input.c 17.1 KB
Newer Older
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
/*
 *  net/dccp/input.c
 * 
 *  An implementation of the DCCP protocol
 *  Arnaldo Carvalho de Melo <acme@conectiva.com.br>
 *
 *	This program is free software; you can redistribute it and/or
 *	modify it under the terms of the GNU General Public License
 *	as published by the Free Software Foundation; either version
 *	2 of the License, or (at your option) any later version.
 */

#include <linux/config.h>
#include <linux/dccp.h>
#include <linux/skbuff.h>

#include <net/sock.h>

#include "ccid.h"
#include "dccp.h"

static void dccp_fin(struct sock *sk, struct sk_buff *skb)
{
	sk->sk_shutdown |= RCV_SHUTDOWN;
	sock_set_flag(sk, SOCK_DONE);
	__skb_pull(skb, dccp_hdr(skb)->dccph_doff * 4);
	__skb_queue_tail(&sk->sk_receive_queue, skb);
	skb_set_owner_r(skb, sk);
	sk->sk_data_ready(sk, 0);
}

static void dccp_rcv_close(struct sock *sk, struct sk_buff *skb)
{
	switch (sk->sk_state) {
	case DCCP_PARTOPEN:
	case DCCP_OPEN:
		dccp_v4_send_reset(sk, DCCP_RESET_CODE_CLOSED);
		dccp_fin(sk, skb);
		dccp_set_state(sk, DCCP_CLOSED);
		break;
	}
}

static void dccp_rcv_closereq(struct sock *sk, struct sk_buff *skb)
{
	/*
	 *   Step 7: Check for unexpected packet types
	 *      If (S.is_server and P.type == CloseReq)
	 *	  Send Sync packet acknowledging P.seqno
	 *	  Drop packet and return
	 */
	if (dccp_sk(sk)->dccps_role != DCCP_ROLE_CLIENT) {
53
		dccp_send_sync(sk, DCCP_SKB_CB(skb)->dccpd_seq, DCCP_PKT_SYNC);
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
		return;
	}

	switch (sk->sk_state) {
	case DCCP_PARTOPEN:
	case DCCP_OPEN:
		dccp_set_state(sk, DCCP_CLOSING);
		dccp_send_close(sk);
		break;
	}
}

static inline void dccp_event_ack_recv(struct sock *sk, struct sk_buff *skb)
{
	struct dccp_sock *dp = dccp_sk(sk);

	if (dp->dccps_options.dccpo_send_ack_vector)
		dccp_ackpkts_check_rcv_ackno(dp->dccps_hc_rx_ackpkts, sk,
					     DCCP_SKB_CB(skb)->dccpd_ack_seq);
}

static int dccp_check_seqno(struct sock *sk, struct sk_buff *skb)
{
	const struct dccp_hdr *dh = dccp_hdr(skb);
	struct dccp_sock *dp = dccp_sk(sk);
79
	u64 lswl, lawl;
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94

	/*
	 *   Step 5: Prepare sequence numbers for Sync
	 *     If P.type == Sync or P.type == SyncAck,
	 *	  If S.AWL <= P.ackno <= S.AWH and P.seqno >= S.SWL,
	 *	     / * P is valid, so update sequence number variables
	 *		 accordingly.  After this update, P will pass the tests
	 *		 in Step 6.  A SyncAck is generated if necessary in
	 *		 Step 15 * /
	 *	     Update S.GSR, S.SWL, S.SWH
	 *	  Otherwise,
	 *	     Drop packet and return
	 */
	if (dh->dccph_type == DCCP_PKT_SYNC || 
	    dh->dccph_type == DCCP_PKT_SYNCACK) {
95
96
		if (between48(DCCP_SKB_CB(skb)->dccpd_ack_seq,
			      dp->dccps_awl, dp->dccps_awh) &&
97
98
99
100
		    !before48(DCCP_SKB_CB(skb)->dccpd_seq, dp->dccps_swl))
			dccp_update_gsr(sk, DCCP_SKB_CB(skb)->dccpd_seq);
		else
			return -1;
101
102
	}
	
