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2 Commits
| Author | SHA1 | Date | |
|---|---|---|---|
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0e9a1225fc | ||
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afe7804a9b |
@@ -6,98 +6,411 @@ Complete TCP/UDP/DNS packet capture implementation using gVisor netstack for And
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Provides full packet capture for mobile VPN applications:
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- **DNS filtering** through ControlD proxy
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- **TCP forwarding** for all TCP traffic
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- **UDP forwarding** with session tracking
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- **Socket protection** to prevent routing loops
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- **IP whitelisting** - only allows connections to DNS-resolved IPs
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- **TCP forwarding** for all TCP traffic (with whitelist enforcement)
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- **UDP forwarding** with session tracking (with whitelist enforcement)
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- **QUIC blocking** for better content filtering
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## Architecture
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## Master Architecture Diagram
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```
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Mobile Apps → VPN TUN Interface → PacketHandler → gVisor Netstack
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┌──────────────────────────────────────────────────────────────────────────────┐
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│ MOBILE APP (Android/iOS) │
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│ │
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│ ┌─────────────────────────────────────────────────────────────────────┐ │
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│ │ VPN Configuration │ │
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│ │ │ │
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│ │ Android: iOS: │ │
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│ │ ┌──────────────────────┐ ┌──────────────────────┐ │ │
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│ │ │ Builder() │ │ NEIPv4Settings │ │ │
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│ │ │ .addAddress( │ │ addresses: [ │ │ │
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│ │ │ "10.0.0.2", 24) │ │ "10.0.0.2"] │ │ │
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│ │ │ .addDnsServer( │ │ │ │ │
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│ │ │ "10.0.0.1") │ │ NEDNSSettings │ │ │
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│ │ │ │ │ servers: [ │ │ │
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│ │ │ FIREWALL MODE: │ │ "10.0.0.1"] │ │ │
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│ │ │ .addRoute( │ │ │ │ │
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│ │ │ "0.0.0.0", 0) │ │ FIREWALL MODE: │ │ │
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│ │ │ │ │ includedRoutes: │ │ │
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│ │ │ DNS-ONLY MODE: │ │ [.default()] │ │ │
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│ │ │ .addRoute( │ │ │ │ │
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│ │ │ "10.0.0.1", 32) │ │ DNS-ONLY MODE: │ │ │
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│ │ │ │ │ includedRoutes: │ │ │
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│ │ │ .addDisallowedApp( │ │ [10.0.0.1/32] │ │ │
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│ │ │ "com.controld.*") │ │ │ │ │
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│ │ └──────────────────────┘ └──────────────────────┘ │ │
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│ │ │ │
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│ │ Result: │ │
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│ │ • Firewall: ALL traffic → VPN │ │
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│ │ • DNS-only: ONLY DNS (port 53) → VPN │ │
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│ └─────────────────────────────────────────────────────────────────────┘ │
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└──────────────────────────┬───────────────────────────────────────────────────┘
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│ Packets
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↓
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├─→ DNS Filter (Port 53)
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│ └─→ ControlD DNS Proxy
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├─→ TCP Forwarder
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│ └─→ net.Dial("tcp") + protect(fd)
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└─→ UDP Forwarder
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└─→ net.Dial("udp") + protect(fd)
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┌──────────────────────────────────────────────────────────────────────────────┐
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│ GOMOBILE LIBRARY (ctrld_library) │
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│ │
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│ ┌─────────────────────────────────────────────────────────────────────┐ │
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│ │ PacketCaptureController.StartWithPacketCapture() │ │
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│ │ │ │
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│ │ Parameters: │ │
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│ │ • tunAddress: "10.0.0.1" (gateway) │ │
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│ │ • deviceAddress: "10.0.0.2" (device IP) │ │
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│ │ • dnsProxyAddress: "127.0.0.1:5354" (Android) / ":53" (iOS) │ │
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│ │ • cdUID, upstreamProto, etc. │ │
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│ └──────────────────────────┬──────────────────────────────────────────┘ │
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│ │ │
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│ ↓ │
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│ ┌──────────────────────────────────────────────────────────────────┐ │
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│ │ NETSTACK CONTROLLER │ │
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│ │ │ │
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│ │ Components: │ │
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│ │ ┌────────────────┐ ┌─────────────┐ ┌──────────────┐ │ │
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│ │ │ DNS Filter │ │ IP Tracker │ │ TCP Forwarder│ │ │
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│ │ │ (port 53) │ │ (5min TTL) │ │ (firewall) │ │ │
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│ │ └────────────────┘ └─────────────┘ └──────────────┘ │ │
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│ │ ┌────────────────┐ │ │
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│ │ │ UDP Forwarder │ │ │
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│ │ │ (firewall) │ │ │
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│ │ └────────────────┘ │ │
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│ └──────────────────────────┬───────────────────────────────────────┘ │
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└─────────────────────────────┼───────────────────────────────────────────────┘
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│
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↓
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Real Network (Protected Sockets)
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```
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┌──────────────────────────────────────────────────────────────────────────────┐
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│ PACKET FLOW DETAILS │
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│ │
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│ INCOMING PACKET (from TUN) │
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│ │ │
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│ ├──→ Is DNS? (port 53) │
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│ │ ├─ YES → DNS Filter │
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│ │ │ ├─→ Forward to ControlD DNS Proxy │
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│ │ │ │ (127.0.0.1:5354 or 127.0.0.1:53) │
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│ │ │ ├─→ Get DNS response │
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│ │ │ ├─→ Extract A/AAAA records │
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│ │ │ ├─→ TrackIP() for each resolved IP │
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│ │ │ │ • Store: resolvedIPs["93.184.216.34"] = now+5min │
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│ │ │ └─→ Return DNS response to app │
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│ │ │ │
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│ │ └─ NO → Is TCP/UDP? │
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│ │ │ │
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│ │ ├──→ TCP Packet │
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│ │ │ ├─→ Extract destination IP │
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│ │ │ ├─→ Check: ipTracker.IsTracked(destIP) │
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│ │ │ │ ├─ NOT TRACKED → BLOCK │
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│ │ │ │ │ Log: "BLOCKED hardcoded IP" │
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│ │ │ │ │ Return (connection reset) │
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│ │ │ │ │ │
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│ │ │ │ └─ TRACKED → ALLOW │
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│ │ │ │ net.Dial("tcp", destIP) │
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│ │ │ │ Bidirectional copy (app ↔ internet) │
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│ │ │ │ │
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│ │ └──→ UDP Packet │
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│ │ ├─→ Is QUIC? (port 443/80) │
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│ │ │ └─ YES → BLOCK (force TCP fallback) │
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│ │ │ │
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│ │ ├─→ Extract destination IP │
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│ │ ├─→ Check: ipTracker.IsTracked(destIP) │
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│ │ │ ├─ NOT TRACKED → BLOCK │
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│ │ │ │ Log: "BLOCKED hardcoded IP" │
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│ │ │ │ Return (drop packet) │
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│ │ │ │ │
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│ │ │ └─ TRACKED → ALLOW │
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│ │ │ net.Dial("udp", destIP) │
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│ │ │ Forward packets (app ↔ internet) │
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│ │ │ 30s timeout per session │
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│ │ │
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│ IP TRACKER STATE (in-memory map): │
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│ ┌────────────────────────────────────────────────────────────┐ │
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│ │ resolvedIPs map: │ │
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│ │ │ │
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│ │ "93.184.216.34" → expires: 2026-03-20 23:35:00 │ │
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│ │ "2606:2800:220::1" → expires: 2026-03-20 23:36:15 │ │
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│ │ "8.8.8.8" → expires: 2026-03-20 23:37:42 │ │
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│ │ │ │
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│ │ Cleanup: Every 30 seconds, remove expired entries │ │
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│ │ TTL: 5 minutes (configurable) │ │
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│ └────────────────────────────────────────────────────────────┘ │
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│ │
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│ EXAMPLE SCENARIO: │
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│ ─────────────────────────────────────────────────────────────────────── │
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│ │
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│ T=0s: App tries: connect(1.2.3.4:443) │
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│ → IsTracked(1.2.3.4)? NO │
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│ → ❌ BLOCKED │
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│ │
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│ T=1s: App queries: DNS "example.com" │
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│ → Response: A 93.184.216.34 │
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│ → TrackIP(93.184.216.34) with TTL=5min │
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│ │
