Log message for disconnecting a client with invalid UTF-8 topic.

Closes #1144. Thanks to Kris Mattheus.

ChangeLog.txt

@@ -36,6 +36,8 @@ Broker:
 - Windows: Fix possible crash when client disconnects. Closes #1137.
 - Fixed durable clients being unable to receive messages when offline, when
   per_listener_settings was set to true. Closes #1081.
+- Add log message for the case where a client is disconnected for sending a
+  topic with invalid UTF-8. Closes #1144.
 
 Library:
 - Fix TLS connections not working over SOCKS.

src/handle_publish.c

@@ -70,6 +70,7 @@ int handle__publish(struct mosquitto_db *db, struct mosquitto *context)
 	}
 
 	if(mosquitto_validate_utf8(topic, slen) != MOSQ_ERR_SUCCESS){
+		log__printf(NULL, MOSQ_LOG_INFO, "Client %s sent topic with invalid UTF-8, disconnecting.", context->id);
 		mosquitto__free(topic);
 		return 1;
 	}