William Kurkian | ea86948 | 2019-04-09 15:16:11 -0400 | [diff] [blame] | 1 | // Copyright 2018 Google Inc. All rights reserved. |
| 2 | // Use of this source code is governed by a BSD-style |
| 3 | // license that can be found in the LICENSE file. |
| 4 | |
| 5 | package uuid |
| 6 | |
| 7 | import ( |
| 8 | "bytes" |
| 9 | "crypto/rand" |
| 10 | "encoding/hex" |
| 11 | "errors" |
| 12 | "fmt" |
| 13 | "io" |
| 14 | "strings" |
khenaidoo | 106c61a | 2021-08-11 18:05:46 -0400 | [diff] [blame^] | 15 | "sync" |
William Kurkian | ea86948 | 2019-04-09 15:16:11 -0400 | [diff] [blame] | 16 | ) |
| 17 | |
| 18 | // A UUID is a 128 bit (16 byte) Universal Unique IDentifier as defined in RFC |
| 19 | // 4122. |
| 20 | type UUID [16]byte |
| 21 | |
| 22 | // A Version represents a UUID's version. |
| 23 | type Version byte |
| 24 | |
| 25 | // A Variant represents a UUID's variant. |
| 26 | type Variant byte |
| 27 | |
| 28 | // Constants returned by Variant. |
| 29 | const ( |
| 30 | Invalid = Variant(iota) // Invalid UUID |
| 31 | RFC4122 // The variant specified in RFC4122 |
| 32 | Reserved // Reserved, NCS backward compatibility. |
| 33 | Microsoft // Reserved, Microsoft Corporation backward compatibility. |
| 34 | Future // Reserved for future definition. |
| 35 | ) |
| 36 | |
khenaidoo | 106c61a | 2021-08-11 18:05:46 -0400 | [diff] [blame^] | 37 | const randPoolSize = 16 * 16 |
| 38 | |
| 39 | var ( |
| 40 | rander = rand.Reader // random function |
| 41 | poolEnabled = false |
| 42 | poolMu sync.Mutex |
| 43 | poolPos = randPoolSize // protected with poolMu |
| 44 | pool [randPoolSize]byte // protected with poolMu |
| 45 | ) |
| 46 | |
| 47 | type invalidLengthError struct{ len int } |
| 48 | |
| 49 | func (err invalidLengthError) Error() string { |
| 50 | return fmt.Sprintf("invalid UUID length: %d", err.len) |
| 51 | } |
| 52 | |
| 53 | // IsInvalidLengthError is matcher function for custom error invalidLengthError |
| 54 | func IsInvalidLengthError(err error) bool { |
| 55 | _, ok := err.(invalidLengthError) |
| 56 | return ok |
| 57 | } |
William Kurkian | ea86948 | 2019-04-09 15:16:11 -0400 | [diff] [blame] | 58 | |
| 59 | // Parse decodes s into a UUID or returns an error. Both the standard UUID |
| 60 | // forms of xxxxxxxx-xxxx-xxxx-xxxx-xxxxxxxxxxxx and |
| 61 | // urn:uuid:xxxxxxxx-xxxx-xxxx-xxxx-xxxxxxxxxxxx are decoded as well as the |
| 62 | // Microsoft encoding {xxxxxxxx-xxxx-xxxx-xxxx-xxxxxxxxxxxx} and the raw hex |
| 63 | // encoding: xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx. |
| 64 | func Parse(s string) (UUID, error) { |
| 65 | var uuid UUID |
| 66 | switch len(s) { |
| 67 | // xxxxxxxx-xxxx-xxxx-xxxx-xxxxxxxxxxxx |
| 68 | case 36: |
| 69 | |
| 70 | // urn:uuid:xxxxxxxx-xxxx-xxxx-xxxx-xxxxxxxxxxxx |
| 71 | case 36 + 9: |
| 72 | if strings.ToLower(s[:9]) != "urn:uuid:" { |
| 73 | return uuid, fmt.Errorf("invalid urn prefix: %q", s[:9]) |
| 74 | } |
| 75 | s = s[9:] |
| 76 | |
| 77 | // {xxxxxxxx-xxxx-xxxx-xxxx-xxxxxxxxxxxx} |
| 78 | case 36 + 2: |
| 79 | s = s[1:] |
| 80 | |
| 81 | // xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx |
| 82 | case 32: |
| 83 | var ok bool |
| 84 | for i := range uuid { |
| 85 | uuid[i], ok = xtob(s[i*2], s[i*2+1]) |
| 86 | if !ok { |
| 87 | return uuid, errors.New("invalid UUID format") |
| 88 | } |
| 89 | } |
| 90 | return uuid, nil |
| 91 | default: |
khenaidoo | 106c61a | 2021-08-11 18:05:46 -0400 | [diff] [blame^] | 92 | return uuid, invalidLengthError{len(s)} |
William Kurkian | ea86948 | 2019-04-09 15:16:11 -0400 | [diff] [blame] | 93 | } |
| 94 | // s is now at least 36 bytes long |
