def test__returns_server_identifier_if_included(self):
server_ip = factory.make_ip_address(ipv6=False)
packet = factory.make_dhcp_packet(
include_server_identifier=True, server_ip=server_ip)
dhcp = DHCP(packet)
self.assertThat(dhcp.is_valid(), Equals(True))
self.assertThat(dhcp.server_identifier, Equals(IPAddress(server_ip)))
def test_is_valid_returns_false_for_truncated_option_value(self):
packet = factory.make_dhcp_packet(truncated_option_value=True)
dhcp = DHCP(packet)
self.assertThat(dhcp.is_valid(), Equals(False))
self.assertThat(
dhcp.invalid_reason, DocTestMatches("Truncated DHCP option value.")
)
def test_is_valid_returns_false_for_invalid_cookie(self):
packet = factory.make_dhcp_packet(bad_cookie=True)
dhcp = DHCP(packet)
self.assertThat(dhcp.is_valid(), Equals(False))
self.assertThat(
dhcp.invalid_reason, DocTestMatches("Invalid DHCP cookie.")
)
def test__is_valid_returns_false_for_truncated_option_length(self):
packet = factory.make_dhcp_packet(truncated_option_length=True)
dhcp = DHCP(packet)
self.assertThat(dhcp.is_valid(), Equals(False))
self.assertThat(
dhcp.invalid_reason,
DocTestMatches("Truncated length field in DHCP option."),
)
def test__server_identifier_none_if_not_included(self):
packet = factory.make_dhcp_packet(
include_server_identifier=False)
dhcp = DHCP(packet)
self.assertThat(dhcp.is_valid(), Equals(True))
self.assertThat(dhcp.server_identifier, Is(None))
def test__is_valid_return_true_for_valid_packet(self):
packet = factory.make_dhcp_packet()
dhcp = DHCP(packet)
self.assertThat(dhcp.is_valid(), Equals(True))
def test__send_requests_and_await_replies(self):
# This test is a bit large because it covers the entire functionality
# of the `send_requests_and_await_replies()` method. (It could be
# split apart into multiple tests, but the large amount of setup work
# and interdependencies makes that a maintenance burden.)
mock_socket = patch_socket(self)
mock_socket.bind = mock.MagicMock()
mock_socket.recvfrom = mock.MagicMock()
mock_socket.setsockopt = mock.MagicMock()
mock_socket.settimeout = mock.MagicMock()
# Pretend we were successful at deferring the DHCP requests.
self.patch_autospec(detect_module, "blockingCallFromThread")
# This method normally blocks for ~10 seconds, so take control of the
# monotonic clock and make sure the last call to `recvfrom()` happens
# just as we hit the reply timeout.
mock_time_monotonic = self.patch(detect_module.time.monotonic)
mock_time_monotonic.side_effect = (
# Start time (before loop starts).
10,
# First reply (truncated packet).
11,
# Second reply (not a match to our transaction).
12,
# Third reply (Matching reply with server identifier option).
13,
# First socket timeout (need to make sure the loop continues).
14,
# Second socket timeout (hey, we're done!).
10 + detect_module.REPLY_TIMEOUT,
)
mock_xid = factory.make_bytes(4)
valid_dhcp_reply = factory.make_dhcp_packet(
transaction_id=mock_xid,
include_server_identifier=True,
server_ip="127.1.1.1",
)
mock_get_xid = self.patch(detect_module.make_dhcp_transaction_id)
mock_get_xid.return_value = mock_xid
# Valid DHCP packet, but not a match because it doesn't have a
# Server Identifier option.
valid_non_match = DHCPDiscoverPacket(mac="01:02:03:04:05:06",
transaction_id=mock_xid).packet
mock_socket.recvfrom.side_effect = (
# Truncated packet, to test logging.
(b"", ("127.0.0.1", BOOTP_SERVER_PORT)),
(valid_non_match, ("127.0.0.2", BOOTP_SERVER_PORT)),
(valid_dhcp_reply, ("127.0.0.3", BOOTP_SERVER_PORT)),
socket.timeout,
socket.timeout,
)
logger = self.useFixture(TwistedLoggerFixture())
monitor = DHCPRequestMonitor("lo", Clock())
result = monitor.send_requests_and_await_replies()
self.assertThat(
mock_socket.setsockopt,
MockCallsMatch(
call(socket.SOL_SOCKET, socket.SO_REUSEADDR, 1),
call(socket.SOL_SOCKET, socket.SO_BROADCAST, 1),
),
)
self.assertThat(mock_socket.bind, MockCallsMatch(call(("", 68))))
self.assertThat(
mock_socket.settimeout,
MockCallsMatch(call(detect_module.SOCKET_TIMEOUT)),
)
self.assertThat(
mock_socket.recvfrom,
MockCallsMatch(call(2048), call(2048), call(2048), call(2048),
call(2048)),
)
# One of the response packets was truncated.
self.assertThat(
logger.output,
DocTestMatches("Invalid DHCP response...Truncated..."),
)
self.assertThat(result, HasLength(1))
# Ensure we record the fact that the reply packet came from a different
# IP address than the server claimed to be.
self.assertThat(result, Contains(DHCPServer("127.1.1.1", "127.0.0.3")))
