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   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 All currently known SP features have 1-byte quantities. If in the future
  10  *    extensions of RFCs 4340..42 define features with item lengths larger than
  11  *    one byte, a feature-specific extension of the code will be required.
  12  *
  13  *  This program is free software; you can redistribute it and/or
  14  *  modify it under the terms of the GNU General Public License
  15  *  as published by the Free Software Foundation; either version
  16  *  2 of the License, or (at your option) any later version.
  17  */
  18
  19 #include <linux/module.h>
  20
  21 #include "ccid.h"
  22 #include "feat.h"
  23
  24 #define DCCP_FEAT_SP_NOAGREE (-123)
  25
  26 int dccp_feat_change(struct dccp_minisock *dmsk, u8 type, u8 feature,
  27                      u8 *val, u8 len, gfp_t gfp)
  28 {
  29         struct dccp_opt_pend *opt;
  30
  31         dccp_feat_debug(type, feature, *val);
  32
  33         if (len > 3) {
  34                 DCCP_WARN("invalid length %d\n", len);
  35                 return 1;
  36         }
  37         /* XXX add further sanity checks */
  38
  39         /* check if that feature is already being negotiated */
  40         list_for_each_entry(opt, &dmsk->dccpms_pending, dccpop_node) {
  41                 /* ok we found a negotiation for this option already */
  42                 if (opt->dccpop_feat == feature && opt->dccpop_type == type) {
  43                         dccp_pr_debug("Replacing old\n");
  44                         /* replace */
  45                         BUG_ON(opt->dccpop_val == NULL);
  46                         kfree(opt->dccpop_val);
  47                         opt->dccpop_val  = val;
  48                         opt->dccpop_len  = len;
  49                         opt->dccpop_conf = 0;
  50                         return 0;
  51                 }
  52         }
  53
  54         /* negotiation for a new feature */
  55         opt = kmalloc(sizeof(*opt), gfp);
  56         if (opt == NULL)
  57                 return -ENOMEM;
  58
  59         opt->dccpop_type = type;
  60         opt->dccpop_feat = feature;
  61         opt->dccpop_len  = len;
  62         opt->dccpop_val  = val;
  63         opt->dccpop_conf = 0;
  64         opt->dccpop_sc   = NULL;
  65
  66         BUG_ON(opt->dccpop_val == NULL);
  67
  68         list_add_tail(&opt->dccpop_node, &dmsk->dccpms_pending);
  69         return 0;
  70 }
  71
  72 EXPORT_SYMBOL_GPL(dccp_feat_change);
  73
  74 static int dccp_feat_update_ccid(struct sock *sk, u8 type, u8 new_ccid_nr)
  75 {
  76         struct dccp_sock *dp = dccp_sk(sk);
  77         struct dccp_minisock *dmsk = dccp_msk(sk);
  78         /* figure out if we are changing our CCID or the peer's */
  79         const int rx = type == DCCPO_CHANGE_R;
  80         const u8 ccid_nr = rx ? dmsk->dccpms_rx_ccid : dmsk->dccpms_tx_ccid;
  81         struct ccid *new_ccid;
  82
  83         /* Check if nothing is being changed. */
  84         if (ccid_nr == new_ccid_nr)
  85                 return 0;
  86
  87         new_ccid = ccid_new(new_ccid_nr, sk, rx, GFP_ATOMIC);
  88         if (new_ccid == NULL)
  89                 return -ENOMEM;
  90
  91         if (rx) {
  92                 ccid_hc_rx_delete(dp->dccps_hc_rx_ccid, sk);
  93                 dp->dccps_hc_rx_ccid = new_ccid;
  94                 dmsk->dccpms_rx_ccid = new_ccid_nr;
  95         } else {
  96                 ccid_hc_tx_delete(dp->dccps_hc_tx_ccid, sk);
  97                 dp->dccps_hc_tx_ccid = new_ccid;
  98                 dmsk->dccpms_tx_ccid = new_ccid_nr;
  99         }
 100
 101         return 0;
 102 }
 103
 104 static int dccp_feat_update(struct sock *sk, u8 type, u8 feat, u8 val)
 105 {
 106         dccp_feat_debug(type, feat, val);
 107
 108         switch (feat) {
 109         case DCCPF_CCID:
 110                 return dccp_feat_update_ccid(sk, type, val);
 111         default:
 112                 dccp_pr_debug("UNIMPLEMENTED: %s(%d, ...)\n",
 113                               dccp_feat_typename(type), feat);
 114                 break;
 115         }
 116         return 0;
 117 }
 118
 119 static int dccp_feat_reconcile(struct sock *sk, struct dccp_opt_pend *opt,
 120                                u8 *rpref, u8 rlen)
 121 {
 122         struct dccp_sock *dp = dccp_sk(sk);
 123         u8 *spref, slen, *res = NULL;
 124         int i, j, rc, agree = 1;
 125
 126         BUG_ON(rpref == NULL);
 127
