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
;
374 struct tfrc_tx_hist_entry
*acked
;
379 /* we are only interested in ACKs */
380 if (!(DCCP_SKB_CB(skb
)->dccpd_type
== DCCP_PKT_ACK
||
381 DCCP_SKB_CB(skb
)->dccpd_type
== DCCP_PKT_DATAACK
))
383 /* ... and only in the established state */
384 if (hctx
->state
!= TFRC_SSTATE_FBACK
&&
385 hctx
->state
!= TFRC_SSTATE_NO_FBACK
)
389 * Locate the acknowledged packet in the TX history.
391 * Returning "entry not found" here can for instance happen when
392 * - the host has not sent out anything (e.g. a passive server),
393 * - the Ack is outdated (packet with higher Ack number was received),
394 * - it is a bogus Ack (for a packet not sent on this connection).
396 acked
= tfrc_tx_hist_find_entry(hctx
->hist
, dccp_hdr_ack_seq(skb
));
399 /* For the sake of RTT sampling, ignore/remove all older entries */
400 tfrc_tx_hist_purge(&acked
->next
);
402 /* Update the moving average for the RTT estimate (RFC 3448, 4.3) */
403 now
= ktime_get_real();
404 r_sample
= dccp_sample_rtt(sk
, ktime_us_delta(now
, acked
->stamp
));
405 hctx
->rtt
= tfrc_ewma(hctx
->rtt
, r_sample
, 9);
407 /* Update receive rate in units of 64 * bytes/second */
408 hctx
->x_recv
= opt_recv
->ccid3or_receive_rate
;
411 /* Update loss event rate (which is scaled by 1e6) */
412 pinv
= opt_recv
->ccid3or_loss_event_rate
;
416 hctx
->p
= tfrc_invert_loss_event_rate(pinv
);
419 * Update allowed sending rate X as per draft rfc3448bis-00, 4.2/3
421 if (hctx
->state
== TFRC_SSTATE_NO_FBACK
) {
422 ccid3_hc_tx_set_state(sk
, TFRC_SSTATE_FBACK
);
424 if (hctx
->t_rto
== 0) {
426 * Initial feedback packet: Larger Initial Windows (4.2)
428 hctx
->x
= rfc3390_initial_rate(sk
);
431 ccid3_update_send_interval(hctx
);
433 goto done_computing_x
;
434 } else if (hctx
->p
== 0) {
436 * First feedback after nofeedback timer expiry (4.3)
438 goto done_computing_x
;
442 /* Update sending rate (step 4 of [RFC 3448, 4.3]) */
444 hctx
->x_calc
= tfrc_calc_x(hctx
->s
, hctx
->rtt
, hctx
->p
);
445 ccid3_hc_tx_update_x(sk
, &now
);
448 ccid3_pr_debug("%s(%p), RTT=%uus (sample=%uus), s=%u, "
449 "p=%u, X_calc=%u, X_recv=%u, X=%u\n",
450 dccp_role(sk
), sk
, hctx
->rtt
, r_sample
,
451 hctx
->s
, hctx
->p
, hctx
->x_calc
,
452 (unsigned)(hctx
->x_recv
>> 6),
453 (unsigned)(hctx
->x
>> 6));
455 /* unschedule no feedback timer */
456 sk_stop_timer(sk
, &hctx
->no_feedback_timer
);
459 * As we have calculated new ipi, delta, t_nom it is possible
460 * that we now can send a packet, so wake up dccp_wait_for_ccid
462 sk
->sk_write_space(sk
);
465 * Update timeout interval for the nofeedback timer.
466 * We use a configuration option to increase the lower bound.
467 * This can help avoid triggering the nofeedback timer too
468 * often ('spinning') on LANs with small RTTs.
