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// Copyright 2009 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. See RFC 7230 through 7235.
//
// This is the high-level Client interface.
// The low-level implementation is in transport.go.
package http
import (
"crypto/tls"
"encoding/base64"
"errors"
"fmt"
"io"
"io/ioutil"
"log"
"net/url"
"sort"
"strings"
"sync"
"time"
)
// A Client is an HTTP client. Its zero value (DefaultClient) is a
// usable client that uses DefaultTransport.
//
// The Client's Transport typically has internal state (cached TCP
// connections), so Clients should be reused instead of created as
// needed. Clients are safe for concurrent use by multiple goroutines.
//
// A Client is higher-level than a RoundTripper (such as Transport)
// and additionally handles HTTP details such as cookies and
// redirects.
//
// When following redirects, the Client will forward all headers set on the
// initial Request except:
//
// • when forwarding sensitive headers like "Authorization",
// "WWW-Authenticate", and "Cookie" to untrusted targets.
// These headers will be ignored when following a redirect to a domain
// that is not a subdomain match or exact match of the initial domain.
// For example, a redirect from "foo.com" to either "foo.com" or "sub.foo.com"
// will forward the sensitive headers, but a redirect to "bar.com" will not.
//
// • when forwarding the "Cookie" header with a non-nil cookie Jar.
// Since each redirect may mutate the state of the cookie jar,
// a redirect may possibly alter a cookie set in the initial request.
// When forwarding the "Cookie" header, any mutated cookies will be omitted,
// with the expectation that the Jar will insert those mutated cookies
// with the updated values (assuming the origin matches).
// If Jar is nil, the initial cookies are forwarded without change.
//
type Client struct {
// Transport specifies the mechanism by which individual
// HTTP requests are made.
// If nil, DefaultTransport is used.
Transport RoundTripper
// CheckRedirect specifies the policy for handling redirects.
// If CheckRedirect is not nil, the client calls it before
// following an HTTP redirect. The arguments req and via are
// the upcoming request and the requests made already, oldest
// first. If CheckRedirect returns an error, the Client's Get
// method returns both the previous Response (with its Body
// closed) and CheckRedirect's error (wrapped in a url.Error)
// instead of issuing the Request req.
// As a special case, if CheckRedirect returns ErrUseLastResponse,
// then the most recent response is returned with its body
// unclosed, along with a nil error.
//
// If CheckRedirect is nil, the Client uses its default policy,
// which is to stop after 10 consecutive requests.
CheckRedirect func(req *Request, via []*Request) error
// Jar specifies the cookie jar.
//
// The Jar is used to insert relevant cookies into every
// outbound Request and is updated with the cookie values
// of every inbound Response. The Jar is consulted for every
// redirect that the Client follows.
//
// If Jar is nil, cookies are only sent if they are explicitly
// set on the Request.
Jar CookieJar
// Timeout specifies a time limit for requests made by this
// Client. The timeout includes connection time, any
// redirects, and reading the response body. The timer remains
// running after Get, Head, Post, or Do return and will
// interrupt reading of the Response.Body.
//
// A Timeout of zero means no timeout.
//
// The Client cancels requests to the underlying Transport
// as if the Request's Context ended.
//
// For compatibility, the Client will also use the deprecated
// CancelRequest method on Transport if found. New
// RoundTripper implementations should use the Request's Context
// for cancellation instead of implementing CancelRequest.
Timeout time.Duration
}
// DefaultClient is the default Client and is used by Get, Head, and Post.
var DefaultClient = &Client{}
// RoundTripper is an interface representing the ability to execute a
// single HTTP transaction, obtaining the Response for a given Request.
//
// A RoundTripper must be safe for concurrent use by multiple
// goroutines.
type RoundTripper interface {
// RoundTrip executes a single HTTP transaction, returning
// a Response for the provided Request.
//
// RoundTrip should not attempt to interpret the response. In
// particular, RoundTrip must return err == nil if it obtained
// a response, regardless of the response's HTTP status code.
// A non-nil err should be reserved for failure to obtain a
// response. Similarly, RoundTrip should not attempt to
// handle higher-level protocol details such as redirects,
// authentication, or cookies.
