54 lines
1.3 KiB
Go
54 lines
1.3 KiB
Go
// Copyright 2021 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 http2
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import "strings"
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// The HTTP protocols are defined in terms of ASCII, not Unicode. This file
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// contains helper functions which may use Unicode-aware functions which would
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// otherwise be unsafe and could introduce vulnerabilities if used improperly.
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// asciiEqualFold is strings.EqualFold, ASCII only. It reports whether s and t
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// are equal, ASCII-case-insensitively.
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func asciiEqualFold(s, t string) bool {
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if len(s) != len(t) {
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return false
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}
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for i := 0; i < len(s); i++ {
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if lower(s[i]) != lower(t[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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// lower returns the ASCII lowercase version of b.
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func lower(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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// isASCIIPrint returns whether s is ASCII and printable according to
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// https://tools.ietf.org/html/rfc20#section-4.2.
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func isASCIIPrint(s string) bool {
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for i := 0; i < len(s); i++ {
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if s[i] < ' ' || s[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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// asciiToLower returns the lowercase version of s if s is ASCII and printable,
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// and whether or not it was.
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func asciiToLower(s string) (lower string, ok bool) {
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if !isASCIIPrint(s) {
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return "", false
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}
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return strings.ToLower(s), true
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}
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