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ssh2tcp.go
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ssh2tcp.go
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package main
import (
"errors"
"flag"
"io"
"io/ioutil"
"net/url"
"os"
"os/signal"
"sync"
"syscall"
"go.uber.org/zap"
"golang.org/x/crypto/ssh"
)
var lg *zap.Logger
type DataChannel interface {
Read(data []byte) (int, error)
Write(data []byte) (int, error)
Close() error
CloseWrite() error
}
type Server interface {
Listen() error
Accept(dcs chan<- interface{}) error
Close() error
}
type Client interface {
Connect() (DataChannel, error)
Close() error
}
func init() {
var err error
lg, err = zap.NewProduction()
if err != nil {
panic(err)
}
}
func doServer(s Server, dcs chan<- interface{}, wg *sync.WaitGroup, done <-chan struct{}) {
defer wg.Done()
err := s.Listen()
if err != nil {
lg.Debug("Listen() failed")
return
}
for {
err := s.Accept(dcs)
if err != nil {
lg.Debug("Accept() failed")
return
}
select {
case <-done:
lg.Debug("server done")
return
default:
}
}
return
}
func newServerChannel(c Client, dcs <-chan interface{}, wg *sync.WaitGroup, done <-chan struct{}) {
defer wg.Done()
for {
select {
case dc := <-dcs:
lg.Debug("New datachannel received")
sdc, ok := dc.(DataChannel)
if ok {
wg.Add(1)
go setupRelay(c, sdc, wg, done)
}
case <-done:
lg.Debug("Done")
return
}
}
}
func setupRelay(c Client, sdc DataChannel, wg *sync.WaitGroup, done <-chan struct{}) {
defer wg.Done()
cdc, err := c.Connect()
if err != nil {
sdc.Close()
return
}
wg.Add(2)
var once sync.Once
closer := func() {
cdc.Close()
sdc.Close()
}
go func() {
defer wg.Done()
io.Copy(cdc, sdc)
lg.Debug("s2c done")
once.Do(closer)
}()
go func() {
defer wg.Done()
io.Copy(sdc, cdc)
lg.Debug("c2s done")
once.Do(closer)
}()
for {
select {
case <-done:
lg.Debug("done")
once.Do(closer)
return
}
}
}
func initClient(u *url.URL, ca string) (Client, error) {
switch u.Scheme {
case "tcp":
tc := TcpClient{}
tc.addr = u.Host
return &tc, nil
case "ssh":
sc := SshClient{}
var sshUser string
var sshPass string
var ok bool
if ca != "" {
sc.addr = ca + ":22"
sshUser = u.User.Username() + "@" + u.Host
} else {
sc.addr = u.Host
sshUser = u.User.Username()
}
sshPass, ok = u.User.Password()
if !ok {
sshPass = "12345678"
}
sc.cfg = ssh.ClientConfig{
User: sshUser,
Auth: []ssh.AuthMethod{
ssh.Password(sshPass),
},
HostKeyCallback: ssh.InsecureIgnoreHostKey(),
}
return &sc, nil
default:
return nil, errors.New("Invalid scheme")
}
return nil, errors.New("Invalid scheme")
}
func initServer(u *url.URL, hostkey string) (Server, error) {
switch u.Scheme {
case "tcp":
ts := TcpServer{}
ts.addr = u.Host
return &ts, nil
case "ssh":
ss := SshServer{}
ss.addr = u.Host
ss.cfg = ssh.ServerConfig{
PasswordCallback: func(c ssh.ConnMetadata, pass []byte) (*ssh.Permissions, error) {
return nil, nil
},
}
privKey, err := ioutil.ReadFile(hostkey)
if err == nil {
priv, err := ssh.ParsePrivateKey(privKey)
if err != nil {
lg.Warn("Unable to parse private key")
return nil, err
}
ss.cfg.AddHostKey(priv)
} else {
lg.Warn("Unable to read hostkey")
return nil, err
}
return &ss, nil
default:
return nil, errors.New("Invalid scheme")
}
return nil, errors.New("Invalid scheme")
}
func main() {
listenURL := flag.String("listen", "", "Listen address, eg. ssh://127.0.0.1:1234")
connectURL := flag.String("connect", "", "Connect address, eg. tcp://127.0.0.1:4321")
caURL := flag.String("ca", "", "CA address")
hostKey := flag.String("hostkey", "", "Host private key for SSH listener")
debug := flag.Bool("debug", false, "true to enable debug logging")
flag.Parse()
if *debug {
lg = zap.NewExample()
}
if *listenURL == "" || *connectURL == "" {
panic("'listen' or 'connect' has to be specified")
}
var listen *url.URL
var connect *url.URL
var err error
var client Client
var server Server
listen, err = url.Parse(*listenURL)
if err != nil {
panic("Unable to parse listen URL")
}
connect, err = url.Parse(*connectURL)
if err != nil {
panic("Unable to parse connect URL")
}
var wg sync.WaitGroup
done := make(chan struct{})
sdcs := make(chan interface{})
client, err = initClient(connect, *caURL)
if err != nil {
panic("Unable to create client")
}
server, err = initServer(listen, *hostKey)
if err != nil {
panic("Unable to create server")
}
wg.Add(1)
go doServer(server, sdcs, &wg, done)
wg.Add(1)
go newServerChannel(client, sdcs, &wg, done)
signal_chan := make(chan os.Signal, 1)
signal.Notify(signal_chan,
syscall.SIGHUP,
syscall.SIGINT,
syscall.SIGTERM,
syscall.SIGQUIT)
quit := false
for !quit {
select {
case <-signal_chan:
lg.Debug("Signal received")
quit = true
}
}
close(done)
client.Close()
server.Close()
lg.Debug("Waiting for all done")
wg.Wait()
lg.Debug("All done")
}