// Copyright 1999-2016 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 <stdio.h>

#include <string.h>

#include <openssl/asn1.h>

#include <openssl/asn1t.h>

#include <openssl/conf.h>

#include <openssl/err.h>

#include <openssl/mem.h>

#include <openssl/obj.h>

#include <openssl/x509.h>

#include "internal.h"

using namespace bssl;

static STACK_OF(CONF_VALUE) *i2v_AUTHORITY_KEYID(

    const X509V3_EXT_METHOD *method, void *ext, STACK_OF(CONF_VALUE) *extlist);

static void *v2i_AUTHORITY_KEYID(const X509V3_EXT_METHOD *method,

                                 const X509V3_CTX *ctx,

                                 const STACK_OF(CONF_VALUE) *values);

const X509V3_EXT_METHOD bssl::v3_akey_id = {

    NID_authority_key_identifier,

    X509V3_EXT_MULTILINE,

    ASN1_ITEM_ref(AUTHORITY_KEYID),

    nullptr,

    nullptr,

    nullptr,

    nullptr,

    nullptr,

    nullptr,

    i2v_AUTHORITY_KEYID,

    v2i_AUTHORITY_KEYID,

    nullptr,

    nullptr,

    nullptr,

};

static STACK_OF(CONF_VALUE) *i2v_AUTHORITY_KEYID(

    const X509V3_EXT_METHOD *method, void *ext, STACK_OF(CONF_VALUE) *extlist) {

  const AUTHORITY_KEYID *akeyid =

      reinterpret_cast<const AUTHORITY_KEYID *>(ext);

  int extlist_was_null = extlist == nullptr;

  if (akeyid->keyid) {

    char *tmp = x509v3_bytes_to_hex(akeyid->keyid->data, akeyid->keyid->length);

    int ok = tmp != nullptr && X509V3_add_value("keyid", tmp, &extlist);

    OPENSSL_free(tmp);

    if (!ok) {

      goto err;

    }

  }

  if (akeyid->issuer) {

    STACK_OF(CONF_VALUE) *tmpextlist =

        i2v_GENERAL_NAMES(nullptr, akeyid->issuer, extlist);

    if (tmpextlist == nullptr) {

      goto err;

    }

    extlist = tmpextlist;

  }

  if (akeyid->serial) {

    if (!X509V3_add_value_int("serial", akeyid->serial, &extlist)) {

      goto err;

    }

  }

  return extlist;

err:

  if (extlist_was_null) {

    sk_CONF_VALUE_pop_free(extlist, X509V3_conf_free);

  }

  return nullptr;

}

// Currently two options:

//

// - keyid: Use the issuer's subject key ID. The value 'always' means it's an

//   error if the issuer certificate doesn't have one.

//

// - issuer: Use the issuer's issuer and serial number. The default is to only

//   use this if the key ID is not present. The value 'always' means it's always

//   included.

static void *v2i_AUTHORITY_KEYID(const X509V3_EXT_METHOD *method,

                                 const X509V3_CTX *ctx,

                                 const STACK_OF(CONF_VALUE) *values) {

  enum Option { kOff = 0, kOn = 1, kAlways = 2 };

  Option use_key_id = kOff, use_issuer = kOff;

  for (const CONF_VALUE *cnf : values) {

    if (!strcmp(cnf->name, "keyid")) {

      use_key_id = kOn;

      if (cnf->value && !strcmp(cnf->value, "always")) {

        use_key_id = kAlways;

      }

    } else if (!strcmp(cnf->name, "issuer")) {

      use_issuer = kOn;

      if (cnf->value && !strcmp(cnf->value, "always")) {

        use_issuer = kAlways;

      }

    } else {

      OPENSSL_PUT_ERROR(X509V3, X509V3_R_UNKNOWN_OPTION);

      ERR_add_error_data(2, "name=", cnf->name);

      return nullptr;

    }

  }

  if (!ctx || !ctx->issuer_cert) {

    if (ctx && (ctx->flags == X509V3_CTX_TEST)) {

      return AUTHORITY_KEYID_new();

    }

    OPENSSL_PUT_ERROR(X509V3, X509V3_R_NO_ISSUER_CERTIFICATE);

    return nullptr;

  }

  UniquePtr<ASN1_OCTET_STRING> key_id;

  if (use_key_id != kOff) {

    int critical;

    key_id.reset(static_cast<ASN1_OCTET_STRING *>(X509_get_ext_d2i(

        ctx->issuer_cert, NID_subject_key_identifier, &critical, nullptr)));

    if (key_id == nullptr && critical != -1) {

      return nullptr;  // Syntax error in the extension.

    }

    if (use_key_id == kAlways && key_id == nullptr) {

      OPENSSL_PUT_ERROR(X509V3, X509V3_R_UNABLE_TO_GET_ISSUER_KEYID);

      return nullptr;

    }

  }

  UniquePtr<ASN1_INTEGER> serial;

  UniquePtr<GENERAL_NAMES> issuer_gens;

  if ((use_issuer == kOn && key_id == nullptr) || use_issuer == kAlways) {

    UniquePtr<X509_NAME> issuer_name(

        X509_NAME_dup(X509_get_issuer_name(ctx->issuer_cert)));

    serial.reset(ASN1_INTEGER_dup(X509_get0_serialNumber(ctx->issuer_cert)));

    if (issuer_name == nullptr || serial == nullptr) {

      OPENSSL_PUT_ERROR(X509V3, X509V3_R_UNABLE_TO_GET_ISSUER_DETAILS);

      return nullptr;

    }

    // AKID wraps the issuer name in a GeneralNames structure.

    UniquePtr<GENERAL_NAME> gen(GENERAL_NAME_new());

    if (gen == nullptr) {

      return nullptr;

    }

    gen->type = GEN_DIRNAME;

    gen->d.directoryName = issuer_name.release();

    issuer_gens.reset(sk_GENERAL_NAME_new_null());

    if (issuer_gens == nullptr ||

        !PushToStack(issuer_gens.get(), std::move(gen))) {

      return nullptr;

    }

  }

  UniquePtr<AUTHORITY_KEYID> akid(AUTHORITY_KEYID_new());

  if (akid == nullptr) {

    return nullptr;

  }

  akid->issuer = issuer_gens.release();

  akid->serial = serial.release();

  akid->keyid = key_id.release();

  return akid.release();

}