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          * There are no default values for unknown features, so encountering a
 100          * negative index here indicates a serious problem somewhere else.
 101          */
 102         DCCP_BUG_ON(idx < 0);
 103
 104         return idx < 0 ? 0 : dccp_feat_table[idx].default_value;
 105 }
 106
 107 /* copy constructor, fval must not already contain allocated memory */
 108 static int dccp_feat_clone_sp_val(dccp_feat_val *fval, u8 const *val, u8 len)
 109 {
 110         fval->sp.len = len;
 111         if (fval->sp.len > 0) {
 112                 fval->sp.vec = kmemdup(val, len, gfp_any());
 113                 if (fval->sp.vec == NULL) {
 114                         fval->sp.len = 0;
 115                         return -ENOBUFS;
 116                 }
 117         }
 118         return 0;
 119 }
 120
 121 static void dccp_feat_val_destructor(u8 feat_num, dccp_feat_val *val)
 122 {
 123         if (unlikely(val == NULL))
 124                 return;
 125         if (dccp_feat_type(feat_num) == FEAT_SP)
 126                 kfree(val->sp.vec);
 127         memset(val, 0, sizeof(*val));
 128 }
 129
 130 static struct dccp_feat_entry *
 131               dccp_feat_clone_entry(struct dccp_feat_entry const *original)
 132 {
 133         struct dccp_feat_entry *new;
 134         u8 type = dccp_feat_type(original->feat_num);
 135
 136         if (type == FEAT_UNKNOWN)
 137                 return NULL;
 138
 139         new = kmemdup(original, sizeof(struct dccp_feat_entry), gfp_any());
 140         if (new == NULL)
 141                 return NULL;
 142
 143         if (type == FEAT_SP && dccp_feat_clone_sp_val(&new->val,
 144                                                       original->val.sp.vec,
 145                                                       original->val.sp.len)) {
 146                 kfree(new);
 147                 return NULL;
 148         }
 149         return new;
 150 }
 151
 152 static void dccp_feat_entry_destructor(struct dccp_feat_entry *entry)
 153 {
 154         if (entry != NULL) {
 155                 dccp_feat_val_destructor(entry->feat_num, &entry->val);
 156                 kfree(entry);
 157         }
 158 }
 159
 160 /*
 161  * List management functions
 162  *
 163  * Feature negotiation lists rely on and maintain the following invariants:
 164  * - each feat_num in the list is known, i.e. we know its type and default value
 165  * - each feat_num/is_local combination is unique (old entries are overwritten)
 166  * - SP values are always freshly allocated
 167  * - list is sorted in increasing order of feature number (faster lookup)
 168  */
 169 static struct dccp_feat_entry *dccp_feat_list_lookup(struct list_head *fn_list,
 170                                                      u8 feat_num, bool is_local)
 171 {
 172         struct dccp_feat_entry *entry;
 173
 174         list_for_each_entry(entry, fn_list, node)
 175                 if (entry->feat_num == feat_num && entry->is_local == is_local)
 176                         return entry;
 177                 else if (entry->feat_num > feat_num)
 178                         break;
 179         return NULL;
 180 }
 181
 182 /**
 183  * dccp_feat_entry_new  -  Central list update routine (called by all others)
 184  * @head:  list to add to
 185  * @feat:  feature number
 186  * @local: whether the local (1) or remote feature with number @feat is meant
 187  * This is the only constructor and serves to ensure the above invariants.
 188  */
 189 static struct dccp_feat_entry *
 190               dccp_feat_entry_new(struct list_head *head, u8 feat, bool local)
 191 {
 192         struct dccp_feat_entry *entry;
 193
 194         list_for_each_entry(entry, head, node)
 195                 if (entry->feat_num == feat && entry->is_local == local) {
 196                         dccp_feat_val_destructor(entry->feat_num, &entry->val);
 197                         return entry;
 198                 } else if (entry->feat_num > feat) {
 199                         head = &entry->node;
 200                         break;
 201                 }
 202
 203         entry = kmalloc(sizeof(*entry), gfp_any());
 204         if (entry != NULL) {
 205                 entry->feat_num = feat;
 206                 entry->is_local = local;
 207                 list_add_tail(&entry->node, head);
 208         }
 209         return entry;
 210 }
 211
 212 /**
 213  * dccp_feat_push_change  -  Add/overwrite a Change option in the list
 214  * @fn_list: feature-negotiation list to update
 215  * @feat: one of %dccp_feature_numbers
 216  * @local: whether local (1) or remote (0) @feat_num is meant
 217  * @needs_mandatory: whether to use Mandatory feature negotiation options
 218  * @fval: pointer to NN/SP value to be inserted (will be copied)
 219  */
 220 static int dccp_feat_push_change(struct list_head *fn_list, u8 feat, u8 local,
 221                                  u8 mandatory, dccp_feat_val *fval)
 222 {
 223         struct dccp_feat_entry *new = dccp_feat_entry_new(fn_list, feat, local);
 224
 225         if (new == NULL)
 226                 return -ENOMEM;
 227
 228         new->feat_num        = feat;
 229         new->is_local        = local;
 230         new->state           = FEAT_INITIALISING;
