4 * An implementation of the DCCP protocol
5 * Arnaldo Carvalho de Melo <acme@conectiva.com.br>
7 * This program is free software; you can redistribute it and/or
8 * modify it under the terms of the GNU General Public License
9 * as published by the Free Software Foundation; either version
10 * 2 of the License, or (at your option) any later version.
13 #include <linux/dccp.h>
14 #include <linux/skbuff.h>
22 /* rate-limit for syncs in reply to sequence-invalid packets; RFC 4340, 7.5.4 */
23 int sysctl_dccp_sync_ratelimit __read_mostly = HZ / 8;
25 static void dccp_enqueue_skb(struct sock *sk, struct sk_buff *skb)
27 __skb_pull(skb, dccp_hdr(skb)->dccph_doff * 4);
28 __skb_queue_tail(&sk->sk_receive_queue, skb);
29 skb_set_owner_r(skb, sk);
30 sk->sk_data_ready(sk, 0);
33 static void dccp_fin(struct sock *sk, struct sk_buff *skb)
36 * On receiving Close/CloseReq, both RD/WR shutdown are performed.
37 * RFC 4340, 8.3 says that we MAY send further Data/DataAcks after
38 * receiving the closing segment, but there is no guarantee that such
39 * data will be processed at all.
41 sk->sk_shutdown = SHUTDOWN_MASK;
42 sock_set_flag(sk, SOCK_DONE);
43 dccp_enqueue_skb(sk, skb);
46 static int dccp_rcv_close(struct sock *sk, struct sk_buff *skb)
50 switch (sk->sk_state) {
52 * We ignore Close when received in one of the following states:
53 * - CLOSED (may be a late or duplicate packet)
54 * - PASSIVE_CLOSEREQ (the peer has sent a CloseReq earlier)
55 * - RESPOND (already handled by dccp_check_req)
59 * Simultaneous-close: receiving a Close after sending one. This
60 * can happen if both client and server perform active-close and
61 * will result in an endless ping-pong of crossing and retrans-
62 * mitted Close packets, which only terminates when one of the
63 * nodes times out (min. 64 seconds). Quicker convergence can be
64 * achieved when one of the nodes acts as tie-breaker.
65 * This is ok as both ends are done with data transfer and each
66 * end is just waiting for the other to acknowledge termination.
68 if (dccp_sk(sk)->dccps_role != DCCP_ROLE_CLIENT)
72 case DCCP_ACTIVE_CLOSEREQ:
73 dccp_send_reset(sk, DCCP_RESET_CODE_CLOSED);
78 /* Give waiting application a chance to read pending data */
81 dccp_set_state(sk, DCCP_PASSIVE_CLOSE);
83 case DCCP_PASSIVE_CLOSE:
85 * Retransmitted Close: we have already enqueued the first one.
