Move MTU setting to SSL context, not config
This setting belongs to the individual connection, not to a configuration
shared by many connections. (If a default value is desired, that can be handled
by the application code that calls mbedtls_ssl_set_mtu().)
There are at least two ways in which this matters:
- per-connection settings can be adjusted if MTU estimates become available
during the lifetime of the connection
- it is at least conceivable that a server might recognize restricted clients
based on range of IPs and immediately set a lower MTU for them. This is much
easier to do with a per-connection setting than by maintaining multiple
near-duplicated ssl_config objects that differ only by the MTU setting.
diff --git a/programs/ssl/ssl_server2.c b/programs/ssl/ssl_server2.c
index 484f84f..71ec85b 100644
--- a/programs/ssl/ssl_server2.c
+++ b/programs/ssl/ssl_server2.c
@@ -2165,9 +2165,6 @@
#if defined(MBEDTLS_SSL_PROTO_DTLS)
if( opt.hs_to_min != DFL_HS_TO_MIN || opt.hs_to_max != DFL_HS_TO_MAX )
mbedtls_ssl_conf_handshake_timeout( &conf, opt.hs_to_min, opt.hs_to_max );
-
- if( opt.dtls_mtu != DFL_DTLS_MTU )
- mbedtls_ssl_conf_mtu( &conf, opt.dtls_mtu );
#endif /* MBEDTLS_SSL_PROTO_DTLS */
#if defined(MBEDTLS_SSL_MAX_FRAGMENT_LENGTH)
@@ -2486,6 +2483,11 @@
mbedtls_ssl_set_bio( &ssl, &client_fd, mbedtls_net_send, mbedtls_net_recv,
opt.nbio == 0 ? mbedtls_net_recv_timeout : NULL );
+#if defined(MBEDTLS_SSL_PROTO_DTLS)
+ if( opt.dtls_mtu != DFL_DTLS_MTU )
+ mbedtls_ssl_set_mtu( &ssl, opt.dtls_mtu );
+#endif
+
#if defined(MBEDTLS_TIMING_C)
mbedtls_ssl_set_timer_cb( &ssl, &timer, mbedtls_timing_set_delay,
mbedtls_timing_get_delay );