package main

import (
	"fmt"
	"io"
	"io/ioutil"
	"log"
	"os"
	"os/exec"

	"github.com/gliderlabs/ssh"
	gossh "golang.org/x/crypto/ssh"
)

func shellHandler(s ssh.Session) {
	cmd := exec.Command("/bin/rc")
	stdin, err := cmd.StdinPipe()
	if err != nil {
		log.Fatal(err)
	}
	stdout, err := cmd.StdoutPipe()
	if err != nil {
		log.Fatal(err)
	}
	/*
		stderr, err := cmd.StderrPipe()
		if err != nil {
			log.Fatal(err)
		}
	*/
	err = cmd.Start()
	if err != nil {
		log.Fatal(err)
	}
	go io.Copy(stdin, s)
	io.Copy(s, stdout)
}

func main() {
	if len(os.Args) < 2 {
		fmt.Fprintf(os.Stderr, "Usage: %s path-to-pubkey\n", os.Args[0])
	}
	pubAuth := ssh.PublicKeyAuth(func(ctx ssh.Context, key ssh.PublicKey) bool {
		data, err := ioutil.ReadFile(os.Args[1])
		if err != nil {
			log.Fatal(err)
		}
		allowed, _, _, _, _ := ssh.ParseAuthorizedKey(data)
		return ssh.KeysEqual(key, allowed)
	})
	priv, err := ioutil.ReadFile("./id_rsa")
	if err != nil {
		log.Fatal(err)
	}
	signer, err := gossh.ParsePrivateKey(priv)
	if err != nil {
		log.Fatal(err)
	}
	s := &ssh.Server{
		Addr:    ":2222",
		Handler: shellHandler,
	}
	s.AddHostKey(signer)
	err = s.SetOption(ssh.NoPty())
	if err != nil {
		log.Fatal(err)
	}
	err = s.SetOption(pubAuth)
	if err != nil {
		log.Fatal(err)
	}

	log.Println("starting ssh server on port 2222...")
	log.Fatal(s.ListenAndServe())
}