# 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. More information on using SSL in Twisted can be found in the SSL howto .

## 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.internet.endpoints.serverFromString` method to build a SSL endpoint. Note that one factory (in this case, a site) can listen on multiple ports with multiple protocols.

Of course, this endpoint doesn’t work without a TLS certificate and a private key. You’ll need to create a self-signed cert and key. This will obviously not be trusted by your web browser, so you’ll see a warning when you connect. In this case, don’t worry: you’re not at risk.

To create a certificate and key that can be used by this tutorial, run the following:

    openssl req -x509 -newkey rsa:2048 -keyout key.pem -out cert.pem -days 365

`finger22.py`

    # Do everything properly, and componentize
    from zope.interface import Interface, implementer

    from OpenSSL import SSL

    from twisted.application import internet, service, strports
    from twisted.internet import defer, endpoints, protocol, reactor
    from twisted.protocols import basic
    from twisted.python import components
    from twisted.spread import pb
    from twisted.web import resource, server, static, xmlrpc
    from twisted.words.protocols import irc

    class IFingerService(Interface):
        def getUser(user):
            """
            Return a deferred returning L{bytes}.
            """

        def getUsers():
            """
            Return a deferred returning a L{list} of L{bytes}.
            """

    class IFingerSetterService(Interface):
        def setUser(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 + b"\r\n")
                self.transport.loseConnection()

            d.addCallback(writeValue)

    class IFingerFactory(Interface):
        def getUser(user):
            """
            Return a deferred returning a string.
            """

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

    @implementer(IFingerFactory)
    class FingerFactoryFromService(protocol.ServerFactory):
        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(user, status):
            """
            Return a deferred returning L{bytes}.
            """

        def buildProtocol(addr):
            """
            Return a protocol returning L{bytes}.
            """

    @implementer(IFingerSetterFactory)
    class FingerSetterFactoryFromService(protocol.ServerFactory):
        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.encode("ascii"))
                d.addErrback(catchError)
                d.addCallback(lambda m: f"Status of {msg}: {m}")
                d.addCallback(lambda m: self.msg(user, m))

    class IIRCClientFactory(Interface):

        """
        @ivar nickname
        """

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

        def buildProtocol(addr):
            """
            Return a protocol.
            """

    @implementer(IIRCClientFactory)
    class IRCClientFactoryFromService(protocol.ClientFactory):
        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(
                [f'<li><a href="{user}">{user}</a></li>' 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(username):
            """
            Return a user's status.
            """

        def remote_getUsers():
            """
            Return a user's status.
            """

    @implementer(IPerspectiveFinger)
    class PerspectiveFingerFromService(pb.Root):
        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
    )

    @implementer(IFingerService)
    class FingerService(service.Service):
        def __init__(self, filename):
            self.filename = filename
            self.users = {}

        def _read(self):
            self.users.clear()
            with open(self.filename, "rb") as f:
                for line in f:
                    user, status = line.split(b":", 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, b"No such user"))

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

        def startService(self):
            self._read()
            service.Service.startService(self)

        def stopService(self):
            service.Service.stopService(self)
            self.call.cancel()

    application = service.Application("finger", uid=1, gid=1)
    f = FingerService("/etc/users")
    serviceCollection = service.IServiceCollection(application)
    f.setServiceParent(serviceCollection)
    strports.service("tcp:79", IFingerFactory(f)).setServiceParent(serviceCollection)
    site = server.Site(resource.IResource(f))
    strports.service(
        "tcp:8000",
        site,
    ).setServiceParent(serviceCollection)
    strports.service(
        "ssl:port=443:certKey=cert.pem:privateKey=key.pem", site
    ).setServiceParent(serviceCollection)
    i = IIRCClientFactory(f)
    i.nickname = "fingerbot"
    internet.ClientService(
        endpoints.clientFromString(reactor, "tcp:irc.freenode.org:6667"), i
    ).setServiceParent(serviceCollection)
    strports.service(
        "tcp:8889", pb.PBServerFactory(IPerspectiveFinger(f))
    ).setServiceParent(serviceCollection)