summaryrefslogtreecommitdiff
path: root/net/dccp/feat.c
blob: 0e789e2e0aa9538314f0ec6e5d736c7bcf80db57 (plain)
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
96
97
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
126
127
128
129
130
131
132
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
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
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
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
312
313
314
315
316
317
318
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
354
355
356
357
358
359
360
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
396
397
398
399
400
401
402
403
404
405
406
407
408
409
410
411
412
413
414
415
416
417
418
419
420
421
422
423
424
425
426
427
428
429
430
431
432
433
434
435
436
437
438
439
440
441
442
443
444
445
446
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
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
516
517
518
519
520
521
522
523
524
525
526
527
528
529
530
531
532
533
534
535
536
537
538
539
540
541
542
543
544
545
546
547
548
549
550
551
552
553
554
555
556
557
558
559
560
561
562
563
564
565
566
567
568
569
570
571
572
573
574
575
576
577
578
579
580
581
582
583
584
585
586
587
588
589
590
591
592
593
594
595
596
597
598
599
600
601
602
603
604
605
606
607
608
609
610
611
612
613
614
615
616
617
618
619
620
621
622
623
624
625
626
627
628
629
630
631
632
633
634
635
636
637
638
639
640
641
642
643
644
645
646
647
648
649
650
651
652
653
654
655
656
657
658
659
660
661
662
663
664
665
666
667
668
669
670
671
672
673
674
675
676
677
678
679
680
681
682
683
684
685
686
687
688
689
690
691
692
693
694
695
696
697
698
699
700
701
702
703
704
705
706
707
708
709
710
711
712
713
714
715
716
717
718
719
720
721
722
723
724
725
726
727
728
729
730
731
732
733
734
735
736
737
738
739
740
741
742
743
744
745
746
747
748
749
750
751
752
753
754
755
756
757
758
759
760
761
762
763
764
765
766
767
768
769
770
771
772
773
774
775
776
777
778
779
780
781
782
783
784
785
786
787
788
789
790
791
792
793
794
795
796
797
798
799
800
801
802
803
804
805
806
807
808
809
810
811
812
813
/*
 *  net/dccp/feat.c
 *
 *  An implementation of the DCCP protocol
 *  Andrea Bittau <a.bittau@cs.ucl.ac.uk>
 *
 *  ASSUMPTIONS
 *  -----------
 *  o Feature negotiation is coordinated with connection setup (as in TCP), wild
 *    changes of parameters of an established connection are not supported.
 *  o All currently known SP features have 1-byte quantities. If in the future
 *    extensions of RFCs 4340..42 define features with item lengths larger than
 *    one byte, a feature-specific extension of the code will be required.
 *
 *  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/module.h>

#include "ccid.h"
#include "feat.h"

#define DCCP_FEAT_SP_NOAGREE (-123)

