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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/config.h>
14 #include <linux/dccp.h>
15 #include <linux/skbuff.h>
16
17 #include <net/sock.h>
18
19 #include "ackvec.h"
20 #include "ccid.h"
21 #include "dccp.h"
22
23 static void dccp_fin(struct sock *sk, struct sk_buff *skb)
24 {
25         sk->sk_shutdown |= RCV_SHUTDOWN;
26         sock_set_flag(sk, SOCK_DONE);
27         __skb_pull(skb, dccp_hdr(skb)->dccph_doff * 4);
28         __skb_queue_tail(&sk->sk_receive_queue, skb);
29         skb_set_owner_r(skb, sk);
30         sk->sk_data_ready(sk, 0);
31 }
32
33 static void dccp_rcv_close(struct sock *sk, struct sk_buff *skb)
34 {
35         dccp_send_reset(sk, DCCP_RESET_CODE_CLOSED);
36         dccp_fin(sk, skb);
37         dccp_set_state(sk, DCCP_CLOSED);
38         sk_wake_async(sk, 1, POLL_HUP);
39 }
40
41 static void dccp_rcv_closereq(struct sock *sk, struct sk_buff *skb)
42 {
43         /*
44          *   Step 7: Check for unexpected packet types
45          *      If (S.is_server and P.type == CloseReq)
46          *        Send Sync packet acknowledging P.seqno
47          *        Drop packet and return
48          */
49         if (dccp_sk(sk)->dccps_role != DCCP_ROLE_CLIENT) {
50                 dccp_send_sync(sk, DCCP_SKB_CB(skb)->dccpd_seq, DCCP_PKT_SYNC);
51                 return;
52         }
53
54         if (sk->sk_state != DCCP_CLOSING)
55                 dccp_set_state(sk, DCCP_CLOSING);
56         dccp_send_close(sk, 0);
57 }
58
59 static void dccp_event_ack_recv(struct sock *sk, struct sk_buff *skb)
60 {
61         struct dccp_sock *dp = dccp_sk(sk);
62
63         if (dccp_msk(sk)->dccpms_send_ack_vector)
64                 dccp_ackvec_check_rcv_ackno(dp->dccps_hc_rx_ackvec, sk,
65                                             DCCP_SKB_CB(skb)->dccpd_ack_seq);
66 }
67
68 static int dccp_check_seqno(struct sock *sk, struct sk_buff *skb)
69 {
70         const struct dccp_hdr *dh = dccp_hdr(skb);
71         struct dccp_sock *dp = dccp_sk(sk);
72         u64 lswl, lawl;
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(DCCP_SKB_CB(skb)->dccpd_ack_seq,
89                               dp->dccps_awl, dp->dccps_awh) &&
90                     !before48(DCCP_SKB_CB(skb)->dccpd_seq, dp->dccps_swl))
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                 LIMIT_NETDEBUG(KERN_WARNING "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",
136                                dccp_packet_name(dh->dccph_type),
137                                (unsigned long long) lswl,
138                                (unsigned long long)
139                                DCCP_SKB_CB(skb)->dccpd_seq,
140                                (unsigned long long) dp->dccps_swh,
141                                (DCCP_SKB_CB(skb)->dccpd_ack_seq ==
142                                 DCCP_PKT_WITHOUT_ACK_SEQ) ? "doesn't exist" : "exists",
143                                (unsigned long long) lawl,
144                                (unsigned long long)
145                                DCCP_SKB_CB(skb)->dccpd_ack_seq,
146                                (unsigned long long) dp->dccps_awh);
147                 dccp_send_sync(sk, DCCP_SKB_CB(skb)->dccpd_seq, DCCP_PKT_SYNC);
148                 return -1;
149         }
150
151         return 0;
152 }
153
154 static int __dccp_rcv_established(struct sock *sk, struct sk_buff *skb,
155                                   const struct dccp_hdr *dh, const unsigned len)
156 {
157         struct dccp_sock *dp = dccp_sk(sk);
158
159         switch (dccp_hdr(skb)->dccph_type) {
160         case DCCP_PKT_DATAACK:
161         case DCCP_PKT_DATA:
162                 /*
163                  * FIXME: check if sk_receive_queue is full, schedule DATA_DROPPED
164                  * option if it is.
