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) {
130 /* OK we can send... make sure previous packet was sent off */
131 if (!hctx->ccid2hctx_sendwait) {
132 hctx->ccid2hctx_sendwait = 1;
137 return 1; /* XXX CCID should dequeue when ready instead of polling */
140 static void ccid2_change_l_ack_ratio(struct sock *sk, u32 val)
142 struct dccp_sock *dp = dccp_sk(sk);
143 u32 max_ratio = DIV_ROUND_UP(ccid2_hc_tx_sk(sk)->ccid2hctx_cwnd, 2);
146 * Ensure that Ack Ratio does not exceed ceil(cwnd/2), which is (2) from
147 * RFC 4341, 6.1.2. We ignore the statement that Ack Ratio 2 is always
148 * acceptable since this causes starvation/deadlock whenever cwnd < 2.
149 * The same problem arises when Ack Ratio is 0 (ie. Ack Ratio disabled).
151 if (val == 0 || val > max_ratio) {
152 DCCP_WARN("Limiting Ack Ratio (%u) to %u\n", val, max_ratio);
155 if (val > 0xFFFF) /* RFC 4340, 11.3 */
158 if (val == dp->dccps_l_ack_ratio)
161 ccid2_pr_debug("changing local ack ratio to %u\n", val);
162 dp->dccps_l_ack_ratio = val;
165 static void ccid2_change_srtt(struct ccid2_hc_tx_sock *hctx, long val)
167 ccid2_pr_debug("change SRTT to %ld\n", val);
168 hctx->ccid2hctx_srtt = val;
171 static void ccid2_start_rto_timer(struct sock *sk);
173 static void ccid2_hc_tx_rto_expire(unsigned long data)
175 struct sock *sk = (struct sock *)data;
176 struct ccid2_hc_tx_sock *hctx = ccid2_hc_tx_sk(sk);
180 if (sock_owned_by_user(sk)) {
181 sk_reset_timer(sk, &hctx->ccid2hctx_rtotimer,
186 ccid2_pr_debug("RTO_EXPIRE\n");
188 ccid2_hc_tx_check_sanity(hctx);
191 hctx->ccid2hctx_rto <<= 1;
193 s = hctx->ccid2hctx_rto / HZ;
195 hctx->ccid2hctx_rto = 60 * HZ;
197 ccid2_start_rto_timer(sk);
199 /* adjust pipe, cwnd etc */
200 hctx->ccid2hctx_ssthresh = hctx->ccid2hctx_cwnd / 2;
201 if (hctx->ccid2hctx_ssthresh < 2)
202 hctx->ccid2hctx_ssthresh = 2;
203 hctx->ccid2hctx_cwnd = 1;
204 hctx->ccid2hctx_pipe = 0;
206 /* clear state about stuff we sent */
207 hctx->ccid2hctx_seqt = hctx->ccid2hctx_seqh;
208 hctx->ccid2hctx_ssacks = 0;
209 hctx->ccid2hctx_acks = 0;
211 /* clear ack ratio state. */
212 hctx->ccid2hctx_rpseq = 0;
213 hctx->ccid2hctx_rpdupack = -1;
214 ccid2_change_l_ack_ratio(sk, 1);
215 ccid2_hc_tx_check_sanity(hctx);
221 static void ccid2_start_rto_timer(struct sock *sk)
223 struct ccid2_hc_tx_sock *hctx = ccid2_hc_tx_sk(sk);
225 ccid2_pr_debug("setting RTO timeout=%ld\n", hctx->ccid2hctx_rto);
227 BUG_ON(timer_pending(&hctx->ccid2hctx_rtotimer));
228 sk_reset_timer(sk, &hctx->ccid2hctx_rtotimer,
229 jiffies + hctx->ccid2hctx_rto);
232 static void ccid2_hc_tx_packet_sent(struct sock *sk, int more, unsigned int len)
234 struct dccp_sock *dp = dccp_sk(sk);
235 struct ccid2_hc_tx_sock *hctx = ccid2_hc_tx_sk(sk);
236 struct ccid2_seq *next;
239 BUG_ON(!hctx->ccid2hctx_sendwait);
240 hctx->ccid2hctx_sendwait = 0;
241 hctx->ccid2hctx_pipe++;
243 /* There is an issue. What if another packet is sent between
244 * packet_send() and packet_sent(). Then the sequence number would be
250 hctx->ccid2hctx_seqh->ccid2s_seq = seq;
251 hctx->ccid2hctx_seqh->ccid2s_acked = 0;
