1 // Copyright 2009 The Go Authors. All rights reserved.
2 // Use of this source code is governed by a BSD-style
3 // license that can be found in the LICENSE file.
5 // HTTP client. See RFC 7230 through 7235.
7 // This is the high-level Client interface.
8 // The low-level implementation is in transport.go.
27 // A Client is an HTTP client. Its zero value (DefaultClient) is a
28 // usable client that uses DefaultTransport.
30 // The Client's Transport typically has internal state (cached TCP
31 // connections), so Clients should be reused instead of created as
32 // needed. Clients are safe for concurrent use by multiple goroutines.
34 // A Client is higher-level than a RoundTripper (such as Transport)
35 // and additionally handles HTTP details such as cookies and
38 // When following redirects, the Client will forward all headers set on the
39 // initial Request except:
41 // • when forwarding sensitive headers like "Authorization",
42 // "WWW-Authenticate", and "Cookie" to untrusted targets.
43 // These headers will be ignored when following a redirect to a domain
44 // that is not a subdomain match or exact match of the initial domain.
45 // For example, a redirect from "foo.com" to either "foo.com" or "sub.foo.com"
46 // will forward the sensitive headers, but a redirect to "bar.com" will not.
48 // • when forwarding the "Cookie" header with a non-nil cookie Jar.
49 // Since each redirect may mutate the state of the cookie jar,
50 // a redirect may possibly alter a cookie set in the initial request.
51 // When forwarding the "Cookie" header, any mutated cookies will be omitted,
52 // with the expectation that the Jar will insert those mutated cookies
53 // with the updated values (assuming the origin matches).
54 // If Jar is nil, the initial cookies are forwarded without change.
57 // Transport specifies the mechanism by which individual
58 // HTTP requests are made.
59 // If nil, DefaultTransport is used.
60 Transport RoundTripper
62 // CheckRedirect specifies the policy for handling redirects.
63 // If CheckRedirect is not nil, the client calls it before
64 // following an HTTP redirect. The arguments req and via are
65 // the upcoming request and the requests made already, oldest
66 // first. If CheckRedirect returns an error, the Client's Get
67 // method returns both the previous Response (with its Body
68 // closed) and CheckRedirect's error (wrapped in a url.Error)
69 // instead of issuing the Request req.
70 // As a special case, if CheckRedirect returns ErrUseLastResponse,
71 // then the most recent response is returned with its body
72 // unclosed, along with a nil error.
74 // If CheckRedirect is nil, the Client uses its default policy,
75 // which is to stop after 10 consecutive requests.
76 CheckRedirect
func(req
*Request
, via
[]*Request
) error
78 // Jar specifies the cookie jar.
80 // The Jar is used to insert relevant cookies into every
81 // outbound Request and is updated with the cookie values
82 // of every inbound Response. The Jar is consulted for every
83 // redirect that the Client follows.
85 // If Jar is nil, cookies are only sent if they are explicitly
86 // set on the Request.
89 // Timeout specifies a time limit for requests made by this
90 // Client. The timeout includes connection time, any
91 // redirects, and reading the response body. The timer remains
92 // running after Get, Head, Post, or Do return and will
93 // interrupt reading of the Response.Body.
95 // A Timeout of zero means no timeout.
97 // The Client cancels requests to the underlying Transport
98 // as if the Request's Context ended.
100 // For compatibility, the Client will also use the deprecated
101 // CancelRequest method on Transport if found. New
102 // RoundTripper implementations should use the Request's Context
103 // for cancelation instead of implementing CancelRequest.
104 Timeout time
.Duration
107 // DefaultClient is the default Client and is used by Get, Head, and Post.
108 var DefaultClient
= &Client
{}
110 // RoundTripper is an interface representing the ability to execute a
111 // single HTTP transaction, obtaining the Response for a given Request.
113 // A RoundTripper must be safe for concurrent use by multiple
115 type RoundTripper
interface {
116 // RoundTrip executes a single HTTP transaction, returning
117 // a Response for the provided Request.
