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jackandClaude Fable 5
e4b3cff5fa
BLE stays the control plane: a sender with a queued file > 64 KiB to a directly connected peer advertising the wifiBulk capability sends a bulkTransferOffer (0x04) inside the established Noise session — transferID, file size, payload SHA-256, a fresh 32-byte token, and a random per-transfer Bonjour instance name. The receiver answers bulkTransferResponse (0x05) with its own token half, then both sides meet on a per-transfer _bitchat-bulk._tcp channel over peer-to-peer Wi-Fi (AWDL). The TCP stream is secured independently of TLS: both tokens traveled inside Noise, so only the two peers can derive the ChaChaPoly channel key (HKDF-SHA256, domain "bitchat-bulk-v1", transferID as salt). Frames are length-prefixed sealed boxes with structured direction+counter nonces; the first frame must prove knowledge of the key or the client is disconnected, and the final hash is verified against the offer before delivery. Decline, timeout, or any mid-transfer error falls back to BLE fragmentation exactly once, driving the same TransferProgressManager stream so the UI is unchanged. Wi-Fi-negotiated transfers may carry up to 8 MiB (new FileTransferLimits.maxWifiBulkPayloadBytes, enforced by the receiver from the accepted offer); the BLE path keeps its existing caps. Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>
Test Harness Guide
This test suite uses an in-memory networking harness to make end-to-end and integration tests deterministic, fast, and race-free without touching production code.
In-Memory Bus
- File:
bitchatTests/Mocks/MockBLEService.swift - Registry/Adjacency: Global
registrymapspeerIDto aMockBLEServiceinstance;adjacencyrecords simulated links between peers. - Setup: Call
MockBLEService.resetTestBus()insetUp()to clear state between tests. - Topology: Use
simulateConnectedPeer(_:)andsimulateDisconnectedPeer(_:)to add/remove links.connectFullMesh()helpers in tests build larger topologies. - Handlers: Tests can observe data via
messageDeliveryHandler(decodedBitchatMessage) andpacketDeliveryHandler(rawBitchatPacket). - De‑duplication: A thread-safe
seenMessageIDsprevents duplicate deliveries during flooding/relays.
Broadcast Flooding
- Flag:
MockBLEService.autoFloodEnabled - Intent: When
true, public broadcasts propagate across the entire connected component (ignores TTL for reach) while still de‑duping to prevent loops. - Usage: Enabled in Integration tests (
setUp) to simulate large-network broadcast; disabled in E2E tests to keep routing explicit and verify TTL behavior (seePublicChatE2ETests.testZeroTTLNotRelayed).
Rehandshake Flow (Noise)
- Why: The legacy NACK recovery path was removed; recovery now relies on Noise session rehandshake after decrypt failure or desync.
- Manager:
NoiseSessionManagermanages per-peer sessions. - Pattern: On decrypt failure, proactively clear the local session and re-initiate a handshake. The peer accepts and replaces their session.
- Test:
IntegrationTests.testRehandshakeAfterDecryptionFailure- Corrupts ciphertext to induce a decrypt error.
- Calls
removeSession(for:)on the initiator’s manager beforeinitiateHandshake(with:)to avoidalreadyEstablished. - Verifies encrypt/decrypt succeeds post-rehandshake.
Tips
- Determinism: Add small async delays only where handler installation/topology changes could race the first send.
- Scoping: Keep
autoFloodEnabledtoggled only within Integration tests; always reset intearDown()to avoid cross-test contamination. - Direct vs Relay: Private messages target a specific peer when adjacent; otherwise they are surfaced to neighbors for relay and, if known, also delivered to the target.
Quick Start
- Create nodes and connect them:
let svc = MockBLEService(); svc.myPeerID = "PEER1"svc.simulateConnectedPeer("PEER2")
- Observe messages:
svc.messageDeliveryHandler = { msg in /* asserts */ }
- Enable broadcast flooding for Integration suites only:
MockBLEService.autoFloodEnabled = true