Pull alexey-fixes into release branch
[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 u8 dccp_reset_code_convert(const u8 code)
62 {
63         const u8 error_code[] = {
64         [DCCP_RESET_CODE_CLOSED]             = 0,       /* normal termination */
65         [DCCP_RESET_CODE_UNSPECIFIED]        = 0,       /* nothing known */
66         [DCCP_RESET_CODE_ABORTED]            = ECONNRESET,
67
68         [DCCP_RESET_CODE_NO_CONNECTION]      = ECONNREFUSED,
69         [DCCP_RESET_CODE_CONNECTION_REFUSED] = ECONNREFUSED,
70         [DCCP_RESET_CODE_TOO_BUSY]           = EUSERS,
71         [DCCP_RESET_CODE_AGGRESSION_PENALTY] = EDQUOT,
72
73         [DCCP_RESET_CODE_PACKET_ERROR]       = ENOMSG,
74         [DCCP_RESET_CODE_BAD_INIT_COOKIE]    = EBADR,
75         [DCCP_RESET_CODE_BAD_SERVICE_CODE]   = EBADRQC,
76         [DCCP_RESET_CODE_OPTION_ERROR]       = EILSEQ,
77         [DCCP_RESET_CODE_MANDATORY_ERROR]    = EOPNOTSUPP,
78         };
79
80         return code >= DCCP_MAX_RESET_CODES ? 0 : error_code[code];
81 }
82
83 static void dccp_rcv_reset(struct sock *sk, struct sk_buff *skb)
84 {
85         u8 err = dccp_reset_code_convert(dccp_hdr_reset(skb)->dccph_reset_code);
86
87         sk->sk_err = err;
88
89         /* Queue the equivalent of TCP fin so that dccp_recvmsg exits the loop */
90         dccp_fin(sk, skb);
91
92         if (err && !sock_flag(sk, SOCK_DEAD))
93                 sk_wake_async(sk, 0, POLL_ERR);
94         dccp_time_wait(sk, DCCP_TIME_WAIT, 0);
95 }
96
97 static void dccp_event_ack_recv(struct sock *sk, struct sk_buff *skb)
98 {
99         struct dccp_sock *dp = dccp_sk(sk);
100
101         if (dccp_msk(sk)->dccpms_send_ack_vector)
102                 dccp_ackvec_check_rcv_ackno(dp->dccps_hc_rx_ackvec, sk,
103                                             DCCP_SKB_CB(skb)->dccpd_ack_seq);
104 }
105
106 static int dccp_check_seqno(struct sock *sk, struct sk_buff *skb)
107 {
108         const struct dccp_hdr *dh = dccp_hdr(skb);
109         struct dccp_sock *dp = dccp_sk(sk);
110         u64 lswl, lawl, seqno = DCCP_SKB_CB(skb)->dccpd_seq,
111                         ackno = DCCP_SKB_CB(skb)->dccpd_ack_seq;
112
113         /*
114          *   Step 5: Prepare sequence numbers for Sync
115          *     If P.type == Sync or P.type == SyncAck,
116          *        If S.AWL <= P.ackno <= S.AWH and P.seqno >= S.SWL,
117          *           / * P is valid, so update sequence number variables
118          *               accordingly.  After this update, P will pass the tests
119          *               in Step 6.  A SyncAck is generated if necessary in
120          *               Step 15 * /
121          *           Update S.GSR, S.SWL, S.SWH
122          *        Otherwise,
123          *           Drop packet and return
124          */
125         if (dh->dccph_type == DCCP_PKT_SYNC ||
126             dh->dccph_type == DCCP_PKT_SYNCACK) {
127                 if (between48(ackno, dp->dccps_awl, dp->dccps_awh) &&
128                     dccp_delta_seqno(dp->dccps_swl, seqno) >= 0)
129                         dccp_update_gsr(sk, seqno);
130                 else
131                         return -1;
132         }
133
134         /*
135          *   Step 6: Check sequence numbers
136          *      Let LSWL = S.SWL and LAWL = S.AWL
137          *      If P.type == CloseReq or P.type == Close or P.type == Reset,
138          *        LSWL := S.GSR + 1, LAWL := S.GAR
