net/sctp/tsnmap.c

   1 /* SCTP kernel reference Implementation
   2  * Copyright (c) 1999-2000 Cisco, Inc.
   3  * Copyright (c) 1999-2001 Motorola, Inc.
   4  * Copyright (c) 2001-2003 International Business Machines, Corp.
   5  * Copyright (c) 2001 Intel Corp.
   6  *
   7  * This file is part of the SCTP kernel reference Implementation
   8  *
   9  * These functions manipulate sctp tsn mapping array.
  10  *
  11  * The SCTP reference implementation is free software;
  12  * you can redistribute it and/or modify it under the terms of
  13  * the GNU General Public License as published by
  14  * the Free Software Foundation; either version 2, or (at your option)
  15  * any later version.
  16  *
  17  * The SCTP reference implementation is distributed in the hope that it
  18  * will be useful, but WITHOUT ANY WARRANTY; without even the implied
  19  *                 ************************
  20  * warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.
  21  * See the GNU General Public License for more details.
  22  *
  23  * You should have received a copy of the GNU General Public License
  24  * along with GNU CC; see the file COPYING.  If not, write to
  25  * the Free Software Foundation, 59 Temple Place - Suite 330,
  26  * Boston, MA 02111-1307, USA.
  27  *
  28  * Please send any bug reports or fixes you make to the
  29  * email address(es):
  30  *    lksctp developers <lksctp-developers@lists.sourceforge.net>
  31  *
  32  * Or submit a bug report through the following website:
  33  *    http://www.sf.net/projects/lksctp
  34  *
  35  * Written or modified by:
  36  *    La Monte H.P. Yarroll <piggy@acm.org>
  37  *    Jon Grimm             <jgrimm@us.ibm.com>
  38  *    Karl Knutson          <karl@athena.chicago.il.us>
  39  *
  40  * Any bugs reported given to us we will try to fix... any fixes shared will
  41  * be incorporated into the next SCTP release.
  42  */
  43
  44 #include <linux/types.h>
  45 #include <net/sctp/sctp.h>
  46 #include <net/sctp/sm.h>
  47
  48 static void sctp_tsnmap_update(struct sctp_tsnmap *map);
  49 static void sctp_tsnmap_find_gap_ack(__u8 *map, __u16 off,
  50                                      __u16 len, __u16 base,
  51                                      int *started, __u16 *start,
  52                                      int *ended, __u16 *end);
  53
  54 /* Create a new sctp_tsnmap.
  55  * Allocate room to store at least 'len' contiguous TSNs.
  56  */
  57 struct sctp_tsnmap *sctp_tsnmap_new(__u16 len, __u32 initial_tsn, int gfp)
  58 {
  59         struct sctp_tsnmap *retval;
  60
  61         retval = kmalloc(sizeof(struct sctp_tsnmap) +
  62                          sctp_tsnmap_storage_size(len), gfp);
  63         if (!retval)
  64                 goto fail;
  65
  66         if (!sctp_tsnmap_init(retval, len, initial_tsn))
  67                 goto fail_map;
  68         retval->malloced = 1;
  69         return retval;
  70
  71 fail_map:
  72         kfree(retval);
  73 fail:
  74         return NULL;
  75 }
  76
  77 /* Initialize a block of memory as a tsnmap.  */
  78 struct sctp_tsnmap *sctp_tsnmap_init(struct sctp_tsnmap *map, __u16 len,
  79                                      __u32 initial_tsn)
  80 {
  81         map->tsn_map = map->raw_map;
  82         map->overflow_map = map->tsn_map + len;
  83         map->len = len;
  84
  85         /* Clear out a TSN ack status.  */
  86         memset(map->tsn_map, 0x00, map->len + map->len);
  87
  88         /* Keep track of TSNs represented by tsn_map.  */
  89         map->base_tsn = initial_tsn;
  90         map->overflow_tsn = initial_tsn + map->len;
  91         map->cumulative_tsn_ack_point = initial_tsn - 1;
  92         map->max_tsn_seen = map->cumulative_tsn_ack_point;
  93         map->malloced = 0;
  94         map->num_dup_tsns = 0;
  95
  96         return map;
  97 }
  98
  99 /* Test the tracking state of this TSN.
 100  * Returns:
 101  *   0 if the TSN has not yet been seen
 102  *  >0 if the TSN has been seen (duplicate)
 103  *  <0 if the TSN is invalid (too large to track)
 104  */
 105 int sctp_tsnmap_check(const struct sctp_tsnmap *map, __u32 tsn)
 106 {
 107         __s32 gap;
 108         int dup;
 109
 110         /* Calculate the index into the mapping arrays.  */
 111         gap = tsn - map->base_tsn;
 112
 113         /* Verify that we can hold this TSN.  */
 114         if (gap >= (/* base */ map->len + /* overflow */ map->len)) {
 115                 dup = -1;
 116                 goto out;
 117         }
 118
 119         /* Honk if we've already seen this TSN.
 120          * We have three cases:
 121          *      1. The TSN is ancient or belongs to a previous tsn_map.
 122          *      2. The TSN is already marked in the tsn_map.
