2 * net/dccp/ccids/ccid3.c
4 * Copyright (c) 2007 The University of Aberdeen, Scotland, UK
5 * Copyright (c) 2005-7 The University of Waikato, Hamilton, New Zealand.
6 * Copyright (c) 2005-7 Ian McDonald <ian.mcdonald@jandi.co.nz>
8 * An implementation of the DCCP protocol
10 * This code has been developed by the University of Waikato WAND
11 * research group. For further information please see http://www.wand.net.nz/
13 * This code also uses code from Lulea University, rereleased as GPL by its
15 * Copyright (c) 2003 Nils-Erik Mattsson, Joacim Haggmark, Magnus Erixzon
17 * Changes to meet Linux coding standards, to make it meet latest ccid3 draft
18 * and to make it work as a loadable module in the DCCP stack written by
19 * Arnaldo Carvalho de Melo <acme@conectiva.com.br>.
21 * Copyright (c) 2005 Arnaldo Carvalho de Melo <acme@conectiva.com.br>
23 * This program is free software; you can redistribute it and/or modify
24 * it under the terms of the GNU General Public License as published by
25 * the Free Software Foundation; either version 2 of the License, or
26 * (at your option) any later version.
28 * This program is distributed in the hope that it will be useful,
29 * but WITHOUT ANY WARRANTY; without even the implied warranty of
30 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
31 * GNU General Public License for more details.
33 * You should have received a copy of the GNU General Public License
34 * along with this program; if not, write to the Free Software
35 * Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
40 #include <asm/unaligned.h>
42 #ifdef CONFIG_IP_DCCP_CCID3_DEBUG
43 static int ccid3_debug;
44 #define ccid3_pr_debug(format, a...) DCCP_PR_DEBUG(ccid3_debug, format, ##a)
46 #define ccid3_pr_debug(format, a...)
50 * Transmitter Half-Connection Routines
52 #ifdef CONFIG_IP_DCCP_CCID3_DEBUG
53 static const char *ccid3_tx_state_name(enum ccid3_hc_tx_states state)
55 static char *ccid3_state_names[] = {
56 [TFRC_SSTATE_NO_SENT] = "NO_SENT",
57 [TFRC_SSTATE_NO_FBACK] = "NO_FBACK",
58 [TFRC_SSTATE_FBACK] = "FBACK",
59 [TFRC_SSTATE_TERM] = "TERM",
62 return ccid3_state_names[state];
66 static void ccid3_hc_tx_set_state(struct sock *sk,
67 enum ccid3_hc_tx_states state)
69 struct ccid3_hc_tx_sock *hctx = ccid3_hc_tx_sk(sk);
70 enum ccid3_hc_tx_states oldstate = hctx->ccid3hctx_state;
72 ccid3_pr_debug("%s(%p) %-8.8s -> %s\n",
73 dccp_role(sk), sk, ccid3_tx_state_name(oldstate),
74 ccid3_tx_state_name(state));
75 WARN_ON(state == oldstate);
76 hctx->ccid3hctx_state = state;
80 * Compute the initial sending rate X_init in the manner of RFC 3390:
82 * X_init = min(4 * s, max(2 * s, 4380 bytes)) / RTT
84 * Note that RFC 3390 uses MSS, RFC 4342 refers to RFC 3390, and rfc3448bis
85 * (rev-02) clarifies the use of RFC 3390 with regard to the above formula.
86 * For consistency with other parts of the code, X_init is scaled by 2^6.
88 static inline u64 rfc3390_initial_rate(struct sock *sk)
90 const struct ccid3_hc_tx_sock *hctx = ccid3_hc_tx_sk(sk);
91 const __u32 w_init = min_t(__u32, 4 * hctx->ccid3hctx_s,
92 max_t(__u32, 2 * hctx->ccid3hctx_s, 4380));
94 return scaled_div(w_init << 6, hctx->ccid3hctx_rtt);
98 * Recalculate t_ipi and delta (should be called whenever X changes)
100 static void ccid3_update_send_interval(struct ccid3_hc_tx_sock *hctx)
102 /* Calculate new t_ipi = s / X_inst (X_inst is in 64 * bytes/second) */
103 hctx->ccid3hctx_t_ipi = scaled_div32(((u64)hctx->ccid3hctx_s) << 6,
106 /* Calculate new delta by delta = min(t_ipi / 2, t_gran / 2) */
107 hctx->ccid3hctx_delta = min_t(u32, hctx->ccid3hctx_t_ipi / 2,
108 TFRC_OPSYS_HALF_TIME_GRAN);
110 ccid3_pr_debug("t_ipi=%u, delta=%u, s=%u, X=%u\n",
111 hctx->ccid3hctx_t_ipi, hctx->ccid3hctx_delta,
112 hctx->ccid3hctx_s, (unsigned)(hctx->ccid3hctx_x >> 6));
116 static u32 ccid3_hc_tx_idle_rtt(struct ccid3_hc_tx_sock *hctx, ktime_t now)
118 u32 delta = ktime_us_delta(now, hctx->ccid3hctx_t_last_win_count);
120 return delta / hctx->ccid3hctx_rtt;
124 * ccid3_hc_tx_update_x - Update allowed sending rate X
125 * @stamp: most recent time if available - can be left NULL.
