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