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transport.go
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transport.go
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// Copyright 2015 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.
// Transport code.
package http2
import (
"bufio"
"bytes"
"compress/gzip"
"context"
"crypto/rand"
"crypto/tls"
"errors"
"fmt"
"io"
"io/fs"
"log"
"math"
"math/bits"
mathrand "math/rand"
"net"
"net/http"
"net/http/httptrace"
"net/textproto"
"os"
"sort"
"strconv"
"strings"
"sync"
"sync/atomic"
"time"
"golang.org/x/net/http/httpguts"
"golang.org/x/net/http2/hpack"
"golang.org/x/net/idna"
)
const (
// transportDefaultConnFlow is how many connection-level flow control
// tokens we give the server at start-up, past the default 64k.
transportDefaultConnFlow = 1 << 30
// transportDefaultStreamFlow is how many stream-level flow
// control tokens we announce to the peer, and how many bytes
// we buffer per stream.
transportDefaultStreamFlow = 4 << 20
defaultUserAgent = "Go-http-client/2.0"
// initialMaxConcurrentStreams is a connections maxConcurrentStreams until
// it's received servers initial SETTINGS frame, which corresponds with the
// spec's minimum recommended value.
initialMaxConcurrentStreams = 100
// defaultMaxConcurrentStreams is a connections default maxConcurrentStreams
// if the server doesn't include one in its initial SETTINGS frame.
defaultMaxConcurrentStreams = 1000
)
// Transport is an HTTP/2 Transport.
//
// A Transport internally caches connections to servers. It is safe
// for concurrent use by multiple goroutines.
type Transport struct {
// DialTLSContext specifies an optional dial function with context for
// creating TLS connections for requests.
//
// If DialTLSContext and DialTLS is nil, tls.Dial is used.
//
// If the returned net.Conn has a ConnectionState method like tls.Conn,
// it will be used to set http.Response.TLS.
DialTLSContext func(ctx context.Context, network, addr string, cfg *tls.Config) (net.Conn, error)
// DialTLS specifies an optional dial function for creating
// TLS connections for requests.
//
// If DialTLSContext and DialTLS is nil, tls.Dial is used.
//
// Deprecated: Use DialTLSContext instead, which allows the transport
// to cancel dials as soon as they are no longer needed.
// If both are set, DialTLSContext takes priority.
DialTLS func(network, addr string, cfg *tls.Config) (net.Conn, error)
// TLSClientConfig specifies the TLS configuration to use with
// tls.Client. If nil, the default configuration is used.
TLSClientConfig *tls.Config
// ConnPool optionally specifies an alternate connection pool to use.
// If nil, the default is used.
ConnPool ClientConnPool
// DisableCompression, if true, prevents the Transport from
// requesting compression with an "Accept-Encoding: gzip"
// request header when the Request contains no existing
// Accept-Encoding value. If the Transport requests gzip on
// its own and gets a gzipped response, it's transparently
// decoded in the Response.Body. However, if the user
// explicitly requested gzip it is not automatically
// uncompressed.
DisableCompression bool
// AllowHTTP, if true, permits HTTP/2 requests using the insecure,
// plain-text "http" scheme. Note that this does not enable h2c support.
AllowHTTP bool
// MaxHeaderListSize is the http2 SETTINGS_MAX_HEADER_LIST_SIZE to
// send in the initial settings frame. It is how many bytes
// of response headers are allowed. Unlike the http2 spec, zero here
// means to use a default limit (currently 10MB). If you actually
// want to advertise an unlimited value to the peer, Transport
// interprets the highest possible value here (0xffffffff or 1<<32-1)
// to mean no limit.
MaxHeaderListSize uint32
// MaxReadFrameSize is the http2 SETTINGS_MAX_FRAME_SIZE to send in the
// initial settings frame. It is the size in bytes of the largest frame
// payload that the sender is willing to receive. If 0, no setting is
// sent, and the value is provided by the peer, which should be 16384
// according to the spec:
// https://datatracker.ietf.org/doc/html/rfc7540#section-6.5.2.
// Values are bounded in the range 16k to 16M.
MaxReadFrameSize uint32
// MaxDecoderHeaderTableSize optionally specifies the http2
// SETTINGS_HEADER_TABLE_SIZE to send in the initial settings frame. It
// informs the remote endpoint of the maximum size of the header compression
// table used to decode header blocks, in octets. If zero, the default value
// of 4096 is used.
