# The Evolution of Finger: configuration and packaging of the finger service

## Introduction

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

In this part, we make it easier for non-programmers to configure a finger server, and show how to package it in the .deb and RPM package formats.

## Plugins

So far, the user had to be somewhat of a programmer to be able to configure stuff. Maybe we can eliminate even that? Move old code to finger/__init__.py and...

Full source code for finger module here:

    # finger.py module

    from twisted.application import internet, service, strports
    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.web.woven import page, model, interfaces
    from twisted.spread import pb
    from OpenSSL import SSL
    import cgi

    class IFingerService(components.Interface):

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

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

    class IFingerSetterService(components.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+'\n')
                self.transport.loseConnection()
            d.addCallback(writeValue)

    class IFingerFactory(components.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__ = 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(components.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__ = 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(components.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__ = 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 UsersModel(model.MethodModel):

        def initialize(self, *args, **kwargs):
            self.service=args[0]

        def wmfactory_users(self, request):
            return self.service.getUsers()

    components.registerAdapter(UsersModel, IFingerService, interfaces.IModel)

    class UserStatusTree(page.Page):

        template = """<html><head><title>Users</title></head><body>
        <h1>Users</h1>
        <ul model="users" view="List">
        <li pattern="listItem"><a view="Anchor" /></li>
        </ul></body></html>"""

        def initialize(self, *args, **kwargs):
            self.service=args[0]

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

        def wchild_RPC2 (self, request):
            return UserStatusXR(self.service)

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

    class UserStatus(page.Page):

        template='''<html><head><title view="Text" model="user"/></head>
        <body><h1 view="Text" model="user"/>
        <p model="status" view="Text" />
        </body></html>'''

        def initialize(self, **kwargs):
            self.user = kwargs['user']
            self.service = kwargs['service']

        def wmfactory_user(self, request):
            return self.user

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

    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(components.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__ = 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__ = 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

    # Easy configuration

    def makeService(config):
        # finger on port 79
        s = service.MultiService()
        f = FingerService(config['file'])
        h = internet.TCPServer(79, IFingerFactory(f))
        h.setServiceParent(s)

        # website on port 8000
        r = resource.IResource(f)
        r.templateDirectory = config['templates']
        site = server.Site(r)
        j = internet.TCPServer(8000, site)
        j.setServiceParent(s)

        # ssl on port 443
    #    if config.get('ssl'):
    #        k = internet.SSLServer(443, site, ServerContextFactory())
    #        k.setServiceParent(s)

        # irc fingerbot
        if config.has_key('ircnick'):
            i = IIRCClientFactory(f)
            i.nickname = config['ircnick']
            ircserver = config['ircserver']
            b = internet.TCPClient(ircserver, 6667, i)
            b.setServiceParent(s)

        # Pespective Broker on port 8889
        if config.has_key('pbport'):
            m = internet.TCPServer(
                int(config['pbport']),
                pb.PBServerFactory(IPerspectiveFinger(f)))
            m.setServiceParent(s)

        return s

finger module - listings/finger/finger/finger.py

    # finger/tap.py
    from twisted.application import internet, service
    from twisted.internet import interfaces
    from twisted.python import usage
    import finger

    class Options(usage.Options):

        optParameters = [
            ['file', 'f', '/etc/users'],
            ['templates', 't', '/usr/share/finger/templates'],
            ['ircnick', 'n', 'fingerbot'],
            ['ircserver', None, 'irc.freenode.net'],
            ['pbport', 'p', 8889],
            ]

        optFlags = [['ssl', 's']]

    def makeService(config):
        return finger.makeService(config)

finger/tap.py - listings/finger/finger/tap.py

And register it all:

    #finger/plugins.tml
    register('finger', 'finger.tap',
     description='Build a finger server tap',
     type='tap', tapname='finger')

finger/plugins.tml - listings/finger/finger/plugins.tml

And now, the following works

    % mktap finger --file=/etc/users --ircnick=fingerbot
    % sudo twistd -nf finger.tap

## OS Integration

If we already have the finger package installed in PYTHONPATH (e.g. we added it to site-packages), we can achieve easy integration:

### Debian

    % tap2deb --unsigned -m "Foo <foo@example.com>" --type=python finger.tac
    % sudo dpkg -i .build/*.deb

### Red Hat / Mandrake

    % tap2rpm --type=python finger.tac #[maybe other options needed]
    % sudo rpm -i .build/*.rpm

Will properly register the tap/tac, init.d scripts, etc. for the given file.

If it doesn't work on your favorite OS: patches accepted!

Index

Version: 1.3.0