Merge git://git.infradead.org/battery-2.6
[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 /* 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;
24
25 static void dccp_fin(struct sock *sk, struct sk_buff *skb)
26 {
27         sk->sk_shutdown |= RCV_SHUTDOWN;
28         sock_set_flag(sk, SOCK_DONE);
29         __skb_pull(skb, dccp_hdr(skb)->dccph_doff * 4);
30         __skb_queue_tail(&sk->sk_receive_queue, skb);
31         skb_set_owner_r(skb, sk);
32         sk->sk_data_ready(sk, 0);
33 }
34
35 static void dccp_rcv_close(struct sock *sk, struct sk_buff *skb)
36 {
37         dccp_send_reset(sk, DCCP_RESET_CODE_CLOSED);
38         dccp_fin(sk, skb);
39         dccp_set_state(sk, DCCP_CLOSED);
40         sk_wake_async(sk, 1, POLL_HUP);
41 }
42
43 static void dccp_rcv_closereq(struct sock *sk, struct sk_buff *skb)
44 {
45         /*
46          *   Step 7: Check for unexpected packet types
47          *      If (S.is_server and P.type == CloseReq)
48          *        Send Sync packet acknowledging P.seqno
49          *        Drop packet and return
50          */
51         if (dccp_sk(sk)->dccps_role != DCCP_ROLE_CLIENT) {
52                 dccp_send_sync(sk, DCCP_SKB_CB(skb)->dccpd_seq, DCCP_PKT_SYNC);
53                 return;
54         }
55
56         if (sk->sk_state != DCCP_CLOSING)
57                 dccp_set_state(sk, DCCP_CLOSING);
58         dccp_send_close(sk, 0);
59 }
60
61 static void dccp_event_ack_recv(struct sock *sk, struct sk_buff *skb)
62 {
63         struct dccp_sock *dp = dccp_sk(sk);
64
65         if (dccp_msk(sk)->dccpms_send_ack_vector)
66                 dccp_ackvec_check_rcv_ackno(dp->dccps_hc_rx_ackvec, sk,
67                                             DCCP_SKB_CB(skb)->dccpd_ack_seq);
68 }
69
70 static int dccp_check_seqno(struct sock *sk, struct sk_buff *skb)
71 {
72         const struct dccp_hdr *dh = dccp_hdr(skb);
73         struct dccp_sock *dp = dccp_sk(sk);
74         u64 lswl, lawl, seqno = DCCP_SKB_CB(skb)->dccpd_seq,
75                         ackno = DCCP_SKB_CB(skb)->dccpd_ack_seq;
76
77         /*
78          *   Step 5: Prepare sequence numbers for Sync
79          *     If P.type == Sync or P.type == SyncAck,
80          *        If S.AWL <= P.ackno <= S.AWH and P.seqno >= S.SWL,
81          *           / * P is valid, so update sequence number variables
82          *               accordingly.  After this update, P will pass the tests
83          *               in Step 6.  A SyncAck is generated if necessary in
84          *               Step 15 * /
85          *           Update S.GSR, S.SWL, S.SWH
86          *        Otherwise,
87          *           Drop packet and return
88          */
89         if (dh->dccph_type == DCCP_PKT_SYNC ||
90             dh->dccph_type == DCCP_PKT_SYNCACK) {
91                 if (between48(ackno, dp->dccps_awl, dp->dccps_awh) &&
92                     dccp_delta_seqno(dp->dccps_swl, seqno) >= 0)
93                         dccp_update_gsr(sk, seqno);
94                 else
95                         return -1;
96         }
97
98         /*
99          *   Step 6: Check sequence numbers
100          *      Let LSWL = S.SWL and LAWL = S.AWL
101          *      If P.type == CloseReq or P.type == Close or P.type == Reset,
102          *        LSWL := S.GSR + 1, LAWL := S.GAR
103          *      If LSWL <= P.seqno <= S.SWH
104          *           and (P.ackno does not exist or LAWL <= P.ackno <= S.AWH),
105          *        Update S.GSR, S.SWL, S.SWH
106          *        If P.type != Sync,
107          *           Update S.GAR
108          */
109         lswl = dp->dccps_swl;
110         lawl = dp->dccps_awl;
111
112         if (dh->dccph_type == DCCP_PKT_CLOSEREQ ||
113             dh->dccph_type == DCCP_PKT_CLOSE ||
114             dh->dccph_type == DCCP_PKT_RESET) {
115                 lswl = ADD48(dp->dccps_gsr, 1);
116                 lawl = dp->dccps_gar;
117         }
118
119         if (between48(seqno, lswl, dp->dccps_swh) &&
120             (ackno == DCCP_PKT_WITHOUT_ACK_SEQ ||
121              between48(ackno, lawl, dp->dccps_awh))) {
122                 dccp_update_gsr(sk, seqno);
123
124                 if (dh->dccph_type != DCCP_PKT_SYNC &&
125                     (ackno != DCCP_PKT_WITHOUT_ACK_SEQ))
126                         dp->dccps_gar = ackno;
127         } else {
128                 unsigned long now = jiffies;
129                 /*
130                  *   Step 6: Check sequence numbers
131                  *      Otherwise,
132                  *         If P.type == Reset,
133                  *            Send Sync packet acknowledging S.GSR
134                  *         Otherwise,
135                  *            Send Sync packet acknowledging P.seqno
136                  *      Drop packet and return
137                  *
138                  *   These Syncs are rate-limited as per RFC 4340, 7.5.4:
139                  *   at most 1 / (dccp_sync_rate_limit * HZ) Syncs per second.
