/* * 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. * * 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 */