113 lines
2.6 KiB
C
113 lines
2.6 KiB
C
/*
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* simpletlv.c: Simple TLV encoding and decoding functions
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*
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* Copyright (C) 2016 Red Hat, Inc.
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*
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* Authors: Robert Relyea <rrelyea@redhat.com>
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* Jakub Jelen <jjelen@redhat.com>
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*
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* This library is free software; you can redistribute it and/or
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* modify it under the terms of the GNU Lesser General Public
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* License as published by the Free Software Foundation; either
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* version 2.1 of the License, or (at your option) any later version.
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*
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* This library is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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* Lesser General Public License for more details.
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*
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* You should have received a copy of the GNU Lesser General Public
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* License along with this library; if not, write to the Free Software
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* Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
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*/
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#if HAVE_CONFIG_H
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#include "config.h"
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#endif
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#include <stdio.h>
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#include <string.h>
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#include <ctype.h>
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#include <assert.h>
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#include <stdlib.h>
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#include "internal.h"
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#include "simpletlv.h"
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/*
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* Put a tag/length record to a file in Simple TLV based on the datalen
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* content length.
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*/
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int
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sc_simpletlv_put_tag(u8 tag, size_t datalen, u8 *out, size_t outlen, u8 **ptr)
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{
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u8 *p = out;
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if (outlen < 2 || (outlen < 4 && datalen >= 0xff))
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return SC_ERROR_INVALID_ARGUMENTS;
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/* tag is just number between 0x01 and 0xFE */
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if (tag == 0x00 || tag == 0xff)
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return SC_ERROR_INVALID_ARGUMENTS;
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if (datalen > 0xffff) {
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/* we can't store more than two bytes in Simple TLV */
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return SC_ERROR_WRONG_LENGTH;
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}
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*p++ = tag; /* tag is single byte */
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if (datalen < 0xff) {
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/* short value up to 255 */
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*p++ = (u8)datalen; /* is in the second byte */
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} else {
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/* longer values up to 65535 */
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*p++ = (u8)0xff; /* first byte is 0xff */
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*p++ = (u8)datalen & 0xff;
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*p++ = (u8)(datalen >> 8) & 0xff; /* LE */
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}
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if (ptr != NULL)
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*ptr = p;
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return SC_SUCCESS;
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}
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/* Read the TL file and return appropriate tag and the length of associated
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* content.
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*/
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int
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sc_simpletlv_read_tag(const u8 **buf, size_t buflen, u8 *tag_out, size_t *taglen)
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{
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u8 tag;
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size_t left = buflen, len;
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const u8 *p = *buf;
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*buf = NULL;
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if (left < 2) {
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return SC_ERROR_INVALID_TLV_OBJECT;
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}
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tag = *p;
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p++;
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len = *p;
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p++;
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left -= 2;
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if (len == 0xff) {
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/* don't crash on bad data */
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if (left < 2) {
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return SC_ERROR_INVALID_TLV_OBJECT;
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}
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/* skip two bytes (the size) */
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len = lebytes2ushort(p);
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p += 2;
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left -= 2;
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}
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*tag_out = tag;
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*taglen = len;
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*buf = p;
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if (len > left)
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return SC_ERROR_TLV_END_OF_CONTENTS;
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return SC_SUCCESS;
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}
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