Merge git://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux-2.6
[linux-2.6/sactl.git] / net / dccp / feat.c
blob4152308958ab0b3a10a70b729e32e8d988816e3b
1 /*
2 * net/dccp/feat.c
4 * Feature negotiation for the DCCP protocol (RFC 4340, section 6)
6 * Copyright (c) 2008 Gerrit Renker <gerrit@erg.abdn.ac.uk>
7 * Rewrote from scratch, some bits from earlier code by
8 * Copyright (c) 2005 Andrea Bittau <a.bittau@cs.ucl.ac.uk>
11 * ASSUMPTIONS
12 * -----------
13 * o Feature negotiation is coordinated with connection setup (as in TCP), wild
14 * changes of parameters of an established connection are not supported.
15 * o All currently known SP features have 1-byte quantities. If in the future
16 * extensions of RFCs 4340..42 define features with item lengths larger than
17 * one byte, a feature-specific extension of the code will be required.
19 * This program is free software; you can redistribute it and/or
20 * modify it under the terms of the GNU General Public License
21 * as published by the Free Software Foundation; either version
22 * 2 of the License, or (at your option) any later version.
24 #include <linux/module.h>
25 #include "ccid.h"
26 #include "feat.h"
29 * Feature activation handlers.
31 * These all use an u64 argument, to provide enough room for NN/SP features. At
32 * this stage the negotiated values have been checked to be within their range.
34 static int dccp_hdlr_ccid(struct sock *sk, u64 ccid, bool rx)
36 struct dccp_sock *dp = dccp_sk(sk);
37 struct ccid *new_ccid = ccid_new(ccid, sk, rx);
39 if (new_ccid == NULL)
40 return -ENOMEM;
42 if (rx) {
43 ccid_hc_rx_delete(dp->dccps_hc_rx_ccid, sk);
44 dp->dccps_hc_rx_ccid = new_ccid;
45 } else {
46 ccid_hc_tx_delete(dp->dccps_hc_tx_ccid, sk);
47 dp->dccps_hc_tx_ccid = new_ccid;
49 return 0;
52 static int dccp_hdlr_seq_win(struct sock *sk, u64 seq_win, bool rx)
54 if (!rx)
55 dccp_msk(sk)->dccpms_sequence_window = seq_win;
56 return 0;
59 static int dccp_hdlr_ack_ratio(struct sock *sk, u64 ratio, bool rx)
61 if (rx)
62 dccp_sk(sk)->dccps_r_ack_ratio = ratio;
63 else
64 dccp_sk(sk)->dccps_l_ack_ratio = ratio;
65 return 0;
68 static int dccp_hdlr_ackvec(struct sock *sk, u64 enable, bool rx)
70 struct dccp_sock *dp = dccp_sk(sk);
72 if (rx) {
73 if (enable && dp->dccps_hc_rx_ackvec == NULL) {
74 dp->dccps_hc_rx_ackvec = dccp_ackvec_alloc(gfp_any());
75 if (dp->dccps_hc_rx_ackvec == NULL)
76 return -ENOMEM;
77 } else if (!enable) {
78 dccp_ackvec_free(dp->dccps_hc_rx_ackvec);
79 dp->dccps_hc_rx_ackvec = NULL;
82 return 0;
85 static int dccp_hdlr_ndp(struct sock *sk, u64 enable, bool rx)
87 if (!rx)
88 dccp_sk(sk)->dccps_send_ndp_count = (enable > 0);
89 return 0;
93 * Minimum Checksum Coverage is located at the RX side (9.2.1). This means that
94 * `rx' holds when the sending peer informs about his partial coverage via a
95 * ChangeR() option. In the other case, we are the sender and the receiver
96 * announces its coverage via ChangeL() options. The policy here is to honour
97 * such communication by enabling the corresponding partial coverage - but only
98 * if it has not been set manually before; the warning here means that all
99 * packets will be dropped.
101 static int dccp_hdlr_min_cscov(struct sock *sk, u64 cscov, bool rx)
103 struct dccp_sock *dp = dccp_sk(sk);
105 if (rx)
106 dp->dccps_pcrlen = cscov;
107 else {
108 if (dp->dccps_pcslen == 0)
109 dp->dccps_pcslen = cscov;
110 else if (cscov > dp->dccps_pcslen)
111 DCCP_WARN("CsCov %u too small, peer requires >= %u\n",
112 dp->dccps_pcslen, (u8)cscov);
114 return 0;
117 static const struct {
118 u8 feat_num; /* DCCPF_xxx */
119 enum dccp_feat_type rxtx; /* RX or TX */
120 enum dccp_feat_type reconciliation; /* SP or NN */
121 u8 default_value; /* as in 6.4 */
122 int (*activation_hdlr)(struct sock *sk, u64 val, bool rx);
124 * Lookup table for location and type of features (from RFC 4340/4342)
125 * +--------------------------+----+-----+----+----+---------+-----------+
126 * | Feature | Location | Reconc. | Initial | Section |
127 * | | RX | TX | SP | NN | Value | Reference |
128 * +--------------------------+----+-----+----+----+---------+-----------+
129 * | DCCPF_CCID | | X | X | | 2 | 10 |
130 * | DCCPF_SHORT_SEQNOS | | X | X | | 0 | 7.6.1 |
131 * | DCCPF_SEQUENCE_WINDOW | | X | | X | 100 | 7.5.2 |
132 * | DCCPF_ECN_INCAPABLE | X | | X | | 0 | 12.1 |
133 * | DCCPF_ACK_RATIO | | X | | X | 2 | 11.3 |
134 * | DCCPF_SEND_ACK_VECTOR | X | | X | | 0 | 11.5 |
135 * | DCCPF_SEND_NDP_COUNT | | X | X | | 0 | 7.7.2 |
136 * | DCCPF_MIN_CSUM_COVER | X | | X | | 0 | 9.2.1 |
137 * | DCCPF_DATA_CHECKSUM | X | | X | | 0 | 9.3.1 |
138 * | DCCPF_SEND_LEV_RATE | X | | X | | 0 | 4342/8.4 |
139 * +--------------------------+----+-----+----+----+---------+-----------+
141 } dccp_feat_table[] = {
142 { DCCPF_CCID, FEAT_AT_TX, FEAT_SP, 2, dccp_hdlr_ccid },
143 { DCCPF_SHORT_SEQNOS, FEAT_AT_TX, FEAT_SP, 0, NULL },
144 { DCCPF_SEQUENCE_WINDOW, FEAT_AT_TX, FEAT_NN, 100, dccp_hdlr_seq_win },
145 { DCCPF_ECN_INCAPABLE, FEAT_AT_RX, FEAT_SP, 0, NULL },
146 { DCCPF_ACK_RATIO, FEAT_AT_TX, FEAT_NN, 2, dccp_hdlr_ack_ratio},
147 { DCCPF_SEND_ACK_VECTOR, FEAT_AT_RX, FEAT_SP, 0, dccp_hdlr_ackvec },
148 { DCCPF_SEND_NDP_COUNT, FEAT_AT_TX, FEAT_SP, 0, dccp_hdlr_ndp },
149 { DCCPF_MIN_CSUM_COVER, FEAT_AT_RX, FEAT_SP, 0, dccp_hdlr_min_cscov},
150 { DCCPF_DATA_CHECKSUM, FEAT_AT_RX, FEAT_SP, 0, NULL },
151 { DCCPF_SEND_LEV_RATE, FEAT_AT_RX, FEAT_SP, 0, NULL },
153 #define DCCP_FEAT_SUPPORTED_MAX ARRAY_SIZE(dccp_feat_table)
156 * dccp_feat_index - Hash function to map feature number into array position
157 * Returns consecutive array index or -1 if the feature is not understood.
