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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  *      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                 DCCP_WARN("option type %d invalid in negotiation\n", type);
  29                 return 1;
  30         }
  31         if (!dccp_feat_is_valid_length(type, feature, len)) {
  32                 DCCP_WARN("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                         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         /* XXX assume 1 byte vals */
 183         rlen = 1 + opt->dccpop_len;
 184         rpref = kmalloc(rlen, GFP_ATOMIC);
 185         if (rpref == NULL)
 186                 return -ENOMEM;
 187
 188         *rpref = *res;
 189         memcpy(&rpref[1], opt->dccpop_val, opt->dccpop_len);
 190
 191         /* put it in the "confirm queue" */
 192         if (opt->dccpop_sc == NULL) {
 193                 opt->dccpop_sc = kmalloc(sizeof(*opt->dccpop_sc), GFP_ATOMIC);
 194                 if (opt->dccpop_sc == NULL) {
 195                         kfree(rpref);
 196                         return -ENOMEM;
 197                 }
 198         } else {
 199                 /* recycle the confirm slot */
 200                 BUG_ON(opt->dccpop_sc->dccpoc_val == NULL);
 201                 kfree(opt->dccpop_sc->dccpoc_val);
 202                 dccp_pr_debug("recycling confirm slot\n");
 203         }
 204         memset(opt->dccpop_sc, 0, sizeof(*opt->dccpop_sc));
 205
 206         opt->dccpop_sc->dccpoc_val = rpref;
 207         opt->dccpop_sc->dccpoc_len = rlen;
 208
 209         /* update the option on our side [we are about to send the confirm] */
 210         rc = dccp_feat_update(sk, opt->dccpop_type, opt->dccpop_feat, *res);
 211         if (rc) {
 212                 kfree(opt->dccpop_sc->dccpoc_val);
 213                 kfree(opt->dccpop_sc);
 214                 opt->dccpop_sc = NULL;
 215                 return rc;
 216         }
 217
 218         dccp_pr_debug("Will confirm %d\n", *rpref);
 219
 220         /* say we want to change to X but we just got a confirm X, suppress our
 221          * change
 222          */
 223         if (!opt->dccpop_conf) {
 224                 if (*opt->dccpop_val == *res)
 225                         opt->dccpop_conf = 1;
 226                 dccp_pr_debug("won't ask for change of same feature\n");
 227         }
 228
 229         return agree ? 0 : DCCP_FEAT_SP_NOAGREE; /* used for mandatory opts */
 230 }
 231
 232 static int dccp_feat_sp(struct sock *sk, u8 type, u8 feature, u8 *val, u8 len)
 233 {
 234         struct dccp_minisock *dmsk = dccp_msk(sk);
 235         struct dccp_opt_pend *opt;
 236         int rc = 1;
 237         u8 t;
 238
 239         /*
 240          * We received a CHANGE.  We gotta match it against our own preference
 241          * list.  If we got a CHANGE_R it means it's a change for us, so we need
 242          * to compare our CHANGE_L list.
 243          */
 244         if (type == DCCPO_CHANGE_L)
 245                 t = DCCPO_CHANGE_R;
 246         else
 247                 t = DCCPO_CHANGE_L;
 248
 249         /* find our preference list for this feature */
 250         list_for_each_entry(opt, &dmsk->dccpms_pending, dccpop_node) {
 251                 if (opt->dccpop_type != t || opt->dccpop_feat != feature)
 252                         continue;
 253
 254                 /* find the winner from the two preference lists */
 255                 rc = dccp_feat_reconcile(sk, opt, val, len);
 256                 break;
 257         }
 258
 259         /* We didn't deal with the change.  This can happen if we have no
 260          * preference list for the feature.  In fact, it just shouldn't
 261          * happen---if we understand a feature, we should have a preference list
 262          * with at least the default value.