MaxDecoderHeaderTableSize uint32
// MaxEncoderHeaderTableSize optionally specifies an upper limit for the
// header compression table used for encoding request headers. Received
// SETTINGS_HEADER_TABLE_SIZE settings are capped at this limit. If zero,
// the default value of 4096 is used.
MaxEncoderHeaderTableSize uint32
// StrictMaxConcurrentStreams controls whether the server's
// SETTINGS_MAX_CONCURRENT_STREAMS should be respected
// globally. If false, new TCP connections are created to the
// server as needed to keep each under the per-connection
// SETTINGS_MAX_CONCURRENT_STREAMS limit. If true, the
// server's SETTINGS_MAX_CONCURRENT_STREAMS is interpreted as
// a global limit and callers of RoundTrip block when needed,
// waiting for their turn.
StrictMaxConcurrentStreams bool
// IdleConnTimeout is the maximum amount of time an idle
// (keep-alive) connection will remain idle before closing
// itself.
// Zero means no limit.
IdleConnTimeout time.Duration
// ReadIdleTimeout is the timeout after which a health check using ping
// frame will be carried out if no frame is received on the connection.
// Note that a ping response will is considered a received frame, so if
// there is no other traffic on the connection, the health check will
// be performed every ReadIdleTimeout interval.
// If zero, no health check is performed.
ReadIdleTimeout time.Duration
// PingTimeout is the timeout after which the connection will be closed
// if a response to Ping is not received.
// Defaults to 15s.
PingTimeout time.Duration
// WriteByteTimeout is the timeout after which the connection will be
// closed no data can be written to it. The timeout begins when data is
// available to write, and is extended whenever any bytes are written.
WriteByteTimeout time.Duration
// CountError, if non-nil, is called on HTTP/2 transport errors.
// It's intended to increment a metric for monitoring, such
// as an expvar or Prometheus metric.
// The errType consists of only ASCII word characters.
CountError func(errType string)
// t1, if non-nil, is the standard library Transport using
// this transport. Its settings are used (but not its
// RoundTrip method, etc).
t1 *http.Transport
connPoolOnce sync.Once
connPoolOrDef ClientConnPool // non-nil version of ConnPool
*transportTestHooks
}
// Hook points used for testing.
// Outside of tests, t.transportTestHooks is nil and these all have minimal implementations.
// Inside tests, see the testSyncHooks function docs.
type transportTestHooks struct {
newclientconn func(*ClientConn)
group synctestGroupInterface
}
func (t *Transport) markNewGoroutine() {
if t != nil && t.transportTestHooks != nil {
t.transportTestHooks.group.Join()
}
}
// newTimer creates a new time.Timer, or a synthetic timer in tests.
func (t *Transport) newTimer(d time.Duration) timer {
if t.transportTestHooks != nil {
return t.transportTestHooks.group.NewTimer(d)
}
return timeTimer{time.NewTimer(d)}
}
// afterFunc creates a new time.AfterFunc timer, or a synthetic timer in tests.
func (t *Transport) afterFunc(d time.Duration, f func()) timer {
if t.transportTestHooks != nil {
return t.transportTestHooks.group.AfterFunc(d, f)
}
return timeTimer{time.AfterFunc(d, f)}
}
func (t *Transport) contextWithTimeout(ctx context.Context, d time.Duration) (context.Context, context.CancelFunc) {
if t.transportTestHooks != nil {
return t.transportTestHooks.group.ContextWithTimeout(ctx, d)
}
return context.WithTimeout(ctx, d)
}
func (t *Transport) maxHeaderListSize() uint32 {
if t.MaxHeaderListSize == 0 {
return 10 << 20
}
if t.MaxHeaderListSize == 0xffffffff {
return 0
}
return t.MaxHeaderListSize
}
func (t *Transport) maxFrameReadSize() uint32 {
if t.MaxReadFrameSize == 0 {
return 0 // use the default provided by the peer
}
if t.MaxReadFrameSize < minMaxFrameSize {
return minMaxFrameSize
}
if t.MaxReadFrameSize > maxFrameSize {
return maxFrameSize
}
return t.MaxReadFrameSize
}
func (t *Transport) disableCompression() bool {
return t.DisableCompression || (t.t1 != nil && t.t1.DisableCompression)
}
func (t *Transport) pingTimeout() time.Duration {
if t.PingTimeout == 0 {
return 15 * time.Second
}
return t.PingTimeout
}
// ConfigureTransport configures a net/http HTTP/1 Transport to use HTTP/2.
