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/slab.h> 46 #include <linux/types.h> 47 #include <linux/bitmap.h> 48 #include <net/sctp/sctp.h> 49 #include <net/sctp/sm.h> 50 51 static void sctp_tsnmap_update(struct sctp_tsnmap *map); 52 static void sctp_tsnmap_find_gap_ack(unsigned long *map, __u16 off, 53 __u16 len, __u16 *start, __u16 *end); 54 static int sctp_tsnmap_grow(struct sctp_tsnmap *map, u16 gap); 55 56 /* Initialize a block of memory as a tsnmap. */ 57 struct sctp_tsnmap *sctp_tsnmap_init(struct sctp_tsnmap *map, __u16 len, 58 __u32 initial_tsn, gfp_t gfp) 59 { 60 if (!map->tsn_map) { 61 map->tsn_map = kzalloc(len>>3, gfp); 62 if (map->tsn_map == NULL) 63 return NULL; 64 65 map->len = len; 66 } else { 67 bitmap_zero(map->tsn_map, map->len); 68 } 69 70 /* Keep track of TSNs represented by tsn_map. */ 71 map->base_tsn = initial_tsn; 72 map->cumulative_tsn_ack_point = initial_tsn - 1; 73 map->max_tsn_seen = map->cumulative_tsn_ack_point; 74 map->num_dup_tsns = 0; 75 76 return map; 77 } 78 79 void sctp_tsnmap_free(struct sctp_tsnmap *map) 80 { 81 map->len = 0; 82 kfree(map->tsn_map); 83 } 84 85 /* Test the tracking state of this TSN. 86 * Returns: 87 * 0 if the TSN has not yet been seen 88 * >0 if the TSN has been seen (duplicate) 89 * <0 if the TSN is invalid (too large to track) 90 */ 91 int sctp_tsnmap_check(const struct sctp_tsnmap *map, __u32 tsn) 92 { 93 u32 gap; 94 95 /* Check to see if this is an old TSN */ 96 if (TSN_lte(tsn, map->cumulative_tsn_ack_point)) 97 return 1; 98 99 /* Verify that we can hold this TSN and that it will not 100 * overlfow our map 101 */ 102 if (!TSN_lt(tsn, map->base_tsn + SCTP_TSN_MAP_SIZE)) 103 return -1; 104 105 /* Calculate the index into the mapping arrays. */ 106 gap = tsn - map->base_tsn; 107 108 /* Check to see if TSN has already been recorded. */ 109 if (gap < map->len && test_bit(gap, map->tsn_map)) 110 return 1; 111 else 112 return 0; 113 } 114 115 116 /* Mark this TSN as seen. */ 117 int sctp_tsnmap_mark(struct sctp_tsnmap *map, __u32 tsn) 118 { 119 u16 gap; 120 121 if (TSN_lt(tsn, map->base_tsn)) 122 return 0; 123 124 gap = tsn - map->base_tsn; 125 126 if (gap >= map->len && !sctp_tsnmap_grow(map, gap)) 127 return -ENOMEM; 128 129 if (!sctp_tsnmap_has_gap(map) && gap == 0) { 130 /* In this case the map has no gaps and the tsn we are 131 * recording is the next expected tsn. We don't touch 132 * the map but simply bump the values. 133 */ 134 map->max_tsn_seen++; 135 map->cumulative_tsn_ack_point++; 136 map->base_tsn++; 137 } else { 138 /* Either we already have a gap, or about to record a gap, so 139 * have work to do. 140 * 141 * Bump the max. 142 */ 143 if (TSN_lt(map->max_tsn_seen, tsn)) 144 map->max_tsn_seen = tsn; 145 146 /* Mark the TSN as received. */ 147 set_bit(gap, map->tsn_map); 148 149 /* Go fixup any internal TSN mapping variables including 150 * cumulative_tsn_ack_point. 