Re: [PATCH v6 1/2] Implement IP_UNICAST_IF socket option.

Le mardi 07 février 2012 à 14:44 -0700, Erich E. Hoover a écrit :

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 <redacted>

This seems good, only the changelog is not formatted to fit in short
lines (70 cols)

Also title should include subsystem name  :

ipv4: Implement IP_UNICAST_IF socket option.

Acked-by: Eric Dumazet <redacted>