dccp: Resolve dependencies of features on choice of CCID
[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         /* Avoid negotiating alien CCIDs by only advertising supported ones */
387         if (feat == DCCPF_CCID && !ccid_support_check(sp_val, sp_len))
388                 return -EOPNOTSUPP;
389
390         if (dccp_feat_clone_sp_val(&fval, sp_val, sp_len))
391                 return -ENOMEM;
392
393         return dccp_feat_push_change(fn, feat, is_local, mandatory, &fval);
394 }
395
396 int dccp_feat_change(struct dccp_minisock *dmsk, u8 type, u8 feature,
397                      u8 *val, u8 len, gfp_t gfp)
398 {
399         struct dccp_opt_pend *opt;
400
401         dccp_feat_debug(type, feature, *val);
402
403         if (len > 3) {
404                 DCCP_WARN("invalid length %d\n", len);
405                 return -EINVAL;
406         }
407         /* XXX add further sanity checks */
408
409         /* check if that feature is already being negotiated */
410         list_for_each_entry(opt, &dmsk->dccpms_pending, dccpop_node) {
411                 /* ok we found a negotiation for this option already */
412                 if (opt->dccpop_feat == feature && opt->dccpop_type == type) {
413                         dccp_pr_debug("Replacing old\n");
414                         /* replace */
415                         BUG_ON(opt->dccpop_val == NULL);
416                         kfree(opt->dccpop_val);
417                         opt->dccpop_val  = val;
418                         opt->dccpop_len  = len;
419                         opt->dccpop_conf = 0;
420                         return 0;
421                 }
422         }
423
424         /* negotiation for a new feature */
425         opt = kmalloc(sizeof(*opt), gfp);
426         if (opt == NULL)
427                 return -ENOMEM;
428
429         opt->dccpop_type = type;
430         opt->dccpop_feat = feature;
431         opt->dccpop_len  = len;
432         opt->dccpop_val  = val;
433         opt->dccpop_conf = 0;
434         opt->dccpop_sc   = NULL;
435
436         BUG_ON(opt->dccpop_val == NULL);
437
438         list_add_tail(&opt->dccpop_node, &dmsk->dccpms_pending);
439         return 0;
440 }
441
442 EXPORT_SYMBOL_GPL(dccp_feat_change);
443
444 /*
445  *      Tracking features whose value depend on the choice of CCID
446  *
447  * This is designed with an extension in mind so that a list walk could be done
448  * before activating any features. However, the existing framework was found to
449  * work satisfactorily up until now, the automatic verification is left open.
450  * When adding new CCIDs, add a corresponding dependency table here.
451  */
452 static const struct ccid_dependency *dccp_feat_ccid_deps(u8 ccid, bool is_local)
453 {
454         static const struct ccid_dependency ccid2_dependencies[2][2] = {
455                 /*
456                  * CCID2 mandates Ack Vectors (RFC 4341, 4.): as CCID is a TX
457                  * feature and Send Ack Vector is an RX feature, `is_local'
458                  * needs to be reversed.
459                  */
460                 {       /* Dependencies of the receiver-side (remote) CCID2 */
461                         {
462                                 .dependent_feat = DCCPF_SEND_ACK_VECTOR,
463                                 .is_local       = true,
464                                 .is_mandatory   = true,
465                                 .val            = 1
466                         },
467                         { 0, 0, 0, 0 }
468                 },
469                 {       /* Dependencies of the sender-side (local) CCID2 */
470                         {
471                                 .dependent_feat = DCCPF_SEND_ACK_VECTOR,
472                                 .is_local       = false,
473                                 .is_mandatory   = true,
474                                 .val            = 1
475                         },
476                         { 0, 0, 0, 0 }
477                 }
478         };
479         static const struct ccid_dependency ccid3_dependencies[2][5] = {
480                 {       /*
481                          * Dependencies of the receiver-side CCID3
482                          */
483                         {       /* locally disable Ack Vectors */
484                                 .dependent_feat = DCCPF_SEND_ACK_VECTOR,
485                                 .is_local       = true,
486                                 .is_mandatory   = false,
487                                 .val            = 0
488                         },
489                         {       /* see below why Send Loss Event Rate is on */
490                                 .dependent_feat = DCCPF_SEND_LEV_RATE,
491                                 .is_local       = true,
492                                 .is_mandatory   = true,
493                                 .val            = 1
494                         },
495                         {       /* NDP Count is needed as per RFC 4342, 6.1.1 */
496                                 .dependent_feat = DCCPF_SEND_NDP_COUNT,
497                                 .is_local       = false,
498                                 .is_mandatory   = true,
499                                 .val            = 1
500                         },
501                         { 0, 0, 0, 0 },
502                 },
503                 {       /*
504                          * CCID3 at the TX side: we request that the HC-receiver
505                          * will not send Ack Vectors (they will be ignored, so
506                          * Mandatory is not set); we enable Send Loss Event Rate
507                          * (Mandatory since the implementation does not support
508                          * the Loss Intervals option of RFC 4342, 8.6).
