1 files changed, 511 insertions, 0 deletions
diff --git a/src/net/http/client.go b/src/net/http/client.go
new file mode 100644
index 000000000..ce884d1f0
--- /dev/null
+++ b/src/net/http/client.go
@@ -0,0 +1,511 @@
+// 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, "]") }
+
+// 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
+}
+
+// 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 ref := refererForURL(lastReq.URL, nreq.URL); ref != "" {
+					nreq.Header.Set("Referer", ref)
+				}
+
+				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
+}