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ae31c339 ACM |
1 | /* |
2 | * net/dccp/ackvec.c | |
3 | * | |
4 | * An implementation of the DCCP protocol | |
5 | * Copyright (c) 2005 Arnaldo Carvalho de Melo <acme@ghostprotocols.net> | |
6 | * | |
7 | * This program is free software; you can redistribute it and/or modify it | |
8 | * under the terms of the GNU General Public License as published by the | |
9 | * Free Software Foundation; version 2 of the License; | |
10 | */ | |
11 | ||
12 | #include "ackvec.h" | |
13 | #include "dccp.h" | |
14 | ||
15 | #include <linux/dccp.h> | |
16 | #include <linux/skbuff.h> | |
17 | ||
18 | #include <net/sock.h> | |
19 | ||
20 | int dccp_insert_option_ackvec(struct sock *sk, struct sk_buff *skb) | |
21 | { | |
22 | struct dccp_sock *dp = dccp_sk(sk); | |
23 | struct dccp_ackvec *av = dp->dccps_hc_rx_ackvec; | |
24 | int len = av->dccpav_vec_len + 2; | |
25 | struct timeval now; | |
26 | u32 elapsed_time; | |
27 | unsigned char *to, *from; | |
28 | ||
29 | dccp_timestamp(sk, &now); | |
30 | elapsed_time = timeval_delta(&now, &av->dccpav_time) / 10; | |
31 | ||
32 | if (elapsed_time != 0) | |
33 | dccp_insert_option_elapsed_time(sk, skb, elapsed_time); | |
34 | ||
35 | if (DCCP_SKB_CB(skb)->dccpd_opt_len + len > DCCP_MAX_OPT_LEN) | |
36 | return -1; | |
37 | ||
38 | /* | |
39 | * XXX: now we have just one ack vector sent record, so | |
40 | * we have to wait for it to be cleared. | |
41 | * | |
42 | * Of course this is not acceptable, but this is just for | |
43 | * basic testing now. | |
44 | */ | |
45 | if (av->dccpav_ack_seqno != DCCP_MAX_SEQNO + 1) | |
46 | return -1; | |
47 | ||
48 | DCCP_SKB_CB(skb)->dccpd_opt_len += len; | |
49 | ||
50 | to = skb_push(skb, len); | |
51 | *to++ = DCCPO_ACK_VECTOR_0; | |
52 | *to++ = len; | |
53 | ||
54 | len = av->dccpav_vec_len; | |
55 | from = av->dccpav_buf + av->dccpav_buf_head; | |
56 | ||
57 | /* Check if buf_head wraps */ | |
e4dfd449 ACM |
58 | if ((int)av->dccpav_buf_head + len > av->dccpav_vec_len) { |
59 | const u32 tailsize = av->dccpav_vec_len - av->dccpav_buf_head; | |
ae31c339 ACM |
60 | |
61 | memcpy(to, from, tailsize); | |
62 | to += tailsize; | |
63 | len -= tailsize; | |
64 | from = av->dccpav_buf; | |
65 | } | |
66 | ||
67 | memcpy(to, from, len); | |
68 | /* | |
69 | * From draft-ietf-dccp-spec-11.txt: | |
70 | * | |
71 | * For each acknowledgement it sends, the HC-Receiver will add an | |
72 | * acknowledgement record. ack_seqno will equal the HC-Receiver | |
73 | * sequence number it used for the ack packet; ack_ptr will equal | |
74 | * buf_head; ack_ackno will equal buf_ackno; and ack_nonce will | |
75 | * equal buf_nonce. | |
76 | * | |
77 | * This implemention uses just one ack record for now. | |
78 | */ | |
79 | av->dccpav_ack_seqno = DCCP_SKB_CB(skb)->dccpd_seq; | |
80 | av->dccpav_ack_ptr = av->dccpav_buf_head; | |
81 | av->dccpav_ack_ackno = av->dccpav_buf_ackno; | |
82 | av->dccpav_ack_nonce = av->dccpav_buf_nonce; | |
83 | av->dccpav_sent_len = av->dccpav_vec_len; | |
84 | ||
85 | dccp_pr_debug("%sACK Vector 0, len=%d, ack_seqno=%llu, " | |
