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
->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
);
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
= clamp_t(__u32
, 4380U, 2 * hctx
->s
, 4 * hctx
->s
);
93 return scaled_div(w_init
<< 6, hctx
->rtt
);
97 * ccid3_update_send_interval - Calculate new t_ipi = s / X_inst
98 * This respects the granularity of X_inst (64 * bytes/second).
100 static void ccid3_update_send_interval(struct ccid3_hc_tx_sock
*hctx
)
102 hctx
->t_ipi
= scaled_div32(((u64
)hctx
->s
) << 6, hctx
->x
);
104 ccid3_pr_debug("t_ipi=%u, s=%u, X=%u\n", hctx
->t_ipi
,
105 hctx
->s
, (unsigned)(hctx
->x
>> 6));
108 static u32
ccid3_hc_tx_idle_rtt(struct ccid3_hc_tx_sock
*hctx
, ktime_t now
)
110 u32 delta
= ktime_us_delta(now
, hctx
->t_last_win_count
);
112 return delta
/ hctx
->rtt
;
116 * ccid3_hc_tx_update_x - Update allowed sending rate X
117 * @stamp: most recent time if available - can be left NULL.
118 * This function tracks draft rfc3448bis, check there for latest details.
120 * Note: X and X_recv are both stored in units of 64 * bytes/second, to support
121 * fine-grained resolution of sending rates. This requires scaling by 2^6
122 * throughout the code. Only X_calc is unscaled (in bytes/second).
125 static void ccid3_hc_tx_update_x(struct sock
*sk
, ktime_t
*stamp
)
127 struct ccid3_hc_tx_sock
*hctx
= ccid3_hc_tx_sk(sk
);
128 u64 min_rate
= 2 * hctx
->x_recv
;
129 const u64 old_x
= hctx
->x
;
130 ktime_t now
= stamp
? *stamp
: ktime_get_real();
133 * Handle IDLE periods: do not reduce below RFC3390 initial sending rate
134 * when idling [RFC 4342, 5.1]. Definition of idling is from rfc3448bis:
135 * a sender is idle if it has not sent anything over a 2-RTT-period.
136 * For consistency with X and X_recv, min_rate is also scaled by 2^6.
138 if (ccid3_hc_tx_idle_rtt(hctx
, now
) >= 2) {
139 min_rate
= rfc3390_initial_rate(sk
);
140 min_rate
= max(min_rate
, 2 * hctx
->x_recv
);
145 hctx
->x
= min(((u64
)hctx
->x_calc
) << 6, min_rate
);
146 hctx
->x
= max(hctx
->x
, (((u64
)hctx
->s
) << 6) / TFRC_T_MBI
);
148 } else if (ktime_us_delta(now
, hctx
->t_ld
) - (s64
)hctx
->rtt
>= 0) {
150 hctx
->x
= min(2 * hctx
->x
, min_rate
);
151 hctx
->x
= max(hctx
->x
,
152 scaled_div(((u64
)hctx
->s
) << 6, hctx
->rtt
));
156 if (hctx
->x
!= old_x
) {
157 ccid3_pr_debug("X_prev=%u, X_now=%u, X_calc=%u, "
158 "X_recv=%u\n", (unsigned)(old_x
>> 6),
159 (unsigned)(hctx
->x
>> 6), hctx
->x_calc
,
160 (unsigned)(hctx
->x_recv
>> 6));
162 ccid3_update_send_interval(hctx
);
167 * Track the mean packet size `s' (cf. RFC 4342, 5.3 and RFC 3448, 4.1)
168 * @len: DCCP packet payload size in bytes
170 static inline void ccid3_hc_tx_update_s(struct ccid3_hc_tx_sock
*hctx
, int len
)
172 const u16 old_s
= hctx
->s
;
174 hctx
->s
= tfrc_ewma(hctx
->s
, len
, 9);
176 if (hctx
->s
!= old_s
)
177 ccid3_update_send_interval(hctx
);
181 * Update Window Counter using the algorithm from [RFC 4342, 8.1].
182 * As elsewhere, RTT > 0 is assumed by using dccp_sample_rtt().
