net/dccp/feat.c

   1 /*
   2  *  net/dccp/feat.c
   3  *
   4  *  An implementation of the DCCP protocol
   5  *  Andrea Bittau <a.bittau@cs.ucl.ac.uk>
   6  *
   7  *  ASSUMPTIONS
   8  *  -----------
   9  *  o Feature negotiation is coordinated with connection setup (as in TCP), wild
  10  *    changes of parameters of an established connection are not supported.
  11  *  o All currently known SP features have 1-byte quantities. If in the future
  12  *    extensions of RFCs 4340..42 define features with item lengths larger than
  13  *    one byte, a feature-specific extension of the code will be required.
  14  *
  15  *  This program is free software; you can redistribute it and/or
  16  *  modify it under the terms of the GNU General Public License
  17  *  as published by the Free Software Foundation; either version
  18  *  2 of the License, or (at your option) any later version.
  19  */
  20
  21 #include <linux/module.h>
  22
  23 #include "ccid.h"
  24 #include "feat.h"
  25
  26 #define DCCP_FEAT_SP_NOAGREE (-123)
  27
  28 static const struct {
  29         u8                      feat_num;               /* DCCPF_xxx */
  30         enum dccp_feat_type     rxtx;                   /* RX or TX  */
  31         enum dccp_feat_type     reconciliation;         /* SP or NN  */
  32         u8                      default_value;          /* as in 6.4 */
  33 /*
  34  *    Lookup table for location and type of features (from RFC 4340/4342)
  35  *  +--------------------------+----+-----+----+----+---------+-----------+
  36  *  | Feature                  | Location | Reconc. | Initial |  Section  |
  37  *  |                          | RX | TX  | SP | NN |  Value  | Reference |
  38  *  +--------------------------+----+-----+----+----+---------+-----------+
  39  *  | DCCPF_CCID               |    |  X  | X  |    |   2     | 10        |
  40  *  | DCCPF_SHORT_SEQNOS       |    |  X  | X  |    |   0     |  7.6.1    |
  41  *  | DCCPF_SEQUENCE_WINDOW    |    |  X  |    | X  | 100     |  7.5.2    |
  42  *  | DCCPF_ECN_INCAPABLE      | X  |     | X  |    |   0     | 12.1      |
  43  *  | DCCPF_ACK_RATIO          |    |  X  |    | X  |   2     | 11.3      |
  44  *  | DCCPF_SEND_ACK_VECTOR    | X  |     | X  |    |   0     | 11.5      |
  45  *  | DCCPF_SEND_NDP_COUNT     |    |  X  | X  |    |   0     |  7.7.2    |
  46  *  | DCCPF_MIN_CSUM_COVER     | X  |     | X  |    |   0     |  9.2.1    |
  47  *  | DCCPF_DATA_CHECKSUM      | X  |     | X  |    |   0     |  9.3.1    |
  48  *  | DCCPF_SEND_LEV_RATE      | X  |     | X  |    |   0     | 4342/8.4  |
  49  *  +--------------------------+----+-----+----+----+---------+-----------+
  50  */
  51 } dccp_feat_table[] = {
  52         { DCCPF_CCID,            FEAT_AT_TX, FEAT_SP, 2 },
  53         { DCCPF_SHORT_SEQNOS,    FEAT_AT_TX, FEAT_SP, 0 },
  54         { DCCPF_SEQUENCE_WINDOW, FEAT_AT_TX, FEAT_NN, 100 },
  55         { DCCPF_ECN_INCAPABLE,   FEAT_AT_RX, FEAT_SP, 0 },
  56         { DCCPF_ACK_RATIO,       FEAT_AT_TX, FEAT_NN, 2 },
  57         { DCCPF_SEND_ACK_VECTOR, FEAT_AT_RX, FEAT_SP, 0 },
  58         { DCCPF_SEND_NDP_COUNT,  FEAT_AT_TX, FEAT_SP, 0 },
  59         { DCCPF_MIN_CSUM_COVER,  FEAT_AT_RX, FEAT_SP, 0 },
  60         { DCCPF_DATA_CHECKSUM,   FEAT_AT_RX, FEAT_SP, 0 },
  61         { DCCPF_SEND_LEV_RATE,   FEAT_AT_RX, FEAT_SP, 0 },
  62 };
  63 #define DCCP_FEAT_SUPPORTED_MAX         ARRAY_SIZE(dccp_feat_table)
  64
  65 /**
  66  * dccp_feat_index  -  Hash function to map feature number into array position
  67  * Returns consecutive array index or -1 if the feature is not understood.
  68  */
  69 static int dccp_feat_index(u8 feat_num)
  70 {
  71         /* The first 9 entries are occupied by the types from RFC 4340, 6.4 */
  72         if (feat_num > DCCPF_RESERVED && feat_num <= DCCPF_DATA_CHECKSUM)
  73                 return feat_num - 1;
  74
  75         /*
  76          * Other features: add cases for new feature types here after adding
  77          * them to the above table.
