c3lf-system-3/core/mail/protocol.py

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import logging
import aiosmtplib
from channels.layers import get_channel_layer
from channels.db import database_sync_to_async
from django.core.files.base import ContentFile
from mail.models import Email, EventAddress, EmailAttachment
from notify_sessions.models import SystemEvent
from tickets.models import IssueThread
def find_quoted_printable(s, marker):
positions = [i for i in range(len(s)) if s.lower().startswith('=?utf-8?' + marker + '?', i)]
for pos in positions:
end = s.find('?=', pos + 10)
if end == -1:
continue
yield pos, end + 3
def unescape_and_decode_quoted_printable(s):
import quopri
decoded = ''
last_end = 0
for start, end in find_quoted_printable(s, 'q'):
decoded += s[last_end:start]
decoded += quopri.decodestring(s[start + 10:end - 3]).decode('utf-8')
last_end = end
decoded += s[last_end:]
return decoded
def unescape_and_decode_base64(s):
import base64
decoded = ''
last_end = 0
for start, end in find_quoted_printable(s, 'b'):
decoded += s[last_end:start]
decoded += base64.b64decode(s[start + 10:end - 3]).decode('utf-8')
last_end = end
decoded += s[last_end:]
return decoded
def unescape_simplified_quoted_printable(s):
import quopri
return quopri.decodestring(s).decode('utf-8')
def collect_references(issue_thread):
mails = issue_thread.emails.order_by('timestamp')
references = []
for mail in mails:
if mail.reference:
references.append(mail.reference)
return references
def make_reply(reply_email, references=None, event=None):
from email.message import EmailMessage
from core.settings import MAIL_DOMAIN
event = event or "mail"
reply = EmailMessage()
reply["From"] = reply_email.sender
reply["To"] = reply_email.recipient
reply["Subject"] = reply_email.subject
reply["Reply-To"] = f"{event}@{MAIL_DOMAIN}"
if reply_email.in_reply_to:
reply["In-Reply-To"] = reply_email.in_reply_to
if reply_email.reference:
reply["Message-ID"] = reply_email.reference
else:
reply["Message-ID"] = reply_email.id + "@" + MAIL_DOMAIN
reply_email.reference = reply["Message-ID"]
reply_email.save()
if references:
reply["References"] = " ".join(references)
reply.set_content(reply_email.body)
return reply
async def send_smtp(message):
await aiosmtplib.send(message, hostname="127.0.0.1", port=25, use_tls=False, start_tls=False)
def find_active_issue_thread(in_reply_to, address, subject):
from re import match
uuid_match = match(r'^ticket\+([a-f0-9-]{36})@', address)
if uuid_match:
issue = IssueThread.objects.filter(uuid=uuid_match.group(1))
if issue.exists():
return issue.first(), False
reply_to = Email.objects.filter(reference=in_reply_to)
if reply_to.exists():
return reply_to.first().issue_thread, False
else:
issue = IssueThread.objects.create(name=subject)
return issue, True
def find_target_event(address):
try:
address_map = EventAddress.objects.get(address=address)
if address_map.event:
return address_map.event
except EventAddress.DoesNotExist:
pass
return None
def parse_email_body(raw, log=None):
import email
from hashlib import sha256
attachments = []
parsed = email.message_from_bytes(raw)
body = ""
if parsed.is_multipart():
for part in parsed.walk():
ctype = part.get_content_type()
cdispo = str(part.get('Content-Disposition'))
# skip any text/plain (txt) attachments
if ctype == 'text/plain' and 'attachment' not in cdispo:
segment = part.get_payload()
if not segment:
continue
segment = unescape_and_decode_quoted_printable(segment)
segment = unescape_and_decode_base64(segment)
if part.get('Content-Transfer-Encoding') == 'quoted-printable':
segment = unescape_simplified_quoted_printable(segment)
log.debug(segment)
body = body + segment
elif 'attachment' in cdispo or 'inline' in cdispo:
file = ContentFile(part.get_payload(decode=True))
chash = sha256(file.read()).hexdigest()
name = part.get_filename()
if name is None:
name = "unnamed"
attachment, _ = EmailAttachment.objects.get_or_create(
name=name, mime_type=ctype, file=file, hash=chash)
attachment.save()
attachments.append(attachment)
if 'inline' in cdispo:
body = body + f'<img src="cid:{attachment.id}">'
log.info("Image %s %s", ctype, attachment.id)
else:
log.info("Attachment %s %s", ctype, cdispo)
else:
if parsed.get_content_type() == 'text/plain':
body = parsed.get_payload()
elif parsed.get_content_type() == 'text/html':
from bs4 import BeautifulSoup
import re
body = parsed.get_payload()
soup = BeautifulSoup(body, 'html.parser')
body = re.sub(r'([\r\n]+.?)*[\r\n]', r'\n', soup.get_text()).strip('\n')
else:
log.warning("Unknown content type %s", parsed.get_content_type())
