Merge pull request #332 from dragos-oancea/sofia-tport-null-ptr

[sofia-sip] scan-build: Access to field 'ai_addr' results in a dereference of a null pointer (loaded from variable 'res')

libs/sofia-sip/libsofia-sip-ua/tport/tport.c

@@ -1661,6 +1661,8 @@ int tport_bind_server(tport_master_t *mr,
   for (tbf = &mr->mr_primaries; *tbf; tbf = &(*tbf)->pri_next)
     ;
 
+  if (!res)
+    return -1;
   port = port0 = port1 = ntohs(((su_sockaddr_t *)res->ai_addr)->su_port);
   error = EPROTONOSUPPORT;