Re: [Twisted-Python] socket communications in flash

June 17, 2003


      On Thursday, Jun 12, 2003, at 20:00 America/New_York, e okyere wrote:
...
I am looking at doing low-level sock comms with flash mx and hopefully  
c++
and upon hitting this thread:
http://twistedmatrix.com/pipermail/twisted-python/2002-May/001121.html
thought I should contact you to see if you have any experience in that  
line.
If so, I'd appreciate any resources you can share or point to.
This is similar to how I've done it in the past (warning: untested, not  
commented, mostly rape & paste from other code I've written):

########
import sys, random, md5
from twisted.python.compat import True, False
from twisted.python import log
from twisted.protocols.basic import LineReceiver
from twisted.web import microdom
from twisted.internet.protocol import Factory


class XMLPipe(LineReceiver):
     delimiter = '\0'

     def connectionMade(self):
         pass

     def sendMessage(self, message):
         self.transport.writeSequence(('<packet>', str(message),  
'</packet>', self.delimiter))

     def lineReceived(self, line):
         if not line:
             log.msg("WARNING:  Empty message from client")
             return
         packet = microdom.parseString(line).childNodes[0]
         if packet.nodeName != 'packet':
             raise ValueError, '%r is not a packet tag' % packet
         self.packetReceived(packet)

     def packetReceived(self, packet):
         raise NotImplementedError

     def connectionLost(self, reason):
         pass

class FlashPipe(XMLPipe):
     def connectionMade(self):
         self.authenticated = False
         self.user = None
         self.issueChallenge()

     def packetReceived(self, packet):
         for node in packet.childNodes:
             self.nodeReceived(node)

     def nodeReceived(self, node):
         return getattr(self, 'handle_'+node.nodeName,  
self.xmlerror)(node)

     def xmlerror(self, node):
         log.msg('Unrecognized Node %r %r' % (node, node.toxml()))
         self.sendMessage('<error>Unrecognized Node</error>')

     def issueChallenge(self):
         # some entropy
         self.pendingChallenge = md5.new(''.join((
             hex(id(self)),
             hex(random.randrange(sys.maxint)),
         ))).hexdigest()
         self.sendMessage(''.join(
             ('<challenge>', self.pendingChallenge, '</challenge>'
         )))

     def handle_response(self, node):
         resp = node.firstChild().nodeValue.strip()
         for possible, user in self.factory.authorized.iteritems():
             h = md5.new(self.pendingChallenge)
             h.update(possible)
             if h.hexdigest() == resp:
                 break
         else:
             return
         log.msg('authenticated as %s' % user)
         self.user = user
         self.authenticated = True
         self.sendMessage('<authenticated />')

class FlashXMLFactory(Factory):
     noisy = 0
     protocol = FlashPipe
     authorized = {'somerandomdata' : 'valid user'}

if __name__=='__main__':
     from twisted.internet import reactor
     log.startLogging(sys.stdout)
     reactor.listenTCP(8888, FlashXMLFactory())
     reactor.run()

####

A conversation would look like this:
SERVER:  
'<packet><challenge>d41d8cd98f00b204e9800998ecf8427e</challenge></ 
packet>\0'
CLIENT:  
'<packet><response>f87504a987151d223335f0753f010b74</response></ 
packet>\0'
SERVER: '<packet><authenticated /></packet>\0'

-bob

Re: [Twisted-Python] socket communications in flash

Bob Ippolito