//
// RoundTrip should not modify the request, except for
// consuming and closing the Request's Body. RoundTrip may
// read fields of the request in a separate goroutine. Callers
// should not mutate or reuse the request until the Response's
// Body has been closed.
//
// RoundTrip must always close the body, including on errors,
// but depending on the implementation may do so in a separate
// goroutine even after RoundTrip returns. This means that
// callers wanting to reuse the body for subsequent requests
// must arrange to wait for the Close call before doing so.
//
// The Request's URL and Header fields must be initialized.
RoundTrip(*Request) (*Response, error)
}
// refererForURL returns a referer without any authentication info or
// an empty string if lastReq scheme is https and newReq scheme is http.
func refererForURL(lastReq, newReq *url.URL) string {
// https://tools.ietf.org/html/rfc7231#section-5.5.2
// "Clients SHOULD NOT include a Referer header field in a
// (non-secure) HTTP request if the referring page was
// transferred with a secure protocol."
if lastReq.Scheme == "https" && newReq.Scheme == "http" {
return ""
}
referer := lastReq.String()
if lastReq.User != nil {
// This is not very efficient, but is the best we can
// do without:
// - introducing a new method on URL
// - creating a race condition
// - copying the URL struct manually, which would cause
// maintenance problems down the line
auth := lastReq.User.String() + "@"
referer = strings.Replace(referer, auth, "", 1)
}
return referer
}
// didTimeout is non-nil only if err != nil.
func (c *Client) send(req *Request, deadline time.Time) (resp *Response, didTimeout func() bool, err error) {
if c.Jar != nil {
for _, cookie := range c.Jar.Cookies(req.URL) {
req.AddCookie(cookie)
}
}
resp, didTimeout, err = send(req, c.transport(), deadline)
if err != nil {
return nil, didTimeout, err
}
if c.Jar != nil {
if rc := resp.Cookies(); len(rc) > 0 {
c.Jar.SetCookies(req.URL, rc)
}
}
return resp, nil, nil
}
func (c *Client) deadline() time.Time {
if c.Timeout > 0 {
return time.Now().Add(c.Timeout)
}
return time.Time{}
}
func (c *Client) transport() RoundTripper {
if c.Transport != nil {
return c.Transport
}
return DefaultTransport
}
// send issues an HTTP request.
// Caller should close resp.Body when done reading from it.
func send(ireq *Request, rt RoundTripper, deadline time.Time) (resp *Response, didTimeout func() bool, err error) {
req := ireq // req is either the original request, or a modified fork
if rt == nil {
req.closeBody()
return nil, alwaysFalse, errors.New("http: no Client.Transport or DefaultTransport")
}
if req.URL == nil {
req.closeBody()
return nil, alwaysFalse, errors.New("http: nil Request.URL")
}
if req.RequestURI != "" {
req.closeBody()
return nil, alwaysFalse, errors.New("http: Request.RequestURI can't be set in client requests.")
}
// forkReq forks req into a shallow clone of ireq the first
// time it's called.
forkReq := func() {
if ireq == req {
req = new(Request)
*req = *ireq // shallow clone
}
}
// Most the callers of send (Get, Post, et al) don't need
// Headers, leaving it uninitialized. We guarantee to the
// Transport that this has been initialized, though.
if req.Header == nil {
forkReq()
req.Header = make(Header)
}
if u := req.URL.User; u != nil && req.Header.Get("Authorization") == "" {
username := u.Username()
password, _ := u.Password()
forkReq()
req.Header = ireq.Header.Clone()
req.Header.Set("Authorization", "Basic "+basicAuth(username, password))
}
if !deadline.IsZero() {
forkReq()
}
stopTimer, didTimeout := setRequestCancel(req, rt, deadline)
resp, err = rt.RoundTrip(req)
if err != nil {
stopTimer()
if resp != nil {
log.Printf("RoundTripper returned a response & error; ignoring response")
}
if tlsErr, ok := err.(tls.RecordHeaderError); ok {
// If we get a bad TLS record header, check to see if the
// response looks like HTTP and give a more helpful error.
