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 <iam4@cs.waikato.ac.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/config.h>
  15 #include <linux/dccp.h>
  16 #include <linux/module.h>
  17 #include <linux/types.h>
  18 #include <linux/kernel.h>
  19 #include <linux/skbuff.h>
  20
  21 #include "ccid.h"
  22 #include "dccp.h"
  23
  24 static void dccp_ackpkts_check_rcv_ackvector(struct dccp_ackpkts *ap,
  25                                              struct sock *sk,
  26                                              const u64 ackno,
  27                                              const unsigned char len,
  28                                              const unsigned char *vector);
  29
  30 /* stores the default values for new connection. may be changed with sysctl */
  31 static const struct dccp_options dccpo_default_values = {
  32         .dccpo_sequence_window    = DCCPF_INITIAL_SEQUENCE_WINDOW,
  33         .dccpo_ccid               = DCCPF_INITIAL_CCID,
  34         .dccpo_send_ack_vector    = DCCPF_INITIAL_SEND_ACK_VECTOR,
  35         .dccpo_send_ndp_count     = DCCPF_INITIAL_SEND_NDP_COUNT,
  36 };
  37
  38 void dccp_options_init(struct dccp_options *dccpo)
  39 {
  40         memcpy(dccpo, &dccpo_default_values, sizeof(*dccpo));
  41 }
  42
  43 static u32 dccp_decode_value_var(const unsigned char *bf, const u8 len)
  44 {
  45         u32 value = 0;
  46
  47         if (len > 3)
  48                 value += *bf++ << 24;
  49         if (len > 2)
  50                 value += *bf++ << 16;
  51         if (len > 1)
  52                 value += *bf++ << 8;
  53         if (len > 0)
  54                 value += *bf;
  55
  56         return value;
  57 }
  58
  59 int dccp_parse_options(struct sock *sk, struct sk_buff *skb)
  60 {
  61         struct dccp_sock *dp = dccp_sk(sk);
  62 #ifdef CONFIG_IP_DCCP_DEBUG
  63         const char *debug_prefix = dp->dccps_role == DCCP_ROLE_CLIENT ?
  64                                         "CLIENT rx opt: " : "server rx opt: ";
  65 #endif
  66         const struct dccp_hdr *dh = dccp_hdr(skb);
  67         const u8 pkt_type = DCCP_SKB_CB(skb)->dccpd_type;
  68         unsigned char *options = (unsigned char *)dh + dccp_hdr_len(skb);
  69         unsigned char *opt_ptr = options;
  70         const unsigned char *opt_end = (unsigned char *)dh +
  71                                         (dh->dccph_doff * 4);
  72         struct dccp_options_received *opt_recv = &dp->dccps_options_received;
  73         unsigned char opt, len;
  74         unsigned char *value;
  75         u32 elapsed_time;
  76
  77         memset(opt_recv, 0, sizeof(*opt_recv));
  78
  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_invalid_option;
  88
  89                         len = *opt_ptr++;
  90                         if (len < 3)
  91                                 goto out_invalid_option;
  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_invalid_option;
 102                 }
 103
 104                 switch (opt) {
 105                 case DCCPO_PADDING:
 106                         break;
 107                 case DCCPO_NDP_COUNT:
 108                         if (len > 3)
 109                                 goto out_invalid_option;
 110
 111                         opt_recv->dccpor_ndp = dccp_decode_value_var(value, len);
 112                         dccp_pr_debug("%sNDP count=%d\n", debug_prefix,
 113                                       opt_recv->dccpor_ndp);
 114                         break;
 115                 case DCCPO_ACK_VECTOR_0:
 116                         if (len > DCCP_MAX_ACK_VECTOR_LEN)
 117                                 goto out_invalid_option;
 118
 119                         if (pkt_type == DCCP_PKT_DATA)
 120                                 continue;
 121
 122                         opt_recv->dccpor_ack_vector_len = len;
 123                         opt_recv->dccpor_ack_vector_idx = value - options;
 124
 125                         dccp_pr_debug("%sACK vector 0, len=%d, ack_ackno=%llu\n",
 126                                       debug_prefix, len,
 127                                       (unsigned long long)
 128                                       DCCP_SKB_CB(skb)->dccpd_ack_seq);
 129                         dccp_ackvector_print(DCCP_SKB_CB(skb)->dccpd_ack_seq,
 130                                              value, len);
 131                         dccp_ackpkts_check_rcv_ackvector(dp->dccps_hc_rx_ackpkts,
 132                                                          sk,
 133                                                  DCCP_SKB_CB(skb)->dccpd_ack_seq,
 134                                                          len, value);
