// Copyright 2014 The Go Authors. All rights reserved. // Use of this source code is governed by a BSD-style // license that can be found in the LICENSE file. // TODO: turn off the serve goroutine when idle, so // an idle conn only has the readFrames goroutine active. (which could // also be optimized probably to pin less memory in crypto/tls). This // would involve tracking when the serve goroutine is active (atomic // int32 read/CAS probably?) and starting it up when frames arrive, // and shutting it down when all handlers exit. the occasional PING // packets could use time.AfterFunc to call sc.wakeStartServeLoop() // (which is a no-op if already running) and then queue the PING write // as normal. The serve loop would then exit in most cases (if no // Handlers running) and not be woken up again until the PING packet // returns. // TODO (maybe): add a mechanism for Handlers to going into // half-closed-local mode (rw.(io.Closer) test?) but not exit their // handler, and continue to be able to read from the // Request.Body. This would be a somewhat semantic change from HTTP/1 // (or at least what we expose in net/http), so I'd probably want to // add it there too. For now, this package says that returning from // the Handler ServeHTTP function means you're both done reading and // done writing, without a way to stop just one or the other. package http2 import ( "bufio" "bytes" "context" "crypto/tls" "errors" "fmt" "io" "log" "math" "net" "net/http" "net/textproto" "net/url" "os" "reflect" "runtime" "strconv" "strings" "sync" "time" "golang.org/x/net/http/httpguts" "golang.org/x/net/http2/hpack" ) const ( prefaceTimeout = 10 * time.Second firstSettingsTimeout = 2 * time.Second // should be in-flight with preface anyway handlerChunkWriteSize = 4 << 10 defaultMaxStreams = 250 // TODO: make this 100 as the GFE seems to? maxQueuedControlFrames = 10000 ) var ( errClientDisconnected = errors.New("client disconnected") errClosedBody = errors.New("body closed by handler") errHandlerComplete = errors.New("http2: request body closed due to handler exiting") errStreamClosed = errors.New("http2: stream closed") ) var responseWriterStatePool = sync.Pool{ New: func() interface{} { rws := &responseWriterState{} rws.bw = bufio.NewWriterSize(chunkWriter{rws}, handlerChunkWriteSize) return rws }, } // Test hooks. var ( testHookOnConn func() testHookGetServerConn func(*serverConn) testHookOnPanicMu *sync.Mutex // nil except in tests testHookOnPanic func(sc *serverConn, panicVal interface{}) (rePanic bool) ) // Server is an HTTP/2 server. type Server struct { // MaxHandlers limits the number of http.Handler ServeHTTP goroutines // which may run at a time over all connections. // Negative or zero no limit. // TODO: implement MaxHandlers int // MaxConcurrentStreams optionally specifies the number of // concurrent streams that each client may have open at a // time. This is unrelated to the number of http.Handler goroutines // which may be active globally, which is MaxHandlers. // If zero, MaxConcurrentStreams defaults to at least 100, per // the HTTP/2 spec's recommendations. MaxConcurrentStreams uint32 // MaxReadFrameSize optionally specifies the largest frame // this server is willing to read. A valid value is between // 16k and 16M, inclusive. If zero or otherwise invalid, a // default value is used. MaxReadFrameSize uint32 // PermitProhibitedCipherSuites, if true, permits the use of // cipher suites prohibited by the HTTP/2 spec. PermitProhibitedCipherSuites bool // IdleTimeout specifies how long until idle clients should be // closed with a GOAWAY frame. PING frames are not considered // activity for the purposes of IdleTimeout. IdleTimeout time.Duration // MaxUploadBufferPerConnection is the size of the initial flow // control window for each connections. The HTTP/2 spec does not // allow this to be smaller than 65535 or larger than 2^32-1. // If the value is outside this range, a default value will be // used instead. MaxUploadBufferPerConnection int32 // MaxUploadBufferPerStream is the size of the initial flow control // window for each stream. The HTTP/2 spec does not allow this to // be larger than 2^32-1. If the value is zero or larger than the // maximum, a default value will be used instead. MaxUploadBufferPerStream int32 // NewWriteScheduler constructs a write scheduler for a connection. // If nil, a default scheduler is chosen. NewWriteScheduler func() WriteScheduler // Internal state. This is a pointer (rather than embedded directly) // so that we don't embed a Mutex in this struct, which will make the // struct non-copyable, which might break some callers. state *serverInternalState } func (s *Server) initialConnRecvWindowSize() int32 { if s.MaxUploadBufferPerConnection > initialWindowSize { return s.MaxUploadBufferPerConnection } return 1 << 20 } func (s *Server) initialStreamRecvWindowSize() int32 { if s.MaxUploadBufferPerStream > 0 { return s.MaxUploadBufferPerStream } return 1 << 20 } func (s *Server) maxReadFrameSize() uint32 { if v := s.MaxReadFrameSize; v >= minMaxFrameSize && v <= maxFrameSize { return v } return defaultMaxReadFrameSize } func (s *Server) maxConcurrentStreams() uint32 { if v := s.MaxConcurrentStreams; v > 0 { return v } return defaultMaxStreams } // maxQueuedControlFrames is the maximum number of control frames like // SETTINGS, PING and RST_STREAM that will be queued for writing before // the connection is closed to prevent memory exhaustion attacks. func (s *Server) maxQueuedControlFrames() int { // TODO: if anybody asks, add a Server field, and remember to define the // behavior of negative values. return maxQueuedControlFrames } type serverInternalState struct { mu sync.Mutex activeConns map[*serverConn]struct{} } func (s *serverInternalState) registerConn(sc *serverConn) { if s == nil { return // if the Server was used without calling ConfigureServer } s.mu.Lock() s.activeConns[sc] = struct{}{} s.mu.Unlock() } func (s *serverInternalState) unregisterConn(sc *serverConn) { if s == nil { return // if the Server was used without calling ConfigureServer } s.mu.Lock() delete(s.activeConns, sc) s.mu.Unlock() } func (s *serverInternalState) startGracefulShutdown() { if s == nil { return // if the Server was used without calling ConfigureServer } s.mu.Lock() for sc := range s.activeConns { sc.startGracefulShutdown() } s.mu.Unlock() } // ConfigureServer adds HTTP/2 support to a net/http Server. // // The configuration conf may be nil. // // ConfigureServer must be called before s begins serving. func ConfigureServer(s *http.Server, conf *Server) error { if s == nil { panic("nil *http.Server") } if conf == nil { conf = new(Server) } conf.state = &serverInternalState{activeConns: make(map[*serverConn]struct{})} if h1, h2 := s, conf; h2.IdleTimeout == 0 { if h1.IdleTimeout != 0 { h2.IdleTimeout = h1.IdleTimeout } else { h2.IdleTimeout = h1.ReadTimeout } } s.RegisterOnShutdown(conf.state.startGracefulShutdown) if s.TLSConfig == nil { s.TLSConfig = new(tls.Config) } else if s.TLSConfig.CipherSuites != nil { // If they already provided a CipherSuite list, return // an error if it has a bad order or is missing // ECDHE_RSA_WITH_AES_128_GCM_SHA256 or ECDHE_ECDSA_WITH_AES_128_GCM_SHA256. haveRequired := false sawBad := false for i, cs := range s.TLSConfig.CipherSuites { switch cs { case tls.TLS_ECDHE_RSA_WITH_AES_128_GCM_SHA256, // Alternative MTI cipher to not discourage ECDSA-only servers. // See http://golang.org/cl/30721 for further information. tls.TLS_ECDHE_ECDSA_WITH_AES_128_GCM_SHA256: haveRequired = true } if isBadCipher(cs) { sawBad = true } else if sawBad { return fmt.Errorf("http2: TLSConfig.CipherSuites index %d contains an HTTP/2-approved cipher suite (%#04x), but it comes after unapproved cipher suites. With this configuration, clients that don't support previous, approved cipher suites may be given an unapproved one and reject the connection.", i, cs) } } if !haveRequired { return fmt.Errorf("http2: TLSConfig.CipherSuites is missing an HTTP/2-required AES_128_GCM_SHA256 cipher.") } } // Note: not setting MinVersion to tls.VersionTLS12, // as we don't want to interfere with HTTP/1.1 traffic // on the user's server. We enforce TLS 1.2 later once // we accept a connection. Ideally this should be done // during next-proto selection, but using TLS <1.2 with // HTTP/2 is still the client's bug. s.TLSConfig.PreferServerCipherSuites = true haveNPN := false for _, p := range s.TLSConfig.NextProtos { if p == NextProtoTLS { haveNPN = true break } } if !haveNPN { s.TLSConfig.NextProtos = append(s.TLSConfig.NextProtos, NextProtoTLS) } if s.TLSNextProto == nil { s.TLSNextProto = map[string]func(*http.Server, *tls.Conn, http.Handler){} } protoHandler := func(hs *http.Server, c *tls.Conn, h http.Handler) { if testHookOnConn != nil { testHookOnConn() } conf.ServeConn(c, &ServeConnOpts{ Handler: h, BaseConfig: hs, }) } s.TLSNextProto[NextProtoTLS] = protoHandler return nil } // ServeConnOpts are options for the Server.ServeConn method. type ServeConnOpts struct { // BaseConfig optionally sets the base configuration // for values. If nil, defaults are used. BaseConfig *http.Server // Handler specifies which handler to use for processing // requests. If nil, BaseConfig.Handler is used. If BaseConfig // or BaseConfig.Handler is nil, http.DefaultServeMux is used. Handler http.Handler } func (o *ServeConnOpts) baseConfig() *http.Server { if o != nil && o.BaseConfig != nil { return o.BaseConfig } return new(http.Server) } func (o *ServeConnOpts) handler() http.Handler { if o != nil { if o.Handler != nil { return o.Handler } if o.BaseConfig != nil && o.BaseConfig.Handler != nil { return o.BaseConfig.Handler } } return http.DefaultServeMux } // ServeConn serves HTTP/2 requests on the provided connection and // blocks until the connection is no longer readable. // // ServeConn starts speaking HTTP/2 assuming that c has not had any // reads or writes. It writes its initial settings frame and expects // to be able to read the preface and settings frame from the // client. If c has a ConnectionState method like a *tls.Conn, the // ConnectionState is used to verify the TLS ciphersuite and to set // the Request.TLS field in Handlers. // // ServeConn does not support h2c by itself. Any h2c support must be // implemented in terms of providing a suitably-behaving net.Conn. // // The opts parameter is optional. If nil, default values are used. func (s *Server) ServeConn(c net.Conn, opts *ServeConnOpts) { baseCtx, cancel := serverConnBaseContext(c, opts) defer cancel() sc := &serverConn{ srv: s, hs: opts.baseConfig(), conn: c, baseCtx: baseCtx, remoteAddrStr: c.RemoteAddr().String(), bw: newBufferedWriter(c), handler: opts.handler(), streams: make(map[uint32]*stream), readFrameCh: make(chan readFrameResult), wantWriteFrameCh: make(chan FrameWriteRequest, 8), serveMsgCh: make(chan interface{}, 8), wroteFrameCh: make(chan frameWriteResult, 1), // buffered; one send in writeFrameAsync bodyReadCh: make(chan bodyReadMsg), // buffering doesn't matter either way doneServing: make(chan struct{}), clientMaxStreams: math.MaxUint32, // Section 6.5.2: "Initially, there is no limit to this value" advMaxStreams: s.maxConcurrentStreams(), initialStreamSendWindowSize: initialWindowSize, maxFrameSize: initialMaxFrameSize, headerTableSize: initialHeaderTableSize, serveG: newGoroutineLock(), pushEnabled: true, } s.state.registerConn(sc) defer s.state.unregisterConn(sc) // The net/http package sets the write deadline from the // http.Server.WriteTimeout during the TLS handshake, but then // passes the connection off to us with the deadline already set. // Write deadlines are set per stream in serverConn.newStream. // Disarm the net.Conn write deadline here. if sc.hs.WriteTimeout != 0 { sc.conn.SetWriteDeadline(time.Time{}) } if s.NewWriteScheduler != nil { sc.writeSched = s.NewWriteScheduler() } else { sc.writeSched = NewRandomWriteScheduler() } // These start at the RFC-specified defaults. If there is a higher // configured value for inflow, that will be updated when we send a // WINDOW_UPDATE shortly after sending SETTINGS. sc.flow.add(initialWindowSize) sc.inflow.add(initialWindowSize) sc.hpackEncoder = hpack.NewEncoder(&sc.headerWriteBuf) fr := NewFramer(sc.bw, c) fr.ReadMetaHeaders = hpack.NewDecoder(initialHeaderTableSize, nil) fr.MaxHeaderListSize = sc.maxHeaderListSize() fr.SetMaxReadFrameSize(s.maxReadFrameSize()) sc.framer = fr if tc, ok := c.(connectionStater); ok { sc.tlsState = new(tls.ConnectionState) *sc.tlsState = tc.ConnectionState() // 9.2 Use of TLS Features // An implementation of HTTP/2 over TLS MUST use TLS // 1.2 or higher with the restrictions on feature set // and cipher suite described in this section. Due to // implementation limitations, it might not be // possible to fail TLS negotiation. An endpoint MUST // immediately terminate an HTTP/2 connection that // does not meet the TLS requirements described in // this section with a connection error (Section // 5.4.1) of type INADEQUATE_SECURITY. if sc.tlsState.Version < tls.VersionTLS12 { sc.rejectConn(ErrCodeInadequateSecurity, "TLS version too low") return } if sc.tlsState.ServerName == "" { // Client must use SNI, but we don't enforce that anymore, // since it was causing problems when connecting to bare IP // addresses during development. // // TODO: optionally enforce? Or enforce at the time we receive // a new request, and verify the ServerName matches the :authority? // But that precludes proxy situations, perhaps. // // So for now, do nothing here again. } if !s.PermitProhibitedCipherSuites && isBadCipher(sc.tlsState.CipherSuite) { // "Endpoints MAY choose to generate a connection error // (Section 5.4.1) of type INADEQUATE_SECURITY if one of // the prohibited cipher suites are negotiated." // // We choose that. In my opinion, the spec is weak // here. It also says both parties must support at least // TLS_ECDHE_RSA_WITH_AES_128_GCM_SHA256 so there's no // excuses here. If we really must, we could allow an // "AllowInsecureWeakCiphers" option on the server later. // Let's see how it plays out first. sc.rejectConn(ErrCodeInadequateSecurity, fmt.Sprintf("Prohibited TLS 1.2 Cipher Suite: %x", sc.tlsState.CipherSuite)) return } } if hook := testHookGetServerConn; hook != nil { hook(sc) } sc.serve() } func serverConnBaseContext(c net.Conn, opts *ServeConnOpts) (ctx context.Context, cancel func()) { ctx, cancel = context.WithCancel(context.Background()) ctx = context.WithValue(ctx, http.LocalAddrContextKey, c.LocalAddr()) if hs := opts.baseConfig(); hs != nil { ctx = context.WithValue(ctx, http.ServerContextKey, hs) } return } func (sc *serverConn) rejectConn(err ErrCode, debug string) { sc.vlogf("http2: server rejecting conn: %v, %s", err, debug) // ignoring errors. hanging up anyway. sc.framer.WriteGoAway(0, err, []byte(debug)) sc.bw.Flush() sc.conn.Close() } type serverConn struct { // Immutable: srv *Server hs *http.Server conn net.Conn bw *bufferedWriter // writing to conn handler http.Handler baseCtx context.Context framer *Framer doneServing chan struct{} // closed when serverConn.serve ends readFrameCh chan readFrameResult // written by serverConn.readFrames wantWriteFrameCh chan FrameWriteRequest // from handlers -> serve wroteFrameCh chan frameWriteResult // from writeFrameAsync -> serve, tickles more frame writes bodyReadCh chan bodyReadMsg // from handlers -> serve serveMsgCh chan interface{} // misc messages & code to send to / run on the serve loop flow flow // conn-wide (not stream-specific) outbound flow control inflow flow // conn-wide inbound flow control tlsState *tls.ConnectionState // shared by all handlers, like net/http remoteAddrStr string writeSched WriteScheduler // Everything following is owned by the serve loop; use serveG.check(): serveG goroutineLock // used to verify funcs are on serve() pushEnabled bool sawFirstSettings bool // got the initial SETTINGS frame after the preface needToSendSettingsAck bool unackedSettings int // how many SETTINGS have we sent without ACKs? queuedControlFrames int // control frames in the writeSched queue clientMaxStreams uint32 // SETTINGS_MAX_CONCURRENT_STREAMS from client (our PUSH_PROMISE limit) advMaxStreams uint32 // our SETTINGS_MAX_CONCURRENT_STREAMS advertised the client curClientStreams uint32 // number of open streams initiated by the client curPushedStreams uint32 // number of open streams initiated by server push maxClientStreamID uint32 // max ever seen from client (odd), or 0 if there have been no client requests maxPushPromiseID uint32 // ID of the last push promise (even), or 0 if there have been no pushes streams map[uint32]*stream initialStreamSendWindowSize int32 maxFrameSize int32 headerTableSize uint32 peerMaxHeaderListSize uint32 // zero means unknown (default) canonHeader map[string]string // http2-lower-case -> Go-Canonical-Case writingFrame bool // started writing a frame (on serve goroutine or separate) writingFrameAsync bool // started a frame on its own goroutine but haven't heard back on wroteFrameCh needsFrameFlush bool // last frame write wasn't a flush inGoAway bool // we've started to or sent GOAWAY inFrameScheduleLoop bool // whether we're in the scheduleFrameWrite loop needToSendGoAway bool // we need to schedule a GOAWAY frame write goAwayCode ErrCode shutdownTimer *time.Timer // nil until used idleTimer *time.Timer // nil if unused // Owned by the writeFrameAsync goroutine: headerWriteBuf bytes.Buffer hpackEncoder *hpack.Encoder // Used by startGracefulShutdown. shutdownOnce sync.Once } func (sc *serverConn) maxHeaderListSize() uint32 { n := sc.hs.MaxHeaderBytes if n <= 0 { n = http.DefaultMaxHeaderBytes } // http2's count is in a slightly different unit and includes 32 bytes per pair. // So, take the net/http.Server value and pad it up a bit, assuming 10 headers. const perFieldOverhead = 32 // per http2 spec const typicalHeaders = 10 // conservative return uint32(n + typicalHeaders*perFieldOverhead) } func (sc *serverConn) curOpenStreams() uint32 { sc.serveG.check() return sc.curClientStreams + sc.curPushedStreams } // stream represents a stream. This is the minimal metadata needed by // the serve goroutine. Most of the actual stream state is owned by // the http.Handler's goroutine in the responseWriter. Because the // responseWriter's responseWriterState is recycled at the end of a // handler, this struct intentionally has no pointer to the // *responseWriter{,State} itself, as the Handler ending nils out the // responseWriter's state field. type stream struct { // immutable: sc *serverConn id uint32 body *pipe // non-nil if expecting DATA frames cw closeWaiter // closed wait stream transitions to closed state ctx context.Context cancelCtx func() // owned by serverConn's serve loop: bodyBytes int64 // body bytes seen so far declBodyBytes int64 // or -1 if undeclared flow flow // limits writing from Handler to client inflow flow // what the client is allowed to POST/etc to us parent *stream // or nil numTrailerValues int64 weight uint8 state streamState resetQueued bool // RST_STREAM queued for write; set by sc.resetStream gotTrailerHeader bool // HEADER frame for trailers was seen wroteHeaders bool // whether we wrote headers (not status 100) writeDeadline *time.Timer // nil if unused trailer http.Header // accumulated trailers reqTrailer http.Header // handler's Request.Trailer } func (sc *serverConn) Framer() *Framer { return sc.framer } func (sc *serverConn) CloseConn() error { return sc.conn.Close() } func (sc *serverConn) Flush() error { return sc.bw.Flush() } func (sc *serverConn) HeaderEncoder() (*hpack.Encoder, *bytes.Buffer) { return sc.hpackEncoder, &sc.headerWriteBuf } func (sc *serverConn) state(streamID uint32) (streamState, *stream) { sc.serveG.check() // http://tools.ietf.org/html/rfc7540#section-5.1 if st, ok := sc.streams[streamID]; ok { return st.state, st } // "The first use of a new stream identifier implicitly closes all // streams in the "idle" state that might have been initiated by // that peer with a lower-valued stream identifier. For example, if // a client sends a HEADERS frame on stream 7 without ever sending a // frame on stream 5, then stream 5 transitions to the "closed" // state when the first frame for stream 7 is sent or received." if streamID%2 == 1 { if streamID <= sc.maxClientStreamID { return stateClosed, nil } } else { if streamID <= sc.maxPushPromiseID { return stateClosed, nil } } return stateIdle, nil } // setConnState calls the net/http ConnState hook for this connection, if configured. // Note that the net/http package does StateNew and StateClosed for us. // There is currently no plan for StateHijacked or hijacking HTTP/2 connections. func (sc *serverConn) setConnState(state http.ConnState) { if sc.hs.ConnState != nil { sc.hs.ConnState(sc.conn, state) } } func (sc *serverConn) vlogf(format string, args ...interface{}) { if VerboseLogs { sc.logf(format, args...) } } func (sc *serverConn) logf(format string, args ...interface{}) { if lg := sc.hs.ErrorLog; lg != nil { lg.Printf(format, args...) } else { log.Printf(format, args...) } } // errno returns v's underlying uintptr, else 0. // // TODO: remove this helper function once http2 can use build // tags. See comment in isClosedConnError. func errno(v error) uintptr { if rv := reflect.ValueOf(v); rv.Kind() == reflect.Uintptr { return uintptr(rv.Uint()) } return 0 } // isClosedConnError reports whether err is an error from use of a closed // network connection. func isClosedConnError(err error) bool { if err == nil { return false } // TODO: remove this string search and be more like the Windows // case below. That might involve modifying the standard library // to return better error types. str := err.Error() if strings.Contains(str, "use of closed network connection") { return true } // TODO(bradfitz): x/tools/cmd/bundle doesn't really support // build tags, so I can't make an http2_windows.go file with // Windows-specific stuff. Fix that and move this, once we // have a way to bundle this into std's net/http somehow. if runtime.GOOS == "windows" { if oe, ok := err.