err.no Git - linux-2.6/blob - net/dccp/options.c

   1 /*
   2  *  net/dccp/options.c
   3  *
   4  *  An implementation of the DCCP protocol
   5  *  Copyright (c) 2005 Aristeu Sergio Rozanski Filho <aris@cathedrallabs.org>
   6  *  Copyright (c) 2005 Arnaldo Carvalho de Melo <acme@ghostprotocols.net>
   7  *  Copyright (c) 2005 Ian McDonald <ian.mcdonald@jandi.co.nz>
   8  *
   9  *      This program is free software; you can redistribute it and/or
  10  *      modify it under the terms of the GNU General Public License
  11  *      as published by the Free Software Foundation; either version
  12  *      2 of the License, or (at your option) any later version.
  13  */
  14 #include <linux/dccp.h>
  15 #include <linux/module.h>
  16 #include <linux/types.h>
  17 #include <asm/unaligned.h>
  18 #include <linux/kernel.h>
  19 #include <linux/skbuff.h>
  20
  21 #include "ackvec.h"
  22 #include "ccid.h"
  23 #include "dccp.h"
  24 #include "feat.h"
  25
  26 int sysctl_dccp_feat_sequence_window = DCCPF_INITIAL_SEQUENCE_WINDOW;
  27 int sysctl_dccp_feat_rx_ccid          = DCCPF_INITIAL_CCID;
  28 int sysctl_dccp_feat_tx_ccid          = DCCPF_INITIAL_CCID;
  29 int sysctl_dccp_feat_ack_ratio        = DCCPF_INITIAL_ACK_RATIO;
  30 int sysctl_dccp_feat_send_ack_vector = DCCPF_INITIAL_SEND_ACK_VECTOR;
  31 int sysctl_dccp_feat_send_ndp_count  = DCCPF_INITIAL_SEND_NDP_COUNT;
  32
  33 static u32 dccp_decode_value_var(const unsigned char *bf, const u8 len)
  34 {
  35         u32 value = 0;
  36
  37         if (len > 3)
  38                 value += *bf++ << 24;
  39         if (len > 2)
  40                 value += *bf++ << 16;
  41         if (len > 1)
  42                 value += *bf++ << 8;
  43         if (len > 0)
  44                 value += *bf;
  45
  46         return value;
  47 }
  48
  49 /**
  50  * dccp_parse_options  -  Parse DCCP options present in @skb
  51  * @sk: client|server|listening dccp socket (when @dreq != NULL)
  52  * @dreq: request socket to use during connection setup, or NULL
  53  */
  54 int dccp_parse_options(struct sock *sk, struct dccp_request_sock *dreq,
  55                        struct sk_buff *skb)
  56 {
  57         struct dccp_sock *dp = dccp_sk(sk);
  58         const struct dccp_hdr *dh = dccp_hdr(skb);
  59         const u8 pkt_type = DCCP_SKB_CB(skb)->dccpd_type;
  60         u64 ackno = DCCP_SKB_CB(skb)->dccpd_ack_seq;
  61         unsigned char *options = (unsigned char *)dh + dccp_hdr_len(skb);
  62         unsigned char *opt_ptr = options;
  63         const unsigned char *opt_end = (unsigned char *)dh +
  64                                         (dh->dccph_doff * 4);
  65         struct dccp_options_received *opt_recv = &dp->dccps_options_received;
  66         unsigned char opt, len;
  67         unsigned char *value;
  68         u32 elapsed_time;
  69         __be32 opt_val;
  70         int rc;
  71         int mandatory = 0;
  72
  73         memset(opt_recv, 0, sizeof(*opt_recv));
  74
  75         opt = len = 0;
  76         while (opt_ptr != opt_end) {
  77                 opt   = *opt_ptr++;
  78                 len   = 0;
  79                 value = NULL;
  80
  81                 /* Check if this isn't a single byte option */
  82                 if (opt > DCCPO_MAX_RESERVED) {
  83                         if (opt_ptr == opt_end)
  84                                 goto out_invalid_option;
  85
  86                         len = *opt_ptr++;
  87                         if (len < 3)
  88                                 goto out_invalid_option;
  89                         /*
  90                          * Remove the type and len fields, leaving
  91                          * just the value size
  92                          */
  93                         len     -= 2;
  94                         value   = opt_ptr;
  95                         opt_ptr += len;
  96
  97                         if (opt_ptr > opt_end)
  98                                 goto out_invalid_option;
  99                 }
 100
 101                 /*
 102                  * CCID-Specific Options (from RFC 4340, sec. 10.3):
 103                  *
 104                  * Option numbers 128 through 191 are for options sent from the
 105                  * HC-Sender to the HC-Receiver; option numbers 192 through 255
 106                  * are for options sent from the HC-Receiver to the HC-Sender.
