466 lines
13 KiB
C
466 lines
13 KiB
C
/*
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* ASN.1 buffer writing functionality
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*
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* Copyright (C) 2006-2015, ARM Limited, All Rights Reserved
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* SPDX-License-Identifier: Apache-2.0
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*
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* Licensed under the Apache License, Version 2.0 (the "License"); you may
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* not use this file except in compliance with the License.
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* You may obtain a copy of the License at
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*
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* http://www.apache.org/licenses/LICENSE-2.0
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*
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* Unless required by applicable law or agreed to in writing, software
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* distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
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* WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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* See the License for the specific language governing permissions and
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* limitations under the License.
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*
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* This file is part of mbed TLS (https://tls.mbed.org)
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*/
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#if !defined(MBEDTLS_CONFIG_FILE)
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#include "mbedtls/config.h"
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#else
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#include MBEDTLS_CONFIG_FILE
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#endif
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#if defined(MBEDTLS_ASN1_WRITE_C)
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#include "mbedtls/asn1write.h"
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#include <string.h>
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#if defined(MBEDTLS_PLATFORM_C)
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#include "mbedtls/platform.h"
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#else
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#include <stdlib.h>
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#define mbedtls_calloc calloc
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#define mbedtls_free free
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#endif
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int mbedtls_asn1_write_len( unsigned char **p, unsigned char *start, size_t len )
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{
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if( len < 0x80 )
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{
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if( *p - start < 1 )
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return( MBEDTLS_ERR_ASN1_BUF_TOO_SMALL );
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*--(*p) = (unsigned char) len;
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return( 1 );
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}
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if( len <= 0xFF )
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{
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if( *p - start < 2 )
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return( MBEDTLS_ERR_ASN1_BUF_TOO_SMALL );
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*--(*p) = (unsigned char) len;
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*--(*p) = 0x81;
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return( 2 );
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}
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if( len <= 0xFFFF )
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{
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if( *p - start < 3 )
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return( MBEDTLS_ERR_ASN1_BUF_TOO_SMALL );
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*--(*p) = ( len ) & 0xFF;
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*--(*p) = ( len >> 8 ) & 0xFF;
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*--(*p) = 0x82;
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return( 3 );
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}
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if( len <= 0xFFFFFF )
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{
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if( *p - start < 4 )
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return( MBEDTLS_ERR_ASN1_BUF_TOO_SMALL );
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*--(*p) = ( len ) & 0xFF;
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*--(*p) = ( len >> 8 ) & 0xFF;
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*--(*p) = ( len >> 16 ) & 0xFF;
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*--(*p) = 0x83;
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return( 4 );
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}
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if( len <= 0xFFFFFFFF )
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{
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if( *p - start < 5 )
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return( MBEDTLS_ERR_ASN1_BUF_TOO_SMALL );
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*--(*p) = ( len ) & 0xFF;
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*--(*p) = ( len >> 8 ) & 0xFF;
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*--(*p) = ( len >> 16 ) & 0xFF;
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*--(*p) = ( len >> 24 ) & 0xFF;
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*--(*p) = 0x84;
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return( 5 );
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}
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return( MBEDTLS_ERR_ASN1_INVALID_LENGTH );
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}
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int mbedtls_asn1_write_tag( unsigned char **p, unsigned char *start, unsigned char tag )
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{
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if( *p - start < 1 )
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return( MBEDTLS_ERR_ASN1_BUF_TOO_SMALL );
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*--(*p) = tag;
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return( 1 );
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}
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int mbedtls_asn1_write_raw_buffer( unsigned char **p, unsigned char *start,
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const unsigned char *buf, size_t size )
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{
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size_t len = 0;
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if( *p < start || (size_t)( *p - start ) < size )
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return( MBEDTLS_ERR_ASN1_BUF_TOO_SMALL );
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len = size;
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(*p) -= len;
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memcpy( *p, buf, len );
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return( (int) len );
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}
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#if defined(MBEDTLS_BIGNUM_C)
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int mbedtls_asn1_write_mpi( unsigned char **p, unsigned char *start, const mbedtls_mpi *X )
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{
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int ret;
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size_t len = 0;
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// Write the MPI
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//
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len = mbedtls_mpi_size( X );
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if( *p < start || (size_t)( *p - start ) < len )
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return( MBEDTLS_ERR_ASN1_BUF_TOO_SMALL );
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(*p) -= len;
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MBEDTLS_MPI_CHK( mbedtls_mpi_write_binary( X, *p, len ) );
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// DER format assumes 2s complement for numbers, so the leftmost bit
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// should be 0 for positive numbers and 1 for negative numbers.
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//
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if( X->s ==1 && **p & 0x80 )
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{
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if( *p - start < 1 )
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return( MBEDTLS_ERR_ASN1_BUF_TOO_SMALL );
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*--(*p) = 0x00;
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len += 1;
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}
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MBEDTLS_ASN1_CHK_ADD( len, mbedtls_asn1_write_len( p, start, len ) );
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MBEDTLS_ASN1_CHK_ADD( len, mbedtls_asn1_write_tag( p, start, MBEDTLS_ASN1_INTEGER ) );
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ret = (int) len;
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cleanup:
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return( ret );
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}
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#endif /* MBEDTLS_BIGNUM_C */
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int mbedtls_asn1_write_null( unsigned char **p, unsigned char *start )
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{
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int ret;
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size_t len = 0;
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// Write NULL
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//
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MBEDTLS_ASN1_CHK_ADD( len, mbedtls_asn1_write_len( p, start, 0) );
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MBEDTLS_ASN1_CHK_ADD( len, mbedtls_asn1_write_tag( p, start, MBEDTLS_ASN1_NULL ) );
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return( (int) len );
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}
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int mbedtls_asn1_write_oid( unsigned char **p, unsigned char *start,
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const char *oid, size_t oid_len )
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{
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int ret;
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size_t len = 0;
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MBEDTLS_ASN1_CHK_ADD( len, mbedtls_asn1_write_raw_buffer( p, start,
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(const unsigned char *) oid, oid_len ) );
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MBEDTLS_ASN1_CHK_ADD( len , mbedtls_asn1_write_len( p, start, len ) );
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MBEDTLS_ASN1_CHK_ADD( len , mbedtls_asn1_write_tag( p, start, MBEDTLS_ASN1_OID ) );
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return( (int) len );
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}
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int mbedtls_asn1_write_algorithm_identifier( unsigned char **p, unsigned char *start,
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const char *oid, size_t oid_len,
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size_t par_len )
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{
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int ret;
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size_t len = 0;
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if( par_len == 0 )
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MBEDTLS_ASN1_CHK_ADD( len, mbedtls_asn1_write_null( p, start ) );
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else
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len += par_len;
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MBEDTLS_ASN1_CHK_ADD( len, mbedtls_asn1_write_oid( p, start, oid, oid_len ) );
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MBEDTLS_ASN1_CHK_ADD( len, mbedtls_asn1_write_len( p, start, len ) );
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MBEDTLS_ASN1_CHK_ADD( len, mbedtls_asn1_write_tag( p, start,
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MBEDTLS_ASN1_CONSTRUCTED | MBEDTLS_ASN1_SEQUENCE ) );
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return( (int) len );
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}
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int mbedtls_asn1_write_algorithm_identifier_no_params( unsigned char **p, unsigned char *start,
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const char *oid, size_t oid_len )
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{
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int ret;
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size_t len = 0;
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MBEDTLS_ASN1_CHK_ADD( len, mbedtls_asn1_write_oid( p, start, oid, oid_len ) );
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MBEDTLS_ASN1_CHK_ADD( len, mbedtls_asn1_write_len( p, start, len ) );
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MBEDTLS_ASN1_CHK_ADD( len, mbedtls_asn1_write_tag( p, start,
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MBEDTLS_ASN1_CONSTRUCTED | MBEDTLS_ASN1_SEQUENCE ) );
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return( (int) len );
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}
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int mbedtls_asn1_write_bool( unsigned char **p, unsigned char *start, int boolean )
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{
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int ret;
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size_t len = 0;
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if( *p - start < 1 )
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return( MBEDTLS_ERR_ASN1_BUF_TOO_SMALL );
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*--(*p) = (boolean) ? 255 : 0;
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len++;
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MBEDTLS_ASN1_CHK_ADD( len, mbedtls_asn1_write_len( p, start, len ) );
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MBEDTLS_ASN1_CHK_ADD( len, mbedtls_asn1_write_tag( p, start, MBEDTLS_ASN1_BOOLEAN ) );
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return( (int) len );
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}
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int mbedtls_asn1_write_int( unsigned char **p, unsigned char *start, int val )
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{
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int ret;
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size_t len = 0;
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//
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// a better world:
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//
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// the loop below terminates after at most sizeof(int)+1 iterations:
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// because of
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//
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// P >> (8 * sizeof(int)) == 0 for all P >= 0
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// and
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// N >> (8 * sizeof(int)) == -1 for all N < 0
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//
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// it is valid to encode and then right shift 8 bits until the result
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// of the shift operation is either 0 or -1.
