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 (!dccp_feat_is_valid_type(type)) {
  28                 pr_info("option type %d invalid in negotiation\n", type);
  29                 return 1;
  30         }
  31         if (!dccp_feat_is_valid_length(type, feature, len)) {
  32                 pr_info("invalid length %d\n", len);
  33                 return 1;
  34         }
  35         /* XXX add further sanity checks */
  36
  37         /* check if that feature is already being negotiated */
  38         list_for_each_entry(opt, &dmsk->dccpms_pending, dccpop_node) {
  39                 /* ok we found a negotiation for this option already */
  40                 if (opt->dccpop_feat == feature && opt->dccpop_type == type) {
  41                         dccp_pr_debug("Replacing old\n");
  42                         /* replace */
  43                         BUG_ON(opt->dccpop_val == NULL);
  44                         kfree(opt->dccpop_val);
  45                         opt->dccpop_val  = val;
  46                         opt->dccpop_len  = len;
  47                         opt->dccpop_conf = 0;
  48                         return 0;
  49                 }
  50         }
  51
  52         /* negotiation for a new feature */
  53         opt = kmalloc(sizeof(*opt), gfp);
  54         if (opt == NULL)
  55                 return -ENOMEM;
  56
  57         opt->dccpop_type = type;
  58         opt->dccpop_feat = feature;
  59         opt->dccpop_len  = len;
  60         opt->dccpop_val  = val;
  61         opt->dccpop_conf = 0;
  62         opt->dccpop_sc   = NULL;
  63
  64         BUG_ON(opt->dccpop_val == NULL);
  65
  66         list_add_tail(&opt->dccpop_node, &dmsk->dccpms_pending);
  67         return 0;
  68 }
  69
  70 EXPORT_SYMBOL_GPL(dccp_feat_change);
  71
  72 static int dccp_feat_update_ccid(struct sock *sk, u8 type, u8 new_ccid_nr)
  73 {
  74         struct dccp_sock *dp = dccp_sk(sk);
  75         struct dccp_minisock *dmsk = dccp_msk(sk);
  76         /* figure out if we are changing our CCID or the peer's */
  77         const int rx = type == DCCPO_CHANGE_R;
  78         const u8 ccid_nr = rx ? dmsk->dccpms_rx_ccid : dmsk->dccpms_tx_ccid;
  79         struct ccid *new_ccid;
  80
  81         /* Check if nothing is being changed. */
  82         if (ccid_nr == new_ccid_nr)
  83                 return 0;
  84
  85         new_ccid = ccid_new(new_ccid_nr, sk, rx, GFP_ATOMIC);
  86         if (new_ccid == NULL)
  87                 return -ENOMEM;
  88
  89         if (rx) {
  90                 ccid_hc_rx_delete(dp->dccps_hc_rx_ccid, sk);
  91                 dp->dccps_hc_rx_ccid = new_ccid;
  92                 dmsk->dccpms_rx_ccid = new_ccid_nr;
  93         } else {
  94                 ccid_hc_tx_delete(dp->dccps_hc_tx_ccid, sk);
  95                 dp->dccps_hc_tx_ccid = new_ccid;
  96                 dmsk->dccpms_tx_ccid = new_ccid_nr;
  97         }
  98
  99         return 0;
 100 }
 101
 102 /* XXX taking only u8 vals */
 103 static int dccp_feat_update(struct sock *sk, u8 type, u8 feat, u8 val)
 104 {
 105         dccp_feat_debug(type, feat, val);
 106
 107         switch (feat) {
 108         case DCCPF_CCID:
 109                 return dccp_feat_update_ccid(sk, type, val);
 110         default:
 111                 dccp_pr_debug("UNIMPLEMENTED: %s(%d, ...)\n",
 112                               dccp_feat_typename(type), feat);
 113                 break;
 114         }
 115         return 0;
 116 }
 117
 118 static int dccp_feat_reconcile(struct sock *sk, struct dccp_opt_pend *opt,
 119                                u8 *rpref, u8 rlen)
 120 {
 121         struct dccp_sock *dp = dccp_sk(sk);
 122         u8 *spref, slen, *res = NULL;
 123         int i, j, rc, agree = 1;
 124
 125         BUG_ON(rpref == NULL);
 126
