Merge master.kernel.org:/pub/scm/linux/kernel/git/davej/cpufreq
[linux-2.6] / 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, seqno = DCCP_SKB_CB(skb)->dccpd_seq,
72                         ackno = DCCP_SKB_CB(skb)->dccpd_ack_seq;
73
74         /*
75          *   Step 5: Prepare sequence numbers for Sync
76          *     If P.type == Sync or P.type == SyncAck,
77          *        If S.AWL <= P.ackno <= S.AWH and P.seqno >= S.SWL,
78          *           / * P is valid, so update sequence number variables
79          *               accordingly.  After this update, P will pass the tests
80          *               in Step 6.  A SyncAck is generated if necessary in
81          *               Step 15 * /
82          *           Update S.GSR, S.SWL, S.SWH
83          *        Otherwise,
84          *           Drop packet and return
85          */
86         if (dh->dccph_type == DCCP_PKT_SYNC ||
87             dh->dccph_type == DCCP_PKT_SYNCACK) {
88                 if (between48(ackno, dp->dccps_awl, dp->dccps_awh) &&
89                     dccp_delta_seqno(dp->dccps_swl, seqno) >= 0)
90                         dccp_update_gsr(sk, seqno);
91                 else
92                         return -1;
93         }
94
95         /*
96          *   Step 6: Check sequence numbers
97          *      Let LSWL = S.SWL and LAWL = S.AWL
98          *      If P.type == CloseReq or P.type == Close or P.type == Reset,
99          *        LSWL := S.GSR + 1, LAWL := S.GAR
100          *      If LSWL <= P.seqno <= S.SWH
101          *           and (P.ackno does not exist or LAWL <= P.ackno <= S.AWH),
102          *        Update S.GSR, S.SWL, S.SWH
103          *        If P.type != Sync,
104          *           Update S.GAR
105          */
106         lswl = dp->dccps_swl;
107         lawl = dp->dccps_awl;
108
109         if (dh->dccph_type == DCCP_PKT_CLOSEREQ ||
110             dh->dccph_type == DCCP_PKT_CLOSE ||
111             dh->dccph_type == DCCP_PKT_RESET) {
112                 lswl = ADD48(dp->dccps_gsr, 1);
113                 lawl = dp->dccps_gar;
114         }
115
116         if (between48(seqno, lswl, dp->dccps_swh) &&
117             (ackno == DCCP_PKT_WITHOUT_ACK_SEQ ||
118              between48(ackno, lawl, dp->dccps_awh))) {
119                 dccp_update_gsr(sk, seqno);
120
121                 if (dh->dccph_type != DCCP_PKT_SYNC &&
122                     (ackno != DCCP_PKT_WITHOUT_ACK_SEQ))
123                         dp->dccps_gar = ackno;
124         } else {
125                 unsigned long now = jiffies;
126                 /*
127                  *   Step 6: Check sequence numbers
128                  *      Otherwise,
129                  *         If P.type == Reset,
130                  *            Send Sync packet acknowledging S.GSR
131                  *         Otherwise,
132                  *            Send Sync packet acknowledging P.seqno
133                  *      Drop packet and return
134                  *
135                  *   These Syncs are rate-limited as per RFC 4340, 7.5.4:
136                  *   at most 1 / (dccp_sync_rate_limit * HZ) Syncs per second.
