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>
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 Changing non-negotiable (NN) values is supported in state OPEN/PARTOPEN.
16 * o All currently known SP features have 1-byte quantities. If in the future
17 * extensions of RFCs 4340..42 define features with item lengths larger than
18 * one byte, a feature-specific extension of the code will be required.
20 * This program is free software; you can redistribute it and/or
21 * modify it under the terms of the GNU General Public License
22 * as published by the Free Software Foundation; either version
23 * 2 of the License, or (at your option) any later version.
25 #include <linux/module.h>
26 #include <linux/slab.h>
30 /* feature-specific sysctls - initialised to the defaults from RFC 4340, 6.4 */
31 unsigned long sysctl_dccp_sequence_window __read_mostly = 100;
32 int sysctl_dccp_rx_ccid __read_mostly = 2,
33 sysctl_dccp_tx_ccid __read_mostly = 2;
36 * Feature activation handlers.
38 * These all use an u64 argument, to provide enough room for NN/SP features. At
39 * this stage the negotiated values have been checked to be within their range.
41 static int dccp_hdlr_ccid(struct sock *sk, u64 ccid, bool rx)
43 struct dccp_sock *dp = dccp_sk(sk);
44 struct ccid *new_ccid = ccid_new(ccid, sk, rx);
50 ccid_hc_rx_delete(dp->dccps_hc_rx_ccid, sk);
51 dp->dccps_hc_rx_ccid = new_ccid;
53 ccid_hc_tx_delete(dp->dccps_hc_tx_ccid, sk);
54 dp->dccps_hc_tx_ccid = new_ccid;
59 static int dccp_hdlr_seq_win(struct sock *sk, u64 seq_win, bool rx)
61 struct dccp_sock *dp = dccp_sk(sk);
64 dp->dccps_r_seq_win = seq_win;
65 /* propagate changes to update SWL/SWH */
66 dccp_update_gsr(sk, dp->dccps_gsr);
68 dp->dccps_l_seq_win = seq_win;
69 /* propagate changes to update AWL */
70 dccp_update_gss(sk, dp->dccps_gss);
75 static int dccp_hdlr_ack_ratio(struct sock *sk, u64 ratio, bool rx)
78 dccp_sk(sk)->dccps_r_ack_ratio = ratio;
80 dccp_sk(sk)->dccps_l_ack_ratio = ratio;
84 static int dccp_hdlr_ackvec(struct sock *sk, u64 enable, bool rx)
86 struct dccp_sock *dp = dccp_sk(sk);
89 if (enable && dp->dccps_hc_rx_ackvec == NULL) {
90 dp->dccps_hc_rx_ackvec = dccp_ackvec_alloc(gfp_any());
91 if (dp->dccps_hc_rx_ackvec == NULL)
94 dccp_ackvec_free(dp->dccps_hc_rx_ackvec);
95 dp->dccps_hc_rx_ackvec = NULL;
101 static int dccp_hdlr_ndp(struct sock *sk, u64 enable, bool rx)
104 dccp_sk(sk)->dccps_send_ndp_count = (enable > 0);
109 * Minimum Checksum Coverage is located at the RX side (9.2.1). This means that
110 * `rx' holds when the sending peer informs about his partial coverage via a
111 * ChangeR() option. In the other case, we are the sender and the receiver
112 * announces its coverage via ChangeL() options. The policy here is to honour
113 * such communication by enabling the corresponding partial coverage - but only
114 * if it has not been set manually before; the warning here means that all
115 * packets will be dropped.
117 static int dccp_hdlr_min_cscov(struct sock *sk, u64 cscov, bool rx)
119 struct dccp_sock *dp = dccp_sk(sk);
122 dp->dccps_pcrlen = cscov;
124 if (dp->dccps_pcslen == 0)
125 dp->dccps_pcslen = cscov;
126 else if (cscov > dp->dccps_pcslen)
127 DCCP_WARN("CsCov %u too small, peer requires >= %u\n",
128 dp->dccps_pcslen, (u8)cscov);
133 static const struct {
134 u8 feat_num; /* DCCPF_xxx */
135 enum dccp_feat_type rxtx; /* RX or TX */
136 enum dccp_feat_type reconciliation; /* SP or NN */
137 u8 default_value; /* as in 6.4 */
138 int (*activation_hdlr)(struct sock *sk, u64 val, bool rx);
140 * Lookup table for location and type of features (from RFC 4340/4342)
141 * +--------------------------+----+-----+----+----+---------+-----------+
142 * | Feature | Location | Reconc. | Initial | Section |
143 * | | RX | TX | SP | NN | Value | Reference |
144 * +--------------------------+----+-----+----+----+---------+-----------+
145 * | DCCPF_CCID | | X | X | | 2 | 10 |
146 * | DCCPF_SHORT_SEQNOS | | X | X | | 0 | 7.6.1 |
147 * | DCCPF_SEQUENCE_WINDOW | | X | | X | 100 | 7.5.2 |
148 * | DCCPF_ECN_INCAPABLE | X | | X | | 0 | 12.1 |
149 * | DCCPF_ACK_RATIO | | X | | X | 2 | 11.3 |
150 * | DCCPF_SEND_ACK_VECTOR | X | | X | | 0 | 11.5 |
151 * | DCCPF_SEND_NDP_COUNT | | X | X | | 0 | 7.7.2 |
152 * | DCCPF_MIN_CSUM_COVER | X | | X | | 0 | 9.2.1 |
153 * | DCCPF_DATA_CHECKSUM | X | | X | | 0 | 9.3.1 |
154 * | DCCPF_SEND_LEV_RATE | X | | X | | 0 | 4342/8.4 |
155 * +--------------------------+----+-----+----+----+---------+-----------+
157 } dccp_feat_table[] = {
158 { DCCPF_CCID, FEAT_AT_TX, FEAT_SP, 2, dccp_hdlr_ccid },
159 { DCCPF_SHORT_SEQNOS, FEAT_AT_TX, FEAT_SP, 0, NULL },
160 { DCCPF_SEQUENCE_WINDOW, FEAT_AT_TX, FEAT_NN, 100, dccp_hdlr_seq_win },
161 { DCCPF_ECN_INCAPABLE, FEAT_AT_RX, FEAT_SP, 0, NULL },
162 { DCCPF_ACK_RATIO, FEAT_AT_TX, FEAT_NN, 2, dccp_hdlr_ack_ratio},
163 { DCCPF_SEND_ACK_VECTOR, FEAT_AT_RX, FEAT_SP, 0, dccp_hdlr_ackvec },
164 { DCCPF_SEND_NDP_COUNT, FEAT_AT_TX, FEAT_SP, 0, dccp_hdlr_ndp },
165 { DCCPF_MIN_CSUM_COVER, FEAT_AT_RX, FEAT_SP, 0, dccp_hdlr_min_cscov},
166 { DCCPF_DATA_CHECKSUM, FEAT_AT_RX, FEAT_SP, 0, NULL },
167 { DCCPF_SEND_LEV_RATE, FEAT_AT_RX, FEAT_SP, 0, NULL },
169 #define DCCP_FEAT_SUPPORTED_MAX ARRAY_SIZE(dccp_feat_table)
172 * dccp_feat_index - Hash function to map feature number into array position
173 * Returns consecutive array index or -1 if the feature is not understood.