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│ T=2s: App tries: connect(93.184.216.34:443) │
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│ → IsTracked(93.184.216.34)? YES (expires T+301s) │
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│ → ✅ ALLOWED │
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│ │
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│ T=302s: App tries: connect(93.184.216.34:443) │
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│ → IsTracked(93.184.216.34)? NO (expired) │
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│ → ❌ BLOCKED (must do DNS again) │
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└──────────────────────────────────────────────────────────────────────────────┘
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┌──────────────────────────────────────────────────────────────────────────────┐
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│ MODE COMPARISON (Firewall vs DNS-only) │
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│ │
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│ ┌─────────────────────────────────┬─────────────────────────────────┐ │
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│ │ FIREWALL MODE │ DNS-ONLY MODE │ │
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│ │ (Default Routes Configured) │ (Only DNS Route Configured) │ │
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│ ├─────────────────────────────────┼─────────────────────────────────┤ │
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│ │ Routes (Android): │ Routes (Android): │ │
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│ │ • addRoute("0.0.0.0", 0) │ • addRoute("10.0.0.1", 32) │ │
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│ │ │ │ │
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│ │ Routes (iOS): │ Routes (iOS): │ │
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│ │ • includedRoutes: [.default()] │ • includedRoutes: │ │
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│ │ │ [10.0.0.1/32] │ │
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│ ├─────────────────────────────────┼─────────────────────────────────┤ │
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│ │ Traffic Sent to VPN: │ Traffic Sent to VPN: │ │
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│ │ ✅ DNS (port 53) │ ✅ DNS (port 53) │ │
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│ │ ✅ TCP (all ports) │ ❌ TCP (bypasses VPN) │ │
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│ │ ✅ UDP (all ports) │ ❌ UDP (bypasses VPN) │ │
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│ ├─────────────────────────────────┼─────────────────────────────────┤ │
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│ │ IP Tracker Behavior: │ IP Tracker Behavior: │ │
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│ │ • Tracks DNS-resolved IPs │ • Tracks DNS-resolved IPs │ │
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│ │ • Blocks hardcoded TCP/UDP IPs │ • No TCP/UDP to block │ │
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│ │ • Enforces DNS-first policy │ • N/A (no non-DNS traffic) │ │
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│ ├─────────────────────────────────┼─────────────────────────────────┤ │
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│ │ Use Case: │ Use Case: │ │
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│ │ • Full content filtering │ • DNS filtering only │ │
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│ │ • Block DNS bypass attempts │ • Minimal battery impact │ │
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│ │ • Enforce ControlD policies │ • Fast web browsing │ │
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│ └─────────────────────────────────┴─────────────────────────────────┘ │
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│ │
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│ MODE SWITCHING: │
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│ • Android: VpnController.setFirewallMode(enabled) → recreates VPN │
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│ • iOS: sendProviderMessage("set_firewall_mode") → updates routes │
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│ • Both: No app restart needed │
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└──────────────────────────────────────────────────────────────────────────────┘
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┌──────────────────────────────────────────────────────────────────────────────┐
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│ DETAILED PACKET FLOW (Firewall Mode) │
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│ │
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│ 1. APP MAKES REQUEST │
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│ ─────────────────────────────────────────────────────────────────────── │
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│ App: connect("example.com", 443) │
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│ ↓ │
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│ OS: Perform DNS lookup for "example.com" │
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│ ↓ │
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│ OS: Send DNS query to VPN DNS server (10.0.0.1) │
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│ │
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│ 2. DNS PACKET FLOW │
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│ ─────────────────────────────────────────────────────────────────────── │
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│ [DNS Query Packet: 10.0.0.2:12345 → 10.0.0.1:53] │
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│ ↓ │
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│ TUN Interface → readPacket() │
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│ ↓ │
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│ DNSFilter.ProcessPacket() │
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│ ├─ Detect port 53 (DNS) │
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│ ├─ Extract DNS payload │
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│ ├─ Forward to ControlD DNS proxy (127.0.0.1:5354 or :53) │
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│ │ ↓ │
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│ │ ControlD DNS Proxy │
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│ │ ├─ Apply filtering rules │
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│ │ ├─ Query upstream DNS (DoH/DoT/DoQ) │
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│ │ └─ Return response: A 93.184.216.34 │
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│ │ ↓ │
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│ ├─ Parse DNS response │
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│ ├─ extractAndTrackIPs() │
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│ │ └─ IPTracker.TrackIP(93.184.216.34) │
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│ │ • Store: resolvedIPs["93.184.216.34"] = now + 5min │
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│ ├─ Build DNS response packet │
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│ └─ writePacket() → TUN → App │
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│ │
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│ OS receives DNS response → resolves "example.com" to 93.184.216.34 │
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│ │
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│ 3. TCP CONNECTION FLOW │
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│ ─────────────────────────────────────────────────────────────────────── │
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│ OS: connect(93.184.216.34:443) │
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│ ↓ │
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│ [TCP SYN Packet: 10.0.0.2:54321 → 93.184.216.34:443] │
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│ ↓ │
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│ TUN Interface → readPacket() │
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│ ↓ │
|
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│ gVisor Netstack → TCPForwarder.handleConnection() │
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│ ├─ Extract destination IP: 93.184.216.34 │
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│ ├─ Check internal VPN subnet (10.0.0.0/24)? │
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│ │ └─ NO (skip check) │
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│ ├─ ipTracker.IsTracked(93.184.216.34)? │
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│ │ ├─ Check resolvedIPs map │
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│ │ ├─ Found: expires at T+300s │
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│ │ ├─ Not expired yet │
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│ │ └─ YES ✅ │
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│ ├─ ALLOWED - create upstream connection │
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│ ├─ net.Dial("tcp", "93.184.216.34:443") │
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│ │ ↓ │
|
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│ │ [Real Network Connection] │
|
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│ │ ↓ │
|
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│ └─ Bidirectional copy (TUN ↔ Internet) │
|
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│ │
|
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│ 4. BLOCKED SCENARIO (Hardcoded IP) │
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│ ─────────────────────────────────────────────────────────────────────── │
|
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│ App: connect(1.2.3.4:443) // Hardcoded IP, no DNS! │
|
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│ ↓ │
|
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│ [TCP SYN Packet: 10.0.0.2:54322 → 1.2.3.4:443] │
|
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│ ↓ │
|
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│ TUN Interface → readPacket() │
|
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│ ↓ │
|
||||
│ gVisor Netstack → TCPForwarder.handleConnection() │
|
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│ ├─ Extract destination IP: 1.2.3.4 │
|
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│ ├─ ipTracker.IsTracked(1.2.3.4)? │
|
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│ │ └─ Check resolvedIPs map → NOT FOUND │
|
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│ │ └─ NO ❌ │
|
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│ ├─ BLOCKED │
|
||||
│ ├─ Log: "[TCP] BLOCKED hardcoded IP: 10.0.0.2:54322 → 1.2.3.4:443" │
|
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│ └─ Return (send TCP RST to app) │
|
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│ │
|
||||
│ App receives connection refused/reset │
|
||||
└──────────────────────────────────────────────────────────────────────────────┘
|
||||
|
||||
┌──────────────────────────────────────────────────────────────────────────────┐
|
||||
│ PLATFORM-SPECIFIC DETAILS │
|
||||
│ │
|
||||
│ ANDROID │
|
||||
│ ──────────────────────────────────────────────────────────────────────── │
|
||||
│ • VPN Config: ControlDService.kt │
|
||||
│ • Packet I/O: FileInputStream/FileOutputStream on VPN fd │
|
||||
│ • DNS Proxy: Listens on 0.0.0.0:5354 (connects via 127.0.0.1:5354) │
|
||||
│ • Self-Exclusion: addDisallowedApplication(packageName) │
|
||||
│ • Mode Switch: Recreates VPN interface with new routes │
|
||||
│ • No routing loops: App traffic bypasses VPN │
|
||||
│ │
|
||||
│ IOS │
|
||||
│ ──────────────────────────────────────────────────────────────────────── │
|
||||
│ • VPN Config: PacketTunnelProvider.swift │
|
||||
│ • Packet I/O: NEPacketTunnelFlow (async → blocking via PacketQueue) │
|
||||
│ • DNS Proxy: Listens on 127.0.0.1:53 │
|
||||
│ • Self-Exclusion: Network Extension sockets auto-bypass │
|
||||
│ • Mode Switch: setTunnelNetworkSettings() with new routes │
|
||||
│ • Write Batching: 16 packets per batch, 5ms flush timer │
|
||||
│ • No routing loops: Extension traffic bypasses VPN │
|
||||
└──────────────────────────────────────────────────────────────────────────────┘
|
||||
|
||||
## Components
|
||||
|
||||
### DNS Filter (`dns_filter.go`)
|
||||
Detects DNS packets on port 53 and routes to ControlD proxy.
|
||||
- Detects DNS packets on port 53 (UDP/TCP)
|
||||
- Forwards to ControlD DNS proxy (via DNS bridge)
|
||||
- Parses DNS responses to extract A/AAAA records
|
||||
- Automatically tracks resolved IPs via IP Tracker
|
||||
- Builds DNS response packets and sends back to TUN
|
||||
|
||||
### DNS Bridge (`dns_bridge.go`)
|
||||
Tracks DNS queries by transaction ID with 5-second timeout.
|
||||
- Bridges between netstack and ControlD DNS proxy
|
||||
- Tracks DNS queries by transaction ID
|
||||
- 5-second timeout per query
|
||||
- Returns responses to DNS filter
|
||||
|
||||
### IP Tracker (`ip_tracker.go`)
|
||||
- **Always enabled** - tracks all DNS-resolved IPs
|
||||
- In-memory whitelist with 5-minute TTL per IP
|
||||
- Background cleanup every 30 seconds (removes expired IPs)
|
||||
- Thread-safe with RWMutex (optimized for read-heavy workload)
|
||||
- Used by TCP/UDP forwarders to enforce DNS-first policy
|
||||
|
||||
### TCP Forwarder (`tcp_forwarder.go`)
|
||||
Forwards TCP connections using gVisor's `tcp.NewForwarder()`.
