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
|
package shapeshifter
import (
"fmt"
"io"
"log"
"net"
"sync"
"github.com/OperatorFoundation/shapeshifter-transports/transports/obfs4"
)
type ShapeShifter struct {
Cert string
IatMode int
Target string // remote ip:port obfs4 server
SocksAddr string // -proxylistenaddr in shapeshifter-dispatcher
ln net.Listener
errChan chan error
}
func (ss *ShapeShifter) Open() error {
err := ss.checkOptions()
if err != nil {
return err
}
ss.ln, err = net.Listen("tcp", ss.SocksAddr)
if err != nil {
return fmt.Errorf("failed to listen: %s", err.Error())
}
go ss.clientAcceptLoop()
return nil
}
func (ss *ShapeShifter) Close() error {
if ss.ln != nil {
return ss.ln.Close()
}
return nil
}
func (ss *ShapeShifter) GetErrorChannel() chan error {
if ss.errChan == nil {
ss.errChan = make(chan error, 2)
}
return ss.errChan
}
func (ss *ShapeShifter) GetLastError() error {
if ss.errChan == nil {
ss.errChan = make(chan error, 2)
}
return <-ss.errChan
}
func (ss ShapeShifter) clientAcceptLoop() error {
for {
conn, err := ss.ln.Accept()
if err != nil {
if e, ok := err.(net.Error); ok && !e.Temporary() {
return err
}
ss.sendError("Error accepting connection: %v", err)
continue
}
go ss.clientHandler(conn)
}
}
func (ss ShapeShifter) clientHandler(conn net.Conn) {
defer conn.Close()
transport := obfs4.NewObfs4Client(ss.Cert, ss.IatMode)
remote, err := transport.Dial(ss.Target)
if err != nil {
ss.sendError("outgoing connection failed %s: %v", ss.Target, err)
return
}
if remote == nil {
ss.sendError("outgoing connection failed %s", ss.Target)
return
}
defer remote.Close()
err = copyLoop(conn, remote)
if err != nil {
ss.sendError("%s - closed connection: %v", ss.Target, err)
} else {
log.Printf("%s - closed connection", ss.Target)
}
return
}
func copyLoop(a net.Conn, b net.Conn) error {
// Note: b is always the pt connection. a is the SOCKS/ORPort connection.
errChan := make(chan error, 2)
var wg sync.WaitGroup
wg.Add(2)
go func() {
defer wg.Done()
defer b.Close()
defer a.Close()
_, err := io.Copy(b, a)
errChan <- err
}()
go func() {
defer wg.Done()
defer a.Close()
defer b.Close()
_, err := io.Copy(a, b)
errChan <- err
}()
// Wait for both upstream and downstream to close. Since one side
// terminating closes the other, the second error in the channel will be
// something like EINVAL (though io.Copy() will swallow EOF), so only the
// first error is returned.
wg.Wait()
if len(errChan) > 0 {
return <-errChan
}
return nil
}
func (ss *ShapeShifter) checkOptions() error {
if ss.SocksAddr == "" {
ss.SocksAddr = "127.0.0.1:0"
}
if ss.Cert == "" {
return fmt.Errorf("obfs4 transport missing cert argument")
}
return nil
}
func (ss *ShapeShifter) sendError(format string, a ...interface{}) {
if ss.errChan == nil {
ss.errChan = make(chan error, 2)
}
select {
case ss.errChan <- fmt.Errorf(format, a...):
default:
log.Printf(format, a...)
}
}
|
