2 * net/dccp/ccids/ccid2.c
4 * Copyright (c) 2005, 2006 Andrea Bittau <a.bittau@cs.ucl.ac.uk>
6 * Changes to meet Linux coding standards, and DCCP infrastructure fixes.
8 * Copyright (c) 2006 Arnaldo Carvalho de Melo <acme@conectiva.com.br>
10 * This program is free software; you can redistribute it and/or modify
11 * it under the terms of the GNU General Public License as published by
12 * the Free Software Foundation; either version 2 of the License, or
13 * (at your option) any later version.
15 * This program is distributed in the hope that it will be useful,
16 * but WITHOUT ANY WARRANTY; without even the implied warranty of
17 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
18 * GNU General Public License for more details.
20 * You should have received a copy of the GNU General Public License
21 * along with this program; if not, write to the Free Software
22 * Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
26 * This implementation should follow RFC 4341
34 #ifdef CONFIG_IP_DCCP_CCID2_DEBUG
35 static int ccid2_debug;
36 #define ccid2_pr_debug(format, a...) DCCP_PR_DEBUG(ccid2_debug, format, ##a)
38 static void ccid2_hc_tx_check_sanity(const struct ccid2_hc_tx_sock *hctx)
42 struct ccid2_seq *seqp = hctx->ccid2hctx_seqh;
44 /* there is data in the chain */
45 if (seqp != hctx->ccid2hctx_seqt) {
46 seqp = seqp->ccid2s_prev;
48 if (!seqp->ccid2s_acked)
51 while (seqp != hctx->ccid2hctx_seqt) {
52 struct ccid2_seq *prev = seqp->ccid2s_prev;
55 if (!prev->ccid2s_acked)
58 /* packets are sent sequentially */
59 BUG_ON(dccp_delta_seqno(seqp->ccid2s_seq,
60 prev->ccid2s_seq ) >= 0);
61 BUG_ON(time_before(seqp->ccid2s_sent,
68 BUG_ON(pipe != hctx->ccid2hctx_pipe);
69 ccid2_pr_debug("len of chain=%d\n", len);
72 seqp = seqp->ccid2s_prev;
74 } while (seqp != hctx->ccid2hctx_seqh);
76 ccid2_pr_debug("total len=%d\n", len);
77 BUG_ON(len != hctx->ccid2hctx_seqbufc * CCID2_SEQBUF_LEN);
80 #define ccid2_pr_debug(format, a...)
81 #define ccid2_hc_tx_check_sanity(hctx)
84 static int ccid2_hc_tx_alloc_seq(struct ccid2_hc_tx_sock *hctx)
86 struct ccid2_seq *seqp;
89 /* check if we have space to preserve the pointer to the buffer */
90 if (hctx->ccid2hctx_seqbufc >= (sizeof(hctx->ccid2hctx_seqbuf) /
91 sizeof(struct ccid2_seq*)))
94 /* allocate buffer and initialize linked list */
95 seqp = kmalloc(CCID2_SEQBUF_LEN * sizeof(struct ccid2_seq), gfp_any());
99 for (i = 0; i < (CCID2_SEQBUF_LEN - 1); i++) {
100 seqp[i].ccid2s_next = &seqp[i + 1];
101 seqp[i + 1].ccid2s_prev = &seqp[i];
103 seqp[CCID2_SEQBUF_LEN - 1].ccid2s_next = seqp;
104 seqp->ccid2s_prev = &seqp[CCID2_SEQBUF_LEN - 1];
106 /* This is the first allocation. Initiate the head and tail. */
107 if (hctx->ccid2hctx_seqbufc == 0)
108 hctx->ccid2hctx_seqh = hctx->ccid2hctx_seqt = seqp;
110 /* link the existing list with the one we just created */
111 hctx->ccid2hctx_seqh->ccid2s_next = seqp;
112 seqp->ccid2s_prev = hctx->ccid2hctx_seqh;
114 hctx->ccid2hctx_seqt->ccid2s_prev = &seqp[CCID2_SEQBUF_LEN - 1];
115 seqp[CCID2_SEQBUF_LEN - 1].ccid2s_next = hctx->ccid2hctx_seqt;
118 /* store the original pointer to the buffer so we can free it */
119 hctx->ccid2hctx_seqbuf[hctx->ccid2hctx_seqbufc] = seqp;
120 hctx->ccid2hctx_seqbufc++;
125 static int ccid2_hc_tx_send_packet(struct sock *sk, struct sk_buff *skb)
127 struct ccid2_hc_tx_sock *hctx = ccid2_hc_tx_sk(sk);
129 if (hctx->ccid2hctx_pipe < hctx->ccid2hctx_cwnd)
132 return 1; /* XXX CCID should dequeue when ready instead of polling */
135 static void ccid2_change_l_ack_ratio(struct sock *sk, u32 val)
137 struct dccp_sock *dp = dccp_sk(sk);
138 u32 max_ratio = DIV_ROUND_UP(ccid2_hc_tx_sk(sk)->ccid2hctx_cwnd, 2);
141 * Ensure that Ack Ratio does not exceed ceil(cwnd/2), which is (2) from
142 * RFC 4341, 6.1.2. We ignore the statement that Ack Ratio 2 is always
143 * acceptable since this causes starvation/deadlock whenever cwnd < 2.
