Merge #2397

2397: Fix resolving alias addresses for postfix when target is a punycode domain r=mergify[bot] a=ghostwheel42

## What type of PR?

bug-fix

## What does this PR do?

- fix splitting of localpart in resolve_destination
- idna-enode domain-part of email addresses before returning to postfix

### Related issue(s)
- closes #2393


Co-authored-by: Alexander Graf <ghostwheel42@users.noreply.github.com>

core/admin/mailu/internal/views/postfix.py

@@ -33,8 +33,9 @@ def postfix_alias_map(alias):
     localpart, domain_name = models.Email.resolve_domain(alias)
     if localpart is None:
         return flask.jsonify(domain_name)
-    destination = models.Email.resolve_destination(localpart, domain_name)
-    return flask.jsonify(",".join(destination)) if destination else flask.abort(404)
+    if destinations := models.Email.resolve_destination(localpart, domain_name):
+        return flask.jsonify(",".join(idna_encode(destinations)))
+    return flask.abort(404)
 
 @internal.route("/postfix/transport/<path:email>")
 def postfix_transport(email):
@@ -142,9 +143,11 @@ def postfix_sender_login(sender):
     if localpart is None:
         return flask.jsonify(",".join(wildcard_senders)) if wildcard_senders else flask.abort(404)
     localpart = localpart[:next((i for i, ch in enumerate(localpart) if ch in flask.current_app.config.get('RECIPIENT_DELIMITER')), None)]
-    destination = models.Email.resolve_destination(localpart, domain_name, True)
-    destination = [*destination, *wildcard_senders] if destination else [*wildcard_senders]
-    return flask.jsonify(",".join(destination)) if destination else flask.abort(404)
+    destinations = models.Email.resolve_destination(localpart, domain_name, True) or []
+    destinations.extend(wildcard_senders)
+    if destinations:
+        return flask.jsonify(",".join(idna_encode(destinations)))
+    return flask.abort(404)
 
 @internal.route("/postfix/sender/rate/<path:sender>")
 def postfix_sender_rate(sender):
@@ -169,3 +172,11 @@ def postfix_sender_access(sender):
         except sqlalchemy.exc.StatementError:
             pass
     return flask.abort(404)
+
+# idna encode domain part of each address in list of addresses
+def idna_encode(addresses):
+    return [
+        f"{localpart}@{idna.encode(domain).decode('ascii')}"
+        for (localpart, domain) in
+        (address.rsplit("@", 1) for address in addresses)
+    ]

core/admin/mailu/models.py

@@ -439,10 +439,15 @@ class Email(object):
         localpart_stripped = None
         stripped_alias = None
 
-        delim = os.environ.get('RECIPIENT_DELIMITER')
-        if delim in localpart:
-            localpart_stripped = localpart.rsplit(delim, 1)[0]
+        if delims := os.environ.get('RECIPIENT_DELIMITER'):
+            try:
+                pos = next(i for i, c in enumerate(localpart) if c in delims)
+            except StopIteration:
+                pass
+            else:
+                localpart_stripped = localpart[:pos]
 
+        # is localpart@domain_name or localpart_stripped@domain_name an user?
         user = User.query.get(f'{localpart}@{domain_name}')
         if not user and localpart_stripped:
             user = User.query.get(f'{localpart_stripped}@{domain_name}')
@@ -450,19 +455,18 @@ class Email(object):
         if user:
             email = f'{localpart}@{domain_name}'
 
-            if user.forward_enabled:
-                destination = user.forward_destination
-                if user.forward_keep or ignore_forward_keep:
-                    destination.append(email)
-            else:
-                destination = [email]
+            if not user.forward_enabled:
+                return [email]
 
+            destination = user.forward_destination
+            if user.forward_keep or ignore_forward_keep:
+                destination.append(email)
             return destination
 
-        pure_alias = Alias.resolve(localpart, domain_name)
-
-        if pure_alias and not pure_alias.wildcard:
-            return pure_alias.destination
+        # is localpart, domain_name or localpart_stripped@domain_name an alias?
+        if pure_alias := Alias.resolve(localpart, domain_name):
+            if not pure_alias.wildcard:
+                return pure_alias.destination
 
         if stripped_alias := Alias.resolve(localpart_stripped, domain_name):
             return stripped_alias.destination