 127         /* check if we are the black sheep */
 128         if (dp->dccps_role == DCCP_ROLE_CLIENT) {
 129                 spref = rpref;
 130                 slen  = rlen;
 131                 rpref = opt->dccpop_val;
 132                 rlen  = opt->dccpop_len;
 133         } else {
 134                 spref = opt->dccpop_val;
 135                 slen  = opt->dccpop_len;
 136         }
 137         /*
 138          * Now we have server preference list in spref and client preference in
 139          * rpref
 140          */
 141         BUG_ON(spref == NULL);
 142         BUG_ON(rpref == NULL);
 143
 144         /* FIXME sanity check vals */
 145
 146         /* Are values in any order?  XXX Lame "algorithm" here */
 147         /* XXX assume values are 1 byte */
 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                         WARN_ON(1); /* XXX implement res */
 173                         return -EFAULT;
 174                 }
 175
 176                 dccp_pr_debug("Don't agree... reconfirming %d\n", *res);
 177                 agree = 0; /* this is used for mandatory options... */
 178         }
 179
 180         /* need to put result and our preference list */
 181         /* XXX assume 1 byte vals */
 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: opt->dccpop_type = DCCPO_CONFIRM_R; break;
 330         case DCCPO_CHANGE_R: opt->dccpop_type = DCCPO_CONFIRM_L; break;
 331         default:             pr_info("invalid type %d\n", type); return;
 332
 333         }
 334         opt->dccpop_feat = feature;
 335         opt->dccpop_val  = NULL;
 336         opt->dccpop_len  = 0;
 337
 338         /* change feature */
 339         dccp_pr_debug("Empty %s(%d)\n", dccp_feat_typename(type), feature);
 340
 341         list_add_tail(&opt->dccpop_node, &dmsk->dccpms_conf);
 342 }
 343
 344 static void dccp_feat_flush_confirm(struct sock *sk)
 345 {
 346         struct dccp_minisock *dmsk = dccp_msk(sk);
 347         /* Check if there is anything to confirm in the first place */
 348         int yes = !list_empty(&dmsk->dccpms_conf);
 349
 350         if (!yes) {
 351                 struct dccp_opt_pend *opt;
 352
 353                 list_for_each_entry(opt, &dmsk->dccpms_pending, dccpop_node) {
 354                         if (opt->dccpop_conf) {
 355                                 yes = 1;
 356                                 break;
 357                         }
 358                 }
 359         }
 360
 361         if (!yes)
 362                 return;
 363
 364         /* OK there is something to confirm... */
 365         /* XXX check if packet is in flight?  Send delayed ack?? */
 366         if (sk->sk_state == DCCP_OPEN)
 367                 dccp_send_ack(sk);
 368 }
 369
 370 int dccp_feat_change_recv(struct sock *sk, u8 type, u8 feature, u8 *val, u8 len)
 371 {
 372         int rc;
 373
 374         dccp_feat_debug(type, feature, *val);
 375
 376         /* figure out if it's SP or NN feature */
 377         switch (feature) {
 378         /* deal with SP features */
 379         case DCCPF_CCID:
 380                 rc = dccp_feat_sp(sk, type, feature, val, len);
 381                 break;
 382
 383         /* deal with NN features */
 384         case DCCPF_ACK_RATIO:
 385                 rc = dccp_feat_nn(sk, type, feature, val, len);
 386                 break;
 387
 388         /* XXX implement other features */
 389         default:
 390                 dccp_pr_debug("UNIMPLEMENTED: not handling %s(%d, ...)\n",
 391                               dccp_feat_typename(type), feature);
 392                 rc = -EFAULT;
 393                 break;
 394         }
 395
 396         /* check if there were problems changing features */
 397         if (rc) {
 398                 /* If we don't agree on SP, we sent a confirm for old value.