// See golang.org/issue/11111.
if string(tlsErr.RecordHeader[:]) == "HTTP/" {
err = errors.New("http: server gave HTTP response to HTTPS client")
}
}
return nil, didTimeout, err
}
if !deadline.IsZero() {
resp.Body = &cancelTimerBody{
stop: stopTimer,
rc: resp.Body,
reqDidTimeout: didTimeout,
}
}
return resp, nil, nil
}
// setRequestCancel sets the Cancel field of req, if deadline is
// non-zero. The RoundTripper's type is used to determine whether the legacy
// CancelRequest behavior should be used.
//
// As background, there are three ways to cancel a request:
// First was Transport.CancelRequest. (deprecated)
// Second was Request.Cancel (this mechanism).
// Third was Request.Context.
func setRequestCancel(req *Request, rt RoundTripper, deadline time.Time) (stopTimer func(), didTimeout func() bool) {
if deadline.IsZero() {
return nop, alwaysFalse
}
initialReqCancel := req.Cancel // the user's original Request.Cancel, if any
cancel := make(chan struct{})
req.Cancel = cancel
doCancel := func() {
// The newer way (the second way in the func comment):
close(cancel)
// The legacy compatibility way, used only
// for RoundTripper implementations written
// before Go 1.5 or Go 1.6.
type canceler interface {
CancelRequest(*Request)
}
switch v := rt.(type) {
case *Transport, *http2Transport:
// Do nothing. The net/http package's transports
// support the new Request.Cancel channel
case canceler:
v.CancelRequest(req)
}
}
stopTimerCh := make(chan struct{})
var once sync.Once
stopTimer = func() { once.Do(func() { close(stopTimerCh) }) }
timer := time.NewTimer(time.Until(deadline))
var timedOut atomicBool
go func() {
select {
case <-initialReqCancel:
doCancel()
timer.Stop()
case <-timer.C:
timedOut.setTrue()
doCancel()
case <-stopTimerCh:
timer.Stop()
}
}()
return stopTimer, timedOut.isSet
}
// See 2 (end of page 4) https://www.ietf.org/rfc/rfc2617.txt
// "To receive authorization, the client sends the userid and password,
// separated by a single colon (":") character, within a base64
// encoded string in the credentials."
// It is not meant to be urlencoded.
func basicAuth(username, password string) string {
auth := username + ":" + password
return base64.StdEncoding.EncodeToString([]byte(auth))
}
// Get issues a GET to the specified URL. If the response is one of
// the following redirect codes, Get follows the redirect, up to a
// maximum of 10 redirects:
//
// 301 (Moved Permanently)
// 302 (Found)
// 303 (See Other)
// 307 (Temporary Redirect)
// 308 (Permanent Redirect)
//
// An error is returned if there were too many redirects or if there
// was an HTTP protocol error. A non-2xx response doesn't cause an
// error. Any returned error will be of type *url.Error. The url.Error
// value's Timeout method will report true if request timed out or was
// canceled.
//
// When err is nil, resp always contains a non-nil resp.Body.
// Caller should close resp.Body when done reading from it.
//
// Get is a wrapper around DefaultClient.Get.
//
// To make a request with custom headers, use NewRequest and
// DefaultClient.Do.
func Get(url string) (resp *Response, err error) {
return DefaultClient.Get(url)
}
// Get issues a GET to the specified URL. If the response is one of the
// following redirect codes, Get follows the redirect after calling the
// Client's CheckRedirect function:
//
// 301 (Moved Permanently)
// 302 (Found)
// 303 (See Other)
// 307 (Temporary Redirect)
// 308 (Permanent Redirect)
//
// An error is returned if the Client's CheckRedirect function fails
// or if there was an HTTP protocol error. A non-2xx response doesn't
// cause an error. Any returned error will be of type *url.Error. The
// url.Error value's Timeout method will report true if request timed
// out or was canceled.
//
// When err is nil, resp always contains a non-nil resp.Body.
// Caller should close resp.Body when done reading from it.
