/work/mbedtls-3.6.6/library/x509write_csr.c

Source
/*
 *  X.509 Certificate Signing Request writing
 *
 *  Copyright The Mbed TLS Contributors
 *  SPDX-License-Identifier: Apache-2.0 OR GPL-2.0-or-later
 */
/*
 * References:
 * - CSRs: PKCS#10 v1.7 aka RFC 2986
 * - attributes: PKCS#9 v2.0 aka RFC 2985
 */

#include "common.h"

#if defined(MBEDTLS_X509_CSR_WRITE_C)

#include "x509_internal.h"
#include "mbedtls/x509_csr.h"
#include "mbedtls/asn1write.h"
#include "mbedtls/error.h"
#include "mbedtls/oid.h"
#include "mbedtls/platform_util.h"

#if defined(MBEDTLS_USE_PSA_CRYPTO)
#include "psa/crypto.h"
#include "psa_util_internal.h"
#include "mbedtls/psa_util.h"
#endif /* MBEDTLS_USE_PSA_CRYPTO */

#include <string.h>
#include <stdlib.h>

#if defined(MBEDTLS_PEM_WRITE_C)
#include "mbedtls/pem.h"
#endif

#include "mbedtls/platform.h"

void mbedtls_x509write_csr_init(mbedtls_x509write_csr *ctx)
{
    memset(ctx, 0, sizeof(mbedtls_x509write_csr));
}

void mbedtls_x509write_csr_free(mbedtls_x509write_csr *ctx)
{
    if (ctx == NULL) {
        return;
    }

    mbedtls_asn1_free_named_data_list(&ctx->subject);
    mbedtls_asn1_free_named_data_list(&ctx->extensions);

    mbedtls_platform_zeroize(ctx, sizeof(mbedtls_x509write_csr));
}

void mbedtls_x509write_csr_set_md_alg(mbedtls_x509write_csr *ctx, mbedtls_md_type_t md_alg)
{
    ctx->md_alg = md_alg;
}

void mbedtls_x509write_csr_set_key(mbedtls_x509write_csr *ctx, mbedtls_pk_context *key)
{
    ctx->key = key;
}

int mbedtls_x509write_csr_set_subject_name(mbedtls_x509write_csr *ctx,
                                           const char *subject_name)
{
    mbedtls_asn1_free_named_data_list(&ctx->subject);
    return mbedtls_x509_string_to_names(&ctx->subject, subject_name);
}

int mbedtls_x509write_csr_set_extension(mbedtls_x509write_csr *ctx,
                                        const char *oid, size_t oid_len,
                                        int critical,
                                        const unsigned char *val, size_t val_len)
{
    return mbedtls_x509_set_extension(&ctx->extensions, oid, oid_len,
                                      critical, val, val_len);
}

int mbedtls_x509write_csr_set_subject_alternative_name(mbedtls_x509write_csr *ctx,
                                                       const mbedtls_x509_san_list *san_list)
{
    return mbedtls_x509_write_set_san_common(&ctx->extensions, san_list);
}

int mbedtls_x509write_csr_set_key_usage(mbedtls_x509write_csr *ctx, unsigned char key_usage)
{
    unsigned char buf[4] = { 0 };
    unsigned char *c;
    int ret = MBEDTLS_ERR_ERROR_CORRUPTION_DETECTED;

    c = buf + 4;

    ret = mbedtls_asn1_write_named_bitstring(&c, buf, &key_usage, 8);
    if (ret < 3 || ret > 4) {
        return ret;
    }

    ret = mbedtls_x509write_csr_set_extension(ctx, MBEDTLS_OID_KEY_USAGE,
                                              MBEDTLS_OID_SIZE(MBEDTLS_OID_KEY_USAGE),
                                              0, c, (size_t) ret);
    if (ret != 0) {
        return ret;
    }

    return 0;
}

int mbedtls_x509write_csr_set_ns_cert_type(mbedtls_x509write_csr *ctx,
                                           unsigned char ns_cert_type)
{
    unsigned char buf[4] = { 0 };
    unsigned char *c;
    int ret = MBEDTLS_ERR_ERROR_CORRUPTION_DETECTED;

