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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) 2002-2021 OpenVPN 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; if not, write to the Free Software Foundation, Inc.,
* 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 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;
break;
case COMP_ALGV2_UNCOMPRESSED:
ALLOC_OBJ_CLEAR(compctx, struct compress_context);
compctx->flags = opt->flags;
compctx->alg = compv2_stub_alg;
break;
#ifdef ENABLE_LZO
case COMP_ALG_LZO:
ALLOC_OBJ_CLEAR(compctx, struct compress_context);
compctx->flags = opt->flags;
compctx->alg = lzo_alg;
break;
#endif
#ifdef ENABLE_LZ4
case COMP_ALG_LZ4:
ALLOC_OBJ_CLEAR(compctx, struct compress_context);
compctx->flags = opt->flags;
compctx->alg = lz4_alg;
break;
case COMP_ALGV2_LZ4:
ALLOC_OBJ_CLEAR(compctx, struct compress_context);
compctx->flags = opt->flags;
compctx->alg = lz4v2_alg;
break;
#endif
}
if (compctx)
{
(*compctx->alg.compress_init)(compctx);
}
return compctx;
}
/* In the v2 compression schemes, an uncompressed packet has
* has no opcode in front, unless the first byte is 0x50. In this
* case the packet needs to be escaped */
void
compv2_escape_data_ifneeded(struct buffer *buf)
{
uint8_t *head = BPTR(buf);
if (head[0] != COMP_ALGV2_INDICATOR_BYTE)
{
return;
}
/* Header is 0x50 */
ASSERT(buf_prepend(buf, 2));
head = BPTR(buf);
head[0] = COMP_ALGV2_INDICATOR_BYTE;
head[1] = COMP_ALGV2_UNCOMPRESSED;
}
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 incompressible */
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");
buf_printf(out, "IV_LZ4v2=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");
buf_printf(out, "IV_COMP_STUBv2=1\n");
buf_printf(out, "IV_TCPNL=1\n");
}
}
#endif /* USE_COMP */
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