(*net.OpError); ok && oe.Op == "read" { if se, ok := oe.Err.(*os.SyscallError); ok && se.Syscall == "wsarecv" { const WSAECONNABORTED = 10053 const WSAECONNRESET = 10054 if n := errno(se.Err); n == WSAECONNRESET || n == WSAECONNABORTED { return true } } } } return false } func (sc *serverConn) condlogf(err error, format string, args ...interface{}) { if err == nil { return } if err == io.EOF || err == io.ErrUnexpectedEOF || isClosedConnError(err) || err == errPrefaceTimeout { // Boring, expected errors. sc.vlogf(format, args...) } else { sc.logf(format, args...) } } func (sc *serverConn) canonicalHeader(v string) string { sc.serveG.check() buildCommonHeaderMapsOnce() cv, ok := commonCanonHeader[v] if ok { return cv } cv, ok = sc.canonHeader[v] if ok { return cv } if sc.canonHeader == nil { sc.canonHeader = make(map[string]string) } cv = http.CanonicalHeaderKey(v) sc.canonHeader[v] = cv return cv } type readFrameResult struct { f Frame // valid until readMore is called err error // readMore should be called once the consumer no longer needs or // retains f. After readMore, f is invalid and more frames can be // read. readMore func() } // readFrames is the loop that reads incoming frames. // It takes care to only read one frame at a time, blocking until the // consumer is done with the frame. // It's run on its own goroutine. func (sc *serverConn) readFrames() { gate := make(gate) gateDone := gate.Done for { f, err := sc.framer.ReadFrame() select { case sc.readFrameCh <- readFrameResult{f, err, gateDone}: case <-sc.doneServing: return } select { case <-gate: case <-sc.doneServing: return } if terminalReadFrameError(err) { return } } } // frameWriteResult is the message passed from writeFrameAsync to the serve goroutine. type frameWriteResult struct { wr FrameWriteRequest // what was written (or attempted) err error // result of the writeFrame call } // writeFrameAsync runs in its own goroutine and writes a single frame // and then reports when it's done. // At most one goroutine can be running writeFrameAsync at a time per // serverConn. func (sc *serverConn) writeFrameAsync(wr FrameWriteRequest) { err := wr.write.writeFrame(sc) sc.wroteFrameCh <- frameWriteResult{wr, err} } func (sc *serverConn) closeAllStreamsOnConnClose() { sc.serveG.check() for _, st := range sc.streams { sc.closeStream(st, errClientDisconnected) } } func (sc *serverConn) stopShutdownTimer() { sc.serveG.check() if t := sc.shutdownTimer; t != nil { t.Stop() } } func (sc *serverConn) notePanic() { // Note: this is for serverConn.serve panicking, not http.Handler code. if testHookOnPanicMu != nil { testHookOnPanicMu.Lock() defer testHookOnPanicMu.Unlock() } if testHookOnPanic != nil { if e := recover(); e != nil { if testHookOnPanic(sc, e) { panic(e) } } } } func (sc *serverConn) serve() { sc.serveG.check() defer sc.notePanic() defer sc.conn.Close() defer sc.closeAllStreamsOnConnClose() defer sc.stopShutdownTimer() defer close(sc.doneServing) // unblocks handlers trying to send if VerboseLogs { sc.vlogf("http2: server connection from %v on %p", sc.conn.RemoteAddr(), sc.hs) } sc.writeFrame(FrameWriteRequest{ write: writeSettings{ {SettingMaxFrameSize, sc.srv.maxReadFrameSize()}, {SettingMaxConcurrentStreams, sc.advMaxStreams}, {SettingMaxHeaderListSize, sc.maxHeaderListSize()}, {SettingInitialWindowSize, uint32(sc.srv.initialStreamRecvWindowSize())}, }, }) sc.unackedSettings++ // Each connection starts with intialWindowSize inflow tokens. // If a higher value is configured, we add more tokens. if diff := sc.srv.initialConnRecvWindowSize() - initialWindowSize; diff > 0 { sc.sendWindowUpdate(nil, int(diff)) } if err := sc.readPreface(); err != nil { sc.condlogf(err, "http2: server: error reading preface from client %v: %v", sc.conn.RemoteAddr(), err) return } // Now that we've got the preface, get us out of the // "StateNew" state. We can't go directly to idle, though. // Active means we read some data and anticipate a request. We'll // do another Active when we get a HEADERS frame. sc.setConnState(http.StateActive) sc.setConnState(http.StateIdle) if sc.srv.IdleTimeout != 0 { sc.idleTimer = time.AfterFunc(sc.srv.IdleTimeout, sc.onIdleTimer) defer sc.idleTimer.Stop() } go sc.readFrames() // closed by defer sc.conn.Close above settingsTimer := time.AfterFunc(firstSettingsTimeout, sc.onSettingsTimer) defer settingsTimer.Stop() loopNum := 0 for { loopNum++ select { case wr := <-sc.wantWriteFrameCh: if se, ok := wr.write.(StreamError); ok { sc.resetStream(se) break } sc.writeFrame(wr) case res := <-sc.wroteFrameCh: sc.wroteFrame(res) case res := <-sc.readFrameCh: if !sc.processFrameFromReader(res) { return } res.readMore() if settingsTimer != nil { settingsTimer.Stop() settingsTimer = nil } case m := <-sc.bodyReadCh: sc.noteBodyRead(m.st, m.n) case msg := <-sc.serveMsgCh: switch v := msg.(type) { case func(int): v(loopNum) // for testing case *serverMessage: switch v { case settingsTimerMsg: sc.logf("timeout waiting for SETTINGS frames from %v", sc.conn.RemoteAddr()) return case idleTimerMsg: sc.vlogf("connection is idle") sc.goAway(ErrCodeNo) case shutdownTimerMsg: sc.vlogf("GOAWAY close timer fired; closing conn from %v", sc.conn.RemoteAddr()) return case gracefulShutdownMsg: sc.startGracefulShutdownInternal() default: panic("unknown timer") } case *startPushRequest: sc.startPush(v) default: panic(fmt.Sprintf("unexpected type %T", v)) } } // If the peer is causing us to generate a lot of control frames, // but not reading them from us, assume they are trying to make us // run out of memory. if sc.queuedControlFrames > sc.srv.maxQueuedControlFrames() { sc.vlogf("http2: too many control frames in send queue, closing connection") return } // Start the shutdown timer after sending a GOAWAY. When sending GOAWAY // with no error code (graceful shutdown), don't start the timer until // all open streams have been completed. sentGoAway := sc.inGoAway && !sc.needToSendGoAway && !sc.writingFrame gracefulShutdownComplete := sc.goAwayCode == ErrCodeNo && sc.curOpenStreams() == 0 if sentGoAway && sc.shutdownTimer == nil && (sc.goAwayCode != ErrCodeNo || gracefulShutdownComplete) { sc.shutDownIn(goAwayTimeout) } } } func (sc *serverConn) awaitGracefulShutdown(sharedCh <-chan struct{}, privateCh chan struct{}) { select { case <-sc.doneServing: case <-sharedCh: close(privateCh) } } type serverMessage int // Message values sent to serveMsgCh. var ( settingsTimerMsg = new(serverMessage) idleTimerMsg = new(serverMessage) shutdownTimerMsg = new(serverMessage) gracefulShutdownMsg = new(serverMessage) ) func (sc *serverConn) onSettingsTimer() { sc.sendServeMsg(settingsTimerMsg) } func (sc *serverConn) onIdleTimer() { sc.sendServeMsg(idleTimerMsg) } func (sc *serverConn) onShutdownTimer() { sc.sendServeMsg(shutdownTimerMsg) } func (sc *serverConn) sendServeMsg(msg interface{}) { sc.serveG.checkNotOn() // NOT select { case sc.serveMsgCh <- msg: case <-sc.doneServing: } } var errPrefaceTimeout = errors.New("timeout waiting for client preface") // readPreface reads the ClientPreface greeting from the peer or // returns errPrefaceTimeout on timeout, or an error if the greeting // is invalid. func (sc *serverConn) readPreface() error { errc := make(chan error, 1) go func() { // Read the client preface buf := make([]byte, len(ClientPreface)) if _, err := io.ReadFull(sc.conn, buf); err != nil { errc <- err } else if !bytes.Equal(buf, clientPreface) { errc <- fmt.Errorf("bogus greeting %q", buf) } else { errc <- nil } }() timer := time.NewTimer(prefaceTimeout) // TODO: configurable on *Server? defer timer.Stop() select { case <-timer.C: return errPrefaceTimeout case err := <-errc: if err == nil { if VerboseLogs { sc.vlogf("http2: server: client %v said hello", sc.conn.RemoteAddr()) } } return err } } var errChanPool = sync.Pool{ New: func() interface{} { return make(chan error, 1) }, } var writeDataPool = sync.Pool{ New: func() interface{} { return new(writeData) }, } // writeDataFromHandler writes DATA response frames from a handler on // the given stream. func (sc *serverConn) writeDataFromHandler(stream *stream, data []byte, endStream bool) error { ch := errChanPool.Get().(chan error) writeArg := writeDataPool.Get().(*writeData) *writeArg = writeData{stream.id, data, endStream} err := sc.writeFrameFromHandler(FrameWriteRequest{ write: writeArg, stream: stream, done: ch, }) if err != nil { return err } var frameWriteDone bool // the frame write is done (successfully or not) select { case err = <-ch: frameWriteDone = true case <-sc.doneServing: return errClientDisconnected case <-stream.cw: // If both ch and stream.cw were ready (as might // happen on the final Write after an http.Handler // ends), prefer the write result. Otherwise this // might just be us successfully closing the stream. // The writeFrameAsync and serve goroutines guarantee // that the ch send will happen before the stream.cw // close. select { case err = <-ch: frameWriteDone = true default: return errStreamClosed } } errChanPool.Put(ch) if frameWriteDone { writeDataPool.Put(writeArg) } return err } // writeFrameFromHandler sends wr to sc.wantWriteFrameCh, but aborts // if the connection has gone away. // // This must not be run from the serve goroutine itself, else it might // deadlock writing to sc.wantWriteFrameCh (which is only mildly // buffered and is read by serve itself). If you're on the serve // goroutine, call writeFrame instead. func (sc *serverConn) writeFrameFromHandler(wr FrameWriteRequest) error { sc.serveG.checkNotOn() // NOT select { case sc.wantWriteFrameCh <- wr: return nil case <-sc.doneServing: // Serve loop is gone. // Client has closed their connection to the server. return errClientDisconnected } } // writeFrame schedules a frame to write and sends it if there's nothing // already being written. // // There is no pushback here (the serve goroutine never blocks). It's // the http.Handlers that block, waiting for their previous frames to // make it onto the wire // // If you're not on the serve goroutine, use writeFrameFromHandler instead. func (sc *serverConn) writeFrame(wr FrameWriteRequest) { sc.serveG.check() // If true, wr will not be written and wr.done will not be signaled. var ignoreWrite bool // We are not allowed to write frames on closed streams. RFC 7540 Section // 5.1.1 says: "An endpoint MUST NOT send frames other than PRIORITY on // a closed stream." Our server never sends PRIORITY, so that exception // does not apply. // // The serverConn might close an open stream while the stream's handler // is still running. For example, the server might close a stream when it // receives bad data from the client. If this happens, the handler might // attempt to write a frame after the stream has been closed (since the // handler hasn't yet been notified of the close). In this case, we simply // ignore the frame. The handler will notice that the stream is closed when // it waits for the frame to be written. // // As an exception to this rule, we allow sending RST_STREAM after close. // This allows us to immediately reject new streams without tracking any // state for those streams (except for the queued RST_STREAM frame). This // may result in duplicate RST_STREAMs in some cases, but the client should // ignore those. if wr.StreamID() != 0 { _, isReset := wr.write.