103
104
105
106
107
108
109
110
111
112
113
114
115
116
	/*
	 *   Step 6: Check sequence numbers
	 *      Let LSWL = S.SWL and LAWL = S.AWL
	 *      If P.type == CloseReq or P.type == Close or P.type == Reset,
	 *	  LSWL := S.GSR + 1, LAWL := S.GAR
	 *      If LSWL <= P.seqno <= S.SWH
	 *	     and (P.ackno does not exist or LAWL <= P.ackno <= S.AWH),
	 *	  Update S.GSR, S.SWL, S.SWH
	 *	  If P.type != Sync,
	 *	     Update S.GAR
	 *      Otherwise,
	 *	  Send Sync packet acknowledging P.seqno
	 *	  Drop packet and return
	 */
117
118
119
120
	lswl = dp->dccps_swl;
	lawl = dp->dccps_awl;

	if (dh->dccph_type == DCCP_PKT_CLOSEREQ ||
121
122
	    dh->dccph_type == DCCP_PKT_CLOSE ||
	    dh->dccph_type == DCCP_PKT_RESET) {
123
124
125
126
127
128
129
		lswl = dp->dccps_gsr;
		dccp_inc_seqno(&lswl);
		lawl = dp->dccps_gar;
	}

	if (between48(DCCP_SKB_CB(skb)->dccpd_seq, lswl, dp->dccps_swh) &&
	    (DCCP_SKB_CB(skb)->dccpd_ack_seq == DCCP_PKT_WITHOUT_ACK_SEQ ||
130
131
	     between48(DCCP_SKB_CB(skb)->dccpd_ack_seq,
		       lawl, dp->dccps_awh))) {
132
133
134
		dccp_update_gsr(sk, DCCP_SKB_CB(skb)->dccpd_seq);

		if (dh->dccph_type != DCCP_PKT_SYNC &&
135
136
		    (DCCP_SKB_CB(skb)->dccpd_ack_seq !=
		     DCCP_PKT_WITHOUT_ACK_SEQ))
137
138
			dp->dccps_gar = DCCP_SKB_CB(skb)->dccpd_ack_seq;
	} else {
139
140
141
142
143
		LIMIT_NETDEBUG(KERN_WARNING "DCCP: Step 6 failed for %s packet, "
					    "(LSWL(%llu) <= P.seqno(%llu) <= S.SWH(%llu)) and "
					    "(P.ackno %s or LAWL(%llu) <= P.ackno(%llu) <= S.AWH(%llu), "
					    "sending SYNC...\n",
			       dccp_packet_name(dh->dccph_type),
144
145
146
147
			       (unsigned long long) lswl,
			       (unsigned long long)
			       DCCP_SKB_CB(skb)->dccpd_seq,
			       (unsigned long long) dp->dccps_swh,
148
149
			       (DCCP_SKB_CB(skb)->dccpd_ack_seq ==
			        DCCP_PKT_WITHOUT_ACK_SEQ) ? "doesn't exist" : "exists",
150
151
152
153
			       (unsigned long long) lawl,
			       (unsigned long long)
			       DCCP_SKB_CB(skb)->dccpd_ack_seq,
			       (unsigned long long) dp->dccps_awh);
154
		dccp_send_sync(sk, DCCP_SKB_CB(skb)->dccpd_seq, DCCP_PKT_SYNC);
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
		return -1;
	}

	return 0;
}

int dccp_rcv_established(struct sock *sk, struct sk_buff *skb,
			 const struct dccp_hdr *dh, const unsigned len)
{
	struct dccp_sock *dp = dccp_sk(sk);

	if (dccp_check_seqno(sk, skb))
		goto discard;

	if (dccp_parse_options(sk, skb))
		goto discard;

	if (DCCP_SKB_CB(skb)->dccpd_ack_seq != DCCP_PKT_WITHOUT_ACK_SEQ)
		dccp_event_ack_recv(sk, skb);

	/*
	 * FIXME: check ECN to see if we should use
	 * DCCP_ACKPKTS_STATE_ECN_MARKED
	 */
	if (dp->dccps_options.dccpo_send_ack_vector) {
		struct dccp_ackpkts *ap = dp->dccps_hc_rx_ackpkts;

		if (dccp_ackpkts_add(dp->dccps_hc_rx_ackpkts,
				     DCCP_SKB_CB(skb)->dccpd_seq,
				     DCCP_ACKPKTS_STATE_RECEIVED)) {
185
186
			LIMIT_NETDEBUG(KERN_WARNING "DCCP: acknowledgeable "
						    "packets buffer full!\n");
187
188
			ap->dccpap_ack_seqno = DCCP_MAX_SEQNO + 1;
			inet_csk_schedule_ack(sk);
189
190
191
			inet_csk_reset_xmit_timer(sk, ICSK_TIME_DACK,
						  TCP_DELACK_MIN,
						  DCCP_RTO_MAX);
192
193
194
195
196
197
198
199
200
201
			goto discard;
		}