 135                         break;
 136                 case DCCPO_TIMESTAMP:
 137                         if (len != 4)
 138                                 goto out_invalid_option;
 139
 140                         opt_recv->dccpor_timestamp = ntohl(*(u32 *)value);
 141
 142                         dp->dccps_timestamp_echo = opt_recv->dccpor_timestamp;
 143                         dccp_timestamp(sk, &dp->dccps_timestamp_time);
 144
 145                         dccp_pr_debug("%sTIMESTAMP=%u, ackno=%llu\n",
 146                                       debug_prefix, opt_recv->dccpor_timestamp,
 147                                       (unsigned long long)
 148                                       DCCP_SKB_CB(skb)->dccpd_ack_seq);
 149                         break;
 150                 case DCCPO_TIMESTAMP_ECHO:
 151                         if (len != 4 && len != 6 && len != 8)
 152                                 goto out_invalid_option;
 153
 154                         opt_recv->dccpor_timestamp_echo = ntohl(*(u32 *)value);
 155
 156                         dccp_pr_debug("%sTIMESTAMP_ECHO=%u, len=%d, ackno=%llu, ",
 157                                       debug_prefix,
 158                                       opt_recv->dccpor_timestamp_echo,
 159                                       len + 2,
 160                                       (unsigned long long)
 161                                       DCCP_SKB_CB(skb)->dccpd_ack_seq);
 162
 163
 164                         if (len == 4)
 165                                 break;
 166
 167                         if (len == 6)
 168                                 elapsed_time = ntohs(*(u16 *)(value + 4));
 169                         else
 170                                 elapsed_time = ntohl(*(u32 *)(value + 4));
 171
 172                         /* Give precedence to the biggest ELAPSED_TIME */
 173                         if (elapsed_time > opt_recv->dccpor_elapsed_time)
 174                                 opt_recv->dccpor_elapsed_time = elapsed_time;
 175                         break;
 176                 case DCCPO_ELAPSED_TIME:
 177                         if (len != 2 && len != 4)
 178                                 goto out_invalid_option;
 179
 180                         if (pkt_type == DCCP_PKT_DATA)
 181                                 continue;
 182
 183                         if (len == 2)
 184                                 elapsed_time = ntohs(*(u16 *)value);
 185                         else
 186                                 elapsed_time = ntohl(*(u32 *)value);
 187
 188                         if (elapsed_time > opt_recv->dccpor_elapsed_time)
 189                                 opt_recv->dccpor_elapsed_time = elapsed_time;
 190
 191                         dccp_pr_debug("%sELAPSED_TIME=%d\n", debug_prefix,
 192                                       elapsed_time);
 193                         break;
 194                         /*
 195                          * From draft-ietf-dccp-spec-11.txt:
 196                          *
 197                          *      Option numbers 128 through 191 are for
 198                          *      options sent from the HC-Sender to the
 199                          *      HC-Receiver; option numbers 192 through 255
 200                          *      are for options sent from the HC-Receiver to
 201                          *      the HC-Sender.
 202                          */
 203                 case 128 ... 191: {
 204                         const u16 idx = value - options;
 205
 206                         if (ccid_hc_rx_parse_options(dp->dccps_hc_rx_ccid, sk,
 207                                                      opt, len, idx,
 208                                                      value) != 0)
 209                                 goto out_invalid_option;
 210                 }
 211                         break;
 212                 case 192 ... 255: {
 213                         const u16 idx = value - options;
 214
 215                         if (ccid_hc_tx_parse_options(dp->dccps_hc_tx_ccid, sk,
 216                                                      opt, len, idx,
 217                                                      value) != 0)
 218                                 goto out_invalid_option;
 219                 }
 220                         break;
 221                 default:
 222                         pr_info("DCCP(%p): option %d(len=%d) not "
 223                                 "implemented, ignoring\n",
 224                                 sk, opt, len);
 225                         break;
 226                 }
 227         }
 228
 229         return 0;
 230
 231 out_invalid_option:
 232         DCCP_INC_STATS_BH(DCCP_MIB_INVALIDOPT);
 233         DCCP_SKB_CB(skb)->dccpd_reset_code = DCCP_RESET_CODE_OPTION_ERROR;
 234         pr_info("DCCP(%p): invalid option %d, len=%d\n", sk, opt, len);
 235         return -1;
 236 }
 237
 238 static void dccp_encode_value_var(const u32 value, unsigned char *to,
 239                                   const unsigned int len)
 240 {
 241         if (len > 3)
 242                 *to++ = (value & 0xFF000000) >> 24;
 243         if (len > 2)
 244                 *to++ = (value & 0xFF0000) >> 16;
 245         if (len > 1)
 246                 *to++ = (value & 0xFF00) >> 8;
 247         if (len > 0)
 248                 *to++ = (value & 0xFF);
 249 }
 250
 251 static inline int dccp_ndp_len(const int ndp)
 252 {
 253         return likely(ndp <= 0xFF) ? 1 : ndp <= 0xFFFF ? 2 : 3;
 254 }
 255
 256 void dccp_insert_option(struct sock *sk, struct sk_buff *skb,
 257                         const unsigned char option,
 258                         const void *value, const unsigned char len)
 259 {
 260         unsigned char *to;
 261
 262         if (DCCP_SKB_CB(skb)->dccpd_opt_len + len + 2 > DCCP_MAX_OPT_LEN) {
 263                 LIMIT_NETDEBUG(KERN_INFO "DCCP: packet too small to insert "
 264                                "%d option!\n", option);
 265                 return;
 266         }
 267
 268         DCCP_SKB_CB(skb)->dccpd_opt_len += len + 2;
 269
 270         to    = skb_push(skb, len + 2);
 271         *to++ = option;
 272         *to++ = len + 2;
 273
 274         memcpy(to, value, len);
 275 }
 276
 277 EXPORT_SYMBOL_GPL(dccp_insert_option);
 278
 279 static void dccp_insert_option_ndp(struct sock *sk, struct sk_buff *skb)
 280 {
 281         struct dccp_sock *dp = dccp_sk(sk);
 282         int ndp = dp->dccps_ndp_count;
 283
 284         if (dccp_non_data_packet(skb))
 285                 ++dp->dccps_ndp_count;
 286         else
 287                 dp->dccps_ndp_count = 0;
 288
 289         if (ndp > 0) {
 290                 unsigned char *ptr;
 291                 const int ndp_len = dccp_ndp_len(ndp);
 292                 const int len = ndp_len + 2;
 293
 294                 if (DCCP_SKB_CB(skb)->dccpd_opt_len + len > DCCP_MAX_OPT_LEN)
 295                         return;
 296
 297                 DCCP_SKB_CB(skb)->dccpd_opt_len += len;
 298
 299                 ptr = skb_push(skb, len);
 300                 *ptr++ = DCCPO_NDP_COUNT;
 301                 *ptr++ = len;
 302                 dccp_encode_value_var(ndp, ptr, ndp_len);
 303         }
 304 }
 305
 306 static inline int dccp_elapsed_time_len(const u32 elapsed_time)
 307 {
 308         return elapsed_time == 0 ? 0 : elapsed_time <= 0xFFFF ? 2 : 4;
 309 }
 310
 311 void dccp_insert_option_elapsed_time(struct sock *sk,
 312                                      struct sk_buff *skb,
 313                                      u32 elapsed_time)
 314 {
 315 #ifdef CONFIG_IP_DCCP_DEBUG
 316         struct dccp_sock *dp = dccp_sk(sk);
 317         const char *debug_prefix = dp->dccps_role == DCCP_ROLE_CLIENT ?
 318                                         "CLIENT TX opt: " : "server TX opt: ";
 319 #endif
 320         const int elapsed_time_len = dccp_elapsed_time_len(elapsed_time);
 321         const int len = 2 + elapsed_time_len;
 322         unsigned char *to;
 323
 324         if (elapsed_time_len == 0)
 325                 return;
 326
 327         if (DCCP_SKB_CB(skb)->dccpd_opt_len + len > DCCP_MAX_OPT_LEN) {
 328                 LIMIT_NETDEBUG(KERN_INFO "DCCP: packet too small to "
 329                                          "insert elapsed time!\n");
 330                 return;
 331         }
 332
 333         DCCP_SKB_CB(skb)->dccpd_opt_len += len;
 334
 335         to    = skb_push(skb, len);
 336         *to++ = DCCPO_ELAPSED_TIME;
 337         *to++ = len;
 338
 339         if (elapsed_time_len == 2) {
 340                 const u16 var16 = htons((u16)elapsed_time);
 341                 memcpy(to, &var16, 2);
 342         } else {
 343                 const u32 var32 = htonl(elapsed_time);
 344                 memcpy(to, &var32, 4);
 345         }
 346
 347         dccp_pr_debug("%sELAPSED_TIME=%u, len=%d, seqno=%llu\n",
 348                       debug_prefix, elapsed_time,
 349                       len,
 350                       (unsigned long long) DCCP_SKB_CB(skb)->dccpd_seq);
 351 }
 352
 353 EXPORT_SYMBOL_GPL(dccp_insert_option_elapsed_time);
 354
 355 static void dccp_insert_option_ack_vector(struct sock *sk, struct sk_buff *skb)
 356 {
 357         struct dccp_sock *dp = dccp_sk(sk);
 358 #ifdef CONFIG_IP_DCCP_DEBUG
 359         const char *debug_prefix = dp->dccps_role == DCCP_ROLE_CLIENT ?
