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1/*
2 * Copyright (c) 2007 The University of Aberdeen, Scotland, UK
3 * Copyright (c) 2005-7 The University of Waikato, Hamilton, New Zealand.
4 * Copyright (c) 2005-7 Ian McDonald <ian.mcdonald@jandi.co.nz>
5 *
6 * An implementation of the DCCP protocol
7 *
8 * This code has been developed by the University of Waikato WAND
9 * research group. For further information please see http://www.wand.net.nz/
10 *
11 * This code also uses code from Lulea University, rereleased as GPL by its
12 * authors:
13 * Copyright (c) 2003 Nils-Erik Mattsson, Joacim Haggmark, Magnus Erixzon
14 *
15 * Changes to meet Linux coding standards, to make it meet latest ccid3 draft
16 * and to make it work as a loadable module in the DCCP stack written by
17 * Arnaldo Carvalho de Melo <acme@conectiva.com.br>.
18 *
19 * Copyright (c) 2005 Arnaldo Carvalho de Melo <acme@conectiva.com.br>
20 *
21 * This program is free software; you can redistribute it and/or modify
22 * it under the terms of the GNU General Public License as published by
23 * the Free Software Foundation; either version 2 of the License, or
24 * (at your option) any later version.
25 *
26 * This program is distributed in the hope that it will be useful,
27 * but WITHOUT ANY WARRANTY; without even the implied warranty of
28 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
29 * GNU General Public License for more details.
30 *
31 * You should have received a copy of the GNU General Public License
32 * along with this program; if not, write to the Free Software
33 * Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
34 */
35#include "../dccp.h"
36#include "ccid3.h"
37
38#include <asm/unaligned.h>
39
40#ifdef CONFIG_IP_DCCP_CCID3_DEBUG
41static int ccid3_debug;
42#define ccid3_pr_debug(format, a...) DCCP_PR_DEBUG(ccid3_debug, format, ##a)
43#else
44#define ccid3_pr_debug(format, a...)
45#endif
46
47/*
48 * Transmitter Half-Connection Routines
49 */
50#ifdef CONFIG_IP_DCCP_CCID3_DEBUG
51static const char *ccid3_tx_state_name(enum ccid3_hc_tx_states state)
52{
53 static const char *const ccid3_state_names[] = {
54 [TFRC_SSTATE_NO_SENT] = "NO_SENT",
55 [TFRC_SSTATE_NO_FBACK] = "NO_FBACK",
56 [TFRC_SSTATE_FBACK] = "FBACK",
57 };
58
59 return ccid3_state_names[state];
60}
61#endif
62
63static void ccid3_hc_tx_set_state(struct sock *sk,
64 enum ccid3_hc_tx_states state)
65{
66 struct ccid3_hc_tx_sock *hc = ccid3_hc_tx_sk(sk);
67 enum ccid3_hc_tx_states oldstate = hc->tx_state;
68
69 ccid3_pr_debug("%s(%p) %-8.8s -> %s\n",
70 dccp_role(sk), sk, ccid3_tx_state_name(oldstate),
71 ccid3_tx_state_name(state));
72 WARN_ON(state == oldstate);
73 hc->tx_state = state;
74}
75
76/*
77 * Compute the initial sending rate X_init in the manner of RFC 3390:
78 *
79 * X_init = min(4 * s, max(2 * s, 4380 bytes)) / RTT
80 *
81 * Note that RFC 3390 uses MSS, RFC 4342 refers to RFC 3390, and rfc3448bis
82 * (rev-02) clarifies the use of RFC 3390 with regard to the above formula.
83 * For consistency with other parts of the code, X_init is scaled by 2^6.
84 */
85static inline u64 rfc3390_initial_rate(struct sock *sk)
86{
87 const struct ccid3_hc_tx_sock *hc = ccid3_hc_tx_sk(sk);
88 const __u32 w_init = clamp_t(__u32, 4380U, 2 * hc->tx_s, 4 * hc->tx_s);
89
90 return scaled_div(w_init << 6, hc->tx_rtt);
91}
92
93/**
94 * ccid3_update_send_interval - Calculate new t_ipi = s / X_inst
95 * This respects the granularity of X_inst (64 * bytes/second).
96 */
97static void ccid3_update_send_interval(struct ccid3_hc_tx_sock *hc)
98{
99 hc->tx_t_ipi = scaled_div32(((u64)hc->tx_s) << 6, hc->tx_x);
100
101 ccid3_pr_debug("t_ipi=%u, s=%u, X=%u\n", hc->tx_t_ipi,
102 hc->tx_s, (unsigned)(hc->tx_x >> 6));
103}
104
105static u32 ccid3_hc_tx_idle_rtt(struct ccid3_hc_tx_sock *hc, ktime_t now)
106{
107 u32 delta = ktime_us_delta(now, hc->tx_t_last_win_count);
108
109 return delta / hc->tx_rtt;
110}
111
112/**
113 * ccid3_hc_tx_update_x - Update allowed sending rate X
114 * @stamp: most recent time if available - can be left NULL.
115 * This function tracks draft rfc3448bis, check there for latest details.
116 *
117 * Note: X and X_recv are both stored in units of 64 * bytes/second, to support
118 * fine-grained resolution of sending rates. This requires scaling by 2^6
119 * throughout the code. Only X_calc is unscaled (in bytes/second).
120 *
121 */
122static void ccid3_hc_tx_update_x(struct sock *sk, ktime_t *stamp)
123{
124 struct ccid3_hc_tx_sock *hc = ccid3_hc_tx_sk(sk);
125 __u64 min_rate = 2 * hc->tx_x_recv;
126 const __u64 old_x = hc->tx_x;
127 ktime_t now = stamp ? *stamp : ktime_get_real();
128
129 /*
130 * Handle IDLE periods: do not reduce below RFC3390 initial sending rate
131 * when idling [RFC 4342, 5.1]. Definition of idling is from rfc3448bis:
132 * a sender is idle if it has not sent anything over a 2-RTT-period.
133 * For consistency with X and X_recv, min_rate is also scaled by 2^6.
134 */
135 if (ccid3_hc_tx_idle_rtt(hc, now) >= 2) {
136 min_rate = rfc3390_initial_rate(sk);
137 min_rate = max(min_rate, 2 * hc->tx_x_recv);
138 }
139
140 if (hc->tx_p > 0) {
141
142 hc->tx_x = min(((__u64)hc->tx_x_calc) << 6, min_rate);
143 hc->tx_x = max(hc->tx_x, (((__u64)hc->tx_s) << 6) / TFRC_T_MBI);
144
145 } else if (ktime_us_delta(now, hc->tx_t_ld) - (s64)hc->tx_rtt >= 0) {
146
147 hc->tx_x = min(2 * hc->tx_x, min_rate);
148 hc->tx_x = max(hc->tx_x,
149 scaled_div(((__u64)hc->tx_s) << 6, hc->tx_rtt));
150 hc->tx_t_ld = now;
151 }
152
153 if (hc->tx_x != old_x) {
154 ccid3_pr_debug("X_prev=%u, X_now=%u, X_calc=%u, "
155 "X_recv=%u\n", (unsigned)(old_x >> 6),
156 (unsigned)(hc->tx_x >> 6), hc->tx_x_calc,
157 (unsigned)(hc->tx_x_recv >> 6));
158
159 ccid3_update_send_interval(hc);
160 }
161}
162
163/*
164 * Track the mean packet size `s' (cf. RFC 4342, 5.3 and RFC 3448, 4.1)
165 * @len: DCCP packet payload size in bytes
166 */
167static inline void ccid3_hc_tx_update_s(struct ccid3_hc_tx_sock *hc, int len)
168{
169 const u16 old_s = hc->tx_s;
170
171 hc->tx_s = tfrc_ewma(hc->tx_s, len, 9);
172
173 if (hc->tx_s != old_s)
174 ccid3_update_send_interval(hc);
175}
176
177/*
178 * Update Window Counter using the algorithm from [RFC 4342, 8.1].
179 * As elsewhere, RTT > 0 is assumed by using dccp_sample_rtt().
180 */
181static inline void ccid3_hc_tx_update_win_count(struct ccid3_hc_tx_sock *hc,
182 ktime_t now)
183{
184 u32 delta = ktime_us_delta(now, hc->tx_t_last_win_count),
185 quarter_rtts = (4 * delta) / hc->tx_rtt;
186
187 if (quarter_rtts > 0) {
188 hc->tx_t_last_win_count = now;
189 hc->tx_last_win_count += min(quarter_rtts, 5U);
190 hc->tx_last_win_count &= 0xF; /* mod 16 */
191 }
192}
193
194static void ccid3_hc_tx_no_feedback_timer(unsigned long data)
195{
196 struct sock *sk = (struct sock *)data;
197 struct ccid3_hc_tx_sock *hc = ccid3_hc_tx_sk(sk);
198 unsigned long t_nfb = USEC_PER_SEC / 5;
199
200 bh_lock_sock(sk);
201 if (sock_owned_by_user(sk)) {
202 /* Try again later. */
203 /* XXX: set some sensible MIB */
204 goto restart_timer;
205 }
206
207 ccid3_pr_debug("%s(%p, state=%s) - entry\n", dccp_role(sk), sk,
208 ccid3_tx_state_name(hc->tx_state));
209
210 /* Ignore and do not restart after leaving the established state */
211 if ((1 << sk->sk_state) & ~(DCCPF_OPEN | DCCPF_PARTOPEN))
212 goto out;
213
214 /* Reset feedback state to "no feedback received" */
215 if (hc->tx_state == TFRC_SSTATE_FBACK)
216 ccid3_hc_tx_set_state(sk, TFRC_SSTATE_NO_FBACK);
217
218 /*
219 * Determine new allowed sending rate X as per draft rfc3448bis-00, 4.4
220 * RTO is 0 if and only if no feedback has been received yet.