151 */ 152 sctp_tsnmap_update(map); 153 } 154 155 return 0; 156 } 157 158 159 /* Initialize a Gap Ack Block iterator from memory being provided. */ 160 SCTP_STATIC void sctp_tsnmap_iter_init(const struct sctp_tsnmap *map, 161 struct sctp_tsnmap_iter *iter) 162 { 163 /* Only start looking one past the Cumulative TSN Ack Point. */ 164 iter->start = map->cumulative_tsn_ack_point + 1; 165 } 166 167 /* Get the next Gap Ack Blocks. Returns 0 if there was not another block 168 * to get. 169 */ 170 SCTP_STATIC int sctp_tsnmap_next_gap_ack(const struct sctp_tsnmap *map, 171 struct sctp_tsnmap_iter *iter, 172 __u16 *start, __u16 *end) 173 { 174 int ended = 0; 175 __u16 start_ = 0, end_ = 0, offset; 176 177 /* If there are no more gap acks possible, get out fast. */ 178 if (TSN_lte(map->max_tsn_seen, iter->start)) 179 return 0; 180 181 offset = iter->start - map->base_tsn; 182 sctp_tsnmap_find_gap_ack(map->tsn_map, offset, map->len, 183 &start_, &end_); 184 185 /* The Gap Ack Block happens to end at the end of the map. */ 186 if (start_ && !end_) 187 end_ = map->len - 1; 188 189 /* If we found a Gap Ack Block, return the start and end and 190 * bump the iterator forward. 191 */ 192 if (end_) { 193 /* Fix up the start and end based on the 194 * Cumulative TSN Ack which is always 1 behind base. 195 */ 196 *start = start_ + 1; 197 *end = end_ + 1; 198 199 /* Move the iterator forward. */ 200 iter->start = map->cumulative_tsn_ack_point + *end + 1; 201 ended = 1; 202 } 203 204 return ended; 205 } 206 207 /* Mark this and any lower TSN as seen. */ 208 void sctp_tsnmap_skip(struct sctp_tsnmap *map, __u32 tsn) 209 { 210 u32 gap; 211 212 if (TSN_lt(tsn, map->base_tsn)) 213 return; 214 if (!TSN_lt(tsn, map->base_tsn + SCTP_TSN_MAP_SIZE)) 215 return; 216 217 /* Bump the max. */ 218 if (TSN_lt(map->max_tsn_seen, tsn)) 219 map->max_tsn_seen = tsn; 220 221 gap = tsn - map->base_tsn + 1; 222 223 map->base_tsn += gap; 224 map->cumulative_tsn_ack_point += gap; 225 if (gap >= map->len) { 226 /* If our gap is larger then the map size, just 227 * zero out the map. 228 */ 229 bitmap_zero(map->tsn_map, map->len); 230 } else { 231 /* If the gap is smaller than the map size, 232 * shift the map by 'gap' bits and update further. 233 */ 234 bitmap_shift_right(map->tsn_map, map->tsn_map, gap, map->len); 235 sctp_tsnmap_update(map); 236 } 237 } 238 239 /******************************************************************** 240 * 2nd Level Abstractions 241 ********************************************************************/ 242 243 /* This private helper function updates the tsnmap buffers and 244 * the Cumulative TSN Ack Point. 245 */ 246 static void sctp_tsnmap_update(struct sctp_tsnmap *map) 247 { 248 u16 len; 249 unsigned long zero_bit; 250 251 252 len = map->max_tsn_seen - map->cumulative_tsn_ack_point; 253 zero_bit = find_first_zero_bit(map->tsn_map, len); 254 if (!zero_bit) 255 return; /* The first 0-bit is bit 0. nothing to do */ 256 257 map->base_tsn += zero_bit; 258 map->cumulative_tsn_ack_point += zero_bit; 259 260 bitmap_shift_right(map->tsn_map, map->tsn_map, zero_bit, map->len); 261 } 262 263 /* How many data chunks