//
// To make a request with custom headers, use NewRequest and Client.Do.
func (c *Client) Get(url string) (resp *Response, err error) {
req, err := NewRequest("GET", url, nil)
if err != nil {
return nil, err
}
return c.Do(req)
}
func alwaysFalse() bool { return false }
// ErrUseLastResponse can be returned by Client.CheckRedirect hooks to
// control how redirects are processed. If returned, the next request
// is not sent and the most recent response is returned with its body
// unclosed.
var ErrUseLastResponse = errors.New("net/http: use last response")
// checkRedirect calls either the user's configured CheckRedirect
// function, or the default.
func (c *Client) checkRedirect(req *Request, via []*Request) error {
fn := c.CheckRedirect
if fn == nil {
fn = defaultCheckRedirect
}
return fn(req, via)
}
// redirectBehavior describes what should happen when the
// client encounters a 3xx status code from the server
func redirectBehavior(reqMethod string, resp *Response, ireq *Request) (redirectMethod string, shouldRedirect, includeBody bool) {
switch resp.StatusCode {
case 301, 302, 303:
redirectMethod = reqMethod
shouldRedirect = true
includeBody = false
// RFC 2616 allowed automatic redirection only with GET and
// HEAD requests. RFC 7231 lifts this restriction, but we still
// restrict other methods to GET to maintain compatibility.
// See Issue 18570.
if reqMethod != "GET" && reqMethod != "HEAD" {
redirectMethod = "GET"
}
case 307, 308:
redirectMethod = reqMethod
shouldRedirect = true
includeBody = true
// Treat 307 and 308 specially, since they're new in
// Go 1.8, and they also require re-sending the request body.
if resp.Header.Get("Location") == "" {
// 308s have been observed in the wild being served
// without Location headers. Since Go 1.7 and earlier
// didn't follow these codes, just stop here instead
// of returning an error.
// See Issue 17773.
shouldRedirect = false
break
}
if ireq.GetBody == nil && ireq.outgoingLength() != 0 {
// We had a request body, and 307/308 require
// re-sending it, but GetBody is not defined. So just
// return this response to the user instead of an
// error, like we did in Go 1.7 and earlier.
shouldRedirect = false
}
}
return redirectMethod, shouldRedirect, includeBody
}
// urlErrorOp returns the (*url.Error).Op value to use for the
// provided (*Request).Method value.
func urlErrorOp(method string) string {
if method == "" {
return "Get"
}
return method[:1] + strings.ToLower(method[1:])
}
// Do sends an HTTP request and returns an HTTP response, following
// policy (such as redirects, cookies, auth) as configured on the
// client.
//
// An error is returned if caused by client policy (such as
// CheckRedirect), or failure to speak HTTP (such as a network
// connectivity problem). A non-2xx status code doesn't cause an
// error.
//
// If the returned error is nil, the Response will contain a non-nil
// Body which the user is expected to close. If the Body is not both
// read to EOF and closed, the Client's underlying RoundTripper
// (typically Transport) may not be able to re-use a persistent TCP
// connection to the server for a subsequent "keep-alive" request.
//
// The request Body, if non-nil, will be closed by the underlying
// Transport, even on errors.
//
// On error, any Response can be ignored. A non-nil Response with a
// non-nil error only occurs when CheckRedirect fails, and even then
// the returned Response.Body is already closed.
//
// Generally Get, Post, or PostForm will be used instead of Do.
//
// If the server replies with a redirect, the Client first uses the
// CheckRedirect function to determine whether the redirect should be
// followed. If permitted, a 301, 302, or 303 redirect causes
// subsequent requests to use HTTP method GET
// (or HEAD if the original request was HEAD), with no body.
// A 307 or 308 redirect preserves the original HTTP method and body,
// provided that the Request.GetBody function is defined.
// The NewRequest function automatically sets GetBody for common
// standard library body types.
