Prevent malicious peers from forging events attributed to users on other
instances. Every relay event processor now verifies the acting user's
homeInstance (from payload) matches X-Federation-Origin (from HMAC-verified
header) via verifyAttribution(), normalized to bare domain.
- Add verifyAttribution() helper using extractDomain normalization
- Guard all 13 event processors before any user resolution or DB writes
- Add homeInstance to FederationRelayReaction type + outbound payloads
- Replace unnormalized string equality in friend handlers
- Log mismatched values on rejection for debugging
Sliding-window rate limiter (30 req/min per peer origin) on POST
/api/federation/relay, matching the existing accept endpoint pattern.
Returns 429 when exceeded — outbox workers retry with backoff. Check
runs before HMAC verification to avoid wasted computation on floods.
Extract processRelayEvents() from the relay HTTP handler and call it
directly in runInitialSyncForNewPeers(), eliminating the HTTP round-trip
through public DNS that failed on networks without hairpin NAT.
Comprehensive internal document covering the complete lifecycle of
federated DMs: data model, relay pipeline, event processing, bootstrap
path, local-only broadcast principle, system messages, and all known
pitfalls with their fixes.
Jannis Braun