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
  76         memset(opt_recv, 0, sizeof(*opt_recv));
  77
  78         while (opt_ptr != opt_end) {
  79                 opt   = *opt_ptr++;
  80                 len   = 0;
  81                 value = NULL;
  82
  83                 /* Check if this isn't a single byte option */
  84                 if (opt > DCCPO_MAX_RESERVED) {
  85                         if (opt_ptr == opt_end)
  86                                 goto out_invalid_option;
  87
  88                         len = *opt_ptr++;
  89                         if (len < 3)
  90                                 goto out_invalid_option;
  91                         /*
  92                          * Remove the type and len fields, leaving
  93                          * just the value size
  94                          */
  95                         len     -= 2;
  96                         value   = opt_ptr;
  97                         opt_ptr += len;
  98
  99                         if (opt_ptr > opt_end)
 100                                 goto out_invalid_option;
 101                 }
 102
 103                 switch (opt) {
 104                 case DCCPO_PADDING:
 105                         break;
 106                 case DCCPO_NDP_COUNT:
 107                         if (len > 3)
 108                                 goto out_invalid_option;
 109
 110                         opt_recv->dccpor_ndp = dccp_decode_value_var(value, len);
 111                         dccp_pr_debug("%sNDP count=%d\n", debug_prefix,
 112                                       opt_recv->dccpor_ndp);
 113                         break;
 114                 case DCCPO_ACK_VECTOR_0:
 115                         if (len > DCCP_MAX_ACK_VECTOR_LEN)
 116                                 goto out_invalid_option;
 117
 118                         if (pkt_type == DCCP_PKT_DATA)
 119                                 continue;
 120
 121                         opt_recv->dccpor_ack_vector_len = len;
 122                         opt_recv->dccpor_ack_vector_idx = value - options;
 123
 124                         dccp_pr_debug("%sACK vector 0, len=%d, ack_ackno=%llu\n",
 125                                       debug_prefix, len,
 126                                       (unsigned long long)
 127                                       DCCP_SKB_CB(skb)->dccpd_ack_seq);
 128                         dccp_ackvector_print(DCCP_SKB_CB(skb)->dccpd_ack_seq,
 129                                              value, len);
 130                         dccp_ackpkts_check_rcv_ackvector(dp->dccps_hc_rx_ackpkts,
 131                                                          sk,
 132                                                  DCCP_SKB_CB(skb)->dccpd_ack_seq,
 133                                                          len, value);
 134                         break;
 135                 case DCCPO_TIMESTAMP:
 136                         if (len != 4)
 137                                 goto out_invalid_option;
 138
 139                         opt_recv->dccpor_timestamp = ntohl(*(u32 *)value);
 140
 141                         dp->dccps_timestamp_echo = opt_recv->dccpor_timestamp;
 142                         do_gettimeofday(&dp->dccps_timestamp_time);
 143
 144                         dccp_pr_debug("%sTIMESTAMP=%u, ackno=%llu\n",
 145                                       debug_prefix, opt_recv->dccpor_timestamp,
 146                                       (unsigned long long)
 147                                       DCCP_SKB_CB(skb)->dccpd_ack_seq);
 148                         break;
 149                 case DCCPO_TIMESTAMP_ECHO:
 150                         if (len != 4 && len != 6 && len != 8)
 151                                 goto out_invalid_option;
 152
 153                         opt_recv->dccpor_timestamp_echo = ntohl(*(u32 *)value);
 154
 155                         dccp_pr_debug("%sTIMESTAMP_ECHO=%u, len=%d, ackno=%llu, ",
 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
 162                         if (len > 4) {
 163                                 if (len == 6)
 164                                         opt_recv->dccpor_elapsed_time =
 165                                                  ntohs(*(u16 *)(value + 4));
 166                                 else
 167                                         opt_recv->dccpor_elapsed_time =
 168                                                  ntohl(*(u32 *)(value + 4));
 169
 170                                 dccp_pr_debug("%sTIMESTAMP_ECHO ELAPSED_TIME=%d\n",
 171                                       debug_prefix,
 172                                       opt_recv->dccpor_elapsed_time);
 173                         }
 174                         break;
 175                 case DCCPO_ELAPSED_TIME:
 176                         if (len != 2 && len != 4)
 177                                 goto out_invalid_option;
 178
 179                         if (pkt_type == DCCP_PKT_DATA)
 180                                 continue;
 181
 182                         if (len == 2)
 183                                 opt_recv->dccpor_elapsed_time =
 184                                                         ntohs(*(u16 *)value);
 185                         else
 186                                 opt_recv->dccpor_elapsed_time =
 187                                                         ntohl(*(u32 *)value);
 188
 189                         dccp_pr_debug("%sELAPSED_TIME=%d\n", debug_prefix,
 190                                       opt_recv->dccpor_elapsed_time);
 191                         break;
 192                         /*
 193                          * From draft-ietf-dccp-spec-11.txt:
 194                          *
 195                          *      Option numbers 128 through 191 are for
 196                          *      options sent from the HC-Sender to the
 197                          *      HC-Receiver; option numbers 192 through 255
 198                          *      are for options sent from the HC-Receiver to
 199                          *      the HC-Sender.
