LXR linux/net/dccp/input.c

   1/*
   2 *  net/dccp/input.c
   3 *
   4 *  An implementation of the DCCP protocol
   5 *  Arnaldo Carvalho de Melo <acme@conectiva.com.br>
   6 *
   7 *      This program is free software; you can redistribute it and/or
   8 *      modify it under the terms of the GNU General Public License
   9 *      as published by the Free Software Foundation; either version
  10 *      2 of the License, or (at your option) any later version.
  11 */
  12
  13#include <linux/dccp.h>
  14#include <linux/skbuff.h>
  15
  16#include <net/sock.h>
  17
  18#include "ackvec.h"
  19#include "ccid.h"
  20#include "dccp.h"
  21
  22/* rate-limit for syncs in reply to sequence-invalid packets; RFC 4340, 7.5.4 */
  23int sysctl_dccp_sync_ratelimit  __read_mostly = HZ / 8;
  24
  25static void dccp_fin(struct sock *sk, struct sk_buff *skb)
  26{
  27        sk->sk_shutdown |= RCV_SHUTDOWN;
  28        sock_set_flag(sk, SOCK_DONE);
  29        __skb_pull(skb, dccp_hdr(skb)->dccph_doff * 4);
  30        __skb_queue_tail(&sk->sk_receive_queue, skb);
  31        skb_set_owner_r(skb, sk);
  32        sk->sk_data_ready(sk, 0);
  33}
  34
  35static void dccp_rcv_close(struct sock *sk, struct sk_buff *skb)
  36{
  37        dccp_send_reset(sk, DCCP_RESET_CODE_CLOSED);
  38        dccp_fin(sk, skb);
  39        dccp_set_state(sk, DCCP_CLOSED);
  40        sk_wake_async(sk, 1, POLL_HUP);
  41}
  42
  43static void dccp_rcv_closereq(struct sock *sk, struct sk_buff *skb)
  44{
  45        /*
  46         *   Step 7: Check for unexpected packet types
  47         *      If (S.is_server and P.type == CloseReq)
  48         *        Send Sync packet acknowledging P.seqno
  49         *        Drop packet and return
  50         */
  51        if (dccp_sk(sk)->dccps_role != DCCP_ROLE_CLIENT) {
  52                dccp_send_sync(sk, DCCP_SKB_CB(skb)->dccpd_seq, DCCP_PKT_SYNC);
  53                return;
  54        }
  55
  56        if (sk->sk_state != DCCP_CLOSING)
  57                dccp_set_state(sk, DCCP_CLOSING);
  58        dccp_send_close(sk, 0);
  59}
  60
  61static u8 dccp_reset_code_convert(const u8 code)
  62{
  63        const u8 error_code[] = {
  64        [DCCP_RESET_CODE_CLOSED]             = 0,       /* normal termination */
  65        [DCCP_RESET_CODE_UNSPECIFIED]        = 0,       /* nothing known */
  66        [DCCP_RESET_CODE_ABORTED]            = ECONNRESET,
  67
  68        [DCCP_RESET_CODE_NO_CONNECTION]      = ECONNREFUSED,
  69        [DCCP_RESET_CODE_CONNECTION_REFUSED] = ECONNREFUSED,
  70        [DCCP_RESET_CODE_TOO_BUSY]           = EUSERS,
  71        [DCCP_RESET_CODE_AGGRESSION_PENALTY] = EDQUOT,
  72
  73        [DCCP_RESET_CODE_PACKET_ERROR]       = ENOMSG,
  74        [DCCP_RESET_CODE_BAD_INIT_COOKIE]    = EBADR,
  75        [DCCP_RESET_CODE_BAD_SERVICE_CODE]   = EBADRQC,
  76        [DCCP_RESET_CODE_OPTION_ERROR]       = EILSEQ,
  77        [DCCP_RESET_CODE_MANDATORY_ERROR]    = EOPNOTSUPP,
  78        };
  79
  80        return code >= DCCP_MAX_RESET_CODES ? 0 : error_code[code];
  81}
  82
  83static void dccp_rcv_reset(struct sock *sk, struct sk_buff *skb)
  84{
  85        u8 err = dccp_reset_code_convert(dccp_hdr_reset(skb)->dccph_reset_code);
  86
  87        sk->sk_err = err;
  88
  89        /* Queue the equivalent of TCP fin so that dccp_recvmsg exits the loop */
  90        dccp_fin(sk, skb);
  91
  92        if (err && !sock_flag(sk, SOCK_DEAD))
  93                sk_wake_async(sk, 0, POLL_ERR);
  94        dccp_time_wait(sk, DCCP_TIME_WAIT, 0);
  95}
  96