252 hctx->ccid2hctx_seqh->ccid2s_sent = jiffies;
254 next = hctx->ccid2hctx_seqh->ccid2s_next;
255 /* check if we need to alloc more space */
256 if (next == hctx->ccid2hctx_seqt) {
257 if (ccid2_hc_tx_alloc_seq(hctx)) {
258 DCCP_CRIT("packet history - out of memory!");
259 /* FIXME: find a more graceful way to bail out */
262 next = hctx->ccid2hctx_seqh->ccid2s_next;
263 BUG_ON(next == hctx->ccid2hctx_seqt);
265 hctx->ccid2hctx_seqh = next;
267 ccid2_pr_debug("cwnd=%d pipe=%d\n", hctx->ccid2hctx_cwnd,
268 hctx->ccid2hctx_pipe);
271 * FIXME: The code below is broken and the variables have been removed
272 * from the socket struct. The `ackloss' variable was always set to 0,
273 * and with arsent there are several problems:
274 * (i) it doesn't just count the number of Acks, but all sent packets;
275 * (ii) it is expressed in # of packets, not # of windows, so the
276 * comparison below uses the wrong formula: Appendix A of RFC 4341
277 * comes up with the number K = cwnd / (R^2 - R) of consecutive windows
278 * of data with no lost or marked Ack packets. If arsent were the # of
279 * consecutive Acks received without loss, then Ack Ratio needs to be
280 * decreased by 1 when
281 * arsent >= K * cwnd / R = cwnd^2 / (R^3 - R^2)
282 * where cwnd / R is the number of Acks received per window of data
283 * (cf. RFC 4341, App. A). The problems are that
284 * - arsent counts other packets as well;
285 * - the comparison uses a formula different from RFC 4341;
286 * - computing a cubic/quadratic equation each time is too complicated.
287 * Hence a different algorithm is needed.
290 /* Ack Ratio. Need to maintain a concept of how many windows we sent */
291 hctx->ccid2hctx_arsent++;
292 /* We had an ack loss in this window... */
293 if (hctx->ccid2hctx_ackloss) {
294 if (hctx->ccid2hctx_arsent >= hctx->ccid2hctx_cwnd) {
295 hctx->ccid2hctx_arsent = 0;
296 hctx->ccid2hctx_ackloss = 0;
299 /* No acks lost up to now... */
300 /* decrease ack ratio if enough packets were sent */
301 if (dp->dccps_l_ack_ratio > 1) {
302 /* XXX don't calculate denominator each time */
303 int denom = dp->dccps_l_ack_ratio * dp->dccps_l_ack_ratio -
304 dp->dccps_l_ack_ratio;
306 denom = hctx->ccid2hctx_cwnd * hctx->ccid2hctx_cwnd / denom;
308 if (hctx->ccid2hctx_arsent >= denom) {
309 ccid2_change_l_ack_ratio(sk, dp->dccps_l_ack_ratio - 1);
310 hctx->ccid2hctx_arsent = 0;
313 /* we can't increase ack ratio further [1] */
314 hctx->ccid2hctx_arsent = 0; /* or maybe set it to cwnd*/
319 /* setup RTO timer */
320 if (!timer_pending(&hctx->ccid2hctx_rtotimer))
321 ccid2_start_rto_timer(sk);
323 #ifdef CONFIG_IP_DCCP_CCID2_DEBUG
324 ccid2_pr_debug("Sent: seq=%llu\n", (unsigned long long)seq);
326 struct ccid2_seq *seqp = hctx->ccid2hctx_seqt;
328 while (seqp != hctx->ccid2hctx_seqh) {
329 ccid2_pr_debug("out seq=%llu acked=%d time=%lu\n",
330 (unsigned long long)seqp->ccid2s_seq,
331 seqp->ccid2s_acked, seqp->ccid2s_sent);
332 seqp = seqp->ccid2s_next;
335 ccid2_pr_debug("=========\n");
336 ccid2_hc_tx_check_sanity(hctx);
340 /* XXX Lame code duplication!