static const struct {
	u8			feat_num;		/* DCCPF_xxx */
	enum dccp_feat_type	rxtx;			/* RX or TX  */
	enum dccp_feat_type	reconciliation;		/* SP or NN  */
	u8			default_value;		/* as in 6.4 */
/*
 *    Lookup table for location and type of features (from RFC 4340/4342)
 *  +--------------------------+----+-----+----+----+---------+-----------+
 *  | Feature                  | Location | Reconc. | Initial |  Section  |
 *  |                          | RX | TX  | SP | NN |  Value  | Reference |
 *  +--------------------------+----+-----+----+----+---------+-----------+
 *  | DCCPF_CCID               |    |  X  | X  |    |   2     | 10        |
 *  | DCCPF_SHORT_SEQNOS       |    |  X  | X  |    |   0     |  7.6.1    |
 *  | DCCPF_SEQUENCE_WINDOW    |    |  X  |    | X  | 100     |  7.5.2    |
 *  | DCCPF_ECN_INCAPABLE      | X  |     | X  |    |   0     | 12.1      |
 *  | DCCPF_ACK_RATIO          |    |  X  |    | X  |   2     | 11.3      |
 *  | DCCPF_SEND_ACK_VECTOR    | X  |     | X  |    |   0     | 11.5      |
 *  | DCCPF_SEND_NDP_COUNT     |    |  X  | X  |    |   0     |  7.7.2    |
 *  | DCCPF_MIN_CSUM_COVER     | X  |     | X  |    |   0     |  9.2.1    |
 *  | DCCPF_DATA_CHECKSUM      | X  |     | X  |    |   0     |  9.3.1    |
 *  | DCCPF_SEND_LEV_RATE      | X  |     | X  |    |   0     | 4342/8.4  |
 *  +--------------------------+----+-----+----+----+---------+-----------+
 */
} dccp_feat_table[] = {
	{ DCCPF_CCID,		 FEAT_AT_TX, FEAT_SP, 2 },
	{ DCCPF_SHORT_SEQNOS,	 FEAT_AT_TX, FEAT_SP, 0 },
	{ DCCPF_SEQUENCE_WINDOW, FEAT_AT_TX, FEAT_NN, 100 },
	{ DCCPF_ECN_INCAPABLE,	 FEAT_AT_RX, FEAT_SP, 0 },
	{ DCCPF_ACK_RATIO,	 FEAT_AT_TX, FEAT_NN, 2 },
	{ DCCPF_SEND_ACK_VECTOR, FEAT_AT_RX, FEAT_SP, 0 },
	{ DCCPF_SEND_NDP_COUNT,  FEAT_AT_TX, FEAT_SP, 0 },
	{ DCCPF_MIN_CSUM_COVER,  FEAT_AT_RX, FEAT_SP, 0 },
	{ DCCPF_DATA_CHECKSUM,	 FEAT_AT_RX, FEAT_SP, 0 },
	{ DCCPF_SEND_LEV_RATE,	 FEAT_AT_RX, FEAT_SP, 0 },
};
#define DCCP_FEAT_SUPPORTED_MAX		ARRAY_SIZE(dccp_feat_table)

/**
 * dccp_feat_index  -  Hash function to map feature number into array position
 * Returns consecutive array index or -1 if the feature is not understood.
 */
static int dccp_feat_index(u8 feat_num)
{
	/* The first 9 entries are occupied by the types from RFC 4340, 6.4 */
	if (feat_num > DCCPF_RESERVED && feat_num <= DCCPF_DATA_CHECKSUM)
		return feat_num - 1;

	/*
	 * Other features: add cases for new feature types here after adding
	 * them to the above table.
	 */
	switch (feat_num) {
	case DCCPF_SEND_LEV_RATE:
			return DCCP_FEAT_SUPPORTED_MAX - 1;
	}
	return -1;
}

static u8 dccp_feat_type(u8 feat_num)
{
	int idx = dccp_feat_index(feat_num);

	if (idx < 0)
		return FEAT_UNKNOWN;
	return dccp_feat_table[idx].reconciliation;
}

/* copy constructor, fval must not already contain allocated memory */
static int dccp_feat_clone_sp_val(dccp_feat_val *fval, u8 const *val, u8 len)
{
	fval->sp.len = len;
	if (fval->sp.len > 0) {
		fval->sp.vec = kmemdup(val, len, gfp_any());
		if (fval->sp.vec == NULL) {
			fval->sp.len = 0;
			return -ENOBUFS;
		}
	}
	return 0;
}

static void dccp_feat_val_destructor(u8 feat_num, dccp_feat_val *val)
{
	if (unlikely(val == NULL))
		return;
	if (dccp_feat_type(feat_num) == FEAT_SP)
		kfree(val->sp.vec);
	memset(val, 0, sizeof(*val));
}

static struct dccp_feat_entry *
	      dccp_feat_clone_entry(struct dccp_feat_entry const *original)
{
	struct dccp_feat_entry *new;
	u8 type = dccp_feat_type(original->feat_num);

