python-zeroconf · bdraco · Jun 19, 2021 · Jun 19, 2021
diff --git a/tests/test_handlers.py b/tests/test_handlers.py
@@ -4,6 +4,7 @@
 
 """ Unit tests for zeroconf._handlers """
 
+import asyncio
 import logging
 import pytest
 import socket
@@ -834,3 +835,83 @@ async def test_qu_response_only_sends_additionals_if_sends_answer():
     # unregister
     zc.registry.remove(info)
     await aiozc.async_close()
+
+
+# This test uses asyncio because it needs to access the cache directly
+# which is not threadsafe
+@pytest.mark.asyncio
+async def test_cache_flush_bit():
+    """Test that the cache flush bit sets the TTL to one for matching records."""
+    # instantiate a zeroconf instance
+    aiozc = AsyncZeroconf(interfaces=['127.0.0.1'])
+    zc = aiozc.zeroconf
+
+    type_ = "_cacheflush._tcp.local."
+    name = "knownname"
+    registration_name = "%s.%s" % (name, type_)
+    desc = {'path': '/~paulsm/'}
+    server_name = "server-uu1.local."
+    info = ServiceInfo(
+        type_, registration_name, 80, 0, 0, desc, server_name, addresses=[socket.inet_aton("10.0.1.2")]
+    )
+    a_record = info.dns_addresses()[0]
+    zc.cache.async_add_records([info.dns_pointer(), a_record, info.dns_text(), info.dns_service()])
+
+    info.addresses = [socket.inet_aton("10.0.1.5"), socket.inet_aton("10.0.1.6")]
+    new_records = info.dns_addresses()
+    for new_record in new_records:
+        assert new_record.unique is True
+
+    original_a_record = zc.cache.get(a_record)
+    # Do the run within 1s to verify the original record is not going to be expired
+    out = r.DNSOutgoing(const._FLAGS_QR_RESPONSE | const._FLAGS_AA, multicast=True)
+    for answer in new_records:
+        out.add_answer_at_time(answer, 0)
+    for packet in out.packets():
+        zc.record_manager.async_updates_from_response(r.DNSIncoming(packet))
+    assert zc.cache.get(a_record) is original_a_record
+    assert original_a_record.ttl != 1
+    for record in new_records:
+        assert zc.cache.get(record) is not None
+
+    original_a_record.created = current_time_millis() - 1001
+
+    # Do the run within 1s to verify the original record is not going to be expired
+    out = r.DNSOutgoing(const._FLAGS_QR_RESPONSE | const._FLAGS_AA, multicast=True)
+    for answer in new_records:
+        out.add_answer_at_time(answer, 0)
+    for packet in out.packets():
+        zc.record_manager.async_updates_from_response(r.DNSIncoming(packet))
+    assert original_a_record.ttl == 1
+    for record in new_records:
+        assert zc.cache.get(record) is not None
+
+    cached_records = [zc.cache.get(record) for record in new_records]
+    for record in cached_records:
+        record.created = current_time_millis() - 1001
+
+    fresh_address = socket.inet_aton("4.4.4.4")
+    info.addresses = [fresh_address]
+    # Do the run within 1s to verify the two new records get marked as expired
+    out = r.DNSOutgoing(const._FLAGS_QR_RESPONSE | const._FLAGS_AA, multicast=True)
+    for answer in info.dns_addresses():
+        out.add_answer_at_time(answer, 0)
+    for packet in out.packets():
+        zc.record_manager.async_updates_from_response(r.DNSIncoming(packet))
+    for record in cached_records:
+        assert record.ttl == 1
+
+    for entry in zc.cache.get_all_by_details(server_name, const._TYPE_A, const._CLASS_IN):
+        if entry.address == fresh_address:
+            assert entry.ttl > 1
+        else:
+            assert entry.ttl == 1
+
+    # Wait for the ttl 1 records to expire
+    await asyncio.sleep(1.01)
+
+    loaded_info = r.ServiceInfo(type_, registration_name)
+    loaded_info.load_from_cache(zc)
+    assert loaded_info.addresses == info.addresses
+
+    await aiozc.async_close()