		/*
		 * FIXME: this activation is probably wrong, have to study more
		 * TCP delack machinery and how it fits into DCCP draft, but
		 * for now it kinda "works" 8)
		 */
		if (!inet_csk_ack_scheduled(sk)) {
			inet_csk_schedule_ack(sk);
202
203
			inet_csk_reset_xmit_timer(sk, ICSK_TIME_DACK, 5 * HZ,
						  DCCP_RTO_MAX);
204
205
206
207
208
209
210
211
212
213
		}
	}

	ccid_hc_rx_packet_recv(dp->dccps_hc_rx_ccid, sk, skb);
	ccid_hc_tx_packet_recv(dp->dccps_hc_tx_ccid, sk, skb);

	switch (dccp_hdr(skb)->dccph_type) {
	case DCCP_PKT_DATAACK:
	case DCCP_PKT_DATA:
		/*
214
215
		 * FIXME: check if sk_receive_queue is full, schedule DATA_DROPPED
		 * option if it is.
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
		 */
		__skb_pull(skb, dh->dccph_doff * 4);
		__skb_queue_tail(&sk->sk_receive_queue, skb);
		skb_set_owner_r(skb, sk);
		sk->sk_data_ready(sk, 0);
		return 0;
	case DCCP_PKT_ACK:
		goto discard;
	case DCCP_PKT_RESET:
		/*
		 *  Step 9: Process Reset
		 *	If P.type == Reset,
		 *		Tear down connection
		 *		S.state := TIMEWAIT
		 *		Set TIMEWAIT timer
		 *		Drop packet and return
		*/
		dccp_fin(sk, skb);
		dccp_time_wait(sk, DCCP_TIME_WAIT, 0);
		return 0;
	case DCCP_PKT_CLOSEREQ:
		dccp_rcv_closereq(sk, skb);
		goto discard;
	case DCCP_PKT_CLOSE:
		dccp_rcv_close(sk, skb);
		return 0;
	case DCCP_PKT_REQUEST:
		/* Step 7 
            	 *   or (S.is_server and P.type == Response)
		 *   or (S.is_client and P.type == Request)
		 *   or (S.state >= OPEN and P.type == Request
		 *	and P.seqno >= S.OSR)
		 *    or (S.state >= OPEN and P.type == Response
		 *	and P.seqno >= S.OSR)
		 *    or (S.state == RESPOND and P.type == Data),
		 *  Send Sync packet acknowledging P.seqno
		 *  Drop packet and return
		 */
		if (dp->dccps_role != DCCP_ROLE_LISTEN)
			goto send_sync;
		goto check_seq;
	case DCCP_PKT_RESPONSE:
		if (dp->dccps_role != DCCP_ROLE_CLIENT)
			goto send_sync;
check_seq:
		if (!before48(DCCP_SKB_CB(skb)->dccpd_seq, dp->dccps_osr)) {
send_sync:
263
264
			dccp_send_sync(sk, DCCP_SKB_CB(skb)->dccpd_seq,
				       DCCP_PKT_SYNC);
265
266
		}
		break;
267
268
269
270
271
272
273
274
275
276
277
	case DCCP_PKT_SYNC:
		dccp_send_sync(sk, DCCP_SKB_CB(skb)->dccpd_seq,
			       DCCP_PKT_SYNCACK);
		/*
		 * From the draft:
		 *
		 * As with DCCP-Ack packets, DCCP-Sync and DCCP-SyncAck packets
		 * MAY have non-zero-length application data areas, whose
		 * contents * receivers MUST ignore.
		 */
		goto discard;
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
	}

	DCCP_INC_STATS_BH(DCCP_MIB_INERRS);
discard:
	__kfree_skb(skb);
	return 0;
}

static int dccp_rcv_request_sent_state_process(struct sock *sk,
					       struct sk_buff *skb,
					       const struct dccp_hdr *dh,
					       const unsigned len)
{
	/* 
	 *  Step 4: Prepare sequence numbers in REQUEST
	 *     If S.state == REQUEST,
	 *	  If (P.type == Response or P.type == Reset)
	 *		and S.AWL <= P.ackno <= S.AWH,
	 *	     / * Set sequence number variables corresponding to the
	 *		other endpoint, so P will pass the tests in Step 6 * /
	 *	     Set S.GSR, S.ISR, S.SWL, S.SWH
	 *	     / * Response processing continues in Step 10; Reset
	 *		processing continues in Step 9 * /
	*/
	if (dh->dccph_type == DCCP_PKT_RESPONSE) {
		const struct inet_connection_sock *icsk = inet_csk(sk);
		struct dccp_sock *dp = dccp_sk(sk);