	if (type == FEAT_UNKNOWN)
		return NULL;

	new = kmemdup(original, sizeof(struct dccp_feat_entry), gfp_any());
	if (new == NULL)
		return NULL;

	if (type == FEAT_SP && dccp_feat_clone_sp_val(&new->val,
						      original->val.sp.vec,
						      original->val.sp.len)) {
		kfree(new);
		return NULL;
	}
	return new;
}

static void dccp_feat_entry_destructor(struct dccp_feat_entry *entry)
{
	if (entry != NULL) {
		dccp_feat_val_destructor(entry->feat_num, &entry->val);
		kfree(entry);
	}
}

/*
 * List management functions
 *
 * Feature negotiation lists rely on and maintain the following invariants:
 * - each feat_num in the list is known, i.e. we know its type and default value
 * - each feat_num/is_local combination is unique (old entries are overwritten)
 * - SP values are always freshly allocated
 * - list is sorted in increasing order of feature number (faster lookup)
 */

static inline void dccp_feat_list_pop(struct dccp_feat_entry *entry)
{
	list_del(&entry->node);
	dccp_feat_entry_destructor(entry);
}

void dccp_feat_list_purge(struct list_head *fn_list)
{
	struct dccp_feat_entry *entry, *next;

	list_for_each_entry_safe(entry, next, fn_list, node)
		dccp_feat_entry_destructor(entry);
	INIT_LIST_HEAD(fn_list);
}
EXPORT_SYMBOL_GPL(dccp_feat_list_purge);

/* generate @to as full clone of @from - @to must not contain any nodes */
int dccp_feat_clone_list(struct list_head const *from, struct list_head *to)
{
	struct dccp_feat_entry *entry, *new;

	INIT_LIST_HEAD(to);
	list_for_each_entry(entry, from, node) {
		new = dccp_feat_clone_entry(entry);
		if (new == NULL)
			goto cloning_failed;
		list_add_tail(&new->node, to);
	}
	return 0;

cloning_failed:
	dccp_feat_list_purge(to);
	return -ENOMEM;
}

int dccp_feat_change(struct dccp_minisock *dmsk, u8 type, u8 feature,
		     u8 *val, u8 len, gfp_t gfp)
{
	struct dccp_opt_pend *opt;

	dccp_feat_debug(type, feature, *val);

	if (len > 3) {
		DCCP_WARN("invalid length %d\n", len);
		return -EINVAL;
	}
	/* XXX add further sanity checks */

	/* check if that feature is already being negotiated */
	list_for_each_entry(opt, &dmsk->dccpms_pending, dccpop_node) {
		/* ok we found a negotiation for this option already */
		if (opt->dccpop_feat == feature && opt->dccpop_type == type) {
			dccp_pr_debug("Replacing old\n");
			/* replace */
			BUG_ON(opt->dccpop_val == NULL);
			kfree(opt->dccpop_val);
			opt->dccpop_val	 = val;
			opt->dccpop_len	 = len;
			opt->dccpop_conf = 0;
			return 0;
		}
	}

	/* negotiation for a new feature */
	opt = kmalloc(sizeof(*opt), gfp);
	if (opt == NULL)
		return -ENOMEM;

	opt->dccpop_type = type;
	opt->dccpop_feat = feature;
	opt->dccpop_len	 = len;
	opt->dccpop_val	 = val;
	opt->dccpop_conf = 0;
	opt->dccpop_sc	 = NULL;

	BUG_ON(opt->dccpop_val == NULL);

	list_add_tail(&opt->dccpop_node, &dmsk->dccpms_pending);
	return 0;
}

EXPORT_SYMBOL_GPL(dccp_feat_change);

static int dccp_feat_update_ccid(struct sock *sk, u8 type, u8 new_ccid_nr)
{
	struct dccp_sock *dp = dccp_sk(sk);
	struct dccp_minisock *dmsk = dccp_msk(sk);
	/* figure out if we are changing our CCID or the peer's */
	const int rx = type == DCCPO_CHANGE_R;
	const u8 ccid_nr = rx ? dmsk->dccpms_rx_ccid : dmsk->dccpms_tx_ccid;
	struct ccid *new_ccid;