140                  */
141                 if (time_before(now, (dp->dccps_rate_last +
142                                       sysctl_dccp_sync_ratelimit)))
143                         return 0;
144
145                 DCCP_WARN("DCCP: Step 6 failed for %s packet, "
146                           "(LSWL(%llu) <= P.seqno(%llu) <= S.SWH(%llu)) and "
147                           "(P.ackno %s or LAWL(%llu) <= P.ackno(%llu) <= S.AWH(%llu), "
148                           "sending SYNC...\n",  dccp_packet_name(dh->dccph_type),
149                           (unsigned long long) lswl, (unsigned long long) seqno,
150                           (unsigned long long) dp->dccps_swh,
151                           (ackno == DCCP_PKT_WITHOUT_ACK_SEQ) ? "doesn't exist"
152                                                               : "exists",
153                           (unsigned long long) lawl, (unsigned long long) ackno,
154                           (unsigned long long) dp->dccps_awh);
155
156                 dp->dccps_rate_last = now;
157
158                 if (dh->dccph_type == DCCP_PKT_RESET)
159                         seqno = dp->dccps_gsr;
160                 dccp_send_sync(sk, seqno, DCCP_PKT_SYNC);
161                 return -1;
162         }
163
164         return 0;
165 }
166
167 static int __dccp_rcv_established(struct sock *sk, struct sk_buff *skb,
168                                   const struct dccp_hdr *dh, const unsigned len)
169 {
170         struct dccp_sock *dp = dccp_sk(sk);
171
172         switch (dccp_hdr(skb)->dccph_type) {
173         case DCCP_PKT_DATAACK:
174         case DCCP_PKT_DATA:
175                 /*
176                  * FIXME: check if sk_receive_queue is full, schedule DATA_DROPPED
177                  * option if it is.
178                  */
179                 __skb_pull(skb, dh->dccph_doff * 4);
180                 __skb_queue_tail(&sk->sk_receive_queue, skb);
181                 skb_set_owner_r(skb, sk);
182                 sk->sk_data_ready(sk, 0);
183                 return 0;
184         case DCCP_PKT_ACK:
185                 goto discard;
186         case DCCP_PKT_RESET:
187                 /*
188                  *  Step 9: Process Reset
189                  *      If P.type == Reset,
190                  *              Tear down connection
191                  *              S.state := TIMEWAIT
192                  *              Set TIMEWAIT timer
193                  *              Drop packet and return
194                 */
195                 dccp_fin(sk, skb);
196                 dccp_time_wait(sk, DCCP_TIME_WAIT, 0);
197                 return 0;
198         case DCCP_PKT_CLOSEREQ:
199                 dccp_rcv_closereq(sk, skb);
200                 goto discard;
201         case DCCP_PKT_CLOSE:
202                 dccp_rcv_close(sk, skb);
203                 return 0;
204         case DCCP_PKT_REQUEST:
205                 /* Step 7
206                  *   or (S.is_server and P.type == Response)
207                  *   or (S.is_client and P.type == Request)
208                  *   or (S.state >= OPEN and P.type == Request
209                  *      and P.seqno >= S.OSR)
210                  *    or (S.state >= OPEN and P.type == Response
211                  *      and P.seqno >= S.OSR)
212                  *    or (S.state == RESPOND and P.type == Data),
213                  *  Send Sync packet acknowledging P.seqno
214                  *  Drop packet and return
215                  */
216                 if (dp->dccps_role != DCCP_ROLE_LISTEN)
217                         goto send_sync;
218                 goto check_seq;
219         case DCCP_PKT_RESPONSE:
220                 if (dp->dccps_role != DCCP_ROLE_CLIENT)
221                         goto send_sync;
222 check_seq:
223                 if (dccp_delta_seqno(dp->dccps_osr,
224                                      DCCP_SKB_CB(skb)->dccpd_seq) >= 0) {
225 send_sync:
226                         dccp_send_sync(sk, DCCP_SKB_CB(skb)->dccpd_seq,
227                                        DCCP_PKT_SYNC);
228                 }
229                 break;
230         case DCCP_PKT_SYNC:
231                 dccp_send_sync(sk, DCCP_SKB_CB(skb)->dccpd_seq,
232                                DCCP_PKT_SYNCACK);
233                 /*
234                  * From RFC 4340, sec. 5.7
235                  *
236                  * As with DCCP-Ack packets, DCCP-Sync and DCCP-SyncAck packets
237                  * MAY have non-zero-length application data areas, whose
238                  * contents receivers MUST ignore.
