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
155
156
157
158
159
160
161
162
163
164
165
|
// reader.go largerly mimics github.com/emersion/go-gpgmail, with changes made
// to interface with the gpg package in aerc
package gpg
import (
"bufio"
"bytes"
"fmt"
"io"
"mime"
"strings"
"git.sr.ht/~rjarry/aerc/lib/crypto/gpg/gpgbin"
"git.sr.ht/~rjarry/aerc/models"
"github.com/emersion/go-message/textproto"
)
type Reader struct {
Header textproto.Header
MessageDetails *models.MessageDetails
}
func NewReader(h textproto.Header, body io.Reader) (*Reader, error) {
t, params, err := mime.ParseMediaType(h.Get("Content-Type"))
if err != nil {
return nil, err
}
if strings.EqualFold(t, "multipart/encrypted") && strings.EqualFold(params["protocol"], "application/pgp-encrypted") {
mr := textproto.NewMultipartReader(body, params["boundary"])
return newEncryptedReader(h, mr)
}
if strings.EqualFold(t, "multipart/signed") && strings.EqualFold(params["protocol"], "application/pgp-signature") {
micalg := params["micalg"]
mr := textproto.NewMultipartReader(body, params["boundary"])
return newSignedReader(h, mr, micalg)
}
var headerBuf bytes.Buffer
textproto.WriteHeader(&headerBuf, h)
return &Reader{
Header: h,
MessageDetails: &models.MessageDetails{
Body: io.MultiReader(&headerBuf, body),
},
}, nil
}
func Read(r io.Reader) (*Reader, error) {
br := bufio.NewReader(r)
h, err := textproto.ReadHeader(br)
if err != nil {
return nil, err
}
return NewReader(h, br)
}
func newEncryptedReader(h textproto.Header, mr *textproto.MultipartReader) (*Reader, error) {
p, err := mr.NextPart()
if err != nil {
return nil, fmt.Errorf("gpgmail: failed to read first part in multipart/encrypted message: %v", err)
}
t, _, err := mime.ParseMediaType(p.Header.Get("Content-Type"))
if err != nil {
return nil, fmt.Errorf("gpgmail: failed to parse Content-Type of first part in multipart/encrypted message: %v", err)
}
if !strings.EqualFold(t, "application/pgp-encrypted") {
return nil, fmt.Errorf("gpgmail: first part in multipart/encrypted message has type %q, not application/pgp-encrypted", t)
}
metadata, err := textproto.ReadHeader(bufio.NewReader(p))
if err != nil {
return nil, fmt.Errorf("gpgmail: failed to parse application/pgp-encrypted part: %v", err)
}
if s := metadata.Get("Version"); s != "1" {
return nil, fmt.Errorf("gpgmail: unsupported PGP/MIME version: %q", s)
}
p, err = mr.NextPart()
if err != nil {
return nil, fmt.Errorf("gpgmail: failed to read second part in multipart/encrypted message: %v", err)
}
t, _, err = mime.ParseMediaType(p.Header.Get("Content-Type"))
if err != nil {
return nil, fmt.Errorf("gpgmail: failed to parse Content-Type of second part in multipart/encrypted message: %v", err)
}
if !strings.EqualFold(t, "application/octet-stream") {
return nil, fmt.Errorf("gpgmail: second part in multipart/encrypted message has type %q, not application/octet-stream", t)
}
md, err := gpgbin.Decrypt(p)
if err != nil {
return nil, fmt.Errorf("gpgmail: failed to read PGP message: %v", err)
}
cleartext := bufio.NewReader(md.Body)
cleartextHeader, err := textproto.ReadHeader(cleartext)
if err != nil {
return nil, fmt.Errorf("gpgmail: failed to read encrypted header: %v", err)
}
t, params, err := mime.ParseMediaType(cleartextHeader.Get("Content-Type"))
if err != nil {
return nil, err
}
if md.IsEncrypted && !md.IsSigned && strings.EqualFold(t, "multipart/signed") && strings.EqualFold(params["protocol"], "application/pgp-signature") {
// RFC 1847 encapsulation, see RFC 3156 section 6.1
micalg := params["micalg"]
mr := textproto.NewMultipartReader(cleartext, params["boundary"])
mds, err := newSignedReader(cleartextHeader, mr, micalg)
if err != nil {
return nil, fmt.Errorf("gpgmail: failed to read encapsulated multipart/signed message: %v", err)
}
mds.MessageDetails.IsEncrypted = md.IsEncrypted
mds.MessageDetails.DecryptedWith = md.DecryptedWith
mds.MessageDetails.DecryptedWithKeyId = md.DecryptedWithKeyId
return mds, nil
}
var headerBuf bytes.Buffer
textproto.WriteHeader(&headerBuf, cleartextHeader)
md.Body = io.MultiReader(&headerBuf, cleartext)
return &Reader{
Header: h,
MessageDetails: md,
}, nil
}
func newSignedReader(h textproto.Header, mr *textproto.MultipartReader, micalg string) (*Reader, error) {
micalg = strings.ToLower(micalg)
p, err := mr.NextPart()
if err != nil {
return nil, fmt.Errorf("gpgmail: failed to read signed part in multipart/signed message: %v", err)
}
var headerBuf bytes.Buffer
textproto.WriteHeader(&headerBuf, p.Header)
var msg bytes.Buffer
headerRdr := bytes.NewReader(headerBuf.Bytes())
fullMsg := io.MultiReader(headerRdr, p)
io.Copy(&msg, fullMsg)
sig, err := mr.NextPart()
if err != nil {
return nil, fmt.Errorf("gpgmail: failed to read pgp part in multipart/signed message: %v", err)
}
md, err := gpgbin.Verify(&msg, sig)
if err != nil {
return nil, fmt.Errorf("gpgmail: failed to read PGP message: %v", err)
}
if md.Micalg != micalg && md.SignatureError == "" {
md.SignatureError = "gpg: header hash does not match actual sig hash"
}
return &Reader{
Header: h,
MessageDetails: md,
}, nil
}
|
