network: drop use of legacy DHCP relay agent in sd-dhcp-server

Then, this deprecates
- BindToInterface=
- RelayTarget=
- RelayAgentCircuitId=
- RelayAgentRemoteId=
settings in [DHCPServer] section.
These are gracefully translated as new settings.

test/test-network/conf/25-agent-client-peer.network

@@ -3,13 +3,12 @@
 Name=client-peer
 
 [Network]
-Address=192.168.6.2/24
+Address=198.51.100.10/24
 DHCPServer=yes
-IPv4Forwarding=yes
 IPv6AcceptRA=no
 
 [DHCPServer]
-RelayTarget=192.168.5.1
+RelayTarget=192.0.2.1
 BindToInterface=no
 RelayAgentCircuitId=string:sample_circuit_id
 RelayAgentRemoteId=string:sample_remote_id

test/test-network/conf/25-agent-client.network

@@ -4,5 +4,4 @@ Name=client
 
 [Network]
 DHCP=yes
-IPv4Forwarding=yes
 IPv6AcceptRA=no

test/test-network/conf/25-agent-server-peer.network

@@ -3,6 +3,5 @@
 Name=server-peer
 
 [Network]
-Address=192.168.5.2/24
-IPv4Forwarding=yes
+Address=192.0.2.2/24
 IPv6AcceptRA=no

test/test-network/conf/25-agent-server.network

@@ -1,16 +0,0 @@
-# SPDX-License-Identifier: LGPL-2.1-or-later
-[Match]
-Name=server
-
-[Network]
-Address=192.168.5.1/24
-IPv4Forwarding=yes
-DHCPServer=yes
-IPv6AcceptRA=no
-
-[DHCPServer]
-BindToInterface=no
-PoolOffset=150
-PoolSize=1
-DNS=192.168.5.1
-NTP=192.168.5.1

test/test-network/conf/25-agent-veth-server.netdev

@@ -1,9 +0,0 @@
-# SPDX-License-Identifier: LGPL-2.1-or-later
-[NetDev]
-Name=server
-Kind=veth
-MACAddress=12:34:56:78:9b:bc
-
-[Peer]
-Name=server-peer
-MACAddress=12:34:56:78:9b:bd

test/test-network/systemd-networkd-tests.py

@@ -8364,11 +8364,22 @@ class NetworkdDHCPServerRelayAgentTests(unittest.TestCase, Utilities):
         tear_down_common()
 
     def test_relay_agent(self):
+        check_output('ip netns add ns-server')
+        check_output('ip link add server type veth peer server-peer')
+        check_output('ip link set server netns ns-server')
+        check_output('ip netns exec ns-server ip link set server up')
+        check_output('ip netns exec ns-server ip address add 192.0.2.1/24 dev server')
+
+        start_dnsmasq(
+            namespace='ns-server',
+            interface='server',
+            ipv4_range='198.51.100.100,198.51.100.109',
+            ipv4_router='198.51.100.10',
+        )
+
         copy_network_unit(
             '25-agent-veth-client.netdev',
-            '25-agent-veth-server.netdev',
             '25-agent-client.network',
-            '25-agent-server.network',
             '25-agent-client-peer.network',
             '25-agent-server-peer.network',
         )
@@ -8378,7 +8389,7 @@ class NetworkdDHCPServerRelayAgentTests(unittest.TestCase, Utilities):
 
         output = networkctl_status('client')
         print(output)
-        self.assertRegex(output, r'Address: 192.168.5.150 \(DHCPv4 via 192.168.5.1\)')
+        self.assertRegex(output, r'Address: 198\.51\.100\.10[0-9] \(DHCPv4 via 192\.0\.2\.1\)')
 
     def test_relay_agent_on_bridge(self):
         copy_network_unit(
@@ -8392,7 +8403,7 @@ class NetworkdDHCPServerRelayAgentTests(unittest.TestCase, Utilities):
         self.wait_online('bridge-relay:routable', 'client-peer:enslaved')
 
         # For issue #30763.
-        self.check_networkd_log('bridge-relay: DHCPv4 server: STARTED')
+        self.check_networkd_log('bridge-relay: Relaying DHCPv4 messages')
 
     def test_sd_dhcp_relay(self):
         check_output('ip netns add ns-relay')