[DCCP] CCID: Improve CCID infrastructure
[linux-3.10.git] / net / dccp / input.c
1 /*
2  *  net/dccp/input.c
3  * 
4  *  An implementation of the DCCP protocol
5  *  Arnaldo Carvalho de Melo <acme@conectiva.com.br>
6  *
7  *      This program is free software; you can redistribute it and/or
8  *      modify it under the terms of the GNU General Public License
9  *      as published by the Free Software Foundation; either version
10  *      2 of the License, or (at your option) any later version.
11  */
12
13 #include <linux/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_v4_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 inline void dccp_event_ack_recv(struct sock *sk, struct sk_buff *skb)
60 {
61         struct dccp_sock *dp = dccp_sk(sk);
62
63         if (dp->dccps_options.dccpo_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 inline int __dccp_rcv_established(struct sock *sk, struct sk_buff *skb,
155                                          const struct dccp_hdr *dh,
156                                          const unsigned len)
157 {
158         struct dccp_sock *dp = dccp_sk(sk);
159
160         switch (dccp_hdr(skb)->dccph_type) {
161         case DCCP_PKT_DATAACK:
162         case DCCP_PKT_DATA:
163                 /*
164                  * FIXME: check if sk_receive_queue is full, schedule DATA_DROPPED
165                  * option if it is.
166                  */
167                 __skb_pull(skb, dh->dccph_doff * 4);
168                 __skb_queue_tail(&sk->sk_receive_queue, skb);
169                 skb_set_owner_r(skb, sk);
170                 sk->sk_data_ready(sk, 0);
171                 return 0;
172         case DCCP_PKT_ACK:
173                 goto discard;
174         case DCCP_PKT_RESET:
175                 /*
176                  *  Step 9: Process Reset
177                  *      If P.type == Reset,
178                  *              Tear down connection
179                  *              S.state := TIMEWAIT
180                  *              Set TIMEWAIT timer
181                  *              Drop packet and return
182                 */
183                 dccp_fin(sk, skb);
184                 dccp_time_wait(sk, DCCP_TIME_WAIT, 0);
185                 return 0;
186         case DCCP_PKT_CLOSEREQ:
187                 dccp_rcv_closereq(sk, skb);
188                 goto discard;
189         case DCCP_PKT_CLOSE:
190                 dccp_rcv_close(sk, skb);
191                 return 0;
192         case DCCP_PKT_REQUEST:
193                 /* Step 7 
194                  *   or (S.is_server and P.type == Response)
195                  *   or (S.is_client and P.type == Request)
196                  *   or (S.state >= OPEN and P.type == Request
197                  *      and P.seqno >= S.OSR)
198                  *    or (S.state >= OPEN and P.type == Response
199                  *      and P.seqno >= S.OSR)
200                  *    or (S.state == RESPOND and P.type == Data),
201                  *  Send Sync packet acknowledging P.seqno
202                  *  Drop packet and return
203                  */
204                 if (dp->dccps_role != DCCP_ROLE_LISTEN)
205                         goto send_sync;
206                 goto check_seq;
207         case DCCP_PKT_RESPONSE:
208                 if (dp->dccps_role != DCCP_ROLE_CLIENT)
209                         goto send_sync;
210 check_seq:
211                 if (!before48(DCCP_SKB_CB(skb)->dccpd_seq, dp->dccps_osr)) {
212 send_sync:
213                         dccp_send_sync(sk, DCCP_SKB_CB(skb)->dccpd_seq,
214                                        DCCP_PKT_SYNC);
215                 }
216                 break;
217         case DCCP_PKT_SYNC:
218                 dccp_send_sync(sk, DCCP_SKB_CB(skb)->dccpd_seq,
219                                DCCP_PKT_SYNCACK);
220                 /*
221                  * From the draft:
222                  *
223                  * As with DCCP-Ack packets, DCCP-Sync and DCCP-SyncAck packets
224                  * MAY have non-zero-length application data areas, whose
225                  * contents * receivers MUST ignore.
