/*
  *  OpenVPN -- An application to securely tunnel IP networks
  *             over a single UDP port, with support for SSL/TLS-based
  *             session authentication and key exchange,
  *             packet encryption, packet authentication, and
  *             packet compression.
  *

  *  Copyright (C) 2002-2008 Telethra, Inc. <sales@openvpn.net>

  *
  *  This program is free software; you can redistribute it and/or modify
  *  it under the terms of the GNU General Public License version 2
  *  as published by the Free Software Foundation.
  *
  *  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 (see the file COPYING included with this
  *  distribution); if not, write to the Free Software Foundation, Inc.,
  *  59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
  */
 

 #include "syshead.h"

 
 #ifdef USE_LZO
 
 #include "lzo.h"
 #include "error.h"
 #include "otime.h"
 
 #include "memdbg.h"
 
 static bool
 lzo_adaptive_compress_test (struct lzo_adaptive_compress *ac)
 {
   const bool save = ac->compress_state;
   const time_t local_now = now;
 
   if (!ac->compress_state)
     {
       if (local_now >= ac->next)
 	{
 	  if (ac->n_total > AC_MIN_BYTES
 	      && (ac->n_total - ac->n_comp) < (ac->n_total / (100 / AC_SAVE_PCT)))
 	    {
 	      ac->compress_state = true;
 	      ac->next = local_now + AC_OFF_SEC;
 	    }
 	  else
 	    {
 	      ac->next = local_now + AC_SAMP_SEC;
 	    }
 	  dmsg (D_COMP, "lzo_adaptive_compress_test: comp=%d total=%d", ac->n_comp, ac->n_total);
 	  ac->n_total = ac->n_comp = 0;
 	}
     }
   else 
     {
       if (local_now >= ac->next)
 	{
 	  ac->next = local_now + AC_SAMP_SEC;
 	  ac->n_total = ac->n_comp = 0;
 	  ac->compress_state = false;
 	}
     }
 
   if (ac->compress_state != save)
     dmsg (D_COMP_LOW, "Adaptive compression state %s", (ac->compress_state ? "OFF" : "ON"));
 
   return !ac->compress_state;
 }
 

 static inline void

 lzo_adaptive_compress_data (struct lzo_adaptive_compress *ac, int n_total, int n_comp)
 {

   ac->n_total += n_total;
   ac->n_comp += n_comp;

 }
 
 void lzo_adjust_frame_parameters (struct frame *frame)
 {
   /* Leave room for our one-byte compressed/didn't-compress prefix byte. */
   frame_add_to_extra_frame (frame, LZO_PREFIX_LEN);
 
   /* Leave room for compression buffer to expand in worst case scenario
      where data is totally uncompressible */
   frame_add_to_extra_buffer (frame, LZO_EXTRA_BUFFER (EXPANDED_SIZE(frame)));
 }
 
 void

 lzo_compress_init (struct lzo_compress_workspace *lzowork, unsigned int flags)

 {
   CLEAR (*lzowork);
 
   lzowork->wmem_size = LZO_WORKSPACE;

   lzowork->flags = flags;

 
   if (lzo_init () != LZO_E_OK)
     msg (M_FATAL, "Cannot initialize LZO compression library");
   lzowork->wmem = (lzo_voidp) lzo_malloc (lzowork->wmem_size);
   check_malloc_return (lzowork->wmem);
   msg (M_INFO, "LZO compression initialized");

   lzowork->defined = true;

 }
 
 void
 lzo_compress_uninit (struct lzo_compress_workspace *lzowork)
 {
   if (lzowork)
     {

       ASSERT (lzowork->defined);

       lzo_free (lzowork->wmem);
       lzowork->wmem = NULL;

       lzowork->defined = false;
     }
 }
 
 static inline bool
 lzo_compression_enabled (struct lzo_compress_workspace *lzowork)
 {
   if ((lzowork->flags & (LZO_SELECTED|LZO_ON)) == (LZO_SELECTED|LZO_ON))
     {
       if (lzowork->flags & LZO_ADAPTIVE)
 	return lzo_adaptive_compress_test (&lzowork->ac);
       else
 	return true;

     }

   return false;

 }
 
 /* Magic numbers to tell our peer if we compressed or not */
 #define YES_COMPRESS 0x66
 #define NO_COMPRESS  0xFA
 
 void
 lzo_compress (struct buffer *buf, struct buffer work,
 	      struct lzo_compress_workspace *lzowork,
 	      const struct frame* frame)
 {
   lzo_uint zlen = 0;
   int err;
   bool compressed = false;
 

