dccp: Limit feature negotiation to connection setup phase
[linux-2.6.git] / net / dccp / feat.c
1 /*
2  *  net/dccp/feat.c
3  *
4  *  An implementation of the DCCP protocol
5  *  Andrea Bittau <a.bittau@cs.ucl.ac.uk>
6  *
7  *  ASSUMPTIONS
8  *  -----------
9  *  o Feature negotiation is coordinated with connection setup (as in TCP), wild
10  *    changes of parameters of an established connection are not supported.
11  *  o All currently known SP features have 1-byte quantities. If in the future
12  *    extensions of RFCs 4340..42 define features with item lengths larger than
13  *    one byte, a feature-specific extension of the code will be required.
14  *
15  *  This program is free software; you can redistribute it and/or
16  *  modify it under the terms of the GNU General Public License
17  *  as published by the Free Software Foundation; either version
18  *  2 of the License, or (at your option) any later version.
19  */
20
21 #include <linux/module.h>
22
23 #include "ccid.h"
24 #include "feat.h"
25
26 #define DCCP_FEAT_SP_NOAGREE (-123)
27
28 static const struct {
29         u8                      feat_num;               /* DCCPF_xxx */
30         enum dccp_feat_type     rxtx;                   /* RX or TX  */
31         enum dccp_feat_type     reconciliation;         /* SP or NN  */
32         u8                      default_value;          /* as in 6.4 */
33 /*
34  *    Lookup table for location and type of features (from RFC 4340/4342)
35  *  +--------------------------+----+-----+----+----+---------+-----------+
36  *  | Feature                  | Location | Reconc. | Initial |  Section  |
37  *  |                          | RX | TX  | SP | NN |  Value  | Reference |
38  *  +--------------------------+----+-----+----+----+---------+-----------+
39  *  | DCCPF_CCID               |    |  X  | X  |    |   2     | 10        |
40  *  | DCCPF_SHORT_SEQNOS       |    |  X  | X  |    |   0     |  7.6.1    |
41  *  | DCCPF_SEQUENCE_WINDOW    |    |  X  |    | X  | 100     |  7.5.2    |
42  *  | DCCPF_ECN_INCAPABLE      | X  |     | X  |    |   0     | 12.1      |
43  *  | DCCPF_ACK_RATIO          |    |  X  |    | X  |   2     | 11.3      |
44  *  | DCCPF_SEND_ACK_VECTOR    | X  |     | X  |    |   0     | 11.5      |
45  *  | DCCPF_SEND_NDP_COUNT     |    |  X  | X  |    |   0     |  7.7.2    |
46  *  | DCCPF_MIN_CSUM_COVER     | X  |     | X  |    |   0     |  9.2.1    |
47  *  | DCCPF_DATA_CHECKSUM      | X  |     | X  |    |   0     |  9.3.1    |
48  *  | DCCPF_SEND_LEV_RATE      | X  |     | X  |    |   0     | 4342/8.4  |
49  *  +--------------------------+----+-----+----+----+---------+-----------+
50  */
51 } dccp_feat_table[] = {
52         { DCCPF_CCID,            FEAT_AT_TX, FEAT_SP, 2 },
53         { DCCPF_SHORT_SEQNOS,    FEAT_AT_TX, FEAT_SP, 0 },
54         { DCCPF_SEQUENCE_WINDOW, FEAT_AT_TX, FEAT_NN, 100 },
55         { DCCPF_ECN_INCAPABLE,   FEAT_AT_RX, FEAT_SP, 0 },
56         { DCCPF_ACK_RATIO,       FEAT_AT_TX, FEAT_NN, 2 },
57         { DCCPF_SEND_ACK_VECTOR, FEAT_AT_RX, FEAT_SP, 0 },
58         { DCCPF_SEND_NDP_COUNT,  FEAT_AT_TX, FEAT_SP, 0 },
59         { DCCPF_MIN_CSUM_COVER,  FEAT_AT_RX, FEAT_SP, 0 },
60         { DCCPF_DATA_CHECKSUM,   FEAT_AT_RX, FEAT_SP, 0 },
61         { DCCPF_SEND_LEV_RATE,   FEAT_AT_RX, FEAT_SP, 0 },
62 };
63 #define DCCP_FEAT_SUPPORTED_MAX         ARRAY_SIZE(dccp_feat_table)
64
65 /**
66  * dccp_feat_index  -  Hash function to map feature number into array position
67  * Returns consecutive array index or -1 if the feature is not understood.
