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 u64 dccp_decode_value_var(const u8 *bf, const u8 len)
  27 {
  28         u64 value = 0;
  29
  30         if (len >= DCCP_OPTVAL_MAXLEN)
  31                 value += ((u64)*bf++) << 40;
  32         if (len > 4)
  33                 value += ((u64)*bf++) << 32;
  34         if (len > 3)
  35                 value += ((u64)*bf++) << 24;
  36         if (len > 2)
  37                 value += ((u64)*bf++) << 16;
  38         if (len > 1)
  39                 value += ((u64)*bf++) << 8;
  40         if (len > 0)
  41                 value += *bf;
  42
  43         return value;
  44 }
  45
  46 /**
  47  * dccp_parse_options  -  Parse DCCP options present in @skb
  48  * @sk: client|server|listening dccp socket (when @dreq != NULL)
  49  * @dreq: request socket to use during connection setup, or NULL
  50  */
  51 int dccp_parse_options(struct sock *sk, struct dccp_request_sock *dreq,
  52                        struct sk_buff *skb)
  53 {
  54         struct dccp_sock *dp = dccp_sk(sk);
  55         const struct dccp_hdr *dh = dccp_hdr(skb);
  56         const u8 pkt_type = DCCP_SKB_CB(skb)->dccpd_type;
  57         unsigned char *options = (unsigned char *)dh + dccp_hdr_len(skb);
  58         unsigned char *opt_ptr = options;
  59         const unsigned char *opt_end = (unsigned char *)dh +
  60                                         (dh->dccph_doff * 4);
  61         struct dccp_options_received *opt_recv = &dp->dccps_options_received;
  62         unsigned char opt, len;
  63         unsigned char *uninitialized_var(value);
  64         u32 elapsed_time;
  65         __be32 opt_val;
  66         int rc;
  67         int mandatory = 0;
  68
  69         memset(opt_recv, 0, sizeof(*opt_recv));
  70
  71         opt = len = 0;
  72         while (opt_ptr != opt_end) {
  73                 opt   = *opt_ptr++;
  74                 len   = 0;
  75                 value = NULL;
  76
  77                 /* Check if this isn't a single byte option */
  78                 if (opt > DCCPO_MAX_RESERVED) {
  79                         if (opt_ptr == opt_end)
  80                                 goto out_nonsensical_length;
  81
  82                         len = *opt_ptr++;
  83                         if (len < 2)
  84                                 goto out_nonsensical_length;
  85                         /*
  86                          * Remove the type and len fields, leaving
  87                          * just the value size
  88                          */
  89                         len     -= 2;
  90                         value   = opt_ptr;
  91                         opt_ptr += len;
  92
  93                         if (opt_ptr > opt_end)
  94                                 goto out_nonsensical_length;
  95                 }
  96
  97                 /*
  98                  * CCID-specific options are ignored during connection setup, as
  99                  * negotiation may still be in progress (see RFC 4340, 10.3).
 100                  * The same applies to Ack Vectors, as these depend on the CCID.