 399                  * However we propagate rc to caller in case option was
 400                  * mandatory
 401                  */
 402                 if (rc != DCCP_FEAT_SP_NOAGREE)
 403                         dccp_feat_empty_confirm(dccp_msk(sk), type, feature);
 404         }
 405
 406         /* generate the confirm [if required] */
 407         dccp_feat_flush_confirm(sk);
 408
 409         return rc;
 410 }
 411
 412 EXPORT_SYMBOL_GPL(dccp_feat_change_recv);
 413
 414 int dccp_feat_confirm_recv(struct sock *sk, u8 type, u8 feature,
 415                            u8 *val, u8 len)
 416 {
 417         u8 t;
 418         struct dccp_opt_pend *opt;
 419         struct dccp_minisock *dmsk = dccp_msk(sk);
 420         int found = 0;
 421         int all_confirmed = 1;
 422
 423         dccp_feat_debug(type, feature, *val);
 424
 425         /* locate our change request */
 426         switch (type) {
 427         case DCCPO_CONFIRM_L: t = DCCPO_CHANGE_R; break;
 428         case DCCPO_CONFIRM_R: t = DCCPO_CHANGE_L; break;
 429         default:              pr_info("invalid type %d\n", type);
 430                               return 1;
 431
 432         }
 433         /* XXX sanity check feature value */
 434
 435         list_for_each_entry(opt, &dmsk->dccpms_pending, dccpop_node) {
 436                 if (!opt->dccpop_conf && opt->dccpop_type == t &&
 437                     opt->dccpop_feat == feature) {
 438                         found = 1;
 439                         dccp_pr_debug("feature %d found\n", opt->dccpop_feat);
 440
 441                         /* XXX do sanity check */
 442
 443                         opt->dccpop_conf = 1;
 444
 445                         /* We got a confirmation---change the option */
 446                         dccp_feat_update(sk, opt->dccpop_type,
 447                                          opt->dccpop_feat, *val);
 448
 449                         /* XXX check the return value of dccp_feat_update */
 450                         break;
 451                 }
 452
 453                 if (!opt->dccpop_conf)
 454                         all_confirmed = 0;
 455         }
 456
 457         /* fix re-transmit timer */
 458         /* XXX gotta make sure that no option negotiation occurs during
 459          * connection shutdown.  Consider that the CLOSEREQ is sent and timer is
 460          * on.  if all options are confirmed it might kill timer which should
 461          * remain alive until close is received.
 462          */
 463         if (all_confirmed) {
 464                 dccp_pr_debug("clear feat negotiation timer %p\n", sk);
 465                 inet_csk_clear_xmit_timer(sk, ICSK_TIME_RETRANS);
 466         }
 467
 468         if (!found)
 469                 dccp_pr_debug("%s(%d, ...) never requested\n",
 470                               dccp_feat_typename(type), feature);
 471         return 0;
 472 }
 473
 474 EXPORT_SYMBOL_GPL(dccp_feat_confirm_recv);
 475
 476 void dccp_feat_clean(struct dccp_minisock *dmsk)
 477 {
 478         struct dccp_opt_pend *opt, *next;
 479
 480         list_for_each_entry_safe(opt, next, &dmsk->dccpms_pending,
 481                                  dccpop_node) {
 482                 BUG_ON(opt->dccpop_val == NULL);
 483                 kfree(opt->dccpop_val);
 484
 485                 if (opt->dccpop_sc != NULL) {
 486                         BUG_ON(opt->dccpop_sc->dccpoc_val == NULL);
 487                         kfree(opt->dccpop_sc->dccpoc_val);
 488                         kfree(opt->dccpop_sc);
 489                 }
 490
 491                 kfree(opt);
 492         }
 493         INIT_LIST_HEAD(&dmsk->dccpms_pending);
 494
 495         list_for_each_entry_safe(opt, next, &dmsk->dccpms_conf, dccpop_node) {
 496                 BUG_ON(opt == NULL);
 497                 if (opt->dccpop_val != NULL)
 498                         kfree(opt->dccpop_val);
 499                 kfree(opt);
 500         }
 501         INIT_LIST_HEAD(&dmsk->dccpms_conf);
 502 }
 503
 504 EXPORT_SYMBOL_GPL(dccp_feat_clean);
 505
 506 /* this is to be called only when a listening sock creates its child.  It is
 507  * assumed by the function---the confirm is not duplicated, but rather it is
 508  * "passed on".
 509  */
 510 int dccp_feat_clone(struct sock *oldsk, struct sock *newsk)
 511 {
 512         struct dccp_minisock *olddmsk = dccp_msk(oldsk);
 513         struct dccp_minisock *newdmsk = dccp_msk(newsk);
 514         struct dccp_opt_pend *opt;
 515         int rc = 0;
 516
 517         INIT_LIST_HEAD(&newdmsk->dccpms_pending);
 518         INIT_LIST_HEAD(&newdmsk->dccpms_conf);
 519
 520         list_for_each_entry(opt, &olddmsk->dccpms_pending, dccpop_node) {
 521                 struct dccp_opt_pend *newopt;
 522                 /* copy the value of the option */
 523                 u8 *val = kmemdup(opt->dccpop_val, opt->dccpop_len, GFP_ATOMIC);
 524
 525                 if (val == NULL)
 526                         goto out_clean;
 527
 528                 newopt = kmemdup(opt, sizeof(*newopt), GFP_ATOMIC);
 529                 if (newopt == NULL) {
 530                         kfree(val);
 531                         goto out_clean;
 532                 }
 533
 534                 /* insert the option */
 535                 newopt->dccpop_val = val;
 536                 list_add_tail(&newopt->dccpop_node, &newdmsk->dccpms_pending);
 537
 538                 /* XXX what happens with backlogs and multiple connections at
 539                  * once...
