Set value of SCOPE to SCOPE_LINK for opt121 routes with router unspecified with DHCP

        Default behavior of the plugin is to try and install routes without
        specifying SCOPE which results in not installing certain routes that
        do not have a gateway set in the DHCP server response. If the SCOPE is
        not set to LINK (in particular for NICs in some cloud environment
        that get assigned /32 IPs to them). This change enables routes to be
        installed without the router being specified, but sets to SCOPE_LINK.

Signed-off-by: Olivier Martin <[email protected]>

Author: omartin2010

plugins/ipam/dhcp/lease.go

@@ -474,7 +474,13 @@ func (l *DHCPLease) Routes() []*types.Route {
 	opt121Routes := ack.ClasslessStaticRoute()
 	if len(opt121Routes) > 0 {
 		for _, r := range opt121Routes {
-			routes = append(routes, &types.Route{Dst: *r.Dest, GW: r.Router})
+			route := &types.Route{Dst: *r.Dest, GW: r.Router}
+			// if router is not specified, add SCOPE_LINK so routes are installed
+			if r.Router.IsUnspecified() {
+				scopeLinkValue := int(netlink.SCOPE_LINK)
+				route.Scope = &scopeLinkValue
+			}
+			routes = append(routes, route)
 		}
 		return routes
 	}