470 hctx
->t_rto
= max_t(u32
, 4 * hctx
->rtt
, (CONFIG_IP_DCCP_CCID3_RTO
*
471 (USEC_PER_SEC
/ 1000)));
473 * Schedule no feedback timer to expire in
474 * max(t_RTO, 2 * s/X) = max(t_RTO, 2 * t_ipi)
476 t_nfb
= max(hctx
->t_rto
, 2 * hctx
->t_ipi
);
478 ccid3_pr_debug("%s(%p), Scheduled no feedback timer to "
479 "expire in %lu jiffies (%luus)\n",
480 dccp_role(sk
), sk
, usecs_to_jiffies(t_nfb
), t_nfb
);
482 sk_reset_timer(sk
, &hctx
->no_feedback_timer
,
483 jiffies
+ usecs_to_jiffies(t_nfb
));
486 static int ccid3_hc_tx_parse_options(struct sock
*sk
, u8 packet_type
,
487 u8 option
, u8
*optval
, u8 optlen
)
489 struct ccid3_hc_tx_sock
*hctx
= ccid3_hc_tx_sk(sk
);
490 struct ccid3_options_received
*opt_recv
= &hctx
->options_received
;
494 case TFRC_OPT_RECEIVE_RATE
:
495 case TFRC_OPT_LOSS_EVENT_RATE
:
496 /* Must be ignored on Data packets, cf. RFC 4342 8.3 and 8.5 */
497 if (packet_type
== DCCP_PKT_DATA
)
499 if (unlikely(optlen
!= 4)) {
500 DCCP_WARN("%s(%p), invalid len %d for %u\n",
501 dccp_role(sk
), sk
, optlen
, option
);
504 opt_val
= ntohl(get_unaligned((__be32
*)optval
));
506 if (option
== TFRC_OPT_RECEIVE_RATE
) {
507 opt_recv
->ccid3or_receive_rate
= opt_val
;
508 ccid3_pr_debug("%s(%p), RECEIVE_RATE=%u\n",
509 dccp_role(sk
), sk
, opt_val
);
511 opt_recv
->ccid3or_loss_event_rate
= opt_val
;
512 ccid3_pr_debug("%s(%p), LOSS_EVENT_RATE=%u\n",
513 dccp_role(sk
), sk
, opt_val
);
519 static int ccid3_hc_tx_init(struct ccid
*ccid
, struct sock
*sk
)
521 struct ccid3_hc_tx_sock
*hctx
= ccid_priv(ccid
);
523 hctx
->state
= TFRC_SSTATE_NO_SENT
;
525 setup_timer(&hctx
->no_feedback_timer
,
526 ccid3_hc_tx_no_feedback_timer
, (unsigned long)sk
);
530 static void ccid3_hc_tx_exit(struct sock
*sk
)
532 struct ccid3_hc_tx_sock
*hctx
= ccid3_hc_tx_sk(sk
);
534 ccid3_hc_tx_set_state(sk
, TFRC_SSTATE_TERM
);
535 sk_stop_timer(sk
, &hctx
->no_feedback_timer
);
537 tfrc_tx_hist_purge(&hctx
->hist
);
540 static void ccid3_hc_tx_get_info(struct sock
*sk
, struct tcp_info
*info
)
542 info
->tcpi_rto
= ccid3_hc_tx_sk(sk
)->t_rto
;
543 info
->tcpi_rtt
= ccid3_hc_tx_sk(sk
)->rtt
;
546 static int ccid3_hc_tx_getsockopt(struct sock
*sk
, const int optname
, int len
,
547 u32 __user
*optval
, int __user
*optlen
)
549 const struct ccid3_hc_tx_sock
*hctx
= ccid3_hc_tx_sk(sk
);
550 struct tfrc_tx_info tfrc
;
554 case DCCP_SOCKOPT_CCID_TX_INFO
:
555 if (len
< sizeof(tfrc
))
557 tfrc
.tfrctx_x
= hctx
->x
;
558 tfrc
.tfrctx_x_recv
= hctx
->x_recv
;
559 tfrc
.tfrctx_x_calc
= hctx
->x_calc
;
560 tfrc
.tfrctx_rtt
= hctx
->rtt
;
561 tfrc
.tfrctx_p
= hctx
->p
;
562 tfrc
.tfrctx_rto
= hctx
->t_rto
;
563 tfrc
.tfrctx_ipi
= hctx
->t_ipi
;
571 if (put_user(len
, optlen
) || copy_to_user(optval
, val
, len
))
578 * Receiver Half-Connection Routines
581 /* CCID3 feedback types */
582 enum ccid3_fback_type
{
583 CCID3_FBACK_NONE
= 0,
585 CCID3_FBACK_PERIODIC
,
