Before this commit, on kernel shutdown, the routes were re-exported by
the regular export but treated as withdraw. This was too hairy and
caused unnecessary complexity of the protocol's state machine.
Instead of that, we found out that it makes more sense to just refeed
the routes synchronously and convert to withdraw. This is done by the
direct export access instead of the channel.
It would (maybe) make more sense to run export filters on this in case
the export filter updates the krt_metric attribute, but as this doesn't
work on regular withdraw anyway, it's better for now to just let it be
and maybe somebody in the future fixes this issue.
When VRFs are used, BIRD correctly binds listening (and connecting)
sockets to their VRFs but also re-binds accepted sockets to the same VRF.
This is not needed as the interface bind is inherited in this case, and
indeed this redundant bind causes an -EPERM if BIRD is running as
non-root making BIRD close the connection and reject the peer.
Thanks to Christian Svensson for the original patch and Alexander Zubkov
for suggestions.
This allows to have one main socket for the heavy operations
very restricted just for the appropriate users, whereas the
looking glass socket may be more open.
Implemented an idea originally submitted and requested by Akamai.
Some vendors do not fill the checksum for IPv6 UDP packets.
For interoperability with such implementations one can set
UDP_NO_CHECK6_RX socket option on Linux.
Thanks to Ville O for the suggestion.
Minor changes by committer.
Introducing a new omnipotent internal API to just pass route updates
from whatever point wherever we want.
From now on, all the exports should be processed by RT_WALK_EXPORTS
macro, and you can also issue a separate feed-only request to just get a
feed and finish.
The exporters can now also stop and the readers must expect that to
happen and recover. Main tables don't stop, though.
Explicitly marking domains eligible for RCU synchronization. It's then
forbidden to lock these domains in RCU critical section to avoid
possible deadlock.
This commit makes the route chains in the tables atomic. This allows not
only standard exports but also feeds and bulk exports to be processed
without ever locking the table.
Design note: the overall data structures are quite brittle. We're using
RCU read-locks to keep track about readers, and we're indicating ongoing
work on the data structures by prepending a REF_OBSOLETE sentinel node
to make every reader go waiting.
All the operations are intended to stay inside nest/rt-table.c and it
may be even best to further refactor the code to hide the routing table
internal structure inside there. Nobody shall definitely write any
routines manipulating live routes in tables from outside.