126 * This function tracks draft rfc3448bis, check there for latest details.
128 * Note: X and X_recv are both stored in units of 64 * bytes/second, to support
129 * fine-grained resolution of sending rates. This requires scaling by 2^6
130 * throughout the code. Only X_calc is unscaled (in bytes/second).
133 static void ccid3_hc_tx_update_x(struct sock *sk, ktime_t *stamp)
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;
138 ktime_t now = stamp ? *stamp : ktime_get_real();
141 * Handle IDLE periods: do not reduce below RFC3390 initial sending rate
142 * when idling [RFC 4342, 5.1]. Definition of idling is from rfc3448bis:
143 * a sender is idle if it has not sent anything over a 2-RTT-period.
144 * For consistency with X and X_recv, min_rate is also scaled by 2^6.
146 if (ccid3_hc_tx_idle_rtt(hctx, now) >= 2) {
147 min_rate = rfc3390_initial_rate(sk);
148 min_rate = max(min_rate, 2 * hctx->ccid3hctx_x_recv);
151 if (hctx->ccid3hctx_p > 0) {
153 hctx->ccid3hctx_x = min(((__u64)hctx->ccid3hctx_x_calc) << 6,
155 hctx->ccid3hctx_x = max(hctx->ccid3hctx_x,
156 (((__u64)hctx->ccid3hctx_s) << 6) /
159 } else if (ktime_us_delta(now, hctx->ccid3hctx_t_ld)
160 - (s64)hctx->ccid3hctx_rtt >= 0) {
163 max(min(2 * hctx->ccid3hctx_x, min_rate),
164 scaled_div(((__u64)hctx->ccid3hctx_s) << 6,
165 hctx->ccid3hctx_rtt));
166 hctx->ccid3hctx_t_ld = now;
169 if (hctx->ccid3hctx_x != old_x) {
170 ccid3_pr_debug("X_prev=%u, X_now=%u, X_calc=%u, "
171 "X_recv=%u\n", (unsigned)(old_x >> 6),
172 (unsigned)(hctx->ccid3hctx_x >> 6),
173 hctx->ccid3hctx_x_calc,
174 (unsigned)(hctx->ccid3hctx_x_recv >> 6));
176 ccid3_update_send_interval(hctx);
181 * Track the mean packet size `s' (cf. RFC 4342, 5.3 and RFC 3448, 4.1)
182 * @len: DCCP packet payload size in bytes
184 static inline void ccid3_hc_tx_update_s(struct ccid3_hc_tx_sock *hctx, int len)
186 const u16 old_s = hctx->ccid3hctx_s;
188 hctx->ccid3hctx_s = tfrc_ewma(hctx->ccid3hctx_s, len, 9);
190 if (hctx->ccid3hctx_s != old_s)
191 ccid3_update_send_interval(hctx);
195 * Update Window Counter using the algorithm from [RFC 4342, 8.1].
196 * The algorithm is not applicable if RTT < 4 microseconds.
198 static inline void ccid3_hc_tx_update_win_count(struct ccid3_hc_tx_sock *hctx,
203 if (unlikely(hctx->ccid3hctx_rtt < 4)) /* avoid divide-by-zero */
206 quarter_rtts = ktime_us_delta(now, hctx->ccid3hctx_t_last_win_count);
207 quarter_rtts /= hctx->ccid3hctx_rtt / 4;
209 if (quarter_rtts > 0) {
210 hctx->ccid3hctx_t_last_win_count = now;
211 hctx->ccid3hctx_last_win_count += min_t(u32, quarter_rtts, 5);
212 hctx->ccid3hctx_last_win_count &= 0xF; /* mod 16 */
216 static void ccid3_hc_tx_no_feedback_timer(unsigned long data)
218 struct sock *sk = (struct sock *)data;
219 struct ccid3_hc_tx_sock *hctx = ccid3_hc_tx_sk(sk);
220 unsigned long t_nfb = USEC_PER_SEC / 5;
223 if (sock_owned_by_user(sk)) {
224 /* Try again later. */
225 /* XXX: set some sensible MIB */
229 ccid3_pr_debug("%s(%p, state=%s) - entry \n", dccp_role(sk), sk,
230 ccid3_tx_state_name(hctx->ccid3hctx_state));
232 if (hctx->ccid3hctx_state == TFRC_SSTATE_FBACK)
233 ccid3_hc_tx_set_state(sk, TFRC_SSTATE_NO_FBACK);
234 else if (hctx->ccid3hctx_state != TFRC_SSTATE_NO_FBACK)
238 * Determine new allowed sending rate X as per draft rfc3448bis-00, 4.4
240 if (hctx->ccid3hctx_t_rto == 0 || /* no feedback received yet */
241 hctx->ccid3hctx_p == 0) {
243 /* halve send rate directly */
244 hctx->ccid3hctx_x = max(hctx->ccid3hctx_x / 2,
245 (((__u64)hctx->ccid3hctx_s) << 6) /
247 ccid3_update_send_interval(hctx);
250 * Modify the cached value of X_recv
252 * If (X_calc > 2 * X_recv)
253 * X_recv = max(X_recv / 2, s / (2 * t_mbi));
255 * X_recv = X_calc / 4;
257 * Note that X_recv is scaled by 2^6 while X_calc is not
259 BUG_ON(hctx->ccid3hctx_p && !hctx->ccid3hctx_x_calc);
261 if (hctx->ccid3hctx_x_calc > (hctx->ccid3hctx_x_recv >> 5))
262 hctx->ccid3hctx_x_recv =
263 max(hctx->ccid3hctx_x_recv / 2,
264 (((__u64)hctx->ccid3hctx_s) << 6) /
267 hctx->ccid3hctx_x_recv = hctx->ccid3hctx_x_calc;
268 hctx->ccid3hctx_x_recv <<= 4;
270 ccid3_hc_tx_update_x(sk, NULL);
272 ccid3_pr_debug("Reduced X to %llu/64 bytes/sec\n",
273 (unsigned long long)hctx->ccid3hctx_x);
276 * Set new timeout for the nofeedback timer.