184 static inline void ccid3_hc_tx_update_win_count(struct ccid3_hc_tx_sock
*hctx
,
187 u32 delta
= ktime_us_delta(now
, hctx
->t_last_win_count
),
188 quarter_rtts
= (4 * delta
) / hctx
->rtt
;
190 if (quarter_rtts
> 0) {
191 hctx
->t_last_win_count
= now
;
192 hctx
->last_win_count
+= min(quarter_rtts
, 5U);
193 hctx
->last_win_count
&= 0xF; /* mod 16 */
197 static void ccid3_hc_tx_no_feedback_timer(unsigned long data
)
199 struct sock
*sk
= (struct sock
*)data
;
200 struct ccid3_hc_tx_sock
*hctx
= ccid3_hc_tx_sk(sk
);
201 unsigned long t_nfb
= USEC_PER_SEC
/ 5;
204 if (sock_owned_by_user(sk
)) {
205 /* Try again later. */
206 /* XXX: set some sensible MIB */
210 ccid3_pr_debug("%s(%p, state=%s) - entry \n", dccp_role(sk
), sk
,
211 ccid3_tx_state_name(hctx
->state
));
213 if (hctx
->state
== TFRC_SSTATE_FBACK
)
214 ccid3_hc_tx_set_state(sk
, TFRC_SSTATE_NO_FBACK
);
215 else if (hctx
->state
!= TFRC_SSTATE_NO_FBACK
)
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.
222 if (hctx
->t_rto
== 0 || hctx
->p
== 0) {
224 /* halve send rate directly */
225 hctx
->x
= max(hctx
->x
/ 2, (((u64
)hctx
->s
) << 6) / TFRC_T_MBI
);
226 ccid3_update_send_interval(hctx
);
229 * Modify the cached value of X_recv
231 * If (X_calc > 2 * X_recv)
232 * X_recv = max(X_recv / 2, s / (2 * t_mbi));
234 * X_recv = X_calc / 4;
236 * Note that X_recv is scaled by 2^6 while X_calc is not
238 BUG_ON(hctx
->p
&& !hctx
->x_calc
);
240 if (hctx
->x_calc
> (hctx
->x_recv
>> 5))
242 max(hctx
->x_recv
/ 2,
243 (((__u64
)hctx
->s
) << 6) / (2 * TFRC_T_MBI
));
245 hctx
->x_recv
= hctx
->x_calc
;
248 ccid3_hc_tx_update_x(sk
, NULL
);
250 ccid3_pr_debug("Reduced X to %llu/64 bytes/sec\n",
251 (unsigned long long)hctx
->x
);
254 * Set new timeout for the nofeedback timer.
255 * See comments in packet_recv() regarding the value of t_RTO.
257 if (unlikely(hctx
->t_rto
== 0)) /* no feedback received yet */
258 t_nfb
= TFRC_INITIAL_TIMEOUT
;
260 t_nfb
= max(hctx
->t_rto
, 2 * hctx
->t_ipi
);
263 sk_reset_timer(sk
, &hctx
->no_feedback_timer
,
264 jiffies
+ usecs_to_jiffies(t_nfb
));
272 * > 0: delay (in msecs) that should pass before actually sending
273 * = 0: can send immediately
274 * < 0: error condition; do not send packet
276 static int ccid3_hc_tx_send_packet(struct sock
*sk
, struct sk_buff
*skb
)
278 struct dccp_sock
*dp
= dccp_sk(sk
);
279 struct ccid3_hc_tx_sock
*hctx
= ccid3_hc_tx_sk(sk
);
280 ktime_t now
= ktime_get_real();
284 * This function is called only for Data and DataAck packets. Sending
285 * zero-sized Data(Ack)s is theoretically possible, but for congestion
286 * control this case is pathological - ignore it.
288 if (unlikely(skb
->len
== 0))
291 switch (hctx
->state
) {
292 case TFRC_SSTATE_NO_SENT
:
293 sk_reset_timer(sk
, &hctx
->no_feedback_timer
, (jiffies
+
294 usecs_to_jiffies(TFRC_INITIAL_TIMEOUT
)));
295 hctx
->last_win_count
= 0;
296 hctx
->t_last_win_count
= now
;
298 /* Set t_0 for initial packet */
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.
308 if (dp
->dccps_syn_rtt
) {
309 ccid3_pr_debug("SYN RTT = %uus\n", dp
->dccps_syn_rtt
);
310 hctx
->rtt
= dp
->dccps_syn_rtt
;
311 hctx
->x
= rfc3390_initial_rate(sk
);
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.