68  */
69 static int dccp_feat_index(u8 feat_num)
70 {
71         /* The first 9 entries are occupied by the types from RFC 4340, 6.4 */
72         if (feat_num > DCCPF_RESERVED && feat_num <= DCCPF_DATA_CHECKSUM)
73                 return feat_num - 1;
74
75         /*
76          * Other features: add cases for new feature types here after adding
77          * them to the above table.
78          */
79         switch (feat_num) {
80         case DCCPF_SEND_LEV_RATE:
81                         return DCCP_FEAT_SUPPORTED_MAX - 1;
82         }
83         return -1;
84 }
85
86 static u8 dccp_feat_type(u8 feat_num)
87 {
88         int idx = dccp_feat_index(feat_num);
89
90         if (idx < 0)
91                 return FEAT_UNKNOWN;
92         return dccp_feat_table[idx].reconciliation;
93 }
94
95 static int dccp_feat_default_value(u8 feat_num)
96 {
97         int idx = dccp_feat_index(feat_num);
98
99         return idx < 0 ? : dccp_feat_table[idx].default_value;
100 }
101
102 /* copy constructor, fval must not already contain allocated memory */
103 static int dccp_feat_clone_sp_val(dccp_feat_val *fval, u8 const *val, u8 len)
104 {
105         fval->sp.len = len;
106         if (fval->sp.len > 0) {
107                 fval->sp.vec = kmemdup(val, len, gfp_any());
108                 if (fval->sp.vec == NULL) {
109                         fval->sp.len = 0;
110                         return -ENOBUFS;
111                 }
112         }
113         return 0;
114 }
115
116 static void dccp_feat_val_destructor(u8 feat_num, dccp_feat_val *val)
117 {
118         if (unlikely(val == NULL))
119                 return;
120         if (dccp_feat_type(feat_num) == FEAT_SP)
121                 kfree(val->sp.vec);
122         memset(val, 0, sizeof(*val));
123 }
124
125 static struct dccp_feat_entry *
126               dccp_feat_clone_entry(struct dccp_feat_entry const *original)
127 {
128         struct dccp_feat_entry *new;
129         u8 type = dccp_feat_type(original->feat_num);
130
131         if (type == FEAT_UNKNOWN)
132                 return NULL;
133
134         new = kmemdup(original, sizeof(struct dccp_feat_entry), gfp_any());
135         if (new == NULL)
136                 return NULL;
137
138         if (type == FEAT_SP && dccp_feat_clone_sp_val(&new->val,
139                                                       original->val.sp.vec,
140                                                       original->val.sp.len)) {
141                 kfree(new);
142                 return NULL;
143         }
144         return new;
145 }
146
147 static void dccp_feat_entry_destructor(struct dccp_feat_entry *entry)
148 {
149         if (entry != NULL) {
150                 dccp_feat_val_destructor(entry->feat_num, &entry->val);
151                 kfree(entry);
152         }
153 }
154
155 /*
156  * List management functions
157  *
158  * Feature negotiation lists rely on and maintain the following invariants:
159  * - each feat_num in the list is known, i.e. we know its type and default value
160  * - each feat_num/is_local combination is unique (old entries are overwritten)
161  * - SP values are always freshly allocated
162  * - list is sorted in increasing order of feature number (faster lookup)
163  */
164 static struct dccp_feat_entry *dccp_feat_list_lookup(struct list_head *fn_list,
165                                                      u8 feat_num, bool is_local)
166 {
167         struct dccp_feat_entry *entry;
168
169         list_for_each_entry(entry, fn_list, node)
170                 if (entry->feat_num == feat_num && entry->is_local == is_local)
171                         return entry;
172                 else if (entry->feat_num > feat_num)
173                         break;
174         return NULL;
175 }
176
177 /**
178  * dccp_feat_entry_new  -  Central list update routine (called by all others)
179  * @head:  list to add to
180  * @feat:  feature number
181  * @local: whether the local (1) or remote feature with number @feat is meant
182  * This is the only constructor and serves to ensure the above invariants.