 128         /* check if we are the black sheep */
 129         if (dp->dccps_role == DCCP_ROLE_CLIENT) {
 130                 spref = rpref;
 131                 slen  = rlen;
 132                 rpref = opt->dccpop_val;
 133                 rlen  = opt->dccpop_len;
 134         } else {
 135                 spref = opt->dccpop_val;
 136                 slen  = opt->dccpop_len;
 137         }
 138         /*
 139          * Now we have server preference list in spref and client preference in
 140          * rpref
 141          */
 142         BUG_ON(spref == NULL);
 143         BUG_ON(rpref == NULL);
 144
 145         /* FIXME sanity check vals */
 146
 147         /* Are values in any order?  XXX Lame "algorithm" here */
 148         for (i = 0; i < slen; i++) {
 149                 for (j = 0; j < rlen; j++) {
 150                         if (spref[i] == rpref[j]) {
 151                                 res = &spref[i];
 152                                 break;
 153                         }
 154                 }
 155                 if (res)
 156                         break;
 157         }
 158
 159         /* we didn't agree on anything */
 160         if (res == NULL) {
 161                 /* confirm previous value */
 162                 switch (opt->dccpop_feat) {
 163                 case DCCPF_CCID:
 164                         /* XXX did i get this right? =P */
 165                         if (opt->dccpop_type == DCCPO_CHANGE_L)
 166                                 res = &dccp_msk(sk)->dccpms_tx_ccid;
 167                         else
 168                                 res = &dccp_msk(sk)->dccpms_rx_ccid;
 169                         break;
 170
 171                 default:
 172                         DCCP_BUG("Fell through, feat=%d", opt->dccpop_feat);
 173                         /* XXX implement res */
 174                         return -EFAULT;
 175                 }
 176
 177                 dccp_pr_debug("Don't agree... reconfirming %d\n", *res);
 178                 agree = 0; /* this is used for mandatory options... */
 179         }
 180
 181         /* need to put result and our preference list */
 182         rlen = 1 + opt->dccpop_len;
 183         rpref = kmalloc(rlen, GFP_ATOMIC);
 184         if (rpref == NULL)
 185                 return -ENOMEM;
 186
 187         *rpref = *res;
 188         memcpy(&rpref[1], opt->dccpop_val, opt->dccpop_len);
 189
 190         /* put it in the "confirm queue" */
 191         if (opt->dccpop_sc == NULL) {
 192                 opt->dccpop_sc = kmalloc(sizeof(*opt->dccpop_sc), GFP_ATOMIC);
 193                 if (opt->dccpop_sc == NULL) {
 194                         kfree(rpref);
 195                         return -ENOMEM;
 196                 }
 197         } else {
 198                 /* recycle the confirm slot */
 199                 BUG_ON(opt->dccpop_sc->dccpoc_val == NULL);
 200                 kfree(opt->dccpop_sc->dccpoc_val);
 201                 dccp_pr_debug("recycling confirm slot\n");
 202         }
 203         memset(opt->dccpop_sc, 0, sizeof(*opt->dccpop_sc));
 204
 205         opt->dccpop_sc->dccpoc_val = rpref;
 206         opt->dccpop_sc->dccpoc_len = rlen;
 207
 208         /* update the option on our side [we are about to send the confirm] */
 209         rc = dccp_feat_update(sk, opt->dccpop_type, opt->dccpop_feat, *res);
 210         if (rc) {
 211                 kfree(opt->dccpop_sc->dccpoc_val);
 212                 kfree(opt->dccpop_sc);
 213                 opt->dccpop_sc = NULL;
 214                 return rc;
 215         }
 216
 217         dccp_pr_debug("Will confirm %d\n", *rpref);
 218
 219         /* say we want to change to X but we just got a confirm X, suppress our
 220          * change
 221          */
 222         if (!opt->dccpop_conf) {
 223                 if (*opt->dccpop_val == *res)
 224                         opt->dccpop_conf = 1;
 225                 dccp_pr_debug("won't ask for change of same feature\n");
 226         }
 227
 228         return agree ? 0 : DCCP_FEAT_SP_NOAGREE; /* used for mandatory opts */
 229 }
 230
 231 static int dccp_feat_sp(struct sock *sk, u8 type, u8 feature, u8 *val, u8 len)
 232 {
 233         struct dccp_minisock *dmsk = dccp_msk(sk);
 234         struct dccp_opt_pend *opt;
 235         int rc = 1;
 236         u8 t;
 237
 238         /*
 239          * We received a CHANGE.  We gotta match it against our own preference
 240          * list.  If we got a CHANGE_R it means it's a change for us, so we need
 241          * to compare our CHANGE_L list.