 200                          */
 201                 case 128 ... 191: {
 202                         const u16 idx = value - options;
 203
 204                         if (ccid_hc_rx_parse_options(dp->dccps_hc_rx_ccid, sk,
 205                                                      opt, len, idx,
 206                                                      value) != 0)
 207                                 goto out_invalid_option;
 208                 }
 209                         break;
 210                 case 192 ... 255: {
 211                         const u16 idx = value - options;
 212
 213                         if (ccid_hc_tx_parse_options(dp->dccps_hc_tx_ccid, sk,
 214                                                      opt, len, idx,
 215                                                      value) != 0)
 216                                 goto out_invalid_option;
 217                 }
 218                         break;
 219                 default:
 220                         pr_info("DCCP(%p): option %d(len=%d) not "
 221                                 "implemented, ignoring\n",
 222                                 sk, opt, len);
 223                         break;
 224                 }
 225         }
 226
 227         return 0;
 228
 229 out_invalid_option:
 230         DCCP_INC_STATS_BH(DCCP_MIB_INVALIDOPT);
 231         DCCP_SKB_CB(skb)->dccpd_reset_code = DCCP_RESET_CODE_OPTION_ERROR;
 232         pr_info("DCCP(%p): invalid option %d, len=%d\n", sk, opt, len);
 233         return -1;
 234 }
 235
 236 static void dccp_encode_value_var(const u32 value, unsigned char *to,
 237                                   const unsigned int len)
 238 {
 239         if (len > 3)
 240                 *to++ = (value & 0xFF000000) >> 24;
 241         if (len > 2)
 242                 *to++ = (value & 0xFF0000) >> 16;
 243         if (len > 1)
 244                 *to++ = (value & 0xFF00) >> 8;
 245         if (len > 0)
 246                 *to++ = (value & 0xFF);
 247 }
 248
 249 static inline int dccp_ndp_len(const int ndp)
 250 {
 251         return likely(ndp <= 0xFF) ? 1 : ndp <= 0xFFFF ? 2 : 3;
 252 }
 253
 254 void dccp_insert_option(struct sock *sk, struct sk_buff *skb,
 255                         const unsigned char option,
 256                         const void *value, const unsigned char len)
 257 {
 258         unsigned char *to;
 259
 260         if (DCCP_SKB_CB(skb)->dccpd_opt_len + len + 2 > DCCP_MAX_OPT_LEN) {
 261                 LIMIT_NETDEBUG(KERN_INFO "DCCP: packet too small to insert "
 262                                "%d option!\n", option);
 263                 return;
 264         }
 265
 266         DCCP_SKB_CB(skb)->dccpd_opt_len += len + 2;
 267
 268         to    = skb_push(skb, len + 2);
 269         *to++ = option;
 270         *to++ = len + 2;
 271
 272         memcpy(to, value, len);
 273 }
 274
 275 EXPORT_SYMBOL_GPL(dccp_insert_option);
 276
 277 static void dccp_insert_option_ndp(struct sock *sk, struct sk_buff *skb)
 278 {
 279         struct dccp_sock *dp = dccp_sk(sk);
 280         int ndp = dp->dccps_ndp_count;
 281
 282         if (dccp_non_data_packet(skb))
 283                 ++dp->dccps_ndp_count;
 284         else
 285                 dp->dccps_ndp_count = 0;
 286
 287         if (ndp > 0) {
 288                 unsigned char *ptr;
 289                 const int ndp_len = dccp_ndp_len(ndp);
 290                 const int len = ndp_len + 2;
 291
 292                 if (DCCP_SKB_CB(skb)->dccpd_opt_len + len > DCCP_MAX_OPT_LEN)
 293                         return;
 294
 295                 DCCP_SKB_CB(skb)->dccpd_opt_len += len;
 296
 297                 ptr = skb_push(skb, len);
 298                 *ptr++ = DCCPO_NDP_COUNT;
 299                 *ptr++ = len;
 300                 dccp_encode_value_var(ndp, ptr, ndp_len);
 301         }
 302 }
 303
 304 static inline int dccp_elapsed_time_len(const u32 elapsed_time)
 305 {
 306         return elapsed_time == 0 ? 0 : elapsed_time <= 0xFFFF ? 2 : 4;
 307 }
 308
 309 void dccp_insert_option_elapsed_time(struct sock *sk,
 310                                      struct sk_buff *skb,
 311                                      u32 elapsed_time)
 312 {
 313 #ifdef CONFIG_IP_DCCP_DEBUG
 314         struct dccp_sock *dp = dccp_sk(sk);
 315         const char *debug_prefix = dp->dccps_role == DCCP_ROLE_CLIENT ?
