package dialer import ( "context" "net" "syscall" ) type controlFn = func(ctx context.Context, network, address string, c syscall.RawConn) error func addControlToListenConfig(lc *net.ListenConfig, fn controlFn) { llc := *lc lc.Control = func(network, address string, c syscall.RawConn) (err error) { switch { case llc.Control != nil: if err = llc.Control(network, address, c); err != nil { return } } return fn(context.Background(), network, address, c) } } 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) } }