 242          */
 243         if (type == DCCPO_CHANGE_L)
 244                 t = DCCPO_CHANGE_R;
 245         else
 246                 t = DCCPO_CHANGE_L;
 247
 248         /* find our preference list for this feature */
 249         list_for_each_entry(opt, &dmsk->dccpms_pending, dccpop_node) {
 250                 if (opt->dccpop_type != t || opt->dccpop_feat != feature)
 251                         continue;
 252
 253                 /* find the winner from the two preference lists */
 254                 rc = dccp_feat_reconcile(sk, opt, val, len);
 255                 break;
 256         }
 257
 258         /* We didn't deal with the change.  This can happen if we have no
 259          * preference list for the feature.  In fact, it just shouldn't
 260          * happen---if we understand a feature, we should have a preference list
 261          * with at least the default value.
 262          */
 263         BUG_ON(rc == 1);
 264
 265         return rc;
 266 }
 267
 268 static int dccp_feat_nn(struct sock *sk, u8 type, u8 feature, u8 *val, u8 len)
 269 {
 270         struct dccp_opt_pend *opt;
 271         struct dccp_minisock *dmsk = dccp_msk(sk);
 272         u8 *copy;
 273         int rc;
 274
 275         /* NN features must be Change L (sec. 6.3.2) */
 276         if (type != DCCPO_CHANGE_L) {
 277                 dccp_pr_debug("received %s for NN feature %d\n",
 278                                 dccp_feat_typename(type), feature);
 279                 return -EFAULT;
 280         }
 281
 282         /* XXX sanity check opt val */
 283
 284         /* copy option so we can confirm it */
 285         opt = kzalloc(sizeof(*opt), GFP_ATOMIC);
 286         if (opt == NULL)
 287                 return -ENOMEM;
 288
 289         copy = kmemdup(val, len, GFP_ATOMIC);
 290         if (copy == NULL) {
 291                 kfree(opt);
 292                 return -ENOMEM;
 293         }
 294
 295         opt->dccpop_type = DCCPO_CONFIRM_R; /* NN can only confirm R */
 296         opt->dccpop_feat = feature;
 297         opt->dccpop_val  = copy;
 298         opt->dccpop_len  = len;
 299
 300         /* change feature */
 301         rc = dccp_feat_update(sk, type, feature, *val);
 302         if (rc) {
 303                 kfree(opt->dccpop_val);
 304                 kfree(opt);
 305                 return rc;
 306         }
 307
 308         dccp_feat_debug(type, feature, *copy);
 309
 310         list_add_tail(&opt->dccpop_node, &dmsk->dccpms_conf);
 311
 312         return 0;
 313 }
 314
 315 static void dccp_feat_empty_confirm(struct dccp_minisock *dmsk,
 316                                     u8 type, u8 feature)
 317 {
 318         /* XXX check if other confirms for that are queued and recycle slot */
 319         struct dccp_opt_pend *opt = kzalloc(sizeof(*opt), GFP_ATOMIC);
 320
 321         if (opt == NULL) {
 322                 /* XXX what do we do?  Ignoring should be fine.  It's a change
 323                  * after all =P
 324                  */
 325                 return;
 326         }
 327
 328         switch (type) {
 329         case DCCPO_CHANGE_L:
 330                 opt->dccpop_type = DCCPO_CONFIRM_R;
 331                 break;
 332         case DCCPO_CHANGE_R:
 333                 opt->dccpop_type = DCCPO_CONFIRM_L;
 334                 break;
 335         default:
 336                 DCCP_WARN("invalid type %d\n", type);
 337                 kfree(opt);
 338                 return;
 339         }
 340         opt->dccpop_feat = feature;
 341         opt->dccpop_val  = NULL;
 342         opt->dccpop_len  = 0;
 343
 344         /* change feature */
 345         dccp_pr_debug("Empty %s(%d)\n", dccp_feat_typename(type), feature);
 346
 347         list_add_tail(&opt->dccpop_node, &dmsk->dccpms_conf);
 348 }
 349
 350 static void dccp_feat_flush_confirm(struct sock *sk)
 351 {
 352         struct dccp_minisock *dmsk = dccp_msk(sk);
 353         /* Check if there is anything to confirm in the first place */
 354         int yes = !list_empty(&dmsk->dccpms_conf);
 355
 356         if (!yes) {
 357                 struct dccp_opt_pend *opt;
 358