139          *      If LSWL <= P.seqno <= S.SWH
140          *           and (P.ackno does not exist or LAWL <= P.ackno <= S.AWH),
141          *        Update S.GSR, S.SWL, S.SWH
142          *        If P.type != Sync,
143          *           Update S.GAR
144          */
145         lswl = dp->dccps_swl;
146         lawl = dp->dccps_awl;
147
148         if (dh->dccph_type == DCCP_PKT_CLOSEREQ ||
149             dh->dccph_type == DCCP_PKT_CLOSE ||
150             dh->dccph_type == DCCP_PKT_RESET) {
151                 lswl = ADD48(dp->dccps_gsr, 1);
152                 lawl = dp->dccps_gar;
153         }
154
155         if (between48(seqno, lswl, dp->dccps_swh) &&
156             (ackno == DCCP_PKT_WITHOUT_ACK_SEQ ||
157              between48(ackno, lawl, dp->dccps_awh))) {
158                 dccp_update_gsr(sk, seqno);
159
160                 if (dh->dccph_type != DCCP_PKT_SYNC &&
161                     (ackno != DCCP_PKT_WITHOUT_ACK_SEQ))
162                         dp->dccps_gar = ackno;
163         } else {
164                 unsigned long now = jiffies;
165                 /*
166                  *   Step 6: Check sequence numbers
167                  *      Otherwise,
168                  *         If P.type == Reset,
169                  *            Send Sync packet acknowledging S.GSR
170                  *         Otherwise,
171                  *            Send Sync packet acknowledging P.seqno
172                  *      Drop packet and return
173                  *
174                  *   These Syncs are rate-limited as per RFC 4340, 7.5.4:
175                  *   at most 1 / (dccp_sync_rate_limit * HZ) Syncs per second.
176                  */
177                 if (time_before(now, (dp->dccps_rate_last +
178                                       sysctl_dccp_sync_ratelimit)))
179                         return 0;
180
181                 DCCP_WARN("DCCP: Step 6 failed for %s packet, "
182                           "(LSWL(%llu) <= P.seqno(%llu) <= S.SWH(%llu)) and "
183                           "(P.ackno %s or LAWL(%llu) <= P.ackno(%llu) <= S.AWH(%llu), "
184                           "sending SYNC...\n",  dccp_packet_name(dh->dccph_type),
185                           (unsigned long long) lswl, (unsigned long long) seqno,
186                           (unsigned long long) dp->dccps_swh,
187                           (ackno == DCCP_PKT_WITHOUT_ACK_SEQ) ? "doesn't exist"
188                                                               : "exists",
189                           (unsigned long long) lawl, (unsigned long long) ackno,
190                           (unsigned long long) dp->dccps_awh);
191
192                 dp->dccps_rate_last = now;
193
194                 if (dh->dccph_type == DCCP_PKT_RESET)
195                         seqno = dp->dccps_gsr;
196                 dccp_send_sync(sk, seqno, DCCP_PKT_SYNC);
197                 return -1;
198         }
199
200         return 0;
201 }
202
203 static int __dccp_rcv_established(struct sock *sk, struct sk_buff *skb,
204                                   const struct dccp_hdr *dh, const unsigned len)
205 {
206         struct dccp_sock *dp = dccp_sk(sk);
207
208         switch (dccp_hdr(skb)->dccph_type) {
209         case DCCP_PKT_DATAACK:
210         case DCCP_PKT_DATA:
211                 /*
212                  * FIXME: check if sk_receive_queue is full, schedule DATA_DROPPED
213                  * option if it is.
