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@imfht imfht/transport.go
Created Nov 1, 2018

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modified transport. can visit a domain IPv4 only or IPv6 only.
// 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 7230 through 7235.
//
// This is the low-level Transport implementation of RoundTripper.
// The high-level interface is in client.go.
package http
import (
"bufio"
"compress/gzip"
"container/list"
"context"
"crypto/tls"
"errors"
"fmt"
"io"
"log"
"net"
"net/http/httptrace"
"net/textproto"
"net/url"
"os"
"reflect"
"strings"
"sync"
"sync/atomic"
"time"
"golang_org/x/net/http/httpguts"
"golang_org/x/net/http/httpproxy"
)
// DefaultTransport is the default implementation of Transport and is
// used by DefaultClient. It establishes network connections as needed
// and caches them for reuse by subsequent calls. It uses HTTP proxies
// as directed by the $HTTP_PROXY and $NO_PROXY (or $http_proxy and
// $no_proxy) environment variables.
var DefaultTransport RoundTripper = &Transport{
Proxy: ProxyFromEnvironment,
DialContext: (&net.Dialer{
Timeout: 30 * time.Second,
KeepAlive: 30 * time.Second,
DualStack: true,
}).DialContext,
MaxIdleConns: 100,
IdleConnTimeout: 90 * time.Second,
TLSHandshakeTimeout: 10 * time.Second,
ExpectContinueTimeout: 1 * time.Second,
IPv6Only: false,
}
// DefaultMaxIdleConnsPerHost is the default value of Transport's
// MaxIdleConnsPerHost.
const DefaultMaxIdleConnsPerHost = 2
// connsPerHostClosedCh is a closed channel used by MaxConnsPerHost
// for the property that receives from a closed channel return the
// zero value.
var connsPerHostClosedCh = make(chan struct{})
func init() {
close(connsPerHostClosedCh)
}
// Transport is an implementation of RoundTripper that supports HTTP,
// HTTPS, and HTTP proxies (for either HTTP or HTTPS with CONNECT).
//
// By default, Transport caches connections for future re-use.
// This may leave many open connections when accessing many hosts.
// This behavior can be managed using Transport's CloseIdleConnections method
// and the MaxIdleConnsPerHost and DisableKeepAlives fields.
//
// Transports should be reused instead of created as needed.
// Transports are safe for concurrent use by multiple goroutines.
//
// A Transport is a low-level primitive for making HTTP and HTTPS requests.
// For high-level functionality, such as cookies and redirects, see Client.
//
// Transport uses HTTP/1.1 for HTTP URLs and either HTTP/1.1 or HTTP/2
// for HTTPS URLs, depending on whether the server supports HTTP/2,
// and how the Transport is configured. The DefaultTransport supports HTTP/2.
// To explicitly enable HTTP/2 on a transport, use golang.org/x/net/http2
// and call ConfigureTransport. See the package docs for more about HTTP/2.
//
// The Transport will send CONNECT requests to a proxy for its own use
// when processing HTTPS requests, but Transport should generally not
// be used to send a CONNECT request. That is, the Request passed to
// the RoundTrip method should not have a Method of "CONNECT", as Go's
// HTTP/1.x implementation does not support full-duplex request bodies
// being written while the response body is streamed. Go's HTTP/2
// implementation does support full duplex, but many CONNECT proxies speak
// HTTP/1.x.
//
// Responses with status codes in the 1xx range are either handled
// automatically (100 expect-continue) or ignored. The one
// exception is HTTP status code 101 (Switching Protocols), which is
// considered a terminal status and returned by RoundTrip. To see the
// ignored 1xx responses, use the httptrace trace package's
// ClientTrace.Got1xxResponse.
type Transport struct {
idleMu sync.Mutex
wantIdle bool // user has requested to close all idle conns
idleConn map[connectMethodKey][]*persistConn // most recently used at end
idleConnCh map[connectMethodKey]chan *persistConn
idleLRU connLRU
reqMu sync.Mutex
reqCanceler map[*Request]func(error)
altMu sync.Mutex // guards changing altProto only
altProto atomic.Value // of nil or map[string]RoundTripper, key is URI scheme
connCountMu sync.Mutex
connPerHostCount map[connectMethodKey]int
connPerHostAvailable map[connectMethodKey]chan struct{}
// Proxy specifies a function to return a proxy for a given
// Request. If the function returns a non-nil error, the
// request is aborted with the provided error.
//
// The proxy type is determined by the URL scheme. "http",
// "https", and "socks5" are supported. If the scheme is empty,
// "http" is assumed.
//
// If Proxy is nil or returns a nil *URL, no proxy is used.
Proxy func(*Request) (*url.URL, error)
// DialContext specifies the dial function for creating unencrypted TCP connections.
// If DialContext is nil (and the deprecated Dial below is also nil),
// then the transport dials using package net.
//
// DialContext runs concurrently with calls to RoundTrip.
// A RoundTrip call that initiates a dial may end up using
// an connection dialed previously when the earlier connection
// becomes idle before the later DialContext completes.
DialContext func(ctx context.Context, network, addr string) (net.Conn, error)
// Dial specifies the dial function for creating unencrypted TCP connections.
//
// Dial runs concurrently with calls to RoundTrip.
// A RoundTrip call that initiates a dial may end up using
// an connection dialed previously when the earlier connection
// becomes idle before the later Dial completes.
//
// Deprecated: Use DialContext instead, which allows the transport
// to cancel dials as soon as they are no longer needed.
// If both are set, DialContext takes priority.
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.
// If non-nil, HTTP/2 support may not be enabled by default.
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, disables HTTP keep-alives and
// will only use the connection to the server for a single
// HTTP request.
//
// This is unrelated to the similarly named TCP keep-alives.
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
// MaxIdleConns controls the maximum number of idle (keep-alive)
// connections across all hosts. Zero means no limit.
MaxIdleConns int
// MaxIdleConnsPerHost, if non-zero, controls the maximum idle
// (keep-alive) connections to keep per-host. If zero,
// DefaultMaxIdleConnsPerHost is used.
MaxIdleConnsPerHost int
// MaxConnsPerHost optionally limits the total number of
// connections per host, including connections in the dialing,
// active, and idle states. On limit violation, dials will block.
//
// Zero means no limit.
//
// For HTTP/2, this currently only controls the number of new
// connections being created at a time, instead of the total
// number. In practice, hosts using HTTP/2 only have about one
// idle connection, though.
MaxConnsPerHost int
// 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
// 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
// ExpectContinueTimeout, if non-zero, specifies the amount of
// time to wait for a server's first response headers after fully
// writing the request headers if the request has an
// "Expect: 100-continue" header. Zero means no timeout and
// causes the body to be sent immediately, without
// waiting for the server to approve.
// This time does not include the time to send the request header.
ExpectContinueTimeout time.Duration
// TLSNextProto specifies how the Transport switches to an
// alternate protocol (such as HTTP/2) after a TLS NPN/ALPN
// protocol negotiation. If Transport dials an TLS connection
// with a non-empty protocol name and TLSNextProto contains a
// map entry for that key (such as "h2"), then the func is
// called with the request's authority (such as "example.com"
// or "example.com:1234") and the TLS connection. The function
// must return a RoundTripper that then handles the request.
// If TLSNextProto is not nil, HTTP/2 support is not enabled
// automatically.
TLSNextProto map[string]func(authority string, c *tls.Conn) RoundTripper
// ProxyConnectHeader optionally specifies headers to send to
// proxies during CONNECT requests.
ProxyConnectHeader Header
// MaxResponseHeaderBytes specifies a limit on how many
// response bytes are allowed in the server's response
// header.
//
// Zero means to use a default limit.
MaxResponseHeaderBytes int64
// nextProtoOnce guards initialization of TLSNextProto and
// h2transport (via onceSetNextProtoDefaults)
nextProtoOnce sync.Once
h2transport h2Transport // non-nil if http2 wired up
IPv6Only bool // IPv6 only
IPv4Only bool // IPv4 only
}
// h2Transport is the interface we expect to be able to call from
// net/http against an *http2.Transport that's either bundled into
// h2_bundle.go or supplied by the user via x/net/http2.
//
// We name it with the "h2" prefix to stay out of the "http2" prefix
// namespace used by x/tools/cmd/bundle for h2_bundle.go.
type h2Transport interface {
CloseIdleConnections()
}
// onceSetNextProtoDefaults initializes TLSNextProto.