159 static int dccp_feat_index(u8 feat_num)
161 /* The first 9 entries are occupied by the types from RFC 4340, 6.4 */
162 if (feat_num > DCCPF_RESERVED && feat_num <= DCCPF_DATA_CHECKSUM)
163 return feat_num - 1;
166 * Other features: add cases for new feature types here after adding
167 * them to the above table.
169 switch (feat_num) {
170 case DCCPF_SEND_LEV_RATE:
171 return DCCP_FEAT_SUPPORTED_MAX - 1;
173 return -1;
176 static u8 dccp_feat_type(u8 feat_num)
178 int idx = dccp_feat_index(feat_num);
180 if (idx < 0)
181 return FEAT_UNKNOWN;
182 return dccp_feat_table[idx].reconciliation;
185 static int dccp_feat_default_value(u8 feat_num)
187 int idx = dccp_feat_index(feat_num);
189 * There are no default values for unknown features, so encountering a
190 * negative index here indicates a serious problem somewhere else.
192 DCCP_BUG_ON(idx < 0);
194 return idx < 0 ? 0 : dccp_feat_table[idx].default_value;
197 static int __dccp_feat_activate(struct sock *sk, const int idx,
198 const bool is_local, dccp_feat_val const *fval)
200 bool rx;
201 u64 val;
203 if (idx < 0 || idx >= DCCP_FEAT_SUPPORTED_MAX)
204 return -1;
205 if (dccp_feat_table[idx].activation_hdlr == NULL)
206 return 0;
208 if (fval == NULL) {
209 val = dccp_feat_table[idx].default_value;
210 } else if (dccp_feat_table[idx].reconciliation == FEAT_SP) {
211 if (fval->sp.vec == NULL) {
213 * This can happen when an empty Confirm is sent
214 * for an SP (i.e. known) feature. In this case
215 * we would be using the default anyway.
217 DCCP_CRIT("Feature #%d undefined: using default", idx);
218 val = dccp_feat_table[idx].default_value;
219 } else {
220 val = fval->sp.vec[0];
222 } else {
223 val = fval->nn;
226 /* Location is RX if this is a local-RX or remote-TX feature */
227 rx = (is_local == (dccp_feat_table[idx].rxtx == FEAT_AT_RX));
229 return dccp_feat_table[idx].activation_hdlr(sk, val, rx);
232 /* Test for "Req'd" feature (RFC 4340, 6.4) */
233 static inline int dccp_feat_must_be_understood(u8 feat_num)
235 return feat_num == DCCPF_CCID || feat_num == DCCPF_SHORT_SEQNOS ||
236 feat_num == DCCPF_SEQUENCE_WINDOW;
239 /* copy constructor, fval must not already contain allocated memory */
240 static int dccp_feat_clone_sp_val(dccp_feat_val *fval, u8 const *val, u8 len)
242 fval->sp.len = len;
243 if (fval->sp.len > 0) {
244 fval->sp.vec = kmemdup(val, len, gfp_any());
245 if (fval->sp.vec == NULL) {
246 fval->sp.len = 0;
247 return -ENOBUFS;
250 return 0;
253 static void dccp_feat_val_destructor(u8 feat_num, dccp_feat_val *val)
255 if (unlikely(val == NULL))
256 return;
257 if (dccp_feat_type(feat_num) == FEAT_SP)
258 kfree(val->sp.vec);
259 memset(val, 0, sizeof(*val));
262 static struct dccp_feat_entry *
263 dccp_feat_clone_entry(struct dccp_feat_entry const *original)
265 struct dccp_feat_entry *new;
266 u8 type = dccp_feat_type(original->feat_num);
268 if (type == FEAT_UNKNOWN)
269 return NULL;
271 new = kmemdup(original, sizeof(struct dccp_feat_entry), gfp_any());
272 if (new == NULL)
273 return NULL;
275 if (type == FEAT_SP && dccp_feat_clone_sp_val(&new->val,
276 original->val.sp.vec,
277 original->val.sp.len)) {
278 kfree(new);
279 return NULL;
281 return new;
284 static void dccp_feat_entry_destructor(struct dccp_feat_entry *entry)
286 if (entry != NULL) {
287 dccp_feat_val_destructor(entry->feat_num, &entry->val);
288 kfree(entry);
293 * List management functions
295 * Feature negotiation lists rely on and maintain the following invariants:
296 * - each feat_num in the list is known, i.e. we know its type and default value
297 * - each feat_num/is_local combination is unique (old entries are overwritten)
298 * - SP values are always freshly allocated
299 * - list is sorted in increasing order of feature number (faster lookup)
301 static struct dccp_feat_entry *dccp_feat_list_lookup(struct list_head *fn_list,
302 u8 feat_num, bool is_local)
304 struct dccp_feat_entry *entry;
306 list_for_each_entry(entry, fn_list, node) {
307 if (entry->feat_num == feat_num && entry->is_local == is_local)
308 return entry;
309 else if (entry->feat_num > feat_num)
310 break;
312 return NULL;
316 * dccp_feat_entry_new - Central list update routine (called by all others)
317 * @head: list to add to
318 * @feat: feature number
319 * @local: whether the local (1) or remote feature with number @feat is meant
320 * This is the only constructor and serves to ensure the above invariants.
