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   1 /*
   2  *  net/dccp/options.c
   3  *
   4  *  An implementation of the DCCP protocol
   5  *  Aristeu Sergio Rozanski Filho <aris@cathedrallabs.org>
   6  *  Arnaldo Carvalho de Melo <acme@ghostprotocols.net>
   7  *
   8  *      This program is free software; you can redistribute it and/or
   9  *      modify it under the terms of the GNU General Public License
  10  *      as published by the Free Software Foundation; either version
  11  *      2 of the License, or (at your option) any later version.
  12  */
  13 #include <linux/config.h>
  14 #include <linux/dccp.h>
  15 #include <linux/module.h>
  16 #include <linux/types.h>
  17 #include <linux/kernel.h>
  18 #include <linux/skbuff.h>
  19
  20 #include "ccid.h"
  21 #include "dccp.h"
  22
  23 static void dccp_ackpkts_check_rcv_ackvector(struct dccp_ackpkts *ap,
  24                                              struct sock *sk,
  25                                              const u64 ackno,
  26                                              const unsigned char len,
  27                                              const unsigned char *vector);
  28
  29 /* stores the default values for new connection. may be changed with sysctl */
  30 static const struct dccp_options dccpo_default_values = {
  31         .dccpo_sequence_window    = DCCPF_INITIAL_SEQUENCE_WINDOW,
  32         .dccpo_ccid               = DCCPF_INITIAL_CCID,
  33         .dccpo_send_ack_vector    = DCCPF_INITIAL_SEND_ACK_VECTOR,
  34         .dccpo_send_ndp_count     = DCCPF_INITIAL_SEND_NDP_COUNT,
  35 };
  36
  37 void dccp_options_init(struct dccp_options *dccpo)
  38 {
  39         memcpy(dccpo, &dccpo_default_values, sizeof(*dccpo));
  40 }
  41
  42 static u32 dccp_decode_value_var(const unsigned char *bf, const u8 len)
  43 {
  44         u32 value = 0;
  45
  46         if (len > 3)
  47                 value += *bf++ << 24;
  48         if (len > 2)
  49                 value += *bf++ << 16;
  50         if (len > 1)
  51                 value += *bf++ << 8;
  52         if (len > 0)
  53                 value += *bf;
  54
  55         return value;
  56 }
  57
  58 int dccp_parse_options(struct sock *sk, struct sk_buff *skb)
  59 {
  60         struct dccp_sock *dp = dccp_sk(sk);
  61 #ifdef DCCP_DEBUG
  62         const char *debug_prefix = dp->dccps_role == DCCP_ROLE_CLIENT ?
  63                                         "CLIENT rx opt: " : "server rx opt: ";
  64 #endif
  65         const struct dccp_hdr *dh = dccp_hdr(skb);
  66         const u8 pkt_type = DCCP_SKB_CB(skb)->dccpd_type;
  67         unsigned char *options = (unsigned char *)dh + dccp_hdr_len(skb);
  68         unsigned char *opt_ptr = options;
  69         const unsigned char *opt_end = (unsigned char *)dh +
  70                                         (dh->dccph_doff * 4);
  71         struct dccp_options_received *opt_recv = &dp->dccps_options_received;
  72         unsigned char opt, len;
  73         unsigned char *value;
  74
  75         memset(opt_recv, 0, sizeof(*opt_recv));
  76
  77         while (opt_ptr != opt_end) {
  78                 opt   = *opt_ptr++;
  79                 len   = 0;
  80                 value = NULL;
  81
  82                 /* Check if this isn't a single byte option */
  83                 if (opt > DCCPO_MAX_RESERVED) {
  84                         if (opt_ptr == opt_end)
  85                                 goto out_invalid_option;
  86
  87                         len = *opt_ptr++;
  88                         if (len < 3)
  89                                 goto out_invalid_option;
  90                         /*
  91                          * Remove the type and len fields, leaving
  92                          * just the value size
  93                          */
  94                         len     -= 2;
  95                         value   = opt_ptr;
  96                         opt_ptr += len;
  97
  98                         if (opt_ptr > opt_end)
  99                                 goto out_invalid_option;
 100                 }
 101
 102                 switch (opt) {
 103                 case DCCPO_PADDING:
 104                         break;
 105                 case DCCPO_NDP_COUNT:
 106                         if (len > 3)
 107                                 goto out_invalid_option;
 108
 109                         opt_recv->dccpor_ndp = dccp_decode_value_var(value, len);
 110                         dccp_pr_debug("%sNDP count=%d\n", debug_prefix,