 316                                         "CLIENT TX opt: " : "server TX opt: ";
 317 #endif
 318         const int elapsed_time_len = dccp_elapsed_time_len(elapsed_time);
 319         const int len = 2 + elapsed_time_len;
 320         unsigned char *to;
 321
 322         if (elapsed_time_len == 0)
 323                 return;
 324
 325         if (DCCP_SKB_CB(skb)->dccpd_opt_len + len > DCCP_MAX_OPT_LEN) {
 326                 LIMIT_NETDEBUG(KERN_INFO "DCCP: packet too small to "
 327                                          "insert elapsed time!\n");
 328                 return;
 329         }
 330
 331         DCCP_SKB_CB(skb)->dccpd_opt_len += len;
 332
 333         to    = skb_push(skb, len);
 334         *to++ = DCCPO_ELAPSED_TIME;
 335         *to++ = len;
 336
 337         if (elapsed_time_len == 2) {
 338                 const u16 var16 = htons((u16)elapsed_time);
 339                 memcpy(to, &var16, 2);
 340         } else {
 341                 const u32 var32 = htonl(elapsed_time);
 342                 memcpy(to, &var32, 4);
 343         }
 344
 345         dccp_pr_debug("%sELAPSED_TIME=%u, len=%d, seqno=%llu\n",
 346                       debug_prefix, elapsed_time,
 347                       len,
 348                       (unsigned long long) DCCP_SKB_CB(skb)->dccpd_seq);
 349 }
 350
 351 EXPORT_SYMBOL(dccp_insert_option_elapsed_time);
 352
 353 static void dccp_insert_option_ack_vector(struct sock *sk, struct sk_buff *skb)
 354 {
 355         struct dccp_sock *dp = dccp_sk(sk);
 356 #ifdef CONFIG_IP_DCCP_DEBUG
 357         const char *debug_prefix = dp->dccps_role == DCCP_ROLE_CLIENT ?
 358                                         "CLIENT TX opt: " : "server TX opt: ";
 359 #endif
 360         struct dccp_ackpkts *ap = dp->dccps_hc_rx_ackpkts;
 361         int len = ap->dccpap_buf_vector_len + 2;
 362         const u32 elapsed_time = now_delta(ap->dccpap_time) / 10;
 363         unsigned char *to, *from;
 364
 365         if (elapsed_time != 0)
 366                 dccp_insert_option_elapsed_time(sk, skb, elapsed_time);
 367
 368         if (DCCP_SKB_CB(skb)->dccpd_opt_len + len > DCCP_MAX_OPT_LEN) {
 369                 LIMIT_NETDEBUG(KERN_INFO "DCCP: packet too small to "
 370                                          "insert ACK Vector!\n");
 371                 return;
 372         }
 373
 374         /*
 375          * XXX: now we have just one ack vector sent record, so
 376          * we have to wait for it to be cleared.
 377          *
 378          * Of course this is not acceptable, but this is just for
 379          * basic testing now.