	/* Check if nothing is being changed. */
	if (ccid_nr == new_ccid_nr)
		return 0;

	new_ccid = ccid_new(new_ccid_nr, sk, rx, GFP_ATOMIC);
	if (new_ccid == NULL)
		return -ENOMEM;

	if (rx) {
		ccid_hc_rx_delete(dp->dccps_hc_rx_ccid, sk);
		dp->dccps_hc_rx_ccid = new_ccid;
		dmsk->dccpms_rx_ccid = new_ccid_nr;
	} else {
		ccid_hc_tx_delete(dp->dccps_hc_tx_ccid, sk);
		dp->dccps_hc_tx_ccid = new_ccid;
		dmsk->dccpms_tx_ccid = new_ccid_nr;
	}

	return 0;
}

static int dccp_feat_update(struct sock *sk, u8 type, u8 feat, u8 val)
{
	dccp_feat_debug(type, feat, val);

	switch (feat) {
	case DCCPF_CCID:
		return dccp_feat_update_ccid(sk, type, val);
	default:
		dccp_pr_debug("UNIMPLEMENTED: %s(%d, ...)\n",
			      dccp_feat_typename(type), feat);
		break;
	}
	return 0;
}

static int dccp_feat_reconcile(struct sock *sk, struct dccp_opt_pend *opt,
			       u8 *rpref, u8 rlen)
{
	struct dccp_sock *dp = dccp_sk(sk);
	u8 *spref, slen, *res = NULL;
	int i, j, rc, agree = 1;

	BUG_ON(rpref == NULL);

	/* check if we are the black sheep */
	if (dp->dccps_role == DCCP_ROLE_CLIENT) {
		spref = rpref;
		slen  = rlen;
		rpref = opt->dccpop_val;
		rlen  = opt->dccpop_len;
	} else {
		spref = opt->dccpop_val;
		slen  = opt->dccpop_len;
	}
	/*
	 * Now we have server preference list in spref and client preference in
	 * rpref
	 */
	BUG_ON(spref == NULL);
	BUG_ON(rpref == NULL);

	/* FIXME sanity check vals */

	/* Are values in any order?  XXX Lame "algorithm" here */
	for (i = 0; i < slen; i++) {
		for (j = 0; j < rlen; j++) {
			if (spref[i] == rpref[j]) {
				res = &spref[i];
				break;
			}
		}
		if (res)
			break;
	}

	/* we didn't agree on anything */
	if (res == NULL) {
		/* confirm previous value */
		switch (opt->dccpop_feat) {
		case DCCPF_CCID:
			/* XXX did i get this right? =P */
			if (opt->dccpop_type == DCCPO_CHANGE_L)
				res = &dccp_msk(sk)->dccpms_tx_ccid;
			else
				res = &dccp_msk(sk)->dccpms_rx_ccid;
			break;

		default:
			DCCP_BUG("Fell through, feat=%d", opt->dccpop_feat);
			/* XXX implement res */
			return -EFAULT;
		}

		dccp_pr_debug("Don't agree... reconfirming %d\n", *res);
		agree = 0; /* this is used for mandatory options... */
	}

	/* need to put result and our preference list */
	rlen = 1 + opt->dccpop_len;
	rpref = kmalloc(rlen, GFP_ATOMIC);
	if (rpref == NULL)
		return -ENOMEM;

	*rpref = *res;
	memcpy(&rpref[1], opt->dccpop_val, opt->dccpop_len);

