1 /* SCTP kernel 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 implementation 8 * 9 * These functions manipulate sctp tsn mapping array. 10 * 11 * This SCTP 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 * This SCTP 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 <linux/bitmap.h> 47 #include <net/sctp/sctp.h> 48 #include <net/sctp/sm.h> 49 50 static void sctp_tsnmap_update(struct sctp_tsnmap *map); 51 static void sctp_tsnmap_find_gap_ack(unsigned long *map, __u16 off, 52 __u16 len, __u16 *start, __u16 *end); 53 static int sctp_tsnmap_grow(struct sctp_tsnmap *map, u16 gap); 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, gfp_t gfp) 58 { 59 if (!map->tsn_map) { 60 map->tsn_map = kzalloc(len>>3, gfp); 61 if (map->tsn_map == NULL) 62 return NULL; 63 64 map->len = len; 65 } else { 66 bitmap_zero(map->tsn_map, map->len); 67 } 68 69 /* Keep track of TSNs represented by tsn_map. */ 70 map->base_tsn = initial_tsn; 71 map->cumulative_tsn_ack_point = initial_tsn - 1; 72 map->max_tsn_seen = map->cumulative_tsn_ack_point; 73 map->num_dup_tsns = 0; 74 75 return map; 76 } 77 78 void sctp_tsnmap_free(struct sctp_tsnmap *map) 79 { 80 map->len = 0; 81 kfree(map->tsn_map); 82 } 83 84 /* Test the tracking state of this TSN. 85 * Returns: 86 * 0 if the TSN has not yet been seen 87 * >0 if the TSN has been seen (duplicate) 88 * <0 if the TSN is invalid (too large to track) 89 */ 90 int sctp_tsnmap_check(const struct sctp_tsnmap *map, __u32 tsn) 91 { 92 u32 gap; 93 94 /* Check to see if this is an old TSN */ 95 if (TSN_lte(tsn, map->cumulative_tsn_ack_point)) 96 return 1; 97 98 /* Verify that we can hold this TSN and that it will not 99 * overlfow our map 100 */ 101 if (!TSN_lt(tsn, map->base_tsn + SCTP_TSN_MAP_SIZE)) 102 return -1; 103 104 /* Calculate the index into the mapping arrays. */ 105 gap = tsn - map->base_tsn; 106 107 /* Check to see if TSN has already been recorded. */ 108 if (gap < map->len && test_bit(gap, map->tsn_map)) 109 return 1; 110 else 111 return 0; 112 } 113 114 115 /* Mark this TSN as seen. */ 116 int sctp_tsnmap_mark(struct sctp_tsnmap *map, __u32 tsn) 117 { 118 u16 gap; 119 120 if (TSN_lt(tsn, map->base_tsn)) 121 return 0; 122 123 gap = tsn - map->base_tsn; 124 125 if (gap >= map->len && !sctp_tsnmap_grow(map, gap)) 126 return -ENOMEM; 127 128 if (!sctp_tsnmap_has_gap(map) && gap == 0) { 129 /* In this case the map has no gaps and the tsn we are 130 * recording is the next expected tsn. We don't touch 131 * the map but simply bump the values. 132 */ 133 map->max_tsn_seen++; 134 map->cumulative_tsn_ack_point++; 135 map->base_tsn++; 136 } else { 137 /* Either we already have a gap, or about to record a gap, so 138 * have work to do. 139 * 140 * Bump the max. 141 */ 142 if (TSN_lt(map->max_tsn_seen, tsn)) 143 map->max_tsn_seen = tsn; 144 145 /* Mark the TSN as received. */ 146 set_bit(gap, map->tsn_map); 147 148 /* Go fixup any internal TSN mapping variables including 149 * cumulative_tsn_ack_point. 