86 | "ack_ackno=%llu\n", | |
87 | debug_prefix, av->dccpav_sent_len, | |
88 | (unsigned long long)av->dccpav_ack_seqno, | |
89 | (unsigned long long)av->dccpav_ack_ackno); | |
90 | return -1; | |
91 | } | |
92 | ||
93 | struct dccp_ackvec *dccp_ackvec_alloc(const unsigned int len, | |
dd0fc66f | 94 | const gfp_t priority) |
ae31c339 | 95 | { |
e4dfd449 | 96 | struct dccp_ackvec *av; |
ae31c339 | 97 | |
e4dfd449 ACM |
98 | BUG_ON(len == 0); |
99 | ||
100 | if (len > DCCP_MAX_ACKVEC_LEN) | |
101 | return NULL; | |
102 | ||
103 | av = kmalloc(sizeof(*av) + len, priority); | |
ae31c339 ACM |
104 | if (av != NULL) { |
105 | av->dccpav_buf_len = len; | |
106 | av->dccpav_buf_head = | |
107 | av->dccpav_buf_tail = av->dccpav_buf_len - 1; | |
108 | av->dccpav_buf_ackno = | |
109 | av->dccpav_ack_ackno = av->dccpav_ack_seqno = ~0LLU; | |
110 | av->dccpav_buf_nonce = av->dccpav_buf_nonce = 0; | |
111 | av->dccpav_ack_ptr = 0; | |
112 | av->dccpav_time.tv_sec = 0; | |
113 | av->dccpav_time.tv_usec = 0; | |
114 | av->dccpav_sent_len = av->dccpav_vec_len = 0; | |
115 | } | |
116 | ||
117 | return av; | |
118 | } | |
119 | ||
120 | void dccp_ackvec_free(struct dccp_ackvec *av) | |
121 | { | |
122 | kfree(av); | |
123 | } | |
124 | ||
125 | static inline u8 dccp_ackvec_state(const struct dccp_ackvec *av, | |
e4dfd449 | 126 | const u8 index) |
ae31c339 ACM |
127 | { |
128 | return av->dccpav_buf[index] & DCCP_ACKVEC_STATE_MASK; | |
129 | } | |
130 | ||
131 | static inline u8 dccp_ackvec_len(const struct dccp_ackvec *av, | |
e4dfd449 | 132 | const u8 index) |
ae31c339 ACM |
133 | { |
134 | return av->dccpav_buf[index] & DCCP_ACKVEC_LEN_MASK; | |
135 | } | |
136 | ||
137 | /* | |
138 | * If several packets are missing, the HC-Receiver may prefer to enter multiple | |
139 | * bytes with run length 0, rather than a single byte with a larger run length; | |
140 | * this simplifies table updates if one of the missing packets arrives. | |
141 | */ | |
142 | static inline int dccp_ackvec_set_buf_head_state(struct dccp_ackvec *av, | |
143 | const unsigned int packets, | |
e4dfd449 | 144 | const unsigned char state) |
ae31c339 ACM |
145 | { |
146 | unsigned int gap; | |
147 | signed long new_head; | |
148 | ||
149 | if (av->dccpav_vec_len + packets > av->dccpav_buf_len) | |
150 | return -ENOBUFS; | |
151 | ||
152 | gap = packets - 1; | |
153 | new_head = av->dccpav_buf_head - packets; | |
154 | ||
155 | if (new_head < 0) { | |
156 | if (gap > 0) { | |
157 | memset(av->dccpav_buf, DCCP_ACKVEC_STATE_NOT_RECEIVED, | |
158 | gap + new_head + 1); | |
159 | gap = -new_head; | |
160 | } | |
161 | new_head += av->dccpav_buf_len; | |
162 | } | |
163 | ||
164 | av->dccpav_buf_head = new_head; | |
165 | ||
166 | if (gap > 0) | |
167 | memset(av->dccpav_buf + av->dccpav_buf_head + 1, | |
168 | DCCP_ACKVEC_STATE_NOT_RECEIVED, gap); | |
169 | ||
170 | av->dccpav_buf[av->dccpav_buf_head] = state; | |
171 | av->dccpav_vec_len += packets; | |
172 | return 0; | |
173 | } | |
174 | ||
175 | /* | |
176 | * Implements the draft-ietf-dccp-spec-11.txt Appendix A | |
177 | */ | |