 111                                       opt_recv->dccpor_ndp);
 112                         break;
 113                 case DCCPO_ACK_VECTOR_0:
 114                         if (len > DCCP_MAX_ACK_VECTOR_LEN)
 115                                 goto out_invalid_option;
 116
 117                         if (pkt_type == DCCP_PKT_DATA)
 118                                 continue;
 119
 120                         opt_recv->dccpor_ack_vector_len = len;
 121                         opt_recv->dccpor_ack_vector_idx = value - options;
 122
 123                         dccp_pr_debug("%sACK vector 0, len=%d, ack_ackno=%llu\n",
 124                                       debug_prefix, len,
 125                                       (unsigned long long)
 126                                       DCCP_SKB_CB(skb)->dccpd_ack_seq);
 127                         dccp_ackvector_print(DCCP_SKB_CB(skb)->dccpd_ack_seq,
 128                                              value, len);
 129                         dccp_ackpkts_check_rcv_ackvector(dp->dccps_hc_rx_ackpkts,
 130                                                          sk,
 131                                                  DCCP_SKB_CB(skb)->dccpd_ack_seq,
 132                                                          len, value);
 133                         break;
 134                 case DCCPO_TIMESTAMP:
 135                         if (len != 4)
 136                                 goto out_invalid_option;
 137
 138                         opt_recv->dccpor_timestamp = ntohl(*(u32 *)value);
 139
 140                         dp->dccps_timestamp_echo = opt_recv->dccpor_timestamp;
 141                         dp->dccps_timestamp_time = jiffies;
 142
 143                         dccp_pr_debug("%sTIMESTAMP=%u, ackno=%llu\n",
 144                                       debug_prefix, opt_recv->dccpor_timestamp,
 145                                       (unsigned long long)
 146                                       DCCP_SKB_CB(skb)->dccpd_ack_seq);
 147                         break;
 148                 case DCCPO_TIMESTAMP_ECHO:
 149                         if (len < 4 || len > 8)
 150                                 goto out_invalid_option;
 151
 152                         opt_recv->dccpor_timestamp_echo = ntohl(*(u32 *)value);
 153
 154                         dccp_pr_debug("%sTIMESTAMP_ECHO=%u, len=%d, ackno=%llu, "
 155                                       "diff=%u\n",
 156                                       debug_prefix,
 157                                       opt_recv->dccpor_timestamp_echo,
 158                                       len + 2,
 159                                       (unsigned long long)
 160                                       DCCP_SKB_CB(skb)->dccpd_ack_seq,
 161                                       (tcp_time_stamp -
 162                                        opt_recv->dccpor_timestamp_echo));
 163
 164                         opt_recv->dccpor_elapsed_time =
 165                                         dccp_decode_value_var(value + 4,
 166                                                              len - 4);
 167                         dccp_pr_debug("%sTIMESTAMP_ECHO ELAPSED_TIME=%d\n",
 168                                       debug_prefix,
 169                                       opt_recv->dccpor_elapsed_time);
 170                         break;
 171                 case DCCPO_ELAPSED_TIME:
 172                         if (len > 4)
 173                                 goto out_invalid_option;
 174
 175                         if (pkt_type == DCCP_PKT_DATA)
 176                                 continue;
 177                         opt_recv->dccpor_elapsed_time =
 178                                         dccp_decode_value_var(value, len);
 179                         dccp_pr_debug("%sELAPSED_TIME=%d\n", debug_prefix,
 180                                       opt_recv->dccpor_elapsed_time);
 181                         break;
 182                         /*
 183                          * From draft-ietf-dccp-spec-11.txt:
 184                          *
 185                          *      Option numbers 128 through 191 are for
 186                          *      options sent from the HC-Sender to the
 187                          *      HC-Receiver; option numbers 192 through 255
 188                          *      are for options sent from the HC-Receiver to
 189                          *      the HC-Sender.