// It must be called via t.nextProtoOnce.Do.
func (t *Transport) onceSetNextProtoDefaults() {
if strings.Contains(os.Getenv("GODEBUG"), "http2client=0") {
return
}
// If they've already configured http2 with
// golang.org/x/net/http2 instead of the bundled copy, try to
// get at its http2.Transport value (via the the "https"
// altproto map) so we can call CloseIdleConnections on it if
// requested. (Issue 22891)
altProto, _ := t.altProto.Load().(map[string]RoundTripper)
if rv := reflect.ValueOf(altProto["https"]); rv.IsValid() && rv.Type().Kind() == reflect.Struct && rv.Type().NumField() == 1 {
if v := rv.Field(0); v.CanInterface() {
if h2i, ok := v.Interface().(h2Transport); ok {
t.h2transport = h2i
}
}
}
if t.TLSNextProto != nil {
// This is the documented way to disable http2 on a
// Transport.
return
}
if t.TLSClientConfig != nil || t.Dial != nil || t.DialTLS != nil {
// Be conservative and don't automatically enable
// http2 if they've specified a custom TLS config or
// custom dialers. Let them opt-in themselves via
// http2.ConfigureTransport so we don't surprise them
// by modifying their tls.Config. Issue 14275.
return
}
t2, err := http2configureTransport(t)
if err != nil {
log.Printf("Error enabling Transport HTTP/2 support: %v", err)
return
}
t.h2transport = t2
// Auto-configure the http2.Transport's MaxHeaderListSize from
// the http.Transport's MaxResponseHeaderBytes. They don't
// exactly mean the same thing, but they're close.
//
// TODO: also add this to x/net/http2.Configure Transport, behind
// a +build go1.7 build tag:
if limit1 := t.MaxResponseHeaderBytes; limit1 != 0 && t2.MaxHeaderListSize == 0 {
const h2max = 1<<32 - 1
if limit1 >= h2max {
t2.MaxHeaderListSize = h2max
} else {
t2.MaxHeaderListSize = uint32(limit1)
}
}
}
// ProxyFromEnvironment returns the URL of the proxy to use for a
// given request, as indicated by the environment variables
// HTTP_PROXY, HTTPS_PROXY and NO_PROXY (or the lowercase versions
// thereof). HTTPS_PROXY takes precedence over HTTP_PROXY for https
// requests.
//
// The environment values may be either a complete URL or a
// "host[:port]", in which case the "http" scheme is assumed.
// An error is returned if the value is a different form.
//
// A nil URL and nil error are returned if no proxy is defined in the
// environment, or a proxy should not be used for the given request,
// as defined by NO_PROXY.
//
// As a special case, if req.URL.Host is "localhost" (with or without
// a port number), then a nil URL and nil error will be returned.
func ProxyFromEnvironment(req *Request) (*url.URL, error) {
return envProxyFunc()(req.URL)
}
// ProxyURL returns a proxy function (for use in a Transport)
// that always returns the same URL.
func ProxyURL(fixedURL *url.URL) func(*Request) (*url.URL, error) {
return func(*Request) (*url.URL, error) {
return fixedURL, nil
}
}
// transportRequest is a wrapper around a *Request that adds
// optional extra headers to write and stores any error to return
// from roundTrip.
type transportRequest struct {
*Request // original request, not to be mutated
extra Header // extra headers to write, or nil
trace *httptrace.ClientTrace // optional
mu sync.Mutex // guards err
err error // first setError value for mapRoundTripError to consider
}
func (tr *transportRequest) extraHeaders() Header {
if tr.extra == nil {
tr.extra = make(Header)
}
return tr.extra
}
func (tr *transportRequest) setError(err error) {
tr.mu.Lock()
if tr.err == nil {
tr.err = err
}
tr.mu.Unlock()
}
// roundTrip implements a RoundTripper over HTTP.
func (t *Transport) roundTrip(req *Request) (*Response, error) {
t.nextProtoOnce.Do(t.onceSetNextProtoDefaults)
ctx := req.Context()
trace := httptrace.ContextClientTrace(ctx)
if req.URL == nil {
req.closeBody()
return nil, errors.New("http: nil Request.URL")
}
if req.Header == nil {
req.closeBody()
return nil, errors.New("http: nil Request.Header")
}
scheme := req.URL.Scheme
isHTTP := scheme == "http" || scheme == "https"
if isHTTP {
for k, vv := range req.Header {
if !httpguts.ValidHeaderFieldName(k) {
return nil, fmt.Errorf("net/http: invalid header field name %q", k)
}
for _, v := range vv {
if !httpguts.ValidHeaderFieldValue(v) {
return nil, fmt.Errorf("net/http: invalid header field value %q for key %v", v, k)
}
}
}
}
altProto, _ := t.altProto.Load().(map[string]RoundTripper)
if altRT := altProto[scheme]; altRT != nil {
if resp, err := altRT.RoundTrip(req); err != ErrSkipAltProtocol {
return resp, err
}
}
if !isHTTP {
req.closeBody()
return nil, &badStringError{"unsupported protocol scheme", scheme}
}
if req.Method != "" && !validMethod(req.Method) {
return nil, fmt.Errorf("net/http: invalid method %q", req.Method)
}
if req.URL.Host == "" {
req.closeBody()
return nil, errors.New("http: no Host in request URL")
}
for {
select {
case <-ctx.Done():
req.closeBody()
return nil, ctx.Err()
default:
}
// treq gets modified by roundTrip, so we need to recreate for each retry.
treq := &transportRequest{Request: req, trace: trace}
cm, err := t.connectMethodForRequest(treq)
if err != nil {
req.closeBody()
return nil, err
}
// 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(treq, cm)
if err != nil {
t.setReqCanceler(req, nil)
req.closeBody()
return nil, err
}
var resp *Response
if pconn.alt != nil {
// HTTP/2 path.
t.decHostConnCount(cm.key()) // don't count cached http2 conns toward conns per host
t.setReqCanceler(req, nil) // not cancelable with CancelRequest
resp, err = pconn.alt.RoundTrip(req)
} else {
resp, err = pconn.roundTrip(treq)
}
if err == nil {
return resp, nil
}
if !pconn.shouldRetryRequest(req, err) {
// Issue 16465: return underlying net.Conn.Read error from peek,
// as we've historically done.
if e, ok := err.(transportReadFromServerError); ok {
err = e.err
}
return nil, err
}
testHookRoundTripRetried()
// Rewind the body if we're able to. (HTTP/2 does this itself so we only
// need to do it for HTTP/1.1 connections.)
if req.GetBody != nil && pconn.alt == nil {
newReq := *req
var err error
newReq.Body, err = req.GetBody()
if err != nil {
return nil, err
}
req = &newReq
}
}
}
// shouldRetryRequest reports whether we should retry sending a failed
// HTTP request on a new connection. The non-nil input error is the
// error from roundTrip.
func (pc *persistConn) shouldRetryRequest(req *Request, err error) bool {
if http2isNoCachedConnError(err) {
// Issue 16582: if the user started a bunch of
// requests at once, they can all pick the same conn
// and violate the server's max concurrent streams.
// Instead, match the HTTP/1 behavior for now and dial
// again to get a new TCP connection, rather than failing
// this request.
return true
}
if err == errMissingHost {
// User error.
return false
}
if !pc.isReused() {
// This was a fresh connection. There's no reason the server
// should've hung up on us.
//
// Also, if we retried now, we could loop forever
// creating new connections and retrying if the server
// is just hanging up on us because it doesn't like
// our request (as opposed to sending an error).
return false
}
if _, ok := err.(nothingWrittenError); ok {
// We never wrote anything, so it's safe to retry, if there's no body or we
// can "rewind" the body with GetBody.
return req.outgoingLength() == 0 || req.GetBody != nil
}
if !req.isReplayable() {
// Don't retry non-idempotent requests.
return false
}
if _, ok := err.(transportReadFromServerError); ok {
// We got some non-EOF net.Conn.Read failure reading
// the 1st response byte from the server.
return true
}
if err == errServerClosedIdle {
// The server replied with io.EOF while we were trying to
// read the response. Probably an unfortunately keep-alive
// timeout, just as the client was writing a request.
return true
}
return false // conservatively
}
// ErrSkipAltProtocol is a sentinel error value defined by Transport.RegisterProtocol.
var ErrSkipAltProtocol = errors.New("net/http: skip alternate protocol")
// 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".
