2 * ASN.1 buffer writing functionality
4 * Copyright (C) 2006-2015, ARM Limited, All Rights Reserved
5 * SPDX-License-Identifier: Apache-2.0
7 * Licensed under the Apache License, Version 2.0 (the "License"); you may
8 * not use this file except in compliance with the License.
9 * You may obtain a copy of the License at
11 * http://www.apache.org/licenses/LICENSE-2.0
13 * Unless required by applicable law or agreed to in writing, software
14 * distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
15 * WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
16 * See the License for the specific language governing permissions and
17 * limitations under the License.
19 * This file is part of mbed TLS (https://tls.mbed.org)
22 #if !defined(MBEDTLS_CONFIG_FILE)
23 #include "mbedtls/config.h"
25 #include MBEDTLS_CONFIG_FILE
28 #if defined(MBEDTLS_ASN1_WRITE_C)
30 #include "mbedtls/asn1write.h"
34 #if defined(MBEDTLS_PLATFORM_C)
35 #include "mbedtls/platform.h"
38 #define mbedtls_calloc calloc
39 #define mbedtls_free free
42 int mbedtls_asn1_write_len( unsigned char **p, unsigned char *start, size_t len )
47 return( MBEDTLS_ERR_ASN1_BUF_TOO_SMALL );
49 *--(*p) = (unsigned char) len;
56 return( MBEDTLS_ERR_ASN1_BUF_TOO_SMALL );
58 *--(*p) = (unsigned char) len;
66 return( MBEDTLS_ERR_ASN1_BUF_TOO_SMALL );
68 *--(*p) = ( len ) & 0xFF;
69 *--(*p) = ( len >> 8 ) & 0xFF;
77 return( MBEDTLS_ERR_ASN1_BUF_TOO_SMALL );
79 *--(*p) = ( len ) & 0xFF;
80 *--(*p) = ( len >> 8 ) & 0xFF;
81 *--(*p) = ( len >> 16 ) & 0xFF;
86 #if SIZE_MAX > 0xFFFFFFFF
87 if( len <= 0xFFFFFFFF )
91 return( MBEDTLS_ERR_ASN1_BUF_TOO_SMALL );
93 *--(*p) = ( len ) & 0xFF;
94 *--(*p) = ( len >> 8 ) & 0xFF;
95 *--(*p) = ( len >> 16 ) & 0xFF;
96 *--(*p) = ( len >> 24 ) & 0xFF;
101 #if SIZE_MAX > 0xFFFFFFFF
102 return( MBEDTLS_ERR_ASN1_INVALID_LENGTH );
106 int mbedtls_asn1_write_tag( unsigned char **p, unsigned char *start, unsigned char tag )
109 return( MBEDTLS_ERR_ASN1_BUF_TOO_SMALL );
116 int mbedtls_asn1_write_raw_buffer( unsigned char **p, unsigned char *start,
117 const unsigned char *buf, size_t size )
121 if( *p < start || (size_t)( *p - start ) < size )
122 return( MBEDTLS_ERR_ASN1_BUF_TOO_SMALL );
126 memcpy( *p, buf, len );
131 #if defined(MBEDTLS_BIGNUM_C)
132 int mbedtls_asn1_write_mpi( unsigned char **p, unsigned char *start, const mbedtls_mpi *X )
139 len = mbedtls_mpi_size( X );
141 if( *p < start || (size_t)( *p - start ) < len )
142 return( MBEDTLS_ERR_ASN1_BUF_TOO_SMALL );
145 MBEDTLS_MPI_CHK( mbedtls_mpi_write_binary( X, *p, len ) );
147 // DER format assumes 2s complement for numbers, so the leftmost bit
148 // should be 0 for positive numbers and 1 for negative numbers.
