Follow-ups deferred from the REQUEST_SYNC review (#1371):
- SyncTypeFlags.init(rawValue:) now masks to the union of bits that map to a
known message type (derived from the bit↔type table, so it tracks new
types automatically). Phantom bits from a truncated/garbled flags field —
or a type a newer peer added — no longer live in the set as membership no
contains() matches yet toData() re-serializes.
- GossipSyncManager stored each latest announce as (hex-id string, packet)
and diffed announces against the stored string while every other type
recomputed the ID via PacketIdUtil. Collapsed the store to just the packet
and recompute the ID everywhere, removing the latent dual-path divergence.
- Documented the REQUEST_SYNC TLV table and marked fragmentIdFilter (0x06)
with a TODO(v2): it's parsed/re-serialized but never populated or honored
(reserved for incremental fragment sync) — finish or drop, not silent dead
surface.
Adds SyncTypeFlags phantom-bit/round-trip tests and a GossipSyncManager test
that an announce already in the requester's filter is suppressed (guards the
recompute path). Full suite: 1034 tests pass.
Co-authored-by: jack <jackjackbits@users.noreply.github.com>
Co-authored-by: Claude Opus 4.8 <noreply@anthropic.com>
Small encrypted crews (hard cap 16) between public broadcast and 1:1 DMs:
Protocol
- MessageType.groupMessage = 0x25: broadcast packets with a cleartext
16-byte group ID + epoch, ChaCha20-Poly1305 ciphertext (epoch bound as
AEAD AAD), inner Ed25519 sender signature over
"bitchat-group-msg-v1"|groupID|messageID|timestamp|content
- NoisePayloadType.groupInvite = 0x06 / .groupKeyUpdate = 0x07:
creator-signed group state (key, epoch, roster) 1:1 over Noise; signature
over "bitchat-group-v1"|groupID|epoch|key-hash|roster-hash and the Noise
session peer must BE the creator
- SyncTypeFlags bit 10 (groupMessage): variable-length LE bitfield widens
1 -> 2 bytes inside the length-prefixed REQUEST_SYNC TLV; old clients
ignore unknown bits and answer with types they know
- PeerCapabilities.localSupported now advertises .groups
Storage
- GroupStore: symmetric keys in the keychain, roster/name/epoch as
protected JSON in Application Support; wiped in panicClearAllData()
Behavior
- Non-members relay 0x25 like any broadcast but cannot read it; group
messages join gossip-sync backfill with the public-message window
- Receivers drop wrong-epoch envelopes, bad sender signatures, and
senders missing from the creator-signed roster
- Fire-and-flood delivery (no per-member acks in v1)
UI
- Groups open as chat windows through the private-chat sheet (virtual
"group_" peer IDs); groups section in the people sheet; /group
create/invite/remove/leave/list commands; invitees get a system message
+ notification and the group appears in their people sheet
Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>
Part A — source-route origination policy:
- Gate route application (BLESourceRouteOriginationPolicy): only packets we
author, directed at a single peer, with TTL headroom, whose recipient is
not directly connected. Relays no longer attach routes to (and re-sign)
packets they merely forward.
- Version-gate paths: MeshTopologyTracker records the highest protocol
version observed per peer; BFS routes require every intermediate hop and
the recipient to be v2-observed, capped at 4 intermediate hops.
- Degrade on failure: BLESourceRouteFailureCache marks a routed send that
sees no inbound traffic from the recipient within 10s as failed and floods
for 60s before retrying routes.
Part B — REQUEST_SYNC fragmentIdFilter (TLV 0x06):
- Requester: BLEFragmentAssemblyBuffer reports stalled broadcast
reassemblies (no new fragment for 5s, retried at most every 10s); the
maintenance pass sends a types=fragment REQUEST_SYNC naming the stalled
8-byte fragment stream IDs to each connected peer.
- Responder: GossipSyncManager restricts the fragment diff to exactly the
named streams, bypassing the since-cursor while the GCS filter still
excludes pieces the requester holds; RSR/TTL-0/rate-limit semantics
unchanged and REQUEST_SYNC stays link-local.
- Bounds: at most 60 IDs per request (60*17-1 = 1019 bytes <= the 1024-byte
decoder cap); oversized 0x06 values are ignored, not fatal.
Docs: SOURCE_ROUTING.md gains the iOS origination policy (§8);
REQUEST_SYNC_MANAGER.md documents 0x05/0x06 as implemented.
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>
jack