#!/usr/bin/env python
#
# flashpolicyd.py
# Simple socket policy file server for Flash
#
# Usage: flashpolicyd.py [--port=N] --file=FILE
#
# Logs to stderr
# Requires Python 2.5 or later

from __future__ import with_statement
import os
import sys
import optparse
import socket
import thread
import exceptions
import contextlib

VERSION = 0.1


def daemon():
    """Daemonize the current process."""
    if os.fork() != 0:
        os._exit(0)
    os.setsid()
    if os.fork() != 0:
        os._exit(0)
    os.umask(0)
    devnull = os.open(os.devnull, os.O_RDWR)
    os.dup2(devnull, 0)
    # xxx fixme - this is just to make sure that nothing gets stupidly lost -
    # should use devnull
    crashlog = os.open('/var/log/sfa_flashpolicy.log', os.O_RDWR | os.O_APPEND | os.O_CREAT, 0644)
    os.dup2(crashlog, 1)
    os.dup2(crashlog, 2)


class policy_server(object):

    def __init__(self, port, path):
        self.port = port
        self.path = path
        self.policy = self.read_policy(path)
        self.log('Listening on port %d\n' % port)
        try:
            self.sock = socket.socket(socket.AF_INET6, socket.SOCK_STREAM)
        except AttributeError:
            # AttributeError catches Python built without IPv6
            self.sock = socket.socket(socket.AF_INET, socket.SOCK_STREAM)
        except socket.error:
            # socket.error catches OS with IPv6 disabled
            self.sock = socket.socket(socket.AF_INET, socket.SOCK_STREAM)
        self.sock.setsockopt(socket.SOL_SOCKET, socket.SO_REUSEADDR, 1)
        self.sock.bind(('', port))
        self.sock.listen(5)

    def read_policy(self, path):
        with open(path, 'rb') as f:
            policy = f.read(10001)
            if len(policy) > 10000:
                raise exceptions.RuntimeError('File probably too large to be a policy file',
                                              path)
            if 'cross-domain-policy' not in policy:
                raise exceptions.RuntimeError('Not a valid policy file',
                                              path)
            return policy

    def run(self):
        try:
            while True:
                thread.start_new_thread(self.handle, self.sock.accept())
        except socket.error as e:
            self.log('Error accepting connection: %s' % e[1])

    def handle(self, conn, addr):
        addrstr = '%s:%s' % (addr[0], addr[1])
        try:
            self.log('Connection from %s' % addrstr)
            with contextlib.closing(conn):
                # It's possible that we won't get the entire request in
                # a single recv, but very unlikely.
                request = conn.recv(1024).strip()
                # if request != '<policy-file-request/>\0':
                #    self.log('Unrecognized request from %s: %s' % (addrstr, request))
                #    return
                self.log('Valid request received from %s' % addrstr)
                conn.sendall(self.policy)
                self.log('Sent policy file to %s' % addrstr)
        except socket.error as e:
            self.log('Error handling connection from %s: %s' % (addrstr, e[1]))
        except Exception as e:
            self.log('Error handling connection from %s: %s' % (addrstr, e[1]))

    def log(self, str):
        print >>sys.stderr, str


def main():
    parser = optparse.OptionParser(usage='%prog [--port=PORT] --file=FILE',
                                   version='%prog ' + str(VERSION))
    parser.add_option('-p', '--port', dest='port', type=int, default=843,
                      help='listen on port PORT', metavar='PORT')
    parser.add_option('-f', '--file', dest='path',
                      help='server policy file FILE', metavar='FILE')
    parser.add_option("-d", "--daemon", dest="daemon", action="store_true",
                      help="Run as daemon.", default=False)
    opts, args = parser.parse_args()
    if args:
        parser.error('No arguments are needed. See help.')
    if not opts.path:
        parser.error('File must be specified. See help.')

    try:
        if opts.daemon:
            daemon()
        policy_server(opts.port, opts.path).run()
    except Exception as e:
        print >> sys.stderr, e
        sys.exit(1)
    except KeyboardInterrupt:
        pass

if __name__ == '__main__':
    main()