//
// If rt.RoundTrip returns ErrSkipAltProtocol, the Transport will
// handle the RoundTrip itself for that one request, as if the
// protocol were not registered.
func (t *Transport) RegisterProtocol(scheme string, rt RoundTripper) {
t.altMu.Lock()
defer t.altMu.Unlock()
oldMap, _ := t.altProto.Load().(map[string]RoundTripper)
if _, exists := oldMap[scheme]; exists {
panic("protocol " + scheme + " already registered")
}
newMap := make(map[string]RoundTripper)
for k, v := range oldMap {
newMap[k] = v
}
newMap[scheme] = rt
t.altProto.Store(newMap)
}
// 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.nextProtoOnce.Do(t.onceSetNextProtoDefaults)
t.idleMu.Lock()
m := t.idleConn
t.idleConn = nil
t.idleConnCh = nil
t.wantIdle = true
t.idleLRU = connLRU{}
t.idleMu.Unlock()
for _, conns := range m {
for _, pconn := range conns {
pconn.close(errCloseIdleConns)
}
}
if t2 := t.h2transport; t2 != nil {
t2.CloseIdleConnections()
}
}
// CancelRequest cancels an in-flight request by closing its connection.
// CancelRequest should only be called after RoundTrip has returned.
//
// Deprecated: Use Request.WithContext to create a request with a
// cancelable context instead. CancelRequest cannot cancel HTTP/2
// requests.
func (t *Transport) CancelRequest(req *Request) {
t.cancelRequest(req, errRequestCanceled)
}
// Cancel an in-flight request, recording the error value.
func (t *Transport) cancelRequest(req *Request, err error) {
t.reqMu.Lock()
cancel := t.reqCanceler[req]
delete(t.reqCanceler, req)
t.reqMu.Unlock()
if cancel != nil {
cancel(err)
}
}
//
// Private implementation past this point.
//
var (
// proxyConfigOnce guards proxyConfig
envProxyOnce sync.Once
envProxyFuncValue func(*url.URL) (*url.URL, error)
)
// defaultProxyConfig returns a ProxyConfig value looked up
// from the environment. This mitigates expensive lookups
// on some platforms (e.g. Windows).
func envProxyFunc() func(*url.URL) (*url.URL, error) {
envProxyOnce.Do(func() {
envProxyFuncValue = httpproxy.FromEnvironment().ProxyFunc()
})
return envProxyFuncValue
}
// resetProxyConfig is used by tests.
func resetProxyConfig() {
envProxyOnce = sync.Once{}
envProxyFuncValue = nil
}
func (t *Transport) connectMethodForRequest(treq *transportRequest) (cm connectMethod, err error) {
if port := treq.URL.Port(); !validPort(port) {
return cm, fmt.Errorf("invalid URL port %q", port)
}
cm.targetScheme = treq.URL.Scheme
cm.targetAddr = canonicalAddr(treq.URL)
if t.Proxy != nil {
cm.proxyURL, err = t.Proxy(treq.Request)
if err == nil && cm.proxyURL != nil {
if port := cm.proxyURL.Port(); !validPort(port) {
return cm, fmt.Errorf("invalid proxy URL port %q", port)
}
}
}
return cm, err
}
// proxyAuth returns the Proxy-Authorization header to set
// on requests, if applicable.
func (cm *connectMethod) proxyAuth() string {
if cm.proxyURL == nil {
return ""
}
if u := cm.proxyURL.User; u != nil {
username := u.Username()
password, _ := u.Password()
return "Basic " + basicAuth(username, password)
}
return ""
}
// error values for debugging and testing, not seen by users.
var (
errKeepAlivesDisabled = errors.New("http: putIdleConn: keep alives disabled")
errConnBroken = errors.New("http: putIdleConn: connection is in bad state")
errWantIdle = errors.New("http: putIdleConn: CloseIdleConnections was called")
errTooManyIdle = errors.New("http: putIdleConn: too many idle connections")
errTooManyIdleHost = errors.New("http: putIdleConn: too many idle connections for host")
errCloseIdleConns = errors.New("http: CloseIdleConnections called")
errReadLoopExiting = errors.New("http: persistConn.readLoop exiting")
errIdleConnTimeout = errors.New("http: idle connection timeout")
errNotCachingH2Conn = errors.New("http: not caching alternate protocol's connections")
// errServerClosedIdle is not seen by users for idempotent requests, but may be
// seen by a user if the server shuts down an idle connection and sends its FIN
// in flight with already-written POST body bytes from the client.
// See https://github.com/golang/go/issues/19943#issuecomment-355607646
errServerClosedIdle = errors.New("http: server closed idle connection")
)
// transportReadFromServerError is used by Transport.readLoop when the
// 1 byte peek read fails and we're actually anticipating a response.
// Usually this is just due to the inherent keep-alive shut down race,
// where the server closed the connection at the same time the client
// wrote. The underlying err field is usually io.EOF or some
// ECONNRESET sort of thing which varies by platform. But it might be
// the user's custom net.Conn.Read error too, so we carry it along for
// them to return from Transport.RoundTrip.
type transportReadFromServerError struct {
err error
}
func (e transportReadFromServerError) Error() string {
return fmt.Sprintf("net/http: Transport failed to read from server: %v", e.err)
}
func (t *Transport) putOrCloseIdleConn(pconn *persistConn) {
if err := t.tryPutIdleConn(pconn); err != nil {
pconn.close(err)
}
}
func (t *Transport) maxIdleConnsPerHost() int {
if v := t.MaxIdleConnsPerHost; v != 0 {
return v
}
return DefaultMaxIdleConnsPerHost
}
// tryPutIdleConn 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, tryPutIdleConn returns
// an error explaining why it wasn't registered.
// tryPutIdleConn does not close pconn. Use putOrCloseIdleConn instead for that.
func (t *Transport) tryPutIdleConn(pconn *persistConn) error {
if t.DisableKeepAlives || t.MaxIdleConnsPerHost < 0 {
return errKeepAlivesDisabled
}
if pconn.isBroken() {
return errConnBroken
}
if pconn.alt != nil {
return errNotCachingH2Conn
}
pconn.markReused()
key := pconn.cacheKey
t.idleMu.Lock()
defer t.idleMu.Unlock()
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/
return nil
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 {
return errWantIdle
}
if t.idleConn == nil {
t.idleConn = make(map[connectMethodKey][]*persistConn)
}
idles := t.idleConn[key]
if len(idles) >= t.maxIdleConnsPerHost() {
return errTooManyIdleHost
}
for _, exist := range idles {
if exist == pconn {
log.Fatalf("dup idle pconn %p in freelist", pconn)
}
}
t.idleConn[key] = append(idles, pconn)
t.idleLRU.add(pconn)
if t.MaxIdleConns != 0 && t.idleLRU.len() > t.MaxIdleConns {
oldest := t.idleLRU.removeOldest()
oldest.close(errTooManyIdle)
t.removeIdleConnLocked(oldest)
}
if t.IdleConnTimeout > 0 {
if pconn.idleTimer != nil {
pconn.idleTimer.Reset(t.IdleConnTimeout)
} else {
pconn.idleTimer = time.AfterFunc(t.IdleConnTimeout, pconn.closeConnIfStillIdle)
}
}
pconn.idleAt = time.Now()
return nil
}
// 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, idleSince time.Time) {
key := cm.key()
t.idleMu.Lock()
defer t.idleMu.Unlock()
for {
pconns, ok := t.idleConn[key]
if !ok {
return nil, time.Time{}
}
if len(pconns) == 1 {
pconn = pconns[0]
delete(t.idleConn, key)
} else {
// 2 or more cached connections; use the most
// recently used one at the end.
pconn = pconns[len(pconns)-1]
t.idleConn[key] = pconns[:len(pconns)-1]
}
t.idleLRU.remove(pconn)
if pconn.isBroken() {
// There is a tiny window where this is
// possible, between the connecting dying and
// the persistConn readLoop calling
// Transport.removeIdleConn. Just skip it and
// carry on.
continue
}
return pconn, pconn.idleAt
}
}
// removeIdleConn marks pconn as dead.
func (t *Transport) removeIdleConn(pconn *persistConn) {
t.idleMu.Lock()
defer t.idleMu.Unlock()
t.removeIdleConnLocked(pconn)
}
// t.idleMu must be held.
