/***************************************************************************
 *                                  _   _ ____  _
 *  Project                     ___| | | |  _ \| |
 *                             / __| | | | |_) | |
 *                            | (__| |_| |  _ <| |___
 *                             \___|\___/|_| \_\_____|
 *
 * Copyright (C) Daniel Stenberg, <daniel@haxx.se>, et al.
 *
 * This software is licensed as described in the file COPYING, which
 * you should have received as part of this distribution. The terms
 * are also available at https://curl.se/docs/copyright.html.
 *
 * You may opt to use, copy, modify, merge, publish, distribute and/or sell
 * copies of the Software, and permit persons to whom the Software is
 * furnished to do so, under the terms of the COPYING file.
 *
 * This software is distributed on an "AS IS" basis, WITHOUT WARRANTY OF ANY
 * KIND, either express or implied.
 *
 * SPDX-License-Identifier: curl
 *
 ***************************************************************************/
/* <DESC>
 * Use in-memory user certificate and private key and retrieve an HTTPS page.
 * </DESC>
 */

/* Written by Ishan SinghLevett, based on Theo Borm's cacertinmem.c. Note that
 * to maintain simplicity this example does not use a CA certificate for peer
 * verification. Some form of peer verification must be used in real
 * circumstances when a secure connection is required.
 */

/* Requires: USE_OPENSSL */

#include <openssl/ssl.h>

#include <stdio.h>

#include <curl/curl.h>

static size_t write_cb(void *ptr, size_t size, size_t nmemb, void *stream)
{
  fwrite(ptr, size, nmemb, (FILE *)stream);
  return nmemb * size;
}

static CURLcode sslctx_function(CURL *curl, void *sslctx, void *pointer)
{
  /** This example uses a (fake) certificate and private key **/
  /* replace the XXX with the actual client/user certificate */
  static const char mypem[] =
    "-----BEGIN CERTIFICATE-----\n"
    "XXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXX\n"
    "XXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXX\n"
    "XXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXX\n"
    "XXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXX\n"
    "XXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXX\n"
    "XXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXX\n"
    "XXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXX\n"
    "XXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXX\n"
    "-----END CERTIFICATE-----\n";

  /* replace the XXX with the actual private key */
  static const char mykey[] =
    "-----BEGIN PRIVATE KEY-----\n"
    "XXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXX\n"
    "XXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXX\n"
    "XXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXX\n"
    "-----END PRIVATE KEY-----\n";

  CURLcode result = CURLE_ABORTED_BY_CALLBACK;
  X509 *cert = NULL;
  BIO *bio = NULL;
  BIO *kbio = NULL;
  EVP_PKEY *pkey = NULL;
  int ret;

  (void)curl;
  (void)pointer;

  /* get a BIO */
  bio = BIO_new_mem_buf(mypem, sizeof(mypem) - 1);
  if(!bio) {
    printf("BIO_new_mem_buf() failed\n");
    goto out;
  }

  /* use it to read the PEM formatted certificate from memory into an X509
     structure that SSL can use. */
  cert = PEM_read_bio_X509(bio, NULL, 0, NULL);
  if(!cert) {
    printf("PEM_read_bio_X509() failed\n");
    goto out;
  }

  /* tell SSL to use the X509 certificate */
  ret = SSL_CTX_use_certificate((SSL_CTX *)sslctx, cert);
  if(ret != 1) {
    printf("SSL_CTX_use_certificate() failed\n");
    goto out;
  }

  /* create a bio for the private key */
  kbio = BIO_new_mem_buf(mykey, sizeof(mykey) - 1);
  if(!kbio) {
    printf("BIO_new_mem_buf() failed\n");
    goto out;
  }

  pkey = PEM_read_bio_PrivateKey(kbio, NULL, NULL, NULL);
  if(!pkey) {
    printf("PEM_read_bio_PrivateKey() failed\n");
    goto out;
  }

  /* tell SSL to use the private key from memory */
  ret = SSL_CTX_use_PrivateKey((SSL_CTX *)sslctx, pkey);
  if(ret != 1) {
    printf("SSL_CTX_use_PrivateKey() failed\n");
    goto out;
  }

  result = CURLE_OK;

out:
  /* free resources that have been allocated by OpenSSL functions */
  if(bio)
    BIO_free(bio);

  if(kbio)
    BIO_free(kbio);

  if(pkey)
    EVP_PKEY_free(pkey);

  if(cert)
    X509_free(cert);

  /* all set to go */
  return result;
}

int main(void)
{
  CURL *curl;

  CURLcode result = curl_global_init(CURL_GLOBAL_ALL);
  if(result != CURLE_OK)
    return (int)result;

  curl = curl_easy_init();
  if(curl) {
    curl_easy_setopt(curl, CURLOPT_VERBOSE, 0L);
    curl_easy_setopt(curl, CURLOPT_HEADER, 0L);
    curl_easy_setopt(curl, CURLOPT_NOPROGRESS, 1L);
    curl_easy_setopt(curl, CURLOPT_NOSIGNAL, 1L);
    curl_easy_setopt(curl, CURLOPT_WRITEFUNCTION, write_cb);
    curl_easy_setopt(curl, CURLOPT_WRITEDATA, stdout);
    curl_easy_setopt(curl, CURLOPT_HEADERFUNCTION, write_cb);
    curl_easy_setopt(curl, CURLOPT_HEADERDATA, stderr);
    curl_easy_setopt(curl, CURLOPT_SSLCERTTYPE, "PEM");

    /* both VERIFYPEER and VERIFYHOST are set to 0 in this case because there
       is no CA certificate */
    curl_easy_setopt(curl, CURLOPT_SSL_VERIFYPEER, 0L);
    curl_easy_setopt(curl, CURLOPT_SSL_VERIFYHOST, 0L);

    curl_easy_setopt(curl, CURLOPT_URL, "https://www.example.com/");
    curl_easy_setopt(curl, CURLOPT_SSLKEYTYPE, "PEM");

    /* first try: retrieve page without user certificate and key -> fails */
    result = curl_easy_perform(curl);
    if(result == CURLE_OK)
      printf("*** transfer succeeded ***\n");
    else
      printf("*** transfer failed ***\n");

    /* second try: retrieve page using user certificate and key -> succeeds to
     * load the certificate and key by installing a function doing the
     * necessary "modifications" to the SSL CONTEXT before link init
     */
    curl_easy_setopt(curl, CURLOPT_SSL_CTX_FUNCTION, sslctx_function);
    result = curl_easy_perform(curl);
    if(result == CURLE_OK)
      printf("*** transfer succeeded ***\n");
    else
      printf("*** transfer failed ***\n");

    curl_easy_cleanup(curl);
  }
  curl_global_cleanup();
  return (int)result;
}