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   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                  * The same applies to Ack Vectors, as these depend on the CCID.
 111                  *
 112                  */
 113                 if (dreq != NULL && (opt >= 128 ||
 114                     opt == DCCPO_ACK_VECTOR_0 || opt == DCCPO_ACK_VECTOR_1))
 115                         goto ignore_option;
 116
 117                 switch (opt) {
 118                 case DCCPO_PADDING:
 119                         break;
 120                 case DCCPO_MANDATORY:
 121                         if (mandatory)
 122                                 goto out_invalid_option;
 123                         if (pkt_type != DCCP_PKT_DATA)
 124                                 mandatory = 1;
 125                         break;
 126                 case DCCPO_NDP_COUNT:
 127                         if (len > 3)
 128                                 goto out_invalid_option;
 129
 130                         opt_recv->dccpor_ndp = dccp_decode_value_var(value, len);
 131                         dccp_pr_debug("%s rx opt: NDP count=%d\n", dccp_role(sk),
 132                                       opt_recv->dccpor_ndp);
 133                         break;
 134                 case DCCPO_CHANGE_L:
 135                         /* fall through */
 136                 case DCCPO_CHANGE_R:
 137                         if (pkt_type == DCCP_PKT_DATA)
 138                                 break;
 139                         if (len < 2)
 140                                 goto out_invalid_option;
 141                         rc = dccp_feat_change_recv(sk, opt, *value, value + 1,
 142                                                    len - 1);
 143                         /*
 144                          * When there is a change error, change_recv is
 145                          * responsible for dealing with it.  i.e. reply with an
 146                          * empty confirm.
 147                          * If the change was mandatory, then we need to die.
 148                          */
 149                         if (rc && mandatory)
 150                                 goto out_invalid_option;
 151                         break;
 152                 case DCCPO_CONFIRM_L:
 153                         /* fall through */
 154                 case DCCPO_CONFIRM_R:
 155                         if (pkt_type == DCCP_PKT_DATA)
 156                                 break;
 157                         if (len < 2)    /* FIXME this disallows empty confirm */
 158                                 goto out_invalid_option;
 159                         if (dccp_feat_confirm_recv(sk, opt, *value,
 160                                                    value + 1, len - 1))
 161                                 goto out_invalid_option;
 162                         break;
 163                 case DCCPO_ACK_VECTOR_0:
 164                 case DCCPO_ACK_VECTOR_1:
 165                         if (dccp_packet_without_ack(skb))   /* RFC 4340, 11.4 */
 166                                 break;
 167
 168                         if (dccp_msk(sk)->dccpms_send_ack_vector &&
 169                             dccp_ackvec_parse(sk, skb, &ackno, opt, value, len))
 170                                 goto out_invalid_option;
 171                         break;
 172                 case DCCPO_TIMESTAMP:
 173                         if (len != 4)
 174                                 goto out_invalid_option;
 175                         /*
 176                          * RFC 4340 13.1: "The precise time corresponding to
 177                          * Timestamp Value zero is not specified". We use
 178                          * zero to indicate absence of a meaningful timestamp.
