lzf.c

twocrypt(2c)是一个 PoC工具

/*
   lzf.c - fast compression and decompression support
   --------------------------------------------------

   Extremely fast and surprisingly robust block compression by Marc
   Alexander Lehmann, adopted and simplified for 2c. I've fixed some 
   things in the code, including one bug.

   Original copyright follows:

   -- snip! --

   Copyright (c) 2000-2002 Marc Alexander Lehmann <[e-mail]>
  
   Redistribution and use in source and binary forms, with or without 
   modification, are permitted provided that the following conditions are 
   met:

   1.  Redistributions of source code must retain the above copyright notice,
       this list of conditions and the following disclaimer.
 
   2.  Redistributions in binary form must reproduce the above copyright
       notice, this list of conditions and the following disclaimer in the
       documentation and/or other materials provided with the distribution.

   3.  The name of the author may not be used to endorse or promote products
       derived from this software without specific prior written permission.

   THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR 
   IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES 
   OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.  
   IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, 
   SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
   PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS;
   OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY,
   WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR 
   OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF 
   ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.

 */

#include <stdio.h>
#include <stdlib.h>
#include <unistd.h>
#include "macros.h"
#include "lzf.h"

_u32 lzf (const _u8* in, _u32 ilen, _u8* out, _u32 olen) {

  _u8 *htab[1<<HLOG], **hslot, *ip = (_u8*)in, *op = out,
                *iend  = ip + ilen, *oend = op + olen, *ref;

  _u32 hval = (ip[0] << 8) + ip[1], off;
  _s32 lit = 0;

  do {

    hval   = ( hval << 8 ) + (ip + 2 < iend) ? ip[2] : 0;
    hslot  = htab + IDX (hval);
    ref    = *hslot; 
    *hslot = ip;

    if ((off = ip - ref - 1) < MAX_OFF && ip + 4 < iend && 
         ref > in && *(_u16*)ref == *(_u16*)ip && 
         ref[2] == ip[2] ) {

      _u32 len = 2;
      _u32 maxlen = iend - ip - len;
 
      maxlen = maxlen > MAX_REF ? MAX_REF : maxlen;

      do len++; while (len < maxlen && ref[len] == ip[len]);

      if (op + lit + 1 + 3 >= oend) return 0;

      if (lit) {
        *op++ = lit - 1;
        lit = -lit; 
        do *op++ = ip[lit]; while (++lit);
      }

      len -= 2;
      ip++;

      if (len < 7) {
        *op++ = (off >> 8) + (len << 5);
      } else {
        *op++ = (off >> 8) + (  7 << 5);
        *op++ = len - 7;
      }

      *op++ = off;
      ip += len;
      hval = ( ip[0] << 8 ) + ip[1];
      hval = ( hval << 8 ) + ip[2];
      htab[IDX (hval)] = ip;
      ip++;

    } else {
      lit++;
      ip++;

      if (lit == MAX_LIT) {
        if (op + 1 + MAX_LIT >= oend) return 0;
        *op++ = MAX_LIT - 1;
        lit = -lit;
        do *op++ = ip[lit]; while (++lit);
      }
    }

  } while (ip < iend);

  if (lit) {
    if (op + lit + 1 >= oend) return 0;
    *op++ = lit - 1;
    lit = -lit;
    do *op++ = ip[lit]; while (++lit);
  }

  return op - out;

}



_u32 unlzf (const _u8* in, _u32 ilen, _u8* out,_u32 olen) {

  _u8 *op = out, *iend = (_u8*)in + ilen, *oend = out + olen;

  do {

    _u32 ctrl = *in++;

    if (ctrl < (1 << 5)) {
      ctrl++;
      if (op + ctrl > oend)
        fatal("[-] Decompression: file corrupted 1 (bad password?)..\n");

      do *op++ = *in++; while (--ctrl);

    } else {
      _u32 len   = ctrl >> 5;
      _u8 *ref = op - ((ctrl & 0x1f) << 8) - 1;

      if (len == 7) len += *in++;
          
      ref -= *in++;

      if (op + len + 2 > oend)
        fatal("[-] Decompression: file corrupted 2 (bad password?).\n");

      if (ref < out)
        fatal("[-] Decompression: file corrupted 3 (bad password?).\n");

      *op++ = *ref++;
      *op++ = *ref++;

      do *op++ = *ref++; while (--len);
    }
  }

  while (op < oend && in < iend);

  return op - out;
}