178 | int dccp_ackvec_add(struct dccp_ackvec *av, const struct sock *sk, | |
179 | const u64 ackno, const u8 state) | |
180 | { | |
181 | /* | |
182 | * Check at the right places if the buffer is full, if it is, tell the | |
183 | * caller to start dropping packets till the HC-Sender acks our ACK | |
184 | * vectors, when we will free up space in dccpav_buf. | |
185 | * | |
186 | * We may well decide to do buffer compression, etc, but for now lets | |
187 | * just drop. | |
188 | * | |
189 | * From Appendix A: | |
190 | * | |
191 | * Of course, the circular buffer may overflow, either when the | |
192 | * HC-Sender is sending data at a very high rate, when the | |
193 | * HC-Receiver's acknowledgements are not reaching the HC-Sender, | |
194 | * or when the HC-Sender is forgetting to acknowledge those acks | |
195 | * (so the HC-Receiver is unable to clean up old state). In this | |
196 | * case, the HC-Receiver should either compress the buffer (by | |
197 | * increasing run lengths when possible), transfer its state to | |
198 | * a larger buffer, or, as a last resort, drop all received | |
199 | * packets, without processing them whatsoever, until its buffer | |
200 | * shrinks again. | |
201 | */ | |
202 | ||
203 | /* See if this is the first ackno being inserted */ | |
204 | if (av->dccpav_vec_len == 0) { | |
205 | av->dccpav_buf[av->dccpav_buf_head] = state; | |
206 | av->dccpav_vec_len = 1; | |
207 | } else if (after48(ackno, av->dccpav_buf_ackno)) { | |
208 | const u64 delta = dccp_delta_seqno(av->dccpav_buf_ackno, | |
209 | ackno); | |
210 | ||
211 | /* | |
212 | * Look if the state of this packet is the same as the | |
213 | * previous ackno and if so if we can bump the head len. | |
214 | */ | |
215 | if (delta == 1 && | |
216 | dccp_ackvec_state(av, av->dccpav_buf_head) == state && | |
217 | (dccp_ackvec_len(av, av->dccpav_buf_head) < | |
218 | DCCP_ACKVEC_LEN_MASK)) | |
219 | av->dccpav_buf[av->dccpav_buf_head]++; | |
220 | else if (dccp_ackvec_set_buf_head_state(av, delta, state)) | |
221 | return -ENOBUFS; | |
222 | } else { | |
223 | /* | |
224 | * A.1.2. Old Packets | |
225 | * | |
226 | * When a packet with Sequence Number S arrives, and | |
227 | * S <= buf_ackno, the HC-Receiver will scan the table | |
228 | * for the byte corresponding to S. (Indexing structures | |
229 | * could reduce the complexity of this scan.) | |
230 | */ | |
231 | u64 delta = dccp_delta_seqno(ackno, av->dccpav_buf_ackno); | |
e4dfd449 | 232 | u8 index = av->dccpav_buf_head; |
ae31c339 ACM |
233 | |
234 | while (1) { | |
235 | const u8 len = dccp_ackvec_len(av, index); | |
236 | const u8 state = dccp_ackvec_state(av, index); | |
237 | /* | |
238 | * valid packets not yet in dccpav_buf have a reserved | |
239 | * entry, with a len equal to 0. | |
240 | */ | |
241 | if (state == DCCP_ACKVEC_STATE_NOT_RECEIVED && | |
242 | len == 0 && delta == 0) { /* Found our | |
243 | reserved seat! */ | |
244 | dccp_pr_debug("Found %llu reserved seat!\n", | |
245 | (unsigned long long)ackno); | |
246 | av->dccpav_buf[index] = state; | |
247 | goto out; | |
248 | } | |
249 | /* len == 0 means one packet */ | |