// It returns an error if t1 has already been HTTP/2-enabled.
//
// Use ConfigureTransports instead to configure the HTTP/2 Transport.
func ConfigureTransport(t1 *http.Transport) error {
_, err := ConfigureTransports(t1)
return err
}
// ConfigureTransports configures a net/http HTTP/1 Transport to use HTTP/2.
// It returns a new HTTP/2 Transport for further configuration.
// It returns an error if t1 has already been HTTP/2-enabled.
func ConfigureTransports(t1 *http.Transport) (*Transport, error) {
return configureTransports(t1)
}
func configureTransports(t1 *http.Transport) (*Transport, error) {
connPool := new(clientConnPool)
t2 := &Transport{
ConnPool: noDialClientConnPool{connPool},
t1: t1,
}
connPool.t = t2
if err := registerHTTPSProtocol(t1, noDialH2RoundTripper{t2}); err != nil {
return nil, err
}
if t1.TLSClientConfig == nil {
t1.TLSClientConfig = new(tls.Config)
}
if !strSliceContains(t1.TLSClientConfig.NextProtos, "h2") {
t1.TLSClientConfig.NextProtos = append([]string{"h2"}, t1.TLSClientConfig.NextProtos...)
}
if !strSliceContains(t1.TLSClientConfig.NextProtos, "http/1.1") {
t1.TLSClientConfig.NextProtos = append(t1.TLSClientConfig.NextProtos, "http/1.1")
}
upgradeFn := func(authority string, c *tls.Conn) http.RoundTripper {
addr := authorityAddr("https", authority)
if used, err := connPool.addConnIfNeeded(addr, t2, c); err != nil {
go c.Close()
return erringRoundTripper{err}
} else if !used {
// Turns out we don't need this c.
// For example, two goroutines made requests to the same host
// at the same time, both kicking off TCP dials. (since protocol
// was unknown)
go c.Close()
}
return t2
}
if m := t1.TLSNextProto; len(m) == 0 {
t1.TLSNextProto = map[string]func(string, *tls.Conn) http.RoundTripper{
"h2": upgradeFn,
}
} else {
m["h2"] = upgradeFn
}
return t2, nil
}
func (t *Transport) connPool() ClientConnPool {
t.connPoolOnce.Do(t.initConnPool)
return t.connPoolOrDef
}
func (t *Transport) initConnPool() {
if t.ConnPool != nil {
t.connPoolOrDef = t.ConnPool
} else {
t.connPoolOrDef = &clientConnPool{t: t}
}
}
// ClientConn is the state of a single HTTP/2 client connection to an
// HTTP/2 server.
type ClientConn struct {
t *Transport
tconn net.Conn // usually *tls.Conn, except specialized impls
tlsState *tls.ConnectionState // nil only for specialized impls
reused uint32 // whether conn is being reused; atomic
singleUse bool // whether being used for a single http.Request
getConnCalled bool // used by clientConnPool
// readLoop goroutine fields:
readerDone chan struct{} // closed on error
readerErr error // set before readerDone is closed
idleTimeout time.Duration // or 0 for never
idleTimer timer
mu sync.Mutex // guards following
cond *sync.Cond // hold mu; broadcast on flow/closed changes
flow outflow // our conn-level flow control quota (cs.outflow is per stream)
inflow inflow // peer's conn-level flow control
doNotReuse bool // whether conn is marked to not be reused for any future requests
closing bool
closed bool
seenSettings bool // true if we've seen a settings frame, false otherwise
wantSettingsAck bool // we sent a SETTINGS frame and haven't heard back
goAway *GoAwayFrame // if non-nil, the GoAwayFrame we received
goAwayDebug string // goAway frame's debug data, retained as a string
streams map[uint32]*clientStream // client-initiated
streamsReserved int // incr by ReserveNewRequest; decr on RoundTrip
nextStreamID uint32
pendingRequests int // requests blocked and waiting to be sent because len(streams) == maxConcurrentStreams
pings map[[8]byte]chan struct{} // in flight ping data to notification channel
br *bufio.Reader
lastActive time.Time
lastIdle time.Time // time last idle
// Settings from peer: (also guarded by wmu)
maxFrameSize uint32
maxConcurrentStreams uint32
peerMaxHeaderListSize uint64
peerMaxHeaderTableSize uint32
initialWindowSize uint32
// reqHeaderMu is a 1-element semaphore channel controlling access to sending new requests.