 190                          */
 191                 case 128 ... 191: {
 192                         const u16 idx = value - options;
 193
 194                         if (ccid_hc_rx_parse_options(dp->dccps_hc_rx_ccid, sk,
 195                                                      opt, len, idx,
 196                                                      value) != 0)
 197                                 goto out_invalid_option;
 198                 }
 199                         break;
 200                 case 192 ... 255: {
 201                         const u16 idx = value - options;
 202
 203                         if (ccid_hc_tx_parse_options(dp->dccps_hc_tx_ccid, sk,
 204                                                      opt, len, idx,
 205                                                      value) != 0)
 206                                 goto out_invalid_option;
 207                 }
 208                         break;
 209                 default:
 210                         pr_info("DCCP(%p): option %d(len=%d) not "
 211                                 "implemented, ignoring\n",
 212                                 sk, opt, len);
 213                         break;
 214                 }
 215         }
 216
 217         return 0;
 218
 219 out_invalid_option:
 220         DCCP_INC_STATS_BH(DCCP_MIB_INVALIDOPT);
 221         DCCP_SKB_CB(skb)->dccpd_reset_code = DCCP_RESET_CODE_OPTION_ERROR;
 222         pr_info("DCCP(%p): invalid option %d, len=%d\n", sk, opt, len);
 223         return -1;
 224 }
 225
 226 static void dccp_encode_value_var(const u32 value, unsigned char *to,
 227                                   const unsigned int len)
 228 {
 229         if (len > 3)
 230                 *to++ = (value & 0xFF000000) >> 24;
 231         if (len > 2)
 232                 *to++ = (value & 0xFF0000) >> 16;
 233         if (len > 1)
 234                 *to++ = (value & 0xFF00) >> 8;
 235         if (len > 0)
 236                 *to++ = (value & 0xFF);
 237 }
 238
 239 static inline int dccp_ndp_len(const int ndp)
 240 {
 241         return likely(ndp <= 0xFF) ? 1 : ndp <= 0xFFFF ? 2 : 3;
 242 }
 243
 244 void dccp_insert_option(struct sock *sk, struct sk_buff *skb,
 245                         const unsigned char option,
 246                         const void *value, const unsigned char len)
 247 {
 248         unsigned char *to;
 249
 250         if (DCCP_SKB_CB(skb)->dccpd_opt_len + len + 2 > DCCP_MAX_OPT_LEN) {
 251                 LIMIT_NETDEBUG(KERN_INFO "DCCP: packet too small to insert "
 252                                "%d option!\n", option);
 253                 return;
 254         }
 255
 256         DCCP_SKB_CB(skb)->dccpd_opt_len += len + 2;
 257
 258         to    = skb_push(skb, len + 2);
 259         *to++ = option;
 260         *to++ = len + 2;
 261
 262         memcpy(to, value, len);
 263 }
 264
 265 EXPORT_SYMBOL_GPL(dccp_insert_option);
 266
 267 static void dccp_insert_option_ndp(struct sock *sk, struct sk_buff *skb)
 268 {
 269         struct dccp_sock *dp = dccp_sk(sk);
 270         int ndp = dp->dccps_ndp_count;
 271
 272         if (dccp_non_data_packet(skb))
 273                 ++dp->dccps_ndp_count;
 274         else
 275                 dp->dccps_ndp_count = 0;
 276
 277         if (ndp > 0) {
 278                 unsigned char *ptr;
 279                 const int ndp_len = dccp_ndp_len(ndp);
 280                 const int len = ndp_len + 2;
 281
 282                 if (DCCP_SKB_CB(skb)->dccpd_opt_len + len > DCCP_MAX_OPT_LEN)
 283                         return;
 284
 285                 DCCP_SKB_CB(skb)->dccpd_opt_len += len;
 286
 287                 ptr = skb_push(skb, len);
 288                 *ptr++ = DCCPO_NDP_COUNT;
 289                 *ptr++ = len;
 290                 dccp_encode_value_var(ndp, ptr, ndp_len);
 291         }
 292 }
 293
 294 static inline int dccp_elapsed_time_len(const u32 elapsed_time)
 295 {
 296         return elapsed_time == 0 ? 0 :
 297                elapsed_time <= 0xFF ? 1 :
 298                elapsed_time <= 0xFFFF ? 2 :
 299                elapsed_time <= 0xFFFFFF ? 3 : 4;
 300 }
 301
 302 void dccp_insert_option_elapsed_time(struct sock *sk,
 303                                      struct sk_buff *skb,
 304                                      u32 elapsed_time)
 305 {
 306 #ifdef DCCP_DEBUG
 307         struct dccp_sock *dp = dccp_sk(sk);
 308         const char *debug_prefix = dp->dccps_role == DCCP_ROLE_CLIENT ?