(StreamError) if state, _ := sc.state(wr.StreamID()); state == stateClosed && !isReset { ignoreWrite = true } } // Don't send a 100-continue response if we've already sent headers. // See golang.org/issue/14030. switch wr.write.(type) { case *writeResHeaders: wr.stream.wroteHeaders = true case write100ContinueHeadersFrame: if wr.stream.wroteHeaders { // We do not need to notify wr.done because this frame is // never written with wr.done != nil. if wr.done != nil { panic("wr.done != nil for write100ContinueHeadersFrame") } ignoreWrite = true } } if !ignoreWrite { if wr.isControl() { sc.queuedControlFrames++ // For extra safety, detect wraparounds, which should not happen, // and pull the plug. if sc.queuedControlFrames < 0 { sc.conn.Close() } } sc.writeSched.Push(wr) } sc.scheduleFrameWrite() } // startFrameWrite starts a goroutine to write wr (in a separate // goroutine since that might block on the network), and updates the // serve goroutine's state about the world, updated from info in wr. func (sc *serverConn) startFrameWrite(wr FrameWriteRequest) { sc.serveG.check() if sc.writingFrame { panic("internal error: can only be writing one frame at a time") } st := wr.stream if st != nil { switch st.state { case stateHalfClosedLocal: switch wr.write.(type) { case StreamError, handlerPanicRST, writeWindowUpdate: // RFC 7540 Section 5.1 allows sending RST_STREAM, PRIORITY, and WINDOW_UPDATE // in this state. (We never send PRIORITY from the server, so that is not checked.) default: panic(fmt.Sprintf("internal error: attempt to send frame on a half-closed-local stream: %v", wr)) } case stateClosed: panic(fmt.Sprintf("internal error: attempt to send frame on a closed stream: %v", wr)) } } if wpp, ok := wr.write.(*writePushPromise); ok { var err error wpp.promisedID, err = wpp.allocatePromisedID() if err != nil { sc.writingFrameAsync = false wr.replyToWriter(err) return } } sc.writingFrame = true sc.needsFrameFlush = true if wr.write.staysWithinBuffer(sc.bw.Available()) { sc.writingFrameAsync = false err := wr.write.writeFrame(sc) sc.wroteFrame(frameWriteResult{wr, err}) } else { sc.writingFrameAsync = true go sc.writeFrameAsync(wr) } } // errHandlerPanicked is the error given to any callers blocked in a read from // Request.Body when the main goroutine panics. Since most handlers read in the // main ServeHTTP goroutine, this will show up rarely. var errHandlerPanicked = errors.New("http2: handler panicked") // wroteFrame is called on the serve goroutine with the result of // whatever happened on writeFrameAsync. func (sc *serverConn) wroteFrame(res frameWriteResult) { sc.serveG.check() if !sc.writingFrame { panic("internal error: expected to be already writing a frame") } sc.writingFrame = false sc.writingFrameAsync = false wr := res.wr if writeEndsStream(wr.write) { st := wr.stream if st == nil { panic("internal error: expecting non-nil stream") } switch st.state { case stateOpen: // Here we would go to stateHalfClosedLocal in // theory, but since our handler is done and // the net/http package provides no mechanism // for closing a ResponseWriter while still // reading data (see possible TODO at top of // this file), we go into closed state here // anyway, after telling the peer we're // hanging up on them. We'll transition to // stateClosed after the RST_STREAM frame is // written. st.state = stateHalfClosedLocal // Section 8.1: a server MAY request that the client abort // transmission of a request without error by sending a // RST_STREAM with an error code of NO_ERROR after sending // a complete response. sc.resetStream(streamError(st.id, ErrCodeNo)) case stateHalfClosedRemote: sc.closeStream(st, errHandlerComplete) } } else { switch v := wr.write.(type) { case StreamError: // st may be unknown if the RST_STREAM was generated to reject bad input. if st, ok := sc.streams[v.StreamID]; ok { sc.closeStream(st, v) } case handlerPanicRST: sc.closeStream(wr.stream, errHandlerPanicked) } } // Reply (if requested) to unblock the ServeHTTP goroutine. wr.replyToWriter(res.err) sc.scheduleFrameWrite() } // scheduleFrameWrite tickles the frame writing scheduler. // // If a frame is already being written, nothing happens. This will be called again // when the frame is done being written. // // If a frame isn't being written and we need to send one, the best frame // to send is selected by writeSched. // // If a frame isn't being written and there's nothing else to send, we // flush the write buffer. func (sc *serverConn) scheduleFrameWrite() { sc.serveG.check() if sc.writingFrame || sc.inFrameScheduleLoop { return } sc.inFrameScheduleLoop = true for !sc.writingFrameAsync { if sc.needToSendGoAway { sc.needToSendGoAway = false sc.startFrameWrite(FrameWriteRequest{ write: &writeGoAway{ maxStreamID: sc.maxClientStreamID, code: sc.goAwayCode, }, }) continue } if sc.needToSendSettingsAck { sc.needToSendSettingsAck = false sc.startFrameWrite(FrameWriteRequest{write: writeSettingsAck{}}) continue } if !sc.inGoAway || sc.goAwayCode == ErrCodeNo { if wr, ok := sc.writeSched.Pop(); ok { if wr.isControl() { sc.queuedControlFrames-- } sc.startFrameWrite(wr) continue } } if sc.needsFrameFlush { sc.startFrameWrite(FrameWriteRequest{write: flushFrameWriter{}}) sc.needsFrameFlush = false // after startFrameWrite, since it sets this true continue } break } sc.inFrameScheduleLoop = false } // startGracefulShutdown gracefully shuts down a connection. This // sends GOAWAY with ErrCodeNo to tell the client we're gracefully // shutting down. The connection isn't closed until all current // streams are done. // // startGracefulShutdown returns immediately; it does not wait until // the connection has shut down. func (sc *serverConn) startGracefulShutdown() { sc.serveG.checkNotOn() // NOT sc.shutdownOnce.Do(func() { sc.sendServeMsg(gracefulShutdownMsg) }) } // After sending GOAWAY, the connection will close after goAwayTimeout. // If we close the connection immediately after sending GOAWAY, there may // be unsent data in our kernel receive buffer, which will cause the kernel // to send a TCP RST on close() instead of a FIN. This RST will abort the // connection immediately, whether or not the client had received the GOAWAY. // // Ideally we should delay for at least 1 RTT + epsilon so the client has // a chance to read the GOAWAY and stop sending messages. Measuring RTT // is hard, so we approximate with 1 second. See golang.org/issue/18701. // // This is a var so it can be shorter in tests, where all requests uses the // loopback interface making the expected RTT very small. // // TODO: configurable? var goAwayTimeout = 1 * time.Second func (sc *serverConn) startGracefulShutdownInternal() { sc.goAway(ErrCodeNo) } func (sc *serverConn) goAway(code ErrCode) { sc.serveG.check() if sc.inGoAway { return } sc.inGoAway = true sc.needToSendGoAway = true sc.goAwayCode = code sc.scheduleFrameWrite() } func (sc *serverConn) shutDownIn(d time.Duration) { sc.serveG.check() sc.shutdownTimer = time.AfterFunc(d, sc.onShutdownTimer) } func (sc *serverConn) resetStream(se StreamError) { sc.serveG.check() sc.writeFrame(FrameWriteRequest{write: se}) if st, ok := sc.streams[se.StreamID]; ok { st.resetQueued = true } } // processFrameFromReader processes the serve loop's read from readFrameCh from the // frame-reading goroutine. // processFrameFromReader returns whether the connection should be kept open. func (sc *serverConn) processFrameFromReader(res readFrameResult) bool { sc.serveG.check() err := res.err if err != nil { if err == ErrFrameTooLarge { sc.goAway(ErrCodeFrameSize) return true // goAway will close the loop } clientGone := err == io.EOF || err == io.ErrUnexpectedEOF || isClosedConnError(err) if clientGone { // TODO: could we also get into this state if // the peer does a half close // (e.g. CloseWrite) because they're done // sending frames but they're still wanting // our open replies? Investigate. // TODO: add CloseWrite to crypto/tls.Conn first // so we have a way to test this? I suppose // just for testing we could have a non-TLS mode. return false } } else { f := res.f if VerboseLogs { sc.vlogf("http2: server read frame %v", summarizeFrame(f)) } err = sc.processFrame(f) if err == nil { return true } } switch ev := err.(type) { case StreamError: sc.resetStream(ev) return true case goAwayFlowError: sc.goAway(ErrCodeFlowControl) return true case ConnectionError: sc.logf("http2: server connection error from %v: %v", sc.conn.RemoteAddr(), ev) sc.goAway(ErrCode(ev)) return true // goAway will handle shutdown default: if res.err != nil { sc.vlogf("http2: server closing client connection; error reading frame from client %s: %v", sc.conn.RemoteAddr(), err) } else { sc.logf("http2: server closing client connection: %v", err) } return false } } func (sc *serverConn) processFrame(f Frame) error { sc.serveG.check() // First frame received must be SETTINGS. if !sc.sawFirstSettings { if _, ok := f.(*SettingsFrame); !ok { return ConnectionError(ErrCodeProtocol) } sc.sawFirstSettings = true } switch f := f.