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transport.go
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transport.go
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// Copyright 2011 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.
// HTTP client implementation. See RFC 2616.
//
// This is the low-level Transport implementation of RoundTripper.
// The high-level interface is in client.go.
package remote
import (
"bufio"
"crypto/tls"
"errors"
"fmt"
"io"
"log"
"net"
"net/http"
"net/url"
"os"
"strings"
"sync"
"time"
)
// DefaultMaxIdleConnsPerHost is the default value of Transport's
// MaxIdleConnsPerHost.
const DefaultMaxIdleConnsPerHost = 2
// Transport is an implementation of RoundTripper that supports HTTP,
// HTTPS, and HTTP proxies (for either HTTP or HTTPS with CONNECT).
// Transport can also cache connections for future re-use.
type Transport struct {
idleMu sync.Mutex
wantIdle bool // user has requested to close all idle conns
idleConn map[connectMethodKey][]*persistConn
idleConnCh map[connectMethodKey]chan *persistConn
reqMu sync.Mutex
reqCanceler map[*http.Request]func()
reqCanceled map[*http.Request]bool
altMu sync.RWMutex
altProto map[string]http.RoundTripper // nil or map of URI scheme => RoundTripper
// Dial specifies the dial function for creating unencrypted
// TCP connections.
// If Dial is nil, net.Dial is used.
Dial func(network, addr string) (net.Conn, error)
// DialTLS specifies an optional dial function for creating
// TLS connections for non-proxied HTTPS requests.
//
// If DialTLS is nil, Dial and TLSClientConfig are used.
//
// If DialTLS is set, the Dial hook is not used for HTTPS
// requests and the TLSClientConfig and TLSHandshakeTimeout
// are ignored. The returned net.Conn is assumed to already be
// past the TLS handshake.
DialTLS func(network, addr string) (net.Conn, error)
// TLSClientConfig specifies the TLS configuration to use with
// tls.Client. If nil, the default configuration is used.
TLSClientConfig *tls.Config
// TLSHandshakeTimeout specifies the maximum amount of time waiting to
// wait for a TLS handshake. Zero means no timeout.
TLSHandshakeTimeout time.Duration
// DisableKeepAlives, if true, prevents re-use of TCP connections
// between different HTTP requests.
DisableKeepAlives bool
// 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
// MaxIdleConnsPerHost, if non-zero, controls the maximum idle
// (keep-alive) to keep per-host. If zero,
// DefaultMaxIdleConnsPerHost is used.
MaxIdleConnsPerHost int
// ResponseHeaderTimeout, if non-zero, specifies the amount of
// time to wait for a server's response headers after fully
// writing the request (including its body, if any). This
// time does not include the time to read the response body.
ResponseHeaderTimeout time.Duration
// TODO: tunable on global max cached connections
// TODO: tunable on timeout on cached connections
}
// transportRequest is a wrapper around a *Request that adds
// optional extra headers to write.
type transportRequest struct {
*http.Request // original request, not to be mutated
extra http.Header // extra headers to write, or nil
}
func (tr *transportRequest) extraHeaders() http.Header {
if tr.extra == nil {
tr.extra = make(http.Header)
}
return tr.extra
}
func closeBody(req *http.Request) {
if req.Body != nil {
req.Body.Close()
}
}
func hasPort(s string) bool { return strings.LastIndex(s, ":") > strings.LastIndex(s, "]") }
// RoundTrip implements the RoundTripper interface.
//
// For higher-level HTTP client support (such as handling of cookies
// and redirects), see Get, Post, and the Client type.
func (t *Transport) RoundTrip(req *http.Request) (resp *http.Response, err error) {
if req.URL == nil {
closeBody(req)
return nil, errors.New("http: nil Request.URL")
}
if req.Header == nil {
closeBody(req)
return nil, errors.New("http: nil Request.Header")
}
if req.URL.Scheme != "http" && req.URL.Scheme != "https" {
closeBody(req)
return nil, errors.New("http: bad scheme")
}
if req.URL.Host == "" {
closeBody(req)
return nil, errors.New("http: no Host in request URL")
}
treq := &transportRequest{Request: req}
cm := t.connectMethodForRequest(treq)
// Get the cached or newly-created connection to either the
// host (for http or https), the http proxy, or the http proxy
// pre-CONNECTed to https server. In any case, we'll be ready
// to send it requests.
pconn, err := t.getConn(req, cm)
if err != nil {
t.setReqCanceler(req, nil)
closeBody(req)
return nil, err
}
return pconn.roundTrip(treq)
}
// RegisterProtocol registers a new protocol with scheme.