175 static int dccp_feat_index(u8 feat_num)
177 /* The first 9 entries are occupied by the types from RFC 4340, 6.4 */
178 if (feat_num > DCCPF_RESERVED && feat_num <= DCCPF_DATA_CHECKSUM)
182 * Other features: add cases for new feature types here after adding
183 * them to the above table.
186 case DCCPF_SEND_LEV_RATE:
187 return DCCP_FEAT_SUPPORTED_MAX - 1;
192 static u8 dccp_feat_type(u8 feat_num)
194 int idx = dccp_feat_index(feat_num);
198 return dccp_feat_table[idx].reconciliation;
201 static int dccp_feat_default_value(u8 feat_num)
203 int idx = dccp_feat_index(feat_num);
205 * There are no default values for unknown features, so encountering a
206 * negative index here indicates a serious problem somewhere else.
208 DCCP_BUG_ON(idx < 0);
210 return idx < 0 ? 0 : dccp_feat_table[idx].default_value;
214 * Debugging and verbose-printing section
216 static const char *dccp_feat_fname(const u8 feat)
218 static const char *const feature_names[] = {
219 [DCCPF_RESERVED] = "Reserved",
220 [DCCPF_CCID] = "CCID",
221 [DCCPF_SHORT_SEQNOS] = "Allow Short Seqnos",
222 [DCCPF_SEQUENCE_WINDOW] = "Sequence Window",
223 [DCCPF_ECN_INCAPABLE] = "ECN Incapable",
224 [DCCPF_ACK_RATIO] = "Ack Ratio",
225 [DCCPF_SEND_ACK_VECTOR] = "Send ACK Vector",
226 [DCCPF_SEND_NDP_COUNT] = "Send NDP Count",
227 [DCCPF_MIN_CSUM_COVER] = "Min. Csum Coverage",
228 [DCCPF_DATA_CHECKSUM] = "Send Data Checksum",
230 if (feat > DCCPF_DATA_CHECKSUM && feat < DCCPF_MIN_CCID_SPECIFIC)
231 return feature_names[DCCPF_RESERVED];
233 if (feat == DCCPF_SEND_LEV_RATE)
234 return "Send Loss Event Rate";
235 if (feat >= DCCPF_MIN_CCID_SPECIFIC)
236 return "CCID-specific";
238 return feature_names[feat];
241 static const char *const dccp_feat_sname[] = {
242 "DEFAULT", "INITIALISING", "CHANGING", "UNSTABLE", "STABLE",
245 #ifdef CONFIG_IP_DCCP_DEBUG
246 static const char *dccp_feat_oname(const u8 opt)
249 case DCCPO_CHANGE_L: return "Change_L";
250 case DCCPO_CONFIRM_L: return "Confirm_L";
251 case DCCPO_CHANGE_R: return "Change_R";
252 case DCCPO_CONFIRM_R: return "Confirm_R";
257 static void dccp_feat_printval(u8 feat_num, dccp_feat_val const *val)
259 u8 i, type = dccp_feat_type(feat_num);
261 if (val == NULL || (type == FEAT_SP && val->sp.vec == NULL))
262 dccp_pr_debug_cat("(NULL)");
263 else if (type == FEAT_SP)
264 for (i = 0; i < val->sp.len; i++)
265 dccp_pr_debug_cat("%s%u", i ? " " : "", val->sp.vec[i]);
266 else if (type == FEAT_NN)
267 dccp_pr_debug_cat("%llu", (unsigned long long)val->nn);
269 dccp_pr_debug_cat("unknown type %u", type);
272 static void dccp_feat_printvals(u8 feat_num, u8 *list, u8 len)
274 u8 type = dccp_feat_type(feat_num);
275 dccp_feat_val fval = { .sp.vec = list, .sp.len = len };
278 fval.nn = dccp_decode_value_var(list, len);
279 dccp_feat_printval(feat_num, &fval);
282 static void dccp_feat_print_entry(struct dccp_feat_entry const *entry)
284 dccp_debug(" * %s %s = ", entry->is_local ? "local" : "remote",
285 dccp_feat_fname(entry->feat_num));
286 dccp_feat_printval(entry->feat_num, &entry->val);
287 dccp_pr_debug_cat(", state=%s %s\n", dccp_feat_sname[entry->state],
288 entry->needs_confirm ? "(Confirm pending)" : "");
291 #define dccp_feat_print_opt(opt, feat, val, len, mandatory) do { \
292 dccp_pr_debug("%s(%s, ", dccp_feat_oname(opt), dccp_feat_fname(feat));\
293 dccp_feat_printvals(feat, val, len); \
294 dccp_pr_debug_cat(") %s\n", mandatory ? "!" : ""); } while (0)
296 #define dccp_feat_print_fnlist(fn_list) { \
297 const struct dccp_feat_entry *___entry; \
299 dccp_pr_debug("List Dump:\n"); \
300 list_for_each_entry(___entry, fn_list, node) \
301 dccp_feat_print_entry(___entry); \
303 #else /* ! CONFIG_IP_DCCP_DEBUG */
304 #define dccp_feat_print_opt(opt, feat, val, len, mandatory)
305 #define dccp_feat_print_fnlist(fn_list)
308 static int __dccp_feat_activate(struct sock *sk, const int idx,
309 const bool is_local, dccp_feat_val const *fval)
314 if (idx < 0 || idx >= DCCP_FEAT_SUPPORTED_MAX)
316 if (dccp_feat_table[idx].activation_hdlr == NULL)
320 val = dccp_feat_table[idx].default_value;
321 } else if (dccp_feat_table[idx].reconciliation == FEAT_SP) {
322 if (fval->sp.vec == NULL) {
324 * This can happen when an empty Confirm is sent
325 * for an SP (i.e. known) feature. In this case
326 * we would be using the default anyway.
328 DCCP_CRIT("Feature #%d undefined: using default", idx);
329 val = dccp_feat_table[idx].default_value;
331 val = fval->sp.vec[0];
337 /* Location is RX if this is a local-RX or remote-TX feature */
338 rx = (is_local == (dccp_feat_table[idx].rxtx == FEAT_AT_RX));
340 dccp_debug(" -> activating %s %s, %sval=%llu\n", rx ? "RX" : "TX",
341 dccp_feat_fname(dccp_feat_table[idx].feat_num),
342 fval ? "" : "default ", (unsigned long long)val);
344 return dccp_feat_table[idx].activation_hdlr(sk, val, rx);
348 * dccp_feat_activate - Activate feature value on socket
349 * @sk: fully connected DCCP socket (after handshake is complete)
350 * @feat_num: feature to activate, one of %dccp_feature_numbers
351 * @local: whether local (1) or remote (0) @feat_num is meant
352 * @fval: the value (SP or NN) to activate, or NULL to use the default value
354 * For general use this function is preferable over __dccp_feat_activate().
