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