87 sk_wake_async(sk, SOCK_WAKE_WAITD, POLL_HUP);
92 static int dccp_rcv_closereq(struct sock *sk, struct sk_buff *skb)
97 * Step 7: Check for unexpected packet types
98 * If (S.is_server and P.type == CloseReq)
99 * Send Sync packet acknowledging P.seqno
100 * Drop packet and return
102 if (dccp_sk(sk)->dccps_role != DCCP_ROLE_CLIENT) {
103 dccp_send_sync(sk, DCCP_SKB_CB(skb)->dccpd_seq, DCCP_PKT_SYNC);
107 /* Step 13: process relevant Client states < CLOSEREQ */
108 switch (sk->sk_state) {
109 case DCCP_REQUESTING:
110 dccp_send_close(sk, 0);
111 dccp_set_state(sk, DCCP_CLOSING);
115 /* Give waiting application a chance to read pending data */
118 dccp_set_state(sk, DCCP_PASSIVE_CLOSEREQ);
120 case DCCP_PASSIVE_CLOSEREQ:
121 sk_wake_async(sk, SOCK_WAKE_WAITD, POLL_HUP);
126 static u8 dccp_reset_code_convert(const u8 code)
128 const u8 error_code[] = {
129 [DCCP_RESET_CODE_CLOSED] = 0, /* normal termination */
130 [DCCP_RESET_CODE_UNSPECIFIED] = 0, /* nothing known */
131 [DCCP_RESET_CODE_ABORTED] = ECONNRESET,
133 [DCCP_RESET_CODE_NO_CONNECTION] = ECONNREFUSED,
134 [DCCP_RESET_CODE_CONNECTION_REFUSED] = ECONNREFUSED,
135 [DCCP_RESET_CODE_TOO_BUSY] = EUSERS,
136 [DCCP_RESET_CODE_AGGRESSION_PENALTY] = EDQUOT,
138 [DCCP_RESET_CODE_PACKET_ERROR] = ENOMSG,
139 [DCCP_RESET_CODE_BAD_INIT_COOKIE] = EBADR,
140 [DCCP_RESET_CODE_BAD_SERVICE_CODE] = EBADRQC,
141 [DCCP_RESET_CODE_OPTION_ERROR] = EILSEQ,
142 [DCCP_RESET_CODE_MANDATORY_ERROR] = EOPNOTSUPP,
145 return code >= DCCP_MAX_RESET_CODES ? 0 : error_code[code];
148 static void dccp_rcv_reset(struct sock *sk, struct sk_buff *skb)
150 u8 err = dccp_reset_code_convert(dccp_hdr_reset(skb)->dccph_reset_code);
154 /* Queue the equivalent of TCP fin so that dccp_recvmsg exits the loop */
157 if (err && !sock_flag(sk, SOCK_DEAD))
158 sk_wake_async(sk, SOCK_WAKE_IO, POLL_ERR);
159 dccp_time_wait(sk, DCCP_TIME_WAIT, 0);
162 static void dccp_event_ack_recv(struct sock *sk, struct sk_buff *skb)
164 struct dccp_sock *dp = dccp_sk(sk);
166 if (dccp_msk(sk)->dccpms_send_ack_vector)
167 dccp_ackvec_check_rcv_ackno(dp->dccps_hc_rx_ackvec, sk,
168 DCCP_SKB_CB(skb)->dccpd_ack_seq);
171 static void dccp_deliver_input_to_ccids(struct sock *sk, struct sk_buff *skb)
173 const struct dccp_sock *dp = dccp_sk(sk);
175 /* Don't deliver to RX CCID when node has shut down read end. */
176 if (!(sk->sk_shutdown & RCV_SHUTDOWN))
177 ccid_hc_rx_packet_recv(dp->dccps_hc_rx_ccid, sk, skb);
179 * Until the TX queue has been drained, we can not honour SHUT_WR, since
180 * we need received feedback as input to adjust congestion control.