  97static void dccp_event_ack_recv(struct sock *sk, struct sk_buff *skb)
  98{
  99        struct dccp_sock *dp = dccp_sk(sk);
 100
 101        if (dccp_msk(sk)->dccpms_send_ack_vector)
 102                dccp_ackvec_check_rcv_ackno(dp->dccps_hc_rx_ackvec, sk,
 103                                            DCCP_SKB_CB(skb)->dccpd_ack_seq);
 104}
 105
 106static int dccp_check_seqno(struct sock *sk, struct sk_buff *skb)
 107{
 108        const struct dccp_hdr *dh = dccp_hdr(skb);
 109        struct dccp_sock *dp = dccp_sk(sk);
 110        u64 lswl, lawl, seqno = DCCP_SKB_CB(skb)->dccpd_seq,
 111                        ackno = DCCP_SKB_CB(skb)->dccpd_ack_seq;
 112
 113        /*
 114         *   Step 5: Prepare sequence numbers for Sync
 115         *     If P.type == Sync or P.type == SyncAck,
 116         *        If S.AWL <= P.ackno <= S.AWH and P.seqno >= S.SWL,
 117         *           / * P is valid, so update sequence number variables
 118         *               accordingly.  After this update, P will pass the tests
 119         *               in Step 6.  A SyncAck is generated if necessary in
 120         *               Step 15 * /
 121         *           Update S.GSR, S.SWL, S.SWH
 122         *        Otherwise,
 123         *           Drop packet and return
 124         */
 125        if (dh->dccph_type == DCCP_PKT_SYNC ||
 126            dh->dccph_type == DCCP_PKT_SYNCACK) {
 127                if (between48(ackno, dp->dccps_awl, dp->dccps_awh) &&
 128                    dccp_delta_seqno(dp->dccps_swl, seqno) >= 0)
 129                        dccp_update_gsr(sk, seqno);
 130                else
 131                        return -1;
 132        }
 133
 134        /*
 135         *   Step 6: Check sequence numbers
 136         *      Let LSWL = S.SWL and LAWL = S.AWL
 137         *      If P.type == CloseReq or P.type == Close or P.type == Reset,
 138         *        LSWL := S.GSR + 1, LAWL := S.GAR
 139         *      If LSWL <= P.seqno <= S.SWH
 140         *           and (P.ackno does not exist or LAWL <= P.ackno <= S.AWH),
 141         *        Update S.GSR, S.SWL, S.SWH
 142         *        If P.type != Sync,
 143         *           Update S.GAR
 144         */
 145        lswl = dp->dccps_swl;
 146        lawl = dp->dccps_awl;
 147
 148        if (dh->dccph_type == DCCP_PKT_CLOSEREQ ||
 149            dh->dccph_type == DCCP_PKT_CLOSE ||
 150            dh->dccph_type == DCCP_PKT_RESET) {
 151                lswl = ADD48(dp->dccps_gsr, 1);
 152                lawl = dp->dccps_gar;
 153        }
 154
 155        if (between48(seqno, lswl, dp->dccps_swh) &&
 156            (ackno == DCCP_PKT_WITHOUT_ACK_SEQ ||
 157             between48(ackno, lawl, dp->dccps_awh))) {
 158                dccp_update_gsr(sk, seqno);
 159
 160                if (dh->dccph_type != DCCP_PKT_SYNC &&
 161                    (ackno != DCCP_PKT_WITHOUT_ACK_SEQ))
 162                        dp->dccps_gar = ackno;
 163        } else {
 164                unsigned long now = jiffies;
 165                /*
 166                 *   Step 6: Check sequence numbers
 167                 *      Otherwise,
 168                 *         If P.type == Reset,
 169                 *            Send Sync packet acknowledging S.GSR
 170                 *         Otherwise,
 171                 *            Send Sync packet acknowledging P.seqno
 172                 *      Drop packet and return
 173                 *
 174                 *   These Syncs are rate-limited as per RFC 4340, 7.5.4:
 175                 *   at most 1 / (dccp_sync_rate_limit * HZ) Syncs per second.