func (t *Transport) removeIdleConnLocked(pconn *persistConn) {
if pconn.idleTimer != nil {
pconn.idleTimer.Stop()
}
t.idleLRU.remove(pconn)
key := pconn.cacheKey
pconns := t.idleConn[key]
switch len(pconns) {
case 0:
// Nothing
case 1:
if pconns[0] == pconn {
delete(t.idleConn, key)
}
default:
for i, v := range pconns {
if v != pconn {
continue
}
// Slide down, keeping most recently-used
// conns at the end.
copy(pconns[i:], pconns[i+1:])
t.idleConn[key] = pconns[:len(pconns)-1]
break
}
}
}
func (t *Transport) setReqCanceler(r *Request, fn func(error)) {
t.reqMu.Lock()
defer t.reqMu.Unlock()
if t.reqCanceler == nil {
t.reqCanceler = make(map[*Request]func(error))
}
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 *Request, fn func(error)) 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
}
var zeroDialer net.Dialer
func (t *Transport) dial(ctx context.Context, network, addr string) (net.Conn, error) {
if t.DialContext != nil {
return t.DialContext(ctx, network, addr)
}
if t.Dial != nil {
c, err := t.Dial(network, addr)
if c == nil && err == nil {
err = errors.New("net/http: Transport.Dial hook returned (nil, nil)")
}
return c, err
}
return zeroDialer.DialContext(ctx, network, addr)
}
// 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(treq *transportRequest, cm connectMethod) (*persistConn, error) {
req := treq.Request
trace := treq.trace
ctx := req.Context()
if trace != nil && trace.GetConn != nil {
trace.GetConn(cm.addr())
}
if pc, idleSince := t.getIdleConn(cm); pc != nil {
if trace != nil && trace.GotConn != nil {
trace.GotConn(pc.gotIdleConnTrace(idleSince))
}
// 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(error) {})
return pc, nil
}
type dialRes struct {
pc *persistConn
err error
}
dialc := make(chan dialRes)
cmKey := cm.key()
// Copy these hooks so we don't race on the postPendingDial in
// the goroutine we launch. Issue 11136.
testHookPrePendingDial := testHookPrePendingDial
testHookPostPendingDial := testHookPostPendingDial
handlePendingDial := func() {
testHookPrePendingDial()
go func() {
if v := <-dialc; v.err == nil {
t.putOrCloseIdleConn(v.pc)
} else {
t.decHostConnCount(cmKey)
}
testHookPostPendingDial()
}()
}
cancelc := make(chan error, 1)
t.setReqCanceler(req, func(err error) { cancelc <- err })
if t.MaxConnsPerHost > 0 {
select {
case <-t.incHostConnCount(cmKey):
// count below conn per host limit; proceed
case pc := <-t.getIdleConnCh(cm):
if trace != nil && trace.GotConn != nil {
trace.GotConn(httptrace.GotConnInfo{Conn: pc.conn, Reused: pc.isReused()})
}
return pc, nil
case <-req.Cancel:
return nil, errRequestCanceledConn
case <-req.Context().Done():
return nil, req.Context().Err()
case err := <-cancelc:
if err == errRequestCanceled {
err = errRequestCanceledConn
}
return nil, err
}
}
go func() {
pc, err := t.dialConn(ctx, cm)
dialc <- dialRes{pc, err}
}()
idleConnCh := t.getIdleConnCh(cm)
select {
case v := <-dialc:
// Our dial finished.
if v.pc != nil {
if trace != nil && trace.GotConn != nil && v.pc.alt == nil {
trace.GotConn(httptrace.GotConnInfo{Conn: v.pc.conn})
}
return v.pc, nil
}
// Our dial failed. See why to return a nicer error
// value.
t.decHostConnCount(cmKey)
select {
case <-req.Cancel:
// It was an error due to cancelation, so prioritize that
// error value. (Issue 16049)
return nil, errRequestCanceledConn
case <-req.Context().Done():
return nil, req.Context().Err()
case err := <-cancelc:
if err == errRequestCanceled {
err = errRequestCanceledConn
}
return nil, err
default:
// It wasn't an error due to cancelation, so
// return the original error message:
return nil, 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()
if trace != nil && trace.GotConn != nil {
trace.GotConn(httptrace.GotConnInfo{Conn: pc.conn, Reused: pc.isReused()})
}
return pc, nil
case <-req.Cancel:
handlePendingDial()
return nil, errRequestCanceledConn
case <-req.Context().Done():
handlePendingDial()
return nil, req.Context().Err()
case err := <-cancelc:
handlePendingDial()
if err == errRequestCanceled {
err = errRequestCanceledConn
}
return nil, err
}
}
// incHostConnCount increments the count of connections for a
// given host. It returns an already-closed channel if the count
// is not at its limit; otherwise it returns a channel which is
// notified when the count is below the limit.
func (t *Transport) incHostConnCount(cmKey connectMethodKey) <-chan struct{} {
if t.MaxConnsPerHost <= 0 {
return connsPerHostClosedCh
}
t.connCountMu.Lock()
defer t.connCountMu.Unlock()
if t.connPerHostCount[cmKey] == t.MaxConnsPerHost {
if t.connPerHostAvailable == nil {
t.connPerHostAvailable = make(map[connectMethodKey]chan struct{})
}
ch, ok := t.connPerHostAvailable[cmKey]
if !ok {
ch = make(chan struct{})
t.connPerHostAvailable[cmKey] = ch
}
return ch
}
if t.connPerHostCount == nil {
t.connPerHostCount = make(map[connectMethodKey]int)
}
t.connPerHostCount[cmKey]++
// return a closed channel to avoid race: if decHostConnCount is called
// after incHostConnCount and during the nil check, decHostConnCount
// will delete the channel since it's not being listened on yet.
return connsPerHostClosedCh
}
// decHostConnCount decrements the count of connections
// for a given host.
// See Transport.MaxConnsPerHost.
func (t *Transport) decHostConnCount(cmKey connectMethodKey) {
if t.MaxConnsPerHost <= 0 {
return
}
t.connCountMu.Lock()
defer t.connCountMu.Unlock()
t.connPerHostCount[cmKey]--
select {
case t.connPerHostAvailable[cmKey] <- struct{}{}:
default:
// close channel before deleting avoids getConn waiting forever in
// case getConn has reference to channel but hasn't started waiting.
// This could lead to more than MaxConnsPerHost in the unlikely case
// that > 1 go routine has fetched the channel but none started waiting.
if t.connPerHostAvailable[cmKey] != nil {
close(t.connPerHostAvailable[cmKey])
}
delete(t.connPerHostAvailable, cmKey)
}
if t.connPerHostCount[cmKey] == 0 {
delete(t.connPerHostCount, cmKey)
}
}
// connCloseListener wraps a connection, the transport that dialed it
// and the connected-to host key so the host connection count can be
// transparently decremented by whatever closes the embedded connection.
type connCloseListener struct {
net.Conn
t *Transport
cmKey connectMethodKey
didClose int32
}
func (c *connCloseListener) Close() error {
if atomic.AddInt32(&c.didClose, 1) != 1 {
return nil
}
err := c.Conn.Close()
c.t.decHostConnCount(c.cmKey)
return err
}
// The connect method and the transport can both specify a TLS
// Host name. The transport's name takes precedence if present.
func chooseTLSHost(cm connectMethod, t *Transport) string {
tlsHost := ""
if t.TLSClientConfig != nil {
tlsHost = t.TLSClientConfig.ServerName
}
if tlsHost == "" {
tlsHost = cm.tlsHost()
}
return tlsHost
}
// Add TLS to a persistent connection, i.e. negotiate a TLS session. If pconn is already a TLS
// tunnel, this function establishes a nested TLS session inside the encrypted channel.
