2 * net/dccp/ccids/ccid3.c
4 * Copyright (c) 2005 The University of Waikato, Hamilton, New Zealand.
5 * Copyright (c) 2005-6 Ian McDonald <ian.mcdonald@jandi.co.nz>
7 * An implementation of the DCCP protocol
9 * This code has been developed by the University of Waikato WAND
10 * research group. For further information please see http://www.wand.net.nz/
12 * This code also uses code from Lulea University, rereleased as GPL by its
14 * Copyright (c) 2003 Nils-Erik Mattsson, Joacim Haggmark, Magnus Erixzon
16 * Changes to meet Linux coding standards, to make it meet latest ccid3 draft
17 * and to make it work as a loadable module in the DCCP stack written by
18 * Arnaldo Carvalho de Melo <acme@conectiva.com.br>.
20 * Copyright (c) 2005 Arnaldo Carvalho de Melo <acme@conectiva.com.br>
22 * This program is free software; you can redistribute it and/or modify
23 * it under the terms of the GNU General Public License as published by
24 * the Free Software Foundation; either version 2 of the License, or
25 * (at your option) any later version.
27 * This program is distributed in the hope that it will be useful,
28 * but WITHOUT ANY WARRANTY; without even the implied warranty of
29 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
30 * GNU General Public License for more details.
32 * You should have received a copy of the GNU General Public License
33 * along with this program; if not, write to the Free Software
34 * Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
38 #include "lib/packet_history.h"
39 #include "lib/loss_interval.h"
43 #ifdef CONFIG_IP_DCCP_CCID3_DEBUG
44 static int ccid3_debug;
45 #define ccid3_pr_debug(format, a...) DCCP_PR_DEBUG(ccid3_debug, format, ##a)
47 #define ccid3_pr_debug(format, a...)
50 static struct dccp_tx_hist *ccid3_tx_hist;
51 static struct dccp_rx_hist *ccid3_rx_hist;
52 static struct dccp_li_hist *ccid3_li_hist;
55 * Transmitter Half-Connection Routines
57 #ifdef CONFIG_IP_DCCP_CCID3_DEBUG
58 static const char *ccid3_tx_state_name(enum ccid3_hc_tx_states state)
60 static char *ccid3_state_names[] = {
61 [TFRC_SSTATE_NO_SENT] = "NO_SENT",
62 [TFRC_SSTATE_NO_FBACK] = "NO_FBACK",
63 [TFRC_SSTATE_FBACK] = "FBACK",
64 [TFRC_SSTATE_TERM] = "TERM",
67 return ccid3_state_names[state];
71 static void ccid3_hc_tx_set_state(struct sock *sk,
72 enum ccid3_hc_tx_states state)
74 struct ccid3_hc_tx_sock *hctx = ccid3_hc_tx_sk(sk);
75 enum ccid3_hc_tx_states oldstate = hctx->ccid3hctx_state;
77 ccid3_pr_debug("%s(%p) %-8.8s -> %s\n",
78 dccp_role(sk), sk, ccid3_tx_state_name(oldstate),
79 ccid3_tx_state_name(state));
80 WARN_ON(state == oldstate);
81 hctx->ccid3hctx_state = state;
85 * Compute the initial sending rate X_init according to RFC 3390:
86 * w_init = min(4 * MSS, max(2 * MSS, 4380 bytes))
87 * X_init = w_init / RTT
88 * For consistency with other parts of the code, X_init is scaled by 2^6.
90 static inline u64 rfc3390_initial_rate(struct sock *sk)
92 const struct dccp_sock *dp = dccp_sk(sk);
93 const __u32 w_init = min(4 * dp->dccps_mss_cache,
94 max(2 * dp->dccps_mss_cache, 4380U));
96 return scaled_div(w_init << 6, ccid3_hc_tx_sk(sk)->ccid3hctx_rtt);
100 * Recalculate t_ipi and delta (should be called whenever X changes)
102 static inline void ccid3_update_send_interval(struct ccid3_hc_tx_sock *hctx)
104 /* Calculate new t_ipi = s / X_inst (X_inst is in 64 * bytes/second) */
105 hctx->ccid3hctx_t_ipi = scaled_div32(((u64)hctx->ccid3hctx_s) << 6,
108 /* Calculate new delta by delta = min(t_ipi / 2, t_gran / 2) */
109 hctx->ccid3hctx_delta = min_t(u32, hctx->ccid3hctx_t_ipi / 2,
110 TFRC_OPSYS_HALF_TIME_GRAN);
112 ccid3_pr_debug("t_ipi=%u, delta=%u, s=%u, X=%u\n",
113 hctx->ccid3hctx_t_ipi, hctx->ccid3hctx_delta,
114 hctx->ccid3hctx_s, (unsigned)(hctx->ccid3hctx_x >> 6));
120 * X_calc = calcX(s, R, p);
121 * X = max(min(X_calc, 2 * X_recv), s / t_mbi);
123 * If (now - tld >= R)
124 * X = max(min(2 * X, 2 * X_recv), s / R);
127 * Note: X and X_recv are both stored in units of 64 * bytes/second, to support
128 * fine-grained resolution of sending rates. This requires scaling by 2^6
129 * throughout the code. Only X_calc is unscaled (in bytes/second).
132 static void ccid3_hc_tx_update_x(struct sock *sk, struct timeval *now)
135 struct ccid3_hc_tx_sock *hctx = ccid3_hc_tx_sk(sk);
136 __u64 min_rate = 2 * hctx->ccid3hctx_x_recv;
137 const __u64 old_x = hctx->ccid3hctx_x;
140 * Handle IDLE periods: do not reduce below RFC3390 initial sending rate
141 * when idling [RFC 4342, 5.1]. See also draft-ietf-dccp-rfc3448bis.
142 * For consistency with X and X_recv, min_rate is also scaled by 2^6.
