Fix ghost peers and stale messages from gossip sync (#766)

Problem:
- Ghost peers from yesterday appeared on app restart
- Old messages resurfaced after restarting
- Peers running 24+ hours synced stale data to restarting peers

Root causes:
1. GossipSyncManager stored packets indefinitely (no time limit)
2. handleAnnounce/handleMessage had no timestamp validation
3. Relayed announces from other peers could be arbitrarily old

Solution (defense in depth):
- Added 15-minute age window to GossipSyncManager config
- Gossip storage rejects expired packets at ingestion
- Gossip sync responses filter out expired packets
- GCS payload building excludes expired packets
- Periodic cleanup removes expired announcements/messages
- handleAnnounce rejects stale announces before processing
- handleMessage rejects stale broadcast messages before processing

This prevents ghost peers from appearing on restart and ensures
only recent mesh state is synchronized between peers.

Co-authored-by: jack <jackjackbits@users.noreply.github.com>

bitchat/Services/BLEService.swift

@@ -2415,7 +2415,20 @@ extension BLEService {
         if peerID == myPeerID {
             return
         }
-        
+
+        // Reject stale announces to prevent ghost peers from appearing
+        // Use same 15-minute window as gossip sync (900 seconds)
+        let maxAnnounceAgeSeconds: TimeInterval = 900
+        let nowMs = UInt64(Date().timeIntervalSince1970 * 1000)
+        let ageThresholdMs = UInt64(maxAnnounceAgeSeconds * 1000)
+        if nowMs >= ageThresholdMs {
+            let cutoffMs = nowMs - ageThresholdMs
+            if packet.timestamp < cutoffMs {
+                SecureLogger.debug("⏰ Ignoring stale announce from \(peerID.prefix(8))… (age: \(Double(nowMs - packet.timestamp) / 1000.0)s)", category: .session)
+                return
+            }
+        }
+
         // Suppress announce logs to reduce noise
 
         // Precompute signature verification outside barrier to reduce contention
@@ -2591,6 +2604,26 @@ extension BLEService {
         // the sync path without re-processing regular relayed copies.
         if peerID == myPeerID && packet.ttl != 0 { return }
 
+        // Reject stale broadcast messages to prevent old messages from appearing
+        // Use same 15-minute window as gossip sync (900 seconds)
+        // Check if this is a broadcast message (recipient is all 0xFF or nil)
+        let isBroadcast: Bool = {
+            guard let r = packet.recipientID else { return true }
+            return r.count == 8 && r.allSatisfy { $0 == 0xFF }
+        }()
+        if isBroadcast {
+            let maxMessageAgeSeconds: TimeInterval = 900
+            let nowMs = UInt64(Date().timeIntervalSince1970 * 1000)
+            let ageThresholdMs = UInt64(maxMessageAgeSeconds * 1000)
+            if nowMs >= ageThresholdMs {
+                let cutoffMs = nowMs - ageThresholdMs
+                if packet.timestamp < cutoffMs {
+                    SecureLogger.debug("⏰ Ignoring stale broadcast message from \(peerID.prefix(8))… (age: \(Double(nowMs - packet.timestamp) / 1000.0)s)", category: .session)
+                    return
+                }
+            }
+        }
+
         var accepted = false
         var senderNickname: String = ""
 

bitchat/Sync/GossipSyncManager.swift

@@ -12,6 +12,7 @@ final class GossipSyncManager {
         var seenCapacity: Int = 1000          // max packets per sync (cap across types)
         var gcsMaxBytes: Int = 400           // filter size budget (128..1024)
         var gcsTargetFpr: Double = 0.01      // 1%
+        var maxMessageAgeSeconds: TimeInterval = 900  // 15 min - discard older messages
     }
 
     private let myPeerID: PeerID
@@ -36,7 +37,10 @@ final class GossipSyncManager {
         stop()
         let timer = DispatchSource.makeTimerSource(queue: queue)
         timer.schedule(deadline: .now() + 30.0, repeating: 30.0, leeway: .seconds(1))
-        timer.setEventHandler { [weak self] in self?.sendRequestSync() }
+        timer.setEventHandler { [weak self] in
+            self?.cleanupExpiredMessages()
+            self?.sendRequestSync()
+        }
         timer.resume()
         periodicTimer = timer
     }
@@ -57,6 +61,18 @@ final class GossipSyncManager {
         }
     }
 
