This fixes an internal table cleanup bug introduced
in ff397df7.

This also fixes memory leaks from import/export tables being never
cleaned up and freed.

If there are roa_check() calls in channel filters, then the channel
subscribes to ROA table notifications, which are sent when ROA tables
are updated (subject to settle time) and trigger channel reload or
refeed.

Thanks to Robert Scheck <bird@robert-scheck.de> who reported it
and Toke Høiland-Jørgensen <toke@toke.dk> who suggested this patch.

The old code stored route verdicts and temporary routes directly in
rtable. The new code do not store received routes (it immediately
compares them with exported routes and resolves conflicts) and uses
internal bitmap to keep track of which routes were received and which
needs to be reinstalled.

By not putting 'invalid' temporary routes to rtable, we keep rtable
in consistent state, therefore scan no longer needs to be atomic
operation and could be splitted to multiple events.

This info is now stored in an internal bmap. Unfortunately, net.flags
is still needed for temporary kernel data.

The same information is stored in export_map of kernel protocol.

Use a hierarchical bitmap in a routing table to assign ids to routes, and
then use bitmaps (indexed by route id) in channels to keep track whether
routes were exported. This avoids unreliable and inefficient re-evaluation
of filters for old routes in order to determine whether they were exported.

The patch implements optional internal export table to a channel and
hooks it to BGP so it can be used as Adj-RIB-Out. When enabled, all
exported (post-filtered) routes are stored there. An export table can be
examined using e.g. 'show route export table bgp1.ipv4'.

Nest requires that nexthops are sorted, the kernel protocol have to
ensure that for alien routes.

The temporary atttributes are no longer removed by ea_do_prune(), but
they are undefined by store_tmp_attrs() protocol hooks. This fixes
several bugs where temporary attributes were removed when they should
not or not removed when they should be. The flag EAF_TEMP is no longer
needed and was removed.

Update all protocol make_tmp_attrs() / store_tmp_attrs() hooks to use
helper functions and to handle unset attributes properly.

Also fix some related bugs like improper handling of empty eattr list.

Keep track of whether OSPF tmpattrs are actually defined for given route
(using flags in rte->pflags). That makes them behave more like real
eattrs so a protocol can define just a subset of them or they can be
undefined by filters.

Do not set ospf_metric2 for other than type 2 external OSPF routes and do
not set ospf_tag for non-external OSPF routes. That also fixes a bug
where internal/inter-area route propagated from one OSPF instance to
another is initiated with infinity ospf_metric2.

Thanks to Yaroslav Dronskii for the bugreport.

... and consted some declarations.

This is a major change of how the filters are interpreted. If everything
works how it should, it should not affect you unless you are hacking the
filters themselves.

Anyway, this change should make a huge improvement in the filter performance
as previous benchmarks showed that our major problem lies in the
recursion itself.

There are also some changes in nest and protocols, related mostly to
spreading const declarations throughout the whole BIRD and also to
refactored dynamic attribute definitions. The need of these came up
during the whole work and it is too difficult to split out these
not-so-related changes.

This protocol is highly experimental and nobody should use it in
production. Anyway it may help you getting some insight into what eats
so much time in filter processing.

The patch implements optional internal import table to a channel and
hooks it to BGP so it can be used as Adj-RIB-In. When enabled, all
received (pre-filtered) routes are stored there and import filters can
be re-evaluated without explicit route refresh. An import table can be
examined using e.g. 'show route import table bgp1.ipv4'.

For local route marking purposes, local custom route attributes may be
defined. These attributes are seamlessly stripped after export filter to
every real protocol like Kernel, BGP or OSPF, they however pass through
pipes. We currently allow at most 256 custom attributes.

This should be much faster than currently used bgp communities
for marking routes.

Once upon a time, far far away, there were the old Bird developers
discussing what direction of route flow shall be called import and
export. They decided to say "import to protocol" and "export to table"
when speaking about a protocol. When speaking about a table, they
spoke about "importing to table" and "exporting to protocol".

The latter terminology was adopted in configuration, then also the
bird CLI in commit ea2ae6dd started to use it (in year 2009). Now
it's 2018 and the terminology is the latter. Import is from protocol to
table, export is from table to protocol. Anyway, there was still an
import_control hook which executed right before route export.

