// 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/evp.h>

#include <string.h>

#include <array>

#include <openssl/bytestring.h>

#include <openssl/dsa.h>

#include <openssl/ec_key.h>

#include <openssl/err.h>

#include <openssl/rsa.h>

#include <openssl/span.h>

#include "../bytestring/internal.h"

#include "../internal.h"

#include "../mem_internal.h"

#include "internal.h"

using namespace bssl;

EVP_PKEY *EVP_PKEY_from_subject_public_key_info(const uint8_t *in, size_t len,

                                                const EVP_PKEY_ALG *const *algs,

                                                size_t num_algs) {

  // Parse the SubjectPublicKeyInfo.

  CBS cbs, spki, algorithm, oid, key;

  CBS_init(&cbs, in, len);

  if (!CBS_get_asn1(&cbs, &spki, CBS_ASN1_SEQUENCE) ||

      !CBS_get_asn1(&spki, &algorithm, CBS_ASN1_SEQUENCE) ||

      !CBS_get_asn1(&algorithm, &oid, CBS_ASN1_OBJECT) ||

      !CBS_get_asn1(&spki, &key, CBS_ASN1_BITSTRING) ||

      CBS_len(&spki) != 0 ||  //

      CBS_len(&cbs) != 0) {

    OPENSSL_PUT_ERROR(EVP, EVP_R_DECODE_ERROR);

    return nullptr;

  }

  UniquePtr<EvpPkey> ret(FromOpaque(EVP_PKEY_new()));

  if (ret == nullptr) {

    return nullptr;

  }

  for (const EVP_PKEY_ALG *alg : Span(algs, num_algs)) {

    if (alg->method->pub_decode == nullptr ||

        Span(alg->method->oid, alg->method->oid_len) != oid) {

      continue;

    }

    // Every key type we support encodes the key as a byte string with the same

    // conversion to BIT STRING, so perform that common conversion ahead of

    // time, but only after the OID is recognized as supported.

    CBS key_bytes = key;

    uint8_t padding;

    if (!CBS_get_u8(&key_bytes, &padding) || padding != 0) {

      OPENSSL_PUT_ERROR(EVP, EVP_R_DECODE_ERROR);

      return nullptr;

    }

    CBS params = algorithm;

    switch (alg->method->pub_decode(alg, ret.get(), &params, &key_bytes)) {

      case evp_decode_error:

        return nullptr;

      case evp_decode_ok:

        return ret.release();

      case evp_decode_unsupported:

        // Continue trying other algorithms.

        break;

    }

  }

  OPENSSL_PUT_ERROR(EVP, EVP_R_UNSUPPORTED_ALGORITHM);

  return nullptr;

}

int EVP_marshal_public_key(CBB *cbb, const EVP_PKEY *key) {

  auto *impl = FromOpaque(key);

  if (impl->ameth == nullptr || impl->ameth->pub_encode == nullptr) {

    OPENSSL_PUT_ERROR(EVP, EVP_R_UNSUPPORTED_ALGORITHM);

    return 0;

  }

  if (impl->pkey == nullptr) {

    OPENSSL_PUT_ERROR(EVP, EVP_R_NO_KEY_SET);

    return 0;

  }

  return impl->ameth->pub_encode(cbb, impl);

}

EVP_PKEY *EVP_PKEY_from_private_key_info(const uint8_t *in, size_t len,

                                         const EVP_PKEY_ALG *const *algs,

                                         size_t num_algs) {

  // Parse the PrivateKeyInfo.

  CBS cbs, pkcs8, oid, algorithm, key;

  uint64_t version;

  CBS_init(&cbs, in, len);

  if (!CBS_get_asn1(&cbs, &pkcs8, CBS_ASN1_SEQUENCE) ||

      !CBS_get_asn1_uint64(&pkcs8, &version) || version != 0 ||

      !CBS_get_asn1(&pkcs8, &algorithm, CBS_ASN1_SEQUENCE) ||

      !CBS_get_asn1(&algorithm, &oid, CBS_ASN1_OBJECT) ||

      !CBS_get_asn1(&pkcs8, &key, CBS_ASN1_OCTETSTRING) ||

      // A PrivateKeyInfo ends with a SET of Attributes which we ignore.