137                  */
138                 if (time_before(now, (dp->dccps_rate_last +
139                                       sysctl_dccp_sync_ratelimit)))
140                         return 0;
141
142                 DCCP_WARN("DCCP: Step 6 failed for %s packet, "
143                           "(LSWL(%llu) <= P.seqno(%llu) <= S.SWH(%llu)) and "
144                           "(P.ackno %s or LAWL(%llu) <= P.ackno(%llu) <= S.AWH(%llu), "
145                           "sending SYNC...\n",  dccp_packet_name(dh->dccph_type),
146                           (unsigned long long) lswl, (unsigned long long) seqno,
147                           (unsigned long long) dp->dccps_swh,
148                           (ackno == DCCP_PKT_WITHOUT_ACK_SEQ) ? "doesn't exist"
149                                                               : "exists",
150                           (unsigned long long) lawl, (unsigned long long) ackno,
151                           (unsigned long long) dp->dccps_awh);
152
153                 dp->dccps_rate_last = now;
154
155                 if (dh->dccph_type == DCCP_PKT_RESET)
156                         seqno = dp->dccps_gsr;
157                 dccp_send_sync(sk, seqno, DCCP_PKT_SYNC);
158                 return -1;
159         }
160
161         return 0;
162 }
163
164 static int __dccp_rcv_established(struct sock *sk, struct sk_buff *skb,
165                                   const struct dccp_hdr *dh, const unsigned len)
166 {
167         struct dccp_sock *dp = dccp_sk(sk);
168
169         switch (dccp_hdr(skb)->dccph_type) {
170         case DCCP_PKT_DATAACK:
171         case DCCP_PKT_DATA:
172                 /*
173                  * FIXME: check if sk_receive_queue is full, schedule DATA_DROPPED
174                  * option if it is.
175                  */
176                 __skb_pull(skb, dh->dccph_doff * 4);
177                 __skb_queue_tail(&sk->sk_receive_queue, skb);
178                 skb_set_owner_r(skb, sk);
179                 sk->sk_data_ready(sk, 0);
180                 return 0;
181         case DCCP_PKT_ACK:
182                 goto discard;
183         case DCCP_PKT_RESET:
184                 /*
185                  *  Step 9: Process Reset
186                  *      If P.type == Reset,
187                  *              Tear down connection
188                  *              S.state := TIMEWAIT
189                  *              Set TIMEWAIT timer
190                  *              Drop packet and return
191                 */
192                 dccp_fin(sk, skb);
193                 dccp_time_wait(sk, DCCP_TIME_WAIT, 0);
194                 return 0;
195         case DCCP_PKT_CLOSEREQ:
196                 dccp_rcv_closereq(sk, skb);
197                 goto discard;
198         case DCCP_PKT_CLOSE:
199                 dccp_rcv_close(sk, skb);
200                 return 0;
201         case DCCP_PKT_REQUEST:
202                 /* Step 7
203                  *   or (S.is_server and P.type == Response)
204                  *   or (S.is_client and P.type == Request)
205                  *   or (S.state >= OPEN and P.type == Request
206                  *      and P.seqno >= S.OSR)
207                  *    or (S.state >= OPEN and P.type == Response
208                  *      and P.seqno >= S.OSR)
209                  *    or (S.state == RESPOND and P.type == Data),
210                  *  Send Sync packet acknowledging P.seqno
211                  *  Drop packet and return
212                  */
213                 if (dp->dccps_role != DCCP_ROLE_LISTEN)
214                         goto send_sync;
215                 goto check_seq;
216         case DCCP_PKT_RESPONSE:
217                 if (dp->dccps_role != DCCP_ROLE_CLIENT)
218                         goto send_sync;
219 check_seq:
220                 if (dccp_delta_seqno(dp->dccps_osr,
221                                      DCCP_SKB_CB(skb)->dccpd_seq) >= 0) {
222 send_sync:
223                         dccp_send_sync(sk, DCCP_SKB_CB(skb)->dccpd_seq,
224                                        DCCP_PKT_SYNC);
225                 }
226                 break;
227         case DCCP_PKT_SYNC:
228                 dccp_send_sync(sk, DCCP_SKB_CB(skb)->dccpd_seq,
229                                DCCP_PKT_SYNCACK);
230                 /*
231                  * From RFC 4340, sec. 5.7
232                  *
233                  * As with DCCP-Ack packets, DCCP-Sync and DCCP-SyncAck packets
234                  * MAY have non-zero-length application data areas, whose
235                  * contents receivers MUST ignore.