341 * returns -1 if none was found.
342 * else returns the next offset to use in the function call.
344 static int ccid2_ackvector(struct sock *sk, struct sk_buff *skb, int offset,
345 unsigned char **vec, unsigned char *veclen)
347 const struct dccp_hdr *dh = dccp_hdr(skb);
348 unsigned char *options = (unsigned char *)dh + dccp_hdr_len(skb);
349 unsigned char *opt_ptr;
350 const unsigned char *opt_end = (unsigned char *)dh +
351 (dh->dccph_doff * 4);
352 unsigned char opt, len;
353 unsigned char *value;
358 if (opt_ptr >= opt_end)
361 while (opt_ptr != opt_end) {
366 /* Check if this isn't a single byte option */
367 if (opt > DCCPO_MAX_RESERVED) {
368 if (opt_ptr == opt_end)
369 goto out_invalid_option;
373 goto out_invalid_option;
375 * Remove the type and len fields, leaving
376 * just the value size
382 if (opt_ptr > opt_end)
383 goto out_invalid_option;
387 case DCCPO_ACK_VECTOR_0:
388 case DCCPO_ACK_VECTOR_1:
391 return offset + (opt_ptr - options);
398 DCCP_BUG("Invalid option - this should not happen (previous parsing)!");
402 static void ccid2_hc_tx_kill_rto_timer(struct sock *sk)
404 struct ccid2_hc_tx_sock *hctx = ccid2_hc_tx_sk(sk);
406 sk_stop_timer(sk, &hctx->ccid2hctx_rtotimer);
407 ccid2_pr_debug("deleted RTO timer\n");
410 static inline void ccid2_new_ack(struct sock *sk,
411 struct ccid2_seq *seqp,
412 unsigned int *maxincr)
414 struct ccid2_hc_tx_sock *hctx = ccid2_hc_tx_sk(sk);
417 if (hctx->ccid2hctx_cwnd < hctx->ccid2hctx_ssthresh) {
418 hctx->ccid2hctx_acks = 0;
420 /* We can increase cwnd at most maxincr [ack_ratio/2] */
422 /* increase every 2 acks */
423 hctx->ccid2hctx_ssacks++;
424 if (hctx->ccid2hctx_ssacks == 2) {
425 hctx->ccid2hctx_cwnd++;
426 hctx->ccid2hctx_ssacks = 0;
427 *maxincr = *maxincr - 1;
430 /* increased cwnd enough for this single ack */
431 hctx->ccid2hctx_ssacks = 0;
434 hctx->ccid2hctx_ssacks = 0;
435 hctx->ccid2hctx_acks++;
437 if (hctx->ccid2hctx_acks >= hctx->ccid2hctx_cwnd) {
438 hctx->ccid2hctx_cwnd++;
439 hctx->ccid2hctx_acks = 0;
444 if (hctx->ccid2hctx_srtt == -1 ||
445 time_after(jiffies, hctx->ccid2hctx_lastrtt + hctx->ccid2hctx_srtt)) {
446 unsigned long r = (long)jiffies - (long)seqp->ccid2s_sent;
449 /* first measurement */
450 if (hctx->ccid2hctx_srtt == -1) {
451 ccid2_pr_debug("R: %lu Time=%lu seq=%llu\n",
453 (unsigned long long)seqp->ccid2s_seq);
454 ccid2_change_srtt(hctx, r);
455 hctx->ccid2hctx_rttvar = r >> 1;
458 long tmp = hctx->ccid2hctx_srtt - r;
465 hctx->ccid2hctx_rttvar *= 3;
466 hctx->ccid2hctx_rttvar >>= 2;
467 hctx->ccid2hctx_rttvar += tmp;
470 srtt = hctx->ccid2hctx_srtt;
475 ccid2_change_srtt(hctx, srtt);
477 s = hctx->ccid2hctx_rttvar << 2;
478 /* clock granularity is 1 when based on jiffies */
481 hctx->ccid2hctx_rto = hctx->ccid2hctx_srtt + s;
483 /* must be at least a second */
484 s = hctx->ccid2hctx_rto / HZ;
485 /* DCCP doesn't require this [but I like it cuz my code sux] */
488 hctx->ccid2hctx_rto = HZ;
492 hctx->ccid2hctx_rto = HZ * 60;
494 hctx->ccid2hctx_lastrtt = jiffies;