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//
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// since ASN.1 BER/DER Integer encoding is specified as
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// two's complement, MSB of leading payload octet must be
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// 1 for negative and 0 for non-negative integers.
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//
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// 7 bit right shift of val and check for 0 or -1 as termination
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// condition ensures that a padding octet is written if the
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// MSB of the encoded octet does not match the sign of
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// the input.
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//
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// for ( ;; )
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// {
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// if( *p - start < 1 )
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// return( MBEDTLS_ERR_ASN1_BUF_TOO_SMALL );
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// *--(*p) = (unsigned char)(val & 0xFF);
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// len += 1;
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//
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// if( val >> 7 == 0 || val >> 7 == -1 )
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// break;
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//
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// val >>= 8;
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// }
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//
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// reality:
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//
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// 1) Arithmethic right shift on signed integers is
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// implementation-defined behaviour for negative integers.
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//
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// one can emulate arithmetic right shift with sign extension for
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// negative input by using a logical right shift and then set the
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// shifted-in bits to one.
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//
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// but since
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// 2) The ISO C standard allows three encoding methods for signed
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// integers: two's complement, one's complement and sign/magnitude.
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//
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// the two's complement encoding has to be ensured.
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//
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unsigned int v, fix7, fix8, cmp;
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if( val < 0 ) {
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v = ~((unsigned int) -val) + 1;
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fix7 = 0xFE << (sizeof(int) -1) * 8;
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fix8 = 0xFF << (sizeof(int) -1) * 8;
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cmp = -1;
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} else {
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v = (unsigned int)val;
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fix7 = 0;
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fix8 = 0;
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cmp = 0;
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}
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for( ;; )
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{
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if( *p - start < 1 )
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return( MBEDTLS_ERR_ASN1_BUF_TOO_SMALL );
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*--(*p) = (unsigned char) (v & 0xFF);
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len += 1;
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if( (v >> 7 | fix7) == cmp )
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break;
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v = v >> 8 | fix8;
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}
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MBEDTLS_ASN1_CHK_ADD( len, mbedtls_asn1_write_len( p, start, len ) );
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MBEDTLS_ASN1_CHK_ADD( len, mbedtls_asn1_write_tag( p, start, MBEDTLS_ASN1_INTEGER ) );
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return( (int) len );
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}
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int mbedtls_asn1_write_printable_string( unsigned char **p, unsigned char *start,
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const char *text, size_t text_len )
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{
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int ret;
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size_t len = 0;
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MBEDTLS_ASN1_CHK_ADD( len, mbedtls_asn1_write_raw_buffer( p, start,
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(const unsigned char *) text, text_len ) );
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MBEDTLS_ASN1_CHK_ADD( len, mbedtls_asn1_write_len( p, start, len ) );
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MBEDTLS_ASN1_CHK_ADD( len, mbedtls_asn1_write_tag( p, start, MBEDTLS_ASN1_PRINTABLE_STRING ) );
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return( (int) len );
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}
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int mbedtls_asn1_write_ia5_string( unsigned char **p, unsigned char *start,
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const char *text, size_t text_len )
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{
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int ret;
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size_t len = 0;
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MBEDTLS_ASN1_CHK_ADD( len, mbedtls_asn1_write_raw_buffer( p, start,
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(const unsigned char *) text, text_len ) );
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MBEDTLS_ASN1_CHK_ADD( len, mbedtls_asn1_write_len( p, start, len ) );