226                  */
227                 goto discard;
228         }
229
230         DCCP_INC_STATS_BH(DCCP_MIB_INERRS);
231 discard:
232         __kfree_skb(skb);
233         return 0;
234 }
235
236 int dccp_rcv_established(struct sock *sk, struct sk_buff *skb,
237                          const struct dccp_hdr *dh, const unsigned len)
238 {
239         struct dccp_sock *dp = dccp_sk(sk);
240
241         if (dccp_check_seqno(sk, skb))
242                 goto discard;
243
244         if (dccp_parse_options(sk, skb))
245                 goto discard;
246
247         if (DCCP_SKB_CB(skb)->dccpd_ack_seq != DCCP_PKT_WITHOUT_ACK_SEQ)
248                 dccp_event_ack_recv(sk, skb);
249
250         if (dp->dccps_options.dccpo_send_ack_vector &&
251             dccp_ackvec_add(dp->dccps_hc_rx_ackvec, sk,
252                             DCCP_SKB_CB(skb)->dccpd_seq,
253                             DCCP_ACKVEC_STATE_RECEIVED))
254                 goto discard;
255
256         ccid_hc_rx_packet_recv(dp->dccps_hc_rx_ccid, sk, skb);
257         ccid_hc_tx_packet_recv(dp->dccps_hc_tx_ccid, sk, skb);
258
259         return __dccp_rcv_established(sk, skb, dh, len);
260 discard:
261         __kfree_skb(skb);
262         return 0;
263 }
264
265 EXPORT_SYMBOL_GPL(dccp_rcv_established);
266
267 static int dccp_rcv_request_sent_state_process(struct sock *sk,
268                                                struct sk_buff *skb,
269                                                const struct dccp_hdr *dh,
270                                                const unsigned len)
271 {
272         /* 
273          *  Step 4: Prepare sequence numbers in REQUEST
274          *     If S.state == REQUEST,
275          *        If (P.type == Response or P.type == Reset)
276          *              and S.AWL <= P.ackno <= S.AWH,
277          *           / * Set sequence number variables corresponding to the
278          *              other endpoint, so P will pass the tests in Step 6 * /
279          *           Set S.GSR, S.ISR, S.SWL, S.SWH
280          *           / * Response processing continues in Step 10; Reset
281          *              processing continues in Step 9 * /
282         */
283         if (dh->dccph_type == DCCP_PKT_RESPONSE) {
284                 const struct inet_connection_sock *icsk = inet_csk(sk);
285                 struct dccp_sock *dp = dccp_sk(sk);
286
287                 /* Stop the REQUEST timer */
288                 inet_csk_clear_xmit_timer(sk, ICSK_TIME_RETRANS);
289                 BUG_TRAP(sk->sk_send_head != NULL);
290                 __kfree_skb(sk->sk_send_head);
291                 sk->sk_send_head = NULL;
292
293                 if (!between48(DCCP_SKB_CB(skb)->dccpd_ack_seq,
294                                dp->dccps_awl, dp->dccps_awh)) {
295                         dccp_pr_debug("invalid ackno: S.AWL=%llu, "
296                                       "P.ackno=%llu, S.AWH=%llu \n",
297                                       (unsigned long long)dp->dccps_awl,
298                            (unsigned long long)DCCP_SKB_CB(skb)->dccpd_ack_seq,
299                                       (unsigned long long)dp->dccps_awh);
300                         goto out_invalid_packet;
301                 }
302
303                 if (dccp_parse_options(sk, skb))
304                         goto out_invalid_packet;
305
306                 if (dp->dccps_options.dccpo_send_ack_vector &&
307                     dccp_ackvec_add(dp->dccps_hc_rx_ackvec, sk,
308                                     DCCP_SKB_CB(skb)->dccpd_seq,
309                                     DCCP_ACKVEC_STATE_RECEIVED))
310                         goto out_invalid_packet; /* FIXME: change error code */
311
312                 dp->dccps_isr = DCCP_SKB_CB(skb)->dccpd_seq;
313                 dccp_update_gsr(sk, dp->dccps_isr);
314                 /*
315                  * SWL and AWL are initially adjusted so that they are not less than
316                  * the initial Sequence Numbers received and sent, respectively:
317                  *      SWL := max(GSR + 1 - floor(W/4), ISR),
318                  *      AWL := max(GSS - W' + 1, ISS).