	/* put it in the "confirm queue" */
	if (opt->dccpop_sc == NULL) {
		opt->dccpop_sc = kmalloc(sizeof(*opt->dccpop_sc), GFP_ATOMIC);
		if (opt->dccpop_sc == NULL) {
			kfree(rpref);
			return -ENOMEM;
		}
	} else {
		/* recycle the confirm slot */
		BUG_ON(opt->dccpop_sc->dccpoc_val == NULL);
		kfree(opt->dccpop_sc->dccpoc_val);
		dccp_pr_debug("recycling confirm slot\n");
	}
	memset(opt->dccpop_sc, 0, sizeof(*opt->dccpop_sc));

	opt->dccpop_sc->dccpoc_val = rpref;
	opt->dccpop_sc->dccpoc_len = rlen;

	/* update the option on our side [we are about to send the confirm] */
	rc = dccp_feat_update(sk, opt->dccpop_type, opt->dccpop_feat, *res);
	if (rc) {
		kfree(opt->dccpop_sc->dccpoc_val);
		kfree(opt->dccpop_sc);
		opt->dccpop_sc = NULL;
		return rc;
	}

	dccp_pr_debug("Will confirm %d\n", *rpref);

	/* say we want to change to X but we just got a confirm X, suppress our
	 * change
	 */
	if (!opt->dccpop_conf) {
		if (*opt->dccpop_val == *res)
			opt->dccpop_conf = 1;
		dccp_pr_debug("won't ask for change of same feature\n");
	}

	return agree ? 0 : DCCP_FEAT_SP_NOAGREE; /* used for mandatory opts */
}

static int dccp_feat_sp(struct sock *sk, u8 type, u8 feature, u8 *val, u8 len)
{
	struct dccp_minisock *dmsk = dccp_msk(sk);
	struct dccp_opt_pend *opt;
	int rc = 1;
	u8 t;

	/*
	 * We received a CHANGE.  We gotta match it against our own preference
	 * list.  If we got a CHANGE_R it means it's a change for us, so we need
	 * to compare our CHANGE_L list.
	 */
	if (type == DCCPO_CHANGE_L)
		t = DCCPO_CHANGE_R;
	else
		t = DCCPO_CHANGE_L;

	/* find our preference list for this feature */
	list_for_each_entry(opt, &dmsk->dccpms_pending, dccpop_node) {
		if (opt->dccpop_type != t || opt->dccpop_feat != feature)
			continue;

		/* find the winner from the two preference lists */
		rc = dccp_feat_reconcile(sk, opt, val, len);
		break;
	}

	/* We didn't deal with the change.  This can happen if we have no
	 * preference list for the feature.  In fact, it just shouldn't
	 * happen---if we understand a feature, we should have a preference list
	 * with at least the default value.
	 */
	BUG_ON(rc == 1);

	return rc;
}

static int dccp_feat_nn(struct sock *sk, u8 type, u8 feature, u8 *val, u8 len)
{
	struct dccp_opt_pend *opt;
	struct dccp_minisock *dmsk = dccp_msk(sk);
	u8 *copy;
	int rc;

	/* NN features must be Change L (sec. 6.3.2) */
	if (type != DCCPO_CHANGE_L) {
		dccp_pr_debug("received %s for NN feature %d\n",
				dccp_feat_typename(type), feature);
		return -EFAULT;
	}

	/* XXX sanity check opt val */

	/* copy option so we can confirm it */
	opt = kzalloc(sizeof(*opt), GFP_ATOMIC);
	if (opt == NULL)
		return -ENOMEM;

	copy = kmemdup(val, len, GFP_ATOMIC);
	if (copy == NULL) {
		kfree(opt);
		return -ENOMEM;
	}

	opt->dccpop_type = DCCPO_CONFIRM_R; /* NN can only confirm R */
	opt->dccpop_feat = feature;
	opt->dccpop_val	 = copy;
	opt->dccpop_len	 = len;

