Add ssl_set_client_transport_id()

library/ssl_tls.c

diff --git a/library/ssl_tls.c b/library/ssl_tls.c
index 27ee058..d854199 100644
--- a/library/ssl_tls.c
+++ b/library/ssl_tls.c
@@ -3749,6 +3749,12 @@
     ssl->alpn_chosen = NULL;
 #endif
 
+#if defined(POLARSSL_SSL_PROTO_DTLS) && defined(POLARSSL_SSL_SRV_C)
+    polarssl_free( ssl->cli_id );
+    ssl->cli_id = NULL;
+    ssl->cli_id_len = 0;
+#endif
+
     if( ( ret = ssl_handshake_init( ssl ) ) != 0 )
         return( ret );
 
@@ -5033,6 +5039,10 @@
     }
 #endif
 
+#if defined(POLARSSL_SSL_PROTO_DTLS) && defined(POLARSSL_SSL_SRV_C)
+    polarssl_free( ssl->cli_id );
+#endif
+
     SSL_DEBUG_MSG( 2, ( "<= free" ) );
 
     /* Actually clear after last debug message */