313 lines
9.9 KiB
Python
313 lines
9.9 KiB
Python
# PyMod-Milter is free software: you can redistribute it and/or modify
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# it under the terms of the GNU General Public License as published by
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# the Free Software Foundation, either version 3 of the License, or
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# (at your option) any later version.
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#
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# PyMod-Milter is distributed in the hope that it will be useful,
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# but WITHOUT ANY WARRANTY; without even the implied warranty of
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# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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# GNU General Public License for more details.
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#
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# You should have received a copy of the GNU General Public License
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# along with PyMod-Milter. If not, see <http://www.gnu.org/licenses/>.
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#
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__all__ = [
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"make_header",
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"actions",
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"conditions",
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"run",
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"version",
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"CustomLogger",
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"Rule",
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"ModifyMilter"]
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import Milter
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import logging
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from Milter.utils import parse_addr
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from email.charset import Charset
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from email.header import Header, decode_header
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from io import BytesIO
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from pymodmilter.conditions import Conditions
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def make_header(decoded_seq, maxlinelen=None, header_name=None,
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continuation_ws=' ', errors='strict'):
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"""Create a Header from a sequence of pairs as returned by decode_header()
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decode_header() takes a header value string and returns a sequence of
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pairs of the format (decoded_string, charset) where charset is the string
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name of the character set.
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This function takes one of those sequence of pairs and returns a Header
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instance. Optional maxlinelen, header_name, and continuation_ws are as in
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the Header constructor.
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"""
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h = Header(maxlinelen=maxlinelen, header_name=header_name,
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continuation_ws=continuation_ws)
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for s, charset in decoded_seq:
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# None means us-ascii but we can simply pass it on to h.append()
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if charset is not None and not isinstance(charset, Charset):
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charset = Charset(charset)
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h.append(s, charset, errors=errors)
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return h
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class CustomLogger(logging.LoggerAdapter):
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def process(self, msg, kwargs):
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if "name" in self.extra:
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msg = "{}: {}".format(self.extra["name"], msg)
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if "qid" in self.extra:
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msg = "{}: {}".format(self.extra["qid"], msg)
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if self.logger.getEffectiveLevel() != logging.DEBUG:
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msg = msg.replace("\n", "").replace("\r", "")
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return msg, kwargs
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class Rule:
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"""
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Rule to implement multiple actions on emails.
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"""
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def __init__(self, name, local_addrs, conditions, actions, pretend=False,
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loglevel=logging.INFO):
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logger = logging.getLogger(name)
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self.logger = CustomLogger(logger, {"name": name})
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self.logger.setLevel(loglevel)
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if logger is None:
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logger = logging.getLogger(__name__)
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self.logger = CustomLogger(logger, {"name": name})
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self.conditions = Conditions(
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local_addrs=local_addrs,
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args=conditions,
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logger=self.logger)
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self.actions = actions
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self.pretend = pretend
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self._needs = []
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for action in actions:
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for need in action.needs():
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if need not in self._needs:
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self._needs.append(need)
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self.logger.debug("needs: {}".format(", ".join(self._needs)))
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def needs(self):
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"""Return the needs of this rule."""
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return self._needs
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def ignores(self, host=None, envfrom=None, envto=None):
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args = {}
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if host is not None:
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args["host"] = host
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if envfrom is not None:
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args["envfrom"] = envfrom
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if envto is not None:
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args["envto"] = envto
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if self.conditions.match(args):
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for action in self.actions:
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if action.conditions.match(args):
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return False
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return True
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def execute(self, milter, pretend=None):
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"""Execute all actions of this rule."""