 231         new->needs_confirm   = 0;
 232         new->empty_confirm   = 0;
 233         new->val             = *fval;
 234         new->needs_mandatory = mandatory;
 235
 236         return 0;
 237 }
 238
 239 static inline void dccp_feat_list_pop(struct dccp_feat_entry *entry)
 240 {
 241         list_del(&entry->node);
 242         dccp_feat_entry_destructor(entry);
 243 }
 244
 245 void dccp_feat_list_purge(struct list_head *fn_list)
 246 {
 247         struct dccp_feat_entry *entry, *next;
 248
 249         list_for_each_entry_safe(entry, next, fn_list, node)
 250                 dccp_feat_entry_destructor(entry);
 251         INIT_LIST_HEAD(fn_list);
 252 }
 253 EXPORT_SYMBOL_GPL(dccp_feat_list_purge);
 254
 255 /* generate @to as full clone of @from - @to must not contain any nodes */
 256 int dccp_feat_clone_list(struct list_head const *from, struct list_head *to)
 257 {
 258         struct dccp_feat_entry *entry, *new;
 259
 260         INIT_LIST_HEAD(to);
 261         list_for_each_entry(entry, from, node) {
 262                 new = dccp_feat_clone_entry(entry);
 263                 if (new == NULL)
 264                         goto cloning_failed;
 265                 list_add_tail(&new->node, to);
 266         }
 267         return 0;
 268
 269 cloning_failed:
 270         dccp_feat_list_purge(to);
 271         return -ENOMEM;
 272 }
 273
 274 static u8 dccp_feat_is_valid_nn_val(u8 feat_num, u64 val)
 275 {
 276         switch (feat_num) {
 277         case DCCPF_ACK_RATIO:
 278                 return val <= DCCPF_ACK_RATIO_MAX;
 279         case DCCPF_SEQUENCE_WINDOW:
 280                 return val >= DCCPF_SEQ_WMIN && val <= DCCPF_SEQ_WMAX;
 281         }
 282         return 0;       /* feature unknown - so we can't tell */
 283 }
 284
 285 /* check that SP values are within the ranges defined in RFC 4340 */
 286 static u8 dccp_feat_is_valid_sp_val(u8 feat_num, u8 val)
 287 {
 288         switch (feat_num) {
 289         case DCCPF_CCID:
 290                 return val == DCCPC_CCID2 || val == DCCPC_CCID3;
 291         /* Type-check Boolean feature values: */
 292         case DCCPF_SHORT_SEQNOS:
 293         case DCCPF_ECN_INCAPABLE:
 294         case DCCPF_SEND_ACK_VECTOR:
 295         case DCCPF_SEND_NDP_COUNT:
 296         case DCCPF_DATA_CHECKSUM:
 297         case DCCPF_SEND_LEV_RATE:
 298                 return val < 2;
 299         case DCCPF_MIN_CSUM_COVER:
 300                 return val < 16;
 301         }
 302         return 0;                       /* feature unknown */
 303 }
 304
 305 static u8 dccp_feat_sp_list_ok(u8 feat_num, u8 const *sp_list, u8 sp_len)
 306 {
 307         if (sp_list == NULL || sp_len < 1)
 308                 return 0;
 309         while (sp_len--)
 310                 if (!dccp_feat_is_valid_sp_val(feat_num, *sp_list++))
 311                         return 0;
 312         return 1;
 313 }
 314
 315 /**
 316  * __feat_register_nn  -  Register new NN value on socket
 317  * @fn: feature-negotiation list to register with
 318  * @feat: an NN feature from %dccp_feature_numbers
 319  * @mandatory: use Mandatory option if 1
 320  * @nn_val: value to register (restricted to 4 bytes)
 321  * Note that NN features are local by definition (RFC 4340, 6.3.2).
 322  */
 323 static int __feat_register_nn(struct list_head *fn, u8 feat,
 324                               u8 mandatory, u64 nn_val)
 325 {
 326         dccp_feat_val fval = { .nn = nn_val };
 327
 328         if (dccp_feat_type(feat) != FEAT_NN ||
 329             !dccp_feat_is_valid_nn_val(feat, nn_val))
 330                 return -EINVAL;
 331
 332         /* Don't bother with default values, they will be activated anyway. */
 333         if (nn_val - (u64)dccp_feat_default_value(feat) == 0)
 334                 return 0;
 335
 336         return dccp_feat_push_change(fn, feat, 1, mandatory, &fval);
 337 }
 338
 339 /**
 340  * __feat_register_sp  -  Register new SP value/list on socket
 341  * @fn: feature-negotiation list to register with
 342  * @feat: an SP feature from %dccp_feature_numbers
 343  * @is_local: whether the local (1) or the remote (0) @feat is meant
 344  * @mandatory: use Mandatory option if 1
 345  * @sp_val: SP value followed by optional preference list
 346  * @sp_len: length of @sp_val in bytes
 347  */
 348 static int __feat_register_sp(struct list_head *fn, u8 feat, u8 is_local,
 349                               u8 mandatory, u8 const *sp_val, u8 sp_len)
 350 {
 351         dccp_feat_val fval;
 352
 353         if (dccp_feat_type(feat) != FEAT_SP ||
 354             !dccp_feat_sp_list_ok(feat, sp_val, sp_len))
 355                 return -EINVAL;
 356
 357         /* Avoid negotiating alien CCIDs by only advertising supported ones */
 358         if (feat == DCCPF_CCID && !ccid_support_check(sp_val, sp_len))
 359                 return -EOPNOTSUPP;
 360
 361         if (dccp_feat_clone_sp_val(&fval, sp_val, sp_len))
 362                 return -ENOMEM;
 363
 364         return dccp_feat_push_change(fn, feat, is_local, mandatory, &fval);
 365 }
 366
 367 int dccp_feat_change(struct dccp_minisock *dmsk, u8 type, u8 feature,
 368                      u8 *val, u8 len, gfp_t gfp)
 369 {
 370         struct dccp_opt_pend *opt;
 371
 372         dccp_feat_debug(type, feature, *val);
