523 lines
17 KiB
Python
523 lines
17 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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"add_header",
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"mod_header",
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"del_header",
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"add_disclaimer",
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"rewrite_links",
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"store",
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"ActionConfig",
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"Action"]
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import logging
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import os
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import re
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from base64 import b64encode
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from bs4 import BeautifulSoup
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from collections import defaultdict
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from copy import copy
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from datetime import datetime
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from email.message import MIMEPart
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from pymodmilter import CustomLogger, BaseConfig
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from pymodmilter.conditions import ConditionsConfig, Conditions
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from pymodmilter import replace_illegal_chars
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def add_header(milter, field, value, pretend=False,
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logger=logging.getLogger(__name__)):
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"""Add a mail header field."""
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header = f"{field}: {value}"
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if logger.getEffectiveLevel() == logging.DEBUG:
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logger.debug(f"add_header: {header}")
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else:
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logger.info(f"add_header: {header[0:70]}")
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milter.msg.add_header(field, replace_illegal_chars(value))
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if not pretend:
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milter.addheader(field, value)
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def mod_header(milter, field, value, search=None, pretend=False,
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logger=logging.getLogger(__name__)):
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"""Change the value of a mail header field."""
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if isinstance(field, str):
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field = re.compile(field, re.IGNORECASE)
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if isinstance(search, str):
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search = re.compile(search, re.MULTILINE + re.DOTALL + re.IGNORECASE)
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idx = defaultdict(int)
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for i, (f, v) in enumerate(milter.msg.items()):
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f_lower = f.lower()
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idx[f_lower] += 1
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if not field.match(f):
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continue
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new_value = v
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if search is not None:
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new_value = search.sub(value, v).strip()
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else:
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new_value = value
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if not new_value:
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logger.warning(
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"mod_header: resulting value is empty, "
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"skip modification")
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continue
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if new_value == v:
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continue
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header = f"{f}: {v}"
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new_header = f"{f}: {new_value}"
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if logger.getEffectiveLevel() == logging.DEBUG:
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logger.debug(f"mod_header: {header}: {new_header}")
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else:
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logger.info(f"mod_header: {header[0:70]}: {new_header[0:70]}")
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milter.msg.replace_header(
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f, replace_illegal_chars(new_value), idx=idx[f_lower])
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if not pretend:
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milter.chgheader(f, new_value, idx=idx[f_lower])
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def del_header(milter, field, value=None, pretend=False,
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logger=logging.getLogger(__name__)):
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"""Delete a mail header field."""
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if isinstance(field, str):
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field = re.compile(field, re.IGNORECASE)
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if isinstance(value, str):
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value = re.compile(value, re.MULTILINE + re.DOTALL + re.IGNORECASE)
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idx = defaultdict(int)
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for f, v in milter.msg.items():
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f_lower = f.lower()
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idx[f_lower] += 1
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if not field.match(f):
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continue
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if value is not None and not value.search(v):
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continue
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header = f"{f}: {v}"
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if logger.getEffectiveLevel() == logging.DEBUG:
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logger.debug(f"del_header: {header}")
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else:
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logger.info(f"del_header: {header[0:70]}")
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milter.msg.remove_header(f, idx=idx[f_lower])
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if not pretend:
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milter.chgheader(f, "", idx=idx[f_lower])
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idx[f_lower] -= 1
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def _get_body_content(msg, pref):
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part = None
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content = None
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if not msg.is_multipart() and msg.get_content_type() == f"text/{pref}":
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part = msg
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else:
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part = msg.get_body(preferencelist=(pref))
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if part is not None:
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content = part.get_content()
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return (part, content)
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def _has_content_before_body_tag(soup):
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s = copy(soup)
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for element in s.find_all("head") + s.find_all("body"):
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element.extract()
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if len(s.text.strip()) > 0:
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return True
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return False
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def _patch_message_body(milter, action, text_template, html_template, logger):
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text_body, text_content = _get_body_content(milter.msg, "plain")
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html_body, html_content = _get_body_content(milter.msg, "html")
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if text_content is None and html_content is None:
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raise RuntimeError("message does not contain any body part")
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if text_content is not None:
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logger.info(f"{action} text disclaimer")
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if action == "prepend":
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content = f"{text_template}{text_content}"
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else:
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content = f"{text_content}{text_template}"
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text_body.set_content(
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content.encode(), maintype="text", subtype="plain")
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text_body.set_param("charset", "UTF-8", header="Content-Type")
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del text_body["MIME-Version"]
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if html_content is not None:
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logger.info(f"{action} html disclaimer")
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soup = BeautifulSoup(html_content, "html.parser")
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body = soup.find('body')
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if not body:
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body = soup
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elif _has_content_before_body_tag(soup):
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body = soup
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if action == "prepend":
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body.insert(0, copy(html_template))
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else:
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body.append(html_template)
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html_body.set_content(
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str(soup).encode(), maintype="text", subtype="html")
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html_body.set_param("charset", "UTF-8", header="Content-Type")
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del html_body["MIME-Version"]
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def _wrap_message(milter, logger):
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attachment = MIMEPart()
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attachment.set_content(milter.msg.as_bytes(),
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maintype="plain", subtype="text",
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disposition="attachment",
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filename=f"{milter.qid}.eml",
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params={"name": f"{milter.qid}.eml"})
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milter.msg.clear_content()
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milter.msg.set_content(
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"Please see the original email attached.")
