[DCCP]: Provide function for RTT sampling
[linux-3.10.git] / net / dccp / input.c
1 /*
2  *  net/dccp/input.c
3  *
4  *  An implementation of the DCCP protocol
5  *  Arnaldo Carvalho de Melo <acme@conectiva.com.br>
6  *
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.
11  */
12
13 #include <linux/dccp.h>
14 #include <linux/skbuff.h>
15
16 #include <net/sock.h>
17
18 #include "ackvec.h"
19 #include "ccid.h"
20 #include "dccp.h"
21
22 static void dccp_fin(struct sock *sk, struct sk_buff *skb)
23 {
24         sk->sk_shutdown |= RCV_SHUTDOWN;
25         sock_set_flag(sk, SOCK_DONE);
26         __skb_pull(skb, dccp_hdr(skb)->dccph_doff * 4);
27         __skb_queue_tail(&sk->sk_receive_queue, skb);
28         skb_set_owner_r(skb, sk);
29         sk->sk_data_ready(sk, 0);
30 }
31
32 static void dccp_rcv_close(struct sock *sk, struct sk_buff *skb)
33 {
34         dccp_send_reset(sk, DCCP_RESET_CODE_CLOSED);
35         dccp_fin(sk, skb);
36         dccp_set_state(sk, DCCP_CLOSED);
37         sk_wake_async(sk, 1, POLL_HUP);
38 }
39
40 static void dccp_rcv_closereq(struct sock *sk, struct sk_buff *skb)
41 {
42         /*
43          *   Step 7: Check for unexpected packet types
44          *      If (S.is_server and P.type == CloseReq)
45          *        Send Sync packet acknowledging P.seqno
46          *        Drop packet and return
47          */
48         if (dccp_sk(sk)->dccps_role != DCCP_ROLE_CLIENT) {
49                 dccp_send_sync(sk, DCCP_SKB_CB(skb)->dccpd_seq, DCCP_PKT_SYNC);
50                 return;
51         }
52
53         if (sk->sk_state != DCCP_CLOSING)
54                 dccp_set_state(sk, DCCP_CLOSING);
55         dccp_send_close(sk, 0);
56 }
57
58 static void dccp_event_ack_recv(struct sock *sk, struct sk_buff *skb)
59 {
60         struct dccp_sock *dp = dccp_sk(sk);
61
62         if (dccp_msk(sk)->dccpms_send_ack_vector)
63                 dccp_ackvec_check_rcv_ackno(dp->dccps_hc_rx_ackvec, sk,
64                                             DCCP_SKB_CB(skb)->dccpd_ack_seq);
65 }
66
67 static int dccp_check_seqno(struct sock *sk, struct sk_buff *skb)
68 {
69         const struct dccp_hdr *dh = dccp_hdr(skb);
70         struct dccp_sock *dp = dccp_sk(sk);
71         u64 lswl, lawl;
72
73         /*
74          *   Step 5: Prepare sequence numbers for Sync
75          *     If P.type == Sync or P.type == SyncAck,
76          *        If S.AWL <= P.ackno <= S.AWH and P.seqno >= S.SWL,
77          *           / * P is valid, so update sequence number variables
78          *               accordingly.  After this update, P will pass the tests
79          *               in Step 6.  A SyncAck is generated if necessary in
80          *               Step 15 * /
81          *           Update S.GSR, S.SWL, S.SWH
82          *        Otherwise,
83          *           Drop packet and return
84          */
85         if (dh->dccph_type == DCCP_PKT_SYNC ||
86             dh->dccph_type == DCCP_PKT_SYNCACK) {
87                 if (between48(DCCP_SKB_CB(skb)->dccpd_ack_seq,
88                               dp->dccps_awl, dp->dccps_awh) &&
89                     dccp_delta_seqno(dp->dccps_swl,
90                                      DCCP_SKB_CB(skb)->dccpd_seq) >= 0)
91                         dccp_update_gsr(sk, DCCP_SKB_CB(skb)->dccpd_seq);
