// Copyright 1995-2016 The OpenSSL Project Authors. All Rights Reserved.

//

// 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

//

//     https://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.

#include <openssl/asn1.h>

#include <limits.h>

#include <string.h>

#include <openssl/bytestring.h>

#include <openssl/err.h>

#include <openssl/mem.h>

#include <openssl/span.h>

#include "../internal.h"

#include "internal.h"

using namespace bssl;

int ASN1_BIT_STRING_set(ASN1_BIT_STRING *x, const unsigned char *d,

                        ossl_ssize_t len) {

  return ASN1_STRING_set(x, d, len);

}

int bssl::asn1_bit_string_length(const ASN1_BIT_STRING *str,

                                 uint8_t *out_padding_bits) {

  int len = str->length;

  if (str->flags & ASN1_STRING_FLAG_BITS_LEFT) {

    // If the string is already empty, it cannot have padding bits.

    *out_padding_bits = len == 0 ? 0 : str->flags & 0x07;

    return len;

  }

  // TODO(https://crbug.com/boringssl/447): If we move this logic to

  // |ASN1_BIT_STRING_set_bit|, can we remove this representation?

  while (len > 0 && str->data[len - 1] == 0) {

    len--;

  }

  uint8_t padding_bits = 0;

  if (len > 0) {

    uint8_t last = str->data[len - 1];

    assert(last != 0);

    for (; padding_bits < 7; padding_bits++) {

      if (last & (1 << padding_bits)) {

        break;

      }

    }

  }

  *out_padding_bits = padding_bits;

  return len;

}

int ASN1_BIT_STRING_num_bytes(const ASN1_BIT_STRING *str, size_t *out) {

  uint8_t padding_bits;

  int len = asn1_bit_string_length(str, &padding_bits);

  if (padding_bits != 0) {

    return 0;

  }

  *out = len;

  return 1;

}

int i2c_ASN1_BIT_STRING(const ASN1_BIT_STRING *a, unsigned char **pp) {

  if (a == nullptr) {

    return 0;

  }

  uint8_t bits;

  int len = asn1_bit_string_length(a, &bits);

  if (len > INT_MAX - 1) {

    OPENSSL_PUT_ERROR(ASN1, ERR_R_OVERFLOW);

    return 0;

  }

  int ret = 1 + len;

  if (pp == nullptr) {

    return ret;

  }

  uint8_t *p = *pp;

  *(p++) = bits;

  OPENSSL_memcpy(p, a->data, len);

  if (len > 0) {

    p[len - 1] &= (0xff << bits);

  }

  p += len;

  *pp = p;

  return ret;

}

int bssl::asn1_marshal_bit_string(CBB *out, const ASN1_BIT_STRING *in,

                                  CBS_ASN1_TAG tag) {

  int len = i2c_ASN1_BIT_STRING(in, nullptr);

  if (len <= 0) {

    return 0;

  }

  tag = tag == 0 ? CBS_ASN1_BITSTRING : tag;

  CBB child;

  uint8_t *ptr;

  return CBB_add_asn1(out, &child, tag) &&                         //

         CBB_add_space(&child, &ptr, static_cast<size_t>(len)) &&  //

         i2c_ASN1_BIT_STRING(in, &ptr) == len &&                   //

         CBB_flush(out);

}

static int asn1_parse_bit_string_contents(Span<const uint8_t> in,

                                          ASN1_BIT_STRING *out) {

  CBS cbs = in;

  uint8_t padding;

  if (!CBS_get_u8(&cbs, &padding)) {

    OPENSSL_PUT_ERROR(ASN1, ASN1_R_STRING_TOO_SHORT);

    return 0;

  }

  if (padding > 7) {

    OPENSSL_PUT_ERROR(ASN1, ASN1_R_INVALID_BIT_STRING_BITS_LEFT);

    return 0;

  }

  // Unused bits in a BIT STRING must be zero.

  uint8_t padding_mask = (1 << padding) - 1;

  if (padding != 0) {

    CBS copy = cbs;

    uint8_t last;

    if (!CBS_get_last_u8(&copy, &last) || (last & padding_mask) != 0) {

      OPENSSL_PUT_ERROR(ASN1, ASN1_R_INVALID_BIT_STRING_PADDING);

      return 0;

    }

  }

  if (!ASN1_STRING_set(out, CBS_data(&cbs), CBS_len(&cbs))) {

    return 0;

  }

  out->type = V_ASN1_BIT_STRING;

  // |ASN1_STRING_FLAG_BITS_LEFT| and the bottom 3 bits encode |padding|.

  out->flags &= ~0x07;

  out->flags |= ASN1_STRING_FLAG_BITS_LEFT | padding;

  return 1;