(type) { case *SettingsFrame: return sc.processSettings(f) case *MetaHeadersFrame: return sc.processHeaders(f) case *WindowUpdateFrame: return sc.processWindowUpdate(f) case *PingFrame: return sc.processPing(f) case *DataFrame: return sc.processData(f) case *RSTStreamFrame: return sc.processResetStream(f) case *PriorityFrame: return sc.processPriority(f) case *GoAwayFrame: return sc.processGoAway(f) case *PushPromiseFrame: // A client cannot push. Thus, servers MUST treat the receipt of a PUSH_PROMISE // frame as a connection error (Section 5.4.1) of type PROTOCOL_ERROR. return ConnectionError(ErrCodeProtocol) default: sc.vlogf("http2: server ignoring frame: %v", f.Header()) return nil } } func (sc *serverConn) processPing(f *PingFrame) error { sc.serveG.check() if f.IsAck() { // 6.7 PING: " An endpoint MUST NOT respond to PING frames // containing this flag." return nil } if f.StreamID != 0 { // "PING frames are not associated with any individual // stream. If a PING frame is received with a stream // identifier field value other than 0x0, the recipient MUST // respond with a connection error (Section 5.4.1) of type // PROTOCOL_ERROR." return ConnectionError(ErrCodeProtocol) } if sc.inGoAway && sc.goAwayCode != ErrCodeNo { return nil } sc.writeFrame(FrameWriteRequest{write: writePingAck{f}}) return nil } func (sc *serverConn) processWindowUpdate(f *WindowUpdateFrame) error { sc.serveG.check() switch { case f.StreamID != 0: // stream-level flow control state, st := sc.state(f.StreamID) if state == stateIdle { // Section 5.1: "Receiving any frame other than HEADERS // or PRIORITY on a stream in this state MUST be // treated as a connection error (Section 5.4.1) of // type PROTOCOL_ERROR." return ConnectionError(ErrCodeProtocol) } if st == nil { // "WINDOW_UPDATE can be sent by a peer that has sent a // frame bearing the END_STREAM flag. This means that a // receiver could receive a WINDOW_UPDATE frame on a "half // closed (remote)" or "closed" stream. A receiver MUST // NOT treat this as an error, see Section 5.1." return nil } if !st.flow.add(int32(f.Increment)) { return streamError(f.StreamID, ErrCodeFlowControl) } default: // connection-level flow control if !sc.flow.add(int32(f.Increment)) { return goAwayFlowError{} } } sc.scheduleFrameWrite() return nil } func (sc *serverConn) processResetStream(f *RSTStreamFrame) error { sc.serveG.check() state, st := sc.state(f.StreamID) if state == stateIdle { // 6.4 "RST_STREAM frames MUST NOT be sent for a // stream in the "idle" state. If a RST_STREAM frame // identifying an idle stream is received, the // recipient MUST treat this as a connection error // (Section 5.4.1) of type PROTOCOL_ERROR. return ConnectionError(ErrCodeProtocol) } if st != nil { st.cancelCtx() sc.closeStream(st, streamError(f.StreamID, f.ErrCode)) } return nil } func (sc *serverConn) closeStream(st *stream, err error) { sc.serveG.check() if st.state == stateIdle || st.state == stateClosed { panic(fmt.Sprintf("invariant; can't close stream in state %v", st.state)) } st.state = stateClosed if st.writeDeadline != nil { st.writeDeadline.Stop() } if st.isPushed() { sc.curPushedStreams-- } else { sc.curClientStreams-- } delete(sc.streams, st.id) if len(sc.streams) == 0 { sc.setConnState(http.StateIdle) if sc.srv.IdleTimeout != 0 { sc.idleTimer.Reset(sc.srv.IdleTimeout) } if h1ServerKeepAlivesDisabled(sc.hs) { sc.startGracefulShutdownInternal() } } if p := st.body; p != nil { // Return any buffered unread bytes worth of conn-level flow control. // See golang.org/issue/16481 sc.sendWindowUpdate(nil, p.Len()) p.CloseWithError(err) } st.cw.Close() // signals Handler's CloseNotifier, unblocks writes, etc sc.writeSched.CloseStream(st.id) } func (sc *serverConn) processSettings(f *SettingsFrame) error { sc.serveG.check() if f.IsAck() { sc.unackedSettings-- if sc.unackedSettings < 0 { // Why is the peer ACKing settings we never sent? // The spec doesn't mention this case, but // hang up on them anyway. return ConnectionError(ErrCodeProtocol) } return nil } if f.NumSettings() > 100 || f.HasDuplicates() { // This isn't actually in the spec, but hang up on // suspiciously large settings frames or those with // duplicate entries. return ConnectionError(ErrCodeProtocol) } if err := f.ForeachSetting(sc.processSetting); err != nil { return err } // TODO: judging by RFC 7540, Section 6.5.3 each SETTINGS frame should be // acknowledged individually, even if multiple are received before the ACK. sc.needToSendSettingsAck = true sc.scheduleFrameWrite() return nil } func (sc *serverConn) processSetting(s Setting) error { sc.serveG.check() if err := s.Valid(); err != nil { return err } if VerboseLogs { sc.vlogf("http2: server processing setting %v", s) } switch s.ID { case SettingHeaderTableSize: sc.headerTableSize = s.Val sc.hpackEncoder.SetMaxDynamicTableSize(s.Val) case SettingEnablePush: sc.pushEnabled = s.Val != 0 case SettingMaxConcurrentStreams: sc.clientMaxStreams = s.Val case SettingInitialWindowSize: return sc.processSettingInitialWindowSize(s.Val) case SettingMaxFrameSize: sc.maxFrameSize = int32(s.Val) // the maximum valid s.Val is < 2^31 case SettingMaxHeaderListSize: sc.peerMaxHeaderListSize = s.Val default: // Unknown setting: "An endpoint that receives a SETTINGS // frame with any unknown or unsupported identifier MUST // ignore that setting." if VerboseLogs { sc.vlogf("http2: server ignoring unknown setting %v", s) } } return nil } func (sc *serverConn) processSettingInitialWindowSize(val uint32) error { sc.serveG.check() // Note: val already validated to be within range by // processSetting's Valid call. // "A SETTINGS frame can alter the initial flow control window // size for all current streams. When the value of // SETTINGS_INITIAL_WINDOW_SIZE changes, a receiver MUST // adjust the size of all stream flow control windows that it // maintains by the difference between the new value and the // old value." old := sc.initialStreamSendWindowSize sc.initialStreamSendWindowSize = int32(val) growth := int32(val) - old // may be negative for _, st := range sc.streams { if !st.flow.add(growth) { // 6.9.2 Initial Flow Control Window Size // "An endpoint MUST treat a change to // SETTINGS_INITIAL_WINDOW_SIZE that causes any flow // control window to exceed the maximum size as a // connection error (Section 5.4.1) of type // FLOW_CONTROL_ERROR." return ConnectionError(ErrCodeFlowControl) } } return nil } func (sc *serverConn) processData(f *DataFrame) error { sc.serveG.check() if sc.inGoAway && sc.goAwayCode != ErrCodeNo { return nil } data := f.Data() // "If a DATA frame is received whose stream is not in "open" // or "half closed (local)" state, the recipient MUST respond // with a stream error (Section 5.4.2) of type STREAM_CLOSED." id := f.Header().StreamID state, st := sc.state(id) if id == 0 || state == stateIdle { // Section 5.1: "Receiving any frame other than HEADERS // or PRIORITY on a stream in this state MUST be // treated as a connection error (Section 5.4.1) of // type PROTOCOL_ERROR." return ConnectionError(ErrCodeProtocol) } if st == nil || state != stateOpen || st.gotTrailerHeader || st.resetQueued { // This includes sending a RST_STREAM if the stream is // in stateHalfClosedLocal (which currently means that // the http.Handler returned, so it's done reading & // done writing). Try to stop the client from sending // more DATA. // But still enforce their connection-level flow control, // and return any flow control bytes since we're not going // to consume them. if sc.inflow.available() < int32(f.Length) { return streamError(id, ErrCodeFlowControl) } // Deduct the flow control from inflow, since we're // going to immediately add it back in // sendWindowUpdate, which also schedules sending the // frames. sc.inflow.take(int32(f.Length)) sc.sendWindowUpdate(nil, int(f.Length)) // conn-level if st != nil && st.resetQueued { // Already have a stream error in flight. Don't send another. return nil } return streamError(id, ErrCodeStreamClosed) } if st.body == nil { panic("internal error: should have a body in this state") } // Sender sending more than they'd declared? if st.declBodyBytes != -1 && st.bodyBytes+int64(len(data)) > st.declBodyBytes { st.body.CloseWithError(fmt.Errorf("sender tried to send more than declared Content-Length of %d bytes", st.declBodyBytes)) // RFC 7540, sec 8.1.2.6: A request or response is also malformed if the // value of a content-length header field does not equal the sum of the // DATA frame payload lengths that form the body. return streamError(id, ErrCodeProtocol) } if f.Length > 0 { // Check whether the client has flow control quota. if st.inflow.available() < int32(f.Length) { return streamError(id, ErrCodeFlowControl) } st.inflow.take(int32(f.Length)) if len(data) > 0 { wrote, err := st.body.Write(data) if err != nil { return streamError(id, ErrCodeStreamClosed) } if wrote != len(data) { panic("internal error: bad Writer") } st.bodyBytes += int64(len(data)) } // Return any padded flow control now, since we won't // refund it later on body reads. if pad := int32(f.Length) - int32(len(data)); pad > 0 { sc.sendWindowUpdate32(nil, pad) sc.sendWindowUpdate32(st, pad) } } if f.StreamEnded() { st.endStream() } return nil } func (sc *serverConn) processGoAway(f *GoAwayFrame) error { sc.serveG.check() if f.ErrCode != ErrCodeNo { sc.logf("http2: received GOAWAY %+v, starting graceful shutdown", f) } else { sc.vlogf("http2: received GOAWAY %+v, starting graceful shutdown", f) } sc.startGracefulShutdownInternal() // http://tools.ietf.org/html/rfc7540#section-6.8 // We should not create any new streams, which means we should disable push. sc.pushEnabled = false return nil } // isPushed reports whether the stream is server-initiated. func (st *stream) isPushed() bool { return st.id%2 == 0 } // endStream closes a Request.Body's pipe. It is called when a DATA // frame says a request body is over (or after trailers). func (st *stream) endStream() { sc := st.sc sc.serveG.check() if st.declBodyBytes != -1 && st.declBodyBytes != st.bodyBytes { st.body.CloseWithError(fmt.Errorf("request declared a Content-Length of %d but only wrote %d bytes", st.declBodyBytes, st.bodyBytes)) } else { st.body.closeWithErrorAndCode(io.EOF, st.copyTrailersToHandlerRequest) st.body.CloseWithError(io.EOF) } st.state = stateHalfClosedRemote } // copyTrailersToHandlerRequest is run in the Handler's goroutine in // its Request.Body.Read just before it gets io.EOF. func (st *stream) copyTrailersToHandlerRequest() { for k, vv := range st.trailer { if _, ok := st.reqTrailer[k]; ok { // Only copy it over it was pre-declared. st.reqTrailer[k] = vv } } } // onWriteTimeout is run on its own goroutine (from time.AfterFunc) // when the stream's WriteTimeout has fired. func (st *stream) onWriteTimeout() { st.sc.writeFrameFromHandler(FrameWriteRequest{write: streamError(st.id, ErrCodeInternal)}) } func (sc *serverConn) processHeaders(f *MetaHeadersFrame) error { sc.serveG.check() id := f.StreamID if sc.inGoAway { // Ignore. return nil } // http://tools.ietf.org/html/rfc7540#section-5.1.1 // Streams initiated by a client MUST use odd-numbered stream // identifiers. [...] An endpoint that receives an unexpected // stream identifier MUST respond with a connection error // (Section 5.4.1) of type PROTOCOL_ERROR. if id%2 != 1 { return ConnectionError(ErrCodeProtocol) } // A HEADERS frame can be used to create a new stream or // send a trailer for an open one. If we already have a stream // open, let it process its own HEADERS frame (trailers at this // point, if it's valid). if