92                 else
93                         return -1;
94         }
95
96         /*
97          *   Step 6: Check sequence numbers
98          *      Let LSWL = S.SWL and LAWL = S.AWL
99          *      If P.type == CloseReq or P.type == Close or P.type == Reset,
100          *        LSWL := S.GSR + 1, LAWL := S.GAR
101          *      If LSWL <= P.seqno <= S.SWH
102          *           and (P.ackno does not exist or LAWL <= P.ackno <= S.AWH),
103          *        Update S.GSR, S.SWL, S.SWH
104          *        If P.type != Sync,
105          *           Update S.GAR
106          *      Otherwise,
107          *        Send Sync packet acknowledging P.seqno
108          *        Drop packet and return
109          */
110         lswl = dp->dccps_swl;
111         lawl = dp->dccps_awl;
112
113         if (dh->dccph_type == DCCP_PKT_CLOSEREQ ||
114             dh->dccph_type == DCCP_PKT_CLOSE ||
115             dh->dccph_type == DCCP_PKT_RESET) {
116                 lswl = dp->dccps_gsr;
117                 dccp_inc_seqno(&lswl);
118                 lawl = dp->dccps_gar;
119         }
120
121         if (between48(DCCP_SKB_CB(skb)->dccpd_seq, lswl, dp->dccps_swh) &&
122             (DCCP_SKB_CB(skb)->dccpd_ack_seq == DCCP_PKT_WITHOUT_ACK_SEQ ||
123              between48(DCCP_SKB_CB(skb)->dccpd_ack_seq,
124                        lawl, dp->dccps_awh))) {
125                 dccp_update_gsr(sk, DCCP_SKB_CB(skb)->dccpd_seq);
126
127                 if (dh->dccph_type != DCCP_PKT_SYNC &&
128                     (DCCP_SKB_CB(skb)->dccpd_ack_seq !=
129                      DCCP_PKT_WITHOUT_ACK_SEQ))
130                         dp->dccps_gar = DCCP_SKB_CB(skb)->dccpd_ack_seq;
131         } else {
132                 DCCP_WARN("DCCP: Step 6 failed for %s packet, "
133                           "(LSWL(%llu) <= P.seqno(%llu) <= S.SWH(%llu)) and "
134                           "(P.ackno %s or LAWL(%llu) <= P.ackno(%llu) <= S.AWH(%llu), "
135                           "sending SYNC...\n",  dccp_packet_name(dh->dccph_type),
136                           (unsigned long long) lswl,
137                           (unsigned long long) DCCP_SKB_CB(skb)->dccpd_seq,
138                           (unsigned long long) dp->dccps_swh,
139                           (DCCP_SKB_CB(skb)->dccpd_ack_seq ==
140                                 DCCP_PKT_WITHOUT_ACK_SEQ) ? "doesn't exist" : "exists",
141                           (unsigned long long) lawl,
142                           (unsigned long long) DCCP_SKB_CB(skb)->dccpd_ack_seq,
143                           (unsigned long long) dp->dccps_awh);
144                 dccp_send_sync(sk, DCCP_SKB_CB(skb)->dccpd_seq, DCCP_PKT_SYNC);
145                 return -1;
146         }
147
148         return 0;
149 }
150
151 static int __dccp_rcv_established(struct sock *sk, struct sk_buff *skb,
152                                   const struct dccp_hdr *dh, const unsigned len)
153 {
154         struct dccp_sock *dp = dccp_sk(sk);
155
156         switch (dccp_hdr(skb)->dccph_type) {
157         case DCCP_PKT_DATAACK:
158         case DCCP_PKT_DATA:
159                 /*
160                  * FIXME: check if sk_receive_queue is full, schedule DATA_DROPPED
161                  * option if it is.
