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   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                         do_gettimeofday(&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         const u32 elapsed_time = timeval_now_delta(&ap->dccpap_time) / 10;
 365         unsigned char *to, *from;
 366
 367         if (elapsed_time != 0)
 368                 dccp_insert_option_elapsed_time(sk, skb, elapsed_time);
 369
 370         if (DCCP_SKB_CB(skb)->dccpd_opt_len + len > DCCP_MAX_OPT_LEN) {
 371                 LIMIT_NETDEBUG(KERN_INFO "DCCP: packet too small to "
 372                                          "insert ACK Vector!\n");
 373                 return;
 374         }
 375
 376         /*
 377          * XXX: now we have just one ack vector sent record, so
 378          * we have to wait for it to be cleared.
 379          *
 380          * Of course this is not acceptable, but this is just for
 381          * basic testing now.
 382          */
 383         if (ap->dccpap_ack_seqno != DCCP_MAX_SEQNO + 1)
 384                 return;
 385
 386         DCCP_SKB_CB(skb)->dccpd_opt_len += len;
 387
 388         to    = skb_push(skb, len);
 389         *to++ = DCCPO_ACK_VECTOR_0;
 390         *to++ = len;
 391
 392         len  = ap->dccpap_buf_vector_len;
 393         from = ap->dccpap_buf + ap->dccpap_buf_head;
 394
 395         /* Check if buf_head wraps */
 396         if (ap->dccpap_buf_head + len > ap->dccpap_buf_len) {
 397                 const unsigned int tailsize = (ap->dccpap_buf_len -
 398                                                ap->dccpap_buf_head);
 399
 400                 memcpy(to, from, tailsize);
 401                 to   += tailsize;
 402                 len  -= tailsize;
 403                 from = ap->dccpap_buf;
 404         }
 405
 406         memcpy(to, from, len);
 407         /*
 408          *      From draft-ietf-dccp-spec-11.txt:
 409          *
 410          *      For each acknowledgement it sends, the HC-Receiver will add an
 411          *      acknowledgement record.  ack_seqno will equal the HC-Receiver
 412          *      sequence number it used for the ack packet; ack_ptr will equal
 413          *      buf_head; ack_ackno will equal buf_ackno; and ack_nonce will
 414          *      equal buf_nonce.
 415          *
 416          * This implemention uses just one ack record for now.
 417          */
 418         ap->dccpap_ack_seqno      = DCCP_SKB_CB(skb)->dccpd_seq;
 419         ap->dccpap_ack_ptr        = ap->dccpap_buf_head;
 420         ap->dccpap_ack_ackno      = ap->dccpap_buf_ackno;
 421         ap->dccpap_ack_nonce      = ap->dccpap_buf_nonce;
 422         ap->dccpap_ack_vector_len = ap->dccpap_buf_vector_len;
 423
 424         dccp_pr_debug("%sACK Vector 0, len=%d, ack_seqno=%llu, "
 425                       "ack_ackno=%llu\n",
 426                       debug_prefix, ap->dccpap_ack_vector_len,
 427                       (unsigned long long) ap->dccpap_ack_seqno,
 428                       (unsigned long long) ap->dccpap_ack_ackno);
 429 }
 430
 431 void dccp_insert_option_timestamp(struct sock *sk, struct sk_buff *skb)
 432 {
 433         struct timeval tv;
 434         u32 now;
 435
 436         do_gettimeofday(&tv);
 437         now = (tv.tv_sec * USEC_PER_SEC + tv.tv_usec) / 10;
 438         /* yes this will overflow but that is the point as we want a
 439          * 10 usec 32 bit timer which mean it wraps every 11.9 hours */
 440
 441         now = htonl(now);
 442         dccp_insert_option(sk, skb, DCCPO_TIMESTAMP, &now, sizeof(now));
 443 }
 444
 445 EXPORT_SYMBOL_GPL(dccp_insert_option_timestamp);
 446
 447 static void dccp_insert_option_timestamp_echo(struct sock *sk,
 448                                               struct sk_buff *skb)
 449 {
 450         struct dccp_sock *dp = dccp_sk(sk);
 451 #ifdef CONFIG_IP_DCCP_DEBUG
 452         const char *debug_prefix = dp->dccps_role == DCCP_ROLE_CLIENT ?
