Add NetConn() net.Conn support for cast

Author: nekohasekai

common/upstream.go

@@ -1,16 +1,25 @@
 package common
 
+import "net"
+
 type WithUpstream interface {
 	Upstream() any
 }
 
+type stdWithUpstreamNetConn interface {
+	NetConn() net.Conn
+}
+
 func Cast[T any](obj any) (T, bool) {
 	if c, ok := obj.(T); ok {
 		return c, true
 	}
 	if u, ok := obj.(WithUpstream); ok {
 		return Cast[T](u.Upstream())
 	}
+	if u, ok := obj.(stdWithUpstreamNetConn); ok {
+		return Cast[T](u.NetConn())
+	}
 	return DefaultValue[T](), false
 }
 
@@ -27,5 +36,8 @@ func Top(obj any) any {
 	if u, ok := obj.(WithUpstream); ok {
 		return Top(u.Upstream())
 	}
+	if u, ok := obj.(stdWithUpstreamNetConn); ok {
+		return Top(u.NetConn())
+	}
 	return obj
 }