|
||||
- Handles TCP connections via gVisor's `tcp.NewForwarder()`
|
||||
- Checks `ipTracker != nil` (always true) for firewall enforcement
|
||||
- Allows internal VPN subnet (10.0.0.0/24) without checks
|
||||
- Blocks connections to non-tracked IPs (logs: "BLOCKED hardcoded IP")
|
||||
- Forwards allowed connections via `net.Dial("tcp")` to real network
|
||||
- Bidirectional copy between TUN and internet
|
||||
|
||||
### UDP Forwarder (`udp_forwarder.go`)
|
||||
Forwards UDP packets with session tracking and 60-second idle timeout.
|
||||
- Handles UDP packets via gVisor's `udp.NewForwarder()`
|
||||
- Session tracking with 30-second read timeout
|
||||
- Checks `ipTracker != nil` (always true) for firewall enforcement
|
||||
- Blocks QUIC (UDP/443, UDP/80) to force TCP fallback
|
||||
- Blocks connections to non-tracked IPs (logs: "BLOCKED hardcoded IP")
|
||||
- Forwards allowed packets via `net.Dial("udp")` to real network
|
||||
|
||||
### Packet Handler (`packet_handler.go`)
|
||||
Interface for TUN I/O and socket protection.
|
||||
- Interface for TUN I/O operations (read, write, close)
|
||||
- `MobilePacketHandler` wraps mobile platform callbacks
|
||||
- Bridges gomobile interface with netstack
|
||||
|
||||
### Netstack Controller (`netstack.go`)
|
||||
Manages gVisor stack and coordinates all components.
|
||||
|
||||
## Socket Protection
|
||||
|
||||
Critical for preventing routing loops:
|
||||
|
||||
```go
|
||||
// Protection happens BEFORE connect()
|
||||
dialer.Control = func(network, address string, c syscall.RawConn) error {
|
||||
return c.Control(func(fd uintptr) {
|
||||
protectSocket(int(fd))
|
||||
})
|
||||
}
|
||||
```
|
||||
|
||||
**All protected sockets:**
|
||||
- TCP/UDP forwarder sockets (user traffic)
|
||||
- ControlD API sockets (api.controld.com)
|
||||
- DoH upstream sockets (freedns.controld.com)
|
||||
- Manages gVisor TCP/IP stack
|
||||
- Coordinates DNS Filter, IP Tracker, TCP/UDP Forwarders
|
||||
- Always creates IP Tracker (firewall always on)
|
||||
- Reads packets from TUN → injects into netstack
|
||||
- Writes packets from netstack → sends to TUN
|
||||
- Filters outbound packets (source = 10.0.0.x)
|
||||
- Blocks QUIC before injection into netstack
|
||||
|
||||
## Platform Configuration
|
||||
|
||||
### Android
|
||||
|
||||
```kotlin
|
||||
// Base VPN configuration (same for both modes)
|
||||
Builder()
|
||||
.addAddress("10.0.0.2", 24)
|
||||
.addRoute("0.0.0.0", 0)
|
||||
.addDnsServer("10.0.0.1")
|
||||
.setMtu(1500)
|
||||
.setBlocking(true)
|
||||
.addDisallowedApplication(packageName) // Exclude self from VPN!
|
||||
|
||||
override fun protectSocket(fd: Long) {
|
||||
protect(fd.toInt()) // VpnService.protect()
|
||||
// Firewall mode - route ALL traffic
|
||||
if (isFirewallMode) {
|
||||
vpnBuilder.addRoute("0.0.0.0", 0)
|
||||
}
|
||||
// DNS-only mode - route ONLY DNS server IP
|
||||
else {
|
||||
vpnBuilder.addRoute("10.0.0.1", 32)
|
||||
}
|
||||
|
||||
// DNS Proxy: 0.0.0.0:5354
|
||||
vpnInterface = vpnBuilder.establish()
|
||||
|
||||
// DNS Proxy listens on: 0.0.0.0:5354
|
||||
// Library connects to: 127.0.0.1:5354
|
||||
```
|
||||
|
||||
**Important:**
|
||||
- App MUST exclude itself using `addDisallowedApplication()` to prevent routing loops
|
||||
- Mode switching: Call `setFirewallMode(enabled)` to recreate VPN interface with new routes
|
||||
|
||||
### iOS
|
||||
|
||||
```swift
|
||||
NEIPv4Settings(addresses: ["10.0.0.2"], ...)
|
||||
NEDNSSettings(servers: ["10.0.0.1"])
|
||||
includedRoutes = [NEIPv4Route.default()]
|
||||
// Base configuration (same for both modes)
|
||||
let ipv4Settings = NEIPv4Settings(
|
||||
addresses: ["10.0.0.2"],
|
||||
subnetMasks: ["255.255.255.0"]
|
||||
)
|
||||
|
||||
func protectSocket(_ fd: Int) throws {
|
||||
// No action needed - iOS Network Extension sockets
|
||||
// automatically bypass VPN tunnel
|
||||
// Firewall mode - route ALL traffic
|
||||
if isFirewallMode {
|
||||
ipv4Settings.includedRoutes = [NEIPv4Route.default()]
|
||||
}
|
||||
// DNS-only mode - route ONLY DNS server IP
|
||||
else {
|
||||
ipv4Settings.includedRoutes = [
|
||||
NEIPv4Route(destinationAddress: "10.0.0.1", subnetMask: "255.255.255.255")
|
||||
]
|
||||
}
|
||||
|
||||
// DNS Proxy: 127.0.0.1:53
|
||||
let dnsSettings = NEDNSSettings(servers: ["10.0.0.1"])
|
||||
dnsSettings.matchDomains = [""]
|
||||
|
||||
networkSettings.ipv4Settings = ipv4Settings
|
||||
networkSettings.dnsSettings = dnsSettings
|
||||
networkSettings.mtu = 1500
|
||||
|
||||
setTunnelNetworkSettings(networkSettings)
|
||||
|
||||
// DNS Proxy listens on: 127.0.0.1:53
|
||||
// Library connects to: 127.0.0.1:53
|
||||
```
|
||||
|
||||
**Note:** iOS Network Extensions run in separate process - sockets automatically bypass VPN.
|
||||
**Note:**
|
||||
- Network Extension sockets automatically bypass VPN - no routing loops
|
||||
- Mode switching: Send message `{"action": "set_firewall_mode", "enabled": "true"}` to extension
|
||||
|
||||
## Protocol Support
|
||||
|
||||
@@ -113,17 +426,70 @@ func protectSocket(_ fd: Int) throws {
|
||||
|
||||
## QUIC Blocking
|
||||
|
||||
Drops UDP packets on ports 443 and 80 to force TCP fallback:
|
||||
Blocks UDP packets on ports 443 and 80 to force TCP fallback.
|
||||
|
||||
**Where it's blocked:**
|
||||
- `netstack.go:354-369` - Blocks QUIC **before** injection into gVisor stack
|
||||
- Early blocking (pre-netstack) for efficiency
|
||||
- Checks destination port (UDP/443, UDP/80) in raw packet
|
||||
|
||||
**Why:**
|
||||
- Better DNS filtering (QUIC bypasses DNS)
|
||||
- Visible SNI for content filtering
|
||||
- Consistent ControlD policy enforcement
|
||||
- QUIC/HTTP3 can use cached IPs, bypassing DNS filtering entirely
|
||||
- TCP/TLS provides visible SNI for content filtering
|
||||
- Ensures consistent ControlD policy enforcement
|
||||
- IP tracker alone isn't enough (apps cache QUIC IPs aggressively)
|
||||
|
||||
**Result:**
|
||||
- Apps automatically fallback to TCP/TLS
|
||||
- No user-visible errors
|
||||
- Slightly slower initial connection, then normal
|
||||
- Apps automatically fallback to TCP/TLS (HTTP/2, HTTP/1.1)
|
||||
- No user-visible errors (fallback is seamless)
|
||||
- Slightly slower initial connection, then normal performance
|
||||
|
||||
**Note:** IP tracker ALSO blocks hardcoded IPs, but QUIC blocking provides additional layer of protection since QUIC apps often cache IPs longer than 5 minutes.
