309 lines
8.8 KiB
Go
309 lines
8.8 KiB
Go
// Copyright 2009 The Go Authors. All rights reserved.
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// Use of this source code is governed by a BSD-style
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// license that can be found in the LICENSE file.
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// Primitive HTTP client. See RFC 2616.
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package http
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import (
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"bytes"
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"encoding/base64"
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"fmt"
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"io"
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"io/ioutil"
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"os"
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"strconv"
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"strings"
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)
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// A Client is an HTTP client. Its zero value (DefaultClient) is a usable client
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// that uses DefaultTransport.
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// Client is not yet very configurable.
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type Client struct {
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Transport RoundTripper // if nil, DefaultTransport is used
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// If CheckRedirect is not nil, the client calls it before
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// following an HTTP redirect. The arguments req and via
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// are the upcoming request and the requests made already,
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// oldest first. If CheckRedirect returns an error, the client
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// returns that error instead of issue the Request req.
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//
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// If CheckRedirect is nil, the Client uses its default policy,
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// which is to stop after 10 consecutive requests.
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CheckRedirect func(req *Request, via []*Request) os.Error
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}
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// DefaultClient is the default Client and is used by Get, Head, and Post.
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var DefaultClient = &Client{}
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// RoundTripper is an interface representing the ability to execute a
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// single HTTP transaction, obtaining the Response for a given Request.
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type RoundTripper interface {
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// RoundTrip executes a single HTTP transaction, returning
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// the Response for the request req. RoundTrip should not
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// attempt to interpret the response. In particular,
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// RoundTrip must return err == nil if it obtained a response,
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// regardless of the response's HTTP status code. A non-nil
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// err should be reserved for failure to obtain a response.
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// Similarly, RoundTrip should not attempt to handle
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// higher-level protocol details such as redirects,
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// authentication, or cookies.
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//
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// RoundTrip may modify the request. The request Headers field is
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// guaranteed to be initialized.
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RoundTrip(req *Request) (resp *Response, err os.Error)
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}
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// Given a string of the form "host", "host:port", or "[ipv6::address]:port",
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// return true if the string includes a port.
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func hasPort(s string) bool { return strings.LastIndex(s, ":") > strings.LastIndex(s, "]") }
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// Used in Send to implement io.ReadCloser by bundling together the
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// bufio.Reader through which we read the response, and the underlying
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// network connection.
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type readClose struct {
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io.Reader
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io.Closer
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}
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// Do sends an HTTP request and returns an HTTP response, following
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// policy (e.g. redirects, cookies, auth) as configured on the client.
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//
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// Callers should close resp.Body when done reading from it.
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//
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// Generally Get, Post, or PostForm will be used instead of Do.
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func (c *Client) Do(req *Request) (resp *Response, err os.Error) {
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return send(req, c.Transport)
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}
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// send issues an HTTP request. Caller should close resp.Body when done reading from it.
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func send(req *Request, t RoundTripper) (resp *Response, err os.Error) {
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if t == nil {
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t = DefaultTransport
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if t == nil {
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err = os.NewError("no http.Client.Transport or http.DefaultTransport")
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return
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}
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}
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// Most the callers of send (Get, Post, et al) don't need
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// Headers, leaving it uninitialized. We guarantee to the
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// Transport that this has been initialized, though.
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if req.Header == nil {
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req.Header = make(Header)
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}
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info := req.URL.RawUserinfo
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if len(info) > 0 {
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enc := base64.URLEncoding
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encoded := make([]byte, enc.EncodedLen(len(info)))
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enc.Encode(encoded, []byte(info))
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if req.Header == nil {
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req.Header = make(Header)
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}
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req.Header.Set("Authorization", "Basic "+string(encoded))
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}
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return t.RoundTrip(req)
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}
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// True if the specified HTTP status code is one for which the Get utility should
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// automatically redirect.
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func shouldRedirect(statusCode int) bool {
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switch statusCode {
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case StatusMovedPermanently, StatusFound, StatusSeeOther, StatusTemporaryRedirect:
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return true
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}
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return false
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}
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// Get issues a GET to the specified URL. If the response is one of the following
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// redirect codes, Get follows the redirect, up to a maximum of 10 redirects:
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//
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// 301 (Moved Permanently)
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// 302 (Found)
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// 303 (See Other)
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// 307 (Temporary Redirect)
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//
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// finalURL is the URL from which the response was fetched -- identical to the
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// input URL unless redirects were followed.
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//
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// Caller should close r.Body when done reading from it.
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//
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// Get is a convenience wrapper around DefaultClient.Get.
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func Get(url string) (r *Response, finalURL string, err os.Error) {
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return DefaultClient.Get(url)
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}
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// Get issues a GET to the specified URL. If the response is one of the
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// following redirect codes, Get follows the redirect after calling the
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// Client's CheckRedirect function.
