[proxmark3-svn] / common / mbedtls / asn1write.c

/*
 * ASN.1 buffer writing functionality
 *
 *  Copyright (C) 2006-2015, ARM Limited, All Rights Reserved
 *  SPDX-License-Identifier: GPL-2.0
 *
 *  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.
 *
 *  This file is part of mbed TLS (https://tls.mbed.org)
 */

#if !defined(MBEDTLS_CONFIG_FILE)
#include "mbedtls/config.h"
#else
#include MBEDTLS_CONFIG_FILE
#endif

#if defined(MBEDTLS_ASN1_WRITE_C)

#include "mbedtls/asn1write.h"

#include <string.h>

#if defined(MBEDTLS_PLATFORM_C)
#include "mbedtls/platform.h"
#else
#include <stdlib.h>
#define mbedtls_calloc    calloc
#define mbedtls_free       free
#endif

int mbedtls_asn1_write_len( unsigned char **p, unsigned char *start, size_t len )
{
    if( len < 0x80 )
    {
        if( *p - start < 1 )
            return( MBEDTLS_ERR_ASN1_BUF_TOO_SMALL );

        *--(*p) = (unsigned char) len;
        return( 1 );
    }

    if( len <= 0xFF )
    {
        if( *p - start < 2 )
            return( MBEDTLS_ERR_ASN1_BUF_TOO_SMALL );

        *--(*p) = (unsigned char) len;
        *--(*p) = 0x81;
        return( 2 );
    }

    if( len <= 0xFFFF )
    {
        if( *p - start < 3 )
            return( MBEDTLS_ERR_ASN1_BUF_TOO_SMALL );

        *--(*p) = ( len       ) & 0xFF;
        *--(*p) = ( len >>  8 ) & 0xFF;
        *--(*p) = 0x82;
        return( 3 );
    }

    if( len <= 0xFFFFFF )
    {
        if( *p - start < 4 )
            return( MBEDTLS_ERR_ASN1_BUF_TOO_SMALL );

        *--(*p) = ( len       ) & 0xFF;
        *--(*p) = ( len >>  8 ) & 0xFF;
        *--(*p) = ( len >> 16 ) & 0xFF;
        *--(*p) = 0x83;
        return( 4 );
    }

#if SIZE_MAX > 0xFFFFFFFF
    if( len <= 0xFFFFFFFF )
#endif
    {
        if( *p - start < 5 )
            return( MBEDTLS_ERR_ASN1_BUF_TOO_SMALL );

        *--(*p) = ( len       ) & 0xFF;
        *--(*p) = ( len >>  8 ) & 0xFF;
        *--(*p) = ( len >> 16 ) & 0xFF;
        *--(*p) = ( len >> 24 ) & 0xFF;
        *--(*p) = 0x84;
        return( 5 );
    }

#if SIZE_MAX > 0xFFFFFFFF
    return( MBEDTLS_ERR_ASN1_INVALID_LENGTH );
#endif
}

int mbedtls_asn1_write_tag( unsigned char **p, unsigned char *start, unsigned char tag )
{
    if( *p - start < 1 )
        return( MBEDTLS_ERR_ASN1_BUF_TOO_SMALL );

    *--(*p) = tag;

    return( 1 );
}

int mbedtls_asn1_write_raw_buffer( unsigned char **p, unsigned char *start,
                           const unsigned char *buf, size_t size )
{
    size_t len = 0;

    if( *p < start || (size_t)( *p - start ) < size )
        return( MBEDTLS_ERR_ASN1_BUF_TOO_SMALL );

    len = size;
    (*p) -= len;
    memcpy( *p, buf, len );

    return( (int) len );
}

#if defined(MBEDTLS_BIGNUM_C)
int mbedtls_asn1_write_mpi( unsigned char **p, unsigned char *start, const mbedtls_mpi *X )
{
    int ret;
    size_t len = 0;

    // Write the MPI
    //
    len = mbedtls_mpi_size( X );

    if( *p < start || (size_t)( *p - start ) < len )
        return( MBEDTLS_ERR_ASN1_BUF_TOO_SMALL );