144 * The same problem arises when Ack Ratio is 0 (ie. Ack Ratio disabled).
146 if (val == 0 || val > max_ratio) {
147 DCCP_WARN("Limiting Ack Ratio (%u) to %u\n", val, max_ratio);
150 if (val > 0xFFFF) /* RFC 4340, 11.3 */
153 if (val == dp->dccps_l_ack_ratio)
156 ccid2_pr_debug("changing local ack ratio to %u\n", val);
157 dp->dccps_l_ack_ratio = val;
160 static void ccid2_change_srtt(struct ccid2_hc_tx_sock *hctx, long val)
162 ccid2_pr_debug("change SRTT to %ld\n", val);
163 hctx->ccid2hctx_srtt = val;
166 static void ccid2_start_rto_timer(struct sock *sk);
168 static void ccid2_hc_tx_rto_expire(unsigned long data)
170 struct sock *sk = (struct sock *)data;
171 struct ccid2_hc_tx_sock *hctx = ccid2_hc_tx_sk(sk);
175 if (sock_owned_by_user(sk)) {
176 sk_reset_timer(sk, &hctx->ccid2hctx_rtotimer,
181 ccid2_pr_debug("RTO_EXPIRE\n");
183 ccid2_hc_tx_check_sanity(hctx);
186 hctx->ccid2hctx_rto <<= 1;
188 s = hctx->ccid2hctx_rto / HZ;
190 hctx->ccid2hctx_rto = 60 * HZ;
192 ccid2_start_rto_timer(sk);
194 /* adjust pipe, cwnd etc */
195 hctx->ccid2hctx_ssthresh = hctx->ccid2hctx_cwnd / 2;
196 if (hctx->ccid2hctx_ssthresh < 2)
197 hctx->ccid2hctx_ssthresh = 2;
198 hctx->ccid2hctx_cwnd = 1;
199 hctx->ccid2hctx_pipe = 0;
201 /* clear state about stuff we sent */
202 hctx->ccid2hctx_seqt = hctx->ccid2hctx_seqh;
203 hctx->ccid2hctx_ssacks = 0;
204 hctx->ccid2hctx_acks = 0;
206 /* clear ack ratio state. */
207 hctx->ccid2hctx_rpseq = 0;
208 hctx->ccid2hctx_rpdupack = -1;
209 ccid2_change_l_ack_ratio(sk, 1);
210 ccid2_hc_tx_check_sanity(hctx);
216 static void ccid2_start_rto_timer(struct sock *sk)
218 struct ccid2_hc_tx_sock *hctx = ccid2_hc_tx_sk(sk);
220 ccid2_pr_debug("setting RTO timeout=%ld\n", hctx->ccid2hctx_rto);
222 BUG_ON(timer_pending(&hctx->ccid2hctx_rtotimer));
223 sk_reset_timer(sk, &hctx->ccid2hctx_rtotimer,
224 jiffies + hctx->ccid2hctx_rto);
227 static void ccid2_hc_tx_packet_sent(struct sock *sk, int more, unsigned int len)
229 struct dccp_sock *dp = dccp_sk(sk);
230 struct ccid2_hc_tx_sock *hctx = ccid2_hc_tx_sk(sk);
231 struct ccid2_seq *next;
234 hctx->ccid2hctx_pipe++;
236 /* There is an issue. What if another packet is sent between
237 * packet_send() and packet_sent(). Then the sequence number would be
243 hctx->ccid2hctx_seqh->ccid2s_seq = seq;
244 hctx->ccid2hctx_seqh->ccid2s_acked = 0;
245 hctx->ccid2hctx_seqh->ccid2s_sent = jiffies;
247 next = hctx->ccid2hctx_seqh->ccid2s_next;
248 /* check if we need to alloc more space */
249 if (next == hctx->ccid2hctx_seqt) {
250 if (ccid2_hc_tx_alloc_seq(hctx)) {
251 DCCP_CRIT("packet history - out of memory!");
252 /* FIXME: find a more graceful way to bail out */
255 next = hctx->ccid2hctx_seqh->ccid2s_next;