 360                                         "CLIENT TX opt: " : "server TX opt: ";
 361 #endif
 362         struct dccp_ackpkts *ap = dp->dccps_hc_rx_ackpkts;
 363         int len = ap->dccpap_buf_vector_len + 2;
 364         struct timeval now;
 365         u32 elapsed_time;
 366         unsigned char *to, *from;
 367
 368         dccp_timestamp(sk, &now);
 369         elapsed_time = timeval_delta(&now, &ap->dccpap_time) / 10;
 370
 371         if (elapsed_time != 0)
 372                 dccp_insert_option_elapsed_time(sk, skb, elapsed_time);
 373
 374         if (DCCP_SKB_CB(skb)->dccpd_opt_len + len > DCCP_MAX_OPT_LEN) {
 375                 LIMIT_NETDEBUG(KERN_INFO "DCCP: packet too small to "
 376                                          "insert ACK Vector!\n");
 377                 return;
 378         }
 379
 380         /*
 381          * XXX: now we have just one ack vector sent record, so
 382          * we have to wait for it to be cleared.
 383          *
 384          * Of course this is not acceptable, but this is just for
 385          * basic testing now.
 386          */
 387         if (ap->dccpap_ack_seqno != DCCP_MAX_SEQNO + 1)
 388                 return;
 389
 390         DCCP_SKB_CB(skb)->dccpd_opt_len += len;
 391
 392         to    = skb_push(skb, len);
 393         *to++ = DCCPO_ACK_VECTOR_0;
 394         *to++ = len;
 395
 396         len  = ap->dccpap_buf_vector_len;
 397         from = ap->dccpap_buf + ap->dccpap_buf_head;
 398
 399         /* Check if buf_head wraps */
 400         if (ap->dccpap_buf_head + len > ap->dccpap_buf_len) {
 401                 const unsigned int tailsize = (ap->dccpap_buf_len -
 402                                                ap->dccpap_buf_head);
 403
 404                 memcpy(to, from, tailsize);
 405                 to   += tailsize;
 406                 len  -= tailsize;
 407                 from = ap->dccpap_buf;
 408         }
 409
 410         memcpy(to, from, len);
 411         /*
 412          *      From draft-ietf-dccp-spec-11.txt:
 413          *
 414          *      For each acknowledgement it sends, the HC-Receiver will add an
 415          *      acknowledgement record.  ack_seqno will equal the HC-Receiver
 416          *      sequence number it used for the ack packet; ack_ptr will equal
 417          *      buf_head; ack_ackno will equal buf_ackno; and ack_nonce will
 418          *      equal buf_nonce.
 419          *
 420          * This implemention uses just one ack record for now.
 421          */
 422         ap->dccpap_ack_seqno      = DCCP_SKB_CB(skb)->dccpd_seq;
 423         ap->dccpap_ack_ptr        = ap->dccpap_buf_head;
 424         ap->dccpap_ack_ackno      = ap->dccpap_buf_ackno;
 425         ap->dccpap_ack_nonce      = ap->dccpap_buf_nonce;
 426         ap->dccpap_ack_vector_len = ap->dccpap_buf_vector_len;
 427
 428         dccp_pr_debug("%sACK Vector 0, len=%d, ack_seqno=%llu, "
 429                       "ack_ackno=%llu\n",
 430                       debug_prefix, ap->dccpap_ack_vector_len,
 431                       (unsigned long long) ap->dccpap_ack_seqno,
 432                       (unsigned long long) ap->dccpap_ack_ackno);
 433 }
 434
 435 void dccp_timestamp(const struct sock *sk, struct timeval *tv)
 436 {
 437         const struct dccp_sock *dp = dccp_sk(sk);
 438
 439         do_gettimeofday(tv);
 440         tv->tv_sec  -= dp->dccps_epoch.tv_sec;
 441         tv->tv_usec -= dp->dccps_epoch.tv_usec;
 442
 443         while (tv->tv_usec < 0) {
 444                 tv->tv_sec--;
 445                 tv->tv_usec += USEC_PER_SEC;
 446         }
 447 }
 448
 449 EXPORT_SYMBOL_GPL(dccp_timestamp);
 450
 451 void dccp_insert_option_timestamp(struct sock *sk, struct sk_buff *skb)
 452 {
 453         struct timeval tv;
 454         u32 now;
 455
 456         dccp_timestamp(sk, &tv);
 457         now = timeval_usecs(&tv) / 10;
 458         /* yes this will overflow but that is the point as we want a
 459          * 10 usec 32 bit timer which mean it wraps every 11.9 hours */
 460
 461         now = htonl(now);
 462         dccp_insert_option(sk, skb, DCCPO_TIMESTAMP, &now, sizeof(now));
 463 }
 464
 465 EXPORT_SYMBOL_GPL(dccp_insert_option_timestamp);
 466
 467 static void dccp_insert_option_timestamp_echo(struct sock *sk,
 468                                               struct sk_buff *skb)
 469 {
 470         struct dccp_sock *dp = dccp_sk(sk);
 471 #ifdef CONFIG_IP_DCCP_DEBUG
 472         const char *debug_prefix = dp->dccps_role == DCCP_ROLE_CLIENT ?
