/core/http/client.go
Go | 487 lines | 261 code | 45 blank | 181 comment | 77 complexity | b9da6019dae0f383e352816e29f33071 MD5 | raw file
- // 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 2616.
- //
- // This is the high-level Client interface.
- // The low-level implementation is in transport.go.
- package http
- import (
- "encoding/base64"
- "errors"
- "fmt"
- "io"
- "io/ioutil"
- "log"
- "net/url"
- "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.
- 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 and
- // CheckRedirect's error (wrapped in a url.Error) instead of
- // issuing the Request req.
- //
- // 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.
- // If Jar is nil, cookies are not sent in requests and ignored
- // in responses.
- 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's Transport must support the CancelRequest
- // method or Client will return errors when attempting to make
- // a request with Get, Head, Post, or Do. Client's default
- // Transport (DefaultTransport) supports 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
- // the Response for the request req. 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 Body, including on errors. The
- // request's URL and Header fields are guaranteed to be
- // initialized.
- RoundTrip(*Request) (*Response, error)
- }
- // Given a string of the form "host", "host:port", or "[ipv6::address]:port",
- // return true if the string includes a port.
- func hasPort(s string) bool { return strings.LastIndex(s, ":") > strings.LastIndex(s, "]") }
- // Used in Send to implement io.ReadCloser by bundling together the
- // bufio.Reader through which we read the response, and the underlying
- // network connection.
- type readClose struct {
- io.Reader
- io.Closer
- }
- func (c *Client) send(req *Request) (*Response, error) {
- if c.Jar != nil {
- for _, cookie := range c.Jar.Cookies(req.URL) {
- req.AddCookie(cookie)
- }
- }
- resp, err := send(req, c.transport())
- if err != nil {
- return nil, err
- }
- if c.Jar != nil {
- if rc := resp.Cookies(); len(rc) > 0 {
- c.Jar.SetCookies(req.URL, rc)
- }
- }
- return resp, err
- }
- // Do sends an HTTP request and returns an HTTP response, following
- // policy (e.g. redirects, cookies, auth) as configured on the client.
- //
- // An error is returned if caused by client policy (such as
- // CheckRedirect), or if there was an HTTP protocol error.
- // A non-2xx response doesn't cause an error.
- //
- // When err is nil, resp always contains a non-nil resp.Body.
- //
- // Callers should close resp.Body when done reading from it. If
- // resp.Body is not 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.
- //
- // Generally Get, Post, or PostForm will be used instead of Do.
- func (c *Client) Do(req *Request) (resp *Response, err error) {
- if req.Method == "GET" || req.Method == "HEAD" {
- return c.doFollowingRedirects(req, shouldRedirectGet)
- }
- if req.Method == "POST" || req.Method == "PUT" {
- return c.doFollowingRedirects(req, shouldRedirectPost)
- }
- return c.send(req)
- }
- 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(req *Request, t RoundTripper) (resp *Response, err error) {
- if t == nil {
- req.closeBody()
- return nil, errors.New("http: no Client.Transport or DefaultTransport")
- }
- if req.URL == nil {
- req.closeBody()
- return nil, errors.New("http: nil Request.URL")
- }
- if req.RequestURI != "" {
- req.closeBody()
- return nil, errors.New("http: Request.RequestURI can't be set in client requests.")
- }
- // 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 {
- req.Header = make(Header)
- }
- if u := req.URL.User; u != nil {
- username := u.Username()
- password, _ := u.Password()
- req.Header.Set("Authorization", "Basic "+basicAuth(username, password))
- }
- resp, err = t.RoundTrip(req)
- if err != nil {
- if resp != nil {
- log.Printf("RoundTripper returned a response & error; ignoring response")
- }
- return nil, err
- }
- return resp, nil
- }
- // See 2 (end of page 4) http://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))
- }
- // True if the specified HTTP status code is one for which the Get utility should
- // automatically redirect.
- func shouldRedirectGet(statusCode int) bool {
- switch statusCode {
- case StatusMovedPermanently, StatusFound, StatusSeeOther, StatusTemporaryRedirect:
- return true
- }
- return false
- }
- // True if the specified HTTP status code is one for which the Post utility should
- // automatically redirect.
- func shouldRedirectPost(statusCode int) bool {
- switch statusCode {
- case StatusFound, StatusSeeOther:
- return true
- }
- return false
- }
- // 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)
- //
- // 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.
- //
- // 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.
- 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)
- //
- // 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.
- //
- // When err is nil, resp always contains a non-nil resp.Body.
- // Caller should close resp.Body when done reading from it.