256 BUG_ON(next == hctx->ccid2hctx_seqt);
258 hctx->ccid2hctx_seqh = next;
260 ccid2_pr_debug("cwnd=%d pipe=%d\n", hctx->ccid2hctx_cwnd,
261 hctx->ccid2hctx_pipe);
264 * FIXME: The code below is broken and the variables have been removed
265 * from the socket struct. The `ackloss' variable was always set to 0,
266 * and with arsent there are several problems:
267 * (i) it doesn't just count the number of Acks, but all sent packets;
268 * (ii) it is expressed in # of packets, not # of windows, so the
269 * comparison below uses the wrong formula: Appendix A of RFC 4341
270 * comes up with the number K = cwnd / (R^2 - R) of consecutive windows
271 * of data with no lost or marked Ack packets. If arsent were the # of
272 * consecutive Acks received without loss, then Ack Ratio needs to be
273 * decreased by 1 when
274 * arsent >= K * cwnd / R = cwnd^2 / (R^3 - R^2)
275 * where cwnd / R is the number of Acks received per window of data
276 * (cf. RFC 4341, App. A). The problems are that
277 * - arsent counts other packets as well;
278 * - the comparison uses a formula different from RFC 4341;
279 * - computing a cubic/quadratic equation each time is too complicated.
280 * Hence a different algorithm is needed.
283 /* Ack Ratio. Need to maintain a concept of how many windows we sent */
284 hctx->ccid2hctx_arsent++;
285 /* We had an ack loss in this window... */
286 if (hctx->ccid2hctx_ackloss) {
287 if (hctx->ccid2hctx_arsent >= hctx->ccid2hctx_cwnd) {
288 hctx->ccid2hctx_arsent = 0;
289 hctx->ccid2hctx_ackloss = 0;
292 /* No acks lost up to now... */
293 /* decrease ack ratio if enough packets were sent */
294 if (dp->dccps_l_ack_ratio > 1) {
295 /* XXX don't calculate denominator each time */
296 int denom = dp->dccps_l_ack_ratio * dp->dccps_l_ack_ratio -
297 dp->dccps_l_ack_ratio;
299 denom = hctx->ccid2hctx_cwnd * hctx->ccid2hctx_cwnd / denom;
301 if (hctx->ccid2hctx_arsent >= denom) {
302 ccid2_change_l_ack_ratio(sk, dp->dccps_l_ack_ratio - 1);
303 hctx->ccid2hctx_arsent = 0;
306 /* we can't increase ack ratio further [1] */
307 hctx->ccid2hctx_arsent = 0; /* or maybe set it to cwnd*/
312 /* setup RTO timer */
313 if (!timer_pending(&hctx->ccid2hctx_rtotimer))
314 ccid2_start_rto_timer(sk);
316 #ifdef CONFIG_IP_DCCP_CCID2_DEBUG
317 ccid2_pr_debug("Sent: seq=%llu\n", (unsigned long long)seq);
319 struct ccid2_seq *seqp = hctx->ccid2hctx_seqt;
321 while (seqp != hctx->ccid2hctx_seqh) {
322 ccid2_pr_debug("out seq=%llu acked=%d time=%lu\n",
323 (unsigned long long)seqp->ccid2s_seq,
324 seqp->ccid2s_acked, seqp->ccid2s_sent);
325 seqp = seqp->ccid2s_next;
328 ccid2_pr_debug("=========\n");
329 ccid2_hc_tx_check_sanity(hctx);
333 /* XXX Lame code duplication!