// The Transport will pass requests using the given scheme to rt.
// It is rt's responsibility to simulate HTTP request semantics.
//
// RegisterProtocol can be used by other packages to provide
// implementations of protocol schemes like "ftp" or "file".
func (t *Transport) RegisterProtocol(scheme string, rt http.RoundTripper) {
if scheme == "http" || scheme == "https" {
panic("protocol " + scheme + " already registered")
}
t.altMu.Lock()
defer t.altMu.Unlock()
if t.altProto == nil {
t.altProto = make(map[string]http.RoundTripper)
}
if _, exists := t.altProto[scheme]; exists {
panic("protocol " + scheme + " already registered")
}
t.altProto[scheme] = rt
}
// CloseIdleConnections closes any connections which were previously
// connected from previous requests but are now sitting idle in
// a "keep-alive" state. It does not interrupt any connections currently
// in use.
func (t *Transport) CloseIdleConnections() {
t.idleMu.Lock()
m := t.idleConn
t.idleConn = nil
t.idleConnCh = nil
t.wantIdle = true
t.idleMu.Unlock()
for _, conns := range m {
for _, pconn := range conns {
pconn.close()
}
}
}
// CancelRequest cancels an in-flight request by closing its connection.
// CancelRequest should only be called after RoundTrip has returned.
func (t *Transport) CancelRequest(req *http.Request) {
t.reqMu.Lock()
if cancel, ok := t.reqCanceler[req]; ok {
delete(t.reqCanceler, req)
t.reqMu.Unlock()
if cancel != nil {
cancel()
}
} else {
if t.reqCanceled == nil {
t.reqCanceled = make(map[*http.Request]bool)
}
t.reqCanceled[req] = true
t.reqMu.Unlock()
}
}
//
// Private implementation past this point.
//
// envOnce looks up an environment variable (optionally by multiple
// names) once. It mitigates expensive lookups on some platforms
// (e.g. Windows).
type envOnce struct {
names []string
once sync.Once
val string
}
func (e *envOnce) Get() string {
e.once.Do(e.init)
return e.val
}
func (e *envOnce) init() {
for _, n := range e.names {
e.val = os.Getenv(n)
if e.val != "" {
return
}
}
}
// reset is used by tests
func (e *envOnce) reset() {
e.once = sync.Once{}
e.val = ""
}
func (t *Transport) connectMethodForRequest(treq *transportRequest) (cm connectMethod) {
cm.targetScheme = treq.URL.Scheme
cm.targetAddr = canonicalAddr(treq.URL)
return cm
}
// putIdleConn adds pconn to the list of idle persistent connections awaiting
// a new request.
// If pconn is no longer needed or not in a good state, putIdleConn
// returns false.
func (t *Transport) putIdleConn(pconn *persistConn) bool {
if t.DisableKeepAlives || t.MaxIdleConnsPerHost < 0 {
pconn.close()
return false
}
if pconn.isBroken() {
return false
}
key := pconn.cacheKey
max := t.MaxIdleConnsPerHost
if max == 0 {
max = DefaultMaxIdleConnsPerHost
}
t.idleMu.Lock()
waitingDialer := t.idleConnCh[key]
select {
case waitingDialer <- pconn:
// We're done with this pconn and somebody else is
// currently waiting for a conn of this type (they're
// actively dialing, but this conn is ready
// first). Chrome calls this socket late binding. See
// https://insouciant.org/tech/connection-management-in-chromium/
t.idleMu.Unlock()
return true
default:
if waitingDialer != nil {
// They had populated this, but their dial won
// first, so we can clean up this map entry.