356 static int dccp_feat_activate(struct sock *sk, u8 feat_num, bool local,
357 dccp_feat_val const *fval)
359 return __dccp_feat_activate(sk, dccp_feat_index(feat_num), local, fval);
362 /* Test for "Req'd" feature (RFC 4340, 6.4) */
363 static inline int dccp_feat_must_be_understood(u8 feat_num)
365 return feat_num == DCCPF_CCID || feat_num == DCCPF_SHORT_SEQNOS ||
366 feat_num == DCCPF_SEQUENCE_WINDOW;
369 /* copy constructor, fval must not already contain allocated memory */
370 static int dccp_feat_clone_sp_val(dccp_feat_val *fval, u8 const *val, u8 len)
373 if (fval->sp.len > 0) {
374 fval->sp.vec = kmemdup(val, len, gfp_any());
375 if (fval->sp.vec == NULL) {
383 static void dccp_feat_val_destructor(u8 feat_num, dccp_feat_val *val)
385 if (unlikely(val == NULL))
387 if (dccp_feat_type(feat_num) == FEAT_SP)
389 memset(val, 0, sizeof(*val));
392 static struct dccp_feat_entry *
393 dccp_feat_clone_entry(struct dccp_feat_entry const *original)
395 struct dccp_feat_entry *new;
396 u8 type = dccp_feat_type(original->feat_num);
398 if (type == FEAT_UNKNOWN)
401 new = kmemdup(original, sizeof(struct dccp_feat_entry), gfp_any());
405 if (type == FEAT_SP && dccp_feat_clone_sp_val(&new->val,
406 original->val.sp.vec,
407 original->val.sp.len)) {
414 static void dccp_feat_entry_destructor(struct dccp_feat_entry *entry)
417 dccp_feat_val_destructor(entry->feat_num, &entry->val);
423 * List management functions
425 * Feature negotiation lists rely on and maintain the following invariants:
426 * - each feat_num in the list is known, i.e. we know its type and default value
427 * - each feat_num/is_local combination is unique (old entries are overwritten)
428 * - SP values are always freshly allocated
429 * - list is sorted in increasing order of feature number (faster lookup)
431 static struct dccp_feat_entry *dccp_feat_list_lookup(struct list_head *fn_list,
432 u8 feat_num, bool is_local)
434 struct dccp_feat_entry *entry;
436 list_for_each_entry(entry, fn_list, node) {
437 if (entry->feat_num == feat_num && entry->is_local == is_local)
439 else if (entry->feat_num > feat_num)
446 * dccp_feat_entry_new - Central list update routine (called by all others)
447 * @head: list to add to
448 * @feat: feature number
449 * @local: whether the local (1) or remote feature with number @feat is meant
451 * This is the only constructor and serves to ensure the above invariants.
453 static struct dccp_feat_entry *
454 dccp_feat_entry_new(struct list_head *head, u8 feat, bool local)
456 struct dccp_feat_entry *entry;
458 list_for_each_entry(entry, head, node)
459 if (entry->feat_num == feat && entry->is_local == local) {
460 dccp_feat_val_destructor(entry->feat_num, &entry->val);
462 } else if (entry->feat_num > feat) {
467 entry = kmalloc(sizeof(*entry), gfp_any());
469 entry->feat_num = feat;
470 entry->is_local = local;
471 list_add_tail(&entry->node, head);
477 * dccp_feat_push_change - Add/overwrite a Change option in the list
478 * @fn_list: feature-negotiation list to update
479 * @feat: one of %dccp_feature_numbers
480 * @local: whether local (1) or remote (0) @feat_num is meant
481 * @mandatory: whether to use Mandatory feature negotiation options
482 * @fval: pointer to NN/SP value to be inserted (will be copied)
484 static int dccp_feat_push_change(struct list_head *fn_list, u8 feat, u8 local,
485 u8 mandatory, dccp_feat_val *fval)
487 struct dccp_feat_entry *new = dccp_feat_entry_new(fn_list, feat, local);
492 new->feat_num = feat;
493 new->is_local = local;
494 new->state = FEAT_INITIALISING;
495 new->needs_confirm = false;
496 new->empty_confirm = false;
498 new->needs_mandatory = mandatory;
504 * dccp_feat_push_confirm - Add a Confirm entry to the FN list
505 * @fn_list: feature-negotiation list to add to
506 * @feat: one of %dccp_feature_numbers
507 * @local: whether local (1) or remote (0) @feat_num is being confirmed
508 * @fval: pointer to NN/SP value to be inserted or NULL
510 * Returns 0 on success, a Reset code for further processing otherwise.
512 static int dccp_feat_push_confirm(struct list_head *fn_list, u8 feat, u8 local,
515 struct dccp_feat_entry *new = dccp_feat_entry_new(fn_list, feat, local);
518 return DCCP_RESET_CODE_TOO_BUSY;
520 new->feat_num = feat;
521 new->is_local = local;
522 new->state = FEAT_STABLE; /* transition in 6.6.2 */
523 new->needs_confirm = true;
524 new->empty_confirm = (fval == NULL);
525 new->val.nn = 0; /* zeroes the whole structure */
526 if (!new->empty_confirm)
528 new->needs_mandatory = false;
533 static int dccp_push_empty_confirm(struct list_head *fn_list, u8 feat, u8 local)
535 return dccp_feat_push_confirm(fn_list, feat, local, NULL);
538 static inline void dccp_feat_list_pop(struct dccp_feat_entry *entry)
540 list_del(&entry->node);
541 dccp_feat_entry_destructor(entry);
544 void dccp_feat_list_purge(struct list_head *fn_list)
546 struct dccp_feat_entry *entry, *next;
548 list_for_each_entry_safe(entry, next, fn_list, node)
549 dccp_feat_entry_destructor(entry);
550 INIT_LIST_HEAD(fn_list);
552 EXPORT_SYMBOL_GPL(dccp_feat_list_purge);
554 /* generate @to as full clone of @from - @to must not contain any nodes */
555 int dccp_feat_clone_list(struct list_head const *from, struct list_head *to)
557 struct dccp_feat_entry *entry, *new;
560 list_for_each_entry(entry, from, node) {
561 new = dccp_feat_clone_entry(entry);
564 list_add_tail(&new->node, to);
569 dccp_feat_list_purge(to);
574 * dccp_feat_valid_nn_length - Enforce length constraints on NN options
575 * Length is between 0 and %DCCP_OPTVAL_MAXLEN. Used for outgoing packets only,
576 * incoming options are accepted as long as their values are valid.
