fix: accept uppercase .local. trailer in service_type_name (#1747)

bluetoothbot · web-flow · commit 37edde2f5d96 · 2026-05-20T07:16:14.000-05:00
diff --git a/src/zeroconf/_utils/name.py b/src/zeroconf/_utils/name.py
@@ -83,7 +83,9 @@ def service_type_name(type_: str, *, strict: bool = True) -> str:  # pylint: dis
         # https://datatracker.ietf.org/doc/html/rfc6763#section-7.2
         raise BadTypeInNameException(f"Full name ({type_}) must be > 256 bytes")
 
-    if type_.endswith((_TCP_PROTOCOL_LOCAL_TRAILER, _NONTCP_PROTOCOL_LOCAL_TRAILER)):
+    # RFC 1035 §2.3.3 / RFC 6762 §16 — DNS name comparisons are case-insensitive.
+    type_lower = type_.lower()
+    if type_lower.endswith((_TCP_PROTOCOL_LOCAL_TRAILER, _NONTCP_PROTOCOL_LOCAL_TRAILER)):
         remaining = type_[: -len(_TCP_PROTOCOL_LOCAL_TRAILER)].split(".")
         trailer = type_[-len(_TCP_PROTOCOL_LOCAL_TRAILER) :]
         has_protocol = True
@@ -92,7 +94,7 @@ def service_type_name(type_: str, *, strict: bool = True) -> str:  # pylint: dis
             f"Type '{type_}' must end with "
             f"'{_TCP_PROTOCOL_LOCAL_TRAILER}' or '{_NONTCP_PROTOCOL_LOCAL_TRAILER}'"
         )
-    elif type_.endswith(_LOCAL_TRAILER):
+    elif type_lower.endswith(_LOCAL_TRAILER):
         remaining = type_[: -len(_LOCAL_TRAILER)].split(".")
         trailer = type_[-len(_LOCAL_TRAILER) + 1 :]
         has_protocol = False
diff --git a/tests/utils/test_name.py b/tests/utils/test_name.py
@@ -61,6 +61,28 @@ def test_service_type_name_non_strict_compliant_names(instance_name, service_typ
     assert instance_name_from_service_info(info, strict=False) == instance_name
 
 
+@pytest.mark.parametrize(
+    "type_, expected",
+    (
+        ("_http._tcp.LOCAL.", "_http._tcp.LOCAL."),
+        ("_http._TCP.local.", "_http._TCP.local."),
+        ("_HTTP._tcp.local.", "_HTTP._tcp.local."),
+        ("Instance._http._tcp.LOCAL.", "_http._tcp.LOCAL."),
+        ("_ntp._udp.LOCAL.", "_ntp._udp.LOCAL."),
+        ("_ntp._UDP.local.", "_ntp._UDP.local."),
+        ("Instance._ntp._udp.LOCAL.", "_ntp._udp.LOCAL."),
+    ),
+)
+def test_service_type_name_uppercase_trailer(type_, expected):
+    """RFC 1035 §2.3.3 / RFC 6762 §16 — DNS names are case-insensitive."""
+    assert nameutils.service_type_name(type_) == expected
+
+
+def test_service_type_name_uppercase_local_non_strict():
+    """Non-strict mode accepts uppercase .LOCAL. trailer without a protocol label."""
+    assert nameutils.service_type_name("Localhost.LOCAL.", strict=False) == "LOCAL."
+
+
 def test_possible_types():
     """Test possible types from name."""
     assert nameutils.possible_types(".") == set()