 373
 374         if (len > 3) {
 375                 DCCP_WARN("invalid length %d\n", len);
 376                 return -EINVAL;
 377         }
 378         /* XXX add further sanity checks */
 379
 380         /* check if that feature is already being negotiated */
 381         list_for_each_entry(opt, &dmsk->dccpms_pending, dccpop_node) {
 382                 /* ok we found a negotiation for this option already */
 383                 if (opt->dccpop_feat == feature && opt->dccpop_type == type) {
 384                         dccp_pr_debug("Replacing old\n");
 385                         /* replace */
 386                         BUG_ON(opt->dccpop_val == NULL);
 387                         kfree(opt->dccpop_val);
 388                         opt->dccpop_val  = val;
 389                         opt->dccpop_len  = len;
 390                         opt->dccpop_conf = 0;
 391                         return 0;
 392                 }
 393         }
 394
 395         /* negotiation for a new feature */
 396         opt = kmalloc(sizeof(*opt), gfp);
 397         if (opt == NULL)
 398                 return -ENOMEM;
 399
 400         opt->dccpop_type = type;
 401         opt->dccpop_feat = feature;
 402         opt->dccpop_len  = len;
 403         opt->dccpop_val  = val;
 404         opt->dccpop_conf = 0;
 405         opt->dccpop_sc   = NULL;
 406
 407         BUG_ON(opt->dccpop_val == NULL);
 408
 409         list_add_tail(&opt->dccpop_node, &dmsk->dccpms_pending);
 410         return 0;
 411 }
 412
 413 EXPORT_SYMBOL_GPL(dccp_feat_change);
 414
 415 /*
 416  *      Tracking features whose value depend on the choice of CCID
 417  *
 418  * This is designed with an extension in mind so that a list walk could be done
 419  * before activating any features. However, the existing framework was found to
 420  * work satisfactorily up until now, the automatic verification is left open.
 421  * When adding new CCIDs, add a corresponding dependency table here.
 422  */
 423 static const struct ccid_dependency *dccp_feat_ccid_deps(u8 ccid, bool is_local)
 424 {
 425         static const struct ccid_dependency ccid2_dependencies[2][2] = {
 426                 /*
 427                  * CCID2 mandates Ack Vectors (RFC 4341, 4.): as CCID is a TX
 428                  * feature and Send Ack Vector is an RX feature, `is_local'
 429                  * needs to be reversed.
 430                  */
 431                 {       /* Dependencies of the receiver-side (remote) CCID2 */
 432                         {
 433                                 .dependent_feat = DCCPF_SEND_ACK_VECTOR,
 434                                 .is_local       = true,
 435                                 .is_mandatory   = true,
 436                                 .val            = 1
 437                         },
 438                         { 0, 0, 0, 0 }
 439                 },
 440                 {       /* Dependencies of the sender-side (local) CCID2 */
 441                         {
 442                                 .dependent_feat = DCCPF_SEND_ACK_VECTOR,
 443                                 .is_local       = false,
 444                                 .is_mandatory   = true,
 445                                 .val            = 1
 446                         },
 447                         { 0, 0, 0, 0 }
 448                 }
 449         };
 450         static const struct ccid_dependency ccid3_dependencies[2][5] = {
 451                 {       /*
 452                          * Dependencies of the receiver-side CCID3
 453                          */
 454                         {       /* locally disable Ack Vectors */
 455                                 .dependent_feat = DCCPF_SEND_ACK_VECTOR,
 456                                 .is_local       = true,
 457                                 .is_mandatory   = false,
 458                                 .val            = 0
 459                         },
 460                         {       /* see below why Send Loss Event Rate is on */
 461                                 .dependent_feat = DCCPF_SEND_LEV_RATE,
 462                                 .is_local       = true,
 463                                 .is_mandatory   = true,
 464                                 .val            = 1
 465                         },
 466                         {       /* NDP Count is needed as per RFC 4342, 6.1.1 */
 467                                 .dependent_feat = DCCPF_SEND_NDP_COUNT,
 468                                 .is_local       = false,
 469                                 .is_mandatory   = true,
 470                                 .val            = 1
 471                         },
 472                         { 0, 0, 0, 0 },
 473                 },
 474                 {       /*
 475                          * CCID3 at the TX side: we request that the HC-receiver
 476                          * will not send Ack Vectors (they will be ignored, so
 477                          * Mandatory is not set); we enable Send Loss Event Rate
 478                          * (Mandatory since the implementation does not support
 479                          * the Loss Intervals option of RFC 4342, 8.6).
 480                          * The last two options are for peer's information only.