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milter.msg.add_alternative(
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"<html><body>Please see the original email attached.</body></html>",
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subtype="html")
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milter.msg.make_mixed()
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milter.msg.attach(attachment)
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def _inject_body(milter):
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if not milter.msg.is_multipart():
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milter.msg.make_mixed()
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attachments = []
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for attachment in milter.msg.iter_attachments():
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if "content-disposition" not in attachment:
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attachment["Content-Disposition"] = "attachment"
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attachments.append(attachment)
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milter.msg.clear_content()
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milter.msg.set_content("")
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milter.msg.add_alternative("", subtype="html")
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milter.msg.make_mixed()
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for attachment in attachments:
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milter.msg.attach(attachment)
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def add_disclaimer(milter, text_template, html_template, action, error_policy,
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pretend=False, logger=logging.getLogger(__name__)):
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"""Append or prepend a disclaimer to the mail body."""
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old_headers = milter.msg.items()
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try:
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try:
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_patch_message_body(
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milter, action, text_template, html_template, logger)
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except RuntimeError as e:
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logger.info(f"{e}, inject empty plain and html body")
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_inject_body(milter)
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_patch_message_body(
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milter, action, text_template, html_template, logger)
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except Exception as e:
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logger.warning(e)
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if error_policy == "ignore":
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logger.info(
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"unable to add disclaimer to message body, "
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"ignore error according to policy")
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return
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elif error_policy == "reject":
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logger.info(
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"unable to add disclaimer to message body, "
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"reject message according to policy")
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return [
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("reject", "Message rejected due to error")]
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logger.info("wrap original message in a new message envelope")
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try:
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_wrap_message(milter, logger)
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_patch_message_body(
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milter, action, text_template, html_template, logger)
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except Exception as e:
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logger.error(e)
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raise Exception(
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"unable to wrap message in a new message envelope, "
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"give up ...")
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if not pretend:
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milter.update_headers(old_headers)
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milter.replacebody()
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def rewrite_links(milter, repl, pretend=False,
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logger=logging.getLogger(__name__)):
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"""Rewrite link targets in the mail html body."""
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html_body, html_content = _get_body_content(milter.msg, "html")
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if html_content is not None:
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soup = BeautifulSoup(html_content, "html.parser")
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rewritten = 0
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for link in soup.find_all("a", href=True):
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if not link["href"]:
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continue
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if "{URL_B64}" in repl:
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url_b64 = b64encode(link["href"].encode()).decode()
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target = repl.replace("{URL_B64}", url_b64)
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else:
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target = repl
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link["href"] = target
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rewritten += 1
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if rewritten:
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logger.info(f"rewrote {rewritten} link(s) in html body")
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html_body.set_content(
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str(soup).encode(), maintype="text", subtype="html")
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html_body.set_param("charset", "UTF-8", header="Content-Type")
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del html_body["MIME-Version"]
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if not pretend:
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milter.replacebody()
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def store(milter, directory, pretend=False,
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logger=logging.getLogger(__name__)):
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timestamp = datetime.now().strftime("%Y%m%d%H%M%S")
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store_id = f"{timestamp}_{milter.qid}"
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datafile = os.path.join(directory, store_id)
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logger.info(f"store message in file {datafile}")
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try:
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with open(datafile, "wb") as fp:
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fp.write(milter.msg.as_bytes())
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except IOError as e:
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raise RuntimeError(f"unable to store message: {e}")
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class ActionConfig(BaseConfig):
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def __init__(self, idx, rule_cfg, cfg, debug):
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if "name" in cfg:
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assert isinstance(cfg["name"], str), \
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f"{rule_cfg['name']}: Action #{idx}: name: invalid value, " \
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f"should be string"
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cfg["name"] = f"{rule_cfg['name']}: {cfg['name']}"
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else:
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cfg["name"] = f"{rule_cfg['name']}: Action #{idx}"
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if "loglevel" not in cfg:
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cfg["loglevel"] = rule_cfg["loglevel"]
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super().__init__(cfg, debug)
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self["pretend"] = rule_cfg["pretend"]
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self["conditions"] = None
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self["type"] = ""
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if "pretend" in cfg:
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pretend = cfg["pretend"]
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assert isinstance(pretend, bool), \
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f"{self['name']}: pretend: invalid value, should be bool"
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self["pretend"] = pretend
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assert "type" in cfg, \
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f"{self['name']}: mandatory parameter 'type' not found"
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assert isinstance(cfg["type"], str), \
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f"{self['name']}: type: invalid value, should be string"
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self["type"] = cfg["type"]
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if self["type"] == "add_header":
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self["func"] = add_header
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self["need_body"] = False