165                  */
166                 __skb_pull(skb, dh->dccph_doff * 4);
167                 __skb_queue_tail(&sk->sk_receive_queue, skb);
168                 skb_set_owner_r(skb, sk);
169                 sk->sk_data_ready(sk, 0);
170                 return 0;
171         case DCCP_PKT_ACK:
172                 goto discard;
173         case DCCP_PKT_RESET:
174                 /*
175                  *  Step 9: Process Reset
176                  *      If P.type == Reset,
177                  *              Tear down connection
178                  *              S.state := TIMEWAIT
179                  *              Set TIMEWAIT timer
180                  *              Drop packet and return
181                 */
182                 dccp_fin(sk, skb);
183                 dccp_time_wait(sk, DCCP_TIME_WAIT, 0);
184                 return 0;
185         case DCCP_PKT_CLOSEREQ:
186                 dccp_rcv_closereq(sk, skb);
187                 goto discard;
188         case DCCP_PKT_CLOSE:
189                 dccp_rcv_close(sk, skb);
190                 return 0;
191         case DCCP_PKT_REQUEST:
192                 /* Step 7 
193                  *   or (S.is_server and P.type == Response)
194                  *   or (S.is_client and P.type == Request)
195                  *   or (S.state >= OPEN and P.type == Request
196                  *      and P.seqno >= S.OSR)
197                  *    or (S.state >= OPEN and P.type == Response
198                  *      and P.seqno >= S.OSR)
199                  *    or (S.state == RESPOND and P.type == Data),
200                  *  Send Sync packet acknowledging P.seqno
201                  *  Drop packet and return
202                  */
203                 if (dp->dccps_role != DCCP_ROLE_LISTEN)
204                         goto send_sync;
205                 goto check_seq;
206         case DCCP_PKT_RESPONSE:
207                 if (dp->dccps_role != DCCP_ROLE_CLIENT)
208                         goto send_sync;
209 check_seq:
210                 if (!before48(DCCP_SKB_CB(skb)->dccpd_seq, dp->dccps_osr)) {
211 send_sync:
212                         dccp_send_sync(sk, DCCP_SKB_CB(skb)->dccpd_seq,
213                                        DCCP_PKT_SYNC);
214                 }
215                 break;
216         case DCCP_PKT_SYNC:
217                 dccp_send_sync(sk, DCCP_SKB_CB(skb)->dccpd_seq,
218                                DCCP_PKT_SYNCACK);
219                 /*
220                  * From the draft:
221                  *
222                  * As with DCCP-Ack packets, DCCP-Sync and DCCP-SyncAck packets
223                  * MAY have non-zero-length application data areas, whose
224                  * contents * receivers MUST ignore.
225                  */
226                 goto discard;
227         }
228
229         DCCP_INC_STATS_BH(DCCP_MIB_INERRS);
230 discard:
231         __kfree_skb(skb);
232         return 0;
233 }
234
235 int dccp_rcv_established(struct sock *sk, struct sk_buff *skb,
236                          const struct dccp_hdr *dh, const unsigned len)
237 {
238         struct dccp_sock *dp = dccp_sk(sk);
239
240         if (dccp_check_seqno(sk, skb))
241                 goto discard;
242
243         if (dccp_parse_options(sk, skb))
244                 goto discard;
245
246         if (DCCP_SKB_CB(skb)->dccpd_ack_seq != DCCP_PKT_WITHOUT_ACK_SEQ)
247                 dccp_event_ack_recv(sk, skb);
248
249         if (dccp_msk(sk)->dccpms_send_ack_vector &&
250             dccp_ackvec_add(dp->dccps_hc_rx_ackvec, sk,
251                             DCCP_SKB_CB(skb)->dccpd_seq,
252                             DCCP_ACKVEC_STATE_RECEIVED))
253                 goto discard;
254
255         ccid_hc_rx_packet_recv(dp->dccps_hc_rx_ccid, sk, skb);
256         ccid_hc_tx_packet_recv(dp->dccps_hc_tx_ccid, sk, skb);
257
258         return __dccp_rcv_established(sk, skb, dh, len);
259 discard:
260         __kfree_skb(skb);
261         return 0;
262 }
263
264 EXPORT_SYMBOL_GPL(dccp_rcv_established);
265
266 static int dccp_rcv_request_sent_state_process(struct sock *sk,
267                                                struct sk_buff *skb,
268                                                const struct dccp_hdr *dh,
269                                                const unsigned len)
270 {
271         /* 
272          *  Step 4: Prepare sequence numbers in REQUEST
273          *     If S.state == REQUEST,