|
||||
|
||||
## IP Blocking (DNS Bypass Prevention)
|
||||
|
||||
**Firewall is ALWAYS enabled.** The IP tracker runs in all modes and tracks all DNS-resolved IPs.
|
||||
|
||||
**How it works:**
|
||||
1. DNS responses are parsed to extract A and AAAA records
|
||||
2. Resolved IPs are tracked in memory whitelist for 5 minutes (TTL)
|
||||
3. In **firewall mode**: TCP/UDP connections to **non-whitelisted** IPs are **BLOCKED**
|
||||
4. In **DNS-only mode**: Only DNS traffic reaches the VPN, so IP blocking is inactive
|
||||
|
||||
**Mode Behavior:**
|
||||
- **Firewall mode** (default routes): OS sends ALL traffic to VPN
|
||||
- DNS queries → tracked IPs
|
||||
- TCP/UDP connections → checked against tracker → blocked if not tracked
|
||||
|
||||
- **DNS-only mode** (DNS route only): OS sends ONLY DNS to VPN
|
||||
- DNS queries → tracked IPs
|
||||
- TCP/UDP connections → bypass VPN entirely (never reach tracker)
|
||||
|
||||
**Why IP tracker is always on:**
|
||||
- Simplifies implementation (no enable/disable logic)
|
||||
- Ready for mode switching at runtime
|
||||
- In DNS-only mode, tracker tracks IPs but never blocks (no TCP/UDP traffic)
|
||||
|
||||
**Example (Firewall Mode):**
|
||||
```
|
||||
T=0s: App connects to 1.2.3.4 directly
|
||||
→ ❌ BLOCKED (not in tracker)
|
||||
|
||||
T=1s: App queries "example.com" → DNS returns 93.184.216.34
|
||||
→ Tracker stores: 93.184.216.34 (expires in 5min)
|
||||
|
||||
T=2s: App connects to 93.184.216.34
|
||||
→ ✅ ALLOWED (found in tracker, not expired)
|
||||
|
||||
T=302s: App connects to 93.184.216.34
|
||||
→ ❌ BLOCKED (expired, must query DNS again)
|
||||
```
|
||||
|
||||
**Components:**
|
||||
- `ip_tracker.go` - Always-on whitelist with 5min TTL, 30s cleanup
|
||||
- `dns_filter.go` - Extracts A/AAAA records, tracks IPs automatically
|
||||
- `tcp_forwarder.go` - Checks `ipTracker != nil` (always true)
|
||||
- `udp_forwarder.go` - Checks `ipTracker != nil` (always true)
|
||||
|
||||
## Usage (Android)
|
||||
|
||||
@@ -132,9 +498,6 @@ Drops UDP packets on ports 443 and 80 to force TCP fallback:
|
||||
val callback = object : PacketAppCallback {
|
||||
override fun readPacket(): ByteArray { ... }
|
||||
override fun writePacket(packet: ByteArray) { ... }
|
||||
override fun protectSocket(fd: Long) {
|
||||
protect(fd.toInt())
|
||||
}
|
||||
override fun closePacketIO() { ... }
|
||||
override fun exit(s: String) { ... }
|
||||
override fun hostname(): String = "android-device"
|
||||
@@ -145,44 +508,59 @@ val callback = object : PacketAppCallback {
|
||||
// Create controller
|
||||
val controller = Ctrld_library.newPacketCaptureController(callback)
|
||||
|
||||
// Start
|
||||
// Start with all parameters
|
||||
controller.startWithPacketCapture(
|
||||
callback,
|
||||
cdUID,
|
||||
"", "",
|
||||
filesDir.absolutePath,
|
||||
"doh",
|
||||
2,
|
||||
"$filesDir/ctrld.log"
|
||||
callback, // PacketAppCallback
|
||||
"10.0.0.1", // TUN address (gateway)
|
||||
"10.0.0.2", // Device address
|
||||
1500, // MTU
|
||||
"127.0.0.1:5354", // DNS proxy address
|
||||
"your-cd-uid", // ControlD UID
|
||||
"", // Provision ID (optional)
|
||||
"", // Custom hostname (optional)
|
||||
filesDir.absolutePath, // Home directory
|
||||
"doh", // Upstream protocol (doh/dot/doq)
|
||||
2, // Log level (0-3)
|
||||
"$filesDir/ctrld.log" // Log path
|
||||
)
|
||||
|
||||
// Stop
|
||||
controller.stop(false, 0)
|
||||
|
||||
// Runtime mode switching (no restart needed)
|
||||
VpnController.instance?.setFirewallMode(context, isFirewallMode = true)
|
||||
```
|
||||
|
||||
## Usage (iOS)
|
||||
|
||||
```swift
|
||||
// DNS-only mode
|
||||
// Start LocalProxy with all parameters
|
||||
let proxy = LocalProxy()
|
||||
proxy.mode = .firewall // or .dnsOnly
|
||||
|
||||
proxy.start(
|
||||
cUID: cdUID,
|
||||
deviceName: UIDevice.current.name,
|
||||
upstreamProto: "doh",
|
||||
logLevel: 3,
|
||||
provisionID: ""
|
||||
tunAddress: "10.0.0.1", // TUN address (gateway)
|
||||
deviceAddress: "10.0.0.2", // Device address
|
||||
mtu: 1500, // MTU
|
||||
dnsProxyAddress: "127.0.0.1:53", // DNS proxy address
|
||||
cUID: cdUID, // ControlD UID
|
||||
provisionID: "", // Provision ID (optional)
|
||||
customHostname: "", // Custom hostname (optional)
|
||||
homeDir: FileManager().temporaryDirectory.path, // Home directory
|
||||
upstreamProto: "doh", // Upstream protocol
|
||||
logLevel: 2, // Log level (0-3)
|
||||
logPath: FileManager().temporaryDirectory.appendingPathComponent("ctrld.log").path,
|
||||
deviceName: UIDevice.current.name, // Device name
|
||||
packetFlow: packetFlow // NEPacketTunnelFlow
|
||||
)
|
||||
|
||||
// Firewall mode (full capture)
|
||||
let proxy = LocalProxy()
|
||||
proxy.startFirewall(
|
||||
cUID: cdUID,
|
||||
deviceName: UIDevice.current.name,
|
||||
upstreamProto: "doh",
|
||||
logLevel: 3,
|
||||
provisionID: "",
|
||||
packetFlow: packetFlow
|
||||
)
|
||||
// Stop
|
||||
proxy.stop()
|
||||
|
||||
// Runtime mode switching (no restart needed)
|
||||
// Send message from main app to extension:
|
||||
let message = ["action": "set_firewall_mode", "enabled": "true"]
|
||||
session.sendProviderMessage(JSONEncoder().encode(message)) { response in }
|
||||
```
|
||||
|
||||
## Requirements
|
||||
@@ -196,10 +574,11 @@ proxy.startFirewall(
|
||||
|
||||
- `packet_handler.go` - TUN I/O interface
|
||||
- `netstack.go` - gVisor controller
|
||||
- `dns_filter.go` - DNS packet detection
|
||||
- `dns_filter.go` - DNS packet detection and IP extraction
|
||||
- `dns_bridge.go` - Transaction tracking
|
||||
- `tcp_forwarder.go` - TCP forwarding
|
||||
- `udp_forwarder.go` - UDP forwarding
|
||||
- `ip_tracker.go` - DNS-resolved IP whitelist with TTL
|
||||
- `tcp_forwarder.go` - TCP forwarding with whitelist enforcement
|
||||
- `udp_forwarder.go` - UDP forwarding with whitelist enforcement
|
||||
|
||||
## License
|
||||
|
||||
|
||||
@@ -5,6 +5,7 @@ import (
|
||||
"fmt"
|
||||
"net"
|
||||
|
||||
"github.com/miekg/dns"
|
||||
"gvisor.dev/gvisor/pkg/tcpip"
|
||||
"gvisor.dev/gvisor/pkg/tcpip/header"
|
||||
)
|
||||
@@ -12,12 +13,14 @@ import (
|
||||
// DNSFilter intercepts and processes DNS packets.
|
||||
type DNSFilter struct {
|
||||
dnsHandler func([]byte) ([]byte, error)
|
||||
ipTracker *IPTracker
|
||||
}
|
||||
|
||||
// NewDNSFilter creates a new DNS filter with the given handler.
