libgo/go/http/client.go

   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.
   4
   5 // Primitive HTTP client. See RFC 2616.
   6
   7 package http
   8
   9 import (
  10         "bufio"
  11         "bytes"
  12         "crypto/tls"
  13         "encoding/base64"
  14         "fmt"
  15         "io"
  16         "net"
  17         "os"
  18         "strconv"
  19         "strings"
  20 )
  21
  22 // Given a string of the form "host", "host:port", or "[ipv6::address]:port",
  23 // return true if the string includes a port.
  24 func hasPort(s string) bool { return strings.LastIndex(s, ":") > strings.LastIndex(s, "]") }
  25
  26 // Used in Send to implement io.ReadCloser by bundling together the
  27 // bufio.Reader through which we read the response, and the underlying
  28 // network connection.
  29 type readClose struct {
  30         io.Reader
  31         io.Closer
  32 }
  33
  34 // Send issues an HTTP request.  Caller should close resp.Body when done reading it.
  35 //
  36 // TODO: support persistent connections (multiple requests on a single connection).
  37 // send() method is nonpublic because, when we refactor the code for persistent
  38 // connections, it may no longer make sense to have a method with this signature.
  39 func send(req *Request) (resp *Response, err os.Error) {
  40         if req.URL.Scheme != "http" && req.URL.Scheme != "https" {
  41                 return nil, &badStringError{"unsupported protocol scheme", req.URL.Scheme}
  42         }
  43
  44         addr := req.URL.Host
  45         if !hasPort(addr) {
  46                 addr += ":" + req.URL.Scheme
  47         }
  48         info := req.URL.RawUserinfo
  49         if len(info) > 0 {
  50                 enc := base64.URLEncoding
  51                 encoded := make([]byte, enc.EncodedLen(len(info)))
  52                 enc.Encode(encoded, []byte(info))
  53                 if req.Header == nil {
  54                         req.Header = make(map[string]string)
  55                 }
  56                 req.Header["Authorization"] = "Basic " + string(encoded)
  57         }
  58
  59         var conn io.ReadWriteCloser
  60         if req.URL.Scheme == "http" {
  61                 conn, err = net.Dial("tcp", "", addr)
  62                 if err != nil {
  63                         return nil, err
  64                 }
  65         } else { // https
  66                 conn, err = tls.Dial("tcp", "", addr)
  67                 if err != nil {
  68                         return nil, err
  69                 }
  70                 h := req.URL.Host
  71                 if hasPort(h) {
  72                         h = h[0:strings.LastIndex(h, ":")]
  73                 }
  74                 if err := conn.(*tls.Conn).VerifyHostname(h); err != nil {
  75                         return nil, err
  76                 }
  77         }
  78
  79         err = req.Write(conn)
  80         if err != nil {
  81                 conn.Close()
  82                 return nil, err
  83         }
  84
  85         reader := bufio.NewReader(conn)
  86         resp, err = ReadResponse(reader, req.Method)
  87         if err != nil {
  88                 conn.Close()
  89                 return nil, err
  90         }
  91
  92         resp.Body = readClose{resp.Body, conn}
  93
  94         return
  95 }
  96
  97 // True if the specified HTTP status code is one for which the Get utility should
  98 // automatically redirect.
  99 func shouldRedirect(statusCode int) bool {
 100         switch statusCode {
 101         case StatusMovedPermanently, StatusFound, StatusSeeOther, StatusTemporaryRedirect:
 102                 return true
 103         }
 104         return false
 105 }
 106
 107 // Get issues a GET to the specified URL.  If the response is one of the following
 108 // redirect codes, it follows the redirect, up to a maximum of 10 redirects:
 109 //
 110 //    301 (Moved Permanently)
 111 //    302 (Found)
 112 //    303 (See Other)
 113 //    307 (Temporary Redirect)
 114 //
 115 // finalURL is the URL from which the response was fetched -- identical to the
 116 // input URL unless redirects were followed.