    c = buf + 4;

    ret = mbedtls_asn1_write_named_bitstring(&c, buf, &ns_cert_type, 8);
    if (ret < 3 || ret > 4) {
        return ret;
    }

    ret = mbedtls_x509write_csr_set_extension(ctx, MBEDTLS_OID_NS_CERT_TYPE,
                                              MBEDTLS_OID_SIZE(MBEDTLS_OID_NS_CERT_TYPE),
                                              0, c, (size_t) ret);
    if (ret != 0) {
        return ret;
    }

    return 0;
}

static int x509write_csr_der_internal(mbedtls_x509write_csr *ctx,
                                      unsigned char *buf,
                                      size_t size,
                                      unsigned char *sig, size_t sig_size,
                                      int (*f_rng)(void *, unsigned char *, size_t),
                                      void *p_rng)
{
    int ret = MBEDTLS_ERR_ERROR_CORRUPTION_DETECTED;
    const char *sig_oid;
    size_t sig_oid_len = 0;
    unsigned char *c, *c2;
    unsigned char hash[MBEDTLS_MD_MAX_SIZE];
    size_t pub_len = 0, sig_and_oid_len = 0, sig_len;
    size_t len = 0;
    mbedtls_pk_type_t pk_alg;
#if defined(MBEDTLS_USE_PSA_CRYPTO)
    size_t hash_len;
    psa_algorithm_t hash_alg = mbedtls_md_psa_alg_from_type(ctx->md_alg);
#endif /* MBEDTLS_USE_PSA_CRYPTO */

    /* Write the CSR backwards starting from the end of buf */
    c = buf + size;

    MBEDTLS_ASN1_CHK_ADD(len, mbedtls_x509_write_extensions(&c, buf,
                                                            ctx->extensions));

    if (len) {
        MBEDTLS_ASN1_CHK_ADD(len, mbedtls_asn1_write_len(&c, buf, len));
        MBEDTLS_ASN1_CHK_ADD(len,
                             mbedtls_asn1_write_tag(
                                 &c, buf,
                                 MBEDTLS_ASN1_CONSTRUCTED | MBEDTLS_ASN1_SEQUENCE));

        MBEDTLS_ASN1_CHK_ADD(len, mbedtls_asn1_write_len(&c, buf, len));
        MBEDTLS_ASN1_CHK_ADD(len,
                             mbedtls_asn1_write_tag(
                                 &c, buf,
                                 MBEDTLS_ASN1_CONSTRUCTED | MBEDTLS_ASN1_SET));

        MBEDTLS_ASN1_CHK_ADD(len,
                             mbedtls_asn1_write_oid(
                                 &c, buf, MBEDTLS_OID_PKCS9_CSR_EXT_REQ,
                                 MBEDTLS_OID_SIZE(MBEDTLS_OID_PKCS9_CSR_EXT_REQ)));

        MBEDTLS_ASN1_CHK_ADD(len, mbedtls_asn1_write_len(&c, buf, len));
        MBEDTLS_ASN1_CHK_ADD(len,
                             mbedtls_asn1_write_tag(
                                 &c, buf,
                                 MBEDTLS_ASN1_CONSTRUCTED | MBEDTLS_ASN1_SEQUENCE));
    }

    MBEDTLS_ASN1_CHK_ADD(len, mbedtls_asn1_write_len(&c, buf, len));
    MBEDTLS_ASN1_CHK_ADD(len,
                         mbedtls_asn1_write_tag(
                             &c, buf,
                             MBEDTLS_ASN1_CONSTRUCTED | MBEDTLS_ASN1_CONTEXT_SPECIFIC));

    MBEDTLS_ASN1_CHK_ADD(pub_len, mbedtls_pk_write_pubkey_der(ctx->key,
                                                              buf, (size_t) (c - buf)));
    c -= pub_len;
    len += pub_len;

    /*
     *  Subject  ::=  Name
     */
    MBEDTLS_ASN1_CHK_ADD(len, mbedtls_x509_write_names(&c, buf,
                                                       ctx->subject));