578 static u8 dccp_feat_valid_nn_length(u8 feat_num)
580 if (feat_num == DCCPF_ACK_RATIO) /* RFC 4340, 11.3 and 6.6.8 */
582 if (feat_num == DCCPF_SEQUENCE_WINDOW) /* RFC 4340, 7.5.2 and 6.5 */
587 static u8 dccp_feat_is_valid_nn_val(u8 feat_num, u64 val)
590 case DCCPF_ACK_RATIO:
591 return val <= DCCPF_ACK_RATIO_MAX;
592 case DCCPF_SEQUENCE_WINDOW:
593 return val >= DCCPF_SEQ_WMIN && val <= DCCPF_SEQ_WMAX;
595 return 0; /* feature unknown - so we can't tell */
598 /* check that SP values are within the ranges defined in RFC 4340 */
599 static u8 dccp_feat_is_valid_sp_val(u8 feat_num, u8 val)
603 return val == DCCPC_CCID2 || val == DCCPC_CCID3;
604 /* Type-check Boolean feature values: */
605 case DCCPF_SHORT_SEQNOS:
606 case DCCPF_ECN_INCAPABLE:
607 case DCCPF_SEND_ACK_VECTOR:
608 case DCCPF_SEND_NDP_COUNT:
609 case DCCPF_DATA_CHECKSUM:
610 case DCCPF_SEND_LEV_RATE:
612 case DCCPF_MIN_CSUM_COVER:
615 return 0; /* feature unknown */
618 static u8 dccp_feat_sp_list_ok(u8 feat_num, u8 const *sp_list, u8 sp_len)
620 if (sp_list == NULL || sp_len < 1)
623 if (!dccp_feat_is_valid_sp_val(feat_num, *sp_list++))
629 * dccp_feat_insert_opts - Generate FN options from current list state
630 * @skb: next sk_buff to be sent to the peer
631 * @dp: for client during handshake and general negotiation
632 * @dreq: used by the server only (all Changes/Confirms in LISTEN/RESPOND)
634 int dccp_feat_insert_opts(struct dccp_sock *dp, struct dccp_request_sock *dreq,
637 struct list_head *fn = dreq ? &dreq->dreq_featneg : &dp->dccps_featneg;
638 struct dccp_feat_entry *pos, *next;
639 u8 opt, type, len, *ptr, nn_in_nbo[DCCP_OPTVAL_MAXLEN];
642 /* put entries into @skb in the order they appear in the list */
643 list_for_each_entry_safe_reverse(pos, next, fn, node) {
644 opt = dccp_feat_genopt(pos);
645 type = dccp_feat_type(pos->feat_num);
648 if (pos->empty_confirm) {
652 if (type == FEAT_SP) {
653 len = pos->val.sp.len;
654 ptr = pos->val.sp.vec;
655 rpt = pos->needs_confirm;
656 } else if (type == FEAT_NN) {
657 len = dccp_feat_valid_nn_length(pos->feat_num);
659 dccp_encode_value_var(pos->val.nn, ptr, len);
661 DCCP_BUG("unknown feature %u", pos->feat_num);
665 dccp_feat_print_opt(opt, pos->feat_num, ptr, len, 0);
667 if (dccp_insert_fn_opt(skb, opt, pos->feat_num, ptr, len, rpt))
669 if (pos->needs_mandatory && dccp_insert_option_mandatory(skb))
672 if (skb->sk->sk_state == DCCP_OPEN &&
673 (opt == DCCPO_CONFIRM_R || opt == DCCPO_CONFIRM_L)) {
675 * Confirms don't get retransmitted (6.6.3) once the
676 * connection is in state OPEN
678 dccp_feat_list_pop(pos);
681 * Enter CHANGING after transmitting the Change
684 if (pos->state == FEAT_INITIALISING)
685 pos->state = FEAT_CHANGING;
692 * __feat_register_nn - Register new NN value on socket
693 * @fn: feature-negotiation list to register with
694 * @feat: an NN feature from %dccp_feature_numbers
695 * @mandatory: use Mandatory option if 1
696 * @nn_val: value to register (restricted to 4 bytes)
698 * Note that NN features are local by definition (RFC 4340, 6.3.2).
700 static int __feat_register_nn(struct list_head *fn, u8 feat,
701 u8 mandatory, u64 nn_val)
703 dccp_feat_val fval = { .nn = nn_val };
705 if (dccp_feat_type(feat) != FEAT_NN ||
706 !dccp_feat_is_valid_nn_val(feat, nn_val))
709 /* Don't bother with default values, they will be activated anyway. */
710 if (nn_val - (u64)dccp_feat_default_value(feat) == 0)
713 return dccp_feat_push_change(fn, feat, 1, mandatory, &fval);
717 * __feat_register_sp - Register new SP value/list on socket
718 * @fn: feature-negotiation list to register with
719 * @feat: an SP feature from %dccp_feature_numbers
720 * @is_local: whether the local (1) or the remote (0) @feat is meant
721 * @mandatory: use Mandatory option if 1
722 * @sp_val: SP value followed by optional preference list
723 * @sp_len: length of @sp_val in bytes
725 static int __feat_register_sp(struct list_head *fn, u8 feat, u8 is_local,
726 u8 mandatory, u8 const *sp_val, u8 sp_len)
730 if (dccp_feat_type(feat) != FEAT_SP ||
731 !dccp_feat_sp_list_ok(feat, sp_val, sp_len))
734 /* Avoid negotiating alien CCIDs by only advertising supported ones */
735 if (feat == DCCPF_CCID && !ccid_support_check(sp_val, sp_len))
738 if (dccp_feat_clone_sp_val(&fval, sp_val, sp_len))
741 return dccp_feat_push_change(fn, feat, is_local, mandatory, &fval);
745 * dccp_feat_register_sp - Register requests to change SP feature values
746 * @sk: client or listening socket
747 * @feat: one of %dccp_feature_numbers
748 * @is_local: whether the local (1) or remote (0) @feat is meant
749 * @list: array of preferred values, in descending order of preference
750 * @len: length of @list in bytes
752 int dccp_feat_register_sp(struct sock *sk, u8 feat, u8 is_local,
753 u8 const *list, u8 len)
754 { /* any changes must be registered before establishing the connection */
755 if (sk->sk_state != DCCP_CLOSED)
757 if (dccp_feat_type(feat) != FEAT_SP)
759 return __feat_register_sp(&dccp_sk(sk)->dccps_featneg, feat, is_local,
764 * dccp_feat_nn_get - Query current/pending value of NN feature
765 * @sk: DCCP socket of an established connection
766 * @feat: NN feature number from %dccp_feature_numbers
768 * For a known NN feature, returns value currently being negotiated, or
769 * current (confirmed) value if no negotiation is going on.
