tests/suites/test_suite_x509write.function

/* BEGIN_HEADER */
#include "mbedtls/bignum.h"
#include "mbedtls/x509_crt.h"
#include "mbedtls/x509_csr.h"
#include "mbedtls/pem.h"
#include "mbedtls/oid.h"
#include "mbedtls/rsa.h"
#include "mbedtls/asn1write.h"

#include "hash_info.h"
#include "mbedtls/legacy_or_psa.h"

#if defined(MBEDTLS_RSA_C)
int mbedtls_rsa_decrypt_func( void *ctx, size_t *olen,
                       const unsigned char *input, unsigned char *output,
                       size_t output_max_len )
{
    return( mbedtls_rsa_pkcs1_decrypt( (mbedtls_rsa_context *) ctx, NULL, NULL,
                                        olen, input, output, output_max_len ) );
}
int mbedtls_rsa_sign_func( void *ctx,
                   int (*f_rng)(void *, unsigned char *, size_t), void *p_rng,
                   mbedtls_md_type_t md_alg, unsigned int hashlen,
                   const unsigned char *hash, unsigned char *sig )
{
    return( mbedtls_rsa_pkcs1_sign( (mbedtls_rsa_context *) ctx, f_rng, p_rng,
                                    md_alg, hashlen, hash, sig ) );
}
size_t mbedtls_rsa_key_len_func( void *ctx )
{
    return( ((const mbedtls_rsa_context *) ctx)->len );
}
#endif /* MBEDTLS_RSA_C */

#if defined(MBEDTLS_USE_PSA_CRYPTO) && \
    defined(MBEDTLS_PEM_WRITE_C) && defined(MBEDTLS_X509_CSR_WRITE_C)
static int x509_crt_verifycsr( const unsigned char *buf, size_t buflen )
{
    unsigned char hash[PSA_HASH_MAX_SIZE];
    mbedtls_x509_csr csr;
    int ret = 0;

    mbedtls_x509_csr_init( &csr );

    if( mbedtls_x509_csr_parse( &csr, buf, buflen ) != 0 )
    {
        ret = MBEDTLS_ERR_X509_BAD_INPUT_DATA;
        goto cleanup;
    }

    psa_algorithm_t psa_alg = mbedtls_hash_info_psa_from_md( csr.sig_md );
    size_t hash_size = 0;
    psa_status_t status = psa_hash_compute( psa_alg, csr.cri.p, csr.cri.len,
                                            hash, PSA_HASH_MAX_SIZE, &hash_size );

    if( status != PSA_SUCCESS )
    {
        /* Note: this can't happen except after an internal error */
        ret = MBEDTLS_ERR_X509_BAD_INPUT_DATA;
        goto cleanup;
    }

    if( mbedtls_pk_verify_ext( csr.sig_pk, csr.sig_opts, &csr.pk,
                       csr.sig_md, hash, mbedtls_hash_info_get_size( csr.sig_md ),
                       csr.sig.p, csr.sig.len ) != 0 )
    {
        ret = MBEDTLS_ERR_X509_CERT_VERIFY_FAILED;
        goto cleanup;
    }

cleanup:

    mbedtls_x509_csr_free( &csr );
    return( ret );
}
#endif /* MBEDTLS_USE_PSA_CRYPTO && MBEDTLS_PEM_WRITE_C && MBEDTLS_X509_CSR_WRITE_C */

#if defined(MBEDTLS_X509_CSR_WRITE_C)