 263          */
 264         BUG_ON(rc == 1);
 265
 266         return rc;
 267 }
 268
 269 static int dccp_feat_nn(struct sock *sk, u8 type, u8 feature, u8 *val, u8 len)
 270 {
 271         struct dccp_opt_pend *opt;
 272         struct dccp_minisock *dmsk = dccp_msk(sk);
 273         u8 *copy;
 274         int rc;
 275
 276         /* NN features must be Change L (sec. 6.3.2) */
 277         if (type != DCCPO_CHANGE_L) {
 278                 dccp_pr_debug("received %s for NN feature %d\n",
 279                                 dccp_feat_typename(type), feature);
 280                 return -EFAULT;
 281         }
 282
 283         /* XXX sanity check opt val */
 284
 285         /* copy option so we can confirm it */
 286         opt = kzalloc(sizeof(*opt), GFP_ATOMIC);
 287         if (opt == NULL)
 288                 return -ENOMEM;
 289
 290         copy = kmemdup(val, len, GFP_ATOMIC);
 291         if (copy == NULL) {
 292                 kfree(opt);
 293                 return -ENOMEM;
 294         }
 295
 296         opt->dccpop_type = DCCPO_CONFIRM_R; /* NN can only confirm R */
 297         opt->dccpop_feat = feature;
 298         opt->dccpop_val  = copy;
 299         opt->dccpop_len  = len;
 300
 301         /* change feature */
 302         rc = dccp_feat_update(sk, type, feature, *val);
 303         if (rc) {
 304                 kfree(opt->dccpop_val);
 305                 kfree(opt);
 306                 return rc;
 307         }
 308
 309         dccp_feat_debug(type, feature, *copy);
 310
 311         list_add_tail(&opt->dccpop_node, &dmsk->dccpms_conf);
 312
 313         return 0;
 314 }
 315
 316 static void dccp_feat_empty_confirm(struct dccp_minisock *dmsk,
 317                                     u8 type, u8 feature)
 318 {
 319         /* XXX check if other confirms for that are queued and recycle slot */
 320         struct dccp_opt_pend *opt = kzalloc(sizeof(*opt), GFP_ATOMIC);
 321
 322         if (opt == NULL) {
 323                 /* XXX what do we do?  Ignoring should be fine.  It's a change
 324                  * after all =P
 325                  */
 326                 return;
 327         }
 328
 329         switch (type) {
 330         case DCCPO_CHANGE_L:
 331                 opt->dccpop_type = DCCPO_CONFIRM_R;
 332                 break;
 333         case DCCPO_CHANGE_R:
 334                 opt->dccpop_type = DCCPO_CONFIRM_L;
 335                 break;
 336         default:
 337                 DCCP_WARN("invalid type %d\n", type);
 338                 kfree(opt);
 339                 return;
 340         }
 341         opt->dccpop_feat = feature;
 342         opt->dccpop_val  = NULL;
 343         opt->dccpop_len  = 0;
 344
 345         /* change feature */
 346         dccp_pr_debug("Empty %s(%d)\n", dccp_feat_typename(type), feature);
 347
 348         list_add_tail(&opt->dccpop_node, &dmsk->dccpms_conf);
 349 }
 350
 351 static void dccp_feat_flush_confirm(struct sock *sk)
 352 {
 353         struct dccp_minisock *dmsk = dccp_msk(sk);
 354         /* Check if there is anything to confirm in the first place */
 355         int yes = !list_empty(&dmsk->dccpms_conf);
 356
 357         if (!yes) {
 358                 struct dccp_opt_pend *opt;
 359
 360                 list_for_each_entry(opt, &dmsk->dccpms_pending, dccpop_node) {
 361                         if (opt->dccpop_conf) {
 362                                 yes = 1;
 363                                 break;
 364                         }
 365                 }
 366         }
 367
 368         if (!yes)
 369                 return;
 370
 371         /* OK there is something to confirm... */
 372         /* XXX check if packet is in flight?  Send delayed ack?? */
 373         if (sk->sk_state == DCCP_OPEN)
 374                 dccp_send_ack(sk);
 375 }
 376
 377 int dccp_feat_change_recv(struct sock *sk, u8 type, u8 feature, u8 *val, u8 len)
 378 {
 379         int rc;
 380
 381         dccp_feat_debug(type, feature, *val);
 382
 383         /* figure out if it's SP or NN feature */
 384         switch (feature) {
 385         /* deal with SP features */
 386         case DCCPF_CCID:
 387                 rc = dccp_feat_sp(sk, type, feature, val, len);
 388                 break;
 389
 390         /* deal with NN features */
 391         case DCCPF_ACK_RATIO:
 392                 rc = dccp_feat_nn(sk, type, feature, val, len);
 393                 break;
 394
 395         /* XXX implement other features */
 396         default:
 397                 dccp_pr_debug("UNIMPLEMENTED: not handling %s(%d, ...)\n",
 398                               dccp_feat_typename(type), feature);
 399                 rc = -EFAULT;
 400                 break;
 401         }
 402
 403         /* check if there were problems changing features */
 404         if (rc) {
 405                 /* If we don't agree on SP, we sent a confirm for old value.
