# The Evolution of Finger: using a single factory for multiple protocols

## Introduction

This is the eighth part of the Twisted tutorial Twisted from Scratch, or The Evolution of Finger.

In this part, we add HTTPS support to our web frontend, showing how to have a single factory listen on multiple ports.

## Support HTTPS

All we need to do to code an HTTPS site is just write a context factory (in this case, which loads the certificate from a certain file) and then use the twisted.application.internet.SSLServer method. Note that one factory (in this case, a site) can listen on multiple ports with multiple protocols.

    # Do everything properly, and componentize
    from twisted.application import internet, service
    from twisted.internet import protocol, reactor, defer
    from twisted.protocols import basic, irc
    from twisted.python import components
    from twisted.web import resource, server, static, xmlrpc, microdom
    from twisted.spread import pb
    from zope.interface import Interface, implements
    from OpenSSL import SSL
    import cgi

    class IFingerService(Interface):

        def getUser(self, user):
            """Return a deferred returning a string"""

        def getUsers(self):
            """Return a deferred returning a list of strings"""

    class IFingerSetterService(Interface):

        def setUser(self, user, status):
            """Set the user's status to something"""

    def catchError(err):
        return "Internal error in server"

    class FingerProtocol(basic.LineReceiver):

        def lineReceived(self, user):
            d = self.factory.getUser(user)
            d.addErrback(catchError)
            def writeValue(value):
                self.transport.write(value+'\r\n')
                self.transport.loseConnection()
            d.addCallback(writeValue)

    class IFingerFactory(Interface):

        def getUser(self, user):
            """Return a deferred returning a string"""

        def buildProtocol(self, addr):
            """Return a protocol returning a string"""

    class FingerFactoryFromService(protocol.ServerFactory):

        implements(IFingerFactory)

        protocol = FingerProtocol

        def __init__(self, service):
            self.service = service

        def getUser(self, user):
            return self.service.getUser(user)

    components.registerAdapter(FingerFactoryFromService,
                               IFingerService,
                               IFingerFactory)

    class FingerSetterProtocol(basic.LineReceiver):

        def connectionMade(self):
            self.lines = []

        def lineReceived(self, line):
            self.lines.append(line)

        def connectionLost(self, reason):
            if len(self.lines) == 2:
                self.factory.setUser(*self.lines)

    class IFingerSetterFactory(Interface):

        def setUser(self, user, status):
            """Return a deferred returning a string"""

        def buildProtocol(self, addr):
            """Return a protocol returning a string"""

    class FingerSetterFactoryFromService(protocol.ServerFactory):

        implements(IFingerSetterFactory)

        protocol = FingerSetterProtocol

        def __init__(self, service):
            self.service = service

        def setUser(self, user, status):
            self.service.setUser(user, status)

    components.registerAdapter(FingerSetterFactoryFromService,
                               IFingerSetterService,
                               IFingerSetterFactory)

    class IRCReplyBot(irc.IRCClient):

        def connectionMade(self):
            self.nickname = self.factory.nickname
            irc.IRCClient.connectionMade(self)

        def privmsg(self, user, channel, msg):
            user = user.split('!')[0]
            if self.nickname.lower() == channel.lower():
                d = self.factory.getUser(msg)
                d.addErrback(catchError)
                d.addCallback(lambda m: "Status of %s: %s" % (msg, m))
                d.addCallback(lambda m: self.msg(user, m))

    class IIRCClientFactory(Interface):

        """
        @ivar nickname
        """

        def getUser(self, user):
            """Return a deferred returning a string"""

        def buildProtocol(self, addr):
            """Return a protocol"""

    class IRCClientFactoryFromService(protocol.ClientFactory):

        implements(IIRCClientFactory)

        protocol = IRCReplyBot
        nickname = None

        def __init__(self, service):
            self.service = service

        def getUser(self, user):
            return self.service.getUser(user)

    components.registerAdapter(IRCClientFactoryFromService,
                               IFingerService,
                               IIRCClientFactory)

    class UserStatusTree(resource.Resource):

        def __init__(self, service):
            resource.Resource.__init__(self)
            self.service=service

