146 lines
3.1 KiB
Go
146 lines
3.1 KiB
Go
// Copyright 2013 The Go Authors. All rights reserved.
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//
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// Use of this source code is governed by a BSD-style
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// license that can be found in the LICENSE file or at
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// https://developers.google.com/open-source/licenses/bsd.
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// Package header provides functions for parsing HTTP headers.
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package header
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import (
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"net/http"
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"strings"
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)
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// Octet types from RFC 2616.
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var octetTypes [256]octetType
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type octetType byte
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const (
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isToken octetType = 1 << iota
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isSpace
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)
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func init() {
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// OCTET = <any 8-bit sequence of data>
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// CHAR = <any US-ASCII character (octets 0 - 127)>
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// CTL = <any US-ASCII control character (octets 0 - 31) and DEL (127)>
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// CR = <US-ASCII CR, carriage return (13)>
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// LF = <US-ASCII LF, linefeed (10)>
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// SP = <US-ASCII SP, space (32)>
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// HT = <US-ASCII HT, horizontal-tab (9)>
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// <"> = <US-ASCII double-quote mark (34)>
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// CRLF = CR LF
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// LWS = [CRLF] 1*( SP | HT )
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// TEXT = <any OCTET except CTLs, but including LWS>
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// separators = "(" | ")" | "<" | ">" | "@" | "," | ";" | ":" | "\" | <">
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// | "/" | "[" | "]" | "?" | "=" | "{" | "}" | SP | HT
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// token = 1*<any CHAR except CTLs or separators>
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// qdtext = <any TEXT except <">>
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for c := 0; c < 256; c++ {
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var t octetType
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isCtl := c <= 31 || c == 127
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isChar := 0 <= c && c <= 127
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isSeparator := strings.ContainsRune(" \t\"(),/:;<=>?@[]\\{}", rune(c))
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if strings.ContainsRune(" \t\r\n", rune(c)) {
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t |= isSpace
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}
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if isChar && !isCtl && !isSeparator {
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t |= isToken
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}
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octetTypes[c] = t
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}
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}
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// AcceptSpec describes an Accept* header.
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type AcceptSpec struct {
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Value string
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Q float64
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}
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// ParseAccept parses Accept* headers.
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func ParseAccept(header http.Header, key string) (specs []AcceptSpec) {
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loop:
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for _, s := range header[key] {
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for {
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var spec AcceptSpec
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spec.Value, s = expectTokenSlash(s)
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if spec.Value == "" {
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continue loop
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}
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spec.Q = 1.0
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s = skipSpace(s)
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if strings.HasPrefix(s, ";") {
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s = skipSpace(s[1:])
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if !strings.HasPrefix(s, "q=") {
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continue loop
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}
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spec.Q, s = expectQuality(s[2:])
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if spec.Q < 0.0 {
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continue loop
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}
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}
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specs = append(specs, spec)
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s = skipSpace(s)
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if !strings.HasPrefix(s, ",") {
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continue loop
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}
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s = skipSpace(s[1:])
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}
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}
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return
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}
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func skipSpace(s string) (rest string) {
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i := 0
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for ; i < len(s); i++ {
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if octetTypes[s[i]]&isSpace == 0 {
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break
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}
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}
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return s[i:]
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}
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func expectTokenSlash(s string) (token, rest string) {
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i := 0
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for ; i < len(s); i++ {
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b := s[i]
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if (octetTypes[b]&isToken == 0) && b != '/' {
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break
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}
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}
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return s[:i], s[i:]
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}
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func expectQuality(s string) (q float64, rest string) {
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switch {
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case len(s) == 0:
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return -1, ""
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case s[0] == '0':
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q = 0
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case s[0] == '1':
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q = 1
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default:
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return -1, ""
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}
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s = s[1:]
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if !strings.HasPrefix(s, ".") {
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return q, s
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}
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s = s[1:]
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i := 0
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n := 0
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d := 1
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for ; i < len(s); i++ {
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b := s[i]
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if b < '0' || b > '9' {
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break
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}
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n = n*10 + int(b) - '0'
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d *= 10
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}
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return q + float64(n)/float64(d), s[i:]
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}
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