dccp: Kill dead code and add static markers.
[linux-2.6.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/dccp.h>
14 #include <linux/skbuff.h>
15 #include <linux/slab.h>
16
17 #include <net/sock.h>
18
19 #include "ackvec.h"
20 #include "ccid.h"
21 #include "dccp.h"
22
23 /* rate-limit for syncs in reply to sequence-invalid packets; RFC 4340, 7.5.4 */
24 int sysctl_dccp_sync_ratelimit  __read_mostly = HZ / 8;
25
26 static void dccp_enqueue_skb(struct sock *sk, struct sk_buff *skb)
27 {
28         __skb_pull(skb, dccp_hdr(skb)->dccph_doff * 4);
29         __skb_queue_tail(&sk->sk_receive_queue, skb);
30         skb_set_owner_r(skb, sk);
31         sk->sk_data_ready(sk, 0);
32 }
33
34 static void dccp_fin(struct sock *sk, struct sk_buff *skb)
35 {
36         /*
37          * On receiving Close/CloseReq, both RD/WR shutdown are performed.
38          * RFC 4340, 8.3 says that we MAY send further Data/DataAcks after
39          * receiving the closing segment, but there is no guarantee that such
40          * data will be processed at all.
41          */
42         sk->sk_shutdown = SHUTDOWN_MASK;
43         sock_set_flag(sk, SOCK_DONE);
44         dccp_enqueue_skb(sk, skb);
45 }
46
47 static int dccp_rcv_close(struct sock *sk, struct sk_buff *skb)
48 {
49         int queued = 0;
50
51         switch (sk->sk_state) {
52         /*
53          * We ignore Close when received in one of the following states:
54          *  - CLOSED            (may be a late or duplicate packet)
55          *  - PASSIVE_CLOSEREQ  (the peer has sent a CloseReq earlier)
56          *  - RESPOND           (already handled by dccp_check_req)
57          */
58         case DCCP_CLOSING:
59                 /*
60                  * Simultaneous-close: receiving a Close after sending one. This
61                  * can happen if both client and server perform active-close and
62                  * will result in an endless ping-pong of crossing and retrans-
63                  * mitted Close packets, which only terminates when one of the
64                  * nodes times out (min. 64 seconds). Quicker convergence can be
65                  * achieved when one of the nodes acts as tie-breaker.
66                  * This is ok as both ends are done with data transfer and each
67                  * end is just waiting for the other to acknowledge termination.
68                  */
69                 if (dccp_sk(sk)->dccps_role != DCCP_ROLE_CLIENT)
70                         break;
71                 /* fall through */
72         case DCCP_REQUESTING:
73         case DCCP_ACTIVE_CLOSEREQ:
74                 dccp_send_reset(sk, DCCP_RESET_CODE_CLOSED);
75                 dccp_done(sk);
76                 break;
77         case DCCP_OPEN:
78         case DCCP_PARTOPEN:
79                 /* Give waiting application a chance to read pending data */
80                 queued = 1;
81                 dccp_fin(sk, skb);
82                 dccp_set_state(sk, DCCP_PASSIVE_CLOSE);
83                 /* fall through */
84         case DCCP_PASSIVE_CLOSE:
85                 /*
86                  * Retransmitted Close: we have already enqueued the first one.