 453                                         "CLIENT TX opt: " : "server TX opt: ";
 454 #endif
 455         u32 tstamp_echo;
 456         const u32 elapsed_time =
 457                         timeval_now_delta(&dp->dccps_timestamp_time) / 10;
 458         const int elapsed_time_len = dccp_elapsed_time_len(elapsed_time);
 459         const int len = 6 + elapsed_time_len;
 460         unsigned char *to;
 461
 462         if (DCCP_SKB_CB(skb)->dccpd_opt_len + len > DCCP_MAX_OPT_LEN) {
 463                 LIMIT_NETDEBUG(KERN_INFO "DCCP: packet too small to insert "
 464                                          "timestamp echo!\n");
 465                 return;
 466         }
 467
 468         DCCP_SKB_CB(skb)->dccpd_opt_len += len;
 469
 470         to    = skb_push(skb, len);
 471         *to++ = DCCPO_TIMESTAMP_ECHO;
 472         *to++ = len;
 473
 474         tstamp_echo = htonl(dp->dccps_timestamp_echo);
 475         memcpy(to, &tstamp_echo, 4);
 476         to += 4;
 477
 478         if (elapsed_time_len == 2) {
 479                 const u16 var16 = htons((u16)elapsed_time);
 480                 memcpy(to, &var16, 2);
 481         } else if (elapsed_time_len == 4) {
 482                 const u32 var32 = htonl(elapsed_time);
 483                 memcpy(to, &var32, 4);
 484         }
 485
 486         dccp_pr_debug("%sTIMESTAMP_ECHO=%u, len=%d, seqno=%llu\n",
 487                       debug_prefix, dp->dccps_timestamp_echo,
 488                       len,
 489                       (unsigned long long) DCCP_SKB_CB(skb)->dccpd_seq);
 490
 491         dp->dccps_timestamp_echo = 0;
 492         dp->dccps_timestamp_time.tv_sec = 0;
 493         dp->dccps_timestamp_time.tv_usec = 0;
 494 }
 495
 496 void dccp_insert_options(struct sock *sk, struct sk_buff *skb)
 497 {
 498         struct dccp_sock *dp = dccp_sk(sk);
 499
 500         DCCP_SKB_CB(skb)->dccpd_opt_len = 0;
 501
 502         if (dp->dccps_options.dccpo_send_ndp_count)
 503                 dccp_insert_option_ndp(sk, skb);
 504
 505         if (!dccp_packet_without_ack(skb)) {
 506                 if (dp->dccps_options.dccpo_send_ack_vector &&
 507                     (dp->dccps_hc_rx_ackpkts->dccpap_buf_ackno !=
 508                      DCCP_MAX_SEQNO + 1))
 509                         dccp_insert_option_ack_vector(sk, skb);
 510                 if (dp->dccps_timestamp_echo != 0)
 511                         dccp_insert_option_timestamp_echo(sk, skb);
 512         }
 513
 514         if (dp->dccps_hc_rx_insert_options) {
 515                 ccid_hc_rx_insert_options(dp->dccps_hc_rx_ccid, sk, skb);
 516                 dp->dccps_hc_rx_insert_options = 0;
 517         }
 518         if (dp->dccps_hc_tx_insert_options) {
 519                 ccid_hc_tx_insert_options(dp->dccps_hc_tx_ccid, sk, skb);
 520                 dp->dccps_hc_tx_insert_options = 0;
 521         }
 522
 523         /* XXX: insert other options when appropriate */
 524
 525         if (DCCP_SKB_CB(skb)->dccpd_opt_len != 0) {
 526                 /* The length of all options has to be a multiple of 4 */
 527                 int padding = DCCP_SKB_CB(skb)->dccpd_opt_len % 4;
 528
 529                 if (padding != 0) {
 530                         padding = 4 - padding;
 531                         memset(skb_push(skb, padding), 0, padding);
 532                         DCCP_SKB_CB(skb)->dccpd_opt_len += padding;
 533                 }
 534         }
 535 }
 536
 537 struct dccp_ackpkts *dccp_ackpkts_alloc(const unsigned int len,
 538                                         const unsigned int __nocast priority)
 539 {
 540         struct dccp_ackpkts *ap = kmalloc(sizeof(*ap) + len, priority);
 541
 542         if (ap != NULL) {
 543 #ifdef CONFIG_IP_DCCP_DEBUG
 544                 memset(ap->dccpap_buf, 0xFF, len);
 545 #endif
 546                 ap->dccpap_buf_len   = len;
 547                 ap->dccpap_buf_head  =
 548                         ap->dccpap_buf_tail =
 549                                 ap->dccpap_buf_len - 1;
 550                 ap->dccpap_buf_ackno =
 551                         ap->dccpap_ack_ackno =
 552                                 ap->dccpap_ack_seqno = DCCP_MAX_SEQNO + 1;
 553                 ap->dccpap_buf_nonce = ap->dccpap_buf_nonce = 0;
 554                 ap->dccpap_ack_ptr   = 0;
 555                 ap->dccpap_time.tv_sec = 0;
 556                 ap->dccpap_time.tv_usec = 0;