183  */
184 static struct dccp_feat_entry *
185               dccp_feat_entry_new(struct list_head *head, u8 feat, bool local)
186 {
187         struct dccp_feat_entry *entry;
188
189         list_for_each_entry(entry, head, node)
190                 if (entry->feat_num == feat && entry->is_local == local) {
191                         dccp_feat_val_destructor(entry->feat_num, &entry->val);
192                         return entry;
193                 } else if (entry->feat_num > feat) {
194                         head = &entry->node;
195                         break;
196                 }
197
198         entry = kmalloc(sizeof(*entry), gfp_any());
199         if (entry != NULL) {
200                 entry->feat_num = feat;
201                 entry->is_local = local;
202                 list_add_tail(&entry->node, head);
203         }
204         return entry;
205 }
206
207 /**
208  * dccp_feat_push_change  -  Add/overwrite a Change option in the list
209  * @fn_list: feature-negotiation list to update
210  * @feat: one of %dccp_feature_numbers
211  * @local: whether local (1) or remote (0) @feat_num is meant
212  * @needs_mandatory: whether to use Mandatory feature negotiation options
213  * @fval: pointer to NN/SP value to be inserted (will be copied)
214  */
215 static int dccp_feat_push_change(struct list_head *fn_list, u8 feat, u8 local,
216                                  u8 mandatory, dccp_feat_val *fval)
217 {
218         struct dccp_feat_entry *new = dccp_feat_entry_new(fn_list, feat, local);
219
220         if (new == NULL)
221                 return -ENOMEM;
222
223         new->feat_num        = feat;
224         new->is_local        = local;
225         new->state           = FEAT_INITIALISING;
226         new->needs_confirm   = 0;
227         new->empty_confirm   = 0;
228         new->val             = *fval;
229         new->needs_mandatory = mandatory;
230
231         return 0;
232 }
233
234 /**
235  * dccp_feat_push_confirm  -  Add a Confirm entry to the FN list
236  * @fn_list: feature-negotiation list to add to
237  * @feat: one of %dccp_feature_numbers
238  * @local: whether local (1) or remote (0) @feat_num is being confirmed
239  * @fval: pointer to NN/SP value to be inserted or NULL
240  * Returns 0 on success, a Reset code for further processing otherwise.
241  */
242 static int dccp_feat_push_confirm(struct list_head *fn_list, u8 feat, u8 local,
243                                   dccp_feat_val *fval)
244 {
245         struct dccp_feat_entry *new = dccp_feat_entry_new(fn_list, feat, local);
246
247         if (new == NULL)
248                 return DCCP_RESET_CODE_TOO_BUSY;
249
250         new->feat_num        = feat;
251         new->is_local        = local;
252         new->state           = FEAT_STABLE;     /* transition in 6.6.2 */
253         new->needs_confirm   = 1;
254         new->empty_confirm   = (fval == NULL);
255         new->val.nn          = 0;               /* zeroes the whole structure */
256         if (!new->empty_confirm)
257                 new->val     = *fval;
258         new->needs_mandatory = 0;
259
260         return 0;
261 }
262
263 static int dccp_push_empty_confirm(struct list_head *fn_list, u8 feat, u8 local)
264 {
265         return dccp_feat_push_confirm(fn_list, feat, local, NULL);
266 }
267
268 static inline void dccp_feat_list_pop(struct dccp_feat_entry *entry)
269 {
270         list_del(&entry->node);
271         dccp_feat_entry_destructor(entry);
272 }
273
274 void dccp_feat_list_purge(struct list_head *fn_list)
275 {
276         struct dccp_feat_entry *entry, *next;
277
278         list_for_each_entry_safe(entry, next, fn_list, node)
279                 dccp_feat_entry_destructor(entry);
280         INIT_LIST_HEAD(fn_list);
281 }
282 EXPORT_SYMBOL_GPL(dccp_feat_list_purge);
283
284 /* generate @to as full clone of @from - @to must not contain any nodes */
285 int dccp_feat_clone_list(struct list_head const *from, struct list_head *to)
286 {
287         struct dccp_feat_entry *entry, *new;
288
289         INIT_LIST_HEAD(to);
290         list_for_each_entry(entry, from, node) {
291                 new = dccp_feat_clone_entry(entry);
292                 if (new == NULL)
293                         goto cloning_failed;
294                 list_add_tail(&new->node, to);
295         }
296         return 0;
297
298 cloning_failed:
299         dccp_feat_list_purge(to);
300         return -ENOMEM;
301 }
302
303 int dccp_feat_change(struct dccp_minisock *dmsk, u8 type, u8 feature,