182 if (sk->sk_write_queue.qlen > 0 || !(sk->sk_shutdown & SEND_SHUTDOWN))
183 ccid_hc_tx_packet_recv(dp->dccps_hc_tx_ccid, sk, skb);
186 static int dccp_check_seqno(struct sock *sk, struct sk_buff *skb)
188 const struct dccp_hdr *dh = dccp_hdr(skb);
189 struct dccp_sock *dp = dccp_sk(sk);
190 u64 lswl, lawl, seqno = DCCP_SKB_CB(skb)->dccpd_seq,
191 ackno = DCCP_SKB_CB(skb)->dccpd_ack_seq;
194 * Step 5: Prepare sequence numbers for Sync
195 * If P.type == Sync or P.type == SyncAck,
196 * If S.AWL <= P.ackno <= S.AWH and P.seqno >= S.SWL,
197 * / * P is valid, so update sequence number variables
198 * accordingly. After this update, P will pass the tests
199 * in Step 6. A SyncAck is generated if necessary in
201 * Update S.GSR, S.SWL, S.SWH
203 * Drop packet and return
205 if (dh->dccph_type == DCCP_PKT_SYNC ||
206 dh->dccph_type == DCCP_PKT_SYNCACK) {
207 if (between48(ackno, dp->dccps_awl, dp->dccps_awh) &&
208 dccp_delta_seqno(dp->dccps_swl, seqno) >= 0)
209 dccp_update_gsr(sk, seqno);
215 * Step 6: Check sequence numbers
216 * Let LSWL = S.SWL and LAWL = S.AWL
217 * If P.type == CloseReq or P.type == Close or P.type == Reset,
218 * LSWL := S.GSR + 1, LAWL := S.GAR
219 * If LSWL <= P.seqno <= S.SWH
220 * and (P.ackno does not exist or LAWL <= P.ackno <= S.AWH),
221 * Update S.GSR, S.SWL, S.SWH
225 lswl = dp->dccps_swl;
226 lawl = dp->dccps_awl;
228 if (dh->dccph_type == DCCP_PKT_CLOSEREQ ||
229 dh->dccph_type == DCCP_PKT_CLOSE ||
230 dh->dccph_type == DCCP_PKT_RESET) {
231 lswl = ADD48(dp->dccps_gsr, 1);
232 lawl = dp->dccps_gar;
235 if (between48(seqno, lswl, dp->dccps_swh) &&
236 (ackno == DCCP_PKT_WITHOUT_ACK_SEQ ||
237 between48(ackno, lawl, dp->dccps_awh))) {
238 dccp_update_gsr(sk, seqno);
240 if (dh->dccph_type != DCCP_PKT_SYNC &&
241 (ackno != DCCP_PKT_WITHOUT_ACK_SEQ))
242 dp->dccps_gar = ackno;
244 unsigned long now = jiffies;
246 * Step 6: Check sequence numbers
248 * If P.type == Reset,
249 * Send Sync packet acknowledging S.GSR
251 * Send Sync packet acknowledging P.seqno
252 * Drop packet and return
254 * These Syncs are rate-limited as per RFC 4340, 7.5.4:
255 * at most 1 / (dccp_sync_rate_limit * HZ) Syncs per second.
257 if (time_before(now, (dp->dccps_rate_last +
258 sysctl_dccp_sync_ratelimit)))
261 DCCP_WARN("DCCP: Step 6 failed for %s packet, "
262 "(LSWL(%llu) <= P.seqno(%llu) <= S.SWH(%llu)) and "
263 "(P.ackno %s or LAWL(%llu) <= P.ackno(%llu) <= S.AWH(%llu), "
264 "sending SYNC...\n", dccp_packet_name(dh->dccph_type),
265 (unsigned long long) lswl, (unsigned long long) seqno,
266 (unsigned long long) dp->dccps_swh,
267 (ackno == DCCP_PKT_WITHOUT_ACK_SEQ) ? "doesn't exist"
269 (unsigned long long) lawl, (unsigned long long) ackno,
270 (unsigned long long) dp->dccps_awh);
272 dp->dccps_rate_last = now;
274 if (dh->dccph_type == DCCP_PKT_RESET)
275 seqno = dp->dccps_gsr;
276 dccp_send_sync(sk, seqno, DCCP_PKT_SYNC);
283 static int __dccp_rcv_established(struct sock *sk, struct sk_buff *skb,
284 const struct dccp_hdr *dh, const unsigned len)
286 struct dccp_sock *dp = dccp_sk(sk);
288 switch (dccp_hdr(skb)->dccph_type) {
289 case DCCP_PKT_DATAACK:
292 * FIXME: schedule DATA_DROPPED (RFC 4340, 11.7.2) if and when