150 if( X->s ==1 && **p & 0x80 )
153 return( MBEDTLS_ERR_ASN1_BUF_TOO_SMALL );
159 MBEDTLS_ASN1_CHK_ADD( len, mbedtls_asn1_write_len( p, start, len ) );
160 MBEDTLS_ASN1_CHK_ADD( len, mbedtls_asn1_write_tag( p, start, MBEDTLS_ASN1_INTEGER ) );
167 #endif /* MBEDTLS_BIGNUM_C */
169 int mbedtls_asn1_write_null( unsigned char **p, unsigned char *start )
176 MBEDTLS_ASN1_CHK_ADD( len, mbedtls_asn1_write_len( p, start, 0) );
177 MBEDTLS_ASN1_CHK_ADD( len, mbedtls_asn1_write_tag( p, start, MBEDTLS_ASN1_NULL ) );
182 int mbedtls_asn1_write_oid( unsigned char **p, unsigned char *start,
183 const char *oid, size_t oid_len )
188 MBEDTLS_ASN1_CHK_ADD( len, mbedtls_asn1_write_raw_buffer( p, start,
189 (const unsigned char *) oid, oid_len ) );
190 MBEDTLS_ASN1_CHK_ADD( len , mbedtls_asn1_write_len( p, start, len ) );
191 MBEDTLS_ASN1_CHK_ADD( len , mbedtls_asn1_write_tag( p, start, MBEDTLS_ASN1_OID ) );
196 int mbedtls_asn1_write_algorithm_identifier( unsigned char **p, unsigned char *start,
197 const char *oid, size_t oid_len,
204 MBEDTLS_ASN1_CHK_ADD( len, mbedtls_asn1_write_null( p, start ) );
208 MBEDTLS_ASN1_CHK_ADD( len, mbedtls_asn1_write_oid( p, start, oid, oid_len ) );
210 MBEDTLS_ASN1_CHK_ADD( len, mbedtls_asn1_write_len( p, start, len ) );
211 MBEDTLS_ASN1_CHK_ADD( len, mbedtls_asn1_write_tag( p, start,
212 MBEDTLS_ASN1_CONSTRUCTED | MBEDTLS_ASN1_SEQUENCE ) );
217 int mbedtls_asn1_write_bool( unsigned char **p, unsigned char *start, int boolean )
223 return( MBEDTLS_ERR_ASN1_BUF_TOO_SMALL );
225 *--(*p) = (boolean) ? 255 : 0;
228 MBEDTLS_ASN1_CHK_ADD( len, mbedtls_asn1_write_len( p, start, len ) );
229 MBEDTLS_ASN1_CHK_ADD( len, mbedtls_asn1_write_tag( p, start, MBEDTLS_ASN1_BOOLEAN ) );
234 int mbedtls_asn1_write_int( unsigned char **p, unsigned char *start, int val )
240 return( MBEDTLS_ERR_ASN1_BUF_TOO_SMALL );
245 if( val > 0 && **p & 0x80 )
248 return( MBEDTLS_ERR_ASN1_BUF_TOO_SMALL );
254 MBEDTLS_ASN1_CHK_ADD( len, mbedtls_asn1_write_len( p, start, len ) );
255 MBEDTLS_ASN1_CHK_ADD( len, mbedtls_asn1_write_tag( p, start, MBEDTLS_ASN1_INTEGER ) );
260 int mbedtls_asn1_write_tagged_string( unsigned char **p, unsigned char *start, int tag,
261 const char *text, size_t text_len )
266 MBEDTLS_ASN1_CHK_ADD( len, mbedtls_asn1_write_raw_buffer( p, start,
267 (const unsigned char *) text, text_len ) );
269 MBEDTLS_ASN1_CHK_ADD( len, mbedtls_asn1_write_len( p, start, len ) );
270 MBEDTLS_ASN1_CHK_ADD( len, mbedtls_asn1_write_tag( p, start, tag ) );
275 int mbedtls_asn1_write_utf8_string( unsigned char **p, unsigned char *start,
276 const char *text, size_t text_len )
278 return( mbedtls_asn1_write_tagged_string(p, start, MBEDTLS_ASN1_UTF8_STRING, text, text_len) );
281 int mbedtls_asn1_write_printable_string( unsigned char **p, unsigned char *start,
282 const char *text, size_t text_len )
284 return( mbedtls_asn1_write_tagged_string(p, start, MBEDTLS_ASN1_PRINTABLE_STRING, text, text_len) );
287 int mbedtls_asn1_write_ia5_string( unsigned char **p, unsigned char *start,
288 const char *text, size_t text_len )
290 return( mbedtls_asn1_write_tagged_string(p, start, MBEDTLS_ASN1_IA5_STRING, text, text_len) );
293 int mbedtls_asn1_write_named_bitstring( unsigned char **p,
294 unsigned char *start,
