src/openvpn/lzo.c

   1 /*
   2  *  OpenVPN -- An application to securely tunnel IP networks
   3  *             over a single UDP port, with support for SSL/TLS-based
   4  *             session authentication and key exchange,
   5  *             packet encryption, packet authentication, and
   6  *             packet compression.
   7  *
   8  *  Copyright (C) 2002-2005 OpenVPN Solutions LLC <info@openvpn.net>
   9  *
  10  *  This program is free software; you can redistribute it and/or modify
  11  *  it under the terms of the GNU General Public License version 2
  12  *  as published by the Free Software Foundation.
  13  *
  14  *  This program is distributed in the hope that it will be useful,
  15  *  but WITHOUT ANY WARRANTY; without even the implied warranty of
  16  *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  17  *  GNU General Public License for more details.
  18  *
  19  *  You should have received a copy of the GNU General Public License
  20  *  along with this program (see the file COPYING included with this
  21  *  distribution); if not, write to the Free Software Foundation, Inc.,
  22  *  59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
  23  */
  24
  25 #ifdef WIN32
  26 #include "config-win32.h"
  27 #else
  28 #include "config.h"
  29 #endif
  30
  31 #ifdef USE_LZO
  32
  33 #include "syshead.h"
  34
  35 #include "lzo.h"
  36 #include "error.h"
  37 #include "otime.h"
  38
  39 #include "memdbg.h"
  40
  41 static bool
  42 lzo_adaptive_compress_test (struct lzo_adaptive_compress *ac)
  43 {
  44   const bool save = ac->compress_state;
  45   const time_t local_now = now;
  46
  47   if (!ac->enabled)
  48     return true;
  49
  50   if (!ac->compress_state)
  51     {
  52       if (local_now >= ac->next)
  53         {
  54           if (ac->n_total > AC_MIN_BYTES
  55               && (ac->n_total - ac->n_comp) < (ac->n_total / (100 / AC_SAVE_PCT)))
  56             {
  57               ac->compress_state = true;
  58               ac->next = local_now + AC_OFF_SEC;
  59             }
  60           else
  61             {
  62               ac->next = local_now + AC_SAMP_SEC;
  63             }
  64           dmsg (D_COMP, "lzo_adaptive_compress_test: comp=%d total=%d", ac->n_comp, ac->n_total);
  65           ac->n_total = ac->n_comp = 0;
  66         }
  67     }
  68   else
  69     {
  70       if (local_now >= ac->next)
  71         {
  72           ac->next = local_now + AC_SAMP_SEC;
  73           ac->n_total = ac->n_comp = 0;
  74           ac->compress_state = false;
  75         }
  76     }
  77
  78   if (ac->compress_state != save)
  79     dmsg (D_COMP_LOW, "Adaptive compression state %s", (ac->compress_state ? "OFF" : "ON"));
  80
  81   return !ac->compress_state;
  82 }
  83
  84 static inline void
  85 lzo_adaptive_compress_data (struct lzo_adaptive_compress *ac, int n_total, int n_comp)
  86 {
  87   if (ac->enabled)
  88     {
  89       ac->n_total += n_total;
  90       ac->n_comp += n_comp;
  91     }
  92 }
  93
  94 void lzo_adjust_frame_parameters (struct frame *frame)
  95 {
  96   /* Leave room for our one-byte compressed/didn't-compress prefix byte. */
  97   frame_add_to_extra_frame (frame, LZO_PREFIX_LEN);
  98
  99   /* Leave room for compression buffer to expand in worst case scenario
 100      where data is totally uncompressible */
 101   frame_add_to_extra_buffer (frame, LZO_EXTRA_BUFFER (EXPANDED_SIZE(frame)));
 102 }
 103
 104 void
 105 lzo_compress_init (struct lzo_compress_workspace *lzowork, bool adaptive)
 106 {
 107   CLEAR (*lzowork);
 108
 109   lzowork->wmem_size = LZO_WORKSPACE;
 110   lzowork->ac.enabled = adaptive;
 111
 112   if (lzo_init () != LZO_E_OK)
 113     msg (M_FATAL, "Cannot initialize LZO compression library");
 114   lzowork->wmem = (lzo_voidp) lzo_malloc (lzowork->wmem_size);
 115   check_malloc_return (lzowork->wmem);
 116   msg (M_INFO, "LZO compression initialized");
 117 }
 118
 119 void
 120 lzo_compress_uninit (struct lzo_compress_workspace *lzowork)
 121 {
 122   if (lzowork)
 123     {
 124       lzo_free (lzowork->wmem);
 125       lzowork->wmem = NULL;
 126     }
 127 }
 128
 129 /* Magic numbers to tell our peer if we compressed or not */
 130 #define YES_COMPRESS 0x66
 131 #define NO_COMPRESS  0xFA
 132
 133 void
 134 lzo_compress (struct buffer *buf, struct buffer work,
 135               struct lzo_compress_workspace *lzowork,
 136               const struct frame* frame)
 137 {
 138   lzo_uint zlen = 0;
 139   int err;
 140   bool compressed = false;
 141
 142   if (buf->len <= 0)
 143     return;
 144
 145   /*
 146    * In order to attempt compression, length must be at least COMPRESS_THRESHOLD,
 147    * and our adaptive level must give the OK.
