// 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" "internal/godebug" "io" "log" "net" "net/http/httptrace" "net/http/internal/ascii" "net/textproto" "net/url" "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: defaultTransportDialContext(&net.Dialer{ Timeout: 30 * time.Second, KeepAlive: 30 * time.Second, }), ForceAttemptHTTP2: true, MaxIdleConns: 100, IdleConnTimeout: 90 * time.Second, TLSHandshakeTimeout: 10 * time.Second, ExpectContinueTimeout: 1 * time.Second, } // 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). // // 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. // // 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. // // Transport only retries a request upon encountering a network error // if the request is idempotent and either has no body or has its // Request.GetBody defined. HTTP requests are considered idempotent if // they have HTTP methods GET, HEAD, OPTIONS, or TRACE; or if their // Header map contains an "Idempotency-Key" or "X-Idempotency-Key" // entry. If the idempotency key value is a zero-length slice, the // request is treated as idempotent but the header is not sent on the // wire. type Transport struct { idleMu sync.Mutex closeIdle bool // user has requested to close all idle conns idleConn map[connectMethodKey][]*persistConn // most recently used at end idleConnWait map[connectMethodKey]wantConnQueue // waiting getConns idleLRU connLRU reqMu sync.Mutex reqCanceler map[cancelKey]func(error) altMu sync.Mutex // guards changing altProto only altProto atomic.Value // of nil or map[string]RoundTripper, key is URI scheme connsPerHostMu sync.Mutex connsPerHost map[connectMethodKey]int connsPerHostWait map[connectMethodKey]wantConnQueue // waiting getConns // 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 // a 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 // a 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) // DialTLSContext specifies an optional dial function for creating // TLS connections for non-proxied HTTPS requests. // // If DialTLSContext is nil (and the deprecated DialTLS below is also nil), // DialContext and TLSClientConfig are used. // // If DialTLSContext is set, the Dial and DialContext hooks are 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. DialTLSContext func(ctx context.Context, network, addr string) (net.Conn, error) // DialTLS specifies an optional dial function for creating // TLS connections for non-proxied HTTPS requests. // // Deprecated: Use DialTLSContext instead, which allows the transport // to cancel dials as soon as they are no longer needed. // If both are set, DialTLSContext takes priority. DialTLS func(network, addr string) (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. 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 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. // To set the header dynamically, see GetProxyConnectHeader. ProxyConnectHeader Header // GetProxyConnectHeader optionally specifies a func to return // headers to send to proxyURL during a CONNECT request to the // ip:port target. // If it returns an error, the Transport's RoundTrip fails with // that error. It can return (nil, nil) to not add headers. // If GetProxyConnectHeader is non-nil, ProxyConnectHeader is // ignored. GetProxyConnectHeader func(ctx context.Context, proxyURL *url.URL, target string) (Header, error) // 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 // WriteBufferSize specifies the size of the write buffer used // when writing to the transport. // If zero, a default (currently 4KB) is used. WriteBufferSize int // ReadBufferSize specifies the size of the read buffer used // when reading from the transport. // If zero, a default (currently 4KB) is used. ReadBufferSize int // nextProtoOnce guards initialization of TLSNextProto and // h2transport (via onceSetNextProtoDefaults) nextProtoOnce sync.Once h2transport h2Transport // non-nil if http2 wired up tlsNextProtoWasNil bool // whether TLSNextProto was nil when the Once fired // ForceAttemptHTTP2 controls whether HTTP/2 is enabled when a non-zero // Dial, DialTLS, or DialContext func or TLSClientConfig is provided. // By default, use of any those fields conservatively disables HTTP/2. // To use a custom dialer or TLS config and still attempt HTTP/2 // upgrades, set this to true. ForceAttemptHTTP2 bool } // A cancelKey is the key of the reqCanceler map. // We wrap the *Request in this type since we want to use the original request, // not any transient one created by roundTrip. type cancelKey struct { req *Request } func (t *Transport) writeBufferSize() int { if t.WriteBufferSize > 0 { return t.WriteBufferSize } return 4 << 10 } func (t *Transport) readBufferSize() int { if t.ReadBufferSize > 0 { return t.ReadBufferSize } return 4 << 10 } // Clone returns a deep copy of t's exported fields. func (t *Transport) Clone() *Transport { t.nextProtoOnce.Do(t.onceSetNextProtoDefaults) t2 := &Transport{ Proxy: t.Proxy, DialContext: t.DialContext, Dial: t.Dial, DialTLS: t.DialTLS, DialTLSContext: t.DialTLSContext, TLSHandshakeTimeout: t.TLSHandshakeTimeout, DisableKeepAlives: t.DisableKeepAlives, DisableCompression: t.DisableCompression, MaxIdleConns: t.MaxIdleConns, MaxIdleConnsPerHost: t.MaxIdleConnsPerHost, MaxConnsPerHost: t.MaxConnsPerHost, IdleConnTimeout: t.IdleConnTimeout, ResponseHeaderTimeout: t.ResponseHeaderTimeout, ExpectContinueTimeout: t.ExpectContinueTimeout, ProxyConnectHeader: t.ProxyConnectHeader.Clone(), GetProxyConnectHeader: t.GetProxyConnectHeader, MaxResponseHeaderBytes: t.MaxResponseHeaderBytes, ForceAttemptHTTP2: t.ForceAttemptHTTP2, WriteBufferSize: t.WriteBufferSize, ReadBufferSize: t.ReadBufferSize, } if t.TLSClientConfig != nil { t2.TLSClientConfig = t.TLSClientConfig.Clone() } if !t.tlsNextProtoWasNil { npm := map[string]func(authority string, c *tls.Conn) RoundTripper{} for k, v := range t.TLSNextProto { npm[k] = v } t2.TLSNextProto = npm } return t2 } // 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() } func (t *Transport) hasCustomTLSDialer() bool { return t.DialTLS != nil || t.DialTLSContext != nil } // onceSetNextProtoDefaults initializes TLSNextProto. // It must be called via t.nextProtoOnce.Do. func (t *Transport) onceSetNextProtoDefaults() { t.tlsNextProtoWasNil = (t.TLSNextProto == nil) if godebug.Get("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 "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 return } } } if t.TLSNextProto != nil { // This is the documented way to disable http2 on a // Transport. return } if !t.ForceAttemptHTTP2 && (t.TLSClientConfig != nil || t.Dial != nil || t.DialContext != nil || t.hasCustomTLSDialer()) { // 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. // However, if ForceAttemptHTTP2 is true, it overrides the above checks. return } if omitBundledHTTP2 { return } t2, err := http2configureTransports(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. // The schemes "http", "https", and "socks5" are supported. // 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 cancelKey cancelKey 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() } // useRegisteredProtocol reports whether an alternate protocol (as registered // with Transport.RegisterProtocol) should be respected for this request. func (t *Transport) useRegisteredProtocol(req *Request) bool { if req.URL.Scheme == "https" && req.requiresHTTP1() { // If this request requires HTTP/1, don't use the // "https" alternate protocol, which is used by the // HTTP/2 code to take over requests if there's an // existing cached HTTP/2 connection. return false } return true } // alternateRoundTripper returns the alternate RoundTripper to use // for this request if the Request's URL scheme requires one, // or nil for the normal case of using the Transport. func (t *Transport) alternateRoundTripper(req *Request) RoundTripper { if !t.useRegisteredProtocol(req) { return nil } altProto, _ := t.altProto.Load().(map[string]RoundTripper) return altProto[req.URL.Scheme] } // 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) { req.closeBody() return nil, fmt.Errorf("net/http: invalid header field name %q", k) } for _, v := range vv { if !httpguts.ValidHeaderFieldValue(v) { req.closeBody() // Don't include the value in the error, because it may be sensitive. return nil, fmt.Errorf("net/http: invalid header field value for %q", k) } } } } origReq := req cancelKey := cancelKey{origReq} req = setupRewindBody(req) if altRT := t.alternateRoundTripper(req); altRT != nil { if resp, err := altRT.RoundTrip(req); err != ErrSkipAltProtocol { return resp, err } var err error req, err = rewindBody(req) if err != nil { return nil, err } } if !isHTTP { req.closeBody() return nil, badStringError("unsupported protocol scheme", scheme) } if req.Method != "" && !validMethod(req.Method) { req.closeBody() 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, cancelKey: cancelKey} 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(cancelKey, nil) req.closeBody() return nil, err } var resp *Response if pconn.alt != nil { // HTTP/2 path. t.setReqCanceler(cancelKey, nil) // not cancelable with CancelRequest resp, err = pconn.alt.RoundTrip(req) } else { resp, err = pconn.roundTrip(treq) } if err == nil { resp.Request = origReq return resp, nil } // Failed. Clean up and determine whether to retry. if http2isNoCachedConnError(err) { if t.removeIdleConn(pconn) { t.decConnsPerHost(pconn.cacheKey) } } else if !pconn.shouldRetryRequest(req, err) { // Issue 16465: return underlying net.Conn.Read error from peek, // as we've historically done. if e, ok := err.