236                  */
237                 goto discard;
238         }
239
240         DCCP_INC_STATS_BH(DCCP_MIB_INERRS);
241 discard:
242         __kfree_skb(skb);
243         return 0;
244 }
245
246 int dccp_rcv_established(struct sock *sk, struct sk_buff *skb,
247                          const struct dccp_hdr *dh, const unsigned len)
248 {
249         struct dccp_sock *dp = dccp_sk(sk);
250
251         if (dccp_check_seqno(sk, skb))
252                 goto discard;
253
254         if (dccp_parse_options(sk, skb))
255                 goto discard;
256
257         if (DCCP_SKB_CB(skb)->dccpd_ack_seq != DCCP_PKT_WITHOUT_ACK_SEQ)
258                 dccp_event_ack_recv(sk, skb);
259
260         if (dccp_msk(sk)->dccpms_send_ack_vector &&
261             dccp_ackvec_add(dp->dccps_hc_rx_ackvec, sk,
262                             DCCP_SKB_CB(skb)->dccpd_seq,
263                             DCCP_ACKVEC_STATE_RECEIVED))
264                 goto discard;
265
266         ccid_hc_rx_packet_recv(dp->dccps_hc_rx_ccid, sk, skb);
267         ccid_hc_tx_packet_recv(dp->dccps_hc_tx_ccid, sk, skb);
268
269         return __dccp_rcv_established(sk, skb, dh, len);
270 discard:
271         __kfree_skb(skb);
272         return 0;
273 }
274
275 EXPORT_SYMBOL_GPL(dccp_rcv_established);
276
277 static int dccp_rcv_request_sent_state_process(struct sock *sk,
278                                                struct sk_buff *skb,
279                                                const struct dccp_hdr *dh,
280                                                const unsigned len)
281 {
282         /*
283          *  Step 4: Prepare sequence numbers in REQUEST
284          *     If S.state == REQUEST,
285          *        If (P.type == Response or P.type == Reset)
286          *              and S.AWL <= P.ackno <= S.AWH,
287          *           / * Set sequence number variables corresponding to the
288          *              other endpoint, so P will pass the tests in Step 6 * /
289          *           Set S.GSR, S.ISR, S.SWL, S.SWH
290          *           / * Response processing continues in Step 10; Reset
291          *              processing continues in Step 9 * /
292         */
293         if (dh->dccph_type == DCCP_PKT_RESPONSE) {
294                 const struct inet_connection_sock *icsk = inet_csk(sk);
295                 struct dccp_sock *dp = dccp_sk(sk);
296                 long tstamp = dccp_timestamp();
297
298                 /* Stop the REQUEST timer */
299                 inet_csk_clear_xmit_timer(sk, ICSK_TIME_RETRANS);
300                 BUG_TRAP(sk->sk_send_head != NULL);
301                 __kfree_skb(sk->sk_send_head);
302                 sk->sk_send_head = NULL;
303
304                 if (!between48(DCCP_SKB_CB(skb)->dccpd_ack_seq,
305                                dp->dccps_awl, dp->dccps_awh)) {
306                         dccp_pr_debug("invalid ackno: S.AWL=%llu, "
307                                       "P.ackno=%llu, S.AWH=%llu \n",
308                                       (unsigned long long)dp->dccps_awl,
309                            (unsigned long long)DCCP_SKB_CB(skb)->dccpd_ack_seq,
310                                       (unsigned long long)dp->dccps_awh);
311                         goto out_invalid_packet;
312                 }
313
314                 if (dccp_parse_options(sk, skb))
315                         goto out_invalid_packet;
316
317                 /* Obtain usec RTT sample from SYN exchange (used by CCID 3) */
318                 if (likely(dp->dccps_options_received.dccpor_timestamp_echo))
319                         dp->dccps_syn_rtt = dccp_sample_rtt(sk, 10 * (tstamp -
320                             dp->dccps_options_received.dccpor_timestamp_echo));
321
322                 if (dccp_msk(sk)->dccpms_send_ack_vector &&
323                     dccp_ackvec_add(dp->dccps_hc_rx_ackvec, sk,
324                                     DCCP_SKB_CB(skb)->dccpd_seq,
325                                     DCCP_ACKVEC_STATE_RECEIVED))
326                         goto out_invalid_packet; /* FIXME: change error code */
327
328                 dp->dccps_isr = DCCP_SKB_CB(skb)->dccpd_seq;
329                 dccp_update_gsr(sk, dp->dccps_isr);
330                 /*
331                  * SWL and AWL are initially adjusted so that they are not less than
332                  * the initial Sequence Numbers received and sent, respectively:
333                  *      SWL := max(GSR + 1 - floor(W/4), ISR),
334                  *      AWL := max(GSS - W' + 1, ISS).
