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_send_ack_vector = DCCPF_INITIAL_SEND_ACK_VECTOR;
  30 int sysctl_dccp_feat_send_ndp_count  = DCCPF_INITIAL_SEND_NDP_COUNT;
  31
  32 u64 dccp_decode_value_var(const u8 *bf, const u8 len)
  33 {
  34         u64 value = 0;
  35
  36         if (len >= DCCP_OPTVAL_MAXLEN)
  37                 value += ((u64)*bf++) << 40;
  38         if (len > 4)
  39                 value += ((u64)*bf++) << 32;
  40         if (len > 3)
  41                 value += ((u64)*bf++) << 24;
  42         if (len > 2)
  43                 value += ((u64)*bf++) << 16;
  44         if (len > 1)
  45                 value += ((u64)*bf++) << 8;
  46         if (len > 0)
  47                 value += *bf;
  48
  49         return value;
  50 }
  51
  52 /**
  53  * dccp_parse_options  -  Parse DCCP options present in @skb
  54  * @sk: client|server|listening dccp socket (when @dreq != NULL)
  55  * @dreq: request socket to use during connection setup, or NULL
  56  */
  57 int dccp_parse_options(struct sock *sk, struct dccp_request_sock *dreq,
  58                        struct sk_buff *skb)
  59 {
  60         struct dccp_sock *dp = dccp_sk(sk);
  61         const struct dccp_hdr *dh = dccp_hdr(skb);
  62         const u8 pkt_type = DCCP_SKB_CB(skb)->dccpd_type;
  63         u64 ackno = DCCP_SKB_CB(skb)->dccpd_ack_seq;
  64         unsigned char *options = (unsigned char *)dh + dccp_hdr_len(skb);
  65         unsigned char *opt_ptr = options;
  66         const unsigned char *opt_end = (unsigned char *)dh +
  67                                         (dh->dccph_doff * 4);
  68         struct dccp_options_received *opt_recv = &dp->dccps_options_received;
  69         unsigned char opt, len;
  70         unsigned char *uninitialized_var(value);
  71         u32 elapsed_time;
  72         __be32 opt_val;
  73         int rc;
  74         int mandatory = 0;
  75
  76         memset(opt_recv, 0, sizeof(*opt_recv));
  77
  78         opt = len = 0;
  79         while (opt_ptr != opt_end) {
  80                 opt   = *opt_ptr++;
  81                 len   = 0;
  82                 value = NULL;
  83
  84                 /* Check if this isn't a single byte option */
  85                 if (opt > DCCPO_MAX_RESERVED) {
  86                         if (opt_ptr == opt_end)
  87                                 goto out_nonsensical_length;
  88
  89                         len = *opt_ptr++;
  90                         if (len < 2)
  91                                 goto out_nonsensical_length;
  92                         /*
  93                          * Remove the type and len fields, leaving
  94                          * just the value size
  95                          */
  96                         len     -= 2;
  97                         value   = opt_ptr;
  98                         opt_ptr += len;
  99
 100                         if (opt_ptr > opt_end)
 101                                 goto out_nonsensical_length;
 102                 }
 103
 104                 /*
 105                  * CCID-Specific Options (from RFC 4340, sec. 10.3):
 106                  *
 107                  * Option numbers 128 through 191 are for options sent from the
 108                  * HC-Sender to the HC-Receiver; option numbers 192 through 255
 109                  * are for options sent from the HC-Receiver to the HC-Sender.
 110                  *
 111                  * CCID-specific options are ignored during connection setup, as
 112                  * negotiation may still be in progress (see RFC 4340, 10.3).
 113                  * The same applies to Ack Vectors, as these depend on the CCID.
