484 lines
12 KiB
Go
484 lines
12 KiB
Go
// This files's string processing codes are inspired by https://github.com/segmentio/encoding.
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// The license notation is as follows.
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//
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// # MIT License
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//
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// Copyright (c) 2019 Segment.io, Inc.
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//
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// Permission is hereby granted, free of charge, to any person obtaining a copy
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// of this software and associated documentation files (the "Software"), to deal
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// in the Software without restriction, including without limitation the rights
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// to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
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// copies of the Software, and to permit persons to whom the Software is
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// furnished to do so, subject to the following conditions:
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//
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// The above copyright notice and this permission notice shall be included in all
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// copies or substantial portions of the Software.
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//
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// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
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// IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
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// FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
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// AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
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// LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
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// OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
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// SOFTWARE.
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package encoder
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import (
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"math/bits"
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"reflect"
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"unsafe"
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)
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const (
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lsb = 0x0101010101010101
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msb = 0x8080808080808080
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)
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var hex = "0123456789abcdef"
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//nolint:govet
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func stringToUint64Slice(s string) []uint64 {
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return *(*[]uint64)(unsafe.Pointer(&reflect.SliceHeader{
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Data: ((*reflect.StringHeader)(unsafe.Pointer(&s))).Data,
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Len: len(s) / 8,
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Cap: len(s) / 8,
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}))
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}
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func AppendString(ctx *RuntimeContext, buf []byte, s string) []byte {
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if ctx.Option.Flag&HTMLEscapeOption != 0 {
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if ctx.Option.Flag&NormalizeUTF8Option != 0 {
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return appendNormalizedHTMLString(buf, s)
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}
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return appendHTMLString(buf, s)
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}
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if ctx.Option.Flag&NormalizeUTF8Option != 0 {
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return appendNormalizedString(buf, s)
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}
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return appendString(buf, s)
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}
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func appendNormalizedHTMLString(buf []byte, s string) []byte {
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valLen := len(s)
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if valLen == 0 {
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return append(buf, `""`...)
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}
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buf = append(buf, '"')
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var (
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i, j int
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)
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if valLen >= 8 {
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chunks := stringToUint64Slice(s)
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for _, n := range chunks {
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// combine masks before checking for the MSB of each byte. We include
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// `n` in the mask to check whether any of the *input* byte MSBs were
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// set (i.e. the byte was outside the ASCII range).
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mask := n | (n - (lsb * 0x20)) |
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((n ^ (lsb * '"')) - lsb) |
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((n ^ (lsb * '\\')) - lsb) |
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((n ^ (lsb * '<')) - lsb) |
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((n ^ (lsb * '>')) - lsb) |
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((n ^ (lsb * '&')) - lsb)
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if (mask & msb) != 0 {
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j = bits.TrailingZeros64(mask&msb) / 8
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goto ESCAPE_END
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}
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}
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for i := len(chunks) * 8; i < valLen; i++ {
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if needEscapeHTMLNormalizeUTF8[s[i]] {
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j = i
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goto ESCAPE_END
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}
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}
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// no found any escape characters.
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return append(append(buf, s...), '"')
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}
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ESCAPE_END:
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for j < valLen {
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c := s[j]
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if !needEscapeHTMLNormalizeUTF8[c] {
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// fast path: most of the time, printable ascii characters are used
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j++
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continue
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}
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switch c {
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case '\\', '"':
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buf = append(buf, s[i:j]...)
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buf = append(buf, '\\', c)
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i = j + 1
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j = j + 1
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continue
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case '\n':
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buf = append(buf, s[i:j]...)
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buf = append(buf, '\\', 'n')
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i = j + 1
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j = j + 1
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continue
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case '\r':
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buf = append(buf, s[i:j]...)
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buf = append(buf, '\\', 'r')
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i = j + 1
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j = j + 1
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continue
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case '\t':
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buf = append(buf, s[i:j]...)
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buf = append(buf, '\\', 't')
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i = j + 1
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j = j + 1
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continue
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case '<', '>', '&':
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buf = append(buf, s[i:j]...)
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buf = append(buf, `\u00`...)
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buf = append(buf, hex[c>>4], hex[c&0xF])
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i = j + 1
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j = j + 1
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continue
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case 0x00, 0x01, 0x02, 0x03, 0x04, 0x05, 0x06, 0x07, 0x08, 0x0B, 0x0C, 0x0E, 0x0F, // 0x00-0x0F
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0x10, 0x11, 0x12, 0x13, 0x14, 0x15, 0x16, 0x17, 0x18, 0x19, 0x1A, 0x1B, 0x1C, 0x1D, 0x1E, 0x1F: // 0x10-0x1F
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buf = append(buf, s[i:j]...)
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buf = append(buf, `\u00`...)
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buf = append(buf, hex[c>>4], hex[c&0xF])
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i = j + 1
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j = j + 1
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continue
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}
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state, size := decodeRuneInString(s[j:])
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switch state {
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case runeErrorState:
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buf = append(buf, s[i:j]...)
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buf = append(buf, `\ufffd`...)