 176                 */
 177                if (time_before(now, (dp->dccps_rate_last +
 178                                      sysctl_dccp_sync_ratelimit)))
 179                        return 0;
 180
 181                DCCP_WARN("DCCP: Step 6 failed for %s packet, "
 182                          "(LSWL(%llu) <= P.seqno(%llu) <= S.SWH(%llu)) and "
 183                          "(P.ackno %s or LAWL(%llu) <= P.ackno(%llu) <= S.AWH(%llu), "
 184                          "sending SYNC...\n",  dccp_packet_name(dh->dccph_type),
 185                          (unsigned long long) lswl, (unsigned long long) seqno,
 186                          (unsigned long long) dp->dccps_swh,
 187                          (ackno == DCCP_PKT_WITHOUT_ACK_SEQ) ? "doesn't exist"
 188                                                              : "exists",
 189                          (unsigned long long) lawl, (unsigned long long) ackno,
 190                          (unsigned long long) dp->dccps_awh);
 191
 192                dp->dccps_rate_last = now;
 193
 194                if (dh->dccph_type == DCCP_PKT_RESET)
 195                        seqno = dp->dccps_gsr;
 196                dccp_send_sync(sk, seqno, DCCP_PKT_SYNC);
 197                return -1;
 198        }
 199
 200        return 0;
 201}
 202
 203static int __dccp_rcv_established(struct sock *sk, struct sk_buff *skb,
 204                                  const struct dccp_hdr *dh, const unsigned len)
 205{
 206        struct dccp_sock *dp = dccp_sk(sk);
 207
 208        switch (dccp_hdr(skb)->dccph_type) {
 209        case DCCP_PKT_DATAACK:
 210        case DCCP_PKT_DATA:
 211                /*
 212                 * FIXME: check if sk_receive_queue is full, schedule DATA_DROPPED
 213                 * option if it is.
 214                 */
 215                __skb_pull(skb, dh->dccph_doff * 4);
 216                __skb_queue_tail(&sk->sk_receive_queue, skb);
 217                skb_set_owner_r(skb, sk);
 218                sk->sk_data_ready(sk, 0);
 219                return 0;
 220        case DCCP_PKT_ACK:
 221                goto discard;
 222        case DCCP_PKT_RESET:
 223                /*
 224                 *  Step 9: Process Reset
 225                 *      If P.type == Reset,
 226                 *              Tear down connection
 227                 *              S.state := TIMEWAIT
 228                 *              Set TIMEWAIT timer
 229                 *              Drop packet and return
 230                 */
 231                dccp_rcv_reset(sk, skb);
 232                return 0;
 233        case DCCP_PKT_CLOSEREQ:
 234                dccp_rcv_closereq(sk, skb);
 235                goto discard;
 236        case DCCP_PKT_CLOSE:
 237                dccp_rcv_close(sk, skb);
 238                return 0;
 239        case DCCP_PKT_REQUEST:
 240                /* Step 7
 241                 *   or (S.is_server and P.type == Response)
 242                 *   or (S.is_client and P.type == Request)
 243                 *   or (S.state >= OPEN and P.type == Request
 244                 *      and P.seqno >= S.OSR)
 245                 *    or (S.state >= OPEN and P.type == Response
 246                 *      and P.seqno >= S.OSR)
 247                 *    or (S.state == RESPOND and P.type == Data),
 248                 *  Send Sync packet acknowledging P.seqno
 249                 *  Drop packet and return
 250                 */
 251                if (dp->dccps_role != DCCP_ROLE_LISTEN)
 252                        goto send_sync;
 253                goto check_seq;
 254        case DCCP_PKT_RESPONSE:
 255                if (dp->dccps_role != DCCP_ROLE_CLIENT)
 256                        goto send_sync;
 257check_seq:
 258                if (dccp_delta_seqno(dp->dccps_osr,
 259                                     DCCP_SKB_CB(skb)->dccpd_seq) >= 0) {
 260send_sync:
 261                        dccp_send_sync(sk, DCCP_SKB_CB(skb)->dccpd_seq,
 262                                       DCCP_PKT_SYNC);
 263                }
 264                break;
 265        case DCCP_PKT_SYNC:
 266                dccp_send_sync(sk, DCCP_SKB_CB(skb)->dccpd_seq,
 267                               DCCP_PKT_SYNCACK);
 268                /*
 269                 * From RFC 4340, sec. 5.7
 270                 *
 271                 * As with DCCP-Ack packets, DCCP-Sync and DCCP-SyncAck packets
 272                 * MAY have non-zero-length application data areas, whose
 273                 * contents receivers MUST ignore.
