1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
|
// Copyright (c) 2012 The gocql Authors. 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 can be used to generate and parse universally unique
// identifiers, a standardized format in the form of a 128 bit number.
//
// http://tools.ietf.org/html/rfc4122
package uuid
import (
"crypto/rand"
"encoding/hex"
"errors"
"io"
"net"
"strconv"
"time"
)
type UUID [16]byte
var hardwareAddr []byte
const (
VariantNCSCompat = 0
VariantIETF = 2
VariantMicrosoft = 6
VariantFuture = 7
)
func init() {
if interfaces, err := net.Interfaces(); err == nil {
for _, i := range interfaces {
if i.Flags&net.FlagLoopback == 0 && len(i.HardwareAddr) > 0 {
hardwareAddr = i.HardwareAddr
break
}
}
}
if hardwareAddr == nil {
// If we failed to obtain the MAC address of the current computer,
// we will use a randomly generated 6 byte sequence instead and set
// the multicast bit as recommended in RFC 4122.
hardwareAddr = make([]byte, 6)
_, err := io.ReadFull(rand.Reader, hardwareAddr)
if err != nil {
panic(err)
}
hardwareAddr[0] = hardwareAddr[0] | 0x01
}
}
// Parse parses a 32 digit hexadecimal number (that might contain hyphens)
// representing an UUID.
func Parse(input string) (UUID, error) {
var u UUID
j := 0
for i := 0; i < len(input); i++ {
b := input[i]
switch {
default:
fallthrough
case j == 32:
goto err
case b == '-':
continue
case '0' <= b && b <= '9':
b -= '0'
case 'a' <= b && b <= 'f':
b -= 'a' - 10
case 'A' <= b && b <= 'F':
b -= 'A' - 10
}
u[j/2] |= b << byte(^j&1<<2)
j++
}
if j == 32 {
return u, nil
}
err:
return UUID{}, errors.New("invalid UUID " + strconv.Quote(input))
}
// FromBytes converts a raw byte slice to an UUID. It will panic if the slice
// isn't exactly 16 bytes long.
func FromBytes(input []byte) UUID {
var u UUID
if len(input) != 16 {
panic("UUIDs must be exactly 16 bytes long")
}
copy(u[:], input)
return u
}
// NewRandom generates a totally random UUID (version 4) as described in
// RFC 4122.
func NewRandom() UUID {
var u UUID
io.ReadFull(rand.Reader, u[:])
u[6] &= 0x0F // clear version
u[6] |= 0x40 // set version to 4 (random uuid)
u[8] &= 0x3F // clear variant
u[8] |= 0x80 // set to IETF variant
return u
}
var timeBase = time.Date(1582, time.October, 15, 0, 0, 0, 0, time.UTC).Unix()
// NewTime generates a new time based UUID (version 1) as described in RFC
// 4122. This UUID contains the MAC address of the node that generated the
// UUID, a timestamp and a sequence number.
func NewTime() UUID {
var u UUID
now := time.Now().In(time.UTC)
t := uint64(now.Unix()-timeBase)*10000000 + uint64(now.Nanosecond()/100)
u[0], u[1], u[2], u[3] = byte(t>>24), byte(t>>16), byte(t>>8), byte(t)
u[4], u[5] = byte(t>>40), byte(t>>32)
u[6], u[7] = byte(t>>56)&0x0F, byte(t>>48)
var clockSeq [2]byte
io.ReadFull(rand.Reader, clockSeq[:])
u[8] = clockSeq[1]
u[9] = clockSeq[0]
copy(u[10:], hardwareAddr)
u[6] |= 0x10 // set version to 1 (time based uuid)
u[8] &= 0x3F // clear variant
u[8] |= 0x80 // set to IETF variant
return u
}
// String returns the UUID in it's canonical form, a 32 digit hexadecimal
// number in the form of xxxxxxxx-xxxx-xxxx-xxxx-xxxxxxxxxxxx.
func (u UUID) String() string {
buf := [36]byte{8: '-', 13: '-', 18: '-', 23: '-'}
hex.Encode(buf[0:], u[0:4])
hex.Encode(buf[9:], u[4:6])
hex.Encode(buf[14:], u[6:8])
hex.Encode(buf[19:], u[8:10])
hex.Encode(buf[24:], u[10:])
return string(buf[:])
}
// Bytes returns the raw byte slice for this UUID. A UUID is always 128 bits
// (16 bytes) long.
func (u UUID) Bytes() []byte {
return u[:]
}
// Variant returns the variant of this UUID. This package will only generate
// UUIDs in the IETF variant.
func (u UUID) Variant() int {
x := u[8]
switch byte(0) {
case x & 0x80:
return VariantNCSCompat
case x & 0x40:
return VariantIETF
case x & 0x20:
return VariantMicrosoft
}
return VariantFuture
}
// Version extracts the version of this UUID variant. The RFC 4122 describes
// five kinds of UUIDs.
func (u UUID) Version() int {
return int(u[6] & 0xF0 >> 4)
}
// Node extracts the MAC address of the node who generated this UUID. It will
// return nil if the UUID is not a time based UUID (version 1).
func (u UUID) Node() []byte {
if u.Version() != 1 {
return nil
}
return u[10:]
}
// Timestamp extracts the timestamp information from a time based UUID
// (version 1).
func (u UUID) Timestamp() uint64 {
if u.Version() != 1 {
return 0
}
return uint64(u[0])<<24 + uint64(u[1])<<16 + uint64(u[2])<<8 +
uint64(u[3]) + uint64(u[4])<<40 + uint64(u[5])<<32 +
uint64(u[7])<<48 + uint64(u[6]&0x0F)<<56
}
// Time is like Timestamp, except that it returns a time.Time.
func (u UUID) Time() time.Time {
t := u.Timestamp()
if t == 0 {
return time.Time{}
}
sec := t / 10000000
nsec := t - sec
return time.Unix(int64(sec)+timeBase, int64(nsec))
}
|