    (*p) -= len;
    MBEDTLS_MPI_CHK( mbedtls_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( MBEDTLS_ERR_ASN1_BUF_TOO_SMALL );

        *--(*p) = 0x00;
        len += 1;
    }

    MBEDTLS_ASN1_CHK_ADD( len, mbedtls_asn1_write_len( p, start, len ) );
    MBEDTLS_ASN1_CHK_ADD( len, mbedtls_asn1_write_tag( p, start, MBEDTLS_ASN1_INTEGER ) );

    ret = (int) len;

cleanup:
    return( ret );
}
#endif /* MBEDTLS_BIGNUM_C */

int mbedtls_asn1_write_null( unsigned char **p, unsigned char *start )
{
    int ret;
    size_t len = 0;

    // Write NULL
    //
    MBEDTLS_ASN1_CHK_ADD( len, mbedtls_asn1_write_len( p, start, 0) );
    MBEDTLS_ASN1_CHK_ADD( len, mbedtls_asn1_write_tag( p, start, MBEDTLS_ASN1_NULL ) );

    return( (int) len );
}

int mbedtls_asn1_write_oid( unsigned char **p, unsigned char *start,
                    const char *oid, size_t oid_len )
{
    int ret;
    size_t len = 0;

    MBEDTLS_ASN1_CHK_ADD( len, mbedtls_asn1_write_raw_buffer( p, start,
                                  (const unsigned char *) oid, oid_len ) );
    MBEDTLS_ASN1_CHK_ADD( len , mbedtls_asn1_write_len( p, start, len ) );
    MBEDTLS_ASN1_CHK_ADD( len , mbedtls_asn1_write_tag( p, start, MBEDTLS_ASN1_OID ) );

    return( (int) len );
}

int mbedtls_asn1_write_algorithm_identifier( unsigned char **p, unsigned char *start,
                                     const char *oid, size_t oid_len,
                                     size_t par_len )
{
    int ret;
    size_t len = 0;

    if( par_len == 0 )
        MBEDTLS_ASN1_CHK_ADD( len, mbedtls_asn1_write_null( p, start ) );
    else
        len += par_len;

    MBEDTLS_ASN1_CHK_ADD( len, mbedtls_asn1_write_oid( p, start, oid, oid_len ) );

    MBEDTLS_ASN1_CHK_ADD( len, mbedtls_asn1_write_len( p, start, len ) );
    MBEDTLS_ASN1_CHK_ADD( len, mbedtls_asn1_write_tag( p, start,
                                       MBEDTLS_ASN1_CONSTRUCTED | MBEDTLS_ASN1_SEQUENCE ) );

    return( (int) len );
}

int mbedtls_asn1_write_bool( unsigned char **p, unsigned char *start, int boolean )
{
    int ret;
    size_t len = 0;

    if( *p - start < 1 )
        return( MBEDTLS_ERR_ASN1_BUF_TOO_SMALL );

    *--(*p) = (boolean) ? 255 : 0;
    len++;

    MBEDTLS_ASN1_CHK_ADD( len, mbedtls_asn1_write_len( p, start, len ) );
    MBEDTLS_ASN1_CHK_ADD( len, mbedtls_asn1_write_tag( p, start, MBEDTLS_ASN1_BOOLEAN ) );

    return( (int) len );
}

int mbedtls_asn1_write_int( unsigned char **p, unsigned char *start, int val )
{
    int ret;
    size_t len = 0;

    if( *p - start < 1 )
        return( MBEDTLS_ERR_ASN1_BUF_TOO_SMALL );

    len += 1;
    *--(*p) = val;

    if( val > 0 && **p & 0x80 )
    {
        if( *p - start < 1 )
            return( MBEDTLS_ERR_ASN1_BUF_TOO_SMALL );