      CBS_len(&cbs) != 0) {

    OPENSSL_PUT_ERROR(EVP, EVP_R_DECODE_ERROR);

    return nullptr;

  }

  UniquePtr<EvpPkey> ret(FromOpaque(EVP_PKEY_new()));

  if (ret == nullptr) {

    return nullptr;

  }

  for (const EVP_PKEY_ALG *alg : Span(algs, num_algs)) {

    if (alg->method->priv_decode == nullptr ||

        Span(alg->method->oid, alg->method->oid_len) != oid) {

      continue;

    }

    CBS params = algorithm, key_copy = key;

    switch (alg->method->priv_decode(alg, ret.get(), &params, &key_copy)) {

      case evp_decode_error:

        return nullptr;

      case evp_decode_ok:

        return ret.release();

      case evp_decode_unsupported:

        // Continue trying other algorithms.

        break;

    }

  }

  OPENSSL_PUT_ERROR(EVP, EVP_R_UNSUPPORTED_ALGORITHM);

  return nullptr;

}

int EVP_marshal_private_key(CBB *cbb, const EVP_PKEY *key) {

  auto *impl = FromOpaque(key);

  if (impl->ameth == nullptr || impl->ameth->priv_encode == nullptr) {

    OPENSSL_PUT_ERROR(EVP, EVP_R_UNSUPPORTED_ALGORITHM);

    return 0;

  }

  if (impl->pkey == nullptr) {

    OPENSSL_PUT_ERROR(EVP, EVP_R_NO_KEY_SET);

    return 0;

  }

  return impl->ameth->priv_encode(cbb, impl);

}

EVP_PKEY *EVP_parse_public_key(CBS *cbs) {

  CBS elem;

  if (!CBS_get_asn1_element(cbs, &elem, CBS_ASN1_SEQUENCE)) {

    OPENSSL_PUT_ERROR(EVP, EVP_R_DECODE_ERROR);

    return nullptr;

  }

  auto algs = GetDefaultEVPAlgorithms();

  return EVP_PKEY_from_subject_public_key_info(CBS_data(&elem), CBS_len(&elem),

                                               algs.data(), algs.size());

}

EVP_PKEY *EVP_parse_private_key(CBS *cbs) {

  CBS elem;

  if (!CBS_get_asn1_element(cbs, &elem, CBS_ASN1_SEQUENCE)) {

    OPENSSL_PUT_ERROR(EVP, EVP_R_DECODE_ERROR);

    return nullptr;

  }

  auto algs = GetDefaultEVPAlgorithms();

  return EVP_PKEY_from_private_key_info(CBS_data(&elem), CBS_len(&elem),

                                        algs.data(), algs.size());

}

static bssl::UniquePtr<EVP_PKEY> old_priv_decode(CBS *cbs, int type) {

  UniquePtr<EVP_PKEY> ret(EVP_PKEY_new());

  if (ret == nullptr) {

    return nullptr;

  }

  switch (type) {

    case EVP_PKEY_EC: {

      UniquePtr<EC_KEY> ec_key(EC_KEY_parse_private_key(cbs, nullptr));

      if (ec_key == nullptr) {

        return nullptr;

      }

      EVP_PKEY_assign_EC_KEY(ret.get(), ec_key.release());

      return ret;

    }

    case EVP_PKEY_DSA: {

      UniquePtr<DSA> dsa(DSA_parse_private_key(cbs));

      if (dsa == nullptr) {

        return nullptr;

      }

      EVP_PKEY_assign_DSA(ret.get(), dsa.release());

      return ret;

    }

    case EVP_PKEY_RSA: {

      UniquePtr<RSA> rsa(RSA_parse_private_key(cbs));

      if (rsa == nullptr) {

        return nullptr;

      }

      EVP_PKEY_assign_RSA(ret.get(), rsa.release());

      return ret;

    }

    default:

      OPENSSL_PUT_ERROR(EVP, EVP_R_UNKNOWN_PUBLIC_KEY_TYPE);

      return nullptr;

  }

}

EVP_PKEY *d2i_PrivateKey(int type, EVP_PKEY **out, const uint8_t **inp,

                         long len) {

  return D2IFromCBS(out, inp, len, [&](CBS *cbs) -> UniquePtr<EVP_PKEY> {

    // Parse with the legacy format.

    CBS copy = *cbs;

    UniquePtr<EVP_PKEY> ret = old_priv_decode(cbs, type);

    if (ret == nullptr) {

      // Try again with PKCS#8.