87                  */
88                 sk_wake_async(sk, SOCK_WAKE_WAITD, POLL_HUP);
89         }
90         return queued;
91 }
92
93 static int dccp_rcv_closereq(struct sock *sk, struct sk_buff *skb)
94 {
95         int queued = 0;
96
97         /*
98          *   Step 7: Check for unexpected packet types
99          *      If (S.is_server and P.type == CloseReq)
100          *        Send Sync packet acknowledging P.seqno
101          *        Drop packet and return
102          */
103         if (dccp_sk(sk)->dccps_role != DCCP_ROLE_CLIENT) {
104                 dccp_send_sync(sk, DCCP_SKB_CB(skb)->dccpd_seq, DCCP_PKT_SYNC);
105                 return queued;
106         }
107
108         /* Step 13: process relevant Client states < CLOSEREQ */
109         switch (sk->sk_state) {
110         case DCCP_REQUESTING:
111                 dccp_send_close(sk, 0);
112                 dccp_set_state(sk, DCCP_CLOSING);
113                 break;
114         case DCCP_OPEN:
115         case DCCP_PARTOPEN:
116                 /* Give waiting application a chance to read pending data */
117                 queued = 1;
118                 dccp_fin(sk, skb);
119                 dccp_set_state(sk, DCCP_PASSIVE_CLOSEREQ);
120                 /* fall through */
121         case DCCP_PASSIVE_CLOSEREQ:
122                 sk_wake_async(sk, SOCK_WAKE_WAITD, POLL_HUP);
123         }
124         return queued;
125 }
126
127 static u16 dccp_reset_code_convert(const u8 code)
128 {
129         const u16 error_code[] = {
130         [DCCP_RESET_CODE_CLOSED]             = 0,       /* normal termination */
131         [DCCP_RESET_CODE_UNSPECIFIED]        = 0,       /* nothing known */
132         [DCCP_RESET_CODE_ABORTED]            = ECONNRESET,
133
134         [DCCP_RESET_CODE_NO_CONNECTION]      = ECONNREFUSED,
135         [DCCP_RESET_CODE_CONNECTION_REFUSED] = ECONNREFUSED,
136         [DCCP_RESET_CODE_TOO_BUSY]           = EUSERS,
137         [DCCP_RESET_CODE_AGGRESSION_PENALTY] = EDQUOT,
138
139         [DCCP_RESET_CODE_PACKET_ERROR]       = ENOMSG,
140         [DCCP_RESET_CODE_BAD_INIT_COOKIE]    = EBADR,
141         [DCCP_RESET_CODE_BAD_SERVICE_CODE]   = EBADRQC,
142         [DCCP_RESET_CODE_OPTION_ERROR]       = EILSEQ,
143         [DCCP_RESET_CODE_MANDATORY_ERROR]    = EOPNOTSUPP,
144         };
145
146         return code >= DCCP_MAX_RESET_CODES ? 0 : error_code[code];
147 }
148
149 static void dccp_rcv_reset(struct sock *sk, struct sk_buff *skb)
150 {
151         u16 err = dccp_reset_code_convert(dccp_hdr_reset(skb)->dccph_reset_code);
152
153         sk->sk_err = err;
154
155         /* Queue the equivalent of TCP fin so that dccp_recvmsg exits the loop */
156         dccp_fin(sk, skb);
157
158         if (err && !sock_flag(sk, SOCK_DEAD))
159                 sk_wake_async(sk, SOCK_WAKE_IO, POLL_ERR);
160         dccp_time_wait(sk, DCCP_TIME_WAIT, 0);
161 }
162
163 static void dccp_event_ack_recv(struct sock *sk, struct sk_buff *skb)
164 {
165         struct dccp_sock *dp = dccp_sk(sk);
166
167         if (dp->dccps_hc_rx_ackvec != NULL)
168                 dccp_ackvec_check_rcv_ackno(dp->dccps_hc_rx_ackvec, sk,
169                                             DCCP_SKB_CB(skb)->dccpd_ack_seq);
170 }
171
172 static void dccp_deliver_input_to_ccids(struct sock *sk, struct sk_buff *skb)
173 {
174         const struct dccp_sock *dp = dccp_sk(sk);
175
176         /* Don't deliver to RX CCID when node has shut down read end. */
177         if (!(sk->sk_shutdown & RCV_SHUTDOWN))
178                 ccid_hc_rx_packet_recv(dp->dccps_hc_rx_ccid, sk, skb);
179         /*
180          * Until the TX queue has been drained, we can not honour SHUT_WR, since
181          * we need received feedback as input to adjust congestion control.
