@ MHD_response_add_trailer (struct MHD_Response *response,
 _MHD_EXTERN enum MHD_Bool
 MHD_response_del_header (struct MHD_Response *response,
                          const char *header,
-                         const char *content);
+                         const char *content)
+  MHD_NONNULL(1,2,3);
 
 
 /**
@@ -3005,7 +3080,8 @@ MHD_response_del_header (struct MHD_Response *response,
 _MHD_EXTERN unsigned int
 MHD_response_get_headers (struct MHD_Response *response,
                           MHD_KeyValueIterator iterator,
-                          void *iterator_cls);
+                          void *iterator_cls)
+  MHD_NONNULL(1);
 
 
 /**
@@ -3018,7 +3094,8 @@ MHD_response_get_headers (struct MHD_Response *response,
  */
 _MHD_EXTERN const char *
 MHD_response_get_header (struct MHD_Response *response,
-                         const char *key);
+                         const char *key)
+  MHD_NONNULL(1,2);
 
 
 /* ************Upload and PostProcessor functions ********************** */
@@ -3067,7 +3144,8 @@ typedef struct MHD_Action *
  */
 _MHD_EXTERN struct MHD_Action *
 MHD_action_process_upload (MHD_UploadCallback uc,
-                           void *uc_cls);
+                           void *uc_cls)
+  MHD_NONNULL(1);
 
 
 /**
@@ -3132,7 +3210,8 @@ typedef struct MHD_Action *
 _MHD_EXTERN struct MHD_Action *
 MHD_action_parse_post (size_t buffer_size,
                        MHD_PostDataIterator iter,
-                       void *iter_cls);
+                       void *iter_cls)
+  MHD_NONNULL(2);
 
 
 
@@ -3303,7 +3382,8 @@ _MHD_EXTERN enum MHD_Bool
 MHD_connection_get_information_sz (struct MHD_Connection *connection,
                                    enum MHD_ConnectionInformationType info_type,
                                    union MHD_ConnectionInformation *return_value,
-                                   size_t return_value_size);
+                                   size_t return_value_size)
+  MHD_NONNULL(1,3);
 
 
 /**
@@ -3415,7 +3495,8 @@ _MHD_EXTERN enum MHD_Bool
 MHD_request_get_information_sz (struct MHD_Request *request,
                                 enum MHD_RequestInformationType info_type,
                                 union MHD_RequestInformation *return_value,
-                                size_t return_value_size);
+                                size_t return_value_size)
+  MHD_NONNULL(1,3);
 
 
 /**
@@ -3521,7 +3602,8 @@ _MHD_EXTERN enum MHD_Bool
 MHD_daemon_get_information_sz (struct MHD_Daemon *daemon,
                                enum MHD_DaemonInformationType info_type,
                                union MHD_DaemonInformation *return_value,
-                               size_t return_value_size);
+                               size_t return_value_size)
+  MHD_NONNULL(1,3);
 
 /**
  * Obtain information about the given daemon.
@@ -3588,7 +3670,8 @@ MHD_set_panic_func (MHD_PanicCallback cb,
  *  shorter afterwards due to elimination of escape sequences)
  */
 _MHD_EXTERN size_t
-MHD_http_unescape (char *val);
+MHD_http_unescape (char *val)
+  MHD_NONNULL(1);
 
 
 /**
diff --git a/src/lib/daemon_create.c b/src/lib/daemon_create.c
index ade51c1e..a2173d88 100644
--- a/src/lib/daemon_create.c
+++ b/src/lib/daemon_create.c
@@ -89,8 +89,6 @@ MHD_daemon_create (MHD_RequestCallback cb,
   struct MHD_Daemon *daemon;
 
   MHD_check_global_init_();
-  if (NULL == cb)
-    return NULL;
   if (NULL == (daemon = malloc (sizeof (struct MHD_Daemon))))
     return NULL;
   memset (daemon,
diff --git a/src/lib/daemon_destroy.c b/src/lib/daemon_destroy.c
index 1a8f7094..36f23d17 100644
--- a/src/lib/daemon_destroy.c
+++ b/src/lib/daemon_destroy.c
@@ -93,8 +93,6 @@ MHD_daemon_destroy (struct MHD_Daemon *daemon)
 {
   MHD_socket fd;
 