 309                                         "CLIENT TX opt: " : "server TX opt: ";
 310 #endif
 311         const int elapsed_time_len = dccp_elapsed_time_len(elapsed_time);
 312         const int len = 2 + elapsed_time_len;
 313         unsigned char *to;
 314
 315         /* If elapsed_time == 0... */
 316         if (elapsed_time_len == 2)
 317                 return;
 318
 319         if (DCCP_SKB_CB(skb)->dccpd_opt_len + len > DCCP_MAX_OPT_LEN) {
 320                 LIMIT_NETDEBUG(KERN_INFO "DCCP: packet too small to "
 321                                          "insert elapsed time!\n");
 322                 return;
 323         }
 324
 325         DCCP_SKB_CB(skb)->dccpd_opt_len += len;
 326
 327         to    = skb_push(skb, len);
 328         *to++ = DCCPO_ELAPSED_TIME;
 329         *to++ = len;
 330
 331         dccp_encode_value_var(elapsed_time, to, elapsed_time_len);
 332
 333         dccp_pr_debug("%sELAPSED_TIME=%u, len=%d, seqno=%llu\n",
 334                       debug_prefix, elapsed_time,
 335                       len,
 336                       (unsigned long long) DCCP_SKB_CB(skb)->dccpd_seq);
 337 }
 338
 339 EXPORT_SYMBOL(dccp_insert_option_elapsed_time);
 340
 341 static void dccp_insert_option_ack_vector(struct sock *sk, struct sk_buff *skb)
 342 {
 343         struct dccp_sock *dp = dccp_sk(sk);
 344 #ifdef DCCP_DEBUG
 345         const char *debug_prefix = dp->dccps_role == DCCP_ROLE_CLIENT ?
 346                                         "CLIENT TX opt: " : "server TX opt: ";
 347 #endif
 348         struct dccp_ackpkts *ap = dp->dccps_hc_rx_ackpkts;
 349         int len = ap->dccpap_buf_vector_len + 2;
 350         const u32 elapsed_time = jiffies_to_usecs(jiffies - ap->dccpap_time) / 10;
 351         unsigned char *to, *from;
 352
 353         if (elapsed_time != 0)
 354                 dccp_insert_option_elapsed_time(sk, skb, elapsed_time);
 355
 356         if (DCCP_SKB_CB(skb)->dccpd_opt_len + len > DCCP_MAX_OPT_LEN) {
 357                 LIMIT_NETDEBUG(KERN_INFO "DCCP: packet too small to "
 358                                          "insert ACK Vector!\n");
 359                 return;
 360         }
 361
 362         /*
 363          * XXX: now we have just one ack vector sent record, so
 364          * we have to wait for it to be cleared.
 365          *
 366          * Of course this is not acceptable, but this is just for
 367          * basic testing now.
 368          */
 369         if (ap->dccpap_ack_seqno != DCCP_MAX_SEQNO + 1)
 370                 return;
 371
 372         DCCP_SKB_CB(skb)->dccpd_opt_len += len;
 373
 374         to    = skb_push(skb, len);
 375         *to++ = DCCPO_ACK_VECTOR_0;
 376         *to++ = len;
 377
 378         len  = ap->dccpap_buf_vector_len;
 379         from = ap->dccpap_buf + ap->dccpap_buf_head;
 380
 381         /* Check if buf_head wraps */
 382         if (ap->dccpap_buf_head + len > ap->dccpap_buf_len) {
 383                 const unsigned int tailsize = (ap->dccpap_buf_len -
 384                                                ap->dccpap_buf_head);
 385
 386                 memcpy(to, from, tailsize);
 387                 to   += tailsize;
 388                 len  -= tailsize;
 389                 from = ap->dccpap_buf;
 390         }
 391
 392         memcpy(to, from, len);
 393         /*
 394          *      From draft-ietf-dccp-spec-11.txt:
 395          *
 396          *      For each acknowledgement it sends, the HC-Receiver will add an
 397          *      acknowledgement record.  ack_seqno will equal the HC-Receiver
 398          *      sequence number it used for the ack packet; ack_ptr will equal
 399          *      buf_head; ack_ackno will equal buf_ackno; and ack_nonce will
 400          *      equal buf_nonce.
 401          *
 402          * This implemention uses just one ack record for now.
 403          */
 404         ap->dccpap_ack_seqno      = DCCP_SKB_CB(skb)->dccpd_seq;
 405         ap->dccpap_ack_ptr        = ap->dccpap_buf_head;
 406         ap->dccpap_ack_ackno      = ap->dccpap_buf_ackno;
 407         ap->dccpap_ack_nonce      = ap->dccpap_buf_nonce;
 408         ap->dccpap_ack_vector_len = ap->dccpap_buf_vector_len;
 409
 410         dccp_pr_debug("%sACK Vector 0, len=%d, ack_seqno=%llu, "
 411                       "ack_ackno=%llu\n",
 412                       debug_prefix, ap->dccpap_ack_vector_len,
 413                       (unsigned long long) ap->dccpap_ack_seqno,
 414                       (unsigned long long) ap->dccpap_ack_ackno);
 415 }
 416
 417 static inline void dccp_insert_option_timestamp(struct sock *sk,
 418                                                 struct sk_buff *skb)
 419 {
 420         const u32 now = htonl(tcp_time_stamp);
 421         dccp_insert_option(sk, skb, DCCPO_TIMESTAMP, &now, sizeof(now));
 422 }
 423
 424 static void dccp_insert_option_timestamp_echo(struct sock *sk,
 425                                               struct sk_buff *skb)
 426 {
 427         struct dccp_sock *dp = dccp_sk(sk);
 428 #ifdef DCCP_DEBUG
 429         const char *debug_prefix = dp->dccps_role == DCCP_ROLE_CLIENT ?
