Rayhaan JaufeerallyandClaude Fable 5.1
6197a7ad74
Any malformed UPDATE used to reset the session, withdrawing every route
learned over it. One bad attribute, typically originated ASes away and
passed on by a peer that did not look at it, could take down a session
carrying a full table.
UpdateMessage::decode now applies RFC 7606 and returns the UPDATE as it is
to be acted on, plus a report of what was wrong:
- Treat-as-withdraw: a malformed or misflagged attribute, a missing
mandatory one, or an attribute that overruns the attribute list. The
routes the UPDATE announced (in the body and in MP_REACH_NLRI) are
withdrawn.
- Attribute discard: malformed ATOMIC_AGGREGATE, AGGREGATOR, AS4_PATH and
AS4_AGGREGATOR; an attribute sent twice (the first is kept); LOCAL_PREF,
ORIGINATOR_ID and CLUSTER_LIST from an external peer; AS4_PATH between
four-octet speakers.
- Session reset remains where the prefixes are in doubt: the lengths that
frame the message, an unreadable prefix, a malformed or repeated
MP_REACH_NLRI or MP_UNREACH_NLRI, an unrecognised well-known attribute.
Each now sends its own subcode instead of always Malformed Attribute
List.
The session logs each handled error and counts it in
bgp_update_errors_total{handling}. The parser context says whether the
peer is internal (replacing a field nothing read).
Stricter than before, because the checks did not exist:
- An announcement must carry ORIGIN and AS_PATH, NEXT_HOP for routes in the
body, and LOCAL_PREF from an internal peer.
- An AS_PATH segment must be an AS_SET or AS_SEQUENCE and not empty.
- An attribute value must be used up entirely by its parser; a NEXT_HOP of
six octets, say, was accepted before.
Bugs found on the way: we sent ATOMIC_AGGREGATE flagged optional and
AGGREGATOR flagged non-transitive. The flags now come from one table used
for both writing and checking.
Co-Authored-By: Claude Fable 5.1 <noreply@anthropic.com>
BGP
The bgp crate is an implementation of the Border Gateway Protocol, which is used to exchange routing and control plane information between Autonomous Systems.
The aim of this project is to provide a modern, high performance, secure, programmatic and customizable software package that can be useful to network operators, researchers, and people interested in Internet.
Current status.
The project is currently being rewritten from scratch to be more modular and maintainable, as well as to fix deeper issues with the previous implementation.
⚠️ Warning: This is currently a work in progress and not ready for use.
🛣️ Roadmap to v1.0
We aim for the 1.0 release to be functional and stable to operate peering sessions, and to install routes in the Linux Kernel.
- ☐ Implement basic parsers for the fundamental types required
- ✅ Path Attributes from RFC4271
- ✅ Open message
- ✅ Capabilities from RFC4271
- ✅ Update message
- ☐ Notification message
- ✅ Implement scaffolding required to start and configure a server
- ✅ Implement connection logic to establish sessions with peers (passive and active)
- ✅ Routes originated from the configuration, with communities, announced to all peers
- ✅ Read-only HTTP API, status page and Prometheus metrics
- ☐ Implement an efficient data structure for storing prefixes (e.g. Poptrie)
- ☐ Filtering for peer RIB in / out
- ☐ Main / auxiliary RIBs for exchanging routes between peers
Development
CI runs these three on every push, and fails on any warning:
cargo fmt --all -- --check
cargo clippy --workspace --all-targets -- -D warnings
cargo test --workspace
Lints are configured once, under [workspace.lints] in the root Cargo.toml.
unsafe code is forbidden throughout.
cargo test includes property tests: generated messages must survive being
written and read back, and no input, however damaged, may make a parser
panic. They take about a second; for a longer hunt:
PROPTEST_CASES=1000000 cargo test --release -p bgp-packet --test properties
Coverage-guided fuzz targets for the same parsers are in fuzz/; see
fuzz/README.md. CI runs each of them for a minute.
License
Apache License 2.0; see LICENSE.