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Scott Baker2c1c4822019-10-16 11:02:41 -07001/*
2 * Copyright 2018-present Open Networking Foundation
3
4 * Licensed under the Apache License, Version 2.0 (the "License");
5 * you may not use this file except in compliance with the License.
6 * You may obtain a copy of the License at
7
8 * http://www.apache.org/licenses/LICENSE-2.0
9
10 * Unless required by applicable law or agreed to in writing, software
11 * distributed under the License is distributed on an "AS IS" BASIS,
12 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
13 * See the License for the specific language governing permissions and
14 * limitations under the License.
15 */
16package common
17
18import (
19 "fmt"
20 "math/rand"
21 "time"
22)
23
24//GetRandomSerialNumber returns a serial number formatted as "HOST:PORT"
25func GetRandomSerialNumber() string {
26 rand.Seed(time.Now().UnixNano())
27 return fmt.Sprintf("%d.%d.%d.%d:%d",
28 rand.Intn(255),
29 rand.Intn(255),
30 rand.Intn(255),
31 rand.Intn(255),
32 rand.Intn(9000)+1000,
33 )
34}
35
36//GetRandomMacAddress returns a random mac address
37func GetRandomMacAddress() string {
38 rand.Seed(time.Now().UnixNano())
39 return fmt.Sprintf("%02x:%02x:%02x:%02x:%02x:%02x",
40 rand.Intn(128),
41 rand.Intn(128),
42 rand.Intn(128),
43 rand.Intn(128),
44 rand.Intn(128),
45 rand.Intn(128),
46 )
47}
48
49const letterBytes = "abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ"
50const (
51 letterIdxBits = 6 // 6 bits to represent a letter index
52 letterIdxMask = 1<<letterIdxBits - 1 // All 1-bits, as many as letterIdxBits
53 letterIdxMax = 63 / letterIdxBits // # of letter indices fitting in 63 bits
54)
55
56var src = rand.NewSource(time.Now().UnixNano())
57
58func GetRandomString(n int) string {
59 b := make([]byte, n)
60 // A src.Int63() generates 63 random bits, enough for letterIdxMax characters!
61 for i, cache, remain := n-1, src.Int63(), letterIdxMax; i >= 0; {
62 if remain == 0 {
63 cache, remain = src.Int63(), letterIdxMax
64 }
65 if idx := int(cache & letterIdxMask); idx < len(letterBytes) {
66 b[i] = letterBytes[idx]
67 i--
68 }
69 cache >>= letterIdxBits
70 remain--
71 }
72 return string(b)
73}