        *--(*p) = 0x00;
        len += 1;
    }

    MBEDTLS_ASN1_CHK_ADD( len, mbedtls_asn1_write_len( p, start, len ) );
    MBEDTLS_ASN1_CHK_ADD( len, mbedtls_asn1_write_tag( p, start, MBEDTLS_ASN1_INTEGER ) );

    return( (int) len );
}

int mbedtls_asn1_write_printable_string( unsigned char **p, unsigned char *start,
                                 const char *text, size_t text_len )
{
    int ret;
    size_t len = 0;

    MBEDTLS_ASN1_CHK_ADD( len, mbedtls_asn1_write_raw_buffer( p, start,
                  (const unsigned char *) text, text_len ) );

    MBEDTLS_ASN1_CHK_ADD( len, mbedtls_asn1_write_len( p, start, len ) );
    MBEDTLS_ASN1_CHK_ADD( len, mbedtls_asn1_write_tag( p, start, MBEDTLS_ASN1_PRINTABLE_STRING ) );

    return( (int) len );
}

int mbedtls_asn1_write_ia5_string( unsigned char **p, unsigned char *start,
                           const char *text, size_t text_len )
{
    int ret;
    size_t len = 0;

    MBEDTLS_ASN1_CHK_ADD( len, mbedtls_asn1_write_raw_buffer( p, start,
                  (const unsigned char *) text, text_len ) );

    MBEDTLS_ASN1_CHK_ADD( len, mbedtls_asn1_write_len( p, start, len ) );
    MBEDTLS_ASN1_CHK_ADD( len, mbedtls_asn1_write_tag( p, start, MBEDTLS_ASN1_IA5_STRING ) );

    return( (int) len );
}

int mbedtls_asn1_write_bitstring( unsigned char **p, unsigned char *start,
                          const unsigned char *buf, size_t bits )
{
    int ret;
    size_t len = 0, size;

    size = ( bits / 8 ) + ( ( bits % 8 ) ? 1 : 0 );

    // Calculate byte length
    //
    if( *p < start || (size_t)( *p - start ) < size + 1 )
        return( MBEDTLS_ERR_ASN1_BUF_TOO_SMALL );

    len = size + 1;
    (*p) -= size;
    memcpy( *p, buf, size );

    // Write unused bits
    //
    *--(*p) = (unsigned char) (size * 8 - bits);

    MBEDTLS_ASN1_CHK_ADD( len, mbedtls_asn1_write_len( p, start, len ) );
    MBEDTLS_ASN1_CHK_ADD( len, mbedtls_asn1_write_tag( p, start, MBEDTLS_ASN1_BIT_STRING ) );

    return( (int) len );
}

int mbedtls_asn1_write_octet_string( unsigned char **p, unsigned char *start,
                             const unsigned char *buf, size_t size )
{
    int ret;
    size_t len = 0;

    MBEDTLS_ASN1_CHK_ADD( len, mbedtls_asn1_write_raw_buffer( p, start, buf, size ) );

    MBEDTLS_ASN1_CHK_ADD( len, mbedtls_asn1_write_len( p, start, len ) );
    MBEDTLS_ASN1_CHK_ADD( len, mbedtls_asn1_write_tag( p, start, MBEDTLS_ASN1_OCTET_STRING ) );

    return( (int) len );
}

mbedtls_asn1_named_data *mbedtls_asn1_store_named_data( mbedtls_asn1_named_data **head,
                                        const char *oid, size_t oid_len,
                                        const unsigned char *val,
                                        size_t val_len )
{
    mbedtls_asn1_named_data *cur;

    if( ( cur = mbedtls_asn1_find_named_data( *head, oid, oid_len ) ) == NULL )
    {
        // Add new entry if not present yet based on OID
        //
        cur = (mbedtls_asn1_named_data*)mbedtls_calloc( 1,
                                            sizeof(mbedtls_asn1_named_data) );
        if( cur == NULL )
            return( NULL );

        cur->oid.len = oid_len;
        cur->oid.p = mbedtls_calloc( 1, oid_len );
        if( cur->oid.p == NULL )
        {
            mbedtls_free( cur );
            return( NULL );
        }