	/* change feature */
	rc = dccp_feat_update(sk, type, feature, *val);
	if (rc) {
		kfree(opt->dccpop_val);
		kfree(opt);
		return rc;
	}

	dccp_feat_debug(type, feature, *copy);

	list_add_tail(&opt->dccpop_node, &dmsk->dccpms_conf);

	return 0;
}

static void dccp_feat_empty_confirm(struct dccp_minisock *dmsk,
				    u8 type, u8 feature)
{
	/* XXX check if other confirms for that are queued and recycle slot */
	struct dccp_opt_pend *opt = kzalloc(sizeof(*opt), GFP_ATOMIC);

	if (opt == NULL) {
		/* XXX what do we do?  Ignoring should be fine.  It's a change
		 * after all =P
		 */
		return;
	}

	switch (type) {
	case DCCPO_CHANGE_L:
		opt->dccpop_type = DCCPO_CONFIRM_R;
		break;
	case DCCPO_CHANGE_R:
		opt->dccpop_type = DCCPO_CONFIRM_L;
		break;
	default:
		DCCP_WARN("invalid type %d\n", type);
		kfree(opt);
		return;
	}
	opt->dccpop_feat = feature;
	opt->dccpop_val	 = NULL;
	opt->dccpop_len	 = 0;

	/* change feature */
	dccp_pr_debug("Empty %s(%d)\n", dccp_feat_typename(type), feature);

	list_add_tail(&opt->dccpop_node, &dmsk->dccpms_conf);
}

static void dccp_feat_flush_confirm(struct sock *sk)
{
	struct dccp_minisock *dmsk = dccp_msk(sk);
	/* Check if there is anything to confirm in the first place */
	int yes = !list_empty(&dmsk->dccpms_conf);

	if (!yes) {
		struct dccp_opt_pend *opt;

		list_for_each_entry(opt, &dmsk->dccpms_pending, dccpop_node) {
			if (opt->dccpop_conf) {
				yes = 1;
				break;
			}
		}
	}

	if (!yes)
		return;

	/* OK there is something to confirm... */
	/* XXX check if packet is in flight?  Send delayed ack?? */
	if (sk->sk_state == DCCP_OPEN)
		dccp_send_ack(sk);
}

int dccp_feat_change_recv(struct sock *sk, u8 type, u8 feature, u8 *val, u8 len)
{
	int rc;

	/* Ignore Change requests other than during connection setup */
	if (sk->sk_state != DCCP_LISTEN && sk->sk_state != DCCP_REQUESTING)
		return 0;
	dccp_feat_debug(type, feature, *val);

	/* figure out if it's SP or NN feature */
	switch (feature) {
	/* deal with SP features */
	case DCCPF_CCID:
		rc = dccp_feat_sp(sk, type, feature, val, len);
		break;

	/* deal with NN features */
	case DCCPF_ACK_RATIO:
		rc = dccp_feat_nn(sk, type, feature, val, len);
		break;

	/* XXX implement other features */
	default:
		dccp_pr_debug("UNIMPLEMENTED: not handling %s(%d, ...)\n",
			      dccp_feat_typename(type), feature);
		rc = -EFAULT;
		break;
	}

	/* check if there were problems changing features */
	if (rc) {
		/* If we don't agree on SP, we sent a confirm for old value.
		 * However we propagate rc to caller in case option was
		 * mandatory
		 */
		if (rc != DCCP_FEAT_SP_NOAGREE)
			dccp_feat_empty_confirm(dccp_msk(sk), type, feature);
	}

	/* generate the confirm [if required] */
	dccp_feat_flush_confirm(sk);

	return rc;
}

EXPORT_SYMBOL_GPL(dccp_feat_change_recv);

int dccp_feat_confirm_recv(struct sock *sk, u8 type, u8 feature,
			   u8 *val, u8 len)
{
	u8 t;
	struct dccp_opt_pend *opt;
	struct dccp_minisock *dmsk = dccp_msk(sk);
	int found = 0;
	int all_confirmed = 1;