 114                  *
 115                  */
 116                 if (dreq != NULL && (opt >= 128 ||
 117                     opt == DCCPO_ACK_VECTOR_0 || opt == DCCPO_ACK_VECTOR_1))
 118                         goto ignore_option;
 119
 120                 switch (opt) {
 121                 case DCCPO_PADDING:
 122                         break;
 123                 case DCCPO_MANDATORY:
 124                         if (mandatory)
 125                                 goto out_invalid_option;
 126                         if (pkt_type != DCCP_PKT_DATA)
 127                                 mandatory = 1;
 128                         break;
 129                 case DCCPO_NDP_COUNT:
 130                         if (len > 6)
 131                                 goto out_invalid_option;
 132
 133                         opt_recv->dccpor_ndp = dccp_decode_value_var(value, len);
 134                         dccp_pr_debug("%s opt: NDP count=%llu\n", dccp_role(sk),
 135                                       (unsigned long long)opt_recv->dccpor_ndp);
 136                         break;
 137                 case DCCPO_CHANGE_L ... DCCPO_CONFIRM_R:
 138                         if (pkt_type == DCCP_PKT_DATA)      /* RFC 4340, 6 */
 139                                 break;
 140                         rc = dccp_feat_parse_options(sk, dreq, mandatory, opt,
 141                                                     *value, value + 1, len - 1);
 142                         if (rc)
 143                                 goto out_featneg_failed;
 144                         break;
 145                 case DCCPO_ACK_VECTOR_0:
 146                 case DCCPO_ACK_VECTOR_1:
 147                         if (dccp_packet_without_ack(skb))   /* RFC 4340, 11.4 */
 148                                 break;
 149
 150                         if (dccp_msk(sk)->dccpms_send_ack_vector &&
 151                             dccp_ackvec_parse(sk, skb, &ackno, opt, value, len))
 152                                 goto out_invalid_option;
 153                         break;
 154                 case DCCPO_TIMESTAMP:
 155                         if (len != 4)
 156                                 goto out_invalid_option;
 157                         /*
 158                          * RFC 4340 13.1: "The precise time corresponding to
 159                          * Timestamp Value zero is not specified". We use
 160                          * zero to indicate absence of a meaningful timestamp.
 161                          */
 162                         opt_val = get_unaligned((__be32 *)value);
 163                         if (unlikely(opt_val == 0)) {
 164                                 DCCP_WARN("Timestamp with zero value\n");
 165                                 break;
 166                         }
 167
 168                         if (dreq != NULL) {
 169                                 dreq->dreq_timestamp_echo = ntohl(opt_val);
 170                                 dreq->dreq_timestamp_time = dccp_timestamp();
 171                         } else {
 172                                 opt_recv->dccpor_timestamp =
 173                                         dp->dccps_timestamp_echo = ntohl(opt_val);
 174                                 dp->dccps_timestamp_time = dccp_timestamp();
 175                         }
 176                         dccp_pr_debug("%s rx opt: TIMESTAMP=%u, ackno=%llu\n",
 177                                       dccp_role(sk), ntohl(opt_val),
 178                                       (unsigned long long)
 179                                       DCCP_SKB_CB(skb)->dccpd_ack_seq);
 180                         break;
 181                 case DCCPO_TIMESTAMP_ECHO:
 182                         if (len != 4 && len != 6 && len != 8)
 183                                 goto out_invalid_option;
 184
 185                         opt_val = get_unaligned((__be32 *)value);
 186                         opt_recv->dccpor_timestamp_echo = ntohl(opt_val);
 187
 188                         dccp_pr_debug("%s rx opt: TIMESTAMP_ECHO=%u, len=%d, "
 189                                       "ackno=%llu", dccp_role(sk),
 190                                       opt_recv->dccpor_timestamp_echo,
 191                                       len + 2,
 192                                       (unsigned long long)
 193                                       DCCP_SKB_CB(skb)->dccpd_ack_seq);
 194
 195                         value += 4;
 196
 197                         if (len == 4) {         /* no elapsed time included */
 198                                 dccp_pr_debug_cat("\n");
 199                                 break;
 200                         }
 201
 202                         if (len == 6) {         /* 2-byte elapsed time */
 203                                 __be16 opt_val2 = get_unaligned((__be16 *)value);
 204                                 elapsed_time = ntohs(opt_val2);
 205                         } else {                /* 4-byte elapsed time */
 206                                 opt_val = get_unaligned((__be32 *)value);
 207                                 elapsed_time = ntohl(opt_val);
 208                         }
 209
 210                         dccp_pr_debug_cat(", ELAPSED_TIME=%u\n", elapsed_time);
 211
 212                         /* Give precedence to the biggest ELAPSED_TIME */
 213                         if (elapsed_time > opt_recv->dccpor_elapsed_time)
 214                                 opt_recv->dccpor_elapsed_time = elapsed_time;