182          */
183         if (sk->sk_write_queue.qlen > 0 || !(sk->sk_shutdown & SEND_SHUTDOWN))
184                 ccid_hc_tx_packet_recv(dp->dccps_hc_tx_ccid, sk, skb);
185 }
186
187 static int dccp_check_seqno(struct sock *sk, struct sk_buff *skb)
188 {
189         const struct dccp_hdr *dh = dccp_hdr(skb);
190         struct dccp_sock *dp = dccp_sk(sk);
191         u64 lswl, lawl, seqno = DCCP_SKB_CB(skb)->dccpd_seq,
192                         ackno = DCCP_SKB_CB(skb)->dccpd_ack_seq;
193
194         /*
195          *   Step 5: Prepare sequence numbers for Sync
196          *     If P.type == Sync or P.type == SyncAck,
197          *        If S.AWL <= P.ackno <= S.AWH and P.seqno >= S.SWL,
198          *           / * P is valid, so update sequence number variables
199          *               accordingly.  After this update, P will pass the tests
200          *               in Step 6.  A SyncAck is generated if necessary in
201          *               Step 15 * /
202          *           Update S.GSR, S.SWL, S.SWH
203          *        Otherwise,
204          *           Drop packet and return
205          */
206         if (dh->dccph_type == DCCP_PKT_SYNC ||
207             dh->dccph_type == DCCP_PKT_SYNCACK) {
208                 if (between48(ackno, dp->dccps_awl, dp->dccps_awh) &&
209                     dccp_delta_seqno(dp->dccps_swl, seqno) >= 0)
210                         dccp_update_gsr(sk, seqno);
211                 else
212                         return -1;
213         }
214
215         /*
216          *   Step 6: Check sequence numbers
217          *      Let LSWL = S.SWL and LAWL = S.AWL
218          *      If P.type == CloseReq or P.type == Close or P.type == Reset,
219          *        LSWL := S.GSR + 1, LAWL := S.GAR
220          *      If LSWL <= P.seqno <= S.SWH
221          *           and (P.ackno does not exist or LAWL <= P.ackno <= S.AWH),
222          *        Update S.GSR, S.SWL, S.SWH
223          *        If P.type != Sync,
224          *           Update S.GAR
225          */
226         lswl = dp->dccps_swl;
227         lawl = dp->dccps_awl;
228
229         if (dh->dccph_type == DCCP_PKT_CLOSEREQ ||
230             dh->dccph_type == DCCP_PKT_CLOSE ||
231             dh->dccph_type == DCCP_PKT_RESET) {
232                 lswl = ADD48(dp->dccps_gsr, 1);
233                 lawl = dp->dccps_gar;
234         }
235
236         if (between48(seqno, lswl, dp->dccps_swh) &&
237             (ackno == DCCP_PKT_WITHOUT_ACK_SEQ ||
238              between48(ackno, lawl, dp->dccps_awh))) {
239                 dccp_update_gsr(sk, seqno);
240
241                 if (dh->dccph_type != DCCP_PKT_SYNC &&
242                     (ackno != DCCP_PKT_WITHOUT_ACK_SEQ))
243                         dp->dccps_gar = ackno;
244         } else {
245                 unsigned long now = jiffies;
246                 /*
247                  *   Step 6: Check sequence numbers
248                  *      Otherwise,
249                  *         If P.type == Reset,
250                  *            Send Sync packet acknowledging S.GSR
251                  *         Otherwise,
252                  *            Send Sync packet acknowledging P.seqno
253                  *      Drop packet and return
254                  *
255                  *   These Syncs are rate-limited as per RFC 4340, 7.5.4:
256                  *   at most 1 / (dccp_sync_rate_limit * HZ) Syncs per second.