(nothingWrittenError); ok { err = e.error } if e, ok := err.(transportReadFromServerError); ok { err = e.err } return nil, err } testHookRoundTripRetried() // Rewind the body if we're able to. req, err = rewindBody(req) if err != nil { return nil, err } } } var errCannotRewind = errors.New("net/http: cannot rewind body after connection loss") type readTrackingBody struct { io.ReadCloser didRead bool didClose bool } func (r *readTrackingBody) Read(data []byte) (int, error) { r.didRead = true return r.ReadCloser.Read(data) } func (r *readTrackingBody) Close() error { r.didClose = true return r.ReadCloser.Close() } // setupRewindBody returns a new request with a custom body wrapper // that can report whether the body needs rewinding. // This lets rewindBody avoid an error result when the request // does not have GetBody but the body hasn't been read at all yet. func setupRewindBody(req *Request) *Request { if req.Body == nil || req.Body == NoBody { return req } newReq := *req newReq.Body = &readTrackingBody{ReadCloser: req.Body} return &newReq } // rewindBody returns a new request with the body rewound. // It returns req unmodified if the body does not need rewinding. // rewindBody takes care of closing req.Body when appropriate // (in all cases except when rewindBody returns req unmodified). func rewindBody(req *Request) (rewound *Request, err error) { if req.Body == nil || req.Body == NoBody || (!req.Body.(*readTrackingBody).didRead && !req.Body.(*readTrackingBody).didClose) { return req, nil // nothing to rewind } if !req.Body.(*readTrackingBody).didClose { req.closeBody() } if req.GetBody == nil { return nil, errCannotRewind } body, err := req.GetBody() if err != nil { return nil, err } newReq := *req newReq.Body = &readTrackingBody{ReadCloser: body} return &newReq, nil } // 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.closeIdle = true // close newly idle connections 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(cancelKey{req}, errRequestCanceled) } // Cancel an in-flight request, recording the error value. // Returns whether the request was canceled. func (t *Transport) cancelRequest(key cancelKey, err error) bool { // This function must not return until the cancel func has completed. // See: https://golang.org/issue/34658 t.reqMu.Lock() defer t.reqMu.Unlock() cancel := t.reqCanceler[key] delete(t.reqCanceler, key) if cancel != nil { cancel(err) } return cancel != nil } // // 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) { cm.targetScheme = treq.URL.Scheme cm.targetAddr = canonicalAddr(treq.URL) if t.Proxy != nil { cm.proxyURL, err = t.Proxy(treq.Request) } cm.onlyH1 = treq.requiresHTTP1() 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") errCloseIdle = 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") // 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) Unwrap() error { return e.err } 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 } pconn.markReused() t.idleMu.Lock() defer t.idleMu.Unlock() // HTTP/2 (pconn.alt != nil) connections do not come out of the idle list, // because multiple goroutines can use them simultaneously. // If this is an HTTP/2 connection being “returned,” we're done. if pconn.alt != nil && t.idleLRU.m[pconn] != nil { return nil } // Deliver pconn to goroutine waiting for idle connection, if any. // (They may be actively dialing, but this conn is ready first. // Chrome calls this socket late binding. // See https://www.chromium.org/developers/design-documents/network-stack#TOC-Connection-Management.) key := pconn.cacheKey if q, ok := t.idleConnWait[key]; ok { done := false if pconn.alt == nil { // HTTP/1. // Loop over the waiting list until we find a w that isn't done already, and hand it pconn. for q.len() > 0 { w := q.popFront() if w.tryDeliver(pconn, nil) { done = true break } } } else { // HTTP/2. // Can hand the same pconn to everyone in the waiting list, // and we still won't be done: we want to put it in the idle // list unconditionally, for any future clients too. for q.len() > 0 { w := q.popFront() w.tryDeliver(pconn, nil) } } if q.len() == 0 { delete(t.idleConnWait, key) } else { t.idleConnWait[key] = q } if done { return nil } } if t.closeIdle { return