119 // RoundTrip should not attempt to interpret the response. In
120 // particular, RoundTrip must return err == nil if it obtained
121 // a response, regardless of the response's HTTP status code.
122 // A non-nil err should be reserved for failure to obtain a
123 // response. Similarly, RoundTrip should not attempt to
124 // handle higher-level protocol details such as redirects,
125 // authentication, or cookies.
127 // RoundTrip should not modify the request, except for
128 // consuming and closing the Request's Body. RoundTrip may
129 // read fields of the request in a separate goroutine. Callers
130 // should not mutate or reuse the request until the Response's
131 // Body has been closed.
133 // RoundTrip must always close the body, including on errors,
134 // but depending on the implementation may do so in a separate
135 // goroutine even after RoundTrip returns. This means that
136 // callers wanting to reuse the body for subsequent requests
137 // must arrange to wait for the Close call before doing so.
139 // The Request's URL and Header fields must be initialized.
140 RoundTrip(*Request
) (*Response
, error
)
143 // refererForURL returns a referer without any authentication info or
144 // an empty string if lastReq scheme is https and newReq scheme is http.
145 func refererForURL(lastReq
, newReq
*url
.URL
) string {
146 // https://tools.ietf.org/html/rfc7231#section-5.5.2
147 // "Clients SHOULD NOT include a Referer header field in a
148 // (non-secure) HTTP request if the referring page was
149 // transferred with a secure protocol."
150 if lastReq
.Scheme
== "https" && newReq
.Scheme
== "http" {
153 referer
:= lastReq
.String()
154 if lastReq
.User
!= nil {
155 // This is not very efficient, but is the best we can
157 // - introducing a new method on URL
158 // - creating a race condition
159 // - copying the URL struct manually, which would cause
160 // maintenance problems down the line
161 auth
:= lastReq
.User
.String() + "@"
162 referer
= strings
.Replace(referer
, auth
, "", 1)
167 // didTimeout is non-nil only if err != nil.
168 func (c
*Client
) send(req
*Request
, deadline time
.Time
) (resp
*Response
, didTimeout
func() bool, err error
) {
170 for _
, cookie
:= range c
.Jar
.Cookies(req
.URL
) {
171 req
.AddCookie(cookie
)
174 resp
, didTimeout
, err
= send(req
, c
.transport(), deadline
)
176 return nil, didTimeout
, err
179 if rc
:= resp
.Cookies(); len(rc
) > 0 {
180 c
.Jar
.SetCookies(req
.URL
, rc
)
183 return resp
, nil, nil
186 func (c
*Client
) deadline() time
.Time
{
188 return time
.Now().Add(c
.Timeout
)
193 func (c
*Client
) transport() RoundTripper
{
194 if c
.Transport
!= nil {
197 return DefaultTransport
200 // send issues an HTTP request.
201 // Caller should close resp.Body when done reading from it.
202 func send(ireq
*Request
, rt RoundTripper
, deadline time
.Time
) (resp
*Response
, didTimeout
func() bool, err error
) {
203 req
:= ireq
// req is either the original request, or a modified fork
207 return nil, alwaysFalse
, errors
.New("http: no Client.Transport or DefaultTransport")
212 return nil, alwaysFalse
, errors
.New("http: nil Request.URL")
215 if req
.RequestURI
!= "" {
217 return nil, alwaysFalse
, errors
.New("http: Request.RequestURI can't be set in client requests.")
220 // forkReq forks req into a shallow clone of ireq the first
225 *req
= *ireq
// shallow clone
229 // Most the callers of send (Get, Post, et al) don't need
230 // Headers, leaving it uninitialized. We guarantee to the
231 // Transport that this has been initialized, though.
232 if req
.Header
== nil {
234 req
.Header
= make(Header
)
237 if u
:= req
.URL
.User
; u
!= nil && req
.Header
.Get("Authorization") == "" {
238 username
:= u
.Username()
239 password
, _
:= u
.Password()
241 req
.Header
= cloneHeader(ireq
.Header
)
242 req
.Header
.Set("Authorization", "Basic "+basicAuth(username
, password
))
245 if !deadline
.IsZero() {
248 stopTimer
, didTimeout
:= setRequestCancel(req
, rt
, deadline
)
250 resp
, err
= rt
.RoundTrip(req
)
254 log
.Printf("RoundTripper returned a response & error; ignoring response")
256 if tlsErr
, ok
:= err
.(tls
.RecordHeaderError
); ok
{
257 // If we get a bad TLS record header, check to see if the
258 // response looks like HTTP and give a more helpful error.