 380          */
 381         if (ap->dccpap_ack_seqno != DCCP_MAX_SEQNO + 1)
 382                 return;
 383
 384         DCCP_SKB_CB(skb)->dccpd_opt_len += len;
 385
 386         to    = skb_push(skb, len);
 387         *to++ = DCCPO_ACK_VECTOR_0;
 388         *to++ = len;
 389
 390         len  = ap->dccpap_buf_vector_len;
 391         from = ap->dccpap_buf + ap->dccpap_buf_head;
 392
 393         /* Check if buf_head wraps */
 394         if (ap->dccpap_buf_head + len > ap->dccpap_buf_len) {
 395                 const unsigned int tailsize = (ap->dccpap_buf_len -
 396                                                ap->dccpap_buf_head);
 397
 398                 memcpy(to, from, tailsize);
 399                 to   += tailsize;
 400                 len  -= tailsize;
 401                 from = ap->dccpap_buf;
 402         }
 403
 404         memcpy(to, from, len);
 405         /*
 406          *      From draft-ietf-dccp-spec-11.txt:
 407          *
 408          *      For each acknowledgement it sends, the HC-Receiver will add an
 409          *      acknowledgement record.  ack_seqno will equal the HC-Receiver
 410          *      sequence number it used for the ack packet; ack_ptr will equal
 411          *      buf_head; ack_ackno will equal buf_ackno; and ack_nonce will
 412          *      equal buf_nonce.
 413          *
 414          * This implemention uses just one ack record for now.
 415          */
 416         ap->dccpap_ack_seqno      = DCCP_SKB_CB(skb)->dccpd_seq;
 417         ap->dccpap_ack_ptr        = ap->dccpap_buf_head;
 418         ap->dccpap_ack_ackno      = ap->dccpap_buf_ackno;
 419         ap->dccpap_ack_nonce      = ap->dccpap_buf_nonce;
 420         ap->dccpap_ack_vector_len = ap->dccpap_buf_vector_len;
 421
 422         dccp_pr_debug("%sACK Vector 0, len=%d, ack_seqno=%llu, "
 423                       "ack_ackno=%llu\n",
 424                       debug_prefix, ap->dccpap_ack_vector_len,
 425                       (unsigned long long) ap->dccpap_ack_seqno,
 426                       (unsigned long long) ap->dccpap_ack_ackno);
 427 }
 428
 429 static inline void dccp_insert_option_timestamp(struct sock *sk,
 430                                                 struct sk_buff *skb)
 431 {
 432         struct timeval tv;
 433         u32 now;
 434
 435         do_gettimeofday(&tv);
 436         now = (tv.tv_sec * USEC_PER_SEC + tv.tv_usec) / 10;
 437         /* yes this will overflow but that is the point as we want a
 438          * 10 usec 32 bit timer which mean it wraps every 11.9 hours */
 439
 440         now = htonl(now);
 441         dccp_insert_option(sk, skb, DCCPO_TIMESTAMP, &now, sizeof(now));
 442 }
 443
 444 static void dccp_insert_option_timestamp_echo(struct sock *sk,
 445                                               struct sk_buff *skb)
 446 {
 447         struct dccp_sock *dp = dccp_sk(sk);
 448 #ifdef CONFIG_IP_DCCP_DEBUG
 449         const char *debug_prefix = dp->dccps_role == DCCP_ROLE_CLIENT ?