 359                 list_for_each_entry(opt, &dmsk->dccpms_pending, dccpop_node) {
 360                         if (opt->dccpop_conf) {
 361                                 yes = 1;
 362                                 break;
 363                         }
 364                 }
 365         }
 366
 367         if (!yes)
 368                 return;
 369
 370         /* OK there is something to confirm... */
 371         /* XXX check if packet is in flight?  Send delayed ack?? */
 372         if (sk->sk_state == DCCP_OPEN)
 373                 dccp_send_ack(sk);
 374 }
 375
 376 int dccp_feat_change_recv(struct sock *sk, u8 type, u8 feature, u8 *val, u8 len)
 377 {
 378         int rc;
 379
 380         dccp_feat_debug(type, feature, *val);
 381
 382         /* figure out if it's SP or NN feature */
 383         switch (feature) {
 384         /* deal with SP features */
 385         case DCCPF_CCID:
 386                 rc = dccp_feat_sp(sk, type, feature, val, len);
 387                 break;
 388
 389         /* deal with NN features */
 390         case DCCPF_ACK_RATIO:
 391                 rc = dccp_feat_nn(sk, type, feature, val, len);
 392                 break;
 393
 394         /* XXX implement other features */
 395         default:
 396                 dccp_pr_debug("UNIMPLEMENTED: not handling %s(%d, ...)\n",
 397                               dccp_feat_typename(type), feature);
 398                 rc = -EFAULT;
 399                 break;
 400         }
 401
 402         /* check if there were problems changing features */
 403         if (rc) {
 404                 /* If we don't agree on SP, we sent a confirm for old value.
 405                  * However we propagate rc to caller in case option was
 406                  * mandatory
 407                  */
 408                 if (rc != DCCP_FEAT_SP_NOAGREE)
 409                         dccp_feat_empty_confirm(dccp_msk(sk), type, feature);
 410         }
 411
 412         /* generate the confirm [if required] */
 413         dccp_feat_flush_confirm(sk);
 414
 415         return rc;
 416 }
 417
 418 EXPORT_SYMBOL_GPL(dccp_feat_change_recv);
 419
 420 int dccp_feat_confirm_recv(struct sock *sk, u8 type, u8 feature,
 421                            u8 *val, u8 len)
 422 {
 423         u8 t;
 424         struct dccp_opt_pend *opt;
 425         struct dccp_minisock *dmsk = dccp_msk(sk);
 426         int found = 0;
 427         int all_confirmed = 1;
 428
 429         dccp_feat_debug(type, feature, *val);
 430
 431         /* locate our change request */
 432         switch (type) {
 433         case DCCPO_CONFIRM_L: t = DCCPO_CHANGE_R; break;
 434         case DCCPO_CONFIRM_R: t = DCCPO_CHANGE_L; break;
 435         default:              DCCP_WARN("invalid type %d\n", type);
 436                               return 1;
 437
 438         }
 439         /* XXX sanity check feature value */
 440
 441         list_for_each_entry(opt, &dmsk->dccpms_pending, dccpop_node) {
 442                 if (!opt->dccpop_conf && opt->dccpop_type == t &&
 443                     opt->dccpop_feat == feature) {
 444                         found = 1;
 445                         dccp_pr_debug("feature %d found\n", opt->dccpop_feat);
 446
 447                         /* XXX do sanity check */
 448
 449                         opt->dccpop_conf = 1;
 450
 451                         /* We got a confirmation---change the option */
 452                         dccp_feat_update(sk, opt->dccpop_type,
 453                                          opt->dccpop_feat, *val);
 454
 455                         /* XXX check the return value of dccp_feat_update */
 456                         break;
 457                 }
 458
 459                 if (!opt->dccpop_conf)
 460                         all_confirmed = 0;
 461         }
 462
 463         /* fix re-transmit timer */
 464         /* XXX gotta make sure that no option negotiation occurs during
 465          * connection shutdown.  Consider that the CLOSEREQ is sent and timer is
 466          * on.  if all options are confirmed it might kill timer which should
 467          * remain alive until close is received.