320 hctx
->rtt
= DCCP_FALLBACK_RTT
;
324 ccid3_update_send_interval(hctx
);
326 ccid3_hc_tx_set_state(sk
, TFRC_SSTATE_NO_FBACK
);
328 case TFRC_SSTATE_NO_FBACK
:
329 case TFRC_SSTATE_FBACK
:
330 delay
= ktime_us_delta(hctx
->t_nom
, now
);
331 ccid3_pr_debug("delay=%ld\n", (long)delay
);
333 * Scheduling of packet transmissions [RFC 3448, 4.6]
335 * if (t_now > t_nom - delta)
336 * // send the packet now
338 * // send the packet in (t_nom - t_now) milliseconds.
340 if (delay
>= TFRC_T_DELTA
)
341 return (u32
)delay
/ USEC_PER_MSEC
;
343 ccid3_hc_tx_update_win_count(hctx
, now
);
345 case TFRC_SSTATE_TERM
:
346 DCCP_BUG("%s(%p) - Illegal state TERM", dccp_role(sk
), sk
);
350 /* prepare to send now (add options etc.) */
351 dp
->dccps_hc_tx_insert_options
= 1;
352 DCCP_SKB_CB(skb
)->dccpd_ccval
= hctx
->last_win_count
;
354 /* set the nominal send time for the next following packet */
355 hctx
->t_nom
= ktime_add_us(hctx
->t_nom
, hctx
->t_ipi
);
359 static void ccid3_hc_tx_packet_sent(struct sock
*sk
, int more
,
362 struct ccid3_hc_tx_sock
*hctx
= ccid3_hc_tx_sk(sk
);
364 ccid3_hc_tx_update_s(hctx
, len
);
366 if (tfrc_tx_hist_add(&hctx
->hist
, dccp_sk(sk
)->dccps_gss
))
367 DCCP_CRIT("packet history - out of memory!");
370 static void ccid3_hc_tx_packet_recv(struct sock
*sk
, struct sk_buff
*skb
)
372 struct ccid3_hc_tx_sock
*hctx
= ccid3_hc_tx_sk(sk
);
373 struct ccid3_options_received
*opt_recv
= &hctx
->options_received
;
378 /* we are only interested in ACKs */
379 if (!(DCCP_SKB_CB(skb
)->dccpd_type
== DCCP_PKT_ACK
||
380 DCCP_SKB_CB(skb
)->dccpd_type
== DCCP_PKT_DATAACK
))
382 /* ... and only in the established state */
383 if (hctx
->state
!= TFRC_SSTATE_FBACK
&&
384 hctx
->state
!= TFRC_SSTATE_NO_FBACK
)
387 now
= ktime_get_real();
389 /* Estimate RTT from history if ACK number is valid */
390 r_sample
= tfrc_tx_hist_rtt(hctx
->hist
,
391 DCCP_SKB_CB(skb
)->dccpd_ack_seq
, now
);
393 DCCP_WARN("%s(%p): %s with bogus ACK-%llu\n", dccp_role(sk
), sk
,
394 dccp_packet_name(DCCP_SKB_CB(skb
)->dccpd_type
),
395 (unsigned long long)DCCP_SKB_CB(skb
)->dccpd_ack_seq
);
399 /* Update receive rate in units of 64 * bytes/second */
400 hctx
->x_recv
= opt_recv
->ccid3or_receive_rate
;
403 /* Update loss event rate (which is scaled by 1e6) */
404 pinv
= opt_recv
->ccid3or_loss_event_rate
;
405 if (pinv
== ~0U || pinv
== 0) /* see RFC 4342, 8.5 */
407 else /* can not exceed 100% */
408 hctx
->p
= scaled_div(1, pinv
);
410 * Validate new RTT sample and update moving average
412 r_sample
= dccp_sample_rtt(sk
, r_sample
);
413 hctx
->rtt
= tfrc_ewma(hctx
->rtt
, r_sample
, 9);
415 * Update allowed sending rate X as per draft rfc3448bis-00, 4.2/3
417 if (hctx
->state
== TFRC_SSTATE_NO_FBACK
) {
418 ccid3_hc_tx_set_state(sk
, TFRC_SSTATE_FBACK
);
420 if (hctx
->t_rto
== 0) {
422 * Initial feedback packet: Larger Initial Windows (4.2)
424 hctx
->x
= rfc3390_initial_rate(sk
);
427 ccid3_update_send_interval(hctx
);
429 goto done_computing_x
;
430 } else if (hctx
->p
