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// 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 Response reading and parsing.
package http
import (
"bufio"
"errors"
"io"
"net/textproto"
"net/url"
"strconv"
"strings"
)
var respExcludeHeader = map[string]bool{
"Content-Length": true,
"Transfer-Encoding": true,
"Trailer": true,
}
// Response represents the response from an HTTP request.
//
type Response struct {
Status string // e.g. "200 OK"
StatusCode int // e.g. 200
Proto string // e.g. "HTTP/1.0"
ProtoMajor int // e.g. 1
ProtoMinor int // e.g. 0
// Header maps header keys to values. If the response had multiple
// headers with the same key, they may be concatenated, with comma
// delimiters. (Section 4.2 of RFC 2616 requires that multiple headers
// be semantically equivalent to a comma-delimited sequence.) Values
// duplicated by other fields in this struct (e.g., ContentLength) are
// omitted from Header.
//
// Keys in the map are canonicalized (see CanonicalHeaderKey).
Header Header
// Body represents the response body.
//
// The http Client and Transport guarantee that Body is always
// non-nil, even on responses without a body or responses with
// a zero-lengthed body.
//
// The Body is automatically dechunked if the server replied
// with a "chunked" Transfer-Encoding.
Body io.ReadCloser
// ContentLength records the length of the associated content. The
// value -1 indicates that the length is unknown. Unless Request.Method
// is "HEAD", values >= 0 indicate that the given number of bytes may
// be read from Body.
ContentLength int64
// Contains transfer encodings from outer-most to inner-most. Value is
// nil, means that "identity" encoding is used.
TransferEncoding []string
// Close records whether the header directed that the connection be
// closed after reading Body. The value is advice for clients: neither
// ReadResponse nor Response.Write ever closes a connection.
Close bool
// Trailer maps trailer keys to values, in the same
// format as the header.
Trailer Header
// The Request that was sent to obtain this Response.
// Request's Body is nil (having already been consumed).
// This is only populated for Client requests.
Request *Request
}
// Cookies parses and returns the cookies set in the Set-Cookie headers.
func (r *Response) Cookies() []*Cookie {
return readSetCookies(r.Header)
}
var ErrNoLocation = errors.New("http: no Location header in response")
// Location returns the URL of the response's "Location" header,
// if present. Relative redirects are resolved relative to
// the Response's Request. ErrNoLocation is returned if no
// Location header is present.
func (r *Response) Location() (*url.URL, error) {
lv := r.Header.Get("Location")
if lv == "" {
return nil, ErrNoLocation
}
if r.Request != nil && r.Request.URL != nil {
return r.Request.URL.Parse(lv)
}
return url.Parse(lv)
}
// ReadResponse reads and returns an HTTP response from r.
// The req parameter optionally specifies the Request that corresponds
// to this Response. If nil, a GET request is assumed.
// Clients must call resp.Body.Close when finished reading resp.Body.
// After that call, clients can inspect resp.Trailer to find key/value
// pairs included in the response trailer.
func ReadResponse(r *bufio.Reader, req *Request) (*Response, error) {
tp := textproto.NewReader(r)
resp := &Response{
Request: req,
}
// Parse the first line of the response.
line, err := tp.ReadLine()
if err != nil {
if err == io.EOF {
err = io.ErrUnexpectedEOF
}
return nil, err
}
f := strings.SplitN(line, " ", 3)
if len(f) < 2 {
return nil, &badStringError{"malformed HTTP response", line}
}
reasonPhrase := ""
if len(f) > 2 {
reasonPhrase = f[2]
}
resp.Status = f[1] + " " + reasonPhrase
resp.StatusCode, err = strconv.Atoi(f[1])
if err != nil {
return nil, &badStringError{"malformed HTTP status code", f[1]}
}
resp.Proto = f[0]
var ok bool
if resp.ProtoMajor, resp.ProtoMinor, ok = ParseHTTPVersion(resp.Proto); !ok {
return nil, &badStringError{"malformed HTTP version", resp.Proto}
}
// Parse the response headers.
mimeHeader, err := tp.ReadMIMEHeader()
if err != nil {
return nil, err
}
resp.Header = Header(mimeHeader)
fixPragmaCacheControl(resp.Header)
err = readTransfer(resp, r)
if err != nil {
return nil, err
}
return resp, nil
}
// RFC2616: Should treat
// Pragma: no-cache
// like
// Cache-Control: no-cache
func fixPragmaCacheControl(header Header) {
if hp, ok := header["Pragma"]; ok && len(hp) > 0 && hp[0] == "no-cache" {
if _, presentcc := header["Cache-Control"]; !presentcc {
header["Cache-Control"] = []string{"no-cache"}
}
}
}
// ProtoAtLeast reports whether the HTTP protocol used
// in the response is at least major.minor.
func (r *Response) ProtoAtLeast(major, minor int) bool {
return r.ProtoMajor > major ||
r.ProtoMajor == major && r.ProtoMinor >= minor
}
// Writes the response (header, body and trailer) in wire format. This method
// consults the following fields of the response:
//
// StatusCode
// ProtoMajor
// ProtoMinor
// Request.Method
// TransferEncoding
// Trailer
// Body
// ContentLength
// Header, values for non-canonical keys will have unpredictable behavior
//
// Body is closed after it is sent.
func (r *Response) Write(w io.Writer) error {
// Status line
text := r.Status
if text == "" {
var ok bool
text, ok = statusText[r.StatusCode]
if !ok {
text = "status code " + strconv.Itoa(r.StatusCode)
}
}
protoMajor, protoMinor := strconv.Itoa(r.ProtoMajor), strconv.Itoa(r.ProtoMinor)
statusCode := strconv.Itoa(r.StatusCode) + " "
text = strings.TrimPrefix(text, statusCode)
io.WriteString(w, "HTTP/"+protoMajor+"."+protoMinor+" "+statusCode+text+"\r\n")
// Process Body,ContentLength,Close,Trailer
tw, err := newTransferWriter(r)
if err != nil {
return err
}
err = tw.WriteHeader(w)
if err != nil {
return err
}
// Rest of header
err = r.Header.WriteSubset(w, respExcludeHeader)
if err != nil {
return err
}
// End-of-header
io.WriteString(w, "\r\n")
// Write body and trailer
err = tw.WriteBody(w)
if err != nil {
return err
}
// Success
return nil
}
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