 473                                         "CLIENT TX opt: " : "server TX opt: ";
 474 #endif
 475         struct timeval now;
 476         u32 tstamp_echo;
 477         u32 elapsed_time;
 478         int len, elapsed_time_len;
 479         unsigned char *to;
 480
 481         dccp_timestamp(sk, &now);
 482         elapsed_time = timeval_delta(&now, &dp->dccps_timestamp_time) / 10;
 483         elapsed_time_len = dccp_elapsed_time_len(elapsed_time);
 484         len = 6 + elapsed_time_len;
 485
 486         if (DCCP_SKB_CB(skb)->dccpd_opt_len + len > DCCP_MAX_OPT_LEN) {
 487                 LIMIT_NETDEBUG(KERN_INFO "DCCP: packet too small to insert "
 488                                          "timestamp echo!\n");
 489                 return;
 490         }
 491
 492         DCCP_SKB_CB(skb)->dccpd_opt_len += len;
 493
 494         to    = skb_push(skb, len);
 495         *to++ = DCCPO_TIMESTAMP_ECHO;
 496         *to++ = len;
 497
 498         tstamp_echo = htonl(dp->dccps_timestamp_echo);
 499         memcpy(to, &tstamp_echo, 4);
 500         to += 4;
 501
 502         if (elapsed_time_len == 2) {
 503                 const u16 var16 = htons((u16)elapsed_time);
 504                 memcpy(to, &var16, 2);
 505         } else if (elapsed_time_len == 4) {
 506                 const u32 var32 = htonl(elapsed_time);
 507                 memcpy(to, &var32, 4);
 508         }
 509
 510         dccp_pr_debug("%sTIMESTAMP_ECHO=%u, len=%d, seqno=%llu\n",
 511                       debug_prefix, dp->dccps_timestamp_echo,
 512                       len,
 513                       (unsigned long long) DCCP_SKB_CB(skb)->dccpd_seq);
 514
 515         dp->dccps_timestamp_echo = 0;
 516         dp->dccps_timestamp_time.tv_sec = 0;
 517         dp->dccps_timestamp_time.tv_usec = 0;
 518 }
 519
 520 void dccp_insert_options(struct sock *sk, struct sk_buff *skb)
 521 {
 522         struct dccp_sock *dp = dccp_sk(sk);
 523
 524         DCCP_SKB_CB(skb)->dccpd_opt_len = 0;
 525
 526         if (dp->dccps_options.dccpo_send_ndp_count)
 527                 dccp_insert_option_ndp(sk, skb);
 528
 529         if (!dccp_packet_without_ack(skb)) {
 530                 if (dp->dccps_options.dccpo_send_ack_vector &&
 531                     (dp->dccps_hc_rx_ackpkts->dccpap_buf_ackno !=
 532                      DCCP_MAX_SEQNO + 1))
 533                         dccp_insert_option_ack_vector(sk, skb);
 534                 if (dp->dccps_timestamp_echo != 0)
 535                         dccp_insert_option_timestamp_echo(sk, skb);
 536         }
 537
 538         if (dp->dccps_hc_rx_insert_options) {
 539                 ccid_hc_rx_insert_options(dp->dccps_hc_rx_ccid, sk, skb);
 540                 dp->dccps_hc_rx_insert_options = 0;
 541         }
 542         if (dp->dccps_hc_tx_insert_options) {
 543                 ccid_hc_tx_insert_options(dp->dccps_hc_tx_ccid, sk, skb);
 544                 dp->dccps_hc_tx_insert_options = 0;
 545         }
 546
 547         /* XXX: insert other options when appropriate */
 548
 549         if (DCCP_SKB_CB(skb)->dccpd_opt_len != 0) {
 550                 /* The length of all options has to be a multiple of 4 */
 551                 int padding = DCCP_SKB_CB(skb)->dccpd_opt_len % 4;
 552
 553                 if (padding != 0) {
 554                         padding = 4 - padding;
 555                         memset(skb_push(skb, padding), 0, padding);
 556                         DCCP_SKB_CB(skb)->dccpd_opt_len += padding;
 557                 }
 558         }
 559 }
 560
 561 struct dccp_ackpkts *dccp_ackpkts_alloc(const unsigned int len,
 562                                         const unsigned int __nocast priority)
 563 {
 564         struct dccp_ackpkts *ap = kmalloc(sizeof(*ap) + len, priority);
 565
 566         if (ap != NULL) {
 567 #ifdef CONFIG_IP_DCCP_DEBUG
 568                 memset(ap->dccpap_buf, 0xFF, len);
 569 #endif
 570                 ap->dccpap_buf_len   = len;
 571                 ap->dccpap_buf_head  =
 572                         ap->dccpap_buf_tail =
 573                                 ap->dccpap_buf_len - 1;
 574                 ap->dccpap_buf_ackno =
