mirror of
https://github.com/chillout2k/ExOTA-Milter.git
synced 2025-12-12 18:00:19 +00:00
281 lines
11 KiB
Python
281 lines
11 KiB
Python
import Milter
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import sys
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import traceback
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import os
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import logging
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import string
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import random
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import re
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import email.utils
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import authres
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import json
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# Globals with mostly senseless defaults ;)
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g_milter_name = 'exota-milter'
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g_milter_socket = '/socket/' + g_milter_name
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g_milter_reject_message = 'Security policy violation!'
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g_milter_tmpfail_message = 'Service temporarily not available! Please try again later.'
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g_re_domain = re.compile(r'^.*@(\S+)$', re.IGNORECASE)
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g_loglevel = logging.INFO
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g_milter_dkim_enabled = False
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g_milter_dkim_authservid = 'invalid'
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g_milter_policy_source = 'file' # file, ldap, etc.
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g_milter_policy_file = 'invalid'
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g_milter_policy = {}
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class ExOTAMilter(Milter.Base):
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# Each new connection is handled in an own thread
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def __init__(self):
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self.reset()
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def reset(self):
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self.client_ip = None
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self.queue_id = None
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self.hdr_from = None
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self.hdr_from_domain = None
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self.hdr_tenant_id = None
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self.tenant_id_valid = False
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self.dkim_results = []
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self.dkim_valid = False
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# https://stackoverflow.com/a/2257449
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self.mconn_id = g_milter_name + ': ' + ''.join(
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random.choice(string.ascii_lowercase + string.digits) for _ in range(8)
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)
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logging.debug(self.mconn_id + " RESET")
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# Not registered/used callbacks
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@Milter.nocallback
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def connect(self, IPname, family, hostaddr):
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return Milter.CONTINUE
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@Milter.nocallback
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def hello(self, heloname):
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return Milter.CONTINUE
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@Milter.nocallback
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def eoh(self):
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return Milter.CONTINUE
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@Milter.nocallback
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def body(self, chunk):
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return Milter.CONTINUE
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def envfrom(self, mailfrom, *str):
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# Instance member values remain within reused SMTP-connections!
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if self.client_ip is not None:
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# Milter connection reused!
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logging.debug(self.mconn_id + "/FROM connection reused!")
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self.reset()
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self.client_ip = self.getsymval('{client_addr}')
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if self.client_ip is None:
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logging.error(self.mconn_id + " FROM exception: could not retrieve milter-macro ({client_addr})!")
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self.setreply('550','5.7.1', g_milter_tmpfail_message)
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return Milter.REJECT
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else:
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logging.debug(self.mconn_id + "/FROM client_ip={0}".format(self.client_ip))
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return Milter.CONTINUE
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def envrcpt(self, to, *str):
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logging.debug(self.mconn_id + "/RCPT 5321.rcpt={0}".format(to))
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return Milter.CONTINUE
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def header(self, name, hval):
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logging.debug(self.mconn_id + "/" + str(self.queue_id) +
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"/HEADER Header: {0}, Value: {1}".format(name, hval)
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)
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if(name == "From"):
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hdr_5322_from = email.utils.parseaddr(hval)
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self.hdr_from = hdr_5322_from[1].lower()
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m = re.match(g_re_domain, self.hdr_from)
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if m is None:
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logging.error(self.mconn_id + "/" + str(self.queue_id) + "/HEADER " +
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"Could not determine domain-part of 5322.from=" + self.hdr_from
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)
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self.setreply('450','4.7.1', g_milter_tmpfail_message)
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return Milter.TEMPFAIL
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self.hdr_from_domain = m.group(1)
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logging.debug(self.mconn_id + "/" + str(self.queue_id) +
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"/HEADER 5322.from: {0}, 5322.from_domain: {1}".format(self.hdr_from, self.hdr_from_domain)
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)
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elif(name == "X-MS-Exchange-CrossTenant-Id"):
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self.hdr_tenant_id = hval.lower()
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logging.debug(self.mconn_id + "/" + str(self.queue_id) +
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"/HEADER Tenant-ID: {0}".format(self.hdr_tenant_id)
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)
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elif(name == "Authentication-Results"):
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if g_milter_dkim_enabled == True:
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ar = None
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try:
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ar = authres.AuthenticationResultsHeader.parse(
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"{0}: {1}".format(name, hval)
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)
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if ar.authserv_id == g_milter_dkim_authservid:
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for ar_result in ar.results:
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if ar_result.method == 'dkim':
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self.dkim_results.append({
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"selector": str(ar_result.header_s),
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"from_domain": str(ar_result.header_d),
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"result": str(ar_result.result)
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})
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else:
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logging.debug(self.mconn_id + "/" + str(self.queue_id) +
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"/HEADER Ignoring authentication results of {0}".format(ar.authserv_id)
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)
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except:
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logging.error(self.mconn_id + "/" + str(self.queue_id) +
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"/HEADER AR-parse exception: " + traceback.format_exc()
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)
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return Milter.CONTINUE
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# EOM is not optional and thus always called by MTA
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def eom(self):
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# A queue-id will be generated after the first accepted RCPT TO
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# and therefore not available until DATA command
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self.queue_id = self.getsymval('i')
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if self.queue_id is None:
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logging.error(self.mconn_id + "EOM exception: could not retrieve milter-macro (i)!")
