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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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