/*
 * ASN.1 buffer writing functionality
 *
 *  Copyright (C) 2006-2015, ARM Limited, All Rights Reserved
 *  SPDX-License-Identifier: Apache-2.0
 *
 *  Licensed under the Apache License, Version 2.0 (the "License"); you may
 *  not use this file except in compliance with the License.
 *  You may obtain a copy of the License at
 *
 *  http://www.apache.org/licenses/LICENSE-2.0
 *
 *  Unless required by applicable law or agreed to in writing, software
 *  distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
 *  WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 *  See the License for the specific language governing permissions and
 *  limitations under the License.
 *
 *  This file is part of mbed TLS (https://tls.mbed.org)
 */

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

#if defined(MBEDTLS_ASN1_WRITE_C)

#include "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 (len <= 0xFFFFFFFF) {
    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);
  }

  return (MBEDTLS_ERR_ASN1_INVALID_LENGTH);
}

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;

  // TODO negative values and values larger than 128
  // DER format assumes 2s complement for numbers, so the leftmost bit
  // should be 0 for positive numbers and 1 for negative numbers.
  //
  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 */