/
tunnel.go
175 lines (146 loc) · 3.46 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
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
// Copyright 2017 Marco Conti
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
// http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.
package sshkit
import (
"fmt"
"github.com/pkg/errors"
"github.com/satori/go.uuid"
"golang.org/x/crypto/ssh"
"io"
"net"
"os/exec"
)
// Endpoint defines a host and port
type Endpoint struct {
Host string
Port int
}
// String returns the preferred ssh package address format
func (endpoint *Endpoint) String() string {
return fmt.Sprintf("%s:%d", endpoint.Host, endpoint.Port)
}
// SSHTunnel is the config needed to create a tunnel
type SSHTunnel struct {
Local *Endpoint
Server *Endpoint
Remote *Endpoint
Config *ssh.ClientConfig
socket string
}
// Start initializes the tunnel and starts a forwarding (blocking)
func (tunnel *SSHTunnel) Start() error {
l, err := net.Listen("tcp", tunnel.Local.String())
if err != nil {
return err
}
defer l.Close()
for {
local, err := l.Accept()
if err != nil {
return err
}
go tunnel.forward(local)
}
}
// StartCli creates tunnel to/from remote host via shell exec using ssh commands
func (tunnel *SSHTunnel) StartCli() error {
ident, err := uuid.NewV4()
if err != nil {
panic(err.Error())
}
tunnel.socket = ident.String()
var cmd *exec.Cmd
cmd = exec.Command(
"ssh",
"-p",
string(tunnel.Server.Port),
"-M",
"-S",
tunnel.socket,
"-fnNT",
"-L",
tunnel.route(),
tunnel.userhost(),
)
err = cmd.Start()
if err != nil {
return err
}
err = cmd.Wait()
if err != nil {
return err
}
return nil
}
// StopCli closes tunnel to/from remote host via shell exec using ssh commands
func StopCli(tunnel *SSHTunnel) error {
if tunnel.socket == "" {
return errors.New("No socket identifier available")
}
var cmd *exec.Cmd
cmd = exec.Command(
"ssh",
"-p",
string(tunnel.Server.Port),
"-M",
"-S",
tunnel.socket,
"-O",
"exit",
tunnel.userhost(),
)
err := cmd.Start()
if err != nil {
return err
}
err = cmd.Wait()
if err != nil {
return err
}
return nil
}
// forward handles any incoming/outgoing reader/writer for this tunnel
func (tunnel *SSHTunnel) forward(local net.Conn) {
server, err := ssh.Dial("tcp", tunnel.Server.String(), tunnel.Config)
if err != nil {
fmt.Printf("Server dial error: %s\n", err)
return
}
remote, err := server.Dial("tcp", tunnel.Remote.String())
if err != nil {
fmt.Printf("Remote dial error: %s\n", err)
return
}
copyConn := func(writer, reader net.Conn) {
_, err := io.Copy(writer, reader)
if err != nil {
fmt.Printf("io.Copy error: %s", err)
}
}
go copyConn(local, remote)
go copyConn(remote, local)
}
// userhost returns preformated string of username and host/ip used in CLI actions
func (tunnel *SSHTunnel) userhost() string {
return tunnel.Config.User + "@" + tunnel.Server.Host
}
// route returns preformated string of local port, remote hostname and remote port used in CLI actions
func (tunnel *SSHTunnel) route() string {
return fmt.Sprintf(
"%s:%s:%s",
string(tunnel.Local.Port),
tunnel.Remote.Host,
string(tunnel.Remote.Port),
)
}