[490] Fix auth plugin+WS client+MOSQ_ERR_AUTH related crash.

Thanks to "hasunperera".

Bug: https://github.com/eclipse/mosquitto/issues/490

ChangeLog.txt

@@ -4,6 +4,8 @@ Broker:
 - Fix memory leak if a client provided a username/password for a listener with
   use_identity_as_username configured.
 - Fix use_identity_as_username not working on websockets clients.
+- Don't crash if an auth plugin returns MOSQ_ERR_AUTH for a username check on
+  a websockets client. Closes #490.
 
 Client library:
 - Fix incorrect PSK key being used if it had leading zeroes.

lib/net_mosq.c

@@ -214,6 +214,10 @@ int _mosquitto_socket_close(struct mosquitto *mosq)
 
 	assert(mosq);
 #ifdef WITH_TLS
+#ifdef WITH_WEBSOCKETS
+	if(!mosq->wsi)
+#endif
+	{
 		if(mosq->ssl){
 			SSL_shutdown(mosq->ssl);
 			SSL_free(mosq->ssl);
@@ -223,6 +227,7 @@ int _mosquitto_socket_close(struct mosquitto *mosq)
 			SSL_CTX_free(mosq->ssl_ctx);
 			mosq->ssl_ctx = NULL;
 		}
+	}
 #endif
 
 	if((int)mosq->sock >= 0){