1 package service
2
3 import (
4 "crypto/md5"
5 "crypto/rand"
6 "encoding/hex"
7 "hash"
8 rand2 "math/rand"
9 )
10
11 type UUID [16]byte
12
13 const numBytes = "1234567890"
14
15 func getUUID() (uuidHex string) {
16 uuid := newUUID()
17 uuidHex = hex.EncodeToString(uuid[:])
18 return
19 }
20
21 func randStringBytes(n int) string {
22 b := make([]byte, n)
23 for i := range b {
24 b[i] = numBytes[rand2.Intn(len(numBytes))]
25 }
26 return string(b)
27 }
28
29 func newUUID() UUID {
30 ns := UUID{}
31 safeRandom(ns[:])
32 u := newFromHash(md5.New(), ns, randStringBytes(16))
33 u[6] = (u[6] & 0x0f) | (byte(2) << 4)
34 u[8] = (u[8]&(0xff>>2) | (0x02 << 6))
35
36 return u
37 }
38
39 func newFromHash(h hash.Hash, ns UUID, name string) UUID {
40 u := UUID{}
41 h.Write(ns[:])
42 h.Write([]byte(name))
43 copy(u[:], h.Sum(nil))
44
45 return u
46 }
47
48 func safeRandom(dest []byte) {
49 if _, err := rand.Read(dest); err != nil {
50 panic(err)
51 }
52 }
53
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