		/* Stop the REQUEST timer */
		inet_csk_clear_xmit_timer(sk, ICSK_TIME_RETRANS);
		BUG_TRAP(sk->sk_send_head != NULL);
		__kfree_skb(sk->sk_send_head);
		sk->sk_send_head = NULL;

312
313
314
315
316
317
318
		if (!between48(DCCP_SKB_CB(skb)->dccpd_ack_seq,
			       dp->dccps_awl, dp->dccps_awh)) {
			dccp_pr_debug("invalid ackno: S.AWL=%llu, "
				      "P.ackno=%llu, S.AWH=%llu \n",
				      (unsigned long long)dp->dccps_awl,
			   (unsigned long long)DCCP_SKB_CB(skb)->dccpd_ack_seq,
				      (unsigned long long)dp->dccps_awh);
319
320
321
322
			goto out_invalid_packet;
		}

		dp->dccps_isr = DCCP_SKB_CB(skb)->dccpd_seq;
323
324
325
326
327
328
329
330
331
332
333
334
335
		dccp_update_gsr(sk, dp->dccps_isr);
		/*
		 * SWL and AWL are initially adjusted so that they are not less than
		 * the initial Sequence Numbers received and sent, respectively:
		 *	SWL := max(GSR + 1 - floor(W/4), ISR),
		 *	AWL := max(GSS - W' + 1, ISS).
		 * These adjustments MUST be applied only at the beginning of the
		 * connection.
		 *
		 * AWL was adjusted in dccp_v4_connect -acme
		 */
		dccp_set_seqno(&dp->dccps_swl,
			       max48(dp->dccps_swl, dp->dccps_isr));
336
337
338
339
340
341
342
343
344
345
346
347
348
349

		if (ccid_hc_rx_init(dp->dccps_hc_rx_ccid, sk) != 0 ||
		    ccid_hc_tx_init(dp->dccps_hc_tx_ccid, sk) != 0) {
			ccid_hc_rx_exit(dp->dccps_hc_rx_ccid, sk);
			ccid_hc_tx_exit(dp->dccps_hc_tx_ccid, sk);
			/* FIXME: send appropriate RESET code */
			goto out_invalid_packet;
		}

		dccp_sync_mss(sk, dp->dccps_pmtu_cookie);

		/*
		 *    Step 10: Process REQUEST state (second part)
		 *       If S.state == REQUEST,
350
351
352
353
354
355
		 *	  / * If we get here, P is a valid Response from the
		 *	      server (see Step 4), and we should move to
		 *	      PARTOPEN state. PARTOPEN means send an Ack,
		 *	      don't send Data packets, retransmit Acks
		 *	      periodically, and always include any Init Cookie
		 *	      from the Response * /
356
357
358
		 *	  S.state := PARTOPEN
		 *	  Set PARTOPEN timer
		 * 	  Continue with S.state == PARTOPEN
359
360
		 *	  / * Step 12 will send the Ack completing the
		 *	      three-way handshake * /
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
		 */
		dccp_set_state(sk, DCCP_PARTOPEN);

		/* Make sure socket is routed, for correct metrics. */
		inet_sk_rebuild_header(sk);

		if (!sock_flag(sk, SOCK_DEAD)) {
			sk->sk_state_change(sk);
			sk_wake_async(sk, 0, POLL_OUT);
		}

		if (sk->sk_write_pending || icsk->icsk_ack.pingpong ||
		    icsk->icsk_accept_queue.rskq_defer_accept) {
			/* Save one ACK. Data will be ready after
			 * several ticks, if write_pending is set.
			 *
			 * It may be deleted, but with this feature tcpdumps
			 * look so _wonderfully_ clever, that I was not able
			 * to stand against the temptation 8)     --ANK
			 */
			/*
			 * OK, in DCCP we can as well do a similar trick, its
			 * even in the draft, but there is no need for us to
			 * schedule an ack here, as dccp_sendmsg does this for
			 * us, also stated in the draft. -acme
			 */
			__kfree_skb(skb);
			return 0;
		} 
		dccp_send_ack(sk);
		return -1;
	}