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i = j + 1
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j = j + 1
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continue
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// U+2028 is LINE SEPARATOR.
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// U+2029 is PARAGRAPH SEPARATOR.
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// They are both technically valid characters in JSON strings,
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// but don't work in JSONP, which has to be evaluated as JavaScript,
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// and can lead to security holes there. It is valid JSON to
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// escape them, so we do so unconditionally.
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// See http://timelessrepo.com/json-isnt-a-javascript-subset for discussion.
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case lineSepState:
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buf = append(buf, s[i:j]...)
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buf = append(buf, `\u2028`...)
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i = j + 3
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j = j + 3
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continue
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case paragraphSepState:
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buf = append(buf, s[i:j]...)
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buf = append(buf, `\u2029`...)
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i = j + 3
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j = j + 3
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continue
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}
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j += size
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}
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return append(append(buf, s[i:]...), '"')
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}
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func appendHTMLString(buf []byte, s string) []byte {
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valLen := len(s)
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if valLen == 0 {
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return append(buf, `""`...)
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}
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buf = append(buf, '"')
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var (
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i, j int
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)
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if valLen >= 8 {
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chunks := stringToUint64Slice(s)
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for _, n := range chunks {
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// combine masks before checking for the MSB of each byte. We include
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// `n` in the mask to check whether any of the *input* byte MSBs were
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// set (i.e. the byte was outside the ASCII range).
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mask := n | (n - (lsb * 0x20)) |
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((n ^ (lsb * '"')) - lsb) |
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((n ^ (lsb * '\\')) - lsb) |
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((n ^ (lsb * '<')) - lsb) |
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((n ^ (lsb * '>')) - lsb) |
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((n ^ (lsb * '&')) - lsb)
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if (mask & msb) != 0 {
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j = bits.TrailingZeros64(mask&msb) / 8
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goto ESCAPE_END
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}
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}
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for i := len(chunks) * 8; i < valLen; i++ {
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if needEscapeHTML[s[i]] {
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j = i
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goto ESCAPE_END
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}
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}
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// no found any escape characters.
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return append(append(buf, s...), '"')
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}
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ESCAPE_END:
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for j < valLen {
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c := s[j]
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if !needEscapeHTML[c] {
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// fast path: most of the time, printable ascii characters are used
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j++
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continue
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}
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switch c {
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case '\\', '"':
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buf = append(buf, s[i:j]...)
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buf = append(buf, '\\', c)
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i = j + 1
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j = j + 1
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continue
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case '\n':
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buf = append(buf, s[i:j]...)
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buf = append(buf, '\\', 'n')
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i = j + 1
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j = j + 1
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continue
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case '\r':
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buf = append(buf, s[i:j]...)
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buf = append(buf, '\\', 'r')
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i = j + 1
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j = j + 1
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continue
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case '\t':
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buf = append(buf, s[i:j]...)
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buf = append(buf, '\\', 't')
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i = j + 1
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j = j + 1
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continue
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case '<', '>', '&':
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buf = append(buf, s[i:j]...)
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buf = append(buf, `\u00`...)
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buf = append(buf, hex[c>>4], hex[c&0xF])
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i = j + 1
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j = j + 1
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continue
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case 0x00, 0x01, 0x02, 0x03, 0x04, 0x05, 0x06, 0x07, 0x08, 0x0B, 0x0C, 0x0E, 0x0F, // 0x00-0x0F
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0x10, 0x11, 0x12, 0x13, 0x14, 0x15, 0x16, 0x17, 0x18, 0x19, 0x1A, 0x1B, 0x1C, 0x1D, 0x1E, 0x1F: // 0x10-0x1F
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buf = append(buf, s[i:j]...)
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buf = append(buf, `\u00`...)
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buf = append(buf, hex[c>>4], hex[c&0xF])
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i = j + 1
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j = j + 1
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continue
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}
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j++
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}
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return append(append(buf, s[i:]...), '"')
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}
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func appendNormalizedString(buf []byte, s string) []byte {
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valLen := len(s)
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if valLen == 0 {
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return append(buf, `""`...)
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}
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buf = append(buf, '"')
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var (
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i, j int
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)
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if valLen >= 8 {
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chunks := stringToUint64Slice(s)
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for _, n := range chunks {
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// combine masks before checking for the MSB of each byte. We include
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// `n` in the mask to check whether any of the *input* byte MSBs were
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// set (i.e. the byte was outside the ASCII range).
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mask := n | (n - (lsb * 0x20)) |
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((n ^ (lsb * '"')) - lsb) |
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((n ^ (lsb * '\\')) - lsb)
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if (mask & msb) != 0 {
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j = bits.TrailingZeros64(mask&msb) / 8
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goto ESCAPE_END
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}
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}
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valLen := len(s)
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for i := len(chunks) * 8; i < valLen; i++ {
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if needEscapeNormalizeUTF8[s[i]] {
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j = i
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goto ESCAPE_END
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}
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}
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return append(append(buf, s...), '"')
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}
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ESCAPE_END:
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for j < valLen {
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c := s[j]
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if !needEscapeNormalizeUTF8[c] {
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// fast path: most of the time, printable ascii characters are used
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j++
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continue
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}
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switch c {
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case '\\', '"':
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buf = append(buf, s[i:j]...)