259 // See golang.org/issue/11111.
260 if string(tlsErr
.RecordHeader
[:]) == "HTTP/" {
261 err
= errors
.New("http: server gave HTTP response to HTTPS client")
264 return nil, didTimeout
, err
266 if !deadline
.IsZero() {
267 resp
.Body
= &cancelTimerBody
{
270 reqDidTimeout
: didTimeout
,
273 return resp
, nil, nil
276 // setRequestCancel sets the Cancel field of req, if deadline is
277 // non-zero. The RoundTripper's type is used to determine whether the legacy
278 // CancelRequest behavior should be used.
280 // As background, there are three ways to cancel a request:
281 // First was Transport.CancelRequest. (deprecated)
282 // Second was Request.Cancel (this mechanism).
283 // Third was Request.Context.
284 func setRequestCancel(req
*Request
, rt RoundTripper
, deadline time
.Time
) (stopTimer
func(), didTimeout
func() bool) {
285 if deadline
.IsZero() {
286 return nop
, alwaysFalse
289 initialReqCancel
:= req
.Cancel
// the user's original Request.Cancel, if any
291 cancel
:= make(chan struct{})
295 // The newer way (the second way in the func comment):
298 // The legacy compatibility way, used only
299 // for RoundTripper implementations written
300 // before Go 1.5 or Go 1.6.
301 type canceler
interface {
302 CancelRequest(*Request
)
304 switch v
:= rt
.(type) {
305 case *Transport
, *http2Transport
:
306 // Do nothing. The net/http package's transports
307 // support the new Request.Cancel channel
313 stopTimerCh
:= make(chan struct{})
315 stopTimer
= func() { once
.Do(func() { close(stopTimerCh
) }) }
317 timer
:= time
.NewTimer(time
.Until(deadline
))
318 var timedOut atomicBool
322 case <-initialReqCancel
:
333 return stopTimer
, timedOut
.isSet
336 // See 2 (end of page 4) https://www.ietf.org/rfc/rfc2617.txt
337 // "To receive authorization, the client sends the userid and password,
338 // separated by a single colon (":") character, within a base64
339 // encoded string in the credentials."
340 // It is not meant to be urlencoded.
341 func basicAuth(username
, password
string) string {
342 auth
:= username
+ ":" + password
343 return base64
.StdEncoding
.EncodeToString([]byte(auth
))
346 // Get issues a GET to the specified URL. If the response is one of
347 // the following redirect codes, Get follows the redirect, up to a
348 // maximum of 10 redirects:
350 // 301 (Moved Permanently)
353 // 307 (Temporary Redirect)
354 // 308 (Permanent Redirect)
356 // An error is returned if there were too many redirects or if there
357 // was an HTTP protocol error. A non-2xx response doesn't cause an
358 // error. Any returned error will be of type *url.Error. The url.Error
359 // value's Timeout method will report true if request timed out or was
362 // When err is nil, resp always contains a non-nil resp.Body.
363 // Caller should close resp.Body when done reading from it.
365 // Get is a wrapper around DefaultClient.Get.
367 // To make a request with custom headers, use NewRequest and
369 func Get(url
string) (resp
*Response
, err error
) {
370 return DefaultClient
.Get(url
)
373 // Get issues a GET to the specified URL. If the response is one of the
374 // following redirect codes, Get follows the redirect after calling the
375 // Client's CheckRedirect function:
377 // 301 (Moved Permanently)
380 // 307 (Temporary Redirect)
381 // 308 (Permanent Redirect)
383 // An error is returned if the Client's CheckRedirect function fails
384 // or if there was an HTTP protocol error. A non-2xx response doesn't
385 // cause an error. Any returned error will be of type *url.Error. The
386 // url.Error value's Timeout method will report true if request timed
387 // out or was canceled.
