Fix max_connections not being honoured on libwebsockets listeners.

Closes #3455. Thanks to FelixPopp.

ChangeLog.txt

@@ -10,6 +10,8 @@
 - Fix inconsistent disconnect log message format, and add address:port.
 - Fix `plugin`/`global_plugin` option not allowing space characters.
 - Fix $SYS load values not being published initially. Closes #3459.
+- Fix max_connections not being honoured on libwebsockets listeners. This does
+  not affect the built-in websockets support. Closes #3455.
 
 # Plugins
 - Fix incorrect linking of libmosquitto_common.so for the acl and password

src/websockets.c

@@ -170,12 +170,14 @@ static int callback_mqtt(
 				u->mosq = NULL;
 				return -1;
 			}
+			mosq->listener->client_count++;
 			if((mosq->listener->max_connections > 0 && mosq->listener->client_count > mosq->listener->max_connections)
 					|| (db.config->global_max_connections > 0 && HASH_CNT(hh_sock, db.contexts_by_sock) > (unsigned int)db.config->global_max_connections)){
 
 				if(db.config->connection_messages == true){
 					log__printf(NULL, MOSQ_LOG_NOTICE, "Client connection from %s denied: max_connections exceeded.", mosq->address);
 				}
+				mosq->listener->client_count--;
 				mosquitto_FREE(mosq->address);
 				mosquitto_FREE(mosq);
 				u->mosq = NULL;
@@ -196,6 +198,7 @@ static int callback_mqtt(
 					HASH_DELETE(hh_sock, db.contexts_by_sock, mosq);
 					mosq->sock = INVALID_SOCKET;
 					mux__delete(mosq);
+					mosq->listener->client_count--;
 				}
 				mosq->wsi = NULL;
 #ifdef WITH_TLS