  78          */
  79         switch (feat_num) {
  80         case DCCPF_SEND_LEV_RATE:
  81                         return DCCP_FEAT_SUPPORTED_MAX - 1;
  82         }
  83         return -1;
  84 }
  85
  86 static u8 dccp_feat_type(u8 feat_num)
  87 {
  88         int idx = dccp_feat_index(feat_num);
  89
  90         if (idx < 0)
  91                 return FEAT_UNKNOWN;
  92         return dccp_feat_table[idx].reconciliation;
  93 }
  94
  95 static int dccp_feat_default_value(u8 feat_num)
  96 {
  97         int idx = dccp_feat_index(feat_num);
  98
  99         return idx < 0 ? : dccp_feat_table[idx].default_value;
 100 }
 101
 102 /* copy constructor, fval must not already contain allocated memory */
 103 static int dccp_feat_clone_sp_val(dccp_feat_val *fval, u8 const *val, u8 len)
 104 {
 105         fval->sp.len = len;
 106         if (fval->sp.len > 0) {
 107                 fval->sp.vec = kmemdup(val, len, gfp_any());
 108                 if (fval->sp.vec == NULL) {
 109                         fval->sp.len = 0;
 110                         return -ENOBUFS;
 111                 }
 112         }
 113         return 0;
 114 }
 115
 116 static void dccp_feat_val_destructor(u8 feat_num, dccp_feat_val *val)
 117 {
 118         if (unlikely(val == NULL))
 119                 return;
 120         if (dccp_feat_type(feat_num) == FEAT_SP)
 121                 kfree(val->sp.vec);
 122         memset(val, 0, sizeof(*val));
 123 }
 124
 125 static struct dccp_feat_entry *
 126               dccp_feat_clone_entry(struct dccp_feat_entry const *original)
 127 {
 128         struct dccp_feat_entry *new;
 129         u8 type = dccp_feat_type(original->feat_num);
 130
 131         if (type == FEAT_UNKNOWN)
 132                 return NULL;
 133
 134         new = kmemdup(original, sizeof(struct dccp_feat_entry), gfp_any());
 135         if (new == NULL)
 136                 return NULL;
 137
 138         if (type == FEAT_SP && dccp_feat_clone_sp_val(&new->val,
 139                                                       original->val.sp.vec,
 140                                                       original->val.sp.len)) {
 141                 kfree(new);
 142                 return NULL;
 143         }
 144         return new;
 145 }
 146
 147 static void dccp_feat_entry_destructor(struct dccp_feat_entry *entry)
 148 {
 149         if (entry != NULL) {
 150                 dccp_feat_val_destructor(entry->feat_num, &entry->val);
 151                 kfree(entry);
 152         }
 153 }
 154
 155 /*
 156  * List management functions
 157  *
 158  * Feature negotiation lists rely on and maintain the following invariants:
 159  * - each feat_num in the list is known, i.e. we know its type and default value
 160  * - each feat_num/is_local combination is unique (old entries are overwritten)
 161  * - SP values are always freshly allocated
 162  * - list is sorted in increasing order of feature number (faster lookup)
 163  */
 164 static struct dccp_feat_entry *dccp_feat_list_lookup(struct list_head *fn_list,
 165                                                      u8 feat_num, bool is_local)
 166 {
 167         struct dccp_feat_entry *entry;
 168
 169         list_for_each_entry(entry, fn_list, node)
 170                 if (entry->feat_num == feat_num && entry->is_local == is_local)
 171                         return entry;
 172                 else if (entry->feat_num > feat_num)
 173                         break;
 174         return NULL;
 175 }
 176
 177 /**
 178  * dccp_feat_entry_new  -  Central list update routine (called by all others)
 179  * @head:  list to add to
 180  * @feat:  feature number
 181  * @local: whether the local (1) or remote feature with number @feat is meant
 182  * This is the only constructor and serves to ensure the above invariants.
 183  */
 184 static struct dccp_feat_entry *
 185               dccp_feat_entry_new(struct list_head *head, u8 feat, bool local)
 186 {
 187         struct dccp_feat_entry *entry;
 188
 189         list_for_each_entry(entry, head, node)
 190                 if (entry->feat_num == feat && entry->is_local == local) {
 191                         dccp_feat_val_destructor(entry->feat_num, &entry->val);
 192                         return entry;
 193                 } else if (entry->feat_num > feat) {
 194                         head = &entry->node;
 195                         break;
 196                 }
 197
 198         entry = kmalloc(sizeof(*entry), gfp_any());
 199         if (entry != NULL) {
 200                 entry->feat_num = feat;
 201                 entry->is_local = local;
 202                 list_add_tail(&entry->node, head);
 203         }
 204         return entry;
 205 }
 206
 207 /**
 208  * dccp_feat_push_change  -  Add/overwrite a Change option in the list
 209  * @fn_list: feature-negotiation list to update
 210  * @feat: one of %dccp_feature_numbers
 211  * @local: whether local (1) or remote (0) @feat_num is meant
 212  * @needs_mandatory: whether to use Mandatory feature negotiation options
 213  * @fval: pointer to NN/SP value to be inserted (will be copied)
 214  */
 215 static int dccp_feat_push_change(struct list_head *fn_list, u8 feat, u8 local,
 216                                  u8 mandatory, dccp_feat_val *fval)
 217 {
 218         struct dccp_feat_entry *new = dccp_feat_entry_new(fn_list, feat, local);
 219
 220         if (new == NULL)
 221                 return -ENOMEM;
 222
 223         new->feat_num        = feat;
 224         new->is_local        = local;
 225         new->state           = FEAT_INITIALISING;
 226         new->needs_confirm   = 0;
 227         new->empty_confirm   = 0;
 228         new->val             = *fval;
 229         new->needs_mandatory = mandatory;
 230
 231         return 0;
 232 }
 233
 234 /**
 235  * dccp_feat_push_confirm  -  Add a Confirm entry to the FN list
 236  * @fn_list: feature-negotiation list to add to
 237  * @feat: one of %dccp_feature_numbers
 238  * @local: whether local (1) or remote (0) @feat_num is being confirmed
 239  * @fval: pointer to NN/SP value to be inserted or NULL
 240  * Returns 0 on success, a Reset code for further processing otherwise.
