neard/src/tlv.c

/*
 *
 *  neard - Near Field Communication manager
 *
 *  Copyright (C) 2011  Intel Corporation. All rights reserved.
 *
 *  This program is free software; you can redistribute it and/or modify
 *  it under the terms of the GNU General Public License version 2 as
 *  published by the Free Software Foundation.
 *
 *  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, write to the Free Software
 *  Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA  02110-1301  USA
 *
 */

#ifdef HAVE_CONFIG_H
#include <config.h>
#endif

#include "near.h"

uint16_t near_tlv_length(uint8_t *tlv)
{
	uint16_t length;

	if (tlv[0] == TLV_NULL || tlv[0] == TLV_END)
		length = 0;
	else if (tlv[1] == 0xff)
		length = near_get_be16(tlv + 2);
	else
		length = tlv[1];

	return length;
}

uint8_t *near_tlv_next(uint8_t *tlv)
{
	uint16_t length;
	uint8_t l_length;

	length = near_tlv_length(tlv);
	if (length > 0xfe)
		l_length = 3;
	else if (length == 0)
		l_length = 0;
	else
		l_length = 1;

	/* T (1 byte) + L (1 or 3 bytes) + V */
	return tlv + 1 + l_length + length;
}

uint8_t *near_tlv_data(uint8_t *tlv)
{
	uint16_t length;
	uint8_t l_length;

	length = near_tlv_length(tlv);
	if (length > 0xfe)
		l_length = 3;
	else if (length == 0)
		l_length = 0;
	else
		l_length = 1;

	/* T (1 byte) + L (1 or 3 bytes) */
	return tlv + 1 + l_length;
}

GList *near_tlv_parse(uint8_t *tlv, size_t tlv_length)
{
	GList *records;
	uint8_t *data, t;

	DBG("");

	records = NULL;
	data = tlv;

	while (1) {
		t = tlv[0];

		DBG("tlv 0x%x", tlv[0]);

		switch (t) {
		case TLV_NDEF:
			DBG("NDEF found %d bytes long", near_tlv_length(tlv));

			records = near_ndef_parse_msg(near_tlv_data(tlv),
						near_tlv_length(tlv), NULL);

			break;
		case TLV_END:
			break;
		}

		if (t == TLV_END)
			break;

		tlv = near_tlv_next(tlv);

		if (tlv - data >= (uint16_t) tlv_length)
			break;
	}

	DBG("Done");

	return records;
}