are we missing from our peer? 264 */ 265 __u16 sctp_tsnmap_pending(struct sctp_tsnmap *map) 266 { 267 __u32 cum_tsn = map->cumulative_tsn_ack_point; 268 __u32 max_tsn = map->max_tsn_seen; 269 __u32 base_tsn = map->base_tsn; 270 __u16 pending_data; 271 u32 gap, i; 272 273 pending_data = max_tsn - cum_tsn; 274 gap = max_tsn - base_tsn; 275 276 if (gap == 0 || gap >= map->len) 277 goto out; 278 279 for (i = 0; i < gap+1; i++) { 280 if (test_bit(i, map->tsn_map)) 281 pending_data--; 282 } 283 284 out: 285 return pending_data; 286 } 287 288 /* This is a private helper for finding Gap Ack Blocks. It searches a 289 * single array for the start and end of a Gap Ack Block. 290 * 291 * The flags "started" and "ended" tell is if we found the beginning 292 * or (respectively) the end of a Gap Ack Block. 293 */ 294 static void sctp_tsnmap_find_gap_ack(unsigned long *map, __u16 off, 295 __u16 len, __u16 *start, __u16 *end) 296 { 297 int i = off; 298 299 /* Look through the entire array, but break out 300 * early if we have found the end of the Gap Ack Block. 301 */ 302 303 /* Also, stop looking past the maximum TSN seen. */ 304 305 /* Look for the start. */ 306 i = find_next_bit(map, len, off); 307 if (i < len) 308 *start = i; 309 310 /* Look for the end. */ 311 if (*start) { 312 /* We have found the start, let's find the 313 * end. If we find the end, break out. 314 */ 315 i = find_next_zero_bit(map, len, i); 316 if (i < len) 317 *end = i - 1; 318 } 319 } 320 321 /* Renege that we have seen a TSN. */ 322 void sctp_tsnmap_renege(struct sctp_tsnmap *map, __u32 tsn) 323 { 324 u32 gap; 325 326 if (TSN_lt(tsn, map->base_tsn)) 327 return; 328 /* Assert: TSN is in range. */ 329 if (!TSN_lt(tsn, map->base_tsn + map->len)) 330 return; 331 332 gap = tsn - map->base_tsn; 333 334 /* Pretend we never saw the TSN. */ 335 clear_bit(gap, map->tsn_map); 336 } 337 338 /* How many gap ack blocks do we have recorded? */ 339 __u16 sctp_tsnmap_num_gabs(struct sctp_tsnmap *map, 340 struct sctp_gap_ack_block *gabs) 341 { 342 struct sctp_tsnmap_iter iter; 343 int ngaps = 0; 344 345 /* Refresh the gap ack information. */ 346 if (sctp_tsnmap_has_gap(map)) { 347 __u16 start, end; 348 sctp_tsnmap_iter_init(map, &iter); 349 while (sctp_tsnmap_next_gap_ack(map, &iter, 350 &start, 351 &end)) { 352 353 gabs[ngaps].start = htons(start); 354 gabs[ngaps].end = htons(end); 355 ngaps++; 356 if (ngaps >= SCTP_MAX_GABS) 357 break; 358 } 359 } 360 return ngaps; 361 } 362 363 static int sctp_tsnmap_grow(struct sctp_tsnmap *map, u16 gap) 364 { 365 unsigned long *new; 366 unsigned long inc; 367 u16 len; 368 369 if (gap >= SCTP_TSN_MAP_SIZE) 370 return 0; 371 372 inc = ALIGN((gap - map->len),BITS_PER_LONG) + SCTP_TSN_MAP_INCREMENT; 373 len = min_t(u16, map->len + inc, SCTP_TSN_MAP_SIZE); 374 375 new = kzalloc(len>>3, GFP_ATOMIC); 376 if (!new) 377 return 0; 378 379 bitmap_copy(new, map->tsn_map, map->max_tsn_seen - map->base_tsn); 380 kfree(map->tsn_map); 381 map->tsn_map = new; 382 map->len = len; 383 384 return 1; 385 } 386