322 static struct dccp_feat_entry *
323 dccp_feat_entry_new(struct list_head *head, u8 feat, bool local)
325 struct dccp_feat_entry *entry;
327 list_for_each_entry(entry, head, node)
328 if (entry->feat_num == feat && entry->is_local == local) {
329 dccp_feat_val_destructor(entry->feat_num, &entry->val);
330 return entry;
331 } else if (entry->feat_num > feat) {
332 head = &entry->node;
333 break;
336 entry = kmalloc(sizeof(*entry), gfp_any());
337 if (entry != NULL) {
338 entry->feat_num = feat;
339 entry->is_local = local;
340 list_add_tail(&entry->node, head);
342 return entry;
346 * dccp_feat_push_change - Add/overwrite a Change option in the list
347 * @fn_list: feature-negotiation list to update
348 * @feat: one of %dccp_feature_numbers
349 * @local: whether local (1) or remote (0) @feat_num is meant
350 * @needs_mandatory: whether to use Mandatory feature negotiation options
351 * @fval: pointer to NN/SP value to be inserted (will be copied)
353 static int dccp_feat_push_change(struct list_head *fn_list, u8 feat, u8 local,
354 u8 mandatory, dccp_feat_val *fval)
356 struct dccp_feat_entry *new = dccp_feat_entry_new(fn_list, feat, local);
358 if (new == NULL)
359 return -ENOMEM;
361 new->feat_num = feat;
362 new->is_local = local;
363 new->state = FEAT_INITIALISING;
364 new->needs_confirm = 0;
365 new->empty_confirm = 0;
366 new->val = *fval;
367 new->needs_mandatory = mandatory;
369 return 0;
373 * dccp_feat_push_confirm - Add a Confirm entry to the FN list
374 * @fn_list: feature-negotiation list to add to
375 * @feat: one of %dccp_feature_numbers
376 * @local: whether local (1) or remote (0) @feat_num is being confirmed
377 * @fval: pointer to NN/SP value to be inserted or NULL
378 * Returns 0 on success, a Reset code for further processing otherwise.
380 static int dccp_feat_push_confirm(struct list_head *fn_list, u8 feat, u8 local,
381 dccp_feat_val *fval)
383 struct dccp_feat_entry *new = dccp_feat_entry_new(fn_list, feat, local);
385 if (new == NULL)
386 return DCCP_RESET_CODE_TOO_BUSY;
388 new->feat_num = feat;
389 new->is_local = local;
390 new->state = FEAT_STABLE; /* transition in 6.6.2 */
391 new->needs_confirm = 1;
392 new->empty_confirm = (fval == NULL);
393 new->val.nn = 0; /* zeroes the whole structure */
394 if (!new->empty_confirm)
395 new->val = *fval;
396 new->needs_mandatory = 0;
398 return 0;
401 static int dccp_push_empty_confirm(struct list_head *fn_list, u8 feat, u8 local)
403 return dccp_feat_push_confirm(fn_list, feat, local, NULL);
406 static inline void dccp_feat_list_pop(struct dccp_feat_entry *entry)
408 list_del(&entry->node);
409 dccp_feat_entry_destructor(entry);
412 void dccp_feat_list_purge(struct list_head *fn_list)
414 struct dccp_feat_entry *entry, *next;
416 list_for_each_entry_safe(entry, next, fn_list, node)
417 dccp_feat_entry_destructor(entry);
418 INIT_LIST_HEAD(fn_list);
420 EXPORT_SYMBOL_GPL(dccp_feat_list_purge);
422 /* generate @to as full clone of @from - @to must not contain any nodes */
423 int dccp_feat_clone_list(struct list_head const *from, struct list_head *to)
425 struct dccp_feat_entry *entry, *new;
427 INIT_LIST_HEAD(to);
428 list_for_each_entry(entry, from, node) {
429 new = dccp_feat_clone_entry(entry);
430 if (new == NULL)
431 goto cloning_failed;
432 list_add_tail(&new->node, to);
434 return 0;
436 cloning_failed:
437 dccp_feat_list_purge(to);
438 return -ENOMEM;
442 * dccp_feat_valid_nn_length - Enforce length constraints on NN options
443 * Length is between 0 and %DCCP_OPTVAL_MAXLEN. Used for outgoing packets only,
444 * incoming options are accepted as long as their values are valid.