335                  * These adjustments MUST be applied only at the beginning of the
336                  * connection.
337                  *
338                  * AWL was adjusted in dccp_v4_connect -acme
339                  */
340                 dccp_set_seqno(&dp->dccps_swl,
341                                max48(dp->dccps_swl, dp->dccps_isr));
342
343                 dccp_sync_mss(sk, icsk->icsk_pmtu_cookie);
344
345                 /*
346                  *    Step 10: Process REQUEST state (second part)
347                  *       If S.state == REQUEST,
348                  *        / * If we get here, P is a valid Response from the
349                  *            server (see Step 4), and we should move to
350                  *            PARTOPEN state. PARTOPEN means send an Ack,
351                  *            don't send Data packets, retransmit Acks
352                  *            periodically, and always include any Init Cookie
353                  *            from the Response * /
354                  *        S.state := PARTOPEN
355                  *        Set PARTOPEN timer
356                  *        Continue with S.state == PARTOPEN
357                  *        / * Step 12 will send the Ack completing the
358                  *            three-way handshake * /
359                  */
360                 dccp_set_state(sk, DCCP_PARTOPEN);
361
362                 /* Make sure socket is routed, for correct metrics. */
363                 icsk->icsk_af_ops->rebuild_header(sk);
364
365                 if (!sock_flag(sk, SOCK_DEAD)) {
366                         sk->sk_state_change(sk);
367                         sk_wake_async(sk, 0, POLL_OUT);
368                 }
369
370                 if (sk->sk_write_pending || icsk->icsk_ack.pingpong ||
371                     icsk->icsk_accept_queue.rskq_defer_accept) {
372                         /* Save one ACK. Data will be ready after
373                          * several ticks, if write_pending is set.
374                          *
375                          * It may be deleted, but with this feature tcpdumps
376                          * look so _wonderfully_ clever, that I was not able
377                          * to stand against the temptation 8)     --ANK
378                          */
379                         /*
380                          * OK, in DCCP we can as well do a similar trick, its
381                          * even in the draft, but there is no need for us to
382                          * schedule an ack here, as dccp_sendmsg does this for
383                          * us, also stated in the draft. -acme
384                          */
385                         __kfree_skb(skb);
386                         return 0;
387                 }
388                 dccp_send_ack(sk);
389                 return -1;
390         }
391
392 out_invalid_packet:
393         /* dccp_v4_do_rcv will send a reset */
394         DCCP_SKB_CB(skb)->dccpd_reset_code = DCCP_RESET_CODE_PACKET_ERROR;
395         return 1;
396 }
397
398 static int dccp_rcv_respond_partopen_state_process(struct sock *sk,
399                                                    struct sk_buff *skb,
400                                                    const struct dccp_hdr *dh,
401                                                    const unsigned len)
402 {
403         int queued = 0;
404
405         switch (dh->dccph_type) {
406         case DCCP_PKT_RESET:
407                 inet_csk_clear_xmit_timer(sk, ICSK_TIME_DACK);
408                 break;
409         case DCCP_PKT_DATA:
410                 if (sk->sk_state == DCCP_RESPOND)
411                         break;
412         case DCCP_PKT_DATAACK:
413         case DCCP_PKT_ACK:
414                 /*
415                  * FIXME: we should be reseting the PARTOPEN (DELACK) timer
416                  * here but only if we haven't used the DELACK timer for
417                  * something else, like sending a delayed ack for a TIMESTAMP
418                  * echo, etc, for now were not clearing it, sending an extra
419                  * ACK when there is nothing else to do in DELACK is not a big
420                  * deal after all.