// The remote endpoint's name may be overridden by TLSClientConfig.ServerName.
func (pconn *persistConn) addTLS(name string, trace *httptrace.ClientTrace) error {
// Initiate TLS and check remote host name against certificate.
cfg := cloneTLSConfig(pconn.t.TLSClientConfig)
if cfg.ServerName == "" {
cfg.ServerName = name
}
plainConn := pconn.conn
tlsConn := tls.Client(plainConn, cfg)
errc := make(chan error, 2)
var timer *time.Timer // for canceling TLS handshake
if d := pconn.t.TLSHandshakeTimeout; d != 0 {
timer = time.AfterFunc(d, func() {
errc <- tlsHandshakeTimeoutError{}
})
}
go func() {
if trace != nil && trace.TLSHandshakeStart != nil {
trace.TLSHandshakeStart()
}
err := tlsConn.Handshake()
if timer != nil {
timer.Stop()
}
errc <- err
}()
if err := <-errc; err != nil {
plainConn.Close()
if trace != nil && trace.TLSHandshakeDone != nil {
trace.TLSHandshakeDone(tls.ConnectionState{}, err)
}
return err
}
cs := tlsConn.ConnectionState()
if trace != nil && trace.TLSHandshakeDone != nil {
trace.TLSHandshakeDone(cs, nil)
}
pconn.tlsState = &cs
pconn.conn = tlsConn
return nil
}
func (t *Transport) dialConn(ctx context.Context, 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),
writeLoopDone: make(chan struct{}),
}
trace := httptrace.ContextClientTrace(ctx)
wrapErr := func(err error) error {
if cm.proxyURL != nil {
// Return a typed error, per Issue 16997
return &net.OpError{Op: "proxyconnect", Net: "tcp", Err: err}
}
return err
}
if cm.scheme() == "https" && t.DialTLS != nil {
var err error
pconn.conn, err = t.DialTLS(t.getNetworkString(), cm.addr())
if err != nil {
return nil, wrapErr(err)
}
if pconn.conn == nil {
return nil, wrapErr(errors.New("net/http: Transport.DialTLS returned (nil, nil)"))
}
if tc, ok := pconn.conn.(*tls.Conn); ok {
// Handshake here, in case DialTLS didn't. TLSNextProto below
// depends on it for knowing the connection state.
if trace != nil && trace.TLSHandshakeStart != nil {
trace.TLSHandshakeStart()
}
if err := tc.Handshake(); err != nil {
go pconn.conn.Close()
if trace != nil && trace.TLSHandshakeDone != nil {
trace.TLSHandshakeDone(tls.ConnectionState{}, err)
}
return nil, err
}
cs := tc.ConnectionState()
if trace != nil && trace.TLSHandshakeDone != nil {
trace.TLSHandshakeDone(cs, nil)
}
pconn.tlsState = &cs
}
} else {
conn, err := t.dial(ctx, t.getNetworkString(), cm.addr())
if err != nil {
return nil, wrapErr(err)
}
pconn.conn = conn
if cm.scheme() == "https" {
var firstTLSHost string
if firstTLSHost, _, err = net.SplitHostPort(cm.addr()); err != nil {
return nil, wrapErr(err)
}
if err = pconn.addTLS(firstTLSHost, trace); err != nil {
return nil, wrapErr(err)
}
}
}
// Proxy setup.
switch {
case cm.proxyURL == nil:
// Do nothing. Not using a proxy.
case cm.proxyURL.Scheme == "socks5":
conn := pconn.conn
d := socksNewDialer("tcp", conn.RemoteAddr().String())
if u := cm.proxyURL.User; u != nil {
auth := &socksUsernamePassword{
Username: u.Username(),
}
auth.Password, _ = u.Password()
d.AuthMethods = []socksAuthMethod{
socksAuthMethodNotRequired,
socksAuthMethodUsernamePassword,
}
d.Authenticate = auth.Authenticate
}
if _, err := d.DialWithConn(ctx, conn, "tcp", cm.targetAddr); err != nil {
conn.Close()
return nil, err
}
case cm.targetScheme == "http":
pconn.isProxy = true
if pa := cm.proxyAuth(); pa != "" {
pconn.mutateHeaderFunc = func(h Header) {
h.Set("Proxy-Authorization", pa)
}
}
case cm.targetScheme == "https":
conn := pconn.conn
hdr := t.ProxyConnectHeader
if hdr == nil {
hdr = make(Header)
}
connectReq := &Request{
Method: "CONNECT",
URL: &url.URL{Opaque: cm.targetAddr},
Host: cm.targetAddr,
Header: hdr,
}
if pa := cm.proxyAuth(); pa != "" {
connectReq.Header.Set("Proxy-Authorization", pa)
}
connectReq.Write(conn)
// Read response.
// Okay to use and discard buffered reader here, because
// TLS server will not speak until spoken to.
br := bufio.NewReader(conn)
resp, err := ReadResponse(br, connectReq)
if err != nil {
conn.Close()
return nil, err
}
if resp.StatusCode != 200 {
f := strings.SplitN(resp.Status, " ", 2)
conn.Close()
if len(f) < 2 {
return nil, errors.New("unknown status code")
}
return nil, errors.New(f[1])
}
}
if cm.proxyURL != nil && cm.targetScheme == "https" {
if err := pconn.addTLS(cm.tlsHost(), trace); err != nil {
return nil, err
}
}
if s := pconn.tlsState; s != nil && s.NegotiatedProtocolIsMutual && s.NegotiatedProtocol != "" {
if next, ok := t.TLSNextProto[s.NegotiatedProtocol]; ok {
return &persistConn{alt: next(cm.targetAddr, pconn.conn.(*tls.Conn))}, nil
}
}
if t.MaxConnsPerHost > 0 {
pconn.conn = &connCloseListener{Conn: pconn.conn, t: t, cmKey: pconn.cacheKey}
}
pconn.br = bufio.NewReader(pconn)
pconn.bw = bufio.NewWriter(persistConnWriter{pconn})
go pconn.readLoop()
go pconn.writeLoop()
return pconn, nil
}
// persistConnWriter is the io.Writer written to by pc.bw.
// It accumulates the number of bytes written to the underlying conn,
// so the retry logic can determine whether any bytes made it across
// the wire.
// This is exactly 1 pointer field wide so it can go into an interface
// without allocation.
type persistConnWriter struct {
pc *persistConn
}
func (w persistConnWriter) Write(p []byte) (n int, err error) {
n, err = w.pc.conn.Write(p)
w.pc.nwrite += int64(n)
return
}
// 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
// socks5://proxy.com|http|foo.com socks5 to proxy, then http to foo.com
// socks5://proxy.com|https|foo.com socks5 to proxy, then https to foo.com
// https://proxy.com|https|foo.com https to proxy, then CONNECT to foo.com
// https://proxy.com|http https to proxy, http to anywhere after that
//
type connectMethod struct {
proxyURL *url.URL // nil for no proxy, else full proxy URL
targetScheme string // "http" or "https"
// If proxyURL specifies an http or https proxy, and targetScheme is http (not https),
// then targetAddr is not included in the connect method key, because the socket can
// be reused for different targetAddr values.
targetAddr string
}
func (cm *connectMethod) key() connectMethodKey {
proxyStr := ""
targetAddr := cm.targetAddr
if cm.proxyURL != nil {
proxyStr = cm.proxyURL.String()
if (cm.proxyURL.Scheme == "http" || cm.proxyURL.Scheme == "https") && cm.targetScheme == "http" {
targetAddr = ""
}
}
return connectMethodKey{
proxy: proxyStr,
scheme: cm.targetScheme,
addr: targetAddr,
}
}
// scheme returns the first hop scheme: http, https, or socks5
func (cm *connectMethod) scheme() string {
if cm.proxyURL != nil {
return cm.proxyURL.Scheme
}
return cm.targetScheme
}
// addr returns the first hop "host:port" to which we need to TCP connect.
func (cm *connectMethod) addr() string {
if cm.proxyURL != nil {
return canonicalAddr(cm.proxyURL)
}
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 {
proxy, scheme, addr string
}
func (k connectMethodKey) String() string {
// Only used by tests.
return fmt.Sprintf("%s|%s|%s", k.proxy, 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 {
// alt optionally specifies the TLS NextProto RoundTripper.
// This is used for HTTP/2 today and future protocols later.
// If it's non-nil, the rest of the fields are unused.
alt RoundTripper
t *Transport
cacheKey connectMethodKey
conn net.Conn
tlsState *tls.ConnectionState
br *bufio.Reader // from conn
bw *bufio.Writer // to conn
nwrite int64 // bytes written
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
isProxy bool
sawEOF bool // whether we've seen EOF from conn; owned by readLoop
readLimit int64 // bytes allowed to be read; owned by readLoop
// 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
writeLoopDone chan struct{} // closed when write loop ends
// Both guarded by Transport.idleMu:
idleAt time.Time // time it last become idle
idleTimer *time.Timer // holding an AfterFunc to close it
mu sync.Mutex // guards following fields
numExpectedResponses int
closed error // set non-nil when conn is closed, before closech is closed
canceledErr error // set non-nil if conn is canceled
broken bool // an error has happened on this connection; marked broken so it's not reused.
reused bool // whether conn has had successful request/response and is being reused.
