cloudflare/cloudflared
Publicmirrored from https://github.com/cloudflare/cloudflaredAvailable
h2mux/h2mux.go
427lines · modecode
| 1 | package h2mux |
| 2 | |
| 3 | import ( |
| 4 | "bytes" |
| 5 | "context" |
| 6 | "io" |
| 7 | "strings" |
| 8 | "sync" |
| 9 | "time" |
| 10 | |
| 11 | log "github.com/sirupsen/logrus" |
| 12 | "golang.org/x/net/http2" |
| 13 | "golang.org/x/net/http2/hpack" |
| 14 | "golang.org/x/sync/errgroup" |
| 15 | ) |
| 16 | |
| 17 | const ( |
| 18 | defaultFrameSize uint32 = 1 << 14 // Minimum frame size in http2 spec |
| 19 | defaultWindowSize uint32 = (1 << 16) - 1 // Minimum window size in http2 spec |
| 20 | maxWindowSize uint32 = (1 << 31) - 1 // 2^31-1 = 2147483647, max window size in http2 spec |
| 21 | defaultTimeout time.Duration = 5 * time.Second |
| 22 | defaultRetries uint64 = 5 |
| 23 | defaultWriteBufferMaxLen int = 1024 * 1024 * 512 // 500mb |
| 24 | |
| 25 | SettingMuxerMagic http2.SettingID = 0x42db |
| 26 | MuxerMagicOrigin uint32 = 0xa2e43c8b |
| 27 | MuxerMagicEdge uint32 = 0x1088ebf9 |
| 28 | ) |
| 29 | |
| 30 | type MuxedStreamHandler interface { |
| 31 | ServeStream(*MuxedStream) error |
| 32 | } |
| 33 | |
| 34 | type MuxedStreamFunc func(stream *MuxedStream) error |
| 35 | |
| 36 | func (f MuxedStreamFunc) ServeStream(stream *MuxedStream) error { |
| 37 | return f(stream) |
| 38 | } |
| 39 | |
| 40 | type MuxerConfig struct { |
| 41 | Timeout time.Duration |
| 42 | Handler MuxedStreamHandler |
| 43 | IsClient bool |
| 44 | // Name is used to identify this muxer instance when logging. |
| 45 | Name string |
| 46 | // The minimum time this connection can be idle before sending a heartbeat. |
| 47 | HeartbeatInterval time.Duration |
| 48 | // The minimum number of heartbeats to send before terminating the connection. |
| 49 | MaxHeartbeats uint64 |
| 50 | // Logger to use |
| 51 | Logger *log.Entry |
| 52 | CompressionQuality CompressionSetting |
| 53 | // Initial size for HTTP2 flow control windows |
| 54 | DefaultWindowSize uint32 |
| 55 | // Largest allowable size for HTTP2 flow control windows |
| 56 | MaxWindowSize uint32 |
| 57 | // Largest allowable capacity for the buffer of data to be sent |
| 58 | StreamWriteBufferMaxLen int |
| 59 | } |
| 60 | |
| 61 | type Muxer struct { |
| 62 | // f is used to read and write HTTP2 frames on the wire. |
| 63 | f *http2.Framer |
| 64 | // config is the MuxerConfig given in Handshake. |
| 65 | config MuxerConfig |
| 66 | // w, r are references to the underlying connection used. |
| 67 | w io.WriteCloser |
| 68 | r io.ReadCloser |
| 69 | // muxReader is the read process. |
| 70 | muxReader *MuxReader |
| 71 | // muxWriter is the write process. |
| 72 | muxWriter *MuxWriter |
| 73 | // muxMetricsUpdater is the process to update metrics |
| 74 | muxMetricsUpdater muxMetricsUpdater |
| 75 | // newStreamChan is used to create new streams on the writer thread. |
| 76 | // The writer will assign the next available stream ID. |
| 77 | newStreamChan chan MuxedStreamRequest |
| 78 | // abortChan is used to abort the writer event loop. |
| 79 | abortChan chan struct{} |
| 80 | // abortOnce is used to ensure abortChan is closed once only. |
| 81 | abortOnce sync.Once |
| 82 | // readyList is used to signal writable streams. |
