der_put_length_and_tag
ret = der_put_length_and_tag(p + sizeof(p) - 1, sizeof(p),
der_put_length_and_tag (
ret = der_put_length_and_tag(p, len, datalen,
ret = der_put_length_and_tag(buf + buf_size - buf_len - 1,
ret = der_put_length_and_tag (ptr + ph - 1, ph, content.length,