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authorErich E. Hoover <ehoover@mines.edu>2012-02-08 09:11:07 +0000
committerDavid S. Miller <davem@davemloft.net>2012-02-08 15:52:45 -0500
commit76e21053b5bf33a07c76f99d27a74238310e3c71 (patch)
tree70ac2a67be8f19da96896950447567e156975149 /include/linux/in.h
parent43480aecb1f538d4f6dd8b2c5d2b71fb98659072 (diff)
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 <ehoover@mines.edu> Signed-off-by: Eric Dumazet <eric.dumazet@gmail.com> Signed-off-by: David S. Miller <davem@davemloft.net>
Diffstat (limited to 'include/linux/in.h')
-rw-r--r--include/linux/in.h1
1 files changed, 1 insertions, 0 deletions
diff --git a/include/linux/in.h b/include/linux/in.h
index 01129c0ea87c..e0337f11d92e 100644
--- a/include/linux/in.h
+++ b/include/linux/in.h
@@ -111,6 +111,7 @@ struct in_addr {
#define MCAST_LEAVE_SOURCE_GROUP 47
#define MCAST_MSFILTER 48
#define IP_MULTICAST_ALL 49
+#define IP_UNICAST_IF 50
#define MCAST_EXCLUDE 0
#define MCAST_INCLUDE 1