* feat: Implement Request Sync Manager (V2 Sync) - Add RequestSyncManager to track and attribute sync requests - Update BitchatPacket and BinaryProtocol to support IS_RSR flag (0x10) - Update RequestSyncPacket with new TLV fields (sinceTimestamp, fragmentIdFilter) - Update GossipSyncManager to use unicast sync requests and mark responses as RSR - Update BLEService to enforce timestamp validation for normal packets and exempt valid RSRs - Add documentation for the new sync manager mechanism * fix: Resolve compilation errors in V2 Sync implementation - Remove duplicate restartGossipManager in BLEService - Add missing TransportConfig constants for sync - Add 'sync' log category to BitLogger - Add missing BitLogger import in GossipSyncManager * fix: Update tests for V2 Sync changes - Add requestSyncManager parameter to GossipSyncManager init in tests - Implement getConnectedPeers stub in RecordingDelegate - Remove unused variable warning in SubscriptionRateLimitTests --------- Co-authored-by: a1denvalu3 <> Co-authored-by: jack <212554440+jackjackbits@users.noreply.github.com>
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Request Sync Manager & V2 Packet Updates
This document details the implementation of the Request Sync Manager and updates to the V2 packet structure to improve synchronization security and attribution on iOS, mirroring the Android implementation.
Overview
The goal of these changes is to make the request sync functionality "less blind". Previously, sync requests were broadcast, and responses were accepted without strict attribution or timestamp validation (to allow syncing old messages). This opened up potential spoofing vectors and prevented us from enforcing timestamp checks on normal traffic.
The new implementation introduces a RequestSyncManager to track outgoing sync requests and attributes incoming responses (RSR - Request-Sync Response) to specific peers. This allows us to:
- Enforce Timestamp Validation: Normal packets now require timestamps to be within 2 minutes of the local clock.
- Exempt Solicited Sync Responses: Packets marked as RSR are exempt from timestamp validation only if they correspond to a valid, pending sync request sent to that specific peer.
- Prevent Unsolicited Sync Floods: Unsolicited RSR packets are rejected.
Protocol Changes
Binary Protocol Updates
- New Flag:
IS_RSR(0x10) added to the packet header flags. - BitchatPacket: Updated to include
isRSR: Boolfield. - Encoding/Decoding: Updated
BinaryProtocolto handle the new flag.
Request Sync Payload
The REQUEST_SYNC packet payload (TLV encoded) has been updated to include:
- Future Filters:
sinceTimestamp(Type 0x05): To request packets since a certain time (UInt64 big-endian).fragmentIdFilter(Type 0x06): To request specific fragments (UTF-8 string).
Architecture
RequestSyncManager
A new component (Sync/RequestSyncManager.swift) responsible for:
- Tracking: Stores
peerID -> timestampmappings for pending sync requests. - Validation:
isValidResponse(from: PeerID, isRSR: Bool)checks if an incoming RSR packet matches a pending request within the 30-second window. - Cleanup: Periodically removes expired requests.
GossipSyncManager Updates
- Unicast Sync: Instead of blind broadcasting, the periodic sync task now iterates over connected peers and sends unicast
REQUEST_SYNCpackets. - Registration: Before sending, requests are registered with
RequestSyncManager. - Response Marking: When responding to a
REQUEST_SYNC, generated packets (Announce/Message) are explicitly marked withisRSR = true(andttl = 0).
BLEService (Security Manager) Updates
- Timestamp Enforcement: Checks
abs(now - packetTimestamp) < 2 minutesfor standard packets. - Conditional Exemption: If
packet.isRSRis true (or packet is a legacy TTL=0 response), it queriesRequestSyncManager.- Valid: If solicited, timestamp check is skipped (allowing historical data sync).
- Invalid: If unsolicited or timed out, the packet is rejected.
Usage
These changes are integrated into BLEService and GossipSyncManager. No external API changes are required for clients, but all peers must be updated to support the new IS_RSR flag and protocol logic to participate in the secure sync process.