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self.setreply('450','4.7.1', g_milter_tmpfail_message)
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return Milter.TEMPFAIL
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else:
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logging.debug(self.mconn_id + "/EOM Queue-ID: {0}".format(self.queue_id))
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if self.hdr_from is None:
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logging.error(self.mconn_id + "/" + self.queue_id +
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"/EOM exception: could not determine 5322.from header!"
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)
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self.setreply('550','5.7.1', g_milter_tmpfail_message)
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return Milter.REJECT
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if self.hdr_from_domain not in g_milter_policy:
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logging.error(self.mconn_id + "/" + str(self.queue_id) + "/EOM " +
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"Could not find 5322.from_domain {0} in policy!".format(self.hdr_from_domain)
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)
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self.setreply('550','5.7.1', g_milter_reject_message)
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return Milter.REJECT
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if self.hdr_tenant_id is None:
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logging.error(self.mconn_id + "/" + self.queue_id +
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"/EOM exception: could not determine X-MS-Exchange-CrossTenant-Id"
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)
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self.setreply('550','5.7.1', g_milter_reject_message)
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return Milter.REJECT
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if self.hdr_tenant_id == g_milter_policy[self.hdr_from_domain]['tenant_id'].lower():
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logging.info(self.mconn_id + "/" + self.queue_id +
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"/EOM: 5322.from_domain={1} tenant_id={0} status=match".format(self.hdr_tenant_id, self.hdr_from_domain)
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)
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else:
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logging.error(self.mconn_id + "/" + self.queue_id +
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"/EOM: 5322.from_domain={1} tenant_id={0} status=no_match".format(self.hdr_tenant_id, self.hdr_from_domain)
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)
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self.setreply('550','5.7.1', g_milter_reject_message)
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return Milter.REJECT
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if g_milter_dkim_enabled == True and g_milter_policy[self.hdr_from_domain]['dkim'] == True:
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logging.info(self.mconn_id + "/" + self.queue_id +
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"/EOM: 5322.from_domain={0} dkim_auth=enabled".format(self.hdr_from_domain)
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)
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if len(self.dkim_results) > 0:
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for dkim_result in self.dkim_results:
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if dkim_result['from_domain'] == self.hdr_from_domain:
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logging.debug(self.mconn_id + "/" + self.queue_id +
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"/EOM: Found DKIM authentication result for {0}/{1}".format(
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self.hdr_from_domain, dkim_result['selector']
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)
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)
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if dkim_result['result'] == 'pass':
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logging.info(self.mconn_id + "/" + self.queue_id +
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"/EOM: 5322.from_domain={0} selector={1} result=pass".format(
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self.hdr_from_domain, dkim_result['selector']
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)
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)
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self.dkim_valid = True
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continue
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else:
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logging.info(self.mconn_id + "/" + self.queue_id +
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"/EOM: 5322.from_domain={0} selector={1} result=fail".format(
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self.hdr_from_domain, dkim_result['selector']
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)
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)
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else:
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logging.info(self.mconn_id + "/" + self.queue_id +
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"/EOM: No DKIM authentication results (AR headers) found!"