== 0) {
432 * First feedback after nofeedback timer expiry (4.3)
434 goto done_computing_x
;
438 /* Update sending rate (step 4 of [RFC 3448, 4.3]) */
440 hctx
->x_calc
= tfrc_calc_x(hctx
->s
, hctx
->rtt
, hctx
->p
);
441 ccid3_hc_tx_update_x(sk
, &now
);
444 ccid3_pr_debug("%s(%p), RTT=%uus (sample=%uus), s=%u, "
445 "p=%u, X_calc=%u, X_recv=%u, X=%u\n",
446 dccp_role(sk
), sk
, hctx
->rtt
, r_sample
,
447 hctx
->s
, hctx
->p
, hctx
->x_calc
,
448 (unsigned)(hctx
->x_recv
>> 6),
449 (unsigned)(hctx
->x
>> 6));
451 /* unschedule no feedback timer */
452 sk_stop_timer(sk
, &hctx
->no_feedback_timer
);
455 * As we have calculated new ipi, delta, t_nom it is possible
456 * that we now can send a packet, so wake up dccp_wait_for_ccid
458 sk
->sk_write_space(sk
);
461 * Update timeout interval for the nofeedback timer.
462 * We use a configuration option to increase the lower bound.
463 * This can help avoid triggering the nofeedback timer too
464 * often ('spinning') on LANs with small RTTs.
466 hctx
->t_rto
= max_t(u32
, 4 * hctx
->rtt
, (CONFIG_IP_DCCP_CCID3_RTO
*
467 (USEC_PER_SEC
/ 1000)));
469 * Schedule no feedback timer to expire in
470 * max(t_RTO, 2 * s/X) = max(t_RTO, 2 * t_ipi)
472 t_nfb
= max(hctx
->t_rto
, 2 * hctx
->t_ipi
);
474 ccid3_pr_debug("%s(%p), Scheduled no feedback timer to "
475 "expire in %lu jiffies (%luus)\n",
476 dccp_role(sk
), sk
, usecs_to_jiffies(t_nfb
), t_nfb
);
478 sk_reset_timer(sk
, &hctx
->no_feedback_timer
,
479 jiffies
+ usecs_to_jiffies(t_nfb
));
482 static int ccid3_hc_tx_parse_options(struct sock
*sk
, unsigned char option
,
483 unsigned char len
, u16 idx
,
484 unsigned char *value
)
487 const struct dccp_sock
*dp
= dccp_sk(sk
);
488 struct ccid3_hc_tx_sock
*hctx
= ccid3_hc_tx_sk(sk
);
489 struct ccid3_options_received
*opt_recv
= &hctx
->options_received
;
492 if (opt_recv
->ccid3or_seqno
!= dp
->dccps_gsr
) {
493 opt_recv
->ccid3or_seqno
= dp
->dccps_gsr
;
494 opt_recv
->ccid3or_loss_event_rate
= ~0;
495 opt_recv
->ccid3or_loss_intervals_idx
= 0;
496 opt_recv
->ccid3or_loss_intervals_len
= 0;
497 opt_recv
->ccid3or_receive_rate
= 0;
501 case TFRC_OPT_LOSS_EVENT_RATE
:
502 if (unlikely(len
!= 4)) {
503 DCCP_WARN("%s(%p), invalid len %d "
504 "for TFRC_OPT_LOSS_EVENT_RATE\n",
505 dccp_role(sk
), sk
, len
);
508 opt_val
= get_unaligned((__be32
*)value
);
509 opt_recv
->ccid3or_loss_event_rate
= ntohl(opt_val
);
510 ccid3_pr_debug("%s(%p), LOSS_EVENT_RATE=%u\n",
512 opt_recv
->ccid3or_loss_event_rate
);
515 case TFRC_OPT_LOSS_INTERVALS
:
516 opt_recv
->ccid3or_loss_intervals_idx
= idx
;
517 opt_recv
->ccid3or_loss_intervals_len
= len
;
518 ccid3_pr_debug("%s(%p), LOSS_INTERVALS=(%u, %u)\n",
520 opt_recv
->ccid3or_loss_intervals_idx
,
521 opt_recv
->ccid3or_loss_intervals_len
);
523 case TFRC_OPT_RECEIVE_RATE
:
524 if (unlikely(len
!= 4)) {
525 DCCP_WARN("%s(%p), invalid len %d "
526 "for TFRC_OPT_RECEIVE_RATE\n",
527 dccp_role(sk
), sk
, len
);
530 opt_val
= get_unaligned((__be32
*)value
);
531 opt_recv
->ccid3or_receive_rate