257                  */
258                 if (time_before(now, (dp->dccps_rate_last +
259                                       sysctl_dccp_sync_ratelimit)))
260                         return 0;
261
262                 DCCP_WARN("DCCP: Step 6 failed for %s packet, "
263                           "(LSWL(%llu) <= P.seqno(%llu) <= S.SWH(%llu)) and "
264                           "(P.ackno %s or LAWL(%llu) <= P.ackno(%llu) <= S.AWH(%llu), "
265                           "sending SYNC...\n",  dccp_packet_name(dh->dccph_type),
266                           (unsigned long long) lswl, (unsigned long long) seqno,
267                           (unsigned long long) dp->dccps_swh,
268                           (ackno == DCCP_PKT_WITHOUT_ACK_SEQ) ? "doesn't exist"
269                                                               : "exists",
270                           (unsigned long long) lawl, (unsigned long long) ackno,
271                           (unsigned long long) dp->dccps_awh);
272
273                 dp->dccps_rate_last = now;
274
275                 if (dh->dccph_type == DCCP_PKT_RESET)
276                         seqno = dp->dccps_gsr;
277                 dccp_send_sync(sk, seqno, DCCP_PKT_SYNC);
278                 return -1;
279         }
280
281         return 0;
282 }
283
284 static 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         switch (dccp_hdr(skb)->dccph_type) {
290         case DCCP_PKT_DATAACK:
291         case DCCP_PKT_DATA:
292                 /*
293                  * FIXME: schedule DATA_DROPPED (RFC 4340, 11.7.2) if and when
294                  * - sk_shutdown == RCV_SHUTDOWN, use Code 1, "Not Listening"
295                  * - sk_receive_queue is full, use Code 2, "Receive Buffer"
296                  */
297                 dccp_enqueue_skb(sk, skb);
298                 return 0;
299         case DCCP_PKT_ACK:
300                 goto discard;
301         case DCCP_PKT_RESET:
302                 /*
303                  *  Step 9: Process Reset
304                  *      If P.type == Reset,
305                  *              Tear down connection
306                  *              S.state := TIMEWAIT
307                  *              Set TIMEWAIT timer
308                  *              Drop packet and return
309                  */
310                 dccp_rcv_reset(sk, skb);
311                 return 0;
312         case DCCP_PKT_CLOSEREQ:
313                 if (dccp_rcv_closereq(sk, skb))
314                         return 0;
315                 goto discard;
316         case DCCP_PKT_CLOSE:
317                 if (dccp_rcv_close(sk, skb))
318                         return 0;
319                 goto discard;
320         case DCCP_PKT_REQUEST:
321                 /* Step 7
322                  *   or (S.is_server and P.type == Response)
323                  *   or (S.is_client and P.type == Request)
324                  *   or (S.state >= OPEN and P.type == Request
325                  *      and P.seqno >= S.OSR)
326                  *    or (S.state >= OPEN and P.type == Response
327                  *      and P.seqno >= S.OSR)
328                  *    or (S.state == RESPOND and P.type == Data),
329                  *  Send Sync packet acknowledging P.seqno
330                  *  Drop packet and return
331                  */
332                 if (dp->dccps_role != DCCP_ROLE_LISTEN)
333                         goto send_sync;
334                 goto check_seq;
335         case DCCP_PKT_RESPONSE:
336                 if (dp->dccps_role != DCCP_ROLE_CLIENT)
337                         goto send_sync;
338 check_seq:
339                 if (dccp_delta_seqno(dp->dccps_osr,
340                                      DCCP_SKB_CB(skb)->dccpd_seq) >= 0) {
341 send_sync:
342                         dccp_send_sync(sk, DCCP_SKB_CB(skb)->dccpd_seq,
343                                        DCCP_PKT_SYNC);
344                 }
345                 break;
346         case DCCP_PKT_SYNC:
347                 dccp_send_sync(sk, DCCP_SKB_CB(skb)->dccpd_seq,
348                                DCCP_PKT_SYNCACK);
349                 /*
350                  * From RFC 4340, sec. 5.7
351                  *
352                  * As with DCCP-Ack packets, DCCP-Sync and DCCP-SyncAck packets
353                  * MAY have non-zero-length application data areas, whose
354                  * contents receivers MUST ignore.
