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82 lines
2.2 KiB
82 lines
2.2 KiB
/*
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ASN.1 routines, implementation for libdvben50221
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an implementation for the High Level Common Interface
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Copyright (C) 2004, 2005 Manu Abraham (manu@kromtek.com)
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Copyright (C) 2006 Andrew de Quincey (adq_dvb@lidskialf.net)
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This library is free software; you can redistribute it and/or modify
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it under the terms of the GNU Lesser General Public License as
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published by the Free Software Foundation; either version 2.1 of
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the License, or (at your option) any later version.
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This program 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
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GNU Lesser General Public License for more details.
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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., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
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*/
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#include <stdio.h>
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#include "asn_1.h"
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int asn_1_decode(uint16_t *length, uint8_t *asn_1_array, uint32_t asn_1_array_len)
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{
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uint8_t length_field;
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if (asn_1_array_len < 1)
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return -1;
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length_field = asn_1_array[0];
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if (length_field < 0x80) {
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// there is only one word
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*length = length_field & 0x7f;
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return 1;
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} else if (length_field == 0x81) {
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if (asn_1_array_len < 2)
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return -1;
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*length = asn_1_array[1];
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return 2;
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} else if (length_field == 0x82) {
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if (asn_1_array_len < 3)
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return -1;
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*length = (asn_1_array[1] << 8) | asn_1_array[2];
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return 3;
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}
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return -1;
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}
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int asn_1_encode(uint16_t length, uint8_t *asn_1_array, uint32_t asn_1_array_len)
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{
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if (length < 0x80) {
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if (asn_1_array_len < 1)
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return -1;
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asn_1_array[0] = length & 0x7f;
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return 1;
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} else if (length < 0x100) {
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if (asn_1_array_len < 2)
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return -1;
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asn_1_array[0] = 0x81;
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asn_1_array[1] = length;
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return 2;
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} else {
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if (asn_1_array_len < 3)
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return -1;
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asn_1_array[0] = 0x82;
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asn_1_array[1] = length >> 8;
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asn_1_array[2] = length;
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return 3;
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}
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// never reached
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}
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