Refactored self._renew to None, "renew" or "rebind" to control content of DHCP request messages.

Author: BiffoBear

adafruit_wiznet5k/adafruit_wiznet5k_dhcp.py

@@ -151,7 +151,7 @@ def __init__(
         self._transaction_id = randint(1, 0x7FFFFFFF)
         self._start_time = 0.0
         self._blocking = False
-        self._renew = False
+        self._renew = None
 
         # DHCP binding configuration
         self.dhcp_server_ip = _BROADCAST_SERVER_ADDR
@@ -206,7 +206,7 @@ def _dsm_reset(self) -> None:
         self.local_ip = _UNASSIGNED_IP_ADDR
         self.subnet_mask = _UNASSIGNED_IP_ADDR
         self.dns_server_ip = _UNASSIGNED_IP_ADDR
-        self._renew = False
+        self._renew = None
         self._increment_transaction_id()
         self._start_time = time.monotonic()
 
@@ -351,7 +351,7 @@ def _process_messaging_states(self, *, message_type: int):
                         self.gateway_ip,
                         self.dns_server_ip,
                     )
-                self._renew = False
+                self._renew = None
                 self._dhcp_state = _STATE_BOUND
 
     def _handle_dhcp_message(self) -> int:
@@ -443,14 +443,14 @@ def _dhcp_state_machine(self, *, blocking: bool = False) -> None:
 
             if self._dhcp_state == _STATE_RENEWING:
                 debug_msg("FSM state is RENEWING.", self._debug)
-                self._renew = True
+                self._renew = "renew"
                 self._dhcp_connection_setup()
                 self._start_time = time.monotonic()
                 self._dhcp_state = _STATE_REQUESTING
 
             if self._dhcp_state == _STATE_REBINDING:
                 debug_msg("FSM state is REBINDING.", self._debug)
-                self._renew = True
+                self._renew = "rebind"
                 self.dhcp_server_ip = _BROADCAST_SERVER_ADDR
                 self._dhcp_connection_setup()
                 self._start_time = time.monotonic()
@@ -572,9 +572,10 @@ def option_writer(
                 offset=pointer, option_code=50, option_data=self.local_ip
             )
             # Set Server ID to chosen DHCP server IP address.
-            pointer = option_writer(
-                offset=pointer, option_code=54, option_data=self.dhcp_server_ip
-            )
+            if self._renew != "rebind":
+                pointer = option_writer(
+                    offset=pointer, option_code=54, option_data=self.dhcp_server_ip
+                )
 
         _BUFF[pointer] = 0xFF
         pointer += 1

tests/test_dhcp_helper_functions.py

@@ -184,15 +184,14 @@ def test_generate_dhcp_message_discover_with_non_defaults(
         assert wiz_dhcp._BUFF == result
 
     @pytest.mark.parametrize(
-        "mac_address, hostname, msg_type, time_elapsed, renew, \
+        "mac_address, hostname, msg_type, time_elapsed,  \
         broadcast_only, local_ip, server_ip, result",
         (
             (
                 bytes((255, 97, 36, 101, 42, 99)),
                 "helicopter.org",
                 wiz_dhcp._DHCP_REQUEST,
                 16.3,
-                False,
                 True,
                 bytes((10, 10, 10, 43)),
                 bytes((145, 66, 45, 22)),
@@ -203,7 +202,6 @@ def test_generate_dhcp_message_discover_with_non_defaults(
                 None,
                 wiz_dhcp._DHCP_REQUEST,
                 72.4,
-                False,
                 True,
                 bytes((100, 101, 102, 4)),
                 bytes((245, 166, 5, 11)),
@@ -352,7 +350,7 @@ def test_dsm_reset(mocker, mock_wiznet5k):
     assert dhcp_client.local_ip == wiz_dhcp._UNASSIGNED_IP_ADDR
     assert dhcp_client.subnet_mask == wiz_dhcp._UNASSIGNED_IP_ADDR
     assert dhcp_client.dns_server_ip == wiz_dhcp._UNASSIGNED_IP_ADDR
-    assert dhcp_client._renew is False
+    assert dhcp_client._renew is None
     assert dhcp_client._transaction_id == 4
     assert dhcp_client._start_time == time.monotonic()
 
@@ -569,7 +567,7 @@ def test_timeout_blocking_bad_message(self, mocker, mock_wiznet5k):
 
     @freeze_time("2022-5-5")
     @pytest.mark.parametrize(
-        "renew, blocking", ((True, False), (True, True), (False, False))
+        "renew, blocking", (("renew", False), ("renew", True), (None, False))
     )
     def test_no_response_non_blocking_renewing(
         self, mocker, mock_wiznet5k, renew, blocking
@@ -608,7 +606,7 @@ def test_no_response_non_blocking_renewing(
 
     @freeze_time("2022-5-5")
     @pytest.mark.parametrize(
-        "renew, blocking", ((True, False), (True, True), (False, False))
+        "renew, blocking", (("renew", False), ("renew", True), (None, False))
     )
     def test_bad_message_non_blocking_renewing(
         self, mocker, mock_wiznet5k, renew, blocking
@@ -778,8 +776,8 @@ def test_called_from_requesting_with_ack(self, mock_dhcp, lease_time):
         mock_dhcp._dhcp_state = wiz_dhcp._STATE_REQUESTING
         # Set the lease_time (zero forces a default to be used).
         mock_dhcp._lease_time = lease_time
-        # Set renew to True to confirm that an ACK sets it to False.
-        mock_dhcp._renew = True
+        # Set renew to "renew" to confirm that an ACK sets it to None.
+        mock_dhcp._renew = "renew"
         # Set a start time.
         mock_dhcp._start_time = time.monotonic()
         # Test.
@@ -788,8 +786,8 @@ def test_called_from_requesting_with_ack(self, mock_dhcp, lease_time):
         assert mock_dhcp._t1 == time.monotonic() + lease_time // 2
         assert mock_dhcp._t2 == time.monotonic() + lease_time - lease_time // 8
         assert mock_dhcp._lease_time == time.monotonic() + lease_time
-        # Check that renew is forced to False
-        assert mock_dhcp._renew is False
+        # Check that renew is forced to None
+        assert mock_dhcp._renew is None
         # FSM state should be bound.
         assert mock_dhcp._dhcp_state == wiz_dhcp._STATE_BOUND