[474935] Increment inflight message count correctly.

Don't duplicate the increment when queueing.

Thanks to Joe McIlvain.

Bug: https://bugs.eclipse.org/bugs/show_bug.cgi?id=474935

ChangeLog.txt

@@ -11,6 +11,7 @@ Client library:
 - Handle fragmented TLS packets without a delay. Closes #470660.
 - Fix incorrect loop timeout being chosen when using threaded interface and
   keepalive = 0. Closes #471334.
+- Increment inflight messages count correctly. Closes #474935.
 
 Clients:
 - Report error string on connection failure rather than error code.

THANKS.txt

@@ -40,6 +40,7 @@ Gianfranco Costamagna
 Hiram van Paassen
 Jan-Piet Mens
 Joan Zapata
+Joe McIlvain
 Karl Palsson
 Larry Lendo
 Martin Assarsson

lib/messages_mosq.c

@@ -106,8 +106,18 @@ void mosquitto_message_free(struct mosquitto_message **message)
 	_mosquitto_free(msg);
 }
 
-void _mosquitto_message_queue(struct mosquitto *mosq, struct mosquitto_message_all *message, enum mosquitto_msg_direction dir)
+
+/*
+ * Function: _mosquitto_message_queue
+ *
+ * Returns:
+ *	0 - to indicate an outgoing message can be started
+ *	1 - to indicate that the outgoing message queue is full (inflight limit has been reached)
+ */
+int _mosquitto_message_queue(struct mosquitto *mosq, struct mosquitto_message_all *message, enum mosquitto_msg_direction dir)
 {
+	int rc = 0;
+
 	/* mosq->*_message_mutex should be locked before entering this function */
 	assert(mosq);
 	assert(message);
@@ -121,8 +131,12 @@ void _mosquitto_message_queue(struct mosquitto *mosq, struct mosquitto_message_a
 			mosq->out_messages = message;
 		}
 		mosq->out_messages_last = message;
-		if(message->msg.qos > 0 && (mosq->max_inflight_messages == 0 || mosq->inflight_messages < mosq->max_inflight_messages)){
+		if(message->msg.qos > 0){
+			if(mosq->max_inflight_messages == 0 || mosq->inflight_messages < mosq->max_inflight_messages){
 				mosq->inflight_messages++;
+			}else{
+				rc = 1;
+			}
 		}
 	}else{
 		mosq->in_queue_len++;
@@ -134,6 +148,7 @@ void _mosquitto_message_queue(struct mosquitto *mosq, struct mosquitto_message_a
 		}
 		mosq->in_messages_last = message;
 	}
+	return rc;
 }
 
 void _mosquitto_messages_reconnect_reset(struct mosquitto *mosq)

lib/messages_mosq.h

@@ -22,7 +22,7 @@ Contributors:
 void _mosquitto_message_cleanup_all(struct mosquitto *mosq);
 void _mosquitto_message_cleanup(struct mosquitto_message_all **message);
 int _mosquitto_message_delete(struct mosquitto *mosq, uint16_t mid, enum mosquitto_msg_direction dir);
-void _mosquitto_message_queue(struct mosquitto *mosq, struct mosquitto_message_all *message, enum mosquitto_msg_direction dir);
+int _mosquitto_message_queue(struct mosquitto *mosq, struct mosquitto_message_all *message, enum mosquitto_msg_direction dir);
 void _mosquitto_messages_reconnect_reset(struct mosquitto *mosq);
 int _mosquitto_message_remove(struct mosquitto *mosq, uint16_t mid, enum mosquitto_msg_direction dir, struct mosquitto_message_all **message);
 void _mosquitto_message_retry_check(struct mosquitto *mosq);

lib/mosquitto.c

@@ -549,6 +549,7 @@ int mosquitto_publish(struct mosquitto *mosq, int *mid, const char *topic, int p
 {
 	struct mosquitto_message_all *message;
 	uint16_t local_mid;
+	int queue_status;
 
 	if(!mosq || !topic || qos<0 || qos>2) return MOSQ_ERR_INVAL;
 	if(strlen(topic) == 0) return MOSQ_ERR_INVAL;
@@ -594,8 +595,8 @@ int mosquitto_publish(struct mosquitto *mosq, int *mid, const char *topic, int p
 		message->dup = false;
 
 		pthread_mutex_lock(&mosq->out_message_mutex);
-		_mosquitto_message_queue(mosq, message, mosq_md_out);
+		queue_status = _mosquitto_message_queue(mosq, message, mosq_md_out);
-		if(mosq->max_inflight_messages == 0 || mosq->inflight_messages < mosq->max_inflight_messages){
+		if(queue_status == 0){
 			if(qos == 1){
 				message->state = mosq_ms_wait_for_puback;
 			}else if(qos == 2){