 123          *      3. The TSN is already marked in the tsn_map_overflow.
 124          */
 125         if (gap < 0 ||
 126             (gap < map->len && map->tsn_map[gap]) ||
 127             (gap >= map->len && map->overflow_map[gap - map->len]))
 128                 dup = 1;
 129         else
 130                 dup = 0;
 131
 132 out:
 133         return dup;
 134 }
 135
 136
 137 /* Mark this TSN as seen.  */
 138 void sctp_tsnmap_mark(struct sctp_tsnmap *map, __u32 tsn)
 139 {
 140         __s32 gap;
 141
 142         /* Vacuously mark any TSN which precedes the map base or
 143          * exceeds the end of the map.
 144          */
 145         if (TSN_lt(tsn, map->base_tsn))
 146                 return;
 147         if (!TSN_lt(tsn, map->base_tsn + map->len + map->len))
 148                 return;
 149
 150         /* Bump the max.  */
 151         if (TSN_lt(map->max_tsn_seen, tsn))
 152                 map->max_tsn_seen = tsn;
 153
 154         /* Assert: TSN is in range.  */
 155         gap = tsn - map->base_tsn;
 156
 157         /* Mark the TSN as received.  */
 158         if (gap < map->len)
 159                 map->tsn_map[gap]++;
 160         else
 161                 map->overflow_map[gap - map->len]++;
 162
 163         /* Go fixup any internal TSN mapping variables including
 164          * cumulative_tsn_ack_point.
 165          */
 166         sctp_tsnmap_update(map);
 167 }
 168
 169
 170 /* Dispose of a tsnmap.  */
 171 void sctp_tsnmap_free(struct sctp_tsnmap *map)
 172 {
 173         if (map->malloced)
 174                 kfree(map);
 175 }
 176
 177 /* Initialize a Gap Ack Block iterator from memory being provided.  */
 178 void sctp_tsnmap_iter_init(const struct sctp_tsnmap *map,
 179                            struct sctp_tsnmap_iter *iter)
 180 {
 181         /* Only start looking one past the Cumulative TSN Ack Point.  */
 182         iter->start = map->cumulative_tsn_ack_point + 1;
 183 }
 184
 185 /* Get the next Gap Ack Blocks. Returns 0 if there was not another block
 186  * to get.
 187  */
 188 int sctp_tsnmap_next_gap_ack(const struct sctp_tsnmap *map,
 189         struct sctp_tsnmap_iter *iter, __u16 *start, __u16 *end)
 190 {
 191         int started, ended;
 192         __u16 _start, _end, offset;
 193
 194         /* We haven't found a gap yet.  */
 195         started = ended = 0;
 196
 197         /* If there are no more gap acks possible, get out fast.  */
 198         if (TSN_lte(map->max_tsn_seen, iter->start))
 199                 return 0;
 200
 201         /* Search the first mapping array.  */
 202         if (iter->start - map->base_tsn < map->len) {
 203
 204                 offset = iter->start - map->base_tsn;
 205                 sctp_tsnmap_find_gap_ack(map->tsn_map, offset, map->len, 0,
 206                                          &started, &_start, &ended, &_end);
 207         }
 208
 209         /* Do we need to check the overflow map? */
 210         if (!ended) {
 211                 /* Fix up where we'd like to start searching in the
 212                  * overflow map.
 213                  */
 214                 if (iter->start - map->base_tsn < map->len)
 215                         offset = 0;
 216                 else
 217                         offset = iter->start - map->base_tsn - map->len;
 218
 219                 /* Search the overflow map.  */
 220                 sctp_tsnmap_find_gap_ack(map->overflow_map,
 221                                          offset,
 222                                          map->len,
 223                                          map->len,
 224                                          &started, &_start,
 225                                          &ended, &_end);
 226         }
 227
 228         /* The Gap Ack Block happens to end at the end of the
 229          * overflow map.
 230          */
 231         if (started && !ended) {
 232                 ended++;
 233                 _end = map->len + map->len - 1;
 234         }
 235
 236         /* If we found a Gap Ack Block, return the start and end and
 237          * bump the iterator forward.
 238          */
 239         if (ended) {
 240                 /* Fix up the start and end based on the
 241                  * Cumulative TSN Ack offset into the map.
 242                  */
 243                 int gap = map->cumulative_tsn_ack_point -
 244                         map->base_tsn;
 245
 246                 *start = _start - gap;
 247                 *end = _end - gap;
 248
 249                 /* Move the iterator forward.  */
 250                 iter->start = map->cumulative_tsn_ack_point + *end + 1;
 251         }
 252
 253         return ended;
 254 }
 255
 256 /********************************************************************
 257  * 2nd Level Abstractions
 258  ********************************************************************/
 259
 260 /* This private helper function updates the tsnmap buffers and
 261  * the Cumulative TSN Ack Point.
