[dhcp_relay] CLI: sonic dhcp relay agent for IPv4 (sonic-net#23242)

Why I did it
Currently SONiC uses the 'isc-dhcp-relay' package to allow DHCP relay functionality on IPv4 networks.
With this PR we are adding sonic dhcp relay agent for IPv4 as described in this HLD(sonic-net/SONiC#1938).
Docker changes PR : sonic-net#22486

How I did it
Included new commands to support dhcpv4_relay in dockers/docker-dhcp-relay folder.
Corresponding cli-plugin-tests are included.

How to verify it
Configure sonic DHCPv4 agent as described in the feature HLD(sonic-net/SONiC#1938)
Test it with real client/server with IPv4 or use the sonic-mgmt suite

Co-authored-by: Prashant Srivastava <[email protected]>

Author: cshivashgit

dockers/docker-dhcp-relay/cli-plugin-tests/conftest.py

@@ -9,12 +9,57 @@ def mock_cfgdb():
         'VLAN': {
             'Vlan1000': {
                 'dhcp_servers': ['192.0.0.1']
-            }
+            },
+            'Vlan200': {},
+        },
+        'DHCPV4_RELAY': {
+            'Vlan1000': {
+                'dhcpv4_servers': ['192.0.0.1']
+            },
+            'Vlan200': {},
         },
         'DHCP_RELAY': {
             'Vlan1000': {
                 'dhcpv6_servers': ['fc02:2000::1']
             }
+        },
+        'DEVICE_METADATA': {
+            'localhost': {
+                'has_sonic_dhcpv4_relay' : "False"
+            }
+        },
+        'VRF': {
+            "default": {
+                'VRF': 'default'
+            },
+            "VrfRED": {
+                'VRF': 'VrfRED'
+            },
+            "VrfBLUE": {
+                'VRF': 'VrfBLUE'
+            }
+        },
+        'PORTCHANNEL_INTERFACE': {
+            "PortChannel5": {},
+            "PortChannel6": {},
+            "PortChannel5|192.168.0.1/31": {},
+            "PortChannel6|192.168.0.3/31": {}
+        },
+        'LOOPBACK_INTERFACE': {
+            "Loopback0": {},
+            "Loopback2": {},
+            "Loopback3": {},
+            "Loopback0|10.1.0.1/32": {},
+            "Loopback2|10.1.0.1/32": {},
+            "Loopback3|10.1.0.2/32": {}
+        },
+        'INTERFACE': {
+            "Ethernet0": {},
+            "Ethernet0|10.0.0.0/31": {},
+            "Ethernet8": {},
+            "Ethernet8|10.0.0.4/31": {},
+            "Ethernet12": {},
+            "Ethernet12|10.0.0.6/31": {},
         }
     }
 
@@ -34,6 +79,10 @@ def set_entry(table, key, data):
     def get_keys(table):
         return CONFIG[table].keys()
 
+    def get_table(table):
+        return CONFIG.get(table, {})
+
+    cfgdb.get_table = mock.Mock(side_effect=get_table)
     cfgdb.get_entry = mock.Mock(side_effect=get_entry)
     cfgdb.set_entry = mock.Mock(side_effect=set_entry)
     cfgdb.get_keys = mock.Mock(side_effect=get_keys)

dockers/docker-dhcp-relay/cli-plugin-tests/mock_config.py

@@ -42,6 +42,14 @@
                             "192.0.0.2"
                         ]
                     }
+                },
+                "DHCPV4_RELAY": {
+                    "Vlan1000": {
+                        "dhcpv4_servers": [
+                            "192.0.0.1",
+                            "192.0.0.2"
+                        ]
+                    }
                 }
             }
         }
@@ -170,5 +178,38 @@
                 }
             }
         }
+    ],
+    [
+        "ipv4_dhcp",
+        {
+            "config_db": {
+                "DHCPV4_RELAY": {
+                    "Vlan1000": {
+                        "dhcpv4_servers": [
+                            "192.0.0.1",
+                            "192.0.0.2"
+                        ],
+                        "source_interface": "Ethernet112",
+                        "link_selection": "enable",
+                        "server_vrf": "default",
+                        "vrf_selection": "enable"
+                    },
+                    "Vlan1001": {
+                        "vlanid": "1001",
+                        "dhcpv4_servers": [
+                            "192.0.0.3",
+                            "192.0.0.4"
+                        ],
+                        "agent_relay_mode": "discard",
+                        "max_hop_count": "5"
+                    }
+                },
+                'DEVICE_METADATA': {
+                    'localhost': {
+                        'has_sonic_dhcpv4_relay' : "False"
+                    }
+                }
+            }
+        }
     ]
 ]

