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Arnaldo Carvalho de Meloae31c332005-09-18 00:17:51 -07001/*
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
20int 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 */
Arnaldo Carvalho de Meloe4dfd442006-01-04 01:46:34 -020058 if ((int)av->dccpav_buf_head + len > av->dccpav_vec_len) {
59 const u32 tailsize = av->dccpav_vec_len - av->dccpav_buf_head;
Arnaldo Carvalho de Meloae31c332005-09-18 00:17:51 -070060
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
93struct dccp_ackvec *dccp_ackvec_alloc(const unsigned int len,
Al Virodd0fc662005-10-07 07:46:04 +010094 const gfp_t priority)
Arnaldo Carvalho de Meloae31c332005-09-18 00:17:51 -070095{
Arnaldo Carvalho de Meloe4dfd442006-01-04 01:46:34 -020096 struct dccp_ackvec *av;
Arnaldo Carvalho de Meloae31c332005-09-18 00:17:51 -070097
Arnaldo Carvalho de Meloe4dfd442006-01-04 01:46:34 -020098 BUG_ON(len == 0);
99
100 if (len > DCCP_MAX_ACKVEC_LEN)
101 return NULL;
102
103 av = kmalloc(sizeof(*av) + len, priority);
Arnaldo Carvalho de Meloae31c332005-09-18 00:17:51 -0700104 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
120void dccp_ackvec_free(struct dccp_ackvec *av)
121{
122 kfree(av);
123}
124
125static inline u8 dccp_ackvec_state(const struct dccp_ackvec *av,
Arnaldo Carvalho de Meloe4dfd442006-01-04 01:46:34 -0200126 const u8 index)
Arnaldo Carvalho de Meloae31c332005-09-18 00:17:51 -0700127{
128 return av->dccpav_buf[index] & DCCP_ACKVEC_STATE_MASK;
129}
130
131static inline u8 dccp_ackvec_len(const struct dccp_ackvec *av,
Arnaldo Carvalho de Meloe4dfd442006-01-04 01:46:34 -0200132 const u8 index)
Arnaldo Carvalho de Meloae31c332005-09-18 00:17:51 -0700133{
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 */
142static inline int dccp_ackvec_set_buf_head_state(struct dccp_ackvec *av,
143 const unsigned int packets,
Arnaldo Carvalho de Meloe4dfd442006-01-04 01:46:34 -0200144 const unsigned char state)
Arnaldo Carvalho de Meloae31c332005-09-18 00:17:51 -0700145{
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 */
178int 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);
Arnaldo Carvalho de Meloe4dfd442006-01-04 01:46:34 -0200232 u8 index = av->dccpav_buf_head;
Arnaldo Carvalho de Meloae31c332005-09-18 00:17:51 -0700233
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);
261out:
262 dccp_pr_debug("");
263 return 0;
264
265out_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
273void 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
292void 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
Andrea Bittau6742bbc2006-01-04 01:45:17 -0200300static void dccp_ackvec_throw_away_ack_record(struct dccp_ackvec *av)
Arnaldo Carvalho de Meloae31c332005-09-18 00:17:51 -0700301{
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
Arnaldo Carvalho de Meloe4dfd442006-01-04 01:46:34 -0200310 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;
Arnaldo Carvalho de Meloae31c332005-09-18 00:17:51 -0700314#endif
315 av->dccpav_vec_len -= av->dccpav_sent_len;
316}
317
318void 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);
Andrea Bittau6742bbc2006-01-04 01:45:17 -0200336 dccp_ackvec_throw_away_ack_record(av);
Arnaldo Carvalho de Meloae31c332005-09-18 00:17:51 -0700337 av->dccpav_ack_seqno = DCCP_MAX_SEQNO + 1;
338 }
339}
340
341static 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);
Andrea Bittau6742bbc2006-01-04 01:45:17 -0200399 dccp_ackvec_throw_away_ack_record(av);
Arnaldo Carvalho de Meloae31c332005-09-18 00:17:51 -0700400 }
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
415int 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}