}
	if string(buf) != s {
		t.Errorf("roundtrip data mismatch: got %q, want %q", buf, s)
	}
}

// resyncConn resynchronizes the connection into a sane state.
// It assumes that everything written into c is echoed back to itself.
// It assumes that 0xff is not currently on the wire or in the read buffer.
func resyncConn(t *testing.T, c net.Conn) {
	t.Helper()
	c.SetDeadline(neverTimeout)
	errCh := make(chan error)
	go func() {