107 lines
4.7 KiB
Python
107 lines
4.7 KiB
Python
import urllib
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from email.header import Header
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from email.message import Message
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from app.email import headers
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from app.email_utils import add_or_replace_header, delete_header
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from app.handler.unsubscribe_encoder import (
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UnsubscribeEncoder,
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UnsubscribeAction,
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UnsubscribeData,
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UnsubscribeOriginalData,
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)
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from app.log import LOG
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from app.models import Alias, Contact, UnsubscribeBehaviourEnum
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class UnsubscribeGenerator:
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def _generate_header_with_original_behaviour(
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self, alias: Alias, message: Message
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) -> Message:
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"""
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Generate a header that will encode the original unsub request. To do so
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1. Look if there's an original List_Unsubscribe headers, otherwise do nothing
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2. Header has the form <method1>, <method2>, .. where each method is either
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- mailto:s@b.c?subject=something
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- http(s)://somewhere.com
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3. Check if there are http unsub requests in the header. If there are, reserve them and remove all mailto
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methods to avoid leaking the real mailbox. We forward the message with only http(s) methods.
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4. If there aren't neither https nor mailto methods, strip the header from the message and that's it.
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It could happen if the header is malformed.
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5. Encode in our unsub request the first original mail and subject to unsub, and use that as our unsub header.
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"""
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unsubscribe_data = message[headers.LIST_UNSUBSCRIBE]
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if not unsubscribe_data:
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LOG.info("Email has no unsubscribe header")
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return message
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if isinstance(unsubscribe_data, Header):
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unsubscribe_data = str(unsubscribe_data.encode)
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raw_methods = [method.strip() for method in unsubscribe_data.split(",")]
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mailto_unsubs = None
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other_unsubs = []
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for raw_method in raw_methods:
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start = raw_method.find("<")
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end = raw_method.rfind(">")
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if start == -1 or end == -1 or start >= end:
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continue
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method = raw_method[start + 1 : end]
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url_data = urllib.parse.urlparse(method)
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if url_data.scheme == "mailto":
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query_data = urllib.parse.parse_qs(url_data.query)
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mailto_unsubs = (url_data.path, query_data.get("subject", [""])[0])
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LOG.debug(f"Unsub is mailto to {mailto_unsubs}")
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else:
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LOG.debug(f"Unsub has {url_data.scheme} scheme")
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other_unsubs.append(method)
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# If there are non mailto unsubscribe methods, use those in the header
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if other_unsubs:
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add_or_replace_header(
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message,
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headers.LIST_UNSUBSCRIBE,
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", ".join([f"<{method}>" for method in other_unsubs]),
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)
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add_or_replace_header(
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message, headers.LIST_UNSUBSCRIBE_POST, "List-Unsubscribe=One-Click"
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)
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LOG.debug(f"Adding click unsub methods to header {other_unsubs}")
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return message
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elif not mailto_unsubs:
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LOG.debug("No unsubs. Deleting all unsub headers")
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delete_header(message, headers.LIST_UNSUBSCRIBE)
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delete_header(message, headers.LIST_UNSUBSCRIBE_POST)
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return message
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unsub_data = UnsubscribeData(
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UnsubscribeAction.OriginalUnsubscribeMailto,
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UnsubscribeOriginalData(alias.id, mailto_unsubs[0], mailto_unsubs[1]),
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)
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LOG.debug(f"Adding unsub data {unsub_data}")
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return self._add_unsubscribe_header(message, unsub_data)
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def _add_unsubscribe_header(
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self, message: Message, unsub: UnsubscribeData
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) -> Message:
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unsub_link = UnsubscribeEncoder.encode(unsub.action, unsub.data)
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add_or_replace_header(message, headers.LIST_UNSUBSCRIBE, f"<{unsub_link.link}>")
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if not unsub_link.via_email:
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add_or_replace_header(
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message, headers.LIST_UNSUBSCRIBE_POST, "List-Unsubscribe=One-Click"
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)
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return message
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def add_header_to_message(
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self, alias: Alias, contact: Contact, message: Message
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) -> Message:
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"""
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Add List-Unsubscribe header based on the user preference.
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"""
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unsub_behaviour = alias.user.unsub_behaviour
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if unsub_behaviour == UnsubscribeBehaviourEnum.PreserveOriginal:
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return self._generate_header_with_original_behaviour(alias, message)
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elif unsub_behaviour == UnsubscribeBehaviourEnum.DisableAlias:
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unsub = UnsubscribeData(UnsubscribeAction.DisableAlias, alias.id)
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return self._add_unsubscribe_header(message, unsub)
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else:
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unsub = UnsubscribeData(UnsubscribeAction.DisableContact, contact.id)
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return self._add_unsubscribe_header(message, unsub)
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