 107                  *
 108                  * CCID-specific options are ignored during connection setup, as
 109                  * negotiation may still be in progress (see RFC 4340, 10.3).
 110                  *
 111                  */
 112                 if (dreq != NULL && opt >= 128)
 113                         goto ignore_option;
 114
 115                 switch (opt) {
 116                 case DCCPO_PADDING:
 117                         break;
 118                 case DCCPO_MANDATORY:
 119                         if (mandatory)
 120                                 goto out_invalid_option;
 121                         if (pkt_type != DCCP_PKT_DATA)
 122                                 mandatory = 1;
 123                         break;
 124                 case DCCPO_NDP_COUNT:
 125                         if (len > 3)
 126                                 goto out_invalid_option;
 127
 128                         opt_recv->dccpor_ndp = dccp_decode_value_var(value, len);
 129                         dccp_pr_debug("%s rx opt: NDP count=%d\n", dccp_role(sk),
 130                                       opt_recv->dccpor_ndp);
 131                         break;
 132                 case DCCPO_CHANGE_L:
 133                         /* fall through */
 134                 case DCCPO_CHANGE_R:
 135                         if (len < 2)
 136                                 goto out_invalid_option;
 137                         rc = dccp_feat_change_recv(sk, opt, *value, value + 1,
 138                                                    len - 1);
 139                         /*
 140                          * When there is a change error, change_recv is
 141                          * responsible for dealing with it.  i.e. reply with an
 142                          * empty confirm.
 143                          * If the change was mandatory, then we need to die.
 144                          */
 145                         if (rc && mandatory)
 146                                 goto out_invalid_option;
 147                         break;
 148                 case DCCPO_CONFIRM_L:
 149                         /* fall through */
 150                 case DCCPO_CONFIRM_R:
 151                         if (len < 2)
 152                                 goto out_invalid_option;
 153                         if (dccp_feat_confirm_recv(sk, opt, *value,
 154                                                    value + 1, len - 1))
 155                                 goto out_invalid_option;
 156                         break;
 157                 case DCCPO_ACK_VECTOR_0:
 158                 case DCCPO_ACK_VECTOR_1:
 159                         if (dccp_packet_without_ack(skb))   /* RFC 4340, 11.4 */
 160                                 break;
 161
 162                         if (dccp_msk(sk)->dccpms_send_ack_vector &&
 163                             dccp_ackvec_parse(sk, skb, &ackno, opt, value, len))
 164                                 goto out_invalid_option;
 165                         break;
 166                 case DCCPO_TIMESTAMP:
 167                         if (len != 4)
 168                                 goto out_invalid_option;
 169                         /*
 170                          * RFC 4340 13.1: "The precise time corresponding to
 171                          * Timestamp Value zero is not specified". We use
 172                          * zero to indicate absence of a meaningful timestamp.