One thing is funny. There are two commits in April 1999 with just two
minutes between them. The older announces the final settlement
on config terminology, the newer uses the other definition. Let's see
their commit messages as the git-log tool shows them (the newer first):

    commit 9e0e485e
    Author: Martin Mares <mj@ucw.cz>
    Date:   Mon Apr 5 20:17:59 1999 +0000

	Added some new protocol hooks (look at the comments for better explanation):

		make_tmp_attrs          Convert inline attributes to ea_list
		store_tmp_attrs         Convert ea_list to inline attributes
		import_control          Pre-import decisions

    commit 5056c559
    Author: Martin Mares <mj@ucw.cz>
    Date:   Mon Apr 5 20:15:31 1999 +0000

	Changed syntax of attaching filters to protocols to hopefully the final
	version:

		EXPORT <filter-spec>    for outbound routes (i.e., those announced
					by BIRD to the rest of the world).
		IMPORT <filter-spec>    for inbound routes (i.e., those imported
					by BIRD from the rest of the world).

	where <filter-spec> is one of:

		ALL                     pass all routes
		NONE                    drop all routes
		FILTER <name>           use named filter
		FILTER { <filter> }     use explicitly defined filter

	For all protocols, the default is IMPORT ALL, EXPORT NONE. This includes
	the kernel protocol, so that you need to add EXPORT ALL to get the previous
	configuration of kernel syncer (as usually, see doc/bird.conf.example for
	a bird.conf example :)).

Let's say RIP to this almost 19-years-old inconsistency. For now, if you
import a route, it is always from protocol to table. If you export a
route, it is always from table to protocol.

And they lived happily ever after.

The new MRT protocol is responsible for periodic RIB table dumps in the
MRT format (RFC 6396). Also the existing code for BGP4MP MRT dumps is
refactored and splitted between BGP to MRT protocols, will be more
integrated into MRT in the future.

Example:

protocol mrt {
        table "*";
        filename "%N_%F_%T.mrt";
        period 60;
}

It is partially based on the old MRT code from Pavel Tvrdik.

Some new route source values did not have associated string
in rta_show(), which might caused crash in some cases.

The patch implements long-lived graceful restart for BGP, namely
draft-uttaro-idr-bgp-persistence-03.

This is a fundamental change of an original (1999) concept of route
processing inside BIRD. During import/export, there was a temporary
ea_list created which was to be used instead of the another one inside
the route itself.

This led to some confusion, quirks, and strange filter code that handled
extended route attributes. Dropping it now.

The protocol interface has changed in an uniform way -- the
`struct ea_list *attrs` argument has been removed from store_tmp_attrs(),
import_control(), rt_notify() and get_route_info().

This supersedes the EAP_* constants.

Internal table used for route learn was created with non-matching net
type for IPv6 kernel proto.

Thanks to Toke Hoiland-Jorgensen for the bugreport

ECMP is not enabled on BSD, where it is not supported by BIRD.

Several changes and bugfixes in Babel, namely:

- Exported route parameters stored directly in route table entry
- Exported non-babel routes no longer stored in per-entry route list
- Route update, selection and retraction simplified and fixed
- Route feasibility is evalualated per update and stored with route
- Unreachable route handling fixed, based on hold interval
- Added 'show babel routes' command

Overall, it fixes some issues with proper propagation of triggered
updates, making Babel convergence after topology change almost
instant.

Date/time output (e.g. in logs, show commands) can use %f to specify
subsecond time. By default, millisecond precision is used in output.

Michal 'vorner' Vaner authored 7 years ago and Ondřej Zajíček committed 7 years ago

The patch implements Default Router Preferences and More-Specific Routes
(RFC 4191) for RAdv protocol, allowing to announce router preference and
more specific routes in router advertisements. Routes can be exported to
RAdv like to regular routing protocols.

Some cleanups, bugfixes and other changes done by Ondrej Zajicek.

Add proper support for per-nexthop onlink flag in routes to handle next
hop addresses that are not covered by interface IP ranges. Supported by
kernel and static protocols.

Thanks to Vincent Bernat for the idea.

Some code cleanup, multiple bugfixes, allows to specify also channel
for 'show route export'. Interesting how such apparenty simple thing
like show route cmd has plenty of ugly corner cases.