 557                 ap->dccpap_buf_vector_len = ap->dccpap_ack_vector_len = 0;
 558         }
 559
 560         return ap;
 561 }
 562
 563 void dccp_ackpkts_free(struct dccp_ackpkts *ap)
 564 {
 565         if (ap != NULL) {
 566 #ifdef CONFIG_IP_DCCP_DEBUG
 567                 memset(ap, 0xFF, sizeof(*ap) + ap->dccpap_buf_len);
 568 #endif
 569                 kfree(ap);
 570         }
 571 }
 572
 573 static inline u8 dccp_ackpkts_state(const struct dccp_ackpkts *ap,
 574                                     const unsigned int index)
 575 {
 576         return ap->dccpap_buf[index] & DCCP_ACKPKTS_STATE_MASK;
 577 }
 578
 579 static inline u8 dccp_ackpkts_len(const struct dccp_ackpkts *ap,
 580                                   const unsigned int index)
 581 {
 582         return ap->dccpap_buf[index] & DCCP_ACKPKTS_LEN_MASK;
 583 }
 584
 585 /*
 586  * If several packets are missing, the HC-Receiver may prefer to enter multiple
 587  * bytes with run length 0, rather than a single byte with a larger run length;
 588  * this simplifies table updates if one of the missing packets arrives.
 589  */
 590 static inline int dccp_ackpkts_set_buf_head_state(struct dccp_ackpkts *ap,
 591                                                   const unsigned int packets,
 592                                                   const unsigned char state)
 593 {
 594         unsigned int gap;
 595         signed long new_head;
 596
 597         if (ap->dccpap_buf_vector_len + packets > ap->dccpap_buf_len)
 598                 return -ENOBUFS;
 599
 600         gap      = packets - 1;
 601         new_head = ap->dccpap_buf_head - packets;
 602
 603         if (new_head < 0) {
 604                 if (gap > 0) {
 605                         memset(ap->dccpap_buf, DCCP_ACKPKTS_STATE_NOT_RECEIVED,
 606                                gap + new_head + 1);
 607                         gap = -new_head;
 608                 }
 609                 new_head += ap->dccpap_buf_len;
 610         }
 611
 612         ap->dccpap_buf_head = new_head;
 613
 614         if (gap > 0)
 615                 memset(ap->dccpap_buf + ap->dccpap_buf_head + 1,
 616                        DCCP_ACKPKTS_STATE_NOT_RECEIVED, gap);
 617
 618         ap->dccpap_buf[ap->dccpap_buf_head] = state;
 619         ap->dccpap_buf_vector_len += packets;
 620         return 0;
 621 }
 622
 623 /*
 624  * Implements the draft-ietf-dccp-spec-11.txt Appendix A
 625  */
 626 int dccp_ackpkts_add(struct dccp_ackpkts *ap, u64 ackno, u8 state)
 627 {
 628         /*
 629          * Check at the right places if the buffer is full, if it is, tell the
 630          * caller to start dropping packets till the HC-Sender acks our ACK
 631          * vectors, when we will free up space in dccpap_buf.
 632          *
 633          * We may well decide to do buffer compression, etc, but for now lets
 634          * just drop.
 635          *
 636          * From Appendix A:
 637          *
 638          *      Of course, the circular buffer may overflow, either when the
 639          *      HC-Sender is sending data at a very high rate, when the
 640          *      HC-Receiver's acknowledgements are not reaching the HC-Sender,
 641          *      or when the HC-Sender is forgetting to acknowledge those acks
 642          *      (so the HC-Receiver is unable to clean up old state). In this
 643          *      case, the HC-Receiver should either compress the buffer (by
 644          *      increasing run lengths when possible), transfer its state to
 645          *      a larger buffer, or, as a last resort, drop all received
 646          *      packets, without processing them whatsoever, until its buffer
 647          *      shrinks again.
 648          */
 649
 650         /* See if this is the first ackno being inserted */
 651         if (ap->dccpap_buf_vector_len == 0) {
 652                 ap->dccpap_buf[ap->dccpap_buf_head] = state;
 653                 ap->dccpap_buf_vector_len = 1;
 654         } else if (after48(ackno, ap->dccpap_buf_ackno)) {
 655                 const u64 delta = dccp_delta_seqno(ap->dccpap_buf_ackno,
 656                                                    ackno);
 657
 658                 /*
 659                  * Look if the state of this packet is the same as the
 660                  * previous ackno and if so if we can bump the head len.