509                          * The last two options are for peer's information only.
510                         */
511                         {
512                                 .dependent_feat = DCCPF_SEND_ACK_VECTOR,
513                                 .is_local       = false,
514                                 .is_mandatory   = false,
515                                 .val            = 0
516                         },
517                         {
518                                 .dependent_feat = DCCPF_SEND_LEV_RATE,
519                                 .is_local       = false,
520                                 .is_mandatory   = true,
521                                 .val            = 1
522                         },
523                         {       /* this CCID does not support Ack Ratio */
524                                 .dependent_feat = DCCPF_ACK_RATIO,
525                                 .is_local       = true,
526                                 .is_mandatory   = false,
527                                 .val            = 0
528                         },
529                         {       /* tell receiver we are sending NDP counts */
530                                 .dependent_feat = DCCPF_SEND_NDP_COUNT,
531                                 .is_local       = true,
532                                 .is_mandatory   = false,
533                                 .val            = 1
534                         },
535                         { 0, 0, 0, 0 }
536                 }
537         };
538         switch (ccid) {
539         case DCCPC_CCID2:
540                 return ccid2_dependencies[is_local];
541         case DCCPC_CCID3:
542                 return ccid3_dependencies[is_local];
543         default:
544                 return NULL;
545         }
546 }
547
548 /**
549  * dccp_feat_propagate_ccid - Resolve dependencies of features on choice of CCID
550  * @fn: feature-negotiation list to update
551  * @id: CCID number to track
552  * @is_local: whether TX CCID (1) or RX CCID (0) is meant
553  * This function needs to be called after registering all other features.
554  */
555 static int dccp_feat_propagate_ccid(struct list_head *fn, u8 id, bool is_local)
556 {
557         const struct ccid_dependency *table = dccp_feat_ccid_deps(id, is_local);
558         int i, rc = (table == NULL);
559
560         for (i = 0; rc == 0 && table[i].dependent_feat != DCCPF_RESERVED; i++)
561                 if (dccp_feat_type(table[i].dependent_feat) == FEAT_SP)
562                         rc = __feat_register_sp(fn, table[i].dependent_feat,
563                                                     table[i].is_local,
564                                                     table[i].is_mandatory,
565                                                     &table[i].val, 1);
566                 else
567                         rc = __feat_register_nn(fn, table[i].dependent_feat,
568                                                     table[i].is_mandatory,
569                                                     table[i].val);
570         return rc;
571 }
572
573 /**
574  * dccp_feat_finalise_settings  -  Finalise settings before starting negotiation
575  * @dp: client or listening socket (settings will be inherited)
576  * This is called after all registrations (socket initialisation, sysctls, and
577  * sockopt calls), and before sending the first packet containing Change options
578  * (ie. client-Request or server-Response), to ensure internal consistency.
579  */
580 int dccp_feat_finalise_settings(struct dccp_sock *dp)
581 {
582         struct list_head *fn = &dp->dccps_featneg;
583         struct dccp_feat_entry *entry;
584         int i = 2, ccids[2] = { -1, -1 };
585
586         /*
587          * Propagating CCIDs:
588          * 1) not useful to propagate CCID settings if this host advertises more
589          *    than one CCID: the choice of CCID  may still change - if this is
590          *    the client, or if this is the server and the client sends
591          *    singleton CCID values.
592          * 2) since is that propagate_ccid changes the list, we defer changing
593          *    the sorted list until after the traversal.