293 * - sk_shutdown == RCV_SHUTDOWN, use Code 1, "Not Listening"
294 * - sk_receive_queue is full, use Code 2, "Receive Buffer"
296 dccp_enqueue_skb(sk, skb);
302 * Step 9: Process Reset
303 * If P.type == Reset,
304 * Tear down connection
305 * S.state := TIMEWAIT
307 * Drop packet and return
309 dccp_rcv_reset(sk, skb);
311 case DCCP_PKT_CLOSEREQ:
312 if (dccp_rcv_closereq(sk, skb))
316 if (dccp_rcv_close(sk, skb))
319 case DCCP_PKT_REQUEST:
321 * or (S.is_server and P.type == Response)
322 * or (S.is_client and P.type == Request)
323 * or (S.state >= OPEN and P.type == Request
324 * and P.seqno >= S.OSR)
325 * or (S.state >= OPEN and P.type == Response
326 * and P.seqno >= S.OSR)
327 * or (S.state == RESPOND and P.type == Data),
328 * Send Sync packet acknowledging P.seqno
329 * Drop packet and return
331 if (dp->dccps_role != DCCP_ROLE_LISTEN)
334 case DCCP_PKT_RESPONSE:
335 if (dp->dccps_role != DCCP_ROLE_CLIENT)
338 if (dccp_delta_seqno(dp->dccps_osr,
339 DCCP_SKB_CB(skb)->dccpd_seq) >= 0) {
341 dccp_send_sync(sk, DCCP_SKB_CB(skb)->dccpd_seq,
346 dccp_send_sync(sk, DCCP_SKB_CB(skb)->dccpd_seq,
349 * From RFC 4340, sec. 5.7
351 * As with DCCP-Ack packets, DCCP-Sync and DCCP-SyncAck packets
352 * MAY have non-zero-length application data areas, whose
353 * contents receivers MUST ignore.
358 DCCP_INC_STATS_BH(DCCP_MIB_INERRS);
364 int dccp_rcv_established(struct sock *sk, struct sk_buff *skb,
365 const struct dccp_hdr *dh, const unsigned len)
367 struct dccp_sock *dp = dccp_sk(sk);
369 if (dccp_check_seqno(sk, skb))
372 if (dccp_parse_options(sk, NULL, skb))
375 if (DCCP_SKB_CB(skb)->dccpd_ack_seq != DCCP_PKT_WITHOUT_ACK_SEQ)
376 dccp_event_ack_recv(sk, skb);
378 if (dccp_msk(sk)->dccpms_send_ack_vector &&
379 dccp_ackvec_add(dp->dccps_hc_rx_ackvec, sk,
380 DCCP_SKB_CB(skb)->dccpd_seq,
381 DCCP_ACKVEC_STATE_RECEIVED))
383 dccp_deliver_input_to_ccids(sk, skb);
385 return __dccp_rcv_established(sk, skb, dh, len);
391 EXPORT_SYMBOL_GPL(dccp_rcv_established);
393 static int dccp_rcv_request_sent_state_process(struct sock *sk,
395 const struct dccp_hdr *dh,
399 * Step 4: Prepare sequence numbers in REQUEST
400 * If S.state == REQUEST,
401 * If (P.type == Response or P.type == Reset)
402 * and S.AWL <= P.ackno <= S.AWH,
403 * / * Set sequence number variables corresponding to the
404 * other endpoint, so P will pass the tests in Step 6 * /
405 * Set S.GSR, S.ISR, S.SWL, S.SWH
406 * / * Response processing continues in Step 10; Reset
407 * processing continues in Step 9 * /
409 if (dh->dccph_type == DCCP_PKT_RESPONSE) {
410 const struct inet_connection_sock *icsk = inet_csk(sk);
411 struct dccp_sock *dp = dccp_sk(sk);
412 long tstamp = dccp_timestamp();
414 if (!between48(DCCP_SKB_CB(skb)->dccpd_ack_seq,
415 dp->dccps_awl, dp->dccps_awh)) {
416 dccp_pr_debug("invalid ackno: S.AWL=%llu, "
417 "P.ackno=%llu, S.AWH=%llu \n",
418 (unsigned long long)dp->dccps_awl,
419 (unsigned long long)DCCP_SKB_CB(skb)->dccpd_ack_seq,
420 (unsigned long long)dp->dccps_awh);
421 goto out_invalid_packet;
425 * If option processing (Step 8) failed, return 1 here so that
426 * dccp_v4_do_rcv() sends a Reset. The Reset code depends on
427 * the option type and is set in dccp_parse_options().