 241  */
 242 static int dccp_feat_push_confirm(struct list_head *fn_list, u8 feat, u8 local,
 243                                   dccp_feat_val *fval)
 244 {
 245         struct dccp_feat_entry *new = dccp_feat_entry_new(fn_list, feat, local);
 246
 247         if (new == NULL)
 248                 return DCCP_RESET_CODE_TOO_BUSY;
 249
 250         new->feat_num        = feat;
 251         new->is_local        = local;
 252         new->state           = FEAT_STABLE;     /* transition in 6.6.2 */
 253         new->needs_confirm   = 1;
 254         new->empty_confirm   = (fval == NULL);
 255         new->val.nn          = 0;               /* zeroes the whole structure */
 256         if (!new->empty_confirm)
 257                 new->val     = *fval;
 258         new->needs_mandatory = 0;
 259
 260         return 0;
 261 }
 262
 263 static int dccp_push_empty_confirm(struct list_head *fn_list, u8 feat, u8 local)
 264 {
 265         return dccp_feat_push_confirm(fn_list, feat, local, NULL);
 266 }
 267
 268 static inline void dccp_feat_list_pop(struct dccp_feat_entry *entry)
 269 {
 270         list_del(&entry->node);
 271         dccp_feat_entry_destructor(entry);
 272 }
 273
 274 void dccp_feat_list_purge(struct list_head *fn_list)
 275 {
 276         struct dccp_feat_entry *entry, *next;
 277
 278         list_for_each_entry_safe(entry, next, fn_list, node)
 279                 dccp_feat_entry_destructor(entry);
 280         INIT_LIST_HEAD(fn_list);
 281 }
 282 EXPORT_SYMBOL_GPL(dccp_feat_list_purge);
 283
 284 /* generate @to as full clone of @from - @to must not contain any nodes */
 285 int dccp_feat_clone_list(struct list_head const *from, struct list_head *to)
 286 {
 287         struct dccp_feat_entry *entry, *new;
 288
 289         INIT_LIST_HEAD(to);
 290         list_for_each_entry(entry, from, node) {
 291                 new = dccp_feat_clone_entry(entry);
 292                 if (new == NULL)
 293                         goto cloning_failed;
 294                 list_add_tail(&new->node, to);
 295         }
 296         return 0;
 297
 298 cloning_failed:
 299         dccp_feat_list_purge(to);
 300         return -ENOMEM;
 301 }
 302
 303 static u8 dccp_feat_is_valid_nn_val(u8 feat_num, u64 val)
 304 {
 305         switch (feat_num) {
 306         case DCCPF_ACK_RATIO:
 307                 return val <= DCCPF_ACK_RATIO_MAX;
 308         case DCCPF_SEQUENCE_WINDOW:
 309                 return val >= DCCPF_SEQ_WMIN && val <= DCCPF_SEQ_WMAX;
 310         }
 311         return 0;       /* feature unknown - so we can't tell */
 312 }
 313
 314 /* check that SP values are within the ranges defined in RFC 4340 */
 315 static u8 dccp_feat_is_valid_sp_val(u8 feat_num, u8 val)
 316 {
 317         switch (feat_num) {
 318         case DCCPF_CCID:
 319                 return val == DCCPC_CCID2 || val == DCCPC_CCID3;
 320         /* Type-check Boolean feature values: */
 321         case DCCPF_SHORT_SEQNOS:
 322         case DCCPF_ECN_INCAPABLE:
 323         case DCCPF_SEND_ACK_VECTOR:
 324         case DCCPF_SEND_NDP_COUNT:
 325         case DCCPF_DATA_CHECKSUM:
 326         case DCCPF_SEND_LEV_RATE:
 327                 return val < 2;
 328         case DCCPF_MIN_CSUM_COVER:
 329                 return val < 16;
 330         }
 331         return 0;                       /* feature unknown */
 332 }
 333
 334 static u8 dccp_feat_sp_list_ok(u8 feat_num, u8 const *sp_list, u8 sp_len)
 335 {
 336         if (sp_list == NULL || sp_len < 1)
 337                 return 0;
 338         while (sp_len--)
 339                 if (!dccp_feat_is_valid_sp_val(feat_num, *sp_list++))
 340                         return 0;
 341         return 1;
 342 }
 343
 344 /**
 345  * __feat_register_nn  -  Register new NN value on socket
 346  * @fn: feature-negotiation list to register with
 347  * @feat: an NN feature from %dccp_feature_numbers
 348  * @mandatory: use Mandatory option if 1
 349  * @nn_val: value to register (restricted to 4 bytes)
 350  * Note that NN features are local by definition (RFC 4340, 6.3.2).