334 * returns -1 if none was found.
335 * else returns the next offset to use in the function call.
337 static int ccid2_ackvector(struct sock *sk, struct sk_buff *skb, int offset,
338 unsigned char **vec, unsigned char *veclen)
340 const struct dccp_hdr *dh = dccp_hdr(skb);
341 unsigned char *options = (unsigned char *)dh + dccp_hdr_len(skb);
342 unsigned char *opt_ptr;
343 const unsigned char *opt_end = (unsigned char *)dh +
344 (dh->dccph_doff * 4);
345 unsigned char opt, len;
346 unsigned char *value;
351 if (opt_ptr >= opt_end)
354 while (opt_ptr != opt_end) {
359 /* Check if this isn't a single byte option */
360 if (opt > DCCPO_MAX_RESERVED) {
361 if (opt_ptr == opt_end)
362 goto out_invalid_option;
366 goto out_invalid_option;
368 * Remove the type and len fields, leaving
369 * just the value size
375 if (opt_ptr > opt_end)
376 goto out_invalid_option;
380 case DCCPO_ACK_VECTOR_0:
381 case DCCPO_ACK_VECTOR_1:
384 return offset + (opt_ptr - options);
391 DCCP_BUG("Invalid option - this should not happen (previous parsing)!");
395 static void ccid2_hc_tx_kill_rto_timer(struct sock *sk)
397 struct ccid2_hc_tx_sock *hctx = ccid2_hc_tx_sk(sk);
399 sk_stop_timer(sk, &hctx->ccid2hctx_rtotimer);
400 ccid2_pr_debug("deleted RTO timer\n");
403 static inline void ccid2_new_ack(struct sock *sk,
404 struct ccid2_seq *seqp,
405 unsigned int *maxincr)
407 struct ccid2_hc_tx_sock *hctx = ccid2_hc_tx_sk(sk);
410 if (hctx->ccid2hctx_cwnd < hctx->ccid2hctx_ssthresh) {
411 hctx->ccid2hctx_acks = 0;
413 /* We can increase cwnd at most maxincr [ack_ratio/2] */
415 /* increase every 2 acks */
416 hctx->ccid2hctx_ssacks++;
417 if (hctx->ccid2hctx_ssacks == 2) {
418 hctx->ccid2hctx_cwnd++;
419 hctx->ccid2hctx_ssacks = 0;
420 *maxincr = *maxincr - 1;
423 /* increased cwnd enough for this single ack */
424 hctx->ccid2hctx_ssacks = 0;
427 hctx->ccid2hctx_ssacks = 0;
428 hctx->ccid2hctx_acks++;
430 if (hctx->ccid2hctx_acks >= hctx->ccid2hctx_cwnd) {
431 hctx->ccid2hctx_cwnd++;
432 hctx->ccid2hctx_acks = 0;
437 if (hctx->ccid2hctx_srtt == -1 ||
438 time_after(jiffies, hctx->ccid2hctx_lastrtt + hctx->ccid2hctx_srtt)) {
439 unsigned long r = (long)jiffies - (long)seqp->ccid2s_sent;
442 /* first measurement */
443 if (hctx->ccid2hctx_srtt == -1) {
444 ccid2_pr_debug("R: %lu Time=%lu seq=%llu\n",
446 (unsigned long long)seqp->ccid2s_seq);
447 ccid2_change_srtt(hctx, r);
448 hctx->ccid2hctx_rttvar = r >> 1;
451 long tmp = hctx->ccid2hctx_srtt - r;
458 hctx->ccid2hctx_rttvar *= 3;
459 hctx->ccid2hctx_rttvar >>= 2;
460 hctx->ccid2hctx_rttvar += tmp;
463 srtt = hctx->ccid2hctx_srtt;
468 ccid2_change_srtt(hctx, srtt);
470 s = hctx->ccid2hctx_rttvar << 2;
471 /* clock granularity is 1 when based on jiffies */
474 hctx->ccid2hctx_rto = hctx->ccid2hctx_srtt + s;
476 /* must be at least a second */
477 s = hctx->ccid2hctx_rto / HZ;
478 /* DCCP doesn't require this [but I like it cuz my code sux] */
481 hctx->ccid2hctx_rto = HZ;
485 hctx->ccid2hctx_rto = HZ * 60;
487 hctx->ccid2hctx_lastrtt = jiffies;