389 // When err is nil, resp always contains a non-nil resp.Body.
390 // Caller should close resp.Body when done reading from it.
392 // To make a request with custom headers, use NewRequest and Client.Do.
393 func (c
*Client
) Get(url
string) (resp
*Response
, err error
) {
394 req
, err
:= NewRequest("GET", url
, nil)
401 func alwaysFalse() bool { return false }
403 // ErrUseLastResponse can be returned by Client.CheckRedirect hooks to
404 // control how redirects are processed. If returned, the next request
405 // is not sent and the most recent response is returned with its body
407 var ErrUseLastResponse
= errors
.New("net/http: use last response")
409 // checkRedirect calls either the user's configured CheckRedirect
410 // function, or the default.
411 func (c
*Client
) checkRedirect(req
*Request
, via
[]*Request
) error
{
412 fn
:= c
.CheckRedirect
414 fn
= defaultCheckRedirect
419 // redirectBehavior describes what should happen when the
420 // client encounters a 3xx status code from the server
421 func redirectBehavior(reqMethod
string, resp
*Response
, ireq
*Request
) (redirectMethod
string, shouldRedirect
, includeBody
bool) {
422 switch resp
.StatusCode
{
424 redirectMethod
= reqMethod
425 shouldRedirect
= true
428 // RFC 2616 allowed automatic redirection only with GET and
429 // HEAD requests. RFC 7231 lifts this restriction, but we still
430 // restrict other methods to GET to maintain compatibility.
432 if reqMethod
!= "GET" && reqMethod
!= "HEAD" {
433 redirectMethod
= "GET"
436 redirectMethod
= reqMethod
437 shouldRedirect
= true
440 // Treat 307 and 308 specially, since they're new in
441 // Go 1.8, and they also require re-sending the request body.
442 if resp
.Header
.Get("Location") == "" {
443 // 308s have been observed in the wild being served
444 // without Location headers. Since Go 1.7 and earlier
445 // didn't follow these codes, just stop here instead
446 // of returning an error.
448 shouldRedirect
= false
451 if ireq
.GetBody
== nil && ireq
.outgoingLength() != 0 {
452 // We had a request body, and 307/308 require
453 // re-sending it, but GetBody is not defined. So just
454 // return this response to the user instead of an
455 // error, like we did in Go 1.7 and earlier.
456 shouldRedirect
= false
459 return redirectMethod
, shouldRedirect
, includeBody
462 // urlErrorOp returns the (*url.Error).Op value to use for the
463 // provided (*Request).Method value.
464 func urlErrorOp(method
string) string {
468 return method
[:1] + strings
.ToLower(method
[1:])
471 // Do sends an HTTP request and returns an HTTP response, following
472 // policy (such as redirects, cookies, auth) as configured on the
475 // An error is returned if caused by client policy (such as
476 // CheckRedirect), or failure to speak HTTP (such as a network
477 // connectivity problem). A non-2xx status code doesn't cause an
480 // If the returned error is nil, the Response will contain a non-nil
481 // Body which the user is expected to close. If the Body is not
482 // closed, the Client's underlying RoundTripper (typically Transport)
483 // may not be able to re-use a persistent TCP connection to the server
484 // for a subsequent "keep-alive" request.
486 // The request Body, if non-nil, will be closed by the underlying
487 // Transport, even on errors.
489 // On error, any Response can be ignored. A non-nil Response with a
490 // non-nil error only occurs when CheckRedirect fails, and even then
491 // the returned Response.Body is already closed.
493 // Generally Get, Post, or PostForm will be used instead of Do.
495 // If the server replies with a redirect, the Client first uses the
496 // CheckRedirect function to determine whether the redirect should be
497 // followed. If permitted, a 301, 302, or 303 redirect causes
498 // subsequent requests to use HTTP method GET
499 // (or HEAD if the original request was HEAD), with no body.
500 // A 307 or 308 redirect preserves the original HTTP method and body,
501 // provided that the Request.GetBody function is defined.