| 95 | // it must be of the form xxxxxxxx-xxxx-xxxx-xxxx-xxxxxxxxxxxx |
| 96 | if s[8] != '-' || s[13] != '-' || s[18] != '-' || s[23] != '-' { |
| 97 | return uuid, errors.New("invalid UUID format") |
| 98 | } |
| 99 | for i, x := range [16]int{ |
| 100 | 0, 2, 4, 6, |
| 101 | 9, 11, |
| 102 | 14, 16, |
| 103 | 19, 21, |
| 104 | 24, 26, 28, 30, 32, 34} { |
| 105 | v, ok := xtob(s[x], s[x+1]) |
| 106 | if !ok { |
| 107 | return uuid, errors.New("invalid UUID format") |
| 108 | } |
| 109 | uuid[i] = v |
| 110 | } |
| 111 | return uuid, nil |
| 112 | } |
| 113 | |
| 114 | // ParseBytes is like Parse, except it parses a byte slice instead of a string. |
| 115 | func ParseBytes(b []byte) (UUID, error) { |
| 116 | var uuid UUID |
| 117 | switch len(b) { |
| 118 | case 36: // xxxxxxxx-xxxx-xxxx-xxxx-xxxxxxxxxxxx |
| 119 | case 36 + 9: // urn:uuid:xxxxxxxx-xxxx-xxxx-xxxx-xxxxxxxxxxxx |
| 120 | if !bytes.Equal(bytes.ToLower(b[:9]), []byte("urn:uuid:")) { |
| 121 | return uuid, fmt.Errorf("invalid urn prefix: %q", b[:9]) |
| 122 | } |
| 123 | b = b[9:] |
| 124 | case 36 + 2: // {xxxxxxxx-xxxx-xxxx-xxxx-xxxxxxxxxxxx} |
| 125 | b = b[1:] |
| 126 | case 32: // xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx |
| 127 | var ok bool |
| 128 | for i := 0; i < 32; i += 2 { |
| 129 | uuid[i/2], ok = xtob(b[i], b[i+1]) |
| 130 | if !ok { |
| 131 | return uuid, errors.New("invalid UUID format") |
| 132 | } |
| 133 | } |
| 134 | return uuid, nil |
| 135 | default: |
khenaidoo | 106c61a | 2021-08-11 18:05:46 -0400 | [diff] [blame^] | 136 | return uuid, invalidLengthError{len(b)} |
William Kurkian | ea86948 | 2019-04-09 15:16:11 -0400 | [diff] [blame] | 137 | } |
| 138 | // s is now at least 36 bytes long |
| 139 | // it must be of the form xxxxxxxx-xxxx-xxxx-xxxx-xxxxxxxxxxxx |
| 140 | if b[8] != '-' || b[13] != '-' || b[18] != '-' || b[23] != '-' { |
| 141 | return uuid, errors.New("invalid UUID format") |
| 142 | } |
| 143 | for i, x := range [16]int{ |
| 144 | 0, 2, 4, 6, |
| 145 | 9, 11, |
| 146 | 14, 16, |
| 147 | 19, 21, |
| 148 | 24, 26, 28, 30, 32, 34} { |
| 149 | v, ok := xtob(b[x], b[x+1]) |
| 150 | if !ok { |
| 151 | return uuid, errors.New("invalid UUID format") |
| 152 | } |
| 153 | uuid[i] = v |
| 154 | } |
| 155 | return uuid, nil |
| 156 | } |
| 157 | |
| 158 | // MustParse is like Parse but panics if the string cannot be parsed. |
| 159 | // It simplifies safe initialization of global variables holding compiled UUIDs. |
| 160 | func MustParse(s string) UUID { |
| 161 | uuid, err := Parse(s) |
| 162 | if err != nil { |
| 163 | panic(`uuid: Parse(` + s + `): ` + err.Error()) |
| 164 | } |
| 165 | return uuid |
| 166 | } |
| 167 | |
| 168 | // FromBytes creates a new UUID from a byte slice. Returns an error if the slice |
| 169 | // does not have a length of 16. The bytes are copied from the slice. |
| 170 | func FromBytes(b []byte) (uuid UUID, err error) { |
| 171 | err = uuid.UnmarshalBinary(b) |
| 172 | return uuid, err |
| 173 | } |
| 174 | |
| 175 | // Must returns uuid if err is nil and panics otherwise. |
| 176 | func Must(uuid UUID, err error) UUID { |
| 177 | if err != nil { |
| 178 | panic(err) |
| 179 | } |
| 180 | return uuid |
| 181 | } |
| 182 | |
| 183 | // String returns the string form of uuid, xxxxxxxx-xxxx-xxxx-xxxx-xxxxxxxxxxxx |
| 184 | // , or "" if uuid is invalid. |
| 185 | func (uuid UUID) String() string { |
| 186 | var buf [36]byte |
| 187 | encodeHex(buf[:], uuid) |
| 188 | return string(buf[:]) |
| 189 | } |
| 190 | |
| 191 | // URN returns the RFC 2141 URN form of uuid, |
| 192 | // urn:uuid:xxxxxxxx-xxxx-xxxx-xxxx-xxxxxxxxxxxx, or "" if uuid is invalid. |