489 ccid2_pr_debug("srtt: %ld rttvar: %ld rto: %ld (HZ=%d) R=%lu\n",
490 hctx->ccid2hctx_srtt, hctx->ccid2hctx_rttvar,
491 hctx->ccid2hctx_rto, HZ, r);
494 /* we got a new ack, so re-start RTO timer */
495 ccid2_hc_tx_kill_rto_timer(sk);
496 ccid2_start_rto_timer(sk);
499 static void ccid2_hc_tx_dec_pipe(struct sock *sk)
501 struct ccid2_hc_tx_sock *hctx = ccid2_hc_tx_sk(sk);
503 if (hctx->ccid2hctx_pipe == 0)
504 DCCP_BUG("pipe == 0");
506 hctx->ccid2hctx_pipe--;
508 if (hctx->ccid2hctx_pipe == 0)
509 ccid2_hc_tx_kill_rto_timer(sk);
512 static void ccid2_congestion_event(struct sock *sk, struct ccid2_seq *seqp)
514 struct ccid2_hc_tx_sock *hctx = ccid2_hc_tx_sk(sk);
516 if (time_before(seqp->ccid2s_sent, hctx->ccid2hctx_last_cong)) {
517 ccid2_pr_debug("Multiple losses in an RTT---treating as one\n");
521 hctx->ccid2hctx_last_cong = jiffies;
523 hctx->ccid2hctx_cwnd = hctx->ccid2hctx_cwnd / 2 ? : 1U;
524 hctx->ccid2hctx_ssthresh = max(hctx->ccid2hctx_cwnd, 2U);
526 /* Avoid spurious timeouts resulting from Ack Ratio > cwnd */
527 if (dccp_sk(sk)->dccps_l_ack_ratio > hctx->ccid2hctx_cwnd)
528 ccid2_change_l_ack_ratio(sk, hctx->ccid2hctx_cwnd);
531 static void ccid2_hc_tx_packet_recv(struct sock *sk, struct sk_buff *skb)
533 struct dccp_sock *dp = dccp_sk(sk);
534 struct ccid2_hc_tx_sock *hctx = ccid2_hc_tx_sk(sk);
536 struct ccid2_seq *seqp;
537 unsigned char *vector;
538 unsigned char veclen;
541 unsigned int maxincr = 0;
543 ccid2_hc_tx_check_sanity(hctx);
544 /* check reverse path congestion */
545 seqno = DCCP_SKB_CB(skb)->dccpd_seq;
547 /* XXX this whole "algorithm" is broken. Need to fix it to keep track
548 * of the seqnos of the dupacks so that rpseq and rpdupack are correct
551 /* need to bootstrap */
552 if (hctx->ccid2hctx_rpdupack == -1) {
553 hctx->ccid2hctx_rpdupack = 0;
554 hctx->ccid2hctx_rpseq = seqno;
556 /* check if packet is consecutive */
557 if (dccp_delta_seqno(hctx->ccid2hctx_rpseq, seqno) == 1)
558 hctx->ccid2hctx_rpseq = seqno;
559 /* it's a later packet */
560 else if (after48(seqno, hctx->ccid2hctx_rpseq)) {
561 hctx->ccid2hctx_rpdupack++;
563 /* check if we got enough dupacks */
564 if (hctx->ccid2hctx_rpdupack >= NUMDUPACK) {
565 hctx->ccid2hctx_rpdupack = -1; /* XXX lame */
566 hctx->ccid2hctx_rpseq = 0;
568 ccid2_change_l_ack_ratio(sk, 2 * dp->dccps_l_ack_ratio);
573 /* check forward path congestion */
574 /* still didn't send out new data packets */
575 if (hctx->ccid2hctx_seqh == hctx->ccid2hctx_seqt)
578 switch (DCCP_SKB_CB(skb)->dccpd_type) {
580 case DCCP_PKT_DATAACK:
586 ackno = DCCP_SKB_CB(skb)->dccpd_ack_seq;
587 if (after48(ackno, hctx->ccid2hctx_high_ack))
588 hctx->ccid2hctx_high_ack = ackno;
590 seqp = hctx->ccid2hctx_seqt;
591 while (before48(seqp->ccid2s_seq, ackno)) {
592 seqp = seqp->ccid2s_next;
593 if (seqp == hctx->ccid2hctx_seqh) {
594 seqp = hctx->ccid2hctx_seqh->ccid2s_prev;
599 /* If in slow-start, cwnd can increase at most Ack Ratio / 2 packets for
600 * this single ack. I round up.
