// 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 <openssl/digest.h>

#include <openssl/err.h>

#include <openssl/evp.h>

#include <openssl/mem.h>

#include <openssl/obj.h>

#include <openssl/span.h>

#include <openssl/x509.h>

#include <limits.h>

#include "../internal.h"

#include "../mem_internal.h"

#include "internal.h"

using namespace bssl;

int ASN1_item_sign(const ASN1_ITEM *it, X509_ALGOR *algor1, X509_ALGOR *algor2,

                   ASN1_BIT_STRING *signature, void *asn, EVP_PKEY *pkey,

                   const EVP_MD *type) {

  if (signature->type != V_ASN1_BIT_STRING) {

    OPENSSL_PUT_ERROR(ASN1, ASN1_R_WRONG_TYPE);

    return 0;

  }

  ScopedEVP_MD_CTX ctx;

  if (!EVP_DigestSignInit(ctx.get(), nullptr, type, nullptr, pkey)) {

    return 0;

  }

  return ASN1_item_sign_ctx(it, algor1, algor2, signature, asn, ctx.get());

}

int ASN1_item_sign_ctx(const ASN1_ITEM *it, X509_ALGOR *algor1,

                       X509_ALGOR *algor2, ASN1_BIT_STRING *signature,

                       void *asn, EVP_MD_CTX *ctx) {

  // Historically, this function called |EVP_MD_CTX_cleanup| on return. Some

  // callers rely on this to avoid memory leaks.

  Cleanup cleanup = [&] { EVP_MD_CTX_cleanup(ctx); };

  // Write out the requested copies of the AlgorithmIdentifier. This may modify

  // |asn|, so we must do it first.

  if ((algor1 != nullptr && !x509_digest_sign_algorithm(ctx, algor1)) ||

      (algor2 != nullptr && !x509_digest_sign_algorithm(ctx, algor2))) {

    return 0;

  }

  uint8_t *in = nullptr;

  int in_len = ASN1_item_i2d(reinterpret_cast<ASN1_VALUE *>(asn), &in, it);

  if (in_len < 0) {

    return 0;

  }

  UniquePtr<uint8_t> free_in(in);

  return x509_sign_to_bit_string(ctx, signature, Span(in, in_len));

}

int bssl::x509_sign_to_bit_string(EVP_MD_CTX *ctx, ASN1_BIT_STRING *out,

                                  Span<const uint8_t> in) {

  if (out->type != V_ASN1_BIT_STRING) {

    OPENSSL_PUT_ERROR(ASN1, ASN1_R_WRONG_TYPE);

    return 0;

  }

  EVP_PKEY *pkey = EVP_PKEY_CTX_get0_pkey(ctx->pctx);

  size_t sig_len = EVP_PKEY_size(pkey);

  if (sig_len > INT_MAX) {

    // Ensure the signature will fit in |out|.

    OPENSSL_PUT_ERROR(X509, ERR_R_OVERFLOW);

    return 0;

  }

  Array<uint8_t> sig;

  if (!sig.Init(sig_len)) {

    return 0;

  }

  if (!EVP_DigestSign(ctx, sig.data(), &sig_len, in.data(), in.size())) {

    OPENSSL_PUT_ERROR(X509, ERR_R_EVP_LIB);

    return 0;

  }

  sig.Shrink(sig_len);

  uint8_t *sig_data;

  sig.Release(&sig_data, &sig_len);

  ASN1_STRING_set0(out, sig_data, static_cast<int>(sig_len));

  out->flags &= ~(ASN1_STRING_FLAG_BITS_LEFT | 0x07);

  out->flags |= ASN1_STRING_FLAG_BITS_LEFT;

  return static_cast<int>(sig_len);

}