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if pretend is None:
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pretend = self.pretend
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for action in self.actions:
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milter_action = action.execute(milter)
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if milter_action is not None:
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return milter_action
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class ModifyMilter(Milter.Base):
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"""ModifyMilter based on Milter.Base to implement milter communication"""
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_rules = []
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_loglevel = logging.INFO
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@staticmethod
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def set_rules(rules):
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ModifyMilter._rules = rules
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def set_loglevel(level):
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ModifyMilter._loglevel = level
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def __init__(self):
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self.logger = logging.getLogger(__name__)
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self.logger.setLevel(ModifyMilter._loglevel)
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# save rules, it must not change during runtime
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self.rules = ModifyMilter._rules.copy()
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def connect(self, IPname, family, hostaddr):
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try:
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if hostaddr is None:
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self.logger.error("unable to proceed, host address is None")
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return Milter.TEMPFAIL
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self.logger.debug(
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f"accepted milter connection from {hostaddr[0]} "
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f"port {hostaddr[1]}")
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# remove rules which ignore this host
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for rule in self.rules.copy():
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if rule.ignores(host=hostaddr[0]):
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self.rules.remove(rule)
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if not self.rules:
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self.logger.debug(
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f"host {hostaddr[0]} is ignored by all rules, "
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f"skip further processing")
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return Milter.ACCEPT
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except Exception as e:
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self.logger.exception(
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f"an exception occured in connect function: {e}")
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return Milter.TEMPFAIL
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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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mailfrom = "@".join(parse_addr(mailfrom)).lower()
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for rule in self.rules.copy():
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if rule.ignores(envfrom=mailfrom):
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self.rules.remove(rule)
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if not self.rules:
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self.logger.debug(
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f"envelope-from address {mailfrom} is ignored by "
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f"all rules, skip further processing")
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return Milter.ACCEPT
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self.recipients = set()
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except Exception as e:
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self.logger.exception(
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f"an exception occured in envfrom function: {e}")
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return Milter.TEMPFAIL
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return Milter.CONTINUE
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@Milter.noreply
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def envrcpt(self, to, *str):
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try:
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self.recipients.add("@".join(parse_addr(to)).lower())
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except Exception as e:
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self.logger.exception(
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f"an exception occured in envrcpt function: {e}")
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return Milter.TEMPFAIL
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return Milter.CONTINUE
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def data(self):
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try:
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for rule in self.rules.copy():
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if rule.ignores(envto=[*self.recipients]):
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self.rules.remove(rule)
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if not self.rules:
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self.logger.debug(
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f"envelope-to addresses are ignored by all rules, "
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f"skip further processing")
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return Milter.ACCEPT
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self.qid = self.getsymval('i')
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self.logger = CustomLogger(self.logger, {"qid": self.qid})
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self.logger.debug("received queue-id from MTA")
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self.fields = None
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self.fields_data = None
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self.body_data = None
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needs = []
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for rule in self.rules:
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needs += rule.needs()
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if "fields" in needs:
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self.fields = []
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if "original_fields" in needs:
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self.fields_data = BytesIO()
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if "body" in needs:
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self.body_data = BytesIO()
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except Exception as e:
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self.logger.exception(
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f"an exception occured in data function: {e}")
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return Milter.TEMPFAIL
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return Milter.CONTINUE
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def header(self, name, value):
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try:
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if self.fields_data != None:
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self.fields_data.write(
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name.encode("ascii", errors="surrogateescape"))
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self.fields_data.write(b": ")
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self.fields_data.write(
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value.encode("ascii", errors="surrogateescape"))
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self.fields_data.write(b"\r\n")
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if self.fields is not None:
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# remove surrogates from value
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value = value.encode(
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errors="surrogateescape").decode(errors="replace")
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self.logger.debug(f"received header: {name}: {value}")
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header = make_header(decode_header(value), errors="replace")
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value = str(header).replace("\x00", "")
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self.logger.debug(f"decoded header: {name}: {value}")
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self.fields.append((name, value))
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except Exception as e:
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self.logger.exception(
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f"an exception occured in header function: {e}")
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return Milter.TEMPFAIL
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return Milter.CONTINUE
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def body(self, chunk):
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try:
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if self.body_data is not None:
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self.body_data.write(chunk)
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except Exception as e:
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self.logger.exception(
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f"an exception occured in body function: {e}")
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return Milter.TEMPFAIL
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return Milter.CONTINUE
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def eom(self):
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try:
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for rule in self.rules:
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milter_action = rule.execute(self)
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if milter_action is not None:
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if milter_action["action"] == "reject":
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self.setreply("554", "5.7.0", milter_action["reason"])
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return Milter.REJECT
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if milter_action["action"] == "accept":
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return Milter.ACCEPT
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if milter_action["action"] == "discard":
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return Milter.DISCARD
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except Exception as e:
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self.logger.exception(
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f"an exception occured in eom function: {e}")
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return Milter.TEMPFAIL
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return Milter.ACCEPT
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