Exa-Networks/exabgp 5.0.13

ExaBGP 'Waving Hand' Release

on GitHub

Version 5.0.13

This release is about what a BGP peer can do to ExaBGP and to the programs
reading its API. Three changes alter what a peer or a consumer sees, so read
the compatibility notes before upgrading.

• Security: a peer could write data of its own into the API streams: fields
  into the JSON stream through a BGP-LS attribute, and whole events into the
  text stream through its hostname, its software version or a shutdown message.
  The output stayed parseable, so a program reading the API acted on data no
  peer had sent. BGP-LS did not need to be negotiated. 5.0.11 closed the JSON
  hostname, software version and NOTIFICATION cases only. Upgrade if any
  process reads the API.

• Compatibility: three BGP-LS fields of the JSON API change.
  link-identifiers and sr-adj-lan-sids were always empty and now carry what
  the peer sent. local-te-router-ids was published twice for a router
  announcing an IPv4 and an IPv6 TE Router ID, and a JSON parser keeps only the
  second, so the IPv4 address was lost; it is published once now, holding both.
  remote-te-router-id and sr-adj have the same fault and are left alone,
  since fixing them changes their type. 6.0 renames and fixes those two.

• Compatibility: a message of an unknown type is refused with NOTIFICATION
  1/3 Bad Message Type, where 5.0.12 sent 1/0 Unspecific (RFC 4271 section
  6.1).

• Compatibility: five kinds of malformed message which 5.0.12 accepted are
  now refused, because it invented the missing data and produced a route or a
  filter the peer had not sent: a FlowSpec rule whose operator announces a
  value it does not carry, a prefix whose mask is longer than its address
  family allows, a labelled route with no bottom of stack bit, an MCAST-VPN
  route announcing more than it carries, and a VPN next hop whose route
  distinguisher is not zero.

• Fix: comparing two attributes ignored their content, so any two BGP-LS
  attributes, prefix SIDs, or large or extended community sets compared as
  equal. ExaBGP does not use that comparison itself, so this only affects code
  using it as a library.

• Fix: a peer could stop ExaBGP with a truncated message, attribute,
  capability, route, BGP-LS TLV or operational message. These are now refused
  with a NOTIFICATION.

• Fix: a peer could stop ExaBGP as it wrote the API stream, dropping every
  session on the machine, with a FlowSpec redirect community, a BGP-LS route of
  an unknown type, an undefined ADD-PATH value or a valid SRv6 TLV.

• Fix: FlowSpec, EVPN, BGP-LS VPN and AIGP routes could produce API output
  which is not valid JSON, so a consumer lost the whole line.

• Fix: a BGP-LS attribute was refused when a reserved flag bit was set, and
  a Multi-Topology identifier with reserved bits set was read as a different
  topology. The RFCs ask for those bits to be ignored. A malformed BGP-LS
  attribute now costs the attribute and not the session (RFC 7752 section 5.3).

• Fix: an IPv6 multicast route could be configured and sent, but a route
  received in that family was refused and the session dropped. A BGP-LS VPN
  route was refused on receipt whatever the peer sent.

• Fix: a twenty byte IPv6 extended community lost its leading zeros when
  printed.

• Fix: a PMSI tunnel attribute whose tunnel identifier is not the expected
  width was refused or silently truncated. It is printed in hexadecimal now.

• Fix: a BGP prefix SID attribute holding a TLV we do not know stopped the
  parser.

• Fix: withdrawing a route could file it in the RIB under a second key, so
  one prefix was held twice.

• Fix: two prefixes with the same address and a different mask had no
  defined order, so the order they were packed into an UPDATE was arbitrary.

• Fix: a backslash at the end of a text, and any \uXXXX escape, stopped
  the configuration parser instead of being reported.

• Fix: the package metadata uses the SPDX license expression of PEP 639 and
  ships LICENCE.txt (#1413). The wheel still installs on Python 3.8; building
  the source distribution now needs 3.9.

• QA: CI runs every test in the tree, and every change is compared against
  5.0.12 before it is committed.