421                  */
422
423                 /* Stop the PARTOPEN timer */
424                 if (sk->sk_state == DCCP_PARTOPEN)
425                         inet_csk_clear_xmit_timer(sk, ICSK_TIME_DACK);
426
427                 dccp_sk(sk)->dccps_osr = DCCP_SKB_CB(skb)->dccpd_seq;
428                 dccp_set_state(sk, DCCP_OPEN);
429
430                 if (dh->dccph_type == DCCP_PKT_DATAACK ||
431                     dh->dccph_type == DCCP_PKT_DATA) {
432                         __dccp_rcv_established(sk, skb, dh, len);
433                         queued = 1; /* packet was queued
434                                        (by __dccp_rcv_established) */
435                 }
436                 break;
437         }
438
439         return queued;
440 }
441
442 int dccp_rcv_state_process(struct sock *sk, struct sk_buff *skb,
443                            struct dccp_hdr *dh, unsigned len)
444 {
445         struct dccp_sock *dp = dccp_sk(sk);
446         struct dccp_skb_cb *dcb = DCCP_SKB_CB(skb);
447         const int old_state = sk->sk_state;
448         int queued = 0;
449
450         /*
451          *  Step 3: Process LISTEN state
452          *
453          *     If S.state == LISTEN,
454          *       If P.type == Request or P contains a valid Init Cookie option,
455          *            (* Must scan the packet's options to check for Init
456          *               Cookies.  Only Init Cookies are processed here,
457          *               however; other options are processed in Step 8.  This
458          *               scan need only be performed if the endpoint uses Init
459          *               Cookies *)
460          *            (* Generate a new socket and switch to that socket *)
461          *            Set S := new socket for this port pair
462          *            S.state = RESPOND
463          *            Choose S.ISS (initial seqno) or set from Init Cookies
464          *            Initialize S.GAR := S.ISS
465          *            Set S.ISR, S.GSR, S.SWL, S.SWH from packet or Init
466          *            Cookies Continue with S.state == RESPOND
467          *            (* A Response packet will be generated in Step 11 *)
468          *       Otherwise,
469          *            Generate Reset(No Connection) unless P.type == Reset
470          *            Drop packet and return
471          */
472         if (sk->sk_state == DCCP_LISTEN) {
473                 if (dh->dccph_type == DCCP_PKT_REQUEST) {
474                         if (inet_csk(sk)->icsk_af_ops->conn_request(sk,
475                                                                     skb) < 0)
476                                 return 1;
477
478                         /* FIXME: do congestion control initialization */
479                         goto discard;
480                 }
481                 if (dh->dccph_type == DCCP_PKT_RESET)
482                         goto discard;
483
484                 /* Caller (dccp_v4_do_rcv) will send Reset */
485                 dcb->dccpd_reset_code = DCCP_RESET_CODE_NO_CONNECTION;
486                 return 1;
487         }
488
489         if (sk->sk_state != DCCP_REQUESTING) {
490                 if (dccp_check_seqno(sk, skb))
491                         goto discard;
492
493                 /*
494                  * Step 8: Process options and mark acknowledgeable
495                  */
496                 if (dccp_parse_options(sk, skb))
497                         goto discard;
498
499                 if (dcb->dccpd_ack_seq != DCCP_PKT_WITHOUT_ACK_SEQ)
500                         dccp_event_ack_recv(sk, skb);
501
502                 if (dccp_msk(sk)->dccpms_send_ack_vector &&
503                     dccp_ackvec_add(dp->dccps_hc_rx_ackvec, sk,
504                                     DCCP_SKB_CB(skb)->dccpd_seq,
505                                     DCCP_ACKVEC_STATE_RECEIVED))
506                         goto discard;
507
508                 ccid_hc_rx_packet_recv(dp->dccps_hc_rx_ccid, sk, skb);
509                 ccid_hc_tx_packet_recv(dp->dccps_hc_tx_ccid, sk, skb);
510         }
511
512         /*
513          *  Step 9: Process Reset
514          *      If P.type == Reset,
515          *              Tear down connection
516          *              S.state := TIMEWAIT
