1 /* SCTP kernel reference Implementation 2 * (C) Copyright IBM Corp. 2001, 2004 3 * Copyright (c) 1999-2000 Cisco, Inc. 4 * Copyright (c) 1999-2001 Motorola, Inc. 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 * Sridhar Samudrala <sri@us.ibm.com> 40 * 41 * Any bugs reported given to us we will try to fix... any fixes shared will 42 * be incorporated into the next SCTP release. 43 */ 44 45 #include <linux/types.h> 46 #include <net/sctp/sctp.h> 47 #include <net/sctp/sm.h> 48 49 static void sctp_tsnmap_update(struct sctp_tsnmap *map); 50 static void sctp_tsnmap_find_gap_ack(__u8 *map, __u16 off, 51 __u16 len, __u16 base, 52 int *started, __u16 *start, 53 int *ended, __u16 *end); 54 55 /* Initialize a block of memory as a tsnmap. */ 56 struct sctp_tsnmap *sctp_tsnmap_init(struct sctp_tsnmap *map, __u16 len, 57 __u32 initial_tsn) 58 { 59 map->tsn_map = map->raw_map; 60 map->overflow_map = map->tsn_map + len; 61 map->len = len; 62 63 /* Clear out a TSN ack status. */ 64 memset(map->tsn_map, 0x00, map->len + map->len); 65 66 /* Keep track of TSNs represented by tsn_map. */ 67 map->base_tsn = initial_tsn; 68 map->overflow_tsn = initial_tsn + map->len; 69 map->cumulative_tsn_ack_point = initial_tsn - 1; 70 map->max_tsn_seen = map->cumulative_tsn_ack_point; 71 map->malloced = 0; 72 map->num_dup_tsns = 0; 73 74 return map; 75 } 76 77 /* Test the tracking state of this TSN. 78 * Returns: 79 * 0 if the TSN has not yet been seen 80 * >0 if the TSN has been seen (duplicate) 81 * <0 if the TSN is invalid (too large to track) 82 */ 83 int sctp_tsnmap_check(const struct sctp_tsnmap *map, __u32 tsn) 84 { 85 __s32 gap; 86 int dup; 87 88 /* Calculate the index into the mapping arrays. */ 89 gap = tsn - map->base_tsn; 90 91 /* Verify that we can hold this TSN. */ 92 if (gap >= (/* base */ map->len + /* overflow */ map->len)) { 93 dup = -1; 94 goto out; 95 } 96 97 /* Honk if we've already seen this TSN. 98 * We have three cases: 99 * 1. The TSN is ancient or belongs to a previous tsn_map. 100 * 2. The TSN is already marked in the tsn_map. 101 * 3. The TSN is already marked in the tsn_map_overflow. 102 */ 103 if (gap < 0 || 104 (gap < map->len && map->tsn_map[gap]) || 105 (gap >= map->len && map->overflow_map[gap - map->len])) 106 dup = 1; 107 else 108 dup = 0; 109 110 out: 111 return dup; 112 } 113 114 115 /* Mark this TSN as seen. */ 116 void sctp_tsnmap_mark(struct sctp_tsnmap *map, __u32 tsn) 117 { 118 __s32 gap; 119 120 /* Vacuously mark any TSN which precedes the map base or 121 * exceeds the end of the map. 122 */ 123 if (TSN_lt(tsn, map->base_tsn)) 124 return; 125 if (!TSN_lt(tsn, map->base_tsn + map->len + map->len)) 126 return; 127 128 /* Bump the max. */ 129 if (TSN_lt(map->max_tsn_seen, tsn)) 130 map->max_tsn_seen = tsn; 131 132 /* Assert: TSN is in range. */ 133 gap = tsn - map->base_tsn; 134 135 /* Mark the TSN as received. */ 136 if (gap < map->len) 137 map->tsn_map[gap]++; 138 else 139 map->overflow_map[gap - map->len]++; 140 141 /* Go fixup any internal TSN mapping variables including 142 * cumulative_tsn_ack_point. 