 274                 */
 275                goto discard;
 276        }
 277
 278        DCCP_INC_STATS_BH(DCCP_MIB_INERRS);
 279discard:
 280        __kfree_skb(skb);
 281        return 0;
 282}
 283
 284int dccp_rcv_established(struct sock *sk, struct sk_buff *skb,
 285                         const struct dccp_hdr *dh, const unsigned len)
 286{
 287        struct dccp_sock *dp = dccp_sk(sk);
 288
 289        if (dccp_check_seqno(sk, skb))
 290                goto discard;
 291
 292        if (dccp_parse_options(sk, skb))
 293                goto discard;
 294
 295        if (DCCP_SKB_CB(skb)->dccpd_ack_seq != DCCP_PKT_WITHOUT_ACK_SEQ)
 296                dccp_event_ack_recv(sk, skb);
 297
 298        if (dccp_msk(sk)->dccpms_send_ack_vector &&
 299            dccp_ackvec_add(dp->dccps_hc_rx_ackvec, sk,
 300                            DCCP_SKB_CB(skb)->dccpd_seq,
 301                            DCCP_ACKVEC_STATE_RECEIVED))
 302                goto discard;
 303
 304        ccid_hc_rx_packet_recv(dp->dccps_hc_rx_ccid, sk, skb);
 305        ccid_hc_tx_packet_recv(dp->dccps_hc_tx_ccid, sk, skb);
 306
 307        return __dccp_rcv_established(sk, skb, dh, len);
 308discard:
 309        __kfree_skb(skb);
 310        return 0;
 311}
 312
 313EXPORT_SYMBOL_GPL(dccp_rcv_established);
 314
 315static int dccp_rcv_request_sent_state_process(struct sock *sk,
 316                                               struct sk_buff *skb,
 317                                               const struct dccp_hdr *dh,
 318                                               const unsigned len)
 319{
 320        /*
 321         *  Step 4: Prepare sequence numbers in REQUEST
 322         *     If S.state == REQUEST,
 323         *        If (P.type == Response or P.type == Reset)
 324         *              and S.AWL <= P.ackno <= S.AWH,
 325         *           / * Set sequence number variables corresponding to the
 326         *              other endpoint, so P will pass the tests in Step 6 * /
 327         *           Set S.GSR, S.ISR, S.SWL, S.SWH
 328         *           / * Response processing continues in Step 10; Reset
 329         *              processing continues in Step 9 * /
 330        */
 331        if (dh->dccph_type == DCCP_PKT_RESPONSE) {
 332                const struct inet_connection_sock *icsk = inet_csk(sk);
 333                struct dccp_sock *dp = dccp_sk(sk);
 334                long tstamp = dccp_timestamp();
 335
 336                /* Stop the REQUEST timer */
 337                inet_csk_clear_xmit_timer(sk, ICSK_TIME_RETRANS);
 338                BUG_TRAP(sk->sk_send_head != NULL);
 339                __kfree_skb(sk->sk_send_head);
 340                sk->sk_send_head = NULL;
 341
 342                if (!between48(DCCP_SKB_CB(skb)->dccpd_ack_seq,
 343                               dp->dccps_awl, dp->dccps_awh)) {
 344                        dccp_pr_debug("invalid ackno: S.AWL=%llu, "
 345                                      "P.ackno=%llu, S.AWH=%llu \n",
 346                                      (unsigned long long)dp->dccps_awl,
 347                           (unsigned long long)DCCP_SKB_CB(skb)->dccpd_ack_seq,
 348                                      (unsigned long long)dp->dccps_awh);
 349                        goto out_invalid_packet;
 350                }
 351
 352                if (dccp_parse_options(sk, skb))
 353                        goto out_invalid_packet;
 354
 355                /* Obtain usec RTT sample from SYN exchange (used by CCID 3) */
 356                if (likely(dp->dccps_options_received.dccpor_timestamp_echo))
 357                        dp->dccps_syn_rtt = dccp_sample_rtt(sk, 10 * (tstamp -
 358                            dp->dccps_options_received.dccpor_timestamp_echo));
 359
 360                if (dccp_msk(sk)->dccpms_send_ack_vector &&
 361                    dccp_ackvec_add(dp->dccps_hc_rx_ackvec, sk,
 362                                    DCCP_SKB_CB(skb)->dccpd_seq,
 363                                    DCCP_ACKVEC_STATE_RECEIVED))
 364                        goto out_invalid_packet; /* FIXME: change error code */
 365
 366                dp->dccps_isr = DCCP_SKB_CB(skb)->dccpd_seq;
 367                dccp_update_gsr(sk, dp->dccps_isr);
 368                /*
 369                 * SWL and AWL are initially adjusted so that they are not less than
 370                 * the initial Sequence Numbers received and sent, respectively:
 371                 *      SWL := max(GSR + 1 - floor(W/4), ISR),
 372                 *      AWL := max(GSS - W' + 1, ISS).
