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
54 * Compute the initial sending rate X_init in the manner of RFC 3390:
56 * X_init = min(4 * MPS, max(2 * MPS, 4380 bytes)) / RTT
58 * For consistency with other parts of the code, X_init is scaled by 2^6.
60 static inline u64 rfc3390_initial_rate(struct sock *sk)
62 const u32 mps = dccp_sk(sk)->dccps_mss_cache,
63 w_init = clamp(4380U, 2 * mps, 4 * mps);
65 return scaled_div(w_init << 6, ccid3_hc_tx_sk(sk)->rtt);
69 * ccid3_update_send_interval - Calculate new t_ipi = s / X_inst
70 * This respects the granularity of X_inst (64 * bytes/second).
72 static void ccid3_update_send_interval(struct ccid3_hc_tx_sock *hctx)
74 hctx->t_ipi = scaled_div32(((u64)hctx->s) << 6, hctx->x);
76 ccid3_pr_debug("t_ipi=%u, s=%u, X=%u\n", hctx->t_ipi,
77 hctx->s, (unsigned)(hctx->x >> 6));
80 static u32 ccid3_hc_tx_idle_rtt(struct ccid3_hc_tx_sock *hctx, ktime_t now)
82 u32 delta = ktime_us_delta(now, hctx->t_last_win_count);
84 return delta / hctx->rtt;
88 * ccid3_hc_tx_update_x - Update allowed sending rate X
89 * @stamp: most recent time if available - can be left NULL.
90 * This function tracks draft rfc3448bis, check there for latest details.
92 * Note: X and X_recv are both stored in units of 64 * bytes/second, to support
93 * fine-grained resolution of sending rates. This requires scaling by 2^6
94 * throughout the code. Only X_calc is unscaled (in bytes/second).
97 static void ccid3_hc_tx_update_x(struct sock *sk, ktime_t *stamp)
99 struct ccid3_hc_tx_sock *hctx = ccid3_hc_tx_sk(sk);
100 u64 min_rate = 2 * hctx->x_recv;
101 const u64 old_x = hctx->x;
102 ktime_t now = stamp ? *stamp : ktime_get_real();
105 * Handle IDLE periods: do not reduce below RFC3390 initial sending rate
106 * when idling [RFC 4342, 5.1]. Definition of idling is from rfc3448bis:
107 * a sender is idle if it has not sent anything over a 2-RTT-period.
108 * For consistency with X and X_recv, min_rate is also scaled by 2^6.
110 if (ccid3_hc_tx_idle_rtt(hctx, now) >= 2) {
111 min_rate = rfc3390_initial_rate(sk);
112 min_rate = max(min_rate, 2 * hctx->x_recv);
117 hctx->x = min(((u64)hctx->x_calc) << 6, min_rate);
118 hctx->x = max(hctx->x, (((u64)hctx->s) << 6) / TFRC_T_MBI);
120 } else if (ktime_us_delta(now, hctx->t_ld) - (s64)hctx->rtt >= 0) {
122 hctx->x = min(2 * hctx->x, min_rate);
123 hctx->x = max(hctx->x,
124 scaled_div(((u64)hctx->s) << 6, hctx->rtt));
128 if (hctx->x != old_x) {
129 ccid3_pr_debug("X_prev=%u, X_now=%u, X_calc=%u, "
130 "X_recv=%u\n", (unsigned)(old_x >> 6),
131 (unsigned)(hctx->x >> 6), hctx->x_calc,
132 (unsigned)(hctx->x_recv >> 6));
134 ccid3_update_send_interval(hctx);
139 * ccid3_hc_tx_measure_packet_size - Measuring the packet size `s' (sec 4.1)
140 * @new_len: DCCP payload size in bytes (not used by all methods)
142 static u32 ccid3_hc_tx_measure_packet_size(struct sock *sk, const u16 new_len)
144 #if defined(CONFIG_IP_DCCP_CCID3_MEASURE_S_AS_AVG)
145 return tfrc_ewma(ccid3_hc_tx_sk(sk)->s, new_len, 9);
146 #elif defined(CONFIG_IP_DCCP_CCID3_MEASURE_S_AS_MAX)
147 return max(ccid3_hc_tx_sk(sk)->s, new_len);
148 #else /* CONFIG_IP_DCCP_CCID3_MEASURE_S_AS_MPS */
149 return dccp_sk(sk)->dccps_mss_cache;
154 * Update Window Counter using the algorithm from [RFC 4342, 8.1].