 179                          */
 180                         opt_val = get_unaligned((__be32 *)value);
 181                         if (unlikely(opt_val == 0)) {
 182                                 DCCP_WARN("Timestamp with zero value\n");
 183                                 break;
 184                         }
 185
 186                         if (dreq != NULL) {
 187                                 dreq->dreq_timestamp_echo = ntohl(opt_val);
 188                                 dreq->dreq_timestamp_time = dccp_timestamp();
 189                         } else {
 190                                 opt_recv->dccpor_timestamp =
 191                                         dp->dccps_timestamp_echo = ntohl(opt_val);
 192                                 dp->dccps_timestamp_time = dccp_timestamp();
 193                         }
 194                         dccp_pr_debug("%s rx opt: TIMESTAMP=%u, ackno=%llu\n",
 195                                       dccp_role(sk), ntohl(opt_val),
 196                                       (unsigned long long)
 197                                       DCCP_SKB_CB(skb)->dccpd_ack_seq);
 198                         break;
 199                 case DCCPO_TIMESTAMP_ECHO:
 200                         if (len != 4 && len != 6 && len != 8)
 201                                 goto out_invalid_option;
 202
 203                         opt_val = get_unaligned((__be32 *)value);
 204                         opt_recv->dccpor_timestamp_echo = ntohl(opt_val);
 205
 206                         dccp_pr_debug("%s rx opt: TIMESTAMP_ECHO=%u, len=%d, "
 207                                       "ackno=%llu", dccp_role(sk),
 208                                       opt_recv->dccpor_timestamp_echo,
 209                                       len + 2,
 210                                       (unsigned long long)
 211                                       DCCP_SKB_CB(skb)->dccpd_ack_seq);
 212
 213                         value += 4;
 214
 215                         if (len == 4) {         /* no elapsed time included */
 216                                 dccp_pr_debug_cat("\n");
 217                                 break;
 218                         }
 219
 220                         if (len == 6) {         /* 2-byte elapsed time */
 221                                 __be16 opt_val2 = get_unaligned((__be16 *)value);
 222                                 elapsed_time = ntohs(opt_val2);
 223                         } else {                /* 4-byte elapsed time */
 224                                 opt_val = get_unaligned((__be32 *)value);
 225                                 elapsed_time = ntohl(opt_val);
 226                         }
 227
 228                         dccp_pr_debug_cat(", ELAPSED_TIME=%u\n", elapsed_time);
 229
 230                         /* Give precedence to the biggest ELAPSED_TIME */
 231                         if (elapsed_time > opt_recv->dccpor_elapsed_time)
 232                                 opt_recv->dccpor_elapsed_time = elapsed_time;
 233                         break;
 234                 case DCCPO_ELAPSED_TIME:
 235                         if (dccp_packet_without_ack(skb))   /* RFC 4340, 13.2 */
 236                                 break;
 237
 238                         if (len == 2) {
 239                                 __be16 opt_val2 = get_unaligned((__be16 *)value);
 240                                 elapsed_time = ntohs(opt_val2);
 241                         } else if (len == 4) {
 242                                 opt_val = get_unaligned((__be32 *)value);
 243                                 elapsed_time = ntohl(opt_val);
 244                         } else {
 245                                 goto out_invalid_option;
 246                         }
 247
 248                         if (elapsed_time > opt_recv->dccpor_elapsed_time)
 249                                 opt_recv->dccpor_elapsed_time = elapsed_time;
 250
 251                         dccp_pr_debug("%s rx opt: ELAPSED_TIME=%d\n",
 252                                       dccp_role(sk), elapsed_time);
 253                         break;
 254                 case 128 ... 191: {
 255                         const u16 idx = value - options;
 256
 257                         if (ccid_hc_rx_parse_options(dp->dccps_hc_rx_ccid, sk,
 258                                                      opt, len, idx,
 259                                                      value) != 0)
 260                                 goto out_invalid_option;
 261                 }
 262                         break;
 263                 case 192 ... 255: {
 264                         const u16 idx = value - options;
 265
 266                         if (ccid_hc_tx_parse_options(dp->dccps_hc_tx_ccid, sk,