// Write to reqHeaderMu to lock it, read from it to unlock.
// Lock reqmu BEFORE mu or wmu.
reqHeaderMu chan struct{}
// wmu is held while writing.
// Acquire BEFORE mu when holding both, to avoid blocking mu on network writes.
// Only acquire both at the same time when changing peer settings.
wmu sync.Mutex
bw *bufio.Writer
fr *Framer
werr error // first write error that has occurred
hbuf bytes.Buffer // HPACK encoder writes into this
henc *hpack.Encoder
}
// clientStream is the state for a single HTTP/2 stream. One of these
// is created for each Transport.RoundTrip call.
type clientStream struct {
cc *ClientConn
// Fields of Request that we may access even after the response body is closed.
ctx context.Context
reqCancel <-chan struct{}
trace *httptrace.ClientTrace // or nil
ID uint32
bufPipe pipe // buffered pipe with the flow-controlled response payload
requestedGzip bool
isHead bool
abortOnce sync.Once
abort chan struct{} // closed to signal stream should end immediately
abortErr error // set if abort is closed
peerClosed chan struct{} // closed when the peer sends an END_STREAM flag
donec chan struct{} // closed after the stream is in the closed state
on100 chan struct{} // buffered; written to if a 100 is received
respHeaderRecv chan struct{} // closed when headers are received
res *http.Response // set if respHeaderRecv is closed
flow outflow // guarded by cc.mu
inflow inflow // guarded by cc.mu
bytesRemain int64 // -1 means unknown; owned by transportResponseBody.Read
readErr error // sticky read error; owned by transportResponseBody.Read
reqBody io.ReadCloser
reqBodyContentLength int64 // -1 means unknown
reqBodyClosed chan struct{} // guarded by cc.mu; non-nil on Close, closed when done
// owned by writeRequest:
sentEndStream bool // sent an END_STREAM flag to the peer
sentHeaders bool
// owned by clientConnReadLoop:
firstByte bool // got the first response byte
pastHeaders bool // got first MetaHeadersFrame (actual headers)
pastTrailers bool // got optional second MetaHeadersFrame (trailers)
num1xx uint8 // number of 1xx responses seen
readClosed bool // peer sent an END_STREAM flag
readAborted bool // read loop reset the stream
trailer http.Header // accumulated trailers
resTrailer *http.Header // client's Response.Trailer
}
var got1xxFuncForTests func(int, textproto.MIMEHeader) error
// get1xxTraceFunc returns the value of request's httptrace.ClientTrace.Got1xxResponse func,
// if any. It returns nil if not set or if the Go version is too old.
func (cs *clientStream) get1xxTraceFunc() func(int, textproto.MIMEHeader) error {
if fn := got1xxFuncForTests; fn != nil {
return fn
}
return traceGot1xxResponseFunc(cs.trace)
}
func (cs *clientStream) abortStream(err error) {
cs.cc.mu.Lock()
defer cs.cc.mu.Unlock()
cs.abortStreamLocked(err)
}
func (cs *clientStream) abortStreamLocked(err error) {
cs.abortOnce.Do(func() {
cs.abortErr = err
close(cs.abort)
})
if cs.reqBody != nil {
cs.closeReqBodyLocked()
}
// TODO(dneil): Clean up tests where cs.cc.cond is nil.
if cs.cc.cond != nil {
// Wake up writeRequestBody if it is waiting on flow control.