 351  */
 352 static int __feat_register_nn(struct list_head *fn, u8 feat,
 353                               u8 mandatory, u64 nn_val)
 354 {
 355         dccp_feat_val fval = { .nn = nn_val };
 356
 357         if (dccp_feat_type(feat) != FEAT_NN ||
 358             !dccp_feat_is_valid_nn_val(feat, nn_val))
 359                 return -EINVAL;
 360
 361         /* Don't bother with default values, they will be activated anyway. */
 362         if (nn_val - (u64)dccp_feat_default_value(feat) == 0)
 363                 return 0;
 364
 365         return dccp_feat_push_change(fn, feat, 1, mandatory, &fval);
 366 }
 367
 368 /**
 369  * __feat_register_sp  -  Register new SP value/list on socket
 370  * @fn: feature-negotiation list to register with
 371  * @feat: an SP feature from %dccp_feature_numbers
 372  * @is_local: whether the local (1) or the remote (0) @feat is meant
 373  * @mandatory: use Mandatory option if 1
 374  * @sp_val: SP value followed by optional preference list
 375  * @sp_len: length of @sp_val in bytes
 376  */
 377 static int __feat_register_sp(struct list_head *fn, u8 feat, u8 is_local,
 378                               u8 mandatory, u8 const *sp_val, u8 sp_len)
 379 {
 380         dccp_feat_val fval;
 381
 382         if (dccp_feat_type(feat) != FEAT_SP ||
 383             !dccp_feat_sp_list_ok(feat, sp_val, sp_len))
 384                 return -EINVAL;
 385
 386         if (dccp_feat_clone_sp_val(&fval, sp_val, sp_len))
 387                 return -ENOMEM;
 388
 389         return dccp_feat_push_change(fn, feat, is_local, mandatory, &fval);
 390 }
 391
 392 int dccp_feat_change(struct dccp_minisock *dmsk, u8 type, u8 feature,
 393                      u8 *val, u8 len, gfp_t gfp)
 394 {
 395         struct dccp_opt_pend *opt;
 396
 397         dccp_feat_debug(type, feature, *val);
 398
 399         if (len > 3) {
 400                 DCCP_WARN("invalid length %d\n", len);
 401                 return -EINVAL;
 402         }
 403         /* XXX add further sanity checks */
 404
 405         /* check if that feature is already being negotiated */
 406         list_for_each_entry(opt, &dmsk->dccpms_pending, dccpop_node) {
 407                 /* ok we found a negotiation for this option already */
 408                 if (opt->dccpop_feat == feature && opt->dccpop_type == type) {
 409                         dccp_pr_debug("Replacing old\n");
 410                         /* replace */
 411                         BUG_ON(opt->dccpop_val == NULL);
 412                         kfree(opt->dccpop_val);
 413                         opt->dccpop_val  = val;
 414                         opt->dccpop_len  = len;
 415                         opt->dccpop_conf = 0;
 416                         return 0;
 417                 }
 418         }
 419
 420         /* negotiation for a new feature */
 421         opt = kmalloc(sizeof(*opt), gfp);
 422         if (opt == NULL)
 423                 return -ENOMEM;
 424
 425         opt->dccpop_type = type;
 426         opt->dccpop_feat = feature;
 427         opt->dccpop_len  = len;
 428         opt->dccpop_val  = val;
 429         opt->dccpop_conf = 0;
 430         opt->dccpop_sc   = NULL;
 431
 432         BUG_ON(opt->dccpop_val == NULL);
 433
 434         list_add_tail(&opt->dccpop_node, &dmsk->dccpms_pending);
 435         return 0;
 436 }
 437
 438 EXPORT_SYMBOL_GPL(dccp_feat_change);
 439
 440 static int dccp_feat_update_ccid(struct sock *sk, u8 type, u8 new_ccid_nr)
 441 {
 442         struct dccp_sock *dp = dccp_sk(sk);
 443         struct dccp_minisock *dmsk = dccp_msk(sk);
 444         /* figure out if we are changing our CCID or the peer's */
 445         const int rx = type == DCCPO_CHANGE_R;
 446         const u8 ccid_nr = rx ? dmsk->dccpms_rx_ccid : dmsk->dccpms_tx_ccid;
 447         struct ccid *new_ccid;
 448
 449         /* Check if nothing is being changed. */
 450         if (ccid_nr == new_ccid_nr)
 451                 return 0;
 452
 453         new_ccid = ccid_new(new_ccid_nr, sk, rx, GFP_ATOMIC);
 454         if (new_ccid == NULL)
 455                 return -ENOMEM;
 456
 457         if (rx) {
 458                 ccid_hc_rx_delete(dp->dccps_hc_rx_ccid, sk);
 459                 dp->dccps_hc_rx_ccid = new_ccid;
 460                 dmsk->dccpms_rx_ccid = new_ccid_nr;
 461         } else {
 462                 ccid_hc_tx_delete(dp->dccps_hc_tx_ccid, sk);
 463                 dp->dccps_hc_tx_ccid = new_ccid;
 464                 dmsk->dccpms_tx_ccid = new_ccid_nr;
 465         }
 466
 467         return 0;
 468 }
 469
 470 static int dccp_feat_update(struct sock *sk, u8 type, u8 feat, u8 val)
 471 {
 472         dccp_feat_debug(type, feat, val);
 473
 474         switch (feat) {
 475         case DCCPF_CCID:
 476                 return dccp_feat_update_ccid(sk, type, val);
 477         default:
 478                 dccp_pr_debug("UNIMPLEMENTED: %s(%d, ...)\n",
 479                               dccp_feat_typename(type), feat);