delete(t.idleConnCh, key)
}
}
if t.wantIdle {
t.idleMu.Unlock()
pconn.close()
return false
}
if t.idleConn == nil {
t.idleConn = make(map[connectMethodKey][]*persistConn)
}
if len(t.idleConn[key]) >= max {
t.idleMu.Unlock()
pconn.close()
return false
}
for _, exist := range t.idleConn[key] {
if exist == pconn {
log.Fatalf("dup idle pconn %p in freelist", pconn)
}
}
t.idleConn[key] = append(t.idleConn[key], pconn)
t.idleMu.Unlock()
return true
}
// getIdleConnCh returns a channel to receive and return idle
// persistent connection for the given connectMethod.
// It may return nil, if persistent connections are not being used.
func (t *Transport) getIdleConnCh(cm connectMethod) chan *persistConn {
if t.DisableKeepAlives {
return nil
}
key := cm.key()
t.idleMu.Lock()
defer t.idleMu.Unlock()
t.wantIdle = false
if t.idleConnCh == nil {
t.idleConnCh = make(map[connectMethodKey]chan *persistConn)
}
ch, ok := t.idleConnCh[key]
if !ok {
ch = make(chan *persistConn)
t.idleConnCh[key] = ch
}
return ch
}
func (t *Transport) getIdleConn(cm connectMethod) (pconn *persistConn) {
key := cm.key()
t.idleMu.Lock()
defer t.idleMu.Unlock()
if t.idleConn == nil {
return nil
}
for {
pconns, ok := t.idleConn[key]
if !ok {
return nil
}
if len(pconns) == 1 {
pconn = pconns[0]
delete(t.idleConn, key)
} else {
// 2 or more cached connections; pop last
// TODO: queue?
pconn = pconns[len(pconns)-1]
t.idleConn[key] = pconns[:len(pconns)-1]
}
if !pconn.isBroken() {
return
}
}
}
func (t *Transport) setReqCanceler(r *http.Request, fn func()) {
t.reqMu.Lock()
defer t.reqMu.Unlock()
if t.reqCanceler == nil {
t.reqCanceler = make(map[*http.Request]func())
}
if fn != nil {
t.reqCanceler[r] = fn
} else {
delete(t.reqCanceler, r)
}
}
// replaceReqCanceler replaces an existing cancel function. If there is no cancel function
// for the request, we don't set the function and return false.
// Since CancelRequest will clear the canceler, we can use the return value to detect if
// the request was canceled since the last setReqCancel call.
func (t *Transport) replaceReqCanceler(r *http.Request, fn func()) bool {
t.reqMu.Lock()
defer t.reqMu.Unlock()
_, ok := t.reqCanceler[r]
if !ok {
return false
}
if fn != nil {
t.reqCanceler[r] = fn
} else {
delete(t.reqCanceler, r)
}
return true
}
func (t *Transport) dial(network, addr string) (c net.Conn, err error) {
if t.Dial != nil {
return t.Dial(network, addr)
}
return net.Dial(network, addr)
}
// Testing hooks:
var prePendingDial, postPendingDial func()
// getConn dials and creates a new persistConn to the target as
// specified in the connectMethod. This includes doing a proxy CONNECT
// and/or setting up TLS. If this doesn't return an error, the persistConn
// is ready to write requests to.
func (t *Transport) getConn(req *http.Request, cm connectMethod) (*persistConn, error) {
if pc := t.getIdleConn(cm); pc != nil {
// set request canceler to some non-nil function so we
// can detect whether it was cleared between now and when
// we enter roundTrip
t.setReqCanceler(req, func() {})
t.reqMu.Lock()
if _, ok := t.reqCanceled[req]; ok {
// request canceled before we knew about it
delete(t.reqCanceled, req)
pc.cancelRequest()
}
t.reqMu.Unlock()
return pc, nil
}
type dialRes struct {
pc *persistConn
err error
}
dialc := make(chan dialRes)
// Copy these hooks so we don't race on the postPendingDial in
// the goroutine we launch. Issue 11136.