214                  */
215                 __skb_pull(skb, dh->dccph_doff * 4);
216                 __skb_queue_tail(&sk->sk_receive_queue, skb);
217                 skb_set_owner_r(skb, sk);
218                 sk->sk_data_ready(sk, 0);
219                 return 0;
220         case DCCP_PKT_ACK:
221                 goto discard;
222         case DCCP_PKT_RESET:
223                 /*
224                  *  Step 9: Process Reset
225                  *      If P.type == Reset,
226                  *              Tear down connection
227                  *              S.state := TIMEWAIT
228                  *              Set TIMEWAIT timer
229                  *              Drop packet and return
230                  */
231                 dccp_rcv_reset(sk, skb);
232                 return 0;
233         case DCCP_PKT_CLOSEREQ:
234                 dccp_rcv_closereq(sk, skb);
235                 goto discard;
236         case DCCP_PKT_CLOSE:
237                 dccp_rcv_close(sk, skb);
238                 return 0;
239         case DCCP_PKT_REQUEST:
240                 /* Step 7
241                  *   or (S.is_server and P.type == Response)
242                  *   or (S.is_client and P.type == Request)
243                  *   or (S.state >= OPEN and P.type == Request
244                  *      and P.seqno >= S.OSR)
245                  *    or (S.state >= OPEN and P.type == Response
246                  *      and P.seqno >= S.OSR)
247                  *    or (S.state == RESPOND and P.type == Data),
248                  *  Send Sync packet acknowledging P.seqno
249                  *  Drop packet and return
250                  */
251                 if (dp->dccps_role != DCCP_ROLE_LISTEN)
252                         goto send_sync;
253                 goto check_seq;
254         case DCCP_PKT_RESPONSE:
255                 if (dp->dccps_role != DCCP_ROLE_CLIENT)
256                         goto send_sync;
257 check_seq:
258                 if (dccp_delta_seqno(dp->dccps_osr,
259                                      DCCP_SKB_CB(skb)->dccpd_seq) >= 0) {
260 send_sync:
261                         dccp_send_sync(sk, DCCP_SKB_CB(skb)->dccpd_seq,
262                                        DCCP_PKT_SYNC);
263                 }
264                 break;
265         case DCCP_PKT_SYNC:
266                 dccp_send_sync(sk, DCCP_SKB_CB(skb)->dccpd_seq,
267                                DCCP_PKT_SYNCACK);
268                 /*
269                  * From RFC 4340, sec. 5.7
270                  *
271                  * As with DCCP-Ack packets, DCCP-Sync and DCCP-SyncAck packets
272                  * MAY have non-zero-length application data areas, whose
273                  * contents receivers MUST ignore.
274                  */
275                 goto discard;
276         }
277
278         DCCP_INC_STATS_BH(DCCP_MIB_INERRS);
279 discard:
280         __kfree_skb(skb);
281         return 0;
282 }
283
284 int dccp_rcv_established(struct sock *sk, struct sk_buff *skb,
285                          const struct dccp_hdr *dh, const unsigned len)
286 {
287         struct dccp_sock *dp = dccp_sk(sk);
288
289         if (dccp_check_seqno(sk, skb))
290                 goto discard;
291
292         if (dccp_parse_options(sk, skb))
293                 goto discard;
294
295         if (DCCP_SKB_CB(skb)->dccpd_ack_seq != DCCP_PKT_WITHOUT_ACK_SEQ)
296                 dccp_event_ack_recv(sk, skb);
297
298         if (dccp_msk(sk)->dccpms_send_ack_vector &&
299             dccp_ackvec_add(dp->dccps_hc_rx_ackvec, sk,
300                             DCCP_SKB_CB(skb)->dccpd_seq,
301                             DCCP_ACKVEC_STATE_RECEIVED))
302                 goto discard;