771 u64 dccp_feat_nn_get(struct sock *sk, u8 feat)
773 if (dccp_feat_type(feat) == FEAT_NN) {
774 struct dccp_sock *dp = dccp_sk(sk);
775 struct dccp_feat_entry *entry;
777 entry = dccp_feat_list_lookup(&dp->dccps_featneg, feat, 1);
779 return entry->val.nn;
782 case DCCPF_ACK_RATIO:
783 return dp->dccps_l_ack_ratio;
784 case DCCPF_SEQUENCE_WINDOW:
785 return dp->dccps_l_seq_win;
788 DCCP_BUG("attempt to look up unsupported feature %u", feat);
791 EXPORT_SYMBOL_GPL(dccp_feat_nn_get);
794 * dccp_feat_signal_nn_change - Update NN values for an established connection
795 * @sk: DCCP socket of an established connection
796 * @feat: NN feature number from %dccp_feature_numbers
797 * @nn_val: the new value to use
799 * This function is used to communicate NN updates out-of-band.
801 int dccp_feat_signal_nn_change(struct sock *sk, u8 feat, u64 nn_val)
803 struct list_head *fn = &dccp_sk(sk)->dccps_featneg;
804 dccp_feat_val fval = { .nn = nn_val };
805 struct dccp_feat_entry *entry;
807 if (sk->sk_state != DCCP_OPEN && sk->sk_state != DCCP_PARTOPEN)
810 if (dccp_feat_type(feat) != FEAT_NN ||
811 !dccp_feat_is_valid_nn_val(feat, nn_val))
814 if (nn_val == dccp_feat_nn_get(sk, feat))
815 return 0; /* already set or negotiation under way */
817 entry = dccp_feat_list_lookup(fn, feat, 1);
819 dccp_pr_debug("Clobbering existing NN entry %llu -> %llu\n",
820 (unsigned long long)entry->val.nn,
821 (unsigned long long)nn_val);
822 dccp_feat_list_pop(entry);
825 inet_csk_schedule_ack(sk);
826 return dccp_feat_push_change(fn, feat, 1, 0, &fval);
828 EXPORT_SYMBOL_GPL(dccp_feat_signal_nn_change);
831 * Tracking features whose value depend on the choice of CCID
833 * This is designed with an extension in mind so that a list walk could be done
834 * before activating any features. However, the existing framework was found to
835 * work satisfactorily up until now, the automatic verification is left open.
836 * When adding new CCIDs, add a corresponding dependency table here.
838 static const struct ccid_dependency *dccp_feat_ccid_deps(u8 ccid, bool is_local)
840 static const struct ccid_dependency ccid2_dependencies[2][2] = {
842 * CCID2 mandates Ack Vectors (RFC 4341, 4.): as CCID is a TX
843 * feature and Send Ack Vector is an RX feature, `is_local'
844 * needs to be reversed.
846 { /* Dependencies of the receiver-side (remote) CCID2 */
848 .dependent_feat = DCCPF_SEND_ACK_VECTOR,
850 .is_mandatory = true,
855 { /* Dependencies of the sender-side (local) CCID2 */
857 .dependent_feat = DCCPF_SEND_ACK_VECTOR,
859 .is_mandatory = true,
865 static const struct ccid_dependency ccid3_dependencies[2][5] = {
867 * Dependencies of the receiver-side CCID3
869 { /* locally disable Ack Vectors */
870 .dependent_feat = DCCPF_SEND_ACK_VECTOR,
872 .is_mandatory = false,
875 { /* see below why Send Loss Event Rate is on */
876 .dependent_feat = DCCPF_SEND_LEV_RATE,
878 .is_mandatory = true,
881 { /* NDP Count is needed as per RFC 4342, 6.1.1 */
882 .dependent_feat = DCCPF_SEND_NDP_COUNT,
884 .is_mandatory = true,
890 * CCID3 at the TX side: we request that the HC-receiver
891 * will not send Ack Vectors (they will be ignored, so
892 * Mandatory is not set); we enable Send Loss Event Rate
893 * (Mandatory since the implementation does not support
894 * the Loss Intervals option of RFC 4342, 8.6).
895 * The last two options are for peer's information only.
898 .dependent_feat = DCCPF_SEND_ACK_VECTOR,
900 .is_mandatory = false,
904 .dependent_feat = DCCPF_SEND_LEV_RATE,
906 .is_mandatory = true,
909 { /* this CCID does not support Ack Ratio */
910 .dependent_feat = DCCPF_ACK_RATIO,
912 .is_mandatory = false,
915 { /* tell receiver we are sending NDP counts */
916 .dependent_feat = DCCPF_SEND_NDP_COUNT,
918 .is_mandatory = false,
926 return ccid2_dependencies[is_local];
928 return ccid3_dependencies[is_local];
935 * dccp_feat_propagate_ccid - Resolve dependencies of features on choice of CCID
936 * @fn: feature-negotiation list to update
937 * @id: CCID number to track
938 * @is_local: whether TX CCID (1) or RX CCID (0) is meant
940 * This function needs to be called after registering all other features.
942 static int dccp_feat_propagate_ccid(struct list_head *fn, u8 id, bool is_local)
944 const struct ccid_dependency *table = dccp_feat_ccid_deps(id, is_local);
945 int i, rc = (table == NULL);
947 for (i = 0; rc == 0 && table[i].dependent_feat != DCCPF_RESERVED; i++)
948 if (dccp_feat_type(table[i].dependent_feat) == FEAT_SP)
949 rc = __feat_register_sp(fn, table[i].dependent_feat,
951 table[i].is_mandatory,
954 rc = __feat_register_nn(fn, table[i].dependent_feat,
955 table[i].is_mandatory,
961 * dccp_feat_finalise_settings - Finalise settings before starting negotiation
962 * @dp: client or listening socket (settings will be inherited)
964 * This is called after all registrations (socket initialisation, sysctls, and
965 * sockopt calls), and before sending the first packet containing Change options
966 * (ie. client-Request or server-Response), to ensure internal consistency.
968 int dccp_feat_finalise_settings(struct dccp_sock *dp)
970 struct list_head *fn = &dp->dccps_featneg;
971 struct dccp_feat_entry *entry;
972 int i = 2, ccids[2] = { -1, -1 };
976 * 1) not useful to propagate CCID settings if this host advertises more
977 * than one CCID: the choice of CCID may still change - if this is
978 * the client, or if this is the server and the client sends
979 * singleton CCID values.
980 * 2) since is that propagate_ccid changes the list, we defer changing
981 * the sorted list until after the traversal.
983 list_for_each_entry(entry, fn, node)
984 if (entry->feat_num == DCCPF_CCID && entry->val.sp.len == 1)
985 ccids[entry->is_local] = entry->val.sp.vec[0];
987 if (ccids[i] > 0 && dccp_feat_propagate_ccid(fn, ccids[i], i))
989 dccp_feat_print_fnlist(fn);
994 * dccp_feat_server_ccid_dependencies - Resolve CCID-dependent features
995 * It is the server which resolves the dependencies once the CCID has been
996 * fully negotiated. If no CCID has been negotiated, it uses the default CCID.