 215                         break;
 216                 case DCCPO_ELAPSED_TIME:
 217                         if (dccp_packet_without_ack(skb))   /* RFC 4340, 13.2 */
 218                                 break;
 219
 220                         if (len == 2) {
 221                                 __be16 opt_val2 = get_unaligned((__be16 *)value);
 222                                 elapsed_time = ntohs(opt_val2);
 223                         } else if (len == 4) {
 224                                 opt_val = get_unaligned((__be32 *)value);
 225                                 elapsed_time = ntohl(opt_val);
 226                         } else {
 227                                 goto out_invalid_option;
 228                         }
 229
 230                         if (elapsed_time > opt_recv->dccpor_elapsed_time)
 231                                 opt_recv->dccpor_elapsed_time = elapsed_time;
 232
 233                         dccp_pr_debug("%s rx opt: ELAPSED_TIME=%d\n",
 234                                       dccp_role(sk), elapsed_time);
 235                         break;
 236                 case 128 ... 191: {
 237                         const u16 idx = value - options;
 238
 239                         if (ccid_hc_rx_parse_options(dp->dccps_hc_rx_ccid, sk,
 240                                                      opt, len, idx,
 241                                                      value) != 0)
 242                                 goto out_invalid_option;
 243                 }
 244                         break;
 245                 case 192 ... 255: {
 246                         const u16 idx = value - options;
 247
 248                         if (ccid_hc_tx_parse_options(dp->dccps_hc_tx_ccid, sk,
 249                                                      opt, len, idx,
 250                                                      value) != 0)
 251                                 goto out_invalid_option;
 252                 }
 253                         break;
 254                 default:
 255                         DCCP_CRIT("DCCP(%p): option %d(len=%d) not "
 256                                   "implemented, ignoring", sk, opt, len);
 257                         break;
 258                 }
 259 ignore_option:
 260                 if (opt != DCCPO_MANDATORY)
 261                         mandatory = 0;
 262         }
 263
 264         /* mandatory was the last byte in option list -> reset connection */
 265         if (mandatory)
 266                 goto out_invalid_option;
 267
 268 out_nonsensical_length:
 269         /* RFC 4340, 5.8: ignore option and all remaining option space */
 270         return 0;
 271
 272 out_invalid_option:
 273         DCCP_INC_STATS_BH(DCCP_MIB_INVALIDOPT);
 274         rc = DCCP_RESET_CODE_OPTION_ERROR;
 275 out_featneg_failed:
 276         DCCP_WARN("DCCP(%p): Option %d (len=%d) error=%u\n", sk, opt, len, rc);
 277         DCCP_SKB_CB(skb)->dccpd_reset_code = rc;
 278         DCCP_SKB_CB(skb)->dccpd_reset_data[0] = opt;
 279         DCCP_SKB_CB(skb)->dccpd_reset_data[1] = len > 0 ? value[0] : 0;
 280         DCCP_SKB_CB(skb)->dccpd_reset_data[2] = len > 1 ? value[1] : 0;
 281         return -1;
 282 }
 283
 284 EXPORT_SYMBOL_GPL(dccp_parse_options);
 285
 286 void dccp_encode_value_var(const u64 value, u8 *to, const u8 len)
 287 {
 288         if (len >= DCCP_OPTVAL_MAXLEN)
 289                 *to++ = (value & 0xFF0000000000ull) >> 40;
 290         if (len > 4)
 291                 *to++ = (value & 0xFF00000000ull) >> 32;
 292         if (len > 3)
 293                 *to++ = (value & 0xFF000000) >> 24;
 294         if (len > 2)
 295                 *to++ = (value & 0xFF0000) >> 16;
 296         if (len > 1)
 297                 *to++ = (value & 0xFF00) >> 8;
 298         if (len > 0)
 299                 *to++ = (value & 0xFF);
 300 }
 301
 302 static inline u8 dccp_ndp_len(const u64 ndp)
 303 {
 304         if (likely(ndp <= 0xFF))
 305                 return 1;
 306         return likely(ndp <= USHORT_MAX) ? 2 : (ndp <= UINT_MAX ? 4 : 6);
 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         u64 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 /**
 452  * dccp_insert_option_mandatory  -  Mandatory option (5.8.2)
 453  * Note that since we are using skb_push, this function needs to be called
 454  * _after_ inserting the option it is supposed to influence (stack order).
 455  */
 456 int dccp_insert_option_mandatory(struct sk_buff *skb)
 457 {
 458         if (DCCP_SKB_CB(skb)->dccpd_opt_len >= DCCP_MAX_OPT_LEN)
 459                 return -1;
 460
 461         DCCP_SKB_CB(skb)->dccpd_opt_len++;
 462         *skb_push(skb, 1) = DCCPO_MANDATORY;
 463         return 0;
 464 }
 465
 466 /**
 467  * dccp_insert_fn_opt  -  Insert single Feature-Negotiation option into @skb
 468  * @type: %DCCPO_CHANGE_L, %DCCPO_CHANGE_R, %DCCPO_CONFIRM_L, %DCCPO_CONFIRM_R
 469  * @feat: one out of %dccp_feature_numbers
 470  * @val: NN value or SP array (preferred element first) to copy
 471  * @len: true length of @val in bytes (excluding first element repetition)
 472  * @repeat_first: whether to copy the first element of @val twice
 473  * The last argument is used to construct Confirm options, where the preferred
 474  * value and the preference list appear separately (RFC 4340, 6.3.1). Preference
 475  * lists are kept such that the preferred entry is always first, so we only need
 476  * to copy twice, and avoid the overhead of cloning into a bigger array.
