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package main
import (
"errors"
"fmt"
"io"
"log"
"os"
"strings"
"github.com/chzyer/readline"
"github.com/gliderlabs/ssh"
"github.com/google/shlex"
"github.com/kr/pty"
"golang.org/x/crypto/ssh/terminal"
"github.com/alecthomas/colour"
"github.com/alecthomas/kong"
)
// Handle a single SSH interactive connection.
func handle(log *log.Logger, s ssh.Session) error {
log.Printf("New SSH")
sshPty, _, isPty := s.Pty()
if !isPty {
return errors.New("no PTY requested")
}
log.Printf("Using TERM=%s width=%d height=%d", sshPty.Term, sshPty.Window.Width, sshPty.Window.Height)
cpty, tty, err := pty.Open()
if err != nil {
return err
}
defer tty.Close()
state, err := terminal.GetState(int(cpty.Fd()))
if err != nil {
return err
}
defer terminal.Restore(int(cpty.Fd()), state)
colour.Fprintln(tty, "^BWelcome!^R")
go io.Copy(cpty, s)
go io.Copy(s, cpty)
parser, err := buildShellParser(tty)
if err != nil {
return err
}
rl, err := readline.NewEx(&readline.Config{
Prompt: "> ",
Stderr: tty,
Stdout: tty,
Stdin: tty,
FuncOnWidthChanged: func(f func()) {},
FuncMakeRaw: func() error {
_, err := terminal.MakeRaw(int(cpty.Fd())) // nolint: govet
return err
},
FuncExitRaw: func() error { return nil },
})
if err != nil {
return err
}
log.Printf("Loop")
for {
tty.Sync()
var line string
line, err = rl.Readline()
if err != nil {
if err == io.EOF {
return nil
}
return err
}
var args []string
args, err := shlex.Split(string(line))
if err != nil {
parser.Errorf("%s", err)
continue
}
var ctx *kong.Context
ctx, err = parser.Parse(args)
if err != nil {
parser.Errorf("%s", err)
if err, ok := err.(*kong.ParseError); ok {
log.Println(err.Error())
err.Context.PrintUsage(false)
}
continue
}
err = ctx.Run(ctx)
if err != nil {
parser.Errorf("%s", err)
continue
}
}
}
func buildShellParser(tty *os.File) (*kong.Kong, error) {
parser, err := kong.New(&grammar{},
kong.Name(""),
kong.Description("Example using Kong for interactive command parsing."),
kong.Writers(tty, tty),
kong.Exit(func(int) {}),
kong.ConfigureHelp(kong.HelpOptions{
NoAppSummary: true,
}),
kong.NoDefaultHelp(),
)
return parser, err
}
func handlerWithError(handle func(log *log.Logger, s ssh.Session) error) ssh.Handler {
return func(s ssh.Session) {
prefix := fmt.Sprintf("%s->%s ", s.LocalAddr(), s.RemoteAddr())
l := log.New(os.Stdout, prefix, log.LstdFlags)
err := handle(l, s)
if err != nil {
log.Printf("error: %s", err)
s.Exit(1)
} else {
log.Printf("Bye")
s.Exit(0)
}
}
}
var cli struct {
HostKey string `type:"existingfile" help:"SSH host key to use." default:"server_rsa_key"`
Bind string `help:"Bind address for server." default:"127.0.0.1:6740"`
}
func main() {
ctx := kong.Parse(&cli,
kong.Name("server"),
kong.Description("A network server using Kong for interacting with clients."))
ssh.Handle(handlerWithError(handle))
log.Printf("SSH listening on: %s", cli.Bind)
log.Printf("Using host key: %s", cli.HostKey)
log.Println()
parts := strings.Split(cli.Bind, ":")
log.Printf("Connect with: ssh -p %s %s", parts[1], parts[0])
log.Println()
err := ssh.ListenAndServe(cli.Bind, nil, ssh.HostKeyFile(cli.HostKey))
ctx.FatalIfErrorf(err)
}
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