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buf = append(buf, '\\', c)
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i = j + 1
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j = j + 1
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continue
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case '\n':
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buf = append(buf, s[i:j]...)
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buf = append(buf, '\\', 'n')
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i = j + 1
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j = j + 1
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continue
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case '\r':
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buf = append(buf, s[i:j]...)
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buf = append(buf, '\\', 'r')
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i = j + 1
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j = j + 1
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continue
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case '\t':
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buf = append(buf, s[i:j]...)
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buf = append(buf, '\\', 't')
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i = j + 1
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j = j + 1
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continue
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case 0x00, 0x01, 0x02, 0x03, 0x04, 0x05, 0x06, 0x07, 0x08, 0x0B, 0x0C, 0x0E, 0x0F, // 0x00-0x0F
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0x10, 0x11, 0x12, 0x13, 0x14, 0x15, 0x16, 0x17, 0x18, 0x19, 0x1A, 0x1B, 0x1C, 0x1D, 0x1E, 0x1F: // 0x10-0x1F
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buf = append(buf, s[i:j]...)
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buf = append(buf, `\u00`...)
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buf = append(buf, hex[c>>4], hex[c&0xF])
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i = j + 1
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j = j + 1
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continue
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}
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state, size := decodeRuneInString(s[j:])
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switch state {
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case runeErrorState:
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buf = append(buf, s[i:j]...)
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buf = append(buf, `\ufffd`...)
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i = j + 1
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j = j + 1
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continue
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// U+2028 is LINE SEPARATOR.
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// U+2029 is PARAGRAPH SEPARATOR.
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// They are both technically valid characters in JSON strings,
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// but don't work in JSONP, which has to be evaluated as JavaScript,
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// and can lead to security holes there. It is valid JSON to
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// escape them, so we do so unconditionally.
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// See http://timelessrepo.com/json-isnt-a-javascript-subset for discussion.
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case lineSepState:
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buf = append(buf, s[i:j]...)
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buf = append(buf, `\u2028`...)
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i = j + 3
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j = j + 3
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continue
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case paragraphSepState:
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buf = append(buf, s[i:j]...)
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buf = append(buf, `\u2029`...)
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i = j + 3
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j = j + 3
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continue
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}
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j += size
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}
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return append(append(buf, s[i:]...), '"')
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}
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func appendString(buf []byte, s string) []byte {
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valLen := len(s)
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if valLen == 0 {
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return append(buf, `""`...)
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}
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buf = append(buf, '"')
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var (
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i, j int
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)
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if valLen >= 8 {
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chunks := stringToUint64Slice(s)
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for _, n := range chunks {
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// combine masks before checking for the MSB of each byte. We include
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// `n` in the mask to check whether any of the *input* byte MSBs were
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// set (i.e. the byte was outside the ASCII range).
|
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mask := n | (n - (lsb * 0x20)) |
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((n ^ (lsb * '"')) - lsb) |
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((n ^ (lsb * '\\')) - lsb)
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if (mask & msb) != 0 {
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j = bits.TrailingZeros64(mask&msb) / 8
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goto ESCAPE_END
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}
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}
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valLen := len(s)
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for i := len(chunks) * 8; i < valLen; i++ {
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if needEscape[s[i]] {
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j = i
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goto ESCAPE_END
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}
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}
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return append(append(buf, s...), '"')
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}
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ESCAPE_END:
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for j < valLen {
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c := s[j]
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if !needEscape[c] {
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// fast path: most of the time, printable ascii characters are used
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j++
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continue
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}
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switch c {
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case '\\', '"':
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buf = append(buf, s[i:j]...)
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buf = append(buf, '\\', c)
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i = j + 1
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j = j + 1
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continue
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case '\n':
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buf = append(buf, s[i:j]...)
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buf = append(buf, '\\', 'n')
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i = j + 1
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j = j + 1
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continue
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case '\r':
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buf = append(buf, s[i:j]...)
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buf = append(buf, '\\', 'r')
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i = j + 1
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j = j + 1
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continue
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case '\t':
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buf = append(buf, s[i:j]...)
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buf = append(buf, '\\', 't')
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i = j + 1
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j = j + 1
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continue
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case 0x00, 0x01, 0x02, 0x03, 0x04, 0x05, 0x06, 0x07, 0x08, 0x0B, 0x0C, 0x0E, 0x0F, // 0x00-0x0F
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0x10, 0x11, 0x12, 0x13, 0x14, 0x15, 0x16, 0x17, 0x18, 0x19, 0x1A, 0x1B, 0x1C, 0x1D, 0x1E, 0x1F: // 0x10-0x1F
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buf = append(buf, s[i:j]...)
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buf = append(buf, `\u00`...)
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buf = append(buf, hex[c>>4], hex[c&0xF])
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i = j + 1
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j = j + 1
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continue
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}
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j++
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}
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return append(append(buf, s[i:]...), '"')
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}
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