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server.go
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// 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: replace all <-sc.doneServing with reads from the stream's cw
// instead, and make sure that on close we close all open
// streams. then remove doneServing?
// TODO: re-audit GOAWAY support. Consider each incoming frame type and
// whether it should be ignored during graceful shutdown.
// TODO: disconnect idle clients. GFE seems to do 4 minutes. make
// configurable? or maximum number of idle clients and remove the
// oldest?
// 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"
"crypto/tls"
"errors"
"fmt"
"io"
"log"
"net"
"net/http"
"net/textproto"
"net/url"
"os"
"reflect"
"runtime"
"strconv"
"strings"
"sync"
"time"
"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?
)
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
}
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
}
// 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 conf == nil {
conf = new(Server)
}
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.
const requiredCipher = tls.TLS_ECDHE_RSA_WITH_AES_128_GCM_SHA256
haveRequired := false
sawBad := false
for i, cs := range s.TLSConfig.CipherSuites {
if cs == requiredCipher {
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 HTTP/2-required TLS_ECDHE_RSA_WITH_AES_128_GCM_SHA256")
}
}
// 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)
}
// h2-14 is temporary (as of 2015-03-05) while we wait for all browsers
// to switch to "h2".
s.TLSConfig.NextProtos = append(s.TLSConfig.NextProtos, "h2-14")
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
s.TLSNextProto["h2-14"] = protoHandler // temporary; see above.
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 frameWriteMsg, 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{}),
advMaxStreams: s.maxConcurrentStreams(),
writeSched: writeScheduler{
maxFrameSize: initialMaxFrameSize,
},
initialWindowSize: initialWindowSize,
headerTableSize: initialHeaderTableSize,
serveG: newGoroutineLock(),
pushEnabled: true,
}
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 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 (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 contextContext
framer *Framer
doneServing chan struct{} // closed when serverConn.serve ends
readFrameCh chan readFrameResult // written by serverConn.readFrames
wantWriteFrameCh chan frameWriteMsg // from handlers -> serve
wroteFrameCh chan frameWriteResult // from writeFrameAsync -> serve, tickles more frame writes
bodyReadCh chan bodyReadMsg // from handlers -> serve
testHookCh chan func(int) // code 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
// 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?
clientMaxStreams uint32 // SETTINGS_MAX_CONCURRENT_STREAMS from client (our PUSH_PROMISE limit)
advMaxStreams uint32 // our SETTINGS_MAX_CONCURRENT_STREAMS advertised the client
curOpenStreams uint32 // client's number of open streams
maxStreamID uint32 // max ever seen
streams map[uint32]*stream
initialWindowSize int32
headerTableSize uint32
peerMaxHeaderListSize uint32 // zero means unknown (default)
canonHeader map[string]string // http2-lower-case -> Go-Canonical-Case
writingFrame bool // started write goroutine but haven't heard back on wroteFrameCh
needsFrameFlush bool // last frame write wasn't a flush
writeSched writeScheduler
inGoAway bool // we've started to or sent GOAWAY
needToSendGoAway bool // we need to schedule a GOAWAY frame write
goAwayCode ErrCode
shutdownTimerCh <-chan time.Time // nil until used
shutdownTimer *time.Timer // nil until used
freeRequestBodyBuf []byte // if non-nil, a free initialWindowSize buffer for getRequestBodyBuf
// Owned by the writeFrameAsync goroutine:
headerWriteBuf bytes.Buffer
hpackEncoder *hpack.Encoder
}
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)
}
// 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 contextContext
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
sentReset bool // only true once detached from streams map
gotReset bool // only true once detacted from streams map
gotTrailerHeader bool // HEADER frame for trailers was seen
wroteHeaders bool // whether we wrote headers (not status 100)
reqBuf []byte
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://http2.github.io/http2-spec/#rfc.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 <= sc.maxStreamID {
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) {
// Boring, expected errors.
sc.vlogf(format, args...)
} else {
sc.logf(format, args...)
}
}
func (sc *serverConn) canonicalHeader(v string) string {
sc.serveG.check()
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 {
wm frameWriteMsg // 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(wm frameWriteMsg) {
err := wm.write.writeFrame(sc)
sc.wroteFrameCh <- frameWriteResult{wm, 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(frameWriteMsg{
write: writeSettings{
{SettingMaxFrameSize, sc.srv.maxReadFrameSize()},
{SettingMaxConcurrentStreams, sc.advMaxStreams},
{SettingMaxHeaderListSize, sc.maxHeaderListSize()},
// TODO: more actual settings, notably
// SettingInitialWindowSize, but then we also
// want to bump up the conn window size the
// same amount here right after the settings
},
})
sc.unackedSettings++
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)
go sc.readFrames() // closed by defer sc.conn.Close above
settingsTimer := time.NewTimer(firstSettingsTimeout)
loopNum := 0
for {
loopNum++
select {
case wm := <-sc.wantWriteFrameCh:
sc.writeFrame(wm)
case res := <-sc.wroteFrameCh:
sc.wroteFrame(res)
case res := <-sc.readFrameCh:
if !sc.processFrameFromReader(res) {
return
}
res.readMore()
if settingsTimer.C != nil {
settingsTimer.Stop()
settingsTimer.C = nil
}
case m := <-sc.bodyReadCh:
sc.noteBodyRead(m.st, m.n)
case <-settingsTimer.C:
sc.logf("timeout waiting for SETTINGS frames from %v", sc.conn.RemoteAddr())
return
case <-sc.shutdownTimerCh:
sc.vlogf("GOAWAY close timer fired; closing conn from %v", sc.conn.RemoteAddr())
return
case fn := <-sc.testHookCh:
fn(loopNum)
}
}
}
// readPreface reads the ClientPreface greeting from the peer
// or returns an error on timeout or an invalid greeting.