603 maxincr = dp->dccps_l_ack_ratio >> 1;
606 /* go through all ack vectors */
607 while ((offset = ccid2_ackvector(sk, skb, offset,
608 &vector, &veclen)) != -1) {
609 /* go through this ack vector */
611 const u8 rl = *vector & DCCP_ACKVEC_LEN_MASK;
612 u64 ackno_end_rl = SUB48(ackno, rl);
614 ccid2_pr_debug("ackvec start:%llu end:%llu\n",
615 (unsigned long long)ackno,
616 (unsigned long long)ackno_end_rl);
617 /* if the seqno we are analyzing is larger than the
618 * current ackno, then move towards the tail of our
621 while (after48(seqp->ccid2s_seq, ackno)) {
622 if (seqp == hctx->ccid2hctx_seqt) {
626 seqp = seqp->ccid2s_prev;
631 /* check all seqnos in the range of the vector
634 while (between48(seqp->ccid2s_seq,ackno_end_rl,ackno)) {
635 const u8 state = *vector &
636 DCCP_ACKVEC_STATE_MASK;
638 /* new packet received or marked */
639 if (state != DCCP_ACKVEC_STATE_NOT_RECEIVED &&
640 !seqp->ccid2s_acked) {
642 DCCP_ACKVEC_STATE_ECN_MARKED) {
643 ccid2_congestion_event(sk,
646 ccid2_new_ack(sk, seqp,
649 seqp->ccid2s_acked = 1;
650 ccid2_pr_debug("Got ack for %llu\n",
651 (unsigned long long)seqp->ccid2s_seq);
652 ccid2_hc_tx_dec_pipe(sk);
654 if (seqp == hctx->ccid2hctx_seqt) {
658 seqp = seqp->ccid2s_prev;
663 ackno = SUB48(ackno_end_rl, 1);
670 /* The state about what is acked should be correct now
671 * Check for NUMDUPACK
673 seqp = hctx->ccid2hctx_seqt;
674 while (before48(seqp->ccid2s_seq, hctx->ccid2hctx_high_ack)) {
675 seqp = seqp->ccid2s_next;
676 if (seqp == hctx->ccid2hctx_seqh) {
677 seqp = hctx->ccid2hctx_seqh->ccid2s_prev;
683 if (seqp->ccid2s_acked) {
685 if (done == NUMDUPACK)
688 if (seqp == hctx->ccid2hctx_seqt)
690 seqp = seqp->ccid2s_prev;
693 /* If there are at least 3 acknowledgements, anything unacknowledged
694 * below the last sequence number is considered lost
696 if (done == NUMDUPACK) {
697 struct ccid2_seq *last_acked = seqp;
699 /* check for lost packets */
701 if (!seqp->ccid2s_acked) {
702 ccid2_pr_debug("Packet lost: %llu\n",
703 (unsigned long long)seqp->ccid2s_seq);
704 /* XXX need to traverse from tail -> head in
705 * order to detect multiple congestion events in
708 ccid2_congestion_event(sk, seqp);
709 ccid2_hc_tx_dec_pipe(sk);
711 if (seqp == hctx->ccid2hctx_seqt)
713 seqp = seqp->ccid2s_prev;
716 hctx->ccid2hctx_seqt = last_acked;
719 /* trim acked packets in tail */
720 while (hctx->ccid2hctx_seqt != hctx->ccid2hctx_seqh) {
721 if (!hctx->ccid2hctx_seqt->ccid2s_acked)
724 hctx->ccid2hctx_seqt = hctx->ccid2hctx_seqt->ccid2s_next;
727 ccid2_hc_tx_check_sanity(hctx);
730 static int ccid2_hc_tx_init(struct ccid *ccid, struct sock *sk)
732 struct ccid2_hc_tx_sock *hctx = ccid_priv(ccid);
733 struct dccp_sock *dp = dccp_sk(sk);
736 /* RFC 4341, 5: initialise ssthresh to arbitrarily high (max) value */
737 hctx->ccid2hctx_ssthresh = ~0U;
740 * RFC 4341, 5: "The cwnd parameter is initialized to at most four
741 * packets for new connections, following the rules from [RFC3390]".
