[dhcp_relay]: sonic dhcp relay agent for IPv4

Changes for SONiC DHCPv4 Relay feature

Author: cshivashgit

config/main.py

@@ -1514,6 +1514,23 @@ def config_file_yang_validation(filename):
     return True
 
 
+def check_dhcpv4_relay_dependencies(db, object_name, object_type):
+    """Checks if to be deleted interface/VRF is used in DHCPV4_RELAY table."""
+    for vlan, data in db.get_table('DHCPV4_RELAY').items():
+        if object_type == 'interface':
+
+            source_intf = data.get('source_interface')
+            if source_intf == object_name:
+                raise ValueError(f"Interface '{object_name}' is in use by {vlan}")
+
+        elif object_type == 'vrf':
+            server_vrf = data.get('server_vrf')
+            if server_vrf == object_name:
+                raise ValueError(f"VRF '{object_name}' is in use for dhcp_relay configurations for {vlan}")
+        else:
+            raise ValueError("Unsupported object_type: {}".format(object_type))
+
+
 # This is our main entrypoint - the main 'config' command
 @click.group(cls=clicommon.AbbreviationGroup, context_settings=CONTEXT_SETTINGS)
 @click.pass_context
@@ -2674,6 +2691,12 @@ def remove_portchannel(ctx, portchannel_name):
         if len([(k, v) for k, v in db.get_table('PORTCHANNEL_MEMBER') if k == portchannel_name]) != 0: # TODO: MISSING CONSTRAINT IN YANG MODEL
             ctx.fail("Error: Portchannel {} contains members. Remove members before deleting Portchannel!".format(portchannel_name))
 
+        # Dont proceed if the port channel is used in dhcpv4_relay
+        try:
+            check_dhcpv4_relay_dependencies(db, portchannel_name, 'interface')
+        except ValueError as e:
+            ctx.fail(str(e))
+
     try:
         db.set_entry('PORTCHANNEL', portchannel_name, None)
     except JsonPatchConflict:
@@ -7205,6 +7228,12 @@ def del_vrf(ctx, vrf_name):
         syslog_vrf = syslog_data.get("vrf")
         if syslog_vrf == syslog_vrf_dev:
             ctx.fail("Failed to remove VRF device: {} is in use by SYSLOG_SERVER|{}".format(syslog_vrf, syslog_entry))
+    # Dont proceed if the vrf is used in dhcpv4_relay
+    try:
+        check_dhcpv4_relay_dependencies(config_db, vrf_name, 'vrf')
+    except ValueError as e:
+        ctx.fail(str(e))
+
     if not is_vrf_exists(config_db, vrf_name):
         ctx.fail("VRF {} does not exist!".format(vrf_name))
     elif (vrf_name == 'mgmt' or vrf_name == 'management'):
@@ -8309,6 +8338,12 @@ def del_loopback(ctx, loopback_name):
         if loopback_name not in lo_intfs:
             ctx.fail("{} does not exist".format(loopback_name))
 
+    # Dont proceed if the loopback is used in dhcpv4_relay
+    try:
+        check_dhcpv4_relay_dependencies(config_db, loopback_name, 'interface')
+    except ValueError as e:
+        ctx.fail(str(e))
+
     ips = [ k[1] for k in lo_config_db if type(k) == tuple and k[0] == loopback_name ]
     for ip in ips:
         config_db.set_entry('LOOPBACK_INTERFACE', (loopback_name, ip), None)

config/vlan.py

@@ -184,6 +184,8 @@ def del_vlan(db, vid, multiple, no_restart_dhcp_relay):
                              "First remove vxlan mapping '{}' assigned to VLAN".format(
                               vid, '|'.join(vxmap_key)))
 
+            if vlan in db.cfgdb.get_table('DHCPV4_RELAY'):
+                ctx.fail(f"{vlan} cannot be removed as it is being used in DHCPV4_RELAY table.")
             # set dhcpv4_relay table
             set_dhcp_relay_table('VLAN', config_db, vlan, None)
 

tests/config_test.py

@@ -3078,6 +3078,31 @@ def test_del_nonexistent_loopback_adhoc_validation(self):
         assert result.exit_code != 0
         assert "Loopbax1 is invalid, name should have prefix 'Loopback' and suffix '<0-999>'" in result.output
 
+    def test_del_loopback_with_dhcpv4_relay_entry(self):
+        config.ADHOC_VALIDATION = True
+        runner = CliRunner()
+        db = Db()
+        obj = {'db': db.cfgdb}
+
+        result = runner.invoke(config.config.commands["loopback"].commands["add"], ["Loopback1"], obj=obj)
+        print(result.exit_code)
+        print(result.output)
+        assert result.exit_code == 0
+        assert db.cfgdb.get_entry("LOOPBACK_INTERFACE", "Loopback1") == {}
+
+        db.cfgdb.set_entry("DHCPV4_RELAY", "Vlan100", {
+            "dhcpv4_servers": ["192.0.2.100"],
+            "source_interface": "Loopback1"
+        })
+
+        result = runner.invoke(config.config.commands["loopback"].commands["del"], ["Loopback1"], obj=obj)
+        print(result.exit_code)
+        print(result.output)
+        assert result.exit_code != 0
+        assert "Error: Interface 'Loopback1' is in use by Vlan100" in result.output
+
+        db.cfgdb.set_entry("DHCPV4_RELAY", "Vlan200", None)
+
     @patch("config.validated_config_db_connector.ValidatedConfigDBConnector.validated_set_entry", mock.Mock(return_value=True))
     @patch("validated_config_db_connector.device_info.is_yang_config_validation_enabled", mock.Mock(return_value=True))
     def test_add_loopback_yang_validation(self):

tests/portchannel_test.py

@@ -84,6 +84,25 @@ def test_delete_portchannel_with_invalid_name_adhoc_validation(self):
         assert result.exit_code != 0
         assert "Error: PortChan005 is invalid!, name should have prefix 'PortChannel' and suffix '<0-9999>'" in result.output
 
