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writeback: split writeback_inodes_wb
[linux-2.6/next.git] / net / dccp / input.c
blob6beb6a7d6fbab77ebd161e09a910959dc57805df
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 CCID 3) */
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 int queued = 0;
539
540 switch (dh->dccph_type) {
541 case DCCP_PKT_RESET:
542 inet_csk_clear_xmit_timer(sk, ICSK_TIME_DACK);
543 break;
544 case DCCP_PKT_DATA:
545 if (sk->sk_state == DCCP_RESPOND)
546 break;
547 case DCCP_PKT_DATAACK:
548 case DCCP_PKT_ACK:
549 /*
550 * FIXME: we should be reseting the PARTOPEN (DELACK) timer
551 * here but only if we haven't used the DELACK timer for
552 * something else, like sending a delayed ack for a TIMESTAMP
553 * echo, etc, for now were not clearing it, sending an extra
554 * ACK when there is nothing else to do in DELACK is not a big
555 * deal after all.
556 */
557
558 /* Stop the PARTOPEN timer */
559 if (sk->sk_state == DCCP_PARTOPEN)
560 inet_csk_clear_xmit_timer(sk, ICSK_TIME_DACK);
561
562 dccp_sk(sk)->dccps_osr = DCCP_SKB_CB(skb)->dccpd_seq;
563 dccp_set_state(sk, DCCP_OPEN);
564
565 if (dh->dccph_type == DCCP_PKT_DATAACK ||
566 dh->dccph_type == DCCP_PKT_DATA) {
567 __dccp_rcv_established(sk, skb, dh, len);
568 queued = 1; /* packet was queued
569 (by __dccp_rcv_established) */
570 }
571 break;
572 }
573
574 return queued;
575 }
576
577 int dccp_rcv_state_process(struct sock *sk, struct sk_buff *skb,
578 struct dccp_hdr *dh, unsigned len)
579 {
580 struct dccp_sock *dp = dccp_sk(sk);
581 struct dccp_skb_cb *dcb = DCCP_SKB_CB(skb);
582 const int old_state = sk->sk_state;
583 int queued = 0;
584
585 /*
586 * Step 3: Process LISTEN state
587 *
588 * If S.state == LISTEN,
589 * If P.type == Request or P contains a valid Init Cookie option,
590 * (* Must scan the packet's options to check for Init
591 * Cookies. Only Init Cookies are processed here,
592 * however; other options are processed in Step 8. This
593 * scan need only be performed if the endpoint uses Init
594 * Cookies *)
595 * (* Generate a new socket and switch to that socket *)
596 * Set S := new socket for this port pair
597 * S.state = RESPOND
598 * Choose S.ISS (initial seqno) or set from Init Cookies
599 * Initialize S.GAR := S.ISS
600 * Set S.ISR, S.GSR, S.SWL, S.SWH from packet or Init
601 * Cookies Continue with S.state == RESPOND
602 * (* A Response packet will be generated in Step 11 *)
603 * Otherwise,
604 * Generate Reset(No Connection) unless P.type == Reset
605 * Drop packet and return
606 */
607 if (sk->sk_state == DCCP_LISTEN) {
608 if (dh->dccph_type == DCCP_PKT_REQUEST) {
609 if (inet_csk(sk)->icsk_af_ops->conn_request(sk,
610 skb) < 0)
611 return 1;
612 goto discard;
613 }
614 if (dh->dccph_type == DCCP_PKT_RESET)
615 goto discard;
616
617 /* Caller (dccp_v4_do_rcv) will send Reset */
618 dcb->dccpd_reset_code = DCCP_RESET_CODE_NO_CONNECTION;
619 return 1;
620 }
621
622 if (sk->sk_state != DCCP_REQUESTING && sk->sk_state != DCCP_RESPOND) {
623 if (dccp_check_seqno(sk, skb))
624 goto discard;
625
626 /*
627 * Step 8: Process options and mark acknowledgeable
628 */
629 if (dccp_parse_options(sk, NULL, skb))
630 return 1;
631
