ejabberd_auth.py

"""Author: Rob Moore <giftiger.wunsch@xantoria.com>"""

import logging
import signal
import struct
import sys

from django.contrib.auth.models import check_password
from django.contrib.auth.models import User
from django.core.management.base import BaseCommand


logger = logging.getLogger(__name__)


class Command(BaseCommand):
    help = 'Interface between ejabberd and django; an auth service for XMPP'
    stopping = False

    @staticmethod
    def write_response(success=False):
        """Creates and sends a response back to the ejabberd server."""
        result = 1 if success else 0
        sys.stdout.write(struct.pack('>hh', 2, result))
        sys.stdout.flush()

    @staticmethod
    def _handle_isuser(username, server):
        """
        Handles the `isuser` ejabberd command, indicating whether or not
        the requested user exists in the system.
        """
        return Command.write_response(
            User.objects.filter(username=username).exists()
        )

    @staticmethod
    def _handle_auth(username, server, password):
        """Handles authentication of the user"""
        user = User.objects.filter(username=username)
        if not user:
            return Command.write_response(False)

        user = user[0]
        result = check_password(password, user.password)
        return Command.write_response(result)

    def handle_request(self):
        """Read an ejabberd request and respond to it"""
        try:
            data_size = struct.unpack('>h', sys.stdin.read(2))[0]
            data = sys.stdin.read(data_size).split(':')
            command = input.pop(0)
        # If anything goes wrong, tell ejabberd it's being dumb; don't crash
        except:
            logger.exception('ejabberd gave us a bad request!')
            return Command.write_response(False)

        handler = getattr(Command, '_handle_%s' % command, None)

        # Fail silently; we don't support all commands, but it doesn't mean
        # ejabberd isn't going to attempt them, possibly frequently
        if handler is None:
            return Command.write_response(False)

        return handler(*data)

    def handle(self, **options):
        """
        Per ejabberd external auth API specification, keep listening for
        auth or 'isuser' requests and responding as appropriate using utility
        methods.
        """
        # If we get a SIGINT, stop after we've dealt with the current command
        signal.signal(signal.SIGINT, self.stop_gracefully)

        while not Command.stopping:
            Command.handle_request()

    @staticmethod
    def stop_gracefully(*args):
        Command.stopping = True