 477  */
 478 int dccp_insert_fn_opt(struct sk_buff *skb, u8 type, u8 feat,
 479                        u8 *val, u8 len, bool repeat_first)
 480 {
 481         u8 tot_len, *to;
 482
 483         /* take the `Feature' field and possible repetition into account */
 484         if (len > (DCCP_SINGLE_OPT_MAXLEN - 2)) {
 485                 DCCP_WARN("length %u for feature %u too large\n", len, feat);
 486                 return -1;
 487         }
 488
 489         if (unlikely(val == NULL || len == 0))
 490                 len = repeat_first = 0;
 491         tot_len = 3 + repeat_first + len;
 492
 493         if (DCCP_SKB_CB(skb)->dccpd_opt_len + tot_len > DCCP_MAX_OPT_LEN) {
 494                 DCCP_WARN("packet too small for feature %d option!\n", feat);
 495                 return -1;
 496         }
 497         DCCP_SKB_CB(skb)->dccpd_opt_len += tot_len;
 498
 499         to    = skb_push(skb, tot_len);
 500         *to++ = type;
 501         *to++ = tot_len;
 502         *to++ = feat;
 503
 504         if (repeat_first)
 505                 *to++ = *val;
 506         if (len)
 507                 memcpy(to, val, len);
 508
 509         dccp_pr_debug("%s(%s (%d), ...), length %d\n",
 510                       dccp_feat_typename(type),
 511                       dccp_feat_name(feat), feat, len);
 512         return 0;
 513 }
 514
 515 /* The length of all options needs to be a multiple of 4 (5.8) */
 516 static void dccp_insert_option_padding(struct sk_buff *skb)
 517 {
 518         int padding = DCCP_SKB_CB(skb)->dccpd_opt_len % 4;
 519
 520         if (padding != 0) {
 521                 padding = 4 - padding;
 522                 memset(skb_push(skb, padding), 0, padding);
 523                 DCCP_SKB_CB(skb)->dccpd_opt_len += padding;
 524         }
 525 }
 526
 527 int dccp_insert_options(struct sock *sk, struct sk_buff *skb)
 528 {
 529         struct dccp_sock *dp = dccp_sk(sk);
 530         struct dccp_minisock *dmsk = dccp_msk(sk);
 531
 532         DCCP_SKB_CB(skb)->dccpd_opt_len = 0;
 533
 534         if (dmsk->dccpms_send_ndp_count &&
 535             dccp_insert_option_ndp(sk, skb))
 536                 return -1;
 537
 538         if (DCCP_SKB_CB(skb)->dccpd_type != DCCP_PKT_DATA) {
 539
 540                 /* Feature Negotiation */
 541                 if (dccp_feat_insert_opts(dp, NULL, skb))
 542                         return -1;
 543
 544                 if (DCCP_SKB_CB(skb)->dccpd_type == DCCP_PKT_REQUEST) {
 545                         /*
 546                          * Obtain RTT sample from Request/Response exchange.
 547                          * This is currently used in CCID 3 initialisation.
 548                          */
 549                         if (dccp_insert_option_timestamp(sk, skb))
 550                                 return -1;
 551
 552                 } else 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
 559         if (dp->dccps_hc_rx_insert_options) {
 560                 if (ccid_hc_rx_insert_options(dp->dccps_hc_rx_ccid, sk, skb))
 561                         return -1;
 562                 dp->dccps_hc_rx_insert_options = 0;
 563         }
 564
 565         if (dp->dccps_timestamp_echo != 0 &&
 566             dccp_insert_option_timestamp_echo(dp, NULL, skb))
 567                 return -1;
 568
 569         dccp_insert_option_padding(skb);
 570         return 0;
 571 }
 572
 573 int dccp_insert_options_rsk(struct dccp_request_sock *dreq, struct sk_buff *skb)
 574 {
 575         DCCP_SKB_CB(skb)->dccpd_opt_len = 0;
 576
 577         if (dccp_feat_insert_opts(NULL, dreq, skb))
 578                 return -1;
 579
 580         if (dreq->dreq_timestamp_echo != 0 &&
 581             dccp_insert_option_timestamp_echo(NULL, dreq, skb))
 582                 return -1;
 583
 584         dccp_insert_option_padding(skb);
 585         return 0;
 586 }