352 lines
9.1 KiB
Go
352 lines
9.1 KiB
Go
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// Copyright 2016 The Go Authors. All rights reserved.
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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.
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// Package httplex contains rules around lexical matters of various
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// HTTP-related specifications.
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//
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// This package is shared by the standard library (which vendors it)
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// and x/net/http2. It comes with no API stability promise.
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package httplex
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import (
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"net"
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"strings"
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"unicode/utf8"
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"golang.org/x/net/idna"
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)
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var isTokenTable = [127]bool{
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'!': true,
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'#': true,
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'$': true,
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'%': true,
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'&': true,
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'\'': true,
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'*': true,
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'+': true,
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'-': true,
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'.': true,
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'0': true,
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'1': true,
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'2': true,
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'3': true,
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'4': true,
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'5': true,
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'6': true,
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'7': true,
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'8': true,
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'9': true,
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'A': true,
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'B': true,
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'C': true,
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'D': true,
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'E': true,
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'F': true,
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'G': true,
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'H': true,
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'I': true,
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'J': true,
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'K': true,
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'L': true,
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'M': true,
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'N': true,
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'O': true,
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'P': true,
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'Q': true,
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'R': true,
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'S': true,
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'T': true,
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'U': true,
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'W': true,
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'V': true,
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'X': true,
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'Y': true,
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'Z': true,
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'^': true,
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'_': true,
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'`': true,
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'a': true,
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'b': true,
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'c': true,
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'd': true,
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'e': true,
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'f': true,
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'g': true,
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'h': true,
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'i': true,
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'j': true,
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'k': true,
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'l': true,
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'm': true,
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'n': true,
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'o': true,
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'p': true,
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'q': true,
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'r': true,
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's': true,
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't': true,
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'u': true,
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'v': true,
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'w': true,
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'x': true,
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'y': true,
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'z': true,
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'|': true,
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'~': true,
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}
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func IsTokenRune(r rune) bool {
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i := int(r)
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return i < len(isTokenTable) && isTokenTable[i]
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}
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func isNotToken(r rune) bool {
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return !IsTokenRune(r)
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}
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// HeaderValuesContainsToken reports whether any string in values
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// contains the provided token, ASCII case-insensitively.
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func HeaderValuesContainsToken(values []string, token string) bool {
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for _, v := range values {
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if headerValueContainsToken(v, token) {
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return true
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}
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}
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return false
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}
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// isOWS reports whether b is an optional whitespace byte, as defined
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// by RFC 7230 section 3.2.3.
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func isOWS(b byte) bool { return b == ' ' || b == '\t' }
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// trimOWS returns x with all optional whitespace removes from the
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// beginning and end.
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func trimOWS(x string) string {
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// TODO: consider using strings.Trim(x, " \t") instead,
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// if and when it's fast enough. See issue 10292.
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// But this ASCII-only code will probably always beat UTF-8
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// aware code.
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for len(x) > 0 && isOWS(x[0]) {
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x = x[1:]
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}
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for len(x) > 0 && isOWS(x[len(x)-1]) {
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x = x[:len(x)-1]
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}
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return x
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}
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// headerValueContainsToken reports whether v (assumed to be a
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// 0#element, in the ABNF extension described in RFC 7230 section 7)
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// contains token amongst its comma-separated tokens, ASCII
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// case-insensitively.
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func headerValueContainsToken(v string, token string) bool {
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v = trimOWS(v)
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if comma := strings.IndexByte(v, ','); comma != -1 {
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return tokenEqual(trimOWS(v[:comma]), token) || headerValueContainsToken(v[comma+1:], token)
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}
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return tokenEqual(v, token)
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}
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// lowerASCII returns the ASCII lowercase version of b.
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func lowerASCII(b byte) byte {
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if 'A' <= b && b <= 'Z' {
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return b + ('a' - 'A')
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}
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return b
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}
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// tokenEqual reports whether t1 and t2 are equal, ASCII case-insensitively.
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func tokenEqual(t1, t2 string) bool {
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if len(t1) != len(t2) {
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return false
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}
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for i, b := range t1 {
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if b >= utf8.RuneSelf {
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// No UTF-8 or non-ASCII allowed in tokens.
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return false
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}
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if lowerASCII(byte(b)) != lowerASCII(t2[i]) {
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return false
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}
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}
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return true
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}
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// isLWS reports whether b is linear white space, according
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// to http://www.w3.org/Protocols/rfc2616/rfc2616-sec2.html#sec2.2
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// LWS = [CRLF] 1*( SP | HT )
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func isLWS(b byte) bool { return b == ' ' || b == '\t' }
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// isCTL reports whether b is a control byte, according
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// to http://www.w3.org/Protocols/rfc2616/rfc2616-sec2.html#sec2.2
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// CTL = <any US-ASCII control character
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// (octets 0 - 31) and DEL (127)>
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func isCTL(b byte) bool {
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const del = 0x7f // a CTL
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return b < ' ' || b == del
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}
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// ValidHeaderFieldName reports whether v is a valid HTTP/1.x header name.
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// HTTP/2 imposes the additional restriction that uppercase ASCII
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// letters are not allowed.