-  if (NULL == daemon)
-    return;
   daemon->shutdown = true;
   if (daemon->was_quiesced)
     fd = MHD_INVALID_SOCKET; /* Do not use FD if daemon was quiesced */
diff --git a/src/lib/daemon_get_fdset.c b/src/lib/daemon_get_fdset.c
index afbf3d6b..c3b0dbd9 100644
--- a/src/lib/daemon_get_fdset.c
+++ b/src/lib/daemon_get_fdset.c
@@ -62,7 +62,142 @@ MHD_daemon_get_fdset (struct MHD_Daemon *daemon,
                       fd_set *except_fd_set,
                       MHD_socket *max_fd)
 {
-  return -1;
+  return MHD_daemon_get_fdset2 (daemon,
+                                read_fd_set,
+                                write_fd_set,
+                                except_fd_set,
+                                max_fd,
+                                _MHD_SYS_DEFAULT_FD_SETSIZE);
+}
+
+
+/**
+ * Internal version of #MHD_daemon_get_fdset2().
+ *
+ * @param daemon daemon to get sets from
+ * @param read_fd_set read set
+ * @param write_fd_set write set
+ * @param except_fd_set except set
+ * @param max_fd increased to largest FD added (if larger
+ *               than existing value); can be NULL
+ * @param fd_setsize value of FD_SETSIZE
+ * @return #MHD_SC_OK on success
+ * @ingroup event
+ */
+static enum MHD_StatusCode
+internal_get_fdset2 (struct MHD_Daemon *daemon,
+                     fd_set *read_fd_set,
+                     fd_set *write_fd_set,
+                     fd_set *except_fd_set,
+                     MHD_socket *max_fd,
+                     unsigned int fd_setsize)
+
+{
+  struct MHD_Connection *pos;
+  struct MHD_Connection *posn;
+  int result = MHD_YES;
+  MHD_socket ls;
+
+  if (daemon->shutdown)
+    return MHD_NO;
+
+  ls = daemon->listen_socket;
+  if ( (MHD_INVALID_SOCKET != ls) &&
+       (! daemon->was_quiesced) &&
+       (! MHD_add_to_fd_set_ (ls,
+                              read_fd_set,
+                              max_fd,
+                              fd_setsize)) )
+    result = MHD_NO;
+
+  /* Add all sockets to 'except_fd_set' as well to watch for
+   * out-of-band data. However, ignore errors if INFO_READ
+   * or INFO_WRITE sockets will not fit 'except_fd_set'. */
+  /* Start from oldest connections. Make sense for W32 FDSETs. */
+  for (pos = daemon->connections_tail; NULL != pos; pos = posn)
+    {
+      posn = pos->prev;
+
+      switch (pos->request.event_loop_info)
+        {
+        case MHD_EVENT_LOOP_INFO_READ:
+          if (! MHD_add_to_fd_set_ (pos->socket_fd,
+                                    read_fd_set,
+                                    max_fd,
+                                    fd_setsize))
+            result = MHD_NO;
+#ifdef MHD_POSIX_SOCKETS
+          MHD_add_to_fd_set_ (pos->socket_fd,
+                              except_fd_set,
+                              max_fd,
+                              fd_setsize);
+#endif /* MHD_POSIX_SOCKETS */
+          break;
+        case MHD_EVENT_LOOP_INFO_WRITE:
+          if (! MHD_add_to_fd_set_ (pos->socket_fd,
+                                    write_fd_set,
+                                    max_fd,
+                                    fd_setsize))
+            result = MHD_NO;
+#ifdef MHD_POSIX_SOCKETS
+          MHD_add_to_fd_set_ (pos->socket_fd,
+                              except_fd_set,
+                              max_fd,
+                              fd_setsize);
+#endif /* MHD_POSIX_SOCKETS */
+          break;
+        case MHD_EVENT_LOOP_INFO_BLOCK:
+          if ( (NULL == except_fd_set) ||
+              ! MHD_add_to_fd_set_ (pos->socket_fd,
+                                    except_fd_set,
+                                    max_fd,
+                                    fd_setsize))
+            result = MHD_NO;
+          break;
+        case MHD_EVENT_LOOP_INFO_CLEANUP:
+          /* this should never happen */
+          break;
+        }
+    }
+#ifdef MHD_WINSOCK_SOCKETS
+  /* W32 use limited array for fd_set so add INFO_READ/INFO_WRITE sockets
+   * only after INFO_BLOCK sockets to ensure that INFO_BLOCK sockets will
+   * not be pushed out. */
+  for (pos = daemon->connections_tail; NULL != pos; pos = posn)
+    {
+      posn = pos->prev;
+      MHD_add_to_fd_set_ (pos->socket_fd,
+                          except_fd_set,
+                          max_fd,
+                          fd_setsize);
+    }
+#endif /* MHD_WINSOCK_SOCKETS */
+#if defined(HTTPS_SUPPORT) && defined(UPGRADE_SUPPORT)
+  {
+    struct MHD_UpgradeResponseHandle *urh;
+
+    for (urh = daemon->urh_tail; NULL != urh; urh = urh->prev)
+      {
+        if (MHD_NO ==
+            urh_to_fdset (urh,
+                          read_fd_set,
+                          write_fd_set,
+                          except_fd_set,
+                          max_fd,
+                          fd_setsize))
+          result = MHD_NO;
+      }
+  }
+#endif
+#if DEBUG_CONNECT
+#ifdef HAVE_MESSAGES
+  if (NULL != max_fd)
+    MHD_DLOG (daemon,
+              _("Maximum socket in select set: %d\n"),
+              *max_fd);
+#endif
+#endif /* HTTPS_SUPPORT && UPGRADE_SUPPORT */
+  return result;
 }
 
