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SSDP.py
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SSDP.py
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# Licensed under the MIT license
# http://opensource.org/licenses/mit-license.php
# Copyright 2005, Tim Potter <tpot@samba.org>
# Copyright 2006-2007 John-Mark Gurney <jmg@funkthat.com>
__version__ = '$Change: 1227 $'
# $Id: //depot/python/pymeds/pymeds-0.5/SSDP.py#1 $
#
# 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, task
# 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 = {}
maxage = 7 * 24 * 60 * 60
def doStop(self):
'''Make sure we send out the byebye notifications.'''
for st in self.known.keys():
self.doByebye(st)
del self.known[st]
DatagramProtocol.doStop(self)
def datagramReceived(self, data, (host, port)):
"""Handle a received multicast datagram."""
# Break up message in to command and headers
# TODO: use the email module after trimming off the request line..
# This gets us much better header support.
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, port))
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=%d' % self.maxage
self.doNotifySchedule(st)
reactor.callLater(random.uniform(.5, 1), lambda: self.doNotify(st))
reactor.callLater(random.uniform(1, 5), lambda: self.doNotify(st))
def doNotifySchedule(self, st):
self.doNotify(st)
reactor.callLater(random.uniform(self.maxage / 3,
self.maxage / 2), lambda: self.doNotifySchedule(st))
def doByebye(self, st):
"""Do byebye"""
log.msg('Sending byebye notification for %s' % st)
resp = [ 'NOTIFY * HTTP/1.1',
'Host: %s:%d' % (SSDP_ADDR, SSDP_PORT),
'NTS: ssdp:byebye',
]
stcpy = dict(self.known[st].iteritems())
stcpy['NT'] = stcpy['ST']
del stcpy['ST']
resp.extend(map(lambda x: ': '.join(x), stcpy.iteritems()))
resp.extend(('', ''))
resp = '\r\n'.join(resp)
self.transport.write(resp, (SSDP_ADDR, SSDP_PORT))
self.transport.write(resp, (SSDP_ADDR, SSDP_PORT))
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 of %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.