        memcpy( cur->oid.p, oid, oid_len );

        cur->val.len = val_len;
        cur->val.p = mbedtls_calloc( 1, val_len );
        if( cur->val.p == NULL )
        {
            mbedtls_free( cur->oid.p );
            mbedtls_free( cur );
            return( NULL );
        }

        cur->next = *head;
        *head = cur;
    }
    else if( cur->val.len < val_len )
    {
        /*
         * Enlarge existing value buffer if needed
         * Preserve old data until the allocation succeeded, to leave list in
         * a consistent state in case allocation fails.
         */
        void *p = mbedtls_calloc( 1, val_len );
        if( p == NULL )
            return( NULL );

        mbedtls_free( cur->val.p );
        cur->val.p = p;
        cur->val.len = val_len;
    }

    if( val != NULL )
        memcpy( cur->val.p, val, val_len );

    return( cur );
}
#endif /* MBEDTLS_ASN1_WRITE_C */
Commit	Line	Data
700d8687 OM	1	/*
	2	* ASN.1 buffer writing functionality
	3	*
	4	* Copyright (C) 2006-2015, ARM Limited, All Rights Reserved
	5	* SPDX-License-Identifier: GPL-2.0
	6	*
	7	* This program is free software; you can redistribute it and/or modify
	8	* it under the terms of the GNU General Public License as published by
	9	* the Free Software Foundation; either version 2 of the License, or
	10	* (at your option) any later version.
	11	*
	12	* This program is distributed in the hope that it will be useful,
	13	* but WITHOUT ANY WARRANTY; without even the implied warranty of
	14	* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
	15	* GNU General Public License for more details.
	16	*
	17	* You should have received a copy of the GNU General Public License along
	18	* with this program; if not, write to the Free Software Foundation, Inc.,
	19	* 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
	20	*
	21	* This file is part of mbed TLS (https://tls.mbed.org)
	22	*/
	23
	24	#if !defined(MBEDTLS_CONFIG_FILE)
	25	#include "mbedtls/config.h"
	26	#else
	27	#include MBEDTLS_CONFIG_FILE
	28	#endif
	29
	30	#if defined(MBEDTLS_ASN1_WRITE_C)
	31
	32	#include "mbedtls/asn1write.h"
	33
	34	#include <string.h>
	35
	36	#if defined(MBEDTLS_PLATFORM_C)
	37	#include "mbedtls/platform.h"
	38	#else
	39	#include <stdlib.h>
	40	#define mbedtls_calloc calloc
	41	#define mbedtls_free free
	42	#endif
	43
	44	int mbedtls_asn1_write_len( unsigned char *p, unsigned char start, size_t len )
	45	{
	46	if( len < 0x80 )
	47	{
	48	if( *p - start < 1 )
	49	return( MBEDTLS_ERR_ASN1_BUF_TOO_SMALL );
	50
	51	--(p) = (unsigned char) len;
	52	return( 1 );
	53	}
	54
	55	if( len <= 0xFF )
	56	{
	57	if( *p - start < 2 )
	58	return( MBEDTLS_ERR_ASN1_BUF_TOO_SMALL );
	59
	60	--(p) = (unsigned char) len;
	61	--(p) = 0x81;
	62	return( 2 );
	63	}
	64
65	if( len <= 0xFFFF )
66	{
67	if( *p - start < 3 )
68	return( MBEDTLS_ERR_ASN1_BUF_TOO_SMALL );