594          */
595         list_for_each_entry(entry, fn, node)
596                 if (entry->feat_num == DCCPF_CCID && entry->val.sp.len == 1)
597                         ccids[entry->is_local] = entry->val.sp.vec[0];
598         while (i--)
599                 if (ccids[i] > 0 && dccp_feat_propagate_ccid(fn, ccids[i], i))
600                         return -1;
601         return 0;
602 }
603
604 static int dccp_feat_update_ccid(struct sock *sk, u8 type, u8 new_ccid_nr)
605 {
606         struct dccp_sock *dp = dccp_sk(sk);
607         struct dccp_minisock *dmsk = dccp_msk(sk);
608         /* figure out if we are changing our CCID or the peer's */
609         const int rx = type == DCCPO_CHANGE_R;
610         const u8 ccid_nr = rx ? dmsk->dccpms_rx_ccid : dmsk->dccpms_tx_ccid;
611         struct ccid *new_ccid;
612
613         /* Check if nothing is being changed. */
614         if (ccid_nr == new_ccid_nr)
615                 return 0;
616
617         new_ccid = ccid_new(new_ccid_nr, sk, rx, GFP_ATOMIC);
618         if (new_ccid == NULL)
619                 return -ENOMEM;
620
621         if (rx) {
622                 ccid_hc_rx_delete(dp->dccps_hc_rx_ccid, sk);
623                 dp->dccps_hc_rx_ccid = new_ccid;
624                 dmsk->dccpms_rx_ccid = new_ccid_nr;
625         } else {
626                 ccid_hc_tx_delete(dp->dccps_hc_tx_ccid, sk);
627                 dp->dccps_hc_tx_ccid = new_ccid;
628                 dmsk->dccpms_tx_ccid = new_ccid_nr;
629         }
630
631         return 0;
632 }
633
634 static int dccp_feat_update(struct sock *sk, u8 type, u8 feat, u8 val)
635 {
636         dccp_feat_debug(type, feat, val);
637
638         switch (feat) {
639         case DCCPF_CCID:
640                 return dccp_feat_update_ccid(sk, type, val);
641         default:
642                 dccp_pr_debug("UNIMPLEMENTED: %s(%d, ...)\n",
643                               dccp_feat_typename(type), feat);
644                 break;
645         }
646         return 0;
647 }
648
649 static int dccp_feat_reconcile(struct sock *sk, struct dccp_opt_pend *opt,
650                                u8 *rpref, u8 rlen)
651 {
652         struct dccp_sock *dp = dccp_sk(sk);
653         u8 *spref, slen, *res = NULL;
654         int i, j, rc, agree = 1;
655
656         BUG_ON(rpref == NULL);
657
658         /* check if we are the black sheep */
659         if (dp->dccps_role == DCCP_ROLE_CLIENT) {
660                 spref = rpref;
661                 slen  = rlen;
662                 rpref = opt->dccpop_val;
663                 rlen  = opt->dccpop_len;
664         } else {
665                 spref = opt->dccpop_val;
666                 slen  = opt->dccpop_len;
667         }
668         /*
669          * Now we have server preference list in spref and client preference in
670          * rpref
671          */
672         BUG_ON(spref == NULL);
673         BUG_ON(rpref == NULL);
674
675         /* FIXME sanity check vals */
676
677         /* Are values in any order?  XXX Lame "algorithm" here */
678         for (i = 0; i < slen; i++) {
679                 for (j = 0; j < rlen; j++) {
680                         if (spref[i] == rpref[j]) {
681                                 res = &spref[i];
682                                 break;
683                         }
684                 }
685                 if (res)
686                         break;
687         }
688
689         /* we didn't agree on anything */
690         if (res == NULL) {
691                 /* confirm previous value */
692                 switch (opt->dccpop_feat) {
693                 case DCCPF_CCID:
694                         /* XXX did i get this right? =P */
695                         if (opt->dccpop_type == DCCPO_CHANGE_L)
696                                 res = &dccp_msk(sk)->dccpms_tx_ccid;
697                         else
698                                 res = &dccp_msk(sk)->dccpms_rx_ccid;
699                         break;
700
701                 default:
702                         DCCP_BUG("Fell through, feat=%d", opt->dccpop_feat);
703                         /* XXX implement res */
704                         return -EFAULT;
705                 }
706
