b859722fba72f619448f0f80c33ae5279fe0db63
[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 static u8 dccp_feat_is_valid_nn_val(u8 feat_num, u64 val)
304 {
305         switch (feat_num) {
306         case DCCPF_ACK_RATIO:
307                 return val <= DCCPF_ACK_RATIO_MAX;
308         case DCCPF_SEQUENCE_WINDOW:
309                 return val >= DCCPF_SEQ_WMIN && val <= DCCPF_SEQ_WMAX;
310         }
311         return 0;       /* feature unknown - so we can't tell */
312 }
313
314 /* check that SP values are within the ranges defined in RFC 4340 */
315 static u8 dccp_feat_is_valid_sp_val(u8 feat_num, u8 val)
316 {
317         switch (feat_num) {
318         case DCCPF_CCID:
319                 return val == DCCPC_CCID2 || val == DCCPC_CCID3;
320         /* Type-check Boolean feature values: */
321         case DCCPF_SHORT_SEQNOS:
322         case DCCPF_ECN_INCAPABLE:
323         case DCCPF_SEND_ACK_VECTOR:
324         case DCCPF_SEND_NDP_COUNT:
325         case DCCPF_DATA_CHECKSUM:
326         case DCCPF_SEND_LEV_RATE:
327                 return val < 2;
328         case DCCPF_MIN_CSUM_COVER:
329                 return val < 16;
330         }
331         return 0;                       /* feature unknown */
332 }
333
334 static u8 dccp_feat_sp_list_ok(u8 feat_num, u8 const *sp_list, u8 sp_len)
335 {
336         if (sp_list == NULL || sp_len < 1)
337                 return 0;
338         while (sp_len--)
339                 if (!dccp_feat_is_valid_sp_val(feat_num, *sp_list++))
340                         return 0;
341         return 1;
342 }
343
344 /**
345  * __feat_register_nn  -  Register new NN value on socket
346  * @fn: feature-negotiation list to register with
347  * @feat: an NN feature from %dccp_feature_numbers
348  * @mandatory: use Mandatory option if 1
349  * @nn_val: value to register (restricted to 4 bytes)
350  * Note that NN features are local by definition (RFC 4340, 6.3.2).
351  */
352 static int __feat_register_nn(struct list_head *fn, u8 feat,
353                               u8 mandatory, u64 nn_val)
354 {
355         dccp_feat_val fval = { .nn = nn_val };
356
357         if (dccp_feat_type(feat) != FEAT_NN ||
358             !dccp_feat_is_valid_nn_val(feat, nn_val))
359                 return -EINVAL;
360
361         /* Don't bother with default values, they will be activated anyway. */
362         if (nn_val - (u64)dccp_feat_default_value(feat) == 0)
363                 return 0;
364
365         return dccp_feat_push_change(fn, feat, 1, mandatory, &fval);
366 }
367
368 /**
369  * __feat_register_sp  -  Register new SP value/list on socket
370  * @fn: feature-negotiation list to register with
371  * @feat: an SP feature from %dccp_feature_numbers
372  * @is_local: whether the local (1) or the remote (0) @feat is meant
373  * @mandatory: use Mandatory option if 1
374  * @sp_val: SP value followed by optional preference list
375  * @sp_len: length of @sp_val in bytes
376  */
377 static int __feat_register_sp(struct list_head *fn, u8 feat, u8 is_local,
378                               u8 mandatory, u8 const *sp_val, u8 sp_len)
379 {
380         dccp_feat_val fval;
381
382         if (dccp_feat_type(feat) != FEAT_SP ||
383             !dccp_feat_sp_list_ok(feat, sp_val, sp_len))
384                 return -EINVAL;
385
386         if (dccp_feat_clone_sp_val(&fval, sp_val, sp_len))
387                 return -ENOMEM;
388
389         return dccp_feat_push_change(fn, feat, is_local, mandatory, &fval);
390 }
391
392 int dccp_feat_change(struct dccp_minisock *dmsk, u8 type, u8 feature,
393                      u8 *val, u8 len, gfp_t gfp)
394 {
395         struct dccp_opt_pend *opt;
396
397         dccp_feat_debug(type, feature, *val);
398
399         if (len > 3) {
400                 DCCP_WARN("invalid length %d\n", len);
401                 return -EINVAL;
402         }