319                  * These adjustments MUST be applied only at the beginning of the
320                  * connection.
321                  *
322                  * AWL was adjusted in dccp_v4_connect -acme
323                  */
324                 dccp_set_seqno(&dp->dccps_swl,
325                                max48(dp->dccps_swl, dp->dccps_isr));
326
327                 dccp_sync_mss(sk, icsk->icsk_pmtu_cookie);
328
329                 /*
330                  *    Step 10: Process REQUEST state (second part)
331                  *       If S.state == REQUEST,
332                  *        / * If we get here, P is a valid Response from the
333                  *            server (see Step 4), and we should move to
334                  *            PARTOPEN state. PARTOPEN means send an Ack,
335                  *            don't send Data packets, retransmit Acks
336                  *            periodically, and always include any Init Cookie
337                  *            from the Response * /
338                  *        S.state := PARTOPEN
339                  *        Set PARTOPEN timer
340                  *        Continue with S.state == PARTOPEN
341                  *        / * Step 12 will send the Ack completing the
342                  *            three-way handshake * /
343                  */
344                 dccp_set_state(sk, DCCP_PARTOPEN);
345
346                 /* Make sure socket is routed, for correct metrics. */
347                 icsk->icsk_af_ops->rebuild_header(sk);
348
349                 if (!sock_flag(sk, SOCK_DEAD)) {
350                         sk->sk_state_change(sk);
351                         sk_wake_async(sk, 0, POLL_OUT);
352                 }
353
354                 if (sk->sk_write_pending || icsk->icsk_ack.pingpong ||
355                     icsk->icsk_accept_queue.rskq_defer_accept) {
356                         /* Save one ACK. Data will be ready after
357                          * several ticks, if write_pending is set.
358                          *
359                          * It may be deleted, but with this feature tcpdumps
360                          * look so _wonderfully_ clever, that I was not able
361                          * to stand against the temptation 8)     --ANK
362                          */
363                         /*
364                          * OK, in DCCP we can as well do a similar trick, its
365                          * even in the draft, but there is no need for us to
366                          * schedule an ack here, as dccp_sendmsg does this for
367                          * us, also stated in the draft. -acme
368                          */
369                         __kfree_skb(skb);
370                         return 0;
371                 } 
372                 dccp_send_ack(sk);
373                 return -1;
374         }
375
376 out_invalid_packet:
377         /* dccp_v4_do_rcv will send a reset */
378         DCCP_SKB_CB(skb)->dccpd_reset_code = DCCP_RESET_CODE_PACKET_ERROR;
379         return 1; 
380 }
381
382 static int dccp_rcv_respond_partopen_state_process(struct sock *sk,
383                                                    struct sk_buff *skb,
384                                                    const struct dccp_hdr *dh,
385                                                    const unsigned len)
386 {
387         int queued = 0;
388
389         switch (dh->dccph_type) {
390         case DCCP_PKT_RESET:
391                 inet_csk_clear_xmit_timer(sk, ICSK_TIME_DACK);
392                 break;
393         case DCCP_PKT_DATA:
394                 if (sk->sk_state == DCCP_RESPOND)
395                         break;
396         case DCCP_PKT_DATAACK:
397         case DCCP_PKT_ACK:
398                 /*
399                  * FIXME: we should be reseting the PARTOPEN (DELACK) timer
400                  * here but only if we haven't used the DELACK timer for
401                  * something else, like sending a delayed ack for a TIMESTAMP
402                  * echo, etc, for now were not clearing it, sending an extra
403                  * ACK when there is nothing else to do in DELACK is not a big
404                  * deal after all.