dockers/docker-dhcp-relay/cli-plugin-tests/test_clear_dhcp_relay.py

@@ -19,17 +19,17 @@
 @pytest.fixture(scope="module")
 def patch_import_module():
     # We need to mock import module because clear_dhcp_relay.py has below import
-    # dhcp6_relay = importlib.import_module('show.plugins.dhcp-relay')
+    # dhcprelay = importlib.import_module('show.plugins.dhcp-relay')
     # When install current container, sonic-application-extension would move below file to destination in switch
     # Src: dockers/docker-dhcp-relay/cli/show/plugins/show_dhcp_relay.py
     # Dst: python-package-patch/show/plugins/dhcp-relay.py
     # The dst path doesn't exist in UT env, hence we need to mock it
-    fake_dhcp6_relay = MagicMock()
+    fake_dhcprelay = MagicMock()
 
     with patch('importlib.import_module') as mock_import:
         def side_effect(name):
             if name == 'show.plugins.dhcp-relay':
-                return fake_dhcp6_relay
+                return fake_dhcprelay
             return original_import_module(name)  # fallback
 
         mock_import.side_effect = side_effect
@@ -54,7 +54,7 @@ def test_clear_dhcp_relay_ipv6_counter(interface, patch_import_module):
     gotten_interfaces = ["Ethernet0, Ethernet1"]
 
     mock_counter = MagicMock()
-    clear_dhcp_relay.dhcp6_relay.DHCPv6_Counter.return_value = mock_counter
+    clear_dhcp_relay.dhcprelay.DHCPv6_Counter.return_value = mock_counter
     mock_counter.get_interface.return_value = gotten_interfaces
     clear_dhcp_relay.clear_dhcp_relay_ipv6_counter(interface)
     if interface:
@@ -319,3 +319,30 @@ def test_is_write_db_paused(patch_import_module):
     mock_db = MagicMock()
     clear_dhcp_relay.is_write_db_paused(mock_db, "table_name", "vlan_interface")
     mock_db.get.assert_called_once_with(ANY, "table_name|vlan_interface", "pause_write_to_db")
+
+@pytest.mark.parametrize("direction, pkt_type, interface", [
+    (None, None, None),
+    ("TX", "DISCOVER", "Vlan1000"),
+    ("RX", "OFFER", None),
+])
+def test_clear_dhcp_relay_ipv4_vlan_counter(patch_import_module, direction, pkt_type, interface):
+    clear_dhcp_relay = patch_import_module
+    mock_counter = MagicMock()
+    clear_dhcp_relay.dhcprelay.DHCPv4_Counter.return_value = mock_counter
+    clear_dhcp_relay.clear_dhcp_relay_ipv4_vlan_counter(direction, pkt_type, interface)
+    mock_counter.clear_table.assert_called_once_with(direction, pkt_type, interface)
+
+def test_dhcp4relay_clear_vlan_counters_command(patch_import_module):
+    clear_dhcp_relay = patch_import_module
+    runner = CliRunner()
+    # Patch the actual clear function to verify call
+    with patch.object(clear_dhcp_relay, "clear_dhcp_relay_ipv4_vlan_counter") as mock_clear:
+        result = runner.invoke(clear_dhcp_relay.dhcp4relay_clear.commands['dhcp4relay-vlan-counters'], ['-d', 'TX', 'Vlan1000'])
+        assert result.exit_code == 0
+
+def test_register_adds_dhcp4relay_clear_vlan_counters(patch_import_module):
+    clear_dhcp_relay = patch_import_module
+    cli = MagicMock()
+    clear_dhcp_relay.register(cli)
+    # Check that dhcp4relay_clear_vlan_counters was registered as a command
+    cli.add_command.assert_any_call(clear_dhcp_relay.dhcp4relay_clear_vlan_counters)