 430                                         "CLIENT TX opt: " : "server TX opt: ";
 431 #endif
 432         u32 tstamp_echo;
 433         const u32 elapsed_time = jiffies_to_usecs(jiffies -
 434                                                   dp->dccps_timestamp_time) / 10;
 435         const int elapsed_time_len = dccp_elapsed_time_len(elapsed_time);
 436         const int len = 6 + elapsed_time_len;
 437         unsigned char *to;
 438
 439         if (DCCP_SKB_CB(skb)->dccpd_opt_len + len > DCCP_MAX_OPT_LEN) {
 440                 LIMIT_NETDEBUG(KERN_INFO "DCCP: packet too small to insert "
 441                                          "timestamp echo!\n");
 442                 return;
 443         }
 444
 445         DCCP_SKB_CB(skb)->dccpd_opt_len += len;
 446
 447         to    = skb_push(skb, len);
 448         *to++ = DCCPO_TIMESTAMP_ECHO;
 449         *to++ = len;
 450
 451         tstamp_echo = htonl(dp->dccps_timestamp_echo);
 452         memcpy(to, &tstamp_echo, 4);
 453         to += 4;
 454         dccp_encode_value_var(elapsed_time, to, elapsed_time_len);
 455
 456         dccp_pr_debug("%sTIMESTAMP_ECHO=%u, len=%d, seqno=%llu\n",
 457                       debug_prefix, dp->dccps_timestamp_echo,
 458                       len,
 459                       (unsigned long long) DCCP_SKB_CB(skb)->dccpd_seq);
 460
 461         dp->dccps_timestamp_echo = 0;
 462         dp->dccps_timestamp_time = 0;
 463 }
 464
 465 void dccp_insert_options(struct sock *sk, struct sk_buff *skb)
 466 {
 467         struct dccp_sock *dp = dccp_sk(sk);
 468
 469         DCCP_SKB_CB(skb)->dccpd_opt_len = 0;
 470
 471         if (dp->dccps_options.dccpo_send_ndp_count)
 472                 dccp_insert_option_ndp(sk, skb);
 473
 474         if (!dccp_packet_without_ack(skb)) {
 475                 if (dp->dccps_options.dccpo_send_ack_vector &&
 476                     (dp->dccps_hc_rx_ackpkts->dccpap_buf_ackno !=
 477                      DCCP_MAX_SEQNO + 1))
 478                         dccp_insert_option_ack_vector(sk, skb);
 479
 480                 dccp_insert_option_timestamp(sk, skb);
 481                 if (dp->dccps_timestamp_echo != 0)
 482                         dccp_insert_option_timestamp_echo(sk, skb);
 483         }
 484
 485         ccid_hc_rx_insert_options(dp->dccps_hc_rx_ccid, sk, skb);
 486         ccid_hc_tx_insert_options(dp->dccps_hc_tx_ccid, sk, skb);
 487
 488         /* XXX: insert other options when appropriate */
 489
 490         if (DCCP_SKB_CB(skb)->dccpd_opt_len != 0) {
 491                 /* The length of all options has to be a multiple of 4 */
 492                 int padding = DCCP_SKB_CB(skb)->dccpd_opt_len % 4;
 493
 494                 if (padding != 0) {
 495                         padding = 4 - padding;
 496                         memset(skb_push(skb, padding), 0, padding);
 497                         DCCP_SKB_CB(skb)->dccpd_opt_len += padding;
 498                 }
 499         }
 500 }
 501
 502 struct dccp_ackpkts *dccp_ackpkts_alloc(unsigned int len, int priority)
 503 {
 504         struct dccp_ackpkts *ap = kmalloc(sizeof(*ap) + len, priority);
 505
 506         if (ap != NULL) {
 507 #ifdef DCCP_DEBUG
 508                 memset(ap->dccpap_buf, 0xFF, len);
 509 #endif
 510                 ap->dccpap_buf_len   = len;
 511                 ap->dccpap_buf_head  =
 512                         ap->dccpap_buf_tail =
 513                                 ap->dccpap_buf_len - 1;
 514                 ap->dccpap_buf_ackno =
 515                         ap->dccpap_ack_ackno =
 516                                 ap->dccpap_ack_seqno = DCCP_MAX_SEQNO + 1;
 517                 ap->dccpap_buf_nonce = ap->dccpap_buf_nonce = 0;
 518                 ap->dccpap_ack_ptr   = 0;
 519                 ap->dccpap_time      = 0;
 520                 ap->dccpap_buf_vector_len = ap->dccpap_ack_vector_len = 0;
 521         }
 522
 523         return ap;
 524 }
 525
 526 void dccp_ackpkts_free(struct dccp_ackpkts *ap)
 527 {
 528         if (ap != NULL) {
 529 #ifdef DCCP_DEBUG
