asn1write.c

00001 /*
00002  * ASN.1 buffer writing functionality
00003  *
00004  *  Copyright (C) 2006-2014, Brainspark B.V.
00005  *
00006  *  This file is part of PolarSSL (http://www.polarssl.org)
00007  *  Lead Maintainer: Paul Bakker <polarssl_maintainer at polarssl.org>
00008  *
00009  *  All rights reserved.
00010  *
00011  *  This program is free software; you can redistribute it and/or modify
00012  *  it under the terms of the GNU General Public License as published by
00013  *  the Free Software Foundation; either version 2 of the License, or
00014  *  (at your option) any later version.
00015  *
00016  *  This program is distributed in the hope that it will be useful,
00017  *  but WITHOUT ANY WARRANTY; without even the implied warranty of
00018  *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
00019  *  GNU General Public License for more details.
00020  *
00021  *  You should have received a copy of the GNU General Public License along
00022  *  with this program; if not, write to the Free Software Foundation, Inc.,
00023  *  51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
00024  */
00025 
00026 #if !defined(POLARSSL_CONFIG_FILE)
00027 #include "polarssl/config.h"
00028 #else
00029 #include POLARSSL_CONFIG_FILE
00030 #endif
00031 
00032 #if defined(POLARSSL_ASN1_WRITE_C)
00033 
00034 #include "polarssl/asn1write.h"
00035 
00036 #if defined(POLARSSL_PLATFORM_C)
00037 #include "polarssl/platform.h"
00038 #else
00039 #include <stdlib.h>
00040 #define polarssl_malloc     malloc
00041 #define polarssl_free       free
00042 #endif
00043 
00044 int asn1_write_len( unsigned char **p, unsigned char *start, size_t len )
00045 {
00046     if( len < 0x80 )
00047     {
00048         if( *p - start < 1 )
00049             return( POLARSSL_ERR_ASN1_BUF_TOO_SMALL );
00050 
00051         *--(*p) = (unsigned char) len;
00052         return( 1 );
00053     }
00054 
00055     if( len <= 0xFF )
00056     {
00057         if( *p - start < 2 )
00058             return( POLARSSL_ERR_ASN1_BUF_TOO_SMALL );
00059 
00060         *--(*p) = (unsigned char) len;
00061         *--(*p) = 0x81;
00062         return( 2 );
00063     }
00064 
00065     if( *p - start < 3 )
00066         return( POLARSSL_ERR_ASN1_BUF_TOO_SMALL );
00067 
00068     // We assume we never have lengths larger than 65535 bytes
00069     //
00070     *--(*p) = len % 256;
00071     *--(*p) = ( len / 256 ) % 256;
00072     *--(*p) = 0x82;
00073 
00074     return( 3 );
00075 }
00076 
00077 int asn1_write_tag( unsigned char **p, unsigned char *start, unsigned char tag )
00078 {
00079     if( *p - start < 1 )
00080         return( POLARSSL_ERR_ASN1_BUF_TOO_SMALL );
00081 
00082     *--(*p) = tag;
00083 
00084     return( 1 );
00085 }
00086 
00087 int asn1_write_raw_buffer( unsigned char **p, unsigned char *start,
00088                            const unsigned char *buf, size_t size )
00089 {
00090     size_t len = 0;
00091 
00092     if( *p - start < (int) size )
00093         return( POLARSSL_ERR_ASN1_BUF_TOO_SMALL );
00094 
00095     len = size;
00096     (*p) -= len;
00097     memcpy( *p, buf, len );
00098 
00099     return( (int) len );
00100 }
00101 
00102 #if defined(POLARSSL_BIGNUM_C)
00103 int asn1_write_mpi( unsigned char **p, unsigned char *start, mpi *X )
00104 {
00105     int ret;
00106     size_t len = 0;
00107 
00108     // Write the MPI
00109     //
00110     len = mpi_size( X );
00111 
00112     if( *p - start < (int) len )
00113         return( POLARSSL_ERR_ASN1_BUF_TOO_SMALL );
00114 
00115     (*p) -= len;
00116     MPI_CHK( mpi_write_binary( X, *p, len ) );
00117 
00118     // DER format assumes 2s complement for numbers, so the leftmost bit
00119     // should be 0 for positive numbers and 1 for negative numbers.
