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
|
// Copyright 2017 Docker, Inc.
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
// https://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.
package digest
import (
"fmt"
"hash"
"io"
"regexp"
"strings"
)
// Digest allows simple protection of hex formatted digest strings, prefixed
// by their algorithm. Strings of type Digest have some guarantee of being in
// the correct format and it provides quick access to the components of a
// digest string.
//
// The following is an example of the contents of Digest types:
//
// sha256:7173b809ca12ec5dee4506cd86be934c4596dd234ee82c0662eac04a8c2c71dc
//
// This allows to abstract the digest behind this type and work only in those
// terms.
type Digest string
// NewDigest returns a Digest from alg and a hash.Hash object.
func NewDigest(alg Algorithm, h hash.Hash) Digest {
return NewDigestFromBytes(alg, h.Sum(nil))
}
// NewDigestFromBytes returns a new digest from the byte contents of p.
// Typically, this can come from hash.Hash.Sum(...) or xxx.SumXXX(...)
// functions. This is also useful for rebuilding digests from binary
// serializations.
func NewDigestFromBytes(alg Algorithm, p []byte) Digest {
return Digest(fmt.Sprintf("%s:%x", alg, p))
}
// NewDigestFromHex returns a Digest from alg and a the hex encoded digest.
func NewDigestFromHex(alg, hex string) Digest {
return Digest(fmt.Sprintf("%s:%s", alg, hex))
}
// DigestRegexp matches valid digest types.
var DigestRegexp = regexp.MustCompile(`[a-zA-Z0-9-_+.]+:[a-fA-F0-9]+`)
// DigestRegexpAnchored matches valid digest types, anchored to the start and end of the match.
var DigestRegexpAnchored = regexp.MustCompile(`^` + DigestRegexp.String() + `$`)
var (
// ErrDigestInvalidFormat returned when digest format invalid.
ErrDigestInvalidFormat = fmt.Errorf("invalid checksum digest format")
// ErrDigestInvalidLength returned when digest has invalid length.
ErrDigestInvalidLength = fmt.Errorf("invalid checksum digest length")
// ErrDigestUnsupported returned when the digest algorithm is unsupported.
ErrDigestUnsupported = fmt.Errorf("unsupported digest algorithm")
)
// Parse parses s and returns the validated digest object. An error will
// be returned if the format is invalid.
func Parse(s string) (Digest, error) {
d := Digest(s)
return d, d.Validate()
}
// FromReader consumes the content of rd until io.EOF, returning canonical digest.
func FromReader(rd io.Reader) (Digest, error) {
return Canonical.FromReader(rd)
}
// FromBytes digests the input and returns a Digest.
func FromBytes(p []byte) Digest {
return Canonical.FromBytes(p)
}
// FromString digests the input and returns a Digest.
func FromString(s string) Digest {
return Canonical.FromString(s)
}
// Validate checks that the contents of d is a valid digest, returning an
// error if not.
func (d Digest) Validate() error {
s := string(d)
i := strings.Index(s, ":")
// validate i then run through regexp
if i < 0 || i+1 == len(s) || !DigestRegexpAnchored.MatchString(s) {
return ErrDigestInvalidFormat
}
algorithm := Algorithm(s[:i])
if !algorithm.Available() {
return ErrDigestUnsupported
}
// Digests much always be hex-encoded, ensuring that their hex portion will
// always be size*2
if algorithm.Size()*2 != len(s[i+1:]) {
return ErrDigestInvalidLength
}
return nil
}
// Algorithm returns the algorithm portion of the digest. This will panic if
// the underlying digest is not in a valid format.
func (d Digest) Algorithm() Algorithm {
return Algorithm(d[:d.sepIndex()])
}
// Verifier returns a writer object that can be used to verify a stream of
// content against the digest. If the digest is invalid, the method will panic.
func (d Digest) Verifier() Verifier {
return hashVerifier{
hash: d.Algorithm().Hash(),
digest: d,
}
}
// Hex returns the hex digest portion of the digest. This will panic if the
// underlying digest is not in a valid format.
func (d Digest) Hex() string {
return string(d[d.sepIndex()+1:])
}
func (d Digest) String() string {
return string(d)
}
func (d Digest) sepIndex() int {
i := strings.Index(string(d), ":")
if i < 0 {
panic(fmt.Sprintf("no ':' separator in digest %q", d))
}
return i
}
|