 267                                                      opt, len, idx,
 268                                                      value) != 0)
 269                                 goto out_invalid_option;
 270                 }
 271                         break;
 272                 default:
 273                         DCCP_CRIT("DCCP(%p): option %d(len=%d) not "
 274                                   "implemented, ignoring", sk, opt, len);
 275                         break;
 276                 }
 277 ignore_option:
 278                 if (opt != DCCPO_MANDATORY)
 279                         mandatory = 0;
 280         }
 281
 282         /* mandatory was the last byte in option list -> reset connection */
 283         if (mandatory)
 284                 goto out_invalid_option;
 285
 286         return 0;
 287
 288 out_invalid_option:
 289         DCCP_INC_STATS_BH(DCCP_MIB_INVALIDOPT);
 290         DCCP_SKB_CB(skb)->dccpd_reset_code = DCCP_RESET_CODE_OPTION_ERROR;
 291         DCCP_WARN("DCCP(%p): invalid option %d, len=%d", sk, opt, len);
 292         return -1;
 293 }
 294
 295 EXPORT_SYMBOL_GPL(dccp_parse_options);
 296
 297 static void dccp_encode_value_var(const u32 value, unsigned char *to,
 298                                   const unsigned int len)
 299 {
 300         if (len > 3)
 301                 *to++ = (value & 0xFF000000) >> 24;
 302         if (len > 2)
 303                 *to++ = (value & 0xFF0000) >> 16;
 304         if (len > 1)
 305                 *to++ = (value & 0xFF00) >> 8;
 306         if (len > 0)
 307                 *to++ = (value & 0xFF);
 308 }
 309
 310 static inline int dccp_ndp_len(const int ndp)
 311 {
 312         return likely(ndp <= 0xFF) ? 1 : ndp <= 0xFFFF ? 2 : 3;
 313 }
 314
 315 int dccp_insert_option(struct sock *sk, struct sk_buff *skb,
 316                         const unsigned char option,
 317                         const void *value, const unsigned char len)
 318 {
 319         unsigned char *to;
 320
 321         if (DCCP_SKB_CB(skb)->dccpd_opt_len + len + 2 > DCCP_MAX_OPT_LEN)
 322                 return -1;
 323
 324         DCCP_SKB_CB(skb)->dccpd_opt_len += len + 2;
 325
 326         to    = skb_push(skb, len + 2);
 327         *to++ = option;
 328         *to++ = len + 2;
 329
 330         memcpy(to, value, len);
 331         return 0;
 332 }
 333
 334 EXPORT_SYMBOL_GPL(dccp_insert_option);
 335
 336 static int dccp_insert_option_ndp(struct sock *sk, struct sk_buff *skb)
 337 {
 338         struct dccp_sock *dp = dccp_sk(sk);
 339         int ndp = dp->dccps_ndp_count;
 340
 341         if (dccp_non_data_packet(skb))
 342                 ++dp->dccps_ndp_count;
 343         else
 344                 dp->dccps_ndp_count = 0;
 345
 346         if (ndp > 0) {
 347                 unsigned char *ptr;
 348                 const int ndp_len = dccp_ndp_len(ndp);
 349                 const int len = ndp_len + 2;
 350
 351                 if (DCCP_SKB_CB(skb)->dccpd_opt_len + len > DCCP_MAX_OPT_LEN)
 352                         return -1;
 353
 354                 DCCP_SKB_CB(skb)->dccpd_opt_len += len;
 355
 356                 ptr = skb_push(skb, len);
 357                 *ptr++ = DCCPO_NDP_COUNT;
 358                 *ptr++ = len;
 359                 dccp_encode_value_var(ndp, ptr, ndp_len);
 360         }
 361
 362         return 0;
 363 }
 364
 365 static inline int dccp_elapsed_time_len(const u32 elapsed_time)
 366 {
 367         return elapsed_time == 0 ? 0 : elapsed_time <= 0xFFFF ? 2 : 4;
 368 }
 369
 370 int dccp_insert_option_elapsed_time(struct sock *sk, struct sk_buff *skb,
 371                                     u32 elapsed_time)
 372 {
 373         const int elapsed_time_len = dccp_elapsed_time_len(elapsed_time);
 374         const int len = 2 + elapsed_time_len;
 375         unsigned char *to;
 376
 377         if (elapsed_time_len == 0)
 378                 return 0;
 379
 380         if (DCCP_SKB_CB(skb)->dccpd_opt_len + len > DCCP_MAX_OPT_LEN)
 381                 return -1;
 382
 383         DCCP_SKB_CB(skb)->dccpd_opt_len += len;
 384
 385         to    = skb_push(skb, len);
 386         *to++ = DCCPO_ELAPSED_TIME;
 387         *to++ = len;
 388
 389         if (elapsed_time_len == 2) {
 390                 const __be16 var16 = htons((u16)elapsed_time);
 391                 memcpy(to, &var16, 2);
 392         } else {
 393                 const __be32 var32 = htonl(elapsed_time);
 394                 memcpy(to, &var32, 4);
 395         }
 396
 397         return 0;
 398 }
 399
 400 EXPORT_SYMBOL_GPL(dccp_insert_option_elapsed_time);
 401
 402 int dccp_insert_option_timestamp(struct sock *sk, struct sk_buff *skb)
 403 {
 404         __be32 now = htonl(dccp_timestamp());
 405         /* yes this will overflow but that is the point as we want a
 406          * 10 usec 32 bit timer which mean it wraps every 11.9 hours */
