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// Copyright 2010 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.
package http
import (
"io"
"net/http/httptrace"
"net/textproto"
"sort"
"strings"
"sync"
"time"
)
// A Header represents the key-value pairs in an HTTP header.
//
// The keys should be in canonical form, as returned by
// CanonicalHeaderKey.
type Header map[string][]string
// Add adds the key, value pair to the header.
// It appends to any existing values associated with key.
// The key is case insensitive; it is canonicalized by
// CanonicalHeaderKey.
func (h Header) Add(key, value string) {
textproto.MIMEHeader(h).Add(key, value)
}
// Set sets the header entries associated with key to the
// single element value. It replaces any existing values
// associated with key. The key is case insensitive; it is
// canonicalized by textproto.CanonicalMIMEHeaderKey.
// To use non-canonical keys, assign to the map directly.
func (h Header) Set(key, value string) {
textproto.MIMEHeader(h).Set(key, value)
}
// Get gets the first value associated with the given key. If
// there are no values associated with the key, Get returns "".
// It is case insensitive; textproto.CanonicalMIMEHeaderKey is
// used to canonicalize the provided key. To access multiple
// values of a key, or to use non-canonical keys, access the
// map directly.
func (h Header) Get(key string) string {
return textproto.MIMEHeader(h).Get(key)
}
// get is like Get, but key must already be in CanonicalHeaderKey form.
func (h Header) get(key string) string {
if v := h[key]; len(v) > 0 {
return v[0]
}
return ""
}
// has reports whether h has the provided key defined, even if it's
// set to 0-length slice.
func (h Header) has(key string) bool {
_, ok := h[key]
return ok
}
// Del deletes the values associated with key.
// The key is case insensitive; it is canonicalized by
// CanonicalHeaderKey.
func (h Header) Del(key string) {
textproto.MIMEHeader(h).Del(key)
}
// Write writes a header in wire format.
func (h Header) Write(w io.Writer) error {
return h.write(w, nil)
}
func (h Header) write(w io.Writer, trace *httptrace.ClientTrace) error {
return h.writeSubset(w, nil, trace)
}
func (h Header) clone() Header {
h2 := make(Header, len(h))
for k, vv := range h {
vv2 := make([]string, len(vv))
copy(vv2, vv)
h2[k] = vv2
}
return h2
}
var timeFormats = []string{
TimeFormat,
time.RFC850,
time.ANSIC,
}
// ParseTime parses a time header (such as the Date: header),
// trying each of the three formats allowed by HTTP/1.1:
// TimeFormat, time.RFC850, and time.ANSIC.
func ParseTime(text string) (t time.Time, err error) {
for _, layout := range timeFormats {
t, err = time.Parse(layout, text)
if err == nil {
return
}
}
return
}
var headerNewlineToSpace = strings.NewReplacer("\n", " ", "\r", " ")
// stringWriter implements WriteString on a Writer.
type stringWriter struct {
w io.Writer
}
func (w stringWriter) WriteString(s string) (n int, err error) {
return w.w.Write([]byte(s))
}
type keyValues struct {
key string
values []string
}
// A headerSorter implements sort.Interface by sorting a []keyValues
// by key. It's used as a pointer, so it can fit in a sort.Interface
// interface value without allocation.
type headerSorter struct {
kvs []keyValues
}
func (s *headerSorter) Len() int { return len(s.kvs) }
func (s *headerSorter) Swap(i, j int) { s.kvs[i], s.kvs[j] = s.kvs[j], s.kvs[i] }
func (s *headerSorter) Less(i, j int) bool { return s.kvs[i].key < s.kvs[j].key }
var headerSorterPool = sync.Pool{
New: func() interface{} { return new(headerSorter) },
}
// sortedKeyValues returns h's keys sorted in the returned kvs
// slice. The headerSorter used to sort is also returned, for possible
// return to headerSorterCache.
func (h Header) sortedKeyValues(exclude map[string]bool) (kvs []keyValues, hs *headerSorter) {
hs = headerSorterPool.Get().(*headerSorter)
if cap(hs.kvs) < len(h) {
hs.kvs = make([]keyValues, 0, len(h))
}
kvs = hs.kvs[:0]
for k, vv := range h {
if !exclude[k] {
kvs = append(kvs, keyValues{k, vv})
}
}
hs.kvs = kvs
sort.Sort(hs)
return kvs, hs
}
// WriteSubset writes a header in wire format.
// If exclude is not nil, keys where exclude[key] == true are not written.
func (h Header) WriteSubset(w io.Writer, exclude map[string]bool) error {
return h.writeSubset(w, exclude, nil)
}
func (h Header) writeSubset(w io.Writer, exclude map[string]bool, trace *httptrace.ClientTrace) error {
ws, ok := w.(io.StringWriter)
if !ok {
ws = stringWriter{w}
}
kvs, sorter := h.sortedKeyValues(exclude)
var formattedVals []string
for _, kv := range kvs {
for _, v := range kv.values {
v = headerNewlineToSpace.Replace(v)
v = textproto.TrimString(v)
for _, s := range []string{kv.key, ": ", v, "\r\n"} {
if _, err := ws.WriteString(s); err != nil {
headerSorterPool.Put(sorter)
return err
}
}
if trace != nil && trace.WroteHeaderField != nil {
formattedVals = append(formattedVals, v)
}
}
if trace != nil && trace.WroteHeaderField != nil {
trace.WroteHeaderField(kv.key, formattedVals)
formattedVals = nil
}
}
headerSorterPool.Put(sorter)
return nil
}
// CanonicalHeaderKey returns the canonical format of the
// header key s. The canonicalization converts the first
// letter and any letter following a hyphen to upper case;
// the rest are converted to lowercase. For example, the
// canonical key for "accept-encoding" is "Accept-Encoding".
// If s contains a space or invalid header field bytes, it is
// returned without modifications.
func CanonicalHeaderKey(s string) string { return textproto.CanonicalMIMEHeaderKey(s) }
// hasToken reports whether token appears with v, ASCII
// case-insensitive, with space or comma boundaries.
// token must be all lowercase.
// v may contain mixed cased.
func hasToken(v, token string) bool {
if len(token) > len(v) || token == "" {
return false
}
if v == token {
return true
}
for sp := 0; sp <= len(v)-len(token); sp++ {
// Check that first character is good.
// The token is ASCII, so checking only a single byte
// is sufficient. We skip this potential starting
// position if both the first byte and its potential
// ASCII uppercase equivalent (b|0x20) don't match.
// False positives ('^' => '~') are caught by EqualFold.
if b := v[sp]; b != token[0] && b|0x20 != token[0] {
continue
}
// Check that start pos is on a valid token boundary.
if sp > 0 && !isTokenBoundary(v[sp-1]) {
continue
}
// Check that end pos is on a valid token boundary.
if endPos := sp + len(token); endPos != len(v) && !isTokenBoundary(v[endPos]) {
continue
}
if strings.EqualFold(v[sp:sp+len(token)], token) {
return true
}
}
return false
}
func isTokenBoundary(b byte) bool {
return b == ' ' || b == ',' || b == '\t'
}