 101                  */
 102                 if (dreq != NULL && (opt >= DCCPO_MIN_RX_CCID_SPECIFIC ||
 103                     opt == DCCPO_ACK_VECTOR_0 || opt == DCCPO_ACK_VECTOR_1))
 104                         goto ignore_option;
 105
 106                 switch (opt) {
 107                 case DCCPO_PADDING:
 108                         break;
 109                 case DCCPO_MANDATORY:
 110                         if (mandatory)
 111                                 goto out_invalid_option;
 112                         if (pkt_type != DCCP_PKT_DATA)
 113                                 mandatory = 1;
 114                         break;
 115                 case DCCPO_NDP_COUNT:
 116                         if (len > 6)
 117                                 goto out_invalid_option;
 118
 119                         opt_recv->dccpor_ndp = dccp_decode_value_var(value, len);
 120                         dccp_pr_debug("%s opt: NDP count=%llu\n", dccp_role(sk),
 121                                       (unsigned long long)opt_recv->dccpor_ndp);
 122                         break;
 123                 case DCCPO_CHANGE_L ... DCCPO_CONFIRM_R:
 124                         if (pkt_type == DCCP_PKT_DATA)      /* RFC 4340, 6 */
 125                                 break;
 126                         if (len == 0)
 127                                 goto out_invalid_option;
 128                         rc = dccp_feat_parse_options(sk, dreq, mandatory, opt,
 129                                                     *value, value + 1, len - 1);
 130                         if (rc)
 131                                 goto out_featneg_failed;
 132                         break;
 133                 case DCCPO_TIMESTAMP:
 134                         if (len != 4)
 135                                 goto out_invalid_option;
 136                         /*
 137                          * RFC 4340 13.1: "The precise time corresponding to
 138                          * Timestamp Value zero is not specified". We use
 139                          * zero to indicate absence of a meaningful timestamp.
 140                          */
 141                         opt_val = get_unaligned((__be32 *)value);
 142                         if (unlikely(opt_val == 0)) {
 143                                 DCCP_WARN("Timestamp with zero value\n");
 144                                 break;
 145                         }
 146
 147                         if (dreq != NULL) {
 148                                 dreq->dreq_timestamp_echo = ntohl(opt_val);
 149                                 dreq->dreq_timestamp_time = dccp_timestamp();
 150                         } else {
 151                                 opt_recv->dccpor_timestamp =
 152                                         dp->dccps_timestamp_echo = ntohl(opt_val);
 153                                 dp->dccps_timestamp_time = dccp_timestamp();
 154                         }
 155                         dccp_pr_debug("%s rx opt: TIMESTAMP=%u, ackno=%llu\n",
 156                                       dccp_role(sk), ntohl(opt_val),
 157                                       (unsigned long long)
 158                                       DCCP_SKB_CB(skb)->dccpd_ack_seq);
 159                         /* schedule an Ack in case this sender is quiescent */
 160                         inet_csk_schedule_ack(sk);
 161                         break;
 162                 case DCCPO_TIMESTAMP_ECHO:
 163                         if (len != 4 && len != 6 && len != 8)
 164                                 goto out_invalid_option;
 165
 166                         opt_val = get_unaligned((__be32 *)value);
 167                         opt_recv->dccpor_timestamp_echo = ntohl(opt_val);
 168
 169                         dccp_pr_debug("%s rx opt: TIMESTAMP_ECHO=%u, len=%d, "
 170                                       "ackno=%llu", dccp_role(sk),