 148    */
 149   if (buf->len >= COMPRESS_THRESHOLD && lzo_adaptive_compress_test (&lzowork->ac))
 150     {
 151       ASSERT (buf_init (&work, FRAME_HEADROOM (frame)));
 152       ASSERT (buf_safe (&work, LZO_EXTRA_BUFFER (PAYLOAD_SIZE (frame))));
 153       ASSERT (buf->len <= PAYLOAD_SIZE (frame));
 154
 155       err = LZO_COMPRESS (BPTR (buf), BLEN (buf), BPTR (&work), &zlen, lzowork->wmem);
 156       if (err != LZO_E_OK)
 157         {
 158           dmsg (D_COMP_ERRORS, "LZO compression error: %d", err);
 159           buf->len = 0;
 160           return;
 161         }
 162
 163       ASSERT (buf_safe (&work, zlen));
 164       work.len = zlen;
 165       compressed = true;
 166
 167       dmsg (D_COMP, "compress %d -> %d", buf->len, work.len);
 168       lzowork->pre_compress += buf->len;
 169       lzowork->post_compress += work.len;
 170
 171       /* tell adaptive level about our success or lack thereof in getting any size reduction */
 172       lzo_adaptive_compress_data(&lzowork->ac, buf->len, work.len);
 173     }
 174
 175   /* did compression save us anything ? */
 176   if (compressed && work.len < buf->len)
 177     {
 178       uint8_t *header = buf_prepend (&work, 1);
 179       *header = YES_COMPRESS;
 180       *buf = work;
 181     }
 182   else
 183     {
 184       uint8_t *header = buf_prepend (buf, 1);
 185       *header = NO_COMPRESS;
 186     }
 187 }
 188
 189 void
 190 lzo_decompress (struct buffer *buf, struct buffer work,
 191                 struct lzo_compress_workspace *lzowork,
 192                 const struct frame* frame)
 193 {
 194   lzo_uint zlen = EXPANDED_SIZE (frame);
 195   uint8_t c;            /* flag indicating whether or not our peer compressed */
 196   int err;
 197
 198   if (buf->len <= 0)
 199     return;
 200
 201   ASSERT (buf_init (&work, FRAME_HEADROOM (frame)));
 202
 203   c = *BPTR (buf);
 204   ASSERT (buf_advance (buf, 1));
 205
 206   if (c == YES_COMPRESS)        /* packet was compressed */
 207     {
 208       ASSERT (buf_safe (&work, zlen));
 209       err = LZO_DECOMPRESS (BPTR (buf), BLEN (buf), BPTR (&work), &zlen,
 210                             lzowork->wmem);
 211       if (err != LZO_E_OK)
 212         {
 213           dmsg (D_COMP_ERRORS, "LZO decompression error: %d", err);
 214           buf->len = 0;
 215           return;
 216         }
 217
 218       ASSERT (buf_safe (&work, zlen));
 219       work.len = zlen;
 220
 221       dmsg (D_COMP, "decompress %d -> %d", buf->len, work.len);
 222       lzowork->pre_decompress += buf->len;
 223       lzowork->post_decompress += work.len;
 224
 225       *buf = work;
 226     }
 227   else if (c == NO_COMPRESS)    /* packet was not compressed */
 228     {
 229       ;
 230     }
 231   else
 232     {
 233       dmsg (D_COMP_ERRORS, "Bad LZO decompression header byte: %d", c);
 234       buf->len = 0;
 235     }
 236 }
 237
 238 /*
 239  * Print statistics
 240  */
 241 void lzo_print_stats (const struct lzo_compress_workspace *lzo_compwork, struct status_output *so)
 242 {
 243   status_printf (so, "pre-compress bytes," counter_format, lzo_compwork->pre_compress);
 244   status_printf (so, "post-compress bytes," counter_format, lzo_compwork->post_compress);
 245   status_printf (so, "pre-decompress bytes," counter_format, lzo_compwork->pre_decompress);
 246   status_printf (so, "post-decompress bytes," counter_format, lzo_compwork->post_decompress);
 247 }
 248
 249 #else
 250 static void dummy(void) {}
 251 #endif /* USE_LZO */