mirror of
https://github.com/minio/minio
synced 2024-07-21 10:25:00 +00:00
260 lines
6 KiB
Go
260 lines
6 KiB
Go
// Copyright (c) 2015-2021 MinIO, Inc.
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//
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// This file is part of MinIO Object Storage stack
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//
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// This program is free software: you can redistribute it and/or modify
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// it under the terms of the GNU Affero General Public License as published by
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// the Free Software Foundation, either version 3 of the License, or
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// (at your option) any later version.
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//
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// This program is distributed in the hope that it will be useful
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// but WITHOUT ANY WARRANTY; without even the implied warranty of
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// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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// GNU Affero General Public License for more details.
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//
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// You should have received a copy of the GNU Affero General Public License
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// along with this program. If not, see <http://www.gnu.org/licenses/>.
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package kms
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import (
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"bytes"
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"sort"
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"unicode/utf8"
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)
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// Context is a set of key-value pairs that
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// are associated with a generate data encryption
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// key (DEK).
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//
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// A KMS implementation may bind the context to the
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// generated DEK such that the same context must be
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// provided when decrypting an encrypted DEK.
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type Context map[string]string
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// MarshalText returns a canonical text representation of
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// the Context.
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// MarshalText sorts the context keys and writes the sorted
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// key-value pairs as canonical JSON object. The sort order
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// is based on the un-escaped keys. It never returns an error.
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func (c Context) MarshalText() ([]byte, error) {
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if len(c) == 0 {
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return []byte{'{', '}'}, nil
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}
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// Pre-allocate a buffer - 128 bytes is an arbitrary
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// heuristic value that seems like a good starting size.
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b := bytes.NewBuffer(make([]byte, 0, 128))
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if len(c) == 1 {
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for k, v := range c {
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b.WriteString(`{"`)
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escapeStringJSON(b, k)
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b.WriteString(`":"`)
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escapeStringJSON(b, v)
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b.WriteString(`"}`)
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}
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return b.Bytes(), nil
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}
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sortedKeys := make([]string, 0, len(c))
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for k := range c {
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sortedKeys = append(sortedKeys, k)
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}
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sort.Strings(sortedKeys)
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b.WriteByte('{')
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for i, k := range sortedKeys {
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b.WriteByte('"')
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escapeStringJSON(b, k)
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b.WriteString(`":"`)
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escapeStringJSON(b, c[k])
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b.WriteByte('"')
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if i < len(sortedKeys)-1 {
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b.WriteByte(',')
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}
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}
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b.WriteByte('}')
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return b.Bytes(), nil
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}
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// Adapted from Go stdlib.
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var hexTable = "0123456789abcdef"
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// escapeStringJSON will escape a string for JSON and write it to dst.
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func escapeStringJSON(dst *bytes.Buffer, s string) {
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start := 0
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for i := 0; i < len(s); {
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if b := s[i]; b < utf8.RuneSelf {
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if htmlSafeSet[b] {
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i++
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continue
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}
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if start < i {
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dst.WriteString(s[start:i])
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}
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dst.WriteByte('\\')
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switch b {
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case '\\', '"':
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dst.WriteByte(b)
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case '\n':
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dst.WriteByte('n')
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case '\r':
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dst.WriteByte('r')
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case '\t':
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dst.WriteByte('t')
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default:
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// This encodes bytes < 0x20 except for \t, \n and \r.
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// If escapeHTML is set, it also escapes <, >, and &
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// because they can lead to security holes when
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// user-controlled strings are rendered into JSON
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// and served to some browsers.
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dst.WriteString(`u00`)
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dst.WriteByte(hexTable[b>>4])
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dst.WriteByte(hexTable[b&0xF])
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}
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i++
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start = i
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continue
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}
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c, size := utf8.DecodeRuneInString(s[i:])
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if c == utf8.RuneError && size == 1 {
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if start < i {
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dst.WriteString(s[start:i])
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}
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dst.WriteString(`\ufffd`)
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i += size
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start = i
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continue
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}
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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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if c == '\u2028' || c == '\u2029' {
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if start < i {
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dst.WriteString(s[start:i])
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}
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dst.WriteString(`\u202`)
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dst.WriteByte(hexTable[c&0xF])
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i += size
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start = i
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continue
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}
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i += size
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}
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if start < len(s) {
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dst.WriteString(s[start:])
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}
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}
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// htmlSafeSet holds the value true if the ASCII character with the given
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// array position can be safely represented inside a JSON string, embedded
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// inside of HTML <script> tags, without any additional escaping.
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//
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// All values are true except for the ASCII control characters (0-31), the
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// double quote ("), the backslash character ("\"), HTML opening and closing
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// tags ("<" and ">"), and the ampersand ("&").
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var htmlSafeSet = [utf8.RuneSelf]bool{
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' ': true,
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'!': true,
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'"': false,
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'#': true,
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'$': true,
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'%': true,
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'&': false,
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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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':': true,
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';': true,
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'<': false,
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'=': true,
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'>': false,
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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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'\\': false,
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']': 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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'}': true,
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'~': true,
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'\u007f': true,
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}
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