 481                         */
 482                         {
 483                                 .dependent_feat = DCCPF_SEND_ACK_VECTOR,
 484                                 .is_local       = false,
 485                                 .is_mandatory   = false,
 486                                 .val            = 0
 487                         },
 488                         {
 489                                 .dependent_feat = DCCPF_SEND_LEV_RATE,
 490                                 .is_local       = false,
 491                                 .is_mandatory   = true,
 492                                 .val            = 1
 493                         },
 494                         {       /* this CCID does not support Ack Ratio */
 495                                 .dependent_feat = DCCPF_ACK_RATIO,
 496                                 .is_local       = true,
 497                                 .is_mandatory   = false,
 498                                 .val            = 0
 499                         },
 500                         {       /* tell receiver we are sending NDP counts */
 501                                 .dependent_feat = DCCPF_SEND_NDP_COUNT,
 502                                 .is_local       = true,
 503                                 .is_mandatory   = false,
 504                                 .val            = 1
 505                         },
 506                         { 0, 0, 0, 0 }
 507                 }
 508         };
 509         switch (ccid) {
 510         case DCCPC_CCID2:
 511                 return ccid2_dependencies[is_local];
 512         case DCCPC_CCID3:
 513                 return ccid3_dependencies[is_local];
 514         default:
 515                 return NULL;
 516         }
 517 }
 518
 519 /**
 520  * dccp_feat_propagate_ccid - Resolve dependencies of features on choice of CCID
 521  * @fn: feature-negotiation list to update
 522  * @id: CCID number to track
 523  * @is_local: whether TX CCID (1) or RX CCID (0) is meant
 524  * This function needs to be called after registering all other features.
 525  */
 526 static int dccp_feat_propagate_ccid(struct list_head *fn, u8 id, bool is_local)
 527 {
 528         const struct ccid_dependency *table = dccp_feat_ccid_deps(id, is_local);
 529         int i, rc = (table == NULL);
 530
 531         for (i = 0; rc == 0 && table[i].dependent_feat != DCCPF_RESERVED; i++)
 532                 if (dccp_feat_type(table[i].dependent_feat) == FEAT_SP)
 533                         rc = __feat_register_sp(fn, table[i].dependent_feat,
 534                                                     table[i].is_local,
 535                                                     table[i].is_mandatory,
 536                                                     &table[i].val, 1);
 537                 else
 538                         rc = __feat_register_nn(fn, table[i].dependent_feat,
 539                                                     table[i].is_mandatory,
 540                                                     table[i].val);
 541         return rc;
 542 }
 543
 544 /**
 545  * dccp_feat_finalise_settings  -  Finalise settings before starting negotiation
 546  * @dp: client or listening socket (settings will be inherited)
 547  * This is called after all registrations (socket initialisation, sysctls, and
 548  * sockopt calls), and before sending the first packet containing Change options
 549  * (ie. client-Request or server-Response), to ensure internal consistency.
 550  */
 551 int dccp_feat_finalise_settings(struct dccp_sock *dp)
 552 {
 553         struct list_head *fn = &dp->dccps_featneg;
 554         struct dccp_feat_entry *entry;
 555         int i = 2, ccids[2] = { -1, -1 };
 556
 557         /*
 558          * Propagating CCIDs:
 559          * 1) not useful to propagate CCID settings if this host advertises more
 560          *    than one CCID: the choice of CCID  may still change - if this is
 561          *    the client, or if this is the server and the client sends
 562          *    singleton CCID values.
 563          * 2) since is that propagate_ccid changes the list, we defer changing
 564          *    the sorted list until after the traversal.
 565          */
 566         list_for_each_entry(entry, fn, node)
 567                 if (entry->feat_num == DCCPF_CCID && entry->val.sp.len == 1)
 568                         ccids[entry->is_local] = entry->val.sp.vec[0];
 569         while (i--)
 570                 if (ccids[i] > 0 && dccp_feat_propagate_ccid(fn, ccids[i], i))
 571                         return -1;
 572         return 0;
 573 }
 574
 575 /**
 576  * dccp_feat_server_ccid_dependencies  -  Resolve CCID-dependent features
 577  * It is the server which resolves the dependencies once the CCID has been
 578  * fully negotiated. If no CCID has been negotiated, it uses the default CCID.
 579  */
 580 int dccp_feat_server_ccid_dependencies(struct dccp_request_sock *dreq)
 581 {
 582         struct list_head *fn = &dreq->dreq_featneg;
 583         struct dccp_feat_entry *entry;
 584         u8 is_local, ccid;
 585
 586         for (is_local = 0; is_local <= 1; is_local++) {
 587                 entry = dccp_feat_list_lookup(fn, DCCPF_CCID, is_local);
 588
 589                 if (entry != NULL && !entry->empty_confirm)
 590                         ccid = entry->val.sp.vec[0];
 591                 else
 592                         ccid = dccp_feat_default_value(DCCPF_CCID);
 593
 594                 if (dccp_feat_propagate_ccid(fn, ccid, is_local))
 595                         return -1;
 596         }
 597         return 0;
 598 }
 599
 600 static int dccp_feat_update_ccid(struct sock *sk, u8 type, u8 new_ccid_nr)
 601 {
 602         struct dccp_sock *dp = dccp_sk(sk);
 603         struct dccp_minisock *dmsk = dccp_msk(sk);
 604         /* figure out if we are changing our CCID or the peer's */
 605         const int rx = type == DCCPO_CHANGE_R;
 606         const u8 ccid_nr = rx ? dmsk->dccpms_rx_ccid : dmsk->dccpms_tx_ccid;
 607         struct ccid *new_ccid;
 608
