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