//
// Any returned error will be of type *url.Error. The url.Error
// value's Timeout method will report true if request timed out or was
// canceled.
func (c *Client) Do(req *Request) (*Response, error) {
return c.do(req)
}
var testHookClientDoResult func(retres *Response, reterr error)
func (c *Client) do(req *Request) (retres *Response, reterr error) {
if testHookClientDoResult != nil {
defer func() { testHookClientDoResult(retres, reterr) }()
}
if req.URL == nil {
req.closeBody()
return nil, &url.Error{
Op: urlErrorOp(req.Method),
Err: errors.New("http: nil Request.URL"),
}
}
var (
deadline = c.deadline()
reqs []*Request
resp *Response
copyHeaders = c.makeHeadersCopier(req)
reqBodyClosed = false // have we closed the current req.Body?
// Redirect behavior:
redirectMethod string
includeBody bool
)
uerr := func(err error) error {
// the body may have been closed already by c.send()
if !reqBodyClosed {
req.closeBody()
}
var urlStr string
if resp != nil && resp.Request != nil {
urlStr = stripPassword(resp.Request.URL)
} else {
urlStr = stripPassword(req.URL)
}
return &url.Error{
Op: urlErrorOp(reqs[0].Method),
URL: urlStr,
Err: err,
}
}
for {
// For all but the first request, create the next
// request hop and replace req.
if len(reqs) > 0 {
loc := resp.Header.Get("Location")
if loc == "" {
resp.closeBody()
return nil, uerr(fmt.Errorf("%d response missing Location header", resp.StatusCode))
}
u, err := req.URL.Parse(loc)
if err != nil {
resp.closeBody()
return nil, uerr(fmt.Errorf("failed to parse Location header %q: %v", loc, err))
}
host := ""
if req.Host != "" && req.Host != req.URL.Host {
// If the caller specified a custom Host header and the
// redirect location is relative, preserve the Host header
// through the redirect. See issue #22233.
if u, _ := url.Parse(loc); u != nil && !u.IsAbs() {
host = req.Host
}
}
ireq := reqs[0]
req = &Request{
Method: redirectMethod,
Response: resp,
URL: u,
Header: make(Header),
Host: host,
Cancel: ireq.Cancel,
ctx: ireq.ctx,
}
if includeBody && ireq.GetBody != nil {
req.Body, err = ireq.GetBody()
if err != nil {
resp.closeBody()
return nil, uerr(err)
}
req.ContentLength = ireq.ContentLength
}
// Copy original headers before setting the Referer,
// in case the user set Referer on their first request.
// If they really want to override, they can do it in
// their CheckRedirect func.
copyHeaders(req)
// Add the Referer header from the most recent
// request URL to the new one, if it's not https->http:
if ref := refererForURL(reqs[len(reqs)-1].URL, req.URL); ref != "" {
req.Header.Set("Referer", ref)
}
err = c.checkRedirect(req, reqs)
// Sentinel error to let users select the
// previous response, without closing its
// body. See Issue 10069.
if err == ErrUseLastResponse {
return resp, nil
}
// Close the previous response's body. But
// read at least some of the body so if it's
// small the underlying TCP connection will be
// re-used. No need to check for errors: if it
// fails, the Transport won't reuse it anyway.
const maxBodySlurpSize = 2 << 10
if resp.ContentLength == -1 || resp.ContentLength <= maxBodySlurpSize {
io.CopyN(ioutil.Discard, resp.Body, maxBodySlurpSize)
}
resp.Body.Close()
if err != nil {
// Special case for Go 1 compatibility: return both the response
// and an error if the CheckRedirect function failed.
// See https://golang.org/issue/3795
// The resp.Body has already been closed.
ue := uerr(err)
ue.(*url.Error).URL = loc
return resp, ue
}
}
reqs = append(reqs, req)
var err error
var didTimeout func() bool
if resp, didTimeout, err = c.send(req, deadline); err != nil {
// c.send() always closes req.Body
reqBodyClosed = true
if !deadline.IsZero() && didTimeout() {
err = &httpError{
// TODO: early in cycle: s/Client.Timeout exceeded/timeout or context cancellation/
err: err.Error() + " (Client.Timeout exceeded while awaiting headers)",
timeout: true,
}
}
return nil, uerr(err)
}
var shouldRedirect bool
redirectMethod, shouldRedirect, includeBody = redirectBehavior(req.Method, resp, reqs[0])
if !shouldRedirect {
return resp, nil
}
req.closeBody()
}
}
// makeHeadersCopier makes a function that copies headers from the
// initial Request, ireq. For every redirect, this function must be called
// so that it can copy headers into the upcoming Request.
func (c *Client) makeHeadersCopier(ireq *Request) func(*Request) {
// The headers to copy are from the very initial request.
