asn1write.c

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