277 * See comments in packet_recv() regarding the value of t_RTO.
279 if (unlikely(hctx->ccid3hctx_t_rto == 0)) /* no feedback yet */
280 t_nfb = TFRC_INITIAL_TIMEOUT;
282 t_nfb = max(hctx->ccid3hctx_t_rto, 2 * hctx->ccid3hctx_t_ipi);
285 sk_reset_timer(sk, &hctx->ccid3hctx_no_feedback_timer,
286 jiffies + usecs_to_jiffies(t_nfb));
294 * > 0: delay (in msecs) that should pass before actually sending
295 * = 0: can send immediately
296 * < 0: error condition; do not send packet
298 static int ccid3_hc_tx_send_packet(struct sock *sk, struct sk_buff *skb)
300 struct dccp_sock *dp = dccp_sk(sk);
301 struct ccid3_hc_tx_sock *hctx = ccid3_hc_tx_sk(sk);
302 ktime_t now = ktime_get_real();
306 * This function is called only for Data and DataAck packets. Sending
307 * zero-sized Data(Ack)s is theoretically possible, but for congestion
308 * control this case is pathological - ignore it.
310 if (unlikely(skb->len == 0))
313 switch (hctx->ccid3hctx_state) {
314 case TFRC_SSTATE_NO_SENT:
315 sk_reset_timer(sk, &hctx->ccid3hctx_no_feedback_timer,
317 usecs_to_jiffies(TFRC_INITIAL_TIMEOUT)));
318 hctx->ccid3hctx_last_win_count = 0;
319 hctx->ccid3hctx_t_last_win_count = now;
321 /* Set t_0 for initial packet */
322 hctx->ccid3hctx_t_nom = now;
324 hctx->ccid3hctx_s = skb->len;
327 * Use initial RTT sample when available: recommended by erratum
328 * to RFC 4342. This implements the initialisation procedure of
329 * draft rfc3448bis, section 4.2. Remember, X is scaled by 2^6.
331 if (dp->dccps_syn_rtt) {
332 ccid3_pr_debug("SYN RTT = %uus\n", dp->dccps_syn_rtt);
333 hctx->ccid3hctx_rtt = dp->dccps_syn_rtt;
334 hctx->ccid3hctx_x = rfc3390_initial_rate(sk);
335 hctx->ccid3hctx_t_ld = now;
337 /* Sender does not have RTT sample: X_pps = 1 pkt/sec */
338 hctx->ccid3hctx_x = hctx->ccid3hctx_s;
339 hctx->ccid3hctx_x <<= 6;
341 ccid3_update_send_interval(hctx);
343 ccid3_hc_tx_set_state(sk, TFRC_SSTATE_NO_FBACK);
345 case TFRC_SSTATE_NO_FBACK:
346 case TFRC_SSTATE_FBACK:
347 delay = ktime_us_delta(hctx->ccid3hctx_t_nom, now);
348 ccid3_pr_debug("delay=%ld\n", (long)delay);
350 * Scheduling of packet transmissions [RFC 3448, 4.6]
352 * if (t_now > t_nom - delta)
353 * // send the packet now
355 * // send the packet in (t_nom - t_now) milliseconds.