| 193 | func (uuid UUID) URN() string { |
| 194 | var buf [36 + 9]byte |
| 195 | copy(buf[:], "urn:uuid:") |
| 196 | encodeHex(buf[9:], uuid) |
| 197 | return string(buf[:]) |
| 198 | } |
| 199 | |
| 200 | func encodeHex(dst []byte, uuid UUID) { |
| 201 | hex.Encode(dst, uuid[:4]) |
| 202 | dst[8] = '-' |
| 203 | hex.Encode(dst[9:13], uuid[4:6]) |
| 204 | dst[13] = '-' |
| 205 | hex.Encode(dst[14:18], uuid[6:8]) |
| 206 | dst[18] = '-' |
| 207 | hex.Encode(dst[19:23], uuid[8:10]) |
| 208 | dst[23] = '-' |
| 209 | hex.Encode(dst[24:], uuid[10:]) |
| 210 | } |
| 211 | |
| 212 | // Variant returns the variant encoded in uuid. |
| 213 | func (uuid UUID) Variant() Variant { |
| 214 | switch { |
| 215 | case (uuid[8] & 0xc0) == 0x80: |
| 216 | return RFC4122 |
| 217 | case (uuid[8] & 0xe0) == 0xc0: |
| 218 | return Microsoft |
| 219 | case (uuid[8] & 0xe0) == 0xe0: |
| 220 | return Future |
| 221 | default: |
| 222 | return Reserved |
| 223 | } |
| 224 | } |
| 225 | |
| 226 | // Version returns the version of uuid. |
| 227 | func (uuid UUID) Version() Version { |
| 228 | return Version(uuid[6] >> 4) |
| 229 | } |
| 230 | |
| 231 | func (v Version) String() string { |
| 232 | if v > 15 { |
| 233 | return fmt.Sprintf("BAD_VERSION_%d", v) |
| 234 | } |
| 235 | return fmt.Sprintf("VERSION_%d", v) |
| 236 | } |
| 237 | |
| 238 | func (v Variant) String() string { |
| 239 | switch v { |
| 240 | case RFC4122: |
| 241 | return "RFC4122" |
| 242 | case Reserved: |
| 243 | return "Reserved" |
| 244 | case Microsoft: |
| 245 | return "Microsoft" |
| 246 | case Future: |
| 247 | return "Future" |
| 248 | case Invalid: |
| 249 | return "Invalid" |
| 250 | } |
| 251 | return fmt.Sprintf("BadVariant%d", int(v)) |
| 252 | } |
| 253 | |
| 254 | // SetRand sets the random number generator to r, which implements io.Reader. |
| 255 | // If r.Read returns an error when the package requests random data then |
| 256 | // a panic will be issued. |
| 257 | // |
| 258 | // Calling SetRand with nil sets the random number generator to the default |
| 259 | // generator. |
| 260 | func SetRand(r io.Reader) { |
| 261 | if r == nil { |
| 262 | rander = rand.Reader |
| 263 | return |
| 264 | } |
| 265 | rander = r |
| 266 | } |
khenaidoo | 106c61a | 2021-08-11 18:05:46 -0400 | [diff] [blame^] | 267 | |
| 268 | // EnableRandPool enables internal randomness pool used for Random |
| 269 | // (Version 4) UUID generation. The pool contains random bytes read from |
| 270 | // the random number generator on demand in batches. Enabling the pool |
| 271 | // may improve the UUID generation throughput significantly. |
| 272 | // |
| 273 | // Since the pool is stored on the Go heap, this feature may be a bad fit |
| 274 | // for security sensitive applications. |
| 275 | // |
| 276 | // Both EnableRandPool and DisableRandPool are not thread-safe and should |
| 277 | // only be called when there is no possibility that New or any other |
| 278 | // UUID Version 4 generation function will be called concurrently. |
| 279 | func EnableRandPool() { |
| 280 | poolEnabled = true |
| 281 | } |
| 282 | |
| 283 | // DisableRandPool disables the randomness pool if it was previously |
| 284 | // enabled with EnableRandPool. |
| 285 | // |
| 286 | // Both EnableRandPool and DisableRandPool are not thread-safe and should |
| 287 | // only be called when there is no possibility that New or any other |
| 288 | // UUID Version 4 generation function will be called concurrently. |
| 289 | func DisableRandPool() { |
| 290 | poolEnabled = false |
| 291 | defer poolMu.Unlock() |
| 292 | poolMu.Lock() |
| 293 | poolPos = randPoolSize |
| 294 | } |