155 * As elsewhere, RTT > 0 is assumed by using dccp_sample_rtt().
157 static inline void ccid3_hc_tx_update_win_count(struct ccid3_hc_tx_sock *hctx,
160 u32 delta = ktime_us_delta(now, hctx->t_last_win_count),
161 quarter_rtts = (4 * delta) / hctx->rtt;
163 if (quarter_rtts > 0) {
164 hctx->t_last_win_count = now;
165 hctx->last_win_count += min(quarter_rtts, 5U);
166 hctx->last_win_count &= 0xF; /* mod 16 */
170 static void ccid3_hc_tx_no_feedback_timer(unsigned long data)
172 struct sock *sk = (struct sock *)data;
173 struct ccid3_hc_tx_sock *hctx = ccid3_hc_tx_sk(sk);
174 unsigned long t_nfb = USEC_PER_SEC / 5;
177 if (sock_owned_by_user(sk)) {
178 /* Try again later. */
179 /* XXX: set some sensible MIB */
183 ccid3_pr_debug("%s(%p) entry with%s feedback\n", dccp_role(sk), sk,
184 hctx->feedback ? "" : "out");
186 /* Ignore and do not restart after leaving the established state */
187 if ((1 << sk->sk_state) & ~(DCCPF_OPEN | DCCPF_PARTOPEN))
190 /* Reset feedback state to "no feedback received" */
191 hctx->feedback = false;
194 * Determine new allowed sending rate X as per draft rfc3448bis-00, 4.4
195 * RTO is 0 if and only if no feedback has been received yet.
197 if (hctx->t_rto == 0 || hctx->p == 0) {
199 /* halve send rate directly */
200 hctx->x = max(hctx->x / 2, (((u64)hctx->s) << 6) / TFRC_T_MBI);
201 ccid3_update_send_interval(hctx);
204 * Modify the cached value of X_recv
206 * If (X_calc > 2 * X_recv)
207 * X_recv = max(X_recv / 2, s / (2 * t_mbi));
209 * X_recv = X_calc / 4;
211 * Note that X_recv is scaled by 2^6 while X_calc is not
213 BUG_ON(hctx->p && !hctx->x_calc);
215 if (hctx->x_calc > (hctx->x_recv >> 5))
217 max(hctx->x_recv / 2,
218 (((__u64)hctx->s) << 6) / (2 * TFRC_T_MBI));
220 hctx->x_recv = hctx->x_calc;
223 ccid3_hc_tx_update_x(sk, NULL);
225 ccid3_pr_debug("Reduced X to %llu/64 bytes/sec\n",
226 (unsigned long long)hctx->x);
229 * Set new timeout for the nofeedback timer.
230 * See comments in packet_recv() regarding the value of t_RTO.
232 if (unlikely(hctx->t_rto == 0)) /* no feedback received yet */
233 t_nfb = TFRC_INITIAL_TIMEOUT;
235 t_nfb = max(hctx->t_rto, 2 * hctx->t_ipi);
238 sk_reset_timer(sk, &hctx->no_feedback_timer,
239 jiffies + usecs_to_jiffies(t_nfb));
246 * ccid3_hc_tx_send_packet - Delay-based dequeueing of TX packets
247 * @skb: next packet candidate to send on @sk
248 * This function uses the convention of ccid_packet_dequeue_eval() and
249 * returns a millisecond-delay value between 0 and t_mbi = 64000 msec.
251 static int ccid3_hc_tx_send_packet(struct sock *sk, struct sk_buff *skb)
253 struct dccp_sock *dp = dccp_sk(sk);
254 struct ccid3_hc_tx_sock *hctx = ccid3_hc_tx_sk(sk);
255 ktime_t now = ktime_get_real();
259 * This function is called only for Data and DataAck packets. Sending
260 * zero-sized Data(Ack)s is theoretically possible, but for congestion
261 * control this case is pathological - ignore it.