 373                 * These adjustments MUST be applied only at the beginning of the
 374                 * connection.
 375                 *
 376                 * AWL was adjusted in dccp_v4_connect -acme
 377                 */
 378                dccp_set_seqno(&dp->dccps_swl,
 379                               max48(dp->dccps_swl, dp->dccps_isr));
 380
 381                dccp_sync_mss(sk, icsk->icsk_pmtu_cookie);
 382
 383                /*
 384                 *    Step 10: Process REQUEST state (second part)
 385                 *       If S.state == REQUEST,
 386                 *        / * If we get here, P is a valid Response from the
 387                 *            server (see Step 4), and we should move to
 388                 *            PARTOPEN state. PARTOPEN means send an Ack,
 389                 *            don't send Data packets, retransmit Acks
 390                 *            periodically, and always include any Init Cookie
 391                 *            from the Response * /
 392                 *        S.state := PARTOPEN
 393                 *        Set PARTOPEN timer
 394                 *        Continue with S.state == PARTOPEN
 395                 *        / * Step 12 will send the Ack completing the
 396                 *            three-way handshake * /
 397                 */
 398                dccp_set_state(sk, DCCP_PARTOPEN);
 399
 400                /* Make sure socket is routed, for correct metrics. */
 401                icsk->icsk_af_ops->rebuild_header(sk);
 402
 403                if (!sock_flag(sk, SOCK_DEAD)) {
 404                        sk->sk_state_change(sk);
 405                        sk_wake_async(sk, 0, POLL_OUT);
 406                }
 407
 408                if (sk->sk_write_pending || icsk->icsk_ack.pingpong ||
 409                    icsk->icsk_accept_queue.rskq_defer_accept) {
 410                        /* Save one ACK. Data will be ready after
 411                         * several ticks, if write_pending is set.
 412                         *
 413                         * It may be deleted, but with this feature tcpdumps
 414                         * look so _wonderfully_ clever, that I was not able
 415                         * to stand against the temptation 8)     --ANK
 416                         */
 417                        /*
 418                         * OK, in DCCP we can as well do a similar trick, its
 419                         * even in the draft, but there is no need for us to
 420                         * schedule an ack here, as dccp_sendmsg does this for
 421                         * us, also stated in the draft. -acme
 422                         */
 423                        __kfree_skb(skb);
 424                        return 0;
 425                }
 426                dccp_send_ack(sk);
 427                return -1;
 428        }
 429
 430out_invalid_packet:
 431        /* dccp_v4_do_rcv will send a reset */
 432        DCCP_SKB_CB(skb)->dccpd_reset_code = DCCP_RESET_CODE_PACKET_ERROR;
 433        return 1;
 434}
 435
 436static int dccp_rcv_respond_partopen_state_process(struct sock *sk,
 437                                                   struct sk_buff *skb,
 438                                                   const struct dccp_hdr *dh,
 439                                                   const unsigned len)
 440{
 441        int queued = 0;
 442
 443        switch (dh->dccph_type) {
 444        case DCCP_PKT_RESET:
 445                inet_csk_clear_xmit_timer(sk, ICSK_TIME_DACK);
 446                break;
 447        case DCCP_PKT_DATA:
 448                if (sk->sk_state == DCCP_RESPOND)
 449                        break;
 450        case DCCP_PKT_DATAACK:
 451        case DCCP_PKT_ACK:
 452                /*
 453                 * FIXME: we should be reseting the PARTOPEN (DELACK) timer
 454                 * here but only if we haven't used the DELACK timer for
 455                 * something else, like sending a delayed ack for a TIMESTAMP
 456                 * echo, etc, for now were not clearing it, sending an extra
 457                 * ACK when there is nothing else to do in DELACK is not a big
 458                 * deal after all.