304                      u8 *val, u8 len, gfp_t gfp)
305 {
306         struct dccp_opt_pend *opt;
307
308         dccp_feat_debug(type, feature, *val);
309
310         if (len > 3) {
311                 DCCP_WARN("invalid length %d\n", len);
312                 return -EINVAL;
313         }
314         /* XXX add further sanity checks */
315
316         /* check if that feature is already being negotiated */
317         list_for_each_entry(opt, &dmsk->dccpms_pending, dccpop_node) {
318                 /* ok we found a negotiation for this option already */
319                 if (opt->dccpop_feat == feature && opt->dccpop_type == type) {
320                         dccp_pr_debug("Replacing old\n");
321                         /* replace */
322                         BUG_ON(opt->dccpop_val == NULL);
323                         kfree(opt->dccpop_val);
324                         opt->dccpop_val  = val;
325                         opt->dccpop_len  = len;
326                         opt->dccpop_conf = 0;
327                         return 0;
328                 }
329         }
330
331         /* negotiation for a new feature */
332         opt = kmalloc(sizeof(*opt), gfp);
333         if (opt == NULL)
334                 return -ENOMEM;
335
336         opt->dccpop_type = type;
337         opt->dccpop_feat = feature;
338         opt->dccpop_len  = len;
339         opt->dccpop_val  = val;
340         opt->dccpop_conf = 0;
341         opt->dccpop_sc   = NULL;
342
343         BUG_ON(opt->dccpop_val == NULL);
344
345         list_add_tail(&opt->dccpop_node, &dmsk->dccpms_pending);
346         return 0;
347 }
348
349 EXPORT_SYMBOL_GPL(dccp_feat_change);
350
351 static int dccp_feat_update_ccid(struct sock *sk, u8 type, u8 new_ccid_nr)
352 {
353         struct dccp_sock *dp = dccp_sk(sk);
354         struct dccp_minisock *dmsk = dccp_msk(sk);
355         /* figure out if we are changing our CCID or the peer's */
356         const int rx = type == DCCPO_CHANGE_R;
357         const u8 ccid_nr = rx ? dmsk->dccpms_rx_ccid : dmsk->dccpms_tx_ccid;
358         struct ccid *new_ccid;
359
360         /* Check if nothing is being changed. */
361         if (ccid_nr == new_ccid_nr)
362                 return 0;
363
364         new_ccid = ccid_new(new_ccid_nr, sk, rx, GFP_ATOMIC);
365         if (new_ccid == NULL)
366                 return -ENOMEM;
367
368         if (rx) {
369                 ccid_hc_rx_delete(dp->dccps_hc_rx_ccid, sk);
370                 dp->dccps_hc_rx_ccid = new_ccid;
371                 dmsk->dccpms_rx_ccid = new_ccid_nr;
372         } else {
373                 ccid_hc_tx_delete(dp->dccps_hc_tx_ccid, sk);
374                 dp->dccps_hc_tx_ccid = new_ccid;
375                 dmsk->dccpms_tx_ccid = new_ccid_nr;
376         }
377
378         return 0;
379 }
380
381 static int dccp_feat_update(struct sock *sk, u8 type, u8 feat, u8 val)
382 {
383         dccp_feat_debug(type, feat, val);
384
385         switch (feat) {
386         case DCCPF_CCID:
387                 return dccp_feat_update_ccid(sk, type, val);
388         default:
389                 dccp_pr_debug("UNIMPLEMENTED: %s(%d, ...)\n",
390                               dccp_feat_typename(type), feat);
391                 break;
392         }
393         return 0;
394 }
395
396 static int dccp_feat_reconcile(struct sock *sk, struct dccp_opt_pend *opt,
397                                u8 *rpref, u8 rlen)
398 {
399         struct dccp_sock *dp = dccp_sk(sk);
400         u8 *spref, slen, *res = NULL;
401         int i, j, rc, agree = 1;
402
403         BUG_ON(rpref == NULL);
404
405         /* check if we are the black sheep */
406         if (dp->dccps_role == DCCP_ROLE_CLIENT) {
407                 spref = rpref;
408                 slen  = rlen;
409                 rpref = opt->dccpop_val;
410                 rlen  = opt->dccpop_len;
411         } else {
412                 spref = opt->dccpop_val;
413                 slen  = opt->dccpop_len;
414         }
415         /*
416          * Now we have server preference list in spref and client preference in
417          * rpref
418          */
419         BUG_ON(spref == NULL);
420         BUG_ON(rpref == NULL);
421
422         /* FIXME sanity check vals */
423
424         /* Are values in any order?  XXX Lame "algorithm" here */
425         for (i = 0; i < slen; i++) {
426                 for (j = 0; j < rlen; j++) {
427                         if (spref[i] == rpref[j]) {