502 // The NewRequest function automatically sets GetBody for common
503 // standard library body types.
505 // Any returned error will be of type *url.Error. The url.Error
506 // value's Timeout method will report true if request timed out or was
508 func (c
*Client
) Do(req
*Request
) (*Response
, error
) {
512 var testHookClientDoResult
func(retres
*Response
, reterr error
)
514 func (c
*Client
) do(req
*Request
) (retres
*Response
, reterr error
) {
515 if testHookClientDoResult
!= nil {
516 defer func() { testHookClientDoResult(retres
, reterr
) }()
520 return nil, &url
.Error
{
521 Op
: urlErrorOp(req
.Method
),
522 Err
: errors
.New("http: nil Request.URL"),
527 deadline
= c
.deadline()
530 copyHeaders
= c
.makeHeadersCopier(req
)
531 reqBodyClosed
= false // have we closed the current req.Body?
533 // Redirect behavior:
534 redirectMethod
string
537 uerr
:= func(err error
) error
{
538 // the body may have been closed already by c.send()
543 if resp
!= nil && resp
.Request
!= nil {
544 urlStr
= stripPassword(resp
.Request
.URL
)
546 urlStr
= stripPassword(req
.URL
)
549 Op
: urlErrorOp(reqs
[0].Method
),
555 // For all but the first request, create the next
556 // request hop and replace req.
558 loc
:= resp
.Header
.Get("Location")
561 return nil, uerr(fmt
.Errorf("%d response missing Location header", resp
.StatusCode
))
563 u
, err
:= req
.URL
.Parse(loc
)
566 return nil, uerr(fmt
.Errorf("failed to parse Location header %q: %v", loc
, err
))
569 if req
.Host
!= "" && req
.Host
!= req
.URL
.Host
{
570 // If the caller specified a custom Host header and the
571 // redirect location is relative, preserve the Host header
572 // through the redirect. See issue #22233.
573 if u
, _
:= url
.Parse(loc
); u
!= nil && !u
.IsAbs() {
579 Method
: redirectMethod
,
582 Header
: make(Header
),
587 if includeBody
&& ireq
.GetBody
!= nil {
588 req
.Body
, err
= ireq
.GetBody()
591 return nil, uerr(err
)
593 req
.ContentLength
= ireq
.ContentLength
596 // Copy original headers before setting the Referer,
597 // in case the user set Referer on their first request.
598 // If they really want to override, they can do it in
599 // their CheckRedirect func.
602 // Add the Referer header from the most recent
603 // request URL to the new one, if it's not https->http:
604 if ref
:= refererForURL(reqs
[len(reqs
)-1].URL
, req
.URL
); ref
!= "" {
605 req
.Header
.Set("Referer", ref
)
607 err
= c
.checkRedirect(req
, reqs
)
609 // Sentinel error to let users select the
610 // previous response, without closing its
611 // body. See Issue 10069.
612 if err
== ErrUseLastResponse
{
616 // Close the previous response's body. But
617 // read at least some of the body so if it's
618 // small the underlying TCP connection will be
619 // re-used. No need to check for errors: if it
620 // fails, the Transport won't reuse it anyway.
621 const maxBodySlurpSize
= 2 << 10
622 if resp
.ContentLength
== -1 || resp
.ContentLength
<= maxBodySlurpSize
{
623 io
.CopyN(ioutil
.Discard
, resp
.Body
, maxBodySlurpSize
)
628 // Special case for Go 1 compatibility: return both the response
629 // and an error if the CheckRedirect function failed.
630 // See https://golang.org/issue/3795
631 // The resp.Body has already been closed.
633 ue
.(*url
.Error
).URL
= loc
638 reqs
= append(reqs
, req
)
640 var didTimeout
func() bool
641 if resp
, didTimeout
, err
= c
.send(req
, deadline
); err
!= nil {
642 // c.send() always closes req.Body
644 if !deadline
.IsZero() && didTimeout() {
646 // TODO: early in cycle: s/Client.Timeout exceeded/timeout or context cancelation/
647 err
: err
.Error() + " (Client.Timeout exceeded while awaiting headers)",
651 return nil, uerr(err
)
654 var shouldRedirect
bool
655 redirectMethod
, shouldRedirect
, includeBody
= redirectBehavior(req
.Method
, resp
, reqs
[0])
664 // makeHeadersCopier makes a function that copies headers from the
665 // initial Request, ireq. For every redirect, this function must be called
666 // so that it can copy headers into the upcoming Request.
