#!/usr/bin/env python

# Copyright (c) Twisted Matrix Laboratories.
# See LICENSE for details.
import getpass
import os
import struct
import sys

from twisted.conch.ssh import channel, common, connection, keys, transport, userauth
from twisted.internet import defer, protocol, reactor
from twisted.python import log

"""
Example of using a simple SSH client.

It will try to authenticate with a SSH key or ask for a password.

Re-using a private key is dangerous, generate one.
For this example you can use:

$ ckeygen -t rsa -f ssh-keys/client_rsa
"""

# Replace this with your username.
# Default username and password will match the sshsimpleserver.py
USER = b"user"
HOST = "localhost"
PORT = 5022
SERVER_FINGERPRINT = b"55:55:66:24:6b:03:0e:f1:ec:f8:66:c3:51:df:27:4b"

# Path to RSA SSH keys accepted by the server.
CLIENT_RSA_PUBLIC = "ssh-keys/client_rsa.pub"
# Set CLIENT_RSA_PUBLIC to empty to not use SSH key auth.
# CLIENT_RSA_PUBLIC = ''
CLIENT_RSA_PRIVATE = "ssh-keys/client_rsa"


class SimpleTransport(transport.SSHClientTransport):
    def verifyHostKey(self, hostKey, fingerprint):
        print("Server host key fingerprint: %s" % fingerprint)
        if SERVER_FINGERPRINT == fingerprint:
            return defer.succeed(True)
        else:
            print("Bad host key. Expecting: %s" % SERVER_FINGERPRINT)
            return defer.fail(Exception("Bad server key"))

    def connectionSecure(self):
        self.requestService(SimpleUserAuth(USER, SimpleConnection()))


class SimpleUserAuth(userauth.SSHUserAuthClient):
    def getPassword(self):
        return defer.succeed(getpass.getpass(f"{USER}@{HOST}'s password: "))

    def getGenericAnswers(self, name, instruction, questions):
        print(name)
        print(instruction)
        answers = []
        for prompt, echo in questions:
            if echo:
                answer = input(prompt)
            else:
                answer = getpass.getpass(prompt)
            answers.append(answer)
        return defer.succeed(answers)

    def getPublicKey(self):
        if (
            not CLIENT_RSA_PUBLIC
            or not os.path.exists(CLIENT_RSA_PUBLIC)
            or self.lastPublicKey
        ):
            # the file doesn't exist, or we've tried a public key
            return
        return keys.Key.fromFile(filename=CLIENT_RSA_PUBLIC)

    def getPrivateKey(self):
        """
        A deferred can also be returned.
        """
        return defer.succeed(keys.Key.fromFile(CLIENT_RSA_PRIVATE))


class SimpleConnection(connection.SSHConnection):
    def serviceStarted(self):
        self.openChannel(TrueChannel(2 ** 16, 2 ** 15, self))
        self.openChannel(FalseChannel(2 ** 16, 2 ** 15, self))
        self.openChannel(CatChannel(2 ** 16, 2 ** 15, self))


class TrueChannel(channel.SSHChannel):
    name = b"session"  # needed for commands

    def openFailed(self, reason):
        print("true failed", reason)

    def channelOpen(self, ignoredData):
        self.conn.sendRequest(self, "exec", common.NS("true"))

    def request_exit_status(self, data):
        status = struct.unpack(">L", data)[0]
        print("true status was: %s" % status)
        self.loseConnection()


class FalseChannel(channel.SSHChannel):
    name = b"session"

    def openFailed(self, reason):
        print("false failed", reason)

    def channelOpen(self, ignoredData):
        self.conn.sendRequest(self, "exec", common.NS("false"))

    def request_exit_status(self, data):
        status = struct.unpack(">L", data)[0]
        print("false status was: %s" % status)
        self.loseConnection()


class CatChannel(channel.SSHChannel):
    name = b"session"

    def openFailed(self, reason):
        print("echo failed", reason)

    def channelOpen(self, ignoredData):
        self.data = b""
        d = self.conn.sendRequest(self, "exec", common.NS("cat"), wantReply=1)
        d.addCallback(self._cbRequest)

    def _cbRequest(self, ignored):
        self.write(b"hello conch\n")
        self.conn.sendEOF(self)

    def dataReceived(self, data):
        self.data += data

    def closed(self):
        print("got data from cat: %s" % repr(self.data))
        self.loseConnection()
        reactor.stop()


log.startLogging(sys.stdout)
protocol.ClientCreator(reactor, SimpleTransport).connectTCP(HOST, PORT)
reactor.run()