errCloseIdle } 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) } // Set idle timer, but only for HTTP/1 (pconn.alt == nil). // The HTTP/2 implementation manages the idle timer itself // (see idleConnTimeout in h2_bundle.go). if t.IdleConnTimeout > 0 && pconn.alt == nil { if pconn.idleTimer != nil { pconn.idleTimer.Reset(t.IdleConnTimeout) } else { pconn.idleTimer = time.AfterFunc(t.IdleConnTimeout, pconn.closeConnIfStillIdle) } } pconn.idleAt = time.Now() return nil } // queueForIdleConn queues w to receive the next idle connection for w.cm. // As an optimization hint to the caller, queueForIdleConn reports whether // it successfully delivered an already-idle connection. func (t *Transport) queueForIdleConn(w *wantConn) (delivered bool) { if t.DisableKeepAlives { return false } t.idleMu.Lock() defer t.idleMu.Unlock() // Stop closing connections that become idle - we might want one. // (That is, undo the effect of t.CloseIdleConnections.) t.closeIdle = false if w == nil { // Happens in test hook. return false } // If IdleConnTimeout is set, calculate the oldest // persistConn.idleAt time we're willing to use a cached idle // conn. var oldTime time.Time if t.IdleConnTimeout > 0 { oldTime = time.Now().Add(-t.IdleConnTimeout) } // Look for most recently-used idle connection. if list, ok := t.idleConn[w.key]; ok { stop := false delivered := false for len(list) > 0 && !stop { pconn := list[len(list)-1] // See whether this connection has been idle too long, considering // only the wall time (the Round(0)), in case this is a laptop or VM // coming out of suspend with previously cached idle connections. tooOld := !oldTime.IsZero() && pconn.idleAt.Round(0).Before(oldTime) if tooOld { // Async cleanup. Launch in its own goroutine (as if a // time.AfterFunc called it); it acquires idleMu, which we're // holding, and does a synchronous net.Conn.Close. go pconn.closeConnIfStillIdle() } if pconn.isBroken() || tooOld { // If either persistConn.readLoop has marked the connection // broken, but Transport.removeIdleConn has not yet removed it // from the idle list, or if this persistConn is too old (it was // idle too long), then ignore it and look for another. In both // cases it's already in the process of being closed. list = list[:len(list)-1] continue } delivered = w.tryDeliver(pconn, nil) if delivered { if pconn.alt != nil { // HTTP/2: multiple clients can share pconn. // Leave it in the list. } else { // HTTP/1: only one client can use pconn. // Remove it from the list. t.idleLRU.remove(pconn) list = list[:len(list)-1] } } stop = true } if len(list) > 0 { t.idleConn[w.key] = list } else { delete(t.idleConn, w.key) } if stop { return delivered } } // Register to receive next connection that becomes idle. if t.idleConnWait == nil { t.idleConnWait = make(map[connectMethodKey]wantConnQueue) } q := t.idleConnWait[w.key] q.cleanFront() q.pushBack(w) t.idleConnWait[w.key] = q return false } // removeIdleConn marks pconn as dead. func (t *Transport) removeIdleConn(pconn *persistConn) bool { t.idleMu.Lock() defer t.idleMu.Unlock() return t.removeIdleConnLocked(pconn) } // t.idleMu must be held. func (t *Transport) removeIdleConnLocked(pconn *persistConn) bool { if pconn.idleTimer != nil { pconn.idleTimer.Stop() } t.idleLRU.remove(pconn) key := pconn.cacheKey pconns := t.idleConn[key] var removed bool switch len(pconns) { case 0: // Nothing case 1: if pconns[0] == pconn { delete(t.idleConn, key) removed = true } 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] removed = true break } } return removed } func (t *Transport) setReqCanceler(key cancelKey, fn func(error)) { t.reqMu.Lock() defer t.reqMu.Unlock() if t.reqCanceler == nil { t.reqCanceler = make(map[cancelKey]func(error)) } if fn != nil { t.reqCanceler[key] = fn } else { delete(t.reqCanceler, key) } } // 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(key cancelKey, fn func(error)) bool { t.reqMu.Lock() defer t.reqMu.Unlock() _, ok := t.reqCanceler[key] if !ok { return false } if fn != nil { t.reqCanceler[key] = fn } else { delete(t.reqCanceler, key) } 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) } // A wantConn records state about a wanted connection // (that is, an active call to getConn). // The conn may be gotten by dialing or by finding an idle connection, // or a cancellation may make the conn no longer wanted. // These three options are racing against each other and use // wantConn to coordinate and agree about the winning outcome. type wantConn struct { cm connectMethod key connectMethodKey // cm.key() ctx context.Context // context for dial ready