586 CCID3_FBACK_PARAM_CHANGE
589 #ifdef CONFIG_IP_DCCP_CCID3_DEBUG
590 static const char *ccid3_rx_state_name(enum ccid3_hc_rx_states state
)
592 static char *ccid3_rx_state_names
[] = {
593 [TFRC_RSTATE_NO_DATA
] = "NO_DATA",
594 [TFRC_RSTATE_DATA
] = "DATA",
595 [TFRC_RSTATE_TERM
] = "TERM",
598 return ccid3_rx_state_names
[state
];
602 static void ccid3_hc_rx_set_state(struct sock
*sk
,
603 enum ccid3_hc_rx_states state
)
605 struct ccid3_hc_rx_sock
*hcrx
= ccid3_hc_rx_sk(sk
);
606 enum ccid3_hc_rx_states oldstate
= hcrx
->state
;
608 ccid3_pr_debug("%s(%p) %-8.8s -> %s\n",
609 dccp_role(sk
), sk
, ccid3_rx_state_name(oldstate
),
610 ccid3_rx_state_name(state
));
611 WARN_ON(state
== oldstate
);
615 static void ccid3_hc_rx_send_feedback(struct sock
*sk
,
616 const struct sk_buff
*skb
,
617 enum ccid3_fback_type fbtype
)
619 struct ccid3_hc_rx_sock
*hcrx
= ccid3_hc_rx_sk(sk
);
620 struct dccp_sock
*dp
= dccp_sk(sk
);
624 if (unlikely(hcrx
->state
== TFRC_RSTATE_TERM
))
627 now
= ktime_get_real();
630 case CCID3_FBACK_INITIAL
:
632 hcrx
->p_inverse
= ~0U; /* see RFC 4342, 8.5 */
634 case CCID3_FBACK_PARAM_CHANGE
:
636 * When parameters change (new loss or p > p_prev), we do not
637 * have a reliable estimate for R_m of [RFC 3448, 6.2] and so
638 * need to reuse the previous value of X_recv. However, when
639 * X_recv was 0 (due to early loss), this would kill X down to
640 * s/t_mbi (i.e. one packet in 64 seconds).
641 * To avoid such drastic reduction, we approximate X_recv as
642 * the number of bytes since last feedback.
643 * This is a safe fallback, since X is bounded above by X_calc.
645 if (hcrx
->x_recv
> 0)
648 case CCID3_FBACK_PERIODIC
:
649 delta
= ktime_us_delta(now
, hcrx
->tstamp_last_feedback
);
651 DCCP_BUG("delta (%ld) <= 0", (long)delta
);
653 hcrx
->x_recv
= scaled_div32(hcrx
->bytes_recv
, delta
);
659 ccid3_pr_debug("Interval %ldusec, X_recv=%u, 1/p=%u\n",
660 (long)delta
, hcrx
->x_recv
, hcrx
->p_inverse
);
662 hcrx
->tstamp_last_feedback
= now
;
663 hcrx
->last_counter
= dccp_hdr(skb
)->dccph_ccval
;
664 hcrx
->bytes_recv
= 0;
666 dp
->dccps_hc_rx_insert_options
= 1;
670 static int ccid3_hc_rx_insert_options(struct sock
*sk
, struct sk_buff
*skb
)
672 const struct ccid3_hc_rx_sock
*hcrx
= ccid3_hc_rx_sk(sk
);
675 if (!(sk
->sk_state
== DCCP_OPEN
|| sk
->sk_state
== DCCP_PARTOPEN
))
678 if (dccp_packet_without_ack(skb
))
681 x_recv
= htonl(hcrx
->x_recv
);
682 pinv
= htonl(hcrx
->p_inverse
);
684 if (dccp_insert_option(sk
, skb
, TFRC_OPT_LOSS_EVENT_RATE
,
685 &pinv
, sizeof(pinv
)) ||
686 dccp_insert_option(sk
, skb
, TFRC_OPT_RECEIVE_RATE
,
687 &x_recv
, sizeof(x_recv
)))
693 /** ccid3_first_li - Implements [RFC 3448, 6.3.1]
695 * Determine the length of the first loss interval via inverse lookup.
696 * Assume that X_recv can be computed by the throughput equation
700 * Find some p such that f(p) = fval; return 1/p (scaled).