274          *        If (P.type == Response or P.type == Reset)
275          *              and S.AWL <= P.ackno <= S.AWH,
276          *           / * Set sequence number variables corresponding to the
277          *              other endpoint, so P will pass the tests in Step 6 * /
278          *           Set S.GSR, S.ISR, S.SWL, S.SWH
279          *           / * Response processing continues in Step 10; Reset
280          *              processing continues in Step 9 * /
281         */
282         if (dh->dccph_type == DCCP_PKT_RESPONSE) {
283                 const struct inet_connection_sock *icsk = inet_csk(sk);
284                 struct dccp_sock *dp = dccp_sk(sk);
285
286                 /* Stop the REQUEST timer */
287                 inet_csk_clear_xmit_timer(sk, ICSK_TIME_RETRANS);
288                 BUG_TRAP(sk->sk_send_head != NULL);
289                 __kfree_skb(sk->sk_send_head);
290                 sk->sk_send_head = NULL;
291
292                 if (!between48(DCCP_SKB_CB(skb)->dccpd_ack_seq,
293                                dp->dccps_awl, dp->dccps_awh)) {
294                         dccp_pr_debug("invalid ackno: S.AWL=%llu, "
295                                       "P.ackno=%llu, S.AWH=%llu \n",
296                                       (unsigned long long)dp->dccps_awl,
297                            (unsigned long long)DCCP_SKB_CB(skb)->dccpd_ack_seq,
298                                       (unsigned long long)dp->dccps_awh);
299                         goto out_invalid_packet;
300                 }
301
302                 if (dccp_parse_options(sk, skb))
303                         goto out_invalid_packet;
304
305                 if (dccp_msk(sk)->dccpms_send_ack_vector &&
306                     dccp_ackvec_add(dp->dccps_hc_rx_ackvec, sk,
307                                     DCCP_SKB_CB(skb)->dccpd_seq,
308                                     DCCP_ACKVEC_STATE_RECEIVED))
309                         goto out_invalid_packet; /* FIXME: change error code */
310
311                 dp->dccps_isr = DCCP_SKB_CB(skb)->dccpd_seq;
312                 dccp_update_gsr(sk, dp->dccps_isr);
313                 /*
314                  * SWL and AWL are initially adjusted so that they are not less than
315                  * the initial Sequence Numbers received and sent, respectively:
316                  *      SWL := max(GSR + 1 - floor(W/4), ISR),
317                  *      AWL := max(GSS - W' + 1, ISS).
318                  * These adjustments MUST be applied only at the beginning of the
319                  * connection.
320                  *
321                  * AWL was adjusted in dccp_v4_connect -acme
322                  */
323                 dccp_set_seqno(&dp->dccps_swl,
324                                max48(dp->dccps_swl, dp->dccps_isr));
325
326                 dccp_sync_mss(sk, icsk->icsk_pmtu_cookie);
327
328                 /*
329                  *    Step 10: Process REQUEST state (second part)
330                  *       If S.state == REQUEST,
331                  *        / * If we get here, P is a valid Response from the
332                  *            server (see Step 4), and we should move to
333                  *            PARTOPEN state. PARTOPEN means send an Ack,
334                  *            don't send Data packets, retransmit Acks
335                  *            periodically, and always include any Init Cookie
336                  *            from the Response * /
337                  *        S.state := PARTOPEN
338                  *        Set PARTOPEN timer
339                  *        Continue with S.state == PARTOPEN
340                  *        / * Step 12 will send the Ack completing the
341                  *            three-way handshake * /
342                  */
343                 dccp_set_state(sk, DCCP_PARTOPEN);
344
345                 /* Make sure socket is routed, for correct metrics. */
346                 icsk->icsk_af_ops->rebuild_header(sk);
347
348                 if (!sock_flag(sk, SOCK_DEAD)) {
349                         sk->sk_state_change(sk);
350                         sk_wake_async(sk, 0, POLL_OUT);
351                 }
352
353                 if (sk->sk_write_pending || icsk->icsk_ack.pingpong ||
354                     icsk->icsk_accept_queue.rskq_defer_accept) {
355                         /* Save one ACK. Data will be ready after
356                          * several ticks, if write_pending is set.
