/*
 *  ircd-hybrid: an advanced Internet Relay Chat Daemon(ircd).
 *  rsa.c: Functions for use with RSA public key cryptography.
 *
 *  Copyright (C) 2002 by the past and present ircd coders, and others.
 *
 *  This program 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 2 of the License, or
 *  (at your option) any later version.
 *
 *  This program 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, write to the Free Software
 *  Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307
 *  USA
 *
 *  $Id: rsa.c 33 2005-10-02 20:50:00Z knight $
 */

#include "stdinc.h"

#include <openssl/pem.h>
#include <openssl/rand.h>
#include <openssl/rsa.h>
#include <openssl/md5.h>
#include <openssl/bn.h>
#include <openssl/evp.h>
#include <openssl/err.h>

#include "memory.h"
#include "rsa.h"
#include "tools.h"
#include "s_conf.h"
#include "s_log.h"
#include "client.h" /* CIPHERKEYLEN .. eww */
#include "ircd.h" /* bio_spare_fd */

static void binary_to_hex(unsigned char *bin, char *hex, int length);

/*
 * report_crypto_errors - Dump crypto error list to log
 */
void
report_crypto_errors(void)
{
  unsigned long e   = 0;
  unsigned long cnt = 0;

  ERR_load_crypto_strings();

  while ((cnt < 100) && (e = ERR_get_error()))
  {
    ilog(L_CRIT, "SSL error: %s", ERR_error_string(e, 0));
    cnt++;
  }
}

/*
 * verify_private_key - reread private key and verify against inmem key
 */
int
verify_private_key(void)
{
  BIO *file;
  RSA *key;
  RSA *mkey;

  /* If the rsa_private_key directive isn't found, error out. */
  if (ServerInfo.rsa_private_key == NULL)
  {
    ilog(L_NOTICE, "rsa_private_key in serverinfo{} is not defined.");
    return -1;
  }

  /* If rsa_private_key_file isn't available, error out. */
  if (ServerInfo.rsa_private_key_file == NULL)
  {
    ilog(L_NOTICE, "Internal error: rsa_private_key_file isn't defined.");
    return -1;
  }

  if (bio_spare_fd > -1)
    close(bio_spare_fd);

  file = BIO_new_file(ServerInfo.rsa_private_key_file, "r");

  /*
   * If BIO_new_file returned NULL (according to OpenSSL docs), then
   * an error occurred.
   */
  if (file == NULL)
  {
    bio_spare_fd = save_spare_fd("SSL private key validation");
    ilog(L_NOTICE, "Failed to open private key file - can't validate it");
    return -1;
  }

  /*
   * jdc -- Let's do this a little differently.  According to the
   *        OpenSSL documentation, you need to METHOD_free(key) before
   *        assigning it.  Don't believe me?  Check out the following
   *        URL:  http://www.openssl.org/docs/crypto/pem.html#BUGS
   * P.S. -- I have no idea why the key= assignment has to be typecasted.
   *         For some reason the system thinks PEM_read_bio_RSAPrivateKey
   *         is returning an int, not a RSA *.
   * androsyn -- Thats because you didn't have a prototype and including
   * 		 pem.h breaks things for some reason..
   */
  key = (RSA *) PEM_read_bio_RSAPrivateKey(file, NULL, 0, NULL);

  if (key == NULL)
  {
    ilog(L_NOTICE, "PEM_read_bio_RSAPrivateKey() failed; possibly not RSA?");
    report_crypto_errors();
    return -1;
  }

  BIO_set_close(file, BIO_CLOSE);
  BIO_free(file);
  bio_spare_fd = save_spare_fd("SSL private key validation");

  mkey = ServerInfo.rsa_private_key;

  /*
   * Compare the in-memory key to the key we just loaded above.  If
   * any of the portions don't match, then logically we have a different
   * in-memory key vs. the one we just loaded.  This is bad, mmmkay?
   */
  if (mkey->pad != key->pad)
    ilog(L_CRIT, "Private key corrupted: pad %i != pad %i",
                 mkey->pad, key->pad);
  
  if (mkey->version != key->version)
  {
#if (OPENSSL_VERSION_NUMBER & 0x00907000) == 0x00907000
    ilog(L_CRIT, "Private key corrupted: version %li != version %li",
                 mkey->version, key->version);
#else
    ilog(L_CRIT, "Private key corrupted: version %i != version %i",
                 mkey->version, key->version);
#endif
  }    

  if (BN_cmp(mkey->n, key->n))
    ilog(L_CRIT, "Private key corrupted: n differs");
  if (BN_cmp(mkey->e, key->e))
    ilog(L_CRIT, "Private key corrupted: e differs");
  if (BN_cmp(mkey->d, key->d))
    ilog(L_CRIT, "Private key corrupted: d differs");
  if (BN_cmp(mkey->p, key->p))
    ilog(L_CRIT, "Private key corrupted: p differs");
  if (BN_cmp(mkey->q, key->q))
    ilog(L_CRIT, "Private key corrupted: q differs");
  if (BN_cmp(mkey->dmp1, key->dmp1))
    ilog(L_CRIT, "Private key corrupted: dmp1 differs");
  if (BN_cmp(mkey->dmq1, key->dmq1))
    ilog(L_CRIT, "Private key corrupted: dmq1 differs");
  if (BN_cmp(mkey->iqmp, key->iqmp))
    ilog(L_CRIT, "Private key corrupted: iqmp differs");

  RSA_free(key);
  return 0;
}


static void
binary_to_hex(unsigned char *bin, char *hex, int length)
{
  static const char trans[] = "0123456789ABCDEF";
  int i;

  for(i = 0; i < length; i++)
  {
    hex[i  << 1]      = trans[bin[i] >> 4];
    hex[(i << 1) + 1] = trans[bin[i] & 0xf];
  }

  hex[i << 1] = '\0';
}

int
get_randomness(unsigned char *buf, int length)
{
    /* Seed OpenSSL PRNG with EGD enthropy pool -kre */
    if (ConfigFileEntry.use_egd &&
        (ConfigFileEntry.egdpool_path != NULL))
    {
      if (RAND_egd(ConfigFileEntry.egdpool_path) == -1)
            return -1;
    }

  if (RAND_status())
    return (RAND_bytes(buf, length));
  else /* XXX - abort? */
    return (RAND_pseudo_bytes(buf, length));
}

int
generate_challenge(char **r_challenge, char **r_response, RSA *rsa)
{
  unsigned char secret[32], *tmp;
  unsigned long length;
  int ret = -1;

  if (!rsa)
  	return -1;
  get_randomness(secret, 32);
  *r_response = MyMalloc(65);
  binary_to_hex(secret, *r_response, 32);

  length = RSA_size(rsa);
  tmp = MyMalloc(length);
  ret = RSA_public_encrypt(32, secret, tmp, rsa, RSA_PKCS1_PADDING);

  *r_challenge = MyMalloc((length << 1) + 1);
  binary_to_hex( tmp, *r_challenge, length);
  (*r_challenge)[length<<1] = 0;
  MyFree(tmp);

  if (ret < 0)
  {
    report_crypto_errors();
    return -1;
  }
  return 0;
}
