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/*
* simpletlv.c: Simple TLV encoding and decoding functions
*
* Copyright (C) 2016 Red Hat, Inc.
*
* Authors: Robert Relyea <rrelyea@redhat.com>
* Jakub Jelen <jjelen@redhat.com>
*
* This library is free software; you can redistribute it and/or
* modify it under the terms of the GNU Lesser General Public
* License as published by the Free Software Foundation; either
* version 2.1 of the License, or (at your option) any later version.
*
* This library 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
* Lesser General Public License for more details.
*
* You should have received a copy of the GNU Lesser General Public
* License along with this library; if not, write to the Free Software
* Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
*/
#if HAVE_CONFIG_H
#include "config.h"
#endif
#include <stdio.h>
#include <string.h>
#include <ctype.h>
#include <assert.h>
#include <stdlib.h>
#include "internal.h"
#include "simpletlv.h"
/*
* Put a tag/length record to a file in Simple TLV based on the datalen
* content length.
*/
int
sc_simpletlv_put_tag(u8 tag, size_t datalen, u8 *out, size_t outlen, u8 **ptr)
{
u8 *p = out;
if (outlen < 2 || (outlen < 4 && datalen >= 0xff))
return SC_ERROR_INVALID_ARGUMENTS;
/* tag is just number between 0x01 and 0xFE */
if (tag == 0x00 || tag == 0xff)
return SC_ERROR_INVALID_ARGUMENTS;
*p++ = tag; /* tag is single byte */
if (datalen < 0xff) {
/* short value up to 255 */
*p++ = (u8)datalen; /* is in the second byte */
} else if (datalen < 0xffff) {
/* longer values up to 65535 */
*p++ = (u8)0xff; /* first byte is 0xff */
*p++ = (u8)datalen & 0xff;
*p++ = (u8)(datalen >> 8) & 0xff; /* LE */
} else {
/* we can't store more than two bytes in Simple TLV */
return SC_ERROR_WRONG_LENGTH;
}
if (ptr != NULL)
*ptr = p;
return SC_SUCCESS;
}
/* Read the TL file and return appropriate tag and the length of associated
* content.
*/
int
sc_simpletlv_read_tag(const u8 **buf, size_t buflen, u8 *tag_out, size_t *taglen)
{
u8 tag;
size_t left = buflen, len;
const u8 *p = *buf;
*buf = NULL;
if (left < 2) {
return SC_ERROR_INVALID_TLV_OBJECT;
}
tag = *p;
p++;
len = *p;
p++;
left -= 2;
if (len == 0xff) {
/* don't crash on bad data */
if (left < 2) {
return SC_ERROR_INVALID_TLV_OBJECT;
}
/* skip two bytes (the size) */
len = lebytes2ushort(p);
p += 2;
left -= 2;
}
*tag_out = tag;
*taglen = len;
*buf = p;
if (len > left)
return SC_ERROR_TLV_END_OF_CONTENTS;
return SC_SUCCESS;
}