    /*
     *  Version  ::=  INTEGER  {  v1(0), v2(1), v3(2)  }
     */
    MBEDTLS_ASN1_CHK_ADD(len, mbedtls_asn1_write_int(&c, buf, 0));

    MBEDTLS_ASN1_CHK_ADD(len, mbedtls_asn1_write_len(&c, buf, len));
    MBEDTLS_ASN1_CHK_ADD(len,
                         mbedtls_asn1_write_tag(
                             &c, buf,
                             MBEDTLS_ASN1_CONSTRUCTED | MBEDTLS_ASN1_SEQUENCE));

    /*
     * Sign the written CSR data into the sig buffer
     * Note: hash errors can happen only after an internal error
     */
#if defined(MBEDTLS_USE_PSA_CRYPTO)
    if (psa_hash_compute(hash_alg,
                         c,
                         len,
                         hash,
                         sizeof(hash),
                         &hash_len) != PSA_SUCCESS) {
        return MBEDTLS_ERR_PLATFORM_HW_ACCEL_FAILED;
    }
#else /* MBEDTLS_USE_PSA_CRYPTO */
    ret = mbedtls_md(mbedtls_md_info_from_type(ctx->md_alg), c, len, hash);
    if (ret != 0) {
        return ret;
    }
#endif
    if ((ret = mbedtls_pk_sign(ctx->key, ctx->md_alg, hash, 0,
                               sig, sig_size, &sig_len,
                               f_rng, p_rng)) != 0) {
        return ret;
    }

    if (mbedtls_pk_can_do(ctx->key, MBEDTLS_PK_RSA)) {
        pk_alg = MBEDTLS_PK_RSA;
    } else if (mbedtls_pk_can_do(ctx->key, MBEDTLS_PK_ECDSA)) {
        pk_alg = MBEDTLS_PK_ECDSA;
    } else {
        return MBEDTLS_ERR_X509_INVALID_ALG;
    }

    if ((ret = mbedtls_oid_get_oid_by_sig_alg(pk_alg, ctx->md_alg,
                                              &sig_oid, &sig_oid_len)) != 0) {
        return ret;
    }

    /*
     * Move the written CSR data to the start of buf to create space for
     * writing the signature into buf.
     */
    memmove(buf, c, len);

    /*
     * Write sig and its OID into buf backwards from the end of buf.
     * Note: mbedtls_x509_write_sig will check for c2 - ( buf + len ) < sig_len
     * and return MBEDTLS_ERR_ASN1_BUF_TOO_SMALL if needed.
     */
    c2 = buf + size;
    MBEDTLS_ASN1_CHK_ADD(sig_and_oid_len,
                         mbedtls_x509_write_sig(&c2, buf + len, sig_oid, sig_oid_len,
                                                sig, sig_len, pk_alg));

    /*
     * Compact the space between the CSR data and signature by moving the
     * CSR data to the start of the signature.
     */
    c2 -= len;
    memmove(c2, buf, len);

    /* ASN encode the total size and tag the CSR data with it. */
    len += sig_and_oid_len;
    MBEDTLS_ASN1_CHK_ADD(len, mbedtls_asn1_write_len(&c2, buf, len));
    MBEDTLS_ASN1_CHK_ADD(len,
                         mbedtls_asn1_write_tag(
                             &c2, buf,
                             MBEDTLS_ASN1_CONSTRUCTED | MBEDTLS_ASN1_SEQUENCE));

    /* Zero the unused bytes at the start of buf */
    memset(buf, 0, (size_t) (c2 - buf));

    return (int) len;
}

int mbedtls_x509write_csr_der(mbedtls_x509write_csr *ctx, unsigned char *buf,
                              size_t size,
                              int (*f_rng)(void *, unsigned char *, size_t),
                              void *p_rng)
{
    int ret;
    unsigned char *sig;

    if ((sig = mbedtls_calloc(1, MBEDTLS_PK_SIGNATURE_MAX_SIZE)) == NULL) {
        return MBEDTLS_ERR_X509_ALLOC_FAILED;
    }

    ret = x509write_csr_der_internal(ctx, buf, size,
                                     sig, MBEDTLS_PK_SIGNATURE_MAX_SIZE,
                                     f_rng, p_rng);

    mbedtls_free(sig);

    return ret;
}

#define PEM_BEGIN_CSR           "-----BEGIN CERTIFICATE REQUEST-----\n"
#define PEM_END_CSR             "-----END CERTIFICATE REQUEST-----\n"

