/*
 * Copyright (C) 2004,2005,2007,2008,2009 Free Software Foundation
 * Copyright (C) 2001,2002,2003 Nikos Mavrogiannopoulos
 *
 * This file is part of GNUTLS.
 *
 * GNUTLS is free software: you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation, either version 3 of the License, or
 * (at your option) any later version.
 *
 * GNUTLS is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program.  If not, see <http://www.gnu.org/licenses/>.
 */

#include <config.h>

#ifdef ENABLE_PKI

#include <stdio.h>
#include <string.h>
#include <stdlib.h>
#include <unistd.h>
#include <gnutls/gnutls.h>

/* Generates Diffie-Hellman parameters (a prime and a generator
 * of the group). Exports them in PKCS #3 format. Used by certtool.
 */

extern FILE *outfile;
extern FILE *infile;
extern unsigned char buffer[];
extern const int buffer_size;

static int cparams = 0;

int generate_prime (int bits, int how);

/* If how is zero then the included parameters are used.
 */
int
generate_prime (int bits, int how)
{
  unsigned int i;
  int ret;
  gnutls_dh_params_t dh_params;
  gnutls_datum_t p, g;

  gnutls_dh_params_init (&dh_params);

  fprintf (stderr, "Generating DH parameters...");

  if (how != 0)
    {
      ret = gnutls_dh_params_generate2 (dh_params, bits);
      if (ret < 0)
	{
	  fprintf (stderr, "Error generating parameters: %s\n",
		   gnutls_strerror (ret));
	  exit (1);
	}

      ret = gnutls_dh_params_export_raw (dh_params, &p, &g, NULL);
      if (ret < 0)
	{
	  fprintf (stderr, "Error exporting parameters: %s\n",
		   gnutls_strerror (ret));
	  exit (1);
	}
    }
  else
    {
#ifdef ENABLE_SRP
      if (bits <= 1024)
	{
	  p = gnutls_srp_1024_group_prime;
	  g = gnutls_srp_1024_group_generator;
	}
      else if (bits <= 1536)
	{
	  p = gnutls_srp_1536_group_prime;
	  g = gnutls_srp_1536_group_generator;
	}
      else
	{
	  p = gnutls_srp_2048_group_prime;
	  g = gnutls_srp_2048_group_generator;
	}

      ret = gnutls_dh_params_import_raw (dh_params, &p, &g);
      if (ret < 0)
	{
	  fprintf (stderr, "Error exporting parameters: %s\n",
		   gnutls_strerror (ret));
	  exit (1);
	}
#else
      fprintf (stderr, "Parameters unavailable as SRP disabled.\n");
#endif
    }

  if (cparams)
    {

      fprintf (outfile, "/* generator */\n");
      fprintf (outfile, "\nconst uint8 g[%d] = { ", g.size);

      for (i = 0; i < g.size; i++)
	{
	  if (i % 7 == 0)
	    fprintf (outfile, "\n\t");
	  fprintf (outfile, "0x%.2x", g.data[i]);
	  if (i != g.size - 1)
	    fprintf (outfile, ", ");
	}

      fprintf (outfile, "\n};\n\n");
    }
  else
    {
      fprintf (outfile, "\nGenerator: ");

      for (i = 0; i < g.size; i++)
	{
	  if (i != 0 && i % 12 == 0)
	    fprintf (outfile, "\n\t");
	  else if (i != 0 && i != g.size)
	    fprintf (outfile, ":");

	  fprintf (outfile, "%.2x", g.data[i]);
	}

      fprintf (outfile, "\n\n");
    }

  /* print prime */

  if (cparams)
    {
      fprintf (outfile, "/* prime - %d bits */\n", p.size * 8);
      fprintf (outfile, "\nconst uint8 prime[%d] = { ", p.size);

      for (i = 0; i < p.size; i++)
	{
	  if (i % 7 == 0)
	    fprintf (outfile, "\n\t");
	  fprintf (outfile, "0x%.2x", p.data[i]);
	  if (i != p.size - 1)
	    fprintf (outfile, ", ");
	}

      fprintf (outfile, "\n};\n");
    }
  else
    {
      fprintf (outfile, "Prime: ");

      for (i = 0; i < p.size; i++)
	{
	  if (i != 0 && i % 12 == 0)
	    fprintf (outfile, "\n\t");
	  else if (i != 0 && i != p.size)
	    fprintf (outfile, ":");
	  fprintf (outfile, "%.2x", p.data[i]);
	}

      fprintf (outfile, "\n\n");

    }

  if (!cparams)
    {				/* generate a PKCS#3 structure */

      size_t len = buffer_size;

      ret = gnutls_dh_params_export_pkcs3 (dh_params, GNUTLS_X509_FMT_PEM,
					   buffer, &len);

      if (ret == 0)
	{
	  fprintf (outfile, "\n%s", buffer);
	}
      else
	{
	  fprintf (stderr, "Error: %s\n", gnutls_strerror (ret));
	}

    }

  return 0;
}

#endif