 609         /* Check if nothing is being changed. */
 610         if (ccid_nr == new_ccid_nr)
 611                 return 0;
 612
 613         new_ccid = ccid_new(new_ccid_nr, sk, rx, GFP_ATOMIC);
 614         if (new_ccid == NULL)
 615                 return -ENOMEM;
 616
 617         if (rx) {
 618                 ccid_hc_rx_delete(dp->dccps_hc_rx_ccid, sk);
 619                 dp->dccps_hc_rx_ccid = new_ccid;
 620                 dmsk->dccpms_rx_ccid = new_ccid_nr;
 621         } else {
 622                 ccid_hc_tx_delete(dp->dccps_hc_tx_ccid, sk);
 623                 dp->dccps_hc_tx_ccid = new_ccid;
 624                 dmsk->dccpms_tx_ccid = new_ccid_nr;
 625         }
 626
 627         return 0;
 628 }
 629
 630 static int dccp_feat_update(struct sock *sk, u8 type, u8 feat, u8 val)
 631 {
 632         dccp_feat_debug(type, feat, val);
 633
 634         switch (feat) {
 635         case DCCPF_CCID:
 636                 return dccp_feat_update_ccid(sk, type, val);
 637         default:
 638                 dccp_pr_debug("UNIMPLEMENTED: %s(%d, ...)\n",
 639                               dccp_feat_typename(type), feat);
 640                 break;
 641         }
 642         return 0;
 643 }
 644
 645 static int dccp_feat_reconcile(struct sock *sk, struct dccp_opt_pend *opt,
 646                                u8 *rpref, u8 rlen)
 647 {
 648         struct dccp_sock *dp = dccp_sk(sk);
 649         u8 *spref, slen, *res = NULL;
 650         int i, j, rc, agree = 1;
 651
 652         BUG_ON(rpref == NULL);
 653
 654         /* check if we are the black sheep */
 655         if (dp->dccps_role == DCCP_ROLE_CLIENT) {
 656                 spref = rpref;
 657                 slen  = rlen;
 658                 rpref = opt->dccpop_val;
 659                 rlen  = opt->dccpop_len;
 660         } else {
 661                 spref = opt->dccpop_val;
 662                 slen  = opt->dccpop_len;
 663         }
 664         /*
 665          * Now we have server preference list in spref and client preference in
 666          * rpref
 667          */
 668         BUG_ON(spref == NULL);
 669         BUG_ON(rpref == NULL);
 670
 671         /* FIXME sanity check vals */
 672
 673         /* Are values in any order?  XXX Lame "algorithm" here */
 674         for (i = 0; i < slen; i++) {
 675                 for (j = 0; j < rlen; j++) {
 676                         if (spref[i] == rpref[j]) {
 677                                 res = &spref[i];
 678                                 break;
 679                         }
 680                 }
 681                 if (res)
 682                         break;
 683         }
 684
 685         /* we didn't agree on anything */
 686         if (res == NULL) {
 687                 /* confirm previous value */
 688                 switch (opt->dccpop_feat) {
 689                 case DCCPF_CCID:
 690                         /* XXX did i get this right? =P */
 691                         if (opt->dccpop_type == DCCPO_CHANGE_L)
 692                                 res = &dccp_msk(sk)->dccpms_tx_ccid;
 693                         else
 694                                 res = &dccp_msk(sk)->dccpms_rx_ccid;
 695                         break;
 696
 697                 default:
 698                         DCCP_BUG("Fell through, feat=%d", opt->dccpop_feat);
 699                         /* XXX implement res */
 700                         return -EFAULT;
 701                 }
 702
 703                 dccp_pr_debug("Don't agree... reconfirming %d\n", *res);
 704                 agree = 0; /* this is used for mandatory options... */
 705         }
 706
 707         /* need to put result and our preference list */
 708         rlen = 1 + opt->dccpop_len;
 709         rpref = kmalloc(rlen, GFP_ATOMIC);
 710         if (rpref == NULL)
 711                 return -ENOMEM;
 712
 713         *rpref = *res;
 714         memcpy(&rpref[1], opt->dccpop_val, opt->dccpop_len);
 715
 716         /* put it in the "confirm queue" */
 717         if (opt->dccpop_sc == NULL) {
 718                 opt->dccpop_sc = kmalloc(sizeof(*opt->dccpop_sc), GFP_ATOMIC);
 719                 if (opt->dccpop_sc == NULL) {
 720                         kfree(rpref);
 721                         return -ENOMEM;
 722                 }
 723         } else {
 724                 /* recycle the confirm slot */
 725                 BUG_ON(opt->dccpop_sc->dccpoc_val == NULL);
 726                 kfree(opt->dccpop_sc->dccpoc_val);
 727                 dccp_pr_debug("recycling confirm slot\n");
 728         }
 729         memset(opt->dccpop_sc, 0, sizeof(*opt->dccpop_sc));
 730
 731         opt->dccpop_sc->dccpoc_val = rpref;
 732         opt->dccpop_sc->dccpoc_len = rlen;
 733
 734         /* update the option on our side [we are about to send the confirm] */
 735         rc = dccp_feat_update(sk, opt->dccpop_type, opt->dccpop_feat, *res);
 736         if (rc) {
 737                 kfree(opt->dccpop_sc->dccpoc_val);
 738                 kfree(opt->dccpop_sc);
 739                 opt->dccpop_sc = NULL;
 740                 return rc;
 741         }
 742
 743         dccp_pr_debug("Will confirm %d\n", *rpref);
 744
 745         /* say we want to change to X but we just got a confirm X, suppress our
 746          * change
 747          */
 748         if (!opt->dccpop_conf) {
 749                 if (*opt->dccpop_val == *res)
 750                         opt->dccpop_conf = 1;
 751                 dccp_pr_debug("won't ask for change of same feature\n");
 752         }
 753
 754         return agree ? 0 : DCCP_FEAT_SP_NOAGREE; /* used for mandatory opts */
 755 }
 756
 757 static int dccp_feat_sp(struct sock *sk, u8 type, u8 feature, u8 *val, u8 len)
 758 {
 759         struct dccp_minisock *dmsk = dccp_msk(sk);
 760         struct dccp_opt_pend *opt;
 761         int rc = 1;
 762         u8 t;
 763
 764         /*
 765          * We received a CHANGE.  We gotta match it against our own preference
 766          * list.  If we got a CHANGE_R it means it's a change for us, so we need
 767          * to compare our CHANGE_L list.