prePendingDial := prePendingDial
postPendingDial := postPendingDial
handlePendingDial := func() {
if prePendingDial != nil {
prePendingDial()
}
go func() {
if v := <-dialc; v.err == nil {
t.putIdleConn(v.pc)
}
if postPendingDial != nil {
postPendingDial()
}
}()
}
cancelc := make(chan struct{})
t.setReqCanceler(req, func() { close(cancelc) })
t.reqMu.Lock()
if _, ok := t.reqCanceled[req]; ok {
// request canceled before we knew about it
if cancel, ok := t.reqCanceler[req]; ok {
delete(t.reqCanceler, req)
delete(t.reqCanceled, req)
if cancel != nil {
cancel()
}
}
}
t.reqMu.Unlock()
go func() {
pc, err := t.dialConn(cm)
dialc <- dialRes{pc, err}
}()
idleConnCh := t.getIdleConnCh(cm)
select {
case v := <-dialc:
// Our dial finished.
return v.pc, v.err
case pc := <-idleConnCh:
// Another request finished first and its net.Conn
// became available before our dial. Or somebody
// else's dial that they didn't use.
// But our dial is still going, so give it away
// when it finishes:
handlePendingDial()
return pc, nil
case <-cancelc:
handlePendingDial()
return nil, errors.New("net/http: request canceled while waiting for connection")
}
}
func (t *Transport) dialConn(cm connectMethod) (*persistConn, error) {
pconn := &persistConn{
t: t,
cacheKey: cm.key(),
reqch: make(chan requestAndChan, 1),
writech: make(chan writeRequest, 1),
closech: make(chan struct{}),
writeErrCh: make(chan error, 1),
}
tlsDial := t.DialTLS != nil && cm.targetScheme == "https"
if tlsDial {
var err error
pconn.conn, err = t.DialTLS("tcp", cm.addr())
if err != nil {
return nil, err
}
if tc, ok := pconn.conn.(*tls.Conn); ok {
cs := tc.ConnectionState()
pconn.tlsState = &cs
}
} else {
conn, err := t.dial("tcp", cm.addr())
if err != nil {
return nil, err
}
pconn.conn = conn
}
if cm.targetScheme == "https" && !tlsDial {
// Initiate TLS and check remote host name against certificate.
cfg := t.TLSClientConfig
if cfg == nil || cfg.ServerName == "" {
host := cm.tlsHost()
if cfg == nil {
cfg = &tls.Config{ServerName: host}
} else {
clone := *cfg // shallow clone
clone.ServerName = host
cfg = &clone
}
}
plainConn := pconn.conn
tlsConn := tls.Client(plainConn, cfg)
errc := make(chan error, 2)
var timer *time.Timer // for canceling TLS handshake
if d := t.TLSHandshakeTimeout; d != 0 {
timer = time.AfterFunc(d, func() {
errc <- tlsHandshakeTimeoutError{}
})
}
go func() {
err := tlsConn.Handshake()
if timer != nil {
timer.Stop()
}
errc <- err
}()
if err := <-errc; err != nil {
plainConn.Close()
return nil, err
}
if !cfg.InsecureSkipVerify {
if err := tlsConn.VerifyHostname(cfg.ServerName); err != nil {
plainConn.Close()
return nil, err
}
}
cs := tlsConn.ConnectionState()
pconn.tlsState = &cs
pconn.conn = tlsConn
}
pconn.br = bufio.NewReader(noteEOFReader{pconn.conn, &pconn.sawEOF})
pconn.bw = bufio.NewWriter(pconn.conn)
go pconn.readLoop()
go pconn.writeLoop()
return pconn, nil
}
// connectMethod is the map key (in its String form) for keeping persistent
// TCP connections alive for subsequent HTTP requests.