144 if (unlikely(hctx->ccid3hctx_idle)) {
145 min_rate = rfc3390_initial_rate(sk);
146 min_rate = max(min_rate, 2 * hctx->ccid3hctx_x_recv);
149 if (hctx->ccid3hctx_p > 0) {
151 hctx->ccid3hctx_x = min(((__u64)hctx->ccid3hctx_x_calc) << 6,
153 hctx->ccid3hctx_x = max(hctx->ccid3hctx_x,
154 (((__u64)hctx->ccid3hctx_s) << 6) /
157 } else if (timeval_delta(now, &hctx->ccid3hctx_t_ld) -
158 (suseconds_t)hctx->ccid3hctx_rtt >= 0) {
161 max(min(2 * hctx->ccid3hctx_x, min_rate),
162 scaled_div(((__u64)hctx->ccid3hctx_s) << 6,
163 hctx->ccid3hctx_rtt));
164 hctx->ccid3hctx_t_ld = *now;
167 if (hctx->ccid3hctx_x != old_x) {
168 ccid3_pr_debug("X_prev=%u, X_now=%u, X_calc=%u, "
169 "X_recv=%u\n", (unsigned)(old_x >> 6),
170 (unsigned)(hctx->ccid3hctx_x >> 6),
171 hctx->ccid3hctx_x_calc,
172 (unsigned)(hctx->ccid3hctx_x_recv >> 6));
174 ccid3_update_send_interval(hctx);
179 * Track the mean packet size `s' (cf. RFC 4342, 5.3 and RFC 3448, 4.1)
180 * @len: DCCP packet payload size in bytes
182 static inline void ccid3_hc_tx_update_s(struct ccid3_hc_tx_sock *hctx, int len)
184 const u16 old_s = hctx->ccid3hctx_s;
186 hctx->ccid3hctx_s = old_s == 0 ? len : (9 * old_s + len) / 10;
188 if (hctx->ccid3hctx_s != old_s)
189 ccid3_update_send_interval(hctx);
193 * Update Window Counter using the algorithm from [RFC 4342, 8.1].
194 * The algorithm is not applicable if RTT < 4 microseconds.
196 static inline void ccid3_hc_tx_update_win_count(struct ccid3_hc_tx_sock *hctx,
202 if (unlikely(hctx->ccid3hctx_rtt < 4)) /* avoid divide-by-zero */
205 delta = timeval_delta(now, &hctx->ccid3hctx_t_last_win_count);
206 DCCP_BUG_ON(delta < 0);
208 quarter_rtts = (u32)delta / (hctx->ccid3hctx_rtt / 4);
210 if (quarter_rtts > 0) {
211 hctx->ccid3hctx_t_last_win_count = *now;
212 hctx->ccid3hctx_last_win_count += min_t(u32, quarter_rtts, 5);
213 hctx->ccid3hctx_last_win_count &= 0xF; /* mod 16 */
215 ccid3_pr_debug("now at %#X\n", hctx->ccid3hctx_last_win_count);
219 static void ccid3_hc_tx_no_feedback_timer(unsigned long data)
221 struct sock *sk = (struct sock *)data;
222 struct ccid3_hc_tx_sock *hctx = ccid3_hc_tx_sk(sk);
224 unsigned long t_nfb = USEC_PER_SEC / 5;
227 if (sock_owned_by_user(sk)) {
228 /* Try again later. */
229 /* XXX: set some sensible MIB */
233 ccid3_pr_debug("%s(%p, state=%s) - entry \n", dccp_role(sk), sk,
234 ccid3_tx_state_name(hctx->ccid3hctx_state));
236 hctx->ccid3hctx_idle = 1;
238 switch (hctx->ccid3hctx_state) {
239 case TFRC_SSTATE_NO_FBACK:
240 /* RFC 3448, 4.4: Halve send rate directly */
241 hctx->ccid3hctx_x = max(hctx->ccid3hctx_x / 2,
242 (((__u64)hctx->ccid3hctx_s) << 6) /
245 ccid3_pr_debug("%s(%p, state=%s), updated tx rate to %u "
246 "bytes/s\n", dccp_role(sk), sk,
247 ccid3_tx_state_name(hctx->ccid3hctx_state),
248 (unsigned)(hctx->ccid3hctx_x >> 6));
249 /* The value of R is still undefined and so we can not recompute
250 * the timout value. Keep initial value as per [RFC 4342, 5]. */
251 t_nfb = TFRC_INITIAL_TIMEOUT;
252 ccid3_update_send_interval(hctx);
254 case TFRC_SSTATE_FBACK:
256 * Modify the cached value of X_recv [RFC 3448, 4.4]
258 * If (p == 0 || X_calc > 2 * X_recv)
259 * X_recv = max(X_recv / 2, s / (2 * t_mbi));
261 * X_recv = X_calc / 4;
263 * Note that X_recv is scaled by 2^6 while X_calc is not
265 BUG_ON(hctx->ccid3hctx_p && !hctx->ccid3hctx_x_calc);
267 if (hctx->ccid3hctx_p == 0 ||
268 (hctx->ccid3hctx_x_calc > (hctx->ccid3hctx_x_recv >> 5))) {
270 hctx->ccid3hctx_x_recv =
271 max(hctx->ccid3hctx_x_recv / 2,
272 (((__u64)hctx->ccid3hctx_s) << 6) /
275 if (hctx->ccid3hctx_p == 0)
276 dccp_timestamp(sk, &now);
278 hctx->ccid3hctx_x_recv = hctx->ccid3hctx_x_calc;
279 hctx->ccid3hctx_x_recv <<= 4;
281 /* Now recalculate X [RFC 3448, 4.3, step (4)] */
282 ccid3_hc_tx_update_x(sk, &now);
284 * Schedule no feedback timer to expire in
285 * max(t_RTO, 2 * s/X) = max(t_RTO, 2 * t_ipi)
286 * See comments in packet_recv() regarding the value of t_RTO.
288 t_nfb = max(hctx->ccid3hctx_t_rto, 2 * hctx->ccid3hctx_t_ipi);
290 case TFRC_SSTATE_NO_SENT:
291 DCCP_BUG("%s(%p) - Illegal state NO_SENT", dccp_role(sk), sk);
293 case TFRC_SSTATE_TERM:
298 sk_reset_timer(sk, &hctx->ccid3hctx_no_feedback_timer,
299 jiffies + usecs_to_jiffies(t_nfb));
307 * > 0: delay (in msecs) that should pass before actually sending
308 * = 0: can send immediately
309 * < 0: error condition; do not send packet
311 static int ccid3_hc_tx_send_packet(struct sock *sk, struct sk_buff *skb)
313 struct dccp_sock *dp = dccp_sk(sk);
314 struct ccid3_hc_tx_sock *hctx = ccid3_hc_tx_sk(sk);
318 BUG_ON(hctx == NULL);
321 * This function is called only for Data and DataAck packets. Sending
322 * zero-sized Data(Ack)s is theoretically possible, but for congestion
323 * control this case is pathological - ignore it.
