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.

Nasato Goto authored 4 years ago and Ondřej Zajíček committed 4 years ago

The bug generated invalid AGGREGATOR attribute during translation of
32bit ASN to 16bit-only BGP peer. The patch fixes that.

There is a pending draft to make them obsolete

Allow to not only use set literals in path masks, but also existing
set constants or set expressions.

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.

Integrated and extensible BGP with generalized AFI handling,
support for IPv4+IPv6 AFI and unicast+multicast SAFI.

Commit 3c09af41... changed behavior of int_set_add() from prepend to
append, which makes more sense for community list, but prepend must be
used for cluster list. Add int_set_prepend() and use it in cluster list
handling code.

Add support for large communities (draft-ietf-idr-large-community),
96bit alternative to RFC 1997 communities.

Thanks to Matt Griswold for the original patch.

Similar to allowas-in option on other routers.

Thanks to Sergey Popovich for the original patch.

Allows add/filter/delete clist on clist (set algebra on clists).

Allows number ~ bgppath match.

Old AS path maching supposes thath AS number appears
only once in AS path, but that is not true. It also
contains some bugs related to AS path sets.

New code does not use any assumptions about semantic
structure of AS path. It is asymptotically slower than
the old code, but on real paths it is not significant.

It also allows '?' for matching one arbitrary AS number.

AS4 optional attribute errors were handled by session
drop (according to BGP RFC). This patch implements
error handling according to new BGP AS4 draft (*)
 - ignoring invalid AS4 optional attributes.

(*) http://www.ietf.org/internet-drafts/draft-chen-rfc4893bis-02.txt

 - Old MED handling was completely different from behavior
   specified in RFCs - for example they havn't been propagated
   to neighboring areas.

 - Update tie-breaking according to RFC 4271.

 - Change default value for 'default bgp_med' configuration
   option according to RFC 4271.

Added real comparison of BGP routes (inspired by the Cisco one).
Default local preference and default MED are now settable.
Defined filter keywords for all BGP attributes we know.

on AS paths and community sets.

Moved as_path_prepend() there.

Pavel, please move the other functions as well.