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
|
// Package stringid provides helper functions for dealing with string identifiers
package stringid
import (
cryptorand "crypto/rand"
"encoding/hex"
"fmt"
"io"
"math"
"math/big"
"math/rand"
"regexp"
"strconv"
"strings"
"time"
)
const shortLen = 12
var (
validShortID = regexp.MustCompile("^[a-f0-9]{12}$")
validHex = regexp.MustCompile(`^[a-f0-9]{64}$`)
)
// IsShortID determines if an arbitrary string *looks like* a short ID.
func IsShortID(id string) bool {
return validShortID.MatchString(id)
}
// TruncateID returns a shorthand version of a string identifier for convenience.
// A collision with other shorthands is very unlikely, but possible.
// In case of a collision a lookup with TruncIndex.Get() will fail, and the caller
// will need to use a longer prefix, or the full-length Id.
func TruncateID(id string) string {
if i := strings.IndexRune(id, ':'); i >= 0 {
id = id[i+1:]
}
if len(id) > shortLen {
id = id[:shortLen]
}
return id
}
func generateID(r io.Reader) string {
b := make([]byte, 32)
for {
if _, err := io.ReadFull(r, b); err != nil {
panic(err) // This shouldn't happen
}
id := hex.EncodeToString(b)
// if we try to parse the truncated for as an int and we don't have
// an error then the value is all numeric and causes issues when
// used as a hostname. ref #3869
if _, err := strconv.ParseInt(TruncateID(id), 10, 64); err == nil {
continue
}
return id
}
}
// GenerateRandomID returns a unique id.
func GenerateRandomID() string {
return generateID(cryptorand.Reader)
}
// GenerateNonCryptoID generates unique id without using cryptographically
// secure sources of random.
// It helps you to save entropy.
func GenerateNonCryptoID() string {
return generateID(readerFunc(rand.Read))
}
// ValidateID checks whether an ID string is a valid image ID.
func ValidateID(id string) error {
if ok := validHex.MatchString(id); !ok {
return fmt.Errorf("image ID %q is invalid", id)
}
return nil
}
func init() {
// safely set the seed globally so we generate random ids. Tries to use a
// crypto seed before falling back to time.
var seed int64
if cryptoseed, err := cryptorand.Int(cryptorand.Reader, big.NewInt(math.MaxInt64)); err != nil {
// This should not happen, but worst-case fallback to time-based seed.
seed = time.Now().UnixNano()
} else {
seed = cryptoseed.Int64()
}
rand.Seed(seed)
}
type readerFunc func(p []byte) (int, error)
func (fn readerFunc) Read(p []byte) (int, error) {
return fn(p)
}
|