429 if (dccp_parse_options(sk, NULL, skb))
432 /* Obtain usec RTT sample from SYN exchange (used by CCID 3) */
433 if (likely(dp->dccps_options_received.dccpor_timestamp_echo))
434 dp->dccps_syn_rtt = dccp_sample_rtt(sk, 10 * (tstamp -
435 dp->dccps_options_received.dccpor_timestamp_echo));
437 if (dccp_msk(sk)->dccpms_send_ack_vector &&
438 dccp_ackvec_add(dp->dccps_hc_rx_ackvec, sk,
439 DCCP_SKB_CB(skb)->dccpd_seq,
440 DCCP_ACKVEC_STATE_RECEIVED))
441 goto out_invalid_packet; /* FIXME: change error code */
443 /* Stop the REQUEST timer */
444 inet_csk_clear_xmit_timer(sk, ICSK_TIME_RETRANS);
445 WARN_ON(sk->sk_send_head == NULL);
446 kfree_skb(sk->sk_send_head);
447 sk->sk_send_head = NULL;
449 dp->dccps_isr = DCCP_SKB_CB(skb)->dccpd_seq;
450 dccp_update_gsr(sk, dp->dccps_isr);
452 * SWL and AWL are initially adjusted so that they are not less than
453 * the initial Sequence Numbers received and sent, respectively:
454 * SWL := max(GSR + 1 - floor(W/4), ISR),
455 * AWL := max(GSS - W' + 1, ISS).
456 * These adjustments MUST be applied only at the beginning of the
459 * AWL was adjusted in dccp_v4_connect -acme
461 dccp_set_seqno(&dp->dccps_swl,
462 max48(dp->dccps_swl, dp->dccps_isr));
464 dccp_sync_mss(sk, icsk->icsk_pmtu_cookie);
467 * Step 10: Process REQUEST state (second part)
468 * If S.state == REQUEST,
469 * / * If we get here, P is a valid Response from the
470 * server (see Step 4), and we should move to
471 * PARTOPEN state. PARTOPEN means send an Ack,
472 * don't send Data packets, retransmit Acks
473 * periodically, and always include any Init Cookie
474 * from the Response * /
475 * S.state := PARTOPEN
477 * Continue with S.state == PARTOPEN
478 * / * Step 12 will send the Ack completing the
479 * three-way handshake * /
481 dccp_set_state(sk, DCCP_PARTOPEN);
484 * If feature negotiation was successful, activate features now;
485 * an activation failure means that this host could not activate
486 * one ore more features (e.g. insufficient memory), which would
487 * leave at least one feature in an undefined state.
489 if (dccp_feat_activate_values(sk, &dp->dccps_featneg))
490 goto unable_to_proceed;
492 /* Make sure socket is routed, for correct metrics. */
493 icsk->icsk_af_ops->rebuild_header(sk);
495 if (!sock_flag(sk, SOCK_DEAD)) {
496 sk->sk_state_change(sk);
497 sk_wake_async(sk, SOCK_WAKE_IO, POLL_OUT);
500 if (sk->sk_write_pending || icsk->icsk_ack.pingpong ||
501 icsk->icsk_accept_queue.rskq_defer_accept) {
502 /* Save one ACK. Data will be ready after
503 * several ticks, if write_pending is set.