263 if (unlikely(skb->len == 0))
267 sk_reset_timer(sk, &hctx->no_feedback_timer, (jiffies +
268 usecs_to_jiffies(TFRC_INITIAL_TIMEOUT)));
269 hctx->last_win_count = 0;
270 hctx->t_last_win_count = now;
272 /* Set t_0 for initial packet */
276 * Use initial RTT sample when available: recommended by erratum
277 * to RFC 4342. This implements the initialisation procedure of
278 * draft rfc3448bis, section 4.2. Remember, X is scaled by 2^6.
280 if (dp->dccps_syn_rtt) {
281 ccid3_pr_debug("SYN RTT = %uus\n", dp->dccps_syn_rtt);
282 hctx->rtt = dp->dccps_syn_rtt;
283 hctx->x = rfc3390_initial_rate(sk);
287 * Sender does not have RTT sample:
288 * - set fallback RTT (RFC 4340, 3.4) since a RTT value
289 * is needed in several parts (e.g. window counter);
290 * - set sending rate X_pps = 1pps as per RFC 3448, 4.2.
292 hctx->rtt = DCCP_FALLBACK_RTT;
293 hctx->x = dp->dccps_mss_cache;
297 /* Compute t_ipi = s / X */
298 hctx->s = ccid3_hc_tx_measure_packet_size(sk, skb->len);
299 ccid3_update_send_interval(hctx);
302 delay = ktime_us_delta(hctx->t_nom, now);
303 ccid3_pr_debug("delay=%ld\n", (long)delay);
305 * Scheduling of packet transmissions [RFC 3448, 4.6]
307 * if (t_now > t_nom - delta)
308 * // send the packet now
310 * // send the packet in (t_nom - t_now) milliseconds.
312 if (delay >= TFRC_T_DELTA)
313 return (u32)delay / USEC_PER_MSEC;
315 ccid3_hc_tx_update_win_count(hctx, now);
318 /* prepare to send now (add options etc.) */
319 dp->dccps_hc_tx_insert_options = 1;
320 DCCP_SKB_CB(skb)->dccpd_ccval = hctx->last_win_count;
322 /* set the nominal send time for the next following packet */
323 hctx->t_nom = ktime_add_us(hctx->t_nom, hctx->t_ipi);
324 return CCID_PACKET_SEND_AT_ONCE;
327 static void ccid3_hc_tx_packet_sent(struct sock *sk, unsigned int len)
329 struct ccid3_hc_tx_sock *hctx = ccid3_hc_tx_sk(sk);
331 /* Changes to s will become effective the next time X is computed */
332 hctx->s = ccid3_hc_tx_measure_packet_size(sk, len);
334 if (tfrc_tx_hist_add(&hctx->hist, dccp_sk(sk)->dccps_gss))
335 DCCP_CRIT("packet history - out of memory!");
338 static void ccid3_hc_tx_packet_recv(struct sock *sk, struct sk_buff *skb)
340 struct ccid3_hc_tx_sock *hctx = ccid3_hc_tx_sk(sk);
341 struct tfrc_tx_hist_entry *acked;
346 /* we are only interested in ACKs */
347 if (!(DCCP_SKB_CB(skb)->dccpd_type == DCCP_PKT_ACK ||
348 DCCP_SKB_CB(skb)->dccpd_type == DCCP_PKT_DATAACK))
351 * Locate the acknowledged packet in the TX history.
353 * Returning "entry not found" here can for instance happen when
354 * - the host has not sent out anything (e.g. a passive server),
355 * - the Ack is outdated (packet with higher Ack number was received),
356 * - it is a bogus Ack (for a packet not sent on this connection).
