/*
 *  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) 2002-2012 OpenVPN Technologies, 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
 */

#ifdef HAVE_CONFIG_H
#include "config.h"
#elif defined(_MSC_VER)
#include "config-msvc.h"
#endif

#include "syshead.h"

#ifdef USE_COMP

#include "comp.h"
#include "error.h"
#include "otime.h"

#include "memdbg.h"

struct compress_context *
comp_init(const struct compress_options *opt)
{
  struct compress_context *compctx = NULL;
  switch (opt->alg)
    {
    case COMP_ALG_STUB:
      ALLOC_OBJ_CLEAR (compctx, struct compress_context);
      compctx->flags = opt->flags;
      compctx->alg = comp_stub_alg;
      (*compctx->alg.compress_init)(compctx);
      break;
#ifdef ENABLE_LZO
    case COMP_ALG_LZO:
      ALLOC_OBJ_CLEAR (compctx, struct compress_context);
      compctx->flags = opt->flags;
      compctx->alg = lzo_alg;
      (*compctx->alg.compress_init)(compctx);
      break;
#endif
#ifdef ENABLE_LZ4
    case COMP_ALG_LZ4:
      ALLOC_OBJ_CLEAR (compctx, struct compress_context);
      compctx->flags = opt->flags;
      compctx->alg = lz4_alg;
      (*compctx->alg.compress_init)(compctx);
      break;
#endif
    }
  return compctx;
}

void
comp_uninit(struct compress_context *compctx)
{
  if (compctx)
    {
      (*compctx->alg.compress_uninit)(compctx);
      free(compctx);
    }
}

void
comp_add_to_extra_frame(struct frame *frame)
{
  /* Leave room for our one-byte compressed/didn't-compress prefix byte. */
  frame_add_to_extra_frame (frame, COMP_PREFIX_LEN);
}

void
comp_add_to_extra_buffer(struct frame *frame)
{
  /* Leave room for compression buffer to expand in worst case scenario
     where data is totally uncompressible */
  frame_add_to_extra_buffer (frame, COMP_EXTRA_BUFFER (EXPANDED_SIZE(frame)));
}

void
comp_print_stats (const struct compress_context *compctx, struct status_output *so)
{
  if (compctx)
    {
      status_printf (so, "pre-compress bytes," counter_format, compctx->pre_compress);
      status_printf (so, "post-compress bytes," counter_format, compctx->post_compress);
      status_printf (so, "pre-decompress bytes," counter_format, compctx->pre_decompress);
      status_printf (so, "post-decompress bytes," counter_format, compctx->post_decompress);
    }
}

/*
 * Tell our peer which compression algorithms we support.
 */
void
comp_generate_peer_info_string(const struct compress_options *opt, struct buffer *out)
{
  if (opt)
    {
      bool lzo_avail = false;
      if (!(opt->flags & COMP_F_ADVERTISE_STUBS_ONLY))
	{
#if defined(ENABLE_LZ4)
	  buf_printf (out, "IV_LZ4=1\n");
#endif
#if defined(ENABLE_LZO)
	  buf_printf (out, "IV_LZO=1\n");
	  lzo_avail = true;
#endif
	}
      if (!lzo_avail)
	buf_printf (out, "IV_LZO_STUB=1\n");
      buf_printf (out, "IV_COMP_STUB=1\n");
    }
}

#endif /* USE_COMP */