 173                          */
 174                         opt_val = get_unaligned((__be32 *)value);
 175                         if (unlikely(opt_val == 0)) {
 176                                 DCCP_WARN("Timestamp with zero value\n");
 177                                 break;
 178                         }
 179
 180                         if (dreq != NULL) {
 181                                 dreq->dreq_timestamp_echo = ntohl(opt_val);
 182                                 dreq->dreq_timestamp_time = dccp_timestamp();
 183                         } else {
 184                                 opt_recv->dccpor_timestamp =
 185                                         dp->dccps_timestamp_echo = ntohl(opt_val);
 186                                 dp->dccps_timestamp_time = dccp_timestamp();
 187                         }
 188                         dccp_pr_debug("%s rx opt: TIMESTAMP=%u, ackno=%llu\n",
 189                                       dccp_role(sk), ntohl(opt_val),
 190                                       (unsigned long long)
 191                                       DCCP_SKB_CB(skb)->dccpd_ack_seq);
 192                         break;
 193                 case DCCPO_TIMESTAMP_ECHO:
 194                         if (len != 4 && len != 6 && len != 8)
 195                                 goto out_invalid_option;
 196
 197                         opt_val = get_unaligned((__be32 *)value);
 198                         opt_recv->dccpor_timestamp_echo = ntohl(opt_val);
 199
 200                         dccp_pr_debug("%s rx opt: TIMESTAMP_ECHO=%u, len=%d, "
 201                                       "ackno=%llu", dccp_role(sk),
 202                                       opt_recv->dccpor_timestamp_echo,
 203                                       len + 2,
 204                                       (unsigned long long)
 205                                       DCCP_SKB_CB(skb)->dccpd_ack_seq);
 206
 207                         value += 4;
 208
 209                         if (len == 4) {         /* no elapsed time included */
 210                                 dccp_pr_debug_cat("\n");
 211                                 break;
 212                         }
 213
 214                         if (len == 6) {         /* 2-byte elapsed time */
 215                                 __be16 opt_val2 = get_unaligned((__be16 *)value);
 216                                 elapsed_time = ntohs(opt_val2);
 217                         } else {                /* 4-byte elapsed time */
 218                                 opt_val = get_unaligned((__be32 *)value);
 219                                 elapsed_time = ntohl(opt_val);
 220                         }
 221
 222                         dccp_pr_debug_cat(", ELAPSED_TIME=%u\n", elapsed_time);
 223
 224                         /* Give precedence to the biggest ELAPSED_TIME */
 225                         if (elapsed_time > opt_recv->dccpor_elapsed_time)
 226                                 opt_recv->dccpor_elapsed_time = elapsed_time;
 227                         break;
 228                 case DCCPO_ELAPSED_TIME:
 229                         if (dccp_packet_without_ack(skb))   /* RFC 4340, 13.2 */
 230                                 break;
 231
 232                         if (len == 2) {
 233                                 __be16 opt_val2 = get_unaligned((__be16 *)value);
 234                                 elapsed_time = ntohs(opt_val2);
 235                         } else if (len == 4) {
 236                                 opt_val = get_unaligned((__be32 *)value);
 237                                 elapsed_time = ntohl(opt_val);
 238                         } else {
 239                                 goto out_invalid_option;
 240                         }
 241
 242                         if (elapsed_time > opt_recv->dccpor_elapsed_time)
 243                                 opt_recv->dccpor_elapsed_time = elapsed_time;
 244
 245                         dccp_pr_debug("%s rx opt: ELAPSED_TIME=%d\n",
 246                                       dccp_role(sk), elapsed_time);
 247                         break;
 248                 case 128 ... 191: {
 249                         const u16 idx = value - options;
 250
 251                         if (ccid_hc_rx_parse_options(dp->dccps_hc_rx_ccid, sk,
 252                                                      opt, len, idx,
 253                                                      value) != 0)
 254                                 goto out_invalid_option;
 255                 }
 256                         break;
 257                 case 192 ... 255: {
 258                         const u16 idx = value - options;
 259
 260                         if (ccid_hc_tx_parse_options(dp->dccps_hc_tx_ccid, sk,