162                  */
163                 __skb_pull(skb, dh->dccph_doff * 4);
164                 __skb_queue_tail(&sk->sk_receive_queue, skb);
165                 skb_set_owner_r(skb, sk);
166                 sk->sk_data_ready(sk, 0);
167                 return 0;
168         case DCCP_PKT_ACK:
169                 goto discard;
170         case DCCP_PKT_RESET:
171                 /*
172                  *  Step 9: Process Reset
173                  *      If P.type == Reset,
174                  *              Tear down connection
175                  *              S.state := TIMEWAIT
176                  *              Set TIMEWAIT timer
177                  *              Drop packet and return
178                 */
179                 dccp_fin(sk, skb);
180                 dccp_time_wait(sk, DCCP_TIME_WAIT, 0);
181                 return 0;
182         case DCCP_PKT_CLOSEREQ:
183                 dccp_rcv_closereq(sk, skb);
184                 goto discard;
185         case DCCP_PKT_CLOSE:
186                 dccp_rcv_close(sk, skb);
187                 return 0;
188         case DCCP_PKT_REQUEST:
189                 /* Step 7
190                  *   or (S.is_server and P.type == Response)
191                  *   or (S.is_client and P.type == Request)
192                  *   or (S.state >= OPEN and P.type == Request
193                  *      and P.seqno >= S.OSR)
194                  *    or (S.state >= OPEN and P.type == Response
195                  *      and P.seqno >= S.OSR)
196                  *    or (S.state == RESPOND and P.type == Data),
197                  *  Send Sync packet acknowledging P.seqno
198                  *  Drop packet and return
199                  */
200                 if (dp->dccps_role != DCCP_ROLE_LISTEN)
201                         goto send_sync;
202                 goto check_seq;
203         case DCCP_PKT_RESPONSE:
204                 if (dp->dccps_role != DCCP_ROLE_CLIENT)
205                         goto send_sync;
206 check_seq:
207                 if (dccp_delta_seqno(dp->dccps_osr,
208                                      DCCP_SKB_CB(skb)->dccpd_seq) >= 0) {
209 send_sync:
210                         dccp_send_sync(sk, DCCP_SKB_CB(skb)->dccpd_seq,
211                                        DCCP_PKT_SYNC);
212                 }
213                 break;
214         case DCCP_PKT_SYNC:
215                 dccp_send_sync(sk, DCCP_SKB_CB(skb)->dccpd_seq,
216                                DCCP_PKT_SYNCACK);
217                 /*
218                  * From RFC 4340, sec. 5.7
219                  *
220                  * As with DCCP-Ack packets, DCCP-Sync and DCCP-SyncAck packets
221                  * MAY have non-zero-length application data areas, whose
222                  * contents receivers MUST ignore.
223                  */
224                 goto discard;
225         }
226
227         DCCP_INC_STATS_BH(DCCP_MIB_INERRS);
228 discard:
229         __kfree_skb(skb);
230         return 0;
231 }
232
233 int dccp_rcv_established(struct sock *sk, struct sk_buff *skb,
234                          const struct dccp_hdr *dh, const unsigned len)
235 {
236         struct dccp_sock *dp = dccp_sk(sk);
237
238         if (dccp_check_seqno(sk, skb))
239                 goto discard;
240
241         if (dccp_parse_options(sk, skb))
242                 goto discard;
243
244         if (DCCP_SKB_CB(skb)->dccpd_ack_seq != DCCP_PKT_WITHOUT_ACK_SEQ)
245                 dccp_event_ack_recv(sk, skb);
246
247         if (dccp_msk(sk)->dccpms_send_ack_vector &&
248             dccp_ackvec_add(dp->dccps_hc_rx_ackvec, sk,
249                             DCCP_SKB_CB(skb)->dccpd_seq,
250                             DCCP_ACKVEC_STATE_RECEIVED))
251                 goto discard;
252
253         ccid_hc_rx_packet_recv(dp->dccps_hc_rx_ccid, sk, skb);
254         ccid_hc_tx_packet_recv(dp->dccps_hc_tx_ccid, sk, skb);
255
256         return __dccp_rcv_established(sk, skb, dh, len);
257 discard:
258         __kfree_skb(skb);
259         return 0;
260 }
261
262 EXPORT_SYMBOL_GPL(dccp_rcv_established);
263
264 static int dccp_rcv_request_sent_state_process(struct sock *sk,
265                                                struct sk_buff *skb,
266                                                const struct dccp_hdr *dh,
267                                                const unsigned len)
268 {
269         /*
270          *  Step 4: Prepare sequence numbers in REQUEST
271          *     If S.state == REQUEST,
