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/*
* 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) 2002-2010 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
*/
/**
* @file Data Channel Compression module function definitions.
*/
#ifdef HAVE_CONFIG_H
#include "config.h"
#elif defined(_MSC_VER)
#include "config-msvc.h"
#endif
#include "syshead.h"
#if defined(ENABLE_LZO)
#include "comp.h"
#include "error.h"
#include "otime.h"
#include "memdbg.h"
/* Initial command byte to tell our peer if we compressed */
#define LZO_COMPRESS_BYTE 0x66
/**
* Perform adaptive compression housekeeping.
*
* @param ac the adaptive compression state structure.
*
* @return
*/
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;
}
static void
lzo_compress_init (struct compress_context *compctx)
{
msg (D_INIT_MEDIUM, "LZO compression initializing");
ASSERT(!(compctx->flags & COMP_F_SWAP));
compctx->wu.lzo.wmem_size = LZO_WORKSPACE;
if (lzo_init () != LZO_E_OK)
msg (M_FATAL, "Cannot initialize LZO compression library");
compctx->wu.lzo.wmem = (lzo_voidp) lzo_malloc (compctx->wu.lzo.wmem_size);
check_malloc_return (compctx->wu.lzo.wmem);
}
static void
lzo_compress_uninit (struct compress_context *compctx)
{
lzo_free (compctx->wu.lzo.wmem);
compctx->wu.lzo.wmem = NULL;
}
static inline bool
lzo_compression_enabled (struct compress_context *compctx)
{
if (compctx->flags & COMP_F_ASYM)
return false;
else
{
if (compctx->flags & COMP_F_ADAPTIVE)
return lzo_adaptive_compress_test (&compctx->wu.lzo.ac);
else
return true;
}
}
static void
lzo_compress (struct buffer *buf, struct buffer work,
struct compress_context *compctx,
const struct frame* frame)
{
lzo_uint zlen = 0;
int err;
bool compressed = false;
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 (compctx))
{
const size_t ps = PAYLOAD_SIZE (frame);
ASSERT (buf_init (&work, FRAME_HEADROOM (frame)));
ASSERT (buf_safe (&work, ps + COMP_EXTRA_BUFFER (ps)));
if (buf->len > ps)
{
dmsg (D_COMP_ERRORS, "LZO compression buffer overflow");
buf->len = 0;
return;
}
err = LZO_COMPRESS (BPTR (buf), BLEN (buf), BPTR (&work), &zlen, compctx->wu.lzo.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, "LZO compress %d -> %d", buf->len, work.len);
compctx->pre_compress += buf->len;
compctx->post_compress += work.len;
/* tell adaptive level about our success or lack thereof in getting any size reduction */
if (compctx->flags & COMP_F_ADAPTIVE)
lzo_adaptive_compress_data (&compctx->wu.lzo.ac, buf->len, work.len);
}
/* did compression save us anything ? */
if (compressed && work.len < buf->len)
{
uint8_t *header = buf_prepend (&work, 1);
*header = LZO_COMPRESS_BYTE;
*buf = work;
}
else
{
uint8_t *header = buf_prepend (buf, 1);
*header = NO_COMPRESS_BYTE;
}
}
static void
lzo_decompress (struct buffer *buf, struct buffer work,
struct compress_context *compctx,
const struct frame* frame)
{
lzo_uint zlen = EXPANDED_SIZE (frame);
int err;
uint8_t c; /* flag indicating whether or not our peer compressed */
if (buf->len <= 0)
return;
ASSERT (buf_init (&work, FRAME_HEADROOM (frame)));
c = *BPTR (buf);
ASSERT (buf_advance (buf, 1));
if (c == LZO_COMPRESS_BYTE) /* packet was compressed */
{
ASSERT (buf_safe (&work, zlen));
err = LZO_DECOMPRESS (BPTR (buf), BLEN (buf), BPTR (&work), &zlen,
compctx->wu.lzo.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, "LZO decompress %d -> %d", buf->len, work.len);
compctx->pre_decompress += buf->len;
compctx->post_decompress += work.len;
*buf = work;
}
else if (c == NO_COMPRESS_BYTE) /* packet was not compressed */
{
;
}
else
{
dmsg (D_COMP_ERRORS, "Bad LZO decompression header byte: %d", c);
buf->len = 0;
}
}
const struct compress_alg lzo_alg = {
"lzo",
lzo_compress_init,
lzo_compress_uninit,
lzo_compress,
lzo_decompress
};
#else
static void dummy(void) {}
#endif /* ENABLE_LZO */
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