st := sc.streams[f.StreamID]; st != nil { if st.resetQueued { // We're sending RST_STREAM to close the stream, so don't bother // processing this frame. return nil } // RFC 7540, sec 5.1: If an endpoint receives additional frames, other than // WINDOW_UPDATE, PRIORITY, or RST_STREAM, for a stream that is in // this state, it MUST respond with a stream error (Section 5.4.2) of // type STREAM_CLOSED. if st.state == stateHalfClosedRemote { return streamError(id, ErrCodeStreamClosed) } return st.processTrailerHeaders(f) } // [...] The identifier of a newly established stream MUST be // numerically greater than all streams that the initiating // endpoint has opened or reserved. [...] An endpoint that // receives an unexpected stream identifier MUST respond with // a connection error (Section 5.4.1) of type PROTOCOL_ERROR. if id <= sc.maxClientStreamID { return ConnectionError(ErrCodeProtocol) } sc.maxClientStreamID = id if sc.idleTimer != nil { sc.idleTimer.Stop() } // http://tools.ietf.org/html/rfc7540#section-5.1.2 // [...] Endpoints MUST NOT exceed the limit set by their peer. An // endpoint that receives a HEADERS frame that causes their // advertised concurrent stream limit to be exceeded MUST treat // this as a stream error (Section 5.4.2) of type PROTOCOL_ERROR // or REFUSED_STREAM. if sc.curClientStreams+1 > sc.advMaxStreams { if sc.unackedSettings == 0 { // They should know better. return streamError(id, ErrCodeProtocol) } // Assume it's a network race, where they just haven't // received our last SETTINGS update. But actually // this can't happen yet, because we don't yet provide // a way for users to adjust server parameters at // runtime. return streamError(id, ErrCodeRefusedStream) } initialState := stateOpen if f.StreamEnded() { initialState = stateHalfClosedRemote } st := sc.newStream(id, 0, initialState) if f.HasPriority() { if err := checkPriority(f.StreamID, f.Priority); err != nil { return err } sc.writeSched.AdjustStream(st.id, f.Priority) } rw, req, err := sc.newWriterAndRequest(st, f) if err != nil { return err } st.reqTrailer = req.Trailer if st.reqTrailer != nil { st.trailer = make(http.Header) } st.body = req.Body.(*requestBody).pipe // may be nil st.declBodyBytes = req.ContentLength handler := sc.handler.ServeHTTP if f.Truncated { // Their header list was too long. Send a 431 error. handler = handleHeaderListTooLong } else if err := checkValidHTTP2RequestHeaders(req.Header); err != nil { handler = new400Handler(err) } // The net/http package sets the read deadline from the // http.Server.ReadTimeout during the TLS handshake, but then // passes the connection off to us with the deadline already // set. Disarm it here after the request headers are read, // similar to how the http1 server works. Here it's // technically more like the http1 Server's ReadHeaderTimeout // (in Go 1.8), though. That's a more sane option anyway. if sc.hs.ReadTimeout != 0 { sc.conn.SetReadDeadline(time.Time{}) } go sc.runHandler(rw, req, handler) return nil } func (st *stream) processTrailerHeaders(f *MetaHeadersFrame) error { sc := st.sc sc.serveG.check() if st.gotTrailerHeader { return ConnectionError(ErrCodeProtocol) } st.gotTrailerHeader = true if !f.StreamEnded() { return streamError(st.id, ErrCodeProtocol) } if len(f.PseudoFields()) > 0 { return streamError(st.id, ErrCodeProtocol) } if st.trailer != nil { for _, hf := range f.RegularFields() { key := sc.canonicalHeader(hf.Name) if !httpguts.ValidTrailerHeader(key) { // TODO: send more details to the peer somehow. But http2 has // no way to send debug data at a stream level. Discuss with // HTTP folk. return streamError(st.id, ErrCodeProtocol) } st.trailer[key] = append(st.trailer[key], hf.Value) } } st.endStream() return nil } func checkPriority(streamID uint32, p PriorityParam) error { if streamID == p.StreamDep { // Section 5.3.1: "A stream cannot depend on itself. An endpoint MUST treat // this as a stream error (Section 5.4.2) of type PROTOCOL_ERROR." // Section 5.3.3 says that a stream can depend on one of its dependencies, // so it's only self-dependencies that are forbidden. return streamError(streamID, ErrCodeProtocol) } return nil } func (sc *serverConn) processPriority(f *PriorityFrame) error { if sc.inGoAway { return nil } if err := checkPriority(f.StreamID, f.PriorityParam); err != nil { return err } sc.writeSched.AdjustStream(f.StreamID, f.PriorityParam) return nil } func (sc *serverConn) newStream(id, pusherID uint32, state streamState) *stream { sc.serveG.check() if id == 0 { panic("internal error: cannot create stream with id 0") } ctx, cancelCtx := context.WithCancel(sc.baseCtx) st := &stream{ sc: sc, id: id, state: state, ctx: ctx, cancelCtx: cancelCtx, } st.cw.Init() st.flow.conn = &sc.flow // link to conn-level counter st.flow.add(sc.initialStreamSendWindowSize) st.inflow.conn = &sc.inflow // link to conn-level counter st.inflow.add(sc.srv.initialStreamRecvWindowSize()) if sc.hs.WriteTimeout != 0 { st.writeDeadline = time.AfterFunc(sc.hs.WriteTimeout, st.onWriteTimeout) } sc.streams[id] = st sc.writeSched.OpenStream(st.id, OpenStreamOptions{PusherID: pusherID}) if st.isPushed() { sc.curPushedStreams++ } else { sc.curClientStreams++ } if sc.curOpenStreams() == 1 { sc.setConnState(http.StateActive) } return st } func (sc *serverConn) newWriterAndRequest(st *stream, f *MetaHeadersFrame) (*responseWriter, *http.Request, error) { sc.serveG.check() rp := requestParam{ method: f.PseudoValue("method"), scheme: f.PseudoValue("scheme"), authority: f.PseudoValue("authority"), path: f.PseudoValue("path"), } isConnect := rp.method == "CONNECT" if isConnect { if rp.path != "" || rp.scheme != "" || rp.authority == "" { return nil, nil, streamError(f.StreamID, ErrCodeProtocol) } } else if rp.method == "" || rp.path == "" || (rp.scheme != "https" && rp.scheme != "http") { // See 8.1.2.6 Malformed Requests and Responses: // // Malformed requests or responses that are detected // MUST be treated as a stream error (Section 5.4.2) // of type PROTOCOL_ERROR." // // 8.1.2.3 Request Pseudo-Header Fields // "All HTTP/2 requests MUST include exactly one valid // value for the :method, :scheme, and :path // pseudo-header fields" return nil, nil, streamError(f.StreamID, ErrCodeProtocol) } bodyOpen := !f.StreamEnded() if rp.method == "HEAD" && bodyOpen { // HEAD requests can't have bodies return nil, nil, streamError(f.StreamID, ErrCodeProtocol) } rp.header = make(http.Header) for _, hf := range f.RegularFields() { rp.header.Add(sc.canonicalHeader(hf.Name), hf.Value) } if rp.authority == "" { rp.authority = rp.header.Get("Host") } rw, req, err := sc.newWriterAndRequestNoBody(st, rp) if err != nil { return nil, nil, err } if bodyOpen { if vv, ok := rp.header["Content-Length"]; ok { req.ContentLength, _ = strconv.ParseInt(vv[0], 10, 64) } else { req.ContentLength = -1 } req.Body.(*requestBody).pipe = &pipe{ b: &dataBuffer{expected: req.ContentLength}, } } return rw, req, nil } type requestParam struct { method string scheme, authority, path string header http.Header } func (sc *serverConn) newWriterAndRequestNoBody(st *stream, rp requestParam) (*responseWriter, *http.Request, error) { sc.serveG.check() var tlsState *tls.ConnectionState // nil if not scheme https if rp.scheme == "https" { tlsState = sc.tlsState } needsContinue := rp.header.Get("Expect") == "100-continue" if needsContinue { rp.header.Del("Expect") } // Merge Cookie headers into one "; "-delimited value. if cookies := rp.header["Cookie"]; len(cookies) > 1 { rp.header.Set("Cookie", strings.Join(cookies, "; ")) } // Setup Trailers var trailer http.Header for _, v := range rp.header["Trailer"] { for _, key := range strings.Split(v, ",") { key = http.CanonicalHeaderKey(strings.TrimSpace(key)) switch key { case "Transfer-Encoding", "Trailer", "Content-Length": // Bogus. (copy of http1 rules) // Ignore. default: if trailer == nil { trailer = make(http.Header) } trailer[key] = nil } } } delete(rp.header, "Trailer") var url_ *url.URL var requestURI string if rp.method == "CONNECT" { url_ = &url.URL{Host: rp.authority} requestURI = rp.authority // mimic HTTP/1 server behavior } else { var err error url_, err = url.ParseRequestURI(rp.path) if err != nil { return nil, nil, streamError(st.id, ErrCodeProtocol) } requestURI = rp.path } body := &requestBody{ conn: sc, stream: st, needsContinue: needsContinue, } req := &http.Request{ Method: rp.method, URL: url_, RemoteAddr: sc.remoteAddrStr, Header: rp.header, RequestURI: requestURI, Proto: "HTTP/2.0", ProtoMajor: 2, ProtoMinor: 0, TLS: tlsState, Host: rp.authority, Body: body, Trailer: trailer, } req = req.WithContext(st.ctx) rws := responseWriterStatePool.Get().(*responseWriterState) bwSave := rws.bw *rws = responseWriterState{} // zero all the fields rws.conn = sc rws.bw = bwSave rws.bw.Reset(chunkWriter{rws}) rws.stream = st rws.req = req rws.body = body rw := &responseWriter{rws: rws} return rw, req, nil } // Run on its own goroutine. func (sc *serverConn) runHandler(rw *responseWriter, req *http.Request, handler func(http.ResponseWriter, *http.Request)) { didPanic := true defer func() { rw.rws.stream.cancelCtx() if didPanic { e := recover() sc.writeFrameFromHandler(FrameWriteRequest{ write: handlerPanicRST{rw.rws.stream.id}, stream: rw.rws.stream, }) // Same as net/http: if e != nil && e != http.ErrAbortHandler { const size = 64 << 10 buf := make([]byte, size) buf = buf[:runtime.Stack(buf, false)] sc.logf("http2: panic serving %v: %v\n%s", sc.conn.RemoteAddr(), e, buf) } return } rw.handlerDone() }() handler(rw, req) didPanic = false } func handleHeaderListTooLong(w http.ResponseWriter, r *http.Request) { // 10.5.1 Limits on Header Block Size: // .. "A server that receives a larger header block than it is // willing to handle can send an HTTP 431 (Request Header Fields Too // Large) status code" const statusRequestHeaderFieldsTooLarge = 431 // only in Go 1.6+ w.WriteHeader(statusRequestHeaderFieldsTooLarge) io.WriteString(w, "

HTTP Error 431

Request Header Field(s) Too Large