   ASSERT (lzowork->defined);
 

   if (buf->len <= 0)
     return;
 
   /*
    * In order to attempt compression, length must be at least COMPRESS_THRESHOLD,
    * and our adaptive level must give the OK.
    */

   if (buf->len >= COMPRESS_THRESHOLD && lzo_compression_enabled (lzowork))

     {
       ASSERT (buf_init (&work, FRAME_HEADROOM (frame)));
       ASSERT (buf_safe (&work, LZO_EXTRA_BUFFER (PAYLOAD_SIZE (frame))));

 
       if (!(buf->len <= PAYLOAD_SIZE (frame)))
 	{
 	  dmsg (D_COMP_ERRORS, "LZO compression buffer overflow");
 	  buf->len = 0;
 	  return;
 	}

 
       err = LZO_COMPRESS (BPTR (buf), BLEN (buf), BPTR (&work), &zlen, lzowork->wmem);
       if (err != LZO_E_OK)
 	{
 	  dmsg (D_COMP_ERRORS, "LZO compression error: %d", err);
 	  buf->len = 0;
 	  return;
 	}
 
       ASSERT (buf_safe (&work, zlen));
       work.len = zlen;
       compressed = true;
 
       dmsg (D_COMP, "compress %d -> %d", buf->len, work.len);
       lzowork->pre_compress += buf->len;
       lzowork->post_compress += work.len;
 
       /* tell adaptive level about our success or lack thereof in getting any size reduction */

       if (lzowork->flags & LZO_ADAPTIVE)
 	lzo_adaptive_compress_data (&lzowork->ac, buf->len, work.len);

     }
 
   /* did compression save us anything ? */
   if (compressed && work.len < buf->len)
     {
       uint8_t *header = buf_prepend (&work, 1);
       *header = YES_COMPRESS;
       *buf = work;
     }
   else
     {
       uint8_t *header = buf_prepend (buf, 1);
       *header = NO_COMPRESS;
     }
 }
 
 void
 lzo_decompress (struct buffer *buf, struct buffer work,
 		struct lzo_compress_workspace *lzowork,
 		const struct frame* frame)
 {
   lzo_uint zlen = EXPANDED_SIZE (frame);
   uint8_t c;		/* flag indicating whether or not our peer compressed */
   int err;
 

   ASSERT (lzowork->defined);
 

   if (buf->len <= 0)
     return;
 
   ASSERT (buf_init (&work, FRAME_HEADROOM (frame)));
 
   c = *BPTR (buf);
   ASSERT (buf_advance (buf, 1));
 
   if (c == YES_COMPRESS)	/* packet was compressed */
     {
       ASSERT (buf_safe (&work, zlen));
       err = LZO_DECOMPRESS (BPTR (buf), BLEN (buf), BPTR (&work), &zlen,
 			    lzowork->wmem);
       if (err != LZO_E_OK)
 	{
 	  dmsg (D_COMP_ERRORS, "LZO decompression error: %d", err);
 	  buf->len = 0;
 	  return;
 	}
 
       ASSERT (buf_safe (&work, zlen));
       work.len = zlen;
 
       dmsg (D_COMP, "decompress %d -> %d", buf->len, work.len);
       lzowork->pre_decompress += buf->len;
       lzowork->post_decompress += work.len;
 
       *buf = work;
     }
   else if (c == NO_COMPRESS)	/* packet was not compressed */
     {
       ;
     }
   else
     {
       dmsg (D_COMP_ERRORS, "Bad LZO decompression header byte: %d", c);
       buf->len = 0;
     }
 }
 

 void
 lzo_modify_flags (struct lzo_compress_workspace *lzowork, unsigned int flags)
 {
   ASSERT (lzowork->defined);
   lzowork->flags = flags;
 }
 

 /*
  * Print statistics
  */
 void lzo_print_stats (const struct lzo_compress_workspace *lzo_compwork, struct status_output *so)
 {

   ASSERT (lzo_compwork->defined);
 

   status_printf (so, "pre-compress bytes," counter_format, lzo_compwork->pre_compress);
   status_printf (so, "post-compress bytes," counter_format, lzo_compwork->post_compress);
   status_printf (so, "pre-decompress bytes," counter_format, lzo_compwork->pre_decompress);
   status_printf (so, "post-decompress bytes," counter_format, lzo_compwork->post_decompress);
 }
 
 #else
 static void dummy(void) {}
 #endif /* USE_LZO */