| 83 | readyList *ReadyList |
| 84 | // streams tracks currently-open streams. |
| 85 | streams *activeStreamMap |
| 86 | // explicitShutdown records whether the Muxer is closing because Shutdown was called, or due to another |
| 87 | // error. |
| 88 | explicitShutdown *BooleanFuse |
| 89 | |
| 90 | compressionQuality CompressionPreset |
| 91 | } |
| 92 | |
| 93 | type Header struct { |
| 94 | Name, Value string |
| 95 | } |
| 96 | |
| 97 | // Handshake establishes a muxed connection with the peer. |
| 98 | // After the handshake completes, it is possible to open and accept streams. |
| 99 | func Handshake( |
| 100 | w io.WriteCloser, |
| 101 | r io.ReadCloser, |
| 102 | config MuxerConfig, |
| 103 | ) (*Muxer, error) { |
| 104 | // Set default config values |
| 105 | if config.Timeout == 0 { |
| 106 | config.Timeout = defaultTimeout |
| 107 | } |
| 108 | if config.DefaultWindowSize == 0 { |
| 109 | config.DefaultWindowSize = defaultWindowSize |
| 110 | } |
| 111 | if config.MaxWindowSize == 0 { |
| 112 | config.MaxWindowSize = maxWindowSize |
| 113 | } |
| 114 | if config.StreamWriteBufferMaxLen == 0 { |
| 115 | config.StreamWriteBufferMaxLen = defaultWriteBufferMaxLen |
| 116 | } |
| 117 | // Initialise connection state fields |
| 118 | m := &Muxer{ |
| 119 | f: http2.NewFramer(w, r), // A framer that writes to w and reads from r |
| 120 | config: config, |
| 121 | w: w, |
| 122 | r: r, |
| 123 | newStreamChan: make(chan MuxedStreamRequest), |
| 124 | abortChan: make(chan struct{}), |
| 125 | readyList: NewReadyList(), |
| 126 | streams: newActiveStreamMap(config.IsClient), |
| 127 | } |
| 128 | |
| 129 | m.f.ReadMetaHeaders = hpack.NewDecoder(4096, func(hpack.HeaderField) {}) |
| 130 | // Initialise the settings to identify this connection and confirm the other end is sane. |
| 131 | handshakeSetting := http2.Setting{ID: SettingMuxerMagic, Val: MuxerMagicEdge} |
| 132 | compressionSetting := http2.Setting{ID: SettingCompression, Val: config.CompressionQuality.toH2Setting()} |
| 133 | if CompressionIsSupported() { |
| 134 | log.Debug("Compression is supported") |
| 135 | m.compressionQuality = config.CompressionQuality.getPreset() |
| 136 | } else { |
| 137 | log.Debug("Compression is not supported") |
| 138 | compressionSetting = http2.Setting{ID: SettingCompression, Val: 0} |
| 139 | } |
| 140 | |
| 141 | expectedMagic := MuxerMagicOrigin |
| 142 | if config.IsClient { |
| 143 | handshakeSetting.Val = MuxerMagicOrigin |
| 144 | expectedMagic = MuxerMagicEdge |
| 145 | } |
| 146 | errChan := make(chan error, 2) |
| 147 | // Simultaneously send our settings and verify the peer's settings. |
| 148 | go func() { errChan <- m.f.WriteSettings(handshakeSetting, compressionSetting) }() |
| 149 | go func() { errChan <- m.readPeerSettings(expectedMagic) }() |
| 150 | err := joinErrorsWithTimeout(errChan, 2, config.Timeout, ErrHandshakeTimeout) |
| 151 | if err != nil { |
| 152 | return nil, err |
| 153 | } |
| 154 | // Confirm sanity by ACKing the frame and expecting an ACK for our frame. |
| 155 | // Not strictly necessary, but let's pretend to be H2-like. |
| 156 | go func() { errChan <- m.f.WriteSettingsAck() }() |
| 157 | go func() { errChan <- m.readPeerSettingsAck() }() |
