PR: 2755

Submitted by: Robin Seggelmann <seggelmann@fh-muenster.de>

Reduce MTU after failed transmissions.

diff --git a/crypto/bio/bio.h b/crypto/bio/bio.h
index b440bdd6dda3a1a965fbc39cc5ec8a397aee956c..05699ab21210edc4831cf7378a3fe6734edcdba8 100644 (file)
--- a/crypto/bio/bio.h
+++ b/crypto/bio/bio.h
@@ -157,6 +157,7 @@ extern "C" {
 /* #endif */
 
 #define BIO_CTRL_DGRAM_QUERY_MTU          40 /* as kernel for current MTU */
+#define BIO_CTRL_DGRAM_GET_FALLBACK_MTU   47
 #define BIO_CTRL_DGRAM_GET_MTU            41 /* get cached value for MTU */
 #define BIO_CTRL_DGRAM_SET_MTU            42 /* set cached value for
                                              * MTU. want to use this

diff --git a/crypto/bio/bss_dgram.c b/crypto/bio/bss_dgram.c
index 4d1a64ea358e3869c938f05d9a468180408c73b2..1b1e4bec8121fe58102bb4da5f7f275a494239a9 100644 (file)
--- a/crypto/bio/bss_dgram.c
+++ b/crypto/bio/bss_dgram.c
@@ -616,6 +616,27 @@ static long dgram_ctrl(BIO *b, int cmd, long num, void *ptr)
                ret = 0;
 #endif
                break;
+       case BIO_CTRL_DGRAM_GET_FALLBACK_MTU:
+               switch (data->peer.sa.sa_family)
+                       {
+                       case AF_INET:
+                               ret = 576 - 20 - 8;
+                               break;
+#if OPENSSL_USE_IPV6
+                       case AF_INET6:
+#ifdef IN6_IS_ADDR_V4MAPPED
+                               if (IN6_IS_ADDR_V4MAPPED(&data->peer.sa_in6.sin6_addr))
+                                       ret = 576 - 20 - 8;
+                               else
+#endif
+                                       ret = 1280 - 40 - 8;
+                               break;
+#endif
+                       default:
+                               ret = 576 - 20 - 8;
+                               break;
+                       }
+               break;
        case BIO_CTRL_DGRAM_GET_MTU:
                return data->mtu;
                break;

diff --git a/ssl/d1_both.c b/ssl/d1_both.c
index 5c47c7c19639022ee82277a9a440c275cef90c45..373285885c7cdd73e404086d79a37381091ba8bc 100644 (file)
--- a/ssl/d1_both.c
+++ b/ssl/d1_both.c
@@ -227,14 +227,14 @@ int dtls1_do_write(SSL *s, int type)
        unsigned int len, frag_off, mac_size, blocksize;
 
        /* AHA!  Figure out the MTU, and stick to the right size */
-       if ( ! (SSL_get_options(s) & SSL_OP_NO_QUERY_MTU))
+       if (s->d1->mtu < dtls1_min_mtu() && !(SSL_get_options(s) & SSL_OP_NO_QUERY_MTU))
                {
                s->d1->mtu = 
                        BIO_ctrl(SSL_get_wbio(s), BIO_CTRL_DGRAM_QUERY_MTU, 0, NULL);
 
                /* I've seen the kernel return bogus numbers when it doesn't know
                 * (initial write), so just make sure we have a reasonable number */
-               if ( s->d1->mtu < dtls1_min_mtu())
+               if (s->d1->mtu < dtls1_min_mtu())
                        {
                        s->d1->mtu = 0;
                        s->d1->mtu = dtls1_guess_mtu(s->d1->mtu);

diff --git a/ssl/d1_lib.c b/ssl/d1_lib.c
index e205b5c6e54533cc07a112915e73ec424251185e..f4bfd29afd5b18892a2852fba362d24d339f2ebc 100644 (file)
--- a/ssl/d1_lib.c
+++ b/ssl/d1_lib.c
@@ -424,6 +424,11 @@ int dtls1_handle_timeout(SSL *s)
                state->timeout.read_timeouts = 1;
                }
 
+       if (state->timeout_duration > 2)
+               {
+               s->d1->mtu = BIO_ctrl(SSL_get_wbio(s), BIO_CTRL_DGRAM_GET_FALLBACK_MTU, 0, NULL);               
+               }
+
 #ifndef OPENSSL_NO_HEARTBEATS
        if (s->tlsext_hb_pending)
                {