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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.
package http
import (
"strings"
"unicode/utf8"
)
// This file deals with lexical matters of HTTP
var isTokenTable = [127]bool{
'!': true,
'#': true,
'$': true,
'%': true,
'&': true,
'\'': true,
'*': true,
'+': true,
'-': true,
'.': true,
'0': true,
'1': true,
'2': true,
'3': true,
'4': true,
'5': true,
'6': true,
'7': true,
'8': true,
'9': true,
'A': true,
'B': true,
'C': true,
'D': true,
'E': true,
'F': true,
'G': true,
'H': true,
'I': true,
'J': true,
'K': true,
'L': true,
'M': true,
'N': true,
'O': true,
'P': true,
'Q': true,
'R': true,
'S': true,
'T': true,
'U': true,
'W': true,
'V': true,
'X': true,
'Y': true,
'Z': true,
'^': true,
'_': true,
'`': true,
'a': true,
'b': true,
'c': true,
'd': true,
'e': true,
'f': true,
'g': true,
'h': true,
'i': true,
'j': true,
'k': true,
'l': true,
'm': true,
'n': true,
'o': true,
'p': true,
'q': true,
'r': true,
's': true,
't': true,
'u': true,
'v': true,
'w': true,
'x': true,
'y': true,
'z': true,
'|': true,
'~': true,
}
func isToken(r rune) bool {
i := int(r)
return i < len(isTokenTable) && isTokenTable[i]
}
func isNotToken(r rune) bool {
return !isToken(r)
}
// headerValuesContainsToken reports whether any string in values
// contains the provided token, ASCII case-insensitively.
func headerValuesContainsToken(values []string, token string) bool {
for _, v := range values {
if headerValueContainsToken(v, token) {
return true
}
}
return false
}
// isOWS reports whether b is an optional whitespace byte, as defined
// by RFC 7230 section 3.2.3.
func isOWS(b byte) bool { return b == ' ' || b == '\t' }
// trimOWS returns x with all optional whitespace removes from the
// beginning and end.
func trimOWS(x string) string {
// TODO: consider using strings.Trim(x, " \t") instead,
// if and when it's fast enough. See issue 10292.
// But this ASCII-only code will probably always beat UTF-8
// aware code.
for len(x) > 0 && isOWS(x[0]) {
x = x[1:]
}
for len(x) > 0 && isOWS(x[len(x)-1]) {
x = x[:len(x)-1]
}
return x
}
// headerValueContainsToken reports whether v (assumed to be a
// 0#element, in the ABNF extension described in RFC 7230 section 7)
// contains token amongst its comma-separated tokens, ASCII
// case-insensitively.
func headerValueContainsToken(v string, token string) bool {
v = trimOWS(v)
if comma := strings.IndexByte(v, ','); comma != -1 {
return tokenEqual(trimOWS(v[:comma]), token) || headerValueContainsToken(v[comma+1:], token)
}
return tokenEqual(v, token)
}
// lowerASCII returns the ASCII lowercase version of b.
func lowerASCII(b byte) byte {
if 'A' <= b && b <= 'Z' {
return b + ('a' - 'A')
}
return b
}
// tokenEqual reports whether t1 and t2 are equal, ASCII case-insensitively.
func tokenEqual(t1, t2 string) bool {
if len(t1) != len(t2) {
return false
}
for i, b := range t1 {
if b >= utf8.RuneSelf {
// No UTF-8 or non-ASCII allowed in tokens.
return false
}
if lowerASCII(byte(b)) != lowerASCII(t2[i]) {
return false
}
}
return true
}
// isLWS reports whether b is linear white space, according
// to http://www.w3.org/Protocols/rfc2616/rfc2616-sec2.html#sec2.2
// LWS = [CRLF] 1*( SP | HT )
func isLWS(b byte) bool { return b == ' ' || b == '\t' }
// isCTL reports whether b is a control byte, according
// to http://www.w3.org/Protocols/rfc2616/rfc2616-sec2.html#sec2.2
// CTL = <any US-ASCII control character
// (octets 0 - 31) and DEL (127)>
func isCTL(b byte) bool {
const del = 0x7f // a CTL
return b < ' ' || b == del
}
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