From 76e21053b5bf33a07c76f99d27a74238310e3c71 Mon Sep 17 00:00:00 2001 From: "Erich E. Hoover" Date: Wed, 8 Feb 2012 09:11:07 +0000 Subject: ipv4: Implement IP_UNICAST_IF socket option. The IP_UNICAST_IF feature is needed by the Wine project. This patch implements the feature by setting the outgoing interface in a similar fashion to that of IP_MULTICAST_IF. A separate option is needed to handle this feature since the existing options do not provide all of the characteristics required by IP_UNICAST_IF, a summary is provided below. SO_BINDTODEVICE: * SO_BINDTODEVICE requires administrative privileges, IP_UNICAST_IF does not. From reading some old mailing list articles my understanding is that SO_BINDTODEVICE requires administrative privileges because it can override the administrator's routing settings. * The SO_BINDTODEVICE option restricts both outbound and inbound traffic, IP_UNICAST_IF only impacts outbound traffic. IP_PKTINFO: * Since IP_PKTINFO and IP_UNICAST_IF are independent options, implementing IP_UNICAST_IF with IP_PKTINFO will likely break some applications. * Implementing IP_UNICAST_IF on top of IP_PKTINFO significantly complicates the Wine codebase and reduces the socket performance (doing this requires a lot of extra communication between the "server" and "user" layers). bind(): * bind() does not work on broadcast packets, IP_UNICAST_IF is specifically intended to work with broadcast packets. * Like SO_BINDTODEVICE, bind() restricts both outbound and inbound traffic. Signed-off-by: Erich E. Hoover Signed-off-by: Eric Dumazet Signed-off-by: David S. Miller --- net/ipv4/ping.c | 3 ++- 1 file changed, 2 insertions(+), 1 deletion(-) (limited to 'net/ipv4/ping.c') diff --git a/net/ipv4/ping.c b/net/ipv4/ping.c index aea5a199c37a..cfc82cf339f6 100644 --- a/net/ipv4/ping.c +++ b/net/ipv4/ping.c @@ -556,7 +556,8 @@ static int ping_sendmsg(struct kiocb *iocb, struct sock *sk, struct msghdr *msg, ipc.oif = inet->mc_index; if (!saddr) saddr = inet->mc_addr; - } + } else if (!ipc.oif) + ipc.oif = inet->uc_index; flowi4_init_output(&fl4, ipc.oif, sk->sk_mark, tos, RT_SCOPE_UNIVERSE, sk->sk_protocol, -- cgit v1.2.3