#if defined(MBEDTLS_PEM_WRITE_C)
int mbedtls_x509write_csr_pem(mbedtls_x509write_csr *ctx, unsigned char *buf, size_t size,
                              int (*f_rng)(void *, unsigned char *, size_t),
                              void *p_rng)
{
    int ret = MBEDTLS_ERR_ERROR_CORRUPTION_DETECTED;
    size_t olen = 0;

    if ((ret = mbedtls_x509write_csr_der(ctx, buf, size,
                                         f_rng, p_rng)) < 0) {
        return ret;
    }

    if ((ret = mbedtls_pem_write_buffer(PEM_BEGIN_CSR, PEM_END_CSR,
                                        buf + size - ret,
                                        ret, buf, size, &olen)) != 0) {
        return ret;
    }

    return 0;
}
#endif /* MBEDTLS_PEM_WRITE_C */

#endif /* MBEDTLS_X509_CSR_WRITE_C */

Coverage Report

Created: 2026-10-17 06:10

Line	Count	Source
1		/*
2		* X.509 Certificate Signing Request writing
3		*
4		* Copyright The Mbed TLS Contributors
5		* SPDX-License-Identifier: Apache-2.0 OR GPL-2.0-or-later
6		*/
7		/*
8		* References:
9		* - CSRs: PKCS#10 v1.7 aka RFC 2986
10		* - attributes: PKCS#9 v2.0 aka RFC 2985
11		*/
12
13		#include "common.h"
14
15		#if defined(MBEDTLS_X509_CSR_WRITE_C)
16
17		#include "x509_internal.h"
18		#include "mbedtls/x509_csr.h"
19		#include "mbedtls/asn1write.h"
20		#include "mbedtls/error.h"
21		#include "mbedtls/oid.h"
22		#include "mbedtls/platform_util.h"
23
24		#if defined(MBEDTLS_USE_PSA_CRYPTO)
25		#include "psa/crypto.h"
26		#include "psa_util_internal.h"
27		#include "mbedtls/psa_util.h"
28		#endif /* MBEDTLS_USE_PSA_CRYPTO */
29
30		#include <string.h>
31		#include <stdlib.h>
32
33		#if defined(MBEDTLS_PEM_WRITE_C)
34		#include "mbedtls/pem.h"
35		#endif
36
37		#include "mbedtls/platform.h"
38
39		void mbedtls_x509write_csr_init(mbedtls_x509write_csr *ctx)
40	0	{
41	0	memset(ctx, 0, sizeof(mbedtls_x509write_csr));
42	0	}
43
44		void mbedtls_x509write_csr_free(mbedtls_x509write_csr *ctx)
45	0	{
46	0	if (ctx == NULL) {
47	0	return;
48	0	}
49
50	0	mbedtls_asn1_free_named_data_list(&ctx->subject);
51	0	mbedtls_asn1_free_named_data_list(&ctx->extensions);
52
53	0	mbedtls_platform_zeroize(ctx, sizeof(mbedtls_x509write_csr));
54	0	}
55
56		void mbedtls_x509write_csr_set_md_alg(mbedtls_x509write_csr *ctx, mbedtls_md_type_t md_alg)
57	0	{
58	0	ctx->md_alg = md_alg;
59	0	}
60
61		void mbedtls_x509write_csr_set_key(mbedtls_x509write_csr ctx, mbedtls_pk_context key)
62	0	{
63	0	ctx->key = key;
64	0	}
65
66		int mbedtls_x509write_csr_set_subject_name(mbedtls_x509write_csr *ctx,
67		const char *subject_name)
68	0	{
69	0	mbedtls_asn1_free_named_data_list(&ctx->subject);