221 */
222 if (hc->tx_t_rto == 0 || hc->tx_p == 0) {
223
224 /* halve send rate directly */
225 hc->tx_x = max(hc->tx_x / 2,
226 (((__u64)hc->tx_s) << 6) / TFRC_T_MBI);
227 ccid3_update_send_interval(hc);
228 } else {
229 /*
230 * Modify the cached value of X_recv
231 *
232 * If (X_calc > 2 * X_recv)
233 * X_recv = max(X_recv / 2, s / (2 * t_mbi));
234 * Else
235 * X_recv = X_calc / 4;
236 *
237 * Note that X_recv is scaled by 2^6 while X_calc is not
238 */
239 BUG_ON(hc->tx_p && !hc->tx_x_calc);
240
241 if (hc->tx_x_calc > (hc->tx_x_recv >> 5))
242 hc->tx_x_recv =
243 max(hc->tx_x_recv / 2,
244 (((__u64)hc->tx_s) << 6) / (2*TFRC_T_MBI));
245 else {
246 hc->tx_x_recv = hc->tx_x_calc;
247 hc->tx_x_recv <<= 4;
248 }
249 ccid3_hc_tx_update_x(sk, NULL);
250 }
251 ccid3_pr_debug("Reduced X to %llu/64 bytes/sec\n",
252 (unsigned long long)hc->tx_x);
253
254 /*
255 * Set new timeout for the nofeedback timer.
256 * See comments in packet_recv() regarding the value of t_RTO.
257 */
258 if (unlikely(hc->tx_t_rto == 0)) /* no feedback received yet */
259 t_nfb = TFRC_INITIAL_TIMEOUT;
260 else
261 t_nfb = max(hc->tx_t_rto, 2 * hc->tx_t_ipi);
262
263restart_timer:
264 sk_reset_timer(sk, &hc->tx_no_feedback_timer,
265 jiffies + usecs_to_jiffies(t_nfb));
266out:
267 bh_unlock_sock(sk);
268 sock_put(sk);
269}
270
271/**
272 * ccid3_hc_tx_send_packet - Delay-based dequeueing of TX packets
273 * @skb: next packet candidate to send on @sk
274 * This function uses the convention of ccid_packet_dequeue_eval() and
275 * returns a millisecond-delay value between 0 and t_mbi = 64000 msec.
276 */
277static int ccid3_hc_tx_send_packet(struct sock *sk, struct sk_buff *skb)
278{
279 struct dccp_sock *dp = dccp_sk(sk);
280 struct ccid3_hc_tx_sock *hc = ccid3_hc_tx_sk(sk);
281 ktime_t now = ktime_get_real();
282 s64 delay;
283
284 /*
285 * This function is called only for Data and DataAck packets. Sending
286 * zero-sized Data(Ack)s is theoretically possible, but for congestion
287 * control this case is pathological - ignore it.
288 */
289 if (unlikely(skb->len == 0))
290 return -EBADMSG;
291
292 if (hc->tx_state == TFRC_SSTATE_NO_SENT) {
293 sk_reset_timer(sk, &hc->tx_no_feedback_timer, (jiffies +
294 usecs_to_jiffies(TFRC_INITIAL_TIMEOUT)));
295 hc->tx_last_win_count = 0;
296 hc->tx_t_last_win_count = now;
297
298 /* Set t_0 for initial packet */
299 hc->tx_t_nom = now;
300
301 hc->tx_s = skb->len;
302
303 /*
304 * Use initial RTT sample when available: recommended by erratum
305 * to RFC 4342. This implements the initialisation procedure of
306 * draft rfc3448bis, section 4.2. Remember, X is scaled by 2^6.
307 */
308 if (dp->dccps_syn_rtt) {
309 ccid3_pr_debug("SYN RTT = %uus\n", dp->dccps_syn_rtt);
310 hc->tx_rtt = dp->dccps_syn_rtt;
311 hc->tx_x = rfc3390_initial_rate(sk);
312 hc->tx_t_ld = now;
313 } else {
314 /*
315 * Sender does not have RTT sample:
316 * - set fallback RTT (RFC 4340, 3.4) since a RTT value
317 * is needed in several parts (e.g. window counter);
318 * - set sending rate X_pps = 1pps as per RFC 3448, 4.2.
319 */
320 hc->tx_rtt = DCCP_FALLBACK_RTT;
321 hc->tx_x = hc->tx_s;
322 hc->tx_x <<= 6;
323 }
324 ccid3_update_send_interval(hc);
325
326 ccid3_hc_tx_set_state(sk, TFRC_SSTATE_NO_FBACK);
327
328 } else {
329 delay = ktime_us_delta(hc->tx_t_nom, now);
330 ccid3_pr_debug("delay=%ld\n", (long)delay);
331 /*
332 * Scheduling of packet transmissions (RFC 5348, 8.3)
333 *
334 * if (t_now > t_nom - delta)
335 * // send the packet now
336 * else
337 * // send the packet in (t_nom - t_now) milliseconds.
338 */
339 if (delay >= TFRC_T_DELTA)
340 return (u32)delay / USEC_PER_MSEC;
341
342 ccid3_hc_tx_update_win_count(hc, now);
343 }
344
345 /* prepare to send now (add options etc.) */
346 dp->dccps_hc_tx_insert_options = 1;
347 DCCP_SKB_CB(skb)->dccpd_ccval = hc->tx_last_win_count;
348
349 /* set the nominal send time for the next following packet */
350 hc->tx_t_nom = ktime_add_us(hc->tx_t_nom, hc->tx_t_ipi);
351 return CCID_PACKET_SEND_AT_ONCE;
352}
353
354static void ccid3_hc_tx_packet_sent(struct sock *sk, unsigned int len)
355{
356 struct ccid3_hc_tx_sock *hc = ccid3_hc_tx_sk(sk);
357
358 ccid3_hc_tx_update_s(hc, len);
359
360 if (tfrc_tx_hist_add(&hc->tx_hist, dccp_sk(sk)->dccps_gss))
361 DCCP_CRIT("packet history - out of memory!");
362}
363
364static void ccid3_hc_tx_packet_recv(struct sock *sk, struct sk_buff *skb)
365{
366 struct ccid3_hc_tx_sock *hc = ccid3_hc_tx_sk(sk);
367 struct tfrc_tx_hist_entry *acked;
368 ktime_t now;
369 unsigned long t_nfb;
370 u32 r_sample;
371
372 /* we are only interested in ACKs */
373 if (!(DCCP_SKB_CB(skb)->dccpd_type == DCCP_PKT_ACK ||
374 DCCP_SKB_CB(skb)->dccpd_type == DCCP_PKT_DATAACK))
375 return;
376 /*
377 * Locate the acknowledged packet in the TX history.
378 *
379 * Returning "entry not found" here can for instance happen when
380 * - the host has not sent out anything (e.g. a passive server),
381 * - the Ack is outdated (packet with higher Ack number was received),
382 * - it is a bogus Ack (for a packet not sent on this connection).
383 */
384 acked = tfrc_tx_hist_find_entry(hc->tx_hist, dccp_hdr_ack_seq(skb));
385 if (acked == NULL)
386 return;
387 /* For the sake of RTT sampling, ignore/remove all older entries */
388 tfrc_tx_hist_purge(&acked->next);
389
390 /* Update the moving average for the RTT estimate (RFC 3448, 4.3) */
391 now = ktime_get_real();
392 r_sample = dccp_sample_rtt(sk, ktime_us_delta(now, acked->stamp));
393 hc->tx_rtt = tfrc_ewma(hc->tx_rtt, r_sample, 9);
394
395 /*
396 * Update allowed sending rate X as per draft rfc3448bis-00, 4.2/3
397 */
398 if (hc->tx_state == TFRC_SSTATE_NO_FBACK) {
399 ccid3_hc_tx_set_state(sk, TFRC_SSTATE_FBACK);
400
401 if (hc->tx_t_rto == 0) {
402 /*
403 * Initial feedback packet: Larger Initial Windows (4.2)
404 */
405 hc->tx_x = rfc3390_initial_rate(sk);
406 hc->tx_t_ld = now;
407
408 ccid3_update_send_interval(hc);
409
410 goto done_computing_x;
411 } else if (hc->tx_p == 0) {
412 /*
413 * First feedback after nofeedback timer expiry (4.3)
414 */
415 goto done_computing_x;
416 }
417 }
418
419 /* Update sending rate (step 4 of [RFC 3448, 4.3]) */
420 if (hc->tx_p > 0)
421 hc->tx_x_calc = tfrc_calc_x(hc->tx_s, hc->tx_rtt, hc->tx_p);
422 ccid3_hc_tx_update_x(sk, &now);
423
424done_computing_x:
425 ccid3_pr_debug("%s(%p), RTT=%uus (sample=%uus), s=%u, "
426 "p=%u, X_calc=%u, X_recv=%u, X=%u\n",
427 dccp_role(sk), sk, hc->tx_rtt, r_sample,
428 hc->tx_s, hc->tx_p, hc->tx_x_calc,
429 (unsigned)(hc->tx_x_recv >> 6),
430 (unsigned)(hc->tx_x >> 6));
431
432 /* unschedule no feedback timer */
433 sk_stop_timer(sk, &hc->tx_no_feedback_timer);
434
435 /*
436 * As we have calculated new ipi, delta, t_nom it is possible
437 * that we now can send a packet, so wake up dccp_wait_for_ccid
438 */
439 sk->sk_write_space(sk);
440
441 /*
442 * Update timeout interval for the nofeedback timer. In order to control
443 * rate halving on networks with very low RTTs (<= 1 ms), use per-route
444 * tunable RTAX_RTO_MIN value as the lower bound.
