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test_listener.py
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439 lines (366 loc) · 14.5 KB
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"""Unit tests for zeroconf._listener"""
from __future__ import annotations
import logging
import unittest
import unittest.mock
from unittest.mock import MagicMock, patch
import zeroconf as r
from zeroconf import (
ServiceInfo,
Zeroconf,
_engine,
_listener,
const,
current_time_millis,
)
from zeroconf._protocol import outgoing
from zeroconf._protocol.incoming import DNSIncoming
from . import QuestionHistoryWithoutSuppression
log = logging.getLogger("zeroconf")
original_logging_level = logging.NOTSET
def setup_module():
global original_logging_level
original_logging_level = log.level
log.setLevel(logging.DEBUG)
def teardown_module():
if original_logging_level != logging.NOTSET:
log.setLevel(original_logging_level)
def test_guard_against_oversized_packets():
"""Ensure we do not process oversized packets.
These packets can quickly overwhelm the system.
"""
zc = Zeroconf(interfaces=["127.0.0.1"])
generated = r.DNSOutgoing(const._FLAGS_QR_RESPONSE)
for _i in range(5000):
generated.add_answer_at_time(
r.DNSText(
"packet{i}.local.",
const._TYPE_TXT,
const._CLASS_IN | const._CLASS_UNIQUE,
500,
b"path=/~paulsm/",
),
0,
)
try:
# We are patching to generate an oversized packet
with (
patch.object(outgoing, "_MAX_MSG_ABSOLUTE", 100000),
patch.object(outgoing, "_MAX_MSG_TYPICAL", 100000),
):
over_sized_packet = generated.packets()[0]
assert len(over_sized_packet) > const._MAX_MSG_ABSOLUTE
except AttributeError:
# cannot patch with cython
zc.close()
return
generated = r.DNSOutgoing(const._FLAGS_QR_RESPONSE)
okpacket_record = r.DNSText(
"okpacket.local.",
const._TYPE_TXT,
const._CLASS_IN | const._CLASS_UNIQUE,
500,
b"path=/~paulsm/",
)
generated.add_answer_at_time(
okpacket_record,
0,
)
ok_packet = generated.packets()[0]
# We cannot test though the network interface as some operating systems
# will guard against the oversized packet and we won't see it.
listener = _listener.AsyncListener(zc)
listener.transport = unittest.mock.MagicMock()
listener.datagram_received(ok_packet, ("127.0.0.1", const._MDNS_PORT))
assert zc.cache.async_get_unique(okpacket_record) is not None
listener.datagram_received(over_sized_packet, ("127.0.0.1", const._MDNS_PORT))
assert (
zc.cache.async_get_unique(
r.DNSText(
"packet0.local.",
const._TYPE_TXT,
const._CLASS_IN | const._CLASS_UNIQUE,
500,
b"path=/~paulsm/",
)
)
is None
)
logging.getLogger("zeroconf").setLevel(logging.INFO)
listener.datagram_received(over_sized_packet, ("::1", const._MDNS_PORT, 1, 1))
assert (
zc.cache.async_get_unique(
r.DNSText(
"packet0.local.",
const._TYPE_TXT,
const._CLASS_IN | const._CLASS_UNIQUE,
500,
b"path=/~paulsm/",
)
)
is None
)
zc.close()
def test_guard_against_duplicate_packets():
"""Ensure we do not process duplicate packets.
These packets can quickly overwhelm the system.
"""
zc = Zeroconf(interfaces=["127.0.0.1"])
zc.registry.async_add(
ServiceInfo(
"_http._tcp.local.",
"Test._http._tcp.local.",
server="Test._http._tcp.local.",
port=4,
)
)
zc.question_history = QuestionHistoryWithoutSuppression()
class SubListener(_listener.AsyncListener):
def handle_query_or_defer(
self,
msg: DNSIncoming,
addr: str,
port: int,
transport: _engine._WrappedTransport,
v6_flow_scope: tuple[()] | tuple[int, int] = (),
) -> None:
"""Handle a query or defer it for later processing."""