667 func (c
*Client
) makeHeadersCopier(ireq
*Request
) func(*Request
) {
668 // The headers to copy are from the very initial request.
669 // We use a closured callback to keep a reference to these original headers.
671 ireqhdr
= ireq
.Header
.clone()
672 icookies
map[string][]*Cookie
674 if c
.Jar
!= nil && ireq
.Header
.Get("Cookie") != "" {
675 icookies
= make(map[string][]*Cookie
)
676 for _
, c
:= range ireq
.Cookies() {
677 icookies
[c
.Name
] = append(icookies
[c
.Name
], c
)
681 preq
:= ireq
// The previous request
682 return func(req
*Request
) {
683 // If Jar is present and there was some initial cookies provided
684 // via the request header, then we may need to alter the initial
685 // cookies as we follow redirects since each redirect may end up
686 // modifying a pre-existing cookie.
688 // Since cookies already set in the request header do not contain
689 // information about the original domain and path, the logic below
690 // assumes any new set cookies override the original cookie
691 // regardless of domain or path.
693 // See https://golang.org/issue/17494
694 if c
.Jar
!= nil && icookies
!= nil {
696 resp
:= req
.Response
// The response that caused the upcoming redirect
697 for _
, c
:= range resp
.Cookies() {
698 if _
, ok
:= icookies
[c
.Name
]; ok
{
699 delete(icookies
, c
.Name
)
704 ireqhdr
.Del("Cookie")
706 for _
, cs
:= range icookies
{
707 for _
, c
:= range cs
{
708 ss
= append(ss
, c
.Name
+"="+c
.Value
)
711 sort
.Strings(ss
) // Ensure deterministic headers
712 ireqhdr
.Set("Cookie", strings
.Join(ss
, "; "))
716 // Copy the initial request's Header values
717 // (at least the safe ones).
718 for k
, vv
:= range ireqhdr
{
719 if shouldCopyHeaderOnRedirect(k
, preq
.URL
, req
.URL
) {
724 preq
= req
// Update previous Request with the current request
728 func defaultCheckRedirect(req
*Request
, via
[]*Request
) error
{
730 return errors
.New("stopped after 10 redirects")
735 // Post issues a POST to the specified URL.
737 // Caller should close resp.Body when done reading from it.
739 // If the provided body is an io.Closer, it is closed after the
742 // Post is a wrapper around DefaultClient.Post.
744 // To set custom headers, use NewRequest and DefaultClient.Do.
746 // See the Client.Do method documentation for details on how redirects
748 func Post(url
, contentType
string, body io
.Reader
) (resp
*Response
, err error
) {
749 return DefaultClient
.Post(url
, contentType
, body
)
752 // Post issues a POST to the specified URL.
754 // Caller should close resp.Body when done reading from it.
756 // If the provided body is an io.Closer, it is closed after the
759 // To set custom headers, use NewRequest and Client.Do.
761 // See the Client.Do method documentation for details on how redirects
763 func (c
*Client
) Post(url
, contentType
string, body io
.Reader
) (resp
*Response
, err error
) {
764 req
, err
:= NewRequest("POST", url
, body
)
768 req
.Header
.Set("Content-Type", contentType
)
772 // PostForm issues a POST to the specified URL, with data's keys and
773 // values URL-encoded as the request body.
775 // The Content-Type header is set to application/x-www-form-urlencoded.
776 // To set other headers, use NewRequest and DefaultClient.Do.
778 // When err is nil, resp always contains a non-nil resp.Body.
779 // Caller should close resp.Body when done reading from it.
781 // PostForm is a wrapper around DefaultClient.PostForm.