      ERR_clear_error();

      *cbs = copy;

      ret.reset(EVP_parse_private_key(cbs));

      if (ret == nullptr) {

        return nullptr;

      }

      if (EVP_PKEY_id(ret.get()) != type) {

        OPENSSL_PUT_ERROR(EVP, EVP_R_DIFFERENT_KEY_TYPES);

        return nullptr;

      }

    }

    return ret;

  });

}

// num_elements parses one SEQUENCE from `in` and returns the number of elements

// in it. On parse error, it returns zero.

static size_t num_elements(const uint8_t *in, size_t in_len) {

  CBS cbs, sequence;

  CBS_init(&cbs, in, (size_t)in_len);

  if (!CBS_get_asn1(&cbs, &sequence, CBS_ASN1_SEQUENCE)) {

    return 0;

  }

  size_t count = 0;

  while (CBS_len(&sequence) > 0) {

    if (!CBS_get_any_asn1_element(&sequence, nullptr, nullptr, nullptr)) {

      return 0;

    }

    count++;

  }

  return count;

}

EVP_PKEY *d2i_AutoPrivateKey(EVP_PKEY **out, const uint8_t **inp, long len) {

  if (len < 0) {

    OPENSSL_PUT_ERROR(EVP, EVP_R_DECODE_ERROR);

    return nullptr;

  }

  // Parse the input as a PKCS#8 PrivateKeyInfo.

  CBS cbs;

  CBS_init(&cbs, *inp, (size_t)len);

  EVP_PKEY *ret = EVP_parse_private_key(&cbs);

  if (ret != nullptr) {

    if (out != nullptr) {

      EVP_PKEY_free(*out);

      *out = ret;

    }

    *inp = CBS_data(&cbs);

    return ret;

  }

  ERR_clear_error();

  // Count the elements to determine the legacy key format.

  switch (num_elements(*inp, (size_t)len)) {

    case 4:

      return d2i_PrivateKey(EVP_PKEY_EC, out, inp, len);

    case 6:

      return d2i_PrivateKey(EVP_PKEY_DSA, out, inp, len);

    default:

      return d2i_PrivateKey(EVP_PKEY_RSA, out, inp, len);

  }

}

int i2d_PublicKey(const EVP_PKEY *key, uint8_t **outp) {

  switch (EVP_PKEY_id(key)) {

    case EVP_PKEY_RSA:

      return i2d_RSAPublicKey(EVP_PKEY_get0_RSA(key), outp);

    case EVP_PKEY_DSA:

      return i2d_DSAPublicKey(EVP_PKEY_get0_DSA(key), outp);

    case EVP_PKEY_EC:

      return i2o_ECPublicKey(EVP_PKEY_get0_EC_KEY(key), outp);

    default:

      OPENSSL_PUT_ERROR(EVP, EVP_R_UNSUPPORTED_PUBLIC_KEY_TYPE);

      return -1;

  }

}

EVP_PKEY *d2i_PublicKey(int type, EVP_PKEY **out, const uint8_t **inp,

                        long len) {

  return D2IFromCBS(out, inp, len, [&](CBS *cbs) -> UniquePtr<EVP_PKEY> {

    UniquePtr<EVP_PKEY> ret(EVP_PKEY_new());

    if (ret == nullptr) {

      return nullptr;

    }

    switch (type) {

      case EVP_PKEY_RSA: {

        UniquePtr<RSA> rsa(RSA_parse_public_key(cbs));

        if (rsa == nullptr) {

          return nullptr;

        }

        EVP_PKEY_assign_RSA(ret.get(), rsa.release());

        return ret;

      }

      // Unlike OpenSSL, we do not support EC keys with this API. The raw EC

      // public key serialization requires knowing the group. In OpenSSL,

      // calling this function with `EVP_PKEY_EC` and setting `out` to

      // nullptr does not work. It requires `*out` to include a

      // partially-initialized `EVP_PKEY` to extract the group.

      default:

        OPENSSL_PUT_ERROR(EVP, EVP_R_UNSUPPORTED_PUBLIC_KEY_TYPE);

        return nullptr;

    }

  });

}

EVP_PKEY *d2i_PUBKEY(EVP_PKEY **out, const uint8_t **inp, long len) {

  return D2IFromCBS(out, inp, len, EVP_parse_public_key);