// We use a closured callback to keep a reference to these original headers.
var (
ireqhdr = ireq.Header.Clone()
icookies map[string][]*Cookie
)
if c.Jar != nil && ireq.Header.Get("Cookie") != "" {
icookies = make(map[string][]*Cookie)
for _, c := range ireq.Cookies() {
icookies[c.Name] = append(icookies[c.Name], c)
}
}
preq := ireq // The previous request
return func(req *Request) {
// If Jar is present and there was some initial cookies provided
// via the request header, then we may need to alter the initial
// cookies as we follow redirects since each redirect may end up
// modifying a pre-existing cookie.
//
// Since cookies already set in the request header do not contain
// information about the original domain and path, the logic below
// assumes any new set cookies override the original cookie
// regardless of domain or path.
//
// See https://golang.org/issue/17494
if c.Jar != nil && icookies != nil {
var changed bool
resp := req.Response // The response that caused the upcoming redirect
for _, c := range resp.Cookies() {
if _, ok := icookies[c.Name]; ok {
delete(icookies, c.Name)
changed = true
}
}
if changed {
ireqhdr.Del("Cookie")
var ss []string
for _, cs := range icookies {
for _, c := range cs {
ss = append(ss, c.Name+"="+c.Value)
}
}
sort.Strings(ss) // Ensure deterministic headers
ireqhdr.Set("Cookie", strings.Join(ss, "; "))
}
}
// Copy the initial request's Header values
// (at least the safe ones).
for k, vv := range ireqhdr {
if shouldCopyHeaderOnRedirect(k, preq.URL, req.URL) {
req.Header[k] = vv
}
}
preq = req // Update previous Request with the current request
}
}
func defaultCheckRedirect(req *Request, via []*Request) error {
if len(via) >= 10 {
return errors.New("stopped after 10 redirects")
}
return nil
}
// Post issues a POST to the specified URL.
//
// Caller should close resp.Body when done reading from it.
//
// If the provided body is an io.Closer, it is closed after the
// request.
//
// Post is a wrapper around DefaultClient.Post.
//
// To set custom headers, use NewRequest and DefaultClient.Do.
//
// See the Client.Do method documentation for details on how redirects
// are handled.
func Post(url, contentType string, body io.Reader) (resp *Response, err error) {
return DefaultClient.Post(url, contentType, body)
}
// Post issues a POST to the specified URL.
//
// Caller should close resp.Body when done reading from it.
//
// If the provided body is an io.Closer, it is closed after the
// request.
//
// To set custom headers, use NewRequest and Client.Do.
//
// See the Client.Do method documentation for details on how redirects
// are handled.
func (c *Client) Post(url, contentType string, body io.Reader) (resp *Response, err error) {
req, err := NewRequest("POST", url, body)
if err != nil {
return nil, err
}
req.Header.Set("Content-Type", contentType)
return c.Do(req)
}
// PostForm issues a POST to the specified URL, with data's keys and
// values URL-encoded as the request body.
//
// The Content-Type header is set to application/x-www-form-urlencoded.
// To set other headers, use NewRequest and DefaultClient.Do.
//
// When err is nil, resp always contains a non-nil resp.Body.
// Caller should close resp.Body when done reading from it.
//
// PostForm is a wrapper around DefaultClient.PostForm.
//
// See the Client.Do method documentation for details on how redirects
// are handled.
func PostForm(url string, data url.Values) (resp *Response, err error) {
return DefaultClient.PostForm(url, data)
}
// PostForm issues a POST to the specified URL,
// with data's keys and values URL-encoded as the request body.
//
// The Content-Type header is set to application/x-www-form-urlencoded.
// To set other headers, use NewRequest and Client.Do.
//
// When err is nil, resp always contains a non-nil resp.Body.
// Caller should close resp.Body when done reading from it.