403         /* XXX add further sanity checks */
404
405         /* check if that feature is already being negotiated */
406         list_for_each_entry(opt, &dmsk->dccpms_pending, dccpop_node) {
407                 /* ok we found a negotiation for this option already */
408                 if (opt->dccpop_feat == feature && opt->dccpop_type == type) {
409                         dccp_pr_debug("Replacing old\n");
410                         /* replace */
411                         BUG_ON(opt->dccpop_val == NULL);
412                         kfree(opt->dccpop_val);
413                         opt->dccpop_val  = val;
414                         opt->dccpop_len  = len;
415                         opt->dccpop_conf = 0;
416                         return 0;
417                 }
418         }
419
420         /* negotiation for a new feature */
421         opt = kmalloc(sizeof(*opt), gfp);
422         if (opt == NULL)
423                 return -ENOMEM;
424
425         opt->dccpop_type = type;
426         opt->dccpop_feat = feature;
427         opt->dccpop_len  = len;
428         opt->dccpop_val  = val;
429         opt->dccpop_conf = 0;
430         opt->dccpop_sc   = NULL;
431
432         BUG_ON(opt->dccpop_val == NULL);
433
434         list_add_tail(&opt->dccpop_node, &dmsk->dccpms_pending);
435         return 0;
436 }
437
438 EXPORT_SYMBOL_GPL(dccp_feat_change);
439
440 static int dccp_feat_update_ccid(struct sock *sk, u8 type, u8 new_ccid_nr)
441 {
442         struct dccp_sock *dp = dccp_sk(sk);
443         struct dccp_minisock *dmsk = dccp_msk(sk);
444         /* figure out if we are changing our CCID or the peer's */
445         const int rx = type == DCCPO_CHANGE_R;
446         const u8 ccid_nr = rx ? dmsk->dccpms_rx_ccid : dmsk->dccpms_tx_ccid;
447         struct ccid *new_ccid;
448
449         /* Check if nothing is being changed. */
450         if (ccid_nr == new_ccid_nr)
451                 return 0;
452
453         new_ccid = ccid_new(new_ccid_nr, sk, rx, GFP_ATOMIC);
454         if (new_ccid == NULL)
455                 return -ENOMEM;
456
457         if (rx) {
458                 ccid_hc_rx_delete(dp->dccps_hc_rx_ccid, sk);
459                 dp->dccps_hc_rx_ccid = new_ccid;
460                 dmsk->dccpms_rx_ccid = new_ccid_nr;
461         } else {
462                 ccid_hc_tx_delete(dp->dccps_hc_tx_ccid, sk);
463                 dp->dccps_hc_tx_ccid = new_ccid;
464                 dmsk->dccpms_tx_ccid = new_ccid_nr;
465         }
466
467         return 0;
468 }
469
470 static int dccp_feat_update(struct sock *sk, u8 type, u8 feat, u8 val)
471 {
472         dccp_feat_debug(type, feat, val);
473
474         switch (feat) {
475         case DCCPF_CCID:
476                 return dccp_feat_update_ccid(sk, type, val);
477         default:
478                 dccp_pr_debug("UNIMPLEMENTED: %s(%d, ...)\n",
479                               dccp_feat_typename(type), feat);
480                 break;
481         }
482         return 0;
483 }
484
485 static int dccp_feat_reconcile(struct sock *sk, struct dccp_opt_pend *opt,
486                                u8 *rpref, u8 rlen)
487 {
488         struct dccp_sock *dp = dccp_sk(sk);
489         u8 *spref, slen, *res = NULL;
490         int i, j, rc, agree = 1;
491
492         BUG_ON(rpref == NULL);
493
494         /* check if we are the black sheep */
495         if (dp->dccps_role == DCCP_ROLE_CLIENT) {
496                 spref = rpref;
497                 slen  = rlen;
498                 rpref = opt->dccpop_val;
499                 rlen  = opt->dccpop_len;
500         } else {
501                 spref = opt->dccpop_val;
502                 slen  = opt->dccpop_len;
503         }
504         /*
505          * Now we have server preference list in spref and client preference in
506          * rpref
507          */
508         BUG_ON(spref == NULL);
509         BUG_ON(rpref == NULL);