 
@@ -101,7 +236,34 @@ MHD_daemon_get_fdset2 (struct MHD_Daemon *daemon,
                        MHD_socket *max_fd,
                        unsigned int fd_setsize)
 {
-  return -1;
+  if ( (MHD_TM_EXTERNAL_EVENT_LOOP != daemon->threading_model) ||
+       (MHD_ELS_POLL == daemon->event_loop_syscall) ) 
+    return MHD_SC_CONFIGURATION_MISSMATCH_FOR_GET_FDSET;
+
+#ifdef EPOLL_SUPPORT
+  if (MHD_ELS_EPOLL == daemon->event_loop_syscall)
+    {
+      if (daemon->shutdown)
+        return MHD_SC_DAEMON_ALREADY_SHUTDOWN;
+
+      /* we're in epoll mode, use the epoll FD as a stand-in for
+         the entire event set */
+
+      return MHD_add_to_fd_set_ (daemon->epoll_fd,
+                                 read_fd_set,
+                                 max_fd,
+                                 fd_setsize)
+        ? MHD_SC_OK
+        : MHD_SC_SOCKET_OUTSIDE_OF_FDSET_RANGE;
+    }
+#endif
+
+  return internal_get_fdset2 (daemon,
+                              read_fd_set,
+                              write_fd_set,
+                              except_fd_set,
+                              max_fd,
+                              fd_setsize);
 }
 
 /* end of daemon_get_fdset.c */
diff --git a/src/lib/internal.h b/src/lib/internal.h
index 5b147df8..17e5c634 100644
--- a/src/lib/internal.h
+++ b/src/lib/internal.h
@@ -826,6 +826,202 @@ struct MHD_Connection
 };
 