998 int dccp_feat_server_ccid_dependencies(struct dccp_request_sock *dreq)
1000 struct list_head *fn = &dreq->dreq_featneg;
1001 struct dccp_feat_entry *entry;
1004 for (is_local = 0; is_local <= 1; is_local++) {
1005 entry = dccp_feat_list_lookup(fn, DCCPF_CCID, is_local);
1007 if (entry != NULL && !entry->empty_confirm)
1008 ccid = entry->val.sp.vec[0];
1010 ccid = dccp_feat_default_value(DCCPF_CCID);
1012 if (dccp_feat_propagate_ccid(fn, ccid, is_local))
1018 /* Select the first entry in @servlist that also occurs in @clilist (6.3.1) */
1019 static int dccp_feat_preflist_match(u8 *servlist, u8 slen, u8 *clilist, u8 clen)
1023 for (s = 0; s < slen; s++)
1024 for (c = 0; c < clen; c++)
1025 if (servlist[s] == clilist[c])
1031 * dccp_feat_prefer - Move preferred entry to the start of array
1032 * Reorder the @array_len elements in @array so that @preferred_value comes
1033 * first. Returns >0 to indicate that @preferred_value does occur in @array.
1035 static u8 dccp_feat_prefer(u8 preferred_value, u8 *array, u8 array_len)
1037 u8 i, does_occur = 0;
1039 if (array != NULL) {
1040 for (i = 0; i < array_len; i++)
1041 if (array[i] == preferred_value) {
1042 array[i] = array[0];
1046 array[0] = preferred_value;
1052 * dccp_feat_reconcile - Reconcile SP preference lists
1053 * @fv: SP list to reconcile into
1054 * @arr: received SP preference list
1055 * @len: length of @arr in bytes
1056 * @is_server: whether this side is the server (and @fv is the server's list)
1057 * @reorder: whether to reorder the list in @fv after reconciling with @arr
1058 * When successful, > 0 is returned and the reconciled list is in @fval.
1059 * A value of 0 means that negotiation failed (no shared entry).
1061 static int dccp_feat_reconcile(dccp_feat_val *fv, u8 *arr, u8 len,
1062 bool is_server, bool reorder)
1066 if (!fv->sp.vec || !arr) {
1067 DCCP_CRIT("NULL feature value or array");
1072 rc = dccp_feat_preflist_match(fv->sp.vec, fv->sp.len, arr, len);
1074 rc = dccp_feat_preflist_match(arr, len, fv->sp.vec, fv->sp.len);
1082 * Reorder list: used for activating features and in dccp_insert_fn_opt.
1084 return dccp_feat_prefer(rc, fv->sp.vec, fv->sp.len);
1088 * dccp_feat_change_recv - Process incoming ChangeL/R options
1089 * @fn: feature-negotiation list to update
1090 * @is_mandatory: whether the Change was preceded by a Mandatory option
1091 * @opt: %DCCPO_CHANGE_L or %DCCPO_CHANGE_R
1092 * @feat: one of %dccp_feature_numbers
1093 * @val: NN value or SP value/preference list
1094 * @len: length of @val in bytes
1095 * @server: whether this node is the server (1) or the client (0)
1097 static u8 dccp_feat_change_recv(struct list_head *fn, u8 is_mandatory, u8 opt,
1098 u8 feat, u8 *val, u8 len, const bool server)
1100 u8 defval, type = dccp_feat_type(feat);
1101 const bool local = (opt == DCCPO_CHANGE_R);
1102 struct dccp_feat_entry *entry;
1105 if (len == 0 || type == FEAT_UNKNOWN) /* 6.1 and 6.6.8 */
1106 goto unknown_feature_or_value;
1108 dccp_feat_print_opt(opt, feat, val, len, is_mandatory);
1111 * Negotiation of NN features: Change R is invalid, so there is no
1112 * simultaneous negotiation; hence we do not look up in the list.
1114 if (type == FEAT_NN) {
1115 if (local || len > sizeof(fval.nn))
1116 goto unknown_feature_or_value;
1118 /* 6.3.2: "The feature remote MUST accept any valid value..." */
1119 fval.nn = dccp_decode_value_var(val, len);
1120 if (!dccp_feat_is_valid_nn_val(feat, fval.nn))
1121 goto unknown_feature_or_value;
1123 return dccp_feat_push_confirm(fn, feat, local, &fval);
1127 * Unidirectional/simultaneous negotiation of SP features (6.3.1)
1129 entry = dccp_feat_list_lookup(fn, feat, local);
1130 if (entry == NULL) {
1132 * No particular preferences have been registered. We deal with
1133 * this situation by assuming that all valid values are equally
1134 * acceptable, and apply the following checks:
1135 * - if the peer's list is a singleton, we accept a valid value;
1136 * - if we are the server, we first try to see if the peer (the
1137 * client) advertises the default value. If yes, we use it,
1138 * otherwise we accept the preferred value;
1139 * - else if we are the client, we use the first list element.
1141 if (dccp_feat_clone_sp_val(&fval, val, 1))
1142 return DCCP_RESET_CODE_TOO_BUSY;
1144 if (len > 1 && server) {
1145 defval = dccp_feat_default_value(feat);
1146 if (dccp_feat_preflist_match(&defval, 1, val, len) > -1)
1147 fval.sp.vec[0] = defval;
1148 } else if (!dccp_feat_is_valid_sp_val(feat, fval.sp.vec[0])) {
1150 goto unknown_feature_or_value;
1153 /* Treat unsupported CCIDs like invalid values */
1154 if (feat == DCCPF_CCID && !ccid_support_check(fval.sp.vec, 1)) {
1156 goto not_valid_or_not_known;
1159 return dccp_feat_push_confirm(fn, feat, local, &fval);
1161 } else if (entry->state == FEAT_UNSTABLE) { /* 6.6.2 */
1165 if (dccp_feat_reconcile(&entry->val, val, len, server, true)) {
1166 entry->empty_confirm = false;
1167 } else if (is_mandatory) {
1168 return DCCP_RESET_CODE_MANDATORY_ERROR;
1169 } else if (entry->state == FEAT_INITIALISING) {
1171 * Failed simultaneous negotiation (server only): try to `save'
1172 * the connection by checking whether entry contains the default
1173 * value for @feat. If yes, send an empty Confirm to signal that
1174 * the received Change was not understood - which implies using
1175 * the default value.
1176 * If this also fails, we use Reset as the last resort.