143 */ 144 sctp_tsnmap_update(map); 145 } 146 147 148 /* Initialize a Gap Ack Block iterator from memory being provided. */ 149 SCTP_STATIC void sctp_tsnmap_iter_init(const struct sctp_tsnmap *map, 150 struct sctp_tsnmap_iter *iter) 151 { 152 /* Only start looking one past the Cumulative TSN Ack Point. */ 153 iter->start = map->cumulative_tsn_ack_point + 1; 154 } 155 156 /* Get the next Gap Ack Blocks. Returns 0 if there was not another block 157 * to get. 158 */ 159 SCTP_STATIC int sctp_tsnmap_next_gap_ack(const struct sctp_tsnmap *map, 160 struct sctp_tsnmap_iter *iter, 161 __u16 *start, __u16 *end) 162 { 163 int started, ended; 164 __u16 start_, end_, offset; 165 166 /* We haven't found a gap yet. */ 167 started = ended = 0; 168 169 /* If there are no more gap acks possible, get out fast. */ 170 if (TSN_lte(map->max_tsn_seen, iter->start)) 171 return 0; 172 173 /* Search the first mapping array. */ 174 if (iter->start - map->base_tsn < map->len) { 175 176 offset = iter->start - map->base_tsn; 177 sctp_tsnmap_find_gap_ack(map->tsn_map, offset, map->len, 0, 178 &started, &start_, &ended, &end_); 179 } 180 181 /* Do we need to check the overflow map? */ 182 if (!ended) { 183 /* Fix up where we'd like to start searching in the 184 * overflow map. 185 */ 186 if (iter->start - map->base_tsn < map->len) 187 offset = 0; 188 else 189 offset = iter->start - map->base_tsn - map->len; 190 191 /* Search the overflow map. */ 192 sctp_tsnmap_find_gap_ack(map->overflow_map, 193 offset, 194 map->len, 195 map->len, 196 &started, &start_, 197 &ended, &end_); 198 } 199 200 /* The Gap Ack Block happens to end at the end of the 201 * overflow map. 202 */ 203 if (started && !ended) { 204 ended++; 205 end_ = map->len + map->len - 1; 206 } 207 208 /* If we found a Gap Ack Block, return the start and end and 209 * bump the iterator forward. 210 */ 211 if (ended) { 212 /* Fix up the start and end based on the 213 * Cumulative TSN Ack offset into the map. 214 */ 215 int gap = map->cumulative_tsn_ack_point - 216 map->base_tsn; 217 218 *start = start_ - gap; 219 *end = end_ - gap; 220 221 /* Move the iterator forward. */ 222 iter->start = map->cumulative_tsn_ack_point + *end + 1; 223 } 224 225 return ended; 226 } 227 228 /* Mark this and any lower TSN as seen. */ 229 void sctp_tsnmap_skip(struct sctp_tsnmap *map, __u32 tsn) 230 { 231 __s32 gap; 232 233 /* Vacuously mark any TSN which precedes the map base or 234 * exceeds the end of the map. 235 */ 236 if (TSN_lt(tsn, map->base_tsn)) 237 return; 238 if (!TSN_lt(tsn, map->base_tsn + map->len + map->len)) 239 return; 240 241 /* Bump the max. */ 242 if (TSN_lt(map->max_tsn_seen, tsn)) 243 map->max_tsn_seen = tsn; 244 245 /* Assert: TSN is in range. */ 246 gap = tsn - map->base_tsn + 1; 247 248 /* Mark the TSNs as received. */ 249 if (gap <= map->len) 250 memset(map->tsn_map, 0x01, gap); 251 else { 252 memset(map->tsn_map, 0x01, map->len); 253 memset(map->overflow_map, 0x01, (gap - map->len)); 254 } 255 256 /* Go fixup any internal TSN mapping variables including 257 * cumulative_tsn_ack_point. 258 */ 259 sctp_tsnmap_update(map); 260 } 261 262 /******************************************************************** 263 * 2nd Level Abstractions 264 ********************************************************************/ 265 266 /* This private helper function updates the tsnmap buffers and 267 * the Cumulative TSN Ack Point. 