pymeds/SSDP.py

# Licensed under the MIT license
# http://opensource.org/licenses/mit-license.php

# (c) 2005, Tim Potter <tpot@samba.org>

#
# Implementation of SSDP server under Twisted Python.
#

import random
import string

from twisted.python import log
from twisted.internet.protocol import DatagramProtocol
from twisted.internet import reactor

# TODO: Is there a better way of hooking the SSDPServer into a reactor
# without having to know the default SSDP port and multicast address?
# There must be a twisted idiom for doing this.

SSDP_PORT = 1900
SSDP_ADDR = '239.255.255.250'

# TODO: Break out into a HTTPOverUDP class and implement
# process_SEARCH(), process_NOTIFY() methods.  Create UPNP specific
# class to handle services etc.

class SSDPServer(DatagramProtocol):
    """A class implementing a SSDP server.  The notifyReceived and
    searchReceived methods are called when the appropriate type of
    datagram is received by the server."""

    # not used yet
    stdheaders = [ ('Server', 'Twisted, UPnP/1.0, python-upnp'), ]
    elements = {}
    known = {}

    def datagramReceived(self, data, (host, port)):
        """Handle a received multicast datagram."""

        # Break up message in to command and headers

	log.msg('respond to: %s:%d' % (host, port))
        header, payload = data.split('\r\n\r\n')
	lines = header.split('\r\n')
        cmd = string.split(lines[0], ' ')
	lines = map(lambda x: x.replace(': ', ':', 1), lines[1:])
        lines = filter(lambda x: len(x) > 0, lines)

	headers = [string.split(x, ':', 1) for x in lines]
        headers = dict(map(lambda x: (x[0].lower(), x[1]), headers))

        if cmd[0] == 'M-SEARCH' and cmd[1] == '*':
	    # SSDP discovery
            self.discoveryRequest(headers, (host, port))
        elif cmd[0] == 'NOTIFY' and cmd[1] == '*':
	    # SSDP presence
            self.notifyReceived(headers, (host, port))
	else:
	    log.msg('Unknown SSDP command %s %s' % cmd)

    def discoveryRequest(self, headers, (host, port)):
        """Process a discovery request.  The response must be sent to
        the address specified by (host, port)."""

        log.msg('Discovery request for %s' % headers['st'])

        # Do we know about this service?

	if headers['st'] == 'ssdp:all':
	    for i in self.known:
		hcopy = dict(headers.iteritems())
		hcopy['st'] = i
		self.discoveryRequest(hcopy, (host, post))
	    return
        if not self.known.has_key(headers['st']):
            return

        # Generate a response

        response = []
        response.append('HTTP/1.1 200 OK')

        for k, v in self.known[headers['st']].items():
            response.append('%s: %s' % (k, v))

	response.extend(('', ''))
	delay = random.randint(0, int(headers['mx']))
	reactor.callLater(delay, self.transport.write,
	    '\r\n'.join(response), (host, port))

    def register(self, usn, st, location):
        """Register a service or device that this SSDP server will
        respond to."""

        log.msg('Registering %s' % st)
        
        self.known[st] = {}
        self.known[st]['USN'] = usn
        self.known[st]['LOCATION'] = location
        self.known[st]['ST'] = st
        self.known[st]['EXT'] = ''
        self.known[st]['SERVER'] = 'Twisted, UPnP/1.0, python-upnp'
        self.known[st]['CACHE-CONTROL'] = 'max-age=1800'
	self.doNotify(st)

    def doNotify(self, st):
	"""Do notification"""

        log.msg('Sending alive notification for %s' % st)

	resp = [ 'NOTIFY * HTTP/1.1',
		'Host: %s:%d' % (SSDP_ADDR, SSDP_PORT),
		'NTS: ssdp:alive',
	    ]
	stcpy = dict(self.known[st].iteritems())
	stcpy['NT'] = stcpy['ST']
	del stcpy['ST']
	resp.extend(map(lambda x: ': '.join(x), stcpy.iteritems()))
	resp.extend(('', ''))
        self.transport.write('\r\n'.join(resp), (SSDP_ADDR, SSDP_PORT))

    def notifyReceived(self, headers, (host, port)):
        """Process a presence announcement.  We just remember the
        details of the SSDP service announced."""

        if headers['nts'] == 'ssdp:alive':

            if not self.elements.has_key(headers['nt']):

                # Register device/service

                self.elements[headers['nt']] = {}
                self.elements[headers['nt']]['USN'] = headers['usn']
                self.elements[headers['nt']]['host'] = (host, port)

                log.msg('Detected presence for %s' % headers['nt'])

        elif headers['nts'] == 'ssdp:byebye':

            if self.elements.has_key(headers['nt']):

                # Unregister device/service
                
                del(self.elements[headers['nt']])

                log.msg('Detected absence for %s' % headers['nt'])
                
        else:
            log.msg('Unknown subtype %s for notification type %s' %
                    (headers['nts'], headers['nt']))

    def findService(self, name):
        """Return information about a service registered over SSDP."""

        # TODO: Implement me.

        # TODO: Send out a discovery request if we haven't registered
        # a presence announcement.

    def findDevice(self, name):
        """Return information about a device registered over SSDP."""

        # TODO: Implement me.

        # TODO: Send out a discovery request if we haven't registered
        # a presence announcement.