783 // See the Client.Do method documentation for details on how redirects
785 func PostForm(url
string, data url
.Values
) (resp
*Response
, err error
) {
786 return DefaultClient
.PostForm(url
, data
)
789 // PostForm issues a POST to the specified URL,
790 // with data's keys and values URL-encoded as the request body.
792 // The Content-Type header is set to application/x-www-form-urlencoded.
793 // To set other headers, use NewRequest and Client.Do.
795 // When err is nil, resp always contains a non-nil resp.Body.
796 // Caller should close resp.Body when done reading from it.
798 // See the Client.Do method documentation for details on how redirects
800 func (c
*Client
) PostForm(url
string, data url
.Values
) (resp
*Response
, err error
) {
801 return c
.Post(url
, "application/x-www-form-urlencoded", strings
.NewReader(data
.Encode()))
804 // Head issues a HEAD to the specified URL. If the response is one of
805 // the following redirect codes, Head follows the redirect, up to a
806 // maximum of 10 redirects:
808 // 301 (Moved Permanently)
811 // 307 (Temporary Redirect)
812 // 308 (Permanent Redirect)
814 // Head is a wrapper around DefaultClient.Head
815 func Head(url
string) (resp
*Response
, err error
) {
816 return DefaultClient
.Head(url
)
819 // Head issues a HEAD to the specified URL. If the response is one of the
820 // following redirect codes, Head follows the redirect after calling the
821 // Client's CheckRedirect function:
823 // 301 (Moved Permanently)
826 // 307 (Temporary Redirect)
827 // 308 (Permanent Redirect)
828 func (c
*Client
) Head(url
string) (resp
*Response
, err error
) {
829 req
, err
:= NewRequest("HEAD", url
, nil)
836 // cancelTimerBody is an io.ReadCloser that wraps rc with two features:
837 // 1) on Read error or close, the stop func is called.
838 // 2) On Read failure, if reqDidTimeout is true, the error is wrapped and
839 // marked as net.Error that hit its timeout.
840 type cancelTimerBody
struct {
841 stop
func() // stops the time.Timer waiting to cancel the request
843 reqDidTimeout
func() bool
846 func (b
*cancelTimerBody
) Read(p
[]byte) (n
int, err error
) {
847 n
, err
= b
.rc
.Read(p
)
855 if b
.reqDidTimeout() {
857 // TODO: early in cycle: s/Client.Timeout exceeded/timeout or context cancelation/
858 err
: err
.Error() + " (Client.Timeout exceeded while reading body)",
865 func (b
*cancelTimerBody
) Close() error
{
871 func shouldCopyHeaderOnRedirect(headerKey
string, initial
, dest
*url
.URL
) bool {
872 switch CanonicalHeaderKey(headerKey
) {
873 case "Authorization", "Www-Authenticate", "Cookie", "Cookie2":
874 // Permit sending auth/cookie headers from "foo.com"
877 // Note that we don't send all cookies to subdomains
878 // automatically. This function is only used for
879 // Cookies set explicitly on the initial outgoing
880 // client request. Cookies automatically added via the
881 // CookieJar mechanism continue to follow each
882 // cookie's scope as set by Set-Cookie. But for
883 // outgoing requests with the Cookie header set
884 // directly, we don't know their scope, so we assume
885 // it's for *.domain.com.
887 ihost
:= canonicalAddr(initial
)
888 dhost
:= canonicalAddr(dest
)
889 return isDomainOrSubdomain(dhost
, ihost
)
891 // All other headers are copied:
895 // isDomainOrSubdomain reports whether sub is a subdomain (or exact
896 // match) of the parent domain.
898 // Both domains must already be in canonical form.
899 func isDomainOrSubdomain(sub
, parent
string) bool {
903 // If sub is "foo.example.com" and parent is "example.com",
904 // that means sub must end in "."+parent.
905 // Do it without allocating.
906 if !strings
.HasSuffix(sub
, parent
) {
909 return sub
[len(sub
)-len(parent
)-1] == '.'
912 func stripPassword(u
*url
.URL
) string {
913 pass
, passSet
:= u
.User
.Password()
915 return strings
.Replace(u
.String(), pass
+"@", "***@", 1)