/* Feel free to use this example code in any way

   you see fit (Public Domain) */

#include <sys/types.h>

#ifndef _WIN32

#include <sys/select.h>

#include <sys/socket.h>

#else

#include <winsock2.h>

#endif

#include <microhttpd.h>

#include <string.h>

#include <stdio.h>

#include <stdlib.h>

#define PORT 8888

#define REALM     "\"Maintenance\""

#define USER      "a legitimate user"

#define PASSWORD  "and his password"

#define SERVERKEYFILE "server.key"

#define SERVERCERTFILE "server.pem"

static char *

string_to_base64 (const char *message)

{

  const char *lookup =

    "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/";

  unsigned long l;

  size_t i;

  char *tmp;

  size_t length = strlen (message);

  tmp = malloc (length * 2);

  if (NULL == tmp)

    return tmp;

  tmp[0] = 0;

  for (i = 0; i < length; i += 3)

    {

      l = (((unsigned long) message[i]) << 16)

        | (((i + 1) < length) ? (((unsigned long) message[i + 1]) << 8) : 0)

        | (((i + 2) < length) ? ((unsigned long) message[i + 2]) : 0);

      strncat (tmp, &lookup[(l >> 18) & 0x3F], 1);

      strncat (tmp, &lookup[(l >> 12) & 0x3F], 1);

      if (i + 1 < length)

        strncat (tmp, &lookup[(l >> 6) & 0x3F], 1);

      if (i + 2 < length)

        strncat (tmp, &lookup[l & 0x3F], 1);

    }

  if (length % 3)

    strncat (tmp, "===", 3 - length % 3);

  return tmp;

}

static long

get_file_size (const char *filename)

{

  FILE *fp;

  fp = fopen (filename, "rb");

  if (fp)

    {

      long size;

      if ((0 != fseek (fp, 0, SEEK_END)) || (-1 == (size = ftell (fp))))

        size = 0;

      fclose (fp);

      return size;

    }

  else

    return 0;

}

static char *

load_file (const char *filename)

{

  FILE *fp;

  char *buffer;

  long size;

  size = get_file_size (filename);

  if (0 == size)

    return NULL;

  fp = fopen (filename, "rb");

  if (! fp)

    return NULL;

  buffer = malloc (size + 1);

  if (! buffer)

    {

      fclose (fp);

      return NULL;

    }

  buffer[size] = '\0';

  if (size != (long)fread (buffer, 1, size, fp))

    {

      free (buffer);

      buffer = NULL;

    }

  fclose (fp);

  return buffer;

}

static int

ask_for_authentication (struct MHD_Connection *connection, const char *realm)

{

  int ret;

  struct MHD_Response *response;

  char *headervalue;

  const char *strbase = "Basic realm=";

  response = MHD_create_response_from_buffer (0, NULL,

					      MHD_RESPMEM_PERSISTENT);

  if (!response)

    return MHD_NO;

  headervalue = malloc (strlen (strbase) + strlen (realm) + 1);

  if (!headervalue)

    return MHD_NO;

  strcpy (headervalue, strbase);

  strcat (headervalue, realm);

  ret = MHD_add_response_header (response, "WWW-Authenticate", headervalue);

  free (headervalue);

  if (!ret)

    {

      MHD_destroy_response (response);

      return MHD_NO;

    }

  ret = MHD_queue_response (connection, MHD_HTTP_UNAUTHORIZED, response);

  MHD_destroy_response (response);

  return ret;

}

static int

is_authenticated (struct MHD_Connection *connection,

                  const char *username, const char *password)

{

  const char *headervalue;

  char *expected_b64, *expected;

  const char *strbase = "Basic ";

  int authenticated;

  headervalue =

    MHD_lookup_connection_value (connection, MHD_HEADER_KIND,

                                 "Authorization");

  if (NULL == headervalue)

    return 0;

  if (0 != strncmp (headervalue, strbase, strlen (strbase)))

    return 0;

  expected = malloc (strlen (username) + 1 + strlen (password) + 1);

  if (NULL == expected)

    return 0;

  strcpy (expected, username);

  strcat (expected, ":");

  strcat (expected, password);

  expected_b64 = string_to_base64 (expected);

  free (expected);

  if (NULL == expected_b64)

    return 0;

  authenticated =

    (strcmp (headervalue + strlen (strbase), expected_b64) == 0);

  free (expected_b64);

  return authenticated;

}

static int

secret_page (struct MHD_Connection *connection)

{

  int ret;

  struct MHD_Response *response;

  const char *page = "<html><body>A secret.</body></html>";

  response =

    MHD_create_response_from_buffer (strlen (page), (void *) page,

				     MHD_RESPMEM_PERSISTENT);

  if (!response)

    return MHD_NO;

  ret = MHD_queue_response (connection, MHD_HTTP_OK, response);

  MHD_destroy_response (response);

  return ret;

}

static int

answer_to_connection (void *cls, struct MHD_Connection *connection,

                      const char *url, const char *method,

                      const char *version, const char *upload_data,

                      size_t *upload_data_size, void **con_cls)

{

  (void)cls;               /* Unused. Silent compiler warning. */

  (void)url;               /* Unused. Silent compiler warning. */

  (void)version;           /* Unused. Silent compiler warning. */

  (void)upload_data;       /* Unused. Silent compiler warning. */

  (void)upload_data_size;  /* Unused. Silent compiler warning. */

  if (0 != strcmp (method, "GET"))

    return MHD_NO;

  if (NULL == *con_cls)

    {

      *con_cls = connection;

      return MHD_YES;

    }

  if (!is_authenticated (connection, USER, PASSWORD))

    return ask_for_authentication (connection, REALM);

  return secret_page (connection);

}

int

main ()

{

  struct MHD_Daemon *daemon;

  char *key_pem;

  char *cert_pem;

  key_pem = load_file (SERVERKEYFILE);

  cert_pem = load_file (SERVERCERTFILE);

  if ((key_pem == NULL) || (cert_pem == NULL))

    {

      printf ("The key/certificate files could not be read.\n");

      if (NULL != key_pem)

        free (key_pem);

      if (NULL != cert_pem)

        free (cert_pem);

      return 1;

    }

  daemon =

    MHD_start_daemon (MHD_USE_INTERNAL_POLLING_THREAD | MHD_USE_TLS, PORT, NULL,

                      NULL, &answer_to_connection, NULL,

                      MHD_OPTION_HTTPS_MEM_KEY, key_pem,

                      MHD_OPTION_HTTPS_MEM_CERT, cert_pem, MHD_OPTION_END);

  if (NULL == daemon)

    {

      printf ("%s\n", cert_pem);

      free (key_pem);

      free (cert_pem);

      return 1;

    }

  (void) getchar ();

  MHD_stop_daemon (daemon);

  free (key_pem);

  free (cert_pem);

  return 0;

}