355                  */
356                 goto discard;
357         }
358
359         DCCP_INC_STATS_BH(DCCP_MIB_INERRS);
360 discard:
361         __kfree_skb(skb);
362         return 0;
363 }
364
365 int dccp_rcv_established(struct sock *sk, struct sk_buff *skb,
366                          const struct dccp_hdr *dh, const unsigned len)
367 {
368         struct dccp_sock *dp = dccp_sk(sk);
369
370         if (dccp_check_seqno(sk, skb))
371                 goto discard;
372
373         if (dccp_parse_options(sk, NULL, skb))
374                 return 1;
375
376         if (DCCP_SKB_CB(skb)->dccpd_ack_seq != DCCP_PKT_WITHOUT_ACK_SEQ)
377                 dccp_event_ack_recv(sk, skb);
378
379         if (dp->dccps_hc_rx_ackvec != NULL &&
380             dccp_ackvec_add(dp->dccps_hc_rx_ackvec, sk,
381                             DCCP_SKB_CB(skb)->dccpd_seq,
382                             DCCP_ACKVEC_STATE_RECEIVED))
383                 goto discard;
384         dccp_deliver_input_to_ccids(sk, skb);
385
386         return __dccp_rcv_established(sk, skb, dh, len);
387 discard:
388         __kfree_skb(skb);
389         return 0;
390 }
391
392 EXPORT_SYMBOL_GPL(dccp_rcv_established);
393
394 static int dccp_rcv_request_sent_state_process(struct sock *sk,
395                                                struct sk_buff *skb,
396                                                const struct dccp_hdr *dh,
397                                                const unsigned len)
398 {
399         /*
400          *  Step 4: Prepare sequence numbers in REQUEST
401          *     If S.state == REQUEST,
402          *        If (P.type == Response or P.type == Reset)
403          *              and S.AWL <= P.ackno <= S.AWH,
404          *           / * Set sequence number variables corresponding to the
405          *              other endpoint, so P will pass the tests in Step 6 * /
406          *           Set S.GSR, S.ISR, S.SWL, S.SWH
407          *           / * Response processing continues in Step 10; Reset
408          *              processing continues in Step 9 * /
409         */
410         if (dh->dccph_type == DCCP_PKT_RESPONSE) {
411                 const struct inet_connection_sock *icsk = inet_csk(sk);
412                 struct dccp_sock *dp = dccp_sk(sk);
413                 long tstamp = dccp_timestamp();
414
415                 if (!between48(DCCP_SKB_CB(skb)->dccpd_ack_seq,
416                                dp->dccps_awl, dp->dccps_awh)) {
417                         dccp_pr_debug("invalid ackno: S.AWL=%llu, "
418                                       "P.ackno=%llu, S.AWH=%llu\n",
419                                       (unsigned long long)dp->dccps_awl,
420                            (unsigned long long)DCCP_SKB_CB(skb)->dccpd_ack_seq,
421                                       (unsigned long long)dp->dccps_awh);
422                         goto out_invalid_packet;
423                 }
424
425                 /*
426                  * If option processing (Step 8) failed, return 1 here so that
427                  * dccp_v4_do_rcv() sends a Reset. The Reset code depends on
428                  * the option type and is set in dccp_parse_options().
429                  */
430                 if (dccp_parse_options(sk, NULL, skb))
431                         return 1;
432
433                 /* Obtain usec RTT sample from SYN exchange (used by TFRC). */
434                 if (likely(dp->dccps_options_received.dccpor_timestamp_echo))
435                         dp->dccps_syn_rtt = dccp_sample_rtt(sk, 10 * (tstamp -
436                             dp->dccps_options_received.dccpor_timestamp_echo));
437
438                 /* Stop the REQUEST timer */
439                 inet_csk_clear_xmit_timer(sk, ICSK_TIME_RETRANS);
440                 WARN_ON(sk->sk_send_head == NULL);
441                 kfree_skb(sk->sk_send_head);
442                 sk->sk_send_head = NULL;
443
444                 dp->dccps_isr = DCCP_SKB_CB(skb)->dccpd_seq;
445                 dccp_update_gsr(sk, dp->dccps_isr);
446                 /*
447                  * SWL and AWL are initially adjusted so that they are not less than
448                  * the initial Sequence Numbers received and sent, respectively:
449                  *      SWL := max(GSR + 1 - floor(W/4), ISR),
450                  *      AWL := max(GSS - W' + 1, ISS).
451                  * These adjustments MUST be applied only at the beginning of the
452                  * connection.
