libgo/go/net/http/header.go

   1 // Copyright 2010 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 package http
   6
   7 import (
   8         "io"
   9         "net/http/httptrace"
  10         "net/textproto"
  11         "sort"
  12         "strings"
  13         "sync"
  14         "time"
  15 )
  16
  17 var raceEnabled = false // set by race.go
  18
  19 // A Header represents the key-value pairs in an HTTP header.
  20 type Header map[string][]string
  21
  22 // Add adds the key, value pair to the header.
  23 // It appends to any existing values associated with key.
  24 func (h Header) Add(key, value string) {
  25         textproto.MIMEHeader(h).Add(key, value)
  26 }
  27
  28 // Set sets the header entries associated with key to
  29 // the single element value. It replaces any existing
  30 // values associated with key.
  31 func (h Header) Set(key, value string) {
  32         textproto.MIMEHeader(h).Set(key, value)
  33 }
  34
  35 // Get gets the first value associated with the given key.
  36 // It is case insensitive; textproto.CanonicalMIMEHeaderKey is used
  37 // to canonicalize the provided key.
  38 // If there are no values associated with the key, Get returns "".
  39 // To access multiple values of a key, or to use non-canonical keys,
  40 // access the map directly.
  41 func (h Header) Get(key string) string {
  42         return textproto.MIMEHeader(h).Get(key)
  43 }
  44
  45 // get is like Get, but key must already be in CanonicalHeaderKey form.
  46 func (h Header) get(key string) string {
  47         if v := h[key]; len(v) > 0 {
  48                 return v[0]
  49         }
  50         return ""
  51 }
  52
  53 // Del deletes the values associated with key.
  54 func (h Header) Del(key string) {
  55         textproto.MIMEHeader(h).Del(key)
  56 }
  57
  58 // Write writes a header in wire format.
  59 func (h Header) Write(w io.Writer) error {
  60         return h.write(w, nil)
  61 }
  62
  63 func (h Header) write(w io.Writer, trace *httptrace.ClientTrace) error {
  64         return h.writeSubset(w, nil, trace)
  65 }
  66
  67 func (h Header) clone() Header {
  68         h2 := make(Header, len(h))
  69         for k, vv := range h {
  70                 vv2 := make([]string, len(vv))
  71                 copy(vv2, vv)
  72                 h2[k] = vv2
  73         }
  74         return h2
  75 }
  76
  77 var timeFormats = []string{
  78         TimeFormat,
  79         time.RFC850,
  80         time.ANSIC,
  81 }
  82
  83 // ParseTime parses a time header (such as the Date: header),
  84 // trying each of the three formats allowed by HTTP/1.1:
  85 // TimeFormat, time.RFC850, and time.ANSIC.
  86 func ParseTime(text string) (t time.Time, err error) {
  87         for _, layout := range timeFormats {
  88                 t, err = time.Parse(layout, text)
  89                 if err == nil {
  90                         return
  91                 }
  92         }
  93         return
  94 }
  95
  96 var headerNewlineToSpace = strings.NewReplacer("\n", " ", "\r", " ")
  97
  98 type writeStringer interface {
  99         WriteString(string) (int, error)
 100 }
 101
 102 // stringWriter implements WriteString on a Writer.
 103 type stringWriter struct {
 104         w io.Writer
 105 }
 106
 107 func (w stringWriter) WriteString(s string) (n int, err error) {
 108         return w.w.Write([]byte(s))
 109 }
 110
 111 type keyValues struct {
 112         key    string
 113         values []string
 114 }
 115
 116 // A headerSorter implements sort.Interface by sorting a []keyValues
 117 // by key. It's used as a pointer, so it can fit in a sort.Interface
 118 // interface value without allocation.
 119 type headerSorter struct {
 120         kvs []keyValues
 121 }
 122
 123 func (s *headerSorter) Len() int           { return len(s.kvs) }
 124 func (s *headerSorter) Swap(i, j int)      { s.kvs[i], s.kvs[j] = s.kvs[j], s.kvs[i] }
 125 func (s *headerSorter) Less(i, j int) bool { return s.kvs[i].key < s.kvs[j].key }
 126
 127 var headerSorterPool = sync.Pool{
 128         New: func() interface{} { return new(headerSorter) },
 129 }
 130
 131 // sortedKeyValues returns h's keys sorted in the returned kvs
 132 // slice. The headerSorter used to sort is also returned, for possible
 133 // return to headerSorterCache.