272          *        If (P.type == Response or P.type == Reset)
273          *              and S.AWL <= P.ackno <= S.AWH,
274          *           / * Set sequence number variables corresponding to the
275          *              other endpoint, so P will pass the tests in Step 6 * /
276          *           Set S.GSR, S.ISR, S.SWL, S.SWH
277          *           / * Response processing continues in Step 10; Reset
278          *              processing continues in Step 9 * /
279         */
280         if (dh->dccph_type == DCCP_PKT_RESPONSE) {
281                 const struct inet_connection_sock *icsk = inet_csk(sk);
282                 struct dccp_sock *dp = dccp_sk(sk);
283
284                 /* Stop the REQUEST timer */
285                 inet_csk_clear_xmit_timer(sk, ICSK_TIME_RETRANS);
286                 BUG_TRAP(sk->sk_send_head != NULL);
287                 __kfree_skb(sk->sk_send_head);
288                 sk->sk_send_head = NULL;
289
290                 if (!between48(DCCP_SKB_CB(skb)->dccpd_ack_seq,
291                                dp->dccps_awl, dp->dccps_awh)) {
292                         dccp_pr_debug("invalid ackno: S.AWL=%llu, "
293                                       "P.ackno=%llu, S.AWH=%llu \n",
294                                       (unsigned long long)dp->dccps_awl,
295                            (unsigned long long)DCCP_SKB_CB(skb)->dccpd_ack_seq,
296                                       (unsigned long long)dp->dccps_awh);
297                         goto out_invalid_packet;
298                 }
299
300                 if (dccp_parse_options(sk, skb))
301                         goto out_invalid_packet;
302
303                 if (dccp_msk(sk)->dccpms_send_ack_vector &&
304                     dccp_ackvec_add(dp->dccps_hc_rx_ackvec, sk,
305                                     DCCP_SKB_CB(skb)->dccpd_seq,
306                                     DCCP_ACKVEC_STATE_RECEIVED))
307                         goto out_invalid_packet; /* FIXME: change error code */
308
309                 dp->dccps_isr = DCCP_SKB_CB(skb)->dccpd_seq;
310                 dccp_update_gsr(sk, dp->dccps_isr);
311                 /*
312                  * SWL and AWL are initially adjusted so that they are not less than
313                  * the initial Sequence Numbers received and sent, respectively:
314                  *      SWL := max(GSR + 1 - floor(W/4), ISR),
315                  *      AWL := max(GSS - W' + 1, ISS).
316                  * These adjustments MUST be applied only at the beginning of the
317                  * connection.
318                  *
319                  * AWL was adjusted in dccp_v4_connect -acme
320                  */
321                 dccp_set_seqno(&dp->dccps_swl,
322                                max48(dp->dccps_swl, dp->dccps_isr));
323
324                 dccp_sync_mss(sk, icsk->icsk_pmtu_cookie);
325
326                 /*
327                  *    Step 10: Process REQUEST state (second part)
328                  *       If S.state == REQUEST,
329                  *        / * If we get here, P is a valid Response from the
330                  *            server (see Step 4), and we should move to
331                  *            PARTOPEN state. PARTOPEN means send an Ack,
332                  *            don't send Data packets, retransmit Acks
333                  *            periodically, and always include any Init Cookie
334                  *            from the Response * /
335                  *        S.state := PARTOPEN
336                  *        Set PARTOPEN timer
337                  *        Continue with S.state == PARTOPEN
338                  *        / * Step 12 will send the Ack completing the
339                  *            three-way handshake * /
340                  */
341                 dccp_set_state(sk, DCCP_PARTOPEN);
342
343                 /* Make sure socket is routed, for correct metrics. */
344                 icsk->icsk_af_ops->rebuild_header(sk);
345
346                 if (!sock_flag(sk, SOCK_DEAD)) {
347                         sk->sk_state_change(sk);
348                         sk_wake_async(sk, 0, POLL_OUT);
349                 }
350
351                 if (sk->sk_write_pending || icsk->icsk_ack.pingpong ||
352                     icsk->icsk_accept_queue.rskq_defer_accept) {
353                         /* Save one ACK. Data will be ready after
354                          * several ticks, if write_pending is set.