 171                                       opt_recv->dccpor_timestamp_echo,
 172                                       len + 2,
 173                                       (unsigned long long)
 174                                       DCCP_SKB_CB(skb)->dccpd_ack_seq);
 175
 176                         value += 4;
 177
 178                         if (len == 4) {         /* no elapsed time included */
 179                                 dccp_pr_debug_cat("\n");
 180                                 break;
 181                         }
 182
 183                         if (len == 6) {         /* 2-byte elapsed time */
 184                                 __be16 opt_val2 = get_unaligned((__be16 *)value);
 185                                 elapsed_time = ntohs(opt_val2);
 186                         } else {                /* 4-byte elapsed time */
 187                                 opt_val = get_unaligned((__be32 *)value);
 188                                 elapsed_time = ntohl(opt_val);
 189                         }
 190
 191                         dccp_pr_debug_cat(", ELAPSED_TIME=%u\n", elapsed_time);
 192
 193                         /* Give precedence to the biggest ELAPSED_TIME */
 194                         if (elapsed_time > opt_recv->dccpor_elapsed_time)
 195                                 opt_recv->dccpor_elapsed_time = elapsed_time;
 196                         break;
 197                 case DCCPO_ELAPSED_TIME:
 198                         if (dccp_packet_without_ack(skb))   /* RFC 4340, 13.2 */
 199                                 break;
 200
 201                         if (len == 2) {
 202                                 __be16 opt_val2 = get_unaligned((__be16 *)value);
 203                                 elapsed_time = ntohs(opt_val2);
 204                         } else if (len == 4) {
 205                                 opt_val = get_unaligned((__be32 *)value);
 206                                 elapsed_time = ntohl(opt_val);
 207                         } else {
 208                                 goto out_invalid_option;
 209                         }
 210
 211                         if (elapsed_time > opt_recv->dccpor_elapsed_time)
 212                                 opt_recv->dccpor_elapsed_time = elapsed_time;
 213
 214                         dccp_pr_debug("%s rx opt: ELAPSED_TIME=%d\n",
 215                                       dccp_role(sk), elapsed_time);
 216                         break;
 217                 case DCCPO_MIN_RX_CCID_SPECIFIC ... DCCPO_MAX_RX_CCID_SPECIFIC:
 218                         if (ccid_hc_rx_parse_options(dp->dccps_hc_rx_ccid, sk,
 219                                                      pkt_type, opt, value, len))
 220                                 goto out_invalid_option;
 221                         break;
 222                 case DCCPO_ACK_VECTOR_0:
 223                 case DCCPO_ACK_VECTOR_1:
 224                         if (dccp_packet_without_ack(skb))   /* RFC 4340, 11.4 */
 225                                 break;
 226                         /*
 227                          * Ack vectors are processed by the TX CCID if it is
 228                          * interested. The RX CCID need not parse Ack Vectors,
 229                          * since it is only interested in clearing old state.
 230                          * Fall through.
 231                          */
 232                 case DCCPO_MIN_TX_CCID_SPECIFIC ... DCCPO_MAX_TX_CCID_SPECIFIC:
 233                         if (ccid_hc_tx_parse_options(dp->dccps_hc_tx_ccid, sk,
 234                                                      pkt_type, opt, value, len))
 235                                 goto out_invalid_option;
 236                         break;
 237                 default:
 238                         DCCP_CRIT("DCCP(%p): option %d(len=%d) not "
 239                                   "implemented, ignoring", sk, opt, len);
