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Vlad Yasevich60c778b2008-01-11 09:57:09 -05001/* SCTP kernel implementation
Linus Torvalds1da177e2005-04-16 15:20:36 -07002 * (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 *
Vlad Yasevich60c778b2008-01-11 09:57:09 -05007 * This file is part of the SCTP kernel implementation
Linus Torvalds1da177e2005-04-16 15:20:36 -07008 *
9 * These functions manipulate sctp tsn mapping array.
10 *
Vlad Yasevich60c778b2008-01-11 09:57:09 -050011 * This SCTP implementation is free software;
Linus Torvalds1da177e2005-04-16 15:20:36 -070012 * 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 *
Vlad Yasevich60c778b2008-01-11 09:57:09 -050017 * This SCTP implementation is distributed in the hope that it
Linus Torvalds1da177e2005-04-16 15:20:36 -070018 * 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>
Vlad Yasevich8e1ee182008-10-08 14:18:39 -070046#include <linux/bitmap.h>
Linus Torvalds1da177e2005-04-16 15:20:36 -070047#include <net/sctp/sctp.h>
48#include <net/sctp/sm.h>
49
50static void sctp_tsnmap_update(struct sctp_tsnmap *map);
Vlad Yasevich8e1ee182008-10-08 14:18:39 -070051static void sctp_tsnmap_find_gap_ack(unsigned long *map, __u16 off,
52 __u16 len, __u16 *start, __u16 *end);
53static int sctp_tsnmap_grow(struct sctp_tsnmap *map, u16 gap);
Linus Torvalds1da177e2005-04-16 15:20:36 -070054
55/* Initialize a block of memory as a tsnmap. */
56struct sctp_tsnmap *sctp_tsnmap_init(struct sctp_tsnmap *map, __u16 len,
Vlad Yasevich8e1ee182008-10-08 14:18:39 -070057 __u32 initial_tsn, gfp_t gfp)
Linus Torvalds1da177e2005-04-16 15:20:36 -070058{
Vlad Yasevich8e1ee182008-10-08 14:18:39 -070059 if (!map->tsn_map) {
60 map->tsn_map = kzalloc(len>>3, gfp);
61 if (map->tsn_map == NULL)
62 return NULL;
Linus Torvalds1da177e2005-04-16 15:20:36 -070063
Vlad Yasevich8e1ee182008-10-08 14:18:39 -070064 map->len = len;
65 } else {
66 bitmap_zero(map->tsn_map, map->len);
67 }
Linus Torvalds1da177e2005-04-16 15:20:36 -070068
69 /* Keep track of TSNs represented by tsn_map. */
70 map->base_tsn = initial_tsn;
Linus Torvalds1da177e2005-04-16 15:20:36 -070071 map->cumulative_tsn_ack_point = initial_tsn - 1;
72 map->max_tsn_seen = map->cumulative_tsn_ack_point;
Linus Torvalds1da177e2005-04-16 15:20:36 -070073 map->num_dup_tsns = 0;
74
75 return map;
76}
77
Vlad Yasevich8e1ee182008-10-08 14:18:39 -070078void sctp_tsnmap_free(struct sctp_tsnmap *map)
79{
80 map->len = 0;
81 kfree(map->tsn_map);
82}
83
Linus Torvalds1da177e2005-04-16 15:20:36 -070084/* 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 */
90int sctp_tsnmap_check(const struct sctp_tsnmap *map, __u32 tsn)
91{
Vlad Yasevich8e1ee182008-10-08 14:18:39 -070092 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;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700103
104 /* Calculate the index into the mapping arrays. */
105 gap = tsn - map->base_tsn;
106
Vlad Yasevich8e1ee182008-10-08 14:18:39 -0700107 /* Check to see if TSN has already been recorded. */
108 if (gap < map->len && test_bit(gap, map->tsn_map))
109 return 1;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700110 else
Vlad Yasevich8e1ee182008-10-08 14:18:39 -0700111 return 0;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700112}
113
114
115/* Mark this TSN as seen. */
Vlad Yasevich8e1ee182008-10-08 14:18:39 -0700116int sctp_tsnmap_mark(struct sctp_tsnmap *map, __u32 tsn)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700117{
Vlad Yasevich8e1ee182008-10-08 14:18:39 -0700118 u16 gap;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700119
Linus Torvalds1da177e2005-04-16 15:20:36 -0700120 if (TSN_lt(tsn, map->base_tsn))
Vlad Yasevich8e1ee182008-10-08 14:18:39 -0700121 return 0;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700122
Linus Torvalds1da177e2005-04-16 15:20:36 -0700123 gap = tsn - map->base_tsn;
124
Vlad Yasevich8e1ee182008-10-08 14:18:39 -0700125 if (gap >= map->len && !sctp_tsnmap_grow(map, gap))
126 return -ENOMEM;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700127
Vlad Yasevich8e1ee182008-10-08 14:18:39 -0700128 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;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700155}
156
157
158/* Initialize a Gap Ack Block iterator from memory being provided. */
159SCTP_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 */
169SCTP_STATIC int sctp_tsnmap_next_gap_ack(const struct sctp_tsnmap *map,
170 struct sctp_tsnmap_iter *iter,