 407
 408         return dccp_insert_option(sk, skb, DCCPO_TIMESTAMP, &now, sizeof(now));
 409 }
 410
 411 EXPORT_SYMBOL_GPL(dccp_insert_option_timestamp);
 412
 413 static int dccp_insert_option_timestamp_echo(struct dccp_sock *dp,
 414                                              struct dccp_request_sock *dreq,
 415                                              struct sk_buff *skb)
 416 {
 417         __be32 tstamp_echo;
 418         unsigned char *to;
 419         u32 elapsed_time, elapsed_time_len, len;
 420
 421         if (dreq != NULL) {
 422                 elapsed_time = dccp_timestamp() - dreq->dreq_timestamp_time;
 423                 tstamp_echo  = htonl(dreq->dreq_timestamp_echo);
 424                 dreq->dreq_timestamp_echo = 0;
 425         } else {
 426                 elapsed_time = dccp_timestamp() - dp->dccps_timestamp_time;
 427                 tstamp_echo  = htonl(dp->dccps_timestamp_echo);
 428                 dp->dccps_timestamp_echo = 0;
 429         }
 430
 431         elapsed_time_len = dccp_elapsed_time_len(elapsed_time);
 432         len = 6 + elapsed_time_len;
 433
 434         if (DCCP_SKB_CB(skb)->dccpd_opt_len + len > DCCP_MAX_OPT_LEN)
 435                 return -1;
 436
 437         DCCP_SKB_CB(skb)->dccpd_opt_len += len;
 438
 439         to    = skb_push(skb, len);
 440         *to++ = DCCPO_TIMESTAMP_ECHO;
 441         *to++ = len;
 442
 443         memcpy(to, &tstamp_echo, 4);
 444         to += 4;
 445
 446         if (elapsed_time_len == 2) {
 447                 const __be16 var16 = htons((u16)elapsed_time);
 448                 memcpy(to, &var16, 2);
 449         } else if (elapsed_time_len == 4) {
 450                 const __be32 var32 = htonl(elapsed_time);
 451                 memcpy(to, &var32, 4);
 452         }
 453
 454         return 0;
 455 }
 456
 457 static int dccp_insert_feat_opt(struct sk_buff *skb, u8 type, u8 feat,
 458                                 u8 *val, u8 len)
 459 {
 460         u8 *to;
 461
 462         if (DCCP_SKB_CB(skb)->dccpd_opt_len + len + 3 > DCCP_MAX_OPT_LEN) {
 463                 DCCP_WARN("packet too small for feature %d option!\n", feat);
 464                 return -1;
 465         }
 466
 467         DCCP_SKB_CB(skb)->dccpd_opt_len += len + 3;
 468
 469         to    = skb_push(skb, len + 3);
 470         *to++ = type;
 471         *to++ = len + 3;
 472         *to++ = feat;
 473
 474         if (len)
 475                 memcpy(to, val, len);
 476
 477         dccp_pr_debug("%s(%s (%d), ...), length %d\n",
 478                       dccp_feat_typename(type),
 479                       dccp_feat_name(feat), feat, len);
 480         return 0;
 481 }
 482
 483 static int dccp_insert_options_feat(struct sock *sk, struct sk_buff *skb)
 484 {
 485         struct dccp_sock *dp = dccp_sk(sk);
 486         struct dccp_minisock *dmsk = dccp_msk(sk);
 487         struct dccp_opt_pend *opt, *next;
 488         int change = 0;
 489
 490         /* confirm any options [NN opts] */
 491         list_for_each_entry_safe(opt, next, &dmsk->dccpms_conf, dccpop_node) {
 492                 dccp_insert_feat_opt(skb, opt->dccpop_type,
 493                                      opt->dccpop_feat, opt->dccpop_val,
 494                                      opt->dccpop_len);
 495                 /* fear empty confirms */
 496                 if (opt->dccpop_val)
 497                         kfree(opt->dccpop_val);
 498                 kfree(opt);
 499         }
 500         INIT_LIST_HEAD(&dmsk->dccpms_conf);
 501
 502         /* see which features we need to send */
 503         list_for_each_entry(opt, &dmsk->dccpms_pending, dccpop_node) {
 504                 /* see if we need to send any confirm */
 505                 if (opt->dccpop_sc) {
 506                         dccp_insert_feat_opt(skb, opt->dccpop_type + 1,
 507                                              opt->dccpop_feat,
 508                                              opt->dccpop_sc->dccpoc_val,
 509                                              opt->dccpop_sc->dccpoc_len);
 510
 511                         BUG_ON(!opt->dccpop_sc->dccpoc_val);
 512                         kfree(opt->dccpop_sc->dccpoc_val);
 513                         kfree(opt->dccpop_sc);
 514                         opt->dccpop_sc = NULL;
 515                 }
 516
 517                 /* any option not confirmed, re-send it */
 518                 if (!opt->dccpop_conf) {
 519                         dccp_insert_feat_opt(skb, opt->dccpop_type,
 520                                              opt->dccpop_feat, opt->dccpop_val,
 521                                              opt->dccpop_len);
 522                         change++;
 523                 }
 524         }
 525
 526         /* Retransmit timer.