 575                         ap->dccpap_ack_ackno =
 576                                 ap->dccpap_ack_seqno = DCCP_MAX_SEQNO + 1;
 577                 ap->dccpap_buf_nonce = ap->dccpap_buf_nonce = 0;
 578                 ap->dccpap_ack_ptr   = 0;
 579                 ap->dccpap_time.tv_sec = 0;
 580                 ap->dccpap_time.tv_usec = 0;
 581                 ap->dccpap_buf_vector_len = ap->dccpap_ack_vector_len = 0;
 582         }
 583
 584         return ap;
 585 }
 586
 587 void dccp_ackpkts_free(struct dccp_ackpkts *ap)
 588 {
 589         if (ap != NULL) {
 590 #ifdef CONFIG_IP_DCCP_DEBUG
 591                 memset(ap, 0xFF, sizeof(*ap) + ap->dccpap_buf_len);
 592 #endif
 593                 kfree(ap);
 594         }
 595 }
 596
 597 static inline u8 dccp_ackpkts_state(const struct dccp_ackpkts *ap,
 598                                     const unsigned int index)
 599 {
 600         return ap->dccpap_buf[index] & DCCP_ACKPKTS_STATE_MASK;
 601 }
 602
 603 static inline u8 dccp_ackpkts_len(const struct dccp_ackpkts *ap,
 604                                   const unsigned int index)
 605 {
 606         return ap->dccpap_buf[index] & DCCP_ACKPKTS_LEN_MASK;
 607 }
 608
 609 /*
 610  * If several packets are missing, the HC-Receiver may prefer to enter multiple
 611  * bytes with run length 0, rather than a single byte with a larger run length;
 612  * this simplifies table updates if one of the missing packets arrives.
 613  */
 614 static inline int dccp_ackpkts_set_buf_head_state(struct dccp_ackpkts *ap,
 615                                                   const unsigned int packets,
 616                                                   const unsigned char state)
 617 {
 618         unsigned int gap;
 619         signed long new_head;
 620
 621         if (ap->dccpap_buf_vector_len + packets > ap->dccpap_buf_len)
 622                 return -ENOBUFS;
 623
 624         gap      = packets - 1;
 625         new_head = ap->dccpap_buf_head - packets;
 626
 627         if (new_head < 0) {
 628                 if (gap > 0) {
 629                         memset(ap->dccpap_buf, DCCP_ACKPKTS_STATE_NOT_RECEIVED,
 630                                gap + new_head + 1);
 631                         gap = -new_head;
 632                 }
 633                 new_head += ap->dccpap_buf_len;
 634         }
 635
 636         ap->dccpap_buf_head = new_head;
 637
 638         if (gap > 0)
 639                 memset(ap->dccpap_buf + ap->dccpap_buf_head + 1,
 640                        DCCP_ACKPKTS_STATE_NOT_RECEIVED, gap);
 641
 642         ap->dccpap_buf[ap->dccpap_buf_head] = state;
 643         ap->dccpap_buf_vector_len += packets;
 644         return 0;
 645 }
 646
 647 /*
 648  * Implements the draft-ietf-dccp-spec-11.txt Appendix A
 649  */
 650 int dccp_ackpkts_add(struct dccp_ackpkts *ap, const struct sock *sk,
 651                      u64 ackno, u8 state)
 652 {
 653         /*
 654          * Check at the right places if the buffer is full, if it is, tell the
 655          * caller to start dropping packets till the HC-Sender acks our ACK
 656          * vectors, when we will free up space in dccpap_buf.
 657          *
 658          * We may well decide to do buffer compression, etc, but for now lets
 659          * just drop.
 660          *
 661          * From Appendix A:
 662          *
 663          *      Of course, the circular buffer may overflow, either when the
 664          *      HC-Sender is sending data at a very high rate, when the
 665          *      HC-Receiver's acknowledgements are not reaching the HC-Sender,
 666          *      or when the HC-Sender is forgetting to acknowledge those acks
 667          *      (so the HC-Receiver is unable to clean up old state). In this
 668          *      case, the HC-Receiver should either compress the buffer (by
 669          *      increasing run lengths when possible), transfer its state to
 670          *      a larger buffer, or, as a last resort, drop all received
 671          *      packets, without processing them whatsoever, until its buffer
 672          *      shrinks again.