358 acked = tfrc_tx_hist_find_entry(hctx->hist, dccp_hdr_ack_seq(skb));
361 /* For the sake of RTT sampling, ignore/remove all older entries */
362 tfrc_tx_hist_purge(&acked->next);
364 /* Update the moving average for the RTT estimate (RFC 3448, 4.3) */
365 now = ktime_get_real();
366 r_sample = dccp_sample_rtt(sk, ktime_us_delta(now, acked->stamp));
367 hctx->rtt = tfrc_ewma(hctx->rtt, r_sample, 9);
370 * Update allowed sending rate X as per draft rfc3448bis-00, 4.2/3
372 if (!hctx->feedback) {
373 hctx->feedback = true;
375 if (hctx->t_rto == 0) {
377 * Initial feedback packet: Larger Initial Windows (4.2)
379 hctx->x = rfc3390_initial_rate(sk);
382 ccid3_update_send_interval(hctx);
384 goto done_computing_x;
385 } else if (hctx->p == 0) {
387 * First feedback after nofeedback timer expiry (4.3)
389 goto done_computing_x;
393 /* Update sending rate (step 4 of [RFC 3448, 4.3]) */
395 hctx->x_calc = tfrc_calc_x(hctx->s, hctx->rtt, hctx->p);
396 ccid3_hc_tx_update_x(sk, &now);
399 ccid3_pr_debug("%s(%p), RTT=%uus (sample=%uus), s=%u, "
400 "p=%u, X_calc=%u, X_recv=%u, X=%u\n",
401 dccp_role(sk), sk, hctx->rtt, r_sample,
402 hctx->s, hctx->p, hctx->x_calc,
403 (unsigned)(hctx->x_recv >> 6),
404 (unsigned)(hctx->x >> 6));
406 /* unschedule no feedback timer */
407 sk_stop_timer(sk, &hctx->no_feedback_timer);
410 * As we have calculated new ipi, delta, t_nom it is possible
411 * that we now can send a packet, so wake up dccp_wait_for_ccid
413 sk->sk_write_space(sk);
416 * Update timeout interval for the nofeedback timer.
417 * We use a configuration option to increase the lower bound.
418 * This can help avoid triggering the nofeedback timer too
419 * often ('spinning') on LANs with small RTTs.
421 hctx->t_rto = max_t(u32, 4 * hctx->rtt, (CONFIG_IP_DCCP_CCID3_RTO *
422 (USEC_PER_SEC / 1000)));
424 * Schedule no feedback timer to expire in
425 * max(t_RTO, 2 * s/X) = max(t_RTO, 2 * t_ipi)
427 t_nfb = max(hctx->t_rto, 2 * hctx->t_ipi);
429 ccid3_pr_debug("%s(%p), Scheduled no feedback timer to "
430 "expire in %lu jiffies (%luus)\n",
431 dccp_role(sk), sk, usecs_to_jiffies(t_nfb), t_nfb);
433 sk_reset_timer(sk, &hctx->no_feedback_timer,
434 jiffies + usecs_to_jiffies(t_nfb));
437 static int ccid3_hc_tx_parse_options(struct sock *sk, u8 packet_type,
438 u8 option, u8 *optval, u8 optlen)
440 struct ccid3_hc_tx_sock *hctx = ccid3_hc_tx_sk(sk);
444 case TFRC_OPT_RECEIVE_RATE:
445 case TFRC_OPT_LOSS_EVENT_RATE:
446 /* Must be ignored on Data packets, cf. RFC 4342 8.3 and 8.5 */
447 if (packet_type == DCCP_PKT_DATA)
449 if (unlikely(optlen != 4)) {
450 DCCP_WARN("%s(%p), invalid len %d for %u\n",
451 dccp_role(sk), sk, optlen, option);
454 opt_val = ntohl(get_unaligned((__be32 *)optval));
456 if (option == TFRC_OPT_RECEIVE_RATE) {
457 /* Receive Rate is kept in units of 64 bytes/second */
458 hctx->x_recv = opt_val;
461 ccid3_pr_debug("%s(%p), RECEIVE_RATE=%u\n",
462 dccp_role(sk), sk, opt_val);
464 /* Update the fixpoint Loss Event Rate fraction */
465 hctx->p = tfrc_invert_loss_event_rate(opt_val);
467 ccid3_pr_debug("%s(%p), LOSS_EVENT_RATE=%u\n",
468 dccp_role(sk), sk, opt_val);
474 static int ccid3_hc_tx_init(struct ccid *ccid, struct sock *sk)
476 struct ccid3_hc_tx_sock *hctx = ccid_priv(ccid);
479 setup_timer(&hctx->no_feedback_timer,
480 ccid3_hc_tx_no_feedback_timer, (unsigned long)sk);
484 static void ccid3_hc_tx_exit(struct sock *sk)
