udp: add functions for joining and leaving multicast groups

include/re_udp.h

@@ -35,6 +35,9 @@ int  udp_thread_attach(struct udp_sock *us);
 void udp_thread_detach(struct udp_sock *us);
 int  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);
+
 
 /* Helper API */
 typedef bool (udp_helper_send_h)(int *err, struct sa *dst,

src/udp/mcast.c

@@ -0,0 +1,69 @@
+/**
+ * @file mcast.c  UDP Multicast
+ *
+ * Copyright (C) 2010 Creytiv.com
+ */
+
+#define _BSD_SOURCE 1
+#include <re_types.h>
+#include <re_fmt.h>
+#include <re_sa.h>
+#include <re_udp.h>
+
+
+static int multicast_update(struct udp_sock *us, const struct sa *group,
+			    bool join)
+{
+	struct ip_mreq mreq;
+#ifdef HAVE_INET6
+	struct ipv6_mreq mreq6;
+#endif
+	int err;
+
+	if (!us || !group)
+		return EINVAL;
+
+	switch (sa_af(group)) {
+
+	case AF_INET:
+		mreq.imr_multiaddr = group->u.in.sin_addr;
+		mreq.imr_interface.s_addr = 0;
+
+		err = udp_setsockopt(us, IPPROTO_IP,
+				     join
+				     ? IP_ADD_MEMBERSHIP
+				     : IP_DROP_MEMBERSHIP,
+				     &mreq, sizeof(mreq));
+		break;
+
+#ifdef HAVE_INET6
+	case AF_INET6:
+		mreq6.ipv6mr_multiaddr = group->u.in6.sin6_addr;
+		mreq6.ipv6mr_interface = 0;
+
+		err = udp_setsockopt(us, IPPROTO_IPV6,
+				     join
+				     ? IPV6_JOIN_GROUP
+				     : IPV6_LEAVE_GROUP,
+				     &mreq6, sizeof(mreq6));
+		break;
+#endif
+
+	default:
+		return EAFNOSUPPORT;
+	}
+
+	return err;
+}
+
+
+int udp_multicast_join(struct udp_sock *us, const struct sa *group)
+{
+	return multicast_update(us, group, true);
+}
+
+
+int udp_multicast_leave(struct udp_sock *us, const struct sa *group)
+{
+	return multicast_update(us, group, false);
+}

src/udp/mod.mk

@@ -5,3 +5,4 @@
 #
 
 SRCS	+= udp/udp.c
+SRCS	+= udp/mcast.c