DSN: Prvotní verze API na parsování DSN

mo/web/__init__.py

@@ -261,6 +261,7 @@ except ImportError:
 
 # Většina webu je v samostatných modulech
 import mo.web.api
+import mo.web.api_dsn
 import mo.web.acct
 import mo.web.doc
 import mo.web.jinja

mo/web/api_dsn.py

+# Web: API pro zpracování mailových Delivery Status Notifications
+
+import email
+from email.errors import MessageError
+import email.headerregistry
+import email.message
+import email.parser
+import email.policy
+from flask import request, Response
+from flask.json import jsonify
+import re
+from typing import Optional
+import werkzeug.exceptions
+
+import mo.config as config
+import mo.email
+import mo.util_format
+from mo.web import app
+
+
+class DSN:
+    msg: email.message.EmailMessage
+    message_id: str
+    verdict: str
+    dsn_action: str
+    dsn_status: str
+
+    def __init__(self, body: bytes):
+        self.msg = email.message_from_bytes(body, policy=email.policy.default)  # FIXME: Types
+        self.message_id = (self.msg['Message-Id'] or '?').strip()
+        self.dsn_action = '?'
+        self.dsn_status = '?'
+        self.verdict = self.parse_dsn()
+
+    def parse_dsn(self) -> str:
+        if self.msg.get_content_type() != 'multipart/report':
+            return 'unexpected content-type'
+
+        if not self.msg.is_multipart():
+            return 'not multipart'
+
+        report_type = self.msg['Content-type'].params.get('report-type', '?')
+        if report_type != 'delivery-status':
+            return 'unknown report-type'
+
+        if len(self.msg.get_payload()) < 2:
+            return 'too few parts'
+
+        part2: email.message.EmailMessage = self.msg.get_payload(1)
+        if part2.get_content_type() != 'message/delivery-status':
+            return 'unexpected part 2 type'
+
+        dsn = part2.get_payload()
+        if len(dsn) < 2:
+            return 'DSN too short'
+
+        # main = dsn[0]
+
+        per_addr = dsn[1]
+        self.dsn_action = per_addr.get('Action', '?')
+        self.dsn_status = per_addr.get('Status', '?')
+
+        if self.dsn_action != 'failed':
+            return 'not failed'
+
+        return 'ok'
+
+    def find_token(self) -> Optional[str]:
+        to = self.msg.get('To')
+        if to is None:
+            return None
+
+        std_from = email.headerregistry.Address(addr_spec=config.MAIL_CONTACT)
+
+        for addr in to.addresses:
+            if m := re.fullmatch(r'([^+]+)\+(.*)', addr.username):
+                if m[1] == std_from.username and addr.domain == std_from.domain:
+                    return m[2]
+
+        return None
+
+
+@app.route('/api/email-dsn', methods=('POST',))
+def api_email_dsn() -> Response:
+    # FIXME: Authorization?
+    # FIXME: Add in Flask 3.1: request.max_content_length = 1048576
+    body = request.get_data(cache=False)
+
+    try:
+        dsn = DSN(body)
+    except MessageError as e:
+        app.logger.info(f'DSN: Nemohu naparsovat zprávu: {e}')
+        raise werkzeug.exceptions.UnprocessableEntity()
+
+    app.logger.info(f'DSN: Message-ID: {dsn.message_id}')
+    app.logger.info(f'DSN: Parse: action={dsn.dsn_action} status={dsn.dsn_status} -> {dsn.verdict}')
+
+    if dsn.verdict == 'not failed':
+        return jsonify({})
+    elif dsn.verdict != 'ok':
+        raise werkzeug.exceptions.UnprocessableEntity()
+
+    if not (token := dsn.find_token()):
+        app.logger.info('DSN: Token not found')
+        raise werkzeug.exceptions.UnprocessableEntity()
+    app.logger.info(f'DSN: Token: {token}')
+
+    try:
+        user, rr, when = mo.email.validate_dsn_token(token)
+        user_info = f'#{user.user_id}' if user is not None else '-'
+        rr_info = f'#{rr.reg_id}' if rr is not None else '-'
+        age = mo.util_format.time_duration_numeric(mo.now - when)
+        app.logger.info(f'DSN: user={user_info} registration={rr_info} age={age}')
+    except ValueError as e:
+        app.logger.info(f'DSN: {e}')
+        pass
+
+    return jsonify({})