Add test for session resumption

library/ssl_tls.c

@@ -2861,10 +2861,7 @@ int mbedtls_ssl_flight_transmit( mbedtls_ssl_context *ssl )
 
     if( ssl->handshake->retransmit_state != MBEDTLS_SSL_RETRANS_SENDING )
     {
-        MBEDTLS_SSL_DEBUG_MSG( 2, ( "initialise fligh transmission" ) );
+        MBEDTLS_SSL_DEBUG_MSG( 2, ( "initialise flight transmission" ) );
-
-        MBEDTLS_SSL_DEBUG_MSG( 2, ( "max handshake fragment length: %u",
-                                    max_hs_fragment_len ) );
 
         ssl->handshake->cur_msg = ssl->handshake->flight;
         ssl->handshake->cur_msg_p = ssl->handshake->flight->p + 12;
@@ -2906,7 +2903,11 @@ int mbedtls_ssl_flight_transmit( mbedtls_ssl_context *ssl )
                                   ? max_hs_fragment_len : rem_len;
 
             if( frag_off == 0 && frag_len != hs_len )
-                MBEDTLS_SSL_DEBUG_MSG( 2, ( "fragmenting handshake message" ) );
+            {
+                MBEDTLS_SSL_DEBUG_MSG( 2, ( "fragmenting handshake message (%u > %u)",
+                                            (unsigned) hs_len,
+                                            (unsigned) max_hs_fragment_len ) );
+            }
 
             /* Messages are stored with handshake headers as if not fragmented,
              * copy beginning of headers then fill fragmentation fields.

tests/ssl-opt.sh

@@ -5068,6 +5068,32 @@ run_test    "DTLS fragmenting: proxy MTU, simple handshake" \
             -c "found fragmented DTLS handshake message" \
             -C "error"
 
+# This ensures things still work after session_reset(),
+# for example it would have caught #1941.
+# It also exercises the "resumed hanshake" flow.
+# Since we don't support reading fragmented ClientHello yet,
+# up the MTU to 1450 (larger than ClientHello with session ticket,
+# but still smaller than client's Certificate to ensure fragmentation).
+requires_config_enabled MBEDTLS_SSL_PROTO_DTLS
+requires_config_enabled MBEDTLS_RSA_C
+requires_config_enabled MBEDTLS_ECDSA_C
+run_test    "DTLS fragmenting: proxy MTU, resumed handshake" \
+            -p "$P_PXY mtu=1450" \
+            "$P_SRV dtls=1 debug_level=2 auth_mode=required \
+             crt_file=data_files/server7_int-ca.crt \
+             key_file=data_files/server7.key \
+             mtu=1450" \
+            "$P_CLI dtls=1 debug_level=2 \
+             crt_file=data_files/server8_int-ca2.crt \
+             key_file=data_files/server8.key \
+             mtu=1450 reconnect=1" \
+            0 \
+            -S "resend" \
+            -C "resend" \
+            -s "found fragmented DTLS handshake message" \
+            -c "found fragmented DTLS handshake message" \
+            -C "error"
+
 requires_config_enabled MBEDTLS_SSL_PROTO_DTLS
 requires_config_enabled MBEDTLS_RSA_C
 requires_config_enabled MBEDTLS_ECDSA_C