00120     //
00121     if ( X->s  ==1 && **p & 0x80 )
00122     {
00123         if( *p - start < 1 )
00124             return( POLARSSL_ERR_ASN1_BUF_TOO_SMALL );
00125 
00126         *--(*p) = 0x00;
00127         len += 1;
00128     }
00129 
00130     ASN1_CHK_ADD( len, asn1_write_len( p, start, len ) );
00131     ASN1_CHK_ADD( len, asn1_write_tag( p, start, ASN1_INTEGER ) );
00132 
00133     ret = (int) len;
00134 
00135 cleanup:
00136     return( ret );
00137 }
00138 #endif /* POLARSSL_BIGNUM_C */
00139 
00140 int asn1_write_null( unsigned char **p, unsigned char *start )
00141 {
00142     int ret;
00143     size_t len = 0;
00144 
00145     // Write NULL
00146     //
00147     ASN1_CHK_ADD( len, asn1_write_len( p, start, 0) );
00148     ASN1_CHK_ADD( len, asn1_write_tag( p, start, ASN1_NULL ) );
00149 
00150     return( (int) len );
00151 }
00152 
00153 int asn1_write_oid( unsigned char **p, unsigned char *start,
00154                     const char *oid, size_t oid_len )
00155 {
00156     int ret;
00157     size_t len = 0;
00158 
00159     ASN1_CHK_ADD( len, asn1_write_raw_buffer( p, start,
00160                                   (const unsigned char *) oid, oid_len ) );
00161     ASN1_CHK_ADD( len , asn1_write_len( p, start, len ) );
00162     ASN1_CHK_ADD( len , asn1_write_tag( p, start, ASN1_OID ) );
00163 
00164     return( (int) len );
00165 }
00166 
00167 int asn1_write_algorithm_identifier( unsigned char **p, unsigned char *start,
00168                                      const char *oid, size_t oid_len,
00169                                      size_t par_len )
00170 {
00171     int ret;
00172     size_t len = 0;
00173 
00174     if( par_len == 0 )
00175         ASN1_CHK_ADD( len, asn1_write_null( p, start ) );
00176     else
00177         len += par_len;
00178 
00179     ASN1_CHK_ADD( len, asn1_write_oid( p, start, oid, oid_len ) );
00180 
00181     ASN1_CHK_ADD( len, asn1_write_len( p, start, len ) );
00182     ASN1_CHK_ADD( len, asn1_write_tag( p, start,
00183                                        ASN1_CONSTRUCTED | ASN1_SEQUENCE ) );
00184 
00185     return( (int) len );
00186 }
00187 
00188 int asn1_write_bool( unsigned char **p, unsigned char *start, int boolean )
00189 {
00190     int ret;
00191     size_t len = 0;
00192 
00193     if( *p - start < 1 )
00194         return( POLARSSL_ERR_ASN1_BUF_TOO_SMALL );
00195 
00196     *--(*p) = (boolean) ? 1 : 0;
00197     len++;
00198 
00199     ASN1_CHK_ADD( len, asn1_write_len( p, start, len ) );
00200     ASN1_CHK_ADD( len, asn1_write_tag( p, start, ASN1_BOOLEAN ) );
00201 
00202     return( (int) len );
00203 }
00204 
00205 int asn1_write_int( unsigned char **p, unsigned char *start, int val )
00206 {
00207     int ret;
00208     size_t len = 0;
00209 
00210     // TODO negative values and values larger than 128
00211     // DER format assumes 2s complement for numbers, so the leftmost bit
00212     // should be 0 for positive numbers and 1 for negative numbers.