69
70	--(p) = ( len ) & 0xFF;
71	--(p) = ( len >> 8 ) & 0xFF;
72	--(p) = 0x82;
73	return( 3 );
74	}
75
76	if( len <= 0xFFFFFF )
77	{
78	if( *p - start < 4 )
79	return( MBEDTLS_ERR_ASN1_BUF_TOO_SMALL );
80
81	--(p) = ( len ) & 0xFF;
82	--(p) = ( len >> 8 ) & 0xFF;
83	--(p) = ( len >> 16 ) & 0xFF;
84	--(p) = 0x83;
85	return( 4 );
86	}
87
88	#if SIZE_MAX > 0xFFFFFFFF
89	if( len <= 0xFFFFFFFF )
90	#endif
91	{
92	if( *p - start < 5 )
93	return( MBEDTLS_ERR_ASN1_BUF_TOO_SMALL );
94
95	--(p) = ( len ) & 0xFF;
96	--(p) = ( len >> 8 ) & 0xFF;
97	--(p) = ( len >> 16 ) & 0xFF;
98	--(p) = ( len >> 24 ) & 0xFF;
99	--(p) = 0x84;
100	return( 5 );
101	}
102
103	#if SIZE_MAX > 0xFFFFFFFF
104	return( MBEDTLS_ERR_ASN1_INVALID_LENGTH );
105	#endif
106	}
107
108	int mbedtls_asn1_write_tag( unsigned char *p, unsigned char start, unsigned char tag )
109	{
110	if( *p - start < 1 )
111	return( MBEDTLS_ERR_ASN1_BUF_TOO_SMALL );
112
113	--(p) = tag;
114
115	return( 1 );
116	}
117
118	int mbedtls_asn1_write_raw_buffer( unsigned char *p, unsigned char start,
119	const unsigned char *buf, size_t size )
120	{
121	size_t len = 0;
122
123	if( p < start \|\| (size_t)( p - start ) < size )
124	return( MBEDTLS_ERR_ASN1_BUF_TOO_SMALL );
125
126	len = size;
127	(*p) -= len;
128	memcpy( *p, buf, len );
129
130	return( (int) len );
131	}
132
133	#if defined(MBEDTLS_BIGNUM_C)
134	int mbedtls_asn1_write_mpi( unsigned char *p, unsigned char start, const mbedtls_mpi *X )
135	{
136	int ret;
137	size_t len = 0;
138
139	// Write the MPI
140	//
141	len = mbedtls_mpi_size( X );
142
143	if( p < start \|\| (size_t)( p - start ) < len )
144	return( MBEDTLS_ERR_ASN1_BUF_TOO_SMALL );
145
146	(*p) -= len;
147	MBEDTLS_MPI_CHK( mbedtls_mpi_write_binary( X, *p, len ) );
148
149	// DER format assumes 2s complement for numbers, so the leftmost bit
150	// should be 0 for positive numbers and 1 for negative numbers.
151	//
152	if( X->s ==1 && **p & 0x80 )
153	{
154	if( *p - start < 1 )
155	return( MBEDTLS_ERR_ASN1_BUF_TOO_SMALL );
156
157	--(p) = 0x00;
158	len += 1;
159	}
160
161	MBEDTLS_ASN1_CHK_ADD( len, mbedtls_asn1_write_len( p, start, len ) );
162	MBEDTLS_ASN1_CHK_ADD( len, mbedtls_asn1_write_tag( p, start, MBEDTLS_ASN1_INTEGER ) );
163
164	ret = (int) len;
165
166	cleanup:
167	return( ret );
168	}
169	#endif /* MBEDTLS_BIGNUM_C */
170
171	int mbedtls_asn1_write_null( unsigned char *p, unsigned char start )
172	{
173	int ret;
174	size_t len = 0;
175
176	// Write NULL
177	//
178	MBEDTLS_ASN1_CHK_ADD( len, mbedtls_asn1_write_len( p, start, 0) );
179	MBEDTLS_ASN1_CHK_ADD( len, mbedtls_asn1_write_tag( p, start, MBEDTLS_ASN1_NULL ) );
180
181	return( (int) len );
182	}
183
184	int mbedtls_asn1_write_oid( unsigned char *p, unsigned char start,
185	const char *oid, size_t oid_len )
186	{
187	int ret;
188	size_t len = 0;
189