510
511         /* FIXME sanity check vals */
512
513         /* Are values in any order?  XXX Lame "algorithm" here */
514         for (i = 0; i < slen; i++) {
515                 for (j = 0; j < rlen; j++) {
516                         if (spref[i] == rpref[j]) {
517                                 res = &spref[i];
518                                 break;
519                         }
520                 }
521                 if (res)
522                         break;
523         }
524
525         /* we didn't agree on anything */
526         if (res == NULL) {
527                 /* confirm previous value */
528                 switch (opt->dccpop_feat) {
529                 case DCCPF_CCID:
530                         /* XXX did i get this right? =P */
531                         if (opt->dccpop_type == DCCPO_CHANGE_L)
532                                 res = &dccp_msk(sk)->dccpms_tx_ccid;
533                         else
534                                 res = &dccp_msk(sk)->dccpms_rx_ccid;
535                         break;
536
537                 default:
538                         DCCP_BUG("Fell through, feat=%d", opt->dccpop_feat);
539                         /* XXX implement res */
540                         return -EFAULT;
541                 }
542
543                 dccp_pr_debug("Don't agree... reconfirming %d\n", *res);
544                 agree = 0; /* this is used for mandatory options... */
545         }
546
547         /* need to put result and our preference list */
548         rlen = 1 + opt->dccpop_len;
549         rpref = kmalloc(rlen, GFP_ATOMIC);
550         if (rpref == NULL)
551                 return -ENOMEM;
552
553         *rpref = *res;
554         memcpy(&rpref[1], opt->dccpop_val, opt->dccpop_len);
555
556         /* put it in the "confirm queue" */
557         if (opt->dccpop_sc == NULL) {
558                 opt->dccpop_sc = kmalloc(sizeof(*opt->dccpop_sc), GFP_ATOMIC);
559                 if (opt->dccpop_sc == NULL) {
560                         kfree(rpref);
561                         return -ENOMEM;
562                 }
563         } else {
564                 /* recycle the confirm slot */
565                 BUG_ON(opt->dccpop_sc->dccpoc_val == NULL);
566                 kfree(opt->dccpop_sc->dccpoc_val);
567                 dccp_pr_debug("recycling confirm slot\n");
568         }
569         memset(opt->dccpop_sc, 0, sizeof(*opt->dccpop_sc));
570
571         opt->dccpop_sc->dccpoc_val = rpref;
572         opt->dccpop_sc->dccpoc_len = rlen;
573
574         /* update the option on our side [we are about to send the confirm] */
575         rc = dccp_feat_update(sk, opt->dccpop_type, opt->dccpop_feat, *res);
576         if (rc) {
577                 kfree(opt->dccpop_sc->dccpoc_val);
578                 kfree(opt->dccpop_sc);
579                 opt->dccpop_sc = NULL;
580                 return rc;
581         }
582
583         dccp_pr_debug("Will confirm %d\n", *rpref);
584
585         /* say we want to change to X but we just got a confirm X, suppress our
586          * change
587          */
588         if (!opt->dccpop_conf) {
589                 if (*opt->dccpop_val == *res)
590                         opt->dccpop_conf = 1;
591                 dccp_pr_debug("won't ask for change of same feature\n");
592         }
593
594         return agree ? 0 : DCCP_FEAT_SP_NOAGREE; /* used for mandatory opts */
595 }
596
597 static int dccp_feat_sp(struct sock *sk, u8 type, u8 feature, u8 *val, u8 len)
598 {
599         struct dccp_minisock *dmsk = dccp_msk(sk);
600         struct dccp_opt_pend *opt;
601         int rc = 1;
602         u8 t;
603
604         /*
605          * We received a CHANGE.  We gotta match it against our own preference
606          * list.  If we got a CHANGE_R it means it's a change for us, so we need
607          * to compare our CHANGE_L list.