 459                 */
 460
 461                /* Stop the PARTOPEN timer */
 462                if (sk->sk_state == DCCP_PARTOPEN)
 463                        inet_csk_clear_xmit_timer(sk, ICSK_TIME_DACK);
 464
 465                dccp_sk(sk)->dccps_osr = DCCP_SKB_CB(skb)->dccpd_seq;
 466                dccp_set_state(sk, DCCP_OPEN);
 467
 468                if (dh->dccph_type == DCCP_PKT_DATAACK ||
 469                    dh->dccph_type == DCCP_PKT_DATA) {
 470                        __dccp_rcv_established(sk, skb, dh, len);
 471                        queued = 1; /* packet was queued
 472                                       (by __dccp_rcv_established) */
 473                }
 474                break;
 475        }
 476
 477        return queued;
 478}
 479
 480int dccp_rcv_state_process(struct sock *sk, struct sk_buff *skb,
 481                           struct dccp_hdr *dh, unsigned len)
 482{
 483        struct dccp_sock *dp = dccp_sk(sk);
 484        struct dccp_skb_cb *dcb = DCCP_SKB_CB(skb);
 485        const int old_state = sk->sk_state;
 486        int queued = 0;
 487
 488        /*
 489         *  Step 3: Process LISTEN state
 490         *
 491         *     If S.state == LISTEN,
 492         *       If P.type == Request or P contains a valid Init Cookie option,
 493         *            (* Must scan the packet's options to check for Init
 494         *               Cookies.  Only Init Cookies are processed here,
 495         *               however; other options are processed in Step 8.  This
 496         *               scan need only be performed if the endpoint uses Init
 497         *               Cookies *)
 498         *            (* Generate a new socket and switch to that socket *)
 499         *            Set S := new socket for this port pair
 500         *            S.state = RESPOND
 501         *            Choose S.ISS (initial seqno) or set from Init Cookies
 502         *            Initialize S.GAR := S.ISS
 503         *            Set S.ISR, S.GSR, S.SWL, S.SWH from packet or Init
 504         *            Cookies Continue with S.state == RESPOND
 505         *            (* A Response packet will be generated in Step 11 *)
 506         *       Otherwise,
 507         *            Generate Reset(No Connection) unless P.type == Reset
 508         *            Drop packet and return
 509         */
 510        if (sk->sk_state == DCCP_LISTEN) {
 511                if (dh->dccph_type == DCCP_PKT_REQUEST) {
 512                        if (inet_csk(sk)->icsk_af_ops->conn_request(sk,
 513                                                                    skb) < 0)
 514                                return 1;
 515
 516                        /* FIXME: do congestion control initialization */
 517                        goto discard;
 518                }
 519                if (dh->dccph_type == DCCP_PKT_RESET)
 520                        goto discard;
 521
 522                /* Caller (dccp_v4_do_rcv) will send Reset */
 523                dcb->dccpd_reset_code = DCCP_RESET_CODE_NO_CONNECTION;
 524                return 1;
 525        }
 526
 527        if (sk->sk_state != DCCP_REQUESTING) {
 528                if (dccp_check_seqno(sk, skb))
 529                        goto discard;
 530
 531                /*
 532                 * Step 8: Process options and mark acknowledgeable
 533                 */
 534                if (dccp_parse_options(sk, skb))
 535                        goto discard;
 536
 537                if (dcb->dccpd_ack_seq != DCCP_PKT_WITHOUT_ACK_SEQ)
 538                        dccp_event_ack_recv(sk, skb);
 539
 540                if (dccp_msk(sk)->dccpms_send_ack_vector &&
 541                    dccp_ackvec_add(dp->dccps_hc_rx_ackvec, sk,
 542                                    DCCP_SKB_CB(skb)->dccpd_seq,
 543                                    DCCP_ACKVEC_STATE_RECEIVED))
 544                        goto discard;
 545
 546                ccid_hc_rx_packet_recv(dp->dccps_hc_rx_ccid, sk, skb);
 547                ccid_hc_tx_packet_recv(dp->dccps_hc_tx_ccid, sk, skb);
 548        }
 549
 550        /*
 551         *  Step 9: Process Reset
 552         *      If P.type == Reset,