453                  *
454                  * AWL was adjusted in dccp_v4_connect -acme
455                  */
456                 dccp_set_seqno(&dp->dccps_swl,
457                                max48(dp->dccps_swl, dp->dccps_isr));
458
459                 dccp_sync_mss(sk, icsk->icsk_pmtu_cookie);
460
461                 /*
462                  *    Step 10: Process REQUEST state (second part)
463                  *       If S.state == REQUEST,
464                  *        / * If we get here, P is a valid Response from the
465                  *            server (see Step 4), and we should move to
466                  *            PARTOPEN state. PARTOPEN means send an Ack,
467                  *            don't send Data packets, retransmit Acks
468                  *            periodically, and always include any Init Cookie
469                  *            from the Response * /
470                  *        S.state := PARTOPEN
471                  *        Set PARTOPEN timer
472                  *        Continue with S.state == PARTOPEN
473                  *        / * Step 12 will send the Ack completing the
474                  *            three-way handshake * /
475                  */
476                 dccp_set_state(sk, DCCP_PARTOPEN);
477
478                 /*
479                  * If feature negotiation was successful, activate features now;
480                  * an activation failure means that this host could not activate
481                  * one ore more features (e.g. insufficient memory), which would
482                  * leave at least one feature in an undefined state.
483                  */
484                 if (dccp_feat_activate_values(sk, &dp->dccps_featneg))
485                         goto unable_to_proceed;
486
487                 /* Make sure socket is routed, for correct metrics. */
488                 icsk->icsk_af_ops->rebuild_header(sk);
489
490                 if (!sock_flag(sk, SOCK_DEAD)) {
491                         sk->sk_state_change(sk);
492                         sk_wake_async(sk, SOCK_WAKE_IO, POLL_OUT);
493                 }
494
495                 if (sk->sk_write_pending || icsk->icsk_ack.pingpong ||
496                     icsk->icsk_accept_queue.rskq_defer_accept) {
497                         /* Save one ACK. Data will be ready after
498                          * several ticks, if write_pending is set.
499                          *
500                          * It may be deleted, but with this feature tcpdumps
501                          * look so _wonderfully_ clever, that I was not able
502                          * to stand against the temptation 8)     --ANK
503                          */
504                         /*
505                          * OK, in DCCP we can as well do a similar trick, its
506                          * even in the draft, but there is no need for us to
507                          * schedule an ack here, as dccp_sendmsg does this for
508                          * us, also stated in the draft. -acme
509                          */
510                         __kfree_skb(skb);
511                         return 0;
512                 }
513                 dccp_send_ack(sk);
514                 return -1;
515         }
516
517 out_invalid_packet:
518         /* dccp_v4_do_rcv will send a reset */
519         DCCP_SKB_CB(skb)->dccpd_reset_code = DCCP_RESET_CODE_PACKET_ERROR;
520         return 1;
521
522 unable_to_proceed:
523         DCCP_SKB_CB(skb)->dccpd_reset_code = DCCP_RESET_CODE_ABORTED;
524         /*
525          * We mark this socket as no longer usable, so that the loop in
526          * dccp_sendmsg() terminates and the application gets notified.
527          */
528         dccp_set_state(sk, DCCP_CLOSED);
529         sk->sk_err = ECOMM;
530         return 1;
531 }
532
533 static int dccp_rcv_respond_partopen_state_process(struct sock *sk,
534                                                    struct sk_buff *skb,
535                                                    const struct dccp_hdr *dh,
536                                                    const unsigned len)
537 {
538         struct dccp_sock *dp = dccp_sk(sk);
539         u32 sample = dp->dccps_options_received.dccpor_timestamp_echo;
540         int queued = 0;
541
542         switch (dh->dccph_type) {
543         case DCCP_PKT_RESET:
544                 inet_csk_clear_xmit_timer(sk, ICSK_TIME_DACK);
545                 break;
546         case DCCP_PKT_DATA:
547                 if (sk->sk_state == DCCP_RESPOND)
548                         break;
549         case DCCP_PKT_DATAACK:
550         case DCCP_PKT_ACK:
551                 /*
552                  * FIXME: we should be reseting the PARTOPEN (DELACK) timer
553                  * here but only if we haven't used the DELACK timer for
554                  * something else, like sending a delayed ack for a TIMESTAMP
555                  * echo, etc, for now were not clearing it, sending an extra
556                  * ACK when there is nothing else to do in DELACK is not a big
557                  * deal after all.