+    def test_delete_portchannel_in_use_by_dhcpv4_relay(self):
+        config.ADHOC_VALIDATION = True
+        runner = CliRunner()
+        db = Db()
+        obj = {'db': db.cfgdb}
+
+        result = runner.invoke(config.config.commands["portchannel"].commands["add"], ["PortChannel10"], obj=obj)
+
+        db.cfgdb.set_entry("DHCPV4_RELAY", "Vlan100", {"source_interface": "PortChannel10"})
+
+        result = runner.invoke(config.config.commands["portchannel"].commands["del"], ["PortChannel10"], obj=obj)
+        print(result.exit_code)
+        print(result.output)
+        assert result.exit_code != 0
+        assert f"Interface 'PortChannel10' is in use by Vlan100" in result.output
+
+        db.cfgdb.set_entry("DHCPV4_RELAY", "Vlan100", None)
+
+
     def test_add_existing_portchannel_again(self):
         runner = CliRunner()
         db = Db()

tests/vlan_test.py

@@ -1552,6 +1552,42 @@ def test_config_add_del_vlan_dhcp_relay_with_non_empty_entry(self, ip_version, m
             mock_handle_restart.assert_called_once()
             assert "Restart service dhcp_relay failed with error" not in result.output
 
+    def test_config_add_del_vlan_dhcpv4_relay_with_non_empty_entry(self, mock_restart_dhcp_relay_service):
+        runner = CliRunner()
+        db = Db()
+
+        result = runner.invoke(config.config.commands["vlan"].commands["add"], ["999"], obj=db)
+        print(result.exit_code)
+        print(result.output)
+        assert result.exit_code == 0
+        assert db.cfgdb.get_entry("VLAN", "Vlan999") == {"vlanid": "999"}
+
+        # Add a DHCPV4_RELAY entry for Vlan999
+        db.cfgdb.set_entry("DHCPV4_RELAY", "Vlan999", {
+            "dhcpv4_servers": ["192.0.2.1"],
+            "source_interface": "Ethernet4"
+        })
+
+        # Deleting Vlan999 which is being used in DHCPv4 Relay Configuration
+        with mock.patch("utilities_common.dhcp_relay_util.handle_restart_dhcp_relay_service") as mock_handle_restart:
+            result = runner.invoke(config.config.commands["vlan"].commands["del"], ["999"], obj=db)
+            print(result.exit_code)
+            print(result.output)
+
+            assert result.exit_code != 0
+            assert "Vlan999 cannot be removed as it is being used in DHCPV4_RELAY table." in result.output
+
+        # Remove DHCPV4_RELAY entry and try deletion again
+        db.cfgdb.set_entry("DHCPV4_RELAY", "Vlan999", None)
+
+        with mock.patch("utilities_common.dhcp_relay_util.handle_restart_dhcp_relay_service") as mock_handle_restart:
+            result = runner.invoke(config.config.commands["vlan"].commands["del"], ["999"], obj=db)
+            print(result.exit_code)
+            print(result.output)
+
+            assert result.exit_code == 0
+            assert "Vlan999" not in db.cfgdb.get_keys("VLAN")
+
     @pytest.mark.parametrize("ip_version", ["ipv4", "ipv6"])
     def test_config_add_del_vlan_with_dhcp_relay_not_running(self, ip_version):
         runner = CliRunner()

tests/vrf_test.py

@@ -219,6 +219,32 @@ def test_vrf_add_del(self):
         assert ('Vrf100') in db.cfgdb.get_table('VRF')
         assert result.exit_code == 0
 
+        # Add dummy VLAN and DHCP relay config using the VRF
+        vlan = "Vlan100"
+        server_ip = "192.0.2.1"
+        db.cfgdb.mod_entry("VLAN", vlan, {})
+
+        db.cfgdb.set_entry("DHCPV4_RELAY", vlan, {
+            "dhcpv4_servers": [server_ip],
+            "server_vrf": "Vrf100",
+            "link_selection": "enable",
+            "vrf_selection": "enable",
+            "server_id_override": "enable"
+        })
+
+        assert result.exit_code == 0
+
+        # Attempt to delete the VRF in use by DHCPv4_RELAY ὀ~T should failfa
+        result = runner.invoke(config.config.commands["vrf"].commands["del"], ["Vrf100"], obj=vrf_obj)
+        assert result.exit_code != 0
+        assert "VRF 'Vrf100' is in use for dhcp_relay configurations for Vlan100" in result.output
+
+        # Clean up the DHCP config to allow VRF deletion
+        db.cfgdb.set_entry("DHCPV4_RELAY", vlan, None)
+        result = runner.invoke(config.config.commands["vrf"].commands["del"], ["Vrf100"], obj=vrf_obj)
+        assert result.exit_code == 0
+        assert "Vrf100" not in db.cfgdb.get_table("VRF")
+
         result = runner.invoke(config.config.commands["vrf"].commands["add"], ["Vrf1"], obj=vrf_obj)
         assert "VRF Vrf1 already exists!" in result.output
         assert ('Vrf1') in db.cfgdb.get_table('VRF')