239                  */
240                 goto discard;
241         }
242
243         DCCP_INC_STATS_BH(DCCP_MIB_INERRS);
244 discard:
245         __kfree_skb(skb);
246         return 0;
247 }
248
249 int dccp_rcv_established(struct sock *sk, struct sk_buff *skb,
250                          const struct dccp_hdr *dh, const unsigned len)
251 {
252         struct dccp_sock *dp = dccp_sk(sk);
253
254         if (dccp_check_seqno(sk, skb))
255                 goto discard;
256
257         if (dccp_parse_options(sk, skb))
258                 goto discard;
259
260         if (DCCP_SKB_CB(skb)->dccpd_ack_seq != DCCP_PKT_WITHOUT_ACK_SEQ)
261                 dccp_event_ack_recv(sk, skb);
262
263         if (dccp_msk(sk)->dccpms_send_ack_vector &&
264             dccp_ackvec_add(dp->dccps_hc_rx_ackvec, sk,
265                             DCCP_SKB_CB(skb)->dccpd_seq,
266                             DCCP_ACKVEC_STATE_RECEIVED))
267                 goto discard;
268
269         ccid_hc_rx_packet_recv(dp->dccps_hc_rx_ccid, sk, skb);
270         ccid_hc_tx_packet_recv(dp->dccps_hc_tx_ccid, sk, skb);
271
272         return __dccp_rcv_established(sk, skb, dh, len);
273 discard:
274         __kfree_skb(skb);
275         return 0;
276 }
277
278 EXPORT_SYMBOL_GPL(dccp_rcv_established);
279
280 static int dccp_rcv_request_sent_state_process(struct sock *sk,
281                                                struct sk_buff *skb,
282                                                const struct dccp_hdr *dh,
283                                                const unsigned len)
284 {
285         /*
286          *  Step 4: Prepare sequence numbers in REQUEST
287          *     If S.state == REQUEST,
288          *        If (P.type == Response or P.type == Reset)
289          *              and S.AWL <= P.ackno <= S.AWH,
290          *           / * Set sequence number variables corresponding to the
291          *              other endpoint, so P will pass the tests in Step 6 * /
292          *           Set S.GSR, S.ISR, S.SWL, S.SWH
293          *           / * Response processing continues in Step 10; Reset
294          *              processing continues in Step 9 * /
295         */
296         if (dh->dccph_type == DCCP_PKT_RESPONSE) {
297                 const struct inet_connection_sock *icsk = inet_csk(sk);
298                 struct dccp_sock *dp = dccp_sk(sk);
299                 long tstamp = dccp_timestamp();
300
301                 /* Stop the REQUEST timer */
302                 inet_csk_clear_xmit_timer(sk, ICSK_TIME_RETRANS);
303                 BUG_TRAP(sk->sk_send_head != NULL);
304                 __kfree_skb(sk->sk_send_head);
305                 sk->sk_send_head = NULL;
306
307                 if (!between48(DCCP_SKB_CB(skb)->dccpd_ack_seq,
308                                dp->dccps_awl, dp->dccps_awh)) {
309                         dccp_pr_debug("invalid ackno: S.AWL=%llu, "
310                                       "P.ackno=%llu, S.AWH=%llu \n",
311                                       (unsigned long long)dp->dccps_awl,
312                            (unsigned long long)DCCP_SKB_CB(skb)->dccpd_ack_seq,
313                                       (unsigned long long)dp->dccps_awh);
314                         goto out_invalid_packet;
315                 }
316
317                 if (dccp_parse_options(sk, skb))
318                         goto out_invalid_packet;
319
320                 /* Obtain usec RTT sample from SYN exchange (used by CCID 3) */
321                 if (likely(dp->dccps_options_received.dccpor_timestamp_echo))
322                         dp->dccps_syn_rtt = dccp_sample_rtt(sk, 10 * (tstamp -
323                             dp->dccps_options_received.dccpor_timestamp_echo));
324
325                 if (dccp_msk(sk)->dccpms_send_ack_vector &&
326                     dccp_ackvec_add(dp->dccps_hc_rx_ackvec, sk,
327                                     DCCP_SKB_CB(skb)->dccpd_seq,
328                                     DCCP_ACKVEC_STATE_RECEIVED))
329                         goto out_invalid_packet; /* FIXME: change error code */
330
331                 dp->dccps_isr = DCCP_SKB_CB(skb)->dccpd_seq;
332                 dccp_update_gsr(sk, dp->dccps_isr);
333                 /*
334                  * SWL and AWL are initially adjusted so that they are not less than
335                  * the initial Sequence Numbers received and sent, respectively:
336                  *      SWL := max(GSR + 1 - floor(W/4), ISR),
337                  *      AWL := max(GSS - W' + 1, ISS).
338                  * These adjustments MUST be applied only at the beginning of the
339                  * connection.
340                  *
341                  * AWL was adjusted in dccp_v4_connect -acme
342                  */
343                 dccp_set_seqno(&dp->dccps_swl,
344                                max48(dp->dccps_swl, dp->dccps_isr));
345
346                 dccp_sync_mss(sk, icsk->icsk_pmtu_cookie);
347
348                 /*
349                  *    Step 10: Process REQUEST state (second part)
350                  *       If S.state == REQUEST,
351                  *        / * If we get here, P is a valid Response from the
352                  *            server (see Step 4), and we should move to
353                  *            PARTOPEN state. PARTOPEN means send an Ack,
354                  *            don't send Data packets, retransmit Acks
355                  *            periodically, and always include any Init Cookie
356                  *            from the Response * /
357                  *        S.state := PARTOPEN
358                  *        Set PARTOPEN timer
359                  *        Continue with S.state == PARTOPEN
360                  *        / * Step 12 will send the Ack completing the
361                  *            three-way handshake * /
362                  */
363                 dccp_set_state(sk, DCCP_PARTOPEN);
364
365                 /* Make sure socket is routed, for correct metrics. */
366                 icsk->icsk_af_ops->rebuild_header(sk);
367
368                 if (!sock_flag(sk, SOCK_DEAD)) {
369                         sk->sk_state_change(sk);
370                         sk_wake_async(sk, 0, POLL_OUT);
371                 }
372
373                 if (sk->sk_write_pending || icsk->icsk_ack.pingpong ||
374                     icsk->icsk_accept_queue.rskq_defer_accept) {
375                         /* Save one ACK. Data will be ready after
376                          * several ticks, if write_pending is set.
377                          *
378                          * It may be deleted, but with this feature tcpdumps
379                          * look so _wonderfully_ clever, that I was not able
380                          * to stand against the temptation 8)     --ANK
381                          */
382                         /*
383                          * OK, in DCCP we can as well do a similar trick, its
384                          * even in the draft, but there is no need for us to
385                          * schedule an ack here, as dccp_sendmsg does this for
386                          * us, also stated in the draft. -acme
387                          */
388                         __kfree_skb(skb);
389                         return 0;
390                 }
391                 dccp_send_ack(sk);
392                 return -1;
393         }
394
395 out_invalid_packet:
396         /* dccp_v4_do_rcv will send a reset */
397         DCCP_SKB_CB(skb)->dccpd_reset_code = DCCP_RESET_CODE_PACKET_ERROR;
398         return 1;
399 }
400
401 static int dccp_rcv_respond_partopen_state_process(struct sock *sk,
402                                                    struct sk_buff *skb,
403                                                    const struct dccp_hdr *dh,
404                                                    const unsigned len)
405 {
406         int queued = 0;
407
408         switch (dh->dccph_type) {
409         case DCCP_PKT_RESET:
410                 inet_csk_clear_xmit_timer(sk, ICSK_TIME_DACK);
411                 break;
412         case DCCP_PKT_DATA:
413                 if (sk->sk_state == DCCP_RESPOND)
414                         break;
415         case DCCP_PKT_DATAACK:
416         case DCCP_PKT_ACK:
417                 /*
418                  * FIXME: we should be reseting the PARTOPEN (DELACK) timer
419                  * here but only if we haven't used the DELACK timer for
420                  * something else, like sending a delayed ack for a TIMESTAMP
421                  * echo, etc, for now were not clearing it, sending an extra
422                  * ACK when there is nothing else to do in DELACK is not a big
423                  * deal after all.