496 ccid2_pr_debug("srtt: %ld rttvar: %ld rto: %ld (HZ=%d) R=%lu\n",
497 hctx->ccid2hctx_srtt, hctx->ccid2hctx_rttvar,
498 hctx->ccid2hctx_rto, HZ, r);
501 /* we got a new ack, so re-start RTO timer */
502 ccid2_hc_tx_kill_rto_timer(sk);
503 ccid2_start_rto_timer(sk);
506 static void ccid2_hc_tx_dec_pipe(struct sock *sk)
508 struct ccid2_hc_tx_sock *hctx = ccid2_hc_tx_sk(sk);
510 if (hctx->ccid2hctx_pipe == 0)
511 DCCP_BUG("pipe == 0");
513 hctx->ccid2hctx_pipe--;
515 if (hctx->ccid2hctx_pipe == 0)
516 ccid2_hc_tx_kill_rto_timer(sk);
519 static void ccid2_congestion_event(struct sock *sk, struct ccid2_seq *seqp)
521 struct ccid2_hc_tx_sock *hctx = ccid2_hc_tx_sk(sk);
523 if (time_before(seqp->ccid2s_sent, hctx->ccid2hctx_last_cong)) {
524 ccid2_pr_debug("Multiple losses in an RTT---treating as one\n");
528 hctx->ccid2hctx_last_cong = jiffies;
530 hctx->ccid2hctx_cwnd = hctx->ccid2hctx_cwnd / 2 ? : 1U;
531 hctx->ccid2hctx_ssthresh = max(hctx->ccid2hctx_cwnd, 2U);
533 /* Avoid spurious timeouts resulting from Ack Ratio > cwnd */
534 if (dccp_sk(sk)->dccps_l_ack_ratio > hctx->ccid2hctx_cwnd)
535 ccid2_change_l_ack_ratio(sk, hctx->ccid2hctx_cwnd);
538 static void ccid2_hc_tx_packet_recv(struct sock *sk, struct sk_buff *skb)
540 struct dccp_sock *dp = dccp_sk(sk);
541 struct ccid2_hc_tx_sock *hctx = ccid2_hc_tx_sk(sk);
543 struct ccid2_seq *seqp;
544 unsigned char *vector;
545 unsigned char veclen;
548 unsigned int maxincr = 0;
550 ccid2_hc_tx_check_sanity(hctx);
551 /* check reverse path congestion */
552 seqno = DCCP_SKB_CB(skb)->dccpd_seq;
554 /* XXX this whole "algorithm" is broken. Need to fix it to keep track
555 * of the seqnos of the dupacks so that rpseq and rpdupack are correct
558 /* need to bootstrap */
559 if (hctx->ccid2hctx_rpdupack == -1) {
560 hctx->ccid2hctx_rpdupack = 0;
561 hctx->ccid2hctx_rpseq = seqno;
563 /* check if packet is consecutive */
564 if (dccp_delta_seqno(hctx->ccid2hctx_rpseq, seqno) == 1)
565 hctx->ccid2hctx_rpseq = seqno;
566 /* it's a later packet */
567 else if (after48(seqno, hctx->ccid2hctx_rpseq)) {
568 hctx->ccid2hctx_rpdupack++;
570 /* check if we got enough dupacks */
571 if (hctx->ccid2hctx_rpdupack >= NUMDUPACK) {
572 hctx->ccid2hctx_rpdupack = -1; /* XXX lame */
573 hctx->ccid2hctx_rpseq = 0;
575 ccid2_change_l_ack_ratio(sk, 2 * dp->dccps_l_ack_ratio);
580 /* check forward path congestion */
581 /* still didn't send out new data packets */
582 if (hctx->ccid2hctx_seqh == hctx->ccid2hctx_seqt)
585 switch (DCCP_SKB_CB(skb)->dccpd_type) {
587 case DCCP_PKT_DATAACK:
593 ackno = DCCP_SKB_CB(skb)->dccpd_ack_seq;
594 if (after48(ackno, hctx->ccid2hctx_high_ack))
595 hctx->ccid2hctx_high_ack = ackno;
597 seqp = hctx->ccid2hctx_seqt;
598 while (before48(seqp->ccid2s_seq, ackno)) {
599 seqp = seqp->ccid2s_next;
600 if (seqp == hctx->ccid2hctx_seqh) {
601 seqp = hctx->ccid2hctx_seqh->ccid2s_prev;
606 /* If in slow-start, cwnd can increase at most Ack Ratio / 2 packets for
607 * this single ack. I round up.
