/**
 * ircservices.C: IRCServices's weird password encryption thingy, taken from Anope 1.6.3.
 *
 * Copyright © 2007 Pippijn van Steenhoven / The Ermyth Team
 * Rights to this code are as documented in COPYING.
 *
 *
 * Portions of this file were derived from sources bearing the following license:
 * Copyright © 2005 Atheme Development Group
 * Rights to this code are as documented in doc/pod/license.pod.
 *
 * $Id: ircservices.C,v 1.6 2007/09/16 18:54:43 pippijn Exp $
 */
/* Include file for high-level encryption routines.
 *
 * (C) 2003 Anope Team
 * Contact us at info@anope.org
 *
 * Please read doc/poddoc/license.pod and README for further details.
 *
 * Based on the original code of Epona by Lara.
 * Based on the original code of Services by Andy Church. 
 */

#include "atheme.h"
#include <ermyth/crypto.h>

static char const rcsid[] = "$Id: ircservices.C,v 1.6 2007/09/16 18:54:43 pippijn Exp $";

/* necessary anope defines */
#define PASSMAX 32
#define ENCRYPT_MD5 1

/*************************************************************************/

/******** Our own high-level routines. ********/


#define XTOI(c) ((c)>9 ? (c)-'A'+10 : (c)-'0')
/* Result of this:
 * c in [-128,9]  =>  [-183,-46]
 * c in [10,127]  =>  [-38,79]
 */

namespace crypto
{
  namespace impl
  {
    /**
     * Encrypt `src' of length `len' and store the result in `dest'.  If the
     * resulting string would be longer than `size', return -1 and leave `dest'
     * unchanged; else return 0.
     */
    static int
    encrypt (char const * const src, int len, char *dest, int size)
    {
#if ENCRYPT_MD5
      MD5Context context;
      char digest[33];
      char dest2[16];
      int i;
      
      if (size < 32)
        return -1;
      
      memset (&context, 0, sizeof (context));
      memset (&digest, 0, sizeof (digest));
      
      MD5Init (&context);
      MD5Update (&context, (unsigned char const *) src, (size_t) len);
      MD5Final ((unsigned char *) digest, &context);
      
      for (i = 0; i < 32; i += 2)
        dest2[i / 2] = XTOI (digest[i]) << 4 | XTOI (digest[i + 1]);
      
      /* convert to hex, skipping last 8 bytes (constant) -- jilles */
      strcpy (dest, "$ircservices$");
      for (i = 0; i <= 7; i++)
        sprintf (dest + 13 + 2 * i, "%02x", 255 & dest2[i]);
      return 0;
      
#endif
      
      return -1;			/* unknown encryption algorithm */
    }
    
#if 0				/* unused */
    /* Shortcut for encrypting a null-terminated string in place. */
    static int
    encrypt_in_place (char *buf, int size)
    {
      return encrypt (buf, strlen (buf), buf, size);
    }
#endif
    
    /**
     * Compare a plaintext string against an encrypted password.  Return 1 if
     * they match, 0 if not, and -1 if something went wrong.
     */
    static int
    check_password (char const * const plaintext, char const * const password)
    {
      char buf[BUFSIZE];
      
      if (encrypt (plaintext, strlen (plaintext), buf, sizeof (buf)) < 0)
        return -1;
#ifdef ENCRYPT_MD5
      if (strcmp (buf, password) == 0)
#else
        if (0)
#endif
          return 1;
        else
          return 0;
    }
  } // namespace impl
  
  /*************************************************************************/
    
  struct ircservices : handler
  {
    virtual char const *crypt (char const * const key, char const * const salt);
  };

  char const *
  ircservices::crypt (char const * const key, char const * const salt)
  {
    static char output[PASSMAX];
    if (salt[0] == '$' && salt[1] == '1')	/* this is a new pw XXX */
      {
        impl::encrypt (key, strlen (key), output, PASSMAX);
        return output;
      }
    else
      {
        if (impl::check_password (key, salt))
          return salt;
        else
          return "";
      }
  }
} // namespace crypto

#define FACREG_TYPE crypto::ircservices
#define FACREG_TYPE_NAME "ircservices"
#define FACREG_INTERFACE_TYPE crypto::handler
#include <ermyth/factory_reg.h>