Add support for X-Forwarded-For LWS

I know you've added this for the next release, but here is a fix
for LWS. But just incase there are any more 2.0.x releases.

It does leave the incoming port as 0 but as this is pretty meaningless
for a proxied connection I think it's probably ok.

Signed-off-by: Ben Hardill <hardillb@gmail.com>

src/websockets.c

@@ -133,6 +133,7 @@ static int callback_mqtt(
 	uint8_t *buf;
 	int rc;
 	uint8_t byte;
+	char ip_addr_buff[1024];
 
 	switch (reason) {
 		case LWS_CALLBACK_ESTABLISHED:
@@ -157,7 +158,12 @@ static int callback_mqtt(
 			}else{
 				return -1;
 			}
+
+			if (lws_hdr_copy(wsi, ip_addr_buff, sizeof(ip_addr_buff), WSI_TOKEN_X_FORWARDED_FOR) > 0) {
+				mosq->address = mosquitto__strdup(ip_addr_buff);
+			} else {
 				easy_address(lws_get_socket_fd(wsi), mosq);
+			}
 			if(!mosq->address){
 				/* getpeername and inet_ntop failed and not a bridge */
 				mosquitto__free(mosq);