Re: [PATCH 2/2 net-next] net: implement IP_RECVTOS for IP_PKTOPTIONS

From: Jiri Benc <redacted>
Date: Thu, 9 Feb 2012 20:35:49 +0100

Currently, it is not easily possible to get TOS/DSCP value of packets from
an incoming TCP stream. The mechanism is there, IP_PKTOPTIONS getsockopt
with IP_RECVTOS set, the same way as incoming TTL can be queried. This is
not actually implemented for TOS, though.

This patch adds this functionality, both for IPv4 (IP_PKTOPTIONS) and IPv6
(IPV6_2292PKTOPTIONS). For IPv4, like in the IP_RECVTTL case, the value of
the TOS field is stored from the other party's ACK.

This is needed for proxies which require DSCP transparency. One such example
is at http://zph.bratcheda.org/.

Signed-off-by: Jiri Benc <redacted>

All new features should be submitted against the net-next tree, and this
patch didn't apply there cleanly.

I fixed up the problems, but now that you've been warned I won't do so
for you next time.