303
304         ccid_hc_rx_packet_recv(dp->dccps_hc_rx_ccid, sk, skb);
305         ccid_hc_tx_packet_recv(dp->dccps_hc_tx_ccid, sk, skb);
306
307         return __dccp_rcv_established(sk, skb, dh, len);
308 discard:
309         __kfree_skb(skb);
310         return 0;
311 }
312
313 EXPORT_SYMBOL_GPL(dccp_rcv_established);
314
315 static int dccp_rcv_request_sent_state_process(struct sock *sk,
316                                                struct sk_buff *skb,
317                                                const struct dccp_hdr *dh,
318                                                const unsigned len)
319 {
320         /*
321          *  Step 4: Prepare sequence numbers in REQUEST
322          *     If S.state == REQUEST,
323          *        If (P.type == Response or P.type == Reset)
324          *              and S.AWL <= P.ackno <= S.AWH,
325          *           / * Set sequence number variables corresponding to the
326          *              other endpoint, so P will pass the tests in Step 6 * /
327          *           Set S.GSR, S.ISR, S.SWL, S.SWH
328          *           / * Response processing continues in Step 10; Reset
329          *              processing continues in Step 9 * /
330         */
331         if (dh->dccph_type == DCCP_PKT_RESPONSE) {
332                 const struct inet_connection_sock *icsk = inet_csk(sk);
333                 struct dccp_sock *dp = dccp_sk(sk);
334                 long tstamp = dccp_timestamp();
335
336                 /* Stop the REQUEST timer */
337                 inet_csk_clear_xmit_timer(sk, ICSK_TIME_RETRANS);
338                 BUG_TRAP(sk->sk_send_head != NULL);
339                 __kfree_skb(sk->sk_send_head);
340                 sk->sk_send_head = NULL;
341
342                 if (!between48(DCCP_SKB_CB(skb)->dccpd_ack_seq,
343                                dp->dccps_awl, dp->dccps_awh)) {
344                         dccp_pr_debug("invalid ackno: S.AWL=%llu, "
345                                       "P.ackno=%llu, S.AWH=%llu \n",
346                                       (unsigned long long)dp->dccps_awl,
347                            (unsigned long long)DCCP_SKB_CB(skb)->dccpd_ack_seq,
348                                       (unsigned long long)dp->dccps_awh);
349                         goto out_invalid_packet;
350                 }
351
352                 if (dccp_parse_options(sk, skb))
353                         goto out_invalid_packet;
354
355                 /* Obtain usec RTT sample from SYN exchange (used by CCID 3) */
356                 if (likely(dp->dccps_options_received.dccpor_timestamp_echo))
357                         dp->dccps_syn_rtt = dccp_sample_rtt(sk, 10 * (tstamp -
358                             dp->dccps_options_received.dccpor_timestamp_echo));
359
360                 if (dccp_msk(sk)->dccpms_send_ack_vector &&
361                     dccp_ackvec_add(dp->dccps_hc_rx_ackvec, sk,
362                                     DCCP_SKB_CB(skb)->dccpd_seq,
363                                     DCCP_ACKVEC_STATE_RECEIVED))
364                         goto out_invalid_packet; /* FIXME: change error code */
365
366                 dp->dccps_isr = DCCP_SKB_CB(skb)->dccpd_seq;
367                 dccp_update_gsr(sk, dp->dccps_isr);
368                 /*
369                  * SWL and AWL are initially adjusted so that they are not less than
370                  * the initial Sequence Numbers received and sent, respectively:
371                  *      SWL := max(GSR + 1 - floor(W/4), ISR),
372                  *      AWL := max(GSS - W' + 1, ISS).
373                  * These adjustments MUST be applied only at the beginning of the
374                  * connection.
