[PATCH 2.x branch] BGP: Bind listen socket to VRF

[Ondrej Zajicek]

On Fri, Oct 26, 2018 at 08:38:28PM +0200, Alexander Zubkov wrote:
> Hi,
> 
> Thank you for improving the patch.
> 
> Did I get it right? You mean the case when one has the same IP for BGP
> sessions in different VRFs on different interfaces?

Unless 'strict bind' option is used, local IP is irrelevant, because
listening socket is bound to 0.0.0.0 anyways (addr in bgp_open() is
IPA_NONE4/6).

If i have two BGP protocols, one in vrf1 and the second in vrf2, then i
need two listening sockets, first bound to 0.0.0.0 in vrf1, second to
0.0.0.0 in vrf2, they are bound to the same IPA_NONE4/6 address, but in
different VRFs. In your patch the second socket would not be created,
instead the first one would be reused (incorrectly) for the second
protocol.

The old code (without setting vrf) would have one listening socket not
bound to any vrf, such socket would accept incoming sessions from both
vrf1 and vrf2, but cannot distinguish them properly if both have the
same remote ip.

Also, it is possible that the new code has a problem that it would fail
when there are two BGP sessions, one bound to a VRF and one that is not,
because such two listening sockets would be incompatible, i would have to
check that.

Now thinking about it, i also need to fix bgp_find_proto() so that
incoming connections are dispatched properly based on vrfs.

-- 
Elen sila lumenn' omentielvo

Ondrej 'Santiago' Zajicek (email: santiago at crfreenet.org)
OpenPGP encrypted e-mails preferred (KeyID 0x11DEADC3, wwwkeys.pgp.net)
"To err is human -- to blame it on a computer is even more so."
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