 450                                         "CLIENT TX opt: " : "server TX opt: ";
 451 #endif
 452         u32 tstamp_echo;
 453         const u32 elapsed_time = now_delta(dp->dccps_timestamp_time) / 10;
 454         const int elapsed_time_len = dccp_elapsed_time_len(elapsed_time);
 455         const int len = 6 + elapsed_time_len;
 456         unsigned char *to;
 457
 458         if (DCCP_SKB_CB(skb)->dccpd_opt_len + len > DCCP_MAX_OPT_LEN) {
 459                 LIMIT_NETDEBUG(KERN_INFO "DCCP: packet too small to insert "
 460                                          "timestamp echo!\n");
 461                 return;
 462         }
 463
 464         DCCP_SKB_CB(skb)->dccpd_opt_len += len;
 465
 466         to    = skb_push(skb, len);
 467         *to++ = DCCPO_TIMESTAMP_ECHO;
 468         *to++ = len;
 469
 470         tstamp_echo = htonl(dp->dccps_timestamp_echo);
 471         memcpy(to, &tstamp_echo, 4);
 472         to += 4;
 473
 474         if (elapsed_time_len == 2) {
 475                 const u16 var16 = htons((u16)elapsed_time);
 476                 memcpy(to, &var16, 2);
 477         } else if (elapsed_time_len == 4) {
 478                 const u32 var32 = htonl(elapsed_time);
 479                 memcpy(to, &var32, 4);
 480         }
 481
 482         dccp_pr_debug("%sTIMESTAMP_ECHO=%u, len=%d, seqno=%llu\n",
 483                       debug_prefix, dp->dccps_timestamp_echo,
 484                       len,
 485                       (unsigned long long) DCCP_SKB_CB(skb)->dccpd_seq);
 486
 487         dp->dccps_timestamp_echo = 0;
 488         dp->dccps_timestamp_time.tv_sec = 0;
 489         dp->dccps_timestamp_time.tv_usec = 0;
 490 }
 491
 492 void dccp_insert_options(struct sock *sk, struct sk_buff *skb)
 493 {
 494         struct dccp_sock *dp = dccp_sk(sk);
 495
 496         DCCP_SKB_CB(skb)->dccpd_opt_len = 0;
 497
 498         if (dp->dccps_options.dccpo_send_ndp_count)
 499                 dccp_insert_option_ndp(sk, skb);
 500
 501         if (!dccp_packet_without_ack(skb)) {
 502                 if (dp->dccps_options.dccpo_send_ack_vector &&
 503                     (dp->dccps_hc_rx_ackpkts->dccpap_buf_ackno !=
 504                      DCCP_MAX_SEQNO + 1))
 505                         dccp_insert_option_ack_vector(sk, skb);
 506
 507                 dccp_insert_option_timestamp(sk, skb);
 508                 if (dp->dccps_timestamp_echo != 0)
 509                         dccp_insert_option_timestamp_echo(sk, skb);
 510         }
 511
 512         ccid_hc_rx_insert_options(dp->dccps_hc_rx_ccid, sk, skb);
 513         ccid_hc_tx_insert_options(dp->dccps_hc_tx_ccid, sk, skb);
 514
 515         /* XXX: insert other options when appropriate */
 516
 517         if (DCCP_SKB_CB(skb)->dccpd_opt_len != 0) {
 518                 /* The length of all options has to be a multiple of 4 */
 519                 int padding = DCCP_SKB_CB(skb)->dccpd_opt_len % 4;
 520
 521                 if (padding != 0) {
 522                         padding = 4 - padding;
 523                         memset(skb_push(skb, padding), 0, padding);
 524                         DCCP_SKB_CB(skb)->dccpd_opt_len += padding;
 525                 }
 526         }
 527 }
 528
 529 struct dccp_ackpkts *dccp_ackpkts_alloc(const unsigned int len,
 530                                         const unsigned int __nocast priority)
 531 {
 532         struct dccp_ackpkts *ap = kmalloc(sizeof(*ap) + len, priority);
 533
 534         if (ap != NULL) {
 535 #ifdef CONFIG_IP_DCCP_DEBUG
 536                 memset(ap->dccpap_buf, 0xFF, len);
 537 #endif
 538                 ap->dccpap_buf_len   = len;
 539                 ap->dccpap_buf_head  =
 540                         ap->dccpap_buf_tail =
 541                                 ap->dccpap_buf_len - 1;
 542                 ap->dccpap_buf_ackno =
 543                         ap->dccpap_ack_ackno =
 544                                 ap->dccpap_ack_seqno = DCCP_MAX_SEQNO + 1;
 545                 ap->dccpap_buf_nonce = ap->dccpap_buf_nonce = 0;
 546                 ap->dccpap_ack_ptr   = 0;
 547                 ap->dccpap_time.tv_sec = 0;
 548                 ap->dccpap_time.tv_usec = 0;
 549                 ap->dccpap_buf_vector_len = ap->dccpap_ack_vector_len = 0;
 550         }
 551
 552         return ap;
 553 }
 554
 555 void dccp_ackpkts_free(struct dccp_ackpkts *ap)
 556 {
 557         if (ap != NULL) {
 558 #ifdef CONFIG_IP_DCCP_DEBUG
 559                 memset(ap, 0xFF, sizeof(*ap) + ap->dccpap_buf_len);
 560 #endif
 561                 kfree(ap);
 562         }
 563 }
 564
 565 static inline u8 dccp_ackpkts_state(const struct dccp_ackpkts *ap,
 566                                     const unsigned int index)
 567 {
 568         return ap->dccpap_buf[index] & DCCP_ACKPKTS_STATE_MASK;
 569 }
 570
 571 static inline u8 dccp_ackpkts_len(const struct dccp_ackpkts *ap,
 572                                   const unsigned int index)
 573 {
 574         return ap->dccpap_buf[index] & DCCP_ACKPKTS_LEN_MASK;
 575 }
 576
 577 /*
 578  * If several packets are missing, the HC-Receiver may prefer to enter multiple
 579  * bytes with run length 0, rather than a single byte with a larger run length;
 580  * this simplifies table updates if one of the missing packets arrives.