375                  *
376                  * AWL was adjusted in dccp_v4_connect -acme
377                  */
378                 dccp_set_seqno(&dp->dccps_swl,
379                                max48(dp->dccps_swl, dp->dccps_isr));
380
381                 dccp_sync_mss(sk, icsk->icsk_pmtu_cookie);
382
383                 /*
384                  *    Step 10: Process REQUEST state (second part)
385                  *       If S.state == REQUEST,
386                  *        / * If we get here, P is a valid Response from the
387                  *            server (see Step 4), and we should move to
388                  *            PARTOPEN state. PARTOPEN means send an Ack,
389                  *            don't send Data packets, retransmit Acks
390                  *            periodically, and always include any Init Cookie
391                  *            from the Response * /
392                  *        S.state := PARTOPEN
393                  *        Set PARTOPEN timer
394                  *        Continue with S.state == PARTOPEN
395                  *        / * Step 12 will send the Ack completing the
396                  *            three-way handshake * /
397                  */
398                 dccp_set_state(sk, DCCP_PARTOPEN);
399
400                 /* Make sure socket is routed, for correct metrics. */
401                 icsk->icsk_af_ops->rebuild_header(sk);
402
403                 if (!sock_flag(sk, SOCK_DEAD)) {
404                         sk->sk_state_change(sk);
405                         sk_wake_async(sk, 0, POLL_OUT);
406                 }
407
408                 if (sk->sk_write_pending || icsk->icsk_ack.pingpong ||
409                     icsk->icsk_accept_queue.rskq_defer_accept) {
410                         /* Save one ACK. Data will be ready after
411                          * several ticks, if write_pending is set.
412                          *
413                          * It may be deleted, but with this feature tcpdumps
414                          * look so _wonderfully_ clever, that I was not able
415                          * to stand against the temptation 8)     --ANK
416                          */
417                         /*
418                          * OK, in DCCP we can as well do a similar trick, its
419                          * even in the draft, but there is no need for us to
420                          * schedule an ack here, as dccp_sendmsg does this for
421                          * us, also stated in the draft. -acme
422                          */
423                         __kfree_skb(skb);
424                         return 0;
425                 }
426                 dccp_send_ack(sk);
427                 return -1;
428         }
429
430 out_invalid_packet:
431         /* dccp_v4_do_rcv will send a reset */
432         DCCP_SKB_CB(skb)->dccpd_reset_code = DCCP_RESET_CODE_PACKET_ERROR;
433         return 1;
434 }
435
436 static int dccp_rcv_respond_partopen_state_process(struct sock *sk,
437                                                    struct sk_buff *skb,
438                                                    const struct dccp_hdr *dh,
439                                                    const unsigned len)
440 {
441         int queued = 0;
442
443         switch (dh->dccph_type) {
444         case DCCP_PKT_RESET:
445                 inet_csk_clear_xmit_timer(sk, ICSK_TIME_DACK);
446                 break;
447         case DCCP_PKT_DATA:
448                 if (sk->sk_state == DCCP_RESPOND)
449                         break;
450         case DCCP_PKT_DATAACK:
451         case DCCP_PKT_ACK:
452                 /*
453                  * FIXME: we should be reseting the PARTOPEN (DELACK) timer
454                  * here but only if we haven't used the DELACK timer for
455                  * something else, like sending a delayed ack for a TIMESTAMP
456                  * echo, etc, for now were not clearing it, sending an extra
457                  * ACK when there is nothing else to do in DELACK is not a big
458                  * deal after all.