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if not "field" in cfg and "header" in cfg:
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cfg["field"] = cfg["header"]
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self.add_string_arg(cfg, ("field", "value"))
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elif self["type"] == "mod_header":
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self["func"] = mod_header
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self["need_body"] = False
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if not "field" in cfg and "header" in cfg:
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cfg["field"] = cfg["header"]
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args = ["field", "value"]
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if "search" in cfg:
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args.append("search")
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for arg in args:
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self.add_string_arg(cfg, arg)
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if arg in ("field", "search"):
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try:
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self["args"][arg] = re.compile(
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self["args"][arg],
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re.MULTILINE + re.DOTALL + re.IGNORECASE)
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except re.error as e:
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raise ValueError(f"{self['name']}: {arg}: {e}")
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elif self["type"] == "del_header":
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self["func"] = del_header
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self["need_body"] = False
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if not "field" in cfg and "header" in cfg:
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cfg["field"] = cfg["header"]
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args = ["field"]
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if "value" in cfg:
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args.append("value")
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for arg in args:
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self.add_string_arg(cfg, arg)
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try:
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self["args"][arg] = re.compile(
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self["args"][arg],
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re.MULTILINE + re.DOTALL + re.IGNORECASE)
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except re.error as e:
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raise ValueError(f"{self['name']}: {arg}: {e}")
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elif self["type"] == "add_disclaimer":
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self["func"] = add_disclaimer
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self["need_body"] = True
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if not "html_template" in cfg and "html_file" in cfg:
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cfg["html_template"] = cfg["html_file"]
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if not "text_template" in cfg and "text_file" in cfg:
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cfg["text_template"] = cfg["text_file"]
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if "error_policy" not in cfg:
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cfg["error_policy"] = "wrap"
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self.add_string_arg(
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cfg, ("action", "html_template", "text_template",
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"error_policy"))
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assert self["args"]["action"] in ("append", "prepend"), \
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f"{self['name']}: action: invalid value, " \
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f"should be 'append' or 'prepend'"
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assert self["args"]["error_policy"] in ("wrap",
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"ignore",
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"reject"), \
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f"{self['name']}: error_policy: invalid value, " \
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f"should be 'wrap', 'ignore' or 'reject'"
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try:
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with open(self["args"]["html_template"], "r") as f:
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html = BeautifulSoup(f.read(), "html.parser")
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body = html.find('body')
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if body:
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# just use content within the body tag if present
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html = body
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self["args"]["html_template"] = html
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with open(self["args"]["text_template"], "r") as f:
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self["args"]["text_template"] = f.read()
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except IOError as e:
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raise RuntimeError(
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f"{self['name']}: unable to open/read template file: {e}")
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elif self["type"] == "rewrite_links":
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self["func"] = rewrite_links
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self["need_body"] = True
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self.add_string_arg(cfg, "repl")
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elif self["type"] == "store":
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self["func"] = store
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self["need_body"] = True
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assert "storage_type" in cfg, \
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f"{self['name']}: mandatory parameter 'storage_type' not found"
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assert isinstance(cfg["type"], str), \
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f"{self['name']}: storage_type: invalid value, " \
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f"should be string"
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self["storage_type"] = cfg["storage_type"]
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if self["storage_type"] == "file":
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self.add_string_arg(cfg, "directory")
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else:
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raise RuntimeError(
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f"{self['name']}: storage_type: invalid storage type")
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else:
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raise RuntimeError(f"{self['name']}: type: invalid action type")
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if "conditions" in cfg:
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conditions = cfg["conditions"]
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assert isinstance(conditions, dict), \
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f"{self['name']}: conditions: invalid value, should be dict"
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self["conditions"] = ConditionsConfig(self, conditions, debug)
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self.logger.debug(f"pretend={self['pretend']}, "
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f"loglevel={self['loglevel']}, "
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f"type={self['type']}, "
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f"args={self['args']}")
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class Action:
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"""Action to implement a pre-configured action to perform on e-mails."""
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def __init__(self, milter_cfg, cfg):
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self.logger = cfg.logger
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if cfg["conditions"] is None:
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self.conditions = None
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else:
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self.conditions = Conditions(milter_cfg, cfg["conditions"])
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self.pretend = cfg["pretend"]
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self._name = cfg["name"]
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self._func = cfg["func"]
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self._args = cfg["args"]
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self._need_body = cfg["need_body"]
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def need_body(self):
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"""Return the needs of this action."""
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return self._need_body
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def execute(self, milter, pretend=None):
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"""Execute configured action."""
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if pretend is None:
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pretend = self.pretend
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logger = CustomLogger(
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self.logger, {"name": self._name, "qid": milter.qid})
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return self._func(milter=milter, pretend=pretend,
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logger=logger, **self._args)
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