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MBEDTLS_ASN1_CHK_ADD( len, mbedtls_asn1_write_tag( p, start, MBEDTLS_ASN1_IA5_STRING ) );
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return( (int) len );
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}
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int mbedtls_asn1_write_bitstring( unsigned char **p, unsigned char *start,
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const unsigned char *buf, size_t bits )
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{
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int ret;
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size_t len = 0, size;
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size = ( bits / 8 ) + ( ( bits % 8 ) ? 1 : 0 );
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// Calculate byte length
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//
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if( *p < start || (size_t)( *p - start ) < size + 1 )
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return( MBEDTLS_ERR_ASN1_BUF_TOO_SMALL );
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len = size + 1;
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(*p) -= size;
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memcpy( *p, buf, size );
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// Write unused bits
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//
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*--(*p) = (unsigned char) (size * 8 - bits);
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MBEDTLS_ASN1_CHK_ADD( len, mbedtls_asn1_write_len( p, start, len ) );
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MBEDTLS_ASN1_CHK_ADD( len, mbedtls_asn1_write_tag( p, start, MBEDTLS_ASN1_BIT_STRING ) );
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return( (int) len );
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}
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int mbedtls_asn1_write_octet_string( unsigned char **p, unsigned char *start,
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const unsigned char *buf, size_t size )
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{
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int ret;
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size_t len = 0;
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MBEDTLS_ASN1_CHK_ADD( len, mbedtls_asn1_write_raw_buffer( p, start, buf, size ) );
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MBEDTLS_ASN1_CHK_ADD( len, mbedtls_asn1_write_len( p, start, len ) );
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MBEDTLS_ASN1_CHK_ADD( len, mbedtls_asn1_write_tag( p, start, MBEDTLS_ASN1_OCTET_STRING ) );
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return( (int) len );
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}
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mbedtls_asn1_named_data *mbedtls_asn1_store_named_data( mbedtls_asn1_named_data **head,
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const char *oid, size_t oid_len,
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const unsigned char *val,
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size_t val_len )
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{
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mbedtls_asn1_named_data *cur;
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if( ( cur = mbedtls_asn1_find_named_data( *head, oid, oid_len ) ) == NULL )
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{
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// Add new entry if not present yet based on OID
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//
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cur = (mbedtls_asn1_named_data*)mbedtls_calloc( 1,
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sizeof(mbedtls_asn1_named_data) );
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if( cur == NULL )
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return( NULL );
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cur->oid.len = oid_len;
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cur->oid.p = mbedtls_calloc( 1, oid_len );
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if( cur->oid.p == NULL )
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{
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mbedtls_free( cur );
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return( NULL );
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}
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memcpy( cur->oid.p, oid, oid_len );
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cur->val.len = val_len;
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cur->val.p = mbedtls_calloc( 1, val_len );
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if( cur->val.p == NULL )
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{
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mbedtls_free( cur->oid.p );
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mbedtls_free( cur );
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return( NULL );
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}
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cur->next = *head;
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*head = cur;
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}
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else if( cur->val.len < val_len )
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{
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/*
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* Enlarge existing value buffer if needed
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* Preserve old data until the allocation succeeded, to leave list in
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* a consistent state in case allocation fails.
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*/
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void *p = mbedtls_calloc( 1, val_len );
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if( p == NULL )
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return( NULL );
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mbedtls_free( cur->val.p );
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cur->val.p = p;
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cur->val.len = val_len;
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}
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if( val != NULL )
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memcpy( cur->val.p, val, val_len );
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return( cur );
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}
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#endif /* MBEDTLS_ASN1_WRITE_C */
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