-
Notifications
You must be signed in to change notification settings - Fork 0
/
tunnel.go
159 lines (140 loc) · 3.02 KB
/
tunnel.go
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
package main
import (
"fmt"
"log"
"net"
"strings"
"sync"
"github.com/pkg/errors"
"golang.org/x/crypto/ssh"
)
// Endpoint is wrapping
// the host and port of SSHtunnel endpoint
type Endpoint struct {
Host string
Port string
}
func (endpoint *Endpoint) String() string {
return fmt.Sprintf("%s:%s", endpoint.Host, endpoint.Port)
}
// EndpointFromHostPort is helper function
// for creating endpoint from string in format "<host>:<port>"
func EndpointFromHostPort(hostPort string) (*Endpoint, error) {
remote := strings.Split(hostPort, ":")
if len(remote) < 2 {
return nil, fmt.Errorf("Tunnel does not contain a port")
}
return &Endpoint{
remote[0],
remote[1],
}, nil
}
// SSHtunnel represents the
// tunneled connection via ssh
type SSHtunnel struct {
Local *Endpoint
Remote *Endpoint
Active *AtomicBool
stopChan chan bool
listener net.Listener
}
// Start opens(activates) the
// SSHtunnel tunnel
func (t *SSHtunnel) Start(client *ssh.Client, wait *sync.WaitGroup) error {
if client == nil {
return errors.New("metro: ssh client cannot be nil")
}
listener, err := net.Listen("tcp", t.Local.String())
if err != nil {
return err
}
wait.Add(1)
defer wait.Done()
t.listener = listener
for {
conn, err := listener.Accept()
if err != nil {
return err
}
t.Active.Set(true)
go t.forward(conn, client)
}
}
// Stop closes the SSH tunnel
func (t *SSHtunnel) Stop() {
t.listener.Close()
if t.Active.Get() {
// closing stopChan causes
// nil value while channel is
// readed
close(t.stopChan)
}
}
func (t *SSHtunnel) forward(local net.Conn, client *ssh.Client) {
remote, err := client.Dial("tcp", t.Remote.String())
if err != nil {
log.Printf("Remote dial error: %s\n", err)
return
}
copyConnection(local, remote, t.stopChan)
closeConnections(local, remote)
}
func copyConnection(local net.Conn, remote net.Conn, stopChan chan bool) {
localChan := chanFromConn(local)
remoteChan := chanFromConn(remote)
for {
select {
case <-stopChan:
return
case b1 := <-localChan:
if b1 == nil {
return
}
remote.Write(b1.Data)
case b2 := <-remoteChan:
if b2 == nil {
return
}
local.Write(b2.Data)
}
}
}
// Data wraps the content
// and amount of data read from
// connection
type Data struct {
Size int
Data []byte
}
// chanFromConn creates a channel from a Conn object, and sends everything it
// Read()s from the socket to the channel.
func chanFromConn(conn net.Conn) chan *Data {
c := make(chan *Data)
go func() {
// If connection closed,
// EOR err is returned and channel closed
// Reading from closed channel returns nil
defer close(c)
buf1 := make([]byte, 32*1024)
buf2 := make([]byte, 32*1024)
for {
n, err := conn.Read(buf1)
if n > 0 {
copy(buf2, buf1[:n])
c <- &Data{n, buf2[:n]}
}
if err != nil {
c <- nil
break
}
}
}()
return c
}
func closeConnections(connections ...net.Conn) {
for _, conn := range connections {
if err := conn.Close(); err != nil {
log.Println("Cannot close connection: %v\n", err)
}
}
}