632 if (dcb->dccpd_ack_seq != DCCP_PKT_WITHOUT_ACK_SEQ)
633 dccp_event_ack_recv(sk, skb);
634
635 if (dp->dccps_hc_rx_ackvec != NULL &&
636 dccp_ackvec_add(dp->dccps_hc_rx_ackvec, sk,
637 DCCP_SKB_CB(skb)->dccpd_seq,
638 DCCP_ACKVEC_STATE_RECEIVED))
639 goto discard;
640
641 dccp_deliver_input_to_ccids(sk, skb);
642 }
643
644 /*
645 * Step 9: Process Reset
646 * If P.type == Reset,
647 * Tear down connection
648 * S.state := TIMEWAIT
649 * Set TIMEWAIT timer
650 * Drop packet and return
651 */
652 if (dh->dccph_type == DCCP_PKT_RESET) {
653 dccp_rcv_reset(sk, skb);
654 return 0;
655 /*
656 * Step 7: Check for unexpected packet types
657 * If (S.is_server and P.type == Response)
658 * or (S.is_client and P.type == Request)
659 * or (S.state == RESPOND and P.type == Data),
660 * Send Sync packet acknowledging P.seqno
661 * Drop packet and return
662 */
663 } else if ((dp->dccps_role != DCCP_ROLE_CLIENT &&
664 dh->dccph_type == DCCP_PKT_RESPONSE) ||
665 (dp->dccps_role == DCCP_ROLE_CLIENT &&
666 dh->dccph_type == DCCP_PKT_REQUEST) ||
667 (sk->sk_state == DCCP_RESPOND &&
668 dh->dccph_type == DCCP_PKT_DATA)) {
669 dccp_send_sync(sk, dcb->dccpd_seq, DCCP_PKT_SYNC);
670 goto discard;
671 } else if (dh->dccph_type == DCCP_PKT_CLOSEREQ) {
672 if (dccp_rcv_closereq(sk, skb))
673 return 0;
674 goto discard;
675 } else if (dh->dccph_type == DCCP_PKT_CLOSE) {
676 if (dccp_rcv_close(sk, skb))
677 return 0;
678 goto discard;
679 }
680
681 switch (sk->sk_state) {
682 case DCCP_CLOSED:
683 dcb->dccpd_reset_code = DCCP_RESET_CODE_NO_CONNECTION;
684 return 1;
685
686 case DCCP_REQUESTING:
687 queued = dccp_rcv_request_sent_state_process(sk, skb, dh, len);
688 if (queued >= 0)
689 return queued;
690
691 __kfree_skb(skb);
692 return 0;
693
694 case DCCP_RESPOND:
695 case DCCP_PARTOPEN:
696 queued = dccp_rcv_respond_partopen_state_process(sk, skb,
697 dh, len);
698 break;
699 }
700
701 if (dh->dccph_type == DCCP_PKT_ACK ||
702 dh->dccph_type == DCCP_PKT_DATAACK) {
703 switch (old_state) {
704 case DCCP_PARTOPEN:
705 sk->sk_state_change(sk);
706 sk_wake_async(sk, SOCK_WAKE_IO, POLL_OUT);
707 break;
708 }
709 } else if (unlikely(dh->dccph_type == DCCP_PKT_SYNC)) {
710 dccp_send_sync(sk, dcb->dccpd_seq, DCCP_PKT_SYNCACK);
711 goto discard;
712 }
713
714 if (!queued) {
715 discard:
716 __kfree_skb(skb);
717 }
718 return 0;
719 }
720
721 EXPORT_SYMBOL_GPL(dccp_rcv_state_process);
722
723 /**
724 * dccp_sample_rtt - Validate and finalise computation of RTT sample
725 * @delta: number of microseconds between packet and acknowledgment
726 * The routine is kept generic to work in different contexts. It should be
727 * called immediately when the ACK used for the RTT sample arrives.
728 */
729 u32 dccp_sample_rtt(struct sock *sk, long delta)
730 {
731 /* dccpor_elapsed_time is either zeroed out or set and > 0 */
732 delta -= dccp_sk(sk)->dccps_options_received.dccpor_elapsed_time * 10;
733
734 if (unlikely(delta <= 0)) {
735 DCCP_WARN("unusable RTT sample %ld, using min\n", delta);
736 return DCCP_SANE_RTT_MIN;
737 }
738 if (unlikely(delta > DCCP_SANE_RTT_MAX)) {
739 DCCP_WARN("RTT sample %ld too large, using max\n", delta);
740 return DCCP_SANE_RTT_MAX;
741 }
742
743 return delta;
744 }
linux-next