 530                 memset(ap, 0xFF, sizeof(*ap) + ap->dccpap_buf_len);
 531 #endif
 532                 kfree(ap);
 533         }
 534 }
 535
 536 static inline u8 dccp_ackpkts_state(const struct dccp_ackpkts *ap,
 537                                     const unsigned int index)
 538 {
 539         return ap->dccpap_buf[index] & DCCP_ACKPKTS_STATE_MASK;
 540 }
 541
 542 static inline u8 dccp_ackpkts_len(const struct dccp_ackpkts *ap,
 543                                   const unsigned int index)
 544 {
 545         return ap->dccpap_buf[index] & DCCP_ACKPKTS_LEN_MASK;
 546 }
 547
 548 /*
 549  * If several packets are missing, the HC-Receiver may prefer to enter multiple
 550  * bytes with run length 0, rather than a single byte with a larger run length;
 551  * this simplifies table updates if one of the missing packets arrives.
 552  */
 553 static inline int dccp_ackpkts_set_buf_head_state(struct dccp_ackpkts *ap,
 554                                                   const unsigned int packets,
 555                                                   const unsigned char state)
 556 {
 557         unsigned int gap;
 558         signed long new_head;
 559
 560         if (ap->dccpap_buf_vector_len + packets > ap->dccpap_buf_len)
 561                 return -ENOBUFS;
 562
 563         gap      = packets - 1;
 564         new_head = ap->dccpap_buf_head - packets;
 565
 566         if (new_head < 0) {
 567                 if (gap > 0) {
 568                         memset(ap->dccpap_buf, DCCP_ACKPKTS_STATE_NOT_RECEIVED,
 569                                gap + new_head + 1);
 570                         gap = -new_head;
 571                 }
 572                 new_head += ap->dccpap_buf_len;
 573         }
 574
 575         ap->dccpap_buf_head = new_head;
 576
 577         if (gap > 0)
 578                 memset(ap->dccpap_buf + ap->dccpap_buf_head + 1,
 579                        DCCP_ACKPKTS_STATE_NOT_RECEIVED, gap);
 580
 581         ap->dccpap_buf[ap->dccpap_buf_head] = state;
 582         ap->dccpap_buf_vector_len += packets;
 583         return 0;
 584 }
 585
 586 /*
 587  * Implements the draft-ietf-dccp-spec-11.txt Appendix A
 588  */
 589 int dccp_ackpkts_add(struct dccp_ackpkts *ap, u64 ackno, u8 state)
 590 {
 591         /*
 592          * Check at the right places if the buffer is full, if it is, tell the
 593          * caller to start dropping packets till the HC-Sender acks our ACK
 594          * vectors, when we will free up space in dccpap_buf.
 595          *
 596          * We may well decide to do buffer compression, etc, but for now lets
 597          * just drop.
 598          *
 599          * From Appendix A:
 600          *
 601          *      Of course, the circular buffer may overflow, either when the
 602          *      HC-Sender is sending data at a very high rate, when the
 603          *      HC-Receiver's acknowledgements are not reaching the HC-Sender,
 604          *      or when the HC-Sender is forgetting to acknowledge those acks
 605          *      (so the HC-Receiver is unable to clean up old state). In this
 606          *      case, the HC-Receiver should either compress the buffer (by
 607          *      increasing run lengths when possible), transfer its state to
 608          *      a larger buffer, or, as a last resort, drop all received
 609          *      packets, without processing them whatsoever, until its buffer
 610          *      shrinks again.
 611          */
 612
 613         /* See if this is the first ackno being inserted */
 614         if (ap->dccpap_buf_vector_len == 0) {
 615                 ap->dccpap_buf[ap->dccpap_buf_head] = state;
 616                 ap->dccpap_buf_vector_len = 1;
 617         } else if (after48(ackno, ap->dccpap_buf_ackno)) {
 618                 const u64 delta = dccp_delta_seqno(ap->dccpap_buf_ackno,
 619                                                    ackno);
 620
 621                 /*
 622                  * Look if the state of this packet is the same as the
 623                  * previous ackno and if so if we can bump the head len.