446 static u8 dccp_feat_valid_nn_length(u8 feat_num)
448 if (feat_num == DCCPF_ACK_RATIO) /* RFC 4340, 11.3 and 6.6.8 */
449 return 2;
450 if (feat_num == DCCPF_SEQUENCE_WINDOW) /* RFC 4340, 7.5.2 and 6.5 */
451 return 6;
452 return 0;
455 static u8 dccp_feat_is_valid_nn_val(u8 feat_num, u64 val)
457 switch (feat_num) {
458 case DCCPF_ACK_RATIO:
459 return val <= DCCPF_ACK_RATIO_MAX;
460 case DCCPF_SEQUENCE_WINDOW:
461 return val >= DCCPF_SEQ_WMIN && val <= DCCPF_SEQ_WMAX;
463 return 0; /* feature unknown - so we can't tell */
466 /* check that SP values are within the ranges defined in RFC 4340 */
467 static u8 dccp_feat_is_valid_sp_val(u8 feat_num, u8 val)
469 switch (feat_num) {
470 case DCCPF_CCID:
471 return val == DCCPC_CCID2 || val == DCCPC_CCID3;
472 /* Type-check Boolean feature values: */
473 case DCCPF_SHORT_SEQNOS:
474 case DCCPF_ECN_INCAPABLE:
475 case DCCPF_SEND_ACK_VECTOR:
476 case DCCPF_SEND_NDP_COUNT:
477 case DCCPF_DATA_CHECKSUM:
478 case DCCPF_SEND_LEV_RATE:
479 return val < 2;
480 case DCCPF_MIN_CSUM_COVER:
481 return val < 16;
483 return 0; /* feature unknown */
486 static u8 dccp_feat_sp_list_ok(u8 feat_num, u8 const *sp_list, u8 sp_len)
488 if (sp_list == NULL || sp_len < 1)
489 return 0;
490 while (sp_len--)
491 if (!dccp_feat_is_valid_sp_val(feat_num, *sp_list++))
492 return 0;
493 return 1;
497 * dccp_feat_insert_opts - Generate FN options from current list state
498 * @skb: next sk_buff to be sent to the peer
499 * @dp: for client during handshake and general negotiation
500 * @dreq: used by the server only (all Changes/Confirms in LISTEN/RESPOND)
502 int dccp_feat_insert_opts(struct dccp_sock *dp, struct dccp_request_sock *dreq,
503 struct sk_buff *skb)
505 struct list_head *fn = dreq ? &dreq->dreq_featneg : &dp->dccps_featneg;
506 struct dccp_feat_entry *pos, *next;
507 u8 opt, type, len, *ptr, nn_in_nbo[DCCP_OPTVAL_MAXLEN];
508 bool rpt;
510 /* put entries into @skb in the order they appear in the list */
511 list_for_each_entry_safe_reverse(pos, next, fn, node) {
512 opt = dccp_feat_genopt(pos);
513 type = dccp_feat_type(pos->feat_num);
514 rpt = false;
516 if (pos->empty_confirm) {
517 len = 0;
518 ptr = NULL;
519 } else {
520 if (type == FEAT_SP) {
521 len = pos->val.sp.len;
522 ptr = pos->val.sp.vec;
523 rpt = pos->needs_confirm;
524 } else if (type == FEAT_NN) {
525 len = dccp_feat_valid_nn_length(pos->feat_num);
526 ptr = nn_in_nbo;
527 dccp_encode_value_var(pos->val.nn, ptr, len);
528 } else {
529 DCCP_BUG("unknown feature %u", pos->feat_num);
530 return -1;
534 if (dccp_insert_fn_opt(skb, opt, pos->feat_num, ptr, len, rpt))
535 return -1;
536 if (pos->needs_mandatory && dccp_insert_option_mandatory(skb))
537 return -1;
539 * Enter CHANGING after transmitting the Change option (6.6.2).
541 if (pos->state == FEAT_INITIALISING)
542 pos->state = FEAT_CHANGING;
544 return 0;
548 * __feat_register_nn - Register new NN value on socket
549 * @fn: feature-negotiation list to register with
550 * @feat: an NN feature from %dccp_feature_numbers
551 * @mandatory: use Mandatory option if 1
552 * @nn_val: value to register (restricted to 4 bytes)
553 * Note that NN features are local by definition (RFC 4340, 6.3.2).
555 static int __feat_register_nn(struct list_head *fn, u8 feat,
556 u8 mandatory, u64 nn_val)
558 dccp_feat_val fval = { .nn = nn_val };
560 if (dccp_feat_type(feat) != FEAT_NN ||
561 !dccp_feat_is_valid_nn_val(feat, nn_val))
562 return -EINVAL;
564 /* Don't bother with default values, they will be activated anyway. */
565 if (nn_val - (u64)dccp_feat_default_value(feat) == 0)
566 return 0;
568 return dccp_feat_push_change(fn, feat, 1, mandatory, &fval);
572 * __feat_register_sp - Register new SP value/list on socket
573 * @fn: feature-negotiation list to register with
574 * @feat: an SP feature from %dccp_feature_numbers
575 * @is_local: whether the local (1) or the remote (0) @feat is meant
576 * @mandatory: use Mandatory option if 1
577 * @sp_val: SP value followed by optional preference list
578 * @sp_len: length of @sp_val in bytes
580 static int __feat_register_sp(struct list_head *fn, u8 feat, u8 is_local,
581 u8 mandatory, u8 const *sp_val, u8 sp_len)
583 dccp_feat_val fval;
585 if (dccp_feat_type(feat) != FEAT_SP ||
586 !dccp_feat_sp_list_ok(feat, sp_val, sp_len))
587 return -EINVAL;
589 /* Avoid negotiating alien CCIDs by only advertising supported ones */
590 if (feat == DCCPF_CCID && !ccid_support_check(sp_val, sp_len))
591 return -EOPNOTSUPP;
593 if (dccp_feat_clone_sp_val(&fval, sp_val, sp_len))
594 return -ENOMEM;
596 return dccp_feat_push_change(fn, feat, is_local, mandatory, &fval);
600 * dccp_feat_register_sp - Register requests to change SP feature values
601 * @sk: client or listening socket
602 * @feat: one of %dccp_feature_numbers
603 * @is_local: whether the local (1) or remote (0) @feat is meant
604 * @list: array of preferred values, in descending order of preference
605 * @len: length of @list in bytes
607 int dccp_feat_register_sp(struct sock *sk, u8 feat, u8 is_local,
608 u8 const *list, u8 len)
609 { /* any changes must be registered before establishing the connection */
610 if (sk->sk_state != DCCP_CLOSED)
611 return -EISCONN;
612 if (dccp_feat_type(feat) != FEAT_SP)
613 return -EINVAL;
614 return __feat_register_sp(&dccp_sk(sk)->dccps_featneg, feat, is_local,
615 0, list, len);
618 /* Analogous to dccp_feat_register_sp(), but for non-negotiable values */
619 int dccp_feat_register_nn(struct sock *sk, u8 feat, u64 val)
621 /* any changes must be registered before establishing the connection */
622 if (sk->sk_state != DCCP_CLOSED)
623 return -EISCONN;
624 if (dccp_feat_type(feat) != FEAT_NN)
625 return -EINVAL;
626 return __feat_register_nn(&dccp_sk(sk)->dccps_featneg, feat, 0, val);
630 * Tracking features whose value depend on the choice of CCID
632 * This is designed with an extension in mind so that a list walk could be done
633 * before activating any features. However, the existing framework was found to
634 * work satisfactorily up until now, the automatic verification is left open.
