#!/usr/bin/python
# -*- coding: utf-8 -*-

import subprocess
import mechanize
import cookielib
import getpass
import sys
import os
import ssl
import argparse
import atexit
import signal
import ConfigParser
import time
import binascii
import hmac
import hashlib
import shlex
import tncc

ssl._create_default_https_context = ssl._create_unverified_context

"""
OATH code from https://github.com/bdauvergne/python-oath
Copyright 2010, Benjamin Dauvergne

* All rights reserved.
* Redistribution and use in source and binary forms, with or without
  modification, are permitted provided that the following conditions are met:

     * Redistributions of source code must retain the above copyright
       notice, this list of conditions and the following disclaimer.
     * Redistributions in binary form must reproduce the above copyright
       notice, this list of conditions and the following disclaimer in the
       documentation and/or other materials provided with the distribution.'''
"""

def truncated_value(h):
    bytes = map(ord, h)
    offset = bytes[-1] & 0xf
    v = (bytes[offset] & 0x7f) << 24 | (bytes[offset+1] & 0xff) << 16 | \
            (bytes[offset+2] & 0xff) << 8 | (bytes[offset+3] & 0xff)
    return v

def dec(h,p):
    v = truncated_value(h)
    v = v % (10**p)
    return '%0*d' % (p, v)

def int2beint64(i):
    hex_counter = hex(long(i))[2:-1]
    hex_counter = '0' * (16 - len(hex_counter)) + hex_counter
    bin_counter = binascii.unhexlify(hex_counter)
    return bin_counter

def hotp(key):
    key = binascii.unhexlify(key)
    counter = int2beint64(int(time.time()) / 30)
    return dec(hmac.new(key, counter, hashlib.sha256).digest(), 6)

class juniper_vpn(object):
    def __init__(self, args):
        self.args = args
        self.fixed_password = args.password is not None
        self.last_connect = 0

        self.br = mechanize.Browser()

        self.cj = cookielib.LWPCookieJar()
        self.br.set_cookiejar(self.cj)

        # Browser options
        self.br.set_handle_equiv(True)
        self.br.set_handle_redirect(True)
        self.br.set_handle_referer(True)
        self.br.set_handle_robots(False)

        # Follows refresh 0 but not hangs on refresh > 0
        self.br.set_handle_refresh(mechanize._http.HTTPRefreshProcessor(),
                              max_time=1)

        # Want debugging messages?
        #self.br.set_debug_http(True)
        #self.br.set_debug_redirects(True)
        #self.br.set_debug_responses(True)

        self.user_agent = 'Mozilla/5.0 (X11; U; Linux i686; en-US; rv:1.9.0.1) Gecko/2008071615 Fedora/3.0.1-1.fc9 Firefox/3.0.1'
        self.br.addheaders = [('User-agent', self.user_agent)]

        self.last_action = None
        self.needs_2factor = False
        self.key = None
        self.pass_postfix = None

    def find_cookie(self, name):
        for cookie in self.cj:
            if cookie.name == name:
                return cookie
        return None

    def next_action(self):
        if self.find_cookie('DSID'):
            return 'connect'

        for form in self.br.forms():
            if form.name == 'frmLogin':
                return 'login'
            elif form.name == 'frmDefender':
                return 'key'
            elif form.name == 'frmConfirmation':
                return 'continue'
            else:
                raise Exception('Unknown form type:', form.name)
        return 'tncc'

    def run(self):
        # Open landing page
        self.r = self.br.open('https://' + self.args.host)
        while True:
            action = self.next_action()
            if action == 'tncc':
                self.action_tncc()
            elif action == 'login':
                self.action_login()
            elif action == 'key':
                self.action_key()
            elif action == 'continue':
                self.action_continue()
            elif action == 'connect':
                self.action_connect()

            self.last_action = action

    def action_tncc(self):
        # Run tncc host checker
        dspreauth_cookie = self.find_cookie('DSPREAUTH')
        if dspreauth_cookie is None:
            raise Exception('Could not find DSPREAUTH key for host checker')

        dssignin_cookie = self.find_cookie('DSSIGNIN')
        t = tncc.tncc(self.args.host);
        self.cj.set_cookie(t.get_cookie(dspreauth_cookie, dssignin_cookie))

        self.r = self.br.open(self.r.geturl())

    def action_login(self):
        # The token used for two-factor is selected when this form is submitted.
        # If we aren't getting a password, then get the key now, otherwise
        # we could be sitting on the two factor key prompt later on waiting
        # on the user.