445 */
446 hc->tx_t_rto = max_t(u32, 4 * hc->tx_rtt,
447 USEC_PER_SEC/HZ * tcp_rto_min(sk));
448 /*
449 * Schedule no feedback timer to expire in
450 * max(t_RTO, 2 * s/X) = max(t_RTO, 2 * t_ipi)
451 */
452 t_nfb = max(hc->tx_t_rto, 2 * hc->tx_t_ipi);
453
454 ccid3_pr_debug("%s(%p), Scheduled no feedback timer to "
455 "expire in %lu jiffies (%luus)\n",
456 dccp_role(sk), sk, usecs_to_jiffies(t_nfb), t_nfb);
457
458 sk_reset_timer(sk, &hc->tx_no_feedback_timer,
459 jiffies + usecs_to_jiffies(t_nfb));
460}
461
462static int ccid3_hc_tx_parse_options(struct sock *sk, u8 packet_type,
463 u8 option, u8 *optval, u8 optlen)
464{
465 struct ccid3_hc_tx_sock *hc = ccid3_hc_tx_sk(sk);
466 __be32 opt_val;
467
468 switch (option) {
469 case TFRC_OPT_RECEIVE_RATE:
470 case TFRC_OPT_LOSS_EVENT_RATE:
471 /* Must be ignored on Data packets, cf. RFC 4342 8.3 and 8.5 */
472 if (packet_type == DCCP_PKT_DATA)
473 break;
474 if (unlikely(optlen != 4)) {
475 DCCP_WARN("%s(%p), invalid len %d for %u\n",
476 dccp_role(sk), sk, optlen, option);
477 return -EINVAL;
478 }
479 opt_val = ntohl(get_unaligned((__be32 *)optval));
480
481 if (option == TFRC_OPT_RECEIVE_RATE) {
482 /* Receive Rate is kept in units of 64 bytes/second */
483 hc->tx_x_recv = opt_val;
484 hc->tx_x_recv <<= 6;
485
486 ccid3_pr_debug("%s(%p), RECEIVE_RATE=%u\n",
487 dccp_role(sk), sk, opt_val);
488 } else {
489 /* Update the fixpoint Loss Event Rate fraction */
490 hc->tx_p = tfrc_invert_loss_event_rate(opt_val);
491
492 ccid3_pr_debug("%s(%p), LOSS_EVENT_RATE=%u\n",
493 dccp_role(sk), sk, opt_val);
494 }
495 }
496 return 0;
497}
498
499static int ccid3_hc_tx_init(struct ccid *ccid, struct sock *sk)
500{
501 struct ccid3_hc_tx_sock *hc = ccid_priv(ccid);
502
503 hc->tx_state = TFRC_SSTATE_NO_SENT;
504 hc->tx_hist = NULL;
505 setup_timer(&hc->tx_no_feedback_timer,
506 ccid3_hc_tx_no_feedback_timer, (unsigned long)sk);
507 return 0;
508}
509
510static void ccid3_hc_tx_exit(struct sock *sk)
511{
512 struct ccid3_hc_tx_sock *hc = ccid3_hc_tx_sk(sk);
513
514 sk_stop_timer(sk, &hc->tx_no_feedback_timer);
515 tfrc_tx_hist_purge(&hc->tx_hist);
516}
517
518static void ccid3_hc_tx_get_info(struct sock *sk, struct tcp_info *info)
519{
520 info->tcpi_rto = ccid3_hc_tx_sk(sk)->tx_t_rto;
521 info->tcpi_rtt = ccid3_hc_tx_sk(sk)->tx_rtt;
522}
523
524static int ccid3_hc_tx_getsockopt(struct sock *sk, const int optname, int len,
525 u32 __user *optval, int __user *optlen)
526{
527 const struct ccid3_hc_tx_sock *hc = ccid3_hc_tx_sk(sk);
528 struct tfrc_tx_info tfrc;
529 const void *val;
530
531 switch (optname) {
532 case DCCP_SOCKOPT_CCID_TX_INFO:
533 if (len < sizeof(tfrc))
534 return -EINVAL;
535 tfrc.tfrctx_x = hc->tx_x;
536 tfrc.tfrctx_x_recv = hc->tx_x_recv;
537 tfrc.tfrctx_x_calc = hc->tx_x_calc;
538 tfrc.tfrctx_rtt = hc->tx_rtt;
539 tfrc.tfrctx_p = hc->tx_p;
540 tfrc.tfrctx_rto = hc->tx_t_rto;
541 tfrc.tfrctx_ipi = hc->tx_t_ipi;
542 len = sizeof(tfrc);
543 val = &tfrc;
544 break;
545 default:
546 return -ENOPROTOOPT;
547 }
548
549 if (put_user(len, optlen) || copy_to_user(optval, val, len))
550 return -EFAULT;
551
552 return 0;
553}
554
555/*
556 * Receiver Half-Connection Routines
557 */
558
559/* CCID3 feedback types */
560enum ccid3_fback_type {
561 CCID3_FBACK_NONE = 0,
562 CCID3_FBACK_INITIAL,
563 CCID3_FBACK_PERIODIC,
564 CCID3_FBACK_PARAM_CHANGE
565};
566
567#ifdef CONFIG_IP_DCCP_CCID3_DEBUG
568static const char *ccid3_rx_state_name(enum ccid3_hc_rx_states state)
569{
570 static const char *const ccid3_rx_state_names[] = {
571 [TFRC_RSTATE_NO_DATA] = "NO_DATA",
572 [TFRC_RSTATE_DATA] = "DATA",
573 };
574
575 return ccid3_rx_state_names[state];
576}
577#endif
578
579static void ccid3_hc_rx_set_state(struct sock *sk,
580 enum ccid3_hc_rx_states state)
581{
582 struct ccid3_hc_rx_sock *hc = ccid3_hc_rx_sk(sk);
583 enum ccid3_hc_rx_states oldstate = hc->rx_state;
584
585 ccid3_pr_debug("%s(%p) %-8.8s -> %s\n",
586 dccp_role(sk), sk, ccid3_rx_state_name(oldstate),
587 ccid3_rx_state_name(state));
588 WARN_ON(state == oldstate);
589 hc->rx_state = state;
590}
591
592static void ccid3_hc_rx_send_feedback(struct sock *sk,
593 const struct sk_buff *skb,
594 enum ccid3_fback_type fbtype)
595{
596 struct ccid3_hc_rx_sock *hc = ccid3_hc_rx_sk(sk);
597 struct dccp_sock *dp = dccp_sk(sk);
598 ktime_t now = ktime_get_real();
599 s64 delta = 0;
600
601 switch (fbtype) {
602 case CCID3_FBACK_INITIAL:
603 hc->rx_x_recv = 0;
604 hc->rx_pinv = ~0U; /* see RFC 4342, 8.5 */
605 break;
606 case CCID3_FBACK_PARAM_CHANGE:
607 /*
608 * When parameters change (new loss or p > p_prev), we do not
609 * have a reliable estimate for R_m of [RFC 3448, 6.2] and so
610 * need to reuse the previous value of X_recv. However, when
611 * X_recv was 0 (due to early loss), this would kill X down to
612 * s/t_mbi (i.e. one packet in 64 seconds).
613 * To avoid such drastic reduction, we approximate X_recv as
614 * the number of bytes since last feedback.
615 * This is a safe fallback, since X is bounded above by X_calc.
616 */
617 if (hc->rx_x_recv > 0)
618 break;
619 /* fall through */
620 case CCID3_FBACK_PERIODIC:
621 delta = ktime_us_delta(now, hc->rx_tstamp_last_feedback);
622 if (delta <= 0)
623 DCCP_BUG("delta (%ld) <= 0", (long)delta);
624 else
625 hc->rx_x_recv = scaled_div32(hc->rx_bytes_recv, delta);
626 break;
627 default:
628 return;
629 }
630
631 ccid3_pr_debug("Interval %ldusec, X_recv=%u, 1/p=%u\n", (long)delta,
632 hc->rx_x_recv, hc->rx_pinv);
633
634 hc->rx_tstamp_last_feedback = now;
635 hc->rx_last_counter = dccp_hdr(skb)->dccph_ccval;
636 hc->rx_bytes_recv = 0;
637
638 dp->dccps_hc_rx_insert_options = 1;
639 dccp_send_ack(sk);
640}
641
642static int ccid3_hc_rx_insert_options(struct sock *sk, struct sk_buff *skb)
643{
644 const struct ccid3_hc_rx_sock *hc = ccid3_hc_rx_sk(sk);
645 __be32 x_recv, pinv;
646
647 if (!(sk->sk_state == DCCP_OPEN || sk->sk_state == DCCP_PARTOPEN))
648 return 0;
649
650 if (dccp_packet_without_ack(skb))
651 return 0;
652
653 x_recv = htonl(hc->rx_x_recv);
654 pinv = htonl(hc->rx_pinv);
655
656 if (dccp_insert_option(skb, TFRC_OPT_LOSS_EVENT_RATE,
657 &pinv, sizeof(pinv)) ||
658 dccp_insert_option(skb, TFRC_OPT_RECEIVE_RATE,
659 &x_recv, sizeof(x_recv)))
660 return -1;
661
662 return 0;
663}
664
665/**
666 * ccid3_first_li - Implements [RFC 5348, 6.3.1]
667 *
668 * Determine the length of the first loss interval via inverse lookup.
669 * Assume that X_recv can be computed by the throughput equation
670 * s
671 * X_recv = --------
672 * R * fval
673 * Find some p such that f(p) = fval; return 1/p (scaled).
674 */
675static u32 ccid3_first_li(struct sock *sk)
676{
677 struct ccid3_hc_rx_sock *hc = ccid3_hc_rx_sk(sk);
678 u32 x_recv, p, delta;
679 u64 fval;
680
681 if (hc->rx_rtt == 0) {
682 DCCP_WARN("No RTT estimate available, using fallback RTT\n");
683 hc->rx_rtt = DCCP_FALLBACK_RTT;
684 }
685
686 delta = ktime_to_us(net_timedelta(hc->rx_tstamp_last_feedback));
687 x_recv = scaled_div32(hc->rx_bytes_recv, delta);
688 if (x_recv == 0) { /* would also trigger divide-by-zero */
689 DCCP_WARN("X_recv==0\n");
690 if (hc->rx_x_recv == 0) {
691 DCCP_BUG("stored value of X_recv is zero");
692 return ~0U;
693 }
694 x_recv = hc->rx_x_recv;
695 }
696
697 fval = scaled_div(hc->rx_s, hc->rx_rtt);
698 fval = scaled_div32(fval, x_recv);
699 p = tfrc_calc_x_reverse_lookup(fval);
700
701 ccid3_pr_debug("%s(%p), receive rate=%u bytes/s, implied "
702 "loss rate=%u\n", dccp_role(sk), sk, x_recv, p);
703
704 return p == 0 ? ~0U : scaled_div(1, p);
705}
706
707static void ccid3_hc_rx_packet_recv(struct sock *sk, struct sk_buff *skb)
708{
709 struct ccid3_hc_rx_sock *hc = ccid3_hc_rx_sk(sk);
710 enum ccid3_fback_type do_feedback = CCID3_FBACK_NONE;
711 const u64 ndp = dccp_sk(sk)->dccps_options_received.dccpor_ndp;
712 const bool is_data_packet = dccp_data_packet(skb);
713
714 if (unlikely(hc->rx_state == TFRC_RSTATE_NO_DATA)) {
715 if (is_data_packet) {
716 const u32 payload = skb->len - dccp_hdr(skb)->dccph_doff * 4;
717 do_feedback = CCID3_FBACK_INITIAL;
718 ccid3_hc_rx_set_state(sk, TFRC_RSTATE_DATA);
719 hc->rx_s = payload;
720 /*
721 * Not necessary to update rx_bytes_recv here,
722 * since X_recv = 0 for the first feedback packet (cf.
723 * RFC 3448, 6.3) -- gerrit
724 */
725 }
726 goto update_records;
727 }
728
729 if (tfrc_rx_hist_duplicate(&hc->rx_hist, skb))
730 return; /* done receiving */
731
732 if (is_data_packet) {
733 const u32 payload = skb->len - dccp_hdr(skb)->dccph_doff * 4;
734 /*
735 * Update moving-average of s and the sum of received payload bytes
736 */
737 hc->rx_s = tfrc_ewma(hc->rx_s, payload, 9);
738 hc->rx_bytes_recv += payload;
739 }
740
741 /*
742 * Perform loss detection and handle pending losses
743 */
744 if (tfrc_rx_handle_loss(&hc->rx_hist, &hc->rx_li_hist,
745 skb, ndp, ccid3_first_li, sk)) {
746 do_feedback = CCID3_FBACK_PARAM_CHANGE;
747 goto done_receiving;
748 }
749
750 if (tfrc_rx_hist_loss_pending(&hc->rx_hist))
751 return; /* done receiving */
752
753 /*
754 * Handle data packets: RTT sampling and monitoring p
755 */
756 if (unlikely(!is_data_packet))
757 goto update_records;
758
759 if (!tfrc_lh_is_initialised(&hc->rx_li_hist)) {
760 const u32 sample = tfrc_rx_hist_sample_rtt(&hc->rx_hist, skb);
761 /*
762 * Empty loss history: no loss so far, hence p stays 0.
763 * Sample RTT values, since an RTT estimate is required for the
764 * computation of p when the first loss occurs; RFC 3448, 6.3.1.
765 */
766 if (sample != 0)
767 hc->rx_rtt = tfrc_ewma(hc->rx_rtt, sample, 9);
768
769 } else if (tfrc_lh_update_i_mean(&hc->rx_li_hist, skb)) {
770 /*
771 * Step (3) of [RFC 3448, 6.1]: Recompute I_mean and, if I_mean
772 * has decreased (resp. p has increased), send feedback now.
773 */
774 do_feedback = CCID3_FBACK_PARAM_CHANGE;
775 }
776
777 /*
778 * Check if the periodic once-per-RTT feedback is due; RFC 4342, 10.3
779 */
780 if (SUB16(dccp_hdr(skb)->dccph_ccval, hc->rx_last_counter) > 3)
781 do_feedback = CCID3_FBACK_PERIODIC;
782
783update_records:
784 tfrc_rx_hist_add_packet(&hc->rx_hist, skb, ndp);
785
786done_receiving:
787 if (do_feedback)
788 ccid3_hc_rx_send_feedback(sk, skb, do_feedback);
789}
790
791static int ccid3_hc_rx_init(struct ccid *ccid, struct sock *sk)
792{
793 struct ccid3_hc_rx_sock *hc = ccid_priv(ccid);
794
795 hc->rx_state = TFRC_RSTATE_NO_DATA;
796 tfrc_lh_init(&hc->rx_li_hist);
797 return tfrc_rx_hist_alloc(&hc->rx_hist);
798}
799
800static void ccid3_hc_rx_exit(struct sock *sk)
801{
802 struct ccid3_hc_rx_sock *hc = ccid3_hc_rx_sk(sk);
803
804 tfrc_rx_hist_purge(&hc->rx_hist);
805 tfrc_lh_cleanup(&hc->rx_li_hist);
806}
807
808static void ccid3_hc_rx_get_info(struct sock *sk, struct tcp_info *info)
809{
810 info->tcpi_ca_state = ccid3_hc_rx_sk(sk)->rx_state;
811 info->tcpi_options |= TCPI_OPT_TIMESTAMPS;
812 info->tcpi_rcv_rtt = ccid3_hc_rx_sk(sk)->rx_rtt;
813}
814
815static int ccid3_hc_rx_getsockopt(struct sock *sk, const int optname, int len,
816 u32 __user *optval, int __user *optlen)
817{
818 const struct ccid3_hc_rx_sock *hc = ccid3_hc_rx_sk(sk);
819 struct tfrc_rx_info rx_info;
820 const void *val;
821
822 switch (optname) {
823 case DCCP_SOCKOPT_CCID_RX_INFO:
824 if (len < sizeof(rx_info))
825 return -EINVAL;
826 rx_info.tfrcrx_x_recv = hc->rx_x_recv;
827 rx_info.tfrcrx_rtt = hc->rx_rtt;
828 rx_info.tfrcrx_p = tfrc_invert_loss_event_rate(hc->rx_pinv);
829 len = sizeof(rx_info);
830 val = &rx_info;
831 break;
832 default:
833 return -ENOPROTOOPT;
834 }
835
836 if (put_user(len, optlen) || copy_to_user(optval, val, len))
837 return -EFAULT;
838
839 return 0;
840}
841
842struct ccid_operations ccid3_ops = {
843 .ccid_id = DCCPC_CCID3,
844 .ccid_name = "TCP-Friendly Rate Control",
845 .ccid_hc_tx_obj_size = sizeof(struct ccid3_hc_tx_sock),
846 .ccid_hc_tx_init = ccid3_hc_tx_init,
847 .ccid_hc_tx_exit = ccid3_hc_tx_exit,
848 .ccid_hc_tx_send_packet = ccid3_hc_tx_send_packet,
849 .ccid_hc_tx_packet_sent = ccid3_hc_tx_packet_sent,
850 .ccid_hc_tx_packet_recv = ccid3_hc_tx_packet_recv,
851 .ccid_hc_tx_parse_options = ccid3_hc_tx_parse_options,
852 .ccid_hc_rx_obj_size = sizeof(struct ccid3_hc_rx_sock),
853 .ccid_hc_rx_init = ccid3_hc_rx_init,
854 .ccid_hc_rx_exit = ccid3_hc_rx_exit,
855 .ccid_hc_rx_insert_options = ccid3_hc_rx_insert_options,
856 .ccid_hc_rx_packet_recv = ccid3_hc_rx_packet_recv,
857 .ccid_hc_rx_get_info = ccid3_hc_rx_get_info,
858 .ccid_hc_tx_get_info = ccid3_hc_tx_get_info,
859 .ccid_hc_rx_getsockopt = ccid3_hc_rx_getsockopt,
860 .ccid_hc_tx_getsockopt = ccid3_hc_tx_getsockopt,
861};
862
863#ifdef CONFIG_IP_DCCP_CCID3_DEBUG
864module_param(ccid3_debug, bool, 0644);
865MODULE_PARM_DESC(ccid3_debug, "Enable CCID-3 debug messages");
866#endif
1/*
2 * Copyright (c) 2007 The University of Aberdeen, Scotland, UK
3 * Copyright (c) 2005-7 The University of Waikato, Hamilton, New Zealand.
4 * Copyright (c) 2005-7 Ian McDonald <ian.mcdonald@jandi.co.nz>
5 *
6 * An implementation of the DCCP protocol
7 *
8 * This code has been developed by the University of Waikato WAND
9 * research group. For further information please see http://www.wand.net.nz/
10 *
11 * This code also uses code from Lulea University, rereleased as GPL by its
12 * authors:
13 * Copyright (c) 2003 Nils-Erik Mattsson, Joacim Haggmark, Magnus Erixzon
14 *
15 * Changes to meet Linux coding standards, to make it meet latest ccid3 draft
16 * and to make it work as a loadable module in the DCCP stack written by
17 * Arnaldo Carvalho de Melo <acme@conectiva.com.br>.
18 *
19 * Copyright (c) 2005 Arnaldo Carvalho de Melo <acme@conectiva.com.br>
20 *
21 * This program is free software; you can redistribute it and/or modify
22 * it under the terms of the GNU General Public License as published by
23 * the Free Software Foundation; either version 2 of the License, or
24 * (at your option) any later version.
25 *
26 * This program is distributed in the hope that it will be useful,
27 * but WITHOUT ANY WARRANTY; without even the implied warranty of
28 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
29 * GNU General Public License for more details.
30 *
31 * You should have received a copy of the GNU General Public License
32 * along with this program; if not, write to the Free Software
33 * Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
34 */
35#include "../dccp.h"
36#include "ccid3.h"
37
38#include <asm/unaligned.h>
39
40#ifdef CONFIG_IP_DCCP_CCID3_DEBUG
41static bool ccid3_debug;
42#define ccid3_pr_debug(format, a...) DCCP_PR_DEBUG(ccid3_debug, format, ##a)
43#else
44#define ccid3_pr_debug(format, a...)
45#endif
46
47/*
48 * Transmitter Half-Connection Routines
49 */
50#ifdef CONFIG_IP_DCCP_CCID3_DEBUG
51static const char *ccid3_tx_state_name(enum ccid3_hc_tx_states state)
52{
53 static const char *const ccid3_state_names[] = {
54 [TFRC_SSTATE_NO_SENT] = "NO_SENT",
55 [TFRC_SSTATE_NO_FBACK] = "NO_FBACK",
56 [TFRC_SSTATE_FBACK] = "FBACK",
57 };
58
59 return ccid3_state_names[state];
60}
61#endif
62
63static void ccid3_hc_tx_set_state(struct sock *sk,
64 enum ccid3_hc_tx_states state)
65{
66 struct ccid3_hc_tx_sock *hc = ccid3_hc_tx_sk(sk);
67 enum ccid3_hc_tx_states oldstate = hc->tx_state;
68
69 ccid3_pr_debug("%s(%p) %-8.8s -> %s\n",
70 dccp_role(sk), sk, ccid3_tx_state_name(oldstate),
71 ccid3_tx_state_name(state));
72 WARN_ON(state == oldstate);
73 hc->tx_state = state;
74}
75
76/*
77 * Compute the initial sending rate X_init in the manner of RFC 3390:
78 *
79 * X_init = min(4 * s, max(2 * s, 4380 bytes)) / RTT
80 *
81 * Note that RFC 3390 uses MSS, RFC 4342 refers to RFC 3390, and rfc3448bis
82 * (rev-02) clarifies the use of RFC 3390 with regard to the above formula.
83 * For consistency with other parts of the code, X_init is scaled by 2^6.
84 */
85static inline u64 rfc3390_initial_rate(struct sock *sk)
86{
87 const struct ccid3_hc_tx_sock *hc = ccid3_hc_tx_sk(sk);
88 const __u32 w_init = clamp_t(__u32, 4380U, 2 * hc->tx_s, 4 * hc->tx_s);
89
90 return scaled_div(w_init << 6, hc->tx_rtt);
91}
92
93/**
94 * ccid3_update_send_interval - Calculate new t_ipi = s / X_inst
95 * This respects the granularity of X_inst (64 * bytes/second).
96 */
97static void ccid3_update_send_interval(struct ccid3_hc_tx_sock *hc)
98{
99 hc->tx_t_ipi = scaled_div32(((u64)hc->tx_s) << 6, hc->tx_x);
100
101 DCCP_BUG_ON(hc->tx_t_ipi == 0);
102 ccid3_pr_debug("t_ipi=%u, s=%u, X=%u\n", hc->tx_t_ipi,
103 hc->tx_s, (unsigned int)(hc->tx_x >> 6));
104}
105
106static u32 ccid3_hc_tx_idle_rtt(struct ccid3_hc_tx_sock *hc, ktime_t now)
107{
108 u32 delta = ktime_us_delta(now, hc->tx_t_last_win_count);
109
110 return delta / hc->tx_rtt;
111}
112
113/**
114 * ccid3_hc_tx_update_x - Update allowed sending rate X
115 * @stamp: most recent time if available - can be left NULL.
116 *
117 * This function tracks draft rfc3448bis, check there for latest details.
118 *
119 * Note: X and X_recv are both stored in units of 64 * bytes/second, to support
120 * fine-grained resolution of sending rates. This requires scaling by 2^6
121 * throughout the code. Only X_calc is unscaled (in bytes/second).
122 *
123 */
124static void ccid3_hc_tx_update_x(struct sock *sk, ktime_t *stamp)
125{
126 struct ccid3_hc_tx_sock *hc = ccid3_hc_tx_sk(sk);
127 __u64 min_rate = 2 * hc->tx_x_recv;
128 const __u64 old_x = hc->tx_x;
129 ktime_t now = stamp ? *stamp : ktime_get_real();
130
131 /*
132 * Handle IDLE periods: do not reduce below RFC3390 initial sending rate
133 * when idling [RFC 4342, 5.1]. Definition of idling is from rfc3448bis:
134 * a sender is idle if it has not sent anything over a 2-RTT-period.
135 * For consistency with X and X_recv, min_rate is also scaled by 2^6.
136 */
137 if (ccid3_hc_tx_idle_rtt(hc, now) >= 2) {
138 min_rate = rfc3390_initial_rate(sk);
139 min_rate = max(min_rate, 2 * hc->tx_x_recv);
140 }
141
142 if (hc->tx_p > 0) {
143
144 hc->tx_x = min(((__u64)hc->tx_x_calc) << 6, min_rate);
145 hc->tx_x = max(hc->tx_x, (((__u64)hc->tx_s) << 6) / TFRC_T_MBI);
146
147 } else if (ktime_us_delta(now, hc->tx_t_ld) - (s64)hc->tx_rtt >= 0) {
148
149 hc->tx_x = min(2 * hc->tx_x, min_rate);
150 hc->tx_x = max(hc->tx_x,
151 scaled_div(((__u64)hc->tx_s) << 6, hc->tx_rtt));
152 hc->tx_t_ld = now;
153 }
154
155 if (hc->tx_x != old_x) {
156 ccid3_pr_debug("X_prev=%u, X_now=%u, X_calc=%u, "
157 "X_recv=%u\n", (unsigned int)(old_x >> 6),
158 (unsigned int)(hc->tx_x >> 6), hc->tx_x_calc,
159 (unsigned int)(hc->tx_x_recv >> 6));
160
161 ccid3_update_send_interval(hc);
162 }
163}
164
165/**
166 * ccid3_hc_tx_update_s - Track the mean packet size `s'
167 * @len: DCCP packet payload size in bytes
168 *
169 * cf. RFC 4342, 5.3 and RFC 3448, 4.1
170 */
171static inline void ccid3_hc_tx_update_s(struct ccid3_hc_tx_sock *hc, int len)
172{
173 const u16 old_s = hc->tx_s;
174
175 hc->tx_s = tfrc_ewma(hc->tx_s, len, 9);
176
177 if (hc->tx_s != old_s)
178 ccid3_update_send_interval(hc);
179}
180
181/*
182 * Update Window Counter using the algorithm from [RFC 4342, 8.1].
183 * As elsewhere, RTT > 0 is assumed by using dccp_sample_rtt().
184 */
185static inline void ccid3_hc_tx_update_win_count(struct ccid3_hc_tx_sock *hc,
186 ktime_t now)
187{
188 u32 delta = ktime_us_delta(now, hc->tx_t_last_win_count),
189 quarter_rtts = (4 * delta) / hc->tx_rtt;
190
191 if (quarter_rtts > 0) {
192 hc->tx_t_last_win_count = now;
193 hc->tx_last_win_count += min(quarter_rtts, 5U);
194 hc->tx_last_win_count &= 0xF; /* mod 16 */
195 }
196}
197
198static void ccid3_hc_tx_no_feedback_timer(struct timer_list *t)
199{
200 struct ccid3_hc_tx_sock *hc = from_timer(hc, t, tx_no_feedback_timer);
201 struct sock *sk = hc->sk;
202 unsigned long t_nfb = USEC_PER_SEC / 5;
203
204 bh_lock_sock(sk);
205 if (sock_owned_by_user(sk)) {
206 /* Try again later. */
207 /* XXX: set some sensible MIB */
208 goto restart_timer;
209 }
210
211 ccid3_pr_debug("%s(%p, state=%s) - entry\n", dccp_role(sk), sk,
212 ccid3_tx_state_name(hc->tx_state));
213
214 /* Ignore and do not restart after leaving the established state */
215 if ((1 << sk->sk_state) & ~(DCCPF_OPEN | DCCPF_PARTOPEN))
216 goto out;
217
218 /* Reset feedback state to "no feedback received" */
219 if (hc->tx_state == TFRC_SSTATE_FBACK)
220 ccid3_hc_tx_set_state(sk, TFRC_SSTATE_NO_FBACK);
221
222 /*
223 * Determine new allowed sending rate X as per draft rfc3448bis-00, 4.4
224 * RTO is 0 if and only if no feedback has been received yet.
225 */
226 if (hc->tx_t_rto == 0 || hc->tx_p == 0) {
227
228 /* halve send rate directly */
229 hc->tx_x = max(hc->tx_x / 2,
230 (((__u64)hc->tx_s) << 6) / TFRC_T_MBI);
231 ccid3_update_send_interval(hc);
232 } else {
233 /*
234 * Modify the cached value of X_recv
235 *
236 * If (X_calc > 2 * X_recv)
237 * X_recv = max(X_recv / 2, s / (2 * t_mbi));
238 * Else
239 * X_recv = X_calc / 4;
240 *
241 * Note that X_recv is scaled by 2^6 while X_calc is not
242 */
243 if (hc->tx_x_calc > (hc->tx_x_recv >> 5))
244 hc->tx_x_recv =
245 max(hc->tx_x_recv / 2,
246 (((__u64)hc->tx_s) << 6) / (2*TFRC_T_MBI));
247 else {
248 hc->tx_x_recv = hc->tx_x_calc;
249 hc->tx_x_recv <<= 4;
250 }
251 ccid3_hc_tx_update_x(sk, NULL);
252 }
253 ccid3_pr_debug("Reduced X to %llu/64 bytes/sec\n",
254 (unsigned long long)hc->tx_x);
255
256 /*
257 * Set new timeout for the nofeedback timer.
258 * See comments in packet_recv() regarding the value of t_RTO.
259 */
260 if (unlikely(hc->tx_t_rto == 0)) /* no feedback received yet */
261 t_nfb = TFRC_INITIAL_TIMEOUT;
262 else
263 t_nfb = max(hc->tx_t_rto, 2 * hc->tx_t_ipi);
264
265restart_timer:
266 sk_reset_timer(sk, &hc->tx_no_feedback_timer,
267 jiffies + usecs_to_jiffies(t_nfb));
268out:
269 bh_unlock_sock(sk);
270 sock_put(sk);
271}
272
273/**
274 * ccid3_hc_tx_send_packet - Delay-based dequeueing of TX packets
275 * @skb: next packet candidate to send on @sk
276 *
277 * This function uses the convention of ccid_packet_dequeue_eval() and
278 * returns a millisecond-delay value between 0 and t_mbi = 64000 msec.
279 */
280static int ccid3_hc_tx_send_packet(struct sock *sk, struct sk_buff *skb)
281{
282 struct dccp_sock *dp = dccp_sk(sk);
283 struct ccid3_hc_tx_sock *hc = ccid3_hc_tx_sk(sk);
284 ktime_t now = ktime_get_real();
285 s64 delay;
286
287 /*
288 * This function is called only for Data and DataAck packets. Sending
289 * zero-sized Data(Ack)s is theoretically possible, but for congestion
290 * control this case is pathological - ignore it.
291 */
292 if (unlikely(skb->len == 0))
293 return -EBADMSG;
294
295 if (hc->tx_state == TFRC_SSTATE_NO_SENT) {
296 sk_reset_timer(sk, &hc->tx_no_feedback_timer, (jiffies +
297 usecs_to_jiffies(TFRC_INITIAL_TIMEOUT)));
298 hc->tx_last_win_count = 0;
299 hc->tx_t_last_win_count = now;
300
301 /* Set t_0 for initial packet */
302 hc->tx_t_nom = now;
303
304 hc->tx_s = skb->len;
305
306 /*
307 * Use initial RTT sample when available: recommended by erratum
308 * to RFC 4342. This implements the initialisation procedure of
309 * draft rfc3448bis, section 4.2. Remember, X is scaled by 2^6.
310 */
311 if (dp->dccps_syn_rtt) {
312 ccid3_pr_debug("SYN RTT = %uus\n", dp->dccps_syn_rtt);
313 hc->tx_rtt = dp->dccps_syn_rtt;
314 hc->tx_x = rfc3390_initial_rate(sk);
315 hc->tx_t_ld = now;
316 } else {
317 /*
318 * Sender does not have RTT sample:
319 * - set fallback RTT (RFC 4340, 3.4) since a RTT value
320 * is needed in several parts (e.g. window counter);
321 * - set sending rate X_pps = 1pps as per RFC 3448, 4.2.
322 */
323 hc->tx_rtt = DCCP_FALLBACK_RTT;
324 hc->tx_x = hc->tx_s;
325 hc->tx_x <<= 6;
326 }
327 ccid3_update_send_interval(hc);
328
329 ccid3_hc_tx_set_state(sk, TFRC_SSTATE_NO_FBACK);
330
331 } else {
332 delay = ktime_us_delta(hc->tx_t_nom, now);
333 ccid3_pr_debug("delay=%ld\n", (long)delay);
334 /*
335 * Scheduling of packet transmissions (RFC 5348, 8.3)
336 *
337 * if (t_now > t_nom - delta)
338 * // send the packet now
339 * else
340 * // send the packet in (t_nom - t_now) milliseconds.
341 */
342 if (delay >= TFRC_T_DELTA)
343 return (u32)delay / USEC_PER_MSEC;
344
345 ccid3_hc_tx_update_win_count(hc, now);
346 }
347
348 /* prepare to send now (add options etc.) */
349 dp->dccps_hc_tx_insert_options = 1;
350 DCCP_SKB_CB(skb)->dccpd_ccval = hc->tx_last_win_count;
351
352 /* set the nominal send time for the next following packet */
353 hc->tx_t_nom = ktime_add_us(hc->tx_t_nom, hc->tx_t_ipi);
354 return CCID_PACKET_SEND_AT_ONCE;
355}
356
357static void ccid3_hc_tx_packet_sent(struct sock *sk, unsigned int len)
358{
359 struct ccid3_hc_tx_sock *hc = ccid3_hc_tx_sk(sk);
360
361 ccid3_hc_tx_update_s(hc, len);
362
363 if (tfrc_tx_hist_add(&hc->tx_hist, dccp_sk(sk)->dccps_gss))
364 DCCP_CRIT("packet history - out of memory!");
365}
366
367static void ccid3_hc_tx_packet_recv(struct sock *sk, struct sk_buff *skb)
368{
369 struct ccid3_hc_tx_sock *hc = ccid3_hc_tx_sk(sk);
370 struct tfrc_tx_hist_entry *acked;
371 ktime_t now;
372 unsigned long t_nfb;
373 u32 r_sample;
374
375 /* we are only interested in ACKs */
376 if (!(DCCP_SKB_CB(skb)->dccpd_type == DCCP_PKT_ACK ||
377 DCCP_SKB_CB(skb)->dccpd_type == DCCP_PKT_DATAACK))
378 return;
379 /*
380 * Locate the acknowledged packet in the TX history.
381 *
382 * Returning "entry not found" here can for instance happen when
383 * - the host has not sent out anything (e.g. a passive server),
384 * - the Ack is outdated (packet with higher Ack number was received),
385 * - it is a bogus Ack (for a packet not sent on this connection).
386 */
387 acked = tfrc_tx_hist_find_entry(hc->tx_hist, dccp_hdr_ack_seq(skb));
388 if (acked == NULL)
389 return;
390 /* For the sake of RTT sampling, ignore/remove all older entries */
391 tfrc_tx_hist_purge(&acked->next);
392
393 /* Update the moving average for the RTT estimate (RFC 3448, 4.3) */
394 now = ktime_get_real();
395 r_sample = dccp_sample_rtt(sk, ktime_us_delta(now, acked->stamp));
396 hc->tx_rtt = tfrc_ewma(hc->tx_rtt, r_sample, 9);
397
398 /*
399 * Update allowed sending rate X as per draft rfc3448bis-00, 4.2/3
400 */
401 if (hc->tx_state == TFRC_SSTATE_NO_FBACK) {
402 ccid3_hc_tx_set_state(sk, TFRC_SSTATE_FBACK);
403
404 if (hc->tx_t_rto == 0) {
405 /*
406 * Initial feedback packet: Larger Initial Windows (4.2)
407 */
408 hc->tx_x = rfc3390_initial_rate(sk);
409 hc->tx_t_ld = now;
410
411 ccid3_update_send_interval(hc);
412
413 goto done_computing_x;
414 } else if (hc->tx_p == 0) {
415 /*
416 * First feedback after nofeedback timer expiry (4.3)
417 */
418 goto done_computing_x;
419 }
420 }
421
422 /* Update sending rate (step 4 of [RFC 3448, 4.3]) */
423 if (hc->tx_p > 0)
424 hc->tx_x_calc = tfrc_calc_x(hc->tx_s, hc->tx_rtt, hc->tx_p);
425 ccid3_hc_tx_update_x(sk, &now);
426
427done_computing_x:
428 ccid3_pr_debug("%s(%p), RTT=%uus (sample=%uus), s=%u, "
429 "p=%u, X_calc=%u, X_recv=%u, X=%u\n",
430 dccp_role(sk), sk, hc->tx_rtt, r_sample,
431 hc->tx_s, hc->tx_p, hc->tx_x_calc,
432 (unsigned int)(hc->tx_x_recv >> 6),
433 (unsigned int)(hc->tx_x >> 6));
434
435 /* unschedule no feedback timer */
436 sk_stop_timer(sk, &hc->tx_no_feedback_timer);
437
438 /*
439 * As we have calculated new ipi, delta, t_nom it is possible
440 * that we now can send a packet, so wake up dccp_wait_for_ccid
441 */
442 sk->sk_write_space(sk);
443
444 /*
445 * Update timeout interval for the nofeedback timer. In order to control
446 * rate halving on networks with very low RTTs (<= 1 ms), use per-route
447 * tunable RTAX_RTO_MIN value as the lower bound.
448 */
449 hc->tx_t_rto = max_t(u32, 4 * hc->tx_rtt,
450 USEC_PER_SEC/HZ * tcp_rto_min(sk));
451 /*
452 * Schedule no feedback timer to expire in
453 * max(t_RTO, 2 * s/X) = max(t_RTO, 2 * t_ipi)
454 */
455 t_nfb = max(hc->tx_t_rto, 2 * hc->tx_t_ipi);
456
457 ccid3_pr_debug("%s(%p), Scheduled no feedback timer to "
458 "expire in %lu jiffies (%luus)\n",
459 dccp_role(sk), sk, usecs_to_jiffies(t_nfb), t_nfb);
460
461 sk_reset_timer(sk, &hc->tx_no_feedback_timer,
462 jiffies + usecs_to_jiffies(t_nfb));
463}
464
465static int ccid3_hc_tx_parse_options(struct sock *sk, u8 packet_type,
466 u8 option, u8 *optval, u8 optlen)
467{
468 struct ccid3_hc_tx_sock *hc = ccid3_hc_tx_sk(sk);
469 __be32 opt_val;
470
471 switch (option) {
472 case TFRC_OPT_RECEIVE_RATE:
473 case TFRC_OPT_LOSS_EVENT_RATE:
474 /* Must be ignored on Data packets, cf. RFC 4342 8.3 and 8.5 */
475 if (packet_type == DCCP_PKT_DATA)
476 break;
477 if (unlikely(optlen != 4)) {
478 DCCP_WARN("%s(%p), invalid len %d for %u\n",
479 dccp_role(sk), sk, optlen, option);
480 return -EINVAL;
481 }
482 opt_val = ntohl(get_unaligned((__be32 *)optval));
483
484 if (option == TFRC_OPT_RECEIVE_RATE) {
485 /* Receive Rate is kept in units of 64 bytes/second */
486 hc->tx_x_recv = opt_val;
487 hc->tx_x_recv <<= 6;
488
489 ccid3_pr_debug("%s(%p), RECEIVE_RATE=%u\n",
490 dccp_role(sk), sk, opt_val);
491 } else {
492 /* Update the fixpoint Loss Event Rate fraction */
493 hc->tx_p = tfrc_invert_loss_event_rate(opt_val);
494
495 ccid3_pr_debug("%s(%p), LOSS_EVENT_RATE=%u\n",
496 dccp_role(sk), sk, opt_val);
497 }
498 }
499 return 0;
500}
501
502static int ccid3_hc_tx_init(struct ccid *ccid, struct sock *sk)
503{
504 struct ccid3_hc_tx_sock *hc = ccid_priv(ccid);
505
506 hc->tx_state = TFRC_SSTATE_NO_SENT;
507 hc->tx_hist = NULL;
508 hc->sk = sk;
509 timer_setup(&hc->tx_no_feedback_timer,
510 ccid3_hc_tx_no_feedback_timer, 0);
511 return 0;
512}
513
514static void ccid3_hc_tx_exit(struct sock *sk)
515{
516 struct ccid3_hc_tx_sock *hc = ccid3_hc_tx_sk(sk);
517
518 sk_stop_timer(sk, &hc->tx_no_feedback_timer);
519 tfrc_tx_hist_purge(&hc->tx_hist);
520}
521
522static void ccid3_hc_tx_get_info(struct sock *sk, struct tcp_info *info)
523{
524 info->tcpi_rto = ccid3_hc_tx_sk(sk)->tx_t_rto;
525 info->tcpi_rtt = ccid3_hc_tx_sk(sk)->tx_rtt;
526}
527
528static int ccid3_hc_tx_getsockopt(struct sock *sk, const int optname, int len,
529 u32 __user *optval, int __user *optlen)
530{
531 const struct ccid3_hc_tx_sock *hc = ccid3_hc_tx_sk(sk);
532 struct tfrc_tx_info tfrc;
533 const void *val;
534
535 switch (optname) {
536 case DCCP_SOCKOPT_CCID_TX_INFO:
537 if (len < sizeof(tfrc))
538 return -EINVAL;
539 memset(&tfrc, 0, sizeof(tfrc));
540 tfrc.tfrctx_x = hc->tx_x;
541 tfrc.tfrctx_x_recv = hc->tx_x_recv;
542 tfrc.tfrctx_x_calc = hc->tx_x_calc;
543 tfrc.tfrctx_rtt = hc->tx_rtt;
544 tfrc.tfrctx_p = hc->tx_p;
545 tfrc.tfrctx_rto = hc->tx_t_rto;
546 tfrc.tfrctx_ipi = hc->tx_t_ipi;
547 len = sizeof(tfrc);
548 val = &tfrc;
549 break;
550 default:
551 return -ENOPROTOOPT;
552 }
553
554 if (put_user(len, optlen) || copy_to_user(optval, val, len))
555 return -EFAULT;
556
557 return 0;
558}
559
560/*
561 * Receiver Half-Connection Routines
562 */
563
564/* CCID3 feedback types */
565enum ccid3_fback_type {
566 CCID3_FBACK_NONE = 0,
567 CCID3_FBACK_INITIAL,
568 CCID3_FBACK_PERIODIC,
569 CCID3_FBACK_PARAM_CHANGE
570};
571
572#ifdef CONFIG_IP_DCCP_CCID3_DEBUG
573static const char *ccid3_rx_state_name(enum ccid3_hc_rx_states state)
574{
575 static const char *const ccid3_rx_state_names[] = {
576 [TFRC_RSTATE_NO_DATA] = "NO_DATA",
577 [TFRC_RSTATE_DATA] = "DATA",
578 };
579
580 return ccid3_rx_state_names[state];
581}
582#endif
583
584static void ccid3_hc_rx_set_state(struct sock *sk,
585 enum ccid3_hc_rx_states state)
586{
587 struct ccid3_hc_rx_sock *hc = ccid3_hc_rx_sk(sk);
588 enum ccid3_hc_rx_states oldstate = hc->rx_state;
589
590 ccid3_pr_debug("%s(%p) %-8.8s -> %s\n",
591 dccp_role(sk), sk, ccid3_rx_state_name(oldstate),
592 ccid3_rx_state_name(state));
593 WARN_ON(state == oldstate);
594 hc->rx_state = state;
595}
596
597static void ccid3_hc_rx_send_feedback(struct sock *sk,
598 const struct sk_buff *skb,
599 enum ccid3_fback_type fbtype)
600{
601 struct ccid3_hc_rx_sock *hc = ccid3_hc_rx_sk(sk);
602 struct dccp_sock *dp = dccp_sk(sk);
603 ktime_t now = ktime_get_real();
604 s64 delta = 0;
605
606 switch (fbtype) {
607 case CCID3_FBACK_INITIAL:
608 hc->rx_x_recv = 0;
609 hc->rx_pinv = ~0U; /* see RFC 4342, 8.5 */
610 break;
611 case CCID3_FBACK_PARAM_CHANGE:
612 /*
613 * When parameters change (new loss or p > p_prev), we do not
614 * have a reliable estimate for R_m of [RFC 3448, 6.2] and so
615 * need to reuse the previous value of X_recv. However, when
616 * X_recv was 0 (due to early loss), this would kill X down to
617 * s/t_mbi (i.e. one packet in 64 seconds).
618 * To avoid such drastic reduction, we approximate X_recv as
619 * the number of bytes since last feedback.
620 * This is a safe fallback, since X is bounded above by X_calc.
621 */
622 if (hc->rx_x_recv > 0)
623 break;
624 /* fall through */
625 case CCID3_FBACK_PERIODIC:
626 delta = ktime_us_delta(now, hc->rx_tstamp_last_feedback);
627 if (delta <= 0)
628 DCCP_BUG("delta (%ld) <= 0", (long)delta);
629 else
630 hc->rx_x_recv = scaled_div32(hc->rx_bytes_recv, delta);
631 break;
632 default:
633 return;
634 }
635
636 ccid3_pr_debug("Interval %ldusec, X_recv=%u, 1/p=%u\n", (long)delta,
637 hc->rx_x_recv, hc->rx_pinv);
638
639 hc->rx_tstamp_last_feedback = now;
640 hc->rx_last_counter = dccp_hdr(skb)->dccph_ccval;
641 hc->rx_bytes_recv = 0;
642
643 dp->dccps_hc_rx_insert_options = 1;
644 dccp_send_ack(sk);
645}
646
647static int ccid3_hc_rx_insert_options(struct sock *sk, struct sk_buff *skb)
648{
649 const struct ccid3_hc_rx_sock *hc = ccid3_hc_rx_sk(sk);
650 __be32 x_recv, pinv;
651
652 if (!(sk->sk_state == DCCP_OPEN || sk->sk_state == DCCP_PARTOPEN))
653 return 0;
654
655 if (dccp_packet_without_ack(skb))
656 return 0;
657
658 x_recv = htonl(hc->rx_x_recv);
659 pinv = htonl(hc->rx_pinv);
660
661 if (dccp_insert_option(skb, TFRC_OPT_LOSS_EVENT_RATE,
662 &pinv, sizeof(pinv)) ||
663 dccp_insert_option(skb, TFRC_OPT_RECEIVE_RATE,
664 &x_recv, sizeof(x_recv)))
665 return -1;
666
667 return 0;
668}
669
670/**
671 * ccid3_first_li - Implements [RFC 5348, 6.3.1]
672 *
673 * Determine the length of the first loss interval via inverse lookup.
674 * Assume that X_recv can be computed by the throughput equation
675 * s
676 * X_recv = --------
677 * R * fval
678 * Find some p such that f(p) = fval; return 1/p (scaled).
679 */
680static u32 ccid3_first_li(struct sock *sk)
681{
682 struct ccid3_hc_rx_sock *hc = ccid3_hc_rx_sk(sk);
683 u32 x_recv, p, delta;
684 u64 fval;
685
686 if (hc->rx_rtt == 0) {
687 DCCP_WARN("No RTT estimate available, using fallback RTT\n");
688 hc->rx_rtt = DCCP_FALLBACK_RTT;
689 }
690
691 delta = ktime_to_us(net_timedelta(hc->rx_tstamp_last_feedback));
692 x_recv = scaled_div32(hc->rx_bytes_recv, delta);
693 if (x_recv == 0) { /* would also trigger divide-by-zero */
694 DCCP_WARN("X_recv==0\n");
695 if (hc->rx_x_recv == 0) {
696 DCCP_BUG("stored value of X_recv is zero");
697 return ~0U;
698 }
699 x_recv = hc->rx_x_recv;
700 }
701
702 fval = scaled_div(hc->rx_s, hc->rx_rtt);
703 fval = scaled_div32(fval, x_recv);
704 p = tfrc_calc_x_reverse_lookup(fval);
705
706 ccid3_pr_debug("%s(%p), receive rate=%u bytes/s, implied "
707 "loss rate=%u\n", dccp_role(sk), sk, x_recv, p);
708
709 return p == 0 ? ~0U : scaled_div(1, p);
710}
711
712static void ccid3_hc_rx_packet_recv(struct sock *sk, struct sk_buff *skb)
713{
714 struct ccid3_hc_rx_sock *hc = ccid3_hc_rx_sk(sk);
715 enum ccid3_fback_type do_feedback = CCID3_FBACK_NONE;
716 const u64 ndp = dccp_sk(sk)->dccps_options_received.dccpor_ndp;
717 const bool is_data_packet = dccp_data_packet(skb);
718
719 if (unlikely(hc->rx_state == TFRC_RSTATE_NO_DATA)) {
720 if (is_data_packet) {
721 const u32 payload = skb->len - dccp_hdr(skb)->dccph_doff * 4;
722 do_feedback = CCID3_FBACK_INITIAL;
723 ccid3_hc_rx_set_state(sk, TFRC_RSTATE_DATA);
724 hc->rx_s = payload;
725 /*
726 * Not necessary to update rx_bytes_recv here,
727 * since X_recv = 0 for the first feedback packet (cf.
728 * RFC 3448, 6.3) -- gerrit
729 */
730 }
731 goto update_records;
732 }
733
734 if (tfrc_rx_hist_duplicate(&hc->rx_hist, skb))
735 return; /* done receiving */
736
737 if (is_data_packet) {
738 const u32 payload = skb->len - dccp_hdr(skb)->dccph_doff * 4;
739 /*
740 * Update moving-average of s and the sum of received payload bytes
741 */
742 hc->rx_s = tfrc_ewma(hc->rx_s, payload, 9);
743 hc->rx_bytes_recv += payload;
744 }
745
746 /*
747 * Perform loss detection and handle pending losses
748 */
749 if (tfrc_rx_handle_loss(&hc->rx_hist, &hc->rx_li_hist,
750 skb, ndp, ccid3_first_li, sk)) {
751 do_feedback = CCID3_FBACK_PARAM_CHANGE;
752 goto done_receiving;
753 }
754
755 if (tfrc_rx_hist_loss_pending(&hc->rx_hist))
756 return; /* done receiving */
757
758 /*
759 * Handle data packets: RTT sampling and monitoring p
760 */
761 if (unlikely(!is_data_packet))
762 goto update_records;
763
764 if (!tfrc_lh_is_initialised(&hc->rx_li_hist)) {
765 const u32 sample = tfrc_rx_hist_sample_rtt(&hc->rx_hist, skb);
766 /*
767 * Empty loss history: no loss so far, hence p stays 0.
768 * Sample RTT values, since an RTT estimate is required for the
769 * computation of p when the first loss occurs; RFC 3448, 6.3.1.
770 */
771 if (sample != 0)
772 hc->rx_rtt = tfrc_ewma(hc->rx_rtt, sample, 9);
773
774 } else if (tfrc_lh_update_i_mean(&hc->rx_li_hist, skb)) {
775 /*
776 * Step (3) of [RFC 3448, 6.1]: Recompute I_mean and, if I_mean
777 * has decreased (resp. p has increased), send feedback now.
778 */
779 do_feedback = CCID3_FBACK_PARAM_CHANGE;
780 }
781
782 /*
783 * Check if the periodic once-per-RTT feedback is due; RFC 4342, 10.3
784 */
785 if (SUB16(dccp_hdr(skb)->dccph_ccval, hc->rx_last_counter) > 3)
786 do_feedback = CCID3_FBACK_PERIODIC;
787
788update_records:
789 tfrc_rx_hist_add_packet(&hc->rx_hist, skb, ndp);
790
791done_receiving:
792 if (do_feedback)
793 ccid3_hc_rx_send_feedback(sk, skb, do_feedback);
794}
795
796static int ccid3_hc_rx_init(struct ccid *ccid, struct sock *sk)
797{
798 struct ccid3_hc_rx_sock *hc = ccid_priv(ccid);
799
800 hc->rx_state = TFRC_RSTATE_NO_DATA;
801 tfrc_lh_init(&hc->rx_li_hist);
802 return tfrc_rx_hist_alloc(&hc->rx_hist);
803}
804
805static void ccid3_hc_rx_exit(struct sock *sk)
806{
807 struct ccid3_hc_rx_sock *hc = ccid3_hc_rx_sk(sk);
808
809 tfrc_rx_hist_purge(&hc->rx_hist);
810 tfrc_lh_cleanup(&hc->rx_li_hist);
811}
812
813static void ccid3_hc_rx_get_info(struct sock *sk, struct tcp_info *info)
814{
815 info->tcpi_ca_state = ccid3_hc_rx_sk(sk)->rx_state;
816 info->tcpi_options |= TCPI_OPT_TIMESTAMPS;
817 info->tcpi_rcv_rtt = ccid3_hc_rx_sk(sk)->rx_rtt;
818}
819
820static int ccid3_hc_rx_getsockopt(struct sock *sk, const int optname, int len,
821 u32 __user *optval, int __user *optlen)
822{
823 const struct ccid3_hc_rx_sock *hc = ccid3_hc_rx_sk(sk);
824 struct tfrc_rx_info rx_info;
825 const void *val;
826
827 switch (optname) {
828 case DCCP_SOCKOPT_CCID_RX_INFO:
829 if (len < sizeof(rx_info))
830 return -EINVAL;
831 rx_info.tfrcrx_x_recv = hc->rx_x_recv;
832 rx_info.tfrcrx_rtt = hc->rx_rtt;
833 rx_info.tfrcrx_p = tfrc_invert_loss_event_rate(hc->rx_pinv);
834 len = sizeof(rx_info);
835 val = &rx_info;
836 break;
837 default:
838 return -ENOPROTOOPT;
839 }
840
841 if (put_user(len, optlen) || copy_to_user(optval, val, len))
842 return -EFAULT;
843
844 return 0;
845}
846
847struct ccid_operations ccid3_ops = {
848 .ccid_id = DCCPC_CCID3,
849 .ccid_name = "TCP-Friendly Rate Control",
850 .ccid_hc_tx_obj_size = sizeof(struct ccid3_hc_tx_sock),
851 .ccid_hc_tx_init = ccid3_hc_tx_init,
852 .ccid_hc_tx_exit = ccid3_hc_tx_exit,
853 .ccid_hc_tx_send_packet = ccid3_hc_tx_send_packet,
854 .ccid_hc_tx_packet_sent = ccid3_hc_tx_packet_sent,
855 .ccid_hc_tx_packet_recv = ccid3_hc_tx_packet_recv,
856 .ccid_hc_tx_parse_options = ccid3_hc_tx_parse_options,
857 .ccid_hc_rx_obj_size = sizeof(struct ccid3_hc_rx_sock),
858 .ccid_hc_rx_init = ccid3_hc_rx_init,
859 .ccid_hc_rx_exit = ccid3_hc_rx_exit,
860 .ccid_hc_rx_insert_options = ccid3_hc_rx_insert_options,
861 .ccid_hc_rx_packet_recv = ccid3_hc_rx_packet_recv,
862 .ccid_hc_rx_get_info = ccid3_hc_rx_get_info,
863 .ccid_hc_tx_get_info = ccid3_hc_tx_get_info,
864 .ccid_hc_rx_getsockopt = ccid3_hc_rx_getsockopt,
865 .ccid_hc_tx_getsockopt = ccid3_hc_tx_getsockopt,
866};
867
868#ifdef CONFIG_IP_DCCP_CCID3_DEBUG
869module_param(ccid3_debug, bool, 0644);
870MODULE_PARM_DESC(ccid3_debug, "Enable CCID-3 debug messages");
871#endif