super().handle_query_or_defer(msg, addr, port, transport, v6_flow_scope)
listener = SubListener(zc)
listener.transport = MagicMock()
query = r.DNSOutgoing(const._FLAGS_QR_QUERY, multicast=True)
question = r.DNSQuestion("x._http._tcp.local.", const._TYPE_PTR, const._CLASS_IN)
query.add_question(question)
packet_with_qm_question = query.packets()[0]
query3 = r.DNSOutgoing(const._FLAGS_QR_QUERY, multicast=True)
question3 = r.DNSQuestion("x._ay._tcp.local.", const._TYPE_PTR, const._CLASS_IN)
query3.add_question(question3)
packet_with_qm_question2 = query3.packets()[0]
query2 = r.DNSOutgoing(const._FLAGS_QR_QUERY, multicast=True)
question2 = r.DNSQuestion("x._http._tcp.local.", const._TYPE_PTR, const._CLASS_IN)
question2.unicast = True
query2.add_question(question2)
packet_with_qu_question = query2.packets()[0]
addrs = ("1.2.3.4", 43)
with patch.object(listener, "handle_query_or_defer") as _handle_query_or_defer:
start_time = current_time_millis()
listener._process_datagram_at_time(
False,
len(packet_with_qm_question),
start_time,
packet_with_qm_question,
addrs,
)
_handle_query_or_defer.assert_called_once()
_handle_query_or_defer.reset_mock()
# Now call with the same packet again and handle_query_or_defer should not fire
listener._process_datagram_at_time(
False,
len(packet_with_qm_question),
start_time,
packet_with_qm_question,
addrs,
)
_handle_query_or_defer.assert_not_called()
_handle_query_or_defer.reset_mock()
# Now walk time forward 1100 milliseconds
new_time = start_time + 1100
# Now call with the same packet again and handle_query_or_defer should fire
listener._process_datagram_at_time(
False,
len(packet_with_qm_question),
new_time,
packet_with_qm_question,
addrs,
)
_handle_query_or_defer.assert_called_once()
_handle_query_or_defer.reset_mock()
# Now call with the different packet and handle_query_or_defer should fire
listener._process_datagram_at_time(
False,
len(packet_with_qm_question2),
new_time,
packet_with_qm_question2,
addrs,
)
_handle_query_or_defer.assert_called_once()
_handle_query_or_defer.reset_mock()
# Replay the first packet — the recency window remembers more than
# just the most recent payload, so this is a duplicate.
listener._process_datagram_at_time(
False,
len(packet_with_qm_question),
new_time,
packet_with_qm_question,
addrs,
)
_handle_query_or_defer.assert_not_called()
_handle_query_or_defer.reset_mock()
# Now call with the different packet with qu question and handle_query_or_defer should fire
listener._process_datagram_at_time(
False,
len(packet_with_qu_question),
new_time,
packet_with_qu_question,
addrs,
)
_handle_query_or_defer.assert_called_once()
_handle_query_or_defer.reset_mock()
# Now call again with the same packet that has a qu question and handle_query_or_defer should fire
listener._process_datagram_at_time(
False,
len(packet_with_qu_question),
new_time,
packet_with_qu_question,
addrs,
)
_handle_query_or_defer.assert_called_once()
_handle_query_or_defer.reset_mock()
log.setLevel(logging.WARNING)
# Replay the QM packet with debug disabled — suppression must hold
# off the debug-log path too.
listener._process_datagram_at_time(
False,
len(packet_with_qm_question),
new_time,
packet_with_qm_question,
addrs,
)
_handle_query_or_defer.assert_not_called()
_handle_query_or_defer.reset_mock()
# Now call with garbage
listener._process_datagram_at_time(False, len(b"garbage"), new_time, b"garbage", addrs)
_handle_query_or_defer.assert_not_called()
_handle_query_or_defer.reset_mock()
zc.close()
def test_guard_against_alternating_duplicate_packets() -> None:
"""Alternating two distinct payloads must not bypass duplicate suppression."""
zc = Zeroconf(interfaces=["127.0.0.1"])
zc.registry.async_add(
ServiceInfo(
"_http._tcp.local.",
"Test._http._tcp.local.",
server="Test._http._tcp.local.",
port=4,
)
)
zc.question_history = QuestionHistoryWithoutSuppression()
class SubListener(_listener.AsyncListener):
def handle_query_or_defer(
self,
msg: DNSIncoming,
addr: str,
port: int,
transport: _engine._WrappedTransport,
v6_flow_scope: tuple[()] | tuple[int, int] = (),
) -> None:
super().handle_query_or_defer(msg, addr, port, transport, v6_flow_scope)
listener = SubListener(zc)
listener.transport = MagicMock()
query_a = r.DNSOutgoing(const._FLAGS_QR_QUERY, multicast=True)
query_a.add_question(r.DNSQuestion("a._http._tcp.local.", const._TYPE_PTR, const._CLASS_IN))
packet_a = query_a.packets()[0]
query_b = r.DNSOutgoing(const._FLAGS_QR_QUERY, multicast=True)
query_b.add_question(r.DNSQuestion("b._http._tcp.local.", const._TYPE_PTR, const._CLASS_IN))
packet_b = query_b.packets()[0]
assert packet_a != packet_b
addrs = ("1.2.3.4", 43)
with patch.object(listener, "handle_query_or_defer") as _handle_query_or_defer:
now = current_time_millis()