357 if (delay - (s64)hctx->ccid3hctx_delta >= 1000)
358 return (u32)delay / 1000L;
360 ccid3_hc_tx_update_win_count(hctx, now);
362 case TFRC_SSTATE_TERM:
363 DCCP_BUG("%s(%p) - Illegal state TERM", dccp_role(sk), sk);
367 /* prepare to send now (add options etc.) */
368 dp->dccps_hc_tx_insert_options = 1;
369 DCCP_SKB_CB(skb)->dccpd_ccval = hctx->ccid3hctx_last_win_count;
371 /* set the nominal send time for the next following packet */
372 hctx->ccid3hctx_t_nom = ktime_add_us(hctx->ccid3hctx_t_nom,
373 hctx->ccid3hctx_t_ipi);
377 static void ccid3_hc_tx_packet_sent(struct sock *sk, int more,
380 struct ccid3_hc_tx_sock *hctx = ccid3_hc_tx_sk(sk);
382 ccid3_hc_tx_update_s(hctx, len);
384 if (tfrc_tx_hist_add(&hctx->ccid3hctx_hist, dccp_sk(sk)->dccps_gss))
385 DCCP_CRIT("packet history - out of memory!");
388 static void ccid3_hc_tx_packet_recv(struct sock *sk, struct sk_buff *skb)
390 struct ccid3_hc_tx_sock *hctx = ccid3_hc_tx_sk(sk);
391 struct ccid3_options_received *opt_recv;
396 /* we are only interested in ACKs */
397 if (!(DCCP_SKB_CB(skb)->dccpd_type == DCCP_PKT_ACK ||
398 DCCP_SKB_CB(skb)->dccpd_type == DCCP_PKT_DATAACK))
400 /* ... and only in the established state */
401 if (hctx->ccid3hctx_state != TFRC_SSTATE_FBACK &&
402 hctx->ccid3hctx_state != TFRC_SSTATE_NO_FBACK)
405 opt_recv = &hctx->ccid3hctx_options_received;
406 now = ktime_get_real();
408 /* Estimate RTT from history if ACK number is valid */
409 r_sample = tfrc_tx_hist_rtt(hctx->ccid3hctx_hist,
410 DCCP_SKB_CB(skb)->dccpd_ack_seq, now);
412 DCCP_WARN("%s(%p): %s with bogus ACK-%llu\n", dccp_role(sk), sk,
413 dccp_packet_name(DCCP_SKB_CB(skb)->dccpd_type),
414 (unsigned long long)DCCP_SKB_CB(skb)->dccpd_ack_seq);
418 /* Update receive rate in units of 64 * bytes/second */
419 hctx->ccid3hctx_x_recv = opt_recv->ccid3or_receive_rate;
420 hctx->ccid3hctx_x_recv <<= 6;
422 /* Update loss event rate (which is scaled by 1e6) */
423 pinv = opt_recv->ccid3or_loss_event_rate;
424 if (pinv == ~0U || pinv == 0) /* see RFC 4342, 8.5 */
425 hctx->ccid3hctx_p = 0;
426 else /* can not exceed 100% */
427 hctx->ccid3hctx_p = scaled_div(1, pinv);
429 * Validate new RTT sample and update moving average
431 r_sample = dccp_sample_rtt(sk, r_sample);
432 hctx->ccid3hctx_rtt = tfrc_ewma(hctx->ccid3hctx_rtt, r_sample, 9);
434 * Update allowed sending rate X as per draft rfc3448bis-00, 4.2/3
436 if (hctx->ccid3hctx_state == TFRC_SSTATE_NO_FBACK) {
437 ccid3_hc_tx_set_state(sk, TFRC_SSTATE_FBACK);
439 if (hctx->ccid3hctx_t_rto == 0) {
441 * Initial feedback packet: Larger Initial Windows (4.2)
443 hctx->ccid3hctx_x = rfc3390_initial_rate(sk);
444 hctx->ccid3hctx_t_ld = now;
446 ccid3_update_send_interval(hctx);
448 goto done_computing_x;
449 } else if (hctx->ccid3hctx_p == 0) {
451 * First feedback after nofeedback timer expiry (4.3)
453 goto done_computing_x;
457 /* Update sending rate (step 4 of [RFC 3448, 4.3]) */
458 if (hctx->ccid3hctx_p > 0)
459 hctx->ccid3hctx_x_calc =
460 tfrc_calc_x(hctx->ccid3hctx_s,
463 ccid3_hc_tx_update_x(sk, &now);
466 ccid3_pr_debug("%s(%p), RTT=%uus (sample=%uus), s=%u, "
467 "p=%u, X_calc=%u, X_recv=%u, X=%u\n",
469 sk, hctx->ccid3hctx_rtt, r_sample,
470 hctx->ccid3hctx_s, hctx->ccid3hctx_p,
471 hctx->ccid3hctx_x_calc,
472 (unsigned)(hctx->ccid3hctx_x_recv >> 6),
473 (unsigned)(hctx->ccid3hctx_x >> 6));
475 /* unschedule no feedback timer */
476 sk_stop_timer(sk, &hctx->ccid3hctx_no_feedback_timer);
479 * As we have calculated new ipi, delta, t_nom it is possible
480 * that we now can send a packet, so wake up dccp_wait_for_ccid
482 sk->sk_write_space(sk);
485 * Update timeout interval for the nofeedback timer.
486 * We use a configuration option to increase the lower bound.
487 * This can help avoid triggering the nofeedback timer too
488 * often ('spinning') on LANs with small RTTs.