355                          *
356                          * It may be deleted, but with this feature tcpdumps
357                          * look so _wonderfully_ clever, that I was not able
358                          * to stand against the temptation 8)     --ANK
359                          */
360                         /*
361                          * OK, in DCCP we can as well do a similar trick, its
362                          * even in the draft, but there is no need for us to
363                          * schedule an ack here, as dccp_sendmsg does this for
364                          * us, also stated in the draft. -acme
365                          */
366                         __kfree_skb(skb);
367                         return 0;
368                 }
369                 dccp_send_ack(sk);
370                 return -1;
371         }
372
373 out_invalid_packet:
374         /* dccp_v4_do_rcv will send a reset */
375         DCCP_SKB_CB(skb)->dccpd_reset_code = DCCP_RESET_CODE_PACKET_ERROR;
376         return 1;
377 }
378
379 static int dccp_rcv_respond_partopen_state_process(struct sock *sk,
380                                                    struct sk_buff *skb,
381                                                    const struct dccp_hdr *dh,
382                                                    const unsigned len)
383 {
384         int queued = 0;
385
386         switch (dh->dccph_type) {
387         case DCCP_PKT_RESET:
388                 inet_csk_clear_xmit_timer(sk, ICSK_TIME_DACK);
389                 break;
390         case DCCP_PKT_DATA:
391                 if (sk->sk_state == DCCP_RESPOND)
392                         break;
393         case DCCP_PKT_DATAACK:
394         case DCCP_PKT_ACK:
395                 /*
396                  * FIXME: we should be reseting the PARTOPEN (DELACK) timer
397                  * here but only if we haven't used the DELACK timer for
398                  * something else, like sending a delayed ack for a TIMESTAMP
399                  * echo, etc, for now were not clearing it, sending an extra
400                  * ACK when there is nothing else to do in DELACK is not a big
401                  * deal after all.
402                  */
403
404                 /* Stop the PARTOPEN timer */
405                 if (sk->sk_state == DCCP_PARTOPEN)
406                         inet_csk_clear_xmit_timer(sk, ICSK_TIME_DACK);
407
408                 dccp_sk(sk)->dccps_osr = DCCP_SKB_CB(skb)->dccpd_seq;
409                 dccp_set_state(sk, DCCP_OPEN);
410
411                 if (dh->dccph_type == DCCP_PKT_DATAACK ||
412                     dh->dccph_type == DCCP_PKT_DATA) {
413                         __dccp_rcv_established(sk, skb, dh, len);
414                         queued = 1; /* packet was queued
415                                        (by __dccp_rcv_established) */
416                 }
417                 break;
418         }
419
420         return queued;
421 }
422
423 int dccp_rcv_state_process(struct sock *sk, struct sk_buff *skb,
424                            struct dccp_hdr *dh, unsigned len)
425 {
426         struct dccp_sock *dp = dccp_sk(sk);
427         struct dccp_skb_cb *dcb = DCCP_SKB_CB(skb);
428         const int old_state = sk->sk_state;
429         int queued = 0;
430
431         /*
432          *  Step 3: Process LISTEN state
433          *
434          *     If S.state == LISTEN,
435          *       If P.type == Request or P contains a valid Init Cookie option,
436          *            (* Must scan the packet's options to check for Init
437          *               Cookies.  Only Init Cookies are processed here,
438          *               however; other options are processed in Step 8.  This
439          *               scan need only be performed if the endpoint uses Init