 480                 break;
 481         }
 482         return 0;
 483 }
 484
 485 static int dccp_feat_reconcile(struct sock *sk, struct dccp_opt_pend *opt,
 486                                u8 *rpref, u8 rlen)
 487 {
 488         struct dccp_sock *dp = dccp_sk(sk);
 489         u8 *spref, slen, *res = NULL;
 490         int i, j, rc, agree = 1;
 491
 492         BUG_ON(rpref == NULL);
 493
 494         /* check if we are the black sheep */
 495         if (dp->dccps_role == DCCP_ROLE_CLIENT) {
 496                 spref = rpref;
 497                 slen  = rlen;
 498                 rpref = opt->dccpop_val;
 499                 rlen  = opt->dccpop_len;
 500         } else {
 501                 spref = opt->dccpop_val;
 502                 slen  = opt->dccpop_len;
 503         }
 504         /*
 505          * Now we have server preference list in spref and client preference in
 506          * rpref
 507          */
 508         BUG_ON(spref == NULL);
 509         BUG_ON(rpref == NULL);
 510
 511         /* FIXME sanity check vals */
 512
 513         /* Are values in any order?  XXX Lame "algorithm" here */
 514         for (i = 0; i < slen; i++) {
 515                 for (j = 0; j < rlen; j++) {
 516                         if (spref[i] == rpref[j]) {
 517                                 res = &spref[i];
 518                                 break;
 519                         }
 520                 }
 521                 if (res)
 522                         break;
 523         }
 524
 525         /* we didn't agree on anything */
 526         if (res == NULL) {
 527                 /* confirm previous value */
 528                 switch (opt->dccpop_feat) {
 529                 case DCCPF_CCID:
 530                         /* XXX did i get this right? =P */
 531                         if (opt->dccpop_type == DCCPO_CHANGE_L)
 532                                 res = &dccp_msk(sk)->dccpms_tx_ccid;
 533                         else
 534                                 res = &dccp_msk(sk)->dccpms_rx_ccid;
 535                         break;
 536
 537                 default:
 538                         DCCP_BUG("Fell through, feat=%d", opt->dccpop_feat);
 539                         /* XXX implement res */
 540                         return -EFAULT;
 541                 }
 542
 543                 dccp_pr_debug("Don't agree... reconfirming %d\n", *res);
 544                 agree = 0; /* this is used for mandatory options... */
 545         }
 546
 547         /* need to put result and our preference list */
 548         rlen = 1 + opt->dccpop_len;
 549         rpref = kmalloc(rlen, GFP_ATOMIC);
 550         if (rpref == NULL)
 551                 return -ENOMEM;
 552
 553         *rpref = *res;
 554         memcpy(&rpref[1], opt->dccpop_val, opt->dccpop_len);
 555
 556         /* put it in the "confirm queue" */
 557         if (opt->dccpop_sc == NULL) {
 558                 opt->dccpop_sc = kmalloc(sizeof(*opt->dccpop_sc), GFP_ATOMIC);
 559                 if (opt->dccpop_sc == NULL) {
 560                         kfree(rpref);
 561                         return -ENOMEM;
 562                 }
 563         } else {
 564                 /* recycle the confirm slot */
 565                 BUG_ON(opt->dccpop_sc->dccpoc_val == NULL);
 566                 kfree(opt->dccpop_sc->dccpoc_val);
 567                 dccp_pr_debug("recycling confirm slot\n");
 568         }
 569         memset(opt->dccpop_sc, 0, sizeof(*opt->dccpop_sc));
 570
 571         opt->dccpop_sc->dccpoc_val = rpref;
 572         opt->dccpop_sc->dccpoc_len = rlen;
 573
 574         /* update the option on our side [we are about to send the confirm] */
 575         rc = dccp_feat_update(sk, opt->dccpop_type, opt->dccpop_feat, *res);
 576         if (rc) {
 577                 kfree(opt->dccpop_sc->dccpoc_val);
 578                 kfree(opt->dccpop_sc);
 579                 opt->dccpop_sc = NULL;
 580                 return rc;
 581         }
 582
 583         dccp_pr_debug("Will confirm %d\n", *rpref);
 584
 585         /* say we want to change to X but we just got a confirm X, suppress our
 586          * change
 587          */
 588         if (!opt->dccpop_conf) {
 589                 if (*opt->dccpop_val == *res)
 590                         opt->dccpop_conf = 1;
 591                 dccp_pr_debug("won't ask for change of same feature\n");
 592         }
 593
 594         return agree ? 0 : DCCP_FEAT_SP_NOAGREE; /* used for mandatory opts */
 595 }
 596
 597 static int dccp_feat_sp(struct sock *sk, u8 type, u8 feature, u8 *val, u8 len)
 598 {
 599         struct dccp_minisock *dmsk = dccp_msk(sk);
 600         struct dccp_opt_pend *opt;
 601         int rc = 1;
 602         u8 t;
 603
 604         /*
 605          * We received a CHANGE.  We gotta match it against our own preference
 606          * list.  If we got a CHANGE_R it means it's a change for us, so we need
 607          * to compare our CHANGE_L list.