405                  */
406
407                 /* Stop the PARTOPEN timer */
408                 if (sk->sk_state == DCCP_PARTOPEN)
409                         inet_csk_clear_xmit_timer(sk, ICSK_TIME_DACK);
410
411                 dccp_sk(sk)->dccps_osr = DCCP_SKB_CB(skb)->dccpd_seq;
412                 dccp_set_state(sk, DCCP_OPEN);
413
414                 if (dh->dccph_type == DCCP_PKT_DATAACK ||
415                     dh->dccph_type == DCCP_PKT_DATA) {
416                         __dccp_rcv_established(sk, skb, dh, len);
417                         queued = 1; /* packet was queued
418                                        (by __dccp_rcv_established) */
419                 }
420                 break;
421         }
422
423         return queued;
424 }
425
426 int dccp_rcv_state_process(struct sock *sk, struct sk_buff *skb,
427                            struct dccp_hdr *dh, unsigned len)
428 {
429         struct dccp_sock *dp = dccp_sk(sk);
430         struct dccp_skb_cb *dcb = DCCP_SKB_CB(skb);
431         const int old_state = sk->sk_state;
432         int queued = 0;
433
434         /*
435          *  Step 3: Process LISTEN state
436          *      (Continuing from dccp_v4_do_rcv and dccp_v6_do_rcv)
437          *
438          *     If S.state == LISTEN,
439          *        If P.type == Request or P contains a valid Init Cookie
440          *              option,
441          *           * Must scan the packet's options to check for an Init
442          *              Cookie.  Only the Init Cookie is processed here,
443          *              however; other options are processed in Step 8.  This
444          *              scan need only be performed if the endpoint uses Init
445          *              Cookies *
446          *           * Generate a new socket and switch to that socket *
447          *           Set S := new socket for this port pair
448          *           S.state = RESPOND
449          *           Choose S.ISS (initial seqno) or set from Init Cookie
450          *           Set S.ISR, S.GSR, S.SWL, S.SWH from packet or Init Cookie
451          *           Continue with S.state == RESPOND
452          *           * A Response packet will be generated in Step 11 *
453          *        Otherwise,
454          *           Generate Reset(No Connection) unless P.type == Reset
455          *           Drop packet and return
456          *
457          * NOTE: the check for the packet types is done in
458          *       dccp_rcv_state_process
459          */
460         if (sk->sk_state == DCCP_LISTEN) {
461                 if (dh->dccph_type == DCCP_PKT_REQUEST) {
462                         if (inet_csk(sk)->icsk_af_ops->conn_request(sk,
463                                                                     skb) < 0)
464                                 return 1;
465
466                         /* FIXME: do congestion control initialization */
467                         goto discard;
468                 }
469                 if (dh->dccph_type == DCCP_PKT_RESET)
470                         goto discard;
471
472                 /* Caller (dccp_v4_do_rcv) will send Reset */
473                 dcb->dccpd_reset_code = DCCP_RESET_CODE_NO_CONNECTION;
474                 return 1;
475         }
476
477         if (sk->sk_state != DCCP_REQUESTING) {
478                 if (dccp_check_seqno(sk, skb))
479                         goto discard;
480
481                 /*
482                  * Step 8: Process options and mark acknowledgeable
483                  */
484                 if (dccp_parse_options(sk, skb))
485                         goto discard;
486
487                 if (dcb->dccpd_ack_seq != DCCP_PKT_WITHOUT_ACK_SEQ)
488                         dccp_event_ack_recv(sk, skb);
489
490                 if (dp->dccps_options.dccpo_send_ack_vector &&
491                     dccp_ackvec_add(dp->dccps_hc_rx_ackvec, sk,