| 158 | err = joinErrorsWithTimeout(errChan, 2, config.Timeout, ErrHandshakeTimeout) |
| 159 | if err != nil { |
| 160 | return nil, err |
| 161 | } |
| 162 | |
| 163 | // set up reader/writer pair ready for serve |
| 164 | streamErrors := NewStreamErrorMap() |
| 165 | goAwayChan := make(chan http2.ErrCode, 1) |
| 166 | inBoundCounter := NewAtomicCounter(0) |
| 167 | outBoundCounter := NewAtomicCounter(0) |
| 168 | pingTimestamp := NewPingTimestamp() |
| 169 | connActive := NewSignal() |
| 170 | idleDuration := config.HeartbeatInterval |
| 171 | // Sanity check to enusre idelDuration is sane |
| 172 | if idleDuration == 0 || idleDuration < defaultTimeout { |
| 173 | idleDuration = defaultTimeout |
| 174 | config.Logger.Warn("Minimum idle time has been adjusted to ", defaultTimeout) |
| 175 | } |
| 176 | maxRetries := config.MaxHeartbeats |
| 177 | if maxRetries == 0 { |
| 178 | maxRetries = defaultRetries |
| 179 | config.Logger.Warn("Minimum number of unacked heartbeats to send before closing the connection has been adjusted to ", maxRetries) |
| 180 | } |
| 181 | |
| 182 | compBytesBefore, compBytesAfter := NewAtomicCounter(0), NewAtomicCounter(0) |
| 183 | |
| 184 | m.muxMetricsUpdater = newMuxMetricsUpdater( |
| 185 | m.abortChan, |
| 186 | compBytesBefore, |
| 187 | compBytesAfter, |
| 188 | ) |
| 189 | |
| 190 | m.explicitShutdown = NewBooleanFuse() |
| 191 | m.muxReader = &MuxReader{ |
| 192 | f: m.f, |
| 193 | handler: m.config.Handler, |
| 194 | streams: m.streams, |
| 195 | readyList: m.readyList, |
| 196 | streamErrors: streamErrors, |
| 197 | goAwayChan: goAwayChan, |
| 198 | abortChan: m.abortChan, |
| 199 | pingTimestamp: pingTimestamp, |
| 200 | connActive: connActive, |
| 201 | initialStreamWindow: m.config.DefaultWindowSize, |
| 202 | streamWindowMax: m.config.MaxWindowSize, |
| 203 | streamWriteBufferMaxLen: m.config.StreamWriteBufferMaxLen, |
| 204 | r: m.r, |
| 205 | metricsUpdater: m.muxMetricsUpdater, |
| 206 | bytesRead: inBoundCounter, |
| 207 | } |
| 208 | m.muxWriter = &MuxWriter{ |
| 209 | f: m.f, |
| 210 | streams: m.streams, |
| 211 | streamErrors: streamErrors, |
| 212 | readyStreamChan: m.readyList.ReadyChannel(), |
| 213 | newStreamChan: m.newStreamChan, |
| 214 | goAwayChan: goAwayChan, |
| 215 | abortChan: m.abortChan, |
| 216 | pingTimestamp: pingTimestamp, |
| 217 | idleTimer: NewIdleTimer(idleDuration, maxRetries), |
| 218 | connActiveChan: connActive.WaitChannel(), |
| 219 | maxFrameSize: defaultFrameSize, |
| 220 | metricsUpdater: m.muxMetricsUpdater, |
| 221 | bytesWrote: outBoundCounter, |
| 222 | } |
| 223 | m.muxWriter.headerEncoder = hpack.NewEncoder(&m.muxWriter.headerBuffer) |
| 224 | |
| 225 | if m.compressionQuality.dictSize > 0 && m.compressionQuality.nDicts > 0 { |
| 226 | nd, sz := m.compressionQuality.nDicts, m.compressionQuality.dictSize |
| 227 | writeDicts, dictChan := newH2WriteDictionaries( |
| 228 | nd, |
| 229 | sz, |
| 230 | m.compressionQuality.quality, |
| 231 | compBytesBefore, |
| 232 | compBytesAfter, |
| 233 | ) |
| 234 | readDicts := newH2ReadDictionaries(nd, sz) |
| 235 | m.muxReader.dictionaries = h2Dictionaries{read: &readDicts, write: writeDicts} |
| 236 | m.muxWriter.useDictChan = dictChan |
