1// Copyright (C) 2013-2018 by Maxim Bublis <b@codemonkey.ru>
2//
3// Permission is hereby granted, free of charge, to any person obtaining
4// a copy of this software and associated documentation files (the
5// "Software"), to deal in the Software without restriction, including
6// without limitation the rights to use, copy, modify, merge, publish,
7// distribute, sublicense, and/or sell copies of the Software, and to
8// permit persons to whom the Software is furnished to do so, subject to
9// the following conditions:
10//
11// The above copyright notice and this permission notice shall be
12// included in all copies or substantial portions of the Software.
13//
14// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
15// EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
16// MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
17// NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE
18// LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION
19// OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION
20// WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
21
22// Package uuid provides implementation of Universally Unique Identifier (UUID).
23// Supported versions are 1, 3, 4 and 5 (as specified in RFC 4122) and
24// version 2 (as specified in DCE 1.1).
25package uuid
26
27import (
28 "bytes"
29 "encoding/hex"
30)
31
32// Size of a UUID in bytes.
33const Size = 16
34
35// UUID representation compliant with specification
36// described in RFC 4122.
37type UUID [Size]byte
38
39// UUID versions
40const (
41 _ byte = iota
42 V1
43 V2
44 V3
45 V4
46 V5
47)
48
49// UUID layout variants.
50const (
51 VariantNCS byte = iota
52 VariantRFC4122
53 VariantMicrosoft
54 VariantFuture
55)
56
57// UUID DCE domains.
58const (
59 DomainPerson = iota
60 DomainGroup
61 DomainOrg
62)
63
64// String parse helpers.
65var (
66 urnPrefix = []byte("urn:uuid:")
67 byteGroups = []int{8, 4, 4, 4, 12}
68)
69
70// Nil is special form of UUID that is specified to have all
71// 128 bits set to zero.
72var Nil = UUID{}
73
74// Predefined namespace UUIDs.
75var (
76 NamespaceDNS = Must(FromString("6ba7b810-9dad-11d1-80b4-00c04fd430c8"))
77 NamespaceURL = Must(FromString("6ba7b811-9dad-11d1-80b4-00c04fd430c8"))
78 NamespaceOID = Must(FromString("6ba7b812-9dad-11d1-80b4-00c04fd430c8"))
79 NamespaceX500 = Must(FromString("6ba7b814-9dad-11d1-80b4-00c04fd430c8"))
80)
81
82// Equal returns true if u1 and u2 equals, otherwise returns false.
83func Equal(u1 UUID, u2 UUID) bool {
84 return bytes.Equal(u1[:], u2[:])
85}
86
87// Version returns algorithm version used to generate UUID.
88func (u UUID) Version() byte {
89 return u[6] >> 4
90}
91
92// Variant returns UUID layout variant.
93func (u UUID) Variant() byte {
94 switch {
95 case (u[8] >> 7) == 0x00:
96 return VariantNCS
97 case (u[8] >> 6) == 0x02:
98 return VariantRFC4122
99 case (u[8] >> 5) == 0x06:
100 return VariantMicrosoft
101 case (u[8] >> 5) == 0x07:
102 fallthrough
103 default:
104 return VariantFuture
105 }
106}
107
108// Bytes returns bytes slice representation of UUID.
109func (u UUID) Bytes() []byte {
110 return u[:]
111}
112
113// Returns canonical string representation of UUID:
114// xxxxxxxx-xxxx-xxxx-xxxx-xxxxxxxxxxxx.
115func (u UUID) String() string {
116 buf := make([]byte, 36)
117
118 hex.Encode(buf[0:8], u[0:4])
119 buf[8] = '-'
120 hex.Encode(buf[9:13], u[4:6])
121 buf[13] = '-'
122 hex.Encode(buf[14:18], u[6:8])
123 buf[18] = '-'
124 hex.Encode(buf[19:23], u[8:10])
125 buf[23] = '-'
126 hex.Encode(buf[24:], u[10:])
127
128 return string(buf)
129}
130
131// SetVersion sets version bits.
132func (u *UUID) SetVersion(v byte) {
133 u[6] = (u[6] & 0x0f) | (v << 4)
134}
135
136// SetVariant sets variant bits.
137func (u *UUID) SetVariant(v byte) {
138 switch v {
139 case VariantNCS:
140 u[8] = (u[8]&(0xff>>1) | (0x00 << 7))
141 case VariantRFC4122:
142 u[8] = (u[8]&(0xff>>2) | (0x02 << 6))
143 case VariantMicrosoft:
144 u[8] = (u[8]&(0xff>>3) | (0x06 << 5))
145 case VariantFuture:
146 fallthrough
147 default:
148 u[8] = (u[8]&(0xff>>3) | (0x07 << 5))
149 }
150}
151
152// Must is a helper that wraps a call to a function returning (UUID, error)
153// and panics if the error is non-nil. It is intended for use in variable
154// initializations such as
155// var packageUUID = uuid.Must(uuid.FromString("123e4567-e89b-12d3-a456-426655440000"));
156func Must(u UUID, err error) UUID {
157 if err != nil {
158 panic(err)
159 }
160 return u
161}