250 | if (delta < len + 1) | |
251 | goto out_duplicate; | |
252 | ||
253 | delta -= len + 1; | |
254 | if (++index == av->dccpav_buf_len) | |
255 | index = 0; | |
256 | } | |
257 | } | |
258 | ||
259 | av->dccpav_buf_ackno = ackno; | |
260 | dccp_timestamp(sk, &av->dccpav_time); | |
261 | out: | |
262 | dccp_pr_debug(""); | |
263 | return 0; | |
264 | ||
265 | out_duplicate: | |
266 | /* Duplicate packet */ | |
267 | dccp_pr_debug("Received a dup or already considered lost " | |
268 | "packet: %llu\n", (unsigned long long)ackno); | |
269 | return -EILSEQ; | |
270 | } | |
271 | ||
272 | #ifdef CONFIG_IP_DCCP_DEBUG | |
273 | void dccp_ackvector_print(const u64 ackno, const unsigned char *vector, int len) | |
274 | { | |
275 | if (!dccp_debug) | |
276 | return; | |
277 | ||
278 | printk("ACK vector len=%d, ackno=%llu |", len, | |
279 | (unsigned long long)ackno); | |
280 | ||
281 | while (len--) { | |
282 | const u8 state = (*vector & DCCP_ACKVEC_STATE_MASK) >> 6; | |
283 | const u8 rl = *vector & DCCP_ACKVEC_LEN_MASK; | |
284 | ||
285 | printk("%d,%d|", state, rl); | |
286 | ++vector; | |
287 | } | |
288 | ||
289 | printk("\n"); | |
290 | } | |
291 | ||
292 | void dccp_ackvec_print(const struct dccp_ackvec *av) | |
293 | { | |
294 | dccp_ackvector_print(av->dccpav_buf_ackno, | |
295 | av->dccpav_buf + av->dccpav_buf_head, | |
296 | av->dccpav_vec_len); | |
297 | } | |
298 | #endif | |
299 | ||
6742bbcb | 300 | static void dccp_ackvec_throw_away_ack_record(struct dccp_ackvec *av) |
ae31c339 ACM |
301 | { |
302 | /* | |
303 | * As we're keeping track of the ack vector size (dccpav_vec_len) and | |
304 | * the sent ack vector size (dccpav_sent_len) we don't need | |
305 | * dccpav_buf_tail at all, but keep this code here as in the future | |
306 | * we'll implement a vector of ack records, as suggested in | |
307 | * draft-ietf-dccp-spec-11.txt Appendix A. -acme | |
308 | */ | |
309 | #if 0 | |
e4dfd449 ACM |
310 | u32 new_buf_tail = av->dccpav_ack_ptr + 1; |
311 | if (new_buf_tail >= av->dccpav_vec_len) | |
312 | new_buf_tail -= av->dccpav_vec_len; | |
313 | av->dccpav_buf_tail = new_buf_tail; | |
ae31c339 ACM |
314 | #endif |
315 | av->dccpav_vec_len -= av->dccpav_sent_len; | |
316 | } | |
317 | ||
318 | void dccp_ackvec_check_rcv_ackno(struct dccp_ackvec *av, struct sock *sk, | |
319 | const u64 ackno) | |
320 | { | |
321 | /* Check if we actually sent an ACK vector */ | |
322 | if (av->dccpav_ack_seqno == DCCP_MAX_SEQNO + 1) | |
323 | return; | |
324 | ||
325 | if (ackno == av->dccpav_ack_seqno) { | |
326 | #ifdef CONFIG_IP_DCCP_DEBUG | |
327 | struct dccp_sock *dp = dccp_sk(sk); | |
328 | const char *debug_prefix = dp->dccps_role == DCCP_ROLE_CLIENT ? | |
329 | "CLIENT rx ack: " : "server rx ack: "; | |
330 | #endif | |
331 | dccp_pr_debug("%sACK packet 0, len=%d, ack_seqno=%llu, " | |
332 | "ack_ackno=%llu, ACKED!\n", | |
333 | debug_prefix, 1, | |
334 | (unsigned long long)av->dccpav_ack_seqno, | |
335 | (unsigned long long)av->dccpav_ack_ackno); | |
6742bbcb | 336 | dccp_ackvec_throw_away_ack_record(av); |
ae31c339 ACM |
337 | av->dccpav_ack_seqno = DCCP_MAX_SEQNO + 1; |