 117 //
 118 // Caller should close r.Body when done reading it.
 119 func Get(url string) (r *Response, finalURL string, err os.Error) {
 120         // TODO: if/when we add cookie support, the redirected request shouldn't
 121         // necessarily supply the same cookies as the original.
 122         // TODO: set referrer header on redirects.
 123         for redirect := 0; ; redirect++ {
 124                 if redirect >= 10 {
 125                         err = os.ErrorString("stopped after 10 redirects")
 126                         break
 127                 }
 128
 129                 var req Request
 130                 if req.URL, err = ParseURL(url); err != nil {
 131                         break
 132                 }
 133                 url = req.URL.String()
 134                 if r, err = send(&req); err != nil {
 135                         break
 136                 }
 137                 if shouldRedirect(r.StatusCode) {
 138                         r.Body.Close()
 139                         if url = r.GetHeader("Location"); url == "" {
 140                                 err = os.ErrorString(fmt.Sprintf("%d response missing Location header", r.StatusCode))
 141                                 break
 142                         }
 143                         continue
 144                 }
 145                 finalURL = url
 146                 return
 147         }
 148
 149         err = &URLError{"Get", url, err}
 150         return
 151 }
 152
 153 // Post issues a POST to the specified URL.
 154 //
 155 // Caller should close r.Body when done reading it.
 156 func Post(url string, bodyType string, body io.Reader) (r *Response, err os.Error) {
 157         var req Request
 158         req.Method = "POST"
 159         req.ProtoMajor = 1
 160         req.ProtoMinor = 1
 161         req.Close = true
 162         req.Body = nopCloser{body}
 163         req.Header = map[string]string{
 164                 "Content-Type": bodyType,
 165         }
 166         req.TransferEncoding = []string{"chunked"}
 167
 168         req.URL, err = ParseURL(url)
 169         if err != nil {
 170                 return nil, err
 171         }
 172
 173         return send(&req)
 174 }
 175
 176 // PostForm issues a POST to the specified URL,
 177 // with data's keys and values urlencoded as the request body.
 178 //
 179 // Caller should close r.Body when done reading it.
 180 func PostForm(url string, data map[string]string) (r *Response, err os.Error) {
 181         var req Request
 182         req.Method = "POST"
 183         req.ProtoMajor = 1
 184         req.ProtoMinor = 1
 185         req.Close = true
 186         body := urlencode(data)
 187         req.Body = nopCloser{body}
 188         req.Header = map[string]string{
 189                 "Content-Type":   "application/x-www-form-urlencoded",
 190                 "Content-Length": strconv.Itoa(body.Len()),
 191         }
 192         req.ContentLength = int64(body.Len())
 193
 194         req.URL, err = ParseURL(url)
 195         if err != nil {
 196                 return nil, err
 197         }
 198
 199         return send(&req)
 200 }
 201
 202 func urlencode(data map[string]string) (b *bytes.Buffer) {
 203         b = new(bytes.Buffer)
 204         first := true
 205         for k, v := range data {
 206                 if first {
 207                         first = false
 208                 } else {
 209                         b.WriteByte('&')
 210                 }
 211                 b.WriteString(URLEscape(k))
 212                 b.WriteByte('=')
 213                 b.WriteString(URLEscape(v))
 214         }
 215         return
 216 }
 217
 218 // Head issues a HEAD to the specified URL.
 219 func Head(url string) (r *Response, err os.Error) {
 220         var req Request
 221         req.Method = "HEAD"
 222         if req.URL, err = ParseURL(url); err != nil {
 223                 return
 224         }
 225         url = req.URL.String()
 226         if r, err = send(&req); err != nil {
 227                 return
 228         }
 229         return
 230 }
 231
 232 type nopCloser struct {
 233         io.Reader
 234 }
 235
 236 func (nopCloser) Close() os.Error { return nil }