Fix #1474 - Check for URI scheme in DMARC parser (#1493)

This also adds some small unit tests for DMARC parsing.

checks/tasks/dmarc_parser.py

@@ -74,9 +74,11 @@ def _check_dmarc_uri(tokens):
         uri, numeric = uri.split("!")
         dmarc_uri_numeric.parseString(numeric)
     try:
-        urlparse(uri)
+        parsed_url = urlparse(uri)
     except ValueError:
         raise ParseException("Could not parse URI.")
+    if parsed_url.scheme == "":
+        raise ParseException("URI scheme is missing (mailto:).")
     return None
 
 

checks/test/test_dmarc_parser.py

@@ -0,0 +1,30 @@
+# Copyright: 2024, ECP, NLnet Labs and the Internet.nl contributors
+# SPDX-License-Identifier: Apache-2.0
+import pytest
+from pyparsing import ParseException
+
+from checks.tasks.dmarc_parser import _check_dmarc_uri, parse
+
+
+def test__check_dmarc_uri():
+    """
+    Check if None is returned on valid URI
+    """
+    assert _check_dmarc_uri(["mailto:[email protected]"]) is None
+
+
+def test__check_dmarc_uri_detect_missing_uri_scheme():
+    """
+    Many people forget to add the mailto: scheme to their DMARC URI.
+    This common error should be detected.
+    """
+    with pytest.raises(ParseException):
+        _check_dmarc_uri(["[email protected]"])
+
+
+def test_parse():
+    sample_record = "v=DMARC1; p=none; rua=mailto:[email protected]"
+    result = parse(sample_record)
+    assert result.version == "v=DMARC1"
+    assert result.directives.request == "p=none"
+    assert result.directives.auri == "rua=mailto:[email protected]"