 581  */
 582 static inline int dccp_ackpkts_set_buf_head_state(struct dccp_ackpkts *ap,
 583                                                   const unsigned int packets,
 584                                                   const unsigned char state)
 585 {
 586         unsigned int gap;
 587         signed long new_head;
 588
 589         if (ap->dccpap_buf_vector_len + packets > ap->dccpap_buf_len)
 590                 return -ENOBUFS;
 591
 592         gap      = packets - 1;
 593         new_head = ap->dccpap_buf_head - packets;
 594
 595         if (new_head < 0) {
 596                 if (gap > 0) {
 597                         memset(ap->dccpap_buf, DCCP_ACKPKTS_STATE_NOT_RECEIVED,
 598                                gap + new_head + 1);
 599                         gap = -new_head;
 600                 }
 601                 new_head += ap->dccpap_buf_len;
 602         }
 603
 604         ap->dccpap_buf_head = new_head;
 605
 606         if (gap > 0)
 607                 memset(ap->dccpap_buf + ap->dccpap_buf_head + 1,
 608                        DCCP_ACKPKTS_STATE_NOT_RECEIVED, gap);
 609
 610         ap->dccpap_buf[ap->dccpap_buf_head] = state;
 611         ap->dccpap_buf_vector_len += packets;
 612         return 0;
 613 }
 614
 615 /*
 616  * Implements the draft-ietf-dccp-spec-11.txt Appendix A
 617  */
 618 int dccp_ackpkts_add(struct dccp_ackpkts *ap, u64 ackno, u8 state)
 619 {
 620         /*
 621          * Check at the right places if the buffer is full, if it is, tell the
 622          * caller to start dropping packets till the HC-Sender acks our ACK
 623          * vectors, when we will free up space in dccpap_buf.
 624          *
 625          * We may well decide to do buffer compression, etc, but for now lets
 626          * just drop.
 627          *
 628          * From Appendix A:
 629          *
 630          *      Of course, the circular buffer may overflow, either when the
 631          *      HC-Sender is sending data at a very high rate, when the
 632          *      HC-Receiver's acknowledgements are not reaching the HC-Sender,
 633          *      or when the HC-Sender is forgetting to acknowledge those acks
 634          *      (so the HC-Receiver is unable to clean up old state). In this
 635          *      case, the HC-Receiver should either compress the buffer (by
 636          *      increasing run lengths when possible), transfer its state to
 637          *      a larger buffer, or, as a last resort, drop all received
 638          *      packets, without processing them whatsoever, until its buffer
 639          *      shrinks again.
 640          */
 641
 642         /* See if this is the first ackno being inserted */
 643         if (ap->dccpap_buf_vector_len == 0) {
 644                 ap->dccpap_buf[ap->dccpap_buf_head] = state;
 645                 ap->dccpap_buf_vector_len = 1;
 646         } else if (after48(ackno, ap->dccpap_buf_ackno)) {
 647                 const u64 delta = dccp_delta_seqno(ap->dccpap_buf_ackno,
 648                                                    ackno);
 649
 650                 /*
 651                  * Look if the state of this packet is the same as the
 652                  * previous ackno and if so if we can bump the head len.
 653                  */
 654                 if (delta == 1 &&
 655                     dccp_ackpkts_state(ap, ap->dccpap_buf_head) == state &&
 656                     (dccp_ackpkts_len(ap, ap->dccpap_buf_head) <
 657                      DCCP_ACKPKTS_LEN_MASK))
 658                         ap->dccpap_buf[ap->dccpap_buf_head]++;
 659                 else if (dccp_ackpkts_set_buf_head_state(ap, delta, state))
 660                         return -ENOBUFS;
 661         } else {
 662                 /*
 663                  * A.1.2.  Old Packets
 664                  *
 665                  *      When a packet with Sequence Number S arrives, and
 666                  *      S <= buf_ackno, the HC-Receiver will scan the table
 667                  *      for the byte corresponding to S. (Indexing structures
 668                  *      could reduce the complexity of this scan.)