 527          * If this is the master listening sock, we don't set a timer on it.  It
 528          * should be fine because if the dude doesn't receive our RESPONSE
 529          * [which will contain the CHANGE] he will send another REQUEST which
 530          * will "retrnasmit" the change.
 531          */
 532         if (change && dp->dccps_role != DCCP_ROLE_LISTEN) {
 533                 dccp_pr_debug("reset feat negotiation timer %p\n", sk);
 534
 535                 /* XXX don't reset the timer on re-transmissions.  I.e. reset it
 536                  * only when sending new stuff i guess.  Currently the timer
 537                  * never backs off because on re-transmission it just resets it!
 538                  */
 539                 inet_csk_reset_xmit_timer(sk, ICSK_TIME_RETRANS,
 540                                           inet_csk(sk)->icsk_rto, DCCP_RTO_MAX);
 541         }
 542
 543         return 0;
 544 }
 545
 546 /* The length of all options needs to be a multiple of 4 (5.8) */
 547 static void dccp_insert_option_padding(struct sk_buff *skb)
 548 {
 549         int padding = DCCP_SKB_CB(skb)->dccpd_opt_len % 4;
 550
 551         if (padding != 0) {
 552                 padding = 4 - padding;
 553                 memset(skb_push(skb, padding), 0, padding);
 554                 DCCP_SKB_CB(skb)->dccpd_opt_len += padding;
 555         }
 556 }
 557
 558 int dccp_insert_options(struct sock *sk, struct sk_buff *skb)
 559 {
 560         struct dccp_sock *dp = dccp_sk(sk);
 561         struct dccp_minisock *dmsk = dccp_msk(sk);
 562
 563         DCCP_SKB_CB(skb)->dccpd_opt_len = 0;
 564
 565         if (dmsk->dccpms_send_ndp_count &&
 566             dccp_insert_option_ndp(sk, skb))
 567                 return -1;
 568
 569         if (!dccp_packet_without_ack(skb)) {
 570                 if (dmsk->dccpms_send_ack_vector &&
 571                     dccp_ackvec_pending(dp->dccps_hc_rx_ackvec) &&
 572                     dccp_insert_option_ackvec(sk, skb))
 573                         return -1;
 574         }
 575
 576         if (dp->dccps_hc_rx_insert_options) {
 577                 if (ccid_hc_rx_insert_options(dp->dccps_hc_rx_ccid, sk, skb))
 578                         return -1;
 579                 dp->dccps_hc_rx_insert_options = 0;
 580         }
 581
 582         /* Feature negotiation */
 583         /* Data packets can't do feat negotiation */
 584         if (DCCP_SKB_CB(skb)->dccpd_type != DCCP_PKT_DATA &&
 585             DCCP_SKB_CB(skb)->dccpd_type != DCCP_PKT_DATAACK &&
 586             dccp_insert_options_feat(sk, skb))
 587                 return -1;
 588
 589         /*
 590          * Obtain RTT sample from Request/Response exchange.
 591          * This is currently used in CCID 3 initialisation.
 592          */
 593         if (DCCP_SKB_CB(skb)->dccpd_type == DCCP_PKT_REQUEST &&
 594             dccp_insert_option_timestamp(sk, skb))
 595                 return -1;
 596
 597         if (dp->dccps_timestamp_echo != 0 &&
 598             dccp_insert_option_timestamp_echo(dp, NULL, skb))
 599                 return -1;
 600
 601         dccp_insert_option_padding(skb);
 602         return 0;
 603 }
 604
 605 int dccp_insert_options_rsk(struct dccp_request_sock *dreq, struct sk_buff *skb)
 606 {
 607         DCCP_SKB_CB(skb)->dccpd_opt_len = 0;
 608
 609         if (dreq->dreq_timestamp_echo != 0 &&
 610             dccp_insert_option_timestamp_echo(NULL, dreq, skb))
 611                 return -1;
 612
 613         dccp_insert_option_padding(skb);
 614         return 0;
 615 }