# Prime both payloads.
listener._process_datagram_at_time(False, len(packet_a), now, packet_a, addrs)
listener._process_datagram_at_time(False, len(packet_b), now, packet_b, addrs)
assert _handle_query_or_defer.call_count == 2
_handle_query_or_defer.reset_mock()
for _ in range(4):
listener._process_datagram_at_time(False, len(packet_a), now, packet_a, addrs)
listener._process_datagram_at_time(False, len(packet_b), now, packet_b, addrs)
_handle_query_or_defer.assert_not_called()
zc.close()
def test_recent_packets_window_is_bounded() -> None:
"""Distinct payloads beyond the recency window evict oldest entries."""
zc = Zeroconf(interfaces=["127.0.0.1"])
zc.registry.async_add(
ServiceInfo(
"_http._tcp.local.",
"Test._http._tcp.local.",
server="Test._http._tcp.local.",
port=4,
)
)
zc.question_history = QuestionHistoryWithoutSuppression()
class SubListener(_listener.AsyncListener):
def handle_query_or_defer(
self,
msg: DNSIncoming,
addr: str,
port: int,
transport: _engine._WrappedTransport,
v6_flow_scope: tuple[()] | tuple[int, int] = (),
) -> None:
super().handle_query_or_defer(msg, addr, port, transport, v6_flow_scope)
listener = SubListener(zc)
listener.transport = MagicMock()
addrs = ("1.2.3.4", 43)
now = current_time_millis()
packets = []
for i in range(const._RECENT_PACKETS_MAX + 4):
query = r.DNSOutgoing(const._FLAGS_QR_QUERY, multicast=True)
query.add_question(r.DNSQuestion(f"n{i}._http._tcp.local.", const._TYPE_PTR, const._CLASS_IN))
packets.append(query.packets()[0])
with patch.object(listener, "handle_query_or_defer") as _handle_query_or_defer:
for packet in packets:
listener._process_datagram_at_time(False, len(packet), now, packet, addrs)
assert _handle_query_or_defer.call_count == len(packets)
_handle_query_or_defer.reset_mock()
# The newest _RECENT_PACKETS_MAX entries are still in the
# window; replaying them must be suppressed. Checked before
# replaying the evicted ones below since that would mutate the
# window and could mask an off-by-one in eviction.
kept = packets[-const._RECENT_PACKETS_MAX :]
for packet in kept:
listener._process_datagram_at_time(False, len(packet), now, packet, addrs)
_handle_query_or_defer.assert_not_called()
# The oldest packets should have been evicted and now replay.
evicted = packets[: len(packets) - const._RECENT_PACKETS_MAX]
for packet in evicted:
listener._process_datagram_at_time(False, len(packet), now, packet, addrs)
assert _handle_query_or_defer.call_count == len(evicted)
zc.close()
def test_recent_packets_miss_with_small_now_is_not_suppressed() -> None:
"""A cache miss must not trigger suppression when `now` is below the suppression interval."""
# time.monotonic() can start near zero on freshly booted systems, so
# `now - _DUPLICATE_PACKET_SUPPRESSION_INTERVAL` is negative for the
# first second of process lifetime. A 0.0 default on the recency
# dict would let any negative `now - INTERVAL` satisfy the compare
# and suppress legitimate traffic.
zc = Zeroconf(interfaces=["127.0.0.1"])
zc.registry.async_add(
ServiceInfo(
"_http._tcp.local.",
"Test._http._tcp.local.",
server="Test._http._tcp.local.",
port=4,
)
)
zc.question_history = QuestionHistoryWithoutSuppression()
class SubListener(_listener.AsyncListener):
def handle_query_or_defer(
self,
msg: DNSIncoming,
addr: str,
port: int,
transport: _engine._WrappedTransport,
v6_flow_scope: tuple[()] | tuple[int, int] = (),
) -> None:
super().handle_query_or_defer(msg, addr, port, transport, v6_flow_scope)
listener = SubListener(zc)
listener.transport = MagicMock()
query = r.DNSOutgoing(const._FLAGS_QR_QUERY, multicast=True)
query.add_question(r.DNSQuestion("a._http._tcp.local.", const._TYPE_PTR, const._CLASS_IN))
packet = query.packets()[0]
addrs = ("1.2.3.4", 43)
with patch.object(listener, "handle_query_or_defer") as _handle_query_or_defer:
listener._process_datagram_at_time(False, len(packet), 0.0, packet, addrs)
_handle_query_or_defer.assert_called_once()
zc.close()