 406                  * However we propagate rc to caller in case option was
 407                  * mandatory
 408                  */
 409                 if (rc != DCCP_FEAT_SP_NOAGREE)
 410                         dccp_feat_empty_confirm(dccp_msk(sk), type, feature);
 411         }
 412
 413         /* generate the confirm [if required] */
 414         dccp_feat_flush_confirm(sk);
 415
 416         return rc;
 417 }
 418
 419 EXPORT_SYMBOL_GPL(dccp_feat_change_recv);
 420
 421 int dccp_feat_confirm_recv(struct sock *sk, u8 type, u8 feature,
 422                            u8 *val, u8 len)
 423 {
 424         u8 t;
 425         struct dccp_opt_pend *opt;
 426         struct dccp_minisock *dmsk = dccp_msk(sk);
 427         int found = 0;
 428         int all_confirmed = 1;
 429
 430         dccp_feat_debug(type, feature, *val);
 431
 432         /* locate our change request */
 433         switch (type) {
 434         case DCCPO_CONFIRM_L: t = DCCPO_CHANGE_R; break;
 435         case DCCPO_CONFIRM_R: t = DCCPO_CHANGE_L; break;
 436         default:              DCCP_WARN("invalid type %d\n", type);
 437                               return 1;
 438
 439         }
 440         /* XXX sanity check feature value */
 441
 442         list_for_each_entry(opt, &dmsk->dccpms_pending, dccpop_node) {
 443                 if (!opt->dccpop_conf && opt->dccpop_type == t &&
 444                     opt->dccpop_feat == feature) {
 445                         found = 1;
 446                         dccp_pr_debug("feature %d found\n", opt->dccpop_feat);
 447
 448                         /* XXX do sanity check */
 449
 450                         opt->dccpop_conf = 1;
 451
 452                         /* We got a confirmation---change the option */
 453                         dccp_feat_update(sk, opt->dccpop_type,
 454                                          opt->dccpop_feat, *val);
 455
 456                         /* XXX check the return value of dccp_feat_update */
 457                         break;
 458                 }
 459
 460                 if (!opt->dccpop_conf)
 461                         all_confirmed = 0;
 462         }
 463
 464         /* fix re-transmit timer */
 465         /* XXX gotta make sure that no option negotiation occurs during
 466          * connection shutdown.  Consider that the CLOSEREQ is sent and timer is
 467          * on.  if all options are confirmed it might kill timer which should
 468          * remain alive until close is received.
 469          */
 470         if (all_confirmed) {
 471                 dccp_pr_debug("clear feat negotiation timer %p\n", sk);
 472                 inet_csk_clear_xmit_timer(sk, ICSK_TIME_RETRANS);
 473         }
 474
 475         if (!found)
 476                 dccp_pr_debug("%s(%d, ...) never requested\n",
 477                               dccp_feat_typename(type), feature);
 478         return 0;
 479 }
 480
 481 EXPORT_SYMBOL_GPL(dccp_feat_confirm_recv);
 482
 483 void dccp_feat_clean(struct dccp_minisock *dmsk)
 484 {
 485         struct dccp_opt_pend *opt, *next;
 486
 487         list_for_each_entry_safe(opt, next, &dmsk->dccpms_pending,
 488                                  dccpop_node) {
 489                 BUG_ON(opt->dccpop_val == NULL);
 490                 kfree(opt->dccpop_val);
 491
 492                 if (opt->dccpop_sc != NULL) {
 493                         BUG_ON(opt->dccpop_sc->dccpoc_val == NULL);
 494                         kfree(opt->dccpop_sc->dccpoc_val);
 495                         kfree(opt->dccpop_sc);
 496                 }
 497
 498                 kfree(opt);
 499         }
 500         INIT_LIST_HEAD(&dmsk->dccpms_pending);
 501
 502         list_for_each_entry_safe(opt, next, &dmsk->dccpms_conf, dccpop_node) {
 503                 BUG_ON(opt == NULL);
 504                 if (opt->dccpop_val != NULL)
 505                         kfree(opt->dccpop_val);
 506                 kfree(opt);
 507         }
 508         INIT_LIST_HEAD(&dmsk->dccpms_conf);
 509 }
 510
 511 EXPORT_SYMBOL_GPL(dccp_feat_clean);
 512
 513 /* this is to be called only when a listening sock creates its child.  It is
 514  * assumed by the function---the confirm is not duplicated, but rather it is
 515  * "passed on".
 516  */
 517 int dccp_feat_clone(struct sock *oldsk, struct sock *newsk)
 518 {
 519         struct dccp_minisock *olddmsk = dccp_msk(oldsk);
 520         struct dccp_minisock *newdmsk = dccp_msk(newsk);
 521         struct dccp_opt_pend *opt;
 522         int rc = 0;
 523
 524         INIT_LIST_HEAD(&newdmsk->dccpms_pending);
 525         INIT_LIST_HEAD(&newdmsk->dccpms_conf);
 526
 527         list_for_each_entry(opt, &olddmsk->dccpms_pending, dccpop_node) {
 528                 struct dccp_opt_pend *newopt;
 529                 /* copy the value of the option */
 530                 u8 *val = kmemdup(opt->dccpop_val, opt->dccpop_len, GFP_ATOMIC);
 531
 532                 if (val == NULL)
 533                         goto out_clean;
 534
 535                 newopt = kmemdup(opt, sizeof(*newopt), GFP_ATOMIC);
 536                 if (newopt == NULL) {
 537                         kfree(val);
 538                         goto out_clean;
 539                 }
 540
 541                 /* insert the option */
 542                 newopt->dccpop_val = val;
 543                 list_add_tail(&newopt->dccpop_node, &newdmsk->dccpms_pending);
 544
 545                 /* XXX what happens with backlogs and multiple connections at
 546                  * once...