 
+#ifdef UPGRADE_SUPPORT
+/**
+ * Buffer we use for upgrade response handling in the unlikely
+ * case where the memory pool was so small it had no buffer
+ * capacity left.  Note that we don't expect to _ever_ use this
+ * buffer, so it's mostly wasted memory (except that it allows
+ * us to handle a tricky error condition nicely). So no need to
+ * make this one big.  Applications that want to perform well
+ * should just pick an adequate size for the memory pools.
+ */
+#define RESERVE_EBUF_SIZE 8
+
+/**
+ * Context we pass to epoll() for each of the two sockets
+ * of a `struct MHD_UpgradeResponseHandle`.  We need to do
+ * this so we can distinguish the two sockets when epoll()
+ * gives us event notifications.
+ */
+struct UpgradeEpollHandle
+{
+  /**
+   * Reference to the overall response handle this struct is
+   * included within.
+   */
+  struct MHD_UpgradeResponseHandle *urh;
+
+  /**
+   * The socket this event is kind-of about.  Note that this is NOT
+   * necessarily the socket we are polling on, as for when we read
+   * from TLS, we epoll() on the connection's socket
+   * (`urh->connection->socket_fd`), while this then the application's
+   * socket (where the application will read from).  Nevertheless, for
+   * the application to read, we need to first read from TLS, hence
+   * the two are related.
+   *
+   * Similarly, for writing to TLS, this epoll() will be on the
+   * connection's `socket_fd`, and this will merely be the FD which
+   * the applicatio would write to.  Hence this struct must always be
+   * interpreted based on which field in `struct
+   * MHD_UpgradeResponseHandle` it is (`app` or `mhd`).
+   */
+  MHD_socket socket;
+
+  /**
+   * IO-state of the @e socket (or the connection's `socket_fd`).
+   */
+  enum MHD_EpollState celi;
+
+};
+
+
+/**
+ * Handle given to the application to manage special
+ * actions relating to MHD responses that "upgrade"
+ * the HTTP protocol (i.e. to WebSockets).
+ */
+struct MHD_UpgradeResponseHandle
+{
+  /**
+   * The connection for which this is an upgrade handle.  Note that
+   * because a response may be shared over many connections, this may
+   * not be the only upgrade handle for the response of this connection.
+   */
+  struct MHD_Connection *connection;
+
+#ifdef HTTPS_SUPPORT
+  /**
+   * Kept in a DLL per daemon.
+   */
+  struct MHD_UpgradeResponseHandle *next;
+
+  /**
+   * Kept in a DLL per daemon.
+   */
+  struct MHD_UpgradeResponseHandle *prev;
+
+#ifdef EPOLL_SUPPORT
+  /**
+   * Next pointer for the EDLL listing urhs that are epoll-ready.
+   */
+  struct MHD_UpgradeResponseHandle *nextE;
+
+  /**
+   * Previous pointer for the EDLL listing urhs that are epoll-ready.
+   */
+  struct MHD_UpgradeResponseHandle *prevE;
+
+  /**
+   * Specifies whether urh already in EDLL list of ready connections.
+   */
+  bool in_eready_list;
+#endif
+
+  /**
+   * The buffer for receiving data from TLS to
+   * be passed to the application.  Contains @e in_buffer_size
+   * bytes (unless @e in_buffer_size is zero). Do not free!
+   */
+  char *in_buffer;
+
+  /**
+   * The buffer for receiving data from the application to
+   * be passed to TLS.  Contains @e out_buffer_size
+   * bytes (unless @e out_buffer_size is zero). Do not free!
+   */
+  char *out_buffer;
+
+  /**
+   * Size of the @e in_buffer.
+   * Set to 0 if the TLS connection went down for reading or socketpair
+   * went down for writing.
+   */
+  size_t in_buffer_size;
+
+  /**
+   * Size of the @e out_buffer.
+   * Set to 0 if the TLS connection went down for writing or socketpair
+   * went down for reading.
+   */
+  size_t out_buffer_size;
+
+  /**
+   * Number of bytes actually in use in the @e in_buffer.  Can be larger
+   * than @e in_buffer_size if and only if @a in_buffer_size is zero and
+   * we still have bytes that can be forwarded.
+   * Reset to zero if all data was forwarded to socketpair or
+   * if socketpair went down for writing.
+   */
+  size_t in_buffer_used;
+
+  /**
+   * Number of bytes actually in use in the @e out_buffer. Can be larger
+   * than @e out_buffer_size if and only if @a out_buffer_size is zero and
+   * we still have bytes that can be forwarded.
+   * Reset to zero if all data was forwarded to TLS connection or
+   * if TLS connection went down for writing.
+   */
+  size_t out_buffer_used;
+
+  /**
+   * The socket we gave to the application (r/w).
+   */
+  struct UpgradeEpollHandle app;
+
+  /**
+   * If @a app_sock was a socketpair, our end of it, otherwise
+   * #MHD_INVALID_SOCKET; (r/w).
+   */
+  struct UpgradeEpollHandle mhd;
+
+  /**
+   * Emergency IO buffer we use in case the memory pool has literally
+   * nothing left.
+   */
+  char e_buf[RESERVE_EBUF_SIZE];
+
+#endif /* HTTPS_SUPPORT */
+
+  /**
+   * Set to true after the application finished with the socket
+   * by #MHD_UPGRADE_ACTION_CLOSE.
+   *
+   * When BOTH @e was_closed (changed by command from application)
+   * AND @e clean_ready (changed internally by MHD) are set to
+   * #MHD_YES, function #MHD_resume_connection() will move this
+   * connection to cleanup list.
+   * @remark This flag could be changed from any thread.
+   */
+  volatile bool was_closed;
+
+  /**
+   * Set to true if connection is ready for cleanup.
+   *
+   * In TLS mode functions #MHD_connection_finish_forward_() must
+   * be called before setting this flag to true.
+   *
+   * In thread-per-connection mode, true in this flag means
+   * that connection's thread exited or about to exit and will
+   * not use MHD_Connection::urh data anymore.
+   *
+   * In any mode true in this flag also means that
+   * MHD_Connection::urh data will not be used for socketpair
+   * forwarding and forwarding itself is finished.
+   *
+   * When BOTH @e was_closed (changed by command from application)
+   * AND @e clean_ready (changed internally by MHD) are set to
+   * true, function #MHD_resume_connection() will move this
+   * connection to cleanup list.
+   * @remark This flag could be changed from thread that process
+   * connection's recv(), send() and response.
+   */
+  bool clean_ready;
+};
+#endif /* UPGRADE_SUPPORT */
+
+
 /**
  * State kept for each MHD daemon.  All connections are kept in two
  * doubly-linked lists.  The first one reflects the state of the
@@ -910,6 +1106,22 @@ struct MHD_Daemon
 