 608          */
 609         if (type == DCCPO_CHANGE_L)
 610                 t = DCCPO_CHANGE_R;
 611         else
 612                 t = DCCPO_CHANGE_L;
 613
 614         /* find our preference list for this feature */
 615         list_for_each_entry(opt, &dmsk->dccpms_pending, dccpop_node) {
 616                 if (opt->dccpop_type != t || opt->dccpop_feat != feature)
 617                         continue;
 618
 619                 /* find the winner from the two preference lists */
 620                 rc = dccp_feat_reconcile(sk, opt, val, len);
 621                 break;
 622         }
 623
 624         /* We didn't deal with the change.  This can happen if we have no
 625          * preference list for the feature.  In fact, it just shouldn't
 626          * happen---if we understand a feature, we should have a preference list
 627          * with at least the default value.
 628          */
 629         BUG_ON(rc == 1);
 630
 631         return rc;
 632 }
 633
 634 static int dccp_feat_nn(struct sock *sk, u8 type, u8 feature, u8 *val, u8 len)
 635 {
 636         struct dccp_opt_pend *opt;
 637         struct dccp_minisock *dmsk = dccp_msk(sk);
 638         u8 *copy;
 639         int rc;
 640
 641         /* NN features must be Change L (sec. 6.3.2) */
 642         if (type != DCCPO_CHANGE_L) {
 643                 dccp_pr_debug("received %s for NN feature %d\n",
 644                                 dccp_feat_typename(type), feature);
 645                 return -EFAULT;
 646         }
 647
 648         /* XXX sanity check opt val */
 649
 650         /* copy option so we can confirm it */
 651         opt = kzalloc(sizeof(*opt), GFP_ATOMIC);
 652         if (opt == NULL)
 653                 return -ENOMEM;
 654
 655         copy = kmemdup(val, len, GFP_ATOMIC);
 656         if (copy == NULL) {
 657                 kfree(opt);
 658                 return -ENOMEM;
 659         }
 660
 661         opt->dccpop_type = DCCPO_CONFIRM_R; /* NN can only confirm R */
 662         opt->dccpop_feat = feature;
 663         opt->dccpop_val  = copy;
 664         opt->dccpop_len  = len;
 665
 666         /* change feature */
 667         rc = dccp_feat_update(sk, type, feature, *val);
 668         if (rc) {
 669                 kfree(opt->dccpop_val);
 670                 kfree(opt);
 671                 return rc;
 672         }
 673
 674         dccp_feat_debug(type, feature, *copy);
 675
 676         list_add_tail(&opt->dccpop_node, &dmsk->dccpms_conf);
 677
 678         return 0;
 679 }
 680
 681 static void dccp_feat_empty_confirm(struct dccp_minisock *dmsk,
 682                                     u8 type, u8 feature)
 683 {
 684         /* XXX check if other confirms for that are queued and recycle slot */
 685         struct dccp_opt_pend *opt = kzalloc(sizeof(*opt), GFP_ATOMIC);
 686
 687         if (opt == NULL) {
 688                 /* XXX what do we do?  Ignoring should be fine.  It's a change
 689                  * after all =P
 690                  */
 691                 return;
 692         }
 693
 694         switch (type) {
 695         case DCCPO_CHANGE_L:
 696                 opt->dccpop_type = DCCPO_CONFIRM_R;
 697                 break;
 698         case DCCPO_CHANGE_R:
 699                 opt->dccpop_type = DCCPO_CONFIRM_L;
 700                 break;
 701         default:
 702                 DCCP_WARN("invalid type %d\n", type);
 703                 kfree(opt);
 704                 return;
 705         }
 706         opt->dccpop_feat = feature;
 707         opt->dccpop_val  = NULL;
 708         opt->dccpop_len  = 0;
 709
 710         /* change feature */
 711         dccp_pr_debug("Empty %s(%d)\n", dccp_feat_typename(type), feature);
 712
 713         list_add_tail(&opt->dccpop_node, &dmsk->dccpms_conf);
 714 }
 715
 716 static void dccp_feat_flush_confirm(struct sock *sk)
 717 {
 718         struct dccp_minisock *dmsk = dccp_msk(sk);
 719         /* Check if there is anything to confirm in the first place */
 720         int yes = !list_empty(&dmsk->dccpms_conf);
 721
 722         if (!yes) {
 723                 struct dccp_opt_pend *opt;
 724
 725                 list_for_each_entry(opt, &dmsk->dccpms_pending, dccpop_node) {
 726                         if (opt->dccpop_conf) {
 727                                 yes = 1;
 728                                 break;
 729                         }
 730                 }
 731         }
 732
 733         if (!yes)
 734                 return;
 735
 736         /* OK there is something to confirm... */
 737         /* XXX check if packet is in flight?  Send delayed ack?? */
 738         if (sk->sk_state == DCCP_OPEN)
 739                 dccp_send_ack(sk);
 740 }
 741
 742 int dccp_feat_change_recv(struct sock *sk, u8 type, u8 feature, u8 *val, u8 len)
 743 {
 744         int rc;
 745
 746         /* Ignore Change requests other than during connection setup */
 747         if (sk->sk_state != DCCP_LISTEN && sk->sk_state != DCCP_REQUESTING)
 748                 return 0;
 749         dccp_feat_debug(type, feature, *val);
 750
 751         /* figure out if it's SP or NN feature */
 752         switch (feature) {
 753         /* deal with SP features */
 754         case DCCPF_CCID:
 755                 rc = dccp_feat_sp(sk, type, feature, val, len);
 756                 break;
 757
 758         /* deal with NN features */
 759         case DCCPF_ACK_RATIO:
 760                 rc = dccp_feat_nn(sk, type, feature, val, len);
 761                 break;
 762
 763         /* XXX implement other features */
 764         default:
 765                 dccp_pr_debug("UNIMPLEMENTED: not handling %s(%d, ...)\n",
 766                               dccp_feat_typename(type), feature);
 767                 rc = -EFAULT;
 768                 break;
 769         }
 770
 771         /* check if there were problems changing features */
 772         if (rc) {
 773                 /* If we don't agree on SP, we sent a confirm for old value.