486 struct ccid3_hc_tx_sock *hctx = ccid3_hc_tx_sk(sk);
488 sk_stop_timer(sk, &hctx->no_feedback_timer);
489 tfrc_tx_hist_purge(&hctx->hist);
492 static void ccid3_hc_tx_get_info(struct sock *sk, struct tcp_info *info)
494 info->tcpi_rto = ccid3_hc_tx_sk(sk)->t_rto;
495 info->tcpi_rtt = ccid3_hc_tx_sk(sk)->rtt;
498 static int ccid3_hc_tx_getsockopt(struct sock *sk, const int optname, int len,
499 u32 __user *optval, int __user *optlen)
501 const struct ccid3_hc_tx_sock *hctx = ccid3_hc_tx_sk(sk);
502 struct tfrc_tx_info tfrc;
506 case DCCP_SOCKOPT_CCID_TX_INFO:
507 if (len < sizeof(tfrc))
509 tfrc.tfrctx_x = hctx->x;
510 tfrc.tfrctx_x_recv = hctx->x_recv;
511 tfrc.tfrctx_x_calc = hctx->x_calc;
512 tfrc.tfrctx_rtt = hctx->rtt;
513 tfrc.tfrctx_p = hctx->p;
514 tfrc.tfrctx_rto = hctx->t_rto;
515 tfrc.tfrctx_ipi = hctx->t_ipi;
523 if (put_user(len, optlen) || copy_to_user(optval, val, len))
530 * Receiver Half-Connection Routines
532 static void ccid3_hc_rx_send_feedback(struct sock *sk,
533 const struct sk_buff *skb,
534 enum ccid3_fback_type fbtype)
536 struct ccid3_hc_rx_sock *hcrx = ccid3_hc_rx_sk(sk);
539 case CCID3_FBACK_INITIAL:
541 hcrx->p_inverse = ~0U; /* see RFC 4342, 8.5 */
543 case CCID3_FBACK_PARAM_CHANGE:
544 if (unlikely(hcrx->feedback == CCID3_FBACK_NONE)) {
546 * rfc3448bis-06, 6.3.1: First packet(s) lost or marked
547 * FIXME: in rfc3448bis the receiver returns X_recv=0
548 * here as it normally would in the first feedback packet.
549 * However this is not possible yet, since the code still
550 * uses RFC 3448, i.e.
552 * Calculate X_calc using the TCP throughput equation.
553 * X = max(min(X_calc, 2*X_recv), s/t_mbi);
554 * would bring X down to s/t_mbi. That is why we return
555 * X_recv according to rfc3448bis-06 for the moment.
557 u32 s = tfrc_rx_hist_packet_size(&hcrx->hist),
558 rtt = tfrc_rx_hist_rtt(&hcrx->hist);
560 hcrx->x_recv = scaled_div32(s, 2 * rtt);
564 * When parameters change (new loss or p > p_prev), we do not
565 * have a reliable estimate for R_m of [RFC 3448, 6.2] and so
566 * always check whether at least RTT time units were covered.
568 hcrx->x_recv = tfrc_rx_hist_x_recv(&hcrx->hist, hcrx->x_recv);
570 case CCID3_FBACK_PERIODIC:
572 * Step (2) of rfc3448bis-06, 6.2:
573 * - if no data packets have been received, just restart timer
574 * - if data packets have been received, re-compute X_recv
576 if (hcrx->hist.bytes_recvd == 0)
577 goto prepare_for_next_time;
578 hcrx->x_recv = tfrc_rx_hist_x_recv(&hcrx->hist, hcrx->x_recv);
584 ccid3_pr_debug("X_recv=%u, 1/p=%u\n", hcrx->x_recv, hcrx->p_inverse);
586 dccp_sk(sk)->dccps_hc_rx_insert_options = 1;
589 prepare_for_next_time:
590 tfrc_rx_hist_restart_byte_counter(&hcrx->hist);
591 hcrx->last_counter = dccp_hdr(skb)->dccph_ccval;
592 hcrx->feedback = fbtype;
595 static int ccid3_hc_rx_insert_options(struct sock *sk, struct sk_buff *skb)
597 const struct ccid3_hc_rx_sock *hcrx = ccid3_hc_rx_sk(sk);
600 if (!(sk->sk_state == DCCP_OPEN || sk->sk_state == DCCP_PARTOPEN))
603 if (dccp_packet_without_ack(skb))
606 x_recv = htonl(hcrx->x_recv);
607 pinv = htonl(hcrx->p_inverse);
609 if (dccp_insert_option(sk, skb, TFRC_OPT_LOSS_EVENT_RATE,
610 &pinv, sizeof(pinv)) ||
611 dccp_insert_option(sk, skb, TFRC_OPT_RECEIVE_RATE,
612 &x_recv, sizeof(x_recv)))
618 /** ccid3_first_li - Implements [RFC 3448, 6.3.1]
620 * Determine the length of the first loss interval via inverse lookup.