635 * When adding new CCIDs, add a corresponding dependency table here.
637 static const struct ccid_dependency *dccp_feat_ccid_deps(u8 ccid, bool is_local)
639 static const struct ccid_dependency ccid2_dependencies[2][2] = {
641 * CCID2 mandates Ack Vectors (RFC 4341, 4.): as CCID is a TX
642 * feature and Send Ack Vector is an RX feature, `is_local'
643 * needs to be reversed.
645 { /* Dependencies of the receiver-side (remote) CCID2 */
647 .dependent_feat = DCCPF_SEND_ACK_VECTOR,
648 .is_local = true,
649 .is_mandatory = true,
650 .val = 1
652 { 0, 0, 0, 0 }
654 { /* Dependencies of the sender-side (local) CCID2 */
656 .dependent_feat = DCCPF_SEND_ACK_VECTOR,
657 .is_local = false,
658 .is_mandatory = true,
659 .val = 1
661 { 0, 0, 0, 0 }
664 static const struct ccid_dependency ccid3_dependencies[2][5] = {
665 { /*
666 * Dependencies of the receiver-side CCID3
668 { /* locally disable Ack Vectors */
669 .dependent_feat = DCCPF_SEND_ACK_VECTOR,
670 .is_local = true,
671 .is_mandatory = false,
672 .val = 0
674 { /* see below why Send Loss Event Rate is on */
675 .dependent_feat = DCCPF_SEND_LEV_RATE,
676 .is_local = true,
677 .is_mandatory = true,
678 .val = 1
680 { /* NDP Count is needed as per RFC 4342, 6.1.1 */
681 .dependent_feat = DCCPF_SEND_NDP_COUNT,
682 .is_local = false,
683 .is_mandatory = true,
684 .val = 1
686 { 0, 0, 0, 0 },
688 { /*
689 * CCID3 at the TX side: we request that the HC-receiver
690 * will not send Ack Vectors (they will be ignored, so
691 * Mandatory is not set); we enable Send Loss Event Rate
692 * (Mandatory since the implementation does not support
693 * the Loss Intervals option of RFC 4342, 8.6).
694 * The last two options are for peer's information only.
697 .dependent_feat = DCCPF_SEND_ACK_VECTOR,
698 .is_local = false,
699 .is_mandatory = false,
700 .val = 0
703 .dependent_feat = DCCPF_SEND_LEV_RATE,
704 .is_local = false,
705 .is_mandatory = true,
706 .val = 1
708 { /* this CCID does not support Ack Ratio */
709 .dependent_feat = DCCPF_ACK_RATIO,
710 .is_local = true,
711 .is_mandatory = false,
712 .val = 0
714 { /* tell receiver we are sending NDP counts */
715 .dependent_feat = DCCPF_SEND_NDP_COUNT,
716 .is_local = true,
717 .is_mandatory = false,
718 .val = 1
720 { 0, 0, 0, 0 }
723 switch (ccid) {
724 case DCCPC_CCID2:
725 return ccid2_dependencies[is_local];
726 case DCCPC_CCID3:
727 return ccid3_dependencies[is_local];
728 default:
729 return NULL;
734 * dccp_feat_propagate_ccid - Resolve dependencies of features on choice of CCID
735 * @fn: feature-negotiation list to update
736 * @id: CCID number to track
737 * @is_local: whether TX CCID (1) or RX CCID (0) is meant
738 * This function needs to be called after registering all other features.
740 static int dccp_feat_propagate_ccid(struct list_head *fn, u8 id, bool is_local)
742 const struct ccid_dependency *table = dccp_feat_ccid_deps(id, is_local);
743 int i, rc = (table == NULL);
745 for (i = 0; rc == 0 && table[i].dependent_feat != DCCPF_RESERVED; i++)
746 if (dccp_feat_type(table[i].dependent_feat) == FEAT_SP)
747 rc = __feat_register_sp(fn, table[i].dependent_feat,
748 table[i].is_local,
749 table[i].is_mandatory,
750 &table[i].val, 1);
751 else
752 rc = __feat_register_nn(fn, table[i].dependent_feat,
753 table[i].is_mandatory,
754 table[i].val);
755 return rc;
759 * dccp_feat_finalise_settings - Finalise settings before starting negotiation
760 * @dp: client or listening socket (settings will be inherited)
761 * This is called after all registrations (socket initialisation, sysctls, and
762 * sockopt calls), and before sending the first packet containing Change options
763 * (ie. client-Request or server-Response), to ensure internal consistency.
765 int dccp_feat_finalise_settings(struct dccp_sock *dp)
767 struct list_head *fn = &dp->dccps_featneg;
768 struct dccp_feat_entry *entry;
769 int i = 2, ccids[2] = { -1, -1 };
772 * Propagating CCIDs:
773 * 1) not useful to propagate CCID settings if this host advertises more
774 * than one CCID: the choice of CCID may still change - if this is
775 * the client, or if this is the server and the client sends
776 * singleton CCID values.
777 * 2) since is that propagate_ccid changes the list, we defer changing
778 * the sorted list until after the traversal.
780 list_for_each_entry(entry, fn, node)
781 if (entry->feat_num == DCCPF_CCID && entry->val.sp.len == 1)
782 ccids[entry->is_local] = entry->val.sp.vec[0];
783 while (i--)
784 if (ccids[i] > 0 && dccp_feat_propagate_ccid(fn, ccids[i], i))
785 return -1;
786 return 0;
790 * dccp_feat_server_ccid_dependencies - Resolve CCID-dependent features
791 * It is the server which resolves the dependencies once the CCID has been
792 * fully negotiated. If no CCID has been negotiated, it uses the default CCID.
