# Copyright (c) 2009-2014 Evgeni Golov <evgeni@golov.de>
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from twisted.protocols.basic import LineOnlyReceiver
from twisted.internet.protocol import Factory
from twisted.internet.interfaces import IHalfCloseableProtocol
from zope.interface import implements
import ipaddr


class PostfixPolicy(LineOnlyReceiver):
    '''Basic implementation of a Postfix policy service.'''

    implements(IHalfCloseableProtocol)

    required_params = []

    def __init__(self):
        self.params = {}
        self.delimiter = '\n'

    def lineReceived(self, line):
        '''Parse stuff from Postfix and call check_policy() afterwards.'''
        line = line.strip().lower()
        if line == '':
            if len(self.params) > 0:
                valid_request = True
                for p in self.required_params:
                    if p not in self.params:
                        valid_request = False
                        break
                if valid_request:
                    self.check_policy()
                else:
                    self.send_action('DUNNO')
            self.params = {}
        else:
            try:
                (pkey, pval) = line.split('=', 1)
                try:
                    pval = pval.decode('utf-8', 'ignore')
                    pval = pval.encode('us-ascii', 'ignore')
                except:
                    pass
                if pkey == 'client_address':
                    pval = ipaddr.IPAddress(pval).exploded
                self.params[pkey] = pval
            except:
                print 'Could not parse "%s"' % line

    def check_policy(self):
        '''Check the incoming mail based on our policy and tell Postfix
        about our decision.

        You probably want to override this one with a function that does
        something useful.
        '''
        self.send_action('DUNNO')

    def send_action(self, action='DUNNO'):
        '''Send action back to Postfix.

        @type action: string
        @param action: the action to be sent to Postfix (default: 'DUNNO')
        '''
        self.sendLine('action=%s\n' % action)
        if self.factory.exim_workaround:
            self.transport.loseConnection()

    def readConnectionLost(self):
        pass

    def writeConnectionLost(self):
        self.transport.loseConnection()


class PostfixPolicyFactory(Factory):
    protocol = PostfixPolicy
    exim_workaround = False