70	0	return mbedtls_x509_string_to_names(&ctx->subject, subject_name);
71	0	}
72
73		int mbedtls_x509write_csr_set_extension(mbedtls_x509write_csr *ctx,
74		const char *oid, size_t oid_len,
75		int critical,
76		const unsigned char *val, size_t val_len)
77	0	{
78	0	return mbedtls_x509_set_extension(&ctx->extensions, oid, oid_len,
79	0	critical, val, val_len);
80	0	}
81
82		int mbedtls_x509write_csr_set_subject_alternative_name(mbedtls_x509write_csr *ctx,
83		const mbedtls_x509_san_list *san_list)
84	0	{
85	0	return mbedtls_x509_write_set_san_common(&ctx->extensions, san_list);
86	0	}
87
88		int mbedtls_x509write_csr_set_key_usage(mbedtls_x509write_csr *ctx, unsigned char key_usage)
89	0	{
90	0	unsigned char buf[4] = { 0 };
91	0	unsigned char *c;
92	0	int ret = MBEDTLS_ERR_ERROR_CORRUPTION_DETECTED;
93
94	0	c = buf + 4;
95
96	0	ret = mbedtls_asn1_write_named_bitstring(&c, buf, &key_usage, 8);
97	0	if (ret < 3 \|\| ret > 4) {
98	0	return ret;
99	0	}
100
101	0	ret = mbedtls_x509write_csr_set_extension(ctx, MBEDTLS_OID_KEY_USAGE,
102	0	MBEDTLS_OID_SIZE(MBEDTLS_OID_KEY_USAGE),
103	0	0, c, (size_t) ret);
104	0	if (ret != 0) {
105	0	return ret;
106	0	}
107
108	0	return 0;
109	0	}
110
111		int mbedtls_x509write_csr_set_ns_cert_type(mbedtls_x509write_csr *ctx,
112		unsigned char ns_cert_type)
113	0	{
114	0	unsigned char buf[4] = { 0 };
115	0	unsigned char *c;
116	0	int ret = MBEDTLS_ERR_ERROR_CORRUPTION_DETECTED;
117
118	0	c = buf + 4;
119
120	0	ret = mbedtls_asn1_write_named_bitstring(&c, buf, &ns_cert_type, 8);
121	0	if (ret < 3 \|\| ret > 4) {
122	0	return ret;
123	0	}
124
125	0	ret = mbedtls_x509write_csr_set_extension(ctx, MBEDTLS_OID_NS_CERT_TYPE,
126	0	MBEDTLS_OID_SIZE(MBEDTLS_OID_NS_CERT_TYPE),
127	0	0, c, (size_t) ret);
128	0	if (ret != 0) {
129	0	return ret;
130	0	}
131
132	0	return 0;
133	0	}
134
135		static int x509write_csr_der_internal(mbedtls_x509write_csr *ctx,
136		unsigned char *buf,
137		size_t size,
138		unsigned char *sig, size_t sig_size,
139		int (f_rng)(void , unsigned char *, size_t),
140		void *p_rng)
141	0	{
142	0	int ret = MBEDTLS_ERR_ERROR_CORRUPTION_DETECTED;
143	0	const char *sig_oid;
144	0	size_t sig_oid_len = 0;
145	0	unsigned char c, c2;
146	0	unsigned char hash[MBEDTLS_MD_MAX_SIZE];
147	0	size_t pub_len = 0, sig_and_oid_len = 0, sig_len;
148	0	size_t len = 0;
149	0	mbedtls_pk_type_t pk_alg;
150		#if defined(MBEDTLS_USE_PSA_CRYPTO)
151		size_t hash_len;
152		psa_algorithm_t hash_alg = mbedtls_md_psa_alg_from_type(ctx->md_alg);
153		#endif /* MBEDTLS_USE_PSA_CRYPTO */
154
155		/* Write the CSR backwards starting from the end of buf */
156	0	c = buf + size;
157
158	0	MBEDTLS_ASN1_CHK_ADD(len, mbedtls_x509_write_extensions(&c, buf,