out_invalid_packet:
	return 1; /* dccp_v4_do_rcv will send a reset, but...
396
397
		     FIXME: the reset code should be
			    DCCP_RESET_CODE_PACKET_ERROR */
398
399
400
401
402
403
404
405
406
407
408
409
410
411
412
413
}

static int dccp_rcv_respond_partopen_state_process(struct sock *sk,
						   struct sk_buff *skb,
						   const struct dccp_hdr *dh,
						   const unsigned len)
{
	int queued = 0;

	switch (dh->dccph_type) {
	case DCCP_PKT_RESET:
		inet_csk_clear_xmit_timer(sk, ICSK_TIME_DACK);
		break;
	case DCCP_PKT_DATAACK:
	case DCCP_PKT_ACK:
		/*
414
415
416
417
418
419
		 * FIXME: we should be reseting the PARTOPEN (DELACK) timer
		 * here but only if we haven't used the DELACK timer for
		 * something else, like sending a delayed ack for a TIMESTAMP
		 * echo, etc, for now were not clearing it, sending an extra
		 * ACK when there is nothing else to do in DELACK is not a big
		 * deal after all.
420
421
422
423
424
425
426
427
428
429
430
		 */

		/* Stop the PARTOPEN timer */
		if (sk->sk_state == DCCP_PARTOPEN)
			inet_csk_clear_xmit_timer(sk, ICSK_TIME_DACK);

		dccp_sk(sk)->dccps_osr = DCCP_SKB_CB(skb)->dccpd_seq;
		dccp_set_state(sk, DCCP_OPEN);

		if (dh->dccph_type == DCCP_PKT_DATAACK) {
			dccp_rcv_established(sk, skb, dh, len);
431
432
			queued = 1; /* packet was queued
				       (by dccp_rcv_established) */
433
434
435
436
437
438
439
440
441
442
443
444
445
446
		}
		break;
	}

	return queued;
}

int dccp_rcv_state_process(struct sock *sk, struct sk_buff *skb,
			   struct dccp_hdr *dh, unsigned len)
{
	struct dccp_sock *dp = dccp_sk(sk);
	const int old_state = sk->sk_state;
	int queued = 0;

447
448
449
450
451
452
453
454
455
456
457
458
459
460
461
462
463
464
465
466
467
468
469
470
471
472
473
474
475
476
477
478
479
480
481
482
483
484
485
486
487
488
	/*
	 *  Step 3: Process LISTEN state
	 *  	(Continuing from dccp_v4_do_rcv and dccp_v6_do_rcv)
	 *
	 *     If S.state == LISTEN,
	 *	  If P.type == Request or P contains a valid Init Cookie
	 *	  	option,
	 *	     * Must scan the packet's options to check for an Init
	 *		Cookie.  Only the Init Cookie is processed here,
	 *		however; other options are processed in Step 8.  This
	 *		scan need only be performed if the endpoint uses Init
	 *		Cookies *
	 *	     * Generate a new socket and switch to that socket *
	 *	     Set S := new socket for this port pair
	 *	     S.state = RESPOND
	 *	     Choose S.ISS (initial seqno) or set from Init Cookie
	 *	     Set S.ISR, S.GSR, S.SWL, S.SWH from packet or Init Cookie
	 *	     Continue with S.state == RESPOND
	 *	     * A Response packet will be generated in Step 11 *
	 *	  Otherwise,
	 *	     Generate Reset(No Connection) unless P.type == Reset
	 *	     Drop packet and return
	 *
	 * NOTE: the check for the packet types is done in
	 *	 dccp_rcv_state_process
	 */
	if (sk->sk_state == DCCP_LISTEN) {
		if (dh->dccph_type == DCCP_PKT_REQUEST) {
			if (dccp_v4_conn_request(sk, skb) < 0)
				return 1;

			/* FIXME: do congestion control initialization */
			goto discard;
		}
		if (dh->dccph_type == DCCP_PKT_RESET)
			goto discard;

		/* Caller (dccp_v4_do_rcv) will send Reset(No Connection)*/
		return 1;
	}

	if (sk->sk_state != DCCP_REQUESTING) {
489
490
491
492
493
494
495
496
497
		if (dccp_check_seqno(sk, skb))
			goto discard;

		/*
		 * Step 8: Process options and mark acknowledgeable
		 */
		if (dccp_parse_options(sk, skb))
			goto discard;

