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Diffstat (limited to 'polarssl/src/library/asn1write.c')
| -rw-r--r-- | polarssl/src/library/asn1write.c | 241 |
1 files changed, 241 insertions, 0 deletions
diff --git a/polarssl/src/library/asn1write.c b/polarssl/src/library/asn1write.c new file mode 100644 index 0000000..e50c17c --- /dev/null +++ b/polarssl/src/library/asn1write.c @@ -0,0 +1,241 @@ +/* + * ASN.1 buffer writing functionality + * + * Copyright (C) 2006-2012, 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_WRITE_C) + +#include "polarssl/asn1write.h" + +int asn1_write_len( unsigned char **p, unsigned char *start, size_t len ) +{ + if( len < 0x80 ) + { + if( *p - start < 1 ) + return( POLARSSL_ERR_ASN1_BUF_TOO_SMALL ); + + *--(*p) = len; + return( 1 ); + } + + if( len <= 0xFF ) + { + if( *p - start < 2 ) + return( POLARSSL_ERR_ASN1_BUF_TOO_SMALL ); + + *--(*p) = len; + *--(*p) = 0x81; + return( 2 ); + } + + if( *p - start < 3 ) + return( POLARSSL_ERR_ASN1_BUF_TOO_SMALL ); + + // We assume we never have lengths larger than 65535 bytes + // + *--(*p) = len % 256; + *--(*p) = ( len / 256 ) % 256; + *--(*p) = 0x82; + + return( 3 ); +} + +int asn1_write_tag( unsigned char **p, unsigned char *start, unsigned char tag ) +{ + if( *p - start < 1 ) + return( POLARSSL_ERR_ASN1_BUF_TOO_SMALL ); + + *--(*p) = tag; + + return( 1 ); +} + +int asn1_write_mpi( unsigned char **p, unsigned char *start, mpi *X ) +{ + int ret; + size_t len = 0; + + // Write the MPI + // + len = mpi_size( X ); + + if( *p - start < (int) len ) + return( POLARSSL_ERR_ASN1_BUF_TOO_SMALL ); + + (*p) -= len; + mpi_write_binary( X, *p, len ); + + // DER format assumes 2s complement for numbers, so the leftmost bit + // should be 0 for positive numbers and 1 for negative numbers. + // + if ( X->s ==1 && **p & 0x80 ) + { + if( *p - start < 1 ) + return( POLARSSL_ERR_ASN1_BUF_TOO_SMALL ); + + *--(*p) = 0x00; + len += 1; + } + + ASN1_CHK_ADD( len, asn1_write_len( p, start, len ) ); + ASN1_CHK_ADD( len, asn1_write_tag( p, start, ASN1_INTEGER ) ); + + return( len ); +} + +int asn1_write_null( unsigned char **p, unsigned char *start ) +{ + int ret; + size_t len = 0; + + // Write NULL + // + ASN1_CHK_ADD( len, asn1_write_len( p, start, 0) ); + ASN1_CHK_ADD( len, asn1_write_tag( p, start, ASN1_NULL ) ); + + return( len ); +} + +int asn1_write_oid( unsigned char **p, unsigned char *start, char *oid ) +{ + int ret; + size_t len = 0; + + // Write OID + // + len = strlen( oid ); + + if( *p - start < (int) len ) + return( POLARSSL_ERR_ASN1_BUF_TOO_SMALL ); + + (*p) -= len; + memcpy( *p, oid, len ); + + ASN1_CHK_ADD( len , asn1_write_len( p, start, len ) ); + ASN1_CHK_ADD( len , asn1_write_tag( p, start, ASN1_OID ) ); + + return( len ); +} + +int asn1_write_algorithm_identifier( unsigned char **p, unsigned char *start, + char *algorithm_oid ) +{ + int ret; + size_t null_len = 0; + size_t oid_len = 0; + size_t len = 0; + + // Write NULL + // + ASN1_CHK_ADD( null_len, asn1_write_null( p, start ) ); + + // Write OID + // + ASN1_CHK_ADD( oid_len, asn1_write_oid( p, start, algorithm_oid ) ); + + len = oid_len + null_len; + ASN1_CHK_ADD( len, asn1_write_len( p, start, oid_len + null_len ) ); + ASN1_CHK_ADD( len, asn1_write_tag( p, start, + ASN1_CONSTRUCTED | ASN1_SEQUENCE ) ); + + return( len ); +} + +int asn1_write_int( unsigned char **p, unsigned char *start, int val ) +{ + int ret; + size_t len = 0; + + // TODO negative values and values larger than 128 + // DER format assumes 2s complement for numbers, so the leftmost bit + // should be 0 for positive numbers and 1 for negative numbers. + // + if( *p - start < 1 ) + return( POLARSSL_ERR_ASN1_BUF_TOO_SMALL ); + + len += 1; + *--(*p) = val; + + if ( val > 0 && **p & 0x80 ) + { + if( *p - start < 1 ) + return( POLARSSL_ERR_ASN1_BUF_TOO_SMALL ); + + *--(*p) = 0x00; + len += 1; + } + + ASN1_CHK_ADD( len, asn1_write_len( p, start, len ) ); + ASN1_CHK_ADD( len, asn1_write_tag( p, start, ASN1_INTEGER ) ); + + return( len ); +} + +int asn1_write_printable_string( unsigned char **p, unsigned char *start, + char *text ) +{ + int ret; + size_t len = 0; + + // Write string + // + len = strlen( text ); + + if( *p - start < (int) len ) + return( POLARSSL_ERR_ASN1_BUF_TOO_SMALL ); + + (*p) -= len; + memcpy( *p, text, len ); + + ASN1_CHK_ADD( len, asn1_write_len( p, start, len ) ); + ASN1_CHK_ADD( len, asn1_write_tag( p, start, ASN1_PRINTABLE_STRING ) ); + + return( len ); +} + +int asn1_write_ia5_string( unsigned char **p, unsigned char *start, + char *text ) +{ + int ret; + size_t len = 0; + + // Write string + // + len = strlen( text ); + + if( *p - start < (int) len ) + return( POLARSSL_ERR_ASN1_BUF_TOO_SMALL ); + + (*p) -= len; + memcpy( *p, text, len ); + + ASN1_CHK_ADD( len, asn1_write_len( p, start, len ) ); + ASN1_CHK_ADD( len, asn1_write_tag( p, start, ASN1_IA5_STRING ) ); + + return( len ); +} + + +#endif |