459                  */
460
461                 /* Stop the PARTOPEN timer */
462                 if (sk->sk_state == DCCP_PARTOPEN)
463                         inet_csk_clear_xmit_timer(sk, ICSK_TIME_DACK);
464
465                 dccp_sk(sk)->dccps_osr = DCCP_SKB_CB(skb)->dccpd_seq;
466                 dccp_set_state(sk, DCCP_OPEN);
467
468                 if (dh->dccph_type == DCCP_PKT_DATAACK ||
469                     dh->dccph_type == DCCP_PKT_DATA) {
470                         __dccp_rcv_established(sk, skb, dh, len);
471                         queued = 1; /* packet was queued
472                                        (by __dccp_rcv_established) */
473                 }
474                 break;
475         }
476
477         return queued;
478 }
479
480 int dccp_rcv_state_process(struct sock *sk, struct sk_buff *skb,
481                            struct dccp_hdr *dh, unsigned len)
482 {
483         struct dccp_sock *dp = dccp_sk(sk);
484         struct dccp_skb_cb *dcb = DCCP_SKB_CB(skb);
485         const int old_state = sk->sk_state;
486         int queued = 0;
487
488         /*
489          *  Step 3: Process LISTEN state
490          *
491          *     If S.state == LISTEN,
492          *       If P.type == Request or P contains a valid Init Cookie option,
493          *            (* Must scan the packet's options to check for Init
494          *               Cookies.  Only Init Cookies are processed here,
495          *               however; other options are processed in Step 8.  This
496          *               scan need only be performed if the endpoint uses Init
497          *               Cookies *)
498          *            (* Generate a new socket and switch to that socket *)
499          *            Set S := new socket for this port pair
500          *            S.state = RESPOND
501          *            Choose S.ISS (initial seqno) or set from Init Cookies
502          *            Initialize S.GAR := S.ISS
503          *            Set S.ISR, S.GSR, S.SWL, S.SWH from packet or Init
504          *            Cookies Continue with S.state == RESPOND
505          *            (* A Response packet will be generated in Step 11 *)
506          *       Otherwise,
507          *            Generate Reset(No Connection) unless P.type == Reset
508          *            Drop packet and return
509          */
510         if (sk->sk_state == DCCP_LISTEN) {
511                 if (dh->dccph_type == DCCP_PKT_REQUEST) {
512                         if (inet_csk(sk)->icsk_af_ops->conn_request(sk,
513                                                                     skb) < 0)
514                                 return 1;
515
516                         /* FIXME: do congestion control initialization */
517                         goto discard;
518                 }
519                 if (dh->dccph_type == DCCP_PKT_RESET)
520                         goto discard;
521
522                 /* Caller (dccp_v4_do_rcv) will send Reset */
523                 dcb->dccpd_reset_code = DCCP_RESET_CODE_NO_CONNECTION;
524                 return 1;
525         }
526
527         if (sk->sk_state != DCCP_REQUESTING) {
528                 if (dccp_check_seqno(sk, skb))
529                         goto discard;
530
531                 /*
532                  * Step 8: Process options and mark acknowledgeable
533                  */
534                 if (dccp_parse_options(sk, skb))
535                         goto discard;
536
537                 if (dcb->dccpd_ack_seq != DCCP_PKT_WITHOUT_ACK_SEQ)
538                         dccp_event_ack_recv(sk, skb);
539
540                 if (dccp_msk(sk)->dccpms_send_ack_vector &&
541                     dccp_ackvec_add(dp->dccps_hc_rx_ackvec, sk,
542                                     DCCP_SKB_CB(skb)->dccpd_seq,
543                                     DCCP_ACKVEC_STATE_RECEIVED))
544                         goto discard;
545
546                 ccid_hc_rx_packet_recv(dp->dccps_hc_rx_ccid, sk, skb);
547                 ccid_hc_tx_packet_recv(dp->dccps_hc_tx_ccid, sk, skb);
548         }
549
550         /*
551          *  Step 9: Process Reset
552          *      If P.type == Reset,
