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Copy pathcontext.go
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259 lines (247 loc) · 6 KB
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// Copyright (c) 2015-2021 MinIO, Inc.
//
// This file is part of MinIO Object Storage stack
//
// This program is free software: you can redistribute it and/or modify
// it under the terms of the GNU Affero General Public License as published by
// the Free Software Foundation, either version 3 of the License, or
// (at your option) any later version.
//
// This program is distributed in the hope that it will be useful
// but WITHOUT ANY WARRANTY; without even the implied warranty of
// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
// GNU Affero General Public License for more details.
//
// You should have received a copy of the GNU Affero General Public License
// along with this program. If not, see <http://www.gnu.org/licenses/>.
package kms
import (
"bytes"
"sort"
"unicode/utf8"
)
// Context is a set of key-value pairs that
// are associated with a generate data encryption
// key (DEK).
//
// A KMS implementation may bind the context to the
// generated DEK such that the same context must be
// provided when decrypting an encrypted DEK.
type Context map[string]string
// MarshalText returns a canonical text representation of
// the Context.
// MarshalText sorts the context keys and writes the sorted
// key-value pairs as canonical JSON object. The sort order
// is based on the un-escaped keys. It never returns an error.
func (c Context) MarshalText() ([]byte, error) {
if len(c) == 0 {
return []byte{'{', '}'}, nil
}
// Pre-allocate a buffer - 128 bytes is an arbitrary
// heuristic value that seems like a good starting size.
b := bytes.NewBuffer(make([]byte, 0, 128))
if len(c) == 1 {
for k, v := range c {
b.WriteString(`{"`)
escapeStringJSON(b, k)
b.WriteString(`":"`)
escapeStringJSON(b, v)
b.WriteString(`"}`)
}
return b.Bytes(), nil
}
sortedKeys := make([]string, 0, len(c))
for k := range c {
sortedKeys = append(sortedKeys, k)
}
sort.Strings(sortedKeys)
b.WriteByte('{')
for i, k := range sortedKeys {
b.WriteByte('"')
escapeStringJSON(b, k)
b.WriteString(`":"`)
escapeStringJSON(b, c[k])
b.WriteByte('"')
if i < len(sortedKeys)-1 {
b.WriteByte(',')
}
}
b.WriteByte('}')
return b.Bytes(), nil
}
// Adapted from Go stdlib.
var hexTable = "0123456789abcdef"
// escapeStringJSON will escape a string for JSON and write it to dst.
func escapeStringJSON(dst *bytes.Buffer, s string) {
start := 0
for i := 0; i < len(s); {
if b := s[i]; b < utf8.RuneSelf {
if htmlSafeSet[b] {
i++
continue
}
if start < i {
dst.WriteString(s[start:i])
}
dst.WriteByte('\\')
switch b {
case '\\', '"':
dst.WriteByte(b)
case '\n':
dst.WriteByte('n')
case '\r':
dst.WriteByte('r')
case '\t':
dst.WriteByte('t')
default:
// This encodes bytes < 0x20 except for \t, \n and \r.
// If escapeHTML is set, it also escapes <, >, and &
// because they can lead to security holes when
// user-controlled strings are rendered into JSON
// and served to some browsers.
dst.WriteString(`u00`)
dst.WriteByte(hexTable[b>>4])
dst.WriteByte(hexTable[b&0xF])
}
i++
start = i
continue
}
c, size := utf8.DecodeRuneInString(s[i:])
if c == utf8.RuneError && size == 1 {
if start < i {
dst.WriteString(s[start:i])
}
dst.WriteString(`\ufffd`)
i += size
start = i
continue
}
// U+2028 is LINE SEPARATOR.
// U+2029 is PARAGRAPH SEPARATOR.
// They are both technically valid characters in JSON strings,
// but don't work in JSONP, which has to be evaluated as JavaScript,
// and can lead to security holes there. It is valid JSON to
<
A6E6
div>
// escape them, so we do so unconditionally.
// See http://timelessrepo.com/json-isnt-a-javascript-subset for discussion.
if c == '\u2028' || c == '\u2029' {
if start < i {
dst.WriteString(s[start:i])
}
dst.WriteString(`\u202`)
dst.WriteByte(hexTable[c&0xF])
i += size
start = i
continue
}
i += size
}
if start < len(s) {
dst.WriteString(s[start:])
}
}
// htmlSafeSet holds the value true if the ASCII character with the given
// array position can be safely represented inside a JSON string, embedded
// inside of HTML <script> tags, without any additional escaping.
//
// All values are true except for the ASCII control characters (0-31), the
// double quote ("), the backslash character ("\"), HTML opening and closing
// tags ("<" and ">"), and the ampersand ("&").
var htmlSafeSet = [utf8.RuneSelf]bool{
' ': true,
'!': true,
'"': false,
'#': true,
'$': true,
'%': true,
'&': false,
'\'': 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,
':': true,
';': true,
'<': false,
'=': true,
'>': false,
'?': 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,
'\\': false,
']': 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,
'}': true,
'~': true,
'\u007f': true,
}