492                                     DCCP_SKB_CB(skb)->dccpd_seq,
493                                     DCCP_ACKVEC_STATE_RECEIVED))
494                         goto discard;
495
496                 ccid_hc_rx_packet_recv(dp->dccps_hc_rx_ccid, sk, skb);
497                 ccid_hc_tx_packet_recv(dp->dccps_hc_tx_ccid, sk, skb);
498         }
499
500         /*
501          *  Step 9: Process Reset
502          *      If P.type == Reset,
503          *              Tear down connection
504          *              S.state := TIMEWAIT
505          *              Set TIMEWAIT timer
506          *              Drop packet and return
507         */
508         if (dh->dccph_type == DCCP_PKT_RESET) {
509                 /*
510                  * Queue the equivalent of TCP fin so that dccp_recvmsg
511                  * exits the loop
512                  */
513                 dccp_fin(sk, skb);
514                 dccp_time_wait(sk, DCCP_TIME_WAIT, 0);
515                 return 0;
516                 /*
517                  *   Step 7: Check for unexpected packet types
518                  *      If (S.is_server and P.type == CloseReq)
519                  *          or (S.is_server and P.type == Response)
520                  *          or (S.is_client and P.type == Request)
521                  *          or (S.state == RESPOND and P.type == Data),
522                  *        Send Sync packet acknowledging P.seqno
523                  *        Drop packet and return
524                  */
525         } else if ((dp->dccps_role != DCCP_ROLE_CLIENT &&
526                     (dh->dccph_type == DCCP_PKT_RESPONSE ||
527                      dh->dccph_type == DCCP_PKT_CLOSEREQ)) ||
528                     (dp->dccps_role == DCCP_ROLE_CLIENT &&
529                      dh->dccph_type == DCCP_PKT_REQUEST) ||
530                     (sk->sk_state == DCCP_RESPOND &&
531                      dh->dccph_type == DCCP_PKT_DATA)) {
532                 dccp_send_sync(sk, dcb->dccpd_seq, DCCP_PKT_SYNC);
533                 goto discard;
534         } else if (dh->dccph_type == DCCP_PKT_CLOSEREQ) {
535                 dccp_rcv_closereq(sk, skb);
536                 goto discard;
537         } else if (dh->dccph_type == DCCP_PKT_CLOSE) {
538                 dccp_rcv_close(sk, skb);
539                 return 0;
540         }
541
542         if (unlikely(dh->dccph_type == DCCP_PKT_SYNC)) {
543                 dccp_send_sync(sk, dcb->dccpd_seq, DCCP_PKT_SYNCACK);
544                 goto discard;
545         }
546
547         switch (sk->sk_state) {
548         case DCCP_CLOSED:
549                 dcb->dccpd_reset_code = DCCP_RESET_CODE_NO_CONNECTION;
550                 return 1;
551
552         case DCCP_REQUESTING:
553                 /* FIXME: do congestion control initialization */
554
555                 queued = dccp_rcv_request_sent_state_process(sk, skb, dh, len);
556                 if (queued >= 0)
557                         return queued;
558
559                 __kfree_skb(skb);
560                 return 0;
561
562         case DCCP_RESPOND:
563         case DCCP_PARTOPEN:
564                 queued = dccp_rcv_respond_partopen_state_process(sk, skb,
565                                                                  dh, len);
566                 break;
567         }
568
569         if (dh->dccph_type == DCCP_PKT_ACK ||
570             dh->dccph_type == DCCP_PKT_DATAACK) {
571                 switch (old_state) {
572                 case DCCP_PARTOPEN:
573                         sk->sk_state_change(sk);
574                         sk_wake_async(sk, 0, POLL_OUT);
575                         break;
576                 }
577         }
578
579         if (!queued) { 
580 discard:
581                 __kfree_skb(skb);
582         }
583         return 0;
584 }
585
586 EXPORT_SYMBOL_GPL(dccp_rcv_state_process);