558                  */
559
560                 /* Stop the PARTOPEN timer */
561                 if (sk->sk_state == DCCP_PARTOPEN)
562                         inet_csk_clear_xmit_timer(sk, ICSK_TIME_DACK);
563
564                 /* Obtain usec RTT sample from SYN exchange (used by TFRC). */
565                 if (likely(sample)) {
566                         long delta = dccp_timestamp() - sample;
567
568                         dp->dccps_syn_rtt = dccp_sample_rtt(sk, 10 * delta);
569                 }
570
571                 dp->dccps_osr = DCCP_SKB_CB(skb)->dccpd_seq;
572                 dccp_set_state(sk, DCCP_OPEN);
573
574                 if (dh->dccph_type == DCCP_PKT_DATAACK ||
575                     dh->dccph_type == DCCP_PKT_DATA) {
576                         __dccp_rcv_established(sk, skb, dh, len);
577                         queued = 1; /* packet was queued
578                                        (by __dccp_rcv_established) */
579                 }
580                 break;
581         }
582
583         return queued;
584 }
585
586 int dccp_rcv_state_process(struct sock *sk, struct sk_buff *skb,
587                            struct dccp_hdr *dh, unsigned len)
588 {
589         struct dccp_sock *dp = dccp_sk(sk);
590         struct dccp_skb_cb *dcb = DCCP_SKB_CB(skb);
591         const int old_state = sk->sk_state;
592         int queued = 0;
593
594         /*
595          *  Step 3: Process LISTEN state
596          *
597          *     If S.state == LISTEN,
598          *       If P.type == Request or P contains a valid Init Cookie option,
599          *            (* Must scan the packet's options to check for Init
600          *               Cookies.  Only Init Cookies are processed here,
601          *               however; other options are processed in Step 8.  This
602          *               scan need only be performed if the endpoint uses Init
603          *               Cookies *)
604          *            (* Generate a new socket and switch to that socket *)
605          *            Set S := new socket for this port pair
606          *            S.state = RESPOND
607          *            Choose S.ISS (initial seqno) or set from Init Cookies
608          *            Initialize S.GAR := S.ISS
609          *            Set S.ISR, S.GSR, S.SWL, S.SWH from packet or Init
610          *            Cookies Continue with S.state == RESPOND
611          *            (* A Response packet will be generated in Step 11 *)
612          *       Otherwise,
613          *            Generate Reset(No Connection) unless P.type == Reset
614          *            Drop packet and return
615          */
616         if (sk->sk_state == DCCP_LISTEN) {
617                 if (dh->dccph_type == DCCP_PKT_REQUEST) {
618                         if (inet_csk(sk)->icsk_af_ops->conn_request(sk,
619                                                                     skb) < 0)
620                                 return 1;
621                         goto discard;
622                 }
623                 if (dh->dccph_type == DCCP_PKT_RESET)
624                         goto discard;
625
626                 /* Caller (dccp_v4_do_rcv) will send Reset */
627                 dcb->dccpd_reset_code = DCCP_RESET_CODE_NO_CONNECTION;
628                 return 1;
629         }
630
631         if (sk->sk_state != DCCP_REQUESTING && sk->sk_state != DCCP_RESPOND) {
632                 if (dccp_check_seqno(sk, skb))
633                         goto discard;
634
635                 /*
636                  * Step 8: Process options and mark acknowledgeable
637                  */
638                 if (dccp_parse_options(sk, NULL, skb))
639                         return 1;
640
641                 if (dcb->dccpd_ack_seq != DCCP_PKT_WITHOUT_ACK_SEQ)
642                         dccp_event_ack_recv(sk, skb);
643
644                 if (dp->dccps_hc_rx_ackvec != NULL &&
645                     dccp_ackvec_add(dp->dccps_hc_rx_ackvec, sk,
646                                     DCCP_SKB_CB(skb)->dccpd_seq,
647                                     DCCP_ACKVEC_STATE_RECEIVED))
648                         goto discard;
649
