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
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