490 hctx->ccid3hctx_t_rto = max_t(u32, 4 * hctx->ccid3hctx_rtt,
491 (CONFIG_IP_DCCP_CCID3_RTO *
492 (USEC_PER_SEC / 1000)));
494 * Schedule no feedback timer to expire in
495 * max(t_RTO, 2 * s/X) = max(t_RTO, 2 * t_ipi)
497 t_nfb = max(hctx->ccid3hctx_t_rto, 2 * hctx->ccid3hctx_t_ipi);
499 ccid3_pr_debug("%s(%p), Scheduled no feedback timer to "
500 "expire in %lu jiffies (%luus)\n",
502 sk, usecs_to_jiffies(t_nfb), t_nfb);
504 sk_reset_timer(sk, &hctx->ccid3hctx_no_feedback_timer,
505 jiffies + usecs_to_jiffies(t_nfb));
508 static int ccid3_hc_tx_parse_options(struct sock *sk, unsigned char option,
509 unsigned char len, u16 idx,
510 unsigned char *value)
513 const struct dccp_sock *dp = dccp_sk(sk);
514 struct ccid3_hc_tx_sock *hctx = ccid3_hc_tx_sk(sk);
515 struct ccid3_options_received *opt_recv;
518 opt_recv = &hctx->ccid3hctx_options_received;
520 if (opt_recv->ccid3or_seqno != dp->dccps_gsr) {
521 opt_recv->ccid3or_seqno = dp->dccps_gsr;
522 opt_recv->ccid3or_loss_event_rate = ~0;
523 opt_recv->ccid3or_loss_intervals_idx = 0;
524 opt_recv->ccid3or_loss_intervals_len = 0;
525 opt_recv->ccid3or_receive_rate = 0;
529 case TFRC_OPT_LOSS_EVENT_RATE:
530 if (unlikely(len != 4)) {
531 DCCP_WARN("%s(%p), invalid len %d "
532 "for TFRC_OPT_LOSS_EVENT_RATE\n",
533 dccp_role(sk), sk, len);
536 opt_val = get_unaligned((__be32 *)value);
537 opt_recv->ccid3or_loss_event_rate = ntohl(opt_val);
538 ccid3_pr_debug("%s(%p), LOSS_EVENT_RATE=%u\n",
540 opt_recv->ccid3or_loss_event_rate);
543 case TFRC_OPT_LOSS_INTERVALS:
544 opt_recv->ccid3or_loss_intervals_idx = idx;
545 opt_recv->ccid3or_loss_intervals_len = len;
546 ccid3_pr_debug("%s(%p), LOSS_INTERVALS=(%u, %u)\n",
548 opt_recv->ccid3or_loss_intervals_idx,
549 opt_recv->ccid3or_loss_intervals_len);
551 case TFRC_OPT_RECEIVE_RATE:
552 if (unlikely(len != 4)) {
553 DCCP_WARN("%s(%p), invalid len %d "
554 "for TFRC_OPT_RECEIVE_RATE\n",
555 dccp_role(sk), sk, len);
558 opt_val = get_unaligned((__be32 *)value);
559 opt_recv->ccid3or_receive_rate = ntohl(opt_val);
560 ccid3_pr_debug("%s(%p), RECEIVE_RATE=%u\n",
562 opt_recv->ccid3or_receive_rate);
570 static int ccid3_hc_tx_init(struct ccid *ccid, struct sock *sk)
572 struct ccid3_hc_tx_sock *hctx = ccid_priv(ccid);
574 hctx->ccid3hctx_state = TFRC_SSTATE_NO_SENT;
575 hctx->ccid3hctx_hist = NULL;
576 setup_timer(&hctx->ccid3hctx_no_feedback_timer,
577 ccid3_hc_tx_no_feedback_timer, (unsigned long)sk);
582 static void ccid3_hc_tx_exit(struct sock *sk)
584 struct ccid3_hc_tx_sock *hctx = ccid3_hc_tx_sk(sk);
586 ccid3_hc_tx_set_state(sk, TFRC_SSTATE_TERM);
587 sk_stop_timer(sk, &hctx->ccid3hctx_no_feedback_timer);
589 tfrc_tx_hist_purge(&hctx->ccid3hctx_hist);
592 static void ccid3_hc_tx_get_info(struct sock *sk, struct tcp_info *info)
594 struct ccid3_hc_tx_sock *hctx;
596 /* Listen socks doesn't have a private CCID block */
597 if (sk->sk_state == DCCP_LISTEN)
600 hctx = ccid3_hc_tx_sk(sk);
601 info->tcpi_rto = hctx->ccid3hctx_t_rto;
602 info->tcpi_rtt = hctx->ccid3hctx_rtt;
605 static int ccid3_hc_tx_getsockopt(struct sock *sk, const int optname, int len,
606 u32 __user *optval, int __user *optlen)
608 const struct ccid3_hc_tx_sock *hctx;
611 /* Listen socks doesn't have a private CCID block */
612 if (sk->sk_state == DCCP_LISTEN)
615 hctx = ccid3_hc_tx_sk(sk);
617 case DCCP_SOCKOPT_CCID_TX_INFO:
618 if (len < sizeof(hctx->ccid3hctx_tfrc))
620 len = sizeof(hctx->ccid3hctx_tfrc);
621 val = &hctx->ccid3hctx_tfrc;
627 if (put_user(len, optlen) || copy_to_user(optval, val, len))
634 * Receiver Half-Connection Routines
637 /* CCID3 feedback types */
638 enum ccid3_fback_type {
639 CCID3_FBACK_NONE = 0,
641 CCID3_FBACK_PERIODIC,
642 CCID3_FBACK_PARAM_CHANGE
645 #ifdef CONFIG_IP_DCCP_CCID3_DEBUG
646 static const char *ccid3_rx_state_name(enum ccid3_hc_rx_states state)
648 static char *ccid3_rx_state_names[] = {
649 [TFRC_RSTATE_NO_DATA] = "NO_DATA",
650 [TFRC_RSTATE_DATA] = "DATA",
651 [TFRC_RSTATE_TERM] = "TERM",
654 return ccid3_rx_state_names[state];
658 static void ccid3_hc_rx_set_state(struct sock *sk,
659 enum ccid3_hc_rx_states state)
661 struct ccid3_hc_rx_sock *hcrx = ccid3_hc_rx_sk(sk);
662 enum ccid3_hc_rx_states oldstate = hcrx->ccid3hcrx_state;
664 ccid3_pr_debug("%s(%p) %-8.8s -> %s\n",
665 dccp_role(sk), sk, ccid3_rx_state_name(oldstate),
666 ccid3_rx_state_name(state));
667 WARN_ON(state == oldstate);
668 hcrx->ccid3hcrx_state = state;
671 static void ccid3_hc_rx_send_feedback(struct sock *sk,
672 const struct sk_buff *skb,
673 enum ccid3_fback_type fbtype)
675 struct ccid3_hc_rx_sock *hcrx = ccid3_hc_rx_sk(sk);
676 struct dccp_sock *dp = dccp_sk(sk);
680 if (unlikely(hcrx->ccid3hcrx_state == TFRC_RSTATE_TERM))
683 now = ktime_get_real();
686 case CCID3_FBACK_INITIAL:
687 hcrx->ccid3hcrx_x_recv = 0;
688 hcrx->ccid3hcrx_pinv = ~0U; /* see RFC 4342, 8.5 */
690 case CCID3_FBACK_PARAM_CHANGE:
692 * When parameters change (new loss or p > p_prev), we do not
693 * have a reliable estimate for R_m of [RFC 3448, 6.2] and so
694 * need to reuse the previous value of X_recv. However, when
695 * X_recv was 0 (due to early loss), this would kill X down to
696 * s/t_mbi (i.e. one packet in 64 seconds).
697 * To avoid such drastic reduction, we approximate X_recv as
698 * the number of bytes since last feedback.
699 * This is a safe fallback, since X is bounded above by X_calc.
701 if (hcrx->ccid3hcrx_x_recv > 0)
704 case CCID3_FBACK_PERIODIC:
705 delta = ktime_us_delta(now, hcrx->ccid3hcrx_tstamp_last_feedback);
707 DCCP_BUG("delta (%ld) <= 0", (long)delta);
709 hcrx->ccid3hcrx_x_recv =
710 scaled_div32(hcrx->ccid3hcrx_bytes_recv, delta);
716 ccid3_pr_debug("Interval %ldusec, X_recv=%u, 1/p=%u\n", (long)delta,
717 hcrx->ccid3hcrx_x_recv, hcrx->ccid3hcrx_pinv);
719 hcrx->ccid3hcrx_tstamp_last_feedback = now;
720 hcrx->ccid3hcrx_last_counter = dccp_hdr(skb)->dccph_ccval;
721 hcrx->ccid3hcrx_bytes_recv = 0;
723 dp->dccps_hc_rx_insert_options = 1;
727 static int ccid3_hc_rx_insert_options(struct sock *sk, struct sk_buff *skb)
729 const struct ccid3_hc_rx_sock *hcrx;
732 if (!(sk->sk_state == DCCP_OPEN || sk->sk_state == DCCP_PARTOPEN))
735 hcrx = ccid3_hc_rx_sk(sk);
737 if (dccp_packet_without_ack(skb))
740 x_recv = htonl(hcrx->ccid3hcrx_x_recv);
741 pinv = htonl(hcrx->ccid3hcrx_pinv);
743 if (dccp_insert_option(sk, skb, TFRC_OPT_LOSS_EVENT_RATE,
744 &pinv, sizeof(pinv)) ||
745 dccp_insert_option(sk, skb, TFRC_OPT_RECEIVE_RATE,
746 &x_recv, sizeof(x_recv)))
752 /** ccid3_first_li - Implements [RFC 3448, 6.3.1]
754 * Determine the length of the first loss interval via inverse lookup.
755 * Assume that X_recv can be computed by the throughput equation
759 * Find some p such that f(p) = fval; return 1/p (scaled).
