new: keeping track of interface index

net/endpoint.go

@@ -11,6 +11,7 @@ import (
 
 type OnHostResolvedCallback func(e *Endpoint)
 type Endpoint struct {
+	Index            int                    `json:"-"`
 	IP               net.IP                 `json:"-"`
 	Net              *net.IPNet             `json:"-"`
 	IPv6             net.IP                 `json:"-"`

net/net.go

@@ -94,6 +94,7 @@ func FindInterface(name string) (*Endpoint, error) {
 				if len(e.HW) == 0 {
 					return nil, fmt.Errorf("Could not detect interface hardware address.")
 				}
+				e.Index = iface.Index
 				return e, nil
 			}
 		}