 261                                                      opt, len, idx,
 262                                                      value) != 0)
 263                                 goto out_invalid_option;
 264                 }
 265                         break;
 266                 default:
 267                         DCCP_CRIT("DCCP(%p): option %d(len=%d) not "
 268                                   "implemented, ignoring", sk, opt, len);
 269                         break;
 270                 }
 271 ignore_option:
 272                 if (opt != DCCPO_MANDATORY)
 273                         mandatory = 0;
 274         }
 275
 276         /* mandatory was the last byte in option list -> reset connection */
 277         if (mandatory)
 278                 goto out_invalid_option;
 279
 280         return 0;
 281
 282 out_invalid_option:
 283         DCCP_INC_STATS_BH(DCCP_MIB_INVALIDOPT);
 284         DCCP_SKB_CB(skb)->dccpd_reset_code = DCCP_RESET_CODE_OPTION_ERROR;
 285         DCCP_WARN("DCCP(%p): invalid option %d, len=%d", sk, opt, len);
 286         return -1;
 287 }
 288
 289 EXPORT_SYMBOL_GPL(dccp_parse_options);
 290
 291 static void dccp_encode_value_var(const u32 value, unsigned char *to,
 292                                   const unsigned int len)
 293 {
 294         if (len > 3)
 295                 *to++ = (value & 0xFF000000) >> 24;
 296         if (len > 2)
 297                 *to++ = (value & 0xFF0000) >> 16;
 298         if (len > 1)
 299                 *to++ = (value & 0xFF00) >> 8;
 300         if (len > 0)
 301                 *to++ = (value & 0xFF);
 302 }
 303
 304 static inline int dccp_ndp_len(const int ndp)
 305 {
 306         return likely(ndp <= 0xFF) ? 1 : ndp <= 0xFFFF ? 2 : 3;
 307 }
 308
 309 int dccp_insert_option(struct sock *sk, struct sk_buff *skb,
 310                         const unsigned char option,
 311                         const void *value, const unsigned char len)
 312 {
 313         unsigned char *to;
 314
 315         if (DCCP_SKB_CB(skb)->dccpd_opt_len + len + 2 > DCCP_MAX_OPT_LEN)
 316                 return -1;
 317
 318         DCCP_SKB_CB(skb)->dccpd_opt_len += len + 2;
 319
 320         to    = skb_push(skb, len + 2);
 321         *to++ = option;
 322         *to++ = len + 2;
 323
 324         memcpy(to, value, len);
 325         return 0;
 326 }
 327
 328 EXPORT_SYMBOL_GPL(dccp_insert_option);
 329
 330 static int dccp_insert_option_ndp(struct sock *sk, struct sk_buff *skb)
 331 {
 332         struct dccp_sock *dp = dccp_sk(sk);
 333         int ndp = dp->dccps_ndp_count;
 334
 335         if (dccp_non_data_packet(skb))
 336                 ++dp->dccps_ndp_count;
 337         else
 338                 dp->dccps_ndp_count = 0;
 339
 340         if (ndp > 0) {
 341                 unsigned char *ptr;
 342                 const int ndp_len = dccp_ndp_len(ndp);
 343                 const int len = ndp_len + 2;
 344
 345                 if (DCCP_SKB_CB(skb)->dccpd_opt_len + len > DCCP_MAX_OPT_LEN)
 346                         return -1;
 347
 348                 DCCP_SKB_CB(skb)->dccpd_opt_len += len;
 349
 350                 ptr = skb_push(skb, len);
 351                 *ptr++ = DCCPO_NDP_COUNT;
 352                 *ptr++ = len;
 353                 dccp_encode_value_var(ndp, ptr, ndp_len);
 354         }
 355
 356         return 0;
 357 }
 358
 359 static inline int dccp_elapsed_time_len(const u32 elapsed_time)
 360 {
 361         return elapsed_time == 0 ? 0 : elapsed_time <= 0xFFFF ? 2 : 4;
 362 }
 363
 364 int dccp_insert_option_elapsed_time(struct sock *sk, struct sk_buff *skb,
 365                                     u32 elapsed_time)
 366 {
 367         const int elapsed_time_len = dccp_elapsed_time_len(elapsed_time);
 368         const int len = 2 + elapsed_time_len;
 369         unsigned char *to;
 370
 371         if (elapsed_time_len == 0)
 372                 return 0;
 373
 374         if (DCCP_SKB_CB(skb)->dccpd_opt_len + len > DCCP_MAX_OPT_LEN)
 375                 return -1;
 376
 377         DCCP_SKB_CB(skb)->dccpd_opt_len += len;
 378
 379         to    = skb_push(skb, len);
 380         *to++ = DCCPO_ELAPSED_TIME;
 381         *to++ = len;
 382
 383         if (elapsed_time_len == 2) {
 384                 const __be16 var16 = htons((u16)elapsed_time);
 385                 memcpy(to, &var16, 2);
 386         } else {
 387                 const __be32 var32 = htonl(elapsed_time);
 388                 memcpy(to, &var32, 4);
 389         }
 390
 391         return 0;
 392 }
 393
 394 EXPORT_SYMBOL_GPL(dccp_insert_option_elapsed_time);
 395
 396 int dccp_insert_option_timestamp(struct sock *sk, struct sk_buff *skb)
 397 {
 398         __be32 now = htonl(dccp_timestamp());
 399         /* yes this will overflow but that is the point as we want a
 400          * 10 usec 32 bit timer which mean it wraps every 11.9 hours */
