| 1 | package sdk |
| 2 | |
| 3 | import ( |
| 4 | "bytes" |
| 5 | "context" |
| 6 | "errors" |
| 7 | "fmt" |
| 8 | "io" |
| 9 | "net" |
| 10 | "sync" |
| 11 | "sync/atomic" |
| 12 | "time" |
| 13 | |
| 14 | "github.com/rs/zerolog/log" |
| 15 | |
| 16 | "github.com/gosuda/portal-tunnel/v2/types" |
| 17 | ) |
| 18 | |
| 19 | func ProxyExposure(ctx context.Context, exposure *Exposure) error { |
| 20 | defer exposure.Close() |
| 21 | if len(exposure.ActiveRelayURLs()) == 0 { |
| 22 | return errors.New("no relay URLs provided") |
| 23 | } |
| 24 | |
| 25 | cfg := exposure.Config() |
| 26 | identity := cfg.Identity |
| 27 | tcpTarget := cfg.TargetAddr |
| 28 | udpTarget := cfg.UDPAddr |
| 29 | udpEnabled := udpTarget != "" |
| 30 | |
| 31 | log.Info(). |
| 32 | Str("release_version", types.ReleaseVersion). |
| 33 | Str("tcp_target", tcpTarget). |
| 34 | Str("service_name", identity.Name). |
| 35 | Strs("relays", exposure.ActiveRelayURLs()). |
| 36 | Msg("starting portal tunnel; public URLs will be logged as relays become ready") |
| 37 | if udpEnabled { |
| 38 | log.Info(). |
| 39 | Str("udp_target", udpTarget). |
| 40 | Str("service_name", identity.Name). |
| 41 | Msg("udp relay enabled") |
| 42 | } |
| 43 | |
| 44 | var connWG sync.WaitGroup |
| 45 | var connCount atomic.Int64 |
| 46 | var udpErrCh chan error |
| 47 | |
| 48 | if udpEnabled { |
| 49 | udpErrCh = make(chan error, 1) |
| 50 | go func() { |
| 51 | if err := runUDPProxy(ctx, exposure, udpTarget); err != nil && ctx.Err() == nil { |
| 52 | udpErrCh <- err |
| 53 | _ = exposure.Close() |
| 54 | } |
| 55 | }() |
| 56 | } |
| 57 | |
| 58 | go func() { |
| 59 | <-ctx.Done() |
| 60 | _ = exposure.Close() |
| 61 | }() |
| 62 | |
| 63 | waitErr := proxyRelayConnections(ctx, exposure, tcpTarget, &connWG, &connCount) |
| 64 | if waitErr != nil { |
| 65 | _ = exposure.Close() |
| 66 | } |
| 67 | |
| 68 | var udpErr error |
| 69 | if udpErrCh != nil { |
| 70 | select { |
| 71 | case udpErr = <-udpErrCh: |
| 72 | default: |
| 73 | } |
| 74 | } |
| 75 | |
| 76 | closeErr := exposure.Close() |
| 77 | if waitErr != nil { |
| 78 | log.Error().Err(waitErr).Msg("relay supervisor exited with error") |
| 79 | } |
| 80 | if udpErr != nil { |
| 81 | log.Error().Err(udpErr).Msg("udp proxy exited with error") |
| 82 | } |
| 83 | if closeErr != nil { |
| 84 | log.Warn().Err(closeErr).Msg("relay shutdown completed with cleanup errors") |
| 85 | } |
| 86 | |
| 87 | if ctx.Err() != nil { |
| 88 | log.Info().Msg("tunnel shutting down") |
| 89 | } |
| 90 | |
| 91 | done := make(chan struct{}) |
| 92 | go func() { |
| 93 | connWG.Wait() |
| 94 | close(done) |
| 95 | }() |
| 96 | |
| 97 | select { |
| 98 | case <-done: |
| 99 | case <-time.After(5 * time.Second): |
| 100 | log.Warn().Msg("tunnel shutdown timeout; connections still active") |
| 101 | } |
| 102 | |
| 103 | log.Info().Msg("tunnel shutdown complete") |
| 104 | return errors.Join(waitErr, udpErr, closeErr) |
| 105 | } |
| 106 | |
| 107 | func proxyRelayConnections(ctx context.Context, exposure *Exposure, localAddr string, connWG *sync.WaitGroup, connCount *atomic.Int64) error { |
| 108 | for { |
| 109 | relayConn, err := exposure.Accept() |
| 110 | if err != nil { |
| 111 | switch { |
| 112 | case errors.Is(err, context.Canceled): |
| 113 | return nil |
| 114 | case ctx.Err() != nil: |
| 115 | return ctx.Err() |
| 116 | case errors.Is(err, net.ErrClosed): |