 624                  */
 625                 if (delta == 1 &&
 626                     dccp_ackpkts_state(ap, ap->dccpap_buf_head) == state &&
 627                     (dccp_ackpkts_len(ap, ap->dccpap_buf_head) <
 628                      DCCP_ACKPKTS_LEN_MASK))
 629                         ap->dccpap_buf[ap->dccpap_buf_head]++;
 630                 else if (dccp_ackpkts_set_buf_head_state(ap, delta, state))
 631                         return -ENOBUFS;
 632         } else {
 633                 /*
 634                  * A.1.2.  Old Packets
 635                  *
 636                  *      When a packet with Sequence Number S arrives, and
 637                  *      S <= buf_ackno, the HC-Receiver will scan the table
 638                  *      for the byte corresponding to S. (Indexing structures
 639                  *      could reduce the complexity of this scan.)
 640                  */
 641                 u64 delta = dccp_delta_seqno(ackno, ap->dccpap_buf_ackno);
 642                 unsigned int index = ap->dccpap_buf_head;
 643
 644                 while (1) {
 645                         const u8 len = dccp_ackpkts_len(ap, index);
 646                         const u8 state = dccp_ackpkts_state(ap, index);
 647                         /*
 648                          * valid packets not yet in dccpap_buf have a reserved
 649                          * entry, with a len equal to 0.
 650                          */
 651                         if (state == DCCP_ACKPKTS_STATE_NOT_RECEIVED &&
 652                             len == 0 && delta == 0) { /* Found our
 653                                                          reserved seat! */
 654                                 dccp_pr_debug("Found %llu reserved seat!\n",
 655                                               (unsigned long long) ackno);
 656                                 ap->dccpap_buf[index] = state;
 657                                 goto out;
 658                         }
 659                         /* len == 0 means one packet */
 660                         if (delta < len + 1)
 661                                 goto out_duplicate;
 662
 663                         delta -= len + 1;
 664                         if (++index == ap->dccpap_buf_len)
 665                                 index = 0;
 666                 }
 667         }
 668
 669         ap->dccpap_buf_ackno = ackno;
 670         ap->dccpap_time = jiffies;
 671 out:
 672         dccp_pr_debug("");
 673         dccp_ackpkts_print(ap);
 674         return 0;
 675
 676 out_duplicate:
 677         /* Duplicate packet */
 678         dccp_pr_debug("Received a dup or already considered lost "
 679                       "packet: %llu\n", (unsigned long long) ackno);
 680         return -EILSEQ;
 681 }
 682
 683 #ifdef DCCP_DEBUG
 684 void dccp_ackvector_print(const u64 ackno, const unsigned char *vector,
 685                           int len)
 686 {
 687         if (!dccp_debug)
 688                 return;
 689
 690         printk("ACK vector len=%d, ackno=%llu |", len,
 691                (unsigned long long) ackno);
 692
 693         while (len--) {
 694                 const u8 state = (*vector & DCCP_ACKPKTS_STATE_MASK) >> 6;
 695                 const u8 rl = (*vector & DCCP_ACKPKTS_LEN_MASK);
 696
 697                 printk("%d,%d|", state, rl);
 698                 ++vector;
 699         }
 700
 701         printk("\n");
 702 }
 703
 704 void dccp_ackpkts_print(const struct dccp_ackpkts *ap)
 705 {
 706         dccp_ackvector_print(ap->dccpap_buf_ackno,
 707                              ap->dccpap_buf + ap->dccpap_buf_head,
 708                              ap->dccpap_buf_vector_len);
 709 }
 710 #endif
 711
 712 static void dccp_ackpkts_trow_away_ack_record(struct dccp_ackpkts *ap)
 713 {
 714         /*
 715          * As we're keeping track of the ack vector size
 716          * (dccpap_buf_vector_len) and the sent ack vector size
 717          * (dccpap_ack_vector_len) we don't need dccpap_buf_tail at all, but
 718          * keep this code here as in the future we'll implement a vector of
 719          * ack records, as suggested in draft-ietf-dccp-spec-11.txt
 720          * Appendix A. -acme
 721          */
 722 #if 0
 723         ap->dccpap_buf_tail = ap->dccpap_ack_ptr + 1;
 724         if (ap->dccpap_buf_tail >= ap->dccpap_buf_len)
 725                 ap->dccpap_buf_tail -= ap->dccpap_buf_len;
 726 #endif
 727         ap->dccpap_buf_vector_len -= ap->dccpap_ack_vector_len;
 728 }
 729
 730 void dccp_ackpkts_check_rcv_ackno(struct dccp_ackpkts *ap, struct sock *sk,
 731                                  u64 ackno)
 732 {
 733         /* Check if we actually sent an ACK vector */
 734         if (ap->dccpap_ack_seqno == DCCP_MAX_SEQNO + 1)
 735                 return;
 736
 737         if (ackno == ap->dccpap_ack_seqno) {
 738 #ifdef DCCP_DEBUG
 739                 struct dccp_sock *dp = dccp_sk(sk);
 740                 const char *debug_prefix = dp->dccps_role == DCCP_ROLE_CLIENT ?