// 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(Header)
}
func (pc *persistConn) maxHeaderResponseSize() int64 {
if v := pc.t.MaxResponseHeaderBytes; v != 0 {
return v
}
return 10 << 20 // conservative default; same as http2
}
func (pc *persistConn) Read(p []byte) (n int, err error) {
if pc.readLimit <= 0 {
return 0, fmt.Errorf("read limit of %d bytes exhausted", pc.maxHeaderResponseSize())
}
if int64(len(p)) > pc.readLimit {
p = p[:pc.readLimit]
}
n, err = pc.conn.Read(p)
if err == io.EOF {
pc.sawEOF = true
}
pc.readLimit -= int64(n)
return
}
// isBroken reports whether this connection is in a known broken state.
func (pc *persistConn) isBroken() bool {
pc.mu.Lock()
b := pc.closed != nil
pc.mu.Unlock()
return b
}
// canceled returns non-nil if the connection was closed due to
// CancelRequest or due to context cancelation.
func (pc *persistConn) canceled() error {
pc.mu.Lock()
defer pc.mu.Unlock()
return pc.canceledErr
}
// isReused reports whether this connection is in a known broken state.
func (pc *persistConn) isReused() bool {
pc.mu.Lock()
r := pc.reused
pc.mu.Unlock()
return r
}
func (pc *persistConn) gotIdleConnTrace(idleAt time.Time) (t httptrace.GotConnInfo) {
pc.mu.Lock()
defer pc.mu.Unlock()
t.Reused = pc.reused
t.Conn = pc.conn
t.WasIdle = true
if !idleAt.IsZero() {
t.IdleTime = time.Since(idleAt)
}
return
}
func (pc *persistConn) cancelRequest(err error) {
pc.mu.Lock()
defer pc.mu.Unlock()
pc.canceledErr = err
pc.closeLocked(errRequestCanceled)
}
// closeConnIfStillIdle closes the connection if it's still sitting idle.
// This is what's called by the persistConn's idleTimer, and is run in its
// own goroutine.
func (pc *persistConn) closeConnIfStillIdle() {
t := pc.t
t.idleMu.Lock()
defer t.idleMu.Unlock()
if _, ok := t.idleLRU.m[pc]; !ok {
// Not idle.
return
}
t.removeIdleConnLocked(pc)
pc.close(errIdleConnTimeout)
}
// mapRoundTripError returns the appropriate error value for
// persistConn.roundTrip.
//
// The provided err is the first error that (*persistConn).roundTrip
// happened to receive from its select statement.
//
// The startBytesWritten value should be the value of pc.nwrite before the roundTrip
// started writing the request.
func (pc *persistConn) mapRoundTripError(req *transportRequest, startBytesWritten int64, err error) error {
if err == nil {
return nil
}
// If the request was canceled, that's better than network
// failures that were likely the result of tearing down the
// connection.
if cerr := pc.canceled(); cerr != nil {
return cerr
}
// See if an error was set explicitly.
req.mu.Lock()
reqErr := req.err
req.mu.Unlock()
if reqErr != nil {
return reqErr
}
if err == errServerClosedIdle {
// Don't decorate
return err
}
if _, ok := err.(transportReadFromServerError); ok {
// Don't decorate
return err
}
if pc.isBroken() {
<-pc.writeLoopDone
if pc.nwrite == startBytesWritten {
return nothingWrittenError{err}
}
return fmt.Errorf("net/http: HTTP/1.x transport connection broken: %v", err)
}
return err
}
func (pc *persistConn) readLoop() {
closeErr := errReadLoopExiting // default value, if not changed below
defer func() {
pc.close(closeErr)
pc.t.removeIdleConn(pc)
}()
tryPutIdleConn := func(trace *httptrace.ClientTrace) bool {
if err := pc.t.tryPutIdleConn(pc); err != nil {
closeErr = err
if trace != nil && trace.PutIdleConn != nil && err != errKeepAlivesDisabled {
trace.PutIdleConn(err)
}
return false
}
if trace != nil && trace.PutIdleConn != nil {
trace.PutIdleConn(nil)
}
return true
}
// eofc is used to block caller 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 {
pc.readLimit = pc.maxHeaderResponseSize()
_, err := pc.br.Peek(1)
pc.mu.Lock()
if pc.numExpectedResponses == 0 {
pc.readLoopPeekFailLocked(err)
pc.mu.Unlock()
return
}
pc.mu.Unlock()
rc := <-pc.reqch
trace := httptrace.ContextClientTrace(rc.req.Context())
var resp *Response
if err == nil {
resp, err = pc.readResponse(rc, trace)
} else {
err = transportReadFromServerError{err}
closeErr = err
}
if err != nil {
if pc.readLimit <= 0 {
err = fmt.Errorf("net/http: server response headers exceeded %d bytes; aborted", pc.maxHeaderResponseSize())
}
select {
case rc.ch <- responseAndError{err: err}:
case <-rc.callerGone:
return
}
return
}
pc.readLimit = maxInt64 // effictively no limit for response bodies
pc.mu.Lock()
pc.numExpectedResponses--
pc.mu.Unlock()
hasBody := rc.req.Method != "HEAD" && resp.ContentLength != 0
if 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
}
if !hasBody {
pc.t.setReqCanceler(rc.req, nil)
// Put the idle conn back into the pool before we send the response
// so if they process it quickly and make another request, they'll
// get this same conn. But we use the unbuffered channel 'rc'
// to guarantee that persistConn.roundTrip got out of its select
// potentially waiting for this persistConn to close.
// but after
alive = alive &&
!pc.sawEOF &&
pc.wroteRequest() &&
tryPutIdleConn(trace)
select {
case rc.ch <- responseAndError{res: resp}:
case <-rc.callerGone:
return
}
// Now that they've read from the unbuffered channel, they're safely
// out of the select that also waits on this goroutine to die, so
// we're allowed to exit now if needed (if alive is false)
testHookReadLoopBeforeNextRead()
continue
}
waitForBodyRead := make(chan bool, 2)
body := &bodyEOFSignal{
body: resp.Body,
earlyCloseFn: func() error {
waitForBodyRead <- false
<-eofc // will be closed by deferred call at the end of the function
return nil
},
fn: func(err error) error {
isEOF := err == io.EOF
waitForBodyRead <- isEOF
if isEOF {
<-eofc // see comment above eofc declaration
} else if err != nil {
if cerr := pc.canceled(); cerr != nil {
return cerr
}
}
return err
},
}
resp.Body = body
if rc.addedGzip && strings.EqualFold(resp.Header.Get("Content-Encoding"), "gzip") {
resp.Body = &gzipReader{body: body}
resp.Header.Del("Content-Encoding")
resp.Header.Del("Content-Length")
resp.ContentLength = -1
resp.Uncompressed = true
}
select {
case rc.ch <- responseAndError{res: resp}:
case <-rc.callerGone:
return
}
// Before looping back to the top of this function and peeking on
// the bufio.Reader, wait for the caller goroutine to finish
// reading the response body. (or for cancelation or death)
select {
case bodyEOF := <-waitForBodyRead:
pc.t.setReqCanceler(rc.req, nil) // before pc might return to idle pool
alive = alive &&
bodyEOF &&
!pc.sawEOF &&
pc.wroteRequest() &&
tryPutIdleConn(trace)
if bodyEOF {
eofc <- struct{}{}
}
case <-rc.req.Cancel:
alive = false
pc.t.CancelRequest(rc.req)
case <-rc.req.Context().Done():
alive = false
pc.t.cancelRequest(rc.req, rc.req.Context().Err())
case <-pc.closech:
alive = false
}
testHookReadLoopBeforeNextRead()
}
}
func (pc *persistConn) readLoopPeekFailLocked(peekErr error) {
if pc.closed != nil {
return
}
if n := pc.br.Buffered(); n > 0 {
buf, _ := pc.br.Peek(n)
log.Printf("Unsolicited response received on idle HTTP channel starting with %q; err=%v", buf, peekErr)
}
if peekErr == io.EOF {
// common case.
pc.closeLocked(errServerClosedIdle)
} else {
pc.closeLocked(fmt.Errorf("readLoopPeekFailLocked: %v", peekErr))
}
}
// readResponse reads an HTTP response (or two, in the case of "Expect:
// 100-continue") from the server. It returns the final non-100 one.