| 117 | return errors.New("all relay listeners stopped") |
| 118 | default: |
| 119 | return err |
| 120 | } |
| 121 | } |
| 122 | |
| 123 | connID := connCount.Add(1) |
| 124 | log.Info(). |
| 125 | Int64("conn_id", connID). |
| 126 | Str("remote_addr", relayConn.RemoteAddr().String()). |
| 127 | Msg("accepted relay connection") |
| 128 | |
| 129 | connWG.Add(1) |
| 130 | go func(connID int64, relayConn net.Conn) { |
| 131 | defer connWG.Done() |
| 132 | if err := proxyConnection(ctx, localAddr, relayConn); err != nil { |
| 133 | log.Debug().Err(err).Int64("conn_id", connID).Msg("proxy connection closed with an I/O error") |
| 134 | } |
| 135 | log.Info().Int64("conn_id", connID).Msg("proxy connection closed") |
| 136 | }(connID, relayConn) |
| 137 | } |
| 138 | } |
| 139 | |
| 140 | var bufferPool = sync.Pool{ |
| 141 | New: func() any { |
| 142 | b := make([]byte, 64*1024) |
| 143 | return &b |
| 144 | }, |
| 145 | } |
| 146 | |
| 147 | func proxyConnection(ctx context.Context, localAddr string, relayConn net.Conn) error { |
| 148 | defer relayConn.Close() |
| 149 | |
| 150 | dialer := &net.Dialer{Timeout: 5 * time.Second} |
| 151 | localConn, err := dialer.DialContext(ctx, "tcp", localAddr) |
| 152 | if err != nil { |
| 153 | return writeEmptyHTTPResponse(relayConn) |
| 154 | } |
| 155 | defer localConn.Close() |
| 156 | |
| 157 | errCh := make(chan error, 2) |
| 158 | stopCh := make(chan struct{}) |
| 159 | |
| 160 | go func() { |
| 161 | select { |
| 162 | case <-ctx.Done(): |
| 163 | _ = relayConn.Close() |
| 164 | _ = localConn.Close() |
| 165 | case <-stopCh: |
| 166 | } |
| 167 | }() |
| 168 | |
| 169 | go func() { |
| 170 | bufPtr := bufferPool.Get().(*[]byte) |
| 171 | defer bufferPool.Put(bufPtr) |
| 172 | _, err := io.CopyBuffer(localConn, relayConn, *bufPtr) |
| 173 | if tcpConn, ok := localConn.(*net.TCPConn); ok { |
| 174 | _ = tcpConn.CloseWrite() |
| 175 | } |
| 176 | errCh <- err |
| 177 | }() |
| 178 | |
| 179 | go func() { |
| 180 | bufPtr := bufferPool.Get().(*[]byte) |
| 181 | defer bufferPool.Put(bufPtr) |
| 182 | _, err := io.CopyBuffer(relayConn, localConn, *bufPtr) |
| 183 | _ = relayConn.Close() |
| 184 | errCh <- err |
| 185 | }() |
| 186 | |
| 187 | var firstErr error |
| 188 | for range 2 { |
| 189 | if err := <-errCh; err != nil && firstErr == nil { |
| 190 | firstErr = err |
| 191 | } |
| 192 | } |
| 193 | |
| 194 | close(stopCh) |
| 195 | if errors.Is(firstErr, io.EOF) || errors.Is(firstErr, net.ErrClosed) { |
| 196 | return nil |
| 197 | } |
| 198 | return firstErr |
| 199 | } |
| 200 | |
| 201 | func writeEmptyHTTPResponse(conn net.Conn) error { |
| 202 | htmlBody := `<!DOCTYPE html> |
| 203 | <html> |
| 204 | <head><title>Service Unavailable</title></head> |
| 205 | <body style="font-family:sans-serif;text-align:center;padding:50px;"> |
| 206 | <h1>Service Unavailable</h1> |
| 207 | <p>The local service is not currently running.</p> |
| 208 | <p>Please start your local application and refresh this page.</p> |
| 209 | </body> |
| 210 | </html>` |
| 211 | response := fmt.Sprintf("HTTP/1.1 503 Service Unavailable\r\n"+ |
| 212 | "Content-Type: text/html; charset=utf-8\r\n"+ |
| 213 | "Content-Length: %d\r\n"+ |
| 214 | "Connection: close\r\n"+ |
| 215 | "\r\n%s", len(htmlBody), htmlBody) |
| 216 | _, err := conn.Write([]byte(response)) |
| 217 | return err |
| 218 | } |
| 219 | |
| 220 | // runUDPProxy waits for the exposure datagram plane and proxies it to the |
