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 --- include/net/inet_sock.h | 2 ++ 1 file changed, 2 insertions(+) (limited to 'include/net/inet_sock.h') diff --git a/include/net/inet_sock.h b/include/net/inet_sock.h index e3e405106af..022f772c0eb 100644 --- a/include/net/inet_sock.h +++ b/include/net/inet_sock.h @@ -132,6 +132,7 @@ struct rtable; * @tos - TOS * @mc_ttl - Multicasting TTL * @is_icsk - is this an inet_connection_sock? + * @uc_index - Unicast outgoing device index * @mc_index - Multicast device index * @mc_list - Group array * @cork - info to build ip hdr on each ip frag while socket is corked @@ -167,6 +168,7 @@ struct inet_sock { transparent:1, mc_all:1, nodefrag:1; + int uc_index; int mc_index; __be32 mc_addr; struct ip_mc_socklist __rcu *mc_list; -- cgit v1.2.3-18-g5258