/*:*
 *: File: ./src/contrib/crypt/md5crypt.cpp
 *: 
 *: yChat; Homepage: www.yChat.org; Version 0.7.9.5-RELEASE
 *: 
 *: Copyright (C) 2003 Paul C. Buetow, Volker Richter
 *: Copyright (C) 2004 Paul C. Buetow
 *: Copyright (C) 2005 EXA Digital Solutions GbR
 *: 
 *: 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.
 *:*/

/*
 * ----------------------------------------------------------------------------
 * "THE BEER-WARE LICENSE" (Revision 42):
 * <phk@login.dknet.dk> wrote this file.  As long as you retain this notice you
 * can do whatever you want with this stuff. If we meet some day, and you think
 * this stuff is worth it, you can buy me a beer in return.   Poul-Henning Kamp
 * ----------------------------------------------------------------------------
 */

/*
 * Ported from FreeBSD to Linux, only minimal changes.  --marekm
 */

#include <unistd.h>
/* #include <stdio.h> */
#include <string.h>
#include "md5.h"

namespace md5
{

static unsigned char itoa64[] =		/* 0 ... 63 => ascii - 64 */
  "./0123456789ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz";

static void
to64(char *s, unsigned long v, int n)
{
  while (--n >= 0)
  {
    *s++ = itoa64[v&0x3f];
    v >>= 6;
  }
}

/*
 * UNIX password
 *
 * Use MD5 for what it is best at...
 */

char *
MD5Crypt(const char *pw, const char *salt)
{
  static char	*magic = "$1$";	/*
                      						 * This string is magic for
                      						 * this algorithm.  Having
                      						 * it this way, we can get
                      						 * get better later on
                      						 */
  static char     passwd[120], *p;
  static const char *sp,*ep;
  unsigned char	final[16];
  int sl,pl,i,j;
  MD5_CTX	ctx,ctx1;
  unsigned long l;

  /* Refine the Salt first */
  sp = salt;

  /* If it starts with the magic string, then skip that */
  if(!strncmp(sp,magic,strlen(magic)))
    sp += strlen(magic);

  /* It stops at the first '$', max 8 chars */
  for(ep=sp;*ep && *ep != '$' && ep < (sp+8);ep++)
    continue;

  /* get the length of the true salt */
  sl = ep - sp;

  MD5Init(&ctx);

  /* The password first, since that is what is most unknown */
  MD5Update(&ctx,(const unsigned char*)pw,strlen(pw));

  /* Then our magic string */
  MD5Update(&ctx,(const unsigned char*)magic,strlen(magic));

  /* Then the raw salt */
  MD5Update(&ctx,(const unsigned char*)sp,sl);

  /* Then just as many characters of the MD5(pw,salt,pw) */
  MD5Init(&ctx1);
  MD5Update(&ctx1,(const unsigned char*)pw,strlen(pw));
  MD5Update(&ctx1,(const unsigned char*)sp,sl);
  MD5Update(&ctx1,(const unsigned char*)pw,strlen(pw));
  MD5Final(final,&ctx1);
  for(pl = strlen(pw); pl > 0; pl -= 16)
    MD5Update(&ctx,final,pl>16 ? 16 : pl);

  /* Don't leave anything around in vm they could use. */
  memset(final,0,sizeof final);

  /* Then something really weird... */
  for (j=0,i = strlen(pw); i ; i >>= 1)
    if(i&1)
      MD5Update(&ctx, final+j, 1);
    else
      MD5Update(&ctx, (const unsigned char*)pw+j, 1);

  /* Now make the output string */
  strcpy(passwd,magic);
  strncat(passwd,sp,sl);
  strcat(passwd,"$");

  MD5Final(final,&ctx);

  /*
   * and now, just to make sure things don't run too fast
   * On a 60 Mhz Pentium this takes 34 msec, so you would
   * need 30 seconds to build a 1000 entry dictionary...
   */
  for(i=0;i<1000;i++)
  {
    MD5Init(&ctx1);
    if(i & 1)
      MD5Update(&ctx1,(const unsigned char*)pw,strlen(pw));
    else
      MD5Update(&ctx1,final,16);

    if(i % 3)
      MD5Update(&ctx1,(const unsigned char*)sp,sl);

    if(i % 7)
      MD5Update(&ctx1,(const unsigned char*)pw,strlen(pw));

    if(i & 1)
      MD5Update(&ctx1,final,16);
    else
      MD5Update(&ctx1,(const unsigned char*)pw,strlen(pw));
    MD5Final(final,&ctx1);
  }

  p = passwd + strlen(passwd);

  l = (final[ 0]<<16) | (final[ 6]<<8) | final[12];
  to64(p,l,4);
  p += 4;
  l = (final[ 1]<<16) | (final[ 7]<<8) | final[13];
  to64(p,l,4);
  p += 4;
  l = (final[ 2]<<16) | (final[ 8]<<8) | final[14];
  to64(p,l,4);
  p += 4;
  l = (final[ 3]<<16) | (final[ 9]<<8) | final[15];
  to64(p,l,4);
  p += 4;
  l = (final[ 4]<<16) | (final[10]<<8) | final[ 5];
  to64(p,l,4);
  p += 4;
  l =                    final[11]                ;
  to64(p,l,2);
  p += 2;
  *p = '\0';

  /* Don't leave anything around in vm they could use. */
  memset(final,0,sizeof final);

  return passwd;
}

}