 547                  */
 548                 /* the master socket no longer needs to worry about confirms */
 549                 opt->dccpop_sc = NULL; /* it's not a memleak---new socket has it */
 550
 551                 /* reset state for a new socket */
 552                 opt->dccpop_conf = 0;
 553         }
 554
 555         /* XXX not doing anything about the conf queue */
 556
 557 out:
 558         return rc;
 559
 560 out_clean:
 561         dccp_feat_clean(newdmsk);
 562         rc = -ENOMEM;
 563         goto out;
 564 }
 565
 566 EXPORT_SYMBOL_GPL(dccp_feat_clone);
 567
 568 static int __dccp_feat_init(struct dccp_minisock *dmsk, u8 type, u8 feat,
 569                             u8 *val, u8 len)
 570 {
 571         int rc = -ENOMEM;
 572         u8 *copy = kmemdup(val, len, GFP_KERNEL);
 573
 574         if (copy != NULL) {
 575                 rc = dccp_feat_change(dmsk, type, feat, copy, len, GFP_KERNEL);
 576                 if (rc)
 577                         kfree(copy);
 578         }
 579         return rc;
 580 }
 581
 582 int dccp_feat_init(struct dccp_minisock *dmsk)
 583 {
 584         int rc;
 585
 586         INIT_LIST_HEAD(&dmsk->dccpms_pending);
 587         INIT_LIST_HEAD(&dmsk->dccpms_conf);
 588
 589         /* CCID L */
 590         rc = __dccp_feat_init(dmsk, DCCPO_CHANGE_L, DCCPF_CCID,
 591                               &dmsk->dccpms_tx_ccid, 1);
 592         if (rc)
 593                 goto out;
 594
 595         /* CCID R */
 596         rc = __dccp_feat_init(dmsk, DCCPO_CHANGE_R, DCCPF_CCID,
 597                               &dmsk->dccpms_rx_ccid, 1);
 598         if (rc)
 599                 goto out;
 600
 601         /* Ack ratio */
 602         rc = __dccp_feat_init(dmsk, DCCPO_CHANGE_L, DCCPF_ACK_RATIO,
 603                               &dmsk->dccpms_ack_ratio, 1);
 604 out:
 605         return rc;
 606 }
 607
 608 EXPORT_SYMBOL_GPL(dccp_feat_init);
 609
 610 #ifdef CONFIG_IP_DCCP_DEBUG
 611 const char *dccp_feat_typename(const u8 type)
 612 {
 613         switch(type) {
 614         case DCCPO_CHANGE_L:  return("ChangeL");
 615         case DCCPO_CONFIRM_L: return("ConfirmL");
 616         case DCCPO_CHANGE_R:  return("ChangeR");
 617         case DCCPO_CONFIRM_R: return("ConfirmR");
 618         /* the following case must not appear in feature negotation  */
 619         default:              dccp_pr_debug("unknown type %d [BUG!]\n", type);
 620         }
 621         return NULL;
 622 }
 623
 624 EXPORT_SYMBOL_GPL(dccp_feat_typename);
 625
 626 const char *dccp_feat_name(const u8 feat)
 627 {
 628         static const char *feature_names[] = {
 629                 [DCCPF_RESERVED]        = "Reserved",
 630                 [DCCPF_CCID]            = "CCID",
 631                 [DCCPF_SHORT_SEQNOS]    = "Allow Short Seqnos",
 632                 [DCCPF_SEQUENCE_WINDOW] = "Sequence Window",
 633                 [DCCPF_ECN_INCAPABLE]   = "ECN Incapable",
 634                 [DCCPF_ACK_RATIO]       = "Ack Ratio",
 635                 [DCCPF_SEND_ACK_VECTOR] = "Send ACK Vector",
 636                 [DCCPF_SEND_NDP_COUNT]  = "Send NDP Count",
 637                 [DCCPF_MIN_CSUM_COVER]  = "Min. Csum Coverage",
 638                 [DCCPF_DATA_CHECKSUM]   = "Send Data Checksum",
 639         };
 640         if (feat >= DCCPF_MIN_CCID_SPECIFIC)
 641                 return "CCID-specific";
 642
 643         if (dccp_feat_is_reserved(feat))
 644                 return feature_names[DCCPF_RESERVED];
 645
 646         return feature_names[feat];
 647 }
 648
 649 EXPORT_SYMBOL_GPL(dccp_feat_name);
 650 #endif /* CONFIG_IP_DCCP_DEBUG */