621 * Assume that X_recv can be computed by the throughput equation
625 * Find some p such that f(p) = fval; return 1/p (scaled).
627 static u32 ccid3_first_li(struct sock *sk)
629 struct ccid3_hc_rx_sock *hcrx = ccid3_hc_rx_sk(sk);
630 u32 s = tfrc_rx_hist_packet_size(&hcrx->hist),
631 rtt = tfrc_rx_hist_rtt(&hcrx->hist), x_recv, p;
635 * rfc3448bis-06, 6.3.1: First data packet(s) are marked or lost. Set p
636 * to give the equivalent of X_target = s/(2*R). Thus fval = 2 and so p
637 * is about 20.64%. This yields an interval length of 4.84 (rounded up).
639 if (unlikely(hcrx->feedback == CCID3_FBACK_NONE))
642 x_recv = tfrc_rx_hist_x_recv(&hcrx->hist, hcrx->x_recv);
646 fval = scaled_div32(scaled_div(s, rtt), x_recv);
647 p = tfrc_calc_x_reverse_lookup(fval);
649 ccid3_pr_debug("%s(%p), receive rate=%u bytes/s, implied "
650 "loss rate=%u\n", dccp_role(sk), sk, x_recv, p);
653 return scaled_div(1, p);
658 static void ccid3_hc_rx_packet_recv(struct sock *sk, struct sk_buff *skb)
660 struct ccid3_hc_rx_sock *hcrx = ccid3_hc_rx_sk(sk);
661 const u64 ndp = dccp_sk(sk)->dccps_options_received.dccpor_ndp;
662 const bool is_data_packet = dccp_data_packet(skb);
665 * Perform loss detection and handle pending losses
667 if (tfrc_rx_congestion_event(&hcrx->hist, &hcrx->li_hist,
668 skb, ndp, ccid3_first_li, sk))
669 ccid3_hc_rx_send_feedback(sk, skb, CCID3_FBACK_PARAM_CHANGE);
671 * Feedback for first non-empty data packet (RFC 3448, 6.3)
673 else if (unlikely(hcrx->feedback == CCID3_FBACK_NONE && is_data_packet))
674 ccid3_hc_rx_send_feedback(sk, skb, CCID3_FBACK_INITIAL);
676 * Check if the periodic once-per-RTT feedback is due; RFC 4342, 10.3
678 else if (!tfrc_rx_hist_loss_pending(&hcrx->hist) && is_data_packet &&
679 SUB16(dccp_hdr(skb)->dccph_ccval, hcrx->last_counter) > 3)
680 ccid3_hc_rx_send_feedback(sk, skb, CCID3_FBACK_PERIODIC);
683 static int ccid3_hc_rx_init(struct ccid *ccid, struct sock *sk)
685 struct ccid3_hc_rx_sock *hcrx = ccid_priv(ccid);
687 tfrc_lh_init(&hcrx->li_hist);
688 return tfrc_rx_hist_init(&hcrx->hist, sk);
691 static void ccid3_hc_rx_exit(struct sock *sk)
693 struct ccid3_hc_rx_sock *hcrx = ccid3_hc_rx_sk(sk);
695 tfrc_rx_hist_purge(&hcrx->hist);
696 tfrc_lh_cleanup(&hcrx->li_hist);
699 static void ccid3_hc_rx_get_info(struct sock *sk, struct tcp_info *info)
701 info->tcpi_options |= TCPI_OPT_TIMESTAMPS;
702 info->tcpi_rcv_rtt = tfrc_rx_hist_rtt(&ccid3_hc_rx_sk(sk)->hist);
705 static int ccid3_hc_rx_getsockopt(struct sock *sk, const int optname, int len,