357                          *
358                          * It may be deleted, but with this feature tcpdumps
359                          * look so _wonderfully_ clever, that I was not able
360                          * to stand against the temptation 8)     --ANK
361                          */
362                         /*
363                          * OK, in DCCP we can as well do a similar trick, its
364                          * even in the draft, but there is no need for us to
365                          * schedule an ack here, as dccp_sendmsg does this for
366                          * us, also stated in the draft. -acme
367                          */
368                         __kfree_skb(skb);
369                         return 0;
370                 } 
371                 dccp_send_ack(sk);
372                 return -1;
373         }
374
375 out_invalid_packet:
376         /* dccp_v4_do_rcv will send a reset */
377         DCCP_SKB_CB(skb)->dccpd_reset_code = DCCP_RESET_CODE_PACKET_ERROR;
378         return 1; 
379 }
380
381 static int dccp_rcv_respond_partopen_state_process(struct sock *sk,
382                                                    struct sk_buff *skb,
383                                                    const struct dccp_hdr *dh,
384                                                    const unsigned len)
385 {
386         int queued = 0;
387
388         switch (dh->dccph_type) {
389         case DCCP_PKT_RESET:
390                 inet_csk_clear_xmit_timer(sk, ICSK_TIME_DACK);
391                 break;
392         case DCCP_PKT_DATA:
393                 if (sk->sk_state == DCCP_RESPOND)
394                         break;
395         case DCCP_PKT_DATAACK:
396         case DCCP_PKT_ACK:
397                 /*
398                  * FIXME: we should be reseting the PARTOPEN (DELACK) timer
399                  * here but only if we haven't used the DELACK timer for
400                  * something else, like sending a delayed ack for a TIMESTAMP
401                  * echo, etc, for now were not clearing it, sending an extra
402                  * ACK when there is nothing else to do in DELACK is not a big
403                  * deal after all.
404                  */
405
406                 /* Stop the PARTOPEN timer */
407                 if (sk->sk_state == DCCP_PARTOPEN)
408                         inet_csk_clear_xmit_timer(sk, ICSK_TIME_DACK);
409
410                 dccp_sk(sk)->dccps_osr = DCCP_SKB_CB(skb)->dccpd_seq;
411                 dccp_set_state(sk, DCCP_OPEN);
412
413                 if (dh->dccph_type == DCCP_PKT_DATAACK ||
414                     dh->dccph_type == DCCP_PKT_DATA) {
415                         __dccp_rcv_established(sk, skb, dh, len);
416                         queued = 1; /* packet was queued
417                                        (by __dccp_rcv_established) */
418                 }
419                 break;
420         }
421
422         return queued;
423 }
424
425 int dccp_rcv_state_process(struct sock *sk, struct sk_buff *skb,
426                            struct dccp_hdr *dh, unsigned len)
427 {
428         struct dccp_sock *dp = dccp_sk(sk);
429         struct dccp_skb_cb *dcb = DCCP_SKB_CB(skb);
430         const int old_state = sk->sk_state;
431         int queued = 0;
432
433         /*
434          *  Step 3: Process LISTEN state
435          *      (Continuing from dccp_v4_do_rcv and dccp_v6_do_rcv)
436          *
437          *     If S.state == LISTEN,
438          *        If P.type == Request or P contains a valid Init Cookie
439          *              option,
440          *           * Must scan the packet's options to check for an Init
441          *              Cookie.  Only the Init Cookie is processed here,
442          *              however; other options are processed in Step 8.  This
443          *              scan need only be performed if the endpoint uses Init
444          *              Cookies *
445          *           * Generate a new socket and switch to that socket *
446          *           Set S := new socket for this port pair
447          *           S.state = RESPOND
448          *           Choose S.ISS (initial seqno) or set from Init Cookie
449          *           Set S.ISR, S.GSR, S.SWL, S.SWH from packet or Init Cookie
450          *           Continue with S.state == RESPOND
451          *           * A Response packet will be generated in Step 11 *
452          *        Otherwise,
453          *           Generate Reset(No Connection) unless P.type == Reset
454          *           Drop packet and return
455          *
456          * NOTE: the check for the packet types is done in
457          *       dccp_rcv_state_process
458          */
459         if (sk->sk_state == DCCP_LISTEN) {
460                 if (dh->dccph_type == DCCP_PKT_REQUEST) {
461                         if (inet_csk(sk)->icsk_af_ops->conn_request(sk,
462                                                                     skb) < 0)