610 maxincr = dp->dccps_l_ack_ratio >> 1;
613 /* go through all ack vectors */
614 while ((offset = ccid2_ackvector(sk, skb, offset,
615 &vector, &veclen)) != -1) {
616 /* go through this ack vector */
618 const u8 rl = *vector & DCCP_ACKVEC_LEN_MASK;
619 u64 ackno_end_rl = SUB48(ackno, rl);
621 ccid2_pr_debug("ackvec start:%llu end:%llu\n",
622 (unsigned long long)ackno,
623 (unsigned long long)ackno_end_rl);
624 /* if the seqno we are analyzing is larger than the
625 * current ackno, then move towards the tail of our
628 while (after48(seqp->ccid2s_seq, ackno)) {
629 if (seqp == hctx->ccid2hctx_seqt) {
633 seqp = seqp->ccid2s_prev;
638 /* check all seqnos in the range of the vector
641 while (between48(seqp->ccid2s_seq,ackno_end_rl,ackno)) {
642 const u8 state = *vector &
643 DCCP_ACKVEC_STATE_MASK;
645 /* new packet received or marked */
646 if (state != DCCP_ACKVEC_STATE_NOT_RECEIVED &&
647 !seqp->ccid2s_acked) {
649 DCCP_ACKVEC_STATE_ECN_MARKED) {
650 ccid2_congestion_event(sk,
653 ccid2_new_ack(sk, seqp,
656 seqp->ccid2s_acked = 1;
657 ccid2_pr_debug("Got ack for %llu\n",
658 (unsigned long long)seqp->ccid2s_seq);
659 ccid2_hc_tx_dec_pipe(sk);
661 if (seqp == hctx->ccid2hctx_seqt) {
665 seqp = seqp->ccid2s_prev;
670 ackno = SUB48(ackno_end_rl, 1);
677 /* The state about what is acked should be correct now
678 * Check for NUMDUPACK
680 seqp = hctx->ccid2hctx_seqt;
681 while (before48(seqp->ccid2s_seq, hctx->ccid2hctx_high_ack)) {
682 seqp = seqp->ccid2s_next;
683 if (seqp == hctx->ccid2hctx_seqh) {
684 seqp = hctx->ccid2hctx_seqh->ccid2s_prev;
690 if (seqp->ccid2s_acked) {
692 if (done == NUMDUPACK)
695 if (seqp == hctx->ccid2hctx_seqt)
697 seqp = seqp->ccid2s_prev;
700 /* If there are at least 3 acknowledgements, anything unacknowledged
701 * below the last sequence number is considered lost
703 if (done == NUMDUPACK) {
704 struct ccid2_seq *last_acked = seqp;
706 /* check for lost packets */
708 if (!seqp->ccid2s_acked) {
709 ccid2_pr_debug("Packet lost: %llu\n",
710 (unsigned long long)seqp->ccid2s_seq);
711 /* XXX need to traverse from tail -> head in
712 * order to detect multiple congestion events in
715 ccid2_congestion_event(sk, seqp);
716 ccid2_hc_tx_dec_pipe(sk);
718 if (seqp == hctx->ccid2hctx_seqt)
720 seqp = seqp->ccid2s_prev;
723 hctx->ccid2hctx_seqt = last_acked;
726 /* trim acked packets in tail */
727 while (hctx->ccid2hctx_seqt != hctx->ccid2hctx_seqh) {
728 if (!hctx->ccid2hctx_seqt->ccid2s_acked)
731 hctx->ccid2hctx_seqt = hctx->ccid2hctx_seqt->ccid2s_next;
734 ccid2_hc_tx_check_sanity(hctx);
737 static int ccid2_hc_tx_init(struct ccid *ccid, struct sock *sk)
739 struct ccid2_hc_tx_sock *hctx = ccid_priv(ccid);
740 struct dccp_sock *dp = dccp_sk(sk);
743 /* RFC 4341, 5: initialise ssthresh to arbitrarily high (max) value */
744 hctx->ccid2hctx_ssthresh = ~0U;
747 * RFC 4341, 5: "The cwnd parameter is initialized to at most four
748 * packets for new connections, following the rules from [RFC3390]".