| 237 | } |
| 238 | |
| 239 | return m, nil |
| 240 | } |
| 241 | |
| 242 | func (m *Muxer) readPeerSettings(magic uint32) error { |
| 243 | frame, err := m.f.ReadFrame() |
| 244 | if err != nil { |
| 245 | return err |
| 246 | } |
| 247 | settingsFrame, ok := frame.(*http2.SettingsFrame) |
| 248 | if !ok { |
| 249 | return ErrBadHandshakeNotSettings |
| 250 | } |
| 251 | if settingsFrame.Header().Flags != 0 { |
| 252 | return ErrBadHandshakeUnexpectedAck |
| 253 | } |
| 254 | peerMagic, ok := settingsFrame.Value(SettingMuxerMagic) |
| 255 | if !ok { |
| 256 | return ErrBadHandshakeNoMagic |
| 257 | } |
| 258 | if magic != peerMagic { |
| 259 | return ErrBadHandshakeWrongMagic |
| 260 | } |
| 261 | peerCompression, ok := settingsFrame.Value(SettingCompression) |
| 262 | if !ok { |
| 263 | m.compressionQuality = compressionPresets[CompressionNone] |
| 264 | return nil |
| 265 | } |
| 266 | ver, fmt, sz, nd := parseCompressionSettingVal(peerCompression) |
| 267 | if ver != compressionVersion || fmt != compressionFormat || sz == 0 || nd == 0 { |
| 268 | m.compressionQuality = compressionPresets[CompressionNone] |
| 269 | return nil |
| 270 | } |
| 271 | // Values used for compression are the mimimum between the two peers |
| 272 | if sz < m.compressionQuality.dictSize { |
| 273 | m.compressionQuality.dictSize = sz |
| 274 | } |
| 275 | if nd < m.compressionQuality.nDicts { |
| 276 | m.compressionQuality.nDicts = nd |
| 277 | } |
| 278 | return nil |
| 279 | } |
| 280 | |
| 281 | func (m *Muxer) readPeerSettingsAck() error { |
| 282 | frame, err := m.f.ReadFrame() |
| 283 | if err != nil { |
| 284 | return err |
| 285 | } |
| 286 | settingsFrame, ok := frame.(*http2.SettingsFrame) |
| 287 | if !ok { |
| 288 | return ErrBadHandshakeNotSettingsAck |
| 289 | } |
| 290 | if settingsFrame.Header().Flags != http2.FlagSettingsAck { |
| 291 | return ErrBadHandshakeUnexpectedSettings |
| 292 | } |
| 293 | return nil |
| 294 | } |
| 295 | |
| 296 | func joinErrorsWithTimeout(errChan <-chan error, receiveCount int, timeout time.Duration, timeoutError error) error { |
| 297 | for i := 0; i < receiveCount; i++ { |
| 298 | select { |
| 299 | case err := <-errChan: |
| 300 | if err != nil { |
| 301 | return err |
| 302 | } |
| 303 | case <-time.After(timeout): |
| 304 | return timeoutError |
| 305 | } |
| 306 | } |
| 307 | return nil |
| 308 | } |
| 309 | |
| 310 | // Serve runs the event loops that comprise h2mux: |
| 311 | // - MuxReader.run() |
| 312 | // - MuxWriter.run() |
| 313 | // - muxMetricsUpdater.run() |
| 314 | // In the normal case, Shutdown() is called concurrently with Serve() to stop |
| 315 | // these loops. |
| 316 | func (m *Muxer) Serve(ctx context.Context) error { |
| 317 | errGroup, _ := errgroup.WithContext(ctx) |
| 318 | errGroup.Go(func() error { |
| 319 | err := m.muxReader.run(m.config.Logger) |
| 320 | m.explicitShutdown.Fuse(false) |
| 321 | m.r.Close() |
| 322 | m.abort() |
| 323 | return err |
| 324 | }) |
| 325 | |
| 326 | errGroup.Go(func() error { |
| 327 | err := m.muxWriter.run(m.config.Logger) |
| 328 | m.explicitShutdown.Fuse(false) |
| 329 | m.w.Close() |
| 330 | m.abort() |
| 331 | return err |
| 332 | }) |
| 333 | |
| 334 | errGroup.Go(func() error { |