650                 dccp_deliver_input_to_ccids(sk, skb);
651         }
652
653         /*
654          *  Step 9: Process Reset
655          *      If P.type == Reset,
656          *              Tear down connection
657          *              S.state := TIMEWAIT
658          *              Set TIMEWAIT timer
659          *              Drop packet and return
660         */
661         if (dh->dccph_type == DCCP_PKT_RESET) {
662                 dccp_rcv_reset(sk, skb);
663                 return 0;
664                 /*
665                  *   Step 7: Check for unexpected packet types
666                  *      If (S.is_server and P.type == Response)
667                  *          or (S.is_client and P.type == Request)
668                  *          or (S.state == RESPOND and P.type == Data),
669                  *        Send Sync packet acknowledging P.seqno
670                  *        Drop packet and return
671                  */
672         } else if ((dp->dccps_role != DCCP_ROLE_CLIENT &&
673                     dh->dccph_type == DCCP_PKT_RESPONSE) ||
674                     (dp->dccps_role == DCCP_ROLE_CLIENT &&
675                      dh->dccph_type == DCCP_PKT_REQUEST) ||
676                     (sk->sk_state == DCCP_RESPOND &&
677                      dh->dccph_type == DCCP_PKT_DATA)) {
678                 dccp_send_sync(sk, dcb->dccpd_seq, DCCP_PKT_SYNC);
679                 goto discard;
680         } else if (dh->dccph_type == DCCP_PKT_CLOSEREQ) {
681                 if (dccp_rcv_closereq(sk, skb))
682                         return 0;
683                 goto discard;
684         } else if (dh->dccph_type == DCCP_PKT_CLOSE) {
685                 if (dccp_rcv_close(sk, skb))
686                         return 0;
687                 goto discard;
688         }
689
690         switch (sk->sk_state) {
691         case DCCP_CLOSED:
692                 dcb->dccpd_reset_code = DCCP_RESET_CODE_NO_CONNECTION;
693                 return 1;
694
695         case DCCP_REQUESTING:
696                 queued = dccp_rcv_request_sent_state_process(sk, skb, dh, len);
697                 if (queued >= 0)
698                         return queued;
699
700                 __kfree_skb(skb);
701                 return 0;
702
703         case DCCP_RESPOND:
704         case DCCP_PARTOPEN:
705                 queued = dccp_rcv_respond_partopen_state_process(sk, skb,
706                                                                  dh, len);
707                 break;
708         }
709
710         if (dh->dccph_type == DCCP_PKT_ACK ||
711             dh->dccph_type == DCCP_PKT_DATAACK) {
712                 switch (old_state) {
713                 case DCCP_PARTOPEN:
714                         sk->sk_state_change(sk);
715                         sk_wake_async(sk, SOCK_WAKE_IO, POLL_OUT);
716                         break;
717                 }
718         } else if (unlikely(dh->dccph_type == DCCP_PKT_SYNC)) {
719                 dccp_send_sync(sk, dcb->dccpd_seq, DCCP_PKT_SYNCACK);
720                 goto discard;
721         }
722
723         if (!queued) {
724 discard:
725                 __kfree_skb(skb);
726         }
727         return 0;
728 }
729
730 EXPORT_SYMBOL_GPL(dccp_rcv_state_process);
731
732 /**
733  *  dccp_sample_rtt  -  Validate and finalise computation of RTT sample
734  *  @delta:     number of microseconds between packet and acknowledgment
735  *  The routine is kept generic to work in different contexts. It should be
736  *  called immediately when the ACK used for the RTT sample arrives.
737  */
738 u32 dccp_sample_rtt(struct sock *sk, long delta)
739 {
740         /* dccpor_elapsed_time is either zeroed out or set and > 0 */
741         delta -= dccp_sk(sk)->dccps_options_received.dccpor_elapsed_time * 10;
742
743         if (unlikely(delta <= 0)) {
744                 DCCP_WARN("unusable RTT sample %ld, using min\n", delta);
745                 return DCCP_SANE_RTT_MIN;
746         }
747         if (unlikely(delta > DCCP_SANE_RTT_MAX)) {
748                 DCCP_WARN("RTT sample %ld too large, using max\n", delta);
749                 return DCCP_SANE_RTT_MAX;
750         }
751
752         return delta;
753 }