707                 dccp_pr_debug("Don't agree... reconfirming %d\n", *res);
708                 agree = 0; /* this is used for mandatory options... */
709         }
710
711         /* need to put result and our preference list */
712         rlen = 1 + opt->dccpop_len;
713         rpref = kmalloc(rlen, GFP_ATOMIC);
714         if (rpref == NULL)
715                 return -ENOMEM;
716
717         *rpref = *res;
718         memcpy(&rpref[1], opt->dccpop_val, opt->dccpop_len);
719
720         /* put it in the "confirm queue" */
721         if (opt->dccpop_sc == NULL) {
722                 opt->dccpop_sc = kmalloc(sizeof(*opt->dccpop_sc), GFP_ATOMIC);
723                 if (opt->dccpop_sc == NULL) {
724                         kfree(rpref);
725                         return -ENOMEM;
726                 }
727         } else {
728                 /* recycle the confirm slot */
729                 BUG_ON(opt->dccpop_sc->dccpoc_val == NULL);
730                 kfree(opt->dccpop_sc->dccpoc_val);
731                 dccp_pr_debug("recycling confirm slot\n");
732         }
733         memset(opt->dccpop_sc, 0, sizeof(*opt->dccpop_sc));
734
735         opt->dccpop_sc->dccpoc_val = rpref;
736         opt->dccpop_sc->dccpoc_len = rlen;
737
738         /* update the option on our side [we are about to send the confirm] */
739         rc = dccp_feat_update(sk, opt->dccpop_type, opt->dccpop_feat, *res);
740         if (rc) {
741                 kfree(opt->dccpop_sc->dccpoc_val);
742                 kfree(opt->dccpop_sc);
743                 opt->dccpop_sc = NULL;
744                 return rc;
745         }
746
747         dccp_pr_debug("Will confirm %d\n", *rpref);
748
749         /* say we want to change to X but we just got a confirm X, suppress our
750          * change
751          */
752         if (!opt->dccpop_conf) {
753                 if (*opt->dccpop_val == *res)
754                         opt->dccpop_conf = 1;
755                 dccp_pr_debug("won't ask for change of same feature\n");
756         }
757
758         return agree ? 0 : DCCP_FEAT_SP_NOAGREE; /* used for mandatory opts */
759 }
760
761 static int dccp_feat_sp(struct sock *sk, u8 type, u8 feature, u8 *val, u8 len)
762 {
763         struct dccp_minisock *dmsk = dccp_msk(sk);
764         struct dccp_opt_pend *opt;
765         int rc = 1;
766         u8 t;
767
768         /*
769          * We received a CHANGE.  We gotta match it against our own preference
770          * list.  If we got a CHANGE_R it means it's a change for us, so we need
771          * to compare our CHANGE_L list.
772          */
773         if (type == DCCPO_CHANGE_L)
774                 t = DCCPO_CHANGE_R;
775         else
776                 t = DCCPO_CHANGE_L;
777
778         /* find our preference list for this feature */
779         list_for_each_entry(opt, &dmsk->dccpms_pending, dccpop_node) {
780                 if (opt->dccpop_type != t || opt->dccpop_feat != feature)
781                         continue;
782
783                 /* find the winner from the two preference lists */
784                 rc = dccp_feat_reconcile(sk, opt, val, len);
785                 break;
786         }
787
788         /* We didn't deal with the change.  This can happen if we have no
789          * preference list for the feature.  In fact, it just shouldn't
790          * happen---if we understand a feature, we should have a preference list
791          * with at least the default value.
792          */
793         BUG_ON(rc == 1);
794
795         return rc;
796 }
797
798 static int dccp_feat_nn(struct sock *sk, u8 type, u8 feature, u8 *val, u8 len)
799 {
800         struct dccp_opt_pend *opt;
801         struct dccp_minisock *dmsk = dccp_msk(sk);
802         u8 *copy;
803         int rc;
804
805         /* NN features must be Change L (sec. 6.3.2) */
806         if (type != DCCPO_CHANGE_L) {
807                 dccp_pr_debug("received %s for NN feature %d\n",
808                                 dccp_feat_typename(type), feature);
809                 return -EFAULT;
810         }
811
812         /* XXX sanity check opt val */
813
814         /* copy option so we can confirm it */
815         opt = kzalloc(sizeof(*opt), GFP_ATOMIC);