 240                         break;
 241                 }
 242 ignore_option:
 243                 if (opt != DCCPO_MANDATORY)
 244                         mandatory = 0;
 245         }
 246
 247         /* mandatory was the last byte in option list -> reset connection */
 248         if (mandatory)
 249                 goto out_invalid_option;
 250
 251 out_nonsensical_length:
 252         /* RFC 4340, 5.8: ignore option and all remaining option space */
 253         return 0;
 254
 255 out_invalid_option:
 256         DCCP_INC_STATS_BH(DCCP_MIB_INVALIDOPT);
 257         rc = DCCP_RESET_CODE_OPTION_ERROR;
 258 out_featneg_failed:
 259         DCCP_WARN("DCCP(%p): Option %d (len=%d) error=%u\n", sk, opt, len, rc);
 260         DCCP_SKB_CB(skb)->dccpd_reset_code = rc;
 261         DCCP_SKB_CB(skb)->dccpd_reset_data[0] = opt;
 262         DCCP_SKB_CB(skb)->dccpd_reset_data[1] = len > 0 ? value[0] : 0;
 263         DCCP_SKB_CB(skb)->dccpd_reset_data[2] = len > 1 ? value[1] : 0;
 264         return -1;
 265 }
 266
 267 EXPORT_SYMBOL_GPL(dccp_parse_options);
 268
 269 void dccp_encode_value_var(const u64 value, u8 *to, const u8 len)
 270 {
 271         if (len >= DCCP_OPTVAL_MAXLEN)
 272                 *to++ = (value & 0xFF0000000000ull) >> 40;
 273         if (len > 4)
 274                 *to++ = (value & 0xFF00000000ull) >> 32;
 275         if (len > 3)
 276                 *to++ = (value & 0xFF000000) >> 24;
 277         if (len > 2)
 278                 *to++ = (value & 0xFF0000) >> 16;
 279         if (len > 1)
 280                 *to++ = (value & 0xFF00) >> 8;
 281         if (len > 0)
 282                 *to++ = (value & 0xFF);
 283 }
 284
 285 static inline u8 dccp_ndp_len(const u64 ndp)
 286 {
 287         if (likely(ndp <= 0xFF))
 288                 return 1;
 289         return likely(ndp <= USHRT_MAX) ? 2 : (ndp <= UINT_MAX ? 4 : 6);
 290 }
 291
 292 int dccp_insert_option(struct sk_buff *skb, const unsigned char option,
 293                        const void *value, const unsigned char len)
 294 {
 295         unsigned char *to;
 296
 297         if (DCCP_SKB_CB(skb)->dccpd_opt_len + len + 2 > DCCP_MAX_OPT_LEN)
 298                 return -1;
 299
 300         DCCP_SKB_CB(skb)->dccpd_opt_len += len + 2;
 301
 302         to    = skb_push(skb, len + 2);
 303         *to++ = option;
 304         *to++ = len + 2;
 305
 306         memcpy(to, value, len);
 307         return 0;
 308 }
 309
 310 EXPORT_SYMBOL_GPL(dccp_insert_option);
 311
 312 static int dccp_insert_option_ndp(struct sock *sk, struct sk_buff *skb)
 313 {
 314         struct dccp_sock *dp = dccp_sk(sk);
 315         u64 ndp = dp->dccps_ndp_count;
 316
 317         if (dccp_non_data_packet(skb))
 318                 ++dp->dccps_ndp_count;
 319         else
 320                 dp->dccps_ndp_count = 0;
 321
 322         if (ndp > 0) {
 323                 unsigned char *ptr;
 324                 const int ndp_len = dccp_ndp_len(ndp);
 325                 const int len = ndp_len + 2;
 326
 327                 if (DCCP_SKB_CB(skb)->dccpd_opt_len + len > DCCP_MAX_OPT_LEN)
 328                         return -1;
 329
 330                 DCCP_SKB_CB(skb)->dccpd_opt_len += len;
 331
 332                 ptr = skb_push(skb, len);
 333                 *ptr++ = DCCPO_NDP_COUNT;
 334                 *ptr++ = len;
 335                 dccp_encode_value_var(ndp, ptr, ndp_len);
 336         }
 337
 338         return 0;
 339 }
 340
 341 static inline int dccp_elapsed_time_len(const u32 elapsed_time)
 342 {
 343         return elapsed_time == 0 ? 0 : elapsed_time <= 0xFFFF ? 2 : 4;
 344 }
 345
 346 /* FIXME: This function is currently not used anywhere */
 347 int dccp_insert_option_elapsed_time(struct sk_buff *skb, u32 elapsed_time)
 348 {
 349         const int elapsed_time_len = dccp_elapsed_time_len(elapsed_time);
 350         const int len = 2 + elapsed_time_len;
 351         unsigned char *to;
 352