 262  */
 263 static void sctp_tsnmap_update(struct sctp_tsnmap *map)
 264 {
 265         __u32 ctsn;
 266
 267         ctsn = map->cumulative_tsn_ack_point;
 268         do {
 269                 ctsn++;
 270                 if (ctsn == map->overflow_tsn) {
 271                         /* Now tsn_map must have been all '1's,
 272                          * so we swap the map and check the overflow table
 273                          */
 274                         __u8 *tmp = map->tsn_map;
 275                         memset(tmp, 0, map->len);
 276                         map->tsn_map = map->overflow_map;
 277                         map->overflow_map = tmp;
 278
 279                         /* Update the tsn_map boundaries.  */
 280                         map->base_tsn += map->len;
 281                         map->overflow_tsn += map->len;
 282                 }
 283         } while (map->tsn_map[ctsn - map->base_tsn]);
 284
 285         map->cumulative_tsn_ack_point = ctsn - 1; /* Back up one. */
 286 }
 287
 288 /* How many data chunks  are we missing from our peer?
 289  */
 290 __u16 sctp_tsnmap_pending(struct sctp_tsnmap *map)
 291 {
 292         __u32 cum_tsn = map->cumulative_tsn_ack_point;
 293         __u32 max_tsn = map->max_tsn_seen;
 294         __u32 base_tsn = map->base_tsn;
 295         __u16 pending_data;
 296         __s32 gap, start, end, i;
 297
 298         pending_data = max_tsn - cum_tsn;
 299         gap = max_tsn - base_tsn;
 300
 301         if (gap <= 0 || gap >= (map->len + map->len))
 302                 goto out;
 303
 304         start = ((cum_tsn >= base_tsn) ? (cum_tsn - base_tsn + 1) : 0);
 305         end = ((gap > map->len ) ? map->len : gap + 1);
 306
 307         for (i = start; i < end; i++) {
 308                 if (map->tsn_map[i])
 309                         pending_data--;
 310         }
 311
 312         if (gap >= map->len) {
 313                 start = 0;
 314                 end = gap - map->len + 1;
 315                 for (i = start; i < end; i++) {
 316                         if (map->overflow_map[i])
 317                                 pending_data--;
 318                 }
 319         }
 320
 321 out:
 322         return pending_data;
 323 }
 324
 325 /* This is a private helper for finding Gap Ack Blocks.  It searches a
 326  * single array for the start and end of a Gap Ack Block.
 327  *
 328  * The flags "started" and "ended" tell is if we found the beginning
 329  * or (respectively) the end of a Gap Ack Block.
 330  */
 331 static void sctp_tsnmap_find_gap_ack(__u8 *map, __u16 off,
 332                                      __u16 len, __u16 base,
 333                                      int *started, __u16 *start,
 334                                      int *ended, __u16 *end)
 335 {
 336         int i = off;
 337
 338         /* Look through the entire array, but break out
 339          * early if we have found the end of the Gap Ack Block.
 340          */
 341
 342         /* Also, stop looking past the maximum TSN seen. */
 343
 344         /* Look for the start. */
 345         if (!(*started)) {
 346                 for (; i < len; i++) {
 347                         if (map[i]) {
 348                                 (*started)++;
 349                                 *start = base + i;
 350                                 break;
 351                         }
 352                 }
 353         }
 354
 355         /* Look for the end.  */
 356         if (*started) {
 357                 /* We have found the start, let's find the
 358                  * end.  If we find the end, break out.
 359                  */
 360                 for (; i < len; i++) {
 361                         if (!map[i]) {
 362                                 (*ended)++;
 363                                 *end = base + i - 1;
 364                                 break;
 365                         }
 366                 }
 367         }
 368 }
 369
 370 /* Renege that we have seen a TSN.  */
 371 void sctp_tsnmap_renege(struct sctp_tsnmap *map, __u32 tsn)
 372 {
 373         __s32 gap;
 374
 375         if (TSN_lt(tsn, map->base_tsn))
 376                 return;
 377         if (!TSN_lt(tsn, map->base_tsn + map->len + map->len))
 378                 return;
 379
 380         /* Assert: TSN is in range.  */
 381         gap = tsn - map->base_tsn;
 382
 383         /* Pretend we never saw the TSN.  */
 384         if (gap < map->len)
 385                 map->tsn_map[gap] = 0;
 386         else
 387                 map->overflow_map[gap - map->len] = 0;
 388 }
 389
 390 /* How many gap ack blocks do we have recorded? */
 391 __u16 sctp_tsnmap_num_gabs(struct sctp_tsnmap *map)
 392 {
 393         struct sctp_tsnmap_iter iter;
 394         int gabs = 0;
 395
 396         /* Refresh the gap ack information. */
 397         if (sctp_tsnmap_has_gap(map)) {
 398                 sctp_tsnmap_iter_init(map, &iter);
 399                 while (sctp_tsnmap_next_gap_ack(map, &iter,
 400                                                 &map->gabs[gabs].start,
 401                                                 &map->gabs[gabs].end)) {
 402
 403                         map->gabs[gabs].start = htons(map->gabs[gabs].start);
 404                         map->gabs[gabs].end = htons(map->gabs[gabs].end);
 405                         gabs++;
 406                         if (gabs >= SCTP_MAX_GABS)
 407                                 break;
 408                 }
 409         }
 410         return gabs;
 411 }