   
 #if HTTPS_SUPPORT
+#ifdef UPGRADE_SUPPORT
+  /**
+   * Head of DLL of upgrade response handles we are processing.
+   * Used for upgraded TLS connections when thread-per-connection
+   * is not used.
+   */
+  struct MHD_UpgradeResponseHandle *urh_head;
+
+  /**
+   * Tail of DLL of upgrade response handles we are processing.
+   * Used for upgraded TLS connections when thread-per-connection
+   * is not used.
+   */
+  struct MHD_UpgradeResponseHandle *urh_tail;
+#endif /* UPGRADE_SUPPORT */
+
   /**
    * Which TLS backend should be used. NULL for no TLS.
    * This is merely the handle to the dlsym() object, not
@@ -1012,13 +1224,10 @@ struct MHD_Daemon
    */
   struct MHD_Connection *eready_tail;
 
-#ifdef EPOLL_SUPPORT
   /**
    * Pointer to marker used to indicate ITC slot in epoll sets.
    */
   const char *epoll_itc_marker;
-#endif
-  
 #ifdef UPGRADE_SUPPORT
   /**
    * Head of EDLL of upgraded connections ready for processing (in epoll mode).
diff --git a/src/lib/request.c b/src/lib/request.c
index b834ba9d..6264111e 100644
--- a/src/lib/request.c
+++ b/src/lib/request.c
@@ -47,8 +47,6 @@ MHD_request_get_values (struct MHD_Request *request,
   int ret;
   struct MHD_HTTP_Header *pos;
 
-  if (NULL == request)
-    return -1;
   ret = 0;
   for (pos = request->headers_received;
        NULL != pos;
@@ -143,8 +141,6 @@ MHD_request_lookup_value (struct MHD_Request *request,
 {
   struct MHD_HTTP_Header *pos;
 
-  if (NULL == request)
-    return NULL;
   for (pos = request->headers_received;
        NULL != pos;
        pos = pos->next)
diff --git a/src/lib/response.c b/src/lib/response.c
index 2a9a2604..ff23c7fd 100644
--- a/src/lib/response.c
+++ b/src/lib/response.c
@@ -172,9 +172,6 @@ MHD_response_del_header (struct MHD_Response *response,
   struct MHD_HTTP_Header *pos;
   struct MHD_HTTP_Header *prev;
 
-  if ( (NULL == header) ||
-       (NULL == content) )
-    return MHD_NO;
   prev = NULL;
   pos = response->first_header;
   while (NULL != pos)
@@ -248,8 +245,6 @@ MHD_response_get_header (struct MHD_Response *response,
 {
   struct MHD_HTTP_Header *pos;
 
-  if (NULL == key)
-    return NULL;
   for (pos = response->first_header;
        NULL != pos;
        pos = pos->next)