553          *              Tear down connection
554          *              S.state := TIMEWAIT
555          *              Set TIMEWAIT timer
556          *              Drop packet and return
557         */
558         if (dh->dccph_type == DCCP_PKT_RESET) {
559                 dccp_rcv_reset(sk, skb);
560                 return 0;
561                 /*
562                  *   Step 7: Check for unexpected packet types
563                  *      If (S.is_server and P.type == CloseReq)
564                  *          or (S.is_server and P.type == Response)
565                  *          or (S.is_client and P.type == Request)
566                  *          or (S.state == RESPOND and P.type == Data),
567                  *        Send Sync packet acknowledging P.seqno
568                  *        Drop packet and return
569                  */
570         } else if ((dp->dccps_role != DCCP_ROLE_CLIENT &&
571                     (dh->dccph_type == DCCP_PKT_RESPONSE ||
572                      dh->dccph_type == DCCP_PKT_CLOSEREQ)) ||
573                     (dp->dccps_role == DCCP_ROLE_CLIENT &&
574                      dh->dccph_type == DCCP_PKT_REQUEST) ||
575                     (sk->sk_state == DCCP_RESPOND &&
576                      dh->dccph_type == DCCP_PKT_DATA)) {
577                 dccp_send_sync(sk, dcb->dccpd_seq, DCCP_PKT_SYNC);
578                 goto discard;
579         } else if (dh->dccph_type == DCCP_PKT_CLOSEREQ) {
580                 dccp_rcv_closereq(sk, skb);
581                 goto discard;
582         } else if (dh->dccph_type == DCCP_PKT_CLOSE) {
583                 dccp_rcv_close(sk, skb);
584                 return 0;
585         }
586
587         switch (sk->sk_state) {
588         case DCCP_CLOSED:
589                 dcb->dccpd_reset_code = DCCP_RESET_CODE_NO_CONNECTION;
590                 return 1;
591
592         case DCCP_REQUESTING:
593                 /* FIXME: do congestion control initialization */
594
595                 queued = dccp_rcv_request_sent_state_process(sk, skb, dh, len);
596                 if (queued >= 0)
597                         return queued;
598
599                 __kfree_skb(skb);
600                 return 0;
601
602         case DCCP_RESPOND:
603         case DCCP_PARTOPEN:
604                 queued = dccp_rcv_respond_partopen_state_process(sk, skb,
605                                                                  dh, len);
606                 break;
607         }
608
609         if (dh->dccph_type == DCCP_PKT_ACK ||
610             dh->dccph_type == DCCP_PKT_DATAACK) {
611                 switch (old_state) {
612                 case DCCP_PARTOPEN:
613                         sk->sk_state_change(sk);
614                         sk_wake_async(sk, 0, POLL_OUT);
615                         break;
616                 }
617         } else if (unlikely(dh->dccph_type == DCCP_PKT_SYNC)) {
618                 dccp_send_sync(sk, dcb->dccpd_seq, DCCP_PKT_SYNCACK);
619                 goto discard;
620         }
621
622         if (!queued) {
623 discard:
624                 __kfree_skb(skb);
625         }
626         return 0;
627 }
628
629 EXPORT_SYMBOL_GPL(dccp_rcv_state_process);
630
631 /**
632  *  dccp_sample_rtt  -  Validate and finalise computation of RTT sample
633  *  @delta:     number of microseconds between packet and acknowledgment
634  *  The routine is kept generic to work in different contexts. It should be
635  *  called immediately when the ACK used for the RTT sample arrives.
636  */
637 u32 dccp_sample_rtt(struct sock *sk, long delta)
638 {
639         /* dccpor_elapsed_time is either zeroed out or set and > 0 */
640         delta -= dccp_sk(sk)->dccps_options_received.dccpor_elapsed_time * 10;
641
642         if (unlikely(delta <= 0)) {
643                 DCCP_WARN("unusable RTT sample %ld, using min\n", delta);
644                 return DCCP_SANE_RTT_MIN;
645         }
646         if (unlikely(delta > DCCP_SANE_RTT_MAX)) {
647                 DCCP_WARN("RTT sample %ld too large, using max\n", delta);
648                 return DCCP_SANE_RTT_MAX;
649         }
650
651         return delta;
652 }
653
654 EXPORT_SYMBOL_GPL(dccp_sample_rtt);