517          *              Set TIMEWAIT timer
518          *              Drop packet and return
519         */
520         if (dh->dccph_type == DCCP_PKT_RESET) {
521                 /*
522                  * Queue the equivalent of TCP fin so that dccp_recvmsg
523                  * exits the loop
524                  */
525                 dccp_fin(sk, skb);
526                 dccp_time_wait(sk, DCCP_TIME_WAIT, 0);
527                 return 0;
528                 /*
529                  *   Step 7: Check for unexpected packet types
530                  *      If (S.is_server and P.type == CloseReq)
531                  *          or (S.is_server and P.type == Response)
532                  *          or (S.is_client and P.type == Request)
533                  *          or (S.state == RESPOND and P.type == Data),
534                  *        Send Sync packet acknowledging P.seqno
535                  *        Drop packet and return
536                  */
537         } else if ((dp->dccps_role != DCCP_ROLE_CLIENT &&
538                     (dh->dccph_type == DCCP_PKT_RESPONSE ||
539                      dh->dccph_type == DCCP_PKT_CLOSEREQ)) ||
540                     (dp->dccps_role == DCCP_ROLE_CLIENT &&
541                      dh->dccph_type == DCCP_PKT_REQUEST) ||
542                     (sk->sk_state == DCCP_RESPOND &&
543                      dh->dccph_type == DCCP_PKT_DATA)) {
544                 dccp_send_sync(sk, dcb->dccpd_seq, DCCP_PKT_SYNC);
545                 goto discard;
546         } else if (dh->dccph_type == DCCP_PKT_CLOSEREQ) {
547                 dccp_rcv_closereq(sk, skb);
548                 goto discard;
549         } else if (dh->dccph_type == DCCP_PKT_CLOSE) {
550                 dccp_rcv_close(sk, skb);
551                 return 0;
552         }
553
554         switch (sk->sk_state) {
555         case DCCP_CLOSED:
556                 dcb->dccpd_reset_code = DCCP_RESET_CODE_NO_CONNECTION;
557                 return 1;
558
559         case DCCP_REQUESTING:
560                 /* FIXME: do congestion control initialization */
561
562                 queued = dccp_rcv_request_sent_state_process(sk, skb, dh, len);
563                 if (queued >= 0)
564                         return queued;
565
566                 __kfree_skb(skb);
567                 return 0;
568
569         case DCCP_RESPOND:
570         case DCCP_PARTOPEN:
571                 queued = dccp_rcv_respond_partopen_state_process(sk, skb,
572                                                                  dh, len);
573                 break;
574         }
575
576         if (dh->dccph_type == DCCP_PKT_ACK ||
577             dh->dccph_type == DCCP_PKT_DATAACK) {
578                 switch (old_state) {
579                 case DCCP_PARTOPEN:
580                         sk->sk_state_change(sk);
581                         sk_wake_async(sk, 0, POLL_OUT);
582                         break;
583                 }
584         } else if (unlikely(dh->dccph_type == DCCP_PKT_SYNC)) {
585                 dccp_send_sync(sk, dcb->dccpd_seq, DCCP_PKT_SYNCACK);
586                 goto discard;
587         }
588
589         if (!queued) {
590 discard:
591                 __kfree_skb(skb);
592         }
593         return 0;
594 }
595
596 EXPORT_SYMBOL_GPL(dccp_rcv_state_process);
597
598 /**
599  *  dccp_sample_rtt  -  Validate and finalise computation of RTT sample
600  *  @delta:     number of microseconds between packet and acknowledgment
601  *  The routine is kept generic to work in different contexts. It should be
602  *  called immediately when the ACK used for the RTT sample arrives.
603  */
604 u32 dccp_sample_rtt(struct sock *sk, long delta)
605 {
606         /* dccpor_elapsed_time is either zeroed out or set and > 0 */
607         delta -= dccp_sk(sk)->dccps_options_received.dccpor_elapsed_time * 10;
608
609         if (unlikely(delta <= 0)) {
610                 DCCP_WARN("unusable RTT sample %ld, using min\n", delta);
611                 return DCCP_SANE_RTT_MIN;
612         }
613         if (unlikely(delta > DCCP_SANE_RTT_MAX)) {
614                 DCCP_WARN("RTT sample %ld too large, using max\n", delta);
615                 return DCCP_SANE_RTT_MAX;
616         }
617
618         return delta;
619 }
620
621 EXPORT_SYMBOL_GPL(dccp_sample_rtt);