150 */ 151 sctp_tsnmap_update(map); 152 } 153 154 return 0; 155 } 156 157 158 /* Initialize a Gap Ack Block iterator from memory being provided. */ 159 SCTP_STATIC void sctp_tsnmap_iter_init(const struct sctp_tsnmap *map, 160 struct sctp_tsnmap_iter *iter) 161 { 162 /* Only start looking one past the Cumulative TSN Ack Point. */ 163 iter->start = map->cumulative_tsn_ack_point + 1; 164 } 165 166 /* Get the next Gap Ack Blocks. Returns 0 if there was not another block 167 * to get. 168 */ 169 SCTP_STATIC int sctp_tsnmap_next_gap_ack(const struct sctp_tsnmap *map, 170 struct sctp_tsnmap_iter *iter, 171 __u16 *start, __u16 *end) 172 { 173 int ended = 0; 174 __u16 start_ = 0, end_ = 0, offset; 175 176 /* If there are no more gap acks possible, get out fast. */ 177 if (TSN_lte(map->max_tsn_seen, iter->start)) 178 return 0; 179 180 offset = iter->start - map->base_tsn; 181 sctp_tsnmap_find_gap_ack(map->tsn_map, offset, map->len, 182 &start_, &end_); 183 184 /* The Gap Ack Block happens to end at the end of the map. */ 185 if (start_ && !end_) 186 end_ = map->len - 1; 187 188 /* If we found a Gap Ack Block, return the start and end and 189 * bump the iterator forward. 190 */ 191 if (end_) { 192 /* Fix up the start and end based on the 193 * Cumulative TSN Ack which is always 1 behind base. 194 */ 195 *start = start_ + 1; 196 *end = end_ + 1; 197 198 /* Move the iterator forward. */ 199 iter->start = map->cumulative_tsn_ack_point + *end + 1; 200 ended = 1; 201 } 202 203 return ended; 204 } 205 206 /* Mark this and any lower TSN as seen. */ 207 void sctp_tsnmap_skip(struct sctp_tsnmap *map, __u32 tsn) 208 { 209 u32 gap; 210 211 if (TSN_lt(tsn, map->base_tsn)) 212 return; 213 if (!TSN_lt(tsn, map->base_tsn + SCTP_TSN_MAP_SIZE)) 214 return; 215 216 /* Bump the max. */ 217 if (TSN_lt(map->max_tsn_seen, tsn)) 218 map->max_tsn_seen = tsn; 219 220 gap = tsn - map->base_tsn + 1; 221 222 map->base_tsn += gap; 223 map->cumulative_tsn_ack_point += gap; 224 if (gap >= map->len) { 225 /* If our gap is larger then the map size, just 226 * zero out the map. 227 */ 228 bitmap_zero(map->tsn_map, map->len); 229 } else { 230 /* If the gap is smaller than the map size, 231 * shift the map by 'gap' bits and update further. 232 */ 233 bitmap_shift_right(map->tsn_map, map->tsn_map, gap, map->len); 234 sctp_tsnmap_update(map); 235 } 236 } 237 238 /******************************************************************** 239 * 2nd Level Abstractions 240 ********************************************************************/ 241 242 /* This private helper function updates the tsnmap buffers and 243 * the Cumulative TSN Ack Point. 244 */ 245 static void sctp_tsnmap_update(struct sctp_tsnmap *map) 246 { 247 u16 len; 248 unsigned long zero_bit; 249 250 251 len = map->max_tsn_seen - map->cumulative_tsn_ack_point; 252 zero_bit = find_first_zero_bit(map->tsn_map, len); 253 if (!zero_bit) 254 return; /* The first 0-bit is bit 0. nothing to do */ 255 256 map->base_tsn += zero_bit; 257 map->cumulative_tsn_ack_point += zero_bit; 258 259 bitmap_shift_right(map->tsn_map, map->tsn_map, zero_bit, map->len); 260 } 261 