 673          */
 674
 675         /* See if this is the first ackno being inserted */
 676         if (ap->dccpap_buf_vector_len == 0) {
 677                 ap->dccpap_buf[ap->dccpap_buf_head] = state;
 678                 ap->dccpap_buf_vector_len = 1;
 679         } else if (after48(ackno, ap->dccpap_buf_ackno)) {
 680                 const u64 delta = dccp_delta_seqno(ap->dccpap_buf_ackno,
 681                                                    ackno);
 682
 683                 /*
 684                  * Look if the state of this packet is the same as the
 685                  * previous ackno and if so if we can bump the head len.
 686                  */
 687                 if (delta == 1 &&
 688                     dccp_ackpkts_state(ap, ap->dccpap_buf_head) == state &&
 689                     (dccp_ackpkts_len(ap, ap->dccpap_buf_head) <
 690                      DCCP_ACKPKTS_LEN_MASK))
 691                         ap->dccpap_buf[ap->dccpap_buf_head]++;
 692                 else if (dccp_ackpkts_set_buf_head_state(ap, delta, state))
 693                         return -ENOBUFS;
 694         } else {
 695                 /*
 696                  * A.1.2.  Old Packets
 697                  *
 698                  *      When a packet with Sequence Number S arrives, and
 699                  *      S <= buf_ackno, the HC-Receiver will scan the table
 700                  *      for the byte corresponding to S. (Indexing structures
 701                  *      could reduce the complexity of this scan.)
 702                  */
 703                 u64 delta = dccp_delta_seqno(ackno, ap->dccpap_buf_ackno);
 704                 unsigned int index = ap->dccpap_buf_head;
 705
 706                 while (1) {
 707                         const u8 len = dccp_ackpkts_len(ap, index);
 708                         const u8 state = dccp_ackpkts_state(ap, index);
 709                         /*
 710                          * valid packets not yet in dccpap_buf have a reserved
 711                          * entry, with a len equal to 0.
 712                          */
 713                         if (state == DCCP_ACKPKTS_STATE_NOT_RECEIVED &&
 714                             len == 0 && delta == 0) { /* Found our
 715                                                          reserved seat! */
 716                                 dccp_pr_debug("Found %llu reserved seat!\n",
 717                                               (unsigned long long) ackno);
 718                                 ap->dccpap_buf[index] = state;
 719                                 goto out;
 720                         }
 721                         /* len == 0 means one packet */
 722                         if (delta < len + 1)
 723                                 goto out_duplicate;
 724
 725                         delta -= len + 1;
 726                         if (++index == ap->dccpap_buf_len)
 727                                 index = 0;
 728                 }
 729         }
 730
 731         ap->dccpap_buf_ackno = ackno;
 732         dccp_timestamp(sk, &ap->dccpap_time);
 733 out:
 734         dccp_pr_debug("");
 735         dccp_ackpkts_print(ap);
 736         return 0;
 737
 738 out_duplicate:
 739         /* Duplicate packet */
 740         dccp_pr_debug("Received a dup or already considered lost "
 741                       "packet: %llu\n", (unsigned long long) ackno);
 742         return -EILSEQ;
 743 }
 744
 745 #ifdef CONFIG_IP_DCCP_DEBUG
 746 void dccp_ackvector_print(const u64 ackno, const unsigned char *vector,
 747                           int len)
 748 {
 749         if (!dccp_debug)
 750                 return;
 751
 752         printk("ACK vector len=%d, ackno=%llu |", len,
 753                (unsigned long long) ackno);
 754
 755         while (len--) {
 756                 const u8 state = (*vector & DCCP_ACKPKTS_STATE_MASK) >> 6;
 757                 const u8 rl = (*vector & DCCP_ACKPKTS_LEN_MASK);
 758
 759                 printk("%d,%d|", state, rl);
 760                 ++vector;
 761         }
 762
 763         printk("\n");
 764 }
 765
 766 void dccp_ackpkts_print(const struct dccp_ackpkts *ap)
 767 {
 768         dccp_ackvector_print(ap->dccpap_buf_ackno,
 769                              ap->dccpap_buf + ap->dccpap_buf_head,
 770                              ap->dccpap_buf_vector_len);
 771 }
 772 #endif
 773
 774 static void dccp_ackpkts_trow_away_ack_record(struct dccp_ackpkts *ap)
 775 {
 776         /*
 777          * As we're keeping track of the ack vector size
 778          * (dccpap_buf_vector_len) and the sent ack vector size
 779          * (dccpap_ack_vector_len) we don't need dccpap_buf_tail at all, but
 780          * keep this code here as in the future we'll implement a vector of
 781          * ack records, as suggested in draft-ietf-dccp-spec-11.txt
 782          * Appendix A. -acme
 783          */
 784 #if 0
 785         ap->dccpap_buf_tail = ap->dccpap_ack_ptr + 1;
 786         if (ap->dccpap_buf_tail >= ap->dccpap_buf_len)
 787                 ap->dccpap_buf_tail -= ap->dccpap_buf_len;
 788 #endif
 789         ap->dccpap_buf_vector_len -= ap->dccpap_ack_vector_len;
 790 }
 791
 792 void dccp_ackpkts_check_rcv_ackno(struct dccp_ackpkts *ap, struct sock *sk,
 793                                  u64 ackno)
 794 {
 795         /* Check if we actually sent an ACK vector */
 796         if (ap->dccpap_ack_seqno == DCCP_MAX_SEQNO + 1)
 797                 return;
 798
 799         if (ackno == ap->dccpap_ack_seqno) {
 800 #ifdef CONFIG_IP_DCCP_DEBUG
 801                 struct dccp_sock *dp = dccp_sk(sk);
 802                 const char *debug_prefix = dp->dccps_role == DCCP_ROLE_CLIENT ?
