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