The Evolution of Finger: configuration 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. Plugins are discussed further in the Twisted Plugin System howto. Writing twistd plugins is covered in Writing a twistd Plugin, and .tac applications are covered in Using the Twisted Application Framework.

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

# finger.py module

from zope.interface import Interface, implements

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

from OpenSSL import SSL

class IFingerService(Interface):

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

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


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+'\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.
        """


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(user, status):
        """
        Return a deferred returning a string.
        """

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

    def buildProtocol(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):

    template = """<html><head><title>Users</title></head><body>
    <h1>Users</h1>
    <ul>
    %(users)s
    </ul>
    </body>
    </html>"""

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

    def getChild(self, path, request):
        if path == '':
            return self
        elif path == 'RPC2':
            return UserStatusXR(self.service)
        else:
            return UserStatus(path, self.service)

    def render_GET(self, request):
        users = self.service.getUsers()
        def cbUsers(users):
            request.write(self.template % {'users': ''.join([
                    # Name should be quoted properly these uses.
                    '<li><a href="%s">%s</a></li>' % (name, name)
                    for name in users])})
            request.finish()
        users.addCallback(cbUsers)
        def ebUsers(err):
            log.err(err, "UserStatusTree failed")
            request.finish()
        users.addErrback(ebUsers)
        return server.NOT_DONE_YET

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


class UserStatus(resource.Resource):

    template='''<html><head><title>%(title)s</title></head>
    <body><h1>%(name)s</h1><p>%(status)s</p></body></html>'''

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

    def render_GET(self, request):
        status = self.service.getUser(self.user)
        def cbStatus(status):
            request.write(self.template % {
                'title': self.user,
                'name': self.user,
                'status': status})
            request.finish()
        status.addCallback(cbStatus)
        def ebStatus(err):
            log.err(err, "UserStatus failed")
            request.finish()
        status.addErrback(ebStatus)
        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.
        """


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

    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())

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

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


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(1079, 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 'ircnick' in config:
        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 'pbport' in config:
        m = internet.TCPServer(
            int(config['pbport']),
            pb.PBServerFactory(IPerspectiveFinger(f)))
        m.setServiceParent(s)

    return s

tap.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)

And register it all:

finger_tutorial.py


from twisted.application.service import ServiceMaker

finger = ServiceMaker(
    'finger', 'finger.tap', 'Run a finger service', 'finger')

Note that the second argument to ServiceMaker ,``finger.tap`` , is a reference to a module (finger/tap.py ), not to a filename.

And now, the following works

% sudo twistd -n finger --file=/etc/users --ircnick=fingerbot

For more details about this, see the twistd plugin documentation .

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