262 /* How many data chunks are we missing from our peer? 263 */ 264 __u16 sctp_tsnmap_pending(struct sctp_tsnmap *map) 265 { 266 __u32 cum_tsn = map->cumulative_tsn_ack_point; 267 __u32 max_tsn = map->max_tsn_seen; 268 __u32 base_tsn = map->base_tsn; 269 __u16 pending_data; 270 u32 gap, i; 271 272 pending_data = max_tsn - cum_tsn; 273 gap = max_tsn - base_tsn; 274 275 if (gap == 0 || gap >= map->len) 276 goto out; 277 278 for (i = 0; i < gap+1; i++) { 279 if (test_bit(i, map->tsn_map)) 280 pending_data--; 281 } 282 283 out: 284 return pending_data; 285 } 286 287 /* This is a private helper for finding Gap Ack Blocks. It searches a 288 * single array for the start and end of a Gap Ack Block. 289 * 290 * The flags "started" and "ended" tell is if we found the beginning 291 * or (respectively) the end of a Gap Ack Block. 292 */ 293 static void sctp_tsnmap_find_gap_ack(unsigned long *map, __u16 off, 294 __u16 len, __u16 *start, __u16 *end) 295 { 296 int i = off; 297 298 /* Look through the entire array, but break out 299 * early if we have found the end of the Gap Ack Block. 300 */ 301 302 /* Also, stop looking past the maximum TSN seen. */ 303 304 /* Look for the start. */ 305 i = find_next_bit(map, len, off); 306 if (i < len) 307 *start = i; 308 309 /* Look for the end. */ 310 if (*start) { 311 /* We have found the start, let's find the 312 * end. If we find the end, break out. 313 */ 314 i = find_next_zero_bit(map, len, i); 315 if (i < len) 316 *end = i - 1; 317 } 318 } 319 320 /* Renege that we have seen a TSN. */ 321 void sctp_tsnmap_renege(struct sctp_tsnmap *map, __u32 tsn) 322 { 323 u32 gap; 324 325 if (TSN_lt(tsn, map->base_tsn)) 326 return; 327 /* Assert: TSN is in range. */ 328 if (!TSN_lt(tsn, map->base_tsn + map->len)) 329 return; 330 331 gap = tsn - map->base_tsn; 332 333 /* Pretend we never saw the TSN. */ 334 clear_bit(gap, map->tsn_map); 335 } 336 337 /* How many gap ack blocks do we have recorded? */ 338 __u16 sctp_tsnmap_num_gabs(struct sctp_tsnmap *map, 339 struct sctp_gap_ack_block *gabs) 340 { 341 struct sctp_tsnmap_iter iter; 342 int ngaps = 0; 343 344 /* Refresh the gap ack information. */ 345 if (sctp_tsnmap_has_gap(map)) { 346 __u16 start, end; 347 sctp_tsnmap_iter_init(map, &iter); 348 while (sctp_tsnmap_next_gap_ack(map, &iter, 349 &start, 350 &end)) { 351 352 gabs[ngaps].start = htons(start); 353 gabs[ngaps].end = htons(end); 354 ngaps++; 355 if (ngaps >= SCTP_MAX_GABS) 356 break; 357 } 358 } 359 return ngaps; 360 } 361 362 static int sctp_tsnmap_grow(struct sctp_tsnmap *map, u16 gap) 363 { 364 unsigned long *new; 365 unsigned long inc; 366 u16 len; 367 368 if (gap >= SCTP_TSN_MAP_SIZE) 369 return 0; 370 371 inc = ALIGN((gap - map->len),BITS_PER_LONG) + SCTP_TSN_MAP_INCREMENT; 372 len = min_t(u16, map->len + inc, SCTP_TSN_MAP_SIZE); 373 374 new = kzalloc(len>>3, GFP_ATOMIC); 375 if (!new) 376 return 0; 377 378 bitmap_copy(new, map->tsn_map, map->max_tsn_seen - map->base_tsn); 379 kfree(map->tsn_map); 380 map->tsn_map = new; 381 map->len = len; 382 383 return 1; 384 } 385