This repository has been archived by the owner on Sep 14, 2022. It is now read-only.
-
Notifications
You must be signed in to change notification settings - Fork 4
/
terminal.go
193 lines (172 loc) · 4.17 KB
/
terminal.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
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
package ssh
import (
"context"
"encoding/base64"
"errors"
"fmt"
"net"
"os"
"path/filepath"
"time"
"github.com/sirupsen/logrus"
"golang.org/x/crypto/ssh"
"golang.org/x/crypto/ssh/knownhosts"
"golang.org/x/term"
)
type ConnectConfig struct {
PrivateKey []byte
User string
Addr string
}
type Terminal interface {
Connect(ctx context.Context, cfg ConnectConfig) error
}
func NewTerminal(log logrus.FieldLogger) Terminal {
return &terminal{log: log}
}
type terminal struct {
log logrus.FieldLogger
}
func (t *terminal) Connect(ctx context.Context, cfg ConnectConfig) error {
// Create SSH connection.
conn, err := t.dial(ctx, cfg)
if err != nil {
return err
}
defer conn.Close()
// Create SSH session.
sess, err := conn.NewSession()
if err != nil {
return err
}
defer sess.Close()
// Exit on context cancel.
go func() {
<-ctx.Done()
conn.Close()
}()
// Create interactive terminal.
fd := int(os.Stdin.Fd())
state, err := term.MakeRaw(fd)
if err != nil {
return fmt.Errorf("terminal make raw: %w", err)
}
defer term.Restore(fd, state)
w, h, err := term.GetSize(fd)
if err != nil {
return fmt.Errorf("terminal get size: %w", err)
}
// Setup session shell.
modes := ssh.TerminalModes{
ssh.ECHO: 1,
ssh.TTY_OP_ISPEED: 14400,
ssh.TTY_OP_OSPEED: 14400,
}
termType := os.Getenv("TERM")
if termType == "" {
termType = "xterm-256color"
}
if err := sess.RequestPty(termType, h, w, modes); err != nil {
return fmt.Errorf("session xterm: %w", err)
}
sess.Stdout = os.Stdout
sess.Stderr = os.Stderr
sess.Stdin = os.Stdin
if err := sess.Shell(); err != nil {
return fmt.Errorf("session shell: %w", err)
}
if err := sess.Wait(); err != nil {
if e, ok := err.(*ssh.ExitError); ok {
switch e.ExitStatus() {
case 130:
return nil
}
}
return fmt.Errorf("ssh: %w", err)
}
return nil
}
func (t *terminal) dial(ctx context.Context, cfg ConnectConfig) (*ssh.Client, error) {
signer, err := ssh.ParsePrivateKey(cfg.PrivateKey)
if err != nil {
return nil, fmt.Errorf("parsing private key: %w", err)
}
home, err := os.UserHomeDir()
if err != nil {
return nil, err
}
knownhostsFilePath := filepath.Join(home, ".ssh", "known_hosts")
if err := ensureKnownHostsFile(knownhostsFilePath); err != nil {
return nil, err
}
var conn *ssh.Client
connTimeout := time.After(2 * time.Minute)
for {
var connerr error
conn, connerr = ssh.Dial("tcp", cfg.Addr, &ssh.ClientConfig{
User: cfg.User,
Auth: []ssh.AuthMethod{
ssh.PublicKeys(signer),
},
HostKeyCallback: t.validateHostKey(knownhostsFilePath),
Timeout: 15 * time.Second,
})
if connerr == nil {
return conn, nil
}
select {
case <-time.After(2 * time.Second):
t.log.Debugf("ssh connection failed, reconnecting: %v", connerr)
case <-connTimeout:
return nil, fmt.Errorf("connection timeout: %w", connerr)
case <-ctx.Done():
return nil, ctx.Err()
}
}
}
// validateHostKey tries to validate known hosts file and adds new entry if host is unknown.
func (t *terminal) validateHostKey(knownhostsFilePath string) ssh.HostKeyCallback {
return func(addr string, remote net.Addr, key ssh.PublicKey) error {
validate, err := knownhosts.New(knownhostsFilePath)
if err != nil {
return err
}
err = validate(addr, remote, key)
var keyErr *knownhosts.KeyError
// Add host key to know hosts only if key is unknown.
if errors.As(err, &keyErr) && len(keyErr.Want) == 0 {
f, err := os.OpenFile(knownhostsFilePath, os.O_APPEND|os.O_WRONLY, 0644)
if err != nil {
return err
}
defer f.Close()
hostname, _, err := net.SplitHostPort(addr)
if err != nil {
return err
}
key := fmt.Sprintf("%s %s %s\n", hostname, key.Type(), base64.StdEncoding.EncodeToString(key.Marshal()))
_, err = f.WriteString(key)
if err != nil {
return err
}
t.log.Warnf("added %s to known hosts in %s", hostname, knownhostsFilePath)
return nil
}
return err
}
}
func ensureKnownHostsFile(path string) error {
_, err := os.Stat(path)
if os.IsNotExist(err) {
f, err := os.Create(path)
if err != nil {
return err
}
if err := f.Chmod(0644); err != nil {
return err
}
defer f.Close()
return nil
}
return err
}