 353         if (elapsed_time_len == 0)
 354                 return 0;
 355
 356         if (DCCP_SKB_CB(skb)->dccpd_opt_len + len > DCCP_MAX_OPT_LEN)
 357                 return -1;
 358
 359         DCCP_SKB_CB(skb)->dccpd_opt_len += len;
 360
 361         to    = skb_push(skb, len);
 362         *to++ = DCCPO_ELAPSED_TIME;
 363         *to++ = len;
 364
 365         if (elapsed_time_len == 2) {
 366                 const __be16 var16 = htons((u16)elapsed_time);
 367                 memcpy(to, &var16, 2);
 368         } else {
 369                 const __be32 var32 = htonl(elapsed_time);
 370                 memcpy(to, &var32, 4);
 371         }
 372
 373         return 0;
 374 }
 375
 376 EXPORT_SYMBOL_GPL(dccp_insert_option_elapsed_time);
 377
 378 static int dccp_insert_option_timestamp(struct sk_buff *skb)
 379 {
 380         __be32 now = htonl(dccp_timestamp());
 381         /* yes this will overflow but that is the point as we want a
 382          * 10 usec 32 bit timer which mean it wraps every 11.9 hours */
 383
 384         return dccp_insert_option(skb, DCCPO_TIMESTAMP, &now, sizeof(now));
 385 }
 386
 387 static int dccp_insert_option_timestamp_echo(struct dccp_sock *dp,
 388                                              struct dccp_request_sock *dreq,
 389                                              struct sk_buff *skb)
 390 {
 391         __be32 tstamp_echo;
 392         unsigned char *to;
 393         u32 elapsed_time, elapsed_time_len, len;
 394
 395         if (dreq != NULL) {
 396                 elapsed_time = dccp_timestamp() - dreq->dreq_timestamp_time;
 397                 tstamp_echo  = htonl(dreq->dreq_timestamp_echo);
 398                 dreq->dreq_timestamp_echo = 0;
 399         } else {
 400                 elapsed_time = dccp_timestamp() - dp->dccps_timestamp_time;
 401                 tstamp_echo  = htonl(dp->dccps_timestamp_echo);
 402                 dp->dccps_timestamp_echo = 0;
 403         }
 404
 405         elapsed_time_len = dccp_elapsed_time_len(elapsed_time);
 406         len = 6 + elapsed_time_len;
 407
 408         if (DCCP_SKB_CB(skb)->dccpd_opt_len + len > DCCP_MAX_OPT_LEN)
 409                 return -1;
 410
 411         DCCP_SKB_CB(skb)->dccpd_opt_len += len;
 412
 413         to    = skb_push(skb, len);
 414         *to++ = DCCPO_TIMESTAMP_ECHO;
 415         *to++ = len;
 416
 417         memcpy(to, &tstamp_echo, 4);
 418         to += 4;
 419
 420         if (elapsed_time_len == 2) {
 421                 const __be16 var16 = htons((u16)elapsed_time);
 422                 memcpy(to, &var16, 2);
 423         } else if (elapsed_time_len == 4) {
 424                 const __be32 var32 = htonl(elapsed_time);
 425                 memcpy(to, &var32, 4);
 426         }
 427
 428         return 0;
 429 }
 430
 431 static int dccp_insert_option_ackvec(struct sock *sk, struct sk_buff *skb)
 432 {
 433         struct dccp_sock *dp = dccp_sk(sk);
 434         struct dccp_ackvec *av = dp->dccps_hc_rx_ackvec;
 435         struct dccp_skb_cb *dcb = DCCP_SKB_CB(skb);
 436         const u16 buflen = dccp_ackvec_buflen(av);
 437         /* Figure out how many options do we need to represent the ackvec */
 438         const u8 nr_opts = DIV_ROUND_UP(buflen, DCCP_SINGLE_OPT_MAXLEN);
 439         u16 len = buflen + 2 * nr_opts;
 440         u8 i, nonce = 0;
 441         const unsigned char *tail, *from;
 442         unsigned char *to;
 443
 444         if (dcb->dccpd_opt_len + len > DCCP_MAX_OPT_LEN) {
 445                 DCCP_WARN("Lacking space for %u bytes on %s packet\n", len,
 446                           dccp_packet_name(dcb->dccpd_type));
 447                 return -1;
 448         }
 449         /*
 450          * Since Ack Vectors are variable-length, we can not always predict
 451          * their size. To catch exception cases where the space is running out
 452          * on the skb, a separate Sync is scheduled to carry the Ack Vector.