325 if (unlikely(skb->len == 0))
328 dccp_timestamp(sk, &now);
330 switch (hctx->ccid3hctx_state) {
331 case TFRC_SSTATE_NO_SENT:
332 sk_reset_timer(sk, &hctx->ccid3hctx_no_feedback_timer,
334 usecs_to_jiffies(TFRC_INITIAL_TIMEOUT)));
335 hctx->ccid3hctx_last_win_count = 0;
336 hctx->ccid3hctx_t_last_win_count = now;
338 /* Set t_0 for initial packet */
339 hctx->ccid3hctx_t_nom = now;
341 hctx->ccid3hctx_s = skb->len;
344 * Use initial RTT sample when available: recommended by erratum
345 * to RFC 4342. This implements the initialisation procedure of
346 * draft rfc3448bis, section 4.2. Remember, X is scaled by 2^6.
348 if (dp->dccps_syn_rtt) {
349 ccid3_pr_debug("SYN RTT = %uus\n", dp->dccps_syn_rtt);
350 hctx->ccid3hctx_rtt = dp->dccps_syn_rtt;
351 hctx->ccid3hctx_x = rfc3390_initial_rate(sk);
352 hctx->ccid3hctx_t_ld = now;
354 /* Sender does not have RTT sample: X = MSS/second */
355 hctx->ccid3hctx_x = dp->dccps_mss_cache;
356 hctx->ccid3hctx_x <<= 6;
358 ccid3_update_send_interval(hctx);
360 ccid3_hc_tx_set_state(sk, TFRC_SSTATE_NO_FBACK);
362 case TFRC_SSTATE_NO_FBACK:
363 case TFRC_SSTATE_FBACK:
364 delay = timeval_delta(&hctx->ccid3hctx_t_nom, &now);
365 ccid3_pr_debug("delay=%ld\n", (long)delay);
367 * Scheduling of packet transmissions [RFC 3448, 4.6]
369 * if (t_now > t_nom - delta)
370 * // send the packet now
372 * // send the packet in (t_nom - t_now) milliseconds.
374 if (delay - (suseconds_t)hctx->ccid3hctx_delta >= 0)
375 return delay / 1000L;
377 ccid3_hc_tx_update_win_count(hctx, &now);
379 case TFRC_SSTATE_TERM:
380 DCCP_BUG("%s(%p) - Illegal state TERM", dccp_role(sk), sk);
384 /* prepare to send now (add options etc.) */
385 dp->dccps_hc_tx_insert_options = 1;
386 DCCP_SKB_CB(skb)->dccpd_ccval = hctx->ccid3hctx_last_win_count;
387 hctx->ccid3hctx_idle = 0;
389 /* set the nominal send time for the next following packet */
390 timeval_add_usecs(&hctx->ccid3hctx_t_nom, hctx->ccid3hctx_t_ipi);
395 static void ccid3_hc_tx_packet_sent(struct sock *sk, int more,
398 struct ccid3_hc_tx_sock *hctx = ccid3_hc_tx_sk(sk);
400 struct dccp_tx_hist_entry *packet;
402 BUG_ON(hctx == NULL);
404 ccid3_hc_tx_update_s(hctx, len);
406 packet = dccp_tx_hist_entry_new(ccid3_tx_hist, GFP_ATOMIC);
407 if (unlikely(packet == NULL)) {
408 DCCP_CRIT("packet history - out of memory!");
411 dccp_tx_hist_add_entry(&hctx->ccid3hctx_hist, packet);
413 dccp_timestamp(sk, &now);
414 packet->dccphtx_tstamp = now;
415 packet->dccphtx_seqno = dccp_sk(sk)->dccps_gss;
416 packet->dccphtx_rtt = hctx->ccid3hctx_rtt;
417 packet->dccphtx_sent = 1;
420 static void ccid3_hc_tx_packet_recv(struct sock *sk, struct sk_buff *skb)
422 const struct dccp_sock *dp = dccp_sk(sk);
423 struct ccid3_hc_tx_sock *hctx = ccid3_hc_tx_sk(sk);
424 struct ccid3_options_received *opt_recv;
425 struct dccp_tx_hist_entry *packet;
430 BUG_ON(hctx == NULL);
432 /* we are only interested in ACKs */
433 if (!(DCCP_SKB_CB(skb)->dccpd_type == DCCP_PKT_ACK ||
434 DCCP_SKB_CB(skb)->dccpd_type == DCCP_PKT_DATAACK))
437 opt_recv = &hctx->ccid3hctx_options_received;
439 switch (hctx->ccid3hctx_state) {
440 case TFRC_SSTATE_NO_FBACK:
441 case TFRC_SSTATE_FBACK:
442 /* get packet from history to look up t_recvdata */
443 packet = dccp_tx_hist_find_entry(&hctx->ccid3hctx_hist,
444 DCCP_SKB_CB(skb)->dccpd_ack_seq);
445 if (unlikely(packet == NULL)) {
446 DCCP_WARN("%s(%p), seqno %llu(%s) doesn't exist "
447 "in history!\n", dccp_role(sk), sk,
448 (unsigned long long)DCCP_SKB_CB(skb)->dccpd_ack_seq,
449 dccp_packet_name(DCCP_SKB_CB(skb)->dccpd_type));
453 /* Update receive rate in units of 64 * bytes/second */
454 hctx->ccid3hctx_x_recv = opt_recv->ccid3or_receive_rate;
455 hctx->ccid3hctx_x_recv <<= 6;
457 /* Update loss event rate */
458 pinv = opt_recv->ccid3or_loss_event_rate;
459 if (pinv == ~0U || pinv == 0) /* see RFC 4342, 8.5 */
460 hctx->ccid3hctx_p = 0;
461 else /* can not exceed 100% */
462 hctx->ccid3hctx_p = 1000000 / pinv;
464 dccp_timestamp(sk, &now);
467 * Calculate new round trip sample as per [RFC 3448, 4.3] by
468 * R_sample = (now - t_recvdata) - t_elapsed
470 r_sample = dccp_sample_rtt(sk, &now, &packet->dccphtx_tstamp);
473 * Update RTT estimate by
474 * If (No feedback recv)
477 * R = q * R + (1 - q) * R_sample;
479 * q is a constant, RFC 3448 recomments 0.9
481 if (hctx->ccid3hctx_state == TFRC_SSTATE_NO_FBACK) {
483 * Larger Initial Windows [RFC 4342, sec. 5]
485 hctx->ccid3hctx_rtt = r_sample;
486 hctx->ccid3hctx_x = rfc3390_initial_rate(sk);
487 hctx->ccid3hctx_t_ld = now;
489 ccid3_update_send_interval(hctx);
491 ccid3_pr_debug("%s(%p), s=%u, MSS=%u, "
492 "R_sample=%uus, X=%u\n", dccp_role(sk),
493 sk, hctx->ccid3hctx_s,
494 dp->dccps_mss_cache, r_sample,
495 (unsigned)(hctx->ccid3hctx_x >> 6));
497 ccid3_hc_tx_set_state(sk, TFRC_SSTATE_FBACK);
499 hctx->ccid3hctx_rtt = (9 * hctx->ccid3hctx_rtt +
502 /* Update sending rate (step 4 of [RFC 3448, 4.3]) */
503 if (hctx->ccid3hctx_p > 0)
504 hctx->ccid3hctx_x_calc =
505 tfrc_calc_x(hctx->ccid3hctx_s,
508 ccid3_hc_tx_update_x(sk, &now);
510 ccid3_pr_debug("%s(%p), RTT=%uus (sample=%uus), s=%u, "
511 "p=%u, X_calc=%u, X_recv=%u, X=%u\n",
513 sk, hctx->ccid3hctx_rtt, r_sample,
514 hctx->ccid3hctx_s, hctx->ccid3hctx_p,
515 hctx->ccid3hctx_x_calc,
516 (unsigned)(hctx->ccid3hctx_x_recv >> 6),
517 (unsigned)(hctx->ccid3hctx_x >> 6));
520 /* unschedule no feedback timer */
521 sk_stop_timer(sk, &hctx->ccid3hctx_no_feedback_timer);
523 /* remove all packets older than the one acked from history */
524 dccp_tx_hist_purge_older(ccid3_tx_hist,
525 &hctx->ccid3hctx_hist, packet);
527 * As we have calculated new ipi, delta, t_nom it is possible
528 * that we now can send a packet, so wake up dccp_wait_for_ccid
530 sk->sk_write_space(sk);
533 * Update timeout interval for the nofeedback timer.
534 * We use a configuration option to increase the lower bound.
535 * This can help avoid triggering the nofeedback timer too
536 * often ('spinning') on LANs with small RTTs.
538 hctx->ccid3hctx_t_rto = max_t(u32, 4 * hctx->ccid3hctx_rtt,
539 CONFIG_IP_DCCP_CCID3_RTO *
540 (USEC_PER_SEC/1000));
542 * Schedule no feedback timer to expire in
543 * max(t_RTO, 2 * s/X) = max(t_RTO, 2 * t_ipi)
545 t_nfb = max(hctx->ccid3hctx_t_rto, 2 * hctx->ccid3hctx_t_ipi);
547 ccid3_pr_debug("%s(%p), Scheduled no feedback timer to "
548 "expire in %lu jiffies (%luus)\n",
550 sk, usecs_to_jiffies(t_nfb), t_nfb);
552 sk_reset_timer(sk, &hctx->ccid3hctx_no_feedback_timer,
553 jiffies + usecs_to_jiffies(t_nfb));
556 hctx->ccid3hctx_idle = 1;
558 case TFRC_SSTATE_NO_SENT: /* fall through */
559 case TFRC_SSTATE_TERM: /* ignore feedback when closing */
564 static int ccid3_hc_tx_parse_options(struct sock *sk, unsigned char option,
565 unsigned char len, u16 idx,
566 unsigned char *value)
569 const struct dccp_sock *dp = dccp_sk(sk);
570 struct ccid3_hc_tx_sock *hctx = ccid3_hc_tx_sk(sk);
571 struct ccid3_options_received *opt_recv;
573 BUG_ON(hctx == NULL);
575 opt_recv = &hctx->ccid3hctx_options_received;
577 if (opt_recv->ccid3or_seqno != dp->dccps_gsr) {
578 opt_recv->ccid3or_seqno = dp->dccps_gsr;
579 opt_recv->ccid3or_loss_event_rate = ~0;
580 opt_recv->ccid3or_loss_intervals_idx = 0;
581 opt_recv->ccid3or_loss_intervals_len = 0;
582 opt_recv->ccid3or_receive_rate = 0;
586 case TFRC_OPT_LOSS_EVENT_RATE:
587 if (unlikely(len != 4)) {
588 DCCP_WARN("%s(%p), invalid len %d "
589 "for TFRC_OPT_LOSS_EVENT_RATE\n",
590 dccp_role(sk), sk, len);
593 opt_recv->ccid3or_loss_event_rate =
594 ntohl(*(__be32 *)value);
595 ccid3_pr_debug("%s(%p), LOSS_EVENT_RATE=%u\n",
597 opt_recv->ccid3or_loss_event_rate);
600 case TFRC_OPT_LOSS_INTERVALS:
601 opt_recv->ccid3or_loss_intervals_idx = idx;
602 opt_recv->ccid3or_loss_intervals_len = len;
603 ccid3_pr_debug("%s(%p), LOSS_INTERVALS=(%u, %u)\n",
605 opt_recv->ccid3or_loss_intervals_idx,
606 opt_recv->ccid3or_loss_intervals_len);
608 case TFRC_OPT_RECEIVE_RATE:
609 if (unlikely(len != 4)) {
610 DCCP_WARN("%s(%p), invalid len %d "
611 "for TFRC_OPT_RECEIVE_RATE\n",
612 dccp_role(sk), sk, len);
615 opt_recv->ccid3or_receive_rate =
616 ntohl(*(__be32 *)value);
617 ccid3_pr_debug("%s(%p), RECEIVE_RATE=%u\n",
619 opt_recv->ccid3or_receive_rate);
627 static int ccid3_hc_tx_init(struct ccid *ccid, struct sock *sk)
629 struct ccid3_hc_tx_sock *hctx = ccid_priv(ccid);
631 hctx->ccid3hctx_s = 0;
632 hctx->ccid3hctx_rtt = 0;
633 hctx->ccid3hctx_state = TFRC_SSTATE_NO_SENT;
634 INIT_LIST_HEAD(&hctx->ccid3hctx_hist);
636 hctx->ccid3hctx_no_feedback_timer.function =
637 ccid3_hc_tx_no_feedback_timer;
638 hctx->ccid3hctx_no_feedback_timer.data = (unsigned long)sk;
639 init_timer(&hctx->ccid3hctx_no_feedback_timer);
644 static void ccid3_hc_tx_exit(struct sock *sk)
646 struct ccid3_hc_tx_sock *hctx = ccid3_hc_tx_sk(sk);
648 BUG_ON(hctx == NULL);
650 ccid3_hc_tx_set_state(sk, TFRC_SSTATE_TERM);
651 sk_stop_timer(sk, &hctx->ccid3hctx_no_feedback_timer);
653 /* Empty packet history */
654 dccp_tx_hist_purge(ccid3_tx_hist, &hctx->ccid3hctx_hist);
657 static void ccid3_hc_tx_get_info(struct sock *sk, struct tcp_info *info)
659 const struct ccid3_hc_tx_sock *hctx = ccid3_hc_tx_sk(sk);
661 /* Listen socks doesn't have a private CCID block */
662 if (sk->sk_state == DCCP_LISTEN)
665 BUG_ON(hctx == NULL);
667 info->tcpi_rto = hctx->ccid3hctx_t_rto;
668 info->tcpi_rtt = hctx->ccid3hctx_rtt;
671 static int ccid3_hc_tx_getsockopt(struct sock *sk, const int optname, int len,
672 u32 __user *optval, int __user *optlen)
674 const struct ccid3_hc_tx_sock *hctx = ccid3_hc_tx_sk(sk);
677 /* Listen socks doesn't have a private CCID block */
678 if (sk->sk_state == DCCP_LISTEN)
682 case DCCP_SOCKOPT_CCID_TX_INFO:
683 if (len < sizeof(hctx->ccid3hctx_tfrc))
685 len = sizeof(hctx->ccid3hctx_tfrc);
686 val = &hctx->ccid3hctx_tfrc;
692 if (put_user(len, optlen) || copy_to_user(optval, val, len))
699 * Receiver Half-Connection Routines
701 #ifdef CONFIG_IP_DCCP_CCID3_DEBUG
702 static const char *ccid3_rx_state_name(enum ccid3_hc_rx_states state)
704 static char *ccid3_rx_state_names[] = {
705 [TFRC_RSTATE_NO_DATA] = "NO_DATA",
706 [TFRC_RSTATE_DATA] = "DATA",
707 [TFRC_RSTATE_TERM] = "TERM",
710 return ccid3_rx_state_names[state];
714 static void ccid3_hc_rx_set_state(struct sock *sk,
715 enum ccid3_hc_rx_states state)
717 struct ccid3_hc_rx_sock *hcrx = ccid3_hc_rx_sk(sk);
718 enum ccid3_hc_rx_states oldstate = hcrx->ccid3hcrx_state;
720 ccid3_pr_debug("%s(%p) %-8.8s -> %s\n",
721 dccp_role(sk), sk, ccid3_rx_state_name(oldstate),
722 ccid3_rx_state_name(state));
723 WARN_ON(state == oldstate);
724 hcrx->ccid3hcrx_state = state;
727 static inline void ccid3_hc_rx_update_s(struct ccid3_hc_rx_sock *hcrx, int len)
729 if (unlikely(len == 0)) /* don't update on empty packets (e.g. ACKs) */
730 ccid3_pr_debug("Packet payload length is 0 - not updating\n");
732 hcrx->ccid3hcrx_s = hcrx->ccid3hcrx_s == 0 ? len :
733 (9 * hcrx->ccid3hcrx_s + len) / 10;
736 static void ccid3_hc_rx_send_feedback(struct sock *sk)
738 struct ccid3_hc_rx_sock *hcrx = ccid3_hc_rx_sk(sk);
739 struct dccp_sock *dp = dccp_sk(sk);
740 struct dccp_rx_hist_entry *packet;
744 ccid3_pr_debug("%s(%p) - entry \n", dccp_role(sk), sk);
746 dccp_timestamp(sk, &now);
748 switch (hcrx->ccid3hcrx_state) {
749 case TFRC_RSTATE_NO_DATA:
750 hcrx->ccid3hcrx_x_recv = 0;
752 case TFRC_RSTATE_DATA:
753 delta = timeval_delta(&now,
754 &hcrx->ccid3hcrx_tstamp_last_feedback);
755 DCCP_BUG_ON(delta < 0);
756 hcrx->ccid3hcrx_x_recv =
757 scaled_div32(hcrx->ccid3hcrx_bytes_recv, delta);
759 case TFRC_RSTATE_TERM:
760 DCCP_BUG("%s(%p) - Illegal state TERM", dccp_role(sk), sk);
764 packet = dccp_rx_hist_find_data_packet(&hcrx->ccid3hcrx_hist);
765 if (unlikely(packet == NULL)) {
766 DCCP_WARN("%s(%p), no data packet in history!\n",
771 hcrx->ccid3hcrx_tstamp_last_feedback = now;
772 hcrx->ccid3hcrx_ccval_last_counter = packet->dccphrx_ccval;
773 hcrx->ccid3hcrx_bytes_recv = 0;
775 /* Elapsed time information [RFC 4340, 13.2] in units of 10 * usecs */
776 delta = timeval_delta(&now, &packet->dccphrx_tstamp);
777 DCCP_BUG_ON(delta < 0);
778 hcrx->ccid3hcrx_elapsed_time = delta / 10;
780 if (hcrx->ccid3hcrx_p == 0)
781 hcrx->ccid3hcrx_pinv = ~0U; /* see RFC 4342, 8.5 */
782 else if (hcrx->ccid3hcrx_p > 1000000) {
783 DCCP_WARN("p (%u) > 100%%\n", hcrx->ccid3hcrx_p);
784 hcrx->ccid3hcrx_pinv = 1; /* use 100% in this case */
786 hcrx->ccid3hcrx_pinv = 1000000 / hcrx->ccid3hcrx_p;
788 dp->dccps_hc_rx_insert_options = 1;
792 static int ccid3_hc_rx_insert_options(struct sock *sk, struct sk_buff *skb)
794 const struct ccid3_hc_rx_sock *hcrx = ccid3_hc_rx_sk(sk);
797 BUG_ON(hcrx == NULL);
799 if (!(sk->sk_state == DCCP_OPEN || sk->sk_state == DCCP_PARTOPEN))
802 DCCP_SKB_CB(skb)->dccpd_ccval = hcrx->ccid3hcrx_ccval_last_counter;
804 if (dccp_packet_without_ack(skb))
807 x_recv = htonl(hcrx->ccid3hcrx_x_recv);
808 pinv = htonl(hcrx->ccid3hcrx_pinv);
810 if ((hcrx->ccid3hcrx_elapsed_time != 0 &&
811 dccp_insert_option_elapsed_time(sk, skb,
812 hcrx->ccid3hcrx_elapsed_time)) ||
813 dccp_insert_option_timestamp(sk, skb) ||
814 dccp_insert_option(sk, skb, TFRC_OPT_LOSS_EVENT_RATE,
815 &pinv, sizeof(pinv)) ||
816 dccp_insert_option(sk, skb, TFRC_OPT_RECEIVE_RATE,
817 &x_recv, sizeof(x_recv)))
823 /* calculate first loss interval
825 * returns estimated loss interval in usecs */
827 static u32 ccid3_hc_rx_calc_first_li(struct sock *sk)
829 struct ccid3_hc_rx_sock *hcrx = ccid3_hc_rx_sk(sk);
830 struct dccp_rx_hist_entry *entry, *next, *tail = NULL;
832 suseconds_t rtt, delta;
833 struct timeval tstamp = { 0, };
839 list_for_each_entry_safe(entry, next, &hcrx->ccid3hcrx_hist,
841 if (dccp_rx_hist_entry_data_packet(entry)) {
846 tstamp = entry->dccphrx_tstamp;
847 win_count = entry->dccphrx_ccval;
851 interval = win_count - entry->dccphrx_ccval;
853 interval += TFRC_WIN_COUNT_LIMIT;
861 if (unlikely(step == 0)) {
862 DCCP_WARN("%s(%p), packet history has no data packets!\n",
867 if (unlikely(interval == 0)) {
868 DCCP_WARN("%s(%p), Could not find a win_count interval > 0."
869 "Defaulting to 1\n", dccp_role(sk), sk);
874 DCCP_CRIT("tail is null\n");
878 delta = timeval_delta(&tstamp, &tail->dccphrx_tstamp);
879 DCCP_BUG_ON(delta < 0);
881 rtt = delta * 4 / interval;
882 ccid3_pr_debug("%s(%p), approximated RTT to %dus\n",
883 dccp_role(sk), sk, (int)rtt);
886 * Determine the length of the first loss interval via inverse lookup.
887 * Assume that X_recv can be computed by the throughput equation
891 * Find some p such that f(p) = fval; return 1/p [RFC 3448, 6.3.1].
893 if (rtt == 0) { /* would result in divide-by-zero */
894 DCCP_WARN("RTT==0\n");
898 dccp_timestamp(sk, &tstamp);
899 delta = timeval_delta(&tstamp, &hcrx->ccid3hcrx_tstamp_last_feedback);
900 DCCP_BUG_ON(delta <= 0);
902 x_recv = scaled_div32(hcrx->ccid3hcrx_bytes_recv, delta);
903 if (x_recv == 0) { /* would also trigger divide-by-zero */
904 DCCP_WARN("X_recv==0\n");
905 if ((x_recv = hcrx->ccid3hcrx_x_recv) == 0) {
906 DCCP_BUG("stored value of X_recv is zero");
911 fval = scaled_div(hcrx->ccid3hcrx_s, rtt);
912 fval = scaled_div32(fval, x_recv);
913 p = tfrc_calc_x_reverse_lookup(fval);
915 ccid3_pr_debug("%s(%p), receive rate=%u bytes/s, implied "
916 "loss rate=%u\n", dccp_role(sk), sk, x_recv, p);
924 static void ccid3_hc_rx_update_li(struct sock *sk, u64 seq_loss, u8 win_loss)
926 struct ccid3_hc_rx_sock *hcrx = ccid3_hc_rx_sk(sk);
927 struct dccp_li_hist_entry *head;
930 if (list_empty(&hcrx->ccid3hcrx_li_hist)) {
931 if (!dccp_li_hist_interval_new(ccid3_li_hist,
932 &hcrx->ccid3hcrx_li_hist, seq_loss, win_loss))
935 head = list_entry(hcrx->ccid3hcrx_li_hist.next,
936 struct dccp_li_hist_entry, dccplih_node);
937 head->dccplih_interval = ccid3_hc_rx_calc_first_li(sk);
939 struct dccp_li_hist_entry *entry;
940 struct list_head *tail;
942 head = list_entry(hcrx->ccid3hcrx_li_hist.next,
943 struct dccp_li_hist_entry, dccplih_node);
944 /* FIXME win count check removed as was wrong */
945 /* should make this check with receive history */
946 /* and compare there as per section 10.2 of RFC4342 */
948 /* new loss event detected */
949 /* calculate last interval length */
950 seq_temp = dccp_delta_seqno(head->dccplih_seqno, seq_loss);
951 entry = dccp_li_hist_entry_new(ccid3_li_hist, GFP_ATOMIC);
954 DCCP_BUG("out of memory - can not allocate entry");
958 list_add(&entry->dccplih_node, &hcrx->ccid3hcrx_li_hist);
960 tail = hcrx->ccid3hcrx_li_hist.prev;
962 kmem_cache_free(ccid3_li_hist->dccplih_slab, tail);
964 /* Create the newest interval */
965 entry->dccplih_seqno = seq_loss;
966 entry->dccplih_interval = seq_temp;
967 entry->dccplih_win_count = win_loss;
971 static int ccid3_hc_rx_detect_loss(struct sock *sk,
972 struct dccp_rx_hist_entry *packet)
974 struct ccid3_hc_rx_sock *hcrx = ccid3_hc_rx_sk(sk);
975 struct dccp_rx_hist_entry *rx_hist =
976 dccp_rx_hist_head(&hcrx->ccid3hcrx_hist);
977 u64 seqno = packet->dccphrx_seqno;
983 tmp_seqno = hcrx->ccid3hcrx_seqno_nonloss;
986 follows48(packet->dccphrx_seqno, hcrx->ccid3hcrx_seqno_nonloss)) {
987 hcrx->ccid3hcrx_seqno_nonloss = seqno;
988 hcrx->ccid3hcrx_ccval_nonloss = packet->dccphrx_ccval;
993 while (dccp_delta_seqno(hcrx->ccid3hcrx_seqno_nonloss, seqno)
994 > TFRC_RECV_NUM_LATE_LOSS) {
996 ccid3_hc_rx_update_li(sk, hcrx->ccid3hcrx_seqno_nonloss,
997 hcrx->ccid3hcrx_ccval_nonloss);
998 tmp_seqno = hcrx->ccid3hcrx_seqno_nonloss;
999 dccp_inc_seqno(&tmp_seqno);
1000 hcrx->ccid3hcrx_seqno_nonloss = tmp_seqno;
1001 dccp_inc_seqno(&tmp_seqno);
1002 while (dccp_rx_hist_find_entry(&hcrx->ccid3hcrx_hist,
1003 tmp_seqno, &ccval)) {
1004 hcrx->ccid3hcrx_seqno_nonloss = tmp_seqno;
1005 hcrx->ccid3hcrx_ccval_nonloss = ccval;
1006 dccp_inc_seqno(&tmp_seqno);
1010 /* FIXME - this code could be simplified with above while */
1011 /* but works at moment */
1012 if (follows48(packet->dccphrx_seqno, hcrx->ccid3hcrx_seqno_nonloss)) {
1013 hcrx->ccid3hcrx_seqno_nonloss = seqno;
1014 hcrx->ccid3hcrx_ccval_nonloss = packet->dccphrx_ccval;
1018 dccp_rx_hist_add_packet(ccid3_rx_hist, &hcrx->ccid3hcrx_hist,
1019 &hcrx->ccid3hcrx_li_hist, packet,
1020 hcrx->ccid3hcrx_seqno_nonloss);
1024 static void ccid3_hc_rx_packet_recv(struct sock *sk, struct sk_buff *skb)
1026 struct ccid3_hc_rx_sock *hcrx = ccid3_hc_rx_sk(sk);
1027 const struct dccp_options_received *opt_recv;
1028 struct dccp_rx_hist_entry *packet;
1030 u32 p_prev, r_sample, rtt_prev;
1031 int loss, payload_size;
1033 BUG_ON(hcrx == NULL);
1035 opt_recv = &dccp_sk(sk)->dccps_options_received;
1037 switch (DCCP_SKB_CB(skb)->dccpd_type) {
1039 if (hcrx->ccid3hcrx_state == TFRC_RSTATE_NO_DATA)
1041 case DCCP_PKT_DATAACK:
1042 if (opt_recv->dccpor_timestamp_echo == 0)
1044 rtt_prev = hcrx->ccid3hcrx_rtt;
1045 dccp_timestamp(sk, &now);
1046 r_sample = dccp_sample_rtt(sk, &now, NULL);
1048 if (hcrx->ccid3hcrx_state == TFRC_RSTATE_NO_DATA)
1049 hcrx->ccid3hcrx_rtt = r_sample;
1051 hcrx->ccid3hcrx_rtt = (hcrx->ccid3hcrx_rtt * 9) / 10 +
1054 if (rtt_prev != hcrx->ccid3hcrx_rtt)
1055 ccid3_pr_debug("%s(%p), New RTT=%uus, elapsed time=%u\n",
1056 dccp_role(sk), sk, hcrx->ccid3hcrx_rtt,
1057 opt_recv->dccpor_elapsed_time);
1061 default: /* We're not interested in other packet types, move along */
1065 packet = dccp_rx_hist_entry_new(ccid3_rx_hist, sk, opt_recv->dccpor_ndp,
1067 if (unlikely(packet == NULL)) {
1068 DCCP_WARN("%s(%p), Not enough mem to add rx packet "
1069 "to history, consider it lost!\n", dccp_role(sk), sk);
1073 loss = ccid3_hc_rx_detect_loss(sk, packet);
1075 if (DCCP_SKB_CB(skb)->dccpd_type == DCCP_PKT_ACK)
1078 payload_size = skb->len - dccp_hdr(skb)->dccph_doff * 4;
1079 ccid3_hc_rx_update_s(hcrx, payload_size);
1081 switch (hcrx->ccid3hcrx_state) {
1082 case TFRC_RSTATE_NO_DATA:
1083 ccid3_pr_debug("%s(%p, state=%s), skb=%p, sending initial "
1084 "feedback\n", dccp_role(sk), sk,
1085 dccp_state_name(sk->sk_state), skb);
1086 ccid3_hc_rx_send_feedback(sk);
1087 ccid3_hc_rx_set_state(sk, TFRC_RSTATE_DATA);
1089 case TFRC_RSTATE_DATA:
1090 hcrx->ccid3hcrx_bytes_recv += payload_size;
1094 dccp_timestamp(sk, &now);
1095 if ((timeval_delta(&now, &hcrx->ccid3hcrx_tstamp_last_ack) -
1096 (suseconds_t)hcrx->ccid3hcrx_rtt) >= 0) {
1097 hcrx->ccid3hcrx_tstamp_last_ack = now;
1098 ccid3_hc_rx_send_feedback(sk);
1101 case TFRC_RSTATE_TERM:
1102 DCCP_BUG("%s(%p) - Illegal state TERM", dccp_role(sk), sk);
1106 /* Dealing with packet loss */
1107 ccid3_pr_debug("%s(%p, state=%s), data loss! Reacting...\n",
1108 dccp_role(sk), sk, dccp_state_name(sk->sk_state));
1110 p_prev = hcrx->ccid3hcrx_p;
1112 /* Calculate loss event rate */
1113 if (!list_empty(&hcrx->ccid3hcrx_li_hist)) {
1114 u32 i_mean = dccp_li_hist_calc_i_mean(&hcrx->ccid3hcrx_li_hist);
1116 /* Scaling up by 1000000 as fixed decimal */
1118 hcrx->ccid3hcrx_p = 1000000 / i_mean;
1120 DCCP_BUG("empty loss history");
1122 if (hcrx->ccid3hcrx_p > p_prev) {
1123 ccid3_hc_rx_send_feedback(sk);
1128 static int ccid3_hc_rx_init(struct ccid *ccid, struct sock *sk)
1130 struct ccid3_hc_rx_sock *hcrx = ccid_priv(ccid);
1132 ccid3_pr_debug("entry\n");
1134 hcrx->ccid3hcrx_state = TFRC_RSTATE_NO_DATA;
1135 INIT_LIST_HEAD(&hcrx->ccid3hcrx_hist);
1136 INIT_LIST_HEAD(&hcrx->ccid3hcrx_li_hist);
1137 dccp_timestamp(sk, &hcrx->ccid3hcrx_tstamp_last_ack);
1138 hcrx->ccid3hcrx_tstamp_last_feedback = hcrx->ccid3hcrx_tstamp_last_ack;
1139 hcrx->ccid3hcrx_s = 0;
1140 hcrx->ccid3hcrx_rtt = 0;
1144 static void ccid3_hc_rx_exit(struct sock *sk)
1146 struct ccid3_hc_rx_sock *hcrx = ccid3_hc_rx_sk(sk);
1148 BUG_ON(hcrx == NULL);
1150 ccid3_hc_rx_set_state(sk, TFRC_RSTATE_TERM);
1152 /* Empty packet history */
1153 dccp_rx_hist_purge(ccid3_rx_hist, &hcrx->ccid3hcrx_hist);
1155 /* Empty loss interval history */
1156 dccp_li_hist_purge(ccid3_li_hist, &hcrx->ccid3hcrx_li_hist);
1159 static void ccid3_hc_rx_get_info(struct sock *sk, struct tcp_info *info)
1161 const struct ccid3_hc_rx_sock *hcrx = ccid3_hc_rx_sk(sk);
1163 /* Listen socks doesn't have a private CCID block */
1164 if (sk->sk_state == DCCP_LISTEN)
1167 BUG_ON(hcrx == NULL);
1169 info->tcpi_ca_state = hcrx->ccid3hcrx_state;
1170 info->tcpi_options |= TCPI_OPT_TIMESTAMPS;
1171 info->tcpi_rcv_rtt = hcrx->ccid3hcrx_rtt;
1174 static int ccid3_hc_rx_getsockopt(struct sock *sk, const int optname, int len,
1175 u32 __user *optval, int __user *optlen)
1177 const struct ccid3_hc_rx_sock *hcrx = ccid3_hc_rx_sk(sk);
1180 /* Listen socks doesn't have a private CCID block */
1181 if (sk->sk_state == DCCP_LISTEN)
1185 case DCCP_SOCKOPT_CCID_RX_INFO:
1186 if (len < sizeof(hcrx->ccid3hcrx_tfrc))
1188 len = sizeof(hcrx->ccid3hcrx_tfrc);
1189 val = &hcrx->ccid3hcrx_tfrc;
1192 return -ENOPROTOOPT;
1195 if (put_user(len, optlen) || copy_to_user(optval, val, len))
1201 static struct ccid_operations ccid3 = {
1202 .ccid_id = DCCPC_CCID3,
1203 .ccid_name = "ccid3",
1204 .ccid_owner = THIS_MODULE,
1205 .ccid_hc_tx_obj_size = sizeof(struct ccid3_hc_tx_sock),
1206 .ccid_hc_tx_init = ccid3_hc_tx_init,
1207 .ccid_hc_tx_exit = ccid3_hc_tx_exit,
1208 .ccid_hc_tx_send_packet = ccid3_hc_tx_send_packet,
1209 .ccid_hc_tx_packet_sent = ccid3_hc_tx_packet_sent,
1210 .ccid_hc_tx_packet_recv = ccid3_hc_tx_packet_recv,
1211 .ccid_hc_tx_parse_options = ccid3_hc_tx_parse_options,
1212 .ccid_hc_rx_obj_size = sizeof(struct ccid3_hc_rx_sock),
1213 .ccid_hc_rx_init = ccid3_hc_rx_init,
1214 .ccid_hc_rx_exit = ccid3_hc_rx_exit,
1215 .ccid_hc_rx_insert_options = ccid3_hc_rx_insert_options,
1216 .ccid_hc_rx_packet_recv = ccid3_hc_rx_packet_recv,
1217 .ccid_hc_rx_get_info = ccid3_hc_rx_get_info,
1218 .ccid_hc_tx_get_info = ccid3_hc_tx_get_info,
1219 .ccid_hc_rx_getsockopt = ccid3_hc_rx_getsockopt,
1220 .ccid_hc_tx_getsockopt = ccid3_hc_tx_getsockopt,
1223 #ifdef CONFIG_IP_DCCP_CCID3_DEBUG
1224 module_param(ccid3_debug, int, 0444);
1225 MODULE_PARM_DESC(ccid3_debug, "Enable debug messages");
1228 static __init int ccid3_module_init(void)
1232 ccid3_rx_hist = dccp_rx_hist_new("ccid3");
1233 if (ccid3_rx_hist == NULL)
1236 ccid3_tx_hist = dccp_tx_hist_new("ccid3");
1237 if (ccid3_tx_hist == NULL)
1240 ccid3_li_hist = dccp_li_hist_new("ccid3");
1241 if (ccid3_li_hist == NULL)
1244 rc = ccid_register(&ccid3);
1246 goto out_free_loss_interval_history;
1250 out_free_loss_interval_history:
1251 dccp_li_hist_delete(ccid3_li_hist);
1252 ccid3_li_hist = NULL;
1254 dccp_tx_hist_delete(ccid3_tx_hist);
1255 ccid3_tx_hist = NULL;
1257 dccp_rx_hist_delete(ccid3_rx_hist);
1258 ccid3_rx_hist = NULL;
1261 module_init(ccid3_module_init);
1263 static __exit void ccid3_module_exit(void)
1265 ccid_unregister(&ccid3);
1267 if (ccid3_tx_hist != NULL) {
1268 dccp_tx_hist_delete(ccid3_tx_hist);
1269 ccid3_tx_hist = NULL;
1271 if (ccid3_rx_hist != NULL) {
1272 dccp_rx_hist_delete(ccid3_rx_hist);
1273 ccid3_rx_hist = NULL;
1275 if (ccid3_li_hist != NULL) {
1276 dccp_li_hist_delete(ccid3_li_hist);
1277 ccid3_li_hist = NULL;
1280 module_exit(ccid3_module_exit);
1282 MODULE_AUTHOR("Ian McDonald <ian.mcdonald@jandi.co.nz>, "
1283 "Arnaldo Carvalho de Melo <acme@ghostprotocols.net>");
1284 MODULE_DESCRIPTION("DCCP TFRC CCID3 CCID");
1285 MODULE_LICENSE("GPL");
1286 MODULE_ALIAS("net-dccp-ccid-3");