= ntohl(opt_val
);
532 ccid3_pr_debug("%s(%p), RECEIVE_RATE=%u\n",
534 opt_recv
->ccid3or_receive_rate
);
542 static int ccid3_hc_tx_init(struct ccid
*ccid
, struct sock
*sk
)
544 struct ccid3_hc_tx_sock
*hctx
= ccid_priv(ccid
);
546 hctx
->state
= TFRC_SSTATE_NO_SENT
;
548 setup_timer(&hctx
->no_feedback_timer
,
549 ccid3_hc_tx_no_feedback_timer
, (unsigned long)sk
);
553 static void ccid3_hc_tx_exit(struct sock
*sk
)
555 struct ccid3_hc_tx_sock
*hctx
= ccid3_hc_tx_sk(sk
);
557 ccid3_hc_tx_set_state(sk
, TFRC_SSTATE_TERM
);
558 sk_stop_timer(sk
, &hctx
->no_feedback_timer
);
560 tfrc_tx_hist_purge(&hctx
->hist
);
563 static void ccid3_hc_tx_get_info(struct sock
*sk
, struct tcp_info
*info
)
565 info
->tcpi_rto
= ccid3_hc_tx_sk(sk
)->t_rto
;
566 info
->tcpi_rtt
= ccid3_hc_tx_sk(sk
)->rtt
;
569 static int ccid3_hc_tx_getsockopt(struct sock
*sk
, const int optname
, int len
,
570 u32 __user
*optval
, int __user
*optlen
)
572 const struct ccid3_hc_tx_sock
*hctx
= ccid3_hc_tx_sk(sk
);
573 struct tfrc_tx_info tfrc
;
577 case DCCP_SOCKOPT_CCID_TX_INFO
:
578 if (len
< sizeof(tfrc
))
580 tfrc
.tfrctx_x
= hctx
->x
;
581 tfrc
.tfrctx_x_recv
= hctx
->x_recv
;
582 tfrc
.tfrctx_x_calc
= hctx
->x_calc
;
583 tfrc
.tfrctx_rtt
= hctx
->rtt
;
584 tfrc
.tfrctx_p
= hctx
->p
;
585 tfrc
.tfrctx_rto
= hctx
->t_rto
;
586 tfrc
.tfrctx_ipi
= hctx
->t_ipi
;
594 if (put_user(len
, optlen
) || copy_to_user(optval
, val
, len
))
601 * Receiver Half-Connection Routines
604 /* CCID3 feedback types */
605 enum ccid3_fback_type
{
606 CCID3_FBACK_NONE
= 0,
608 CCID3_FBACK_PERIODIC
,
609 CCID3_FBACK_PARAM_CHANGE
612 #ifdef CONFIG_IP_DCCP_CCID3_DEBUG
613 static const char *ccid3_rx_state_name(enum ccid3_hc_rx_states state
)
615 static char *ccid3_rx_state_names
[] = {
616 [TFRC_RSTATE_NO_DATA
] = "NO_DATA",
617 [TFRC_RSTATE_DATA
] = "DATA",
618 [TFRC_RSTATE_TERM
] = "TERM",
621 return ccid3_rx_state_names
[state
];
625 static void ccid3_hc_rx_set_state(struct sock
*sk
,
626 enum ccid3_hc_rx_states state
)
628 struct ccid3_hc_rx_sock
*hcrx
= ccid3_hc_rx_sk(sk
);
629 enum ccid3_hc_rx_states oldstate
= hcrx
->state
;
631 ccid3_pr_debug("%s(%p) %-8.8s -> %s\n",
632 dccp_role(sk
), sk
, ccid3_rx_state_name(oldstate
),
633 ccid3_rx_state_name(state
));
634 WARN_ON(state
== oldstate
);
638 static void ccid3_hc_rx_send_feedback(struct sock
*sk
,
639 const struct sk_buff
*skb
,
640 enum ccid3_fback_type fbtype
)
642 struct ccid3_hc_rx_sock
*hcrx
= ccid3_hc_rx_sk(sk
);
643 struct dccp_sock
*dp
= dccp_sk(sk
);
647 if (unlikely(hcrx
->state
== TFRC_RSTATE_TERM
))
650 now
= ktime_get_real();
653 case CCID3_FBACK_INITIAL
:
655 hcrx
->p_inverse
= ~0U; /* see RFC 4342, 8.5 */
657 case CCID3_FBACK_PARAM_CHANGE
:
659 * When parameters change (new loss or p > p_prev), we do not
660 * have a reliable estimate for R_m of [RFC 3448, 6.2] and so
661 * need to reuse the previous value of X_recv. However, when
662 * X_recv was 0 (due to early loss), this would kill X down to
663 * s/t_mbi (i.e. one packet in 64 seconds).