/*
 * The size of this temporary buffer is given by the sequence of functions
 * called hereinafter:
 * - mbedtls_asn1_write_oid()
 *     - 8 bytes for MBEDTLS_OID_EXTENDED_KEY_USAGE raw value
 *     - 1 byte for MBEDTLS_OID_EXTENDED_KEY_USAGE length
 *     - 1 byte for MBEDTLS_ASN1_OID tag
 * - mbedtls_asn1_write_len()
 *     - 1 byte since we're dealing with sizes which are less than 0x80
 * - mbedtls_asn1_write_tag()
 *     - 1 byte
 *
 * This length is fine as long as this function is called using the
 * MBEDTLS_OID_SERVER_AUTH OID. If this is changed in the future, then this
 * buffer's length should be adjusted accordingly.
 * Unfortunately there's no predefined max size for OIDs which can be used
 * to set an overall upper boundary which is always guaranteed.
 */
#define EXT_KEY_USAGE_TMP_BUF_MAX_LENGTH    12

static int csr_set_extended_key_usage( mbedtls_x509write_csr *ctx,
                        const char *oid, size_t oid_len )
{
    unsigned char buf[EXT_KEY_USAGE_TMP_BUF_MAX_LENGTH] = { 0 };
    unsigned char *p = buf + sizeof( buf );
    int ret;
    size_t len = 0;

    /*
     * Following functions fail anyway if the temporary buffer is not large,
     * but we set an extra check here to emphasize a possible source of errors
     */
    if ( oid_len > EXT_KEY_USAGE_TMP_BUF_MAX_LENGTH )
    {
        return MBEDTLS_ERR_X509_BAD_INPUT_DATA;
    }

    MBEDTLS_ASN1_CHK_ADD( len, mbedtls_asn1_write_oid( &p, buf, oid, oid_len ) );
    MBEDTLS_ASN1_CHK_ADD( len, mbedtls_asn1_write_len( &p, buf, ret ) );
    MBEDTLS_ASN1_CHK_ADD( len, mbedtls_asn1_write_tag( &p, buf,
                        MBEDTLS_ASN1_CONSTRUCTED | MBEDTLS_ASN1_SEQUENCE ) );

    ret = mbedtls_x509write_csr_set_extension( ctx, MBEDTLS_OID_EXTENDED_KEY_USAGE,
              MBEDTLS_OID_SIZE( MBEDTLS_OID_EXTENDED_KEY_USAGE ), 0, p, len );

    return ret;
}
#endif  /* MBEDTLS_X509_CSR_WRITE_C */
/* END_HEADER */

/* BEGIN_DEPENDENCIES
 * depends_on:MBEDTLS_BIGNUM_C:MBEDTLS_FS_IO:MBEDTLS_PK_PARSE_C
 * END_DEPENDENCIES
 */

/* BEGIN_CASE depends_on:MBEDTLS_PEM_WRITE_C:MBEDTLS_X509_CSR_WRITE_C */
void x509_csr_check( char * key_file, char * cert_req_check_file, int md_type,
                     int key_usage, int set_key_usage, int cert_type,
                     int set_cert_type, int set_extension )
{
    mbedtls_pk_context key;
    mbedtls_x509write_csr req;
    unsigned char buf[4096];
    int ret;
#if !defined(MBEDTLS_USE_PSA_CRYPTO)
    unsigned char check_buf[4000];
    FILE *f;
    size_t olen = 0;
#endif /* !MBEDTLS_USE_PSA_CRYPTO */
    size_t pem_len = 0, buf_index;
    int der_len = -1;
    const char *subject_name = "C=NL,O=PolarSSL,CN=PolarSSL Server 1";
    mbedtls_test_rnd_pseudo_info rnd_info;

    memset( &rnd_info, 0x2a, sizeof( mbedtls_test_rnd_pseudo_info ) );

    mbedtls_x509write_csr_init( &req );