 768          */
 769         if (type == DCCPO_CHANGE_L)
 770                 t = DCCPO_CHANGE_R;
 771         else
 772                 t = DCCPO_CHANGE_L;
 773
 774         /* find our preference list for this feature */
 775         list_for_each_entry(opt, &dmsk->dccpms_pending, dccpop_node) {
 776                 if (opt->dccpop_type != t || opt->dccpop_feat != feature)
 777                         continue;
 778
 779                 /* find the winner from the two preference lists */
 780                 rc = dccp_feat_reconcile(sk, opt, val, len);
 781                 break;
 782         }
 783
 784         /* We didn't deal with the change.  This can happen if we have no
 785          * preference list for the feature.  In fact, it just shouldn't
 786          * happen---if we understand a feature, we should have a preference list
 787          * with at least the default value.
 788          */
 789         BUG_ON(rc == 1);
 790
 791         return rc;
 792 }
 793
 794 static int dccp_feat_nn(struct sock *sk, u8 type, u8 feature, u8 *val, u8 len)
 795 {
 796         struct dccp_opt_pend *opt;
 797         struct dccp_minisock *dmsk = dccp_msk(sk);
 798         u8 *copy;
 799         int rc;
 800
 801         /* NN features must be Change L (sec. 6.3.2) */
 802         if (type != DCCPO_CHANGE_L) {
 803                 dccp_pr_debug("received %s for NN feature %d\n",
 804                                 dccp_feat_typename(type), feature);
 805                 return -EFAULT;
 806         }
 807
 808         /* XXX sanity check opt val */
 809
 810         /* copy option so we can confirm it */
 811         opt = kzalloc(sizeof(*opt), GFP_ATOMIC);
 812         if (opt == NULL)
 813                 return -ENOMEM;
 814
 815         copy = kmemdup(val, len, GFP_ATOMIC);
 816         if (copy == NULL) {
 817                 kfree(opt);
 818                 return -ENOMEM;
 819         }
 820
 821         opt->dccpop_type = DCCPO_CONFIRM_R; /* NN can only confirm R */
 822         opt->dccpop_feat = feature;
 823         opt->dccpop_val  = copy;
 824         opt->dccpop_len  = len;
 825
 826         /* change feature */
 827         rc = dccp_feat_update(sk, type, feature, *val);
 828         if (rc) {
 829                 kfree(opt->dccpop_val);
 830                 kfree(opt);
 831                 return rc;
 832         }
 833
 834         dccp_feat_debug(type, feature, *copy);
 835
 836         list_add_tail(&opt->dccpop_node, &dmsk->dccpms_conf);
 837
 838         return 0;
 839 }
 840
 841 static void dccp_feat_empty_confirm(struct dccp_minisock *dmsk,
 842                                     u8 type, u8 feature)
 843 {
 844         /* XXX check if other confirms for that are queued and recycle slot */
 845         struct dccp_opt_pend *opt = kzalloc(sizeof(*opt), GFP_ATOMIC);
 846
 847         if (opt == NULL) {
 848                 /* XXX what do we do?  Ignoring should be fine.  It's a change
 849                  * after all =P
 850                  */
 851                 return;
 852         }
 853
 854         switch (type) {
 855         case DCCPO_CHANGE_L:
 856                 opt->dccpop_type = DCCPO_CONFIRM_R;
 857                 break;
 858         case DCCPO_CHANGE_R:
 859                 opt->dccpop_type = DCCPO_CONFIRM_L;
 860                 break;
 861         default:
 862                 DCCP_WARN("invalid type %d\n", type);
 863                 kfree(opt);
 864                 return;
 865         }
 866         opt->dccpop_feat = feature;
 867         opt->dccpop_val  = NULL;
 868         opt->dccpop_len  = 0;
 869
 870         /* change feature */
 871         dccp_pr_debug("Empty %s(%d)\n", dccp_feat_typename(type), feature);
 872
 873         list_add_tail(&opt->dccpop_node, &dmsk->dccpms_conf);
 874 }
 875
 876 static void dccp_feat_flush_confirm(struct sock *sk)
 877 {
 878         struct dccp_minisock *dmsk = dccp_msk(sk);
 879         /* Check if there is anything to confirm in the first place */
 880         int yes = !list_empty(&dmsk->dccpms_conf);
 881
 882         if (!yes) {
 883                 struct dccp_opt_pend *opt;
 884
 885                 list_for_each_entry(opt, &dmsk->dccpms_pending, dccpop_node) {
 886                         if (opt->dccpop_conf) {
 887                                 yes = 1;
 888                                 break;
 889                         }
 890                 }
 891         }
 892
 893         if (!yes)
 894                 return;
 895
 896         /* OK there is something to confirm... */
 897         /* XXX check if packet is in flight?  Send delayed ack?? */
 898         if (sk->sk_state == DCCP_OPEN)
 899                 dccp_send_ack(sk);
 900 }
 901
 902 int dccp_feat_change_recv(struct sock *sk, u8 type, u8 feature, u8 *val, u8 len)
 903 {
 904         int rc;
 905
 906         /* Ignore Change requests other than during connection setup */
 907         if (sk->sk_state != DCCP_LISTEN && sk->sk_state != DCCP_REQUESTING)
 908                 return 0;
 909         dccp_feat_debug(type, feature, *val);
 910
 911         /* figure out if it's SP or NN feature */
 912         switch (feature) {
 913         /* deal with SP features */
 914         case DCCPF_CCID:
 915                 rc = dccp_feat_sp(sk, type, feature, val, len);
 916                 break;
 917
 918         /* deal with NN features */
 919         case DCCPF_ACK_RATIO:
 920                 rc = dccp_feat_nn(sk, type, feature, val, len);
 921                 break;
 922
 923         /* XXX implement other features */
 924         default:
 925                 dccp_pr_debug("UNIMPLEMENTED: not handling %s(%d, ...)\n",
 926                               dccp_feat_typename(type), feature);
 927                 rc = -EFAULT;
 928                 break;
 929         }
 930
 931         /* check if there were problems changing features */
 932         if (rc) {
 933                 /* If we don't agree on SP, we sent a confirm for old value.
