Speed-up TLS handshake

src/microhttpd/connection_https.c

@@ -33,6 +33,7 @@
 #include "response.h"
 #include "mhd_mono_clock.h"
 #include <gnutls/gnutls.h>
+#include "mhd_send.h"
 
 
 /**
@@ -107,6 +108,15 @@ MHD_run_tls_handshake_ (struct MHD_Connection *connection)
   if ((MHD_TLS_CONN_INIT == connection->tls_state) ||
       (MHD_TLS_CONN_HANDSHAKING == connection->tls_state))
   {
+    /* GnuTLS uses sendmsg() (when available) to combine outgoing message
+     * into the single packet therefore there is no need to wait for
+     * additional data after sendmsg(). TLS handshake requires several packets
+     * exchange so set TCP_NODELAY here to avoid delay after each outgoing
+     * packet. As drawback it results in less more packet fragmentation
+     * on platforms without sendmsg() support, but luckily such platforms
+     * are now rare and they don't provide best performance anyway. */
+    if (_MHD_ON != connection->sk_nodelay)
+      MHD_connection_set_nodelay_state_ (connection, true);
     ret = gnutls_handshake (connection->tls_session);
     if (ret == GNUTLS_E_SUCCESS)
     {