749 * We need to convert the bytes of RFC3390 into the packets of RFC 4341.
751 hctx->ccid2hctx_cwnd = min(4U, max(2U, 4380U / dp->dccps_mss_cache));
753 /* Make sure that Ack Ratio is enabled and within bounds. */
754 max_ratio = DIV_ROUND_UP(hctx->ccid2hctx_cwnd, 2);
755 if (dp->dccps_l_ack_ratio == 0 || dp->dccps_l_ack_ratio > max_ratio)
756 dp->dccps_l_ack_ratio = max_ratio;
758 /* XXX init ~ to window size... */
759 if (ccid2_hc_tx_alloc_seq(hctx))
762 hctx->ccid2hctx_rto = 3 * HZ;
763 ccid2_change_srtt(hctx, -1);
764 hctx->ccid2hctx_rttvar = -1;
765 hctx->ccid2hctx_rpdupack = -1;
766 hctx->ccid2hctx_last_cong = jiffies;
767 setup_timer(&hctx->ccid2hctx_rtotimer, ccid2_hc_tx_rto_expire,
770 ccid2_hc_tx_check_sanity(hctx);
774 static void ccid2_hc_tx_exit(struct sock *sk)
776 struct ccid2_hc_tx_sock *hctx = ccid2_hc_tx_sk(sk);
779 ccid2_hc_tx_kill_rto_timer(sk);
781 for (i = 0; i < hctx->ccid2hctx_seqbufc; i++)
782 kfree(hctx->ccid2hctx_seqbuf[i]);
783 hctx->ccid2hctx_seqbufc = 0;
786 static void ccid2_hc_rx_packet_recv(struct sock *sk, struct sk_buff *skb)
788 const struct dccp_sock *dp = dccp_sk(sk);
789 struct ccid2_hc_rx_sock *hcrx = ccid2_hc_rx_sk(sk);
791 switch (DCCP_SKB_CB(skb)->dccpd_type) {
793 case DCCP_PKT_DATAACK:
794 hcrx->ccid2hcrx_data++;
795 if (hcrx->ccid2hcrx_data >= dp->dccps_r_ack_ratio) {
797 hcrx->ccid2hcrx_data = 0;
803 static struct ccid_operations ccid2 = {
804 .ccid_id = DCCPC_CCID2,
805 .ccid_name = "ccid2",
806 .ccid_owner = THIS_MODULE,
807 .ccid_hc_tx_obj_size = sizeof(struct ccid2_hc_tx_sock),
808 .ccid_hc_tx_init = ccid2_hc_tx_init,
809 .ccid_hc_tx_exit = ccid2_hc_tx_exit,
810 .ccid_hc_tx_send_packet = ccid2_hc_tx_send_packet,
811 .ccid_hc_tx_packet_sent = ccid2_hc_tx_packet_sent,
812 .ccid_hc_tx_packet_recv = ccid2_hc_tx_packet_recv,
813 .ccid_hc_rx_obj_size = sizeof(struct ccid2_hc_rx_sock),
814 .ccid_hc_rx_packet_recv = ccid2_hc_rx_packet_recv,
817 #ifdef CONFIG_IP_DCCP_CCID2_DEBUG
818 module_param(ccid2_debug, bool, 0444);
819 MODULE_PARM_DESC(ccid2_debug, "Enable debug messages");
822 static __init int ccid2_module_init(void)
824 return ccid_register(&ccid2);
826 module_init(ccid2_module_init);
828 static __exit void ccid2_module_exit(void)
830 ccid_unregister(&ccid2);
832 module_exit(ccid2_module_exit);
834 MODULE_AUTHOR("Andrea Bittau <a.bittau@cs.ucl.ac.uk>");
835 MODULE_DESCRIPTION("DCCP TCP-Like (CCID2) CCID");
836 MODULE_LICENSE("GPL");
837 MODULE_ALIAS("net-dccp-ccid-2");