498
499
		if (DCCP_SKB_CB(skb)->dccpd_ack_seq !=
		    DCCP_PKT_WITHOUT_ACK_SEQ)
500
501
502
503
504
505
506
507
508
509
510
511
512
513
514
			dccp_event_ack_recv(sk, skb);

		ccid_hc_rx_packet_recv(dp->dccps_hc_rx_ccid, sk, skb);
		ccid_hc_tx_packet_recv(dp->dccps_hc_tx_ccid, sk, skb);

		/*
		 * FIXME: check ECN to see if we should use
		 * DCCP_ACKPKTS_STATE_ECN_MARKED
		 */
		if (dp->dccps_options.dccpo_send_ack_vector) {
			if (dccp_ackpkts_add(dp->dccps_hc_rx_ackpkts,
					     DCCP_SKB_CB(skb)->dccpd_seq,
					     DCCP_ACKPKTS_STATE_RECEIVED))
				goto discard;
			/*
515
516
517
			 * FIXME: this activation is probably wrong, have to
			 * study more TCP delack machinery and how it fits into
			 * DCCP draft, but for now it kinda "works" 8)
518
			 */
519
520
			if ((dp->dccps_hc_rx_ackpkts->dccpap_ack_seqno ==
			     DCCP_MAX_SEQNO + 1) &&
521
522
			    !inet_csk_ack_scheduled(sk)) {
				inet_csk_schedule_ack(sk);
523
524
525
				inet_csk_reset_xmit_timer(sk, ICSK_TIME_DACK,
							  TCP_DELACK_MIN,
							  DCCP_RTO_MAX);
526
527
528
529
530
531
532
533
534
535
536
537
538
			}
		}
	}

	/*
	 *  Step 9: Process Reset
	 *	If P.type == Reset,
	 *		Tear down connection
	 *		S.state := TIMEWAIT
	 *		Set TIMEWAIT timer
	 *		Drop packet and return
	*/
	if (dh->dccph_type == DCCP_PKT_RESET) {
539
540
541
542
		/*
		 * Queue the equivalent of TCP fin so that dccp_recvmsg
		 * exits the loop
		 */
543
544
545
546
547
548
549
550
551
552
553
554
555
		dccp_fin(sk, skb);
		dccp_time_wait(sk, DCCP_TIME_WAIT, 0);
		return 0;
		/*
		 *   Step 7: Check for unexpected packet types
		 *      If (S.is_server and P.type == CloseReq)
		 *	    or (S.is_server and P.type == Response)
		 *	    or (S.is_client and P.type == Request)
		 *	    or (S.state == RESPOND and P.type == Data),
		 *	  Send Sync packet acknowledging P.seqno
		 *	  Drop packet and return
		 */
	} else if ((dp->dccps_role != DCCP_ROLE_CLIENT &&
556
557
		    (dh->dccph_type == DCCP_PKT_RESPONSE ||
		     dh->dccph_type == DCCP_PKT_CLOSEREQ)) ||
558
559
		    (dp->dccps_role == DCCP_ROLE_CLIENT &&
		     dh->dccph_type == DCCP_PKT_REQUEST) ||
560
561
		    (sk->sk_state == DCCP_RESPOND &&
		     dh->dccph_type == DCCP_PKT_DATA)) {
562
563
		dccp_send_sync(sk, DCCP_SKB_CB(skb)->dccpd_seq,
			       DCCP_PKT_SYNC);
564
565
566
567
568
569
570
571
572
573
574
575
576
577
578
579
580
581
582
		goto discard;
	}

	switch (sk->sk_state) {
	case DCCP_CLOSED:
		return 1;

	case DCCP_REQUESTING:
		/* FIXME: do congestion control initialization */

		queued = dccp_rcv_request_sent_state_process(sk, skb, dh, len);
		if (queued >= 0)
			return queued;

		__kfree_skb(skb);
		return 0;

	case DCCP_RESPOND:
	case DCCP_PARTOPEN:
583
584
		queued = dccp_rcv_respond_partopen_state_process(sk, skb,
								 dh, len);
585
586
587
		break;
	}

588
589
	if (dh->dccph_type == DCCP_PKT_ACK ||
	    dh->dccph_type == DCCP_PKT_DATAACK) {
590
591
592
593
594
595
596
597
598
599
600
601
602
603
		switch (old_state) {
		case DCCP_PARTOPEN:
			sk->sk_state_change(sk);
			sk_wake_async(sk, 0, POLL_OUT);
			break;
		}
	}

	if (!queued) { 
discard:
		__kfree_skb(skb);
	}
	return 0;
}