") } // called from handler goroutines. // h may be nil. func (sc *serverConn) writeHeaders(st *stream, headerData *writeResHeaders) error { sc.serveG.checkNotOn() // NOT on var errc chan error if headerData.h != nil { // If there's a header map (which we don't own), so we have to block on // waiting for this frame to be written, so an http.Flush mid-handler // writes out the correct value of keys, before a handler later potentially // mutates it. errc = errChanPool.Get().(chan error) } if err := sc.writeFrameFromHandler(FrameWriteRequest{ write: headerData, stream: st, done: errc, }); err != nil { return err } if errc != nil { select { case err := <-errc: errChanPool.Put(errc) return err case <-sc.doneServing: return errClientDisconnected case <-st.cw: return errStreamClosed } } return nil } // called from handler goroutines. func (sc *serverConn) write100ContinueHeaders(st *stream) { sc.writeFrameFromHandler(FrameWriteRequest{ write: write100ContinueHeadersFrame{st.id}, stream: st, }) } // A bodyReadMsg tells the server loop that the http.Handler read n // bytes of the DATA from the client on the given stream. type bodyReadMsg struct { st *stream n int } // called from handler goroutines. // Notes that the handler for the given stream ID read n bytes of its body // and schedules flow control tokens to be sent. func (sc *serverConn) noteBodyReadFromHandler(st *stream, n int, err error) { sc.serveG.checkNotOn() // NOT on if n > 0 { select { case sc.bodyReadCh <- bodyReadMsg{st, n}: case <-sc.doneServing: } } } func (sc *serverConn) noteBodyRead(st *stream, n int) { sc.serveG.check() sc.sendWindowUpdate(nil, n) // conn-level if st.state != stateHalfClosedRemote && st.state != stateClosed { // Don't send this WINDOW_UPDATE if the stream is closed // remotely. sc.sendWindowUpdate(st, n) } } // st may be nil for conn-level func (sc *serverConn) sendWindowUpdate(st *stream, n int) { sc.serveG.check() // "The legal range for the increment to the flow control // window is 1 to 2^31-1 (2,147,483,647) octets." // A Go Read call on 64-bit machines could in theory read // a larger Read than this. Very unlikely, but we handle it here // rather than elsewhere for now. const maxUint31 = 1<<31 - 1 for n >= maxUint31 { sc.sendWindowUpdate32(st, maxUint31) n -= maxUint31 } sc.sendWindowUpdate32(st, int32(n)) } // st may be nil for conn-level func (sc *serverConn) sendWindowUpdate32(st *stream, n int32) { sc.serveG.check() if n == 0 { return } if n < 0 { panic("negative update") } var streamID uint32 if st != nil { streamID = st.id } sc.writeFrame(FrameWriteRequest{ write: writeWindowUpdate{streamID: streamID, n: uint32(n)}, stream: st, }) var ok bool if st == nil { ok = sc.inflow.add(n) } else { ok = st.inflow.add(n) } if !ok { panic("internal error; sent too many window updates without decrements?") } } // requestBody is the Handler's Request.Body type. // Read and Close may be called concurrently. type requestBody struct { stream *stream conn *serverConn closed bool // for use by Close only sawEOF bool // for use by Read only pipe *pipe // non-nil if we have a HTTP entity message body needsContinue bool // need to send a 100-continue } func (b *requestBody) Close() error { if b.pipe != nil && !b.closed { b.pipe.BreakWithError(errClosedBody) } b.closed = true return nil } func (b *requestBody) Read(p []byte) (n int, err error) { if b.needsContinue { b.needsContinue = false b.conn.write100ContinueHeaders(b.stream) } if b.pipe == nil || b.sawEOF { return 0, io.EOF } n, err = b.pipe.Read(p) if err == io.EOF { b.sawEOF = true } if b.conn == nil && inTests { return } b.conn.noteBodyReadFromHandler(b.stream, n, err) return } // responseWriter is the http.ResponseWriter implementation. It's // intentionally small (1 pointer wide) to minimize garbage. The // responseWriterState pointer inside is zeroed at the end of a // request (in handlerDone) and calls on the responseWriter thereafter // simply crash (caller's mistake), but the much larger responseWriterState // and buffers are reused between multiple requests. type responseWriter struct { rws *responseWriterState } // Optional http.ResponseWriter interfaces implemented. var ( _ http.CloseNotifier = (*responseWriter)(nil) _ http.Flusher = (*responseWriter)(nil) _ stringWriter = (*responseWriter)(nil) ) type responseWriterState struct { // immutable within a request: stream *stream req *http.Request body *requestBody // to close at end of request, if DATA frames didn't conn *serverConn // TODO: adjust buffer writing sizes based on server config, frame size updates from peer, etc bw *bufio.Writer // writing to a chunkWriter{this *responseWriterState} // mutated by http.Handler goroutine: handlerHeader http.Header // nil until called snapHeader http.Header // snapshot of handlerHeader at WriteHeader time trailers []string // set in writeChunk status int // status code passed to WriteHeader wroteHeader bool // WriteHeader called (explicitly or implicitly). Not necessarily sent to user yet. sentHeader bool // have we sent the header frame? handlerDone bool // handler has finished dirty bool // a Write failed; don't reuse this responseWriterState sentContentLen int64 // non-zero if handler set a Content-Length header wroteBytes int64 closeNotifierMu sync.Mutex // guards closeNotifierCh closeNotifierCh chan bool // nil until first used } type chunkWriter struct{ rws *responseWriterState } func (cw chunkWriter) Write(p []byte) (n int, err error) { return cw.rws.writeChunk(p) } func (rws *responseWriterState) hasTrailers() bool { return len(rws.trailers) != 0 } // declareTrailer is called for each Trailer header when the // response header is written. It notes that a header will need to be // written in the trailers at the end of the response. func (rws *responseWriterState) declareTrailer(k string) { k = http.CanonicalHeaderKey(k) if !httpguts.ValidTrailerHeader(k) { // Forbidden by RFC 7230, section 4.1.2. rws.conn.logf("ignoring invalid trailer %q", k) return } if !strSliceContains(rws.trailers, k) { rws.trailers = append(rws.trailers, k) } } // writeChunk writes chunks from the bufio.Writer. But because // bufio.Writer may bypass its chunking, sometimes p may be // arbitrarily large. // // writeChunk is also responsible (on the first chunk) for sending the // HEADER response. func (rws *responseWriterState) writeChunk(p []byte) (n int, err error) { if !rws.wroteHeader { rws.writeHeader(200) } isHeadResp := rws.req.Method == "HEAD" if !rws.sentHeader { rws.sentHeader = true var ctype, clen string if clen = rws.snapHeader.Get("Content-Length"); clen != "" { rws.snapHeader.Del("Content-Length") clen64, err := strconv.ParseInt(clen, 10, 64) if err == nil && clen64 >= 0 { rws.sentContentLen = clen64 } else { clen = "" } } if clen == "" && rws.handlerDone && bodyAllowedForStatus(rws.status) && (len(p) > 0 || !isHeadResp) { clen = strconv.Itoa(len(p)) } _, hasContentType := rws.snapHeader["Content-Type"] if !hasContentType && bodyAllowedForStatus(rws.status) && len(p) > 0 { ctype = http.DetectContentType(p) } var date string if _, ok := rws.snapHeader["Date"]; !ok { // TODO(bradfitz): be faster here, like net/http? measure. date = time.Now().UTC().Format(http.TimeFormat) } for _, v := range rws.snapHeader["Trailer"] { foreachHeaderElement(v, rws.declareTrailer) } // "Connection" headers aren't allowed in HTTP/2 (RFC 7540, 8.1.2.2), // but respect "Connection" == "close" to mean sending a GOAWAY and tearing // down the TCP connection when idle, like we do for HTTP/1. // TODO: remove more Connection-specific header fields here, in addition // to "Connection". if _, ok := rws.snapHeader["Connection"]; ok { v := rws.snapHeader.Get("Connection") delete(rws.snapHeader, "Connection") if v == "close" { rws.conn.startGracefulShutdown() } } endStream := (rws.handlerDone && !rws.hasTrailers() && len(p) == 0) || isHeadResp err = rws.conn.writeHeaders(rws.stream, &writeResHeaders{ streamID: rws.stream.id, httpResCode: rws.status, h: rws.snapHeader, endStream: endStream, contentType: ctype, contentLength: clen, date: date, }) if err != nil { rws.dirty = true return 0, err } if endStream { return 0, nil } } if isHeadResp { return len(p), nil } if len(p) == 0 && !rws.handlerDone { return 0, nil } if rws.handlerDone { rws.promoteUndeclaredTrailers() } endStream := rws.handlerDone && !rws.hasTrailers() if len(p) > 0 || endStream { // only send a 0 byte DATA frame if we're ending the stream. if err := rws.conn.writeDataFromHandler(rws.stream, p, endStream); err != nil { rws.dirty = true return 0, err } } if rws.handlerDone && rws.hasTrailers() { err = rws.conn.writeHeaders(rws.stream, &writeResHeaders{ streamID: rws.stream.id, h: rws.handlerHeader, trailers: rws.trailers, endStream: true, }) if err != nil { rws.dirty = true } return len(p), err } return len(p), nil } // TrailerPrefix is a magic prefix for ResponseWriter.Header map keys // that, if present, signals that the map entry is actually for // the response trailers, and not the response headers. The prefix // is stripped after the ServeHTTP call finishes and the values are // sent in the trailers. // // This mechanism is intended only for trailers that are not known // prior to the headers being written. If the set of trailers is fixed // or known before the header is written, the normal Go trailers mechanism // is preferred: // https://golang.org/pkg/net/http/#ResponseWriter // https://golang.org/pkg/net/http/#example_ResponseWriter_trailers const TrailerPrefix = "Trailer:" // promoteUndeclaredTrailers permits http.Handlers to set trailers // after the header has already been flushed. Because the Go // ResponseWriter interface has no way to set Trailers (only the // Header), and because we didn't want to expand the ResponseWriter // interface, and because nobody used trailers, and because RFC 7230 // says you SHOULD (but not must) predeclare any trailers in the // header, the official ResponseWriter rules said trailers in Go must // be predeclared, and then we reuse the same ResponseWriter.Header() // map to mean both Headers and Trailers. When it's time to write the // Trailers, we pick out the fields of Headers that were declared as // trailers. That worked for a while, until we found the first major // user of Trailers in the wild: gRPC (using them only over http2), // and gRPC libraries permit setting trailers mid-stream without // predeclarnig them. So: change of plans. We still permit the old // way, but we also permit this hack: if a Header() key begins with // "Trailer:", the suffix of that key is a Trailer. Because ':' is an // invalid token byte anyway, there is no ambiguity. (And it's already // filtered out) It's mildly hacky, but not terrible. // // This method runs after the Handler is done and promotes any Header // fields to be trailers. func (rws *responseWriterState) promoteUndeclaredTrailers() { for k, vv := range rws.handlerHeader { if !strings.HasPrefix(k, TrailerPrefix) { continue } trailerKey := strings.TrimPrefix(k, TrailerPrefix) rws.declareTrailer(trailerKey) rws.handlerHeader[http.CanonicalHeaderKey(trailerKey)] = vv } if len(rws.trailers) > 1 { sorter := sorterPool.Get().