// 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"


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 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 issuers subject keyid, the value
// 'always' means its is an error if the issuer certificate doesn't have a
// key id. issuer: use the issuers cert issuer and serial number. The default
// is to only use this if keyid is not present. With the option 'always' this
// is always included.

static void *v2i_AUTHORITY_KEYID(const X509V3_EXT_METHOD *method,
                                 const X509V3_CTX *ctx,
                                 const STACK_OF(CONF_VALUE) *values) {
  char keyid = 0, issuer = 0;
  int j;
  ASN1_OCTET_STRING *ikeyid = nullptr;
  X509_NAME *isname = nullptr;
  GENERAL_NAMES *gens = nullptr;
  GENERAL_NAME *gen = nullptr;
  ASN1_INTEGER *serial = nullptr;
  const X509 *cert;
  AUTHORITY_KEYID *akeyid;

  for (size_t i = 0; i < sk_CONF_VALUE_num(values); i++) {
    const CONF_VALUE *cnf = sk_CONF_VALUE_value(values, i);
    if (!strcmp(cnf->name, "keyid")) {
      keyid = 1;
      if (cnf->value && !strcmp(cnf->value, "always")) {
        keyid = 2;
      }
    } else if (!strcmp(cnf->name, "issuer")) {
      issuer = 1;
      if (cnf->value && !strcmp(cnf->value, "always")) {
        issuer = 2;
      }
    } 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;
  }

  cert = ctx->issuer_cert;

  if (keyid) {
    j = X509_get_ext_by_NID(cert, NID_subject_key_identifier, -1);
    const X509_EXTENSION *ext;
    if ((j >= 0) && (ext = X509_get_ext(cert, j))) {
      ikeyid = reinterpret_cast<ASN1_OCTET_STRING *>(X509V3_EXT_d2i(ext));
    }
    if (keyid == 2 && !ikeyid) {
      OPENSSL_PUT_ERROR(X509V3, X509V3_R_UNABLE_TO_GET_ISSUER_KEYID);
      return nullptr;
    }
  }

  if ((issuer && !ikeyid) || (issuer == 2)) {
    isname = X509_NAME_dup(X509_get_issuer_name(cert));
    serial = ASN1_INTEGER_dup(X509_get0_serialNumber(cert));
    if (!isname || !serial) {
      OPENSSL_PUT_ERROR(X509V3, X509V3_R_UNABLE_TO_GET_ISSUER_DETAILS);
      goto err;
    }
  }

  if (!(akeyid = AUTHORITY_KEYID_new())) {
    goto err;
  }

  if (isname) {
    if (!(gens = sk_GENERAL_NAME_new_null()) || !(gen = GENERAL_NAME_new()) ||
        !sk_GENERAL_NAME_push(gens, gen)) {
      goto err;
    }
    gen->type = GEN_DIRNAME;
    gen->d.dirn = isname;
  }

  akeyid->issuer = gens;
  akeyid->serial = serial;
  akeyid->keyid = ikeyid;

  return akeyid;

err:
  X509_NAME_free(isname);
  ASN1_INTEGER_free(serial);
  ASN1_OCTET_STRING_free(ikeyid);
  return nullptr;
}