chan struct{} // closed when pc, err pair is delivered // hooks for testing to know when dials are done // beforeDial is called in the getConn goroutine when the dial is queued. // afterDial is called when the dial is completed or canceled. beforeDial func() afterDial func() mu sync.Mutex // protects pc, err, close(ready) pc *persistConn err error } // waiting reports whether w is still waiting for an answer (connection or error). func (w *wantConn) waiting() bool { select { case <-w.ready: return false default: return true } } // tryDeliver attempts to deliver pc, err to w and reports whether it succeeded. func (w *wantConn) tryDeliver(pc *persistConn, err error) bool { w.mu.Lock() defer w.mu.Unlock() if w.pc != nil || w.err != nil { return false } w.pc = pc w.err = err if w.pc == nil && w.err == nil { panic("net/http: internal error: misuse of tryDeliver") } close(w.ready) return true } // cancel marks w as no longer wanting a result (for example, due to cancellation). // If a connection has been delivered already, cancel returns it with t.putOrCloseIdleConn. func (w *wantConn) cancel(t *Transport, err error) { w.mu.Lock() if w.pc == nil && w.err == nil { close(w.ready) // catch misbehavior in future delivery } pc := w.pc w.pc = nil w.err = err w.mu.Unlock() if pc != nil { t.putOrCloseIdleConn(pc) } } // A wantConnQueue is a queue of wantConns. type wantConnQueue struct { // This is a queue, not a deque. // It is split into two stages - head[headPos:] and tail. // popFront is trivial (headPos++) on the first stage, and // pushBack is trivial (append) on the second stage. // If the first stage is empty, popFront can swap the // first and second stages to remedy the situation. // // This two-stage split is analogous to the use of two lists // in Okasaki's purely functional queue but without the // overhead of reversing the list when swapping stages. head []*wantConn headPos int tail []*wantConn } // len returns the number of items in the queue. func (q *wantConnQueue) len() int { return len(q.head) - q.headPos + len(q.tail) } // pushBack adds w to the back of the queue. func (q *wantConnQueue) pushBack(w *wantConn) { q.tail = append(q.tail, w) } // popFront removes and returns the wantConn at the front of the queue. func (q *wantConnQueue) popFront() *wantConn { if q.headPos >= len(q.head) { if len(q.tail) == 0 { return nil } // Pick up tail as new head, clear tail. q.head, q.headPos, q.tail = q.tail, 0, q.head[:0] } w := q.head[q.headPos] q.head[q.headPos] = nil q.headPos++ return w } // peekFront returns the wantConn at the front of the queue without removing it. func (q *wantConnQueue) peekFront() *wantConn { if q.headPos < len(q.head) { return q.head[q.headPos] } if len(q.tail) > 0 { return q.tail[0] } return nil } // cleanFront pops any wantConns that are no longer waiting from the head of the // queue, reporting whether any were popped. func (q *wantConnQueue) cleanFront() (cleaned bool) { for { w := q.peekFront() if w == nil || w.waiting() { return cleaned } q.popFront() cleaned = true } } func (t *Transport) customDialTLS(ctx context.Context, network, addr string) (conn net.Conn, err error) { if t.DialTLSContext != nil { conn, err = t.DialTLSContext(ctx, network, addr) } else { conn, err = t.DialTLS(network, addr) } if conn == nil && err == nil { err = errors.New("net/http: Transport.DialTLS or DialTLSContext returned (nil, nil)") } return } // 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) (pc *persistConn, err error) { req := treq.Request trace := treq.trace ctx := req.Context() if trace != nil && trace.GetConn != nil { trace.GetConn(cm.addr()) } w := &wantConn{ cm: cm, key: cm.key(), ctx: ctx, ready: make(chan struct{}, 1), beforeDial: testHookPrePendingDial, afterDial: testHookPostPendingDial, } defer func() { if err != nil { w.cancel(t, err) } }() // Queue for idle connection. if delivered := t.queueForIdleConn(w); delivered { pc := w.pc // Trace only for HTTP/1. // HTTP/2 calls trace.GotConn itself. if pc.alt == nil && trace != nil && trace.GotConn != nil { trace.GotConn(pc.gotIdleConnTrace(pc.idleAt)) } // 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(treq.cancelKey, func(error) {}) return pc, nil } cancelc := make(chan error, 1) t.setReqCanceler(treq.cancelKey, func(err error) { cancelc <- err }) // Queue for permission to dial. t.queueForDial(w) // Wait for completion or cancellation. select { case <-w.ready: // Trace success but only for HTTP/1. // HTTP/2 calls trace.GotConn itself. if w.pc != nil && w.pc.alt == nil && trace != nil && trace.GotConn != nil { trace.GotConn(httptrace.GotConnInfo{Conn: w.pc.conn, Reused: w.pc.isReused()}) } if w.err != nil { // If the request has been canceled, that's probably // what caused w.err; if so, prefer to return the // cancellation error (see golang.org/issue/16049). select { 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 default: // return below } } return w.pc, w.err 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 } } // queueForDial queues w to wait for permission to begin dialing. // Once w receives permission to dial, it will do so in a separate goroutine. func (t *Transport) queueForDial(w *wantConn) { w.beforeDial() if t.MaxConnsPerHost <= 0 { go t.dialConnFor(w) return } t.connsPerHostMu.Lock() defer t.connsPerHostMu.Unlock() if n := t.connsPerHost[w.key]; n < t.MaxConnsPerHost { if t.connsPerHost == nil { t.connsPerHost = make(map[connectMethodKey]int) } t.connsPerHost[w.key] = n + 1 go t.dialConnFor(w) return } if t.connsPerHostWait == nil { t.connsPerHostWait = make(map[connectMethodKey]wantConnQueue) } q := t.connsPerHostWait[w.key] q.cleanFront() q.pushBack(w) t.connsPerHostWait[w.key] = q } // dialConnFor dials on behalf of w and delivers the result to w. // dialConnFor has received permission to dial w.cm and is counted in t.connCount[w.cm.key()]. // If the dial is canceled or unsuccessful, dialConnFor decrements t.connCount[w.cm.key()]. func (t *Transport) dialConnFor(w *wantConn) { defer w.afterDial() pc, err := t.dialConn(w.ctx, w.cm) delivered := w.tryDeliver(pc, err) if err == nil && (!delivered || pc.alt != nil) { // pconn was not passed to w, // or it is HTTP/2 and can be shared. // Add to the idle connection pool. t.putOrCloseIdleConn(pc) } if err != nil { t.decConnsPerHost(w.key) } } // decConnsPerHost decrements the per-host connection count for key, // which may in turn give a different waiting goroutine permission to dial. func (t *Transport) decConnsPerHost(key connectMethodKey) { if t.MaxConnsPerHost <= 0 { return } t.connsPerHostMu.Lock() defer t.connsPerHostMu.Unlock() n := t.connsPerHost[key] if n == 0 { // Shouldn't happen, but if it does, the counting is buggy and could // easily lead to a silent deadlock, so report the problem loudly. panic("net/http: internal error: connCount underflow") } // Can we hand this count to a goroutine still waiting to dial? // (Some goroutines on the wait list may have timed out or // gotten a connection another way. If they're all gone, // we don't want to kick off any spurious dial operations.) if q := t.connsPerHostWait[key]; q.len() > 0 { done := false for q.len() > 0 { w := q.popFront() if w.waiting() { go t.dialConnFor(w) done = true break } } if q.len() == 0 { delete(t.connsPerHostWait, key) } else { // q is a value (like a slice), so we have to store // the updated q back into the map. t.connsPerHostWait[key] = q } if done { return } } // Otherwise, decrement the recorded count. if n--; n == 0 { delete(t.connsPerHost, key) } else { t.connsPerHost[key] = n } } // 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(ctx context.Context, 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 } if pconn.cacheKey.onlyH1 { cfg.NextProtos = nil } 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.HandshakeContext(ctx) 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 } type erringRoundTripper interface { RoundTripErr() error } func (t *Transport) dialConn(ctx context.Context, cm connectMethod) (pconn *persistConn, err 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.hasCustomTLSDialer() { var err error pconn.conn, err = t.customDialTLS(ctx, "tcp", cm.addr()) if err != nil { return nil, wrapErr(err) } 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.HandshakeContext(ctx); 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, "tcp", 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(ctx, 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 var hdr Header if t.GetProxyConnectHeader != nil { var err error hdr, err = t.GetProxyConnectHeader(ctx, cm.proxyURL, cm.targetAddr) if err != nil { conn.Close() return nil, err } } else { hdr = t.ProxyConnectHeader } if hdr == nil { hdr = make(Header) } if pa := cm.proxyAuth(); pa != "" { hdr = hdr.Clone() hdr.Set("Proxy-Authorization", pa) } connectReq := &Request{ Method: "CONNECT", URL: &url.URL{Opaque: cm.targetAddr}, Host: cm.targetAddr, Header: hdr, } // If there's no done channel (no deadline or cancellation // from the caller possible), at least set some (long) // timeout here. This will make sure we don't block forever // and leak a goroutine if the connection stops replying // after the TCP connect. connectCtx := ctx