mbedtls/library/asn1parse.c
Manuel Pégourié-Gonnard a2d4e644ac Some more EC pubkey parsing refactoring
Fix a bug in pk_rsa() and pk_ec() along the way
2013-07-17 15:59:43 +02:00

344 lines
7.7 KiB
C

/*
* Generic ASN.1 parsing
*
* Copyright (C) 2006-2013, Brainspark B.V.
*
* This file is part of PolarSSL (http://www.polarssl.org)
* Lead Maintainer: Paul Bakker <polarssl_maintainer at polarssl.org>
*
* All rights reserved.
*
* This program is free software; you can redistribute it and/or modify
* it under the terms of the GNU General Public License as published by
* the Free Software Foundation; either version 2 of the License, or
* (at your option) any later version.
*
* This program 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 General Public License for more details.
*
* You should have received a copy of the GNU General Public License along
* with this program; if not, write to the Free Software Foundation, Inc.,
* 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
*/
#include "polarssl/config.h"
#if defined(POLARSSL_ASN1_PARSE_C)
#include "polarssl/asn1.h"
#if defined(POLARSSL_BIGNUM_C)
#include "polarssl/bignum.h"
#endif
#if defined(POLARSSL_MEMORY_C)
#include "polarssl/memory.h"
#else
#define polarssl_malloc malloc
#define polarssl_free free
#endif
#include <string.h>
#include <stdlib.h>
/*
* ASN.1 DER decoding routines
*/
int asn1_get_len( unsigned char **p,
const unsigned char *end,
size_t *len )
{
if( ( end - *p ) < 1 )
return( POLARSSL_ERR_ASN1_OUT_OF_DATA );
if( ( **p & 0x80 ) == 0 )
*len = *(*p)++;
else
{
switch( **p & 0x7F )
{
case 1:
if( ( end - *p ) < 2 )
return( POLARSSL_ERR_ASN1_OUT_OF_DATA );
*len = (*p)[1];
(*p) += 2;
break;
case 2:
if( ( end - *p ) < 3 )
return( POLARSSL_ERR_ASN1_OUT_OF_DATA );
*len = ( (*p)[1] << 8 ) | (*p)[2];
(*p) += 3;
break;
case 3:
if( ( end - *p ) < 4 )
return( POLARSSL_ERR_ASN1_OUT_OF_DATA );
*len = ( (*p)[1] << 16 ) | ( (*p)[2] << 8 ) | (*p)[3];
(*p) += 4;
break;
case 4:
if( ( end - *p ) < 5 )
return( POLARSSL_ERR_ASN1_OUT_OF_DATA );
*len = ( (*p)[1] << 24 ) | ( (*p)[2] << 16 ) | ( (*p)[3] << 8 ) | (*p)[4];
(*p) += 5;
break;
default:
return( POLARSSL_ERR_ASN1_INVALID_LENGTH );
}
}
if( *len > (size_t) ( end - *p ) )
return( POLARSSL_ERR_ASN1_OUT_OF_DATA );
return( 0 );
}
int asn1_get_tag( unsigned char **p,
const unsigned char *end,
size_t *len, int tag )
{
if( ( end - *p ) < 1 )
return( POLARSSL_ERR_ASN1_OUT_OF_DATA );
if( **p != tag )
return( POLARSSL_ERR_ASN1_UNEXPECTED_TAG );
(*p)++;
return( asn1_get_len( p, end, len ) );
}
int asn1_get_bool( unsigned char **p,
const unsigned char *end,
int *val )
{
int ret;
size_t len;
if( ( ret = asn1_get_tag( p, end, &len, ASN1_BOOLEAN ) ) != 0 )
return( ret );
if( len != 1 )
return( POLARSSL_ERR_ASN1_INVALID_LENGTH );
*val = ( **p != 0 ) ? 1 : 0;
(*p)++;
return( 0 );
}
int asn1_get_int( unsigned char **p,
const unsigned char *end,
int *val )
{
int ret;
size_t len;
if( ( ret = asn1_get_tag( p, end, &len, ASN1_INTEGER ) ) != 0 )
return( ret );
if( len > sizeof( int ) || ( **p & 0x80 ) != 0 )
return( POLARSSL_ERR_ASN1_INVALID_LENGTH );
*val = 0;
while( len-- > 0 )
{
*val = ( *val << 8 ) | **p;
(*p)++;
}
return( 0 );
}