    USE_PSA_INIT( );

    mbedtls_pk_init( &key );
    TEST_ASSERT( mbedtls_pk_parse_keyfile( &key, key_file, NULL,
                        mbedtls_test_rnd_std_rand, NULL ) == 0 );

    mbedtls_x509write_csr_set_md_alg( &req, md_type );
    mbedtls_x509write_csr_set_key( &req, &key );
    TEST_ASSERT( mbedtls_x509write_csr_set_subject_name( &req, subject_name ) == 0 );
    if( set_key_usage != 0 )
        TEST_ASSERT( mbedtls_x509write_csr_set_key_usage( &req, key_usage ) == 0 );
    if( set_cert_type != 0 )
        TEST_ASSERT( mbedtls_x509write_csr_set_ns_cert_type( &req, cert_type ) == 0 );
    if ( set_extension != 0 )
        TEST_ASSERT( csr_set_extended_key_usage( &req, MBEDTLS_OID_SERVER_AUTH,
                            MBEDTLS_OID_SIZE( MBEDTLS_OID_SERVER_AUTH ) ) == 0 );

    ret = mbedtls_x509write_csr_pem( &req, buf, sizeof( buf ),
                                     mbedtls_test_rnd_pseudo_rand, &rnd_info );
    TEST_ASSERT( ret == 0 );

    pem_len = strlen( (char *) buf );

    for( buf_index = pem_len; buf_index < sizeof( buf ); ++buf_index )
    {
        TEST_ASSERT( buf[buf_index] == 0 );
    }

#if defined(MBEDTLS_USE_PSA_CRYPTO)
    // When using PSA crypto, RNG isn't controllable, so cert_req_check_file can't be used
    (void)cert_req_check_file;
    buf[pem_len] = '\0';
    TEST_ASSERT( x509_crt_verifycsr( buf, pem_len + 1 ) == 0 );
#else
    f = fopen( cert_req_check_file, "r" );
    TEST_ASSERT( f != NULL );
    olen = fread( check_buf, 1, sizeof( check_buf ), f );
    fclose( f );

    TEST_ASSERT( olen >= pem_len - 1 );
    TEST_ASSERT( memcmp( buf, check_buf, pem_len - 1 ) == 0 );
#endif /* MBEDTLS_USE_PSA_CRYPTO */

    der_len = mbedtls_x509write_csr_der( &req, buf, sizeof( buf ),
                                         mbedtls_test_rnd_pseudo_rand,
                                         &rnd_info );
    TEST_ASSERT( der_len >= 0 );

    if( der_len == 0 )
        goto exit;

#if defined(MBEDTLS_USE_PSA_CRYPTO)
    // When using PSA crypto, RNG isn't controllable, result length isn't
    // deterministic over multiple runs, removing a single byte isn't enough to
    // go into the MBEDTLS_ERR_ASN1_BUF_TOO_SMALL error case
    der_len /= 2;
#else
    der_len -= 1;
#endif
    ret = mbedtls_x509write_csr_der( &req, buf, (size_t)( der_len ),
                                     mbedtls_test_rnd_pseudo_rand, &rnd_info );
    TEST_ASSERT( ret == MBEDTLS_ERR_ASN1_BUF_TOO_SMALL );

exit:
    mbedtls_x509write_csr_free( &req );
    mbedtls_pk_free( &key );
    USE_PSA_DONE( );
}
/* END_CASE */

/* BEGIN_CASE depends_on:MBEDTLS_PEM_WRITE_C:MBEDTLS_X509_CSR_WRITE_C:MBEDTLS_USE_PSA_CRYPTO */
void x509_csr_check_opaque( char *key_file, int md_type, int key_usage,
                                 int cert_type )
{
    mbedtls_pk_context key;
    mbedtls_svc_key_id_t key_id = MBEDTLS_SVC_KEY_ID_INIT;
    psa_algorithm_t md_alg_psa, alg_psa;
    mbedtls_x509write_csr req;
    unsigned char buf[4096];
    int ret;
    size_t pem_len = 0;
    const char *subject_name = "C=NL,O=PolarSSL,CN=PolarSSL Server 1";
    mbedtls_test_rnd_pseudo_info rnd_info;

    memset( &rnd_info, 0x2a, sizeof( mbedtls_test_rnd_pseudo_info ) );

    mbedtls_x509write_csr_init( &req );

