From a2560a481b6176e8e33bee63222d6ca46a111f12 Mon Sep 17 00:00:00 2001
From: df <fieldhouse@gmx.net>
Date: Sun, 19 Jul 2020 03:03:37 +0000
Subject: [PATCH] Set multicast IP TTL to 255 in case a receiver demands an
 unrouted packet

Fixing #5 Tinysvcmdns invisible from chrome app mdns-browser
---
 mdnsd.c | 8 ++++++++
 1 file changed, 8 insertions(+)

diff --git a/mdnsd.c b/mdnsd.c
index 6488a53..f5622c7 100644
--- a/mdnsd.c
+++ b/mdnsd.c
@@ -127,6 +127,14 @@ static int create_recv_sock() {
 		log_message(LOG_ERR, "recv bind(): %m");
 	}
 
+	// (issue #5 Tinysvcmdns invisible from chrome app mdns-browser)
+	// TTL -> 255 in case receivers demand it (unrouted pkt)
+	int ttl = 255;
+	if ((r = setsockopt(sd, IPPROTO_IP, IP_MULTICAST_TTL, (void*) &ttl, sizeof(ttl))) < 0) {
+		log_message(LOG_ERR, "recv setsockopt(IP_MULTICAST_IP): %m");
+		return r;
+	}
+
 	// add membership to receiving socket
 	struct ip_mreq mreq;
 	memset(&mreq, 0, sizeof(struct ip_mreq));