215 lines
7.6 KiB
Python
215 lines
7.6 KiB
Python
import struct
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import trio
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import trio.testing
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import pytest
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import signal
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import sys
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from netfilterqueue import NetfilterQueue
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async def test_comms_without_queue(harness):
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await harness.send(2, b"hello", b"world")
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await harness.expect(2, b"hello", b"world")
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await harness.send(1, b"it works?")
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await harness.expect(1, b"it works?")
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async def test_queue_dropping(harness):
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async def drop(packets, msg):
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async for packet in packets:
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if packet.get_payload()[28:] == msg:
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packet.drop()
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else:
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packet.accept()
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async with trio.open_nursery() as nursery:
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async with harness.capture_packets_to(2) as p2, harness.capture_packets_to(
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1
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) as p1:
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nursery.start_soon(drop, p2, b"two")
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nursery.start_soon(drop, p1, b"one")
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await harness.send(2, b"one", b"two", b"three")
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await harness.send(1, b"one", b"two", b"three")
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await harness.expect(2, b"one", b"three")
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await harness.expect(1, b"two", b"three")
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# Once we stop capturing, everything gets through again:
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await harness.send(2, b"one", b"two", b"three")
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await harness.send(1, b"one", b"two", b"three")
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await harness.expect(2, b"one", b"two", b"three")
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await harness.expect(1, b"one", b"two", b"three")
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async def test_rewrite_reorder(harness):
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async def munge(packets):
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def set_udp_payload(p, msg):
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data = bytearray(p.get_payload())
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old_len = len(data) - 28
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if len(msg) != old_len:
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data[2:4] = struct.pack(">H", len(msg) + 28)
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data[24:26] = struct.pack(">H", len(msg) + 8)
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# Recompute checksum too
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data[10:12] = b"\x00\x00"
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words = struct.unpack(">10H", data[:20])
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cksum = sum(words)
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while cksum >> 16:
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cksum = (cksum & 0xFFFF) + (cksum >> 16)
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data[10:12] = struct.pack(">H", cksum ^ 0xFFFF)
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# Clear UDP checksum and set payload
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data[28:] = msg
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data[26:28] = b"\x00\x00"
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p.set_payload(bytes(data))
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async for packet in packets:
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payload = packet.get_payload()[28:]
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if payload == b"one":
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set_udp_payload(packet, b"numero uno")
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assert b"numero uno" == packet.get_payload()[28:]
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packet.accept()
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elif payload == b"two":
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two = packet
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elif payload == b"three":
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set_udp_payload(two, b"TWO")
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packet.accept()
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two.accept()
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else:
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packet.accept()
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async with trio.open_nursery() as nursery:
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async with harness.capture_packets_to(2) as p2:
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nursery.start_soon(munge, p2)
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await harness.send(2, b"one", b"two", b"three", b"four")
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await harness.expect(2, b"numero uno", b"three", b"TWO", b"four")
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async def test_errors(harness):
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with pytest.warns(RuntimeWarning, match="rcvbuf limit is") as record:
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async with harness.capture_packets_to(2, sock_len=2 ** 30):
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pass
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assert record[0].filename.endswith("conftest.py")
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async with harness.capture_packets_to(2, queue_num=0):
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with pytest.raises(OSError, match="Failed to create queue"):
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async with harness.capture_packets_to(2, queue_num=0):
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pass
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nfq = NetfilterQueue()
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nfq.bind(1, lambda p: None, sock_len=131072)
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with pytest.raises(RuntimeError, match="A queue is already bound"):
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nfq.bind(2, lambda p: None, sock_len=131072)
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async def test_unretained(harness):
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# Capture packets without retaining -> can't access payload
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async with harness.capture_packets_to(2, trio.MemorySendChannel.send_nowait) as chan:
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await harness.send(2, b"one", b"two")
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accept = True
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async for p in chan:
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with pytest.raises(RuntimeError, match="Payload data is no longer available"):
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p.get_payload()
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# Can still issue verdicts though
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if accept:
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p.accept()
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accept = False
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else:
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break
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with pytest.raises(RuntimeError, match="Parent queue has already been unbound"):
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p.drop()
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await harness.expect(2, b"one")
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async def test_cb_exception(harness):
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pkt = None
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def cb(channel, p):
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nonlocal pkt
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pkt = p
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raise ValueError("test")
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# Error raised within run():
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with pytest.raises(ValueError, match="test"):
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async with harness.capture_packets_to(2, cb):
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await harness.send(2, b"boom")
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with trio.fail_after(1):
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try:
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await trio.sleep_forever()
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finally:
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# At this point the error has been raised (since we were
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# cancelled) but the queue is still open. We shouldn't
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# be able to access the payload, since we didn't retain(),
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# but verdicts should otherwise work.
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with pytest.raises(RuntimeError, match="Payload data is no longer"):
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pkt.get_payload()
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pkt.accept()
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await harness.expect(2, b"boom")
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with pytest.raises(RuntimeError, match="Verdict already given for this packet"):
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pkt.drop()
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async def test_cb_exception_during_unbind(harness, capsys):
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pkt = None
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def cb(channel, p):
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nonlocal pkt
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pkt = p
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raise ValueError("test")
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if sys.version_info >= (3, 8):
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from _pytest.unraisableexception import catch_unraisable_exception
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else:
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from contextlib import contextmanager
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@contextmanager
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def catch_unraisable_exception():
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pass
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with catch_unraisable_exception() as unraise, trio.CancelScope() as cscope:
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async with harness.capture_packets_to(2, cb):
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# Cancel the task that reads from netfilter:
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cscope.cancel()
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with trio.CancelScope(shield=True):
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await trio.testing.wait_all_tasks_blocked()
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# Now actually send the packet and wait for the report to appear
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# (hopefully)
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await harness.send(2, b"boom boom")
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await trio.sleep(0.5)
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# Exiting the block calls unbind() and raises the exception in the cb.
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# It gets caught and discarded as unraisable.
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if unraise:
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assert unraise.unraisable
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assert unraise.unraisable.object == "netfilterqueue callback during unbind"
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assert unraise.unraisable.exc_type is ValueError
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assert str(unraise.unraisable.exc_value) == "test"
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if not unraise:
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assert "Exception ignored in: 'netfilterqueue callback" in capsys.readouterr().err
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with pytest.raises(RuntimeError, match="Payload data is no longer available"):
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pkt.get_payload()
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with pytest.raises(RuntimeError, match="Parent queue has already been unbound"):
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pkt.drop()
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def test_signal():
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nfq = NetfilterQueue()
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nfq.bind(1, lambda p: None, sock_len=131072)
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def raise_alarm(sig, frame):
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raise KeyboardInterrupt("brrrrrring!")
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old_handler = signal.signal(signal.SIGALRM, raise_alarm)
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old_timer = signal.setitimer(signal.ITIMER_REAL, 0.5, 0)
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try:
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with pytest.raises(KeyboardInterrupt, match="brrrrrring!") as exc_info:
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nfq.run()
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assert any("NetfilterQueue.run" in line.name for line in exc_info.traceback)
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finally:
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signal.setitimer(signal.ITIMER_REAL, *old_timer)
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signal.signal(signal.SIGALRM, old_handler)
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