463                                 return 1;
464
465                         /* FIXME: do congestion control initialization */
466                         goto discard;
467                 }
468                 if (dh->dccph_type == DCCP_PKT_RESET)
469                         goto discard;
470
471                 /* Caller (dccp_v4_do_rcv) will send Reset */
472                 dcb->dccpd_reset_code = DCCP_RESET_CODE_NO_CONNECTION;
473                 return 1;
474         }
475
476         if (sk->sk_state != DCCP_REQUESTING) {
477                 if (dccp_check_seqno(sk, skb))
478                         goto discard;
479
480                 /*
481                  * Step 8: Process options and mark acknowledgeable
482                  */
483                 if (dccp_parse_options(sk, skb))
484                         goto discard;
485
486                 if (dcb->dccpd_ack_seq != DCCP_PKT_WITHOUT_ACK_SEQ)
487                         dccp_event_ack_recv(sk, skb);
488
489                 if (dccp_msk(sk)->dccpms_send_ack_vector &&
490                     dccp_ackvec_add(dp->dccps_hc_rx_ackvec, sk,
491                                     DCCP_SKB_CB(skb)->dccpd_seq,
492                                     DCCP_ACKVEC_STATE_RECEIVED))
493                         goto discard;
494
495                 ccid_hc_rx_packet_recv(dp->dccps_hc_rx_ccid, sk, skb);
496                 ccid_hc_tx_packet_recv(dp->dccps_hc_tx_ccid, sk, skb);
497         }
498
499         /*
500          *  Step 9: Process Reset
501          *      If P.type == Reset,
502          *              Tear down connection
503          *              S.state := TIMEWAIT
504          *              Set TIMEWAIT timer
505          *              Drop packet and return
506         */
507         if (dh->dccph_type == DCCP_PKT_RESET) {
508                 /*
509                  * Queue the equivalent of TCP fin so that dccp_recvmsg
510                  * exits the loop
511                  */
512                 dccp_fin(sk, skb);
513                 dccp_time_wait(sk, DCCP_TIME_WAIT, 0);
514                 return 0;
515                 /*
516                  *   Step 7: Check for unexpected packet types
517                  *      If (S.is_server and P.type == CloseReq)
518                  *          or (S.is_server and P.type == Response)
519                  *          or (S.is_client and P.type == Request)
520                  *          or (S.state == RESPOND and P.type == Data),
521                  *        Send Sync packet acknowledging P.seqno
522                  *        Drop packet and return
523                  */
524         } else if ((dp->dccps_role != DCCP_ROLE_CLIENT &&
525                     (dh->dccph_type == DCCP_PKT_RESPONSE ||
526                      dh->dccph_type == DCCP_PKT_CLOSEREQ)) ||
527                     (dp->dccps_role == DCCP_ROLE_CLIENT &&
528                      dh->dccph_type == DCCP_PKT_REQUEST) ||
529                     (sk->sk_state == DCCP_RESPOND &&
530                      dh->dccph_type == DCCP_PKT_DATA)) {
531                 dccp_send_sync(sk, dcb->dccpd_seq, DCCP_PKT_SYNC);
532                 goto discard;
533         } else if (dh->dccph_type == DCCP_PKT_CLOSEREQ) {
534                 dccp_rcv_closereq(sk, skb);
535                 goto discard;
536         } else if (dh->dccph_type == DCCP_PKT_CLOSE) {
537                 dccp_rcv_close(sk, skb);
538                 return 0;
539         }
540
541         if (unlikely(dh->dccph_type == DCCP_PKT_SYNC)) {
542                 dccp_send_sync(sk, dcb->dccpd_seq, DCCP_PKT_SYNCACK);
543                 goto discard;
544         }
545
546         switch (sk->sk_state) {
547         case DCCP_CLOSED:
548                 dcb->dccpd_reset_code = DCCP_RESET_CODE_NO_CONNECTION;
549                 return 1;
550
551         case DCCP_REQUESTING:
552                 /* FIXME: do congestion control initialization */
553
554                 queued = dccp_rcv_request_sent_state_process(sk, skb, dh, len);
555                 if (queued >= 0)
556                         return queued;
557
558                 __kfree_skb(skb);
559                 return 0;
560
561         case DCCP_RESPOND:
562         case DCCP_PARTOPEN:
563                 queued = dccp_rcv_respond_partopen_state_process(sk, skb,
564                                                                  dh, len);
565                 break;
566         }
567
568         if (dh->dccph_type == DCCP_PKT_ACK ||
569             dh->dccph_type == DCCP_PKT_DATAACK) {
570                 switch (old_state) {
571                 case DCCP_PARTOPEN:
572                         sk->sk_state_change(sk);
573                         sk_wake_async(sk, 0, POLL_OUT);
574                         break;
575                 }
576         }
577
578         if (!queued) { 
579 discard:
580                 __kfree_skb(skb);
581         }
582         return 0;
583 }
584
585 EXPORT_SYMBOL_GPL(dccp_rcv_state_process);