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//
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// RFC 7230 says:
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// header-field = field-name ":" OWS field-value OWS
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// field-name = token
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// token = 1*tchar
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// tchar = "!" / "#" / "$" / "%" / "&" / "'" / "*" / "+" / "-" / "." /
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// "^" / "_" / "`" / "|" / "~" / DIGIT / ALPHA
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func ValidHeaderFieldName(v string) bool {
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if len(v) == 0 {
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return false
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}
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for _, r := range v {
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if !IsTokenRune(r) {
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return false
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}
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}
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return true
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}
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// ValidHostHeader reports whether h is a valid host header.
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func ValidHostHeader(h string) bool {
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// The latest spec is actually this:
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//
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// http://tools.ietf.org/html/rfc7230#section-5.4
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// Host = uri-host [ ":" port ]
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//
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// Where uri-host is:
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// http://tools.ietf.org/html/rfc3986#section-3.2.2
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//
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// But we're going to be much more lenient for now and just
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// search for any byte that's not a valid byte in any of those
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// expressions.
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for i := 0; i < len(h); i++ {
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if !validHostByte[h[i]] {
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return false
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}
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}
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return true
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}
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// See the validHostHeader comment.
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var validHostByte = [256]bool{
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'0': true, '1': true, '2': true, '3': true, '4': true, '5': true, '6': true, '7': true,
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'8': true, '9': true,
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'a': true, 'b': true, 'c': true, 'd': true, 'e': true, 'f': true, 'g': true, 'h': true,
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'i': true, 'j': true, 'k': true, 'l': true, 'm': true, 'n': true, 'o': true, 'p': true,
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'q': true, 'r': true, 's': true, 't': true, 'u': true, 'v': true, 'w': true, 'x': true,
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'y': true, 'z': true,
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'A': true, 'B': true, 'C': true, 'D': true, 'E': true, 'F': true, 'G': true, 'H': true,
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'I': true, 'J': true, 'K': true, 'L': true, 'M': true, 'N': true, 'O': true, 'P': true,
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'Q': true, 'R': true, 'S': true, 'T': true, 'U': true, 'V': true, 'W': true, 'X': true,
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'Y': true, 'Z': true,
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'!': true, // sub-delims
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'$': true, // sub-delims
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'%': true, // pct-encoded (and used in IPv6 zones)
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'&': true, // sub-delims
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'(': true, // sub-delims
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')': true, // sub-delims
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'*': true, // sub-delims
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'+': true, // sub-delims
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',': true, // sub-delims
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'-': true, // unreserved
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'.': true, // unreserved
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':': true, // IPv6address + Host expression's optional port
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';': true, // sub-delims
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'=': true, // sub-delims
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'[': true,
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'\'': true, // sub-delims
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']': true,
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'_': true, // unreserved
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'~': true, // unreserved
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}
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// ValidHeaderFieldValue reports whether v is a valid "field-value" according to
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// http://www.w3.org/Protocols/rfc2616/rfc2616-sec4.html#sec4.2 :
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//
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// message-header = field-name ":" [ field-value ]
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// field-value = *( field-content | LWS )
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// field-content = <the OCTETs making up the field-value
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// and consisting of either *TEXT or combinations
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// of token, separators, and quoted-string>
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//
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// http://www.w3.org/Protocols/rfc2616/rfc2616-sec2.html#sec2.2 :
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//
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// TEXT = <any OCTET except CTLs,
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// but including LWS>
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// LWS = [CRLF] 1*( SP | HT )
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// CTL = <any US-ASCII control character
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// (octets 0 - 31) and DEL (127)>
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//
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// RFC 7230 says:
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// field-value = *( field-content / obs-fold )
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// obj-fold = N/A to http2, and deprecated
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// field-content = field-vchar [ 1*( SP / HTAB ) field-vchar ]
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// field-vchar = VCHAR / obs-text
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// obs-text = %x80-FF
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// VCHAR = "any visible [USASCII] character"
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//
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// http2 further says: "Similarly, HTTP/2 allows header field values
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// that are not valid. While most of the values that can be encoded
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// will not alter header field parsing, carriage return (CR, ASCII
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// 0xd), line feed (LF, ASCII 0xa), and the zero character (NUL, ASCII
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// 0x0) might be exploited by an attacker if they are translated
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// verbatim. Any request or response that contains a character not
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// permitted in a header field value MUST be treated as malformed
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// (Section 8.1.2.6). Valid characters are defined by the
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// field-content ABNF rule in Section 3.2 of [RFC7230]."
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//
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// This function does not (yet?) properly handle the rejection of
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// strings that begin or end with SP or HTAB.
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func ValidHeaderFieldValue(v string) bool {
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for i := 0; i < len(v); i++ {
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b := v[i]
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if isCTL(b) && !isLWS(b) {
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return false
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}
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}
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return true
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}
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func isASCII(s string) bool {
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for i := 0; i < len(s); i++ {
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if s[i] >= utf8.RuneSelf {
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return false
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}
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}
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return true
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}
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// PunycodeHostPort returns the IDNA Punycode version
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// of the provided "host" or "host:port" string.
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func PunycodeHostPort(v string) (string, error) {
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if isASCII(v) {
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return v, nil
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}
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host, port, err := net.SplitHostPort(v)
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if err != nil {
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// The input 'v' argument was just a "host" argument,
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// without a port. This error should not be returned
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// to the caller.
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host = v
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port = ""
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}
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host, err = idna.ToASCII(host)
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if err != nil {
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// Non-UTF-8? Not representable in Punycode, in any
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// case.
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return "", err
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}
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if port == "" {
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return host, nil
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}
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return net.JoinHostPort(host, port), nil
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}
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