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Diffstat (limited to 'src/openvpn/comp.h')
| -rw-r--r-- | src/openvpn/comp.h | 198 |
1 files changed, 198 insertions, 0 deletions
diff --git a/src/openvpn/comp.h b/src/openvpn/comp.h new file mode 100644 index 0000000..9ed9532 --- /dev/null +++ b/src/openvpn/comp.h @@ -0,0 +1,198 @@ +/* + * 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 + */ + +/* + * Generic compression support. Currently we support + * LZO 2 and LZ4. + */ +#ifndef OPENVPN_COMP_H +#define OPENVPN_COMP_H + +#ifdef USE_COMP + +#include "buffer.h" +#include "mtu.h" +#include "common.h" +#include "status.h" + +/* algorithms */ +#define COMP_ALG_UNDEF 0 +#define COMP_ALG_STUB 1 /* support compression command byte and framing without actual compression */ +#define COMP_ALG_LZO 2 /* LZO algorithm */ +#define COMP_ALG_SNAPPY 3 /* Snappy algorithm (no longer supported) */ +#define COMP_ALG_LZ4 4 /* LZ4 algorithm */ + + +/* algorithm v2 */ +#define COMP_ALGV2_UNCOMPRESSED 10 +#define COMP_ALGV2_LZ4 11 +/* +#define COMP_ALGV2_LZO 12 +#define COMP_ALGV2_SNAPPY 13 +*/ + +/* Compression flags */ +#define COMP_F_ADAPTIVE (1<<0) /* COMP_ALG_LZO only */ +#define COMP_F_ASYM (1<<1) /* only downlink is compressed, not uplink */ +#define COMP_F_SWAP (1<<2) /* initial command byte is swapped with last byte in buffer to preserve payload alignment */ +#define COMP_F_ADVERTISE_STUBS_ONLY (1<<3) /* tell server that we only support compression stubs */ + + +/* + * Length of prepended prefix on compressed packets + */ +#define COMP_PREFIX_LEN 1 + +/* + * Prefix bytes + */ + +/* V1 on wire codes */ +/* Initial command byte to tell our peer if we compressed */ +#define LZO_COMPRESS_BYTE 0x66 +#define LZ4_COMPRESS_BYTE 0x69 +#define NO_COMPRESS_BYTE 0xFA +#define NO_COMPRESS_BYTE_SWAP 0xFB /* to maintain payload alignment, replace this byte with last byte of packet */ + +/* V2 on wire code */ +#define COMP_ALGV2_INDICATOR_BYTE 0x50 +#define COMP_ALGV2_UNCOMPRESSED_BYTE 0 +#define COMP_ALGV2_LZ4_BYTE 1 +#define COMP_ALGV2_LZO_BYTE 2 +#define COMP_ALGV2_SNAPPY_BYTE 3 + +/* + * Compress worst case size expansion (for any algorithm) + * + * LZO: len + len/8 + 128 + 3 + * Snappy: len + len/6 + 32 + * LZ4: len + len/255 + 16 (LZ4_COMPRESSBOUND(len)) + */ +#define COMP_EXTRA_BUFFER(len) ((len)/6 + 128 + 3 + COMP_PREFIX_LEN) + +/* + * Don't try to compress any packet smaller than this. + */ +#define COMPRESS_THRESHOLD 100 + +/* Forward declaration of compression context */ +struct compress_context; + +/* + * Virtual methods and other static info for each compression algorithm + */ +struct compress_alg +{ + const char *name; + void (*compress_init)(struct compress_context *compctx); + void (*compress_uninit)(struct compress_context *compctx); + void (*compress)(struct buffer *buf, struct buffer work, + struct compress_context *compctx, + const struct frame* frame); + + void (*decompress)(struct buffer *buf, struct buffer work, + struct compress_context *compctx, + const struct frame* frame); +}; + +/* + * Headers for each compression implementation + */ +#ifdef ENABLE_LZO +#include "lzo.h" +#endif + +#ifdef ENABLE_LZ4 +#include "comp-lz4.h" +#endif + +/* + * Information that basically identifies a compression + * algorithm and related flags. + */ +struct compress_options +{ + int alg; + unsigned int flags; +}; + +/* + * Workspace union of all supported compression algorithms + */ +union compress_workspace_union +{ +#ifdef ENABLE_LZO + struct lzo_compress_workspace lzo; +#endif +#ifdef ENABLE_LZ4 + struct lz4_workspace lz4; +#endif +}; + +/* + * Context for active compression session + */ +struct compress_context +{ + unsigned int flags; + struct compress_alg alg; + union compress_workspace_union wu; + + /* statistics */ + counter_type pre_decompress; + counter_type post_decompress; + counter_type pre_compress; + counter_type post_compress; +}; + +extern const struct compress_alg comp_stub_alg; +extern const struct compress_alg compv2_stub_alg; + +struct compress_context *comp_init(const struct compress_options *opt); + +void comp_uninit(struct compress_context *compctx); + +void comp_add_to_extra_frame(struct frame *frame); +void comp_add_to_extra_buffer(struct frame *frame); + +void comp_print_stats (const struct compress_context *compctx, struct status_output *so); + +void comp_generate_peer_info_string(const struct compress_options *opt, struct buffer *out); + +void compv2_escape_data_ifneeded (struct buffer *buf); + +static inline bool +comp_enabled(const struct compress_options *info) +{ + return info->alg != COMP_ALG_UNDEF; +} + +static inline bool +comp_unswapped_prefix(const struct compress_options *info) +{ + return !(info->flags & COMP_F_SWAP); +} + +#endif /* USE_COMP */ +#endif |