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// Copyright 2018 Google Inc. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.
package uuid
import (
"bytes"
"crypto/rand"
"encoding/hex"
"errors"
"fmt"
"io"
"strings"
)
// A UUID is a 128 bit (16 byte) Universal Unique IDentifier as defined in RFC
// 4122.
type UUID [16]byte
// A Version represents a UUID's version.
type Version byte
// A Variant represents a UUID's variant.
type Variant byte
// Constants returned by Variant.
const (
Invalid = Variant(iota) // Invalid UUID
RFC4122 // The variant specified in RFC4122
Reserved // Reserved, NCS backward compatibility.
Microsoft // Reserved, Microsoft Corporation backward compatibility.
Future // Reserved for future definition.
)
var rander = rand.Reader // random function
// Parse decodes s into a UUID or returns an error. Both the standard UUID
// forms of xxxxxxxx-xxxx-xxxx-xxxx-xxxxxxxxxxxx and
// urn:uuid:xxxxxxxx-xxxx-xxxx-xxxx-xxxxxxxxxxxx are decoded as well as the
// Microsoft encoding {xxxxxxxx-xxxx-xxxx-xxxx-xxxxxxxxxxxx} and the raw hex
// encoding: xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx.
func Parse(s string) (UUID, error) {
var uuid UUID
switch len(s) {
// xxxxxxxx-xxxx-xxxx-xxxx-xxxxxxxxxxxx
case 36:
// urn:uuid:xxxxxxxx-xxxx-xxxx-xxxx-xxxxxxxxxxxx
case 36 + 9:
if strings.ToLower(s[:9]) != "urn:uuid:" {
return uuid, fmt.Errorf("invalid urn prefix: %q", s[:9])
}
s = s[9:]
// {xxxxxxxx-xxxx-xxxx-xxxx-xxxxxxxxxxxx}
case 36 + 2:
s = s[1:]
// xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx
case 32:
var ok bool
for i := range uuid {
uuid[i], ok = xtob(s[i*2], s[i*2+1])
if !ok {
return uuid, errors.New("invalid UUID format")
}
}
return uuid, nil
default:
return uuid, fmt.Errorf("invalid UUID length: %d", len(s))
}
// s is now at least 36 bytes long
// it must be of the form xxxxxxxx-xxxx-xxxx-xxxx-xxxxxxxxxxxx
if s[8] != '-' || s[13] != '-' || s[18] != '-' || s[23] != '-' {
return uuid, errors.New("invalid UUID format")
}
for i, x := range [16]int{
0, 2, 4, 6,
9, 11,
14, 16,
19, 21,
24, 26, 28, 30, 32, 34} {
v, ok := xtob(s[x], s[x+1])
if !ok {
return uuid, errors.New("invalid UUID format")
}
uuid[i] = v
}
return uuid, nil
}
// ParseBytes is like Parse, except it parses a byte slice instead of a string.
func ParseBytes(b []byte) (UUID, error) {
var uuid UUID
switch len(b) {
case 36: // xxxxxxxx-xxxx-xxxx-xxxx-xxxxxxxxxxxx
case 36 + 9: // urn:uuid:xxxxxxxx-xxxx-xxxx-xxxx-xxxxxxxxxxxx
if !bytes.Equal(bytes.ToLower(b[:9]), []byte("urn:uuid:")) {
return uuid, fmt.Errorf("invalid urn prefix: %q", b[:9])
}
b = b[9:]
case 36 + 2: // {xxxxxxxx-xxxx-xxxx-xxxx-xxxxxxxxxxxx}
b = b[1:]
case 32: // xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx
var ok bool
for i := 0; i < 32; i += 2 {
uuid[i/2], ok = xtob(b[i], b[i+1])
if !ok {
return uuid, errors.New("invalid UUID format")
}
}
return uuid, nil
default:
return uuid, fmt.Errorf("invalid UUID length: %d", len(b))
}
// s is now at least 36 bytes long
// it must be of the form xxxxxxxx-xxxx-xxxx-xxxx-xxxxxxxxxxxx
if b[8] != '-' || b[13] != '-' || b[18] != '-' || b[23] != '-' {
return uuid, errors.New("invalid UUID format")
}
for i, x := range [16]int{
0, 2, 4, 6,
9, 11,
14, 16,
19, 21,
24, 26, 28, 30, 32, 34} {
v, ok := xtob(b[x], b[x+1])
if !ok {
return uuid, errors.New("invalid UUID format")
}
uuid[i] = v
}
return uuid, nil
}
// MustParse is like Parse but panics if the string cannot be parsed.
// It simplifies safe initialization of global variables holding compiled UUIDs.
func MustParse(s string) UUID {
uuid, err := Parse(s)
if err != nil {
panic(`uuid: Parse(` + s + `): ` + err.Error())
}
return uuid
}
// FromBytes creates a new UUID from a byte slice. Returns an error if the slice
// does not have a length of 16. The bytes are copied from the slice.
func FromBytes(b []byte) (uuid UUID, err error) {
err = uuid.UnmarshalBinary(b)
return uuid, err
}
// Must returns uuid if err is nil and panics otherwise.
func Must(uuid UUID, err error) UUID {
if err != nil {
panic(err)
}
return uuid
}
// String returns the string form of uuid, xxxxxxxx-xxxx-xxxx-xxxx-xxxxxxxxxxxx
// , or "" if uuid is invalid.
func (uuid UUID) String() string {
var buf [36]byte
encodeHex(buf[:], uuid)
return string(buf[:])
}
// URN returns the RFC 2141 URN form of uuid,
// urn:uuid:xxxxxxxx-xxxx-xxxx-xxxx-xxxxxxxxxxxx, or "" if uuid is invalid.
func (uuid UUID) URN() string {
var buf [36 + 9]byte
copy(buf[:], "urn:uuid:")
encodeHex(buf[9:], uuid)
return string(buf[:])
}
func encodeHex(dst []byte, uuid UUID) {
hex.Encode(dst, uuid[:4])
dst[8] = '-'
hex.Encode(dst[9:13], uuid[4:6])
dst[13] = '-'
hex.Encode(dst[14:18], uuid[6:8])
dst[18] = '-'
hex.Encode(dst[19:23], uuid[8:10])
dst[23] = '-'
hex.Encode(dst[24:], uuid[10:])
}
// Variant returns the variant encoded in uuid.
func (uuid UUID) Variant() Variant {
switch {
case (uuid[8] & 0xc0) == 0x80:
return RFC4122
case (uuid[8] & 0xe0) == 0xc0:
return Microsoft
case (uuid[8] & 0xe0) == 0xe0:
return Future
default:
return Reserved
}
}
// Version returns the version of uuid.
func (uuid UUID) Version() Version {
return Version(uuid[6] >> 4)
}
func (v Version) String() string {
if v > 15 {
return fmt.Sprintf("BAD_VERSION_%d", v)
}
return fmt.Sprintf("VERSION_%d", v)
}
func (v Variant) String() string {
switch v {
case RFC4122:
return "RFC4122"
case Reserved:
return "Reserved"
case Microsoft:
return "Microsoft"
case Future:
return "Future"
case Invalid:
return "Invalid"
}
return fmt.Sprintf("BadVariant%d", int(v))
}
// SetRand sets the random number generator to r, which implements io.Reader.
// If r.Read returns an error when the package requests random data then
// a panic will be issued.
//
// Calling SetRand with nil sets the random number generator to the default
// generator.
func SetRand(r io.Reader) {
if r == nil {
rander = rand.Reader
return
}
rander = r
}
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