608          */
609         if (type == DCCPO_CHANGE_L)
610                 t = DCCPO_CHANGE_R;
611         else
612                 t = DCCPO_CHANGE_L;
613
614         /* find our preference list for this feature */
615         list_for_each_entry(opt, &dmsk->dccpms_pending, dccpop_node) {
616                 if (opt->dccpop_type != t || opt->dccpop_feat != feature)
617                         continue;
618
619                 /* find the winner from the two preference lists */
620                 rc = dccp_feat_reconcile(sk, opt, val, len);
621                 break;
622         }
623
624         /* We didn't deal with the change.  This can happen if we have no
625          * preference list for the feature.  In fact, it just shouldn't
626          * happen---if we understand a feature, we should have a preference list
627          * with at least the default value.
628          */
629         BUG_ON(rc == 1);
630
631         return rc;
632 }
633
634 static int dccp_feat_nn(struct sock *sk, u8 type, u8 feature, u8 *val, u8 len)
635 {
636         struct dccp_opt_pend *opt;
637         struct dccp_minisock *dmsk = dccp_msk(sk);
638         u8 *copy;
639         int rc;
640
641         /* NN features must be Change L (sec. 6.3.2) */
642         if (type != DCCPO_CHANGE_L) {
643                 dccp_pr_debug("received %s for NN feature %d\n",
644                                 dccp_feat_typename(type), feature);
645                 return -EFAULT;
646         }
647
648         /* XXX sanity check opt val */
649
650         /* copy option so we can confirm it */
651         opt = kzalloc(sizeof(*opt), GFP_ATOMIC);
652         if (opt == NULL)
653                 return -ENOMEM;
654
655         copy = kmemdup(val, len, GFP_ATOMIC);
656         if (copy == NULL) {
657                 kfree(opt);
658                 return -ENOMEM;
659         }
660
661         opt->dccpop_type = DCCPO_CONFIRM_R; /* NN can only confirm R */
662         opt->dccpop_feat = feature;
663         opt->dccpop_val  = copy;
664         opt->dccpop_len  = len;
665
666         /* change feature */
667         rc = dccp_feat_update(sk, type, feature, *val);
668         if (rc) {
669                 kfree(opt->dccpop_val);
670                 kfree(opt);
671                 return rc;
672         }
673
674         dccp_feat_debug(type, feature, *copy);
675
676         list_add_tail(&opt->dccpop_node, &dmsk->dccpms_conf);
677
678         return 0;
679 }
680
681 static void dccp_feat_empty_confirm(struct dccp_minisock *dmsk,
682                                     u8 type, u8 feature)
683 {
684         /* XXX check if other confirms for that are queued and recycle slot */
685         struct dccp_opt_pend *opt = kzalloc(sizeof(*opt), GFP_ATOMIC);
686
687         if (opt == NULL) {
688                 /* XXX what do we do?  Ignoring should be fine.  It's a change
689                  * after all =P
690                  */
691                 return;
692         }
693
694         switch (type) {
695         case DCCPO_CHANGE_L:
696                 opt->dccpop_type = DCCPO_CONFIRM_R;
697                 break;
698         case DCCPO_CHANGE_R:
699                 opt->dccpop_type = DCCPO_CONFIRM_L;
700                 break;
701         default:
702                 DCCP_WARN("invalid type %d\n", type);
703                 kfree(opt);
704                 return;
705         }
706         opt->dccpop_feat = feature;
707         opt->dccpop_val  = NULL;
708         opt->dccpop_len  = 0;
709
710         /* change feature */
711         dccp_pr_debug("Empty %s(%d)\n", dccp_feat_typename(type), feature);