//
// A connect method may be of the following types:
//
// Cache key form Description
// ----------------- -------------------------
// |http|foo.com http directly to server, no proxy
// |https|foo.com https directly to server, no proxy
// http://proxy.com|https|foo.com http to proxy, then CONNECT to foo.com
// http://proxy.com|http http to proxy, http to anywhere after that
//
// Note: no support to https to the proxy yet.
//
type connectMethod struct {
targetScheme string // "http" or "https"
targetAddr string // Not used if proxy + http targetScheme (4th example in table)
}
func (cm *connectMethod) key() connectMethodKey {
return connectMethodKey{
scheme: cm.targetScheme,
addr: cm.targetAddr,
}
}
// addr returns the first hop "host:port" to which we need to TCP connect.
func (cm *connectMethod) addr() string {
return cm.targetAddr
}
// tlsHost returns the host name to match against the peer's
// TLS certificate.
func (cm *connectMethod) tlsHost() string {
h := cm.targetAddr
if hasPort(h) {
h = h[:strings.LastIndex(h, ":")]
}
return h
}
// connectMethodKey is the map key version of connectMethod, with a
// stringified proxy URL (or the empty string) instead of a pointer to
// a URL.
type connectMethodKey struct {
scheme, addr string
}
func (k connectMethodKey) String() string {
// Only used by tests.
return fmt.Sprintf("%s|%s|%s", k.scheme, k.addr)
}
// persistConn wraps a connection, usually a persistent one
// (but may be used for non-keep-alive requests as well)
type persistConn struct {
t *Transport
cacheKey connectMethodKey
conn net.Conn
tlsState *tls.ConnectionState
br *bufio.Reader // from conn
sawEOF bool // whether we've seen EOF from conn; owned by readLoop
bw *bufio.Writer // to conn
reqch chan requestAndChan // written by roundTrip; read by readLoop
writech chan writeRequest // written by roundTrip; read by writeLoop
closech chan struct{} // closed when conn closed
// writeErrCh passes the request write error (usually nil)
// from the writeLoop goroutine to the readLoop which passes
// it off to the res.Body reader, which then uses it to decide
// whether or not a connection can be reused. Issue 7569.
writeErrCh chan error
lk sync.Mutex // guards following fields
numExpectedResponses int
closed bool // whether conn has been closed
broken bool // an error has happened on this connection; marked broken so it's not reused.
canceled bool // whether this conn was broken due a CancelRequest
// mutateHeaderFunc is an optional func to modify extra
// headers on each outbound request before it's written. (the
// original Request given to RoundTrip is not modified)
mutateHeaderFunc func(http.Header)
}
// isBroken reports whether this connection is in a known broken state.
func (pc *persistConn) isBroken() bool {
pc.lk.Lock()
b := pc.broken
pc.lk.Unlock()
return b
}
// isCanceled reports whether this connection was closed due to CancelRequest.
func (pc *persistConn) isCanceled() bool {
pc.lk.Lock()
defer pc.lk.Unlock()
return pc.canceled
}
func (pc *persistConn) cancelRequest() {
pc.lk.Lock()
defer pc.lk.Unlock()
pc.canceled = true
pc.closeLocked()
}
func (pc *persistConn) readLoop() {
// eofc is used to block http.Handler goroutines reading from Response.Body
// at EOF until this goroutines has (potentially) added the connection
// back to the idle pool.
eofc := make(chan struct{})
defer close(eofc) // unblock reader on errors
// Read this once, before loop starts. (to avoid races in tests)
testHookMu.Lock()
testHookReadLoopBeforeNextRead := testHookReadLoopBeforeNextRead
testHookMu.Unlock()
alive := true
for alive {
pb, err := pc.br.Peek(1)
pc.lk.Lock()
if pc.numExpectedResponses == 0 {
if !pc.closed {
pc.closeLocked()
if len(pb) > 0 {
log.Printf("Unsolicited response received on idle HTTP channel starting with %q; err=%v",
string(pb), err)
}
}
pc.lk.Unlock()
return
}
pc.lk.Unlock()
rc := <-pc.reqch
var resp *http.Response
if err == nil {
resp, err = http.ReadResponse(pc.br, rc.req)
if err == nil && resp.StatusCode == 100 {
// Skip any 100-continue for now.
