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60c778b2 | 1 | /* SCTP kernel implementation |
1da177e4 LT |
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 | * | |
60c778b2 | 7 | * This file is part of the SCTP kernel implementation |
1da177e4 LT |
8 | * |
9 | * These functions manipulate sctp tsn mapping array. | |
10 | * | |
60c778b2 | 11 | * This SCTP implementation is free software; |
1da177e4 LT |
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 | * | |
60c778b2 | 17 | * This SCTP implementation is distributed in the hope that it |
1da177e4 LT |
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; | |
cc121fa8 | 164 | __u16 start_, end_, offset; |
1da177e4 LT |
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, | |
cc121fa8 | 178 | &started, &start_, &ended, &end_); |
1da177e4 LT |
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, | |
cc121fa8 SS |
196 | &started, &start_, |
197 | &ended, &end_); | |
1da177e4 LT |
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++; | |
cc121fa8 | 205 | end_ = map->len + map->len - 1; |
1da177e4 LT |
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 | ||
cc121fa8 SS |
218 | *start = start_ - gap; |
219 | *end = end_ - gap; | |
1da177e4 LT |
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 | */ | |
d808ad9a | 280 | __u8 *tmp = map->tsn_map; |
1da177e4 LT |
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)) { | |
9f81bcd9 | 404 | __u16 start, end; |
1da177e4 LT |
405 | sctp_tsnmap_iter_init(map, &iter); |
406 | while (sctp_tsnmap_next_gap_ack(map, &iter, | |
9f81bcd9 AV |
407 | &start, |
408 | &end)) { | |
1da177e4 | 409 | |
9f81bcd9 AV |
410 | map->gabs[gabs].start = htons(start); |
411 | map->gabs[gabs].end = htons(end); | |
1da177e4 LT |
412 | gabs++; |
413 | if (gabs >= SCTP_MAX_GABS) | |
414 | break; | |
415 | } | |
416 | } | |
417 | return gabs; | |
418 | } |