712
713         list_add_tail(&opt->dccpop_node, &dmsk->dccpms_conf);
714 }
715
716 static void dccp_feat_flush_confirm(struct sock *sk)
717 {
718         struct dccp_minisock *dmsk = dccp_msk(sk);
719         /* Check if there is anything to confirm in the first place */
720         int yes = !list_empty(&dmsk->dccpms_conf);
721
722         if (!yes) {
723                 struct dccp_opt_pend *opt;
724
725                 list_for_each_entry(opt, &dmsk->dccpms_pending, dccpop_node) {
726                         if (opt->dccpop_conf) {
727                                 yes = 1;
728                                 break;
729                         }
730                 }
731         }
732
733         if (!yes)
734                 return;
735
736         /* OK there is something to confirm... */
737         /* XXX check if packet is in flight?  Send delayed ack?? */
738         if (sk->sk_state == DCCP_OPEN)
739                 dccp_send_ack(sk);
740 }
741
742 int dccp_feat_change_recv(struct sock *sk, u8 type, u8 feature, u8 *val, u8 len)
743 {
744         int rc;
745
746         /* Ignore Change requests other than during connection setup */
747         if (sk->sk_state != DCCP_LISTEN && sk->sk_state != DCCP_REQUESTING)
748                 return 0;
749         dccp_feat_debug(type, feature, *val);
750
751         /* figure out if it's SP or NN feature */
752         switch (feature) {
753         /* deal with SP features */
754         case DCCPF_CCID:
755                 rc = dccp_feat_sp(sk, type, feature, val, len);
756                 break;
757
758         /* deal with NN features */
759         case DCCPF_ACK_RATIO:
760                 rc = dccp_feat_nn(sk, type, feature, val, len);
761                 break;
762
763         /* XXX implement other features */
764         default:
765                 dccp_pr_debug("UNIMPLEMENTED: not handling %s(%d, ...)\n",
766                               dccp_feat_typename(type), feature);
767                 rc = -EFAULT;
768                 break;
769         }
770
771         /* check if there were problems changing features */
772         if (rc) {
773                 /* If we don't agree on SP, we sent a confirm for old value.
774                  * However we propagate rc to caller in case option was
775                  * mandatory
776                  */
777                 if (rc != DCCP_FEAT_SP_NOAGREE)
778                         dccp_feat_empty_confirm(dccp_msk(sk), type, feature);
779         }
780
781         /* generate the confirm [if required] */
782         dccp_feat_flush_confirm(sk);
783
784         return rc;
785 }
786
787 EXPORT_SYMBOL_GPL(dccp_feat_change_recv);
788
789 int dccp_feat_confirm_recv(struct sock *sk, u8 type, u8 feature,
790                            u8 *val, u8 len)
791 {
792         u8 t;
793         struct dccp_opt_pend *opt;
794         struct dccp_minisock *dmsk = dccp_msk(sk);
795         int found = 0;
796         int all_confirmed = 1;
797
798         /* Ignore Confirm options other than during connection setup */
799         if (sk->sk_state != DCCP_LISTEN && sk->sk_state != DCCP_REQUESTING)
800                 return 0;
801         dccp_feat_debug(type, feature, *val);
802
803         /* locate our change request */
804         switch (type) {
805         case DCCPO_CONFIRM_L: t = DCCPO_CHANGE_R; break;
806         case DCCPO_CONFIRM_R: t = DCCPO_CHANGE_L; break;
807         default:              DCCP_WARN("invalid type %d\n", type);
808                               return 1;
809
810         }
811         /* XXX sanity check feature value */
812