 774                  * However we propagate rc to caller in case option was
 775                  * mandatory
 776                  */
 777                 if (rc != DCCP_FEAT_SP_NOAGREE)
 778                         dccp_feat_empty_confirm(dccp_msk(sk), type, feature);
 779         }
 780
 781         /* generate the confirm [if required] */
 782         dccp_feat_flush_confirm(sk);
 783
 784         return rc;
 785 }
 786
 787 EXPORT_SYMBOL_GPL(dccp_feat_change_recv);
 788
 789 int dccp_feat_confirm_recv(struct sock *sk, u8 type, u8 feature,
 790                            u8 *val, u8 len)
 791 {
 792         u8 t;
 793         struct dccp_opt_pend *opt;
 794         struct dccp_minisock *dmsk = dccp_msk(sk);
 795         int found = 0;
 796         int all_confirmed = 1;
 797
 798         /* Ignore Confirm options other than during connection setup */
 799         if (sk->sk_state != DCCP_LISTEN && sk->sk_state != DCCP_REQUESTING)
 800                 return 0;
 801         dccp_feat_debug(type, feature, *val);
 802
 803         /* locate our change request */
 804         switch (type) {
 805         case DCCPO_CONFIRM_L: t = DCCPO_CHANGE_R; break;
 806         case DCCPO_CONFIRM_R: t = DCCPO_CHANGE_L; break;
 807         default:              DCCP_WARN("invalid type %d\n", type);
 808                               return 1;
 809
 810         }
 811         /* XXX sanity check feature value */
 812
 813         list_for_each_entry(opt, &dmsk->dccpms_pending, dccpop_node) {
 814                 if (!opt->dccpop_conf && opt->dccpop_type == t &&
 815                     opt->dccpop_feat == feature) {
 816                         found = 1;
 817                         dccp_pr_debug("feature %d found\n", opt->dccpop_feat);
 818
 819                         /* XXX do sanity check */
 820
 821                         opt->dccpop_conf = 1;
 822
 823                         /* We got a confirmation---change the option */
 824                         dccp_feat_update(sk, opt->dccpop_type,
 825                                          opt->dccpop_feat, *val);
 826
 827                         /* XXX check the return value of dccp_feat_update */
 828                         break;
 829                 }
 830
 831                 if (!opt->dccpop_conf)
 832                         all_confirmed = 0;
 833         }
 834
 835         if (!found)
 836                 dccp_pr_debug("%s(%d, ...) never requested\n",
 837                               dccp_feat_typename(type), feature);
 838         return 0;
 839 }
 840
 841 EXPORT_SYMBOL_GPL(dccp_feat_confirm_recv);
 842
 843 void dccp_feat_clean(struct dccp_minisock *dmsk)
 844 {
 845         struct dccp_opt_pend *opt, *next;
 846
 847         list_for_each_entry_safe(opt, next, &dmsk->dccpms_pending,
 848                                  dccpop_node) {
 849                 BUG_ON(opt->dccpop_val == NULL);
 850                 kfree(opt->dccpop_val);
 851
 852                 if (opt->dccpop_sc != NULL) {
 853                         BUG_ON(opt->dccpop_sc->dccpoc_val == NULL);
 854                         kfree(opt->dccpop_sc->dccpoc_val);
 855                         kfree(opt->dccpop_sc);
 856                 }
 857
 858                 kfree(opt);
 859         }
 860         INIT_LIST_HEAD(&dmsk->dccpms_pending);
 861
 862         list_for_each_entry_safe(opt, next, &dmsk->dccpms_conf, dccpop_node) {
 863                 BUG_ON(opt == NULL);
 864                 if (opt->dccpop_val != NULL)
 865                         kfree(opt->dccpop_val);
 866                 kfree(opt);
 867         }
 868         INIT_LIST_HEAD(&dmsk->dccpms_conf);
 869 }
 870
 871 EXPORT_SYMBOL_GPL(dccp_feat_clean);
 872
 873 /* this is to be called only when a listening sock creates its child.  It is
 874  * assumed by the function---the confirm is not duplicated, but rather it is
 875  * "passed on".
