mirror of
https://github.com/chillout2k/sos-milter.git
synced 2025-12-12 18:10:18 +00:00
219 lines
7.7 KiB
Python
219 lines
7.7 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 dns.resolver
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from timeit import default_timer as timer
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import pprint
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# Globals with mostly senseless defaults ;)
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g_milter_name = 'sos-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*@(\S+)$', re.IGNORECASE)
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g_re_spf_regex = re.compile(r'.*', re.IGNORECASE)
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g_re_expected_txt_data = ''
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g_loglevel = logging.INFO
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g_milter_mode = 'test'
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class SOSMilter(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.time_start = timer()
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self.null_sender = False
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self.env_from = None
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self.env_from_domain = None
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self.spf_record = None
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self.add_header = False
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self.queue_id = None
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self.next_hop = None
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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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# 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 header(self, name, hval):
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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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try:
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# DSNs/bounces are not relevant
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if(mailfrom == '<>'):
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self.null_sender = True
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return Milter.CONTINUE
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mailfrom = mailfrom.replace("<","")
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mailfrom = mailfrom.replace(">","")
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self.env_from = mailfrom
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m = g_re_domain.match(self.env_from)
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if m is None:
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logging.error(self.mconn_id + "/FROM " +
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"Could not determine domain of 5321.from=" + self.env_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.env_from_domain = m.group(1)
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logging.debug(self.mconn_id +
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"/FROM 5321.from-domain=" + self.env_from_domain
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)
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# Get TXT record of sender domain
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dns_response = None
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try:
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dns_response = dns.resolver.query(self.env_from_domain, 'TXT')
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except dns.resolver.NoAnswer as e:
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logging.error(self.mconn_id +
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" /FROM " + e.msg
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)
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# accept message if DNS-resolver fails
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return Milter.CONTINUE
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except dns.resolver.NXDOMAIN as e:
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logging.error(self.mconn_id +
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" /FROM " + e.msg
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)
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# accept message if DNS-resolver fails
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return Milter.CONTINUE
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except:
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logging.error(self.mconn_id + " DNS-Resolver-EXCEPTION: " + traceback.format_exc())
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# accept message if DNS-resolver fails
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return Milter.CONTINUE
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for rdata in dns_response:
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if re.match(r'^"v=spf1.*"$', rdata.to_text(), re.IGNORECASE):
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# we´ve got a SPF match!
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self.spf_record = rdata.to_text()
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break
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return Milter.CONTINUE
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except:
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logging.error(self.mconn_id + " FROM-EXCEPTION: " + traceback.format_exc())
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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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def envrcpt(self, to, *str):
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if self.null_sender == True:
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return Milter.CONTINUE
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try:
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self.next_hop = self.getsymval('{rcpt_host}')
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except:
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logging.error(self.mconn_id + "RCPT exception: " + traceback.format_exc())
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sys.exit(1)
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return Milter.CONTINUE
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def data(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.null_sender:
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logging.info(self.mconn_id + '/' + self.queue_id + "/DATA Skipping bounce/DSN message")
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return Milter.CONTINUE
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if self.spf_record is not None:
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logging.info(self.mconn_id + '/' + self.queue_id + "/DATA " +
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"SPFv1: " + self.spf_record
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)
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logging.info(self.mconn_id + '/' + self.queue_id + "/DATA next-hop=" + self.next_hop)
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if re.match(r'^".+-all"$', self.spf_record, re.IGNORECASE) is not None:
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# SPF record is in restrictive mode
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if g_re_spf_regex.match(self.spf_record) is not None:
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logging.debug(self.mconn_id + '/' + self.queue_id + "/DATA" +
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" SPF-record of 5321.from-domain=" + self.env_from_domain +
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" permits us to relay this message"
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)
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else:
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ex = "Restrictive SPF-record (-all) of 5321.from-domain=" + self.env_from_domain + " does not permit us to relay this message!"
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# Expected 'include' not found in SPF-record
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logging.debug(self.mconn_id + '/' + self.queue_id + "/DATA " + ex)
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if g_milter_mode == 'test':
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logging.debug(self.mconn_id + '/' + self.queue_id + "/DATA " +
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'test-mode: X-SOS-Milter header will be added'
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)
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self.add_header = True
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else:
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logging.error(self.mconn_id + '/' + self.queue_id + "/DATA " + ex)
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self.setreply('550','5.7.1',
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self.mconn_id + ' ' + ex + ' ' + g_milter_reject_message
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)
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return Milter.REJECT
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return Milter.CONTINUE
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def eom(self):
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# EOM is not optional and thus, always called by MTA
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if self.add_header == True:
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self.addheader(
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'X-SOS-Milter',
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self.mconn_id + ' ' + self.env_from_domain + ': failed SPF-expectation'
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)
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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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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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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_MODE' in os.environ:
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if re.match(r'^test|reject$',os.environ['MILTER_MODE'], re.IGNORECASE):
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g_milter_mode = os.environ['MILTER_MODE']
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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 'SPF_REGEX' in os.environ:
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try:
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g_re_spf_regex = re.compile(os.environ['SPF_REGEX'], re.IGNORECASE)
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except:
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logging.error("ENV[SPF_REGEX] exception: " + traceback.format_exc())
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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 = SOSMilter
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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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" in mode: " + g_milter_mode
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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())
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