813         list_for_each_entry(opt, &dmsk->dccpms_pending, dccpop_node) {
814                 if (!opt->dccpop_conf && opt->dccpop_type == t &&
815                     opt->dccpop_feat == feature) {
816                         found = 1;
817                         dccp_pr_debug("feature %d found\n", opt->dccpop_feat);
818
819                         /* XXX do sanity check */
820
821                         opt->dccpop_conf = 1;
822
823                         /* We got a confirmation---change the option */
824                         dccp_feat_update(sk, opt->dccpop_type,
825                                          opt->dccpop_feat, *val);
826
827                         /* XXX check the return value of dccp_feat_update */
828                         break;
829                 }
830
831                 if (!opt->dccpop_conf)
832                         all_confirmed = 0;
833         }
834
835         if (!found)
836                 dccp_pr_debug("%s(%d, ...) never requested\n",
837                               dccp_feat_typename(type), feature);
838         return 0;
839 }
840
841 EXPORT_SYMBOL_GPL(dccp_feat_confirm_recv);
842
843 void dccp_feat_clean(struct dccp_minisock *dmsk)
844 {
845         struct dccp_opt_pend *opt, *next;
846
847         list_for_each_entry_safe(opt, next, &dmsk->dccpms_pending,
848                                  dccpop_node) {
849                 BUG_ON(opt->dccpop_val == NULL);
850                 kfree(opt->dccpop_val);
851
852                 if (opt->dccpop_sc != NULL) {
853                         BUG_ON(opt->dccpop_sc->dccpoc_val == NULL);
854                         kfree(opt->dccpop_sc->dccpoc_val);
855                         kfree(opt->dccpop_sc);
856                 }
857
858                 kfree(opt);
859         }
860         INIT_LIST_HEAD(&dmsk->dccpms_pending);
861
862         list_for_each_entry_safe(opt, next, &dmsk->dccpms_conf, dccpop_node) {
863                 BUG_ON(opt == NULL);
864                 if (opt->dccpop_val != NULL)
865                         kfree(opt->dccpop_val);
866                 kfree(opt);
867         }
868         INIT_LIST_HEAD(&dmsk->dccpms_conf);
869 }
870
871 EXPORT_SYMBOL_GPL(dccp_feat_clean);
872
873 /* this is to be called only when a listening sock creates its child.  It is
874  * assumed by the function---the confirm is not duplicated, but rather it is
875  * "passed on".
876  */
877 int dccp_feat_clone(struct sock *oldsk, struct sock *newsk)
878 {
879         struct dccp_minisock *olddmsk = dccp_msk(oldsk);
880         struct dccp_minisock *newdmsk = dccp_msk(newsk);
881         struct dccp_opt_pend *opt;
882         int rc = 0;
883
884         INIT_LIST_HEAD(&newdmsk->dccpms_pending);
885         INIT_LIST_HEAD(&newdmsk->dccpms_conf);
886
887         list_for_each_entry(opt, &olddmsk->dccpms_pending, dccpop_node) {
888                 struct dccp_opt_pend *newopt;
889                 /* copy the value of the option */
890                 u8 *val = kmemdup(opt->dccpop_val, opt->dccpop_len, GFP_ATOMIC);
891
892                 if (val == NULL)
893                         goto out_clean;
894
895                 newopt = kmemdup(opt, sizeof(*newopt), GFP_ATOMIC);
896                 if (newopt == NULL) {
897                         kfree(val);
898                         goto out_clean;
899                 }
900
901                 /* insert the option */
902                 newopt->dccpop_val = val;
903                 list_add_tail(&newopt->dccpop_node, &newdmsk->dccpms_pending);
904
905                 /* XXX what happens with backlogs and multiple connections at
906                  * once...