|
||||
func NewDNSFilter(handler func([]byte) ([]byte, error)) *DNSFilter {
|
||||
func NewDNSFilter(handler func([]byte) ([]byte, error), ipTracker *IPTracker) *DNSFilter {
|
||||
return &DNSFilter{
|
||||
dnsHandler: handler,
|
||||
ipTracker: ipTracker,
|
||||
}
|
||||
}
|
||||
|
||||
@@ -101,6 +104,11 @@ func (df *DNSFilter) processIPv4(packet []byte) (bool, []byte, error) {
|
||||
return true, nil, fmt.Errorf("DNS handler error: %v", err)
|
||||
}
|
||||
|
||||
// Track IPs from DNS response
|
||||
if df.ipTracker != nil {
|
||||
df.extractAndTrackIPs(dnsResponse)
|
||||
}
|
||||
|
||||
// Build response packet
|
||||
responsePacket := df.buildIPv4UDPPacket(
|
||||
dstIP.As4(), // Swap src/dst
|
||||
@@ -166,6 +174,11 @@ func (df *DNSFilter) processIPv6(packet []byte) (bool, []byte, error) {
|
||||
return true, nil, fmt.Errorf("DNS handler error: %v", err)
|
||||
}
|
||||
|
||||
// Track IPs from DNS response
|
||||
if df.ipTracker != nil {
|
||||
df.extractAndTrackIPs(dnsResponse)
|
||||
}
|
||||
|
||||
// Build response packet
|
||||
srcIP := ipHdr.SourceAddress()
|
||||
dstIP := ipHdr.DestinationAddress()
|
||||
@@ -322,3 +335,31 @@ func parseUDP(udpHeader []byte) (srcPort, dstPort uint16, ok bool) {
|
||||
ok = true
|
||||
return
|
||||
}
|
||||
|
||||
// extractAndTrackIPs parses DNS response and tracks resolved IP addresses
|
||||
func (df *DNSFilter) extractAndTrackIPs(dnsResponse []byte) {
|
||||
if len(dnsResponse) < 12 {
|
||||
return // Invalid DNS response
|
||||
}
|
||||
|
||||
msg := new(dns.Msg)
|
||||
if err := msg.Unpack(dnsResponse); err != nil {
|
||||
return // Failed to parse DNS response
|
||||
}
|
||||
|
||||
// Extract IPs from answer section
|
||||
for _, answer := range msg.Answer {
|
||||
switch rr := answer.(type) {
|
||||
case *dns.A:
|
||||
// IPv4 address
|
||||
if rr.A != nil {
|
||||
df.ipTracker.TrackIP(rr.A)
|
||||
}
|
||||
case *dns.AAAA:
|
||||
// IPv6 address
|
||||
if rr.AAAA != nil {
|
||||
df.ipTracker.TrackIP(rr.AAAA)
|
||||
}
|
||||
}
|
||||
}
|
||||
}
|
||||
|
||||
150
cmd/ctrld_library/netstack/ip_tracker.go
Normal file
150
cmd/ctrld_library/netstack/ip_tracker.go
Normal file
@@ -0,0 +1,150 @@
|
||||
package netstack
|
||||
|
||||
import (
|
||||
"net"
|
||||
"sync"
|
||||
"time"
|
||||
)
|
||||
|
||||
// IPTracker tracks IP addresses that have been resolved through DNS.
|
||||
// This allows blocking direct IP connections that bypass DNS filtering.
|
||||
type IPTracker struct {
|
||||
// Map of IP address string -> expiration time
|
||||
resolvedIPs map[string]time.Time
|
||||
mu sync.RWMutex
|
||||
|
||||
// TTL for tracked IPs (how long to remember them)
|
||||
ttl time.Duration
|
||||
|
||||
// Running state
|
||||
running bool
|
||||
stopCh chan struct{}
|
||||
wg sync.WaitGroup
|
||||
}
|
||||
|
||||
// NewIPTracker creates a new IP tracker with the specified TTL
|
||||
func NewIPTracker(ttl time.Duration) *IPTracker {
|
||||
if ttl == 0 {
|
||||
ttl = 5 * time.Minute // Default 5 minutes
|
||||
}
|
||||
|
||||
return &IPTracker{
|
||||
resolvedIPs: make(map[string]time.Time),
|
||||
ttl: ttl,
|
||||
stopCh: make(chan struct{}),
|
||||
}
|
||||
}
|
||||
|
||||
// Start starts the IP tracker cleanup routine
|
||||
func (t *IPTracker) Start() {
|
||||
t.mu.Lock()
|
||||
if t.running {
|
||||
t.mu.Unlock()
|
||||
return
|
||||
}
|
||||
t.running = true
|
||||
t.mu.Unlock()
|
||||
|
||||
// Start cleanup goroutine to remove expired IPs
|
||||
t.wg.Add(1)
|
||||
go t.cleanupExpiredIPs()
|
||||
}
|
||||
|
||||
// Stop stops the IP tracker
|
||||
func (t *IPTracker) Stop() {
|
||||
if t == nil {
|
||||
return
|
||||
}
|
||||
|
||||
t.mu.Lock()
|
||||
if !t.running {
|
||||
t.mu.Unlock()
|
||||
return
|
||||
}
|
||||
t.running = false
|
||||
t.mu.Unlock()
|
||||
|
||||
// Close stop channel (protected against double close)
|
||||
select {
|
||||
case <-t.stopCh:
|
||||
// Already closed
|
||||
default:
|
||||
close(t.stopCh)
|
||||
}
|
||||
|
||||
t.wg.Wait()
|
||||
|
||||
// Clear all tracked IPs
|
||||
t.mu.Lock()
|
||||
t.resolvedIPs = make(map[string]time.Time)
|
||||
t.mu.Unlock()
|
||||
}
|
||||
|
||||
// TrackIP adds an IP address to the tracking list
|
||||
func (t *IPTracker) TrackIP(ip net.IP) {
|
||||
if ip == nil {
|
||||
return
|
||||
}
|
||||
|
||||
// Normalize to string format
|
||||
ipStr := ip.String()
|
||||
|
||||
t.mu.Lock()
|
||||
t.resolvedIPs[ipStr] = time.Now().Add(t.ttl)
|
||||
t.mu.Unlock()
|
||||
}
|
||||
|
||||
// IsTracked checks if an IP address is in the tracking list
|
||||
// Optimized to minimize lock contention by avoiding write locks in the hot path
|
||||
func (t *IPTracker) IsTracked(ip net.IP) bool {
|
||||
if ip == nil {
|
||||
return false
|
||||
}
|
||||
|
||||
ipStr := ip.String()
|
||||
|
||||
t.mu.RLock()
|
||||
expiration, exists := t.resolvedIPs[ipStr]
|
||||
t.mu.RUnlock()
|
||||
|
||||
if !exists {
|
||||
return false
|
||||
}
|
||||
|
||||
// Check if expired - but DON'T delete here to avoid write lock
|
||||
// Let the cleanup goroutine handle expired entries
|
||||
// This keeps IsTracked fast with only read locks
|
||||
return !time.Now().After(expiration)
|
||||
}
|
||||
|
||||
// GetTrackedCount returns the number of currently tracked IPs
|
||||
func (t *IPTracker) GetTrackedCount() int {
|
||||
t.mu.RLock()
|
||||
defer t.mu.RUnlock()
|
||||
return len(t.resolvedIPs)
|
||||
}
|
||||
|
||||
// cleanupExpiredIPs periodically removes expired IP entries
|
||||
func (t *IPTracker) cleanupExpiredIPs() {
|
||||
defer t.wg.Done()
|
||||
|
||||
ticker := time.NewTicker(30 * time.Second)
|
||||
defer ticker.Stop()
|
||||
|
||||
for {
|
||||
select {
|
||||
case <-t.stopCh:
|
||||
return
|
||||
|
||||
case <-ticker.C:
|
||||
now := time.Now()
|
||||
t.mu.Lock()
|
||||
for ip, expiration := range t.resolvedIPs {
|
||||
if now.After(expiration) {
|
||||
delete(t.resolvedIPs, ip)
|
||||
}
|
||||
}
|
||||
t.mu.Unlock()
|
||||
}
|
||||
}
|
||||
}
|
||||
@@ -28,7 +28,7 @@ const (
|
||||
NICID = 1
|
||||
|
||||
// Channel capacity for packet buffers
|
||||
channelCapacity = 256
|
||||
channelCapacity = 512
|
||||
)
|
||||
|
||||
// NetstackController manages the gVisor netstack integration for mobile packet capture.
|
||||
@@ -37,6 +37,7 @@ type NetstackController struct {
|
||||
linkEP *channel.Endpoint
|
||||
packetHandler PacketHandler
|
||||
dnsFilter *DNSFilter
|
||||
ipTracker *IPTracker
|
||||
tcpForwarder *TCPForwarder
|
||||
udpForwarder *UDPForwarder
|
||||
|
||||
@@ -100,14 +101,19 @@ func NewNetstackController(handler PacketHandler, cfg *Config) (*NetstackControl
|
||||
// Create link endpoint
|
||||
linkEP := channel.New(channelCapacity, cfg.MTU, "")
|
||||
|
||||
// Create DNS filter
|
||||
dnsFilter := NewDNSFilter(cfg.DNSHandler)
|
||||
// Always create IP tracker (5 minute TTL for tracked IPs)
|
||||
// In firewall mode (default routes): blocks direct IP connections
|
||||
// In DNS-only mode: no non-DNS traffic to block
|
||||
ipTracker := NewIPTracker(5 * time.Minute)
|
||||
|
||||
// Create TCP forwarder
|
||||
tcpForwarder := NewTCPForwarder(s, handler.ProtectSocket, ctx)
|
||||
// Create DNS filter with IP tracker
|
||||
dnsFilter := NewDNSFilter(cfg.DNSHandler, ipTracker)
|
||||
|
||||
// Create UDP forwarder
|
||||
udpForwarder := NewUDPForwarder(s, handler.ProtectSocket, ctx)
|
||||
// Create TCP forwarder with IP tracker
|
||||
tcpForwarder := NewTCPForwarder(s, ctx, ipTracker)
|
||||
|
||||
// Create UDP forwarder with IP tracker
|
||||
udpForwarder := NewUDPForwarder(s, ctx, ipTracker)
|
||||
|
||||
// Create NIC
|
||||
if err := s.CreateNIC(NICID, linkEP); err != nil {
|
||||
@@ -176,6 +182,7 @@ func NewNetstackController(handler PacketHandler, cfg *Config) (*NetstackControl
|
||||
linkEP: linkEP,
|
||||
packetHandler: handler,
|
||||
dnsFilter: dnsFilter,
|
||||
ipTracker: ipTracker,
|
||||
tcpForwarder: tcpForwarder,
|
||||
udpForwarder: udpForwarder,
|
||||
ctx: ctx,
|
||||
@@ -199,6 +206,9 @@ func (nc *NetstackController) Start() error {
|
||||
|
||||
nc.started = true
|
||||
|
||||
// Start IP tracker
|
||||
nc.ipTracker.Start()
|
||||
|
||||
// Start packet reader goroutine (TUN -> netstack)
|
||||
nc.wg.Add(1)
|
||||
go nc.readPackets()
|
||||
@@ -207,36 +217,69 @@ func (nc *NetstackController) Start() error {
|
||||
nc.wg.Add(1)
|
||||
go nc.writePackets()
|
||||
|
||||
ctrld.ProxyLogger.Load().Info().Msg("[Netstack] Packet processing started (read/write goroutines)")
|
||||
ctrld.ProxyLogger.Load().Info().Msg("[Netstack] Packet processing started (read/write goroutines + IP tracker)")
|
||||
|
||||
return nil
|
||||
}
|
||||
|
||||
// Stop stops the netstack controller and waits for all goroutines to finish.