 468          */
 469         if (all_confirmed) {
 470                 dccp_pr_debug("clear feat negotiation timer %p\n", sk);
 471                 inet_csk_clear_xmit_timer(sk, ICSK_TIME_RETRANS);
 472         }
 473
 474         if (!found)
 475                 dccp_pr_debug("%s(%d, ...) never requested\n",
 476                               dccp_feat_typename(type), feature);
 477         return 0;
 478 }
 479
 480 EXPORT_SYMBOL_GPL(dccp_feat_confirm_recv);
 481
 482 void dccp_feat_clean(struct dccp_minisock *dmsk)
 483 {
 484         struct dccp_opt_pend *opt, *next;
 485
 486         list_for_each_entry_safe(opt, next, &dmsk->dccpms_pending,
 487                                  dccpop_node) {
 488                 BUG_ON(opt->dccpop_val == NULL);
 489                 kfree(opt->dccpop_val);
 490
 491                 if (opt->dccpop_sc != NULL) {
 492                         BUG_ON(opt->dccpop_sc->dccpoc_val == NULL);
 493                         kfree(opt->dccpop_sc->dccpoc_val);
 494                         kfree(opt->dccpop_sc);
 495                 }
 496
 497                 kfree(opt);
 498         }
 499         INIT_LIST_HEAD(&dmsk->dccpms_pending);
 500
 501         list_for_each_entry_safe(opt, next, &dmsk->dccpms_conf, dccpop_node) {
 502                 BUG_ON(opt == NULL);
 503                 if (opt->dccpop_val != NULL)
 504                         kfree(opt->dccpop_val);
 505                 kfree(opt);
 506         }
 507         INIT_LIST_HEAD(&dmsk->dccpms_conf);
 508 }
 509
 510 EXPORT_SYMBOL_GPL(dccp_feat_clean);
 511
 512 /* this is to be called only when a listening sock creates its child.  It is
 513  * assumed by the function---the confirm is not duplicated, but rather it is
 514  * "passed on".
 515  */
 516 int dccp_feat_clone(struct sock *oldsk, struct sock *newsk)
 517 {
 518         struct dccp_minisock *olddmsk = dccp_msk(oldsk);
 519         struct dccp_minisock *newdmsk = dccp_msk(newsk);
 520         struct dccp_opt_pend *opt;
 521         int rc = 0;
 522
 523         INIT_LIST_HEAD(&newdmsk->dccpms_pending);
 524         INIT_LIST_HEAD(&newdmsk->dccpms_conf);
 525
 526         list_for_each_entry(opt, &olddmsk->dccpms_pending, dccpop_node) {
 527                 struct dccp_opt_pend *newopt;
 528                 /* copy the value of the option */
 529                 u8 *val = kmemdup(opt->dccpop_val, opt->dccpop_len, GFP_ATOMIC);
 530
 531                 if (val == NULL)
 532                         goto out_clean;
 533
 534                 newopt = kmemdup(opt, sizeof(*newopt), GFP_ATOMIC);
 535                 if (newopt == NULL) {
 536                         kfree(val);
 537                         goto out_clean;
 538                 }
 539
 540                 /* insert the option */
 541                 newopt->dccpop_val = val;
 542                 list_add_tail(&newopt->dccpop_node, &newdmsk->dccpms_pending);
 543
 544                 /* XXX what happens with backlogs and multiple connections at
 545                  * once...
