Permit the ServiceBrowser to browse overlong types (#666)

bdraco · web-flow · commit e76c7a5b7648 · 2021-06-15T14:08:01.000-10:00
- At least one type "tivo-videostream" exists in the wild so we are permissive about what we will look for, and strict about what we will announce. Fixes #661
diff --git a/tests/test_exceptions.py b/tests/test_exceptions.py
@@ -60,7 +60,6 @@ def test_bad_service_names(self):
             '_x-._tcp.local.',
             '_22._udp.local.',
             '_2-2._tcp.local.',
-            '_1234567890-abcde._udp.local.',
             '\x00._x._udp.local.',
         )
         for name in bad_names_to_try:
diff --git a/tests/test_services.py b/tests/test_services.py
@@ -1258,3 +1258,20 @@ def test_changing_name_updates_serviceinfo_key():
     assert info_service.key == "mytesthome._homeassistant._tcp.local."
     info_service.name = "YourTestHome._homeassistant._tcp.local."
     assert info_service.key == "yourtesthome._homeassistant._tcp.local."
+
+
+def test_servicebrowser_uses_non_strict_names():
+    """Verify we can look for technically invalid names as we cannot change what others do."""
+
+    # dummy service callback
+    def on_service_state_change(zeroconf, service_type, state_change, name):
+        pass
+
+    zc = r.Zeroconf(interfaces=['127.0.0.1'])
+    browser = ServiceBrowser(zc, ["_tivo-videostream._tcp.local."], [on_service_state_change])
+    browser.cancel()
+
+    # Still fail on completely invalid
+    with pytest.raises(r.BadTypeInNameException):
+        browser = ServiceBrowser(zc, ["tivo-videostream._tcp.local."], [on_service_state_change])
+    zc.close()
diff --git a/tests/utils/test_name.py b/tests/utils/test_name.py
@@ -0,0 +1,26 @@
+#!/usr/bin/env python
+# -*- coding: utf-8 -*-
+
+
+"""Unit tests for zeroconf._utils.name."""
+
+import pytest
+
+from zeroconf._utils import name as nameutils
+from zeroconf import BadTypeInNameException
+
+
+def test_service_type_name_overlong_type():
+    """Test overlong service_type_name type."""
+    with pytest.raises(BadTypeInNameException):
+        nameutils.service_type_name("Tivo1._tivo-videostream._tcp.local.")
+    nameutils.service_type_name("Tivo1._tivo-videostream._tcp.local.", strict=False)
+
+
+def test_service_type_name_overlong_full_name():
+    """Test overlong service_type_name full name."""
+    long_name = "Tivo1Tivo1Tivo1Tivo1Tivo1Tivo1Tivo1Tivo1" * 100
+    with pytest.raises(BadTypeInNameException):
+        nameutils.service_type_name(f"{long_name}._tivo-videostream._tcp.local.")
+    with pytest.raises(BadTypeInNameException):
+        nameutils.service_type_name(f"{long_name}._tivo-videostream._tcp.local.", strict=False)
diff --git a/zeroconf/_utils/name.py b/zeroconf/_utils/name.py
@@ -74,6 +74,9 @@ def service_type_name(type_: str, *, strict: bool = True) -> str:  # pylint: dis
     :param type_: Type, SubType or service name to validate
     :return: fully qualified service name (eg: _http._tcp.local.)
     """
+    if len(type_) > 256:
+        # https://datatracker.ietf.org/doc/html/rfc6763#section-7.2
+        raise BadTypeInNameException("Full name (%s) must be > 256 bytes" % type_)
 
     if type_.endswith((_TCP_PROTOCOL_LOCAL_TRAILER, _NONTCP_PROTOCOL_LOCAL_TRAILER)):
         remaining = type_[: -len(_TCP_PROTOCOL_LOCAL_TRAILER)].split('.')
@@ -104,7 +107,8 @@ def service_type_name(type_: str, *, strict: bool = True) -> str:  # pylint: dis
 
         test_service_name = service_name[1:]
 
-        if len(test_service_name) > 15:
+        if strict and len(test_service_name) > 15:
+            # https://datatracker.ietf.org/doc/html/rfc6763#section-7.2
             raise BadTypeInNameException("Service name (%s) must be <= 15 bytes" % test_service_name)
 
         if '--' in test_service_name:

Original file line number	Diff line number	Diff line change
`@@ -60,7 +60,6 @@ def test_bad_service_names(self):`
`60`	`60`	`'_x-._tcp.local.',`
`61`	`61`	`'_22._udp.local.',`
`62`	`62`	`'_2-2._tcp.local.',`
`63`		`- '_1234567890-abcde._udp.local.',`
`64`	`63`	`'\x00._x._udp.local.',`
`65`	`64`	`)`
`66`	`65`	`for name in bad_names_to_try:`