udp/mcast: Allow joining multicast group on a specific local interface

baresip · Jul 30, 2024 · ed5a03e · ed5a03e
1 parent a64cb83
commit ed5a03e
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Showing 2 changed files with 40 additions and 7 deletions.
diff --git a/include/re_udp.h b/include/re_udp.h
@@ -45,6 +45,10 @@ re_sock_t udp_sock_fd(const struct udp_sock *us, int af);
 
 int  udp_multicast_join(struct udp_sock *us, const struct sa *group);
 int  udp_multicast_leave(struct udp_sock *us, const struct sa *group);
+int  udp_multicast_join_local(struct udp_sock *us, const struct sa *group,
+			      const struct sa *local);
+int  udp_multicast_leave_local(struct udp_sock *us, const struct sa *group,
+			       const struct sa *local);
 int  udp_settos(struct udp_sock *us, uint8_t tos);
 void udp_flush(const struct udp_sock *us);
 void udp_recv_packet(struct udp_sock *us, const struct sa *src,

diff --git a/src/udp/mcast.c b/src/udp/mcast.c
@@ -5,25 +5,40 @@
  */
 #include <re_types.h>
 #include <re_fmt.h>
+#include <re_net.h>
 #include <re_sa.h>
 #include <re_udp.h>
 
 
 static int multicast_update(struct udp_sock *us, const struct sa *group,
-			    bool join)
+			    const struct sa *local, bool join)
 {
-	struct ip_mreq mreq;
+	struct ip_mreqn mreq;
 	struct ipv6_mreq mreq6;
 	int err;
+	int if_index = 0;
 
 	if (!us || !group)
 		return EINVAL;
 
+	if (local && !sa_is_any(local)) {
+		char name[64];
+		if (net_if_getname(name, sizeof(name), sa_af(local), local) != 0)
+			return EADDRNOTAVAIL;
+
+		if ((if_index = if_nametoindex(name)) == 0)
+			return ENXIO;
+	}
+
+
 	switch (sa_af(group)) {
 
 	case AF_INET:
 		mreq.imr_multiaddr = group->u.in.sin_addr;
-		mreq.imr_interface.s_addr = 0;
+		mreq.imr_ifindex = if_index;
+		if (if_index == 0) {
+			mreq.imr_address.s_addr = 0;
+		}
 
 		err = udp_setsockopt(us, IPPROTO_IP,
 				     join
@@ -34,7 +49,10 @@ static int multicast_update(struct udp_sock *us, const struct sa *group,
 
 	case AF_INET6:
 		mreq6.ipv6mr_multiaddr = group->u.in6.sin6_addr;
-		mreq6.ipv6mr_interface = sa_scopeid(group);
+		mreq6.ipv6mr_interface = if_index;
+		if (if_index = 0) {
+			mreq6.ipv6mr_interface = sa_scopeid(group);
+		}
 
 		err = udp_setsockopt(us, IPPROTO_IPV6,
 				     join
@@ -50,14 +68,25 @@ static int multicast_update(struct udp_sock *us, const struct sa *group,
 	return err;
 }
 
-
 int udp_multicast_join(struct udp_sock *us, const struct sa *group)
 {
-	return multicast_update(us, group, true);
+	return multicast_update(us, group, NULL, true);
 }
 
 
 int udp_multicast_leave(struct udp_sock *us, const struct sa *group)
 {
-	return multicast_update(us, group, false);
+	return multicast_update(us, group, NULL, false);
+}
+
+int udp_multicast_join_local(struct udp_sock *us, const struct sa *group,
+			     const struct sa *local)
+{
+	return multicast_update(us, group, local, true);
+}
+
+int udp_multicast_leave_local(struct udp_sock *us, const struct sa *group,
+			      const struct sa *local)
+{
+	return multicast_update(us, group, local, false);
 }