 553         *              Tear down connection
 554         *              S.state := TIMEWAIT
 555         *              Set TIMEWAIT timer
 556         *              Drop packet and return
 557        */
 558        if (dh->dccph_type == DCCP_PKT_RESET) {
 559                dccp_rcv_reset(sk, skb);
 560                return 0;
 561                /*
 562                 *   Step 7: Check for unexpected packet types
 563                 *      If (S.is_server and P.type == CloseReq)
 564                 *          or (S.is_server and P.type == Response)
 565                 *          or (S.is_client and P.type == Request)
 566                 *          or (S.state == RESPOND and P.type == Data),
 567                 *        Send Sync packet acknowledging P.seqno
 568                 *        Drop packet and return
 569                 */
 570        } else if ((dp->dccps_role != DCCP_ROLE_CLIENT &&
 571                    (dh->dccph_type == DCCP_PKT_RESPONSE ||
 572                     dh->dccph_type == DCCP_PKT_CLOSEREQ)) ||
 573                    (dp->dccps_role == DCCP_ROLE_CLIENT &&
 574                     dh->dccph_type == DCCP_PKT_REQUEST) ||
 575                    (sk->sk_state == DCCP_RESPOND &&
 576                     dh->dccph_type == DCCP_PKT_DATA)) {
 577                dccp_send_sync(sk, dcb->dccpd_seq, DCCP_PKT_SYNC);
 578                goto discard;
 579        } else if (dh->dccph_type == DCCP_PKT_CLOSEREQ) {
 580                dccp_rcv_closereq(sk, skb);
 581                goto discard;
 582        } else if (dh->dccph_type == DCCP_PKT_CLOSE) {
 583                dccp_rcv_close(sk, skb);
 584                return 0;
 585        }
 586
 587        switch (sk->sk_state) {
 588        case DCCP_CLOSED:
 589                dcb->dccpd_reset_code = DCCP_RESET_CODE_NO_CONNECTION;
 590                return 1;
 591
 592        case DCCP_REQUESTING:
 593                /* FIXME: do congestion control initialization */
 594
 595                queued = dccp_rcv_request_sent_state_process(sk, skb, dh, len);
 596                if (queued >= 0)
 597                        return queued;
 598
 599                __kfree_skb(skb);
 600                return 0;
 601
 602        case DCCP_RESPOND:
 603        case DCCP_PARTOPEN:
 604                queued = dccp_rcv_respond_partopen_state_process(sk, skb,
 605                                                                 dh, len);
 606                break;
 607        }
 608
 609        if (dh->dccph_type == DCCP_PKT_ACK ||
 610            dh->dccph_type == DCCP_PKT_DATAACK) {
 611                switch (old_state) {
 612                case DCCP_PARTOPEN:
 613                        sk->sk_state_change(sk);
 614                        sk_wake_async(sk, 0, POLL_OUT);
 615                        break;
 616                }
 617        } else if (unlikely(dh->dccph_type == DCCP_PKT_SYNC)) {
 618                dccp_send_sync(sk, dcb->dccpd_seq, DCCP_PKT_SYNCACK);
 619                goto discard;
 620        }
 621
 622        if (!queued) {
 623discard:
 624                __kfree_skb(skb);
 625        }
 626        return 0;
 627}
 628
 629EXPORT_SYMBOL_GPL(dccp_rcv_state_process);
 630
 631/**
 632 *  dccp_sample_rtt  -  Validate and finalise computation of RTT sample
 633 *  @delta:     number of microseconds between packet and acknowledgment
 634 *  The routine is kept generic to work in different contexts. It should be
 635 *  called immediately when the ACK used for the RTT sample arrives.
 636 */
 637u32 dccp_sample_rtt(struct sock *sk, long delta)
 638{
 639        /* dccpor_elapsed_time is either zeroed out or set and > 0 */
 640        delta -= dccp_sk(sk)->dccps_options_received.dccpor_elapsed_time * 10;
 641
 642        if (unlikely(delta <= 0)) {
 643                DCCP_WARN("unusable RTT sample %ld, using min\n", delta);
 644                return DCCP_SANE_RTT_MIN;
 645        }
 646        if (unlikely(delta > DCCP_SANE_RTT_MAX)) {
 647                DCCP_WARN("RTT sample %ld too large, using max\n", delta);
 648                return DCCP_SANE_RTT_MAX;
 649        }
 650
 651        return delta;
 652}
 653
 654EXPORT_SYMBOL_GPL(dccp_sample_rtt);
 655