190	MBEDTLS_ASN1_CHK_ADD( len, mbedtls_asn1_write_raw_buffer( p, start,
191	(const unsigned char *) oid, oid_len ) );
192	MBEDTLS_ASN1_CHK_ADD( len , mbedtls_asn1_write_len( p, start, len ) );
193	MBEDTLS_ASN1_CHK_ADD( len , mbedtls_asn1_write_tag( p, start, MBEDTLS_ASN1_OID ) );
194
195	return( (int) len );
196	}
197
198	int mbedtls_asn1_write_algorithm_identifier( unsigned char *p, unsigned char start,
199	const char *oid, size_t oid_len,
200	size_t par_len )
201	{
202	int ret;
203	size_t len = 0;
204
205	if( par_len == 0 )
206	MBEDTLS_ASN1_CHK_ADD( len, mbedtls_asn1_write_null( p, start ) );
207	else
208	len += par_len;
209
210	MBEDTLS_ASN1_CHK_ADD( len, mbedtls_asn1_write_oid( p, start, oid, oid_len ) );
211
212	MBEDTLS_ASN1_CHK_ADD( len, mbedtls_asn1_write_len( p, start, len ) );
213	MBEDTLS_ASN1_CHK_ADD( len, mbedtls_asn1_write_tag( p, start,
214	MBEDTLS_ASN1_CONSTRUCTED \| MBEDTLS_ASN1_SEQUENCE ) );
215
216	return( (int) len );
217	}
218
219	int mbedtls_asn1_write_bool( unsigned char *p, unsigned char start, int boolean )
220	{
221	int ret;
222	size_t len = 0;
223
224	if( *p - start < 1 )
225	return( MBEDTLS_ERR_ASN1_BUF_TOO_SMALL );
226
227	--(p) = (boolean) ? 255 : 0;
228	len++;
229
230	MBEDTLS_ASN1_CHK_ADD( len, mbedtls_asn1_write_len( p, start, len ) );
231	MBEDTLS_ASN1_CHK_ADD( len, mbedtls_asn1_write_tag( p, start, MBEDTLS_ASN1_BOOLEAN ) );
232
233	return( (int) len );
234	}
235
236	int mbedtls_asn1_write_int( unsigned char *p, unsigned char start, int val )
237	{
238	int ret;
239	size_t len = 0;
240
241	if( *p - start < 1 )
242	return( MBEDTLS_ERR_ASN1_BUF_TOO_SMALL );
243
244	len += 1;
245	--(p) = val;
246
247	if( val > 0 && **p & 0x80 )
248	{
249	if( *p - start < 1 )
250	return( MBEDTLS_ERR_ASN1_BUF_TOO_SMALL );
251
252	--(p) = 0x00;
253	len += 1;
254	}
255
256	MBEDTLS_ASN1_CHK_ADD( len, mbedtls_asn1_write_len( p, start, len ) );
257	MBEDTLS_ASN1_CHK_ADD( len, mbedtls_asn1_write_tag( p, start, MBEDTLS_ASN1_INTEGER ) );
258
259	return( (int) len );
260	}
261
262	int mbedtls_asn1_write_printable_string( unsigned char *p, unsigned char start,
263	const char *text, size_t text_len )
264	{
265	int ret;
266	size_t len = 0;
267
268	MBEDTLS_ASN1_CHK_ADD( len, mbedtls_asn1_write_raw_buffer( p, start,
269	(const unsigned char *) text, text_len ) );
270
271	MBEDTLS_ASN1_CHK_ADD( len, mbedtls_asn1_write_len( p, start, len ) );
272	MBEDTLS_ASN1_CHK_ADD( len, mbedtls_asn1_write_tag( p, start, MBEDTLS_ASN1_PRINTABLE_STRING ) );
273
274	return( (int) len );
275	}
276
277	int mbedtls_asn1_write_ia5_string( unsigned char *p, unsigned char start,
278	const char *text, size_t text_len )
279	{
280	int ret;
281	size_t len = 0;
282
283	MBEDTLS_ASN1_CHK_ADD( len, mbedtls_asn1_write_raw_buffer( p, start,
284	(const unsigned char *) text, text_len ) );
285
286	MBEDTLS_ASN1_CHK_ADD( len, mbedtls_asn1_write_len( p, start, len ) );
