input.c 14.7 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
53
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
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
/*
 *  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) {
		dccp_send_sync(sk, DCCP_SKB_CB(skb)->dccpd_seq);
		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);
	u64 lswl = dp->dccps_swl;
	u64 lawl = dp->dccps_awl;

	/*
	 *   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) {
96
97
		if (between48(DCCP_SKB_CB(skb)->dccpd_ack_seq,
			      dp->dccps_awl, dp->dccps_awh) &&
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
		    !before48(DCCP_SKB_CB(skb)->dccpd_seq, dp->dccps_swl))
			dccp_update_gsr(sk, DCCP_SKB_CB(skb)->dccpd_seq);
		else
			return -1;
	/*
	 *   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
	 */
	} else if (dh->dccph_type == DCCP_PKT_CLOSEREQ ||
		   dh->dccph_type == DCCP_PKT_CLOSE ||
		   dh->dccph_type == DCCP_PKT_RESET) {
		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 ||
126
127
	     between48(DCCP_SKB_CB(skb)->dccpd_ack_seq,
		       lawl, dp->dccps_awh))) {
128
129
130
		dccp_update_gsr(sk, DCCP_SKB_CB(skb)->dccpd_seq);

		if (dh->dccph_type != DCCP_PKT_SYNC &&
131
132
		    (DCCP_SKB_CB(skb)->dccpd_ack_seq !=
		     DCCP_PKT_WITHOUT_ACK_SEQ))
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
			dp->dccps_gar = DCCP_SKB_CB(skb)->dccpd_ack_seq;
	} else {
		dccp_pr_debug("Step 6 failed, sending SYNC...\n");
		dccp_send_sync(sk, DCCP_SKB_CB(skb)->dccpd_seq);
		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)) {
167
168
			LIMIT_NETDEBUG(KERN_INFO "DCCP: acknowledgeable "
						 "packets buffer full!\n");
169
170
			ap->dccpap_ack_seqno = DCCP_MAX_SEQNO + 1;
			inet_csk_schedule_ack(sk);
171
172
173
			inet_csk_reset_xmit_timer(sk, ICSK_TIME_DACK,
						  TCP_DELACK_MIN,
						  DCCP_RTO_MAX);
174
175
176
177
178
179
180
181
182
183
			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);
184
185
			inet_csk_reset_xmit_timer(sk, ICSK_TIME_DACK, 5 * HZ,
						  DCCP_RTO_MAX);
186
187
188
189
190
191
192
193
194
195
		}
	}

	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:
		/*
196
197
		 * FIXME: check if sk_receive_queue is full, schedule DATA_DROPPED
		 * option if it is.
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
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
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
		 */
		__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:
			dccp_send_sync(sk, DCCP_SKB_CB(skb)->dccpd_seq);
		}
		break;
	}

	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;

282
283
284
285
286
287
288
		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);
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
			goto out_invalid_packet;
		}

		dp->dccps_isr = DCCP_SKB_CB(skb)->dccpd_seq;
		dccp_update_gsr(sk, DCCP_SKB_CB(skb)->dccpd_seq);

		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,
308
309
310
311
312
313
		 *	  / * 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 * /
314
315
316
		 *	  S.state := PARTOPEN
		 *	  Set PARTOPEN timer
		 * 	  Continue with S.state == PARTOPEN
317
318
		 *	  / * Step 12 will send the Ack completing the
		 *	      three-way handshake * /
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
		 */
		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...
354
355
		     FIXME: the reset code should be
			    DCCP_RESET_CODE_PACKET_ERROR */
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
}

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:
		/*
372
373
374
375
376
377
		 * 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.
378
379
380
381
382
383
384
385
386
387
388
		 */

		/* 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);
389
390
			queued = 1; /* packet was queued
				       (by dccp_rcv_established) */
391
392
393
394
395
396
397
398
399
400
401
402
403
404
405
406
407
408
409
410
411
412
413
414
		}
		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;

	if (sk->sk_state != DCCP_LISTEN && sk->sk_state != DCCP_REQUESTING) {
		if (dccp_check_seqno(sk, skb))
			goto discard;

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

415
416
		if (DCCP_SKB_CB(skb)->dccpd_ack_seq !=
		    DCCP_PKT_WITHOUT_ACK_SEQ)
417
418
419
420
421
422
423
424
425
426
427
428
429
430
431
			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;
			/*
432
433
434
			 * 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)
435
			 */
436
437
			if ((dp->dccps_hc_rx_ackpkts->dccpap_ack_seqno ==
			     DCCP_MAX_SEQNO + 1) &&
438
439
			    !inet_csk_ack_scheduled(sk)) {
				inet_csk_schedule_ack(sk);
440
441
442
				inet_csk_reset_xmit_timer(sk, ICSK_TIME_DACK,
							  TCP_DELACK_MIN,
							  DCCP_RTO_MAX);
443
444
445
446
447
448
449
450
451
452
453
454
455
			}
		}
	}

	/*
	 *  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) {
456
457
458
459
		/*
		 * Queue the equivalent of TCP fin so that dccp_recvmsg
		 * exits the loop
		 */
460
461
462
463
464
465
466
467
468
469
470
471
472
		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 &&
473
474
		    (dh->dccph_type == DCCP_PKT_RESPONSE ||
		     dh->dccph_type == DCCP_PKT_CLOSEREQ)) ||
475
476
		    (dp->dccps_role == DCCP_ROLE_CLIENT &&
		     dh->dccph_type == DCCP_PKT_REQUEST) ||
477
478
		    (sk->sk_state == DCCP_RESPOND &&
		     dh->dccph_type == DCCP_PKT_DATA)) {
479
480
481
482
483
484
485
486
487
488
489
490
491
492
493
494
495
496
497
498
499
500
501
502
503
504
505
506
507
508
509
510
511
512
513
514
515
		dccp_send_sync(sk, DCCP_SKB_CB(skb)->dccpd_seq);
		goto discard;
	}

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

	case DCCP_LISTEN:
		if (dh->dccph_type == DCCP_PKT_ACK ||
		    dh->dccph_type == DCCP_PKT_DATAACK)
			return 1;

		if (dh->dccph_type == DCCP_PKT_RESET)
			goto discard;

		if (dh->dccph_type == DCCP_PKT_REQUEST) {
			if (dccp_v4_conn_request(sk, skb) < 0)
				return 1;

			/* FIXME: do congestion control initialization */
			goto discard;
		}
		goto discard;

	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:
516
517
		queued = dccp_rcv_respond_partopen_state_process(sk, skb,
								 dh, len);
518
519
520
		break;
	}

521
522
	if (dh->dccph_type == DCCP_PKT_ACK ||
	    dh->dccph_type == DCCP_PKT_DATAACK) {
523
524
525
526
527
528
529
530
531
532
533
534
535
536
		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;
}