702 static u32
ccid3_first_li(struct sock
*sk
)
704 struct ccid3_hc_rx_sock
*hcrx
= ccid3_hc_rx_sk(sk
);
705 u32 x_recv
, p
, delta
;
708 if (hcrx
->rtt
== 0) {
709 DCCP_WARN("No RTT estimate available, using fallback RTT\n");
710 hcrx
->rtt
= DCCP_FALLBACK_RTT
;
713 delta
= ktime_to_us(net_timedelta(hcrx
->tstamp_last_feedback
));
714 x_recv
= scaled_div32(hcrx
->bytes_recv
, delta
);
715 if (x_recv
== 0) { /* would also trigger divide-by-zero */
716 DCCP_WARN("X_recv==0\n");
717 if (hcrx
->x_recv
== 0) {
718 DCCP_BUG("stored value of X_recv is zero");
721 x_recv
= hcrx
->x_recv
;
724 fval
= scaled_div(hcrx
->s
, hcrx
->rtt
);
725 fval
= scaled_div32(fval
, x_recv
);
726 p
= tfrc_calc_x_reverse_lookup(fval
);
728 ccid3_pr_debug("%s(%p), receive rate=%u bytes/s, implied "
729 "loss rate=%u\n", dccp_role(sk
), sk
, x_recv
, p
);
731 return p
== 0 ? ~0U : scaled_div(1, p
);
734 static void ccid3_hc_rx_packet_recv(struct sock
*sk
, struct sk_buff
*skb
)
736 struct ccid3_hc_rx_sock
*hcrx
= ccid3_hc_rx_sk(sk
);
737 enum ccid3_fback_type do_feedback
= CCID3_FBACK_NONE
;
738 const u64 ndp
= dccp_sk(sk
)->dccps_options_received
.dccpor_ndp
;
739 const bool is_data_packet
= dccp_data_packet(skb
);
741 if (unlikely(hcrx
->state
== TFRC_RSTATE_NO_DATA
)) {
742 if (is_data_packet
) {
743 const u32 payload
= skb
->len
- dccp_hdr(skb
)->dccph_doff
* 4;
744 do_feedback
= CCID3_FBACK_INITIAL
;
745 ccid3_hc_rx_set_state(sk
, TFRC_RSTATE_DATA
);
748 * Not necessary to update bytes_recv here,
749 * since X_recv = 0 for the first feedback packet (cf.
750 * RFC 3448, 6.3) -- gerrit
756 if (tfrc_rx_hist_duplicate(&hcrx
->hist
, skb
))
757 return; /* done receiving */
759 if (is_data_packet
) {
760 const u32 payload
= skb
->len
- dccp_hdr(skb
)->dccph_doff
* 4;
762 * Update moving-average of s and the sum of received payload bytes
764 hcrx
->s
= tfrc_ewma(hcrx
->s
, payload
, 9);
765 hcrx
->bytes_recv
+= payload
;
769 * Perform loss detection and handle pending losses
771 if (tfrc_rx_handle_loss(&hcrx
->hist
, &hcrx
->li_hist
,
772 skb
, ndp
, ccid3_first_li
, sk
)) {
773 do_feedback
= CCID3_FBACK_PARAM_CHANGE
;
777 if (tfrc_rx_hist_loss_pending(&hcrx
->hist
))
778 return; /* done receiving */
781 * Handle data packets: RTT sampling and monitoring p
783 if (unlikely(!is_data_packet
))
786 if (!tfrc_lh_is_initialised(&hcrx
->li_hist
)) {
787 const u32 sample
= tfrc_rx_hist_sample_rtt(&hcrx
->hist
, skb
);
789 * Empty loss history: no loss so far, hence p stays 0.
790 * Sample RTT values, since an RTT estimate is required for the
791 * computation of p when the first loss occurs; RFC 3448, 6.3.1.
794 hcrx
->rtt
= tfrc_ewma(hcrx
->rtt
, sample
, 9);
796 } else if (tfrc_lh_update_i_mean(&hcrx
->li_hist
, skb
)) {
798 * Step (3) of [RFC 3448, 6.1]: Recompute I_mean and, if I_mean
799 * has decreased (resp. p has increased), send feedback now.