- func (c *Client) Get(url string) (resp *Response, err error) {
- req, err := NewRequest("GET", url, nil)
- if err != nil {
- return nil, err
- }
- return c.doFollowingRedirects(req, shouldRedirectGet)
- }
- func (c *Client) doFollowingRedirects(ireq *Request, shouldRedirect func(int) bool) (resp *Response, err error) {
- var base *url.URL
- redirectChecker := c.CheckRedirect
- if redirectChecker == nil {
- redirectChecker = defaultCheckRedirect
- }
- var via []*Request
- if ireq.URL == nil {
- ireq.closeBody()
- return nil, errors.New("http: nil Request.URL")
- }
- var reqmu sync.Mutex // guards req
- req := ireq
- var timer *time.Timer
- if c.Timeout > 0 {
- type canceler interface {
- CancelRequest(*Request)
- }
- tr, ok := c.transport().(canceler)
- if !ok {
- return nil, fmt.Errorf("net/http: Client Transport of type %T doesn't support CancelRequest; Timeout not supported", c.transport())
- }
- timer = time.AfterFunc(c.Timeout, func() {
- reqmu.Lock()
- defer reqmu.Unlock()
- tr.CancelRequest(req)
- })
- }
- urlStr := "" // next relative or absolute URL to fetch (after first request)
- redirectFailed := false
- for redirect := 0; ; redirect++ {
- if redirect != 0 {
- nreq := new(Request)
- nreq.Method = ireq.Method
- if ireq.Method == "POST" || ireq.Method == "PUT" {
- nreq.Method = "GET"
- }
- nreq.Header = make(Header)
- nreq.URL, err = base.Parse(urlStr)
- if err != nil {
- break
- }
- if len(via) > 0 {
- // Add the Referer header.
- lastReq := via[len(via)-1]
- if lastReq.URL.Scheme != "https" {
- nreq.Header.Set("Referer", lastReq.URL.String())
- }
- err = redirectChecker(nreq, via)
- if err != nil {
- redirectFailed = true
- break
- }
- }
- reqmu.Lock()
- req = nreq
- reqmu.Unlock()
- }
- urlStr = req.URL.String()
- if resp, err = c.send(req); err != nil {
- break
- }
- if shouldRedirect(resp.StatusCode) {
- // Read the body if small so underlying TCP connection will be re-used.
- // No need to check for errors: if it fails, 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 urlStr = resp.Header.Get("Location"); urlStr == "" {
- err = errors.New(fmt.Sprintf("%d response missing Location header", resp.StatusCode))
- break
- }
- base = req.URL
- via = append(via, req)
- continue
- }
- if timer != nil {
- resp.Body = &cancelTimerBody{timer, resp.Body}
- }
- return resp, nil
- }
- method := ireq.Method
- urlErr := &url.Error{
- Op: method[0:1] + strings.ToLower(method[1:]),
- URL: urlStr,
- Err: err,
- }
- if redirectFailed {
- // Special case for Go 1 compatibility: return both the response
- // and an error if the CheckRedirect function failed.
- // See http://golang.org/issue/3795
- return resp, urlErr
- }
- if resp != nil {
- resp.Body.Close()
- }
- return nil, urlErr
- }
- 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.
- //
- // Post is a wrapper around DefaultClient.Post
- func Post(url string, bodyType string, body io.Reader) (resp *Response, err error) {
- return DefaultClient.Post(url, bodyType, body)
- }
- // Post issues a POST to the specified URL.
- //
- // Caller should close resp.Body when done reading from it.
- //
- // If the provided body is also an io.Closer, it is closed after the
- // request.
- func (c *Client) Post(url string, bodyType 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", bodyType)
- return c.doFollowingRedirects(req, shouldRedirectPost)
- }
- // PostForm issues a POST to the specified URL, with data's keys and
- // values URL-encoded as the request body.
- //
- // 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
- 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 urlencoded as the request body.
- //
- // When err is nil, resp always contains a non-nil resp.Body.
- // Caller should close resp.Body when done reading from it.
- 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 after calling the
- // Client's CheckRedirect function.
- //
- // 301 (Moved Permanently)
- // 302 (Found)
- // 303 (See Other)
- // 307 (Temporary 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)
- func (c *Client) Head(url string) (resp *Response, err error) {
- req, err := NewRequest("HEAD", url, nil)
- if err != nil {
- return nil, err
- }
- return c.doFollowingRedirects(req, shouldRedirectGet)
- }
- type cancelTimerBody struct {
- t *time.Timer
- rc io.ReadCloser
- }
- func (b *cancelTimerBody) Read(p []byte) (n int, err error) {
- n, err = b.rc.Read(p)
- if err == io.EOF {
- b.t.Stop()
- }
- return
- }
- func (b *cancelTimerBody) Close() error {
- err := b.rc.Close()
- b.t.Stop()
- return err
- }