 741                                         "CLIENT rx ack: " : "server rx ack: ";
 742 #endif
 743                 dccp_pr_debug("%sACK packet 0, len=%d, ack_seqno=%llu, "
 744                               "ack_ackno=%llu, ACKED!\n",
 745                               debug_prefix, 1,
 746                               (unsigned long long) ap->dccpap_ack_seqno,
 747                               (unsigned long long) ap->dccpap_ack_ackno);
 748                 dccp_ackpkts_trow_away_ack_record(ap);
 749                 ap->dccpap_ack_seqno = DCCP_MAX_SEQNO + 1;
 750         }
 751 }
 752
 753 static void dccp_ackpkts_check_rcv_ackvector(struct dccp_ackpkts *ap,
 754                                              struct sock *sk, u64 ackno,
 755                                              const unsigned char len,
 756                                              const unsigned char *vector)
 757 {
 758         unsigned char i;
 759
 760         /* Check if we actually sent an ACK vector */
 761         if (ap->dccpap_ack_seqno == DCCP_MAX_SEQNO + 1)
 762                 return;
 763         /*
 764          * We're in the receiver half connection, so if the received an ACK
 765          * vector ackno (e.g. 50) before dccpap_ack_seqno (e.g. 52), we're
 766          * not interested.
 767          *
 768          * Extra explanation with example:
 769          *
 770          * if we received an ACK vector with ackno 50, it can only be acking
 771          * 50, 49, 48, etc, not 52 (the seqno for the ACK vector we sent).
 772          */
 773         /* dccp_pr_debug("is %llu < %llu? ", ackno, ap->dccpap_ack_seqno); */
 774         if (before48(ackno, ap->dccpap_ack_seqno)) {
 775                 /* dccp_pr_debug_cat("yes\n"); */
 776                 return;
 777         }
 778         /* dccp_pr_debug_cat("no\n"); */
 779
 780         i = len;
 781         while (i--) {
 782                 const u8 rl = (*vector & DCCP_ACKPKTS_LEN_MASK);
 783                 u64 ackno_end_rl;
 784
 785                 dccp_set_seqno(&ackno_end_rl, ackno - rl);
 786
 787                 /*
 788                  * dccp_pr_debug("is %llu <= %llu <= %llu? ", ackno_end_rl,
 789                  * ap->dccpap_ack_seqno, ackno);
 790                  */
 791                 if (between48(ap->dccpap_ack_seqno, ackno_end_rl, ackno)) {
 792                         const u8 state = (*vector &
 793                                           DCCP_ACKPKTS_STATE_MASK) >> 6;
 794                         /* dccp_pr_debug_cat("yes\n"); */
 795
 796                         if (state != DCCP_ACKPKTS_STATE_NOT_RECEIVED) {
 797 #ifdef DCCP_DEBUG
 798                                 struct dccp_sock *dp = dccp_sk(sk);
 799                                 const char *debug_prefix =
 800                                         dp->dccps_role == DCCP_ROLE_CLIENT ?
 801                                         "CLIENT rx ack: " : "server rx ack: ";
 802 #endif
 803                                 dccp_pr_debug("%sACK vector 0, len=%d, "
 804                                               "ack_seqno=%llu, ack_ackno=%llu, "
 805                                               "ACKED!\n",
 806                                               debug_prefix, len,
 807                                               (unsigned long long)
 808                                               ap->dccpap_ack_seqno,
 809                                               (unsigned long long)
 810                                               ap->dccpap_ack_ackno);
 811                                 dccp_ackpkts_trow_away_ack_record(ap);
 812                         }
 813                         /*
 814                          * If dccpap_ack_seqno was not received, no problem
 815                          * we'll send another ACK vector.
 816                          */
 817                         ap->dccpap_ack_seqno = DCCP_MAX_SEQNO + 1;
 818                         break;
 819                 }
 820                 /* dccp_pr_debug_cat("no\n"); */
 821
 822                 dccp_set_seqno(&ackno, ackno_end_rl - 1);
 823                 ++vector;
 824         }
 825 }