    USE_PSA_INIT( );

    md_alg_psa = mbedtls_hash_info_psa_from_md( (mbedtls_md_type_t) md_type );
    TEST_ASSERT( md_alg_psa != MBEDTLS_MD_NONE );

    mbedtls_pk_init( &key );
    TEST_ASSERT( mbedtls_pk_parse_keyfile( &key, key_file, NULL,
                        mbedtls_test_rnd_std_rand, NULL ) == 0 );

    if( mbedtls_pk_get_type( &key ) == MBEDTLS_PK_ECKEY )
        alg_psa = PSA_ALG_ECDSA( md_alg_psa );
    else if( mbedtls_pk_get_type( &key ) == MBEDTLS_PK_RSA )
        alg_psa = PSA_ALG_RSA_PKCS1V15_SIGN( md_alg_psa );
    else
        TEST_ASSUME( ! "PK key type not supported in this configuration" );

    TEST_ASSERT( mbedtls_pk_wrap_as_opaque( &key, &key_id, alg_psa,
                                            PSA_KEY_USAGE_SIGN_HASH,
                                            PSA_ALG_NONE ) == 0 );

    mbedtls_x509write_csr_set_md_alg( &req, md_type );
    mbedtls_x509write_csr_set_key( &req, &key );
    TEST_ASSERT( mbedtls_x509write_csr_set_subject_name( &req, subject_name ) == 0 );
    if( key_usage != 0 )
        TEST_ASSERT( mbedtls_x509write_csr_set_key_usage( &req, key_usage ) == 0 );
    if( cert_type != 0 )
        TEST_ASSERT( mbedtls_x509write_csr_set_ns_cert_type( &req, cert_type ) == 0 );

    ret = mbedtls_x509write_csr_pem( &req, buf, sizeof( buf ) - 1,
                                     mbedtls_test_rnd_pseudo_rand, &rnd_info );

    TEST_ASSERT( ret == 0 );

    pem_len = strlen( (char *) buf );
    buf[pem_len] = '\0';
    TEST_ASSERT( x509_crt_verifycsr( buf, pem_len + 1 ) == 0 );


exit:
    mbedtls_x509write_csr_free( &req );
    mbedtls_pk_free( &key );
    psa_destroy_key( key_id );
    PSA_DONE( );
}
/* END_CASE */

/* BEGIN_CASE depends_on:MBEDTLS_PEM_WRITE_C:MBEDTLS_X509_CRT_WRITE_C:MBEDTLS_HAS_ALG_SHA_1_VIA_MD_OR_PSA_BASED_ON_USE_PSA */
void x509_crt_check( char *subject_key_file, char *subject_pwd,
                     char *subject_name, char *issuer_key_file,
                     char *issuer_pwd, char *issuer_name,
                     char *serial_str, char *not_before, char *not_after,
                     int md_type, int key_usage, int set_key_usage,
                     int cert_type, int set_cert_type, int auth_ident,
                     int ver, char *cert_check_file, int pk_wrap, int is_ca,
                     char *cert_verify_file )
{
    mbedtls_pk_context subject_key, issuer_key, issuer_key_alt;
    mbedtls_pk_context *key = &issuer_key;

    mbedtls_x509write_cert crt;
    unsigned char buf[4096];
    unsigned char check_buf[5000];
    unsigned char *p, *end;
    unsigned char tag, sz;
    mbedtls_mpi serial;
    int ret, before_tag, after_tag;
    size_t olen = 0, pem_len = 0, buf_index = 0;
    int der_len = -1;
    FILE *f;
    mbedtls_test_rnd_pseudo_info rnd_info;
#if defined(MBEDTLS_USE_PSA_CRYPTO)
    mbedtls_svc_key_id_t key_id = MBEDTLS_SVC_KEY_ID_INIT;
#endif
    mbedtls_pk_type_t issuer_key_type;

    memset( &rnd_info, 0x2a, sizeof( mbedtls_test_rnd_pseudo_info ) );
    mbedtls_mpi_init( &serial );