428                                 res = &spref[i];
429                                 break;
430                         }
431                 }
432                 if (res)
433                         break;
434         }
435
436         /* we didn't agree on anything */
437         if (res == NULL) {
438                 /* confirm previous value */
439                 switch (opt->dccpop_feat) {
440                 case DCCPF_CCID:
441                         /* XXX did i get this right? =P */
442                         if (opt->dccpop_type == DCCPO_CHANGE_L)
443                                 res = &dccp_msk(sk)->dccpms_tx_ccid;
444                         else
445                                 res = &dccp_msk(sk)->dccpms_rx_ccid;
446                         break;
447
448                 default:
449                         DCCP_BUG("Fell through, feat=%d", opt->dccpop_feat);
450                         /* XXX implement res */
451                         return -EFAULT;
452                 }
453
454                 dccp_pr_debug("Don't agree... reconfirming %d\n", *res);
455                 agree = 0; /* this is used for mandatory options... */
456         }
457
458         /* need to put result and our preference list */
459         rlen = 1 + opt->dccpop_len;
460         rpref = kmalloc(rlen, GFP_ATOMIC);
461         if (rpref == NULL)
462                 return -ENOMEM;
463
464         *rpref = *res;
465         memcpy(&rpref[1], opt->dccpop_val, opt->dccpop_len);
466
467         /* put it in the "confirm queue" */
468         if (opt->dccpop_sc == NULL) {
469                 opt->dccpop_sc = kmalloc(sizeof(*opt->dccpop_sc), GFP_ATOMIC);
470                 if (opt->dccpop_sc == NULL) {
471                         kfree(rpref);
472                         return -ENOMEM;
473                 }
474         } else {
475                 /* recycle the confirm slot */
476                 BUG_ON(opt->dccpop_sc->dccpoc_val == NULL);
477                 kfree(opt->dccpop_sc->dccpoc_val);
478                 dccp_pr_debug("recycling confirm slot\n");
479         }
480         memset(opt->dccpop_sc, 0, sizeof(*opt->dccpop_sc));
481
482         opt->dccpop_sc->dccpoc_val = rpref;
483         opt->dccpop_sc->dccpoc_len = rlen;
484
485         /* update the option on our side [we are about to send the confirm] */
486         rc = dccp_feat_update(sk, opt->dccpop_type, opt->dccpop_feat, *res);
487         if (rc) {
488                 kfree(opt->dccpop_sc->dccpoc_val);
489                 kfree(opt->dccpop_sc);
490                 opt->dccpop_sc = NULL;
491                 return rc;
492         }
493
494         dccp_pr_debug("Will confirm %d\n", *rpref);
495
496         /* say we want to change to X but we just got a confirm X, suppress our
497          * change
498          */
499         if (!opt->dccpop_conf) {
500                 if (*opt->dccpop_val == *res)
501                         opt->dccpop_conf = 1;
502                 dccp_pr_debug("won't ask for change of same feature\n");
503         }
504
505         return agree ? 0 : DCCP_FEAT_SP_NOAGREE; /* used for mandatory opts */
506 }
507
508 static int dccp_feat_sp(struct sock *sk, u8 type, u8 feature, u8 *val, u8 len)
509 {
510         struct dccp_minisock *dmsk = dccp_msk(sk);
511         struct dccp_opt_pend *opt;
512         int rc = 1;
513         u8 t;
514
515         /*
516          * We received a CHANGE.  We gotta match it against our own preference
517          * list.  If we got a CHANGE_R it means it's a change for us, so we need
518          * to compare our CHANGE_L list.
519          */
520         if (type == DCCPO_CHANGE_L)
521                 t = DCCPO_CHANGE_R;
522         else
523                 t = DCCPO_CHANGE_L;
524
525         /* find our preference list for this feature */
526         list_for_each_entry(opt, &dmsk->dccpms_pending, dccpop_node) {
527                 if (opt->dccpop_type != t || opt->dccpop_feat != feature)
528                         continue;
529
530                 /* find the winner from the two preference lists */
531                 rc = dccp_feat_reconcile(sk, opt, val, len);
532                 break;
533         }
534
535         /* We didn't deal with the change.  This can happen if we have no
536          * preference list for the feature.  In fact, it just shouldn't
537          * happen---if we understand a feature, we should have a preference list
538          * with at least the default value.