 669                  */
 670                 u64 delta = dccp_delta_seqno(ackno, ap->dccpap_buf_ackno);
 671                 unsigned int index = ap->dccpap_buf_head;
 672
 673                 while (1) {
 674                         const u8 len = dccp_ackpkts_len(ap, index);
 675                         const u8 state = dccp_ackpkts_state(ap, index);
 676                         /*
 677                          * valid packets not yet in dccpap_buf have a reserved
 678                          * entry, with a len equal to 0.
 679                          */
 680                         if (state == DCCP_ACKPKTS_STATE_NOT_RECEIVED &&
 681                             len == 0 && delta == 0) { /* Found our
 682                                                          reserved seat! */
 683                                 dccp_pr_debug("Found %llu reserved seat!\n",
 684                                               (unsigned long long) ackno);
 685                                 ap->dccpap_buf[index] = state;
 686                                 goto out;
 687                         }
 688                         /* len == 0 means one packet */
 689                         if (delta < len + 1)
 690                                 goto out_duplicate;
 691
 692                         delta -= len + 1;
 693                         if (++index == ap->dccpap_buf_len)
 694                                 index = 0;
 695                 }
 696         }
 697
 698         ap->dccpap_buf_ackno = ackno;
 699         do_gettimeofday(&ap->dccpap_time);
 700 out:
 701         dccp_pr_debug("");
 702         dccp_ackpkts_print(ap);
 703         return 0;
 704
 705 out_duplicate:
 706         /* Duplicate packet */
 707         dccp_pr_debug("Received a dup or already considered lost "
 708                       "packet: %llu\n", (unsigned long long) ackno);
 709         return -EILSEQ;
 710 }
 711
 712 #ifdef CONFIG_IP_DCCP_DEBUG
 713 void dccp_ackvector_print(const u64 ackno, const unsigned char *vector,
 714                           int len)
 715 {
 716         if (!dccp_debug)
 717                 return;
 718
 719         printk("ACK vector len=%d, ackno=%llu |", len,
 720                (unsigned long long) ackno);
 721
 722         while (len--) {
 723                 const u8 state = (*vector & DCCP_ACKPKTS_STATE_MASK) >> 6;
 724                 const u8 rl = (*vector & DCCP_ACKPKTS_LEN_MASK);
 725
 726                 printk("%d,%d|", state, rl);
 727                 ++vector;
 728         }
 729
 730         printk("\n");
 731 }
 732
 733 void dccp_ackpkts_print(const struct dccp_ackpkts *ap)
 734 {
 735         dccp_ackvector_print(ap->dccpap_buf_ackno,
 736                              ap->dccpap_buf + ap->dccpap_buf_head,
 737                              ap->dccpap_buf_vector_len);
 738 }
 739 #endif
 740
 741 static void dccp_ackpkts_trow_away_ack_record(struct dccp_ackpkts *ap)
 742 {
 743         /*
 744          * As we're keeping track of the ack vector size
 745          * (dccpap_buf_vector_len) and the sent ack vector size
 746          * (dccpap_ack_vector_len) we don't need dccpap_buf_tail at all, but
 747          * keep this code here as in the future we'll implement a vector of
 748          * ack records, as suggested in draft-ietf-dccp-spec-11.txt
 749          * Appendix A. -acme
 750          */
 751 #if 0
 752         ap->dccpap_buf_tail = ap->dccpap_ack_ptr + 1;
 753         if (ap->dccpap_buf_tail >= ap->dccpap_buf_len)
 754                 ap->dccpap_buf_tail -= ap->dccpap_buf_len;
 755 #endif
 756         ap->dccpap_buf_vector_len -= ap->dccpap_ack_vector_len;
 757 }
 758
 759 void dccp_ackpkts_check_rcv_ackno(struct dccp_ackpkts *ap, struct sock *sk,
 760                                  u64 ackno)
 761 {
 762         /* Check if we actually sent an ACK vector */
 763         if (ap->dccpap_ack_seqno == DCCP_MAX_SEQNO + 1)
 764                 return;
 765
 766         if (ackno == ap->dccpap_ack_seqno) {
 767 #ifdef CONFIG_IP_DCCP_DEBUG
 768                 struct dccp_sock *dp = dccp_sk(sk);
 769                 const char *debug_prefix = dp->dccps_role == DCCP_ROLE_CLIENT ?