171 __u16 *start, __u16 *end)
172{
Vlad Yasevich8e1ee182008-10-08 14:18:39 -0700173 int ended = 0;
174 __u16 start_ = 0, end_ = 0, offset;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700175
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
Vlad Yasevich8e1ee182008-10-08 14:18:39 -0700180 offset = iter->start - map->base_tsn;
181 sctp_tsnmap_find_gap_ack(map->tsn_map, offset, map->len,
182 &start_, &end_);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700183
Vlad Yasevich8e1ee182008-10-08 14:18:39 -0700184 /* The Gap Ack Block happens to end at the end of the map. */
185 if (start_ && !end_)
186 end_ = map->len - 1;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700187
188 /* If we found a Gap Ack Block, return the start and end and
189 * bump the iterator forward.
190 */
Vlad Yasevich8e1ee182008-10-08 14:18:39 -0700191 if (end_) {
Linus Torvalds1da177e2005-04-16 15:20:36 -0700192 /* Fix up the start and end based on the
Vlad Yasevich8e1ee182008-10-08 14:18:39 -0700193 * Cumulative TSN Ack which is always 1 behind base.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700194 */
Vlad Yasevich8e1ee182008-10-08 14:18:39 -0700195 *start = start_ + 1;
196 *end = end_ + 1;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700197
198 /* Move the iterator forward. */
199 iter->start = map->cumulative_tsn_ack_point + *end + 1;
Vlad Yasevich8e1ee182008-10-08 14:18:39 -0700200 ended = 1;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700201 }
202
203 return ended;
204}
205
206/* Mark this and any lower TSN as seen. */
207void sctp_tsnmap_skip(struct sctp_tsnmap *map, __u32 tsn)
208{
Vlad Yasevich8e1ee182008-10-08 14:18:39 -0700209 u32 gap;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700210
Linus Torvalds1da177e2005-04-16 15:20:36 -0700211 if (TSN_lt(tsn, map->base_tsn))
212 return;
Vlad Yasevich8e1ee182008-10-08 14:18:39 -0700213 if (!TSN_lt(tsn, map->base_tsn + SCTP_TSN_MAP_SIZE))
Linus Torvalds1da177e2005-04-16 15:20:36 -0700214 return;
215
216 /* Bump the max. */
217 if (TSN_lt(map->max_tsn_seen, tsn))
218 map->max_tsn_seen = tsn;
219
Linus Torvalds1da177e2005-04-16 15:20:36 -0700220 gap = tsn - map->base_tsn + 1;
221
Vlad Yasevich8e1ee182008-10-08 14:18:39 -0700222 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 then 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);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700235 }
Linus Torvalds1da177e2005-04-16 15:20:36 -0700236}
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 */
245static void sctp_tsnmap_update(struct sctp_tsnmap *map)
246{
Vlad Yasevich8e1ee182008-10-08 14:18:39 -0700247 u16 len;
248 unsigned long zero_bit;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700249
Linus Torvalds1da177e2005-04-16 15:20:36 -0700250
Vlad Yasevich8e1ee182008-10-08 14:18:39 -0700251 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 */
Linus Torvalds1da177e2005-04-16 15:20:36 -0700255
Vlad Yasevich8e1ee182008-10-08 14:18:39 -0700256 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);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700260}
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;
Vlad Yasevich8e1ee182008-10-08 14:18:39 -0700270 u32 gap, i;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700271
272 pending_data = max_tsn - cum_tsn;
273 gap = max_tsn - base_tsn;
274
Vlad Yasevich8e1ee182008-10-08 14:18:39 -0700275 if (gap == 0 || gap >= map->len)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700276 goto out;
277
Vlad Yasevich8e1ee182008-10-08 14:18:39 -0700278 for (i = 0; i < gap+1; i++) {
279 if (test_bit(i, map->tsn_map))
Linus Torvalds1da177e2005-04-16 15:20:36 -0700280 pending_data--;
281 }
282
Linus Torvalds1da177e2005-04-16 15:20:36 -0700283out:
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 */
Vlad Yasevich8e1ee182008-10-08 14:18:39 -0700293static void sctp_tsnmap_find_gap_ack(unsigned long *map, __u16 off,
294 __u16 len, __u16 *start, __u16 *end)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700295{
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. */
Vlad Yasevich8e1ee182008-10-08 14:18:39 -0700305 i = find_next_bit(map, len, off);
306 if (i < len)
307 *start = i;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700308
309 /* Look for the end. */
Vlad Yasevich8e1ee182008-10-08 14:18:39 -0700310 if (*start) {
Linus Torvalds1da177e2005-04-16 15:20:36 -0700311 /* We have found the start, let's find the
312 * end. If we find the end, break out.