816         if (opt == NULL)
817                 return -ENOMEM;
818
819         copy = kmemdup(val, len, GFP_ATOMIC);
820         if (copy == NULL) {
821                 kfree(opt);
822                 return -ENOMEM;
823         }
824
825         opt->dccpop_type = DCCPO_CONFIRM_R; /* NN can only confirm R */
826         opt->dccpop_feat = feature;
827         opt->dccpop_val  = copy;
828         opt->dccpop_len  = len;
829
830         /* change feature */
831         rc = dccp_feat_update(sk, type, feature, *val);
832         if (rc) {
833                 kfree(opt->dccpop_val);
834                 kfree(opt);
835                 return rc;
836         }
837
838         dccp_feat_debug(type, feature, *copy);
839
840         list_add_tail(&opt->dccpop_node, &dmsk->dccpms_conf);
841
842         return 0;
843 }
844
845 static void dccp_feat_empty_confirm(struct dccp_minisock *dmsk,
846                                     u8 type, u8 feature)
847 {
848         /* XXX check if other confirms for that are queued and recycle slot */
849         struct dccp_opt_pend *opt = kzalloc(sizeof(*opt), GFP_ATOMIC);
850
851         if (opt == NULL) {
852                 /* XXX what do we do?  Ignoring should be fine.  It's a change
853                  * after all =P
854                  */
855                 return;
856         }
857
858         switch (type) {
859         case DCCPO_CHANGE_L:
860                 opt->dccpop_type = DCCPO_CONFIRM_R;
861                 break;
862         case DCCPO_CHANGE_R:
863                 opt->dccpop_type = DCCPO_CONFIRM_L;
864                 break;
865         default:
866                 DCCP_WARN("invalid type %d\n", type);
867                 kfree(opt);
868                 return;
869         }
870         opt->dccpop_feat = feature;
871         opt->dccpop_val  = NULL;
872         opt->dccpop_len  = 0;
873
874         /* change feature */
875         dccp_pr_debug("Empty %s(%d)\n", dccp_feat_typename(type), feature);
876
877         list_add_tail(&opt->dccpop_node, &dmsk->dccpms_conf);
878 }
879
880 static void dccp_feat_flush_confirm(struct sock *sk)
881 {
882         struct dccp_minisock *dmsk = dccp_msk(sk);
883         /* Check if there is anything to confirm in the first place */
884         int yes = !list_empty(&dmsk->dccpms_conf);
885
886         if (!yes) {
887                 struct dccp_opt_pend *opt;
888
889                 list_for_each_entry(opt, &dmsk->dccpms_pending, dccpop_node) {
890                         if (opt->dccpop_conf) {
891                                 yes = 1;
892                                 break;
893                         }
894                 }
895         }
896
897         if (!yes)
898                 return;
899
900         /* OK there is something to confirm... */
901         /* XXX check if packet is in flight?  Send delayed ack?? */
902         if (sk->sk_state == DCCP_OPEN)
903                 dccp_send_ack(sk);
904 }
905
906 int dccp_feat_change_recv(struct sock *sk, u8 type, u8 feature, u8 *val, u8 len)
907 {
908         int rc;
909
910         /* Ignore Change requests other than during connection setup */
911         if (sk->sk_state != DCCP_LISTEN && sk->sk_state != DCCP_REQUESTING)
912                 return 0;
913         dccp_feat_debug(type, feature, *val);
914
915         /* figure out if it's SP or NN feature */
916         switch (feature) {
917         /* deal with SP features */
918         case DCCPF_CCID:
919                 rc = dccp_feat_sp(sk, type, feature, val, len);
920                 break;
921
922         /* deal with NN features */
923         case DCCPF_ACK_RATIO:
924                 rc = dccp_feat_nn(sk, type, feature, val, len);
925                 break;
926
927         /* XXX implement other features */
928         default:
929                 dccp_pr_debug("UNIMPLEMENTED: not handling %s(%d, ...)\n",
930                               dccp_feat_typename(type), feature);
931                 rc = -EFAULT;
932                 break;
933         }
934
935         /* check if there were problems changing features */
936         if (rc) {
937                 /* If we don't agree on SP, we sent a confirm for old value.
