This instruction was removed in the commit linked below
and never used ever again. Rest in peace.

commit 84c7e194
Author: Pavel Machek <pavel@ucw.cz>
Date:   Tue Mar 2 19:49:28 1999 +0000

It was supposed to do tail-recursion in interpret() but it didn't
compile as such. Converting it to loop makes a significant filter
performance improvement for flat filters.

The two-letter instructions were quite messy but they could be easily
read from memory dumps. Now GDB (since 2012) supports pretty printing
enum values and GCC checks the switch construction for missing enum
values so we are converting the nice two-byte values to enums.

Anyway, the enum still keeps the old two-byte values to be able to read
the instruction codes even without GDB from plain memory dump.

Uncommented an old test.

A filter should log messages only if executed explicitly (e.g., during
route export or route import). When a filter is executed for technical
reasons (e.g., to establish whether a route was exported before), it
should run silently.

To comply with RFC 8212 requirements.

The same is already done for clists. Also fixes defined() to work
properly for paths and clists.

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.

They are internally ints, but they got refused as a wrong type. This
fixes setting of the BGP origin and is also needed for RA.

Thanks to Lennert Buytenhek <buytenh@wantstofly.org> for the patch.

Lexer always parsed numbers as unsigned, but parser handled them as
signed and grammar contained many unnecessary checks for negativity.

BTW, 'prefices' is hypercorrection, as 'prefix' is from 'praefixum' with
plural 'praefixa'.

Thanks to Vincent Bernat for the patch.

Dropped struct mpnh and mpnh_*()
Now struct nexthop exists, nexthop_*(), and also included struct nexthop
into struct rta.

Also converted RTD_DEVICE and RTD_ROUTER to RTD_UNICAST. If it is needed
to distinguish between these two cases, RTD_DEVICE is equivalent to
IPA_ZERO(a->nh.gw), RTD_ROUTER is then IPA_NONZERO(a->nh.gw).

From now on, we also explicitely want C99 compatible compiler. We assume
that this 20-year norm should be known almost everywhere.

Add flow4/flow6 network and rt-table type and operations, config grammar
and static protocol support.

Squashed flowspec branch from Pavel Tvrdik.

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

Example:
  bird> eval (1.2.0.0/16 max 20 as 1234).maxlen
  20

Todo: Should be described in user docs

Example:
  bird> eval (1.2.0.0/16 max 20 as 1234).asn
  1234

Todo: Should be described in user docs

The RPKI protocol (RFC 6810) using the RTRLib
(http://rpki.realmv6.org/) that is integrated inside
the BIRD's code.

Implemeted transports are:
 - unprotected transport over TCP
 - secure transport over SSHv2

Example configuration of bird.conf:
  ...
  roa4 table r4;
  roa6 table r6;

  protocol rpki {
    debug all;

    # Import both IPv4 and IPv6 ROAs
    roa4 { table r4; };
    roa6 { table r6; };

    # Set cache server (validator) address,
    # overwrite default port 323
    remote "rpki-validator.realmv6.org" port 8282;

    # Overwrite default time intervals
    retry   10;         # Default 600 seconds
    refresh 60;         # Default 3600 seconds
    expire 600;         # Default 7200 seconds
  }

  protocol rpki {
    debug all;

    # Import only IPv4 routes
    roa4 { table r4; };

    # Set cache server address to localhost,
    # use default ports tcp => 323 or ssh => 22
    remote 127.0.0.1;

    # Use SSH transport instead of unprotected transport over TCP
    ssh encryption {
      bird private key "/home/birdgeek/.ssh/id_rsa";
      remote public key "/home/birdgeek/.ssh/known_hosts";
      user "birdgeek";
    };
  }
  ...

It was an example filtering configuration from BIRD's wiki.

Tests are sorted from trivial tests to more complex tests