 401
 402         return dccp_insert_option(sk, skb, DCCPO_TIMESTAMP, &now, sizeof(now));
 403 }
 404
 405 EXPORT_SYMBOL_GPL(dccp_insert_option_timestamp);
 406
 407 static int dccp_insert_option_timestamp_echo(struct dccp_sock *dp,
 408                                              struct dccp_request_sock *dreq,
 409                                              struct sk_buff *skb)
 410 {
 411         __be32 tstamp_echo;
 412         unsigned char *to;
 413         u32 elapsed_time, elapsed_time_len, len;
 414
 415         if (dreq != NULL) {
 416                 elapsed_time = dccp_timestamp() - dreq->dreq_timestamp_time;
 417                 tstamp_echo  = htonl(dreq->dreq_timestamp_echo);
 418                 dreq->dreq_timestamp_echo = 0;
 419         } else {
 420                 elapsed_time = dccp_timestamp() - dp->dccps_timestamp_time;
 421                 tstamp_echo  = htonl(dp->dccps_timestamp_echo);
 422                 dp->dccps_timestamp_echo = 0;
 423         }
 424
 425         elapsed_time_len = dccp_elapsed_time_len(elapsed_time);
 426         len = 6 + elapsed_time_len;
 427
 428         if (DCCP_SKB_CB(skb)->dccpd_opt_len + len > DCCP_MAX_OPT_LEN)
 429                 return -1;
 430
 431         DCCP_SKB_CB(skb)->dccpd_opt_len += len;
 432
 433         to    = skb_push(skb, len);
 434         *to++ = DCCPO_TIMESTAMP_ECHO;
 435         *to++ = len;
 436
 437         memcpy(to, &tstamp_echo, 4);
 438         to += 4;
 439
 440         if (elapsed_time_len == 2) {
 441                 const __be16 var16 = htons((u16)elapsed_time);
 442                 memcpy(to, &var16, 2);
 443         } else if (elapsed_time_len == 4) {
 444                 const __be32 var32 = htonl(elapsed_time);
 445                 memcpy(to, &var32, 4);
 446         }
 447
 448         return 0;
 449 }
 450
 451 static int dccp_insert_feat_opt(struct sk_buff *skb, u8 type, u8 feat,
 452                                 u8 *val, u8 len)
 453 {
 454         u8 *to;
 455
 456         if (DCCP_SKB_CB(skb)->dccpd_opt_len + len + 3 > DCCP_MAX_OPT_LEN) {
 457                 DCCP_WARN("packet too small for feature %d option!\n", feat);
 458                 return -1;
 459         }
 460
 461         DCCP_SKB_CB(skb)->dccpd_opt_len += len + 3;
 462
 463         to    = skb_push(skb, len + 3);
 464         *to++ = type;
 465         *to++ = len + 3;
 466         *to++ = feat;
 467
 468         if (len)
 469                 memcpy(to, val, len);
 470
 471         dccp_pr_debug("%s(%s (%d), ...), length %d\n",
 472                       dccp_feat_typename(type),
 473                       dccp_feat_name(feat), feat, len);
 474         return 0;
 475 }
 476
 477 static int dccp_insert_options_feat(struct sock *sk, struct sk_buff *skb)
 478 {
 479         struct dccp_sock *dp = dccp_sk(sk);
 480         struct dccp_minisock *dmsk = dccp_msk(sk);
 481         struct dccp_opt_pend *opt, *next;
 482         int change = 0;
 483
 484         /* confirm any options [NN opts] */
 485         list_for_each_entry_safe(opt, next, &dmsk->dccpms_conf, dccpop_node) {
 486                 dccp_insert_feat_opt(skb, opt->dccpop_type,
 487                                      opt->dccpop_feat, opt->dccpop_val,
 488                                      opt->dccpop_len);
 489                 /* fear empty confirms */
 490                 if (opt->dccpop_val)
 491                         kfree(opt->dccpop_val);
 492                 kfree(opt);
 493         }
 494         INIT_LIST_HEAD(&dmsk->dccpms_conf);
 495
 496         /* see which features we need to send */
 497         list_for_each_entry(opt, &dmsk->dccpms_pending, dccpop_node) {
 498                 /* see if we need to send any confirm */
 499                 if (opt->dccpop_sc) {
 500                         dccp_insert_feat_opt(skb, opt->dccpop_type + 1,
 501                                              opt->dccpop_feat,
 502                                              opt->dccpop_sc->dccpoc_val,
 503                                              opt->dccpop_sc->dccpoc_len);
 504
 505                         BUG_ON(!opt->dccpop_sc->dccpoc_val);
 506                         kfree(opt->dccpop_sc->dccpoc_val);
 507                         kfree(opt->dccpop_sc);
 508                         opt->dccpop_sc = NULL;
 509                 }
 510
 511                 /* any option not confirmed, re-send it */
 512                 if (!opt->dccpop_conf) {
 513                         dccp_insert_feat_opt(skb, opt->dccpop_type,
 514                                              opt->dccpop_feat, opt->dccpop_val,
 515                                              opt->dccpop_len);
 516                         change++;
 517                 }
 518         }
 519
 520         /* Retransmit timer.
