491 lines
14 KiB
C
491 lines
14 KiB
C
/*
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* ASN.1 buffer writing functionality
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*
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* Copyright The Mbed TLS Contributors
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* SPDX-License-Identifier: Apache-2.0
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*
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* Licensed under the Apache License, Version 2.0 (the "License"); you may
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* not use this file except in compliance with the License.
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* You may obtain a copy of the License at
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*
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* http://www.apache.org/licenses/LICENSE-2.0
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*
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* Unless required by applicable law or agreed to in writing, software
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* distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
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* WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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* See the License for the specific language governing permissions and
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* limitations under the License.
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*/
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#include "common.h"
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#if defined(MBEDTLS_ASN1_WRITE_C)
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#include "mbedtls/asn1write.h"
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#include "mbedtls/error.h"
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#include <string.h>
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#include "mbedtls/platform.h"
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int mbedtls_asn1_write_len(unsigned char **p, unsigned char *start, size_t len)
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{
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if (len < 0x80) {
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if (*p - start < 1) {
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return MBEDTLS_ERR_ASN1_BUF_TOO_SMALL;
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}
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*--(*p) = (unsigned char) len;
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return 1;
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}
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if (len <= 0xFF) {
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if (*p - start < 2) {
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return MBEDTLS_ERR_ASN1_BUF_TOO_SMALL;
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}
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*--(*p) = (unsigned char) len;
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*--(*p) = 0x81;
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return 2;
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}
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if (len <= 0xFFFF) {
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if (*p - start < 3) {
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return MBEDTLS_ERR_ASN1_BUF_TOO_SMALL;
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}
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*--(*p) = MBEDTLS_BYTE_0(len);
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*--(*p) = MBEDTLS_BYTE_1(len);
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*--(*p) = 0x82;
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return 3;
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}
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if (len <= 0xFFFFFF) {
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if (*p - start < 4) {
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return MBEDTLS_ERR_ASN1_BUF_TOO_SMALL;
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}
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*--(*p) = MBEDTLS_BYTE_0(len);
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*--(*p) = MBEDTLS_BYTE_1(len);
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*--(*p) = MBEDTLS_BYTE_2(len);
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*--(*p) = 0x83;
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return 4;
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}
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int len_is_valid = 1;
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#if SIZE_MAX > 0xFFFFFFFF
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len_is_valid = (len <= 0xFFFFFFFF);
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#endif
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if (len_is_valid) {
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if (*p - start < 5) {
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return MBEDTLS_ERR_ASN1_BUF_TOO_SMALL;
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}
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*--(*p) = MBEDTLS_BYTE_0(len);
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*--(*p) = MBEDTLS_BYTE_1(len);
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*--(*p) = MBEDTLS_BYTE_2(len);
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*--(*p) = MBEDTLS_BYTE_3(len);
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*--(*p) = 0x84;
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return 5;
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}
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return MBEDTLS_ERR_ASN1_INVALID_LENGTH;
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}
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int mbedtls_asn1_write_tag(unsigned char **p, unsigned char *start, unsigned char tag)
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{
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if (*p - start < 1) {
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return MBEDTLS_ERR_ASN1_BUF_TOO_SMALL;
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}
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*--(*p) = tag;
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return 1;
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}
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int mbedtls_asn1_write_raw_buffer(unsigned char **p, unsigned char *start,
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const unsigned char *buf, size_t size)
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{
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size_t len = 0;
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if (*p < start || (size_t) (*p - start) < size) {
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return MBEDTLS_ERR_ASN1_BUF_TOO_SMALL;
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}
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len = size;
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(*p) -= len;
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memcpy(*p, buf, len);
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return (int) len;
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}
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#if defined(MBEDTLS_BIGNUM_C)
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int mbedtls_asn1_write_mpi(unsigned char **p, unsigned char *start, const mbedtls_mpi *X)
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{
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int ret = MBEDTLS_ERR_ERROR_CORRUPTION_DETECTED;
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size_t len = 0;
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// Write the MPI
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//
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len = mbedtls_mpi_size(X);
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/* DER represents 0 with a sign bit (0=nonnegative) and 7 value bits, not
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* as 0 digits. We need to end up with 020100, not with 0200. */
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if (len == 0) {
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len = 1;
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}
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if (*p < start || (size_t) (*p - start) < len) {
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return MBEDTLS_ERR_ASN1_BUF_TOO_SMALL;
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}
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(*p) -= len;
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MBEDTLS_MPI_CHK(mbedtls_mpi_write_binary(X, *p, len));
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// DER format assumes 2s complement for numbers, so the leftmost bit
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// should be 0 for positive numbers and 1 for negative numbers.