// trace is optional.
func (pc *persistConn) readResponse(rc requestAndChan, trace *httptrace.ClientTrace) (resp *Response, err error) {
if trace != nil && trace.GotFirstResponseByte != nil {
if peek, err := pc.br.Peek(1); err == nil && len(peek) == 1 {
trace.GotFirstResponseByte()
}
}
num1xx := 0 // number of informational 1xx headers received
const max1xxResponses = 5 // arbitrary bound on number of informational responses
continueCh := rc.continueCh
for {
resp, err = ReadResponse(pc.br, rc.req)
if err != nil {
return
}
resCode := resp.StatusCode
if continueCh != nil {
if resCode == 100 {
if trace != nil && trace.Got100Continue != nil {
trace.Got100Continue()
}
continueCh <- struct{}{}
continueCh = nil
} else if resCode >= 200 {
close(continueCh)
continueCh = nil
}
}
is1xx := 100 <= resCode && resCode <= 199
// treat 101 as a terminal status, see issue 26161
is1xxNonTerminal := is1xx && resCode != StatusSwitchingProtocols
if is1xxNonTerminal {
num1xx++
if num1xx > max1xxResponses {
return nil, errors.New("net/http: too many 1xx informational responses")
}
pc.readLimit = pc.maxHeaderResponseSize() // reset the limit
if trace != nil && trace.Got1xxResponse != nil {
if err := trace.Got1xxResponse(resCode, textproto.MIMEHeader(resp.Header)); err != nil {
return nil, err
}
}
continue
}
break
}
resp.TLS = pc.tlsState
return
}
// waitForContinue returns the function to block until
// any response, timeout or connection close. After any of them,
// the function returns a bool which indicates if the body should be sent.
func (pc *persistConn) waitForContinue(continueCh <-chan struct{}) func() bool {
if continueCh == nil {
return nil
}
return func() bool {
timer := time.NewTimer(pc.t.ExpectContinueTimeout)
defer timer.Stop()
select {
case _, ok := <-continueCh:
return ok
case <-timer.C:
return true
case <-pc.closech:
return false
}
}
}
// nothingWrittenError wraps a write errors which ended up writing zero bytes.
type nothingWrittenError struct {
error
}
func (pc *persistConn) writeLoop() {
defer close(pc.writeLoopDone)
for {
select {
case wr := <-pc.writech:
startBytesWritten := pc.nwrite
err := wr.req.Request.write(pc.bw, pc.isProxy, wr.req.extra, pc.waitForContinue(wr.continueCh))
if bre, ok := err.(requestBodyReadError); ok {
err = bre.error
// Errors reading from the user's
// Request.Body are high priority.
// Set it here before sending on the
// channels below or calling
// pc.close() which tears town
// connections and causes other
// errors.
wr.req.setError(err)
}
if err == nil {
err = pc.bw.Flush()
}
if err != nil {
wr.req.Request.closeBody()
if pc.nwrite == startBytesWritten {
err = nothingWrittenError{err}
}
}
pc.writeErrCh <- err // to the body reader, which might recycle us
wr.ch <- err // to the roundTrip function
if err != nil {
pc.close(err)
return
}
case <-pc.closech:
return
}
}
}
// maxWriteWaitBeforeConnReuse is how long the a Transport RoundTrip
// will wait to see the Request's Body.Write result after getting a
// response from the server. See comments in (*persistConn).wroteRequest.
const maxWriteWaitBeforeConnReuse = 50 * time.Millisecond
// 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(maxWriteWaitBeforeConnReuse):
return false
}
}
}
// responseAndError is how the goroutine reading from an HTTP/1 server
// communicates with the goroutine doing the RoundTrip.
type responseAndError struct {
res *Response // else use this response (see res method)
err error
}
type requestAndChan struct {
req *Request
ch chan responseAndError // unbuffered; always send in select on callerGone
// whether the Transport (as opposed to the user client code)
// added the Accept-Encoding gzip header. If the Transport
// set it, only then do we transparently decode the gzip.
addedGzip bool
// Optional blocking chan for Expect: 100-continue (for send).
// If the request has an "Expect: 100-continue" header and
// the server responds 100 Continue, readLoop send a value
// to writeLoop via this chan.
continueCh chan<- struct{}
callerGone <-chan struct{} // closed when roundTrip caller has returned
}
// 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
// Optional blocking chan for Expect: 100-continue (for receive).
// If not nil, writeLoop blocks sending request body until
// it receives from this chan.
continueCh <-chan struct{}
}
type httpError struct {
err string
timeout bool
}
func (e *httpError) Error() string { return e.err }
func (e *httpError) Timeout() bool { return e.timeout }
func (e *httpError) Temporary() bool { return true }
var errTimeout error = &httpError{err: "net/http: timeout awaiting response headers", timeout: true}
var errRequestCanceled = errors.New("net/http: request canceled")
var errRequestCanceledConn = errors.New("net/http: request canceled while waiting for connection") // TODO: unify?
func nop() {}
// testHooks. Always non-nil.
var (
testHookEnterRoundTrip = nop
testHookWaitResLoop = nop
testHookRoundTripRetried = nop
testHookPrePendingDial = nop
testHookPostPendingDial = nop
testHookMu sync.Locker = fakeLocker{} // guards following
testHookReadLoopBeforeNextRead = nop
)
func (pc *persistConn) roundTrip(req *transportRequest) (resp *Response, err error) {
testHookEnterRoundTrip()
if !pc.t.replaceReqCanceler(req.Request, pc.cancelRequest) {
pc.t.putOrCloseIdleConn(pc)
return nil, errRequestCanceled
}
pc.mu.Lock()
pc.numExpectedResponses++
headerFn := pc.mutateHeaderFunc
pc.mu.Unlock()
if headerFn != nil {
headerFn(req.extraHeaders())
}
// Ask for a compressed version if the caller didn't set their
// own value for Accept-Encoding. We only attempt to
// uncompress the gzip stream if we were the layer that
// requested it.
requestedGzip := false
if !pc.t.DisableCompression &&
req.Header.Get("Accept-Encoding") == "" &&
req.Header.Get("Range") == "" &&
req.Method != "HEAD" {
// Request gzip only, not deflate. Deflate is ambiguous and
// not as universally supported anyway.
// See: http://www.gzip.org/zlib/zlib_faq.html#faq38
//
// Note that we don't request this for HEAD requests,
// due to a bug in nginx:
// https://trac.nginx.org/nginx/ticket/358
// https://golang.org/issue/5522
//
// We don't request gzip if the request is for a range, since
// auto-decoding a portion of a gzipped document will just fail
// anyway. See https://golang.org/issue/8923
requestedGzip = true
req.extraHeaders().Set("Accept-Encoding", "gzip")
}
var continueCh chan struct{}
if req.ProtoAtLeast(1, 1) && req.Body != nil && req.expectsContinue() {
continueCh = make(chan struct{}, 1)
}
if pc.t.DisableKeepAlives {
req.extraHeaders().Set("Connection", "close")
}
gone := make(chan struct{})
defer close(gone)
defer func() {
if err != nil {
pc.t.setReqCanceler(req.Request, nil)
}
}()
const debugRoundTrip = false
// Write the request concurrently with waiting for a response,
// in case the server decides to reply before reading our full
// request body.
startBytesWritten := pc.nwrite
writeErrCh := make(chan error, 1)
pc.writech <- writeRequest{req, writeErrCh, continueCh}
resc := make(chan responseAndError)
pc.reqch <- requestAndChan{
req: req.Request,
ch: resc,
addedGzip: requestedGzip,
continueCh: continueCh,
callerGone: gone,
}
var respHeaderTimer <-chan time.Time
cancelChan := req.Request.Cancel
ctxDoneChan := req.Context().Done()
for {
testHookWaitResLoop()
select {
case err := <-writeErrCh:
if debugRoundTrip {
req.logf("writeErrCh resv: %T/%#v", err, err)
}
if err != nil {
pc.close(fmt.Errorf("write error: %v", err))
return nil, pc.mapRoundTripError(req, startBytesWritten, err)
}
if d := pc.t.ResponseHeaderTimeout; d > 0 {
if debugRoundTrip {
req.logf("starting timer for %v", d)
}
timer := time.NewTimer(d)
defer timer.Stop() // prevent leaks
respHeaderTimer = timer.C
}
case <-pc.closech:
if debugRoundTrip {
req.logf("closech recv: %T %#v", pc.closed, pc.closed)
}
return nil, pc.mapRoundTripError(req, startBytesWritten, pc.closed)
case <-respHeaderTimer:
if debugRoundTrip {
req.logf("timeout waiting for response headers.")