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//
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// 301 (Moved Permanently)
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// 302 (Found)
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// 303 (See Other)
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// 307 (Temporary Redirect)
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//
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// finalURL is the URL from which the response was fetched -- identical
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// to the input URL unless redirects were followed.
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//
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// Caller should close r.Body when done reading from it.
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func (c *Client) Get(url string) (r *Response, finalURL string, err os.Error) {
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// TODO: if/when we add cookie support, the redirected request shouldn't
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// necessarily supply the same cookies as the original.
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var base *URL
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redirectChecker := c.CheckRedirect
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if redirectChecker == nil {
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redirectChecker = defaultCheckRedirect
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}
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var via []*Request
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for redirect := 0; ; redirect++ {
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var req Request
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req.Method = "GET"
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req.Header = make(Header)
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if base == nil {
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req.URL, err = ParseURL(url)
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} else {
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req.URL, err = base.ParseURL(url)
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}
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if err != nil {
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break
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}
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if len(via) > 0 {
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// Add the Referer header.
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lastReq := via[len(via)-1]
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if lastReq.URL.Scheme != "https" {
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req.Referer = lastReq.URL.String()
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}
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err = redirectChecker(&req, via)
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if err != nil {
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break
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}
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}
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url = req.URL.String()
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if r, err = send(&req, c.Transport); err != nil {
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break
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}
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if shouldRedirect(r.StatusCode) {
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r.Body.Close()
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if url = r.Header.Get("Location"); url == "" {
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err = os.ErrorString(fmt.Sprintf("%d response missing Location header", r.StatusCode))
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break
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}
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base = req.URL
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via = append(via, &req)
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continue
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}
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finalURL = url
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return
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}
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err = &URLError{"Get", url, err}
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return
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}
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func defaultCheckRedirect(req *Request, via []*Request) os.Error {
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if len(via) >= 10 {
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return os.ErrorString("stopped after 10 redirects")
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}
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return nil
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}
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// Post issues a POST to the specified URL.
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//
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// Caller should close r.Body when done reading from it.
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//
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// Post is a wrapper around DefaultClient.Post
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func Post(url string, bodyType string, body io.Reader) (r *Response, err os.Error) {
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return DefaultClient.Post(url, bodyType, body)
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}
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// Post issues a POST to the specified URL.
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//
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// Caller should close r.Body when done reading from it.
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func (c *Client) Post(url string, bodyType string, body io.Reader) (r *Response, err os.Error) {
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var req Request
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req.Method = "POST"
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req.ProtoMajor = 1
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req.ProtoMinor = 1
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req.Close = true
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req.Body = ioutil.NopCloser(body)
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req.Header = Header{
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"Content-Type": {bodyType},
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}
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req.TransferEncoding = []string{"chunked"}
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req.URL, err = ParseURL(url)
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if err != nil {
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return nil, err
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}
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return send(&req, c.Transport)
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}
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// PostForm issues a POST to the specified URL,
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// with data's keys and values urlencoded as the request body.
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//
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// Caller should close r.Body when done reading from it.
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//
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// PostForm is a wrapper around DefaultClient.PostForm
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func PostForm(url string, data map[string]string) (r *Response, err os.Error) {
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return DefaultClient.PostForm(url, data)
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}
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// PostForm issues a POST to the specified URL,
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// with data's keys and values urlencoded as the request body.
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//
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// Caller should close r.Body when done reading from it.
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func (c *Client) PostForm(url string, data map[string]string) (r *Response, err os.Error) {
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var req Request
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req.Method = "POST"
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req.ProtoMajor = 1
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req.ProtoMinor = 1
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req.Close = true
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body := urlencode(data)
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req.Body = ioutil.NopCloser(body)
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req.Header = Header{
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"Content-Type": {"application/x-www-form-urlencoded"},
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"Content-Length": {strconv.Itoa(body.Len())},
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}
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req.ContentLength = int64(body.Len())
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req.URL, err = ParseURL(url)
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if err != nil {
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return nil, err
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}
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return send(&req, c.Transport)
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}
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// TODO: remove this function when PostForm takes a multimap.
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func urlencode(data map[string]string) (b *bytes.Buffer) {
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m := make(map[string][]string, len(data))
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for k, v := range data {
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m[k] = []string{v}
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}
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return bytes.NewBuffer([]byte(EncodeQuery(m)))
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}
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// Head issues a HEAD to the specified URL.
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//
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// Head is a wrapper around DefaultClient.Head
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func Head(url string) (r *Response, err os.Error) {
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return DefaultClient.Head(url)
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}
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// Head issues a HEAD to the specified URL.
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func (c *Client) Head(url string) (r *Response, err os.Error) {
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var req Request
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req.Method = "HEAD"
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if req.URL, err = ParseURL(url); err != nil {
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return
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}
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return send(&req, c.Transport)
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}
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