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//
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if (X->s == 1 && **p & 0x80) {
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if (*p - start < 1) {
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return MBEDTLS_ERR_ASN1_BUF_TOO_SMALL;
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}
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*--(*p) = 0x00;
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len += 1;
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}
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MBEDTLS_ASN1_CHK_ADD(len, mbedtls_asn1_write_len(p, start, len));
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MBEDTLS_ASN1_CHK_ADD(len, mbedtls_asn1_write_tag(p, start, MBEDTLS_ASN1_INTEGER));
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ret = (int) len;
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cleanup:
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return ret;
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}
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#endif /* MBEDTLS_BIGNUM_C */
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int mbedtls_asn1_write_null(unsigned char **p, unsigned char *start)
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{
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int ret = MBEDTLS_ERR_ERROR_CORRUPTION_DETECTED;
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size_t len = 0;
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// Write NULL
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//
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MBEDTLS_ASN1_CHK_ADD(len, mbedtls_asn1_write_len(p, start, 0));
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MBEDTLS_ASN1_CHK_ADD(len, mbedtls_asn1_write_tag(p, start, MBEDTLS_ASN1_NULL));
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return (int) len;
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}
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int mbedtls_asn1_write_oid(unsigned char **p, unsigned char *start,
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const char *oid, size_t oid_len)
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{
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int ret = MBEDTLS_ERR_ERROR_CORRUPTION_DETECTED;
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size_t len = 0;
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MBEDTLS_ASN1_CHK_ADD(len, mbedtls_asn1_write_raw_buffer(p, start,
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(const unsigned char *) oid, oid_len));
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MBEDTLS_ASN1_CHK_ADD(len, mbedtls_asn1_write_len(p, start, len));
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MBEDTLS_ASN1_CHK_ADD(len, mbedtls_asn1_write_tag(p, start, MBEDTLS_ASN1_OID));
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return (int) len;
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}
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int mbedtls_asn1_write_algorithm_identifier(unsigned char **p, unsigned char *start,
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const char *oid, size_t oid_len,
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size_t par_len)
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{
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return mbedtls_asn1_write_algorithm_identifier_ext(p, start, oid, oid_len, par_len, 1);
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}
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int mbedtls_asn1_write_algorithm_identifier_ext(unsigned char **p, unsigned char *start,
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const char *oid, size_t oid_len,
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size_t par_len, int has_par)
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{
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int ret = MBEDTLS_ERR_ERROR_CORRUPTION_DETECTED;
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size_t len = 0;
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if (has_par) {
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if (par_len == 0) {
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MBEDTLS_ASN1_CHK_ADD(len, mbedtls_asn1_write_null(p, start));
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} else {
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len += par_len;
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}
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}
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MBEDTLS_ASN1_CHK_ADD(len, mbedtls_asn1_write_oid(p, start, oid, oid_len));
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MBEDTLS_ASN1_CHK_ADD(len, mbedtls_asn1_write_len(p, start, len));
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MBEDTLS_ASN1_CHK_ADD(len, mbedtls_asn1_write_tag(p, start,
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MBEDTLS_ASN1_CONSTRUCTED |
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MBEDTLS_ASN1_SEQUENCE));
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return (int) len;
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}
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int mbedtls_asn1_write_bool(unsigned char **p, unsigned char *start, int boolean)
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{
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int ret = MBEDTLS_ERR_ERROR_CORRUPTION_DETECTED;
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size_t len = 0;
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if (*p - start < 1) {
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return MBEDTLS_ERR_ASN1_BUF_TOO_SMALL;
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}
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*--(*p) = (boolean) ? 255 : 0;
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len++;
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MBEDTLS_ASN1_CHK_ADD(len, mbedtls_asn1_write_len(p, start, len));
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MBEDTLS_ASN1_CHK_ADD(len, mbedtls_asn1_write_tag(p, start, MBEDTLS_ASN1_BOOLEAN));
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return (int) len;
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}
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static int asn1_write_tagged_int(unsigned char **p, unsigned char *start, int val, int tag)
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{
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int ret = MBEDTLS_ERR_ERROR_CORRUPTION_DETECTED;
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size_t len = 0;
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do {
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if (*p - start < 1) {
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return MBEDTLS_ERR_ASN1_BUF_TOO_SMALL;
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}
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len += 1;
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*--(*p) = val & 0xff;
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val >>= 8;
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} while (val > 0);
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if (**p & 0x80) {
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if (*p - start < 1) {
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return MBEDTLS_ERR_ASN1_BUF_TOO_SMALL;
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}
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*--(*p) = 0x00;