| 221 | // configured local UDP target. |
| 222 | func runUDPProxy(ctx context.Context, exposure *Exposure, udpTarget string) error { |
| 223 | udpAddrs, err := exposure.WaitDatagramReady(ctx) |
| 224 | if err != nil { |
| 225 | if ctx.Err() != nil || errors.Is(err, context.Canceled) { |
| 226 | return ctx.Err() |
| 227 | } |
| 228 | return fmt.Errorf("wait for udp readiness: %w", err) |
| 229 | } |
| 230 | if len(udpAddrs) == 0 { |
| 231 | if ctx.Err() != nil { |
| 232 | return ctx.Err() |
| 233 | } |
| 234 | return errors.New("relay did not expose any UDP listeners") |
| 235 | } |
| 236 | |
| 237 | for _, udpAddr := range udpAddrs { |
| 238 | log.Info(). |
| 239 | Str("udp_addr", udpAddr). |
| 240 | Msg("UDP tunnel ready") |
| 241 | } |
| 242 | |
| 243 | return proxyExposureDatagrams(ctx, exposure, udpTarget) |
| 244 | } |
| 245 | |
| 246 | // proxyExposureDatagrams receives datagrams from the exposure datagram plane |
| 247 | // and forwards them to the local UDP service, relaying responses back. |
| 248 | func proxyExposureDatagrams(ctx context.Context, exposure *Exposure, localAddr string) error { |
| 249 | resolvedAddr, err := net.ResolveUDPAddr("udp", localAddr) |
| 250 | if err != nil { |
| 251 | return fmt.Errorf("resolve udp addr %q: %w", localAddr, err) |
| 252 | } |
| 253 | |
| 254 | mgr := newUDPFlowManager(resolvedAddr, exposure) |
| 255 | go mgr.runCleanup(ctx) |
| 256 | |
| 257 | log.Info().Str("target", localAddr).Msg("udp proxy loop started, waiting for datagrams") |
| 258 | for { |
| 259 | frame, err := exposure.AcceptDatagram() |
| 260 | if err != nil { |
| 261 | if ctx.Err() != nil { |
| 262 | return ctx.Err() |
| 263 | } |
| 264 | if errors.Is(err, net.ErrClosed) { |
| 265 | break |
| 266 | } |
| 267 | return fmt.Errorf("accept datagram: %w", err) |
| 268 | } |
| 269 | |
| 270 | log.Debug(). |
| 271 | Uint32("flow_id", frame.FlowID). |
| 272 | Int("bytes", len(frame.Payload)). |
| 273 | Str("address", frame.Address). |
| 274 | Str("relay_url", frame.RelayURL). |
| 275 | Str("udp_addr", frame.UDPAddr). |
| 276 | Str("target", localAddr). |
| 277 | Msg("datagram received from relay, forwarding to local") |
| 278 | |
| 279 | localConn, err := mgr.getOrCreate(ctx, frame) |
| 280 | if err != nil { |
| 281 | log.Warn(). |
| 282 | Err(err). |
| 283 | Uint32("flow_id", frame.FlowID). |
| 284 | Str("address", frame.Address). |
| 285 | Str("relay_url", frame.RelayURL). |
| 286 | Msg("dial local udp failed") |
| 287 | continue |
| 288 | } |
| 289 | |
| 290 | if _, err := localConn.Write(frame.Payload); err != nil { |
| 291 | log.Warn(). |
| 292 | Err(err). |
| 293 | Uint32("flow_id", frame.FlowID). |
| 294 | Str("address", frame.Address). |
| 295 | Str("relay_url", frame.RelayURL). |
| 296 | Msg("write to local udp failed") |
| 297 | } |
| 298 | } |
| 299 | |
| 300 | return nil |
| 301 | } |
| 302 | |
| 303 | type udpFlowKey struct { |
| 304 | flowID uint32 |
| 305 | address string |
| 306 | relayURL string |
| 307 | } |
| 308 | |
| 309 | type udpFlowEntry struct { |
| 310 | conn *net.UDPConn |
| 311 | lastSeen time.Time |
| 312 | frame types.DatagramFrame |
| 313 | } |
| 314 | |
| 315 | type udpFlowManager struct { |
| 316 | target *net.UDPAddr |
| 317 | exposure *Exposure |
| 318 | mu sync.Mutex |
| 319 | flows map[udpFlowKey]*udpFlowEntry |
| 320 | } |
| 321 | |
| 322 | func newUDPFlowManager(target *net.UDPAddr, exposure *Exposure) *udpFlowManager { |