539          */
540         BUG_ON(rc == 1);
541
542         return rc;
543 }
544
545 static int dccp_feat_nn(struct sock *sk, u8 type, u8 feature, u8 *val, u8 len)
546 {
547         struct dccp_opt_pend *opt;
548         struct dccp_minisock *dmsk = dccp_msk(sk);
549         u8 *copy;
550         int rc;
551
552         /* NN features must be Change L (sec. 6.3.2) */
553         if (type != DCCPO_CHANGE_L) {
554                 dccp_pr_debug("received %s for NN feature %d\n",
555                                 dccp_feat_typename(type), feature);
556                 return -EFAULT;
557         }
558
559         /* XXX sanity check opt val */
560
561         /* copy option so we can confirm it */
562         opt = kzalloc(sizeof(*opt), GFP_ATOMIC);
563         if (opt == NULL)
564                 return -ENOMEM;
565
566         copy = kmemdup(val, len, GFP_ATOMIC);
567         if (copy == NULL) {
568                 kfree(opt);
569                 return -ENOMEM;
570         }
571
572         opt->dccpop_type = DCCPO_CONFIRM_R; /* NN can only confirm R */
573         opt->dccpop_feat = feature;
574         opt->dccpop_val  = copy;
575         opt->dccpop_len  = len;
576
577         /* change feature */
578         rc = dccp_feat_update(sk, type, feature, *val);
579         if (rc) {
580                 kfree(opt->dccpop_val);
581                 kfree(opt);
582                 return rc;
583         }
584
585         dccp_feat_debug(type, feature, *copy);
586
587         list_add_tail(&opt->dccpop_node, &dmsk->dccpms_conf);
588
589         return 0;
590 }
591
592 static void dccp_feat_empty_confirm(struct dccp_minisock *dmsk,
593                                     u8 type, u8 feature)
594 {
595         /* XXX check if other confirms for that are queued and recycle slot */
596         struct dccp_opt_pend *opt = kzalloc(sizeof(*opt), GFP_ATOMIC);
597
598         if (opt == NULL) {
599                 /* XXX what do we do?  Ignoring should be fine.  It's a change
600                  * after all =P
601                  */
602                 return;
603         }
604
605         switch (type) {
606         case DCCPO_CHANGE_L:
607                 opt->dccpop_type = DCCPO_CONFIRM_R;
608                 break;
609         case DCCPO_CHANGE_R:
610                 opt->dccpop_type = DCCPO_CONFIRM_L;
611                 break;
612         default:
613                 DCCP_WARN("invalid type %d\n", type);
614                 kfree(opt);
615                 return;
616         }
617         opt->dccpop_feat = feature;
618         opt->dccpop_val  = NULL;
619         opt->dccpop_len  = 0;
620
621         /* change feature */
622         dccp_pr_debug("Empty %s(%d)\n", dccp_feat_typename(type), feature);
623
624         list_add_tail(&opt->dccpop_node, &dmsk->dccpms_conf);
625 }
626
627 static void dccp_feat_flush_confirm(struct sock *sk)
628 {
629         struct dccp_minisock *dmsk = dccp_msk(sk);
630         /* Check if there is anything to confirm in the first place */
631         int yes = !list_empty(&dmsk->dccpms_conf);
632
633         if (!yes) {
634                 struct dccp_opt_pend *opt;
635
636                 list_for_each_entry(opt, &dmsk->dccpms_pending, dccpop_node) {
637                         if (opt->dccpop_conf) {
638                                 yes = 1;
639                                 break;
640                         }
641                 }
642         }
643
644         if (!yes)
645                 return;
646
647         /* OK there is something to confirm... */
648         /* XXX check if packet is in flight?  Send delayed ack?? */
649         if (sk->sk_state == DCCP_OPEN)
650                 dccp_send_ack(sk);
651 }
652
653 int dccp_feat_change_recv(struct sock *sk, u8 type, u8 feature, u8 *val, u8 len)
654 {
655         int rc;
656
657         /* Ignore Change requests other than during connection setup */
658         if (sk->sk_state != DCCP_LISTEN && sk->sk_state != DCCP_REQUESTING)
659                 return 0;
660         dccp_feat_debug(type, feature, *val);
661
662         /* figure out if it's SP or NN feature */
663         switch (feature) {
664         /* deal with SP features */
665         case DCCPF_CCID:
666                 rc = dccp_feat_sp(sk, type, feature, val, len);
667                 break;
668
669         /* deal with NN features */
670         case DCCPF_ACK_RATIO:
671                 rc = dccp_feat_nn(sk, type, feature, val, len);
672                 break;
673
674         /* XXX implement other features */
675         default:
676                 dccp_pr_debug("UNIMPLEMENTED: not handling %s(%d, ...)\n",
677                               dccp_feat_typename(type), feature);
678                 rc = -EFAULT;
679                 break;
680         }
681
682         /* check if there were problems changing features */
683         if (rc) {
684                 /* If we don't agree on SP, we sent a confirm for old value.
