3 files changed, 24 insertions, 3 deletions

diff --git a/src/include/microhttpd.h b/src/include/microhttpd.h
index 05b86b74..50c7b3af 100644
--- a/src/include/microhttpd.h
+++ b/src/include/microhttpd.h
@@ -130,7 +130,7 @@ typedef intptr_t ssize_t;
  * Current version of the library.
  * 0x01093001 = 1.9.30-1.
  */
-#define MHD_VERSION 0x00094701
+#define MHD_VERSION 0x00094703
 
 /**
  * MHD-internal return code for "YES".
@@ -967,8 +967,15 @@ enum MHD_OPTION
    * pointer to a closure to pass to the request completed callback.
    * The second pointer maybe NULL.
    */
-  MHD_OPTION_NOTIFY_CONNECTION = 27
+  MHD_OPTION_NOTIFY_CONNECTION = 27,
 
+  /**
+   * Allow to change maximum length of the queue of pending connections on
+   * listen socket. If not present than default platform-specific SOMAXCONN
+   * value is used. This option should be followed by an `unsigned int`
+   * argument.
+   */
+  MHD_OPTION_LISTEN_BACKLOG_SIZE = 28
 };
 
 
diff --git a/src/microhttpd/daemon.c b/src/microhttpd/daemon.c
index 209f8e5d..29daaad7 100644
--- a/src/microhttpd/daemon.c
+++ b/src/microhttpd/daemon.c
@@ -3397,6 +3397,9 @@ parse_options_va (struct MHD_Daemon *daemon,
         case MHD_OPTION_LISTENING_ADDRESS_REUSE:
           daemon->listening_address_reuse = va_arg (ap, unsigned int) ? 1 : -1;
           break;
+        case MHD_OPTION_LISTEN_BACKLOG_SIZE:
+          daemon->listen_backlog_size = va_arg (ap, unsigned int);
+          break;
         case MHD_OPTION_ARRAY:
           oa = va_arg (ap, struct MHD_OptionItem*);
           i = 0;
@@ -3423,6 +3426,7 @@ parse_options_va (struct MHD_Daemon *daemon,
                 case MHD_OPTION_THREAD_POOL_SIZE:
                 case MHD_OPTION_TCP_FASTOPEN_QUEUE_SIZE:
                 case MHD_OPTION_LISTENING_ADDRESS_REUSE:
+                case MHD_OPTION_LISTEN_BACKLOG_SIZE:
                   if (MHD_YES != parse_options (daemon,
                                                 servaddr,
                                                 opt,
@@ -3731,6 +3735,11 @@ MHD_start_daemon_va (unsigned int flags,
   daemon->connection_timeout = 0;       /* no timeout */
   daemon->wpipe[0] = MHD_INVALID_PIPE_;
   daemon->wpipe[1] = MHD_INVALID_PIPE_;
+#ifdef SOMAXCONN
+  daemon->listen_backlog_size = SOMAXCONN;
+#else  /* !SOMAXCONN */
+  daemon->listen_backlog_size = 511; /* should be safe value */
+#endif /* !SOMAXCONN */
 #if HAVE_MESSAGES
   daemon->custom_error_log = (MHD_LogCallback) &vfprintf;
   daemon->custom_error_log_cls = stderr;
@@ -4098,7 +4107,7 @@ MHD_start_daemon_va (unsigned int flags,
             }
         }
 #endif
-      if (listen (socket_fd, 32) < 0)
+      if (listen (socket_fd, daemon->listen_backlog_size) < 0)
         {
 #if HAVE_MESSAGES
           MHD_DLOG (daemon,
diff --git a/src/microhttpd/internal.h b/src/microhttpd/internal.h
index 3760fefb..9e1a2901 100644
--- a/src/microhttpd/internal.h
+++ b/src/microhttpd/internal.h
@@ -1301,6 +1301,11 @@ struct MHD_Daemon
    */
   unsigned int fastopen_queue_size;
 #endif
+
+  /**
+   * The size of queue for listen socket.
+   */
+  unsigned int listen_backlog_size;
 };