	/* Ignore Confirm options other than during connection setup */
	if (sk->sk_state != DCCP_LISTEN && sk->sk_state != DCCP_REQUESTING)
		return 0;
	dccp_feat_debug(type, feature, *val);

	/* locate our change request */
	switch (type) {
	case DCCPO_CONFIRM_L: t = DCCPO_CHANGE_R; break;
	case DCCPO_CONFIRM_R: t = DCCPO_CHANGE_L; break;
	default:	      DCCP_WARN("invalid type %d\n", type);
			      return 1;

	}
	/* XXX sanity check feature value */

	list_for_each_entry(opt, &dmsk->dccpms_pending, dccpop_node) {
		if (!opt->dccpop_conf && opt->dccpop_type == t &&
		    opt->dccpop_feat == feature) {
			found = 1;
			dccp_pr_debug("feature %d found\n", opt->dccpop_feat);

			/* XXX do sanity check */

			opt->dccpop_conf = 1;

			/* We got a confirmation---change the option */
			dccp_feat_update(sk, opt->dccpop_type,
					 opt->dccpop_feat, *val);

			/* XXX check the return value of dccp_feat_update */
			break;
		}

		if (!opt->dccpop_conf)
			all_confirmed = 0;
	}

	if (!found)
		dccp_pr_debug("%s(%d, ...) never requested\n",
			      dccp_feat_typename(type), feature);
	return 0;
}

EXPORT_SYMBOL_GPL(dccp_feat_confirm_recv);

void dccp_feat_clean(struct dccp_minisock *dmsk)
{
	struct dccp_opt_pend *opt, *next;

	list_for_each_entry_safe(opt, next, &dmsk->dccpms_pending,
				 dccpop_node) {
		BUG_ON(opt->dccpop_val == NULL);
		kfree(opt->dccpop_val);

		if (opt->dccpop_sc != NULL) {
			BUG_ON(opt->dccpop_sc->dccpoc_val == NULL);
			kfree(opt->dccpop_sc->dccpoc_val);
			kfree(opt->dccpop_sc);
		}

		kfree(opt);
	}
	INIT_LIST_HEAD(&dmsk->dccpms_pending);

	list_for_each_entry_safe(opt, next, &dmsk->dccpms_conf, dccpop_node) {
		BUG_ON(opt == NULL);
		if (opt->dccpop_val != NULL)
			kfree(opt->dccpop_val);
		kfree(opt);
	}
	INIT_LIST_HEAD(&dmsk->dccpms_conf);
}

EXPORT_SYMBOL_GPL(dccp_feat_clean);

/* this is to be called only when a listening sock creates its child.  It is
 * assumed by the function---the confirm is not duplicated, but rather it is
 * "passed on".
 */
int dccp_feat_clone(struct sock *oldsk, struct sock *newsk)
{
	struct dccp_minisock *olddmsk = dccp_msk(oldsk);
	struct dccp_minisock *newdmsk = dccp_msk(newsk);
	struct dccp_opt_pend *opt;
	int rc = 0;

	INIT_LIST_HEAD(&newdmsk->dccpms_pending);
	INIT_LIST_HEAD(&newdmsk->dccpms_conf);

	list_for_each_entry(opt, &olddmsk->dccpms_pending, dccpop_node) {
		struct dccp_opt_pend *newopt;
		/* copy the value of the option */
		u8 *val = kmemdup(opt->dccpop_val, opt->dccpop_len, GFP_ATOMIC);

		if (val == NULL)
			goto out_clean;

		newopt = kmemdup(opt, sizeof(*newopt), GFP_ATOMIC);
		if (newopt == NULL) {
			kfree(val);
			goto out_clean;
		}

		/* insert the option */
		newopt->dccpop_val = val;
		list_add_tail(&newopt->dccpop_node, &newdmsk->dccpms_pending);

		/* XXX what happens with backlogs and multiple connections at
		 * once...
		 */
		/* the master socket no longer needs to worry about confirms */
		opt->dccpop_sc = NULL; /* it's not a memleak---new socket has it */