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len += 1;
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}
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MBEDTLS_ASN1_CHK_ADD(len, mbedtls_asn1_write_len(p, start, len));
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MBEDTLS_ASN1_CHK_ADD(len, mbedtls_asn1_write_tag(p, start, tag));
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return (int) len;
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}
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int mbedtls_asn1_write_int(unsigned char **p, unsigned char *start, int val)
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{
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return asn1_write_tagged_int(p, start, val, MBEDTLS_ASN1_INTEGER);
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}
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int mbedtls_asn1_write_enum(unsigned char **p, unsigned char *start, int val)
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{
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return asn1_write_tagged_int(p, start, val, MBEDTLS_ASN1_ENUMERATED);
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}
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int mbedtls_asn1_write_tagged_string(unsigned char **p, unsigned char *start, int tag,
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const char *text, size_t text_len)
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{
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int ret = MBEDTLS_ERR_ERROR_CORRUPTION_DETECTED;
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size_t len = 0;
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MBEDTLS_ASN1_CHK_ADD(len, mbedtls_asn1_write_raw_buffer(p, start,
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(const unsigned char *) text,
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text_len));
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MBEDTLS_ASN1_CHK_ADD(len, mbedtls_asn1_write_len(p, start, len));
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MBEDTLS_ASN1_CHK_ADD(len, mbedtls_asn1_write_tag(p, start, tag));
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return (int) len;
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}
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int mbedtls_asn1_write_utf8_string(unsigned char **p, unsigned char *start,
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const char *text, size_t text_len)
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{
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return mbedtls_asn1_write_tagged_string(p, start, MBEDTLS_ASN1_UTF8_STRING, text, text_len);
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}
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int mbedtls_asn1_write_printable_string(unsigned char **p, unsigned char *start,
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const char *text, size_t text_len)
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{
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return mbedtls_asn1_write_tagged_string(p, start, MBEDTLS_ASN1_PRINTABLE_STRING, text,
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text_len);
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}
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int mbedtls_asn1_write_ia5_string(unsigned char **p, unsigned char *start,
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const char *text, size_t text_len)
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{
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return mbedtls_asn1_write_tagged_string(p, start, MBEDTLS_ASN1_IA5_STRING, text, text_len);
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}
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int mbedtls_asn1_write_named_bitstring(unsigned char **p,
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unsigned char *start,
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const unsigned char *buf,
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size_t bits)
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{
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size_t unused_bits, byte_len;
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const unsigned char *cur_byte;
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unsigned char cur_byte_shifted;
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unsigned char bit;
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byte_len = (bits + 7) / 8;
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unused_bits = (byte_len * 8) - bits;
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/*
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* Named bitstrings require that trailing 0s are excluded in the encoding
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* of the bitstring. Trailing 0s are considered part of the 'unused' bits
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* when encoding this value in the first content octet
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*/
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if (bits != 0) {
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cur_byte = buf + byte_len - 1;
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cur_byte_shifted = *cur_byte >> unused_bits;
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for (;;) {
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bit = cur_byte_shifted & 0x1;
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cur_byte_shifted >>= 1;
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if (bit != 0) {
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break;
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}
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bits--;
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if (bits == 0) {
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break;
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}
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if (bits % 8 == 0) {
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cur_byte_shifted = *--cur_byte;
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}
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}
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}
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return mbedtls_asn1_write_bitstring(p, start, buf, bits);
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}
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int mbedtls_asn1_write_bitstring(unsigned char **p, unsigned char *start,
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const unsigned char *buf, size_t bits)
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{
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int ret = MBEDTLS_ERR_ERROR_CORRUPTION_DETECTED;
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size_t len = 0;
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size_t unused_bits, byte_len;
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byte_len = (bits + 7) / 8;
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unused_bits = (byte_len * 8) - bits;
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if (*p < start || (size_t) (*p - start) < byte_len + 1) {
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return MBEDTLS_ERR_ASN1_BUF_TOO_SMALL;
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}
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len = byte_len + 1;