742 * We need to convert the bytes of RFC3390 into the packets of RFC 4341.
744 hctx->ccid2hctx_cwnd = min(4U, max(2U, 4380U / dp->dccps_mss_cache));
746 /* Make sure that Ack Ratio is enabled and within bounds. */
747 max_ratio = DIV_ROUND_UP(hctx->ccid2hctx_cwnd, 2);
748 if (dp->dccps_l_ack_ratio == 0 || dp->dccps_l_ack_ratio > max_ratio)
749 dp->dccps_l_ack_ratio = max_ratio;
751 /* XXX init ~ to window size... */
752 if (ccid2_hc_tx_alloc_seq(hctx))
755 hctx->ccid2hctx_rto = 3 * HZ;
756 ccid2_change_srtt(hctx, -1);
757 hctx->ccid2hctx_rttvar = -1;
758 hctx->ccid2hctx_rpdupack = -1;
759 hctx->ccid2hctx_last_cong = jiffies;
760 setup_timer(&hctx->ccid2hctx_rtotimer, ccid2_hc_tx_rto_expire,
763 ccid2_hc_tx_check_sanity(hctx);
767 static void ccid2_hc_tx_exit(struct sock *sk)
769 struct ccid2_hc_tx_sock *hctx = ccid2_hc_tx_sk(sk);
772 ccid2_hc_tx_kill_rto_timer(sk);
774 for (i = 0; i < hctx->ccid2hctx_seqbufc; i++)
775 kfree(hctx->ccid2hctx_seqbuf[i]);
776 hctx->ccid2hctx_seqbufc = 0;
779 static void ccid2_hc_rx_packet_recv(struct sock *sk, struct sk_buff *skb)
781 const struct dccp_sock *dp = dccp_sk(sk);
782 struct ccid2_hc_rx_sock *hcrx = ccid2_hc_rx_sk(sk);
784 switch (DCCP_SKB_CB(skb)->dccpd_type) {
786 case DCCP_PKT_DATAACK:
787 hcrx->ccid2hcrx_data++;
788 if (hcrx->ccid2hcrx_data >= dp->dccps_r_ack_ratio) {
790 hcrx->ccid2hcrx_data = 0;
796 static struct ccid_operations ccid2 = {
797 .ccid_id = DCCPC_CCID2,
798 .ccid_name = "ccid2",
799 .ccid_owner = THIS_MODULE,
800 .ccid_hc_tx_obj_size = sizeof(struct ccid2_hc_tx_sock),
801 .ccid_hc_tx_init = ccid2_hc_tx_init,
802 .ccid_hc_tx_exit = ccid2_hc_tx_exit,
803 .ccid_hc_tx_send_packet = ccid2_hc_tx_send_packet,
804 .ccid_hc_tx_packet_sent = ccid2_hc_tx_packet_sent,
805 .ccid_hc_tx_packet_recv = ccid2_hc_tx_packet_recv,
806 .ccid_hc_rx_obj_size = sizeof(struct ccid2_hc_rx_sock),
807 .ccid_hc_rx_packet_recv = ccid2_hc_rx_packet_recv,
810 #ifdef CONFIG_IP_DCCP_CCID2_DEBUG
811 module_param(ccid2_debug, bool, 0444);
812 MODULE_PARM_DESC(ccid2_debug, "Enable debug messages");
815 static __init int ccid2_module_init(void)
817 return ccid_register(&ccid2);
819 module_init(ccid2_module_init);
821 static __exit void ccid2_module_exit(void)
823 ccid_unregister(&ccid2);
825 module_exit(ccid2_module_exit);
827 MODULE_AUTHOR("Andrea Bittau <a.bittau@cs.ucl.ac.uk>");
828 MODULE_DESCRIPTION("DCCP TCP-Like (CCID2) CCID");
829 MODULE_LICENSE("GPL");
830 MODULE_ALIAS("net-dccp-ccid-2");