		/* reset state for a new socket */
		opt->dccpop_conf = 0;
	}

	/* XXX not doing anything about the conf queue */

out:
	return rc;

out_clean:
	dccp_feat_clean(newdmsk);
	rc = -ENOMEM;
	goto out;
}

EXPORT_SYMBOL_GPL(dccp_feat_clone);

static int __dccp_feat_init(struct dccp_minisock *dmsk, u8 type, u8 feat,
			    u8 *val, u8 len)
{
	int rc = -ENOMEM;
	u8 *copy = kmemdup(val, len, GFP_KERNEL);

	if (copy != NULL) {
		rc = dccp_feat_change(dmsk, type, feat, copy, len, GFP_KERNEL);
		if (rc)
			kfree(copy);
	}
	return rc;
}

int dccp_feat_init(struct dccp_minisock *dmsk)
{
	int rc;

	INIT_LIST_HEAD(&dmsk->dccpms_pending);
	INIT_LIST_HEAD(&dmsk->dccpms_conf);

	/* CCID L */
	rc = __dccp_feat_init(dmsk, DCCPO_CHANGE_L, DCCPF_CCID,
			      &dmsk->dccpms_tx_ccid, 1);
	if (rc)
		goto out;

	/* CCID R */
	rc = __dccp_feat_init(dmsk, DCCPO_CHANGE_R, DCCPF_CCID,
			      &dmsk->dccpms_rx_ccid, 1);
	if (rc)
		goto out;

	/* Ack ratio */
	rc = __dccp_feat_init(dmsk, DCCPO_CHANGE_L, DCCPF_ACK_RATIO,
			      &dmsk->dccpms_ack_ratio, 1);
out:
	return rc;
}

EXPORT_SYMBOL_GPL(dccp_feat_init);

#ifdef CONFIG_IP_DCCP_DEBUG
const char *dccp_feat_typename(const u8 type)
{
	switch(type) {
	case DCCPO_CHANGE_L:  return("ChangeL");
	case DCCPO_CONFIRM_L: return("ConfirmL");
	case DCCPO_CHANGE_R:  return("ChangeR");
	case DCCPO_CONFIRM_R: return("ConfirmR");
	/* the following case must not appear in feature negotation  */
	default:	      dccp_pr_debug("unknown type %d [BUG!]\n", type);
	}
	return NULL;
}

EXPORT_SYMBOL_GPL(dccp_feat_typename);

const char *dccp_feat_name(const u8 feat)
{
	static const char *feature_names[] = {
		[DCCPF_RESERVED]	= "Reserved",
		[DCCPF_CCID]		= "CCID",
		[DCCPF_SHORT_SEQNOS]	= "Allow Short Seqnos",
		[DCCPF_SEQUENCE_WINDOW]	= "Sequence Window",
		[DCCPF_ECN_INCAPABLE]	= "ECN Incapable",
		[DCCPF_ACK_RATIO]	= "Ack Ratio",
		[DCCPF_SEND_ACK_VECTOR]	= "Send ACK Vector",
		[DCCPF_SEND_NDP_COUNT]	= "Send NDP Count",
		[DCCPF_MIN_CSUM_COVER]	= "Min. Csum Coverage",
		[DCCPF_DATA_CHECKSUM]	= "Send Data Checksum",
	};
	if (feat > DCCPF_DATA_CHECKSUM && feat < DCCPF_MIN_CCID_SPECIFIC)
		return feature_names[DCCPF_RESERVED];

	if (feat ==  DCCPF_SEND_LEV_RATE)
		return "Send Loss Event Rate";
	if (feat >= DCCPF_MIN_CCID_SPECIFIC)
		return "CCID-specific";

	return feature_names[feat];
}

EXPORT_SYMBOL_GPL(dccp_feat_name);
#endif /* CONFIG_IP_DCCP_DEBUG */