 803                                         "CLIENT rx ack: " : "server rx ack: ";
 804 #endif
 805                 dccp_pr_debug("%sACK packet 0, len=%d, ack_seqno=%llu, "
 806                               "ack_ackno=%llu, ACKED!\n",
 807                               debug_prefix, 1,
 808                               (unsigned long long) ap->dccpap_ack_seqno,
 809                               (unsigned long long) ap->dccpap_ack_ackno);
 810                 dccp_ackpkts_trow_away_ack_record(ap);
 811                 ap->dccpap_ack_seqno = DCCP_MAX_SEQNO + 1;
 812         }
 813 }
 814
 815 static void dccp_ackpkts_check_rcv_ackvector(struct dccp_ackpkts *ap,
 816                                              struct sock *sk, u64 ackno,
 817                                              const unsigned char len,
 818                                              const unsigned char *vector)
 819 {
 820         unsigned char i;
 821
 822         /* Check if we actually sent an ACK vector */
 823         if (ap->dccpap_ack_seqno == DCCP_MAX_SEQNO + 1)
 824                 return;
 825         /*
 826          * We're in the receiver half connection, so if the received an ACK
 827          * vector ackno (e.g. 50) before dccpap_ack_seqno (e.g. 52), we're
 828          * not interested.
 829          *
 830          * Extra explanation with example:
 831          *
 832          * if we received an ACK vector with ackno 50, it can only be acking
 833          * 50, 49, 48, etc, not 52 (the seqno for the ACK vector we sent).
 834          */
 835         /* dccp_pr_debug("is %llu < %llu? ", ackno, ap->dccpap_ack_seqno); */
 836         if (before48(ackno, ap->dccpap_ack_seqno)) {
 837                 /* dccp_pr_debug_cat("yes\n"); */
 838                 return;
 839         }
 840         /* dccp_pr_debug_cat("no\n"); */
 841
 842         i = len;
 843         while (i--) {
 844                 const u8 rl = (*vector & DCCP_ACKPKTS_LEN_MASK);
 845                 u64 ackno_end_rl;
 846
 847                 dccp_set_seqno(&ackno_end_rl, ackno - rl);
 848
 849                 /*
 850                  * dccp_pr_debug("is %llu <= %llu <= %llu? ", ackno_end_rl,
 851                  * ap->dccpap_ack_seqno, ackno);
 852                  */
 853                 if (between48(ap->dccpap_ack_seqno, ackno_end_rl, ackno)) {
 854                         const u8 state = (*vector &
 855                                           DCCP_ACKPKTS_STATE_MASK) >> 6;
 856                         /* dccp_pr_debug_cat("yes\n"); */
 857
 858                         if (state != DCCP_ACKPKTS_STATE_NOT_RECEIVED) {
 859 #ifdef CONFIG_IP_DCCP_DEBUG
 860                                 struct dccp_sock *dp = dccp_sk(sk);
 861                                 const char *debug_prefix =
 862                                         dp->dccps_role == DCCP_ROLE_CLIENT ?
 863                                         "CLIENT rx ack: " : "server rx ack: ";
 864 #endif
 865                                 dccp_pr_debug("%sACK vector 0, len=%d, "
 866                                               "ack_seqno=%llu, ack_ackno=%llu, "
 867                                               "ACKED!\n",
 868                                               debug_prefix, len,
 869                                               (unsigned long long)
 870                                               ap->dccpap_ack_seqno,
 871                                               (unsigned long long)
 872                                               ap->dccpap_ack_ackno);
 873                                 dccp_ackpkts_trow_away_ack_record(ap);
 874                         }
 875                         /*
 876                          * If dccpap_ack_seqno was not received, no problem
 877                          * we'll send another ACK vector.
 878                          */
 879                         ap->dccpap_ack_seqno = DCCP_MAX_SEQNO + 1;
 880                         break;
 881                 }
 882                 /* dccp_pr_debug_cat("no\n"); */
 883
 884                 dccp_set_seqno(&ackno, ackno_end_rl - 1);
 885                 ++vector;
 886         }
 887 }