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
|
// Copyright 2020 Google LLC All Rights Reserved.
//
// 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
//
// http://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 verify provides a ReadCloser that verifies content matches the
// expected hash values.
package verify
import (
"bytes"
"encoding/hex"
"errors"
"fmt"
"hash"
"io"
"github.com/google/go-containerregistry/internal/and"
v1 "github.com/google/go-containerregistry/pkg/v1"
)
// SizeUnknown is a sentinel value to indicate that the expected size is not known.
const SizeUnknown = -1
type verifyReader struct {
inner io.Reader
hasher hash.Hash
expected v1.Hash
gotSize, wantSize int64
}
// Error provides information about the failed hash verification.
type Error struct {
got string
want v1.Hash
gotSize int64
}
func (v Error) Error() string {
return fmt.Sprintf("error verifying %s checksum after reading %d bytes; got %q, want %q",
v.want.Algorithm, v.gotSize, v.got, v.want)
}
// Read implements io.Reader
func (vc *verifyReader) Read(b []byte) (int, error) {
n, err := vc.inner.Read(b)
vc.gotSize += int64(n)
if err == io.EOF {
if vc.wantSize != SizeUnknown && vc.gotSize != vc.wantSize {
return n, fmt.Errorf("error verifying size; got %d, want %d", vc.gotSize, vc.wantSize)
}
got := hex.EncodeToString(vc.hasher.Sum(nil))
if want := vc.expected.Hex; got != want {
return n, Error{
got: vc.expected.Algorithm + ":" + got,
want: vc.expected,
gotSize: vc.gotSize,
}
}
}
return n, err
}
// ReadCloser wraps the given io.ReadCloser to verify that its contents match
// the provided v1.Hash before io.EOF is returned.
//
// The reader will only be read up to size bytes, to prevent resource
// exhaustion. If EOF is returned before size bytes are read, an error is
// returned.
//
// A size of SizeUnknown (-1) indicates disables size verification when the size
// is unknown ahead of time.
func ReadCloser(r io.ReadCloser, size int64, h v1.Hash) (io.ReadCloser, error) {
w, err := v1.Hasher(h.Algorithm)
if err != nil {
return nil, err
}
r2 := io.TeeReader(r, w) // pass all writes to the hasher.
if size != SizeUnknown {
r2 = io.LimitReader(r2, size) // if we know the size, limit to that size.
}
return &and.ReadCloser{
Reader: &verifyReader{
inner: r2,
hasher: w,
expected: h,
wantSize: size,
},
CloseFunc: r.Close,
}, nil
}
// Descriptor verifies that the embedded Data field matches the Size and Digest
// fields of the given v1.Descriptor, returning an error if the Data field is
// missing or if it contains incorrect data.
func Descriptor(d v1.Descriptor) error {
if d.Data == nil {
return errors.New("error verifying descriptor; Data == nil")
}
h, sz, err := v1.SHA256(bytes.NewReader(d.Data))
if err != nil {
return err
}
if h != d.Digest {
return fmt.Errorf("error verifying Digest; got %q, want %q", h, d.Digest)
}
if sz != d.Size {
return fmt.Errorf("error verifying Size; got %d, want %d", sz, d.Size)
}
return nil
}
|