}

int i2d_PUBKEY(const EVP_PKEY *pkey, uint8_t **outp) {

  if (pkey == nullptr) {

    return 0;

  }

  return I2DFromCBB(

      /*initial_capacity=*/128, outp,

      [&](CBB *cbb) -> bool { return EVP_marshal_public_key(cbb, pkey); });

}

static bssl::UniquePtr<EVP_PKEY> parse_spki(

    CBS *cbs, Span<const EVP_PKEY_ALG *const> algs) {

  CBS spki;

  if (!CBS_get_asn1_element(cbs, &spki, CBS_ASN1_SEQUENCE)) {

    OPENSSL_PUT_ERROR(EVP, EVP_R_DECODE_ERROR);

    return nullptr;

  }

  return UniquePtr<EVP_PKEY>(EVP_PKEY_from_subject_public_key_info(

      CBS_data(&spki), CBS_len(&spki), algs.data(), algs.size()));

}

static bssl::UniquePtr<EVP_PKEY> parse_spki(CBS *cbs, const EVP_PKEY_ALG *alg) {

  return parse_spki(cbs, Span(&alg, 1));

}

RSA *d2i_RSA_PUBKEY(RSA **out, const uint8_t **inp, long len) {

  return D2IFromCBS(out, inp, len, [](CBS *cbs) -> UniquePtr<RSA> {

    UniquePtr<EVP_PKEY> pkey = parse_spki(cbs, EVP_pkey_rsa());

    if (pkey == nullptr) {

      return nullptr;

    }

    return UniquePtr<RSA>(EVP_PKEY_get1_RSA(pkey.get()));

  });

}

int i2d_RSA_PUBKEY(const RSA *rsa, uint8_t **outp) {

  if (rsa == nullptr) {

    return 0;

  }

  UniquePtr<EVP_PKEY> pkey(EVP_PKEY_new());

  if (pkey == nullptr ||

      !EVP_PKEY_set1_RSA(pkey.get(), const_cast<RSA *>(rsa))) {

    return -1;

  }

  return i2d_PUBKEY(pkey.get(), outp);

}

DSA *d2i_DSA_PUBKEY(DSA **out, const uint8_t **inp, long len) {

  return D2IFromCBS(out, inp, len, [](CBS *cbs) -> UniquePtr<DSA> {

    UniquePtr<EVP_PKEY> pkey = parse_spki(cbs, EVP_pkey_dsa());

    if (pkey == nullptr) {

      return nullptr;

    }

    return UniquePtr<DSA>(EVP_PKEY_get1_DSA(pkey.get()));

  });

}

int i2d_DSA_PUBKEY(const DSA *dsa, uint8_t **outp) {

  if (dsa == nullptr) {

    return 0;

  }

  UniquePtr<EVP_PKEY> pkey(EVP_PKEY_new());

  if (pkey == nullptr ||

      !EVP_PKEY_set1_DSA(pkey.get(), const_cast<DSA *>(dsa))) {

    return -1;

  }

  return i2d_PUBKEY(pkey.get(), outp);

}

EC_KEY *d2i_EC_PUBKEY(EC_KEY **out, const uint8_t **inp, long len) {

  return D2IFromCBS(out, inp, len, [](CBS *cbs) -> UniquePtr<EC_KEY> {

    const EVP_PKEY_ALG *const algs[] = {EVP_pkey_ec_p224(), EVP_pkey_ec_p256(),

                                        EVP_pkey_ec_p384(), EVP_pkey_ec_p521()};

    UniquePtr<EVP_PKEY> pkey = parse_spki(cbs, algs);

    if (pkey == nullptr) {

      return nullptr;

    }

    return UniquePtr<EC_KEY>(EVP_PKEY_get1_EC_KEY(pkey.get()));

  });

}

int i2d_EC_PUBKEY(const EC_KEY *ec_key, uint8_t **outp) {

  if (ec_key == nullptr) {

    return 0;

  }

  UniquePtr<EVP_PKEY> pkey(EVP_PKEY_new());

  if (pkey == nullptr ||

      !EVP_PKEY_set1_EC_KEY(pkey.get(), const_cast<EC_KEY *>(ec_key))) {

    return -1;

  }

  return i2d_PUBKEY(pkey.get(), outp);

}