body = "Unknown content type"
body = unescape_and_decode_quoted_printable(body)
body = unescape_and_decode_base64(body)
if parsed.get('Content-Transfer-Encoding') == 'quoted-printable':
body = unescape_simplified_quoted_printable(body)
log.debug(body)
return parsed, body, attachments
@database_sync_to_async
def receive_email(envelope, log=None):
parsed, body, attachments = parse_email_body(envelope.content, log)
header_from = parsed.get('From')
header_to = parsed.get('To')
header_in_reply_to = parsed.get('In-Reply-To')
header_message_id = parsed.get('Message-ID')
if header_from != envelope.mail_from:
log.warning("Header from does not match envelope from")
log.info(f"Header from: {header_from}, envelope from: {envelope.mail_from}")
if header_to != envelope.rcpt_tos[0]:
log.warning("Header to does not match envelope to")
log.info(f"Header to: {header_to}, envelope to: {envelope.rcpt_tos[0]}")
recipient = envelope.rcpt_tos[0].lower() if envelope.rcpt_tos else header_to.lower()
sender = envelope.mail_from if envelope.mail_from else header_from
subject = parsed.get('Subject')
if not subject:
subject = "No subject"
subject = unescape_and_decode_quoted_printable(subject)
subject = unescape_and_decode_base64(subject)
target_event = find_target_event(recipient)
active_issue_thread, new = find_active_issue_thread(header_in_reply_to, recipient, subject)
email = Email.objects.create(
sender=sender, recipient=recipient, body=body, subject=subject, reference=header_message_id,
in_reply_to=header_in_reply_to, raw=envelope.content, event=target_event,
issue_thread=active_issue_thread)
for attachment in attachments:
email.attachments.add(attachment)
email.save()
reply = None
if new:
# auto reply if new issue
references = collect_references(active_issue_thread)
if not sender.startswith('noreply'):
subject = f"Re: {subject} [#{active_issue_thread.short_uuid()}]"
body = '''Your request (#{}) has been received and will be reviewed by our lost&found angels.
We are reviewing incoming requests during the event and teardown. Immediately after the event, expect a delay as the \
workload is high. We will not forget about your request and get back in touch once we have updated information on your \
request. Requests for devices, wallets, credit cards or similar items will be handled with priority.
If you happen to find your lost item or just want to add additional information, please reply to this email. Please \
do not create a new request.
Your c3lf (Cloakroom + Lost&Found) Team'''.format(active_issue_thread.short_uuid())
reply_email = Email.objects.create(
sender=recipient, recipient=sender, body=body, subject=subject,
in_reply_to=header_message_id, event=target_event, issue_thread=active_issue_thread)
reply = make_reply(reply_email, references, event=target_event.slug if target_event else None)
else:
# change state if not new
if active_issue_thread.state != 'pending_new':
active_issue_thread.state = 'pending_open'
active_issue_thread.save()
return email, new, reply
class LMTPHandler:
async def handle_RCPT(self, server, session, envelope, address, rcpt_options):
from core.settings import MAIL_DOMAIN
address = address.lower()
if not address.endswith('@' + MAIL_DOMAIN):
return '550 not relaying to that domain'
envelope.rcpt_tos.append(address)
return '250 OK'
async def handle_DATA(self, server, session, envelope):
log = logging.getLogger('mail.log')
log.setLevel(logging.DEBUG)
log.info('Message from %s' % envelope.mail_from)
log.info('Message for %s' % envelope.rcpt_tos)
log.info('Message data:\n')
content = None
try:
content = envelope.content
email, new, reply = await receive_email(envelope, log)
log.info(f"Created email {email.id}")
systemevent = await database_sync_to_async(SystemEvent.objects.create)(type='email received',
reference=email.id)
log.info(f"Created system event {systemevent.id}")
channel_layer = get_channel_layer()
await channel_layer.group_send(
'general', {"type": "generic.event", "name": "send_message_to_frontend", "event_id": systemevent.id,
"message": "email received"}
)
log.info(f"Sent message to frontend")
if new and reply:
log.info('Sending message to %s' % reply['To'])
await send_smtp(reply)
log.info("Sent auto reply")
return '250 Message accepted for delivery'
except Exception as e:
from hashlib import sha256
random_filename = 'mail-' + sha256(content).hexdigest()
with open(random_filename, 'wb') as f:
f.write(content)
log.error(f"Saved email to {random_filename} because of error %s (%s)", e, type(e))
return '451 Internal server error'