// TODO(bradfitz): if rc.req had "Expect: 100-continue",
// actually block the request body write and signal the
// writeLoop now to begin sending it. (Issue 2184) For now we
// eat it, since we're never expecting one.
resp, err = http.ReadResponse(pc.br, rc.req)
}
}
if resp != nil {
resp.TLS = pc.tlsState
}
hasBody := resp != nil && rc.req.Method != "HEAD" && resp.ContentLength != 0
if err != nil {
pc.close()
} else {
resp.Body = &bodyEOFSignal{body: resp.Body}
}
if err != nil || resp.Close || rc.req.Close || resp.StatusCode <= 199 {
// Don't do keep-alive on error if either party requested a close
// or we get an unexpected informational (1xx) response.
// StatusCode 100 is already handled above.
alive = false
}
var waitForBodyRead chan bool // channel is nil when there's no body
if hasBody {
waitForBodyRead = make(chan bool, 2)
resp.Body.(*bodyEOFSignal).earlyCloseFn = func() error {
waitForBodyRead <- false
return nil
}
resp.Body.(*bodyEOFSignal).fn = func(err error) error {
isEOF := err == io.EOF
waitForBodyRead <- isEOF
if isEOF {
<-eofc // see comment at top
} else if err != nil && pc.isCanceled() {
return errRequestCanceled
}
return err
}
}
pc.lk.Lock()
pc.numExpectedResponses--
pc.lk.Unlock()
// The connection might be going away when we put the
// idleConn below. When that happens, we close the response channel to signal
// to roundTrip that the connection is gone. roundTrip waits for
// both closing and a response in a select, so it might choose
// the close channel, rather than the response.
// We send the response first so that roundTrip can check
// if there is a pending one with a non-blocking select
// on the response channel before erroring out.
rc.ch <- responseAndError{resp, err}
if hasBody {
// To avoid a race, wait for the just-returned
// response body to be fully consumed before peek on
// the underlying bufio reader.
select {
case bodyEOF := <-waitForBodyRead:
pc.t.setReqCanceler(rc.req, nil) // before pc might return to idle pool
alive = alive &&
bodyEOF &&
!pc.sawEOF &&
pc.wroteRequest() &&
pc.t.putIdleConn(pc)
if bodyEOF {
eofc <- struct{}{}
}
case <-pc.closech:
alive = false
}
} else {
pc.t.setReqCanceler(rc.req, nil) // before pc might return to idle pool
alive = alive &&
!pc.sawEOF &&
pc.wroteRequest() &&
pc.t.putIdleConn(pc)
}
if hook := testHookReadLoopBeforeNextRead; hook != nil {
hook()
}
}
pc.close()
}
func (pc *persistConn) writeLoop() {
for {
select {
case wr := <-pc.writech:
if pc.isBroken() {
wr.ch <- errors.New("http: can't write HTTP request on broken connection")
continue
}
err := wr.req.Request.Write(pc.bw)
if err == nil {
err = pc.bw.Flush()
}
if err != nil {
pc.markBroken()
closeBody(wr.req.Request)
}
pc.writeErrCh <- err // to the body reader, which might recycle us
wr.ch <- err // to the roundTrip function
case <-pc.closech:
return
}
}
}
// wroteRequest is a check before recycling a connection that the previous write
// (from writeLoop above) happened and was successful.
func (pc *persistConn) wroteRequest() bool {
select {
case err := <-pc.writeErrCh:
// Common case: the write happened well before the response, so
// avoid creating a timer.
return err == nil
default:
// Rare case: the request was written in writeLoop above but
// before it could send to pc.writeErrCh, the reader read it
// all, processed it, and called us here. In this case, give the
// write goroutine a bit of time to finish its send.
