338 lines
14 KiB
Python
338 lines
14 KiB
Python
# PyHeader-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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# PyHeader-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 PyHeader-Milter. If not, see <http://www.gnu.org/licenses/>.
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#
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__all__ = ["HeaderRule", "HeaderMilter"]
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name = "pyheadermilter"
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import Milter
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import argparse
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import configparser
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import logging
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import logging.handlers
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import os
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import re
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import sys
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from Milter.utils import parse_addr
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from netaddr import IPAddress, IPNetwork, AddrFormatError
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class HeaderRule:
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def __init__(self, name, action, header, search=None, value=None, ignore_hosts=[], only_hosts=[], log=True):
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self.logger = logging.getLogger(__name__)
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self.name = name
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self._action = action
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if action == "add":
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self.header = header
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else:
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try:
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self.header = re.compile(header, re.MULTILINE + re.DOTALL + re.IGNORECASE)
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except re.error as e:
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raise RuntimeError("unable to parse option 'header' of rule '{}': {}".format(name, e))
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if action == "mod":
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try:
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self.search = re.compile(search, re.MULTILINE + re.DOTALL + re.IGNORECASE)
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except re.error as e:
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raise RuntimeError("unable to parse option 'search' of rule '{}': {}".format(name, e))
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else:
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self.search = search
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self.value = value
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self.ignore_hosts = []
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try:
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for ignore in ignore_hosts:
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self.ignore_hosts.append(IPNetwork(ignore))
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except AddrFormatError as e:
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raise RuntimeError("unable to parse option 'ignore_hosts' of rule '{}': {}".format(name, e))
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self.only_hosts = []
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try:
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for only in only_hosts:
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self.only_hosts.append(IPNetwork(only))
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except AddrFormatError as e:
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raise RuntimeError("unable to parse option 'only_hosts' of rule '{}': {}".format(name, e))
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self.log = log
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def get_action(self):
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return self._action
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def log_modification(self):
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return self.log
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def ignore_host(self, host):
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ip = IPAddress(host)
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ignore = False
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for ignored in self.ignore_hosts:
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if ip in ignored:
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ignore = True
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break
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if not ignore and self.only_hosts:
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ignore = True
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for only in self.only_hosts:
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if ip in only:
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ignore = False
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break
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if ignore:
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self.logger.debug("host {} is ignored by rule {}".format(host, self.name))
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return ignore
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def execute(self, headers):
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modified = []
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if self._action == "add":
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modified.append((self.header, self.value, 0, 1))
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else:
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index = 0
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occurrences = {}
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for name, value in headers:
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if name not in occurrences.keys():
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occurrences[name] = 1
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else:
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occurrences[name] += 1
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if self.header.search("{}: {}".format(name, value)):
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if self._action == "del":
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value = ""
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else:
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value = self.search.sub(self.value, value)
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modified.append((name, value, index, occurrences[name]))
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index += 1
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return modified
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class HeaderMilter(Milter.Base):
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"""HeaderMilter based on Milter.Base to implement milter communication"""
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_rules = []
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@staticmethod
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def set_rules(rules):
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HeaderMilter._rules = rules
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def __init__(self):
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self.logger = logging.getLogger(__name__)
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# save rules, it must not change during runtime
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self.rules = HeaderMilter._rules.copy()
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def connect(self, IPname, family, hostaddr):
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self.logger.debug("accepted milter connection from {} port {}".format(*hostaddr))
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ip = IPAddress(hostaddr[0])
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for rule in self.rules.copy():
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if rule.ignore_host(ip):
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self.rules.remove(rule)
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if not self.rules:
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self.logger.debug("host {} is ignored by all rules, skip further processing".format(hostaddr[0]))
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return Milter.ACCEPT
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return Milter.CONTINUE
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@Milter.noreply
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def data(self):
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self.queueid = self.getsymval('i')
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self.logger.debug("{}: received queue-id from MTA".format(self.queueid))
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self.headers = []
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return Milter.CONTINUE
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@Milter.noreply
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def header(self, name, value):
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self.headers.append((name, value))
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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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action = rule.get_action()
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log = rule.log_modification()
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self.logger.debug("{}: executing rule '{}'".format(self.queueid, rule.name))
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modified = rule.execute(self.headers)
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for name, value, index, occurrence in modified:
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if action == "add":
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if log:
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self.logger.info("{}: add: header: {}".format(self.queueid, "{}: {}".format(name, value)[0:50]))
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else:
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self.logger.debug("{}: add: header: {}".format(self.queueid, "{}: {}".format(name, value)[0:50]))
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self.headers.insert(0, (name, value))
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self.addheader(name, value, 1)
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else:
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self.chgheader(name, occurrence, value)
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if action == "mod":
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if log:
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self.logger.info("{}: modify: header: {}".format(self.queueid, "{}: {}".format(name, self.headers[index][1])[0:50]))
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else:
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self.logger.debug("{}: modify: header (occ. {}): {}".format(self.queueid, occurrence, "{}: {}".format(name, self.headers[index][1])[0:50]))
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self.headers[index] = (name, value)
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elif action == "del":
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if log:
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self.logger.info("{}: delete: header: {}".format(self.queueid, "{}: {}".format(name, self.headers[index][1])[0:50]))
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else:
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self.logger.debug("{}: delete: header (occ. {}): {}".format(self.queueid, occurrence, "{}: {}".format(name, self.headers[index][1])[0:50]))
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del self.headers[index]
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return Milter.ACCEPT
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except Exception as e:
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self.logger.exception("an exception occured in eom function: {}".format(e))
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return Milter.TEMPFAIL
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def main():
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"Run PyHeader-Milter."