505 * It may be deleted, but with this feature tcpdumps
506 * look so _wonderfully_ clever, that I was not able
507 * to stand against the temptation 8) --ANK
510 * OK, in DCCP we can as well do a similar trick, its
511 * even in the draft, but there is no need for us to
512 * schedule an ack here, as dccp_sendmsg does this for
513 * us, also stated in the draft. -acme
523 /* dccp_v4_do_rcv will send a reset */
524 DCCP_SKB_CB(skb)->dccpd_reset_code = DCCP_RESET_CODE_PACKET_ERROR;
528 DCCP_SKB_CB(skb)->dccpd_reset_code = DCCP_RESET_CODE_ABORTED;
530 * We mark this socket as no longer usable, so that the loop in
531 * dccp_sendmsg() terminates and the application gets notified.
533 dccp_set_state(sk, DCCP_CLOSED);
538 static int dccp_rcv_respond_partopen_state_process(struct sock *sk,
540 const struct dccp_hdr *dh,
545 switch (dh->dccph_type) {
547 inet_csk_clear_xmit_timer(sk, ICSK_TIME_DACK);
550 if (sk->sk_state == DCCP_RESPOND)
552 case DCCP_PKT_DATAACK:
555 * FIXME: we should be reseting the PARTOPEN (DELACK) timer
556 * here but only if we haven't used the DELACK timer for
557 * something else, like sending a delayed ack for a TIMESTAMP
558 * echo, etc, for now were not clearing it, sending an extra
559 * ACK when there is nothing else to do in DELACK is not a big
563 /* Stop the PARTOPEN timer */
564 if (sk->sk_state == DCCP_PARTOPEN)
565 inet_csk_clear_xmit_timer(sk, ICSK_TIME_DACK);
567 dccp_sk(sk)->dccps_osr = DCCP_SKB_CB(skb)->dccpd_seq;
568 dccp_set_state(sk, DCCP_OPEN);
570 if (dh->dccph_type == DCCP_PKT_DATAACK ||
571 dh->dccph_type == DCCP_PKT_DATA) {
572 __dccp_rcv_established(sk, skb, dh, len);
573 queued = 1; /* packet was queued
574 (by __dccp_rcv_established) */
582 int dccp_rcv_state_process(struct sock *sk, struct sk_buff *skb,
583 struct dccp_hdr *dh, unsigned len)
585 struct dccp_sock *dp = dccp_sk(sk);
586 struct dccp_skb_cb *dcb = DCCP_SKB_CB(skb);
587 const int old_state = sk->sk_state;
591 * Step 3: Process LISTEN state
593 * If S.state == LISTEN,
594 * If P.type == Request or P contains a valid Init Cookie option,
595 * (* Must scan the packet's options to check for Init
596 * Cookies. Only Init Cookies are processed here,
597 * however; other options are processed in Step 8. This
598 * scan need only be performed if the endpoint uses Init
600 * (* Generate a new socket and switch to that socket *)
601 * Set S := new socket for this port pair
603 * Choose S.ISS (initial seqno) or set from Init Cookies
604 * Initialize S.GAR := S.ISS
605 * Set S.ISR, S.GSR, S.SWL, S.SWH from packet or Init
606 * Cookies Continue with S.state == RESPOND
607 * (* A Response packet will be generated in Step 11 *)
609 * Generate Reset(No Connection) unless P.type == Reset
610 * Drop packet and return
612 if (sk->sk_state == DCCP_LISTEN) {
613 if (dh->dccph_type == DCCP_PKT_REQUEST) {
614 if (inet_csk(sk)->icsk_af_ops->conn_request(sk,
619 if (dh->dccph_type == DCCP_PKT_RESET)
