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c680a8e1 RS |
1 | // Copyright 2012 The Go Authors. All rights reserved. |
2 | // Use of this source code is governed by a BSD-style | |
3 | // license that can be found in the LICENSE file. | |
4 | ||
5 | package packet | |
6 | ||
7 | import ( | |
8 | "bytes" | |
9 | "io" | |
10 | "io/ioutil" | |
11 | ||
12 | "golang.org/x/crypto/openpgp/errors" | |
13 | ) | |
14 | ||
15 | // OpaquePacket represents an OpenPGP packet as raw, unparsed data. This is | |
16 | // useful for splitting and storing the original packet contents separately, | |
17 | // handling unsupported packet types or accessing parts of the packet not yet | |
18 | // implemented by this package. | |
19 | type OpaquePacket struct { | |
20 | // Packet type | |
21 | Tag uint8 | |
22 | // Reason why the packet was parsed opaquely | |
23 | Reason error | |
24 | // Binary contents of the packet data | |
25 | Contents []byte | |
26 | } | |
27 | ||
28 | func (op *OpaquePacket) parse(r io.Reader) (err error) { | |
29 | op.Contents, err = ioutil.ReadAll(r) | |
30 | return | |
31 | } | |
32 | ||
33 | // Serialize marshals the packet to a writer in its original form, including | |
34 | // the packet header. | |
35 | func (op *OpaquePacket) Serialize(w io.Writer) (err error) { | |
36 | err = serializeHeader(w, packetType(op.Tag), len(op.Contents)) | |
37 | if err == nil { | |
38 | _, err = w.Write(op.Contents) | |
39 | } | |
40 | return | |
41 | } | |
42 | ||
43 | // Parse attempts to parse the opaque contents into a structure supported by | |
44 | // this package. If the packet is not known then the result will be another | |
45 | // OpaquePacket. | |
46 | func (op *OpaquePacket) Parse() (p Packet, err error) { | |
47 | hdr := bytes.NewBuffer(nil) | |
48 | err = serializeHeader(hdr, packetType(op.Tag), len(op.Contents)) | |
49 | if err != nil { | |
50 | op.Reason = err | |
51 | return op, err | |
52 | } | |
53 | p, err = Read(io.MultiReader(hdr, bytes.NewBuffer(op.Contents))) | |
54 | if err != nil { | |
55 | op.Reason = err | |
56 | p = op | |
57 | } | |
58 | return | |
59 | } | |
60 | ||
61 | // OpaqueReader reads OpaquePackets from an io.Reader. | |
62 | type OpaqueReader struct { | |
63 | r io.Reader | |
64 | } | |
65 | ||
66 | func NewOpaqueReader(r io.Reader) *OpaqueReader { | |
67 | return &OpaqueReader{r: r} | |
68 | } | |
69 | ||
70 | // Read the next OpaquePacket. | |
71 | func (or *OpaqueReader) Next() (op *OpaquePacket, err error) { | |
72 | tag, _, contents, err := readHeader(or.r) | |
73 | if err != nil { | |
74 | return | |
75 | } | |
76 | op = &OpaquePacket{Tag: uint8(tag), Reason: err} | |
77 | err = op.parse(contents) | |
78 | if err != nil { | |
79 | consumeAll(contents) | |
80 | } | |
81 | return | |
82 | } | |
83 | ||
84 | // OpaqueSubpacket represents an unparsed OpenPGP subpacket, | |
85 | // as found in signature and user attribute packets. | |
86 | type OpaqueSubpacket struct { | |
87 | SubType uint8 | |
88 | Contents []byte | |
89 | } | |
90 | ||
91 | // OpaqueSubpackets extracts opaque, unparsed OpenPGP subpackets from | |
92 | // their byte representation. | |
93 | func OpaqueSubpackets(contents []byte) (result []*OpaqueSubpacket, err error) { | |
94 | var ( | |
95 | subHeaderLen int | |
96 | subPacket *OpaqueSubpacket | |
97 | ) | |
98 | for len(contents) > 0 { | |
99 | subHeaderLen, subPacket, err = nextSubpacket(contents) | |
100 | if err != nil { | |
101 | break | |
102 | } | |
103 | result = append(result, subPacket) | |
104 | contents = contents[subHeaderLen+len(subPacket.Contents):] | |
105 | } | |
106 | return | |
107 | } | |
108 | ||
109 | func nextSubpacket(contents []byte) (subHeaderLen int, subPacket *OpaqueSubpacket, err error) { | |
110 | // RFC 4880, section 5.2.3.1 | |
111 | var subLen uint32 | |
112 | if len(contents) < 1 { | |
113 | goto Truncated | |
114 | } | |
115 | subPacket = &OpaqueSubpacket{} | |
116 | switch { | |
117 | case contents[0] < 192: | |
118 | subHeaderLen = 2 // 1 length byte, 1 subtype byte | |
119 | if len(contents) < subHeaderLen { | |
120 | goto Truncated | |
121 | } | |
122 | subLen = uint32(contents[0]) | |
123 | contents = contents[1:] | |
124 | case contents[0] < 255: | |
125 | subHeaderLen = 3 // 2 length bytes, 1 subtype | |
126 | if len(contents) < subHeaderLen { | |
127 | goto Truncated | |
128 | } | |
129 | subLen = uint32(contents[0]-192)<<8 + uint32(contents[1]) + 192 | |
130 | contents = contents[2:] | |
131 | default: | |
132 | subHeaderLen = 6 // 5 length bytes, 1 subtype | |
133 | if len(contents) < subHeaderLen { | |
134 | goto Truncated | |
135 | } | |
136 | subLen = uint32(contents[1])<<24 | | |
137 | uint32(contents[2])<<16 | | |
138 | uint32(contents[3])<<8 | | |
139 | uint32(contents[4]) | |
140 | contents = contents[5:] | |
141 | } | |
142 | if subLen > uint32(len(contents)) || subLen == 0 { | |
143 | goto Truncated | |
144 | } | |
145 | subPacket.SubType = contents[0] | |
146 | subPacket.Contents = contents[1:subLen] | |
147 | return | |
148 | Truncated: | |
149 | err = errors.StructuralError("subpacket truncated") | |
150 | return | |
151 | } | |
152 | ||
153 | func (osp *OpaqueSubpacket) Serialize(w io.Writer) (err error) { | |
154 | buf := make([]byte, 6) | |
155 | n := serializeSubpacketLength(buf, len(osp.Contents)+1) | |
156 | buf[n] = osp.SubType | |
157 | if _, err = w.Write(buf[:n+1]); err != nil { | |
158 | return | |
159 | } | |
160 | _, err = w.Write(osp.Contents) | |
161 | return | |
162 | } |