    USE_PSA_INIT( );

    mbedtls_pk_init( &subject_key );
    mbedtls_pk_init( &issuer_key  );
    mbedtls_pk_init( &issuer_key_alt );

    mbedtls_x509write_crt_init( &crt );

    TEST_ASSERT( mbedtls_pk_parse_keyfile( &subject_key, subject_key_file,
                    subject_pwd, mbedtls_test_rnd_std_rand, NULL ) == 0 );

    TEST_ASSERT( mbedtls_pk_parse_keyfile( &issuer_key, issuer_key_file,
                    issuer_pwd, mbedtls_test_rnd_std_rand, NULL ) == 0 );

    issuer_key_type = mbedtls_pk_get_type( &issuer_key );

#if defined(MBEDTLS_RSA_C)
    /* For RSA PK contexts, create a copy as an alternative RSA context. */
    if( pk_wrap == 1 && issuer_key_type == MBEDTLS_PK_RSA )
    {
        TEST_ASSERT( mbedtls_pk_setup_rsa_alt( &issuer_key_alt,
                                            mbedtls_pk_rsa( issuer_key ),
                                            mbedtls_rsa_decrypt_func,
                                            mbedtls_rsa_sign_func,
                                            mbedtls_rsa_key_len_func ) == 0 );

        key = &issuer_key_alt;
    }
#endif

#if defined(MBEDTLS_USE_PSA_CRYPTO)
    /* For Opaque PK contexts, wrap key as an Opaque RSA context. */
    if( pk_wrap == 2 )
    {
        psa_algorithm_t alg_psa, md_alg_psa;

        md_alg_psa = mbedtls_hash_info_psa_from_md( (mbedtls_md_type_t) md_type );
        TEST_ASSERT( md_alg_psa != MBEDTLS_MD_NONE );

        if( mbedtls_pk_get_type( &issuer_key ) == MBEDTLS_PK_ECKEY )
            alg_psa = PSA_ALG_ECDSA( md_alg_psa );
        else if( mbedtls_pk_get_type( &issuer_key ) == MBEDTLS_PK_RSA )
            alg_psa = PSA_ALG_RSA_PKCS1V15_SIGN( md_alg_psa );
        else
            TEST_ASSUME( ! "PK key type not supported in this configuration" );

        TEST_ASSERT( mbedtls_pk_wrap_as_opaque( &issuer_key, &key_id, alg_psa,
                                                PSA_KEY_USAGE_SIGN_HASH,
                                                PSA_ALG_NONE ) == 0 );
    }
#endif /* MBEDTLS_USE_PSA_CRYPTO */

    if( pk_wrap == 2 )
        TEST_ASSERT( mbedtls_pk_get_type( &issuer_key ) == MBEDTLS_PK_OPAQUE );

    TEST_ASSERT( mbedtls_test_read_mpi( &serial, serial_str ) == 0 );

    if( ver != -1 )
        mbedtls_x509write_crt_set_version( &crt, ver );

    TEST_ASSERT( mbedtls_x509write_crt_set_serial( &crt, &serial ) == 0 );
    TEST_ASSERT( mbedtls_x509write_crt_set_validity( &crt, not_before,
                                                     not_after ) == 0 );
    mbedtls_x509write_crt_set_md_alg( &crt, md_type );
    TEST_ASSERT( mbedtls_x509write_crt_set_issuer_name( &crt, issuer_name ) == 0 );
    TEST_ASSERT( mbedtls_x509write_crt_set_subject_name( &crt, subject_name ) == 0 );
    mbedtls_x509write_crt_set_subject_key( &crt, &subject_key );

    mbedtls_x509write_crt_set_issuer_key( &crt, key );

