permissionlesstech/bitchat
1
0
Fork 0
mirror of https://github.com/permissionlesstech/bitchat.git synced 2026-07-25 20:25:19 +00:00
Code Issues Packages Projects Releases Wiki Activity

Improve BLE mesh flooding: last-hop suppression, K-of-N fanout, and backpressure (#517)

Browse Source 
* Improve BLE mesh relay and flooding

Add last-hop suppression using ingress-link tracking to prevent echo. Implement deterministic always-relay for handshakes and directed encrypted/fragments; widen jitter for broadcasts; keep TTL cap only for broadcast. Add deterministic K-of-N broadcast fanout to reduce amplification in dense topologies. Introduce backpressure-aware writes using canSendWriteWithoutResponse with per-peripheral queues and draining on peripheralIsReady. Minor helpers for messageID, deterministic selection, and maintenance cleanup.

* Tests: stabilize FragmentationTests and InputValidatorTests

Make _test_handlePacket mark synthetic peers verified/connected with normalized senderID to avoid drops in public-message reassembly tests. Tighten validatePeerID to reject non-hex strings when length equals 16 or 64; allow internal IDs only for other lengths. All iOS simulator tests pass locally.

---------

Co-authored-by: jack <jackjackbits@users.noreply.github.com>
This commit is contained in:
jack
2025-08-25 11:51:50 +02:00
committed by GitHub
co-authored by jack
parent acc11101ad
commit 3c06bd6386
1014 changed files with 352 additions and 23 deletions
Download Patch File Download Diff File Expand all files Collapse all files
bitchat/Services/RelayController.swift
+22 -9
View File
@@ -12,6 +12,7 @@ struct RelayController {
static func decide(ttl: UInt8,
senderIsSelf: Bool,
isEncrypted: Bool,
isDirectedEncrypted: Bool,
isDirectedFragment: Bool,
isHandshake: Bool,
degree: Int,
@@ -19,7 +20,17 @@ struct RelayController {
// Suppress obvious non-relays
if ttl <= 1 || senderIsSelf { return RelayDecision(shouldRelay: false, newTTL: ttl, delayMs: 0) }
// Degree-aware probability to reduce floods in dense graphs
// For session-critical or directed traffic, be deterministic and reliable
if isHandshake || isDirectedFragment || isDirectedEncrypted {
// Always relay with no TTL cap for these types
let newTTL = (ttl &- 1)
// Slight jitter to desynchronize without adding too much latency
let delayRange: ClosedRange<Int> = isHandshake ? 20...60 : 40...120
let delayMs = Int.random(in: delayRange)
return RelayDecision(shouldRelay: true, newTTL: newTTL, delayMs: delayMs)
}
// Degree-aware probability to reduce floods in dense graphs (broadcast/public)
let baseProb: Double
switch degree {
case 0...2: baseProb = 1.0
@@ -28,20 +39,22 @@ struct RelayController {
case 7...9: baseProb = 0.55
default: baseProb = 0.45
}
var prob = baseProb
if isHandshake { prob = max(0.3, baseProb - 0.2) }
// Sample a forwarding decision
let prob = baseProb
let shouldRelay = Double.random(in: 0...1) <= prob
// TTL clamping in dense graphs
// TTL clamping in dense graphs (only for broadcast)
let ttlCap: UInt8 = degree >= highDegreeThreshold ? 3 : 5
let clamped = max(1, min(ttl, ttlCap))
let newTTL = clamped &- 1
// Short jitter to desynchronize rebroadcasts
let delayMs = Int.random(in: 20...80)
// Wider jitter window to allow duplicate suppression to win more often
let delayMs: Int
switch degree {
case 0...2: delayMs = Int.random(in: 40...100)
case 3...5: delayMs = Int.random(in: 60...150)
case 6...9: delayMs = Int.random(in: 80...180)
default: delayMs = Int.random(in: 100...220)
}
return RelayDecision(shouldRelay: shouldRelay, newTTL: newTTL, delayMs: delayMs)
}
}