 661                  */
 662                 if (delta == 1 &&
 663                     dccp_ackpkts_state(ap, ap->dccpap_buf_head) == state &&
 664                     (dccp_ackpkts_len(ap, ap->dccpap_buf_head) <
 665                      DCCP_ACKPKTS_LEN_MASK))
 666                         ap->dccpap_buf[ap->dccpap_buf_head]++;
 667                 else if (dccp_ackpkts_set_buf_head_state(ap, delta, state))
 668                         return -ENOBUFS;
 669         } else {
 670                 /*
 671                  * A.1.2.  Old Packets
 672                  *
 673                  *      When a packet with Sequence Number S arrives, and
 674                  *      S <= buf_ackno, the HC-Receiver will scan the table
 675                  *      for the byte corresponding to S. (Indexing structures
 676                  *      could reduce the complexity of this scan.)
 677                  */
 678                 u64 delta = dccp_delta_seqno(ackno, ap->dccpap_buf_ackno);
 679                 unsigned int index = ap->dccpap_buf_head;
 680
 681                 while (1) {
 682                         const u8 len = dccp_ackpkts_len(ap, index);
 683                         const u8 state = dccp_ackpkts_state(ap, index);
 684                         /*
 685                          * valid packets not yet in dccpap_buf have a reserved
 686                          * entry, with a len equal to 0.
 687                          */
 688                         if (state == DCCP_ACKPKTS_STATE_NOT_RECEIVED &&
 689                             len == 0 && delta == 0) { /* Found our
 690                                                          reserved seat! */
 691                                 dccp_pr_debug("Found %llu reserved seat!\n",
 692                                               (unsigned long long) ackno);
 693                                 ap->dccpap_buf[index] = state;
 694                                 goto out;
 695                         }
 696                         /* len == 0 means one packet */
 697                         if (delta < len + 1)
 698                                 goto out_duplicate;
 699
 700                         delta -= len + 1;
 701                         if (++index == ap->dccpap_buf_len)
 702                                 index = 0;
 703                 }
 704         }
 705
 706         ap->dccpap_buf_ackno = ackno;
 707         do_gettimeofday(&ap->dccpap_time);
 708 out:
 709         dccp_pr_debug("");
 710         dccp_ackpkts_print(ap);
 711         return 0;
 712
 713 out_duplicate:
 714         /* Duplicate packet */
 715         dccp_pr_debug("Received a dup or already considered lost "
 716                       "packet: %llu\n", (unsigned long long) ackno);
 717         return -EILSEQ;
 718 }
 719
 720 #ifdef CONFIG_IP_DCCP_DEBUG
 721 void dccp_ackvector_print(const u64 ackno, const unsigned char *vector,
 722                           int len)
 723 {
 724         if (!dccp_debug)
 725                 return;
 726
 727         printk("ACK vector len=%d, ackno=%llu |", len,
 728                (unsigned long long) ackno);
 729
 730         while (len--) {
 731                 const u8 state = (*vector & DCCP_ACKPKTS_STATE_MASK) >> 6;
 732                 const u8 rl = (*vector & DCCP_ACKPKTS_LEN_MASK);
 733
 734                 printk("%d,%d|", state, rl);
 735                 ++vector;
 736         }
 737
 738         printk("\n");
 739 }
 740
 741 void dccp_ackpkts_print(const struct dccp_ackpkts *ap)
 742 {
 743         dccp_ackvector_print(ap->dccpap_buf_ackno,
 744                              ap->dccpap_buf + ap->dccpap_buf_head,
 745                              ap->dccpap_buf_vector_len);
 746 }
 747 #endif
 748
 749 static void dccp_ackpkts_trow_away_ack_record(struct dccp_ackpkts *ap)
 750 {
 751         /*
 752          * As we're keeping track of the ack vector size
 753          * (dccpap_buf_vector_len) and the sent ack vector size
 754          * (dccpap_ack_vector_len) we don't need dccpap_buf_tail at all, but
 755          * keep this code here as in the future we'll implement a vector of
 756          * ack records, as suggested in draft-ietf-dccp-spec-11.txt
 757          * Appendix A. -acme
 758          */
 759 #if 0
 760         ap->dccpap_buf_tail = ap->dccpap_ack_ptr + 1;
 761         if (ap->dccpap_buf_tail >= ap->dccpap_buf_len)
 762                 ap->dccpap_buf_tail -= ap->dccpap_buf_len;
 763 #endif
 764         ap->dccpap_buf_vector_len -= ap->dccpap_ack_vector_len;
 765 }
 766
 767 void dccp_ackpkts_check_rcv_ackno(struct dccp_ackpkts *ap, struct sock *sk,
 768                                  u64 ackno)
 769 {
 770         /* Check if we actually sent an ACK vector */
 771         if (ap->dccpap_ack_seqno == DCCP_MAX_SEQNO + 1)
 772                 return;
 773
 774         if (ackno == ap->dccpap_ack_seqno) {
 775 #ifdef CONFIG_IP_DCCP_DEBUG
 776                 struct dccp_sock *dp = dccp_sk(sk);
 777                 const char *debug_prefix = dp->dccps_role == DCCP_ROLE_CLIENT ?