//
// Less rare case: We also get here in the legitimate case of
// Issue 7569, where the writer is still writing (or stalled),
// but the server has already replied. In this case, we don't
// want to wait too long, and we want to return false so this
// connection isn't re-used.
select {
case err := <-pc.writeErrCh:
return err == nil
case <-time.After(50 * time.Millisecond):
return false
}
}
}
type responseAndError struct {
res *http.Response
err error
}
type requestAndChan struct {
req *http.Request
ch chan responseAndError
}
// A writeRequest is sent by the readLoop's goroutine to the
// writeLoop's goroutine to write a request while the read loop
// concurrently waits on both the write response and the server's
// reply.
type writeRequest struct {
req *transportRequest
ch chan<- error
}
type trHttpError struct {
err string
timeout bool
}
func (e *trHttpError) Error() string { return e.err }
func (e *trHttpError) Timeout() bool { return e.timeout }
func (e *trHttpError) Temporary() bool { return true }
var errTimeout error = &trHttpError{err: "net/http: timeout awaiting response headers", timeout: true}
var errClosed error = &trHttpError{err: "net/http: transport closed before response was received"}
var errRequestCanceled = errors.New("net/http: request canceled")
// nil except for tests
var (
testHookPersistConnClosedGotRes func()
testHookEnterRoundTrip func()
testHookMu sync.Locker = fakeLocker{} // guards following
testHookReadLoopBeforeNextRead func()
)
func (pc *persistConn) roundTrip(req *transportRequest) (resp *http.Response, err error) {
if hook := testHookEnterRoundTrip; hook != nil {
hook()
}
if !pc.t.replaceReqCanceler(req.Request, pc.cancelRequest) {
pc.t.putIdleConn(pc)
return nil, errRequestCanceled
}
pc.lk.Lock()
pc.numExpectedResponses++
headerFn := pc.mutateHeaderFunc
pc.lk.Unlock()
if headerFn != nil {
headerFn(req.extraHeaders())
}
// Write the request concurrently with waiting for a response,
// in case the server decides to reply before reading our full
// request body.
writeErrCh := make(chan error, 1)
pc.writech <- writeRequest{req, writeErrCh}
resc := make(chan responseAndError, 1)
pc.reqch <- requestAndChan{req.Request, resc}
var re responseAndError
var respHeaderTimer <-chan time.Time
WaitResponse:
for {
select {
case err := <-writeErrCh:
if err != nil {
re = responseAndError{nil, err}
pc.close()
break WaitResponse
}
if d := pc.t.ResponseHeaderTimeout; d > 0 {
timer := time.NewTimer(d)
defer timer.Stop() // prevent leaks
respHeaderTimer = timer.C
}
case <-pc.closech:
// The persist connection is dead. This shouldn't
// usually happen (only with Connection: close responses
// with no response bodies), but if it does happen it
// means either a) the remote server hung up on us
// prematurely, or b) the readLoop sent us a response &
// closed its closech at roughly the same time, and we
// selected this case first. If we got a response, readLoop makes sure
// to send it before it puts the conn and closes the channel.
// That way, we can fetch the response, if there is one,
// with a non-blocking receive.
select {
case re = <-resc:
if fn := testHookPersistConnClosedGotRes; fn != nil {
fn()
}
default:
re = responseAndError{err: errClosed}
}
break WaitResponse
case <-respHeaderTimer:
pc.close()
re = responseAndError{err: errTimeout}
break WaitResponse
case re = <-resc:
break WaitResponse
}
}
if re.err != nil {
pc.t.setReqCanceler(req.Request, nil)
}
return re.res, re.err
}
// markBroken marks a connection as broken (so it's not reused).
// It differs from close in that it doesn't close the underlying
// connection for use when it's still being read.
func (pc *persistConn) markBroken() {
pc.lk.Lock()
defer pc.lk.Unlock()
pc.broken = true
}
func (pc *persistConn) close() {
pc.lk.Lock()
defer pc.lk.Unlock()
pc.closeLocked()
}
func (pc *persistConn) closeLocked() {
pc.broken = true
if !pc.closed {
pc.conn.Close()
pc.closed = true
close(pc.closech)
}
pc.mutateHeaderFunc = nil