440          *               Cookies *)
441          *            (* Generate a new socket and switch to that socket *)
442          *            Set S := new socket for this port pair
443          *            S.state = RESPOND
444          *            Choose S.ISS (initial seqno) or set from Init Cookies
445          *            Initialize S.GAR := S.ISS
446          *            Set S.ISR, S.GSR, S.SWL, S.SWH from packet or Init
447          *            Cookies Continue with S.state == RESPOND
448          *            (* A Response packet will be generated in Step 11 *)
449          *       Otherwise,
450          *            Generate Reset(No Connection) unless P.type == Reset
451          *            Drop packet and return
452          */
453         if (sk->sk_state == DCCP_LISTEN) {
454                 if (dh->dccph_type == DCCP_PKT_REQUEST) {
455                         if (inet_csk(sk)->icsk_af_ops->conn_request(sk,
456                                                                     skb) < 0)
457                                 return 1;
458
459                         /* FIXME: do congestion control initialization */
460                         goto discard;
461                 }
462                 if (dh->dccph_type == DCCP_PKT_RESET)
463                         goto discard;
464
465                 /* Caller (dccp_v4_do_rcv) will send Reset */
466                 dcb->dccpd_reset_code = DCCP_RESET_CODE_NO_CONNECTION;
467                 return 1;
468         }
469
470         if (sk->sk_state != DCCP_REQUESTING) {
471                 if (dccp_check_seqno(sk, skb))
472                         goto discard;
473
474                 /*
475                  * Step 8: Process options and mark acknowledgeable
476                  */
477                 if (dccp_parse_options(sk, skb))
478                         goto discard;
479
480                 if (dcb->dccpd_ack_seq != DCCP_PKT_WITHOUT_ACK_SEQ)
481                         dccp_event_ack_recv(sk, skb);
482
483                 if (dccp_msk(sk)->dccpms_send_ack_vector &&
484                     dccp_ackvec_add(dp->dccps_hc_rx_ackvec, sk,
485                                     DCCP_SKB_CB(skb)->dccpd_seq,
486                                     DCCP_ACKVEC_STATE_RECEIVED))
487                         goto discard;
488
489                 ccid_hc_rx_packet_recv(dp->dccps_hc_rx_ccid, sk, skb);
490                 ccid_hc_tx_packet_recv(dp->dccps_hc_tx_ccid, sk, skb);
491         }
492
493         /*
494          *  Step 9: Process Reset
495          *      If P.type == Reset,
496          *              Tear down connection
497          *              S.state := TIMEWAIT
498          *              Set TIMEWAIT timer
499          *              Drop packet and return
500         */
501         if (dh->dccph_type == DCCP_PKT_RESET) {
502                 /*
503                  * Queue the equivalent of TCP fin so that dccp_recvmsg
504                  * exits the loop
505                  */
506                 dccp_fin(sk, skb);
507                 dccp_time_wait(sk, DCCP_TIME_WAIT, 0);
508                 return 0;
509                 /*
510                  *   Step 7: Check for unexpected packet types
511                  *      If (S.is_server and P.type == CloseReq)
512                  *          or (S.is_server and P.type == Response)
513                  *          or (S.is_client and P.type == Request)
514                  *          or (S.state == RESPOND and P.type == Data),
515                  *        Send Sync packet acknowledging P.seqno
516                  *        Drop packet and return
517                  */
518         } else if ((dp->dccps_role != DCCP_ROLE_CLIENT &&
519                     (dh->dccph_type == DCCP_PKT_RESPONSE ||