    if( crt.version >= MBEDTLS_X509_CRT_VERSION_3 )
    {
        /* For the CA case, a path length of -1 means unlimited. */
        TEST_ASSERT( mbedtls_x509write_crt_set_basic_constraints( &crt, is_ca,
                                                                  (is_ca ? -1 : 0) ) == 0 );
        TEST_ASSERT( mbedtls_x509write_crt_set_subject_key_identifier( &crt ) == 0 );
        if( auth_ident )
            TEST_ASSERT( mbedtls_x509write_crt_set_authority_key_identifier( &crt ) == 0 );
        if( set_key_usage != 0 )
            TEST_ASSERT( mbedtls_x509write_crt_set_key_usage( &crt, key_usage ) == 0 );
        if( set_cert_type != 0 )
            TEST_ASSERT( mbedtls_x509write_crt_set_ns_cert_type( &crt, cert_type ) == 0 );
    }

    ret = mbedtls_x509write_crt_pem( &crt, buf, sizeof( buf ),
                                     mbedtls_test_rnd_pseudo_rand, &rnd_info );
    TEST_ASSERT( ret == 0 );

    pem_len = strlen( (char *) buf );

    // check that the rest of the buffer remains clear
    for( buf_index = pem_len; buf_index < sizeof( buf ); ++buf_index )
    {
        TEST_ASSERT( buf[buf_index] == 0 );
    }

    if( issuer_key_type != MBEDTLS_PK_RSA )
    {
        mbedtls_x509_crt crt_parse, trusted;
        uint32_t flags;

        mbedtls_x509_crt_init( &crt_parse );
        mbedtls_x509_crt_init( &trusted );

        TEST_ASSERT( mbedtls_x509_crt_parse_file( &trusted,
                                                  cert_verify_file ) == 0 );
        TEST_ASSERT( mbedtls_x509_crt_parse( &crt_parse,
                                             buf, sizeof( buf ) ) == 0 );

        ret = mbedtls_x509_crt_verify( &crt_parse, &trusted, NULL, NULL, &flags,
                                       NULL, NULL );

        mbedtls_x509_crt_free( &crt_parse );
        mbedtls_x509_crt_free( &trusted );

        TEST_EQUAL( flags, 0 );
        TEST_EQUAL( ret, 0 );
    }
    else if( *cert_check_file != '\0' )
    {
        f = fopen( cert_check_file, "r" );
        TEST_ASSERT( f != NULL );
        olen = fread( check_buf, 1, sizeof( check_buf ), f );
        fclose( f );
        TEST_ASSERT( olen < sizeof( check_buf ) );

        TEST_EQUAL( olen, pem_len );
        TEST_ASSERT( olen >= pem_len - 1 );
        TEST_ASSERT( memcmp( buf, check_buf, pem_len - 1 ) == 0 );
    }

    der_len = mbedtls_x509write_crt_der( &crt, buf, sizeof( buf ),
                                         mbedtls_test_rnd_pseudo_rand,
                                         &rnd_info );
    TEST_ASSERT( der_len >= 0 );

    if( der_len == 0 )
        goto exit;