424                  */
425
426                 /* Stop the PARTOPEN timer */
427                 if (sk->sk_state == DCCP_PARTOPEN)
428                         inet_csk_clear_xmit_timer(sk, ICSK_TIME_DACK);
429
430                 dccp_sk(sk)->dccps_osr = DCCP_SKB_CB(skb)->dccpd_seq;
431                 dccp_set_state(sk, DCCP_OPEN);
432
433                 if (dh->dccph_type == DCCP_PKT_DATAACK ||
434                     dh->dccph_type == DCCP_PKT_DATA) {
435                         __dccp_rcv_established(sk, skb, dh, len);
436                         queued = 1; /* packet was queued
437                                        (by __dccp_rcv_established) */
438                 }
439                 break;
440         }
441
442         return queued;
443 }
444
445 int dccp_rcv_state_process(struct sock *sk, struct sk_buff *skb,
446                            struct dccp_hdr *dh, unsigned len)
447 {
448         struct dccp_sock *dp = dccp_sk(sk);
449         struct dccp_skb_cb *dcb = DCCP_SKB_CB(skb);
450         const int old_state = sk->sk_state;
451         int queued = 0;
452
453         /*
454          *  Step 3: Process LISTEN state
455          *
456          *     If S.state == LISTEN,
457          *       If P.type == Request or P contains a valid Init Cookie option,
458          *            (* Must scan the packet's options to check for Init
459          *               Cookies.  Only Init Cookies are processed here,
460          *               however; other options are processed in Step 8.  This
461          *               scan need only be performed if the endpoint uses Init
462          *               Cookies *)
463          *            (* Generate a new socket and switch to that socket *)
464          *            Set S := new socket for this port pair
465          *            S.state = RESPOND
466          *            Choose S.ISS (initial seqno) or set from Init Cookies
467          *            Initialize S.GAR := S.ISS
468          *            Set S.ISR, S.GSR, S.SWL, S.SWH from packet or Init
469          *            Cookies Continue with S.state == RESPOND
470          *            (* A Response packet will be generated in Step 11 *)
471          *       Otherwise,
472          *            Generate Reset(No Connection) unless P.type == Reset
473          *            Drop packet and return
474          */
475         if (sk->sk_state == DCCP_LISTEN) {
476                 if (dh->dccph_type == DCCP_PKT_REQUEST) {
477                         if (inet_csk(sk)->icsk_af_ops->conn_request(sk,
478                                                                     skb) < 0)
479                                 return 1;
480
481                         /* FIXME: do congestion control initialization */
482                         goto discard;
483                 }
484                 if (dh->dccph_type == DCCP_PKT_RESET)
485                         goto discard;
486
487                 /* Caller (dccp_v4_do_rcv) will send Reset */
488                 dcb->dccpd_reset_code = DCCP_RESET_CODE_NO_CONNECTION;
489                 return 1;
490         }
491
492         if (sk->sk_state != DCCP_REQUESTING) {
493                 if (dccp_check_seqno(sk, skb))
494                         goto discard;
495
496                 /*
497                  * Step 8: Process options and mark acknowledgeable
498                  */
499                 if (dccp_parse_options(sk, skb))
500                         goto discard;
501
502                 if (dcb->dccpd_ack_seq != DCCP_PKT_WITHOUT_ACK_SEQ)
503                         dccp_event_ack_recv(sk, skb);
504
505                 if (dccp_msk(sk)->dccpms_send_ack_vector &&
506                     dccp_ackvec_add(dp->dccps_hc_rx_ackvec, sk,
507                                     DCCP_SKB_CB(skb)->dccpd_seq,
508                                     DCCP_ACKVEC_STATE_RECEIVED))
509                         goto discard;
510
511                 ccid_hc_rx_packet_recv(dp->dccps_hc_rx_ccid, sk, skb);
512                 ccid_hc_tx_packet_recv(dp->dccps_hc_tx_ccid, sk, skb);
513         }
514
515         /*
516          *  Step 9: Process Reset
517          *      If P.type == Reset,
518          *              Tear down connection
519          *              S.state := TIMEWAIT