if ctx.Done() == nil { newCtx, cancel := context.WithTimeout(ctx, 1*time.Minute) defer cancel() connectCtx = newCtx } didReadResponse := make(chan struct{}) // closed after CONNECT write+read is done or fails var ( resp *Response err error // write or read error ) // Write the CONNECT request & read the response. go func() { defer close(didReadResponse) err = connectReq.Write(conn) if err != nil { return } // 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) }() select { case <-connectCtx.Done(): conn.Close() <-didReadResponse return nil, connectCtx.Err() case <-didReadResponse: // resp or err now set } if err != nil { conn.Close() return nil, err } if resp.StatusCode != 200 { _, text, ok := strings.Cut(resp.Status, " ") conn.Close() if !ok { return nil, errors.New("unknown status code") } return nil, errors.New(text) } } if cm.proxyURL != nil && cm.targetScheme == "https" { if err := pconn.addTLS(ctx, 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 { alt := next(cm.targetAddr, pconn.conn.(*tls.Conn)) if e, ok := alt.(erringRoundTripper); ok { // pconn.conn was closed by next (http2configureTransports.upgradeFn). return nil, e.RoundTripErr() } return &persistConn{t: t, cacheKey: pconn.cacheKey, alt: alt}, nil } } pconn.br = bufio.NewReaderSize(pconn, t.readBufferSize()) pconn.bw = bufio.NewWriterSize(persistConnWriter{pconn}, t.writeBufferSize()) 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 } // ReadFrom exposes persistConnWriter's underlying Conn to io.Copy and if // the Conn implements io.ReaderFrom, it can take advantage of optimizations // such as sendfile. func (w persistConnWriter) ReadFrom(r io.Reader) (n int64, err error) { n, err = io.Copy(w.pc.conn, r) w.pc.nwrite += n return } var _ io.ReaderFrom = (*persistConnWriter)(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: // // connectMethod.key().String() Description // ------------------------------ ------------------------- // |http|foo.com http directly to server, no proxy // |https|foo.com https directly to server, no proxy // |https,h1|foo.com https directly to server w/o HTTP/2, 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 { _ incomparable 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 onlyH1 bool // whether to disable HTTP/2 and force HTTP/1 } 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, onlyH1: cm.onlyH1, } } // 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 onlyH1 bool } func (k connectMethodKey) String() string { // Only used by tests. var h1 string if k.onlyH1 { h1 = ",h1" } return fmt.Sprintf("%s|%s%s|%s", k.proxy, k.scheme, h1, 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 cancellation. func (pc *persistConn) canceled() error { pc.mu.Lock() defer pc.mu.Unlock() return pc.canceledErr } // isReused reports whether this connection has been used before. 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 } // Wait for the writeLoop goroutine to terminate to avoid data // races on callers who mutate the request on failure. // // When resc in pc.roundTrip and hence rc.ch receives a responseAndError // with a non-nil error it implies that the persistConn is either closed // or closing. Waiting on pc.writeLoopDone is hence safe as all callers // close closech which in turn ensures writeLoop returns. <-pc.writeLoopDone // 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 { if pc.nwrite == startBytesWritten { return nothingWrittenError{err} } // Don't decorate return err } if pc.isBroken() { if pc.nwrite == startBytesWritten { return nothingWrittenError{err} } return fmt.Errorf("net/http: HTTP/1.x transport connection broken: %v", err) } return err } // errCallerOwnsConn is an internal sentinel error used when we hand // off a writable response.Body to the caller. We use this to prevent // closing a net.Conn that is now owned by the caller. var errCallerOwnsConn = errors.New("read loop ending; caller owns writable underlying conn") 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 // effectively no limit for response bodies pc.mu.Lock() pc.numExpectedResponses-- pc.mu.Unlock() bodyWritable := resp.bodyIsWritable() hasBody := rc.req.Method != "HEAD" && resp.ContentLength != 0 if resp.Close || rc.req.Close || resp.StatusCode <= 199 || bodyWritable { // 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 || bodyWritable { replaced := pc.t.replaceReqCanceler(rc.cancelKey, 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. alive = alive && !pc.sawEOF && pc.wroteRequest() && replaced && tryPutIdleConn(trace) if bodyWritable { closeErr = errCallerOwnsConn } 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 && ascii.