|
||||
func (nc *NetstackController) Stop() error {
|
||||
ctrld.ProxyLogger.Load().Info().Msg("[Netstack] Stop() called - starting shutdown")
|
||||
|
||||
nc.mu.Lock()
|
||||
if !nc.started {
|
||||
nc.mu.Unlock()
|
||||
ctrld.ProxyLogger.Load().Info().Msg("[Netstack] Stop() - already stopped, returning")
|
||||
return nil
|
||||
}
|
||||
nc.mu.Unlock()
|
||||
|
||||
ctrld.ProxyLogger.Load().Info().Msg("[Netstack] Stop() - canceling context")
|
||||
nc.cancel()
|
||||
|
||||
// Close packet handler FIRST to unblock all pending reads
|
||||
ctrld.ProxyLogger.Load().Info().Msg("[Netstack] Stop() - closing packet handler to unblock goroutines")
|
||||
if err := nc.packetHandler.Close(); err != nil {
|
||||
ctrld.ProxyLogger.Load().Error().Msgf("[Netstack] Stop() - failed to close packet handler: %v", err)
|
||||
// Continue shutdown even if close fails
|
||||
}
|
||||
ctrld.ProxyLogger.Load().Info().Msg("[Netstack] Stop() - packet handler closed")
|
||||
|
||||
ctrld.ProxyLogger.Load().Info().Msg("[Netstack] Stop() - waiting for goroutines (max 2 seconds)")
|
||||
|
||||
// Wait for goroutines with timeout
|
||||
done := make(chan struct{})
|
||||
go func() {
|
||||
nc.wg.Wait()
|
||||
close(done)
|
||||
}()
|
||||
|
||||
select {
|
||||
case <-done:
|
||||
ctrld.ProxyLogger.Load().Info().Msg("[Netstack] Stop() - all goroutines finished")
|
||||
case <-time.After(2 * time.Second):
|
||||
ctrld.ProxyLogger.Load().Warn().Msg("[Netstack] Stop() - timeout waiting for goroutines, proceeding anyway")
|
||||
}
|
||||
|
||||
// Stop IP tracker
|
||||
if nc.ipTracker != nil {
|
||||
ctrld.ProxyLogger.Load().Info().Msg("[Netstack] Stop() - stopping IP tracker")
|
||||
nc.ipTracker.Stop()
|
||||
ctrld.ProxyLogger.Load().Info().Msg("[Netstack] Stop() - IP tracker stopped")
|
||||
}
|
||||
|
||||
// Close UDP forwarder
|
||||
if nc.udpForwarder != nil {
|
||||
ctrld.ProxyLogger.Load().Info().Msg("[Netstack] Stop() - closing UDP forwarder")
|
||||
nc.udpForwarder.Close()
|
||||
}
|
||||
|
||||
if err := nc.packetHandler.Close(); err != nil {
|
||||
return fmt.Errorf("failed to close packet handler: %v", err)
|
||||
ctrld.ProxyLogger.Load().Info().Msg("[Netstack] Stop() - UDP forwarder closed")
|
||||
}
|
||||
|
||||
nc.mu.Lock()
|
||||
nc.started = false
|
||||
nc.mu.Unlock()
|
||||
|
||||
ctrld.ProxyLogger.Load().Info().Msg("[Netstack] Stop() - shutdown complete")
|
||||
return nil
|
||||
}
|
||||
|
||||
|
||||
@@ -17,11 +17,6 @@ type PacketHandler interface {
|
||||
|
||||
// Close closes the packet handler and releases resources.
|
||||
Close() error
|
||||
|
||||
// ProtectSocket protects a socket file descriptor from being routed through the VPN.
|
||||
// This is required on Android/iOS to prevent routing loops.
|
||||
// Returns nil if successful, error otherwise.
|
||||
ProtectSocket(fd int) error
|
||||
}
|
||||
|
||||
// MobilePacketHandler implements PacketHandler using callbacks from mobile platforms.
|
||||
@@ -30,7 +25,6 @@ type MobilePacketHandler struct {
|
||||
readFunc func() ([]byte, error)
|
||||
writeFunc func([]byte) error
|
||||
closeFunc func() error
|
||||
protectFunc func(int) error
|
||||
|
||||
mu sync.Mutex
|
||||
closed bool
|
||||
@@ -41,13 +35,11 @@ func NewMobilePacketHandler(
|
||||
readFunc func() ([]byte, error),
|
||||
writeFunc func([]byte) error,
|
||||
closeFunc func() error,
|
||||
protectFunc func(int) error,
|
||||
) *MobilePacketHandler {
|
||||
return &MobilePacketHandler{
|
||||
readFunc: readFunc,
|
||||
writeFunc: writeFunc,
|
||||
closeFunc: closeFunc,
|
||||
protectFunc: protectFunc,
|
||||
closed: false,
|
||||
}
|
||||
}
|
||||
@@ -103,13 +95,3 @@ func (m *MobilePacketHandler) Close() error {
|
||||
|
||||
return nil
|
||||
}
|
||||
|
||||
// ProtectSocket protects a socket file descriptor from VPN routing.
|
||||
func (m *MobilePacketHandler) ProtectSocket(fd int) error {
|
||||
if m.protectFunc == nil {
|
||||
// No protect function provided - this is okay for non-VPN scenarios
|
||||
return nil
|
||||
}
|
||||
|
||||
return m.protectFunc(fd)
|
||||
}
|
||||
|
||||
@@ -4,7 +4,6 @@ import (
|
||||
"context"
|
||||
"io"
|
||||
"net"
|
||||
"syscall"
|
||||
"time"
|
||||
|
||||
"github.com/Control-D-Inc/ctrld"
|
||||
@@ -16,20 +15,20 @@ import (
|
||||
|
||||
// TCPForwarder handles TCP connections from the TUN interface
|
||||
type TCPForwarder struct {
|
||||
protectSocket func(fd int) error
|
||||
ctx context.Context
|
||||
forwarder *tcp.Forwarder
|
||||
ipTracker *IPTracker
|
||||
}
|
||||
|
||||
// NewTCPForwarder creates a new TCP forwarder
|
||||
func NewTCPForwarder(s *stack.Stack, protectSocket func(fd int) error, ctx context.Context) *TCPForwarder {
|
||||
func NewTCPForwarder(s *stack.Stack, ctx context.Context, ipTracker *IPTracker) *TCPForwarder {
|
||||
f := &TCPForwarder{
|
||||
protectSocket: protectSocket,
|
||||
ctx: ctx,
|
||||
ipTracker: ipTracker,
|
||||
}
|
||||
|
||||
// Create gVisor TCP forwarder with handler callback
|
||||
// rcvWnd=0 (default), maxInFlight=1024
|
||||
// rcvWnd=0 (use default), maxInFlight=1024
|
||||
f.forwarder = tcp.NewForwarder(s, 0, 1024, f.handleRequest)
|
||||
|
||||
return f
|
||||
@@ -78,23 +77,31 @@ func (f *TCPForwarder) handleConnection(ep *tcp.Endpoint, wq *waiter.Queue, id s
|
||||
// - LocalAddress/LocalPort = the destination (where packet is going TO)
|
||||
// - RemoteAddress/RemotePort = the source (where packet is coming FROM)
|
||||
// We want to dial the DESTINATION (LocalAddress/LocalPort)
|
||||
dstIP := net.IP(id.LocalAddress.AsSlice())
|
||||
dstAddr := net.TCPAddr{
|
||||
IP: net.IP(id.LocalAddress.AsSlice()),
|
||||
IP: dstIP,
|
||||
Port: int(id.LocalPort),
|
||||
}
|
||||
|
||||
// Create outbound connection with socket protection DURING dial
|
||||
dialer := &net.Dialer{
|
||||
Timeout: 30 * time.Second,
|
||||
// Check if IP blocking is enabled (firewall mode only)
|
||||
// Skip blocking for internal VPN subnet (10.0.0.0/24)
|
||||