 934                  * However we propagate rc to caller in case option was
 935                  * mandatory
 936                  */
 937                 if (rc != DCCP_FEAT_SP_NOAGREE)
 938                         dccp_feat_empty_confirm(dccp_msk(sk), type, feature);
 939         }
 940
 941         /* generate the confirm [if required] */
 942         dccp_feat_flush_confirm(sk);
 943
 944         return rc;
 945 }
 946
 947 EXPORT_SYMBOL_GPL(dccp_feat_change_recv);
 948
 949 int dccp_feat_confirm_recv(struct sock *sk, u8 type, u8 feature,
 950                            u8 *val, u8 len)
 951 {
 952         u8 t;
 953         struct dccp_opt_pend *opt;
 954         struct dccp_minisock *dmsk = dccp_msk(sk);
 955         int found = 0;
 956         int all_confirmed = 1;
 957
 958         /* Ignore Confirm options other than during connection setup */
 959         if (sk->sk_state != DCCP_LISTEN && sk->sk_state != DCCP_REQUESTING)
 960                 return 0;
 961         dccp_feat_debug(type, feature, *val);
 962
 963         /* locate our change request */
 964         switch (type) {
 965         case DCCPO_CONFIRM_L: t = DCCPO_CHANGE_R; break;
 966         case DCCPO_CONFIRM_R: t = DCCPO_CHANGE_L; break;
 967         default:              DCCP_WARN("invalid type %d\n", type);
 968                               return 1;
 969
 970         }
 971         /* XXX sanity check feature value */
 972
 973         list_for_each_entry(opt, &dmsk->dccpms_pending, dccpop_node) {
 974                 if (!opt->dccpop_conf && opt->dccpop_type == t &&
 975                     opt->dccpop_feat == feature) {
 976                         found = 1;
 977                         dccp_pr_debug("feature %d found\n", opt->dccpop_feat);
 978
 979                         /* XXX do sanity check */
 980
 981                         opt->dccpop_conf = 1;
 982
 983                         /* We got a confirmation---change the option */
 984                         dccp_feat_update(sk, opt->dccpop_type,
 985                                          opt->dccpop_feat, *val);
 986
 987                         /* XXX check the return value of dccp_feat_update */
 988                         break;
 989                 }
 990
 991                 if (!opt->dccpop_conf)
 992                         all_confirmed = 0;
 993         }
 994
 995         if (!found)
 996                 dccp_pr_debug("%s(%d, ...) never requested\n",
 997                               dccp_feat_typename(type), feature);
 998         return 0;
 999 }
1000
1001 EXPORT_SYMBOL_GPL(dccp_feat_confirm_recv);
1002
1003 void dccp_feat_clean(struct dccp_minisock *dmsk)
1004 {
1005         struct dccp_opt_pend *opt, *next;
1006
1007         list_for_each_entry_safe(opt, next, &dmsk->dccpms_pending,
1008                                  dccpop_node) {
1009                 BUG_ON(opt->dccpop_val == NULL);
1010                 kfree(opt->dccpop_val);
1011
1012                 if (opt->dccpop_sc != NULL) {
1013                         BUG_ON(opt->dccpop_sc->dccpoc_val == NULL);
1014                         kfree(opt->dccpop_sc->dccpoc_val);
1015                         kfree(opt->dccpop_sc);
1016                 }
1017
1018                 kfree(opt);
1019         }
1020         INIT_LIST_HEAD(&dmsk->dccpms_pending);
1021
1022         list_for_each_entry_safe(opt, next, &dmsk->dccpms_conf, dccpop_node) {
1023                 BUG_ON(opt == NULL);
1024                 if (opt->dccpop_val != NULL)
1025                         kfree(opt->dccpop_val);
1026                 kfree(opt);
1027         }
1028         INIT_LIST_HEAD(&dmsk->dccpms_conf);
1029 }
1030
1031 EXPORT_SYMBOL_GPL(dccp_feat_clean);
1032
1033 /* this is to be called only when a listening sock creates its child.  It is
1034  * assumed by the function---the confirm is not duplicated, but rather it is
1035  * "passed on".