 521          * If this is the master listening sock, we don't set a timer on it.  It
 522          * should be fine because if the dude doesn't receive our RESPONSE
 523          * [which will contain the CHANGE] he will send another REQUEST which
 524          * will "retrnasmit" the change.
 525          */
 526         if (change && dp->dccps_role != DCCP_ROLE_LISTEN) {
 527                 dccp_pr_debug("reset feat negotiation timer %p\n", sk);
 528
 529                 /* XXX don't reset the timer on re-transmissions.  I.e. reset it
 530                  * only when sending new stuff i guess.  Currently the timer
 531                  * never backs off because on re-transmission it just resets it!
 532                  */
 533                 inet_csk_reset_xmit_timer(sk, ICSK_TIME_RETRANS,
 534                                           inet_csk(sk)->icsk_rto, DCCP_RTO_MAX);
 535         }
 536
 537         return 0;
 538 }
 539
 540 int dccp_insert_options(struct sock *sk, struct sk_buff *skb)
 541 {
 542         struct dccp_sock *dp = dccp_sk(sk);
 543         struct dccp_minisock *dmsk = dccp_msk(sk);
 544
 545         DCCP_SKB_CB(skb)->dccpd_opt_len = 0;
 546
 547         if (dmsk->dccpms_send_ndp_count &&
 548             dccp_insert_option_ndp(sk, skb))
 549                 return -1;
 550
 551         if (!dccp_packet_without_ack(skb)) {
 552                 if (dmsk->dccpms_send_ack_vector &&
 553                     dccp_ackvec_pending(dp->dccps_hc_rx_ackvec) &&
 554                     dccp_insert_option_ackvec(sk, skb))
 555                         return -1;
 556         }
 557
 558         if (dp->dccps_hc_rx_insert_options) {
 559                 if (ccid_hc_rx_insert_options(dp->dccps_hc_rx_ccid, sk, skb))
 560                         return -1;
 561                 dp->dccps_hc_rx_insert_options = 0;
 562         }
 563
 564         /* Feature negotiation */
 565         /* Data packets can't do feat negotiation */
 566         if (DCCP_SKB_CB(skb)->dccpd_type != DCCP_PKT_DATA &&
 567             DCCP_SKB_CB(skb)->dccpd_type != DCCP_PKT_DATAACK &&
 568             dccp_insert_options_feat(sk, skb))
 569                 return -1;
 570
 571         /*
 572          * Obtain RTT sample from Request/Response exchange.
 573          * This is currently used in CCID 3 initialisation.
 574          */
 575         if (DCCP_SKB_CB(skb)->dccpd_type == DCCP_PKT_REQUEST &&
 576             dccp_insert_option_timestamp(sk, skb))
 577                 return -1;
 578
 579         if (dp->dccps_timestamp_echo != 0 &&
 580             dccp_insert_option_timestamp_echo(dp, NULL, skb))
 581                 return -1;
 582
 583         /* XXX: insert other options when appropriate */
 584
 585         if (DCCP_SKB_CB(skb)->dccpd_opt_len != 0) {
 586                 /* The length of all options has to be a multiple of 4 */
 587                 int padding = DCCP_SKB_CB(skb)->dccpd_opt_len % 4;
 588
 589                 if (padding != 0) {
 590                         padding = 4 - padding;
 591                         memset(skb_push(skb, padding), 0, padding);
 592                         DCCP_SKB_CB(skb)->dccpd_opt_len += padding;
 593                 }
 594         }
 595
 596         return 0;
 597 }