338 | } | |
339 | } | |
340 | ||
341 | static void dccp_ackvec_check_rcv_ackvector(struct dccp_ackvec *av, | |
342 | struct sock *sk, u64 ackno, | |
343 | const unsigned char len, | |
344 | const unsigned char *vector) | |
345 | { | |
346 | unsigned char i; | |
347 | ||
348 | /* Check if we actually sent an ACK vector */ | |
349 | if (av->dccpav_ack_seqno == DCCP_MAX_SEQNO + 1) | |
350 | return; | |
351 | /* | |
352 | * We're in the receiver half connection, so if the received an ACK | |
353 | * vector ackno (e.g. 50) before dccpav_ack_seqno (e.g. 52), we're | |
354 | * not interested. | |
355 | * | |
356 | * Extra explanation with example: | |
357 | * | |
358 | * if we received an ACK vector with ackno 50, it can only be acking | |
359 | * 50, 49, 48, etc, not 52 (the seqno for the ACK vector we sent). | |
360 | */ | |
361 | /* dccp_pr_debug("is %llu < %llu? ", ackno, av->dccpav_ack_seqno); */ | |
362 | if (before48(ackno, av->dccpav_ack_seqno)) { | |
363 | /* dccp_pr_debug_cat("yes\n"); */ | |
364 | return; | |
365 | } | |
366 | /* dccp_pr_debug_cat("no\n"); */ | |
367 | ||
368 | i = len; | |
369 | while (i--) { | |
370 | const u8 rl = *vector & DCCP_ACKVEC_LEN_MASK; | |
371 | u64 ackno_end_rl; | |
372 | ||
373 | dccp_set_seqno(&ackno_end_rl, ackno - rl); | |
374 | ||
375 | /* | |
376 | * dccp_pr_debug("is %llu <= %llu <= %llu? ", ackno_end_rl, | |
377 | * av->dccpav_ack_seqno, ackno); | |
378 | */ | |
379 | if (between48(av->dccpav_ack_seqno, ackno_end_rl, ackno)) { | |
380 | const u8 state = (*vector & | |
381 | DCCP_ACKVEC_STATE_MASK) >> 6; | |
382 | /* dccp_pr_debug_cat("yes\n"); */ | |
383 | ||
384 | if (state != DCCP_ACKVEC_STATE_NOT_RECEIVED) { | |
385 | #ifdef CONFIG_IP_DCCP_DEBUG | |
386 | struct dccp_sock *dp = dccp_sk(sk); | |
387 | const char *debug_prefix = | |
388 | dp->dccps_role == DCCP_ROLE_CLIENT ? | |
389 | "CLIENT rx ack: " : "server rx ack: "; | |
390 | #endif | |
391 | dccp_pr_debug("%sACK vector 0, len=%d, " | |
392 | "ack_seqno=%llu, ack_ackno=%llu, " | |
393 | "ACKED!\n", | |
394 | debug_prefix, len, | |
395 | (unsigned long long) | |
396 | av->dccpav_ack_seqno, | |
397 | (unsigned long long) | |
398 | av->dccpav_ack_ackno); | |
6742bbcb | 399 | dccp_ackvec_throw_away_ack_record(av); |
ae31c339 ACM |
400 | } |
401 | /* | |
402 | * If dccpav_ack_seqno was not received, no problem | |
403 | * we'll send another ACK vector. | |
404 | */ | |
405 | av->dccpav_ack_seqno = DCCP_MAX_SEQNO + 1; | |
406 | break; | |
407 | } | |
408 | /* dccp_pr_debug_cat("no\n"); */ | |
409 | ||
410 | dccp_set_seqno(&ackno, ackno_end_rl - 1); | |
411 | ++vector; | |
412 | } | |
413 | } | |
414 | ||
415 | int dccp_ackvec_parse(struct sock *sk, const struct sk_buff *skb, | |
416 | const u8 opt, const u8 *value, const u8 len) | |
417 | { | |
418 | if (len > DCCP_MAX_ACKVEC_LEN) | |
419 | return -1; | |
420 | ||
421 | /* dccp_ackvector_print(DCCP_SKB_CB(skb)->dccpd_ack_seq, value, len); */ | |
422 | dccp_ackvec_check_rcv_ackvector(dccp_sk(sk)->dccps_hc_rx_ackvec, sk, | |
423 | DCCP_SKB_CB(skb)->dccpd_ack_seq, | |
424 | len, value); | |
425 | return 0; | |
426 | } |