1179 defval = dccp_feat_default_value(feat);
1180 if (!dccp_feat_reconcile(&entry->val, &defval, 1, server, true))
1181 return DCCP_RESET_CODE_OPTION_ERROR;
1182 entry->empty_confirm = true;
1184 entry->needs_confirm = true;
1185 entry->needs_mandatory = false;
1186 entry->state = FEAT_STABLE;
1189 unknown_feature_or_value:
1191 return dccp_push_empty_confirm(fn, feat, local);
1193 not_valid_or_not_known:
1194 return is_mandatory ? DCCP_RESET_CODE_MANDATORY_ERROR
1195 : DCCP_RESET_CODE_OPTION_ERROR;
1199 * dccp_feat_confirm_recv - Process received Confirm options
1200 * @fn: feature-negotiation list to update
1201 * @is_mandatory: whether @opt was preceded by a Mandatory option
1202 * @opt: %DCCPO_CONFIRM_L or %DCCPO_CONFIRM_R
1203 * @feat: one of %dccp_feature_numbers
1204 * @val: NN value or SP value/preference list
1205 * @len: length of @val in bytes
1206 * @server: whether this node is server (1) or client (0)
1208 static u8 dccp_feat_confirm_recv(struct list_head *fn, u8 is_mandatory, u8 opt,
1209 u8 feat, u8 *val, u8 len, const bool server)
1211 u8 *plist, plen, type = dccp_feat_type(feat);
1212 const bool local = (opt == DCCPO_CONFIRM_R);
1213 struct dccp_feat_entry *entry = dccp_feat_list_lookup(fn, feat, local);
1215 dccp_feat_print_opt(opt, feat, val, len, is_mandatory);
1217 if (entry == NULL) { /* nothing queued: ignore or handle error */
1218 if (is_mandatory && type == FEAT_UNKNOWN)
1219 return DCCP_RESET_CODE_MANDATORY_ERROR;
1221 if (!local && type == FEAT_NN) /* 6.3.2 */
1222 goto confirmation_failed;
1226 if (entry->state != FEAT_CHANGING) /* 6.6.2 */
1230 if (dccp_feat_must_be_understood(feat)) /* 6.6.7 */
1231 goto confirmation_failed;
1233 * Empty Confirm during connection setup: this means reverting
1234 * to the `old' value, which in this case is the default. Since
1235 * we handle default values automatically when no other values
1236 * have been set, we revert to the old value by removing this
1237 * entry from the list.
1239 dccp_feat_list_pop(entry);
1243 if (type == FEAT_NN) {
1244 if (len > sizeof(entry->val.nn))
1245 goto confirmation_failed;
1247 if (entry->val.nn == dccp_decode_value_var(val, len))
1248 goto confirmation_succeeded;
1250 DCCP_WARN("Bogus Confirm for non-existing value\n");
1251 goto confirmation_failed;
1255 * Parsing SP Confirms: the first element of @val is the preferred
1256 * SP value which the peer confirms, the remainder depends on @len.
1257 * Note that only the confirmed value need to be a valid SP value.
1259 if (!dccp_feat_is_valid_sp_val(feat, *val))
1260 goto confirmation_failed;
1262 if (len == 1) { /* peer didn't supply a preference list */
1265 } else { /* preferred value + preference list */
1270 /* Check whether the peer got the reconciliation right (6.6.8) */
1271 if (dccp_feat_reconcile(&entry->val, plist, plen, server, 0) != *val) {
1272 DCCP_WARN("Confirm selected the wrong value %u\n", *val);
1273 return DCCP_RESET_CODE_OPTION_ERROR;
1275 entry->val.sp.vec[0] = *val;
1277 confirmation_succeeded:
1278 entry->state = FEAT_STABLE;
1281 confirmation_failed:
1282 DCCP_WARN("Confirmation failed\n");
1283 return is_mandatory ? DCCP_RESET_CODE_MANDATORY_ERROR
1284 : DCCP_RESET_CODE_OPTION_ERROR;
1288 * dccp_feat_handle_nn_established - Fast-path reception of NN options
1289 * @sk: socket of an established DCCP connection
1290 * @mandatory: whether @opt was preceded by a Mandatory option
1291 * @opt: %DCCPO_CHANGE_L | %DCCPO_CONFIRM_R (NN only)
1292 * @feat: NN number, one of %dccp_feature_numbers
1294 * @len: length of @val in bytes
1296 * This function combines the functionality of change_recv/confirm_recv, with
1297 * the following differences (reset codes are the same):
1298 * - cleanup after receiving the Confirm;
1299 * - values are directly activated after successful parsing;
1300 * - deliberately restricted to NN features.
1301 * The restriction to NN features is essential since SP features can have non-
1302 * predictable outcomes (depending on the remote configuration), and are inter-
1303 * dependent (CCIDs for instance cause further dependencies).
1305 static u8 dccp_feat_handle_nn_established(struct sock *sk, u8 mandatory, u8 opt,
1306 u8 feat, u8 *val, u8 len)
1308 struct list_head *fn = &dccp_sk(sk)->dccps_featneg;
1309 const bool local = (opt == DCCPO_CONFIRM_R);
1310 struct dccp_feat_entry *entry;
1311 u8 type = dccp_feat_type(feat);
1314 dccp_feat_print_opt(opt, feat, val, len, mandatory);
1316 /* Ignore non-mandatory unknown and non-NN features */
1317 if (type == FEAT_UNKNOWN) {
1318 if (local && !mandatory)
1320 goto fast_path_unknown;
1321 } else if (type != FEAT_NN) {
1326 * We don't accept empty Confirms, since in fast-path feature
1327 * negotiation the values are enabled immediately after sending
1328 * the Change option.
1329 * Empty Changes on the other hand are invalid (RFC 4340, 6.1).
1331 if (len == 0 || len > sizeof(fval.nn))
1332 goto fast_path_unknown;
1334 if (opt == DCCPO_CHANGE_L) {
1335 fval.nn = dccp_decode_value_var(val, len);
1336 if (!dccp_feat_is_valid_nn_val(feat, fval.nn))
1337 goto fast_path_unknown;
1339 if (dccp_feat_push_confirm(fn, feat, local, &fval) ||
1340 dccp_feat_activate(sk, feat, local, &fval))
1341 return DCCP_RESET_CODE_TOO_BUSY;
1343 /* set the `Ack Pending' flag to piggyback a Confirm */
1344 inet_csk_schedule_ack(sk);
1346 } else if (opt == DCCPO_CONFIRM_R) {
1347 entry = dccp_feat_list_lookup(fn, feat, local);
1348 if (entry == NULL || entry->state != FEAT_CHANGING)
1351 fval.nn = dccp_decode_value_var(val, len);
1353 * Just ignore a value that doesn't match our current value.
1354 * If the option changes twice within two RTTs, then at least
1355 * one CONFIRM will be received for the old value after a
1356 * new CHANGE was sent.