520                      dh->dccph_type == DCCP_PKT_CLOSEREQ)) ||
521                     (dp->dccps_role == DCCP_ROLE_CLIENT &&
522                      dh->dccph_type == DCCP_PKT_REQUEST) ||
523                     (sk->sk_state == DCCP_RESPOND &&
524                      dh->dccph_type == DCCP_PKT_DATA)) {
525                 dccp_send_sync(sk, dcb->dccpd_seq, DCCP_PKT_SYNC);
526                 goto discard;
527         } else if (dh->dccph_type == DCCP_PKT_CLOSEREQ) {
528                 dccp_rcv_closereq(sk, skb);
529                 goto discard;
530         } else if (dh->dccph_type == DCCP_PKT_CLOSE) {
531                 dccp_rcv_close(sk, skb);
532                 return 0;
533         }
534
535         if (unlikely(dh->dccph_type == DCCP_PKT_SYNC)) {
536                 dccp_send_sync(sk, dcb->dccpd_seq, DCCP_PKT_SYNCACK);
537                 goto discard;
538         }
539
540         switch (sk->sk_state) {
541         case DCCP_CLOSED:
542                 dcb->dccpd_reset_code = DCCP_RESET_CODE_NO_CONNECTION;
543                 return 1;
544
545         case DCCP_REQUESTING:
546                 /* FIXME: do congestion control initialization */
547
548                 queued = dccp_rcv_request_sent_state_process(sk, skb, dh, len);
549                 if (queued >= 0)
550                         return queued;
551
552                 __kfree_skb(skb);
553                 return 0;
554
555         case DCCP_RESPOND:
556         case DCCP_PARTOPEN:
557                 queued = dccp_rcv_respond_partopen_state_process(sk, skb,
558                                                                  dh, len);
559                 break;
560         }
561
562         if (dh->dccph_type == DCCP_PKT_ACK ||
563             dh->dccph_type == DCCP_PKT_DATAACK) {
564                 switch (old_state) {
565                 case DCCP_PARTOPEN:
566                         sk->sk_state_change(sk);
567                         sk_wake_async(sk, 0, POLL_OUT);
568                         break;
569                 }
570         }
571
572         if (!queued) {
573 discard:
574                 __kfree_skb(skb);
575         }
576         return 0;
577 }
578
579 EXPORT_SYMBOL_GPL(dccp_rcv_state_process);
580
581 /**
582  * dccp_sample_rtt  -  Sample RTT from packet exchange
583  *
584  * @sk:     connected dccp_sock
585  * @t_recv: receive timestamp of packet with timestamp echo
586  * @t_hist: packet history timestamp or NULL
587  */
588 u32 dccp_sample_rtt(struct sock *sk, struct timeval *t_recv,
589                                      struct timeval *t_hist)
590 {
591         struct dccp_sock *dp = dccp_sk(sk);
592         struct dccp_options_received *or = &dp->dccps_options_received;
593         suseconds_t delta;
594
595         if (t_hist == NULL) {
596                 if (!or->dccpor_timestamp_echo) {
597                         DCCP_WARN("packet without timestamp echo\n");
598                         return DCCP_SANE_RTT_MAX;
599                 }
600                 timeval_sub_usecs(t_recv, or->dccpor_timestamp_echo * 10);
601                 delta = timeval_usecs(t_recv);
602         } else
603                 delta = timeval_delta(t_recv, t_hist);
604
605         delta -= or->dccpor_elapsed_time * 10;          /* either set or 0 */
606
607         if (unlikely(delta <= 0)) {
608                 DCCP_WARN("unusable RTT sample %ld, using min\n", (long)delta);
609                 return DCCP_SANE_RTT_MIN;
610         }
611         if (unlikely(delta - (suseconds_t)DCCP_SANE_RTT_MAX > 0)) {
612                 DCCP_WARN("RTT sample %ld too large, using max\n", (long)delta);
613                 return DCCP_SANE_RTT_MAX;
614         }
615
616         return delta;
617 }
618
619 EXPORT_SYMBOL_GPL(dccp_sample_rtt);