 876  */
 877 int dccp_feat_clone(struct sock *oldsk, struct sock *newsk)
 878 {
 879         struct dccp_minisock *olddmsk = dccp_msk(oldsk);
 880         struct dccp_minisock *newdmsk = dccp_msk(newsk);
 881         struct dccp_opt_pend *opt;
 882         int rc = 0;
 883
 884         INIT_LIST_HEAD(&newdmsk->dccpms_pending);
 885         INIT_LIST_HEAD(&newdmsk->dccpms_conf);
 886
 887         list_for_each_entry(opt, &olddmsk->dccpms_pending, dccpop_node) {
 888                 struct dccp_opt_pend *newopt;
 889                 /* copy the value of the option */
 890                 u8 *val = kmemdup(opt->dccpop_val, opt->dccpop_len, GFP_ATOMIC);
 891
 892                 if (val == NULL)
 893                         goto out_clean;
 894
 895                 newopt = kmemdup(opt, sizeof(*newopt), GFP_ATOMIC);
 896                 if (newopt == NULL) {
 897                         kfree(val);
 898                         goto out_clean;
 899                 }
 900
 901                 /* insert the option */
 902                 newopt->dccpop_val = val;
 903                 list_add_tail(&newopt->dccpop_node, &newdmsk->dccpms_pending);
 904
 905                 /* XXX what happens with backlogs and multiple connections at
 906                  * once...
 907                  */
 908                 /* the master socket no longer needs to worry about confirms */
 909                 opt->dccpop_sc = NULL; /* it's not a memleak---new socket has it */
 910
 911                 /* reset state for a new socket */
 912                 opt->dccpop_conf = 0;
 913         }
 914
 915         /* XXX not doing anything about the conf queue */
 916
 917 out:
 918         return rc;
 919
 920 out_clean:
 921         dccp_feat_clean(newdmsk);
 922         rc = -ENOMEM;
 923         goto out;
 924 }
 925
 926 EXPORT_SYMBOL_GPL(dccp_feat_clone);
 927
 928 int dccp_feat_init(struct sock *sk)
 929 {
 930         struct dccp_sock *dp = dccp_sk(sk);
 931         struct dccp_minisock *dmsk = dccp_msk(sk);
 932         int rc;
 933
 934         INIT_LIST_HEAD(&dmsk->dccpms_pending);  /* XXX no longer used */
 935         INIT_LIST_HEAD(&dmsk->dccpms_conf);     /* XXX no longer used */
 936
 937         /* CCID L */
 938         rc = __feat_register_sp(&dp->dccps_featneg, DCCPF_CCID, 1, 0,
 939                                 &dmsk->dccpms_tx_ccid, 1);
 940         if (rc)
 941                 goto out;
 942
 943         /* CCID R */
 944         rc = __feat_register_sp(&dp->dccps_featneg, DCCPF_CCID, 0, 0,
 945                                 &dmsk->dccpms_rx_ccid, 1);
 946         if (rc)
 947                 goto out;
 948
 949         /* Ack ratio */
 950         rc = __feat_register_nn(&dp->dccps_featneg, DCCPF_ACK_RATIO, 0,
 951                                 dmsk->dccpms_ack_ratio);
 952 out:
 953         return rc;
 954 }
 955
 956 EXPORT_SYMBOL_GPL(dccp_feat_init);
 957
 958 #ifdef CONFIG_IP_DCCP_DEBUG
 959 const char *dccp_feat_typename(const u8 type)
 960 {
 961         switch(type) {
 962         case DCCPO_CHANGE_L:  return("ChangeL");
 963         case DCCPO_CONFIRM_L: return("ConfirmL");
 964         case DCCPO_CHANGE_R:  return("ChangeR");
 965         case DCCPO_CONFIRM_R: return("ConfirmR");
 966         /* the following case must not appear in feature negotation  */
 967         default:              dccp_pr_debug("unknown type %d [BUG!]\n", type);
 968         }
 969         return NULL;
 970 }
 971
 972 EXPORT_SYMBOL_GPL(dccp_feat_typename);
 973
 974 const char *dccp_feat_name(const u8 feat)
 975 {
 976         static const char *feature_names[] = {
 977                 [DCCPF_RESERVED]        = "Reserved",
 978                 [DCCPF_CCID]            = "CCID",
 979                 [DCCPF_SHORT_SEQNOS]    = "Allow Short Seqnos",
 980                 [DCCPF_SEQUENCE_WINDOW] = "Sequence Window",
 981                 [DCCPF_ECN_INCAPABLE]   = "ECN Incapable",
 982                 [DCCPF_ACK_RATIO]       = "Ack Ratio",
 983                 [DCCPF_SEND_ACK_VECTOR] = "Send ACK Vector",
 984                 [DCCPF_SEND_NDP_COUNT]  = "Send NDP Count",
 985                 [DCCPF_MIN_CSUM_COVER]  = "Min. Csum Coverage",
 986                 [DCCPF_DATA_CHECKSUM]   = "Send Data Checksum",
 987         };
 988         if (feat > DCCPF_DATA_CHECKSUM && feat < DCCPF_MIN_CCID_SPECIFIC)
 989                 return feature_names[DCCPF_RESERVED];
 990
 991         if (feat ==  DCCPF_SEND_LEV_RATE)
 992                 return "Send Loss Event Rate";
 993         if (feat >= DCCPF_MIN_CCID_SPECIFIC)
 994                 return "CCID-specific";
 995
 996         return feature_names[feat];
 997 }
 998
 999 EXPORT_SYMBOL_GPL(dccp_feat_name);
1000 #endif /* CONFIG_IP_DCCP_DEBUG */