938                  * However we propagate rc to caller in case option was
939                  * mandatory
940                  */
941                 if (rc != DCCP_FEAT_SP_NOAGREE)
942                         dccp_feat_empty_confirm(dccp_msk(sk), type, feature);
943         }
944
945         /* generate the confirm [if required] */
946         dccp_feat_flush_confirm(sk);
947
948         return rc;
949 }
950
951 EXPORT_SYMBOL_GPL(dccp_feat_change_recv);
952
953 int dccp_feat_confirm_recv(struct sock *sk, u8 type, u8 feature,
954                            u8 *val, u8 len)
955 {
956         u8 t;
957         struct dccp_opt_pend *opt;
958         struct dccp_minisock *dmsk = dccp_msk(sk);
959         int found = 0;
960         int all_confirmed = 1;
961
962         /* Ignore Confirm options other than during connection setup */
963         if (sk->sk_state != DCCP_LISTEN && sk->sk_state != DCCP_REQUESTING)
964                 return 0;
965         dccp_feat_debug(type, feature, *val);
966
967         /* locate our change request */
968         switch (type) {
969         case DCCPO_CONFIRM_L: t = DCCPO_CHANGE_R; break;
970         case DCCPO_CONFIRM_R: t = DCCPO_CHANGE_L; break;
971         default:              DCCP_WARN("invalid type %d\n", type);
972                               return 1;
973
974         }
975         /* XXX sanity check feature value */
976
977         list_for_each_entry(opt, &dmsk->dccpms_pending, dccpop_node) {
978                 if (!opt->dccpop_conf && opt->dccpop_type == t &&
979                     opt->dccpop_feat == feature) {
980                         found = 1;
981                         dccp_pr_debug("feature %d found\n", opt->dccpop_feat);
982
983                         /* XXX do sanity check */
984
985                         opt->dccpop_conf = 1;
986
987                         /* We got a confirmation---change the option */
988                         dccp_feat_update(sk, opt->dccpop_type,
989                                          opt->dccpop_feat, *val);
990
991                         /* XXX check the return value of dccp_feat_update */
992                         break;
993                 }
994
995                 if (!opt->dccpop_conf)
996                         all_confirmed = 0;
997         }
998
999         if (!found)
1000                 dccp_pr_debug("%s(%d, ...) never requested\n",
1001                               dccp_feat_typename(type), feature);
1002         return 0;
1003 }
1004
1005 EXPORT_SYMBOL_GPL(dccp_feat_confirm_recv);
1006
1007 void dccp_feat_clean(struct dccp_minisock *dmsk)
1008 {
1009         struct dccp_opt_pend *opt, *next;
1010
1011         list_for_each_entry_safe(opt, next, &dmsk->dccpms_pending,
1012                                  dccpop_node) {
1013                 BUG_ON(opt->dccpop_val == NULL);
1014                 kfree(opt->dccpop_val);
1015
1016                 if (opt->dccpop_sc != NULL) {
1017                         BUG_ON(opt->dccpop_sc->dccpoc_val == NULL);
1018                         kfree(opt->dccpop_sc->dccpoc_val);
1019                         kfree(opt->dccpop_sc);
1020                 }
1021
1022                 kfree(opt);
1023         }
1024         INIT_LIST_HEAD(&dmsk->dccpms_pending);
1025
1026         list_for_each_entry_safe(opt, next, &dmsk->dccpms_conf, dccpop_node) {
1027                 BUG_ON(opt == NULL);
1028                 if (opt->dccpop_val != NULL)
1029                         kfree(opt->dccpop_val);
1030                 kfree(opt);
1031         }
1032         INIT_LIST_HEAD(&dmsk->dccpms_conf);
1033 }
1034
1035 EXPORT_SYMBOL_GPL(dccp_feat_clean);
1036
1037 /* this is to be called only when a listening sock creates its child.  It is
1038  * assumed by the function---the confirm is not duplicated, but rather it is
1039  * "passed on".
1040  */
1041 int dccp_feat_clone(struct sock *oldsk, struct sock *newsk)
1042 {
1043         struct dccp_minisock *olddmsk = dccp_msk(oldsk);
1044         struct dccp_minisock *newdmsk = dccp_msk(newsk);
1045         struct dccp_opt_pend *opt;
1046         int rc = 0;
1047
1048         INIT_LIST_HEAD(&newdmsk->dccpms_pending);
1049         INIT_LIST_HEAD(&newdmsk->dccpms_conf);
1050
1051         list_for_each_entry(opt, &olddmsk->dccpms_pending, dccpop_node) {
1052                 struct dccp_opt_pend *newopt;
1053                 /* copy the value of the option */
1054                 u8 *val = kmemdup(opt->dccpop_val, opt->dccpop_len, GFP_ATOMIC);
1055
1056                 if (val == NULL)
1057                         goto out_clean;
1058
1059                 newopt = kmemdup(opt, sizeof(*newopt), GFP_ATOMIC);
1060                 if (newopt == NULL) {
1061                         kfree(val);
1062                         goto out_clean;
1063                 }
1064
1065                 /* insert the option */
1066                 newopt->dccpop_val = val;
1067                 list_add_tail(&newopt->dccpop_node, &newdmsk->dccpms_pending);
1068
1069                 /* XXX what happens with backlogs and multiple connections at
1070                  * once...
