ipv6: report sin6_scope_id if sockopt RECVORIGDSTADDR is set

v4:
a) unchanged

Cc: YOSHIFUJI Hideaki <yoshfuji@linux-ipv6.org>
Acked-by: NYOSHIFUJI Hideaki <yoshfuji@linux-ipv6.org>
Signed-off-by: NHannes Frederic Sowa <hannes@stressinduktion.org>
Acked-by: NYOSHIFUJI Hideaki <yoshfuji@linux-ipv6.org>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

net/ipv6/datagram.c

@@ -594,7 +594,9 @@ int ip6_datagram_recv_ctl(struct sock *sk, struct msghdr *msg,
 			sin6.sin6_addr = ipv6_hdr(skb)->daddr;
 			sin6.sin6_port = ports[1];
 			sin6.sin6_flowinfo = 0;
-			sin6.sin6_scope_id = 0;
+			sin6.sin6_scope_id =
+				ipv6_iface_scope_id(&ipv6_hdr(skb)->daddr,
+						    opt->iif);
 
 			put_cmsg(msg, SOL_IPV6, IPV6_ORIGDSTADDR, sizeof(sin6), &sin6);
 		}