}
pc.close(errTimeout)
return nil, errTimeout
case re := <-resc:
if (re.res == nil) == (re.err == nil) {
panic(fmt.Sprintf("internal error: exactly one of res or err should be set; nil=%v", re.res == nil))
}
if debugRoundTrip {
req.logf("resc recv: %p, %T/%#v", re.res, re.err, re.err)
}
if re.err != nil {
return nil, pc.mapRoundTripError(req, startBytesWritten, re.err)
}
return re.res, nil
case <-cancelChan:
pc.t.CancelRequest(req.Request)
cancelChan = nil
case <-ctxDoneChan:
pc.t.cancelRequest(req.Request, req.Context().Err())
cancelChan = nil
ctxDoneChan = nil
}
}
}
// tLogKey is a context WithValue key for test debugging contexts containing
// a t.Logf func. See export_test.go's Request.WithT method.
type tLogKey struct{}
func (tr *transportRequest) logf(format string, args ...interface{}) {
if logf, ok := tr.Request.Context().Value(tLogKey{}).(func(string, ...interface{})); ok {
logf(time.Now().Format(time.RFC3339Nano)+": "+format, args...)
}
}
// markReused marks this connection as having been successfully used for a
// request and response.
func (pc *persistConn) markReused() {
pc.mu.Lock()
pc.reused = true
pc.mu.Unlock()
}
// close closes the underlying TCP connection and closes
// the pc.closech channel.
//
// The provided err is only for testing and debugging; in normal
// circumstances it should never be seen by users.
func (pc *persistConn) close(err error) {
pc.mu.Lock()
defer pc.mu.Unlock()
pc.closeLocked(err)
}
func (pc *persistConn) closeLocked(err error) {
if err == nil {
panic("nil error")
}
pc.broken = true
if pc.closed == nil {
pc.closed = err
if pc.alt != nil {
// Do nothing; can only get here via getConn's
// handlePendingDial's putOrCloseIdleConn when
// it turns out the abandoned connection in
// flight ended up negotiating an alternate
// protocol. We don't use the connection
// freelist for http2. That's done by the
// alternate protocol's RoundTripper.
} else {
pc.conn.Close()
close(pc.closech)
}
}
pc.mutateHeaderFunc = nil
}
var portMap = map[string]string{
"http": "80",
"https": "443",
"socks5": "1080",
}
// canonicalAddr returns url.Host but always with a ":port" suffix
func canonicalAddr(url *url.URL) string {
addr := url.Hostname()
if v, err := idnaASCII(addr); err == nil {
addr = v
}
port := url.Port()
if port == "" {
port = portMap[url.Scheme]
}
return net.JoinHostPort(addr, port)
}
// bodyEOFSignal is used by the HTTP/1 transport when reading response
// bodies to make sure we see the end of a response body before
// proceeding and reading on the connection again.
//
// It wraps a ReadCloser but runs fn (if non-nil) at most
// once, right before its final (error-producing) Read or Close call
// returns. fn should return the new error to return from Read or Close.
//
// If earlyCloseFn is non-nil and Close is called before io.EOF is
// seen, earlyCloseFn is called instead of fn, and its return value is
// the return value from Close.
type bodyEOFSignal struct {
body io.ReadCloser
mu sync.Mutex // guards following 4 fields
closed bool // whether Close has been called
rerr error // sticky Read error
fn func(error) error // err will be nil on Read io.EOF
earlyCloseFn func() error // optional alt Close func used if io.EOF not seen
}
var errReadOnClosedResBody = errors.New("http: read on closed response body")
func (es *bodyEOFSignal) Read(p []byte) (n int, err error) {
es.mu.Lock()
closed, rerr := es.closed, es.rerr
es.mu.Unlock()
if closed {
return 0, errReadOnClosedResBody
}
if rerr != nil {
return 0, rerr
}
n, err = es.body.Read(p)
if err != nil {
es.mu.Lock()
defer es.mu.Unlock()
if es.rerr == nil {
es.rerr = err
}
err = es.condfn(err)
}
return
}
func (es *bodyEOFSignal) Close() error {
es.mu.Lock()
defer es.mu.Unlock()
if es.closed {
return nil
}
es.closed = true
if es.earlyCloseFn != nil && es.rerr != io.EOF {
return es.earlyCloseFn()
}
err := es.body.Close()
return es.condfn(err)
}
// caller must hold es.mu.
func (es *bodyEOFSignal) condfn(err error) error {
if es.fn == nil {
return err
}
err = es.fn(err)
es.fn = nil
return err
}
// gzipReader wraps a response body so it can lazily
// call gzip.NewReader on the first call to Read
type gzipReader struct {
body *bodyEOFSignal // underlying HTTP/1 response body framing
zr *gzip.Reader // lazily-initialized gzip reader
zerr error // any error from gzip.NewReader; sticky
}
func (gz *gzipReader) Read(p []byte) (n int, err error) {
if gz.zr == nil {
if gz.zerr == nil {
gz.zr, gz.zerr = gzip.NewReader(gz.body)
}
if gz.zerr != nil {
return 0, gz.zerr
}
}
gz.body.mu.Lock()
if gz.body.closed {
err = errReadOnClosedResBody
}
gz.body.mu.Unlock()
if err != nil {
return 0, err
}
return gz.zr.Read(p)
}
func (gz *gzipReader) Close() error {
return gz.body.Close()
}
type readerAndCloser struct {
io.Reader
io.Closer
}
type tlsHandshakeTimeoutError struct{}
func (tlsHandshakeTimeoutError) Timeout() bool { return true }
func (tlsHandshakeTimeoutError) Temporary() bool { return true }
func (tlsHandshakeTimeoutError) Error() string { return "net/http: TLS handshake timeout" }
// fakeLocker is a sync.Locker which does nothing. It's used to guard
// test-only fields when not under test, to avoid runtime atomic
// overhead.
type fakeLocker struct{}
func (fakeLocker) Lock() {}
func (fakeLocker) Unlock() {}
// clneTLSConfig returns a shallow clone of cfg, or a new zero tls.Config if
// cfg is nil. This is safe to call even if cfg is in active use by a TLS
// client or server.
func cloneTLSConfig(cfg *tls.Config) *tls.Config {
if cfg == nil {
return &tls.Config{}
}
return cfg.Clone()
}
type connLRU struct {
ll *list.List // list.Element.Value type is of *persistConn
m map[*persistConn]*list.Element
}
// add adds pc to the head of the linked list.
func (cl *connLRU) add(pc *persistConn) {
if cl.ll == nil {
cl.ll = list.New()
cl.m = make(map[*persistConn]*list.Element)
}
ele := cl.ll.PushFront(pc)
if _, ok := cl.m[pc]; ok {
panic("persistConn was already in LRU")
}
cl.m[pc] = ele
}
func (cl *connLRU) removeOldest() *persistConn {
ele := cl.ll.Back()
pc := ele.Value.(*persistConn)
cl.ll.Remove(ele)
delete(cl.m, pc)
return pc
}
// remove removes pc from cl.
func (cl *connLRU) remove(pc *persistConn) {
if ele, ok := cl.m[pc]; ok {
cl.ll.Remove(ele)
delete(cl.m, pc)
}
}
// len returns the number of items in the cache.
func (cl *connLRU) len() int {
return len(cl.m)
}
// validPort reports whether p (without the colon) is a valid port in
// a URL, per RFC 3986 Section 3.2.3, which says the port may be
// empty, or only contain digits.
func validPort(p string) bool {
for _, r := range []byte(p) {
if r < '0' || r > '9' {
return false
}
}
return true
}
func (t *Transport) getNetworkString() string {
if t.IPv4Only {
return "tcp4"
}
if t.IPv6Only {
return "tcp6"
} else {
return "tcp"
}
}
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