cs.cc.cond.Broadcast()
}
}
func (cs *clientStream) abortRequestBodyWrite() {
cc := cs.cc
cc.mu.Lock()
defer cc.mu.Unlock()
if cs.reqBody != nil && cs.reqBodyClosed == nil {
cs.closeReqBodyLocked()
cc.cond.Broadcast()
}
}
func (cs *clientStream) closeReqBodyLocked() {
if cs.reqBodyClosed != nil {
return
}
cs.reqBodyClosed = make(chan struct{})
reqBodyClosed := cs.reqBodyClosed
go func() {
cs.cc.t.markNewGoroutine()
cs.reqBody.Close()
close(reqBodyClosed)
}()
}
type stickyErrWriter struct {
conn net.Conn
timeout time.Duration
err *error
}
func (sew stickyErrWriter) Write(p []byte) (n int, err error) {
if *sew.err != nil {
return 0, *sew.err
}
for {
if sew.timeout != 0 {
sew.conn.SetWriteDeadline(time.Now().Add(sew.timeout))
}
nn, err := sew.conn.Write(p[n:])
n += nn
if n < len(p) && nn > 0 && errors.Is(err, os.ErrDeadlineExceeded) {
// Keep extending the deadline so long as we're making progress.
continue
}
if sew.timeout != 0 {
sew.conn.SetWriteDeadline(time.Time{})
}
*sew.err = err
return n, err
}
}
// noCachedConnError is the concrete type of ErrNoCachedConn, which
// needs to be detected by net/http regardless of whether it's its
// bundled version (in h2_bundle.go with a rewritten type name) or
// from a user's x/net/http2. As such, as it has a unique method name
// (IsHTTP2NoCachedConnError) that net/http sniffs for via func
// isNoCachedConnError.
type noCachedConnError struct{}
func (noCachedConnError) IsHTTP2NoCachedConnError() {}
func (noCachedConnError) Error() string { return "http2: no cached connection was available" }
// isNoCachedConnError reports whether err is of type noCachedConnError
// or its equivalent renamed type in net/http2's h2_bundle.go. Both types
// may coexist in the same running program.
func isNoCachedConnError(err error) bool {
_, ok := err.(interface{ IsHTTP2NoCachedConnError() })
return ok
}
var ErrNoCachedConn error = noCachedConnError{}
// RoundTripOpt are options for the Transport.RoundTripOpt method.
type RoundTripOpt struct {
// OnlyCachedConn controls whether RoundTripOpt may
// create a new TCP connection. If set true and
// no cached connection is available, RoundTripOpt
// will return ErrNoCachedConn.
OnlyCachedConn bool
}
func (t *Transport) RoundTrip(req *http.Request) (*http.Response, error) {
return t.RoundTripOpt(req, RoundTripOpt{})
}
// authorityAddr returns a given authority (a host/IP, or host:port / ip:port)
// and returns a host:port. The port 443 is added if needed.
func authorityAddr(scheme string, authority string) (addr string) {
host, port, err := net.SplitHostPort(authority)
if err != nil { // authority didn't have a port
host = authority
port = ""
}
if port == "" { // authority's port was empty
port = "443"
if scheme == "http" {
port = "80"
}
}
if a, err := idna.ToASCII(host); err == nil {
host = a
}
// IPv6 address literal, without a port:
if strings.HasPrefix(host, "[") && strings.HasSuffix(host, "]") {
return host + ":" + port
}
return net.JoinHostPort(host, port)
}
// RoundTripOpt is like RoundTrip, but takes options.
func (t *Transport) RoundTripOpt(req *http.Request, opt RoundTripOpt) (*http.Response, error) {
if !(req.URL.Scheme == "https" || (req.URL.Scheme == "http" && t.AllowHTTP)) {
return nil, errors.New("http2: unsupported scheme")
}
addr := authorityAddr(req.URL.Scheme, req.URL.Host)
for retry := 0; ; retry++ {
cc, err := t.connPool().GetClientConn(req, addr)
if err != nil {
t.vlogf("http2: Transport failed to get client conn for %s: %v", addr, err)
return nil, err
}
reused := !atomic.CompareAndSwapUint32(&cc.reused, 0, 1)
traceGotConn(req, cc, reused)
res, err := cc.RoundTrip(req)
if err != nil && retry <= 6 {
roundTripErr := err
if req, err = shouldRetryRequest(req, err); err == nil {
// After the first retry, do exponential backoff with 10% jitter.
if retry == 0 {
t.vlogf("RoundTrip retrying after failure: %v", roundTripErr)
continue
}
backoff := float64(uint(1) << (uint(retry) - 1))
backoff += backoff * (0.1 * mathrand.Float64())
d := time.Second * time.Duration(backoff)
tm := t.newTimer(d)
select {
case <-tm.C():
t.vlogf("RoundTrip retrying after failure: %v", roundTripErr)
continue
case <-req.Context().Done():
tm.Stop()
err = req.Context().Err()
}
}
}
if err != nil {
t.vlogf("RoundTrip failure: %v", err)
return nil, err
}
return res, nil
}
}
// CloseIdleConnections closes any connections which were previously
// connected from previous requests but are now sitting idle.