 546                  */
 547                 /* the master socket no longer needs to worry about confirms */
 548                 opt->dccpop_sc = NULL; /* it's not a memleak---new socket has it */
 549
 550                 /* reset state for a new socket */
 551                 opt->dccpop_conf = 0;
 552         }
 553
 554         /* XXX not doing anything about the conf queue */
 555
 556 out:
 557         return rc;
 558
 559 out_clean:
 560         dccp_feat_clean(newdmsk);
 561         rc = -ENOMEM;
 562         goto out;
 563 }
 564
 565 EXPORT_SYMBOL_GPL(dccp_feat_clone);
 566
 567 static int __dccp_feat_init(struct dccp_minisock *dmsk, u8 type, u8 feat,
 568                             u8 *val, u8 len)
 569 {
 570         int rc = -ENOMEM;
 571         u8 *copy = kmemdup(val, len, GFP_KERNEL);
 572
 573         if (copy != NULL) {
 574                 rc = dccp_feat_change(dmsk, type, feat, copy, len, GFP_KERNEL);
 575                 if (rc)
 576                         kfree(copy);
 577         }
 578         return rc;
 579 }
 580
 581 int dccp_feat_init(struct dccp_minisock *dmsk)
 582 {
 583         int rc;
 584
 585         INIT_LIST_HEAD(&dmsk->dccpms_pending);
 586         INIT_LIST_HEAD(&dmsk->dccpms_conf);
 587
 588         /* CCID L */
 589         rc = __dccp_feat_init(dmsk, DCCPO_CHANGE_L, DCCPF_CCID,
 590                               &dmsk->dccpms_tx_ccid, 1);
 591         if (rc)
 592                 goto out;
 593
 594         /* CCID R */
 595         rc = __dccp_feat_init(dmsk, DCCPO_CHANGE_R, DCCPF_CCID,
 596                               &dmsk->dccpms_rx_ccid, 1);
 597         if (rc)
 598                 goto out;
 599
 600         /* Ack ratio */
 601         rc = __dccp_feat_init(dmsk, DCCPO_CHANGE_L, DCCPF_ACK_RATIO,
 602                               &dmsk->dccpms_ack_ratio, 1);
 603 out:
 604         return rc;
 605 }
 606
 607 EXPORT_SYMBOL_GPL(dccp_feat_init);
 608
 609 #ifdef CONFIG_IP_DCCP_DEBUG
 610 const char *dccp_feat_typename(const u8 type)
 611 {
 612         switch(type) {
 613         case DCCPO_CHANGE_L:  return("ChangeL");
 614         case DCCPO_CONFIRM_L: return("ConfirmL");
 615         case DCCPO_CHANGE_R:  return("ChangeR");
 616         case DCCPO_CONFIRM_R: return("ConfirmR");
 617         /* the following case must not appear in feature negotation  */
 618         default:              dccp_pr_debug("unknown type %d [BUG!]\n", type);
 619         }
 620         return NULL;
 621 }
 622
 623 EXPORT_SYMBOL_GPL(dccp_feat_typename);
 624
 625 const char *dccp_feat_name(const u8 feat)
 626 {
 627         static const char *feature_names[] = {
 628                 [DCCPF_RESERVED]        = "Reserved",
 629                 [DCCPF_CCID]            = "CCID",
 630                 [DCCPF_SHORT_SEQNOS]    = "Allow Short Seqnos",
 631                 [DCCPF_SEQUENCE_WINDOW] = "Sequence Window",
 632                 [DCCPF_ECN_INCAPABLE]   = "ECN Incapable",
 633                 [DCCPF_ACK_RATIO]       = "Ack Ratio",
 634                 [DCCPF_SEND_ACK_VECTOR] = "Send ACK Vector",
 635                 [DCCPF_SEND_NDP_COUNT]  = "Send NDP Count",
 636                 [DCCPF_MIN_CSUM_COVER]  = "Min. Csum Coverage",
 637                 [DCCPF_DATA_CHECKSUM]   = "Send Data Checksum",
 638         };
 639         if (feat > DCCPF_DATA_CHECKSUM && feat < DCCPF_MIN_CCID_SPECIFIC)
 640                 return feature_names[DCCPF_RESERVED];
 641
 642         if (feat >= DCCPF_MIN_CCID_SPECIFIC)
 643                 return "CCID-specific";
 644
 645         return feature_names[feat];
 646 }
 647
 648 EXPORT_SYMBOL_GPL(dccp_feat_name);
 649 #endif /* CONFIG_IP_DCCP_DEBUG */