 770                                         "CLIENT rx ack: " : "server rx ack: ";
 771 #endif
 772                 dccp_pr_debug("%sACK packet 0, len=%d, ack_seqno=%llu, "
 773                               "ack_ackno=%llu, ACKED!\n",
 774                               debug_prefix, 1,
 775                               (unsigned long long) ap->dccpap_ack_seqno,
 776                               (unsigned long long) ap->dccpap_ack_ackno);
 777                 dccp_ackpkts_trow_away_ack_record(ap);
 778                 ap->dccpap_ack_seqno = DCCP_MAX_SEQNO + 1;
 779         }
 780 }
 781
 782 static void dccp_ackpkts_check_rcv_ackvector(struct dccp_ackpkts *ap,
 783                                              struct sock *sk, u64 ackno,
 784                                              const unsigned char len,
 785                                              const unsigned char *vector)
 786 {
 787         unsigned char i;
 788
 789         /* Check if we actually sent an ACK vector */
 790         if (ap->dccpap_ack_seqno == DCCP_MAX_SEQNO + 1)
 791                 return;
 792         /*
 793          * We're in the receiver half connection, so if the received an ACK
 794          * vector ackno (e.g. 50) before dccpap_ack_seqno (e.g. 52), we're
 795          * not interested.
 796          *
 797          * Extra explanation with example:
 798          *
 799          * if we received an ACK vector with ackno 50, it can only be acking
 800          * 50, 49, 48, etc, not 52 (the seqno for the ACK vector we sent).
 801          */
 802         /* dccp_pr_debug("is %llu < %llu? ", ackno, ap->dccpap_ack_seqno); */
 803         if (before48(ackno, ap->dccpap_ack_seqno)) {
 804                 /* dccp_pr_debug_cat("yes\n"); */
 805                 return;
 806         }
 807         /* dccp_pr_debug_cat("no\n"); */
 808
 809         i = len;
 810         while (i--) {
 811                 const u8 rl = (*vector & DCCP_ACKPKTS_LEN_MASK);
 812                 u64 ackno_end_rl;
 813
 814                 dccp_set_seqno(&ackno_end_rl, ackno - rl);
 815
 816                 /*
 817                  * dccp_pr_debug("is %llu <= %llu <= %llu? ", ackno_end_rl,
 818                  * ap->dccpap_ack_seqno, ackno);
 819                  */
 820                 if (between48(ap->dccpap_ack_seqno, ackno_end_rl, ackno)) {
 821                         const u8 state = (*vector &
 822                                           DCCP_ACKPKTS_STATE_MASK) >> 6;
 823                         /* dccp_pr_debug_cat("yes\n"); */
 824
 825                         if (state != DCCP_ACKPKTS_STATE_NOT_RECEIVED) {
 826 #ifdef CONFIG_IP_DCCP_DEBUG
 827                                 struct dccp_sock *dp = dccp_sk(sk);
 828                                 const char *debug_prefix =
 829                                         dp->dccps_role == DCCP_ROLE_CLIENT ?
 830                                         "CLIENT rx ack: " : "server rx ack: ";
 831 #endif
 832                                 dccp_pr_debug("%sACK vector 0, len=%d, "
 833                                               "ack_seqno=%llu, ack_ackno=%llu, "
 834                                               "ACKED!\n",
 835                                               debug_prefix, len,
 836                                               (unsigned long long)
 837                                               ap->dccpap_ack_seqno,
 838                                               (unsigned long long)
 839                                               ap->dccpap_ack_ackno);
 840                                 dccp_ackpkts_trow_away_ack_record(ap);
 841                         }
 842                         /*
 843                          * If dccpap_ack_seqno was not received, no problem
 844                          * we'll send another ACK vector.
 845                          */
 846                         ap->dccpap_ack_seqno = DCCP_MAX_SEQNO + 1;
 847                         break;
 848                 }
 849                 /* dccp_pr_debug_cat("no\n"); */
 850
 851                 dccp_set_seqno(&ackno, ackno_end_rl - 1);
 852                 ++vector;
 853         }
 854 }