 453          */
 454         if (len > DCCPAV_MIN_OPTLEN &&
 455             len + dcb->dccpd_opt_len + skb->len > dp->dccps_mss_cache) {
 456                 DCCP_WARN("No space left for Ack Vector (%u) on skb (%u+%u), "
 457                           "MPS=%u ==> reduce payload size?\n", len, skb->len,
 458                           dcb->dccpd_opt_len, dp->dccps_mss_cache);
 459                 dp->dccps_sync_scheduled = 1;
 460                 return 0;
 461         }
 462         dcb->dccpd_opt_len += len;
 463
 464         to   = skb_push(skb, len);
 465         len  = buflen;
 466         from = av->av_buf + av->av_buf_head;
 467         tail = av->av_buf + DCCPAV_MAX_ACKVEC_LEN;
 468
 469         for (i = 0; i < nr_opts; ++i) {
 470                 int copylen = len;
 471
 472                 if (len > DCCP_SINGLE_OPT_MAXLEN)
 473                         copylen = DCCP_SINGLE_OPT_MAXLEN;
 474
 475                 /*
 476                  * RFC 4340, 12.2: Encode the Nonce Echo for this Ack Vector via
 477                  * its type; ack_nonce is the sum of all individual buf_nonce's.
 478                  */
 479                 nonce ^= av->av_buf_nonce[i];
 480
 481                 *to++ = DCCPO_ACK_VECTOR_0 + av->av_buf_nonce[i];
 482                 *to++ = copylen + 2;
 483
 484                 /* Check if buf_head wraps */
 485                 if (from + copylen > tail) {
 486                         const u16 tailsize = tail - from;
 487
 488                         memcpy(to, from, tailsize);
 489                         to      += tailsize;
 490                         len     -= tailsize;
 491                         copylen -= tailsize;
 492                         from    = av->av_buf;
 493                 }
 494
 495                 memcpy(to, from, copylen);
 496                 from += copylen;
 497                 to   += copylen;
 498                 len  -= copylen;
 499         }
 500         /*
 501          * Each sent Ack Vector is recorded in the list, as per A.2 of RFC 4340.
 502          */
 503         if (dccp_ackvec_update_records(av, dcb->dccpd_seq, nonce))
 504                 return -ENOBUFS;
 505         return 0;
 506 }
 507
 508 /**
 509  * dccp_insert_option_mandatory  -  Mandatory option (5.8.2)
 510  * Note that since we are using skb_push, this function needs to be called
 511  * _after_ inserting the option it is supposed to influence (stack order).
 512  */
 513 int dccp_insert_option_mandatory(struct sk_buff *skb)
 514 {
 515         if (DCCP_SKB_CB(skb)->dccpd_opt_len >= DCCP_MAX_OPT_LEN)
 516                 return -1;
 517
 518         DCCP_SKB_CB(skb)->dccpd_opt_len++;
 519         *skb_push(skb, 1) = DCCPO_MANDATORY;
 520         return 0;
 521 }
 522
 523 /**
 524  * dccp_insert_fn_opt  -  Insert single Feature-Negotiation option into @skb
 525  * @type: %DCCPO_CHANGE_L, %DCCPO_CHANGE_R, %DCCPO_CONFIRM_L, %DCCPO_CONFIRM_R
 526  * @feat: one out of %dccp_feature_numbers
 527  * @val: NN value or SP array (preferred element first) to copy
 528  * @len: true length of @val in bytes (excluding first element repetition)
 529  * @repeat_first: whether to copy the first element of @val twice
 530  * The last argument is used to construct Confirm options, where the preferred
 531  * value and the preference list appear separately (RFC 4340, 6.3.1). Preference
 532  * lists are kept such that the preferred entry is always first, so we only need
 533  * to copy twice, and avoid the overhead of cloning into a bigger array.
