On large configurations, too many threads would spawn with one thread
per loop. Therefore, threads may now run multiple loops at once. The
thread count is configurable and may be changed during run. All threads
are spawned on startup.

This change helps with memory bloating. BIRD filters need large
temporary memory blocks to store their stack and also memory management
keeps its hot page storage per-thread.

Known bugs:
* Thread autobalancing is not yet implemented.
* Low latency loops are executed together with standard loops.

If no channel is flushing, table prune doesn't walk over routes in nets
and also doesn't walk over importing channel lists. This helps to
alleviate the memory caching burdens a lot.

Some CLI actions, notably "show route", are run by queuing an event
somewhere else. If the user closes the socket, in case such an action is
being executed, the CLI must free the socket immediately from the error
hook but the pool must remain until the asynchronous event finishes and
cleans everything up.

Add support for kernel route metric/priority, exported as krt_metric
attribute, like in Linux. This should also fix issues with overwriting
or removing system routes.

Mike Crute authored 2 years ago and Ondřej Zajíček committed 2 years ago

Log message before aborting due to watchdog timeout. We have to use
async-safe write to debug log, as it is done in signal handler.

Minor changes from committer.

Most branching instructions (FI_CONDITION, FI_AND, FI_OR) linearize its
branches in a recursive way, while FI_SWITCH branches are linearized
from parser even before the switch instruction is allocated.

Change linearization of FI_SWITCH branches to make it similar to other
branching instructions. This also fixes an issue with constant
switch evaluation, where linearized branch is mistaken for
non-linearized during switch construction.

Thanks to Jiten Kumar Pathy for the bugreport.

Some of these new BGP role keywords use generic names that collides with
user-defined symbols. Allow them to be redefined. Also remove duplicit
keyword definition for 'prefer'.

During backporting attribute changes from 3.0-branch, some internal
attributes (RIP iface and Babel seqno) leaked to 'show route all' output.
Allow protocols to hide specific attributes with GA_HIDDEN value.

Thanks to Nigel Kukard for the bugreport.

In some cases 16-way tries are too memory-heavy, while 4-way are
almost as efficient as the original 2-way ones.

There were some confusion about validity and usage of pflags, which
caused incorrect usage after some flags from (now removed) protocol-
specific area were moved to pflags.

We state that pflags:

 - Are secondary data used by protocol-specific hooks
 - Can be changed on an existing route (in contrast to copy-on-write
   for primary data)
 - Are irrelevant for propagation (not propagated when changed)
 - Are specific to a routing table (not propagated by pipe)

The patch did these fixes:

 - Do not compare pflags in rte_same(), as they may keep cached values
   like BGP_REF_STALE, causing spurious propagation.

 - Initialize pflags to zero in rte_get_temp(), avoid initialization in
   protocol code, fixing at least two forgotten initializations (krt
   and one case in babel).

 - Improve documentation about pflags

Toke Høiland-Jørgensen authored 2 years ago and Ondřej Zajíček committed 2 years ago

The seqno request retransmission handling was tracking the destination
that a forwarded request was being sent to and always retransmitting to
that same destination. This is unnecessary because we only need to
retransmit requests we originate ourselves, not those we forward on
behalf of others; in fact retransmitting on behalf of others can lead to
exponential multiplication of requests, which would be bad.

So rework the seqno request tracking so that instead of storing the
destination of a request, we just track whether it was a request that we
forwarded on behalf of another node, or if it was a request we originated
ourselves. Forwarded requests are not retransmitted, they are only used
for duplicate suppression, and for triggering an update when satisfied.
If we end up originating a request that we previously forwarded, we
"upgrade" the old request and restart the retransmit counter.

One complication with this is that requests sent in response to unfeasible
updates (section 3.8.2.2 of the RFC) have to be sent as unicast to a
particular peer. However, we don't really need to retransmit those as
there's no starvation when sending such a request; so we just change
such requests to be one-off unicast requests that are not subject to
retransmission or duplicate suppression. This is the same behaviour as
babeld has for such requests.

Minor changes from committer.

Alexander Chernikov authored 2 years ago and Ondřej Zajíček committed 2 years ago

Minor changes from committer.

Alexander Chernikov authored 2 years ago and Ondřej Zajíček committed 2 years ago

Minor changes from committer.

Use symlinks to linux/netlink* to avoid limitations of our buildsystem.

FreeBSD 13.0 added some safechecks for syscalls, rejecting sockaddrs that
are too small, later versions loosen up the check.

Thanks Johannes Moos for the suggestion.

When there is a continuos stream of CLI commands, cli_get_command()
always returns 1 (there is a new command). Anyway, the socket receive
buffer was reset only when there was no command at all, leading to a
strange behavior: after a while, the CLI receive buffer came to its end,
then read() was called with zero size buffer, it returned 0 which was
interpreted as EOF.

The patch fixes that by resetting the buffer position after each command
and moving remaining data at the beginning of buffer.

Thanks to Maria Matejka for examining the bug and for the original bugfix.

The import table does not work reliably together with re-evaluation of
routes due to recursive next hops or flowspec validation. We will at
least document that here, as import tables are completely redesigned and
this issue is fixed in BIRD 3.x branch.