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
|
/*
* Copyright (c) 2014, Yawning Angel <yawning at torproject dot org>
* All rights reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions are met:
*
* * Redistributions of source code must retain the above copyright notice,
* this list of conditions and the following disclaimer.
*
* * Redistributions in binary form must reproduce the above copyright notice,
* this list of conditions and the following disclaimer in the documentation
* and/or other materials provided with the distribution.
*
* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
* AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
* ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE
* LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
* CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
* SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
* INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
* CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
* ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
* POSSIBILITY OF SUCH DAMAGE.
*/
package obfs4
import (
"encoding/base64"
"encoding/json"
"fmt"
"io/ioutil"
"os"
"path"
"git.torproject.org/pluggable-transports/goptlib.git"
"git.torproject.org/pluggable-transports/obfs4.git/common/csrand"
"git.torproject.org/pluggable-transports/obfs4.git/common/drbg"
"git.torproject.org/pluggable-transports/obfs4.git/common/ntor"
)
const (
stateFile = "obfs4_state.json"
)
type jsonServerState struct {
NodeID string `json:"node-id"`
PrivateKey string `json:"private-key"`
PublicKey string `json:"public-key"`
DrbgSeed string `json:"drbg-seed"`
}
type obfs4ServerState struct {
nodeID *ntor.NodeID
identityKey *ntor.Keypair
drbgSeed *drbg.Seed
}
func serverStateFromArgs(stateDir string, args *pt.Args) (*obfs4ServerState, error) {
var js jsonServerState
var nodeIDOk, privKeyOk, seedOk bool
js.NodeID, nodeIDOk = args.Get(nodeIDArg)
js.PrivateKey, privKeyOk = args.Get(privateKeyArg)
js.DrbgSeed, seedOk = args.Get(seedArg)
if !privKeyOk && !nodeIDOk && !seedOk {
if err := jsonServerStateFromFile(stateDir, &js); err != nil {
return nil, err
}
} else if !privKeyOk {
return nil, fmt.Errorf("missing argument '%s'", privateKeyArg)
} else if !nodeIDOk {
return nil, fmt.Errorf("missing argument '%s'", nodeIDArg)
} else if !seedOk {
return nil, fmt.Errorf("missing argument '%s'", seedArg)
}
return serverStateFromJSONServerState(&js)
}
func serverStateFromJSONServerState(js *jsonServerState) (*obfs4ServerState, error) {
var err error
st := new(obfs4ServerState)
if st.nodeID, err = ntor.NodeIDFromBase64(js.NodeID); err != nil {
return nil, err
}
if st.identityKey, err = ntor.KeypairFromBase64(js.PrivateKey); err != nil {
return nil, err
}
var rawSeed []byte
if rawSeed, err = base64.StdEncoding.DecodeString(js.DrbgSeed); err != nil {
return nil, err
}
if st.drbgSeed, err = drbg.SeedFromBytes(rawSeed); err != nil {
return nil, err
}
return st, nil
}
func jsonServerStateFromFile(stateDir string, js *jsonServerState) error {
f, err := ioutil.ReadFile(path.Join(stateDir, stateFile))
if err != nil {
if os.IsNotExist(err) {
if err = newJSONServerState(stateDir, js); err == nil {
return nil
}
}
return err
}
if err = json.Unmarshal(f, js); err != nil {
return err
}
return nil
}
func newJSONServerState(stateDir string, js *jsonServerState) (err error) {
// Generate everything a server needs, using the cryptographic PRNG.
var st obfs4ServerState
rawID := make([]byte, ntor.NodeIDLength)
if err = csrand.Bytes(rawID); err != nil {
return
}
if st.nodeID, err = ntor.NewNodeID(rawID); err != nil {
return
}
if st.identityKey, err = ntor.NewKeypair(false); err != nil {
return
}
if st.drbgSeed, err = drbg.NewSeed(); err != nil {
return
}
// Encode it into JSON format and write the state file.
js.NodeID = st.nodeID.Base64()
js.PrivateKey = st.identityKey.Private().Base64()
js.PublicKey = st.identityKey.Public().Base64()
js.DrbgSeed = st.drbgSeed.Base64()
var encoded []byte
if encoded, err = json.Marshal(js); err != nil {
return
}
if err = ioutil.WriteFile(path.Join(stateDir, stateFile), encoded, 0600); err != nil {
return err
}
return nil
}
|