(*sorter) sorter.SortStrings(rws.trailers) sorterPool.Put(sorter) } } func (w *responseWriter) Flush() { rws := w.rws if rws == nil { panic("Header called after Handler finished") } if rws.bw.Buffered() > 0 { if err := rws.bw.Flush(); err != nil { // Ignore the error. The frame writer already knows. return } } else { // The bufio.Writer won't call chunkWriter.Write // (writeChunk with zero bytes, so we have to do it // ourselves to force the HTTP response header and/or // final DATA frame (with END_STREAM) to be sent. rws.writeChunk(nil) } } func (w *responseWriter) CloseNotify() <-chan bool { rws := w.rws if rws == nil { panic("CloseNotify called after Handler finished") } rws.closeNotifierMu.Lock() ch := rws.closeNotifierCh if ch == nil { ch = make(chan bool, 1) rws.closeNotifierCh = ch cw := rws.stream.cw go func() { cw.Wait() // wait for close ch <- true }() } rws.closeNotifierMu.Unlock() return ch } func (w *responseWriter) Header() http.Header { rws := w.rws if rws == nil { panic("Header called after Handler finished") } if rws.handlerHeader == nil { rws.handlerHeader = make(http.Header) } return rws.handlerHeader } // checkWriteHeaderCode is a copy of net/http's checkWriteHeaderCode. func checkWriteHeaderCode(code int) { // Issue 22880: require valid WriteHeader status codes. // For now we only enforce that it's three digits. // In the future we might block things over 599 (600 and above aren't defined // at http://httpwg.org/specs/rfc7231.html#status.codes) // and we might block under 200 (once we have more mature 1xx support). // But for now any three digits. // // We used to send "HTTP/1.1 000 0" on the wire in responses but there's // no equivalent bogus thing we can realistically send in HTTP/2, // so we'll consistently panic instead and help people find their bugs // early. (We can't return an error from WriteHeader even if we wanted to.) if code < 100 || code > 999 { panic(fmt.Sprintf("invalid WriteHeader code %v", code)) } } func (w *responseWriter) WriteHeader(code int) { rws := w.rws if rws == nil { panic("WriteHeader called after Handler finished") } rws.writeHeader(code) } func (rws *responseWriterState) writeHeader(code int) { if !rws.wroteHeader { checkWriteHeaderCode(code) rws.wroteHeader = true rws.status = code if len(rws.handlerHeader) > 0 { rws.snapHeader = cloneHeader(rws.handlerHeader) } } } func cloneHeader(h http.Header) http.Header { h2 := make(http.Header, len(h)) for k, vv := range h { vv2 := make([]string, len(vv)) copy(vv2, vv) h2[k] = vv2 } return h2 } // The Life Of A Write is like this: // // * Handler calls w.Write or w.WriteString -> // * -> rws.bw (*bufio.Writer) -> // * (Handler might call Flush) // * -> chunkWriter{rws} // * -> responseWriterState.writeChunk(p []byte) // * -> responseWriterState.writeChunk (most of the magic; see comment there) func (w *responseWriter) Write(p []byte) (n int, err error) { return w.write(len(p), p, "") } func (w *responseWriter) WriteString(s string) (n int, err error) { return w.write(len(s), nil, s) } // either dataB or dataS is non-zero. func (w *responseWriter) write(lenData int, dataB []byte, dataS string) (n int, err error) { rws := w.rws if rws == nil { panic("Write called after Handler finished") } if !rws.wroteHeader { w.WriteHeader(200) } if !bodyAllowedForStatus(rws.status) { return 0, http.ErrBodyNotAllowed } rws.wroteBytes += int64(len(dataB)) + int64(len(dataS)) // only one can be set if rws.sentContentLen != 0 && rws.wroteBytes > rws.sentContentLen { // TODO: send a RST_STREAM return 0, errors.New("http2: handler wrote more than declared Content-Length") } if dataB != nil { return rws.bw.Write(dataB) } else { return rws.bw.WriteString(dataS) } } func (w *responseWriter) handlerDone() { rws := w.rws dirty := rws.dirty rws.handlerDone = true w.Flush() w.rws = nil if !dirty { // Only recycle the pool if all prior Write calls to // the serverConn goroutine completed successfully. If // they returned earlier due to resets from the peer // there might still be write goroutines outstanding // from the serverConn referencing the rws memory. See // issue 20704. responseWriterStatePool.Put(rws) } } // Push errors. var ( ErrRecursivePush = errors.New("http2: recursive push not allowed") ErrPushLimitReached = errors.New("http2: push would exceed peer's SETTINGS_MAX_CONCURRENT_STREAMS") ) var _ http.Pusher = (*responseWriter)(nil) func (w *responseWriter) Push(target string, opts *http.PushOptions) error { st := w.rws.stream sc := st.sc sc.serveG.checkNotOn() // No recursive pushes: "PUSH_PROMISE frames MUST only be sent on a peer-initiated stream." // http://tools.ietf.org/html/rfc7540#section-6.6 if st.isPushed() { return ErrRecursivePush } if opts == nil { opts = new(http.PushOptions) } // Default options. if opts.Method == "" { opts.Method = "GET" } if opts.Header == nil { opts.Header = http.Header{} } wantScheme := "http" if w.rws.req.TLS != nil { wantScheme = "https" } // Validate the request. u, err := url.Parse(target) if err != nil { return err } if u.Scheme == "" { if !strings.HasPrefix(target, "/") { return fmt.Errorf("target must be an absolute URL or an absolute path: %q", target) } u.Scheme = wantScheme u.Host = w.rws.req.Host } else { if u.Scheme != wantScheme { return fmt.Errorf("cannot push URL with scheme %q from request with scheme %q", u.Scheme, wantScheme) } if u.Host == "" { return errors.New("URL must have a host") } } for k := range opts.Header { if strings.HasPrefix(k, ":") { return fmt.Errorf("promised request headers cannot include pseudo header %q", k) } // These headers are meaningful only if the request has a body, // but PUSH_PROMISE requests cannot have a body. // http://tools.ietf.org/html/rfc7540#section-8.2 // Also disallow Host, since the promised URL must be absolute. switch strings.ToLower(k) { case "content-length", "content-encoding", "trailer", "te", "expect", "host": return fmt.Errorf("promised request headers cannot include %q", k) } } if err := checkValidHTTP2RequestHeaders(opts.Header); err != nil { return err } // The RFC effectively limits promised requests to GET and HEAD: // "Promised requests MUST be cacheable [GET, HEAD, or POST], and MUST be safe [GET or HEAD]" // http://tools.ietf.org/html/rfc7540#section-8.2 if opts.Method != "GET" && opts.Method != "HEAD" { return fmt.Errorf("method %q must be GET or HEAD", opts.Method) } msg := &startPushRequest{ parent: st, method: opts.Method, url: u, header: cloneHeader(opts.Header), done: errChanPool.Get().(chan error), } select { case <-sc.doneServing: return errClientDisconnected case <-st.cw: return errStreamClosed case sc.serveMsgCh <- msg: } select { case <-sc.doneServing: return errClientDisconnected case <-st.cw: return errStreamClosed case err := <-msg.done: errChanPool.Put(msg.done) return err } } type startPushRequest struct { parent *stream method string url *url.URL header http.Header done chan error } func (sc *serverConn) startPush(msg *startPushRequest) { sc.serveG.check() // http://tools.ietf.org/html/rfc7540#section-6.6. // PUSH_PROMISE frames MUST only be sent on a peer-initiated stream that // is in either the "open" or "half-closed (remote)" state. if msg.parent.state != stateOpen && msg.parent.state != stateHalfClosedRemote { // responseWriter.Push checks that the stream is peer-initiaed. msg.done <- errStreamClosed return } // http://tools.ietf.org/html/rfc7540#section-6.6. if !sc.pushEnabled { msg.done <- http.ErrNotSupported return } // PUSH_PROMISE frames must be sent in increasing order by stream ID, so // we allocate an ID for the promised stream lazily, when the PUSH_PROMISE // is written. Once the ID is allocated, we start the request handler. allocatePromisedID := func() (uint32, error) { sc.serveG.check() // Check this again, just in case. Technically, we might have received // an updated SETTINGS by the time we got around to writing this frame. if !sc.pushEnabled { return 0, http.ErrNotSupported } // http://tools.ietf.org/html/rfc7540#section-6.5.2. if sc.curPushedStreams+1 > sc.clientMaxStreams { return 0, ErrPushLimitReached } // http://tools.ietf.org/html/rfc7540#section-5.1.1. // Streams initiated by the server MUST use even-numbered identifiers. // A server that is unable to establish a new stream identifier can send a GOAWAY // frame so that the client is forced to open a new connection for new streams. if sc.maxPushPromiseID+2 >= 1<<31 { sc.startGracefulShutdownInternal() return 0, ErrPushLimitReached } sc.maxPushPromiseID += 2 promisedID := sc.maxPushPromiseID // http://tools.ietf.org/html/rfc7540#section-8.2. // Strictly speaking, the new stream should start in "reserved (local)", then // transition to "half closed (remote)" after sending the initial HEADERS, but // we start in "half closed (remote)" for simplicity. // See further comments at the definition of stateHalfClosedRemote. promised := sc.newStream(promisedID, msg.parent.id, stateHalfClosedRemote) rw, req, err := sc.newWriterAndRequestNoBody(promised, requestParam{ method: msg.method, scheme: msg.url.Scheme, authority: msg.url.Host, path: msg.url.RequestURI(), header: cloneHeader(msg.header), // clone since handler runs concurrently with writing the PUSH_PROMISE }) if err != nil { // Should not happen, since we've already validated msg.url. panic(fmt.Sprintf("newWriterAndRequestNoBody(%+v): %v", msg.url, err)) } go sc.runHandler(rw, req, sc.handler.ServeHTTP) return promisedID, nil } sc.writeFrame(FrameWriteRequest{ write: &writePushPromise{ streamID: msg.parent.id, method: msg.method, url: msg.url, h: msg.header, allocatePromisedID: allocatePromisedID, }, stream: msg.parent, done: msg.done, }) } // foreachHeaderElement splits v according to the "#rule" construction // in RFC 7230 section 7 and calls fn for each non-empty element. func foreachHeaderElement(v string, fn func(string)) { v = textproto.TrimString(v) if v == "" { return } if !strings.Contains(v, ",") { fn(v) return } for _, f := range strings.Split(v, ",") { if f = textproto.TrimString(f); f != "" { fn(f) } } } // From http://httpwg.org/specs/rfc7540.html#rfc.section.8.1.2.2 var connHeaders = []string{ "Connection", "Keep-Alive", "Proxy-Connection", "Transfer-Encoding", "Upgrade", } // checkValidHTTP2RequestHeaders checks whether h is a valid HTTP/2 request, // per RFC 7540 Section 8.1.2.2. // The returned error is reported to users. func checkValidHTTP2RequestHeaders(h http.Header) error { for _, k := range connHeaders { if _, ok := h[k]; ok { return fmt.Errorf("request header %q is not valid in HTTP/2", k) } } te := h["Te"] if len(te) > 0 && (len(te) > 1 || (te[0] != "trailers" && te[0] != "")) { return errors.New(`request header "TE" may only be "trailers" in HTTP/2`) } return nil } func new400Handler(err error) http.HandlerFunc { return func(w http.ResponseWriter, r *http.Request) { http.Error(w, err.Error(), http.StatusBadRequest) } } // h1ServerKeepAlivesDisabled reports whether hs has its keep-alives // disabled. See comments on h1ServerShutdownChan above for why // the code is written this way. func h1ServerKeepAlivesDisabled(hs *http.Server) bool { var x interface{} = hs type I interface { doKeepAlives() bool } if hs, ok := x.(I); ok { return !hs.doKeepAlives() } return false }