// It does not interrupt any connections currently in use.
func (t *Transport) CloseIdleConnections() {
if cp, ok := t.connPool().(clientConnPoolIdleCloser); ok {
cp.closeIdleConnections()
}
}
var (
errClientConnClosed = errors.New("http2: client conn is closed")
errClientConnUnusable = errors.New("http2: client conn not usable")
errClientConnGotGoAway = errors.New("http2: Transport received Server's graceful shutdown GOAWAY")
)
// shouldRetryRequest is called by RoundTrip when a request fails to get
// response headers. It is always called with a non-nil error.
// It returns either a request to retry (either the same request, or a
// modified clone), or an error if the request can't be replayed.
func shouldRetryRequest(req *http.Request, err error) (*http.Request, error) {
if !canRetryError(err) {
return nil, err
}
// If the Body is nil (or http.NoBody), it's safe to reuse
// this request and its Body.
if req.Body == nil || req.Body == http.NoBody {
return req, nil
}
// If the request body can be reset back to its original
// state via the optional req.GetBody, do that.
if req.GetBody != nil {
body, err := req.GetBody()
if err != nil {
return nil, err
}
newReq := *req
newReq.Body = body
return &newReq, nil
}
// The Request.Body can't reset back to the beginning, but we
// don't seem to have started to read from it yet, so reuse
// the request directly.
if err == errClientConnUnusable {
return req, nil
}
return nil, fmt.Errorf("http2: Transport: cannot retry err [%v] after Request.Body was written; define Request.GetBody to avoid this error", err)
}
func canRetryError(err error) bool {
if err == errClientConnUnusable || err == errClientConnGotGoAway {
return true
}
if se, ok := err.(StreamError); ok {
if se.Code == ErrCodeProtocol && se.Cause == errFromPeer {
// See golang/go#47635, golang/go#42777
return true
}
return se.Code == ErrCodeRefusedStream
}
return false
}
func (t *Transport) dialClientConn(ctx context.Context, addr string, singleUse bool) (*ClientConn, error) {
if t.transportTestHooks != nil {
return t.newClientConn(nil, singleUse)
}
host, _, err := net.SplitHostPort(addr)
if err != nil {
return nil, err
}
tconn, err := t.dialTLS(ctx, "tcp", addr, t.newTLSConfig(host))
if err != nil {
return nil, err
}
return t.newClientConn(tconn, singleUse)
}
func (t *Transport) newTLSConfig(host string) *tls.Config {
cfg := new(tls.Config)
if t.TLSClientConfig != nil {
*cfg = *t.TLSClientConfig.Clone()
}
if !strSliceContains(cfg.NextProtos, NextProtoTLS) {
cfg.NextProtos = append([]string{NextProtoTLS}, cfg.NextProtos...)
}
if cfg.ServerName == "" {
cfg.ServerName = host
}
return cfg
}
func (t *Transport) dialTLS(ctx context.Context, network, addr string, tlsCfg *tls.Config) (net.Conn, error) {
if t.DialTLSContext != nil {
return t.DialTLSContext(ctx, network, addr, tlsCfg)
} else if t.DialTLS != nil {
return t.DialTLS(network, addr, tlsCfg)
}
tlsCn, err := t.dialTLSWithContext(ctx, network, addr, tlsCfg)
if err != nil {
return nil, err
}
state := tlsCn.ConnectionState()
if p := state.NegotiatedProtocol; p != NextProtoTLS {
return nil, fmt.Errorf("http2: unexpected ALPN protocol %q; want %q", p, NextProtoTLS)
}
if !state.NegotiatedProtocolIsMutual {
return nil, errors.New("http2: could not negotiate protocol mutually")
}
return tlsCn, nil
}
// disableKeepAlives reports whether connections should be closed as
// soon as possible after handling the first request.