            # add a specific child for the path "RPC2"
            self.putChild("RPC2", UserStatusXR(self.service))

            # need to do this for resources at the root of the site
            self.putChild("", self)

        def _cb_render_GET(self, users, request):
            userOutput = ''.join(["<li><a href=\"%s\">%s</a></li>" % (user, user)
                    for user in users])
            request.write("""
                <html><head><title>Users</title></head><body>
                <h1>Users</h1>
                <ul>
                %s
                </ul></body></html>""" % userOutput)
            request.finish()

        def render_GET(self, request):
            d = self.service.getUsers()
            d.addCallback(self._cb_render_GET, request)

            # signal that the rendering is not complete
            return server.NOT_DONE_YET

        def getChild(self, path, request):
            return UserStatus(user=path, service=self.service)

    components.registerAdapter(UserStatusTree, IFingerService, resource.IResource)

    class UserStatus(resource.Resource):

        def __init__(self, user, service):
            resource.Resource.__init__(self)
            self.user = user
            self.service = service

        def _cb_render_GET(self, status, request):
            request.write("""<html><head><title>%s</title></head>
            <body><h1>%s</h1>
            <p>%s</p>
            </body></html>""" % (self.user, self.user, status))
            request.finish()

        def render_GET(self, request):
            d = self.service.getUser(self.user)
            d.addCallback(self._cb_render_GET, request)

            # signal that the rendering is not complete
            return server.NOT_DONE_YET

    class UserStatusXR(xmlrpc.XMLRPC):

        def __init__(self, service):
            xmlrpc.XMLRPC.__init__(self)
            self.service = service

        def xmlrpc_getUser(self, user):
            return self.service.getUser(user)

        def xmlrpc_getUsers(self):
            return self.service.getUsers()

    class IPerspectiveFinger(Interface):

        def remote_getUser(self, username):
            """return a user's status"""

        def remote_getUsers(self):
            """return a user's status"""

    class PerspectiveFingerFromService(pb.Root):

        implements(IPerspectiveFinger)

        def __init__(self, service):
            self.service = service

        def remote_getUser(self, username):
            return self.service.getUser(username)

        def remote_getUsers(self):
            return self.service.getUsers()

    components.registerAdapter(PerspectiveFingerFromService,
                               IFingerService,
                               IPerspectiveFinger)

    class FingerService(service.Service):

        implements(IFingerService)

        def __init__(self, filename):
            self.filename = filename
            self._read()

        def _read(self):
            self.users = {}
            for line in file(self.filename):
                user, status = line.split(':', 1)
                user = user.strip()
                status = status.strip()
                self.users[user] = status
            self.call = reactor.callLater(30, self._read)

        def getUser(self, user):
            return defer.succeed(self.users.get(user, "No such user"))

        def getUsers(self):
            return defer.succeed(self.users.keys())

    class ServerContextFactory:

        def getContext(self):
            """Create an SSL context.

            This is a sample implementation that loads a certificate from a file
            called 'server.pem'."""
            ctx = SSL.Context(SSL.SSLv23_METHOD)
            ctx.use_certificate_file('server.pem')
            ctx.use_privatekey_file('server.pem')
            return ctx

    application = service.Application('finger', uid=1, gid=1)
    f = FingerService('/etc/users')
    serviceCollection = service.IServiceCollection(application)
    internet.TCPServer(79, IFingerFactory(f)
                       ).setServiceParent(serviceCollection)
    site = server.Site(resource.IResource(f))
    internet.TCPServer(8000, site
                       ).setServiceParent(serviceCollection)
    internet.SSLServer(443, site, ServerContextFactory()
                       ).setServiceParent(serviceCollection)
    i = IIRCClientFactory(f)
    i.nickname = 'fingerbot'
    internet.TCPClient('irc.freenode.org', 6667, i
                       ).setServiceParent(serviceCollection)
    internet.TCPServer(8889, pb.PBServerFactory(IPerspectiveFinger(f))
                       ).setServiceParent(serviceCollection)

Source listing - listings/finger/finger22.py

Index

Version: 2.1.0