268 */ 269 static void sctp_tsnmap_update(struct sctp_tsnmap *map) 270 { 271 __u32 ctsn; 272 273 ctsn = map->cumulative_tsn_ack_point; 274 do { 275 ctsn++; 276 if (ctsn == map->overflow_tsn) { 277 /* Now tsn_map must have been all '1's, 278 * so we swap the map and check the overflow table 279 */ 280 __u8 *tmp = map->tsn_map; 281 memset(tmp, 0, map->len); 282 map->tsn_map = map->overflow_map; 283 map->overflow_map = tmp; 284 285 /* Update the tsn_map boundaries. */ 286 map->base_tsn += map->len; 287 map->overflow_tsn += map->len; 288 } 289 } while (map->tsn_map[ctsn - map->base_tsn]); 290 291 map->cumulative_tsn_ack_point = ctsn - 1; /* Back up one. */ 292 } 293 294 /* How many data chunks are we missing from our peer? 295 */ 296 __u16 sctp_tsnmap_pending(struct sctp_tsnmap *map) 297 { 298 __u32 cum_tsn = map->cumulative_tsn_ack_point; 299 __u32 max_tsn = map->max_tsn_seen; 300 __u32 base_tsn = map->base_tsn; 301 __u16 pending_data; 302 __s32 gap, start, end, i; 303 304 pending_data = max_tsn - cum_tsn; 305 gap = max_tsn - base_tsn; 306 307 if (gap <= 0 || gap >= (map->len + map->len)) 308 goto out; 309 310 start = ((cum_tsn >= base_tsn) ? (cum_tsn - base_tsn + 1) : 0); 311 end = ((gap > map->len ) ? map->len : gap + 1); 312 313 for (i = start; i < end; i++) { 314 if (map->tsn_map[i]) 315 pending_data--; 316 } 317 318 if (gap >= map->len) { 319 start = 0; 320 end = gap - map->len + 1; 321 for (i = start; i < end; i++) { 322 if (map->overflow_map[i]) 323 pending_data--; 324 } 325 } 326 327 out: 328 return pending_data; 329 } 330 331 /* This is a private helper for finding Gap Ack Blocks. It searches a 332 * single array for the start and end of a Gap Ack Block. 333 * 334 * The flags "started" and "ended" tell is if we found the beginning 335 * or (respectively) the end of a Gap Ack Block. 336 */ 337 static void sctp_tsnmap_find_gap_ack(__u8 *map, __u16 off, 338 __u16 len, __u16 base, 339 int *started, __u16 *start, 340 int *ended, __u16 *end) 341 { 342 int i = off; 343 344 /* Look through the entire array, but break out 345 * early if we have found the end of the Gap Ack Block. 346 */ 347 348 /* Also, stop looking past the maximum TSN seen. */ 349 350 /* Look for the start. */ 351 if (!(*started)) { 352 for (; i < len; i++) { 353 if (map[i]) { 354 (*started)++; 355 *start = base + i; 356 break; 357 } 358 } 359 } 360 361 /* Look for the end. */ 362 if (*started) { 363 /* We have found the start, let's find the 364 * end. If we find the end, break out. 365 */ 366 for (; i < len; i++) { 367 if (!map[i]) { 368 (*ended)++; 369 *end = base + i - 1; 370 break; 371 } 372 } 373 } 374 } 375 376 /* Renege that we have seen a TSN. */ 377 void sctp_tsnmap_renege(struct sctp_tsnmap *map, __u32 tsn) 378 { 379 __s32 gap; 380 381 if (TSN_lt(tsn, map->base_tsn)) 382 return; 383 if (!TSN_lt(tsn, map->base_tsn + map->len + map->len)) 384 return; 385 386 /* Assert: TSN is in range. */ 387 gap = tsn - map->base_tsn; 388 389 /* Pretend we never saw the TSN. */ 390 if (gap < map->len) 391 map->tsn_map[gap] = 0; 392 else 393 map->overflow_map[gap - map->len] = 0; 394 } 395 396 /* How many gap ack blocks do we have recorded? */ 397 __u16 sctp_tsnmap_num_gabs(struct sctp_tsnmap *map) 398 { 399 struct sctp_tsnmap_iter iter; 400 int gabs = 0; 401 402 /* Refresh the gap ack information. */ 403 if (sctp_tsnmap_has_gap(map)) { 404 __u16 start, end; 405 sctp_tsnmap_iter_init(map, &iter); 406 while (sctp_tsnmap_next_gap_ack(map, &iter, 407 &start, 408 &end)) { 409 410 map->gabs[gabs].start = htons(start); 411 map->gabs[gabs].end = htons(end); 412 gabs++; 413 if (gabs >= SCTP_MAX_GABS) 414 break; 415 } 416 } 417 return gabs; 418 } 419