685                  * However we propagate rc to caller in case option was
686                  * mandatory
687                  */
688                 if (rc != DCCP_FEAT_SP_NOAGREE)
689                         dccp_feat_empty_confirm(dccp_msk(sk), type, feature);
690         }
691
692         /* generate the confirm [if required] */
693         dccp_feat_flush_confirm(sk);
694
695         return rc;
696 }
697
698 EXPORT_SYMBOL_GPL(dccp_feat_change_recv);
699
700 int dccp_feat_confirm_recv(struct sock *sk, u8 type, u8 feature,
701                            u8 *val, u8 len)
702 {
703         u8 t;
704         struct dccp_opt_pend *opt;
705         struct dccp_minisock *dmsk = dccp_msk(sk);
706         int found = 0;
707         int all_confirmed = 1;
708
709         /* Ignore Confirm options other than during connection setup */
710         if (sk->sk_state != DCCP_LISTEN && sk->sk_state != DCCP_REQUESTING)
711                 return 0;
712         dccp_feat_debug(type, feature, *val);
713
714         /* locate our change request */
715         switch (type) {
716         case DCCPO_CONFIRM_L: t = DCCPO_CHANGE_R; break;
717         case DCCPO_CONFIRM_R: t = DCCPO_CHANGE_L; break;
718         default:              DCCP_WARN("invalid type %d\n", type);
719                               return 1;
720
721         }
722         /* XXX sanity check feature value */
723
724         list_for_each_entry(opt, &dmsk->dccpms_pending, dccpop_node) {
725                 if (!opt->dccpop_conf && opt->dccpop_type == t &&
726                     opt->dccpop_feat == feature) {
727                         found = 1;
728                         dccp_pr_debug("feature %d found\n", opt->dccpop_feat);
729
730                         /* XXX do sanity check */
731
732                         opt->dccpop_conf = 1;
733
734                         /* We got a confirmation---change the option */
735                         dccp_feat_update(sk, opt->dccpop_type,
736                                          opt->dccpop_feat, *val);
737
738                         /* XXX check the return value of dccp_feat_update */
739                         break;
740                 }
741
742                 if (!opt->dccpop_conf)
743                         all_confirmed = 0;
744         }
745
746         if (!found)
747                 dccp_pr_debug("%s(%d, ...) never requested\n",
748                               dccp_feat_typename(type), feature);
749         return 0;
750 }
751
752 EXPORT_SYMBOL_GPL(dccp_feat_confirm_recv);
753
754 void dccp_feat_clean(struct dccp_minisock *dmsk)
755 {
756         struct dccp_opt_pend *opt, *next;
757
758         list_for_each_entry_safe(opt, next, &dmsk->dccpms_pending,
759                                  dccpop_node) {
760                 BUG_ON(opt->dccpop_val == NULL);
761                 kfree(opt->dccpop_val);
762
763                 if (opt->dccpop_sc != NULL) {
764                         BUG_ON(opt->dccpop_sc->dccpoc_val == NULL);
765                         kfree(opt->dccpop_sc->dccpoc_val);
766                         kfree(opt->dccpop_sc);
767                 }
768
769                 kfree(opt);
770         }
771         INIT_LIST_HEAD(&dmsk->dccpms_pending);
772
773         list_for_each_entry_safe(opt, next, &dmsk->dccpms_conf, dccpop_node) {
774                 BUG_ON(opt == NULL);
775                 if (opt->dccpop_val != NULL)
776                         kfree(opt->dccpop_val);
777                 kfree(opt);
778         }
779         INIT_LIST_HEAD(&dmsk->dccpms_conf);
780 }
781
782 EXPORT_SYMBOL_GPL(dccp_feat_clean);
783
784 /* this is to be called only when a listening sock creates its child.  It is
785  * assumed by the function---the confirm is not duplicated, but rather it is
786  * "passed on".
787  */
788 int dccp_feat_clone(struct sock *oldsk, struct sock *newsk)
789 {
790         struct dccp_minisock *olddmsk = dccp_msk(oldsk);
791         struct dccp_minisock *newdmsk = dccp_msk(newsk);
792         struct dccp_opt_pend *opt;
793         int rc = 0;
794
795         INIT_LIST_HEAD(&newdmsk->dccpms_pending);
796         INIT_LIST_HEAD(&newdmsk->dccpms_conf);
797
798         list_for_each_entry(opt, &olddmsk->dccpms_pending, dccpop_node) {
799                 struct dccp_opt_pend *newopt;
800                 /* copy the value of the option */
801                 u8 *val = kmemdup(opt->dccpop_val, opt->dccpop_len, GFP_ATOMIC);
802
803                 if (val == NULL)
804                         goto out_clean;
805
806                 newopt = kmemdup(opt, sizeof(*newopt), GFP_ATOMIC);
807                 if (newopt == NULL) {
808                         kfree(val);
809                         goto out_clean;
810                 }
811
812                 /* insert the option */
813                 newopt->dccpop_val = val;
814                 list_add_tail(&newopt->dccpop_node, &newdmsk->dccpms_pending);
815
816                 /* XXX what happens with backlogs and multiple connections at
817                  * once...