794 int dccp_feat_server_ccid_dependencies(struct dccp_request_sock *dreq)
796 struct list_head *fn = &dreq->dreq_featneg;
797 struct dccp_feat_entry *entry;
798 u8 is_local, ccid;
800 for (is_local = 0; is_local <= 1; is_local++) {
801 entry = dccp_feat_list_lookup(fn, DCCPF_CCID, is_local);
803 if (entry != NULL && !entry->empty_confirm)
804 ccid = entry->val.sp.vec[0];
805 else
806 ccid = dccp_feat_default_value(DCCPF_CCID);
808 if (dccp_feat_propagate_ccid(fn, ccid, is_local))
809 return -1;
811 return 0;
814 /* Select the first entry in @servlist that also occurs in @clilist (6.3.1) */
815 static int dccp_feat_preflist_match(u8 *servlist, u8 slen, u8 *clilist, u8 clen)
817 u8 c, s;
819 for (s = 0; s < slen; s++)
820 for (c = 0; c < clen; c++)
821 if (servlist[s] == clilist[c])
822 return servlist[s];
823 return -1;
827 * dccp_feat_prefer - Move preferred entry to the start of array
828 * Reorder the @array_len elements in @array so that @preferred_value comes
829 * first. Returns >0 to indicate that @preferred_value does occur in @array.
831 static u8 dccp_feat_prefer(u8 preferred_value, u8 *array, u8 array_len)
833 u8 i, does_occur = 0;
835 if (array != NULL) {
836 for (i = 0; i < array_len; i++)
837 if (array[i] == preferred_value) {
838 array[i] = array[0];
839 does_occur++;
841 if (does_occur)
842 array[0] = preferred_value;
844 return does_occur;
848 * dccp_feat_reconcile - Reconcile SP preference lists
849 * @fval: SP list to reconcile into
850 * @arr: received SP preference list
851 * @len: length of @arr in bytes
852 * @is_server: whether this side is the server (and @fv is the server's list)
853 * @reorder: whether to reorder the list in @fv after reconciling with @arr
854 * When successful, > 0 is returned and the reconciled list is in @fval.
855 * A value of 0 means that negotiation failed (no shared entry).
857 static int dccp_feat_reconcile(dccp_feat_val *fv, u8 *arr, u8 len,
858 bool is_server, bool reorder)
860 int rc;
862 if (!fv->sp.vec || !arr) {
863 DCCP_CRIT("NULL feature value or array");
864 return 0;
867 if (is_server)
868 rc = dccp_feat_preflist_match(fv->sp.vec, fv->sp.len, arr, len);
869 else
870 rc = dccp_feat_preflist_match(arr, len, fv->sp.vec, fv->sp.len);
872 if (!reorder)
873 return rc;
874 if (rc < 0)
875 return 0;
878 * Reorder list: used for activating features and in dccp_insert_fn_opt.
880 return dccp_feat_prefer(rc, fv->sp.vec, fv->sp.len);
884 * dccp_feat_change_recv - Process incoming ChangeL/R options
885 * @fn: feature-negotiation list to update
886 * @is_mandatory: whether the Change was preceded by a Mandatory option
887 * @opt: %DCCPO_CHANGE_L or %DCCPO_CHANGE_R
888 * @feat: one of %dccp_feature_numbers
889 * @val: NN value or SP value/preference list
890 * @len: length of @val in bytes
891 * @server: whether this node is the server (1) or the client (0)
893 static u8 dccp_feat_change_recv(struct list_head *fn, u8 is_mandatory, u8 opt,
894 u8 feat, u8 *val, u8 len, const bool server)
896 u8 defval, type = dccp_feat_type(feat);
897 const bool local = (opt == DCCPO_CHANGE_R);
898 struct dccp_feat_entry *entry;
899 dccp_feat_val fval;
901 if (len == 0 || type == FEAT_UNKNOWN) /* 6.1 and 6.6.8 */
902 goto unknown_feature_or_value;
905 * Negotiation of NN features: Change R is invalid, so there is no
906 * simultaneous negotiation; hence we do not look up in the list.
908 if (type == FEAT_NN) {
909 if (local || len > sizeof(fval.nn))
910 goto unknown_feature_or_value;
912 /* 6.3.2: "The feature remote MUST accept any valid value..." */
913 fval.nn = dccp_decode_value_var(val, len);
914 if (!dccp_feat_is_valid_nn_val(feat, fval.nn))
915 goto unknown_feature_or_value;
917 return dccp_feat_push_confirm(fn, feat, local, &fval);
921 * Unidirectional/simultaneous negotiation of SP features (6.3.1)
923 entry = dccp_feat_list_lookup(fn, feat, local);
924 if (entry == NULL) {
926 * No particular preferences have been registered. We deal with
927 * this situation by assuming that all valid values are equally
928 * acceptable, and apply the following checks:
929 * - if the peer's list is a singleton, we accept a valid value;
930 * - if we are the server, we first try to see if the peer (the
931 * client) advertises the default value. If yes, we use it,
932 * otherwise we accept the preferred value;
933 * - else if we are the client, we use the first list element.
935 if (dccp_feat_clone_sp_val(&fval, val, 1))
936 return DCCP_RESET_CODE_TOO_BUSY;
938 if (len > 1 && server) {
939 defval = dccp_feat_default_value(feat);
940 if (dccp_feat_preflist_match(&defval, 1, val, len) > -1)
941 fval.sp.vec[0] = defval;
942 } else if (!dccp_feat_is_valid_sp_val(feat, fval.sp.vec[0])) {
943 kfree(fval.sp.vec);
944 goto unknown_feature_or_value;
947 /* Treat unsupported CCIDs like invalid values */
948 if (feat == DCCPF_CCID && !ccid_support_check(fval.sp.vec, 1)) {
949 kfree(fval.sp.vec);
950 goto not_valid_or_not_known;
953 return dccp_feat_push_confirm(fn, feat, local, &fval);
955 } else if (entry->state == FEAT_UNSTABLE) { /* 6.6.2 */
956 return 0;
959 if (dccp_feat_reconcile(&entry->val, val, len, server, true)) {
960 entry->empty_confirm = 0;
961 } else if (is_mandatory) {
962 return DCCP_RESET_CODE_MANDATORY_ERROR;
963 } else if (entry->state == FEAT_INITIALISING) {
965 * Failed simultaneous negotiation (server only): try to `save'
966 * the connection by checking whether entry contains the default
967 * value for @feat. If yes, send an empty Confirm to signal that
968 * the received Change was not understood - which implies using
969 * the default value.