    // Not testing against file, check date format
    if( *cert_check_file == '\0' )
    {
        // UTC tag if before 2050, 2 digits less for year
        if( not_before[0] == '2' && ( not_before[1] > '0' || not_before[2] > '4' ) )
        {
            before_tag = MBEDTLS_ASN1_GENERALIZED_TIME;
        }
        else
        {
            before_tag = MBEDTLS_ASN1_UTC_TIME;
            not_before += 2;
        }
        if( not_after[0] == '2' && ( not_after[1] > '0' || not_after[2] > '4' ) )
        {
            after_tag = MBEDTLS_ASN1_GENERALIZED_TIME;
        }
        else
        {
            after_tag = MBEDTLS_ASN1_UTC_TIME;
            not_after += 2;
        }
        end = buf + sizeof( buf );
        for( p = end - der_len ; p < end ; )
        {
            tag = *p++;
            sz = *p++;
            if( tag == MBEDTLS_ASN1_UTC_TIME || tag == MBEDTLS_ASN1_GENERALIZED_TIME )
            {
                // Check correct tag and time written
                TEST_ASSERT( before_tag == tag );
                TEST_ASSERT( memcmp( p, not_before, sz - 1 ) == 0 );
                p += sz;
                tag = *p++;
                sz = *p++;
                TEST_ASSERT( after_tag == tag );
                TEST_ASSERT( memcmp( p, not_after, sz - 1 ) == 0 );
                break;
            }
            // Increment if long form ASN1 length
            if( sz & 0x80 )
                p += sz & 0x0F;
            if( tag != ( MBEDTLS_ASN1_CONSTRUCTED | MBEDTLS_ASN1_SEQUENCE ) )
                p += sz;
        }
        TEST_ASSERT( p < end );
    }

#if defined(MBEDTLS_USE_PSA_CRYPTO)
    // When using PSA crypto, RNG isn't controllable, result length isn't
    // deterministic over multiple runs, removing a single byte isn't enough to
    // go into the MBEDTLS_ERR_ASN1_BUF_TOO_SMALL error case
    if( issuer_key_type != MBEDTLS_PK_RSA )
        der_len /= 2;
    else
#endif
        der_len -= 1;

    ret = mbedtls_x509write_crt_der( &crt, buf, (size_t)( der_len ),
                                     mbedtls_test_rnd_pseudo_rand, &rnd_info );
    TEST_ASSERT( ret == MBEDTLS_ERR_ASN1_BUF_TOO_SMALL );

exit:
    mbedtls_x509write_crt_free( &crt );
    mbedtls_pk_free( &issuer_key_alt );
    mbedtls_pk_free( &subject_key );
    mbedtls_pk_free( &issuer_key );
    mbedtls_mpi_free( &serial );
#if defined(MBEDTLS_USE_PSA_CRYPTO)
    psa_destroy_key( key_id );
#endif
    USE_PSA_DONE( );
}
/* END_CASE */

/* BEGIN_CASE depends_on:MBEDTLS_X509_CREATE_C:MBEDTLS_X509_USE_C */
void mbedtls_x509_string_to_names( char * name, char * parsed_name, int result
                                   )
{
    int ret;
    size_t len = 0;
    mbedtls_asn1_named_data *names = NULL;
    mbedtls_x509_name parsed, *parsed_cur, *parsed_prv;
    unsigned char buf[1024], out[1024], *c;

    memset( &parsed, 0, sizeof( parsed ) );
    memset( out, 0, sizeof( out ) );
    memset( buf, 0, sizeof( buf ) );
    c = buf + sizeof( buf );

    ret = mbedtls_x509_string_to_names( &names, name );
    TEST_ASSERT( ret == result );

    if( ret != 0 )
        goto exit;

    ret = mbedtls_x509_write_names( &c, buf, names );
    TEST_ASSERT( ret > 0 );

    TEST_ASSERT( mbedtls_asn1_get_tag( &c, buf + sizeof( buf ), &len,
                        MBEDTLS_ASN1_CONSTRUCTED | MBEDTLS_ASN1_SEQUENCE ) == 0 );
    TEST_ASSERT( mbedtls_x509_get_name( &c, buf + sizeof( buf ), &parsed ) == 0 );

    ret = mbedtls_x509_dn_gets( (char *) out, sizeof( out ), &parsed );
    TEST_ASSERT( ret > 0 );

    TEST_ASSERT( strcmp( (char *) out, parsed_name ) == 0 );

exit:
    mbedtls_asn1_free_named_data_list( &names );

    parsed_cur = parsed.next;
    while( parsed_cur != 0 )
    {
        parsed_prv = parsed_cur;
        parsed_cur = parsed_cur->next;
        mbedtls_free( parsed_prv );
    }
}
/* END_CASE */