func (t *Transport) disableKeepAlives() bool {
return t.t1 != nil && t.t1.DisableKeepAlives
}
func (t *Transport) expectContinueTimeout() time.Duration {
if t.t1 == nil {
return 0
}
return t.t1.ExpectContinueTimeout
}
func (t *Transport) maxDecoderHeaderTableSize() uint32 {
if v := t.MaxDecoderHeaderTableSize; v > 0 {
return v
}
return initialHeaderTableSize
}
func (t *Transport) maxEncoderHeaderTableSize() uint32 {
if v := t.MaxEncoderHeaderTableSize; v > 0 {
return v
}
return initialHeaderTableSize
}
func (t *Transport) NewClientConn(c net.Conn) (*ClientConn, error) {
return t.newClientConn(c, t.disableKeepAlives())
}
func (t *Transport) newClientConn(c net.Conn, singleUse bool) (*ClientConn, error) {
cc := &ClientConn{
t: t,
tconn: c,
readerDone: make(chan struct{}),
nextStreamID: 1,
maxFrameSize: 16 << 10, // spec default
initialWindowSize: 65535, // spec default
maxConcurrentStreams: initialMaxConcurrentStreams, // "infinite", per spec. Use a smaller value until we have received server settings.
peerMaxHeaderListSize: 0xffffffffffffffff, // "infinite", per spec. Use 2^64-1 instead.
streams: make(map[uint32]*clientStream),
singleUse: singleUse,
wantSettingsAck: true,
pings: make(map[[8]byte]chan struct{}),
reqHeaderMu: make(chan struct{}, 1),
}
if t.transportTestHooks != nil {
t.markNewGoroutine()
t.transportTestHooks.newclientconn(cc)
c = cc.tconn
}
if VerboseLogs {
t.vlogf("http2: Transport creating client conn %p to %v", cc, c.RemoteAddr())
}
cc.cond = sync.NewCond(&cc.mu)
cc.flow.add(int32(initialWindowSize))
// TODO: adjust this writer size to account for frame size +
// MTU + crypto/tls record padding.
cc.bw = bufio.NewWriter(stickyErrWriter{
conn: c,
timeout: t.WriteByteTimeout,
err: &cc.werr,
})
cc.br = bufio.NewReader(c)
cc.fr = NewFramer(cc.bw, cc.br)
if t.maxFrameReadSize() != 0 {
cc.fr.SetMaxReadFrameSize(t.maxFrameReadSize())
}
if t.CountError != nil {
cc.fr.countError = t.CountError
}
maxHeaderTableSize := t.maxDecoderHeaderTableSize()
cc.fr.ReadMetaHeaders = hpack.NewDecoder(maxHeaderTableSize, nil)
cc.fr.MaxHeaderListSize = t.maxHeaderListSize()
cc.henc = hpack.NewEncoder(&cc.hbuf)
cc.henc.SetMaxDynamicTableSizeLimit(t.maxEncoderHeaderTableSize())
cc.peerMaxHeaderTableSize = initialHeaderTableSize
if cs, ok := c.(connectionStater); ok {
state := cs.ConnectionState()
cc.tlsState = &state
}
initialSettings := []Setting{
{ID: SettingEnablePush, Val: 0},
{ID: SettingInitialWindowSize, Val: transportDefaultStreamFlow},
}
if max := t.maxFrameReadSize(); max != 0 {
initialSettings = append(initialSettings, Setting{ID: SettingMaxFrameSize, Val: max})
}
if max := t.maxHeaderListSize(); max != 0 {
initialSettings = append(initialSettings, Setting{ID: SettingMaxHeaderListSize, Val: max})
}
if maxHeaderTableSize != initialHeaderTableSize {
initialSettings = append(initialSettings, Setting{ID: SettingHeaderTableSize, Val: maxHeaderTableSize})
}
cc.bw.Write(clientPreface)
cc.fr.WriteSettings(initialSettings...)
cc.fr.WriteWindowUpdate(0, transportDefaultConnFlow)
cc.inflow.init(transportDefaultConnFlow + initialWindowSize)
cc.bw.Flush()
if cc.werr != nil {
cc.Close()
return nil, cc.werr
}
// Start the idle timer after the connection is fully initialized.
if d := t.idleConnTimeout(); d != 0 {
cc.idleTimeout = d
cc.idleTimer = t.afterFunc(d, cc.onIdleTimeout)
}
go cc.readLoop()
return cc, nil
}
func (cc *ClientConn) healthCheck() {
pingTimeout := cc.t.pingTimeout()
// We don't need to periodically ping in the health check, because the readLoop of ClientConn will
// trigger the healthCheck again if there is no frame received.