287	MBEDTLS_ASN1_CHK_ADD( len, mbedtls_asn1_write_tag( p, start, MBEDTLS_ASN1_IA5_STRING ) );
288
289	return( (int) len );
290	}
291
292	int mbedtls_asn1_write_bitstring( unsigned char *p, unsigned char start,
293	const unsigned char *buf, size_t bits )
294	{
295	int ret;
296	size_t len = 0, size;
297
298	size = ( bits / 8 ) + ( ( bits % 8 ) ? 1 : 0 );
299
300	// Calculate byte length
301	//
302	if( p < start \|\| (size_t)( p - start ) < size + 1 )
303	return( MBEDTLS_ERR_ASN1_BUF_TOO_SMALL );
304
305	len = size + 1;
306	(*p) -= size;
307	memcpy( *p, buf, size );
308
309	// Write unused bits
310	//
311	--(p) = (unsigned char) (size * 8 - bits);
312
313	MBEDTLS_ASN1_CHK_ADD( len, mbedtls_asn1_write_len( p, start, len ) );
314	MBEDTLS_ASN1_CHK_ADD( len, mbedtls_asn1_write_tag( p, start, MBEDTLS_ASN1_BIT_STRING ) );
315
316	return( (int) len );
317	}
318
319	int mbedtls_asn1_write_octet_string( unsigned char *p, unsigned char start,
320	const unsigned char *buf, size_t size )
321	{
322	int ret;
323	size_t len = 0;
324
325	MBEDTLS_ASN1_CHK_ADD( len, mbedtls_asn1_write_raw_buffer( p, start, buf, size ) );
326
327	MBEDTLS_ASN1_CHK_ADD( len, mbedtls_asn1_write_len( p, start, len ) );
328	MBEDTLS_ASN1_CHK_ADD( len, mbedtls_asn1_write_tag( p, start, MBEDTLS_ASN1_OCTET_STRING ) );
329
330	return( (int) len );
331	}
332
333	mbedtls_asn1_named_data mbedtls_asn1_store_named_data( mbedtls_asn1_named_data *head,
334	const char *oid, size_t oid_len,
335	const unsigned char *val,
336	size_t val_len )
337	{
338	mbedtls_asn1_named_data *cur;
339
340	if( ( cur = mbedtls_asn1_find_named_data( *head, oid, oid_len ) ) == NULL )
341	{
342	// Add new entry if not present yet based on OID
343	//
344	cur = (mbedtls_asn1_named_data*)mbedtls_calloc( 1,
345	sizeof(mbedtls_asn1_named_data) );
346	if( cur == NULL )
347	return( NULL );
348
349	cur->oid.len = oid_len;
350	cur->oid.p = mbedtls_calloc( 1, oid_len );
351	if( cur->oid.p == NULL )
352	{
353	mbedtls_free( cur );
354	return( NULL );
355	}
356
357	memcpy( cur->oid.p, oid, oid_len );
358
359	cur->val.len = val_len;
360	cur->val.p = mbedtls_calloc( 1, val_len );
361	if( cur->val.p == NULL )
362	{
363	mbedtls_free( cur->oid.p );
364	mbedtls_free( cur );
365	return( NULL );
366	}
367
368	cur->next = *head;
369	*head = cur;
370	}
371	else if( cur->val.len < val_len )
372	{
373	/*
374	* Enlarge existing value buffer if needed
375	* Preserve old data until the allocation succeeded, to leave list in
376	* a consistent state in case allocation fails.
377	*/
378	void *p = mbedtls_calloc( 1, val_len );
379	if( p == NULL )
380	return( NULL );
381
382	mbedtls_free( cur->val.p );
383	cur->val.p = p;
384	cur->val.len = val_len;
385	}
386
387	if( val != NULL )
388	memcpy( cur->val.p, val, val_len );
389
390	return( cur );
391	}
392	#endif /* MBEDTLS_ASN1_WRITE_C */