#if defined(POLARSSL_BIGNUM_C)
int asn1_get_mpi( unsigned char **p,
const unsigned char *end,
mpi *X )
{
int ret;
size_t len;
if( ( ret = asn1_get_tag( p, end, &len, ASN1_INTEGER ) ) != 0 )
return( ret );
ret = mpi_read_binary( X, *p, len );
*p += len;
return( ret );
}
#endif /* POLARSSL_BIGNUM_C */
int asn1_get_bitstring( unsigned char **p, const unsigned char *end,
asn1_bitstring *bs)
{
int ret;
/* Certificate type is a single byte bitstring */
if( ( ret = asn1_get_tag( p, end, &bs->len, ASN1_BIT_STRING ) ) != 0 )
return( ret );
/* Check length, subtract one for actual bit string length */
if ( bs->len < 1 )
return( POLARSSL_ERR_ASN1_OUT_OF_DATA );
bs->len -= 1;
/* Get number of unused bits, ensure unused bits <= 7 */
bs->unused_bits = **p;
if( bs->unused_bits > 7 )
return( POLARSSL_ERR_ASN1_INVALID_LENGTH );
(*p)++;
/* Get actual bitstring */
bs->p = *p;
*p += bs->len;
if( *p != end )
return( POLARSSL_ERR_ASN1_LENGTH_MISMATCH );
return 0;
}
/*
* Get a bit string without unused bits
*/
int asn1_get_bitstring_null( unsigned char **p, const unsigned char *end,
size_t *len )
{
int ret;
if( ( ret = asn1_get_tag( p, end, len, ASN1_BIT_STRING ) ) != 0 )
return( ret );
if( --*len < 1 || *(*p)++ != 0 )
return( POLARSSL_ERR_ASN1_INVALID_DATA );
return( 0 );
}
/*
* Parses and splits an ASN.1 "SEQUENCE OF <tag>"
*/
int asn1_get_sequence_of( unsigned char **p,
const unsigned char *end,
asn1_sequence *cur,
int tag)
{
int ret;
size_t len;
asn1_buf *buf;
/* Get main sequence tag */
if( ( ret = asn1_get_tag( p, end, &len,
ASN1_CONSTRUCTED | ASN1_SEQUENCE ) ) != 0 )
return( ret );
if( *p + len != end )
return( POLARSSL_ERR_ASN1_LENGTH_MISMATCH );
while( *p < end )
{
buf = &(cur->buf);
buf->tag = **p;
if( ( ret = asn1_get_tag( p, end, &buf->len, tag ) ) != 0 )
return( ret );
buf->p = *p;
*p += buf->len;
/* Allocate and assign next pointer */
if (*p < end)
{
cur->next = (asn1_sequence *) polarssl_malloc(
sizeof( asn1_sequence ) );
if( cur->next == NULL )
return( POLARSSL_ERR_ASN1_MALLOC_FAILED );
cur = cur->next;
}
}
/* Set final sequence entry's next pointer to NULL */
cur->next = NULL;
if( *p != end )
return( POLARSSL_ERR_ASN1_LENGTH_MISMATCH );
return( 0 );
}
int asn1_get_alg( unsigned char **p,
const unsigned char *end,
asn1_buf *alg, asn1_buf *params )
{
int ret;
size_t len;
if( ( ret = asn1_get_tag( p, end, &len,
ASN1_CONSTRUCTED | ASN1_SEQUENCE ) ) != 0 )
return( ret );
end = *p + len;
alg->tag = **p;
if( ( ret = asn1_get_tag( p, end, &alg->len, ASN1_OID ) ) != 0 )
return( ret );
alg->p = *p;
*p += alg->len;
if( *p == end )
{
memset( params, 0, sizeof(asn1_buf) );
return( 0 );
}
params->tag = **p;
(*p)++;
if( ( ret = asn1_get_len( p, end, &params->len ) ) != 0 )
return( ret );
params->p = *p;
*p += params->len;
if( *p != end )
return( POLARSSL_ERR_ASN1_LENGTH_MISMATCH );
return( 0 );
}
int asn1_get_alg_null( unsigned char **p,
const unsigned char *end,
asn1_buf *alg )
{
int ret;
asn1_buf params;
memset( &params, 0, sizeof(asn1_buf) );
if( ( ret = asn1_get_alg( p, end, alg, &params ) ) != 0 )
return( ret );
if( ( params.tag != ASN1_NULL && params.tag != 0 ) || params.len != 0 )
return( POLARSSL_ERR_ASN1_INVALID_DATA );
return( 0 );
}
#endif