 134 func (h Header) sortedKeyValues(exclude map[string]bool) (kvs []keyValues, hs *headerSorter) {
 135         hs = headerSorterPool.Get().(*headerSorter)
 136         if cap(hs.kvs) < len(h) {
 137                 hs.kvs = make([]keyValues, 0, len(h))
 138         }
 139         kvs = hs.kvs[:0]
 140         for k, vv := range h {
 141                 if !exclude[k] {
 142                         kvs = append(kvs, keyValues{k, vv})
 143                 }
 144         }
 145         hs.kvs = kvs
 146         sort.Sort(hs)
 147         return kvs, hs
 148 }
 149
 150 // WriteSubset writes a header in wire format.
 151 // If exclude is not nil, keys where exclude[key] == true are not written.
 152 func (h Header) WriteSubset(w io.Writer, exclude map[string]bool) error {
 153         return h.writeSubset(w, exclude, nil)
 154 }
 155
 156 func (h Header) writeSubset(w io.Writer, exclude map[string]bool, trace *httptrace.ClientTrace) error {
 157         ws, ok := w.(writeStringer)
 158         if !ok {
 159                 ws = stringWriter{w}
 160         }
 161         kvs, sorter := h.sortedKeyValues(exclude)
 162         var formattedVals []string
 163         for _, kv := range kvs {
 164                 for _, v := range kv.values {
 165                         v = headerNewlineToSpace.Replace(v)
 166                         v = textproto.TrimString(v)
 167                         for _, s := range []string{kv.key, ": ", v, "\r\n"} {
 168                                 if _, err := ws.WriteString(s); err != nil {
 169                                         headerSorterPool.Put(sorter)
 170                                         return err
 171                                 }
 172                         }
 173                         if trace != nil && trace.WroteHeaderField != nil {
 174                                 formattedVals = append(formattedVals, v)
 175                         }
 176                 }
 177                 if trace != nil && trace.WroteHeaderField != nil {
 178                         trace.WroteHeaderField(kv.key, formattedVals)
 179                         formattedVals = nil
 180                 }
 181         }
 182         headerSorterPool.Put(sorter)
 183         return nil
 184 }
 185
 186 // CanonicalHeaderKey returns the canonical format of the
 187 // header key s. The canonicalization converts the first
 188 // letter and any letter following a hyphen to upper case;
 189 // the rest are converted to lowercase. For example, the
 190 // canonical key for "accept-encoding" is "Accept-Encoding".
 191 // If s contains a space or invalid header field bytes, it is
 192 // returned without modifications.
 193 func CanonicalHeaderKey(s string) string { return textproto.CanonicalMIMEHeaderKey(s) }
 194
 195 // hasToken reports whether token appears with v, ASCII
 196 // case-insensitive, with space or comma boundaries.
 197 // token must be all lowercase.
 198 // v may contain mixed cased.
 199 func hasToken(v, token string) bool {
 200         if len(token) > len(v) || token == "" {
 201                 return false
 202         }
 203         if v == token {
 204                 return true
 205         }
 206         for sp := 0; sp <= len(v)-len(token); sp++ {
 207                 // Check that first character is good.
 208                 // The token is ASCII, so checking only a single byte
 209                 // is sufficient. We skip this potential starting
 210                 // position if both the first byte and its potential
 211                 // ASCII uppercase equivalent (b|0x20) don't match.
 212                 // False positives ('^' => '~') are caught by EqualFold.
 213                 if b := v[sp]; b != token[0] && b|0x20 != token[0] {
 214                         continue
 215                 }
 216                 // Check that start pos is on a valid token boundary.
 217                 if sp > 0 && !isTokenBoundary(v[sp-1]) {
 218                         continue
 219                 }
 220                 // Check that end pos is on a valid token boundary.
 221                 if endPos := sp + len(token); endPos != len(v) && !isTokenBoundary(v[endPos]) {
 222                         continue
 223                 }
 224                 if strings.EqualFold(v[sp:sp+len(token)], token) {
 225                         return true
 226                 }
 227         }
 228         return false
 229 }
 230
 231 func isTokenBoundary(b byte) bool {
 232         return b == ' ' || b == ',' || b == '\t'
 233 }
 234
 235 func cloneHeader(h Header) Header {
 236         h2 := make(Header, len(h))
 237         for k, vv := range h {
 238                 vv2 := make([]string, len(vv))
 239                 copy(vv2, vv)
 240                 h2[k] = vv2
 241         }
 242         return h2
 243 }