761 static u32 ccid3_first_li(struct sock *sk)
763 struct ccid3_hc_rx_sock *hcrx = ccid3_hc_rx_sk(sk);
764 u32 x_recv, p, delta;
767 if (hcrx->ccid3hcrx_rtt == 0) {
768 DCCP_WARN("No RTT estimate available, using fallback RTT\n");
769 hcrx->ccid3hcrx_rtt = DCCP_FALLBACK_RTT;
772 delta = ktime_to_us(net_timedelta(hcrx->ccid3hcrx_tstamp_last_feedback));
773 x_recv = scaled_div32(hcrx->ccid3hcrx_bytes_recv, delta);
774 if (x_recv == 0) { /* would also trigger divide-by-zero */
775 DCCP_WARN("X_recv==0\n");
776 if ((x_recv = hcrx->ccid3hcrx_x_recv) == 0) {
777 DCCP_BUG("stored value of X_recv is zero");
782 fval = scaled_div(hcrx->ccid3hcrx_s, hcrx->ccid3hcrx_rtt);
783 fval = scaled_div32(fval, x_recv);
784 p = tfrc_calc_x_reverse_lookup(fval);
786 ccid3_pr_debug("%s(%p), receive rate=%u bytes/s, implied "
787 "loss rate=%u\n", dccp_role(sk), sk, x_recv, p);
789 return p == 0 ? ~0U : scaled_div(1, p);
792 static void ccid3_hc_rx_packet_recv(struct sock *sk, struct sk_buff *skb)
794 struct ccid3_hc_rx_sock *hcrx = ccid3_hc_rx_sk(sk);
795 enum ccid3_fback_type do_feedback = CCID3_FBACK_NONE;
796 const u32 ndp = dccp_sk(sk)->dccps_options_received.dccpor_ndp;
797 const bool is_data_packet = dccp_data_packet(skb);
799 if (unlikely(hcrx->ccid3hcrx_state == TFRC_RSTATE_NO_DATA)) {
800 if (is_data_packet) {
801 const u32 payload = skb->len - dccp_hdr(skb)->dccph_doff * 4;
802 do_feedback = CCID3_FBACK_INITIAL;
803 ccid3_hc_rx_set_state(sk, TFRC_RSTATE_DATA);
804 hcrx->ccid3hcrx_s = payload;
806 * Not necessary to update ccid3hcrx_bytes_recv here,
807 * since X_recv = 0 for the first feedback packet (cf.
808 * RFC 3448, 6.3) -- gerrit
814 if (tfrc_rx_hist_duplicate(&hcrx->ccid3hcrx_hist, skb))
815 return; /* done receiving */
817 if (is_data_packet) {
818 const u32 payload = skb->len - dccp_hdr(skb)->dccph_doff * 4;
820 * Update moving-average of s and the sum of received payload bytes
822 hcrx->ccid3hcrx_s = tfrc_ewma(hcrx->ccid3hcrx_s, payload, 9);
823 hcrx->ccid3hcrx_bytes_recv += payload;
827 * Handle pending losses and otherwise check for new loss
829 if (tfrc_rx_hist_loss_pending(&hcrx->ccid3hcrx_hist) &&
830 tfrc_rx_handle_loss(&hcrx->ccid3hcrx_hist,
831 &hcrx->ccid3hcrx_li_hist,
832 skb, ndp, ccid3_first_li, sk) ) {
833 do_feedback = CCID3_FBACK_PARAM_CHANGE;
837 if (tfrc_rx_hist_new_loss_indicated(&hcrx->ccid3hcrx_hist, skb, ndp))
841 * Handle data packets: RTT sampling and monitoring p
843 if (unlikely(!is_data_packet))
846 if (!tfrc_lh_is_initialised(&hcrx->ccid3hcrx_li_hist)) {
847 const u32 sample = tfrc_rx_hist_sample_rtt(&hcrx->ccid3hcrx_hist, skb);
849 * Empty loss history: no loss so far, hence p stays 0.
850 * Sample RTT values, since an RTT estimate is required for the
851 * computation of p when the first loss occurs; RFC 3448, 6.3.1.
854 hcrx->ccid3hcrx_rtt = tfrc_ewma(hcrx->ccid3hcrx_rtt, sample, 9);
856 } else if (tfrc_lh_update_i_mean(&hcrx->ccid3hcrx_li_hist, skb)) {
858 * Step (3) of [RFC 3448, 6.1]: Recompute I_mean and, if I_mean
859 * has decreased (resp. p has increased), send feedback now.