//
// See the Client.Do method documentation for details on how redirects
// are handled.
func (c *Client) PostForm(url string, data url.Values) (resp *Response, err error) {
return c.Post(url, "application/x-www-form-urlencoded", strings.NewReader(data.Encode()))
}
// Head issues a HEAD to the specified URL. If the response is one of
// the following redirect codes, Head follows the redirect, up to a
// maximum of 10 redirects:
//
// 301 (Moved Permanently)
// 302 (Found)
// 303 (See Other)
// 307 (Temporary Redirect)
// 308 (Permanent Redirect)
//
// Head is a wrapper around DefaultClient.Head
func Head(url string) (resp *Response, err error) {
return DefaultClient.Head(url)
}
// Head issues a HEAD to the specified URL. If the response is one of the
// following redirect codes, Head follows the redirect after calling the
// Client's CheckRedirect function:
//
// 301 (Moved Permanently)
// 302 (Found)
// 303 (See Other)
// 307 (Temporary Redirect)
// 308 (Permanent Redirect)
func (c *Client) Head(url string) (resp *Response, err error) {
req, err := NewRequest("HEAD", url, nil)
if err != nil {
return nil, err
}
return c.Do(req)
}
// CloseIdleConnections closes any connections on its Transport 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.
//
// If the Client's Transport does not have a CloseIdleConnections method
// then this method does nothing.
func (c *Client) CloseIdleConnections() {
type closeIdler interface {
CloseIdleConnections()
}
if tr, ok := c.transport().(closeIdler); ok {
tr.CloseIdleConnections()
}
}
// cancelTimerBody is an io.ReadCloser that wraps rc with two features:
// 1) on Read error or close, the stop func is called.
// 2) On Read failure, if reqDidTimeout is true, the error is wrapped and
// marked as net.Error that hit its timeout.
type cancelTimerBody struct {
stop func() // stops the time.Timer waiting to cancel the request
rc io.ReadCloser
reqDidTimeout func() bool
}
func (b *cancelTimerBody) Read(p []byte) (n int, err error) {
n, err = b.rc.Read(p)
if err == nil {
return n, nil
}
b.stop()
if err == io.EOF {
return n, err
}
if b.reqDidTimeout() {
err = &httpError{
// TODO: early in cycle: s/Client.Timeout exceeded/timeout or context cancellation/
err: err.Error() + " (Client.Timeout exceeded while reading body)",
timeout: true,
}
}
return n, err
}
func (b *cancelTimerBody) Close() error {
err := b.rc.Close()
b.stop()
return err
}
func shouldCopyHeaderOnRedirect(headerKey string, initial, dest *url.URL) bool {
switch CanonicalHeaderKey(headerKey) {
case "Authorization", "Www-Authenticate", "Cookie", "Cookie2":
// Permit sending auth/cookie headers from "foo.com"
// to "sub.foo.com".
// Note that we don't send all cookies to subdomains
// automatically. This function is only used for
// Cookies set explicitly on the initial outgoing
// client request. Cookies automatically added via the
// CookieJar mechanism continue to follow each
// cookie's scope as set by Set-Cookie. But for
// outgoing requests with the Cookie header set
// directly, we don't know their scope, so we assume
// it's for *.domain.com.
ihost := canonicalAddr(initial)
dhost := canonicalAddr(dest)
return isDomainOrSubdomain(dhost, ihost)
}
// All other headers are copied:
return true
}
// isDomainOrSubdomain reports whether sub is a subdomain (or exact
// match) of the parent domain.
//
// Both domains must already be in canonical form.
func isDomainOrSubdomain(sub, parent string) bool {
if sub == parent {
return true
}
// If sub is "foo.example.com" and parent is "example.com",
// that means sub must end in "."+parent.
// Do it without allocating.
if !strings.HasSuffix(sub, parent) {
return false
}
return sub[len(sub)-len(parent)-1] == '.'
}
func stripPassword(u *url.URL) string {
_, passSet := u.User.Password()
if passSet {
return strings.Replace(u.String(), u.User.String()+"@", u.User.Username()+":***@", 1)
}
return u.String()
}
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