mosquitto-lib: close socketpair on (re)connect

If the socket pair is still opened on reconnect, close it before
creating it again (just like the state variables). Otherwise, these
sockets are leaked on multiple mosquitto_connect() calls.

Signed-off-by: Simon Wunderlich <sw@simonwunderlich.de>

lib/mosquitto.c

@@ -407,6 +407,15 @@ static int _mosquitto_connect_init(struct mosquitto *mosq, const char *host, int
 
 	mosq->keepalive = keepalive;
 
+	if(mosq->sockpairR != INVALID_SOCKET){
+		COMPAT_CLOSE(mosq->sockpairR);
+		mosq->sockpairR = INVALID_SOCKET;
+	}
+	if(mosq->sockpairW != INVALID_SOCKET){
+		COMPAT_CLOSE(mosq->sockpairW);
+		mosq->sockpairW = INVALID_SOCKET;
+	}
+
 	if(_mosquitto_socketpair(&mosq->sockpairR, &mosq->sockpairW)){
 		_mosquitto_log_printf(mosq, MOSQ_LOG_WARNING,
 				"Warning: Unable to open socket pair, outgoing publish commands may be delayed.");