159	0	ctx->extensions));
160
161	0	if (len) {
162	0	MBEDTLS_ASN1_CHK_ADD(len, mbedtls_asn1_write_len(&c, buf, len));
163	0	MBEDTLS_ASN1_CHK_ADD(len,
164	0	mbedtls_asn1_write_tag(
165	0	&c, buf,
166	0	MBEDTLS_ASN1_CONSTRUCTED \| MBEDTLS_ASN1_SEQUENCE));
167
168	0	MBEDTLS_ASN1_CHK_ADD(len, mbedtls_asn1_write_len(&c, buf, len));
169	0	MBEDTLS_ASN1_CHK_ADD(len,
170	0	mbedtls_asn1_write_tag(
171	0	&c, buf,
172	0	MBEDTLS_ASN1_CONSTRUCTED \| MBEDTLS_ASN1_SET));
173
174	0	MBEDTLS_ASN1_CHK_ADD(len,
175	0	mbedtls_asn1_write_oid(
176	0	&c, buf, MBEDTLS_OID_PKCS9_CSR_EXT_REQ,
177	0	MBEDTLS_OID_SIZE(MBEDTLS_OID_PKCS9_CSR_EXT_REQ)));
178
179	0	MBEDTLS_ASN1_CHK_ADD(len, mbedtls_asn1_write_len(&c, buf, len));
180	0	MBEDTLS_ASN1_CHK_ADD(len,
181	0	mbedtls_asn1_write_tag(
182	0	&c, buf,
183	0	MBEDTLS_ASN1_CONSTRUCTED \| MBEDTLS_ASN1_SEQUENCE));
184	0	}
185
186	0	MBEDTLS_ASN1_CHK_ADD(len, mbedtls_asn1_write_len(&c, buf, len));
187	0	MBEDTLS_ASN1_CHK_ADD(len,
188	0	mbedtls_asn1_write_tag(
189	0	&c, buf,
190	0	MBEDTLS_ASN1_CONSTRUCTED \| MBEDTLS_ASN1_CONTEXT_SPECIFIC));
191
192	0	MBEDTLS_ASN1_CHK_ADD(pub_len, mbedtls_pk_write_pubkey_der(ctx->key,
193	0	buf, (size_t) (c - buf)));
194	0	c -= pub_len;
195	0	len += pub_len;
196
197		/*
198		* Subject ::= Name
199		*/
200	0	MBEDTLS_ASN1_CHK_ADD(len, mbedtls_x509_write_names(&c, buf,
201	0	ctx->subject));
202
203		/*
204		* Version ::= INTEGER { v1(0), v2(1), v3(2) }
205		*/
206	0	MBEDTLS_ASN1_CHK_ADD(len, mbedtls_asn1_write_int(&c, buf, 0));
207
208	0	MBEDTLS_ASN1_CHK_ADD(len, mbedtls_asn1_write_len(&c, buf, len));
209	0	MBEDTLS_ASN1_CHK_ADD(len,
210	0	mbedtls_asn1_write_tag(
211	0	&c, buf,
212	0	MBEDTLS_ASN1_CONSTRUCTED \| MBEDTLS_ASN1_SEQUENCE));
213
214		/*
215		* Sign the written CSR data into the sig buffer
216		* Note: hash errors can happen only after an internal error
217		*/
218		#if defined(MBEDTLS_USE_PSA_CRYPTO)
219		if (psa_hash_compute(hash_alg,
220		c,
221		len,
222		hash,
223		sizeof(hash),
224		&hash_len) != PSA_SUCCESS) {
225		return MBEDTLS_ERR_PLATFORM_HW_ACCEL_FAILED;
226		}
227		#else /* MBEDTLS_USE_PSA_CRYPTO */
228	0	ret = mbedtls_md(mbedtls_md_info_from_type(ctx->md_alg), c, len, hash);
229	0	if (ret != 0) {
230	0	return ret;
231	0	}
232	0	#endif
233	0	if ((ret = mbedtls_pk_sign(ctx->key, ctx->md_alg, hash, 0,
234	0	sig, sig_size, &sig_len,
235	0	f_rng, p_rng)) != 0) {
236	0	return ret;
237	0	}
238
239	0	if (mbedtls_pk_can_do(ctx->key, MBEDTLS_PK_RSA)) {
240	0	pk_alg = MBEDTLS_PK_RSA;
241	0	} else if (mbedtls_pk_can_do(ctx->key, MBEDTLS_PK_ECDSA)) {
242	0	pk_alg = MBEDTLS_PK_ECDSA;
243	0	} else {
244	0	return MBEDTLS_ERR_X509_INVALID_ALG;
245	0	}
246
