UDP fixes:

- respect multicast interface when connecting

net/ipv4/udp.c

@@ -725,6 +725,8 @@ int udp_connect(struct sock *sk, struct sockaddr *uaddr, int addr_len)
 	struct inet_opt *inet = inet_sk(sk);
 	struct sockaddr_in *usin = (struct sockaddr_in *) uaddr;
 	struct rtable *rt;
+	u32 saddr;
+	int oif;
 	int err;
 
 	
@@ -736,8 +738,16 @@ int udp_connect(struct sock *sk, struct sockaddr *uaddr, int addr_len)
 
 	sk_dst_reset(sk);
 
-	err = ip_route_connect(&rt, usin->sin_addr.s_addr, inet->saddr,
-			       RT_CONN_FLAGS(sk), sk->bound_dev_if);
+	oif = sk->bound_dev_if;
+	saddr = inet->saddr;
+	if (MULTICAST(usin->sin_addr.s_addr)) {
+		if (!oif)
+			oif = inet->mc_index;
+		if (!saddr)
+			saddr = inet->mc_addr;
+	}
+	err = ip_route_connect(&rt, usin->sin_addr.s_addr, saddr,
+			       RT_CONN_FLAGS(sk), oif);
 	if (err)
 		return err;
 	if ((rt->rt_flags&RTCF_BROADCAST) && !sk->broadcast) {

net/ipv6/udp.c

@@ -293,6 +293,8 @@ int udpv6_connect(struct sock *sk, struct sockaddr *uaddr, int addr_len)
 				return -EINVAL;
 			}
 			sk->bound_dev_if = usin->sin6_scope_id;
+			if (!sk->bound_dev_if && (addr_type&IPV6_ADDR_MULTICAST))
+				fl.oif = np->mcast_oif;
 		}
 
 		/* Connect to link-local address requires an interface */
@@ -317,6 +319,9 @@ int udpv6_connect(struct sock *sk, struct sockaddr *uaddr, int addr_len)
 	fl.uli_u.ports.dport = inet->dport;
 	fl.uli_u.ports.sport = inet->sport;
 
+	if (!fl.oif && (addr_type&IPV6_ADDR_MULTICAST))
+		fl.oif = np->mcast_oif;
+
 	if (flowlabel) {
 		if (flowlabel->opt && flowlabel->opt->srcrt) {
 			struct rt0_hdr *rt0 = (struct rt0_hdr *) flowlabel->opt->srcrt;