func (s *sshTunnel) Start(readyErrCh chan<- error, errCh chan<- error) {
authMethods := []ssh.AuthMethod{}
if s.options.PrivateKey != "" {
s.logger.Debug(s.logTag, "Reading private key file '%s'", s.options.PrivateKey)
keyContents, err := ioutil.ReadFile(s.options.PrivateKey)
if err != nil {
readyErrCh <- bosherr.WrapErrorf(err, "Reading private key file '%s'", s.options.PrivateKey)
return
}
s.logger.Debug(s.logTag, "Parsing private key file '%s'", s.options.PrivateKey)
signer, err := ssh.ParsePrivateKey(keyContents)
if err != nil {
readyErrCh <- bosherr.WrapErrorf(err, "Parsing private key file '%s'", s.options.PrivateKey)
return
}
authMethods = append(authMethods, ssh.PublicKeys(signer))
}
if s.options.Password != "" {
s.logger.Debug(s.logTag, "Adding password auth method to ssh tunnel config")
keyboardInteractiveChallenge := func(
user,
instruction string,
questions []string,
echos []bool,
) (answers []string, err error) {
if len(questions) == 0 {
return []string{}, nil
}
return []string{s.options.Password}, nil
}
authMethods = append(authMethods, ssh.KeyboardInteractive(keyboardInteractiveChallenge))
authMethods = append(authMethods, ssh.Password(s.options.Password))
}
sshConfig := &ssh.ClientConfig{
User: s.options.User,
Auth: authMethods,
}
s.logger.Debug(s.logTag, "Dialing remote server at %s:%d", s.options.Host, s.options.Port)
remoteAddr := fmt.Sprintf("%s:%d", s.options.Host, s.options.Port)
retryStrategy := &SSHRetryStrategy{
TimeService: s.timeService,
ConnectionRefusedTimeout: s.connectionRefusedTimeout,
AuthFailureTimeout: s.authFailureTimeout,
}
var conn *ssh.Client
var err error
for i := 0; ; i++ {
s.logger.Debug(s.logTag, "Making attempt #%d", i)
conn, err = ssh.Dial("tcp", remoteAddr, sshConfig)
if err == nil {
break
}
if !retryStrategy.IsRetryable(err) {
readyErrCh <- bosherr.WrapError(err, "Failed to connect to remote server")
return
}
s.logger.Debug(s.logTag, "Attempt failed #%d: Dialing remote server: %s", i, err.Error())
time.Sleep(s.startDialDelay)
}
remoteListenAddr := fmt.Sprintf("127.0.0.1:%d", s.options.RemoteForwardPort)
s.logger.Debug(s.logTag, "Listening on remote server %s", remoteListenAddr)
s.remoteListener, err = conn.Listen("tcp", remoteListenAddr)
if err != nil {
readyErrCh <- bosherr.WrapError(err, "Listening on remote server")
return
}
readyErrCh <- nil
for {
remoteConn, err := s.remoteListener.Accept()
s.logger.Debug(s.logTag, "Received connection")
if err != nil {
errCh <- bosherr.WrapError(err, "Accepting connection on remote server")
}
defer func() {
if err = remoteConn.Close(); err != nil {
s.logger.Warn(s.logTag, "Failed to close remote listener connection: %s", err.Error())
}
}()
s.logger.Debug(s.logTag, "Dialing local server")
localDialAddr := fmt.Sprintf("127.0.0.1:%d", s.options.LocalForwardPort)
localConn, err := net.Dial("tcp", localDialAddr)
if err != nil {
errCh <- bosherr.WrapError(err, "Dialing local server")
return
}
go func() {
bytesNum, err := io.Copy(remoteConn, localConn)
defer func() {
if err = localConn.Close(); err != nil {
s.logger.Warn(s.logTag, "Failed to close local dial connection: %s", err.Error())
}
}()
s.logger.Debug(s.logTag, "Copying bytes from local to remote %d", bytesNum)
if err != nil {
errCh <- bosherr.WrapError(err, "Copying bytes from local to remote")
}
}()
go func() {
bytesNum, err := io.Copy(localConn, remoteConn)
defer func() {
if err = localConn.Close(); err != nil {
s.logger.Warn(s.logTag, "Failed to close local dial connection: %s", err.Error())
}
}()
s.logger.Debug(s.logTag, "Copying bytes from remote to local %d", bytesNum)
if err != nil {
errCh <- bosherr.WrapError(err, "Copying bytes from remote to local")
}
}()
}
}
func ExampleNewServerConn() {
// An SSH server is represented by a ServerConfig, which holds
// certificate details and handles authentication of ServerConns.
config := &ssh.ServerConfig{
PasswordCallback: func(c ssh.ConnMetadata, pass []byte) (*ssh.Permissions, error) {
// Should use constant-time compare (or better, salt+hash) in
// a production setting.
if c.User() == "testuser" && string(pass) == "tiger" {
return nil, nil
}
return nil, fmt.Errorf("password rejected for %q", c.User())
},
}
privateBytes, err := ioutil.ReadFile("id_rsa")
if err != nil {
panic("Failed to load private key")
}
private, err := ssh.ParsePrivateKey(privateBytes)
if err != nil {
panic("Failed to parse private key")
}
config.AddHostKey(private)
// Once a ServerConfig has been configured, connections can be
// accepted.
listener, err := net.Listen("tcp", "0.0.0.0:2022")
if err != nil {
panic("failed to listen for connection")
}
nConn, err := listener.Accept()
if err != nil {
panic("failed to accept incoming connection")
}
// Before use, a handshake must be performed on the incoming
// net.Conn.
_, chans, reqs, err := ssh.NewServerConn(nConn, config)
if err != nil {
panic("failed to handshake")
}
// The incoming Request channel must be serviced.
go ssh.DiscardRequests(reqs)
// Service the incoming Channel channel.
for newChannel := range chans {
// Channels have a type, depending on the application level
// protocol intended. In the case of a shell, the type is
// "session" and ServerShell may be used to present a simple
// terminal interface.
if newChannel.ChannelType() != "session" {
newChannel.Reject(ssh.UnknownChannelType, "unknown channel type")
continue
}
channel, requests, err := newChannel.Accept()
if err != nil {
panic("could not accept channel.")
}
// Sessions have out-of-band requests such as "shell",
// "pty-req" and "env". Here we handle only the
// "shell" request.
go func(in <-chan *ssh.Request) {
for req := range in {
ok := false
switch req.Type {
case "shell":
ok = true
if len(req.Payload) > 0 {
// We don't accept any
// commands, only the
// default shell.
ok = false
}
}
req.Reply(ok, nil)
}
}(requests)
term := terminal.NewTerminal(channel, "> ")
go func() {
defer channel.Close()
for {
line, err := term.ReadLine()
if err != nil {
break
}
fmt.Println(line)
}
}()
}
}