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# parse command line
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parser = argparse.ArgumentParser(description="PyHeader milter daemon",
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formatter_class=lambda prog: argparse.HelpFormatter(prog, max_help_position=45, width=140))
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parser.add_argument("-c", "--config", help="Config file to read.", default="/etc/pyheader-milter.conf")
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parser.add_argument("-s", "--socket", help="Socket used to communicate with the MTA.", required=True)
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parser.add_argument("-d", "--debug", help="Log debugging messages.", action="store_true")
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parser.add_argument("-t", "--test", help="Check configuration.", action="store_true")
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args = parser.parse_args()
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# setup logging
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loglevel = logging.INFO
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logname = "pyheader-milter"
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syslog_name = logname
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if args.debug:
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loglevel = logging.DEBUG
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logname = "{}[%(name)s]".format(logname)
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syslog_name = "{}: [%(name)s] %(levelname)s".format(syslog_name)
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# set config files for milter class
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root_logger = logging.getLogger()
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root_logger.setLevel(loglevel)
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# setup console log
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stdouthandler = logging.StreamHandler(sys.stdout)
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stdouthandler.setLevel(logging.DEBUG)
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formatter = logging.Formatter("%(message)s".format(logname))
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stdouthandler.setFormatter(formatter)
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root_logger.addHandler(stdouthandler)
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logger = logging.getLogger(__name__)
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try:
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# read config file
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parser = configparser.ConfigParser()
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if not parser.read(args.config):
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raise RuntimeError("config file not found")
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# check if mandatory config options in global section are present
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if "global" not in parser.sections():
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raise RuntimeError("mandatory section 'global' not present in config file")
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for option in ["rules"]:
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if not parser.has_option("global", option):
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raise RuntimeError("mandatory option '{}' not present in config section 'global'".format(option))
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# read global config section
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global_config = dict(parser.items("global"))
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# read active rules
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active_rules = [ r.strip() for r in global_config["rules"].split(",") ]
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if len(active_rules) != len(set(active_rules)):
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raise RuntimeError("at least one rule is specified multiple times in 'rules' option")
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if "global" in active_rules:
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active_rules.remove("global")
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logger.warning("removed illegal rule name 'global' from list of active rules")
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if not active_rules:
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raise RuntimeError("no rules configured")
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logger.debug("preparing milter configuration ...")
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rules = []
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# iterate active rules
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for rule_name in active_rules:
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# check if config section exists
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if rule_name not in parser.sections():
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raise RuntimeError("config section '{}' does not exist".format(rule_name))
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config = dict(parser.items(rule_name))
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# check if mandatory option action is present in config
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option = "action"
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if option not in config.keys() and \
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option in global_config.keys():
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config[option] = global_config[option]
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if option not in config.keys():
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raise RuntimeError("mandatory option '{}' not specified for rule '{}'".format(option, rule_name))
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config["action"] = config["action"].lower()
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if config["action"] not in ["add", "del", "mod"]:
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raise RuntimeError("invalid action specified for rule '{}'".format(rule_name))
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# check if mandatory options are present in config
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mandatory = ["header"]
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if config["action"] == "add":
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mandatory += ["value"]
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elif config["action"] == "mod":
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mandatory += ["search", "value"]
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for option in mandatory:
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if option not in config.keys() and \
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option in global_config.keys():
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config[option] = global_config[option]
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if option not in config.keys():
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raise RuntimeError("mandatory option '{}' not specified for rule '{}'".format(option, rule_name))
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# check if optional config options are present in config
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defaults = {
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"ignore_hosts": [],
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"only_hosts": [],
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"log": "true"
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}
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for option in defaults.keys():
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if option not in config.keys() and \
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option in global_config.keys():
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config[option] = global_config[option]
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if option not in config.keys():
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config[option] = defaults[option]
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if config["ignore_hosts"]:
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config["ignore_hosts"] = [ h.strip() for h in config["ignore_hosts"].split(",") ]
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if config["only_hosts"]:
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config["only_hosts"] = [ h.strip() for h in config["only_hosts"].split(",") ]
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config["log"] = config["log"].lower()
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if config["log"] == "true":
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config["log"] = True
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elif config["log"] == "false":
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config["log"] = False
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else:
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raise RuntimeError("invalid value specified for option 'log' for rule '{}'".format(rule_name))
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# add rule
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logging.debug("adding rule '{}'".format(rule_name))
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rules.append(HeaderRule(name=rule_name, **config))
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except RuntimeError as e:
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logger.error(e)
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sys.exit(255)
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if args.test:
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print("Configuration ok")
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sys.exit(0)
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# change log format for runtime
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formatter = logging.Formatter("%(asctime)s {}: [%(levelname)s] %(message)s".format(logname), datefmt="%Y-%m-%d %H:%M:%S")
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stdouthandler.setFormatter(formatter)
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# setup syslog
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sysloghandler = logging.handlers.SysLogHandler(address="/dev/log", facility=logging.handlers.SysLogHandler.LOG_MAIL)
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sysloghandler.setLevel(loglevel)
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formatter = logging.Formatter("{}: %(message)s".format(syslog_name))
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sysloghandler.setFormatter(formatter)
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root_logger.addHandler(sysloghandler)
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logger.info("PyHeader-Milter starting")
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HeaderMilter.set_rules(rules)
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# register milter factory class
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Milter.factory = HeaderMilter
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Milter.set_exception_policy(Milter.TEMPFAIL)
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rc = 0
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try:
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Milter.runmilter("pyheader-milter", socketname=args.socket, timeout=30)
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except Milter.milter.error as e:
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logger.error(e)
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rc = 255
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logger.info("PyHeader-Milter terminated")
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sys.exit(rc)
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if __name__ == "__main__":
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main()
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