if f.ipTracker != nil {
|
||||
// Allow internal VPN traffic (10.0.0.0/24)
|
||||
if !(dstIP[0] == 10 && dstIP[1] == 0 && dstIP[2] == 0) {
|
||||
// Check if destination IP was resolved through ControlD DNS
|
||||
// ONLY allow connections to IPs that went through DNS (whitelist approach)
|
||||
if !f.ipTracker.IsTracked(dstIP) {
|
||||
srcAddr := net.IP(id.RemoteAddress.AsSlice())
|
||||
ctrld.ProxyLogger.Load().Info().Msgf("[TCP] BLOCKED hardcoded IP: %s:%d -> %s:%d (not resolved via DNS)",
|
||||
srcAddr, id.RemotePort, dstIP, id.LocalPort)
|
||||
return
|
||||
}
|
||||
}
|
||||
}
|
||||
|
||||
// CRITICAL: Protect socket BEFORE connect() is called
|
||||
if f.protectSocket != nil {
|
||||
dialer.Control = func(network, address string, c syscall.RawConn) error {
|
||||
return c.Control(func(fd uintptr) {
|
||||
f.protectSocket(int(fd))
|
||||
})
|
||||
}
|
||||
// Create outbound connection
|
||||
dialer := &net.Dialer{
|
||||
Timeout: 30 * time.Second,
|
||||
}
|
||||
|
||||
upstreamConn, err := dialer.DialContext(f.ctx, "tcp", dstAddr.String())
|
||||
|
||||
@@ -5,7 +5,6 @@ import (
|
||||
"fmt"
|
||||
"net"
|
||||
"sync"
|
||||
"syscall"
|
||||
"time"
|
||||
|
||||
"github.com/Control-D-Inc/ctrld"
|
||||
@@ -17,9 +16,9 @@ import (
|
||||
|
||||
// UDPForwarder handles UDP packets from the TUN interface
|
||||
type UDPForwarder struct {
|
||||
protectSocket func(fd int) error
|
||||
ctx context.Context
|
||||
forwarder *udp.Forwarder
|
||||
ipTracker *IPTracker
|
||||
|
||||
// Track UDP "connections" (address pairs)
|
||||
connections map[string]*udpConn
|
||||
@@ -33,10 +32,10 @@ type udpConn struct {
|
||||
}
|
||||
|
||||
// NewUDPForwarder creates a new UDP forwarder
|
||||
func NewUDPForwarder(s *stack.Stack, protectSocket func(fd int) error, ctx context.Context) *UDPForwarder {
|
||||
func NewUDPForwarder(s *stack.Stack, ctx context.Context, ipTracker *IPTracker) *UDPForwarder {
|
||||
f := &UDPForwarder{
|
||||
protectSocket: protectSocket,
|
||||
ctx: ctx,
|
||||
ipTracker: ipTracker,
|
||||
connections: make(map[string]*udpConn),
|
||||
}
|
||||
|
||||
@@ -102,22 +101,30 @@ func (f *UDPForwarder) createConnection(req *udp.ForwarderRequest, connKey strin
|
||||
// Extract destination address
|
||||
// LocalAddress/LocalPort = destination (where packet is going TO)
|
||||
// RemoteAddress/RemotePort = source (where packet is coming FROM)
|
||||
dstIP := net.IP(id.LocalAddress.AsSlice())
|
||||
dstAddr := &net.UDPAddr{
|
||||
IP: net.IP(id.LocalAddress.AsSlice()),
|
||||
IP: dstIP,
|
||||
Port: int(id.LocalPort),
|
||||
}
|
||||
|
||||
// Create dialer with socket protection DURING dial
|
||||
dialer := &net.Dialer{}
|
||||
// Check if IP blocking is enabled (firewall mode only)
|
||||
// Skip blocking for internal VPN subnet (10.0.0.0/24)
|
||||
if f.ipTracker != nil {
|
||||
// Allow internal VPN traffic (10.0.0.0/24)
|
||||
if !(dstIP[0] == 10 && dstIP[1] == 0 && dstIP[2] == 0) {
|
||||
// Check if destination IP was resolved through ControlD DNS
|
||||
// ONLY allow connections to IPs that went through DNS (whitelist approach)
|
||||
if !f.ipTracker.IsTracked(dstIP) {
|
||||
srcAddr := net.IP(id.RemoteAddress.AsSlice())
|
||||
ctrld.ProxyLogger.Load().Info().Msgf("[UDP] BLOCKED hardcoded IP: %s:%d -> %s:%d (not resolved via DNS)",
|
||||
srcAddr, id.RemotePort, dstIP, id.LocalPort)
|
||||
return nil
|
||||
}
|
||||
}
|
||||
}
|
||||
|
||||
// CRITICAL: Protect socket BEFORE connect() is called
|
||||
if f.protectSocket != nil {
|
||||
dialer.Control = func(network, address string, c syscall.RawConn) error {
|
||||
return c.Control(func(fd uintptr) {
|
||||
f.protectSocket(int(fd))
|
||||
})
|
||||
}
|
||||
}
|
||||
// Create dialer
|
||||
dialer := &net.Dialer{}
|
||||
|
||||
// Create outbound UDP connection
|
||||
dialConn, dialErr := dialer.Dial("udp", dstAddr.String())
|
||||
@@ -214,13 +221,18 @@ func (f *UDPForwarder) forwardUpstreamToTun(conn *udpConn, ctx context.Context,
|
||||
|
||||
// Close closes all UDP connections
|
||||
func (f *UDPForwarder) Close() {
|
||||
ctrld.ProxyLogger.Load().Info().Msg("[UDP] Close() called - closing all connections")
|
||||
|
||||
f.mu.Lock()
|
||||
defer f.mu.Unlock()
|
||||
|
||||
for _, conn := range f.connections {
|
||||
ctrld.ProxyLogger.Load().Info().Msgf("[UDP] Close() - closing %d connections", len(f.connections))
|
||||
for key, conn := range f.connections {
|
||||
ctrld.ProxyLogger.Load().Debug().Msgf("[UDP] Close() - closing connection: %s", key)
|
||||
conn.cancel()
|
||||
conn.tunEP.Close()
|
||||
conn.upstreamConn.Close()
|
||||
}
|
||||
f.connections = make(map[string]*udpConn)
|
||||
ctrld.ProxyLogger.Load().Info().Msg("[UDP] Close() - all connections closed")
|
||||
}
|
||||
|
||||
@@ -3,7 +3,6 @@ package ctrld_library
|
||||
import (
|
||||
"fmt"
|
||||
"net/netip"
|
||||
"runtime"
|
||||
"time"
|
||||
|
||||
"github.com/Control-D-Inc/ctrld"
|
||||
@@ -26,12 +25,6 @@ type PacketAppCallback interface {
|
||||
|
||||
// ClosePacketIO closes packet I/O resources.
|
||||
ClosePacketIO() error
|
||||
|
||||
// ProtectSocket protects a socket file descriptor from being routed through the VPN.
|
||||
// On Android, this calls VpnService.protect() to prevent routing loops.
|
||||
// On iOS, this marks the socket to bypass the VPN.
|
||||
// Returns nil on success, error on failure.
|
||||
ProtectSocket(fd int) error
|
||||
}
|
||||
|
||||
// PacketCaptureController holds state for packet capture mode
|
||||
@@ -42,6 +35,7 @@ type PacketCaptureController struct {
|
||||
netstackCtrl *netstack.NetstackController
|
||||
dnsBridge *netstack.DNSBridge
|
||||
packetStopCh chan struct{}
|
||||
dnsProxyAddress string
|
||||
}
|
||||
|
||||
// NewPacketCaptureController creates a new packet capture controller
|
||||
@@ -57,6 +51,10 @@ func NewPacketCaptureController(appCallback PacketAppCallback) *PacketCaptureCon
|
||||
// It requires a PacketAppCallback that provides packet read/write capabilities.