664 * To avoid such drastic reduction, we approximate X_recv as
665 * the number of bytes since last feedback.
666 * This is a safe fallback, since X is bounded above by X_calc.
668 if (hcrx
->x_recv
> 0)
671 case CCID3_FBACK_PERIODIC
:
672 delta
= ktime_us_delta(now
, hcrx
->tstamp_last_feedback
);
674 DCCP_BUG("delta (%ld) <= 0", (long)delta
);
676 hcrx
->x_recv
= scaled_div32(hcrx
->bytes_recv
, delta
);
682 ccid3_pr_debug("Interval %ldusec, X_recv=%u, 1/p=%u\n",
683 (long)delta
, hcrx
->x_recv
, hcrx
->p_inverse
);
685 hcrx
->tstamp_last_feedback
= now
;
686 hcrx
->last_counter
= dccp_hdr(skb
)->dccph_ccval
;
687 hcrx
->bytes_recv
= 0;
689 dp
->dccps_hc_rx_insert_options
= 1;
693 static int ccid3_hc_rx_insert_options(struct sock
*sk
, struct sk_buff
*skb
)
695 const struct ccid3_hc_rx_sock
*hcrx
= ccid3_hc_rx_sk(sk
);
698 if (!(sk
->sk_state
== DCCP_OPEN
|| sk
->sk_state
== DCCP_PARTOPEN
))
701 if (dccp_packet_without_ack(skb
))
704 x_recv
= htonl(hcrx
->x_recv
);
705 pinv
= htonl(hcrx
->p_inverse
);
707 if (dccp_insert_option(sk
, skb
, TFRC_OPT_LOSS_EVENT_RATE
,
708 &pinv
, sizeof(pinv
)) ||
709 dccp_insert_option(sk
, skb
, TFRC_OPT_RECEIVE_RATE
,
710 &x_recv
, sizeof(x_recv
)))
716 /** ccid3_first_li - Implements [RFC 3448, 6.3.1]
718 * Determine the length of the first loss interval via inverse lookup.
719 * Assume that X_recv can be computed by the throughput equation
723 * Find some p such that f(p) = fval; return 1/p (scaled).
