test: handle endpoint lookup in case of gateway route

Currently find_endpoint incorrectly tries to find physical address for
sent EID. This fails in case EID is a gatewayed endpoint because don't
have neighbors or physical address.

For gateway routes, return the gateway's physical address instead.
The gateway endpoint will then forward the message to the correct
bridged endpoint internally via looking into its bridged endpoint list.

Signed-off-by: Faizan Ali <faizana@nvidia.com>

Author: faizana-nvidia

tests/mctpenv/__init__.py

@@ -259,11 +259,23 @@ def find_endpoint(self, addr):
             route = self.lookup_route(addr.net, addr.eid)
             if route is None:
                 return None
-            iface = route.iface
-
-            neigh = self.lookup_neighbour(route.iface, addr.eid)
-            # if no neighbour, return an empty lladdr (eg mctpusb)
-            lladdr = neigh.lladdr if neigh else bytes()
+            if route.gw is not None:
+                # In case of gateway routes, we need not have neighbours
+                # for the gated endpoints, but only need to find the
+                # gateway's physical address
+				# TODO: handle recursive gateway and alternate routes
+				# for downstream endpoints
+                gw_net, gw_eid = route.gw
+                gw_route = self.lookup_route(gw_net, gw_eid)
+                if gw_route is None or gw_route.iface is None:
+                    return None
+                iface = gw_route.iface
+                neigh = self.lookup_neighbour(gw_route.iface, gw_eid)
+                lladdr = neigh.lladdr if neigh else bytes()
+            else:
+                iface = route.iface
+                neigh = self.lookup_neighbour(route.iface, addr.eid)
+                lladdr = neigh.lladdr if neigh else bytes()
 
         if iface is None or lladdr is None:
             return None