 534  */
 535 int dccp_insert_fn_opt(struct sk_buff *skb, u8 type, u8 feat,
 536                        u8 *val, u8 len, bool repeat_first)
 537 {
 538         u8 tot_len, *to;
 539
 540         /* take the `Feature' field and possible repetition into account */
 541         if (len > (DCCP_SINGLE_OPT_MAXLEN - 2)) {
 542                 DCCP_WARN("length %u for feature %u too large\n", len, feat);
 543                 return -1;
 544         }
 545
 546         if (unlikely(val == NULL || len == 0))
 547                 len = repeat_first = 0;
 548         tot_len = 3 + repeat_first + len;
 549
 550         if (DCCP_SKB_CB(skb)->dccpd_opt_len + tot_len > DCCP_MAX_OPT_LEN) {
 551                 DCCP_WARN("packet too small for feature %d option!\n", feat);
 552                 return -1;
 553         }
 554         DCCP_SKB_CB(skb)->dccpd_opt_len += tot_len;
 555
 556         to    = skb_push(skb, tot_len);
 557         *to++ = type;
 558         *to++ = tot_len;
 559         *to++ = feat;
 560
 561         if (repeat_first)
 562                 *to++ = *val;
 563         if (len)
 564                 memcpy(to, val, len);
 565         return 0;
 566 }
 567
 568 /* The length of all options needs to be a multiple of 4 (5.8) */
 569 static void dccp_insert_option_padding(struct sk_buff *skb)
 570 {
 571         int padding = DCCP_SKB_CB(skb)->dccpd_opt_len % 4;
 572
 573         if (padding != 0) {
 574                 padding = 4 - padding;
 575                 memset(skb_push(skb, padding), 0, padding);
 576                 DCCP_SKB_CB(skb)->dccpd_opt_len += padding;
 577         }
 578 }
 579
 580 int dccp_insert_options(struct sock *sk, struct sk_buff *skb)
 581 {
 582         struct dccp_sock *dp = dccp_sk(sk);
 583
 584         DCCP_SKB_CB(skb)->dccpd_opt_len = 0;
 585
 586         if (dp->dccps_send_ndp_count && dccp_insert_option_ndp(sk, skb))
 587                 return -1;
 588
 589         if (DCCP_SKB_CB(skb)->dccpd_type != DCCP_PKT_DATA) {
 590
 591                 /* Feature Negotiation */
 592                 if (dccp_feat_insert_opts(dp, NULL, skb))
 593                         return -1;
 594
 595                 if (DCCP_SKB_CB(skb)->dccpd_type == DCCP_PKT_REQUEST) {
 596                         /*
 597                          * Obtain RTT sample from Request/Response exchange.
 598                          * This is currently used for TFRC initialisation.
 599                          */
 600                         if (dccp_insert_option_timestamp(skb))
 601                                 return -1;
 602
 603                 } else if (dccp_ackvec_pending(sk) &&
 604                            dccp_insert_option_ackvec(sk, skb)) {
 605                                 return -1;
 606                 }
 607         }
 608
 609         if (dp->dccps_hc_rx_insert_options) {
 610                 if (ccid_hc_rx_insert_options(dp->dccps_hc_rx_ccid, sk, skb))
 611                         return -1;
 612                 dp->dccps_hc_rx_insert_options = 0;
 613         }
 614
 615         if (dp->dccps_timestamp_echo != 0 &&
 616             dccp_insert_option_timestamp_echo(dp, NULL, skb))
 617                 return -1;
 618
 619         dccp_insert_option_padding(skb);
 620         return 0;
 621 }
 622
 623 int dccp_insert_options_rsk(struct dccp_request_sock *dreq, struct sk_buff *skb)
 624 {
 625         DCCP_SKB_CB(skb)->dccpd_opt_len = 0;
 626
 627         if (dccp_feat_insert_opts(NULL, dreq, skb))
 628                 return -1;
 629
 630         /* Obtain RTT sample from Response/Ack exchange (used by TFRC). */
 631         if (dccp_insert_option_timestamp(skb))
 632                 return -1;
 633
 634         if (dreq->dreq_timestamp_echo != 0 &&
 635             dccp_insert_option_timestamp_echo(NULL, dreq, skb))
 636                 return -1;
 637
 638         dccp_insert_option_padding(skb);
 639         return 0;
 640 }