contest: hw: add local prefix support for container tests

Construct a /96 out of the /64 we have in the DB. Put it in env.
The only real config we need is to make sure remote gets
a route installed so that it doesn't try to resolve L2 directly.

Signed-off-by: Jakub Kicinski <kuba@kernel.org>

Author: kuba-moo

contest/hw/hw_worker.py

@@ -127,6 +127,14 @@ def _ensure_addr(ifname, addr, **kwargs):
     _ip(f'addr add {addr} dev {ifname}', **kwargs)
 
 
+def _install_prefix_route(ifname, prefix, local_v6, **kwargs):
+    """
+    Install a route on remote with a nexthop so that remote doesn't try
+    to resolve the L2 for all the containers, just sends the traffic to us.
+    """
+    _ip(f'-6 route add {prefix} via {local_v6} dev {ifname}', **kwargs)
+
+
 def _collect_device_info(ifname):
     """Collect devlink device info for the test interface.
 
@@ -207,6 +215,9 @@ def setup_test_interfaces(test_dir):
             _ensure_addr(remote_ifname, env['REMOTE_V4'], **peer_kwargs)
         if env.get('REMOTE_V6'):
             _ensure_addr(remote_ifname, env['REMOTE_V6'], **peer_kwargs)
+        if env.get('LOCAL_PREFIX_V6'):
+            _install_prefix_route(remote_ifname, env['LOCAL_PREFIX_V6'],
+                                  env['LOCAL_V6'], **peer_kwargs)
 
     # Wait for peer to be reachable
     peer_ip = env.get('REMOTE_V4', '').split('/')[0]

contest/hw/lib/deployer.py

@@ -157,7 +157,12 @@ def deploy_artifacts(_config, machine_ips, reservation_id, nic_info, tree_path,
         config_lines = []
         config_lines.append(f'NETIF={nic_info.get("ifname", "")}')
         config_lines.append(f'LOCAL_V4={nic_info.get("ip4addr", "")}')
-        config_lines.append(f'LOCAL_V6={nic_info.get("ip6addr", "")}')
+
+        ipv6=nic_info.get("ip6addr", "")
+        config_lines.append(f'LOCAL_V6={ipv6}')
+        if ipv6:
+            local_pfx=ipv6.split("::")[0] + "::2:0:0/96"
+            config_lines.append(f'LOCAL_PREFIX_V6={local_pfx}')
 
         peer = nic_info.get('peer')
         if peer: