//go:build go1.20 package dialer import ( "context" "net" "syscall" ) func addControlToDialer(d *net.Dialer, fn controlFn) { ld := *d d.ControlContext = func(ctx context.Context, network, address string, c syscall.RawConn) (err error) { switch { case ld.ControlContext != nil: if err = ld.ControlContext(ctx, network, address, c); err != nil { return } case ld.Control != nil: if err = ld.Control(network, address, c); err != nil { return } } return fn(ctx, network, address, c) } }