313 */
Vlad Yasevich8e1ee182008-10-08 14:18:39 -0700314 i = find_next_zero_bit(map, len, i);
315 if (i < len)
316 *end = i - 1;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700317 }
318}
319
320/* Renege that we have seen a TSN. */
321void sctp_tsnmap_renege(struct sctp_tsnmap *map, __u32 tsn)
322{
Vlad Yasevich8e1ee182008-10-08 14:18:39 -0700323 u32 gap;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700324
325 if (TSN_lt(tsn, map->base_tsn))
326 return;
Vlad Yasevich8e1ee182008-10-08 14:18:39 -0700327 /* Assert: TSN is in range. */
328 if (!TSN_lt(tsn, map->base_tsn + map->len))
Linus Torvalds1da177e2005-04-16 15:20:36 -0700329 return;
330
Linus Torvalds1da177e2005-04-16 15:20:36 -0700331 gap = tsn - map->base_tsn;
332
333 /* Pretend we never saw the TSN. */
Vlad Yasevich8e1ee182008-10-08 14:18:39 -0700334 clear_bit(gap, map->tsn_map);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700335}
336
337/* How many gap ack blocks do we have recorded? */
338__u16 sctp_tsnmap_num_gabs(struct sctp_tsnmap *map)
339{
340 struct sctp_tsnmap_iter iter;
341 int gabs = 0;
342
343 /* Refresh the gap ack information. */
344 if (sctp_tsnmap_has_gap(map)) {
Al Viro9f81bcd2006-11-20 17:26:34 -0800345 __u16 start, end;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700346 sctp_tsnmap_iter_init(map, &iter);
347 while (sctp_tsnmap_next_gap_ack(map, &iter,
Al Viro9f81bcd2006-11-20 17:26:34 -0800348 &start,
349 &end)) {
Linus Torvalds1da177e2005-04-16 15:20:36 -0700350
Al Viro9f81bcd2006-11-20 17:26:34 -0800351 map->gabs[gabs].start = htons(start);
352 map->gabs[gabs].end = htons(end);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700353 gabs++;
354 if (gabs >= SCTP_MAX_GABS)
355 break;
356 }
357 }
358 return gabs;
359}
Vlad Yasevich8e1ee182008-10-08 14:18:39 -0700360
361static int sctp_tsnmap_grow(struct sctp_tsnmap *map, u16 gap)
362{
363 unsigned long *new;
364 unsigned long inc;
365 u16 len;
366
367 if (gap >= SCTP_TSN_MAP_SIZE)
368 return 0;
369
370 inc = ALIGN((gap - map->len),BITS_PER_LONG) + SCTP_TSN_MAP_INCREMENT;
371 len = min_t(u16, map->len + inc, SCTP_TSN_MAP_SIZE);
372
373 new = kzalloc(len>>3, GFP_ATOMIC);
374 if (!new)
375 return 0;
376
377 bitmap_copy(new, map->tsn_map, map->max_tsn_seen - map->base_tsn);
378 kfree(map->tsn_map);
379 map->tsn_map = new;
380 map->len = len;
381
382 return 1;
383}