ctx, cancel := cc.t.contextWithTimeout(context.Background(), pingTimeout)
defer cancel()
cc.vlogf("http2: Transport sending health check")
err := cc.Ping(ctx)
if err != nil {
cc.vlogf("http2: Transport health check failure: %v", err)
cc.closeForLostPing()
} else {
cc.vlogf("http2: Transport health check success")
}
}
// SetDoNotReuse marks cc as not reusable for future HTTP requests.
func (cc *ClientConn) SetDoNotReuse() {
cc.mu.Lock()
defer cc.mu.Unlock()
cc.doNotReuse = true
}
func (cc *ClientConn) setGoAway(f *GoAwayFrame) {
cc.mu.Lock()
defer cc.mu.Unlock()
old := cc.goAway
cc.goAway = f
// Merge the previous and current GoAway error frames.
if cc.goAwayDebug == "" {
cc.goAwayDebug = string(f.DebugData())
}
if old != nil && old.ErrCode != ErrCodeNo {
cc.goAway.ErrCode = old.ErrCode
}
last := f.LastStreamID
for streamID, cs := range cc.streams {
if streamID <= last {
// The server's GOAWAY indicates that it received this stream.
// It will either finish processing it, or close the connection
// without doing so. Either way, leave the stream alone for now.
continue
}
if streamID == 1 && cc.goAway.ErrCode != ErrCodeNo {
// Don't retry the first stream on a connection if we get a non-NO error.
// If the server is sending an error on a new connection,
// retrying the request on a new one probably isn't going to work.
cs.abortStreamLocked(fmt.Errorf("http2: Transport received GOAWAY from server ErrCode:%v", cc.goAway.ErrCode))
} else {
// Aborting the stream with errClentConnGotGoAway indicates that
// the request should be retried on a new connection.
cs.abortStreamLocked(errClientConnGotGoAway)
}
}
}
// CanTakeNewRequest reports whether the connection can take a new request,
// meaning it has not been closed or received or sent a GOAWAY.
//
// If the caller is going to immediately make a new request on this
// connection, use ReserveNewRequest instead.
func (cc *ClientConn) CanTakeNewRequest() bool {
cc.mu.Lock()
defer cc.mu.Unlock()
return cc.canTakeNewRequestLocked()
}
// ReserveNewRequest is like CanTakeNewRequest but also reserves a
// concurrent stream in cc. The reservation is decremented on the
// next call to RoundTrip.
func (cc *ClientConn) ReserveNewRequest() bool {
cc.mu.Lock()
defer cc.mu.Unlock()
if st := cc.idleStateLocked(); !st.canTakeNewRequest {
return false
}
cc.streamsReserved++
return true
}
// ClientConnState describes the state of a ClientConn.
type ClientConnState struct {
// Closed is whether the connection is closed.
Closed bool
// Closing is whether the connection is in the process of
// closing. It may be closing due to shutdown, being a
// single-use connection, being marked as DoNotReuse, or
// having received a GOAWAY frame.
Closing bool
// StreamsActive is how many streams are active.
StreamsActive int
// StreamsReserved is how many streams have been reserved via
// ClientConn.ReserveNewRequest.
StreamsReserved int
// StreamsPending is how many requests have been sent in excess
// of the peer's advertised MaxConcurrentStreams setting and
// are waiting for other streams to complete.
StreamsPending int
// MaxConcurrentStreams is how many concurrent streams the
// peer advertised as acceptable. Zero means no SETTINGS
// frame has been received yet.
MaxConcurrentStreams uint32
// LastIdle, if non-zero, is when the connection last
// transitioned to idle state.
LastIdle time.Time
}
// State returns a snapshot of cc's state.
func (cc *ClientConn) State() ClientConnState {
cc.wmu.Lock()
maxConcurrent := cc.maxConcurrentStreams
if !cc.seenSettings {
maxConcurrent = 0
}
cc.wmu.Unlock()
cc.mu.Lock()
defer cc.mu.Unlock()
return ClientConnState{
Closed: cc.closed,
Closing: cc.closing || cc.singleUse || cc.doNotReuse || cc.goAway != nil,
StreamsActive: len(cc.streams),
StreamsReserved: cc.streamsReserved,
StreamsPending: cc.pendingRequests,