00213     //
00214     if( *p - start < 1 )
00215         return( POLARSSL_ERR_ASN1_BUF_TOO_SMALL );
00216 
00217     len += 1;
00218     *--(*p) = val;
00219 
00220     if ( val > 0 && **p & 0x80 )
00221     {
00222         if( *p - start < 1 )
00223             return( POLARSSL_ERR_ASN1_BUF_TOO_SMALL );
00224 
00225         *--(*p) = 0x00;
00226         len += 1;
00227     }
00228 
00229     ASN1_CHK_ADD( len, asn1_write_len( p, start, len ) );
00230     ASN1_CHK_ADD( len, asn1_write_tag( p, start, ASN1_INTEGER ) );
00231 
00232     return( (int) len );
00233 }
00234 
00235 int asn1_write_printable_string( unsigned char **p, unsigned char *start,
00236                                  const char *text, size_t text_len )
00237 {
00238     int ret;
00239     size_t len = 0;
00240 
00241     ASN1_CHK_ADD( len, asn1_write_raw_buffer( p, start,
00242                   (const unsigned char *) text, text_len ) );
00243 
00244     ASN1_CHK_ADD( len, asn1_write_len( p, start, len ) );
00245     ASN1_CHK_ADD( len, asn1_write_tag( p, start, ASN1_PRINTABLE_STRING ) );
00246 
00247     return( (int) len );
00248 }
00249 
00250 int asn1_write_ia5_string( unsigned char **p, unsigned char *start,
00251                            const char *text, size_t text_len )
00252 {
00253     int ret;
00254     size_t len = 0;
00255 
00256     ASN1_CHK_ADD( len, asn1_write_raw_buffer( p, start,
00257                   (const unsigned char *) text, text_len ) );
00258 
00259     ASN1_CHK_ADD( len, asn1_write_len( p, start, len ) );
00260     ASN1_CHK_ADD( len, asn1_write_tag( p, start, ASN1_IA5_STRING ) );
00261 
00262     return( (int) len );
00263 }
00264 
00265 int asn1_write_bitstring( unsigned char **p, unsigned char *start,
00266                           const unsigned char *buf, size_t bits )
00267 {
00268     int ret;
00269     size_t len = 0, size;
00270 
00271     size = ( bits / 8 ) + ( ( bits % 8 ) ? 1 : 0 );
00272 
00273     // Calculate byte length
00274     //
00275     if( *p - start < (int) size + 1 )
00276         return( POLARSSL_ERR_ASN1_BUF_TOO_SMALL );
00277 
00278     len = size + 1;
00279     (*p) -= size;
00280     memcpy( *p, buf, size );
00281 
00282     // Write unused bits
00283     //
00284     *--(*p) = (unsigned char) (size * 8 - bits);
00285 
00286     ASN1_CHK_ADD( len, asn1_write_len( p, start, len ) );
00287     ASN1_CHK_ADD( len, asn1_write_tag( p, start, ASN1_BIT_STRING ) );
00288 
00289     return( (int) len );
00290 }
00291 
00292 int asn1_write_octet_string( unsigned char **p, unsigned char *start,
00293                              const unsigned char *buf, size_t size )
00294 {
00295     int ret;
00296     size_t len = 0;
00297 
00298     ASN1_CHK_ADD( len, asn1_write_raw_buffer( p, start, buf, size ) );
00299 
00300     ASN1_CHK_ADD( len, asn1_write_len( p, start, len ) );
00301     ASN1_CHK_ADD( len, asn1_write_tag( p, start, ASN1_OCTET_STRING ) );
00302 
00303     return( (int) len );
00304 }
00305 
00306 asn1_named_data *asn1_store_named_data( asn1_named_data **head,
00307                                         const char *oid, size_t oid_len,
00308                                         const unsigned char *val,
00309                                         size_t val_len )
00310 {
00311     asn1_named_data *cur;
00312 
00313     if( ( cur = asn1_find_named_data( *head, oid, oid_len ) ) == NULL )
00314     {
00315         // Add new entry if not present yet based on OID
00316         //
00317         if( ( cur = polarssl_malloc( sizeof(asn1_named_data) ) ) == NULL )
00318             return( NULL );
00319 
00320         memset( cur, 0, sizeof(asn1_named_data) );
00321 
00322         cur->oid.len = oid_len;
00323         cur->oid.p = polarssl_malloc( oid_len );
00324         if( cur->oid.p == NULL )
00325         {
00326             polarssl_free( cur );
00327             return( NULL );
00328         }
00329 
00330         cur->val.len = val_len;
00331         cur->val.p = polarssl_malloc( val_len );
00332         if( cur->val.p == NULL )
00333         {
00334             polarssl_free( cur->oid.p );
00335             polarssl_free( cur );
00336             return( NULL );
00337         }
00338 
00339         memcpy( cur->oid.p, oid, oid_len );
00340 
00341         cur->next = *head;
00342         *head = cur;
00343     }
00344     else if( cur->val.len < val_len )
00345     {
00346         // Enlarge existing value buffer if needed
00347         //
00348         polarssl_free( cur->val.p );
00349         cur->val.p = NULL;
00350 
00351         cur->val.len = val_len;
00352         cur->val.p = polarssl_malloc( val_len );
00353         if( cur->val.p == NULL )
00354         {
00355             polarssl_free( cur->oid.p );
00356             polarssl_free( cur );
00357             return( NULL );
00358         }
00359     }
00360 
00361     if( val != NULL )
00362         memcpy( cur->val.p, val, val_len );
00363 
00364     return( cur );
00365 }
00366 #endif /* POLARSSL_ASN1_WRITE_C */
00367 
00368