247	0	if ((ret = mbedtls_oid_get_oid_by_sig_alg(pk_alg, ctx->md_alg,
248	0	&sig_oid, &sig_oid_len)) != 0) {
249	0	return ret;
250	0	}
251
252		/*
253		* Move the written CSR data to the start of buf to create space for
254		* writing the signature into buf.
255		*/
256	0	memmove(buf, c, len);
257
258		/*
259		* Write sig and its OID into buf backwards from the end of buf.
260		* Note: mbedtls_x509_write_sig will check for c2 - ( buf + len ) < sig_len
261		* and return MBEDTLS_ERR_ASN1_BUF_TOO_SMALL if needed.
262		*/
263	0	c2 = buf + size;
264	0	MBEDTLS_ASN1_CHK_ADD(sig_and_oid_len,
265	0	mbedtls_x509_write_sig(&c2, buf + len, sig_oid, sig_oid_len,
266	0	sig, sig_len, pk_alg));
267
268		/*
269		* Compact the space between the CSR data and signature by moving the
270		* CSR data to the start of the signature.
271		*/
272	0	c2 -= len;
273	0	memmove(c2, buf, len);
274
275		/* ASN encode the total size and tag the CSR data with it. */
276	0	len += sig_and_oid_len;
277	0	MBEDTLS_ASN1_CHK_ADD(len, mbedtls_asn1_write_len(&c2, buf, len));
278	0	MBEDTLS_ASN1_CHK_ADD(len,
279	0	mbedtls_asn1_write_tag(
280	0	&c2, buf,
281	0	MBEDTLS_ASN1_CONSTRUCTED \| MBEDTLS_ASN1_SEQUENCE));
282
283		/* Zero the unused bytes at the start of buf */
284	0	memset(buf, 0, (size_t) (c2 - buf));
285
286	0	return (int) len;
287	0	}
288
289		int mbedtls_x509write_csr_der(mbedtls_x509write_csr ctx, unsigned char buf,
290		size_t size,
291		int (f_rng)(void , unsigned char *, size_t),
292		void *p_rng)
293	0	{
294	0	int ret;
295	0	unsigned char *sig;
296
297	0	if ((sig = mbedtls_calloc(1, MBEDTLS_PK_SIGNATURE_MAX_SIZE)) == NULL) {
298	0	return MBEDTLS_ERR_X509_ALLOC_FAILED;
299	0	}
300
301	0	ret = x509write_csr_der_internal(ctx, buf, size,
302	0	sig, MBEDTLS_PK_SIGNATURE_MAX_SIZE,
303	0	f_rng, p_rng);
304
305	0	mbedtls_free(sig);
306
307	0	return ret;
308	0	}
309
310	0	#define PEM_BEGIN_CSR "-----BEGIN CERTIFICATE REQUEST-----\n"
311	0	#define PEM_END_CSR "-----END CERTIFICATE REQUEST-----\n"
312
313		#if defined(MBEDTLS_PEM_WRITE_C)
314		int mbedtls_x509write_csr_pem(mbedtls_x509write_csr ctx, unsigned char buf, size_t size,
315		int (f_rng)(void , unsigned char *, size_t),
316		void *p_rng)
317	0	{
318	0	int ret = MBEDTLS_ERR_ERROR_CORRUPTION_DETECTED;
319	0	size_t olen = 0;
320
321	0	if ((ret = mbedtls_x509write_csr_der(ctx, buf, size,
322	0	f_rng, p_rng)) < 0) {
323	0	return ret;
324	0	}
325
326	0	if ((ret = mbedtls_pem_write_buffer(PEM_BEGIN_CSR, PEM_END_CSR,
327	0	buf + size - ret,
328	0	ret, buf, size, &olen)) != 0) {
329	0	return ret;
330	0	}
331
332	0	return 0;
333	0	}
334		#endif /* MBEDTLS_PEM_WRITE_C */
335
336		#endif /* MBEDTLS_X509_CSR_WRITE_C */