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 cancellation or death) select { case bodyEOF := <-waitForBodyRead: replaced := pc.t.replaceReqCanceler(rc.cancelKey, nil) // before pc might return to idle pool alive = alive && bodyEOF && !pc.sawEOF && pc.wroteRequest() && replaced && 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.cancelKey, 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) if is408Message(buf) { pc.closeLocked(errServerClosedIdle) return } else { 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)) } } // is408Message reports whether buf has the prefix of an // HTTP 408 Request Timeout response. // See golang.org/issue/32310. func is408Message(buf []byte) bool { if len(buf) < len("HTTP/1.x 408") { return false } if string(buf[:7]) != "HTTP/1." { return false } return string(buf[8:12]) == " 408" } // 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 } if resp.isProtocolSwitch() { resp.Body = newReadWriteCloserBody(pc.br, pc.conn) } 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 } } } func newReadWriteCloserBody(br *bufio.Reader, rwc io.ReadWriteCloser) io.ReadWriteCloser { body := &readWriteCloserBody{ReadWriteCloser: rwc} if br.Buffered() != 0 { body.br = br } return body } // readWriteCloserBody is the Response.Body type used when we want to // give users write access to the Body through the underlying // connection (TCP, unless using custom dialers). This is then // the concrete type for a Response.Body on the 101 Switching // Protocols response, as used by WebSockets, h2c, etc. type readWriteCloserBody struct { _ incomparable br *bufio.Reader // used until empty io.ReadWriteCloser } func (b *readWriteCloserBody) Read(p []byte) (n int, err error) { if b.br != nil { if n := b.br.Buffered(); len(p) > n { p = p[:n] } n, err = b.br.Read(p) if b.br.Buffered() == 0 { b.br = nil } return n, err } return b.ReadWriteCloser.Read(p) } // 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 down // connections and causes other // errors. wr.req.setError(err) } if err == nil { err = pc.bw.Flush() } if err != nil { 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. t := time.NewTimer(maxWriteWaitBeforeConnReuse) defer t.Stop() select { case err := <-pc.writeErrCh: return err == nil case <-t.C: return false } } } // responseAndError is how the goroutine reading from an HTTP/1 server // communicates with the goroutine doing the RoundTrip. type responseAndError struct { _ incomparable res *Response // else use this response (see res method) err error } type requestAndChan struct { _ incomparable req *Request cancelKey cancelKey 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 caller'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} // errRequestCanceled is set to be identical to the one from h2 to facilitate // testing. var errRequestCanceled = http2errRequestCanceled 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.cancelKey, 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: https://zlib.net/zlib_faq.html#faq39 // // 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.wantsClose() && !isProtocolSwitchHeader(req.Header) { req.extraHeaders().Set("Connection", "close") } gone := make(chan struct{}) defer close(gone) defer func() { if err != nil { pc.t.setReqCanceler(req.cancelKey, 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, cancelKey: req.cancelKey, ch: resc, addedGzip: requestedGzip, continueCh: continueCh, callerGone: gone, } var respHeaderTimer <-chan time.Time cancelChan := req.Request.Cancel ctxDoneChan := req.Context().Done() pcClosed := pc.closech canceled := false 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 <-pcClosed: pcClosed = nil if canceled || pc.t.replaceReqCanceler(req.cancelKey, nil) { 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: canceled = pc.t.cancelRequest(req.cancelKey, errRequestCanceled) cancelChan = nil case <-ctxDoneChan: canceled = pc.t.cancelRequest(req.cancelKey, 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 ...any) { if logf, ok := tr.Request.Context().Value(tLogKey{}).(func(string, ...any)); 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 pc.t.decConnsPerHost(pc.cacheKey) // Close HTTP/1 (pc.alt == nil) connection. // HTTP/2 closes its connection itself. if pc.alt == nil { if err != errCallerOwnsConn { 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 { _ incomparable 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 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() {} // cloneTLSConfig 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) }