 540                  */
 541                 /* the master socket no longer needs to worry about confirms */
 542                 opt->dccpop_sc = NULL; /* it's not a memleak---new socket has it */
 543
 544                 /* reset state for a new socket */
 545                 opt->dccpop_conf = 0;
 546         }
 547
 548         /* XXX not doing anything about the conf queue */
 549
 550 out:
 551         return rc;
 552
 553 out_clean:
 554         dccp_feat_clean(newdmsk);
 555         rc = -ENOMEM;
 556         goto out;
 557 }
 558
 559 EXPORT_SYMBOL_GPL(dccp_feat_clone);
 560
 561 static int __dccp_feat_init(struct dccp_minisock *dmsk, u8 type, u8 feat,
 562                             u8 *val, u8 len)
 563 {
 564         int rc = -ENOMEM;
 565         u8 *copy = kmemdup(val, len, GFP_KERNEL);
 566
 567         if (copy != NULL) {
 568                 rc = dccp_feat_change(dmsk, type, feat, copy, len, GFP_KERNEL);
 569                 if (rc)
 570                         kfree(copy);
 571         }
 572         return rc;
 573 }
 574
 575 int dccp_feat_init(struct dccp_minisock *dmsk)
 576 {
 577         int rc;
 578
 579         INIT_LIST_HEAD(&dmsk->dccpms_pending);
 580         INIT_LIST_HEAD(&dmsk->dccpms_conf);
 581
 582         /* CCID L */
 583         rc = __dccp_feat_init(dmsk, DCCPO_CHANGE_L, DCCPF_CCID,
 584                               &dmsk->dccpms_tx_ccid, 1);
 585         if (rc)
 586                 goto out;
 587
 588         /* CCID R */
 589         rc = __dccp_feat_init(dmsk, DCCPO_CHANGE_R, DCCPF_CCID,
 590                               &dmsk->dccpms_rx_ccid, 1);
 591         if (rc)
 592                 goto out;
 593
 594         /* Ack ratio */
 595         rc = __dccp_feat_init(dmsk, DCCPO_CHANGE_L, DCCPF_ACK_RATIO,
 596                               &dmsk->dccpms_ack_ratio, 1);
 597 out:
 598         return rc;
 599 }
 600
 601 EXPORT_SYMBOL_GPL(dccp_feat_init);
 602
 603 #ifdef CONFIG_IP_DCCP_DEBUG
 604 const char *dccp_feat_typename(const u8 type)
 605 {
 606         switch(type) {
 607         case DCCPO_CHANGE_L:  return("ChangeL");
 608         case DCCPO_CONFIRM_L: return("ConfirmL");
 609         case DCCPO_CHANGE_R:  return("ChangeR");
 610         case DCCPO_CONFIRM_R: return("ConfirmR");
 611         /* the following case must not appear in feature negotation  */
 612         default:              dccp_pr_debug("unknown type %d [BUG!]\n", type);
 613         }
 614         return NULL;
 615 }
 616
 617 EXPORT_SYMBOL_GPL(dccp_feat_typename);
 618
 619 const char *dccp_feat_name(const u8 feat)
 620 {
 621         static const char *feature_names[] = {
 622                 [DCCPF_RESERVED]        = "Reserved",
 623                 [DCCPF_CCID]            = "CCID",
 624                 [DCCPF_SHORT_SEQNOS]    = "Allow Short Seqnos",
 625                 [DCCPF_SEQUENCE_WINDOW] = "Sequence Window",
 626                 [DCCPF_ECN_INCAPABLE]   = "ECN Incapable",
 627                 [DCCPF_ACK_RATIO]       = "Ack Ratio",
 628                 [DCCPF_SEND_ACK_VECTOR] = "Send ACK Vector",
 629                 [DCCPF_SEND_NDP_COUNT]  = "Send NDP Count",
 630                 [DCCPF_MIN_CSUM_COVER]  = "Min. Csum Coverage",
 631                 [DCCPF_DATA_CHECKSUM]   = "Send Data Checksum",
 632         };
 633         if (feat >= DCCPF_MIN_CCID_SPECIFIC)
 634                 return "CCID-specific";
 635
 636         if (dccp_feat_is_reserved(feat))
 637                 return feature_names[DCCPF_RESERVED];
 638
 639         return feature_names[feat];
 640 }
 641
 642 EXPORT_SYMBOL_GPL(dccp_feat_name);
 643 #endif /* CONFIG_IP_DCCP_DEBUG */