725 static u32
ccid3_first_li(struct sock
*sk
)
727 struct ccid3_hc_rx_sock
*hcrx
= ccid3_hc_rx_sk(sk
);
728 u32 x_recv
, p
, delta
;
731 if (hcrx
->rtt
== 0) {
732 DCCP_WARN("No RTT estimate available, using fallback RTT\n");
733 hcrx
->rtt
= DCCP_FALLBACK_RTT
;
736 delta
= ktime_to_us(net_timedelta(hcrx
->tstamp_last_feedback
));
737 x_recv
= scaled_div32(hcrx
->bytes_recv
, delta
);
738 if (x_recv
== 0) { /* would also trigger divide-by-zero */
739 DCCP_WARN("X_recv==0\n");
740 if (hcrx
->x_recv
== 0) {
741 DCCP_BUG("stored value of X_recv is zero");
744 x_recv
= hcrx
->x_recv
;
747 fval
= scaled_div(hcrx
->s
, hcrx
->rtt
);
748 fval
= scaled_div32(fval
, x_recv
);
749 p
= tfrc_calc_x_reverse_lookup(fval
);
751 ccid3_pr_debug("%s(%p), receive rate=%u bytes/s, implied "
752 "loss rate=%u\n", dccp_role(sk
), sk
, x_recv
, p
);
754 return p
== 0 ? ~0U : scaled_div(1, p
);
757 static void ccid3_hc_rx_packet_recv(struct sock
*sk
, struct sk_buff
*skb
)
759 struct ccid3_hc_rx_sock
*hcrx
= ccid3_hc_rx_sk(sk
);
760 enum ccid3_fback_type do_feedback
= CCID3_FBACK_NONE
;
761 const u64 ndp
= dccp_sk(sk
)->dccps_options_received
.dccpor_ndp
;
762 const bool is_data_packet
= dccp_data_packet(skb
);
764 if (unlikely(hcrx
->state
== TFRC_RSTATE_NO_DATA
)) {
765 if (is_data_packet
) {
766 const u32 payload
= skb
->len
- dccp_hdr(skb
)->dccph_doff
* 4;
767 do_feedback
= CCID3_FBACK_INITIAL
;
768 ccid3_hc_rx_set_state(sk
, TFRC_RSTATE_DATA
);
771 * Not necessary to update bytes_recv here,
772 * since X_recv = 0 for the first feedback packet (cf.
773 * RFC 3448, 6.3) -- gerrit
779 if (tfrc_rx_hist_duplicate(&hcrx
->hist
, skb
))
780 return; /* done receiving */
782 if (is_data_packet
) {
783 const u32 payload
= skb
->len
- dccp_hdr(skb
)->dccph_doff
* 4;
785 * Update moving-average of s and the sum of received payload bytes
787 hcrx
->s
= tfrc_ewma(hcrx
->s
, payload
, 9);
788 hcrx
->bytes_recv
+= payload
;
792 * Perform loss detection and handle pending losses
794 if (tfrc_rx_handle_loss(&hcrx
->hist
, &hcrx
->li_hist
,
795 skb
, ndp
, ccid3_first_li
, sk
)) {
796 do_feedback
= CCID3_FBACK_PARAM_CHANGE
;
800 if (tfrc_rx_hist_loss_pending(&hcrx
->hist
))
801 return; /* done receiving */
804 * Handle data packets: RTT sampling and monitoring p
806 if (unlikely(!is_data_packet
))
809 if (!tfrc_lh_is_initialised(&hcrx
->li_hist
)) {
810 const u32 sample
= tfrc_rx_hist_sample_rtt(&hcrx
->hist
, skb
);
812 * Empty loss history: no loss so far, hence p stays 0.
813 * Sample RTT values, since an RTT estimate is required for the
814 * computation of p when the first loss occurs; RFC 3448, 6.3.1.
817 hcrx
->rtt
= tfrc_ewma(hcrx
->rtt
, sample
, 9);
819 } else if (tfrc_lh_update_i_mean(&hcrx
->li_hist
, skb
)) {
821 * Step (3) of [RFC 3448, 6.1]: Recompute I_mean and, if I_mean
822 * has decreased (resp. p has increased), send feedback now.