970 * If this also fails, we use Reset as the last resort.
972 WARN_ON(!server);
973 defval = dccp_feat_default_value(feat);
974 if (!dccp_feat_reconcile(&entry->val, &defval, 1, server, true))
975 return DCCP_RESET_CODE_OPTION_ERROR;
976 entry->empty_confirm = 1;
978 entry->needs_confirm = 1;
979 entry->needs_mandatory = 0;
980 entry->state = FEAT_STABLE;
981 return 0;
983 unknown_feature_or_value:
984 if (!is_mandatory)
985 return dccp_push_empty_confirm(fn, feat, local);
987 not_valid_or_not_known:
988 return is_mandatory ? DCCP_RESET_CODE_MANDATORY_ERROR
989 : DCCP_RESET_CODE_OPTION_ERROR;
993 * dccp_feat_confirm_recv - Process received Confirm options
994 * @fn: feature-negotiation list to update
995 * @is_mandatory: whether @opt was preceded by a Mandatory option
996 * @opt: %DCCPO_CONFIRM_L or %DCCPO_CONFIRM_R
997 * @feat: one of %dccp_feature_numbers
998 * @val: NN value or SP value/preference list
999 * @len: length of @val in bytes
1000 * @server: whether this node is server (1) or client (0)
1002 static u8 dccp_feat_confirm_recv(struct list_head *fn, u8 is_mandatory, u8 opt,
1003 u8 feat, u8 *val, u8 len, const bool server)
1005 u8 *plist, plen, type = dccp_feat_type(feat);
1006 const bool local = (opt == DCCPO_CONFIRM_R);
1007 struct dccp_feat_entry *entry = dccp_feat_list_lookup(fn, feat, local);
1009 if (entry == NULL) { /* nothing queued: ignore or handle error */
1010 if (is_mandatory && type == FEAT_UNKNOWN)
1011 return DCCP_RESET_CODE_MANDATORY_ERROR;
1013 if (!local && type == FEAT_NN) /* 6.3.2 */
1014 goto confirmation_failed;
1015 return 0;
1018 if (entry->state != FEAT_CHANGING) /* 6.6.2 */
1019 return 0;
1021 if (len == 0) {
1022 if (dccp_feat_must_be_understood(feat)) /* 6.6.7 */
1023 goto confirmation_failed;
1025 * Empty Confirm during connection setup: this means reverting
1026 * to the `old' value, which in this case is the default. Since
1027 * we handle default values automatically when no other values
1028 * have been set, we revert to the old value by removing this
1029 * entry from the list.
1031 dccp_feat_list_pop(entry);
1032 return 0;
1035 if (type == FEAT_NN) {
1036 if (len > sizeof(entry->val.nn))
1037 goto confirmation_failed;
1039 if (entry->val.nn == dccp_decode_value_var(val, len))
1040 goto confirmation_succeeded;
1042 DCCP_WARN("Bogus Confirm for non-existing value\n");
1043 goto confirmation_failed;
1047 * Parsing SP Confirms: the first element of @val is the preferred
1048 * SP value which the peer confirms, the remainder depends on @len.
1049 * Note that only the confirmed value need to be a valid SP value.
1051 if (!dccp_feat_is_valid_sp_val(feat, *val))
1052 goto confirmation_failed;
1054 if (len == 1) { /* peer didn't supply a preference list */
1055 plist = val;
1056 plen = len;
1057 } else { /* preferred value + preference list */
1058 plist = val + 1;
1059 plen = len - 1;
1062 /* Check whether the peer got the reconciliation right (6.6.8) */
1063 if (dccp_feat_reconcile(&entry->val, plist, plen, server, 0) != *val) {
1064 DCCP_WARN("Confirm selected the wrong value %u\n", *val);
1065 return DCCP_RESET_CODE_OPTION_ERROR;
1067 entry->val.sp.vec[0] = *val;
1069 confirmation_succeeded:
1070 entry->state = FEAT_STABLE;
1071 return 0;
1073 confirmation_failed:
1074 DCCP_WARN("Confirmation failed\n");
1075 return is_mandatory ? DCCP_RESET_CODE_MANDATORY_ERROR
1076 : DCCP_RESET_CODE_OPTION_ERROR;
1080 * dccp_feat_parse_options - Process Feature-Negotiation Options
1081 * @sk: for general use and used by the client during connection setup
1082 * @dreq: used by the server during connection setup
1083 * @mandatory: whether @opt was preceded by a Mandatory option
1084 * @opt: %DCCPO_CHANGE_L | %DCCPO_CHANGE_R | %DCCPO_CONFIRM_L | %DCCPO_CONFIRM_R
1085 * @feat: one of %dccp_feature_numbers
1086 * @val: value contents of @opt
1087 * @len: length of @val in bytes
1088 * Returns 0 on success, a Reset code for ending the connection otherwise.