1358 if (fval.nn != entry->val.nn)
1361 /* Only activate after receiving the Confirm option (6.6.1). */
1362 dccp_feat_activate(sk, feat, local, &fval);
1364 /* It has been confirmed - so remove the entry */
1365 dccp_feat_list_pop(entry);
1368 DCCP_WARN("Received illegal option %u\n", opt);
1369 goto fast_path_failed;
1375 return dccp_push_empty_confirm(fn, feat, local);
1378 return mandatory ? DCCP_RESET_CODE_MANDATORY_ERROR
1379 : DCCP_RESET_CODE_OPTION_ERROR;
1383 * dccp_feat_parse_options - Process Feature-Negotiation Options
1384 * @sk: for general use and used by the client during connection setup
1385 * @dreq: used by the server during connection setup
1386 * @mandatory: whether @opt was preceded by a Mandatory option
1387 * @opt: %DCCPO_CHANGE_L | %DCCPO_CHANGE_R | %DCCPO_CONFIRM_L | %DCCPO_CONFIRM_R
1388 * @feat: one of %dccp_feature_numbers
1389 * @val: value contents of @opt
1390 * @len: length of @val in bytes
1392 * Returns 0 on success, a Reset code for ending the connection otherwise.
1394 int dccp_feat_parse_options(struct sock *sk, struct dccp_request_sock *dreq,
1395 u8 mandatory, u8 opt, u8 feat, u8 *val, u8 len)
1397 struct dccp_sock *dp = dccp_sk(sk);
1398 struct list_head *fn = dreq ? &dreq->dreq_featneg : &dp->dccps_featneg;
1399 bool server = false;
1401 switch (sk->sk_state) {
1403 * Negotiation during connection setup
1406 server = true; /* fall through */
1407 case DCCP_REQUESTING:
1409 case DCCPO_CHANGE_L:
1410 case DCCPO_CHANGE_R:
1411 return dccp_feat_change_recv(fn, mandatory, opt, feat,
1413 case DCCPO_CONFIRM_R:
1414 case DCCPO_CONFIRM_L:
1415 return dccp_feat_confirm_recv(fn, mandatory, opt, feat,
1420 * Support for exchanging NN options on an established connection.
1424 return dccp_feat_handle_nn_established(sk, mandatory, opt, feat,
1427 return 0; /* ignore FN options in all other states */
1431 * dccp_feat_init - Seed feature negotiation with host-specific defaults
1432 * This initialises global defaults, depending on the value of the sysctls.
1433 * These can later be overridden by registering changes via setsockopt calls.
1434 * The last link in the chain is finalise_settings, to make sure that between
1435 * here and the start of actual feature negotiation no inconsistencies enter.
1437 * All features not appearing below use either defaults or are otherwise
1438 * later adjusted through dccp_feat_finalise_settings().
1440 int dccp_feat_init(struct sock *sk)
1442 struct list_head *fn = &dccp_sk(sk)->dccps_featneg;
1450 /* Non-negotiable (NN) features */
1451 rc = __feat_register_nn(fn, DCCPF_SEQUENCE_WINDOW, 0,
1452 sysctl_dccp_sequence_window);
1456 /* Server-priority (SP) features */
1458 /* Advertise that short seqnos are not supported (7.6.1) */
1459 rc = __feat_register_sp(fn, DCCPF_SHORT_SEQNOS, true, true, &off, 1);
1463 /* RFC 4340 12.1: "If a DCCP is not ECN capable, ..." */
1464 rc = __feat_register_sp(fn, DCCPF_ECN_INCAPABLE, true, true, &on, 1);
1469 * We advertise the available list of CCIDs and reorder according to
1470 * preferences, to avoid failure resulting from negotiating different
1471 * singleton values (which always leads to failure).
1472 * These settings can still (later) be overridden via sockopts.
1474 if (ccid_get_builtin_ccids(&tx.val, &tx.len) ||
1475 ccid_get_builtin_ccids(&rx.val, &rx.len))
1478 if (!dccp_feat_prefer(sysctl_dccp_tx_ccid, tx.val, tx.len) ||
1479 !dccp_feat_prefer(sysctl_dccp_rx_ccid, rx.val, rx.len))
1480 goto free_ccid_lists;
1482 rc = __feat_register_sp(fn, DCCPF_CCID, true, false, tx.val, tx.len);
1484 goto free_ccid_lists;
1486 rc = __feat_register_sp(fn, DCCPF_CCID, false, false, rx.val, rx.len);
1494 int dccp_feat_activate_values(struct sock *sk, struct list_head *fn_list)
1496 struct dccp_sock *dp = dccp_sk(sk);
1497 struct dccp_feat_entry *cur, *next;
1499 dccp_feat_val *fvals[DCCP_FEAT_SUPPORTED_MAX][2] = {
1500 [0 ... DCCP_FEAT_SUPPORTED_MAX-1] = { NULL, NULL }
1503 list_for_each_entry(cur, fn_list, node) {
1505 * An empty Confirm means that either an unknown feature type
1506 * or an invalid value was present. In the first case there is
1507 * nothing to activate, in the other the default value is used.
1509 if (cur->empty_confirm)
1512 idx = dccp_feat_index(cur->feat_num);
1514 DCCP_BUG("Unknown feature %u", cur->feat_num);
1515 goto activation_failed;
1517 if (cur->state != FEAT_STABLE) {
1518 DCCP_CRIT("Negotiation of %s %s failed in state %s",
1519 cur->is_local ? "local" : "remote",
1520 dccp_feat_fname(cur->feat_num),
1521 dccp_feat_sname[cur->state]);
1522 goto activation_failed;
1524 fvals[idx][cur->is_local] = &cur->val;
1528 * Activate in decreasing order of index, so that the CCIDs are always
1529 * activated as the last feature. This avoids the case where a CCID
1530 * relies on the initialisation of one or more features that it depends
1531 * on (e.g. Send NDP Count, Send Ack Vector, and Ack Ratio features).
1533 for (idx = DCCP_FEAT_SUPPORTED_MAX; --idx >= 0;)
1534 if (__dccp_feat_activate(sk, idx, 0, fvals[idx][0]) ||
1535 __dccp_feat_activate(sk, idx, 1, fvals[idx][1])) {
1536 DCCP_CRIT("Could not activate %d", idx);
1537 goto activation_failed;
1540 /* Clean up Change options which have been confirmed already */
1541 list_for_each_entry_safe(cur, next, fn_list, node)
1542 if (!cur->needs_confirm)
1543 dccp_feat_list_pop(cur);
1545 dccp_pr_debug("Activation OK\n");
1550 * We clean up everything that may have been allocated, since
1551 * it is difficult to track at which stage negotiation failed.
1552 * This is ok, since all allocation functions below are robust
1553 * against NULL arguments.
1555 ccid_hc_rx_delete(dp->dccps_hc_rx_ccid, sk);
1556 ccid_hc_tx_delete(dp->dccps_hc_tx_ccid, sk);
1557 dp->dccps_hc_rx_ccid = dp->dccps_hc_tx_ccid = NULL;
1558 dccp_ackvec_free(dp->dccps_hc_rx_ackvec);
1559 dp->dccps_hc_rx_ackvec = NULL;