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/* Write the bitstring. Ensure the unused bits are zeroed */
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if (byte_len > 0) {
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byte_len--;
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*--(*p) = buf[byte_len] & ~((0x1 << unused_bits) - 1);
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(*p) -= byte_len;
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memcpy(*p, buf, byte_len);
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}
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/* Write unused bits */
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*--(*p) = (unsigned char) unused_bits;
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MBEDTLS_ASN1_CHK_ADD(len, mbedtls_asn1_write_len(p, start, len));
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MBEDTLS_ASN1_CHK_ADD(len, mbedtls_asn1_write_tag(p, start, MBEDTLS_ASN1_BIT_STRING));
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return (int) len;
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}
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int mbedtls_asn1_write_octet_string(unsigned char **p, unsigned char *start,
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const unsigned char *buf, size_t size)
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{
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int ret = MBEDTLS_ERR_ERROR_CORRUPTION_DETECTED;
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size_t len = 0;
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MBEDTLS_ASN1_CHK_ADD(len, mbedtls_asn1_write_raw_buffer(p, start, buf, size));
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MBEDTLS_ASN1_CHK_ADD(len, mbedtls_asn1_write_len(p, start, len));
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MBEDTLS_ASN1_CHK_ADD(len, mbedtls_asn1_write_tag(p, start, MBEDTLS_ASN1_OCTET_STRING));
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return (int) len;
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}
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/* This is a copy of the ASN.1 parsing function mbedtls_asn1_find_named_data(),
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* which is replicated to avoid a dependency ASN1_WRITE_C on ASN1_PARSE_C. */
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static mbedtls_asn1_named_data *asn1_find_named_data(
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mbedtls_asn1_named_data *list,
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const char *oid, size_t len)
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{
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while (list != NULL) {
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if (list->oid.len == len &&
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memcmp(list->oid.p, oid, len) == 0) {
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break;
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}
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list = list->next;
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}
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return list;
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}
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mbedtls_asn1_named_data *mbedtls_asn1_store_named_data(
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mbedtls_asn1_named_data **head,
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const char *oid, size_t oid_len,
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const unsigned char *val,
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size_t val_len)
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{
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mbedtls_asn1_named_data *cur;
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if ((cur = asn1_find_named_data(*head, oid, oid_len)) == NULL) {
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// Add new entry if not present yet based on OID
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//
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cur = (mbedtls_asn1_named_data *) mbedtls_calloc(1,
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sizeof(mbedtls_asn1_named_data));
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if (cur == NULL) {
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return NULL;
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}
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cur->oid.len = oid_len;
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cur->oid.p = mbedtls_calloc(1, oid_len);
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if (cur->oid.p == NULL) {
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mbedtls_free(cur);
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return NULL;
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}
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memcpy(cur->oid.p, oid, oid_len);
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cur->val.len = val_len;
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if (val_len != 0) {
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cur->val.p = mbedtls_calloc(1, val_len);
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if (cur->val.p == NULL) {
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mbedtls_free(cur->oid.p);
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mbedtls_free(cur);
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return NULL;
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}
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}
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cur->next = *head;
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*head = cur;
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} else if (val_len == 0) {
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mbedtls_free(cur->val.p);
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cur->val.p = NULL;
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} else if (cur->val.len != val_len) {
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/*
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* Enlarge existing value buffer if needed
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* Preserve old data until the allocation succeeded, to leave list in
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* a consistent state in case allocation fails.
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*/
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void *p = mbedtls_calloc(1, val_len);
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if (p == NULL) {
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return NULL;
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}
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mbedtls_free(cur->val.p);
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cur->val.p = p;
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cur->val.len = val_len;
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}
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if (val != NULL && val_len != 0) {
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memcpy(cur->val.p, val, val_len);
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}
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return cur;
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}
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#endif /* MBEDTLS_ASN1_WRITE_C */
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