1090 int dccp_feat_parse_options(struct sock *sk, struct dccp_request_sock *dreq,
1091 u8 mandatory, u8 opt, u8 feat, u8 *val, u8 len)
1093 struct dccp_sock *dp = dccp_sk(sk);
1094 struct list_head *fn = dreq ? &dreq->dreq_featneg : &dp->dccps_featneg;
1095 bool server = false;
1097 switch (sk->sk_state) {
1099 * Negotiation during connection setup
1101 case DCCP_LISTEN:
1102 server = true; /* fall through */
1103 case DCCP_REQUESTING:
1104 switch (opt) {
1105 case DCCPO_CHANGE_L:
1106 case DCCPO_CHANGE_R:
1107 return dccp_feat_change_recv(fn, mandatory, opt, feat,
1108 val, len, server);
1109 case DCCPO_CONFIRM_R:
1110 case DCCPO_CONFIRM_L:
1111 return dccp_feat_confirm_recv(fn, mandatory, opt, feat,
1112 val, len, server);
1115 return 0; /* ignore FN options in all other states */
1118 int dccp_feat_init(struct sock *sk)
1120 struct dccp_sock *dp = dccp_sk(sk);
1121 struct dccp_minisock *dmsk = dccp_msk(sk);
1122 int rc;
1124 INIT_LIST_HEAD(&dmsk->dccpms_pending); /* XXX no longer used */
1125 INIT_LIST_HEAD(&dmsk->dccpms_conf); /* XXX no longer used */
1127 /* Ack ratio */
1128 rc = __feat_register_nn(&dp->dccps_featneg, DCCPF_ACK_RATIO, 0,
1129 dp->dccps_l_ack_ratio);
1130 return rc;
1133 EXPORT_SYMBOL_GPL(dccp_feat_init);
1135 int dccp_feat_activate_values(struct sock *sk, struct list_head *fn_list)
1137 struct dccp_sock *dp = dccp_sk(sk);
1138 struct dccp_feat_entry *cur, *next;
1139 int idx;
1140 dccp_feat_val *fvals[DCCP_FEAT_SUPPORTED_MAX][2] = {
1141 [0 ... DCCP_FEAT_SUPPORTED_MAX-1] = { NULL, NULL }
1144 list_for_each_entry(cur, fn_list, node) {
1146 * An empty Confirm means that either an unknown feature type
1147 * or an invalid value was present. In the first case there is
1148 * nothing to activate, in the other the default value is used.
1150 if (cur->empty_confirm)
1151 continue;
1153 idx = dccp_feat_index(cur->feat_num);
1154 if (idx < 0) {
1155 DCCP_BUG("Unknown feature %u", cur->feat_num);
1156 goto activation_failed;
1158 if (cur->state != FEAT_STABLE) {
1159 DCCP_CRIT("Negotiation of %s %u failed in state %u",
1160 cur->is_local ? "local" : "remote",
1161 cur->feat_num, cur->state);
1162 goto activation_failed;
1164 fvals[idx][cur->is_local] = &cur->val;
1168 * Activate in decreasing order of index, so that the CCIDs are always
1169 * activated as the last feature. This avoids the case where a CCID
1170 * relies on the initialisation of one or more features that it depends
1171 * on (e.g. Send NDP Count, Send Ack Vector, and Ack Ratio features).
1173 for (idx = DCCP_FEAT_SUPPORTED_MAX; --idx >= 0;)
1174 if (__dccp_feat_activate(sk, idx, 0, fvals[idx][0]) ||
1175 __dccp_feat_activate(sk, idx, 1, fvals[idx][1])) {
1176 DCCP_CRIT("Could not activate %d", idx);
1177 goto activation_failed;
1180 /* Clean up Change options which have been confirmed already */
1181 list_for_each_entry_safe(cur, next, fn_list, node)
1182 if (!cur->needs_confirm)
1183 dccp_feat_list_pop(cur);
1185 dccp_pr_debug("Activation OK\n");
1186 return 0;
1188 activation_failed:
1190 * We clean up everything that may have been allocated, since
1191 * it is difficult to track at which stage negotiation failed.
1192 * This is ok, since all allocation functions below are robust
1193 * against NULL arguments.
1195 ccid_hc_rx_delete(dp->dccps_hc_rx_ccid, sk);
1196 ccid_hc_tx_delete(dp->dccps_hc_tx_ccid, sk);
1197 dp->dccps_hc_rx_ccid = dp->dccps_hc_tx_ccid = NULL;
1198 dccp_ackvec_free(dp->dccps_hc_rx_ackvec);
1199 dp->dccps_hc_rx_ackvec = NULL;
1200 return -1;
1203 #ifdef CONFIG_IP_DCCP_DEBUG
1204 const char *dccp_feat_typename(const u8 type)
1206 switch(type) {
1207 case DCCPO_CHANGE_L: return("ChangeL");
1208 case DCCPO_CONFIRM_L: return("ConfirmL");
1209 case DCCPO_CHANGE_R: return("ChangeR");
1210 case DCCPO_CONFIRM_R: return("ConfirmR");
1211 /* the following case must not appear in feature negotation */
1212 default: dccp_pr_debug("unknown type %d [BUG!]\n", type);
1214 return NULL;
1217 const char *dccp_feat_name(const u8 feat)
1219 static const char *feature_names[] = {
1220 [DCCPF_RESERVED] = "Reserved",
1221 [DCCPF_CCID] = "CCID",
1222 [DCCPF_SHORT_SEQNOS] = "Allow Short Seqnos",
1223 [DCCPF_SEQUENCE_WINDOW] = "Sequence Window",
1224 [DCCPF_ECN_INCAPABLE] = "ECN Incapable",
1225 [DCCPF_ACK_RATIO] = "Ack Ratio",
1226 [DCCPF_SEND_ACK_VECTOR] = "Send ACK Vector",
1227 [DCCPF_SEND_NDP_COUNT] = "Send NDP Count",
1228 [DCCPF_MIN_CSUM_COVER] = "Min. Csum Coverage",
1229 [DCCPF_DATA_CHECKSUM] = "Send Data Checksum",
1231 if (feat > DCCPF_DATA_CHECKSUM && feat < DCCPF_MIN_CCID_SPECIFIC)
1232 return feature_names[DCCPF_RESERVED];
1234 if (feat == DCCPF_SEND_LEV_RATE)
1235 return "Send Loss Event Rate";
1236 if (feat >= DCCPF_MIN_CCID_SPECIFIC)
1237 return "CCID-specific";
1239 return feature_names[feat];
1241 #endif /* CONFIG_IP_DCCP_DEBUG */