622 /* Caller (dccp_v4_do_rcv) will send Reset */
623 dcb->dccpd_reset_code = DCCP_RESET_CODE_NO_CONNECTION;
627 if (sk->sk_state != DCCP_REQUESTING && sk->sk_state != DCCP_RESPOND) {
628 if (dccp_check_seqno(sk, skb))
632 * Step 8: Process options and mark acknowledgeable
634 if (dccp_parse_options(sk, NULL, skb))
637 if (dcb->dccpd_ack_seq != DCCP_PKT_WITHOUT_ACK_SEQ)
638 dccp_event_ack_recv(sk, skb);
640 if (dccp_msk(sk)->dccpms_send_ack_vector &&
641 dccp_ackvec_add(dp->dccps_hc_rx_ackvec, sk,
642 DCCP_SKB_CB(skb)->dccpd_seq,
643 DCCP_ACKVEC_STATE_RECEIVED))
646 dccp_deliver_input_to_ccids(sk, skb);
650 * Step 9: Process Reset
651 * If P.type == Reset,
652 * Tear down connection
653 * S.state := TIMEWAIT
655 * Drop packet and return
657 if (dh->dccph_type == DCCP_PKT_RESET) {
658 dccp_rcv_reset(sk, skb);
661 * Step 7: Check for unexpected packet types
662 * If (S.is_server and P.type == Response)
663 * or (S.is_client and P.type == Request)
664 * or (S.state == RESPOND and P.type == Data),
665 * Send Sync packet acknowledging P.seqno
666 * Drop packet and return
668 } else if ((dp->dccps_role != DCCP_ROLE_CLIENT &&
669 dh->dccph_type == DCCP_PKT_RESPONSE) ||
670 (dp->dccps_role == DCCP_ROLE_CLIENT &&
671 dh->dccph_type == DCCP_PKT_REQUEST) ||
672 (sk->sk_state == DCCP_RESPOND &&
673 dh->dccph_type == DCCP_PKT_DATA)) {
674 dccp_send_sync(sk, dcb->dccpd_seq, DCCP_PKT_SYNC);
676 } else if (dh->dccph_type == DCCP_PKT_CLOSEREQ) {
677 if (dccp_rcv_closereq(sk, skb))
680 } else if (dh->dccph_type == DCCP_PKT_CLOSE) {
681 if (dccp_rcv_close(sk, skb))
686 switch (sk->sk_state) {
688 dcb->dccpd_reset_code = DCCP_RESET_CODE_NO_CONNECTION;
691 case DCCP_REQUESTING:
692 queued = dccp_rcv_request_sent_state_process(sk, skb, dh, len);
701 queued = dccp_rcv_respond_partopen_state_process(sk, skb,
706 if (dh->dccph_type == DCCP_PKT_ACK ||
707 dh->dccph_type == DCCP_PKT_DATAACK) {
710 sk->sk_state_change(sk);
711 sk_wake_async(sk, SOCK_WAKE_IO, POLL_OUT);
714 } else if (unlikely(dh->dccph_type == DCCP_PKT_SYNC)) {
715 dccp_send_sync(sk, dcb->dccpd_seq, DCCP_PKT_SYNCACK);
726 EXPORT_SYMBOL_GPL(dccp_rcv_state_process);
729 * dccp_sample_rtt - Validate and finalise computation of RTT sample
730 * @delta: number of microseconds between packet and acknowledgment
731 * The routine is kept generic to work in different contexts. It should be
732 * called immediately when the ACK used for the RTT sample arrives.
734 u32 dccp_sample_rtt(struct sock *sk, long delta)
736 /* dccpor_elapsed_time is either zeroed out or set and > 0 */
737 delta -= dccp_sk(sk)->dccps_options_received.dccpor_elapsed_time * 10;
739 if (unlikely(delta <= 0)) {
740 DCCP_WARN("unusable RTT sample %ld, using min\n", delta);
741 return DCCP_SANE_RTT_MIN;
743 if (unlikely(delta > DCCP_SANE_RTT_MAX)) {
744 DCCP_WARN("RTT sample %ld too large, using max\n", delta);
745 return DCCP_SANE_RTT_MAX;
751 EXPORT_SYMBOL_GPL(dccp_sample_rtt);