74 lines
2.2 KiB
C
74 lines
2.2 KiB
C
/** \file asn1_helpers.c
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*
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* \brief Helper functions for tests that manipulate ASN.1 data.
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*/
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/*
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* Copyright The Mbed TLS Contributors
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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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#include <test/helpers.h>
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#include <test/macros.h>
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#if defined(MBEDTLS_ASN1_PARSE_C)
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#include <mbedtls/asn1.h>
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int mbedtls_test_asn1_skip_integer( unsigned char **p, const unsigned char *end,
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size_t min_bits, size_t max_bits,
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int must_be_odd )
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{
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size_t len;
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size_t actual_bits;
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unsigned char msb;
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TEST_EQUAL( mbedtls_asn1_get_tag( p, end, &len,
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MBEDTLS_ASN1_INTEGER ),
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0 );
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/* Check if the retrieved length doesn't extend the actual buffer's size.
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* It is assumed here, that end >= p, which validates casting to size_t. */
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TEST_ASSERT( len <= (size_t)( end - *p) );
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/* Tolerate a slight departure from DER encoding:
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* - 0 may be represented by an empty string or a 1-byte string.
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* - The sign bit may be used as a value bit. */
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if( ( len == 1 && ( *p )[0] == 0 ) ||
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( len > 1 && ( *p )[0] == 0 && ( ( *p )[1] & 0x80 ) != 0 ) )
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{
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++( *p );
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--len;
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}
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if( min_bits == 0 && len == 0 )
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return( 1 );
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msb = ( *p )[0];
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TEST_ASSERT( msb != 0 );
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actual_bits = 8 * ( len - 1 );
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while( msb != 0 )
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{
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msb >>= 1;
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++actual_bits;
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}
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TEST_ASSERT( actual_bits >= min_bits );
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TEST_ASSERT( actual_bits <= max_bits );
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if( must_be_odd )
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TEST_ASSERT( ( ( *p )[len-1] & 1 ) != 0 );
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*p += len;
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return( 1 );
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exit:
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return( 0 );
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}
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#endif /* MBEDTLS_ASN1_PARSE_C */
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