        if self.args.password is None or self.last_action == 'login':
            if self.fixed_password:
                print 'Login failed (Invalid username or password?)'
                sys.exit(1)
            else:
                self.args.password = getpass.getpass('Password:')
                self.needs_2factor = False
        if self.args.pass_prefix:
            self.pass_postfix = getpass.getpass("Secondary password postfix:")
        if self.needs_2factor:
            if self.args.oath:
                self.key = hotp(self.args.oath)
            else:
                self.key = getpass.getpass('Two-factor key:')
        else:
            self.key = None

        # Enter username/password
        self.br.select_form(nr=0)
        self.br.form['username'] = self.args.username
        self.br.form['password'] = self.args.password
        if self.args.pass_prefix:
            if self.pass_postfix:
                secondary_password = "".join([  self.args.pass_prefix,
                                                self.pass_postfix])
            else:
                print 'Secondary password postfix not provided'
                sys.exit(1)
            self.br.form['password#2'] = secondary_password
        # Untested, a list of availables realms is provided when this
        # is necessary.
        # self.br.form['realm'] = [realm]
        self.r = self.br.submit()

    def action_key(self):
        # Enter key
        self.needs_2factor = True
        if self.args.oath:
            if self.last_action == 'key':
                print 'Login failed (Invalid OATH key)'
                sys.exit(1)
            self.key = hotp(self.args.oath)
        elif self.key is None:
            self.key = getpass.getpass('Two-factor key:')
        self.br.select_form(nr=0)
        self.br.form['password'] = self.key
        self.key = None
        self.r = self.br.submit()

    def action_continue(self):
        # Yes, I want to terminate the existing connection
        self.br.select_form(nr=0)
        self.r = self.br.submit()

    def action_connect(self):
        now = time.time()
        delay = 10.0 - (now - self.last_connect)
        if delay > 0:
            print 'Waiting %.0f...' % (delay)
            time.sleep(delay)
        self.last_connect = time.time();

        dsid = self.find_cookie('DSID').value
        action = []
        for arg in self.args.action:
            arg = arg.replace('%DSID%', dsid).replace('%HOST%', self.args.host)
            action.append(arg)

        p = subprocess.Popen(action, stdin=subprocess.PIPE)
        if args.stdin is not None:
            stdin = args.stdin.replace('%DSID%', dsid)
            stdin = stdin.replace('%HOST%', self.args.host)
            p.communicate(input = stdin)
        else:
            ret = p.wait()
        ret = p.returncode

        # Openconnect specific
        if ret == 2:
            self.cj.clear(self.args.host, '/', 'DSID')
            self.r = self.br.open(self.r.geturl())

def cleanup():
    os.killpg(0, signal.SIGTERM)

if __name__ == "__main__":
    parser = argparse.ArgumentParser(conflict_handler='resolve')
    parser.add_argument('-h', '--host', type=str,
                        help='VPN host name')
    parser.add_argument('-u', '--username', type=str,
                        help='User name')
    parser.add_argument('-p', '--pass_prefix', type=str,
                        help="Secondary password prefix")
    parser.add_argument('-o', '--oath', type=str,
                        help='OATH key for two factor authentication (hex)')
    parser.add_argument('-c', '--config', type=str,
                        help='Config file')
    parser.add_argument('-s', '--stdin', type=str,
                        help="String to pass to action's stdin")
    parser.add_argument('action', nargs=argparse.REMAINDER,
                        metavar='<action> [<args...>]',
                        help='External command')

    args = parser.parse_args()
    args.__dict__['password'] = None

    if len(args.action) and args.action[0] == '--':
        args.action = args.action[1:]

    if not len(args.action):
        args.action = None

    if args.config is not None:
        config = ConfigParser.RawConfigParser()
        config.read(args.config)
        for arg in ['username', 'host', 'password', 'pass_prefix', 'oath', 'action', 'stdin']:
            if args.__dict__[arg] is None:
                try:
                    args.__dict__[arg] = config.get('vpn', arg)
                except:
                    pass

    if not isinstance(args.action, list):
        args.action = shlex.split(args.action)

    if args.username == None or args.host == None or args.action == []:
        print "--user, --host, and <action> are required parameters"
        sys.exit(1)

    atexit.register(cleanup)
    jvpn = juniper_vpn(args)
    jvpn.run()