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 errors.New("timeout waiting for client preface")
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(frameWriteMsg{
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 wm 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(wm frameWriteMsg) error {
sc.serveG.checkNotOn() // NOT
select {
case sc.wantWriteFrameCh <- wm:
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(wm frameWriteMsg) {
sc.serveG.check()
var ignoreWrite bool
// Don't send a 100-continue response if we've already sent headers.
// See golang.org/issue/14030.
switch wm.write.(type) {
case *writeResHeaders:
wm.stream.wroteHeaders = true
case write100ContinueHeadersFrame:
if wm.stream.wroteHeaders {
ignoreWrite = true
}
}
if !ignoreWrite {
sc.writeSched.add(wm)
}
sc.scheduleFrameWrite()
}
// startFrameWrite starts a goroutine to write wm (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 wm.
func (sc *serverConn) startFrameWrite(wm frameWriteMsg) {
sc.serveG.check()
if sc.writingFrame {
panic("internal error: can only be writing one frame at a time")
}
st := wm.stream
if st != nil {
switch st.state {
case stateHalfClosedLocal:
panic("internal error: attempt to send frame on half-closed-local stream")
case stateClosed:
if st.sentReset || st.gotReset {
// Skip this frame.
sc.scheduleFrameWrite()
return
}
panic(fmt.Sprintf("internal error: attempt to send a write %v on a closed stream", wm))
}
}
sc.writingFrame = true
sc.needsFrameFlush = true
go sc.writeFrameAsync(wm)
}
// 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
// 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
wm := res.wm
st := wm.stream
closeStream := endsStream(wm.write)
if _, ok := wm.write.(handlerPanicRST); ok {
sc.closeStream(st, errHandlerPanicked)
}
// Reply (if requested) to the blocked ServeHTTP goroutine.
if ch := wm.done; ch != nil {
select {
case ch <- res.err:
default:
panic(fmt.Sprintf("unbuffered done channel passed in for type %T", wm.write))
}
}
wm.write = nil // prevent use (assume it's tainted after wm.done send)
if closeStream {
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 finishing writing to 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.
st.state = stateHalfClosedLocal // won't last long, but necessary for closeStream via resetStream
errCancel := StreamError{st.id, ErrCodeCancel}
sc.resetStream(errCancel)
case stateHalfClosedRemote:
sc.closeStream(st, errHandlerComplete)
}
}
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 we need to send one, the best frame
// to send is selected, preferring first things that aren't
// stream-specific (e.g. ACKing settings), and then finding the
// highest priority stream.
//
// 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 {
return
}
if sc.needToSendGoAway {
sc.needToSendGoAway = false
sc.startFrameWrite(frameWriteMsg{
write: &writeGoAway{
maxStreamID: sc.maxStreamID,
code: sc.goAwayCode,
},
})
return
}
if sc.needToSendSettingsAck {
sc.needToSendSettingsAck = false
sc.startFrameWrite(frameWriteMsg{write: writeSettingsAck{}})
return
}
if !sc.inGoAway {
if wm, ok := sc.writeSched.take(); ok {
sc.startFrameWrite(wm)
return
}
}
if sc.needsFrameFlush {
sc.startFrameWrite(frameWriteMsg{write: flushFrameWriter{}})
sc.needsFrameFlush = false // after startFrameWrite, since it sets this true
return
}
}
func (sc *serverConn) goAway(code ErrCode) {
sc.serveG.check()
if sc.inGoAway {
return
}
if code != ErrCodeNo {
sc.shutDownIn(250 * time.Millisecond)
} else {
// TODO: configurable
sc.shutDownIn(1 * time.Second)
}
sc.inGoAway = true
sc.needToSendGoAway = true
sc.goAwayCode = code
sc.scheduleFrameWrite()
}
func (sc *serverConn) shutDownIn(d time.Duration) {
sc.serveG.check()
sc.shutdownTimer = time.NewTimer(d)
sc.shutdownTimerCh = sc.shutdownTimer.C