|
||||
func (pc *PacketCaptureController) StartWithPacketCapture(
|
||||
packetCallback PacketAppCallback,
|
||||
tunAddress string,
|
||||
deviceAddress string,
|
||||
mtu int64,
|
||||
dnsProxyAddress string,
|
||||
CdUID string,
|
||||
ProvisionID string,
|
||||
CustomHostname string,
|
||||
@@ -69,6 +67,14 @@ func (pc *PacketCaptureController) StartWithPacketCapture(
|
||||
return fmt.Errorf("controller already running")
|
||||
}
|
||||
|
||||
// Store DNS proxy address for handleDNSQuery
|
||||
pc.dnsProxyAddress = dnsProxyAddress
|
||||
|
||||
// Set defaults
|
||||
if mtu == 0 {
|
||||
mtu = 1500
|
||||
}
|
||||
|
||||
// Set up configuration
|
||||
pc.baseController.Config = cli.AppConfig{
|
||||
CdUID: CdUID,
|
||||
@@ -81,10 +87,6 @@ func (pc *PacketCaptureController) StartWithPacketCapture(
|
||||
}
|
||||
pc.baseController.AppCallback = packetCallback
|
||||
|
||||
// Set global socket protector for HTTP client sockets (API calls, etc)
|
||||
// This prevents routing loops when ctrld makes HTTP requests to api.controld.com
|
||||
ctrld.SetSocketProtector(packetCallback.ProtectSocket)
|
||||
|
||||
// Create DNS bridge for communication between netstack and DNS proxy
|
||||
pc.dnsBridge = netstack.NewDNSBridge()
|
||||
pc.dnsBridge.Start()
|
||||
@@ -94,36 +96,29 @@ func (pc *PacketCaptureController) StartWithPacketCapture(
|
||||
packetCallback.ReadPacket,
|
||||
packetCallback.WritePacket,
|
||||
packetCallback.ClosePacketIO,
|
||||
packetCallback.ProtectSocket,
|
||||
)
|
||||
|
||||
// Create DNS handler that uses the bridge
|
||||
dnsHandler := func(query []byte) ([]byte, error) {
|
||||
// Extract source IP from query context if available
|
||||
// For now, use a placeholder
|
||||
return pc.dnsBridge.ProcessQuery(query, "10.0.0.2", 0)
|
||||
// Use device address as the source of DNS queries
|
||||
return pc.dnsBridge.ProcessQuery(query, deviceAddress, 0)
|
||||
}
|
||||
|
||||
// Auto-detect platform and use appropriate TUN IP
|
||||
// Android: TUN=10.0.0.1, Device=10.0.0.2
|
||||
// iOS: TUN=10.0.0.2, Device=10.0.0.1
|
||||
tunIP := "10.0.0.1" // Default for Android
|
||||
// Check if running on iOS (no reliable way, so we'll make it configurable)
|
||||
// For now, use Android config. iOS should update their VPN settings to match.
|
||||
|
||||
tunIPv4, err := netip.ParseAddr(tunIP)
|
||||
// Parse TUN IP address
|
||||
tunIPv4, err := netip.ParseAddr(tunAddress)
|
||||
if err != nil {
|
||||
return fmt.Errorf("failed to parse TUN IPv4: %v", err)
|
||||
return fmt.Errorf("failed to parse TUN IPv4 address '%s': %v", tunAddress, err)
|
||||
}
|
||||
|
||||
netstackCfg := &netstack.Config{
|
||||
MTU: 1500,
|
||||
MTU: uint32(mtu),
|
||||
TUNIPv4: tunIPv4,
|
||||
DNSHandler: dnsHandler,
|
||||
UpstreamInterface: nil, // Will use default interface
|
||||
}
|
||||
|
||||
ctrld.ProxyLogger.Load().Info().Msgf("[PacketCapture] Netstack TUN IP: %s", tunIP)
|
||||
ctrld.ProxyLogger.Load().Info().Msgf("[PacketCapture] Network config - TUN: %s, Device: %s, MTU: %d, DNS Proxy: %s",
|
||||
tunAddress, deviceAddress, mtu, dnsProxyAddress)
|
||||
|
||||
// Create netstack controller
|
||||
netstackCtrl, err := netstack.NewNetstackController(packetHandler, netstackCfg)
|
||||
@@ -154,12 +149,10 @@ func (pc *PacketCaptureController) StartWithPacketCapture(
|
||||
cli.RunMobile(&pc.baseController.Config, &appCallback, pc.baseController.stopCh)
|
||||
}()
|
||||
|
||||
// Log platform detection for DNS proxy port
|
||||
dnsPort := "5354"
|
||||
if runtime.GOOS == "ios" || runtime.GOOS == "darwin" {
|
||||
dnsPort = "53"
|
||||
}
|
||||
ctrld.ProxyLogger.Load().Info().Msgf("[PacketCapture] Platform: %s, DNS proxy port: %s", runtime.GOOS, dnsPort)
|
||||
// BLOCK here until stopped (critical - Swift expects this to block!)
|
||||
ctrld.ProxyLogger.Load().Info().Msg("[PacketCapture] Blocking until stop signal...")
|
||||
<-pc.baseController.stopCh
|
||||
ctrld.ProxyLogger.Load().Info().Msg("[PacketCapture] Stop signal received, exiting")
|
||||
|
||||
return nil
|
||||
}
|
||||
@@ -188,22 +181,13 @@ func (pc *PacketCaptureController) handleDNSQuery(query *netstack.DNSQuery) {
|
||||
return
|
||||
}
|
||||
|
||||
// Determine DNS proxy port based on platform
|
||||
// Android: 0.0.0.0:5354
|
||||
// iOS: 127.0.0.1:53
|
||||
dnsProxyAddr := "127.0.0.1:5354" // Default for Android
|
||||
if runtime.GOOS == "ios" || runtime.GOOS == "darwin" {
|
||||
// iOS uses port 53
|
||||
dnsProxyAddr = "127.0.0.1:53"
|
||||
}
|
||||
|
||||
// Send query to actual DNS proxy
|
||||
// Send query to actual DNS proxy using configured address
|
||||
client := &dns.Client{
|
||||
Net: "udp",
|
||||
Timeout: 3 * time.Second,
|
||||
}
|
||||
|
||||
response, _, err := client.Exchange(msg, dnsProxyAddr)
|
||||
response, _, err := client.Exchange(msg, pc.dnsProxyAddress)
|
||||
if err != nil {
|
||||
// Create SERVFAIL response
|
||||
response = new(dns.Msg)
|
||||
@@ -223,41 +207,62 @@ func (pc *PacketCaptureController) handleDNSQuery(query *netstack.DNSQuery) {
|
||||
|
||||
// Stop stops the packet capture controller
|
||||
func (pc *PacketCaptureController) Stop(restart bool, pin int64) int {
|
||||
ctrld.ProxyLogger.Load().Info().Msg("[PacketCapture] Stop() called - starting shutdown")
|
||||
var errorCode = 0
|
||||
|
||||
// Clear global socket protector
|
||||
ctrld.SetSocketProtector(nil)
|
||||
|
||||
// Stop DNS bridge
|
||||
if pc.dnsBridge != nil {
|
||||
ctrld.ProxyLogger.Load().Info().Msg("[PacketCapture] Stop() - stopping DNS bridge")
|
||||
pc.dnsBridge.Stop()
|
||||
pc.dnsBridge = nil
|
||||
ctrld.ProxyLogger.Load().Info().Msg("[PacketCapture] Stop() - DNS bridge stopped")
|
||||
}
|
||||
|
||||
// Stop netstack
|
||||
if pc.netstackCtrl != nil {
|
||||
ctrld.ProxyLogger.Load().Info().Msg("[PacketCapture] Stop() - stopping netstack controller")
|
||||
if err := pc.netstackCtrl.Stop(); err != nil {
|
||||
// Log error but continue shutdown
|
||||
fmt.Printf("Error stopping netstack: %v\n", err)
|
||||
ctrld.ProxyLogger.Load().Error().Msgf("[PacketCapture] Stop() - error stopping netstack: %v", err)
|
||||
}
|
||||
pc.netstackCtrl = nil
|
||||
ctrld.ProxyLogger.Load().Info().Msg("[PacketCapture] Stop() - netstack controller stopped")
|
||||
}
|
||||
|
||||
// Close packet stop channel
|
||||
if pc.packetStopCh != nil {
|
||||
ctrld.ProxyLogger.Load().Info().Msg("[PacketCapture] Stop() - closing packet stop channel")
|
||||
select {
|
||||
case <-pc.packetStopCh:
|
||||
// Already closed
|
||||
ctrld.ProxyLogger.Load().Info().Msg("[PacketCapture] Stop() - packet stop channel already closed")
|
||||
default:
|
||||
close(pc.packetStopCh)
|
||||
ctrld.ProxyLogger.Load().Info().Msg("[PacketCapture] Stop() - packet stop channel closed")
|
||||
}
|
||||
pc.packetStopCh = make(chan struct{})
|
||||
}
|
||||
|
||||
// Stop base controller
|
||||
ctrld.ProxyLogger.Load().Info().Msgf("[PacketCapture] Stop() - stopping base controller (restart=%v, pin=%d)", restart, pin)
|
||||
if !restart {
|
||||
errorCode = cli.CheckDeactivationPin(pin, pc.baseController.stopCh)
|
||||
ctrld.ProxyLogger.Load().Info().Msgf("[PacketCapture] Stop() - deactivation pin check returned: %d", errorCode)
|
||||
}
|
||||
if errorCode == 0 && pc.baseController.stopCh != nil {
|
||||
ctrld.ProxyLogger.Load().Info().Msg("[PacketCapture] Stop() - closing base controller stop channel")
|
||||
select {
|
||||
case <-pc.baseController.stopCh:
|
||||
// Already closed
|
||||
ctrld.ProxyLogger.Load().Info().Msg("[PacketCapture] Stop() - base controller stop channel already closed")
|
||||
default:
|
||||
close(pc.baseController.stopCh)
|
||||
ctrld.ProxyLogger.Load().Info().Msg("[PacketCapture] Stop() - base controller stop channel closed")
|
||||
}
|
||||
pc.baseController.stopCh = nil
|
||||
}
|
||||
|
||||
ctrld.ProxyLogger.Load().Info().Msgf("[PacketCapture] Stop() - shutdown complete, errorCode=%d", errorCode)
|
||||
return errorCode
|
||||
}
|
||||
|
||||
|
||||
Reference in New Issue
Block a user