| 323 | return &udpFlowManager{ |
| 324 | target: target, |
| 325 | exposure: exposure, |
| 326 | flows: make(map[udpFlowKey]*udpFlowEntry), |
| 327 | } |
| 328 | } |
| 329 | |
| 330 | func (m *udpFlowManager) runCleanup(ctx context.Context) { |
| 331 | ticker := time.NewTicker(15 * time.Second) |
| 332 | defer ticker.Stop() |
| 333 | for { |
| 334 | select { |
| 335 | case <-ctx.Done(): |
| 336 | return |
| 337 | case <-ticker.C: |
| 338 | m.mu.Lock() |
| 339 | now := time.Now() |
| 340 | for key, f := range m.flows { |
| 341 | if now.Sub(f.lastSeen) > 30*time.Second { |
| 342 | _ = f.conn.Close() |
| 343 | delete(m.flows, key) |
| 344 | } |
| 345 | } |
| 346 | m.mu.Unlock() |
| 347 | } |
| 348 | } |
| 349 | } |
| 350 | |
| 351 | func (m *udpFlowManager) getOrCreate(ctx context.Context, frame types.DatagramFrame) (*net.UDPConn, error) { |
| 352 | key := udpFlowKey{ |
| 353 | flowID: frame.FlowID, |
| 354 | address: frame.Address, |
| 355 | relayURL: frame.RelayURL, |
| 356 | } |
| 357 | |
| 358 | m.mu.Lock() |
| 359 | if f, ok := m.flows[key]; ok { |
| 360 | f.lastSeen = time.Now() |
| 361 | m.mu.Unlock() |
| 362 | return f.conn, nil |
| 363 | } |
| 364 | m.mu.Unlock() |
| 365 | |
| 366 | localConn, err := net.DialUDP("udp", nil, m.target) |
| 367 | if err != nil { |
| 368 | return nil, err |
| 369 | } |
| 370 | |
| 371 | m.mu.Lock() |
| 372 | if f, ok := m.flows[key]; ok { |
| 373 | m.mu.Unlock() |
| 374 | _ = localConn.Close() |
| 375 | f.lastSeen = time.Now() |
| 376 | return f.conn, nil |
| 377 | } |
| 378 | m.flows[key] = &udpFlowEntry{ |
| 379 | conn: localConn, |
| 380 | lastSeen: time.Now(), |
| 381 | frame: types.DatagramFrame{ |
| 382 | FlowID: frame.FlowID, |
| 383 | Address: frame.Address, |
| 384 | RelayURL: frame.RelayURL, |
| 385 | UDPAddr: frame.UDPAddr, |
| 386 | }, |
| 387 | } |
| 388 | m.mu.Unlock() |
| 389 | |
| 390 | go m.readLoop(ctx, key, localConn) |
| 391 | return localConn, nil |
| 392 | } |
| 393 | |
| 394 | func (m *udpFlowManager) removeFlow(key udpFlowKey) { |
| 395 | m.mu.Lock() |
| 396 | if f, ok := m.flows[key]; ok { |
| 397 | _ = f.conn.Close() |
| 398 | delete(m.flows, key) |
| 399 | } |
| 400 | m.mu.Unlock() |
| 401 | } |
| 402 | |
| 403 | func (m *udpFlowManager) readLoop(ctx context.Context, key udpFlowKey, conn *net.UDPConn) { |
| 404 | buf := make([]byte, 65535) |
| 405 | for { |
| 406 | n, err := conn.Read(buf) |
| 407 | if err != nil { |
| 408 | if ctx.Err() != nil { |
| 409 | return |
| 410 | } |
| 411 | log.Debug(). |
| 412 | Err(err). |
| 413 | Uint32("flow_id", key.flowID). |
| 414 | Str("address", key.address). |
| 415 | Str("relay_url", key.relayURL). |
| 416 | Msg("local read ended") |
| 417 | m.removeFlow(key) |
| 418 | return |
| 419 | } |
| 420 | |
| 421 | m.mu.Lock() |
| 422 | entry := m.flows[key] |
| 423 | if entry == nil { |
| 424 | m.mu.Unlock() |
| 425 | return |
| 426 | } |
| 427 | entry.lastSeen = time.Now() |
| 428 | replyFrame := entry.frame |
| 429 | replyFrame.Payload = bytes.Clone(buf[:n]) |
| 430 | m.mu.Unlock() |
| 431 | |
| 432 | if sendErr := m.exposure.SendDatagram(replyFrame); sendErr != nil { |
| 433 | log.Debug(). |
| 434 | Err(sendErr). |
| 435 | Uint32("flow_id", key.flowID). |
| 436 | Str("address", key.address). |
| 437 | Str("relay_url", key.relayURL). |
| 438 | Msg("send datagram to relay failed") |
| 439 | m.removeFlow(key) |
| 440 | return |
| 441 | } |
| 442 | } |
| 443 | } |