+    // Helper to check if a packet is within the age threshold
+    private func isPacketFresh(_ packet: BitchatPacket) -> Bool {
+        let nowMs = UInt64(Date().timeIntervalSince1970 * 1000)
+        let ageThresholdMs = UInt64(config.maxMessageAgeSeconds * 1000)
+
+        // If current time is less than threshold, accept all (handle clock issues gracefully)
+        guard nowMs >= ageThresholdMs else { return true }
+
+        let cutoffMs = nowMs - ageThresholdMs
+        return packet.timestamp >= cutoffMs
+    }
+
     private func _onPublicPacketSeen(_ packet: BitchatPacket) {
         let mt = MessageType(rawValue: packet.type)
         let isBroadcastRecipient: Bool = {
@@ -67,6 +83,9 @@ final class GossipSyncManager {
         let isAnnounce = (mt == .announce)
         guard isBroadcastMessage || isAnnounce else { return }
 
+        // Reject expired packets to prevent ghost peers and old messages
+        guard isPacketFresh(packet) else { return }
+
         let idHex = PacketIdUtil.computeId(packet).hexEncodedString()
 
         if isBroadcastMessage {
@@ -137,9 +156,10 @@ final class GossipSyncManager {
             return GCSFilter.contains(sortedValues: sorted, candidate: bucket)
         }
 
-        // 1) Announcements: send latest per peer if requester lacks them
+        // 1) Announcements: send latest per peer if requester lacks them (and not expired)
         for (_, pair) in latestAnnouncementByPeer {
             let (idHex, pkt) = pair
+            guard isPacketFresh(pkt) else { continue }
             let idBytes = Data(hexString: idHex) ?? Data()
             if !mightContain(idBytes) {
                 var toSend = pkt
@@ -148,9 +168,10 @@ final class GossipSyncManager {
             }
         }
 
-        // 2) Broadcast messages: send all missing
+        // 2) Broadcast messages: send all missing (and not expired)
         let toSendMsgs = messageOrder.compactMap { messages[$0] }
         for pkt in toSendMsgs {
+            guard isPacketFresh(pkt) else { continue }
             let idBytes = PacketIdUtil.computeId(pkt)
             if !mightContain(idBytes) {
                 var toSend = pkt
@@ -162,11 +183,19 @@ final class GossipSyncManager {
 
     // Build REQUEST_SYNC payload using current candidates and GCS params
     private func buildGcsPayload() -> Data {
-        // Collect candidates: latest announce per peer + broadcast messages
+        // Collect candidates: latest announce per peer + broadcast messages (only fresh)
         var candidates: [BitchatPacket] = []
         candidates.reserveCapacity(latestAnnouncementByPeer.count + messageOrder.count)
-        for (_, pair) in latestAnnouncementByPeer { candidates.append(pair.packet) }
-        for id in messageOrder { if let p = messages[id] { candidates.append(p) } }
+        for (_, pair) in latestAnnouncementByPeer {
+            if isPacketFresh(pair.packet) {
+                candidates.append(pair.packet)
+            }
+        }
+        for id in messageOrder {
+            if let p = messages[id], isPacketFresh(p) {
+                candidates.append(p)
+            }
+        }
         // Sort by timestamp desc
         candidates.sort { $0.timestamp > $1.timestamp }
 
@@ -184,6 +213,23 @@ final class GossipSyncManager {
         return req.encode()
     }
 
+    // Periodic cleanup of expired messages and announcements
+    private func cleanupExpiredMessages() {
+        // Remove expired announcements
+        latestAnnouncementByPeer = latestAnnouncementByPeer.filter { _, pair in
+            isPacketFresh(pair.packet)
+        }
+
+        // Remove expired messages
+        let expiredMessageIds = messages.compactMap { id, pkt in
+            isPacketFresh(pkt) ? nil : id
+        }
+        for id in expiredMessageIds {
+            messages.removeValue(forKey: id)
+            messageOrder.removeAll { $0 == id }
+        }
+    }
+
     // Explicit removal hook for LEAVE/stale peer
     func removeAnnouncementForPeer(_ peerID: PeerID) {
         queue.async { [weak self] in