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// HTTP Response reading and parsing. 6 7package http 8 9import ( 10 "bufio" 11 "errors" 12 "io" 13 "net/textproto" 14 "net/url" 15 "strconv" 16 "strings" 17) 18 19var respExcludeHeader = map[string]bool{ 20 "Content-Length": true, 21 "Transfer-Encoding": true, 22 "Trailer": true, 23} 24 25// Response represents the response from an HTTP request. 26// 27type Response struct { 28 Status string // e.g. "200 OK" 29 StatusCode int // e.g. 200 30 Proto string // e.g. "HTTP/1.0" 31 ProtoMajor int // e.g. 1 32 ProtoMinor int // e.g. 0 33 34 // Header maps header keys to values. If the response had multiple 35 // headers with the same key, they will be concatenated, with comma 36 // delimiters. (Section 4.2 of RFC 2616 requires that multiple headers 37 // be semantically equivalent to a comma-delimited sequence.) Values 38 // duplicated by other fields in this struct (e.g., ContentLength) are 39 // omitted from Header. 40 // 41 // Keys in the map are canonicalized (see CanonicalHeaderKey). 42 Header Header 43 44 // Body represents the response body. 45 // 46 // The http Client and Transport guarantee that Body is always 47 // non-nil, even on responses without a body or responses with 48 // a zero-lengthed body. 49 Body io.ReadCloser 50 51 // ContentLength records the length of the associated content. The 52 // value -1 indicates that the length is unknown. Unless Request.Method 53 // is "HEAD", values >= 0 indicate that the given number of bytes may 54 // be read from Body. 55 ContentLength int64 56 57 // Contains transfer encodings from outer-most to inner-most. Value is 58 // nil, means that "identity" encoding is used. 59 TransferEncoding []string 60 61 // Close records whether the header directed that the connection be 62 // closed after reading Body. The value is advice for clients: neither 63 // ReadResponse nor Response.Write ever closes a connection. 64 Close bool 65 66 // Trailer maps trailer keys to values, in the same 67 // format as the header. 68 Trailer Header 69 70 // The Request that was sent to obtain this Response. 71 // Request's Body is nil (having already been consumed). 72 // This is only populated for Client requests. 73 Request *Request 74} 75 76// Cookies parses and returns the cookies set in the Set-Cookie headers. 77func (r *Response) Cookies() []*Cookie { 78 return readSetCookies(r.Header) 79} 80 81var ErrNoLocation = errors.New("http: no Location header in response") 82 83// Location returns the URL of the response's "Location" header, 84// if present. Relative redirects are resolved relative to 85// the Response's Request. ErrNoLocation is returned if no 86// Location header is present. 87func (r *Response) Location() (*url.URL, error) { 88 lv := r.Header.Get("Location") 89 if lv == "" { 90 return nil, ErrNoLocation 91 } 92 if r.Request != nil && r.Request.URL != nil { 93 return r.Request.URL.Parse(lv) 94 } 95 return url.Parse(lv) 96} 97 98// ReadResponse reads and returns an HTTP response from r. The 99// req parameter specifies the Request that corresponds to 100// this Response. Clients must call resp.Body.Close when finished 101// reading resp.Body. After that call, clients can inspect 102// resp.Trailer to find key/value pairs included in the response 103// trailer. 104func ReadResponse(r *bufio.Reader, req *Request) (resp *Response, err error) { 105 106 tp := textproto.NewReader(r) 107 resp = new(Response) 108 109 resp.Request = req 110 111 // Parse the first line of the response. 112 line, err := tp.ReadLine() 113 if err != nil { 114 if err == io.EOF { 115 err = io.ErrUnexpectedEOF 116 } 117 return nil, err 118 } 119 f := strings.SplitN(line, " ", 3) 120 if len(f) < 2 { 121 return nil, &badStringError{"malformed HTTP response", line} 122 } 123 reasonPhrase := "" 124 if len(f) > 2 { 125 reasonPhrase = f[2] 126 } 127 resp.Status = f[1] + " " + reasonPhrase 128 resp.StatusCode, err = strconv.Atoi(f[1]) 129 if err != nil { 130 return nil, &badStringError{"malformed HTTP status code", f[1]} 131 } 132 133 resp.Proto = f[0] 134 var ok bool 135 if resp.ProtoMajor, resp.ProtoMinor, ok = ParseHTTPVersion(resp.Proto); !ok { 136 return nil, &badStringError{"malformed HTTP version", resp.Proto} 137 } 138 139 // Parse the response headers. 140 mimeHeader, err := tp.ReadMIMEHeader() 141 if err != nil { 142 return nil, err 143 } 144 resp.Header = Header(mimeHeader) 145 146 fixPragmaCacheControl(resp.Header) 147 148 err = readTransfer(resp, r) 149 if err != nil { 150 return nil, err 151 } 152 153 return resp, nil 154} 155 156// RFC2616: Should treat 157// Pragma: no-cache 158// like 159// Cache-Control: no-cache 160func fixPragmaCacheControl(header Header) { 161 if hp, ok := header["Pragma"]; ok && len(hp) > 0 && hp[0] == "no-cache" { 162 if _, presentcc := header["Cache-Control"]; !presentcc { 163 header["Cache-Control"] = []string{"no-cache"} 164 } 165 } 166} 167 168// ProtoAtLeast returns whether the HTTP protocol used 169// in the response is at least major.minor. 170func (r *Response) ProtoAtLeast(major, minor int) bool { 171 return r.ProtoMajor > major || 172 r.ProtoMajor == major && r.ProtoMinor >= minor 173} 174 175// Writes the response (header, body and trailer) in wire format. This method 176// consults the following fields of the response: 177// 178// StatusCode 179// ProtoMajor 180// ProtoMinor 181// Request.Method 182// TransferEncoding 183// Trailer 184// Body 185// ContentLength 186// Header, values for non-canonical keys will have unpredictable behavior 187// 188func (r *Response) Write(w io.Writer) error { 189 190 // Status line 191 text := r.Status 192 if text == "" { 193 var ok bool 194 text, ok = statusText[r.StatusCode] 195 if !ok { 196 text = "status code " + strconv.Itoa(r.StatusCode) 197 } 198 } 199 protoMajor, protoMinor := strconv.Itoa(r.ProtoMajor), strconv.Itoa(r.ProtoMinor) 200 statusCode := strconv.Itoa(r.StatusCode) + " " 201 if strings.HasPrefix(text, statusCode) { 202 text = text[len(statusCode):] 203 } 204 io.WriteString(w, "HTTP/"+protoMajor+"."+protoMinor+" "+statusCode+text+"\r\n") 205 206 // Process Body,ContentLength,Close,Trailer 207 tw, err := newTransferWriter(r) 208 if err != nil { 209 return err 210 } 211 err = tw.WriteHeader(w) 212 if err != nil { 213 return err 214 } 215 216 // Rest of header 217 err = r.Header.WriteSubset(w, respExcludeHeader) 218 if err != nil { 219 return err 220 } 221 222 // End-of-header 223 io.WriteString(w, "\r\n") 224 225 // Write body and trailer 226 err = tw.WriteBody(w) 227 if err != nil { 228 return err 229 } 230 231 // Success 232 return nil 233} 234