818                  */
819                 /* the master socket no longer needs to worry about confirms */
820                 opt->dccpop_sc = NULL; /* it's not a memleak---new socket has it */
821
822                 /* reset state for a new socket */
823                 opt->dccpop_conf = 0;
824         }
825
826         /* XXX not doing anything about the conf queue */
827
828 out:
829         return rc;
830
831 out_clean:
832         dccp_feat_clean(newdmsk);
833         rc = -ENOMEM;
834         goto out;
835 }
836
837 EXPORT_SYMBOL_GPL(dccp_feat_clone);
838
839 static int __dccp_feat_init(struct dccp_minisock *dmsk, u8 type, u8 feat,
840                             u8 *val, u8 len)
841 {
842         int rc = -ENOMEM;
843         u8 *copy = kmemdup(val, len, GFP_KERNEL);
844
845         if (copy != NULL) {
846                 rc = dccp_feat_change(dmsk, type, feat, copy, len, GFP_KERNEL);
847                 if (rc)
848                         kfree(copy);
849         }
850         return rc;
851 }
852
853 int dccp_feat_init(struct dccp_minisock *dmsk)
854 {
855         int rc;
856
857         INIT_LIST_HEAD(&dmsk->dccpms_pending);
858         INIT_LIST_HEAD(&dmsk->dccpms_conf);
859
860         /* CCID L */
861         rc = __dccp_feat_init(dmsk, DCCPO_CHANGE_L, DCCPF_CCID,
862                               &dmsk->dccpms_tx_ccid, 1);
863         if (rc)
864                 goto out;
865
866         /* CCID R */
867         rc = __dccp_feat_init(dmsk, DCCPO_CHANGE_R, DCCPF_CCID,
868                               &dmsk->dccpms_rx_ccid, 1);
869         if (rc)
870                 goto out;
871
872         /* Ack ratio */
873         rc = __dccp_feat_init(dmsk, DCCPO_CHANGE_L, DCCPF_ACK_RATIO,
874                               &dmsk->dccpms_ack_ratio, 1);
875 out:
876         return rc;
877 }
878
879 EXPORT_SYMBOL_GPL(dccp_feat_init);
880
881 #ifdef CONFIG_IP_DCCP_DEBUG
882 const char *dccp_feat_typename(const u8 type)
883 {
884         switch(type) {
885         case DCCPO_CHANGE_L:  return("ChangeL");
886         case DCCPO_CONFIRM_L: return("ConfirmL");
887         case DCCPO_CHANGE_R:  return("ChangeR");
888         case DCCPO_CONFIRM_R: return("ConfirmR");
889         /* the following case must not appear in feature negotation  */
890         default:              dccp_pr_debug("unknown type %d [BUG!]\n", type);
891         }
892         return NULL;
893 }
894
895 EXPORT_SYMBOL_GPL(dccp_feat_typename);
896
897 const char *dccp_feat_name(const u8 feat)
898 {
899         static const char *feature_names[] = {
900                 [DCCPF_RESERVED]        = "Reserved",
901                 [DCCPF_CCID]            = "CCID",
902                 [DCCPF_SHORT_SEQNOS]    = "Allow Short Seqnos",
903                 [DCCPF_SEQUENCE_WINDOW] = "Sequence Window",
904                 [DCCPF_ECN_INCAPABLE]   = "ECN Incapable",
905                 [DCCPF_ACK_RATIO]       = "Ack Ratio",
906                 [DCCPF_SEND_ACK_VECTOR] = "Send ACK Vector",
907                 [DCCPF_SEND_NDP_COUNT]  = "Send NDP Count",
908                 [DCCPF_MIN_CSUM_COVER]  = "Min. Csum Coverage",
909                 [DCCPF_DATA_CHECKSUM]   = "Send Data Checksum",
910         };
911         if (feat > DCCPF_DATA_CHECKSUM && feat < DCCPF_MIN_CCID_SPECIFIC)
912                 return feature_names[DCCPF_RESERVED];
913
914         if (feat ==  DCCPF_SEND_LEV_RATE)
915                 return "Send Loss Event Rate";
916         if (feat >= DCCPF_MIN_CCID_SPECIFIC)
917                 return "CCID-specific";
918
919         return feature_names[feat];
920 }
921
922 EXPORT_SYMBOL_GPL(dccp_feat_name);
923 #endif /* CONFIG_IP_DCCP_DEBUG */