295 const unsigned char *buf,
298 size_t unused_bits, byte_len;
299 const unsigned char *cur_byte;
300 unsigned char cur_byte_shifted;
303 byte_len = ( bits + 7 ) / 8;
304 unused_bits = ( byte_len * 8 ) - bits;
307 * Named bitstrings require that trailing 0s are excluded in the encoding
308 * of the bitstring. Trailing 0s are considered part of the 'unused' bits
309 * when encoding this value in the first content octet
313 cur_byte = buf + byte_len - 1;
314 cur_byte_shifted = *cur_byte >> unused_bits;
318 bit = cur_byte_shifted & 0x1;
319 cur_byte_shifted >>= 1;
329 cur_byte_shifted = *--cur_byte;
333 return( mbedtls_asn1_write_bitstring( p, start, buf, bits ) );
336 int mbedtls_asn1_write_bitstring( unsigned char **p, unsigned char *start,
337 const unsigned char *buf, size_t bits )
341 size_t unused_bits, byte_len;
343 byte_len = ( bits + 7 ) / 8;
344 unused_bits = ( byte_len * 8 ) - bits;
346 if( *p < start || (size_t)( *p - start ) < byte_len + 1 )
347 return( MBEDTLS_ERR_ASN1_BUF_TOO_SMALL );
351 /* Write the bitstring. Ensure the unused bits are zeroed */
355 *--( *p ) = buf[byte_len] & ~( ( 0x1 << unused_bits ) - 1 );
357 memcpy( *p, buf, byte_len );
360 /* Write unused bits */
361 *--( *p ) = (unsigned char)unused_bits;
363 MBEDTLS_ASN1_CHK_ADD( len, mbedtls_asn1_write_len( p, start, len ) );
364 MBEDTLS_ASN1_CHK_ADD( len, mbedtls_asn1_write_tag( p, start, MBEDTLS_ASN1_BIT_STRING ) );
369 int mbedtls_asn1_write_octet_string( unsigned char **p, unsigned char *start,
370 const unsigned char *buf, size_t size )
375 MBEDTLS_ASN1_CHK_ADD( len, mbedtls_asn1_write_raw_buffer( p, start, buf, size ) );
377 MBEDTLS_ASN1_CHK_ADD( len, mbedtls_asn1_write_len( p, start, len ) );
378 MBEDTLS_ASN1_CHK_ADD( len, mbedtls_asn1_write_tag( p, start, MBEDTLS_ASN1_OCTET_STRING ) );
384 /* This is a copy of the ASN.1 parsing function mbedtls_asn1_find_named_data(),
385 * which is replicated to avoid a dependency ASN1_WRITE_C on ASN1_PARSE_C. */
386 static mbedtls_asn1_named_data *asn1_find_named_data(
387 mbedtls_asn1_named_data *list,
388 const char *oid, size_t len )
390 while( list != NULL )
392 if( list->oid.len == len &&
393 memcmp( list->oid.p, oid, len ) == 0 )
404 mbedtls_asn1_named_data *mbedtls_asn1_store_named_data(
405 mbedtls_asn1_named_data **head,
406 const char *oid, size_t oid_len,
407 const unsigned char *val,
410 mbedtls_asn1_named_data *cur;
412 if( ( cur = asn1_find_named_data( *head, oid, oid_len ) ) == NULL )
414 // Add new entry if not present yet based on OID
416 cur = (mbedtls_asn1_named_data*)mbedtls_calloc( 1,
417 sizeof(mbedtls_asn1_named_data) );
421 cur->oid.len = oid_len;
422 cur->oid.p = mbedtls_calloc( 1, oid_len );
423 if( cur->oid.p == NULL )
429 memcpy( cur->oid.p, oid, oid_len );
431 cur->val.len = val_len;
432 cur->val.p = mbedtls_calloc( 1, val_len );
433 if( cur->val.p == NULL )
435 mbedtls_free( cur->oid.p );
443 else if( cur->val.len < val_len )
446 * Enlarge existing value buffer if needed
447 * Preserve old data until the allocation succeeded, to leave list in
448 * a consistent state in case allocation fails.
450 void *p = mbedtls_calloc( 1, val_len );
454 mbedtls_free( cur->val.p );
456 cur->val.len = val_len;
460 memcpy( cur->val.p, val, val_len );
464 #endif /* MBEDTLS_ASN1_WRITE_C */