}

ASN1_BIT_STRING *c2i_ASN1_BIT_STRING(ASN1_BIT_STRING **a,

                                     const unsigned char **pp, long len) {

  if (len < 0) {

    OPENSSL_PUT_ERROR(ASN1, ASN1_R_STRING_TOO_SHORT);

    return nullptr;

  }

  ASN1_BIT_STRING *ret = nullptr;

  if (a == nullptr || *a == nullptr) {

    if ((ret = ASN1_BIT_STRING_new()) == nullptr) {

      return nullptr;

    }

  } else {

    ret = *a;

  }

  if (!asn1_parse_bit_string_contents(Span(*pp, len), ret)) {

    if (ret != nullptr && (a == nullptr || *a != ret)) {

      ASN1_BIT_STRING_free(ret);

    }

    return nullptr;

  }

  if (a != nullptr) {

    *a = ret;

  }

  *pp += len;

  return ret;

}

int bssl::asn1_parse_bit_string(CBS *cbs, ASN1_BIT_STRING *out,

                                CBS_ASN1_TAG tag) {

  tag = tag == 0 ? CBS_ASN1_BITSTRING : tag;

  CBS child;

  if (!CBS_get_asn1(cbs, &child, tag)) {

    OPENSSL_PUT_ERROR(ASN1, ASN1_R_DECODE_ERROR);

    return 0;

  }

  return asn1_parse_bit_string_contents(child, out);

}

int bssl::asn1_parse_bit_string_with_bad_length(CBS *cbs,

                                                ASN1_BIT_STRING *out) {

  CBS child;

  CBS_ASN1_TAG tag;

  size_t header_len;

  int indefinite;

  if (!CBS_get_any_ber_asn1_element(cbs, &child, &tag, &header_len,

                                    /*out_ber_found=*/nullptr,

                                    &indefinite) ||

      tag != CBS_ASN1_BITSTRING || indefinite ||  //

      !CBS_skip(&child, header_len)) {

    OPENSSL_PUT_ERROR(ASN1, ASN1_R_DECODE_ERROR);

    return 0;

  }

  return asn1_parse_bit_string_contents(child, out);

}

// These next 2 functions from Goetz Babin-Ebell <babinebell@trustcenter.de>

int ASN1_BIT_STRING_set_bit(ASN1_BIT_STRING *a, int n, int value) {

  int w, v, iv;

  unsigned char *c;

  w = n / 8;

  v = 1 << (7 - (n & 0x07));

  iv = ~v;

  if (!value) {

    v = 0;

  }

  if (a == nullptr) {

    return 0;

  }

  a->flags &= ~(ASN1_STRING_FLAG_BITS_LEFT | 0x07);  // clear, set on write

  if ((a->length < (w + 1)) || (a->data == nullptr)) {

    if (!value) {

      return 1;  // Don't need to set

    }

    if (a->data == nullptr) {

      c = (unsigned char *)OPENSSL_malloc(w + 1);

    } else {

      c = (unsigned char *)OPENSSL_realloc(a->data, w + 1);

    }

    if (c == nullptr) {

      return 0;

    }

    if (w + 1 - a->length > 0) {

      OPENSSL_memset(c + a->length, 0, w + 1 - a->length);

    }

    a->data = c;

    a->length = w + 1;

  }

  a->data[w] = ((a->data[w]) & iv) | v;

  while ((a->length > 0) && (a->data[a->length - 1] == 0)) {

    a->length--;

  }

  return 1;

}

int ASN1_BIT_STRING_get_bit(const ASN1_BIT_STRING *a, int n) {

  int w, v;

  w = n / 8;

  v = 1 << (7 - (n & 0x07));

  if ((a == nullptr) || (a->length < (w + 1)) || (a->data == nullptr)) {

    return 0;

  }

  return ((a->data[w] & v) != 0);

}

// Checks if the given bit string contains only bits specified by

// the flags vector. Returns 0 if there is at least one bit set in 'a'

// which is not specified in 'flags', 1 otherwise.

// 'len' is the length of 'flags'.

int ASN1_BIT_STRING_check(const ASN1_BIT_STRING *a, const unsigned char *flags,

                          int flags_len) {

  int i, ok;

  // Check if there is one bit set at all.

  if (!a || !a->data) {

    return 1;

  }

  // Check each byte of the internal representation of the bit string.

  ok = 1;

  for (i = 0; i < a->length && ok; ++i) {

    unsigned char mask = i < flags_len ? ~flags[i] : 0xff;

    // We are done if there is an unneeded bit set.

    ok = (a->data[i] & mask) == 0;

  }

  return ok;

}