706 u32 __user *optval, int __user *optlen)
708 const struct ccid3_hc_rx_sock *hcrx = ccid3_hc_rx_sk(sk);
709 struct tfrc_rx_info rx_info;
713 case DCCP_SOCKOPT_CCID_RX_INFO:
714 if (len < sizeof(rx_info))
716 rx_info.tfrcrx_x_recv = hcrx->x_recv;
717 rx_info.tfrcrx_rtt = tfrc_rx_hist_rtt(&hcrx->hist);
718 rx_info.tfrcrx_p = tfrc_invert_loss_event_rate(hcrx->p_inverse);
719 len = sizeof(rx_info);
726 if (put_user(len, optlen) || copy_to_user(optval, val, len))
732 static struct ccid_operations ccid3 = {
733 .ccid_id = DCCPC_CCID3,
734 .ccid_name = "TCP-Friendly Rate Control",
735 .ccid_owner = THIS_MODULE,
736 .ccid_hc_tx_obj_size = sizeof(struct ccid3_hc_tx_sock),
737 .ccid_hc_tx_init = ccid3_hc_tx_init,
738 .ccid_hc_tx_exit = ccid3_hc_tx_exit,
739 .ccid_hc_tx_send_packet = ccid3_hc_tx_send_packet,
740 .ccid_hc_tx_packet_sent = ccid3_hc_tx_packet_sent,
741 .ccid_hc_tx_packet_recv = ccid3_hc_tx_packet_recv,
742 .ccid_hc_tx_parse_options = ccid3_hc_tx_parse_options,
743 .ccid_hc_rx_obj_size = sizeof(struct ccid3_hc_rx_sock),
744 .ccid_hc_rx_init = ccid3_hc_rx_init,
745 .ccid_hc_rx_exit = ccid3_hc_rx_exit,
746 .ccid_hc_rx_insert_options = ccid3_hc_rx_insert_options,
747 .ccid_hc_rx_packet_recv = ccid3_hc_rx_packet_recv,
748 .ccid_hc_rx_get_info = ccid3_hc_rx_get_info,
749 .ccid_hc_tx_get_info = ccid3_hc_tx_get_info,
750 .ccid_hc_rx_getsockopt = ccid3_hc_rx_getsockopt,
751 .ccid_hc_tx_getsockopt = ccid3_hc_tx_getsockopt,
754 #ifdef CONFIG_IP_DCCP_CCID3_DEBUG
755 module_param(ccid3_debug, bool, 0644);
756 MODULE_PARM_DESC(ccid3_debug, "Enable debug messages");
759 static __init int ccid3_module_init(void)
764 * Without a fine-grained clock resolution, RTTs/X_recv are not sampled
765 * correctly and feedback is sent either too early or too late.
767 hrtimer_get_res(CLOCK_MONOTONIC, &tp);
768 if (tp.tv_sec || tp.tv_nsec > DCCP_TIME_RESOLUTION * NSEC_PER_USEC) {
769 printk(KERN_ERR "%s: Timer too coarse (%ld usec), need %u-usec"
770 " resolution - check your clocksource.\n", __func__,
771 tp.tv_nsec/NSEC_PER_USEC, DCCP_TIME_RESOLUTION);
772 return -ESOCKTNOSUPPORT;
774 return ccid_register(&ccid3);
776 module_init(ccid3_module_init);
778 static __exit void ccid3_module_exit(void)
780 ccid_unregister(&ccid3);
782 module_exit(ccid3_module_exit);
784 MODULE_AUTHOR("Ian McDonald <ian.mcdonald@jandi.co.nz>, "
785 "Arnaldo Carvalho de Melo <acme@ghostprotocols.net>");
786 MODULE_DESCRIPTION("DCCP TFRC CCID3 CCID");
787 MODULE_LICENSE("GPL");
788 MODULE_ALIAS("net-dccp-ccid-3");