Only use the fallback mtu after 2 unsuccessful retransmissions if it is less

than the mtu we are already using

Reviewed-by: Tim Hudson <tjh@openssl.org>
(cherry picked from commit 047f21593eebbc617a410a208ded01e65ca11028)

diff --git a/ssl/d1_lib.c b/ssl/d1_lib.c
index 31208b7d7a0bca925ede97f48f9a836833f18a54..0a4d790dd671ba25ae695ba969878bd07e6e37fd 100644 (file)
--- a/ssl/d1_lib.c
+++ b/ssl/d1_lib.c
@@ -475,13 +475,17 @@ void dtls1_stop_timer(SSL *s)
 
 int dtls1_check_timeout_num(SSL *s)
        {
+       unsigned int mtu;
+
        s->d1->timeout.num_alerts++;
 
        /* Reduce MTU after 2 unsuccessful retransmissions */
        if (s->d1->timeout.num_alerts > 2
                        && !(SSL_get_options(s) & SSL_OP_NO_QUERY_MTU))
                {
-               s->d1->mtu = BIO_ctrl(SSL_get_wbio(s), BIO_CTRL_DGRAM_GET_FALLBACK_MTU, 0, NULL);               
+               mtu = BIO_ctrl(SSL_get_wbio(s), BIO_CTRL_DGRAM_GET_FALLBACK_MTU, 0, NULL);
+               if(mtu < s->d1->mtu)
+                       s->d1->mtu = mtu;
                }
 
        if (s->d1->timeout.num_alerts > DTLS1_TMO_ALERT_COUNT)