 778                                         "CLIENT rx ack: " : "server rx ack: ";
 779 #endif
 780                 dccp_pr_debug("%sACK packet 0, len=%d, ack_seqno=%llu, "
 781                               "ack_ackno=%llu, ACKED!\n",
 782                               debug_prefix, 1,
 783                               (unsigned long long) ap->dccpap_ack_seqno,
 784                               (unsigned long long) ap->dccpap_ack_ackno);
 785                 dccp_ackpkts_trow_away_ack_record(ap);
 786                 ap->dccpap_ack_seqno = DCCP_MAX_SEQNO + 1;
 787         }
 788 }
 789
 790 static void dccp_ackpkts_check_rcv_ackvector(struct dccp_ackpkts *ap,
 791                                              struct sock *sk, u64 ackno,
 792                                              const unsigned char len,
 793                                              const unsigned char *vector)
 794 {
 795         unsigned char i;
 796
 797         /* Check if we actually sent an ACK vector */
 798         if (ap->dccpap_ack_seqno == DCCP_MAX_SEQNO + 1)
 799                 return;
 800         /*
 801          * We're in the receiver half connection, so if the received an ACK
 802          * vector ackno (e.g. 50) before dccpap_ack_seqno (e.g. 52), we're
 803          * not interested.
 804          *
 805          * Extra explanation with example:
 806          *
 807          * if we received an ACK vector with ackno 50, it can only be acking
 808          * 50, 49, 48, etc, not 52 (the seqno for the ACK vector we sent).
 809          */
 810         /* dccp_pr_debug("is %llu < %llu? ", ackno, ap->dccpap_ack_seqno); */
 811         if (before48(ackno, ap->dccpap_ack_seqno)) {
 812                 /* dccp_pr_debug_cat("yes\n"); */
 813                 return;
 814         }
 815         /* dccp_pr_debug_cat("no\n"); */
 816
 817         i = len;
 818         while (i--) {
 819                 const u8 rl = (*vector & DCCP_ACKPKTS_LEN_MASK);
 820                 u64 ackno_end_rl;
 821
 822                 dccp_set_seqno(&ackno_end_rl, ackno - rl);
 823
 824                 /*
 825                  * dccp_pr_debug("is %llu <= %llu <= %llu? ", ackno_end_rl,
 826                  * ap->dccpap_ack_seqno, ackno);
 827                  */
 828                 if (between48(ap->dccpap_ack_seqno, ackno_end_rl, ackno)) {
 829                         const u8 state = (*vector &
 830                                           DCCP_ACKPKTS_STATE_MASK) >> 6;
 831                         /* dccp_pr_debug_cat("yes\n"); */
 832
 833                         if (state != DCCP_ACKPKTS_STATE_NOT_RECEIVED) {
 834 #ifdef CONFIG_IP_DCCP_DEBUG
 835                                 struct dccp_sock *dp = dccp_sk(sk);
 836                                 const char *debug_prefix =
 837                                         dp->dccps_role == DCCP_ROLE_CLIENT ?
 838                                         "CLIENT rx ack: " : "server rx ack: ";
 839 #endif
 840                                 dccp_pr_debug("%sACK vector 0, len=%d, "
 841                                               "ack_seqno=%llu, ack_ackno=%llu, "
 842                                               "ACKED!\n",
 843                                               debug_prefix, len,
 844                                               (unsigned long long)
 845                                               ap->dccpap_ack_seqno,
 846                                               (unsigned long long)
 847                                               ap->dccpap_ack_ackno);
 848                                 dccp_ackpkts_trow_away_ack_record(ap);
 849                         }
 850                         /*
 851                          * If dccpap_ack_seqno was not received, no problem
 852                          * we'll send another ACK vector.
 853                          */
 854                         ap->dccpap_ack_seqno = DCCP_MAX_SEQNO + 1;
 855                         break;
 856                 }
 857                 /* dccp_pr_debug_cat("no\n"); */
 858
 859                 dccp_set_seqno(&ackno, ackno_end_rl - 1);
 860                 ++vector;
 861         }
 862 }