1071                  */
1072                 /* the master socket no longer needs to worry about confirms */
1073                 opt->dccpop_sc = NULL; /* it's not a memleak---new socket has it */
1074
1075                 /* reset state for a new socket */
1076                 opt->dccpop_conf = 0;
1077         }
1078
1079         /* XXX not doing anything about the conf queue */
1080
1081 out:
1082         return rc;
1083
1084 out_clean:
1085         dccp_feat_clean(newdmsk);
1086         rc = -ENOMEM;
1087         goto out;
1088 }
1089
1090 EXPORT_SYMBOL_GPL(dccp_feat_clone);
1091
1092 int dccp_feat_init(struct sock *sk)
1093 {
1094         struct dccp_sock *dp = dccp_sk(sk);
1095         struct dccp_minisock *dmsk = dccp_msk(sk);
1096         int rc;
1097
1098         INIT_LIST_HEAD(&dmsk->dccpms_pending);  /* XXX no longer used */
1099         INIT_LIST_HEAD(&dmsk->dccpms_conf);     /* XXX no longer used */
1100
1101         /* CCID L */
1102         rc = __feat_register_sp(&dp->dccps_featneg, DCCPF_CCID, 1, 0,
1103                                 &dmsk->dccpms_tx_ccid, 1);
1104         if (rc)
1105                 goto out;
1106
1107         /* CCID R */
1108         rc = __feat_register_sp(&dp->dccps_featneg, DCCPF_CCID, 0, 0,
1109                                 &dmsk->dccpms_rx_ccid, 1);
1110         if (rc)
1111                 goto out;
1112
1113         /* Ack ratio */
1114         rc = __feat_register_nn(&dp->dccps_featneg, DCCPF_ACK_RATIO, 0,
1115                                 dmsk->dccpms_ack_ratio);
1116 out:
1117         return rc;
1118 }
1119
1120 EXPORT_SYMBOL_GPL(dccp_feat_init);
1121
1122 #ifdef CONFIG_IP_DCCP_DEBUG
1123 const char *dccp_feat_typename(const u8 type)
1124 {
1125         switch(type) {
1126         case DCCPO_CHANGE_L:  return("ChangeL");
1127         case DCCPO_CONFIRM_L: return("ConfirmL");
1128         case DCCPO_CHANGE_R:  return("ChangeR");
1129         case DCCPO_CONFIRM_R: return("ConfirmR");
1130         /* the following case must not appear in feature negotation  */
1131         default:              dccp_pr_debug("unknown type %d [BUG!]\n", type);
1132         }
1133         return NULL;
1134 }
1135
1136 EXPORT_SYMBOL_GPL(dccp_feat_typename);
1137
1138 const char *dccp_feat_name(const u8 feat)
1139 {
1140         static const char *feature_names[] = {
1141                 [DCCPF_RESERVED]        = "Reserved",
1142                 [DCCPF_CCID]            = "CCID",
1143                 [DCCPF_SHORT_SEQNOS]    = "Allow Short Seqnos",
1144                 [DCCPF_SEQUENCE_WINDOW] = "Sequence Window",
1145                 [DCCPF_ECN_INCAPABLE]   = "ECN Incapable",
1146                 [DCCPF_ACK_RATIO]       = "Ack Ratio",
1147                 [DCCPF_SEND_ACK_VECTOR] = "Send ACK Vector",
1148                 [DCCPF_SEND_NDP_COUNT]  = "Send NDP Count",
1149                 [DCCPF_MIN_CSUM_COVER]  = "Min. Csum Coverage",
1150                 [DCCPF_DATA_CHECKSUM]   = "Send Data Checksum",
1151         };
1152         if (feat > DCCPF_DATA_CHECKSUM && feat < DCCPF_MIN_CCID_SPECIFIC)
1153                 return feature_names[DCCPF_RESERVED];
1154
1155         if (feat ==  DCCPF_SEND_LEV_RATE)
1156                 return "Send Loss Event Rate";
1157         if (feat >= DCCPF_MIN_CCID_SPECIFIC)
1158                 return "CCID-specific";
1159
1160         return feature_names[feat];
1161 }
1162
1163 EXPORT_SYMBOL_GPL(dccp_feat_name);
1164 #endif /* CONFIG_IP_DCCP_DEBUG */