861 do_feedback = CCID3_FBACK_PARAM_CHANGE;
865 * Check if the periodic once-per-RTT feedback is due; RFC 4342, 10.3
867 if (SUB16(dccp_hdr(skb)->dccph_ccval, hcrx->ccid3hcrx_last_counter) > 3)
868 do_feedback = CCID3_FBACK_PERIODIC;
871 tfrc_rx_hist_add_packet(&hcrx->ccid3hcrx_hist, skb, ndp);
875 ccid3_hc_rx_send_feedback(sk, skb, do_feedback);
878 static int ccid3_hc_rx_init(struct ccid *ccid, struct sock *sk)
880 struct ccid3_hc_rx_sock *hcrx = ccid_priv(ccid);
882 hcrx->ccid3hcrx_state = TFRC_RSTATE_NO_DATA;
883 tfrc_lh_init(&hcrx->ccid3hcrx_li_hist);
884 return tfrc_rx_hist_alloc(&hcrx->ccid3hcrx_hist);
887 static void ccid3_hc_rx_exit(struct sock *sk)
889 struct ccid3_hc_rx_sock *hcrx = ccid3_hc_rx_sk(sk);
891 ccid3_hc_rx_set_state(sk, TFRC_RSTATE_TERM);
893 tfrc_rx_hist_purge(&hcrx->ccid3hcrx_hist);
894 tfrc_lh_cleanup(&hcrx->ccid3hcrx_li_hist);
897 static void ccid3_hc_rx_get_info(struct sock *sk, struct tcp_info *info)
899 const struct ccid3_hc_rx_sock *hcrx;
901 /* Listen socks doesn't have a private CCID block */
902 if (sk->sk_state == DCCP_LISTEN)
905 hcrx = ccid3_hc_rx_sk(sk);
906 info->tcpi_ca_state = hcrx->ccid3hcrx_state;
907 info->tcpi_options |= TCPI_OPT_TIMESTAMPS;
908 info->tcpi_rcv_rtt = hcrx->ccid3hcrx_rtt;
911 static int ccid3_hc_rx_getsockopt(struct sock *sk, const int optname, int len,
912 u32 __user *optval, int __user *optlen)
914 const struct ccid3_hc_rx_sock *hcrx;
915 struct tfrc_rx_info rx_info;
918 /* Listen socks doesn't have a private CCID block */
919 if (sk->sk_state == DCCP_LISTEN)
922 hcrx = ccid3_hc_rx_sk(sk);
924 case DCCP_SOCKOPT_CCID_RX_INFO:
925 if (len < sizeof(rx_info))
927 rx_info.tfrcrx_x_recv = hcrx->ccid3hcrx_x_recv;
928 rx_info.tfrcrx_rtt = hcrx->ccid3hcrx_rtt;
929 rx_info.tfrcrx_p = hcrx->ccid3hcrx_pinv == 0 ? ~0U :
930 scaled_div(1, hcrx->ccid3hcrx_pinv);
931 len = sizeof(rx_info);
938 if (put_user(len, optlen) || copy_to_user(optval, val, len))
944 static struct ccid_operations ccid3 = {
945 .ccid_id = DCCPC_CCID3,
946 .ccid_name = "TCP-Friendly Rate Control",
947 .ccid_owner = THIS_MODULE,
948 .ccid_hc_tx_obj_size = sizeof(struct ccid3_hc_tx_sock),
949 .ccid_hc_tx_init = ccid3_hc_tx_init,
950 .ccid_hc_tx_exit = ccid3_hc_tx_exit,
951 .ccid_hc_tx_send_packet = ccid3_hc_tx_send_packet,
952 .ccid_hc_tx_packet_sent = ccid3_hc_tx_packet_sent,
953 .ccid_hc_tx_packet_recv = ccid3_hc_tx_packet_recv,
954 .ccid_hc_tx_parse_options = ccid3_hc_tx_parse_options,
955 .ccid_hc_rx_obj_size = sizeof(struct ccid3_hc_rx_sock),
956 .ccid_hc_rx_init = ccid3_hc_rx_init,
957 .ccid_hc_rx_exit = ccid3_hc_rx_exit,
958 .ccid_hc_rx_insert_options = ccid3_hc_rx_insert_options,
959 .ccid_hc_rx_packet_recv = ccid3_hc_rx_packet_recv,
960 .ccid_hc_rx_get_info = ccid3_hc_rx_get_info,
961 .ccid_hc_tx_get_info = ccid3_hc_tx_get_info,
962 .ccid_hc_rx_getsockopt = ccid3_hc_rx_getsockopt,
963 .ccid_hc_tx_getsockopt = ccid3_hc_tx_getsockopt,
966 #ifdef CONFIG_IP_DCCP_CCID3_DEBUG
967 module_param(ccid3_debug, bool, 0444);
968 MODULE_PARM_DESC(ccid3_debug, "Enable debug messages");
971 static __init int ccid3_module_init(void)
973 return ccid_register(&ccid3);
975 module_init(ccid3_module_init);
977 static __exit void ccid3_module_exit(void)
979 ccid_unregister(&ccid3);
981 module_exit(ccid3_module_exit);
983 MODULE_AUTHOR("Ian McDonald <ian.mcdonald@jandi.co.nz>, "
984 "Arnaldo Carvalho de Melo <acme@ghostprotocols.net>");
985 MODULE_DESCRIPTION("DCCP TFRC CCID3 CCID");
986 MODULE_LICENSE("GPL");
987 MODULE_ALIAS("net-dccp-ccid-3");