commit fc572dd4f6958e01eb50a1fa094ed860802f0ddf
author Manuel Pégourié-Gonnard <mpg@elzevir.fr> Thu Oct 09 17:56:57 2014 +0200
committer Paul Bakker <p.j.bakker@polarssl.org> Tue Oct 21 16:32:51 2014 +0200
tree 41913bc616dde437a3fe27c21feb58cb008aeefc
parent 8a7cf2543ac9c06787cb191cdfb20d54e1e49ea3

Retransmit only on last message from prev flight

Be a good network citizen, try to avoid causing congestion by causing a
retransmission explosion.

library/ssl_tls.c

diff --git a/library/ssl_tls.c b/library/ssl_tls.c
index de85b67..e72aa3e 100644
--- a/library/ssl_tls.c
+++ b/library/ssl_tls.c
@@ -2753,8 +2753,10 @@
         if( ssl->handshake != NULL &&
             recv_msg_seq != ssl->handshake->in_msg_seq )
         {
-            /* No sane server ever retransmits HelloVerifyRequest */
-            if( recv_msg_seq < ssl->handshake->in_flight_start_seq &&
+            /* Retransmit only on last message from previous flight, to avoid
+             * too many retransmissions.
+             * Besides, No sane server ever retransmits HelloVerifyRequest */
+            if( recv_msg_seq == ssl->handshake->in_flight_start_seq - 1 &&
                 ssl->in_msg[0] != SSL_HS_HELLO_VERIFY_REQUEST )
             {
                 SSL_DEBUG_MSG( 2, ( "received message from last flight, "