New MessageType 0x23 carries TLV-encoded board posts and tombstones,
self-signed with the author's Ed25519 key ("bitchat-board-v1" /
"bitchat-board-del-v1" domains) so notices verify without the author
present. BoardStore persists raw signed packets under Application
Support/board/ (200 posts, 5 per author, oldest evicted; expiry sweep;
tombstones retained until the deleted post's original expiry) and is
wiped on panic.
Board packets join gossip sync as bit 8 of the existing variable-length
types bitfield (a second byte old decoders already accept and ignore),
with a 60s round and its own capacity, served straight from the board
store so retention has one owner. Posts relay like broadcasts; urgent
posts get the announce-class TTL cap.
UI: a pin button in the header opens the board for the current channel
(geohash board, or mesh-local board), with urgent-pinned newest-first
listing, compose with urgent toggle and 1/3/7-day expiry, and
swipe-delete on own posts. Geohash posts also publish one-way as
Nostr kind-1 location notes when relays are reachable.
Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>
* Harden REQUEST_SYNC and stop gossip-sync re-send loops
Two fixes from an end-to-end review of the sync path:
Efficiency: the GCS filter (400B, p=7) covers ~355 packet IDs, but stores
hold up to 1000 messages + 600 fragments + 200 files. Once a mesh
accumulates more than the filter can cover, responders re-sent the entire
older tail to every requester every round — ~120KB per pair per 30s during
file transfers, dropped by dedup after the airtime was already burned.
Requesters now stamp the dormant sinceTimestamp TLV with the oldest
timestamp their filter covers, and responders skip older packets (announces
exempt: they carry the signing keys needed to verify everything else).
Periodic sync also sends one request per type schedule instead of a union
filter, so fragment floods can't crowd messages out of the filter budget.
Security: a ~40-byte unsigned REQUEST_SYNC with an empty filter could elicit
a full store replay (~900KB) — an unauthenticated >10,000x amplification
vector, repeatable in a tight loop and relayable with crafted TTL to fan the
drain out of every reachable node. Requests now require ttl == 0, a valid
signature from the claimed sender's announced signing key, and a matching
link binding; REQUEST_SYNC is never relayed regardless of TTL; and responses
are rate-limited per peer (8 per 30s sliding window, ~3x the legitimate
cadence).
Cross-platform: verified against bitchat-android — it signs REQUEST_SYNC and
sends SYNC_TTL_HOPS = 0, so both gates hold; it neither sends nor honors
sinceTimestamp yet, so mixed pairs keep today's behavior with no regression.
Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>
* Address Codex review: enforce no-relay on route path, exact since-cursor
Two P2 findings from Codex on the REQUEST_SYNC hardening:
- Route-forwarding bypass: handleRequestSync's early return for a rejected
(nonzero-TTL / unsigned) request still fell through to
forwardAlongRouteIfNeeded, which relays any routed packet with ttl > 1
regardless of type. The no-relay invariant was only enforced on the flood
path. BLERouteForwardingPolicy now suppresses REQUEST_SYNC outright, so a
crafted request with a route and TTL headroom can't be forwarded to the
next hop either.
- Inexact since-cursor: GCSFilter.buildFilter trimmed by hash order when the
encoding overflowed the byte budget, so the cursor (computed from the
untrimmed prefix) could claim coverage of timestamps whose packets were
dropped from the filter — re-sending exactly those every round. buildFilter
now trims from the input tail (oldest, since candidates are newest-first)
and reports includedCount; the cursor is derived from that, so the covered
set is always a contiguous newest-prefix and the cursor is exact.
Adds GCSFilter includedCount coverage (full vs trimmed), a route-forwarding
test for REQUEST_SYNC, and makes the truncated-cursor test robust to trim
variance. Full suite: 1029 tests pass.
Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>
---------
Co-authored-by: jack <jackjackbits@users.noreply.github.com>
Co-authored-by: Claude Opus 4.8 <noreply@anthropic.com>