520          *              Set TIMEWAIT timer
521          *              Drop packet and return
522         */
523         if (dh->dccph_type == DCCP_PKT_RESET) {
524                 /*
525                  * Queue the equivalent of TCP fin so that dccp_recvmsg
526                  * exits the loop
527                  */
528                 dccp_fin(sk, skb);
529                 dccp_time_wait(sk, DCCP_TIME_WAIT, 0);
530                 return 0;
531                 /*
532                  *   Step 7: Check for unexpected packet types
533                  *      If (S.is_server and P.type == CloseReq)
534                  *          or (S.is_server and P.type == Response)
535                  *          or (S.is_client and P.type == Request)
536                  *          or (S.state == RESPOND and P.type == Data),
537                  *        Send Sync packet acknowledging P.seqno
538                  *        Drop packet and return
539                  */
540         } else if ((dp->dccps_role != DCCP_ROLE_CLIENT &&
541                     (dh->dccph_type == DCCP_PKT_RESPONSE ||
542                      dh->dccph_type == DCCP_PKT_CLOSEREQ)) ||
543                     (dp->dccps_role == DCCP_ROLE_CLIENT &&
544                      dh->dccph_type == DCCP_PKT_REQUEST) ||
545                     (sk->sk_state == DCCP_RESPOND &&
546                      dh->dccph_type == DCCP_PKT_DATA)) {
547                 dccp_send_sync(sk, dcb->dccpd_seq, DCCP_PKT_SYNC);
548                 goto discard;
549         } else if (dh->dccph_type == DCCP_PKT_CLOSEREQ) {
550                 dccp_rcv_closereq(sk, skb);
551                 goto discard;
552         } else if (dh->dccph_type == DCCP_PKT_CLOSE) {
553                 dccp_rcv_close(sk, skb);
554                 return 0;
555         }
556
557         switch (sk->sk_state) {
558         case DCCP_CLOSED:
559                 dcb->dccpd_reset_code = DCCP_RESET_CODE_NO_CONNECTION;
560                 return 1;
561
562         case DCCP_REQUESTING:
563                 /* FIXME: do congestion control initialization */
564
565                 queued = dccp_rcv_request_sent_state_process(sk, skb, dh, len);
566                 if (queued >= 0)
567                         return queued;
568
569                 __kfree_skb(skb);
570                 return 0;
571
572         case DCCP_RESPOND:
573         case DCCP_PARTOPEN:
574                 queued = dccp_rcv_respond_partopen_state_process(sk, skb,
575                                                                  dh, len);
576                 break;
577         }
578
579         if (dh->dccph_type == DCCP_PKT_ACK ||
580             dh->dccph_type == DCCP_PKT_DATAACK) {
581                 switch (old_state) {
582                 case DCCP_PARTOPEN:
583                         sk->sk_state_change(sk);
584                         sk_wake_async(sk, 0, POLL_OUT);
585                         break;
586                 }
587         } else if (unlikely(dh->dccph_type == DCCP_PKT_SYNC)) {
588                 dccp_send_sync(sk, dcb->dccpd_seq, DCCP_PKT_SYNCACK);
589                 goto discard;
590         }
591
592         if (!queued) {
593 discard:
594                 __kfree_skb(skb);
595         }
596         return 0;
597 }
598
599 EXPORT_SYMBOL_GPL(dccp_rcv_state_process);
600
601 /**
602  *  dccp_sample_rtt  -  Validate and finalise computation of RTT sample
603  *  @delta:     number of microseconds between packet and acknowledgment
604  *  The routine is kept generic to work in different contexts. It should be
605  *  called immediately when the ACK used for the RTT sample arrives.
606  */
607 u32 dccp_sample_rtt(struct sock *sk, long delta)
608 {
609         /* dccpor_elapsed_time is either zeroed out or set and > 0 */
610         delta -= dccp_sk(sk)->dccps_options_received.dccpor_elapsed_time * 10;
611
612         if (unlikely(delta <= 0)) {
613                 DCCP_WARN("unusable RTT sample %ld, using min\n", delta);
614                 return DCCP_SANE_RTT_MIN;
615         }
616         if (unlikely(delta > DCCP_SANE_RTT_MAX)) {
617                 DCCP_WARN("RTT sample %ld too large, using max\n", delta);
618                 return DCCP_SANE_RTT_MAX;
619         }
620
621         return delta;
622 }
623
624 EXPORT_SYMBOL_GPL(dccp_sample_rtt);