#!/usr/bin/env python

# Copyright (C) 2011  Jeff Forcier <jeff@bitprophet.org>
#
# This file is part of ssh.
#
# 'ssh' is free software; you can redistribute it and/or modify it under the
# terms of the GNU Lesser General Public License as published by the Free
# Software Foundation; either version 2.1 of the License, or (at your option)
# any later version.
#
# 'ssh' is distrubuted in the hope that it will be useful, but WITHOUT ANY
# WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR
# A PARTICULAR PURPOSE.  See the GNU Lesser General Public License for more
# details.
#
# You should have received a copy of the GNU Lesser General Public License
# along with 'ssh'; if not, write to the Free Software Foundation, Inc.,
# 51 Franklin Street, Suite 500, Boston, MA  02110-1335  USA.


import base64
from binascii import hexlify
import getpass
import os
import select
import socket
import sys
import threading
import time
import traceback

import ssh
import interactive


def agent_auth(transport, username):
    """
    Attempt to authenticate to the given transport using any of the private
    keys available from an SSH agent.
    """
    
    agent = ssh.Agent()
    agent_keys = agent.get_keys()
    if len(agent_keys) == 0:
        return
        
    for key in agent_keys:
        print 'Trying ssh-agent key %s' % hexlify(key.get_fingerprint()),
        try:
            transport.auth_publickey(username, key)
            print '... success!'
            return
        except ssh.SSHException:
            print '... nope.'


def manual_auth(username, hostname):
    default_auth = 'p'
    auth = raw_input('Auth by (p)assword, (r)sa key, or (d)ss key? [%s] ' % default_auth)
    if len(auth) == 0:
        auth = default_auth

    if auth == 'r':
        default_path = os.path.join(os.environ['HOME'], '.ssh', 'id_rsa')
        path = raw_input('RSA key [%s]: ' % default_path)
        if len(path) == 0:
            path = default_path
        try:
            key = ssh.RSAKey.from_private_key_file(path)
        except ssh.PasswordRequiredException:
            password = getpass.getpass('RSA key password: ')
            key = ssh.RSAKey.from_private_key_file(path, password)
        t.auth_publickey(username, key)
    elif auth == 'd':
        default_path = os.path.join(os.environ['HOME'], '.ssh', 'id_dsa')
        path = raw_input('DSS key [%s]: ' % default_path)
        if len(path) == 0:
            path = default_path
        try:
            key = ssh.DSSKey.from_private_key_file(path)
        except ssh.PasswordRequiredException:
            password = getpass.getpass('DSS key password: ')
            key = ssh.DSSKey.from_private_key_file(path, password)
        t.auth_publickey(username, key)
    else:
        pw = getpass.getpass('Password for %s@%s: ' % (username, hostname))
        t.auth_password(username, pw)


# setup logging
ssh.util.log_to_file('demo.log')

username = ''
if len(sys.argv) > 1:
    hostname = sys.argv[1]
    if hostname.find('@') >= 0:
        username, hostname = hostname.split('@')
else:
    hostname = raw_input('Hostname: ')
if len(hostname) == 0:
    print '*** Hostname required.'
    sys.exit(1)
port = 22
if hostname.find(':') >= 0:
    hostname, portstr = hostname.split(':')
    port = int(portstr)

# now connect
try:
    sock = socket.socket(socket.AF_INET, socket.SOCK_STREAM)
    sock.connect((hostname, port))
except Exception, e:
    print '*** Connect failed: ' + str(e)
    traceback.print_exc()
    sys.exit(1)

try:
    t = ssh.Transport(sock)
    try:
        t.start_client()
    except ssh.SSHException:
        print '*** SSH negotiation failed.'
        sys.exit(1)

    try:
        keys = ssh.util.load_host_keys(os.path.expanduser('~/.ssh/known_hosts'))
    except IOError:
        try:
            keys = ssh.util.load_host_keys(os.path.expanduser('~/ssh/known_hosts'))
        except IOError:
            print '*** Unable to open host keys file'
            keys = {}

    # check server's host key -- this is important.
    key = t.get_remote_server_key()
    if not keys.has_key(hostname):
        print '*** WARNING: Unknown host key!'
    elif not keys[hostname].has_key(key.get_name()):
        print '*** WARNING: Unknown host key!'
    elif keys[hostname][key.get_name()] != key:
        print '*** WARNING: Host key has changed!!!'
        sys.exit(1)
    else:
        print '*** Host key OK.'

    # get username
    if username == '':
        default_username = getpass.getuser()
        username = raw_input('Username [%s]: ' % default_username)
        if len(username) == 0:
            username = default_username

    agent_auth(t, username)
    if not t.is_authenticated():
        manual_auth(username, hostname)
    if not t.is_authenticated():
        print '*** Authentication failed. :('
        t.close()
        sys.exit(1)

    chan = t.open_session()
    chan.get_pty()
    chan.invoke_shell()
    print '*** Here we go!'
    print
    interactive.interactive_shell(chan)
    chan.close()
    t.close()

except Exception, e:
    print '*** Caught exception: ' + str(e.__class__) + ': ' + str(e)
    traceback.print_exc()
    try:
        t.close()
    except:
        pass
    sys.exit(1)