801 do_feedback
= CCID3_FBACK_PARAM_CHANGE
;
805 * Check if the periodic once-per-RTT feedback is due; RFC 4342, 10.3
807 if (SUB16(dccp_hdr(skb
)->dccph_ccval
, hcrx
->last_counter
) > 3)
808 do_feedback
= CCID3_FBACK_PERIODIC
;
811 tfrc_rx_hist_add_packet(&hcrx
->hist
, skb
, ndp
);
815 ccid3_hc_rx_send_feedback(sk
, skb
, do_feedback
);
818 static int ccid3_hc_rx_init(struct ccid
*ccid
, struct sock
*sk
)
820 struct ccid3_hc_rx_sock
*hcrx
= ccid_priv(ccid
);
822 hcrx
->state
= TFRC_RSTATE_NO_DATA
;
823 tfrc_lh_init(&hcrx
->li_hist
);
824 return tfrc_rx_hist_alloc(&hcrx
->hist
);
827 static void ccid3_hc_rx_exit(struct sock
*sk
)
829 struct ccid3_hc_rx_sock
*hcrx
= ccid3_hc_rx_sk(sk
);
831 ccid3_hc_rx_set_state(sk
, TFRC_RSTATE_TERM
);
833 tfrc_rx_hist_purge(&hcrx
->hist
);
834 tfrc_lh_cleanup(&hcrx
->li_hist
);
837 static void ccid3_hc_rx_get_info(struct sock
*sk
, struct tcp_info
*info
)
839 info
->tcpi_ca_state
= ccid3_hc_rx_sk(sk
)->state
;
840 info
->tcpi_options
|= TCPI_OPT_TIMESTAMPS
;
841 info
->tcpi_rcv_rtt
= ccid3_hc_rx_sk(sk
)->rtt
;
844 static int ccid3_hc_rx_getsockopt(struct sock
*sk
, const int optname
, int len
,
845 u32 __user
*optval
, int __user
*optlen
)
847 const struct ccid3_hc_rx_sock
*hcrx
= ccid3_hc_rx_sk(sk
);
848 struct tfrc_rx_info rx_info
;
852 case DCCP_SOCKOPT_CCID_RX_INFO
:
853 if (len
< sizeof(rx_info
))
855 rx_info
.tfrcrx_x_recv
= hcrx
->x_recv
;
856 rx_info
.tfrcrx_rtt
= hcrx
->rtt
;
857 rx_info
.tfrcrx_p
= tfrc_invert_loss_event_rate(hcrx
->p_inverse
);
858 len
= sizeof(rx_info
);
865 if (put_user(len
, optlen
) || copy_to_user(optval
, val
, len
))
871 static struct ccid_operations ccid3
= {
872 .ccid_id
= DCCPC_CCID3
,
873 .ccid_name
= "TCP-Friendly Rate Control",
874 .ccid_owner
= THIS_MODULE
,
875 .ccid_hc_tx_obj_size
= sizeof(struct ccid3_hc_tx_sock
),
876 .ccid_hc_tx_init
= ccid3_hc_tx_init
,
877 .ccid_hc_tx_exit
= ccid3_hc_tx_exit
,
878 .ccid_hc_tx_send_packet
= ccid3_hc_tx_send_packet
,
879 .ccid_hc_tx_packet_sent
= ccid3_hc_tx_packet_sent
,
880 .ccid_hc_tx_packet_recv
= ccid3_hc_tx_packet_recv
,
881 .ccid_hc_tx_parse_options
= ccid3_hc_tx_parse_options
,
882 .ccid_hc_rx_obj_size
= sizeof(struct ccid3_hc_rx_sock
),
883 .ccid_hc_rx_init
= ccid3_hc_rx_init
,
884 .ccid_hc_rx_exit
= ccid3_hc_rx_exit
,
885 .ccid_hc_rx_insert_options
= ccid3_hc_rx_insert_options
,
886 .ccid_hc_rx_packet_recv
= ccid3_hc_rx_packet_recv
,
887 .ccid_hc_rx_get_info
= ccid3_hc_rx_get_info
,
888 .ccid_hc_tx_get_info
= ccid3_hc_tx_get_info
,
889 .ccid_hc_rx_getsockopt
= ccid3_hc_rx_getsockopt
,
890 .ccid_hc_tx_getsockopt
= ccid3_hc_tx_getsockopt
,
893 #ifdef CONFIG_IP_DCCP_CCID3_DEBUG
894 module_param(ccid3_debug
, bool, 0644);
895 MODULE_PARM_DESC(ccid3_debug
, "Enable debug messages");
898 static __init
int ccid3_module_init(void)
900 return ccid_register(&ccid3
);
902 module_init(ccid3_module_init
);
904 static __exit
void ccid3_module_exit(void)
906 ccid_unregister(&ccid3
);
908 module_exit(ccid3_module_exit
);
910 MODULE_AUTHOR("Ian McDonald <ian.mcdonald@jandi.co.nz>, "
911 "Arnaldo Carvalho de Melo <acme@ghostprotocols.net>");
912 MODULE_DESCRIPTION("DCCP TFRC CCID3 CCID");
913 MODULE_LICENSE("GPL");
914 MODULE_ALIAS("net-dccp-ccid-3");