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)
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self.setreply('550','5.7.1', g_milter_reject_message)
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return Milter.REJECT
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if self.dkim_valid == False:
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logging.info(self.mconn_id + "/" + self.queue_id +
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"/EOM: DKIM authentication failed!"
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)
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self.setreply('550','5.7.1', g_milter_reject_message)
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return Milter.REJECT
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return Milter.CONTINUE
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def abort(self):
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# Client disconnected prematurely
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logging.debug(self.mconn_id + "/ABORT")
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return Milter.CONTINUE
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def close(self):
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# Always called, even when abort is called.
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# Clean up any external resources here.
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logging.debug(self.mconn_id + "/CLOSE")
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return Milter.CONTINUE
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if __name__ == "__main__":
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if 'LOG_LEVEL' in os.environ:
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if re.match(r'^info$', os.environ['LOG_LEVEL'], re.IGNORECASE):
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g_loglevel = logging.INFO
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elif re.match(r'^warn|warning$', os.environ['LOG_LEVEL'], re.IGNORECASE):
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g_loglevel = logging.WARN
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elif re.match(r'^error$', os.environ['LOG_LEVEL'], re.IGNORECASE):
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g_loglevel = logging.ERROR
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elif re.match(r'debug', os.environ['LOG_LEVEL'], re.IGNORECASE):
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g_loglevel = logging.DEBUG
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logging.basicConfig(
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filename=None, # log to stdout
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format='%(asctime)s: %(levelname)s %(message)s',
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level=g_loglevel
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)
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if 'MILTER_NAME' in os.environ:
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g_milter_name = os.environ['MILTER_NAME']
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if 'MILTER_SOCKET' in os.environ:
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g_milter_socket = os.environ['MILTER_SOCKET']
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if 'MILTER_REJECT_MESSAGE' in os.environ:
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g_milter_reject_message = os.environ['MILTER_REJECT_MESSAGE']
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if 'MILTER_TMPFAIL_MESSAGE' in os.environ:
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g_milter_tmpfail_message = os.environ['MILTER_TMPFAIL_MESSAGE']
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if 'MILTER_DKIM_ENABLED' in os.environ:
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g_milter_dkim_enabled = True
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logging.info("DKIM signature authorisation enabled")
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if 'MILTER_DKIM_AUTHSERVID' in os.environ:
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g_milter_dkim_authservid = os.environ['MILTER_DKIM_AUTHSERVID'].lower()
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logging.info("DKIM AuthServID: " + g_milter_dkim_authservid)
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else:
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logging.error("ENV[MILTER_DKIM_AUTHSERVID] is mandatory!")
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sys.exit(1)
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if 'MILTER_POLICY_SOURCE' in os.environ:
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g_milter_policy_source = os.environ['MILTER_POLICY_SOURCE']
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if g_milter_policy_source == 'file':
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if 'MILTER_POLICY_FILE' in os.environ:
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g_milter_policy_file = os.environ['MILTER_POLICY_FILE']
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try:
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with open(g_milter_policy_file, 'r') as policy_file:
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g_milter_policy = json.load(policy_file)
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policy_file.close()
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logging.info("Successfully slurped policy file: {0}".format(g_milter_policy_file))
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except:
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logging.error("Error reading policy file: " + traceback.format_exc())
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sys.exit(1)
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else:
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logging.error("ENV[MILTER_POLICY_FILE] is mandatory!")
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sys.exit(1)
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try:
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timeout = 600
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# Register to have the Milter factory create instances of your class:
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Milter.factory = ExOTAMilter
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# Tell the MTA which features we use
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flags = Milter.ADDHDRS
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Milter.set_flags(flags)
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logging.info("Startup " + g_milter_name +
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"@socket: " + g_milter_socket
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)
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Milter.runmilter(g_milter_name,g_milter_socket,timeout,True)
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logging.info("Shutdown " + g_milter_name)
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except:
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logging.error("MAIN-EXCEPTION: " + traceback.format_exc()) |