/*  Copyright (C) 2015 CZ.NIC, z.s.p.o. <knot-dns@labs.nic.cz>

    This program is free software: you can redistribute it and/or modify
    it under the terms of the GNU General Public License as published by
    the Free Software Foundation, either version 3 of the License, or
    (at your option) any later version.

    This program is distributed in the hope that it will be useful,
    but WITHOUT ANY WARRANTY; without even the implied warranty of
    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
    GNU General Public License for more details.

    You should have received a copy of the GNU General Public License
    along with this program.  If not, see <https://www.gnu.org/licenses/>.
 */

#include <assert.h>
#include <stdint.h>

#include "libknot/attribute.h"
#include "libknot/rrtype/naptr.h"
#include "contrib/wire_ctx.h"

_public_
int knot_naptr_header_size(const uint8_t *naptr, const uint8_t *maxp)
{
	if (!naptr || !maxp || naptr >= maxp) {
		return KNOT_EINVAL;
	}

	wire_ctx_t wire = wire_ctx_init_const(naptr, maxp - naptr);

	/* Fixed fields size (order, preference) */
	wire_ctx_skip(&wire, 2 * sizeof(uint16_t));

	/* Variable fields size (flags, services, regexp) */
	for (int i = 0; i < 3; i++) {
		uint8_t size = wire_ctx_read_u8(&wire);
		wire_ctx_skip(&wire, size);
	}

	if (wire.error != KNOT_EOK) {
		return KNOT_EMALF;
	}

	return wire_ctx_offset(&wire);
}