| 335 | err := m.muxMetricsUpdater.run(m.config.Logger) |
| 336 | return err |
| 337 | }) |
| 338 | |
| 339 | err := errGroup.Wait() |
| 340 | if isUnexpectedTunnelError(err, m.explicitShutdown.Value()) { |
| 341 | return err |
| 342 | } |
| 343 | return nil |
| 344 | } |
| 345 | |
| 346 | // Shutdown is called to initiate the "happy path" of muxer termination. |
| 347 | func (m *Muxer) Shutdown() { |
| 348 | m.explicitShutdown.Fuse(true) |
| 349 | m.muxReader.Shutdown() |
| 350 | } |
| 351 | |
| 352 | // IsUnexpectedTunnelError identifies errors that are expected when shutting down the h2mux tunnel. |
| 353 | // The set of expected errors change depending on whether we initiated shutdown or not. |
| 354 | func isUnexpectedTunnelError(err error, expectedShutdown bool) bool { |
| 355 | if err == nil { |
| 356 | return false |
| 357 | } |
| 358 | if !expectedShutdown { |
| 359 | return true |
| 360 | } |
| 361 | return !isConnectionClosedError(err) |
| 362 | } |
| 363 | |
| 364 | func isConnectionClosedError(err error) bool { |
| 365 | if err == io.EOF { |
| 366 | return true |
| 367 | } |
| 368 | if err == io.ErrClosedPipe { |
| 369 | return true |
| 370 | } |
| 371 | if err.Error() == "tls: use of closed connection" { |
| 372 | return true |
| 373 | } |
| 374 | if strings.HasSuffix(err.Error(), "use of closed network connection") { |
| 375 | return true |
| 376 | } |
| 377 | return false |
| 378 | } |
| 379 | |
| 380 | // OpenStream opens a new data stream with the given headers. |
| 381 | // Called by proxy server and tunnel |
| 382 | func (m *Muxer) OpenStream(headers []Header, body io.Reader) (*MuxedStream, error) { |
| 383 | stream := &MuxedStream{ |
| 384 | responseHeadersReceived: make(chan struct{}), |
| 385 | readBuffer: NewSharedBuffer(), |
| 386 | writeBuffer: &bytes.Buffer{}, |
| 387 | writeBufferMaxLen: m.config.StreamWriteBufferMaxLen, |
| 388 | writeBufferHasSpace: make(chan struct{}, 1), |
| 389 | receiveWindow: m.config.DefaultWindowSize, |
| 390 | receiveWindowCurrentMax: m.config.DefaultWindowSize, |
| 391 | receiveWindowMax: m.config.MaxWindowSize, |
| 392 | sendWindow: m.config.DefaultWindowSize, |
| 393 | readyList: m.readyList, |
| 394 | writeHeaders: headers, |
| 395 | dictionaries: m.muxReader.dictionaries, |
| 396 | } |
| 397 | |
| 398 | select { |
| 399 | // Will be received by mux writer |
| 400 | case m.newStreamChan <- MuxedStreamRequest{stream: stream, body: body}: |
| 401 | case <-m.abortChan: |
| 402 | return nil, ErrConnectionClosed |
| 403 | } |
| 404 | select { |
| 405 | case <-stream.responseHeadersReceived: |
| 406 | return stream, nil |
| 407 | case <-m.abortChan: |
| 408 | return nil, ErrConnectionClosed |
| 409 | } |
| 410 | } |
| 411 | |
| 412 | func (m *Muxer) Metrics() *MuxerMetrics { |
| 413 | return m.muxMetricsUpdater.metrics() |
| 414 | } |
| 415 | |
| 416 | func (m *Muxer) abort() { |
| 417 | m.abortOnce.Do(func() { |
| 418 | close(m.abortChan) |
| 419 | m.readyList.Close() |
| 420 | m.streams.Abort() |
| 421 | }) |
| 422 | } |
| 423 | |
| 424 | // Return how many retries/ticks since the connection was last marked active |
| 425 | func (m *Muxer) TimerRetries() uint64 { |
| 426 | return m.muxWriter.idleTimer.RetryCount() |
| 427 | } |
| 428 | |