This commit is quite a substantial rework of the underlying layers in
BMP TX:
- several unnecessary layers of indirection dropped, including most of
the original BMP's buffer machinery
- all messages are now written directly into one protocol's buffer
allocated for the whole time big enough to fit every possible message
- output blocks are allocated by pages and immediately returned when
used, improving the overall memory footprint
- no intermediary allocation is done from the heap altogether
- there is a documented and configurable limit on the TX queue size
Move all bmp_peer_down() calls to one place and make it synchronous with
BGP session down, ensuring that BMP receives peer_down before route
withdraws from flushing.
Also refactor bmp_peer_down_() message generating code.
Now we use rt_notify() and channels for both feed and notifications,
in both import tables (pre-policy) and regular tables (post-policy).
Remove direct walk in bmp_route_monitor_snapshot().
- Manage BMP state through bmp_peer, bmp_stream, bmp_table structures
- Use channels and rt_notify() hook for route announcements
- Add support for post-policy monitoring
- Send End-of-RIB even when there is no routes
- Remove rte_update_in_notify() hook from import tables
- Update import tables to support channels
- Add bmp_hack (no feed / no flush) flag to channels
Add internal BMP functions with plicit bmp_proto *p as first argument,
which allows using TRACE() macro. Keep list of BMP instances and call
internal functions. Old BMP functions are wrappers that call internal
functions for all enabled BMP instances.
Extract End-of-RIB mark into separate function.
Based on patch from Michal Zagorski <mzagorsk@akamai.com>. Thanks!
The BMP protocol needs OPEN messages of established BGP sessions to
construct appropriate Peer Up messages. Instead of saving them internally
we use OPEN messages stored in BGP instances. This allows BMP instances
to be restarted or enabled later.
Because of this change, we can simplify BMP data structures. No need to
keep track of BGP sessions when we are not started. We have to iterate
over all (established) BGP sessions when the BMP session is established.
This is just a scaffolding now, but some kind of iteration would be
necessary anyway.
Also, the commit cleans up handling of msg/msg_length arguments to be
body/body_length consistently in both rx/tx and peer_up/peer_down calls.
Replace broken TCP connection management with a simple state machine.
Handle failed attempts properly with a timeout, detect and handle TCP
connection close and try to reconnect after that. Remove useless
'station_connected' flag.
Keep open messages saved even after the BMP session establishment,
so they can be used after BMP session flaps.
Use proper log messages for session events.
Most error handling code was was for cases that cannot happen,
or they would be code bugs (and should use ASSERT()). Keep error
handling for just for I/O errors, like in rest of BIRD.
Initial implementation of a basic subset of the BMP (BGP Monitoring
Protocol, RFC 7854) from Akamai team. Submitted for further review
and improvement.