1036  */
1037 int dccp_feat_clone(struct sock *oldsk, struct sock *newsk)
1038 {
1039         struct dccp_minisock *olddmsk = dccp_msk(oldsk);
1040         struct dccp_minisock *newdmsk = dccp_msk(newsk);
1041         struct dccp_opt_pend *opt;
1042         int rc = 0;
1043
1044         INIT_LIST_HEAD(&newdmsk->dccpms_pending);
1045         INIT_LIST_HEAD(&newdmsk->dccpms_conf);
1046
1047         list_for_each_entry(opt, &olddmsk->dccpms_pending, dccpop_node) {
1048                 struct dccp_opt_pend *newopt;
1049                 /* copy the value of the option */
1050                 u8 *val = kmemdup(opt->dccpop_val, opt->dccpop_len, GFP_ATOMIC);
1051
1052                 if (val == NULL)
1053                         goto out_clean;
1054
1055                 newopt = kmemdup(opt, sizeof(*newopt), GFP_ATOMIC);
1056                 if (newopt == NULL) {
1057                         kfree(val);
1058                         goto out_clean;
1059                 }
1060
1061                 /* insert the option */
1062                 newopt->dccpop_val = val;
1063                 list_add_tail(&newopt->dccpop_node, &newdmsk->dccpms_pending);
1064
1065                 /* XXX what happens with backlogs and multiple connections at
1066                  * once...
1067                  */
1068                 /* the master socket no longer needs to worry about confirms */
1069                 opt->dccpop_sc = NULL; /* it's not a memleak---new socket has it */
1070
1071                 /* reset state for a new socket */
1072                 opt->dccpop_conf = 0;
1073         }
1074
1075         /* XXX not doing anything about the conf queue */
1076
1077 out:
1078         return rc;
1079
1080 out_clean:
1081         dccp_feat_clean(newdmsk);
1082         rc = -ENOMEM;
1083         goto out;
1084 }
1085
1086 EXPORT_SYMBOL_GPL(dccp_feat_clone);
1087
1088 int dccp_feat_init(struct sock *sk)
1089 {
1090         struct dccp_sock *dp = dccp_sk(sk);
1091         struct dccp_minisock *dmsk = dccp_msk(sk);
1092         int rc;
1093
1094         INIT_LIST_HEAD(&dmsk->dccpms_pending);  /* XXX no longer used */
1095         INIT_LIST_HEAD(&dmsk->dccpms_conf);     /* XXX no longer used */
1096
1097         /* CCID L */
1098         rc = __feat_register_sp(&dp->dccps_featneg, DCCPF_CCID, 1, 0,
1099                                 &dmsk->dccpms_tx_ccid, 1);
1100         if (rc)
1101                 goto out;
1102
1103         /* CCID R */
1104         rc = __feat_register_sp(&dp->dccps_featneg, DCCPF_CCID, 0, 0,
1105                                 &dmsk->dccpms_rx_ccid, 1);
1106         if (rc)
1107                 goto out;
1108
1109         /* Ack ratio */
1110         rc = __feat_register_nn(&dp->dccps_featneg, DCCPF_ACK_RATIO, 0,
1111                                 dmsk->dccpms_ack_ratio);
1112 out:
1113         return rc;
1114 }
1115
1116 EXPORT_SYMBOL_GPL(dccp_feat_init);
1117
1118 #ifdef CONFIG_IP_DCCP_DEBUG
1119 const char *dccp_feat_typename(const u8 type)
1120 {
1121         switch(type) {
1122         case DCCPO_CHANGE_L:  return("ChangeL");
1123         case DCCPO_CONFIRM_L: return("ConfirmL");
1124         case DCCPO_CHANGE_R:  return("ChangeR");
1125         case DCCPO_CONFIRM_R: return("ConfirmR");
1126         /* the following case must not appear in feature negotation  */
1127         default:              dccp_pr_debug("unknown type %d [BUG!]\n", type);
1128         }
1129         return NULL;
1130 }
1131
1132 EXPORT_SYMBOL_GPL(dccp_feat_typename);
1133
1134 const char *dccp_feat_name(const u8 feat)
1135 {
1136         static const char *feature_names[] = {
1137                 [DCCPF_RESERVED]        = "Reserved",
1138                 [DCCPF_CCID]            = "CCID",
1139                 [DCCPF_SHORT_SEQNOS]    = "Allow Short Seqnos",
1140                 [DCCPF_SEQUENCE_WINDOW] = "Sequence Window",
1141                 [DCCPF_ECN_INCAPABLE]   = "ECN Incapable",
1142                 [DCCPF_ACK_RATIO]       = "Ack Ratio",
1143                 [DCCPF_SEND_ACK_VECTOR] = "Send ACK Vector",
1144                 [DCCPF_SEND_NDP_COUNT]  = "Send NDP Count",
1145                 [DCCPF_MIN_CSUM_COVER]  = "Min. Csum Coverage",
1146                 [DCCPF_DATA_CHECKSUM]   = "Send Data Checksum",
1147         };
1148         if (feat > DCCPF_DATA_CHECKSUM && feat < DCCPF_MIN_CCID_SPECIFIC)
1149                 return feature_names[DCCPF_RESERVED];
1150
1151         if (feat ==  DCCPF_SEND_LEV_RATE)
1152                 return "Send Loss Event Rate";
1153         if (feat >= DCCPF_MIN_CCID_SPECIFIC)
1154                 return "CCID-specific";
1155
1156         return feature_names[feat];
1157 }
1158
1159 EXPORT_SYMBOL_GPL(dccp_feat_name);
1160 #endif /* CONFIG_IP_DCCP_DEBUG */