824 do_feedback
= CCID3_FBACK_PARAM_CHANGE
;
828 * Check if the periodic once-per-RTT feedback is due; RFC 4342, 10.3
830 if (SUB16(dccp_hdr(skb
)->dccph_ccval
, hcrx
->last_counter
) > 3)
831 do_feedback
= CCID3_FBACK_PERIODIC
;
834 tfrc_rx_hist_add_packet(&hcrx
->hist
, skb
, ndp
);
838 ccid3_hc_rx_send_feedback(sk
, skb
, do_feedback
);
841 static int ccid3_hc_rx_init(struct ccid
*ccid
, struct sock
*sk
)
843 struct ccid3_hc_rx_sock
*hcrx
= ccid_priv(ccid
);
845 hcrx
->state
= TFRC_RSTATE_NO_DATA
;
846 tfrc_lh_init(&hcrx
->li_hist
);
847 return tfrc_rx_hist_alloc(&hcrx
->hist
);
850 static void ccid3_hc_rx_exit(struct sock
*sk
)
852 struct ccid3_hc_rx_sock
*hcrx
= ccid3_hc_rx_sk(sk
);
854 ccid3_hc_rx_set_state(sk
, TFRC_RSTATE_TERM
);
856 tfrc_rx_hist_purge(&hcrx
->hist
);
857 tfrc_lh_cleanup(&hcrx
->li_hist
);
860 static void ccid3_hc_rx_get_info(struct sock
*sk
, struct tcp_info
*info
)
862 info
->tcpi_ca_state
= ccid3_hc_rx_sk(sk
)->state
;
863 info
->tcpi_options
|= TCPI_OPT_TIMESTAMPS
;
864 info
->tcpi_rcv_rtt
= ccid3_hc_rx_sk(sk
)->rtt
;
867 static int ccid3_hc_rx_getsockopt(struct sock
*sk
, const int optname
, int len
,
868 u32 __user
*optval
, int __user
*optlen
)
870 const struct ccid3_hc_rx_sock
*hcrx
= ccid3_hc_rx_sk(sk
);
871 struct tfrc_rx_info rx_info
;
875 case DCCP_SOCKOPT_CCID_RX_INFO
:
876 if (len
< sizeof(rx_info
))
878 rx_info
.tfrcrx_x_recv
= hcrx
->x_recv
;
879 rx_info
.tfrcrx_rtt
= hcrx
->rtt
;
880 rx_info
.tfrcrx_p
= hcrx
->p_inverse
== 0 ? ~0U :
881 scaled_div(1, hcrx
->p_inverse
);
882 len
= sizeof(rx_info
);
889 if (put_user(len
, optlen
) || copy_to_user(optval
, val
, len
))
895 static struct ccid_operations ccid3
= {
896 .ccid_id
= DCCPC_CCID3
,
897 .ccid_name
= "TCP-Friendly Rate Control",
898 .ccid_owner
= THIS_MODULE
,
899 .ccid_hc_tx_obj_size
= sizeof(struct ccid3_hc_tx_sock
),
900 .ccid_hc_tx_init
= ccid3_hc_tx_init
,
901 .ccid_hc_tx_exit
= ccid3_hc_tx_exit
,
902 .ccid_hc_tx_send_packet
= ccid3_hc_tx_send_packet
,
903 .ccid_hc_tx_packet_sent
= ccid3_hc_tx_packet_sent
,
904 .ccid_hc_tx_packet_recv
= ccid3_hc_tx_packet_recv
,
905 .ccid_hc_tx_parse_options
= ccid3_hc_tx_parse_options
,
906 .ccid_hc_rx_obj_size
= sizeof(struct ccid3_hc_rx_sock
),
907 .ccid_hc_rx_init
= ccid3_hc_rx_init
,
908 .ccid_hc_rx_exit
= ccid3_hc_rx_exit
,
909 .ccid_hc_rx_insert_options
= ccid3_hc_rx_insert_options
,
910 .ccid_hc_rx_packet_recv
= ccid3_hc_rx_packet_recv
,
911 .ccid_hc_rx_get_info
= ccid3_hc_rx_get_info
,
912 .ccid_hc_tx_get_info
= ccid3_hc_tx_get_info
,
913 .ccid_hc_rx_getsockopt
= ccid3_hc_rx_getsockopt
,
914 .ccid_hc_tx_getsockopt
= ccid3_hc_tx_getsockopt
,
917 #ifdef CONFIG_IP_DCCP_CCID3_DEBUG
918 module_param(ccid3_debug
, bool, 0644);
919 MODULE_PARM_DESC(ccid3_debug
, "Enable debug messages");
922 static __init
int ccid3_module_init(void)
924 return ccid_register(&ccid3
);
926 module_init(ccid3_module_init
);
928 static __exit
void ccid3_module_exit(void)
930 ccid_unregister(&ccid3
);
932 module_exit(ccid3_module_exit
);
934 MODULE_AUTHOR("Ian McDonald <ian.mcdonald@jandi.co.nz>, "
935 "Arnaldo Carvalho de Melo <acme@ghostprotocols.net>");
936 MODULE_DESCRIPTION("DCCP TFRC CCID3 CCID");
937 MODULE_LICENSE("GPL");
938 MODULE_ALIAS("net-dccp-ccid-3");