This basically means that:
* there are some more levels of indirection and asynchronicity, mostly
in cleanup procedures, requiring correct lock ordering
* all the internal table operations (prune, next hop update) are done
without blocking the other parts of BIRD
* the protocols may get their own loops very soon
This commit prevents use-after-free of routes belonging to protocols
which have been already destroyed, delaying also all the protocols'
shutdown until all of their routes have been finally propagated through
all the pipes down to the appropriate exports.
The use-after-free was somehow hypothetic yet theoretically possible in
rare conditions, when one BGP protocol authors a lot of routes and the
user deletes that protocol by reconfiguring in the same time as next hop
update is requested, causing rte_better() to be called on a
not-yet-pruned network prefix while the owner protocol has been already
freed.
In parallel execution environments, this would happen an inter-thread
use-after-free, causing possible heisenbugs or other nasty problems.
There is a simple universal IO loop, taking care of events, timers and
sockets. Primarily, one instance of a protocol should use exactly one IO
loop to do all its work, as is now done in BFD.
Contrary to previous versions, the loop is now launched and cleaned by
the nest/proto.c code, allowing for a protocol to just request its own
loop by setting the loop's lock order in config higher than the_bird.
It is not supported nor checked if any protocol changed the requested
lock order in reconfigure. No protocol should do it at all.
Channels have now included rt_import_req and rt_export_req to hook into
the table instead of just one list node. This will (in future) allow for:
* channel import and export bound to different tables
* more efficient pipe code (dropping most of the channel code)
* conversion of 'show route' to a special kind of export
* temporary static routes from CLI
The import / export states are also updated to the new algorithms.
Routes are now allocated only when they are just to be inserted to the
table. Updating a route needs a locally allocated route structure.
Ownership of the attributes is also now not transfered from protocols to
tables and vice versa but just borrowed which should be easier to handle
in a multithreaded environment.
For numeric operators, comma is used for disjunction in expressions like
"10, 20, 30..40". But for bitmask operators, comma is used for
conjunction in a way that does not really make much sense. Use always
explicit logical operators (&& and ||) to connect bitmask operators.
Thanks to Matt Corallo for the bugreport.
Add support to set or read outgoing MPLS labels using filters. Currently
this supports the addition of one label per route for the first next hop.
Minor changes by committer.
Broken detection of top-level case caused crash when return was called
from top-of-stack position. It should behave as reject/accept.
Thanks to Damian Zaremba for the bugreport.
Add 'weight' route attribute that allows to get and set ECMP weight of
nexthops. Similar to 'gw' attribute, it is limited to the first nexthop,
but it is useful for handling BGP multipath, where an ECMP route is
merged from multiple regular routes.
Compare the content of PM_ASN_SET in path masks. A reconfiguration
was not properly triggering a reload of affected protocols when the
members of a set in a path mask change.
Also, update the printing code to so that it can display sets in a path
mask.
Add a missing return statement. Path masks with the same length were all
considered the same. Comparing two with different length would cause
out-of-bounds memory access.
Implement regex-like '+' operator in BGP path masks to match previous
path mask item multiple times. This is useful as ASNs may appear
multiple times in paths due to path prepending for traffic engineering
purposes.
Do not apply dynamic type check for second argument of AND/OR, as it is
not evaluated immediately like regular argument would be.
Thanks to Mikael for the bugreport.
Initial parsing of test.conf must be done directly in filter_test main,
while reconfiguration is handled as a regular test. Also fix several
minor issues in test code.
We use constant promotion from IPv4 to Router-ID values, as they have
same literals. Instead of ad-hoc code in filter instructions, add
constant promotion code to parse-time typecheck code.
Most expressions can be type-validated in parse time. It is not
strong enough to eliminate runtime checks, but at least one gets
errors immediately during reconfigure.
Function bodies were compared in post-parse time, yet the result was not
used and the functions were incorrectly considered the same as before.
Now the result is used to reload affected protocols.