907                  */
908                 /* the master socket no longer needs to worry about confirms */
909                 opt->dccpop_sc = NULL; /* it's not a memleak---new socket has it */
910
911                 /* reset state for a new socket */
912                 opt->dccpop_conf = 0;
913         }
914
915         /* XXX not doing anything about the conf queue */
916
917 out:
918         return rc;
919
920 out_clean:
921         dccp_feat_clean(newdmsk);
922         rc = -ENOMEM;
923         goto out;
924 }
925
926 EXPORT_SYMBOL_GPL(dccp_feat_clone);
927
928 int dccp_feat_init(struct sock *sk)
929 {
930         struct dccp_sock *dp = dccp_sk(sk);
931         struct dccp_minisock *dmsk = dccp_msk(sk);
932         int rc;
933
934         INIT_LIST_HEAD(&dmsk->dccpms_pending);  /* XXX no longer used */
935         INIT_LIST_HEAD(&dmsk->dccpms_conf);     /* XXX no longer used */
936
937         /* CCID L */
938         rc = __feat_register_sp(&dp->dccps_featneg, DCCPF_CCID, 1, 0,
939                                 &dmsk->dccpms_tx_ccid, 1);
940         if (rc)
941                 goto out;
942
943         /* CCID R */
944         rc = __feat_register_sp(&dp->dccps_featneg, DCCPF_CCID, 0, 0,
945                                 &dmsk->dccpms_rx_ccid, 1);
946         if (rc)
947                 goto out;
948
949         /* Ack ratio */
950         rc = __feat_register_nn(&dp->dccps_featneg, DCCPF_ACK_RATIO, 0,
951                                 dmsk->dccpms_ack_ratio);
952 out:
953         return rc;
954 }
955
956 EXPORT_SYMBOL_GPL(dccp_feat_init);
957
958 #ifdef CONFIG_IP_DCCP_DEBUG
959 const char *dccp_feat_typename(const u8 type)
960 {
961         switch(type) {
962         case DCCPO_CHANGE_L:  return("ChangeL");
963         case DCCPO_CONFIRM_L: return("ConfirmL");
964         case DCCPO_CHANGE_R:  return("ChangeR");
965         case DCCPO_CONFIRM_R: return("ConfirmR");
966         /* the following case must not appear in feature negotation  */
967         default:              dccp_pr_debug("unknown type %d [BUG!]\n", type);
968         }
969         return NULL;
970 }
971
972 EXPORT_SYMBOL_GPL(dccp_feat_typename);
973
974 const char *dccp_feat_name(const u8 feat)
975 {
976         static const char *feature_names[] = {
977                 [DCCPF_RESERVED]        = "Reserved",
978                 [DCCPF_CCID]            = "CCID",
979                 [DCCPF_SHORT_SEQNOS]    = "Allow Short Seqnos",
980                 [DCCPF_SEQUENCE_WINDOW] = "Sequence Window",
981                 [DCCPF_ECN_INCAPABLE]   = "ECN Incapable",
982                 [DCCPF_ACK_RATIO]       = "Ack Ratio",
983                 [DCCPF_SEND_ACK_VECTOR] = "Send ACK Vector",
984                 [DCCPF_SEND_NDP_COUNT]  = "Send NDP Count",
985                 [DCCPF_MIN_CSUM_COVER]  = "Min. Csum Coverage",
986                 [DCCPF_DATA_CHECKSUM]   = "Send Data Checksum",
987         };
988         if (feat > DCCPF_DATA_CHECKSUM && feat < DCCPF_MIN_CCID_SPECIFIC)
989                 return feature_names[DCCPF_RESERVED];
990
991         if (feat ==  DCCPF_SEND_LEV_RATE)
992                 return "Send Loss Event Rate";
993         if (feat >= DCCPF_MIN_CCID_SPECIFIC)
994                 return "CCID-specific";
995
996         return feature_names[feat];
997 }
998
999 EXPORT_SYMBOL_GPL(dccp_feat_name);
1000 #endif /* CONFIG_IP_DCCP_DEBUG */