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;
  72
  73         /*
  74          *   Step 5: Prepare sequence numbers for Sync
  75          *     If P.type == Sync or P.type == SyncAck,
  76          *        If S.AWL <= P.ackno <= S.AWH and P.seqno >= S.SWL,
  77          *           / * P is valid, so update sequence number variables
  78          *               accordingly.  After this update, P will pass the tests
  79          *               in Step 6.  A SyncAck is generated if necessary in
  80          *               Step 15 * /
  81          *           Update S.GSR, S.SWL, S.SWH
  82          *        Otherwise,
  83          *           Drop packet and return
  84          */
  85         if (dh->dccph_type == DCCP_PKT_SYNC ||
  86             dh->dccph_type == DCCP_PKT_SYNCACK) {
  87                 if (between48(DCCP_SKB_CB(skb)->dccpd_ack_seq,
  88                               dp->dccps_awl, dp->dccps_awh) &&
  89                     !before48(DCCP_SKB_CB(skb)->dccpd_seq, dp->dccps_swl))
  90                         dccp_update_gsr(sk, DCCP_SKB_CB(skb)->dccpd_seq);
  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 = dp->dccps_gsr;
 116                 dccp_inc_seqno(&lswl);
 117                 lawl = dp->dccps_gar;
 118         }
 119
 120         if (between48(DCCP_SKB_CB(skb)->dccpd_seq, lswl, dp->dccps_swh) &&
 121             (DCCP_SKB_CB(skb)->dccpd_ack_seq == DCCP_PKT_WITHOUT_ACK_SEQ ||
 122              between48(DCCP_SKB_CB(skb)->dccpd_ack_seq,
 123                        lawl, dp->dccps_awh))) {
 124                 dccp_update_gsr(sk, DCCP_SKB_CB(skb)->dccpd_seq);
 125
 126                 if (dh->dccph_type != DCCP_PKT_SYNC &&
 127                     (DCCP_SKB_CB(skb)->dccpd_ack_seq !=
 128                      DCCP_PKT_WITHOUT_ACK_SEQ))
 129                         dp->dccps_gar = DCCP_SKB_CB(skb)->dccpd_ack_seq;
 130         } else {
 131                 DCCP_WARN("DCCP: Step 6 failed for %s packet, "
 132                           "(LSWL(%llu) <= P.seqno(%llu) <= S.SWH(%llu)) and "
 133                           "(P.ackno %s or LAWL(%llu) <= P.ackno(%llu) <= S.AWH(%llu), "
 134                           "sending SYNC...\n",  dccp_packet_name(dh->dccph_type),
 135                           (unsigned long long) lswl,
 136                           (unsigned long long) DCCP_SKB_CB(skb)->dccpd_seq,
 137                           (unsigned long long) dp->dccps_swh,
 138                           (DCCP_SKB_CB(skb)->dccpd_ack_seq ==
 139                                 DCCP_PKT_WITHOUT_ACK_SEQ) ? "doesn't exist" : "exists",
 140                           (unsigned long long) lawl,
 141                           (unsigned long long) DCCP_SKB_CB(skb)->dccpd_ack_seq,
 142                           (unsigned long long) dp->dccps_awh);
 143                 dccp_send_sync(sk, DCCP_SKB_CB(skb)->dccpd_seq, DCCP_PKT_SYNC);
 144                 return -1;
 145         }
 146
 147         return 0;
 148 }
 149
 150 static int __dccp_rcv_established(struct sock *sk, struct sk_buff *skb,
 151                                   const struct dccp_hdr *dh, const unsigned len)
 152 {
 153         struct dccp_sock *dp = dccp_sk(sk);
 154
 155         switch (dccp_hdr(skb)->dccph_type) {
 156         case DCCP_PKT_DATAACK:
 157         case DCCP_PKT_DATA:
 158                 /*
 159                  * FIXME: check if sk_receive_queue is full, schedule DATA_DROPPED
 160                  * option if it is.
 161                  */
 162                 __skb_pull(skb, dh->dccph_doff * 4);
 163                 __skb_queue_tail(&sk->sk_receive_queue, skb);
 164                 skb_set_owner_r(skb, sk);
 165                 sk->sk_data_ready(sk, 0);
 166                 return 0;
 167         case DCCP_PKT_ACK:
 168                 goto discard;
 169         case DCCP_PKT_RESET:
 170                 /*
 171                  *  Step 9: Process Reset
 172                  *      If P.type == Reset,
 173                  *              Tear down connection
 174                  *              S.state := TIMEWAIT
 175                  *              Set TIMEWAIT timer
 176                  *              Drop packet and return
 177                 */
 178                 dccp_fin(sk, skb);
 179                 dccp_time_wait(sk, DCCP_TIME_WAIT, 0);
 180                 return 0;
 181         case DCCP_PKT_CLOSEREQ:
 182                 dccp_rcv_closereq(sk, skb);
 183                 goto discard;
 184         case DCCP_PKT_CLOSE:
 185                 dccp_rcv_close(sk, skb);
 186                 return 0;
 187         case DCCP_PKT_REQUEST:
 188                 /* Step 7
 189                  *   or (S.is_server and P.type == Response)
 190                  *   or (S.is_client and P.type == Request)
 191                  *   or (S.state >= OPEN and P.type == Request
 192                  *      and P.seqno >= S.OSR)
 193                  *    or (S.state >= OPEN and P.type == Response
 194                  *      and P.seqno >= S.OSR)
 195                  *    or (S.state == RESPOND and P.type == Data),
 196                  *  Send Sync packet acknowledging P.seqno
 197                  *  Drop packet and return
 198                  */
 199                 if (dp->dccps_role != DCCP_ROLE_LISTEN)
 200                         goto send_sync;
 201                 goto check_seq;
 202         case DCCP_PKT_RESPONSE:
 203                 if (dp->dccps_role != DCCP_ROLE_CLIENT)
 204                         goto send_sync;
 205 check_seq:
 206                 if (!before48(DCCP_SKB_CB(skb)->dccpd_seq, dp->dccps_osr)) {
 207 send_sync:
 208                         dccp_send_sync(sk, DCCP_SKB_CB(skb)->dccpd_seq,
 209                                        DCCP_PKT_SYNC);
 210                 }
 211                 break;
 212         case DCCP_PKT_SYNC:
 213                 dccp_send_sync(sk, DCCP_SKB_CB(skb)->dccpd_seq,
 214                                DCCP_PKT_SYNCACK);
 215                 /*
 216                  * From RFC 4340, sec. 5.7
 217                  *
 218                  * As with DCCP-Ack packets, DCCP-Sync and DCCP-SyncAck packets
 219                  * MAY have non-zero-length application data areas, whose
 220                  * contents receivers MUST ignore.
 221                  */
 222                 goto discard;
 223         }
 224
 225         DCCP_INC_STATS_BH(DCCP_MIB_INERRS);
 226 discard:
 227         __kfree_skb(skb);
 228         return 0;
 229 }
 230
 231 int dccp_rcv_established(struct sock *sk, struct sk_buff *skb,
 232                          const struct dccp_hdr *dh, const unsigned len)
 233 {
 234         struct dccp_sock *dp = dccp_sk(sk);
 235
 236         if (dccp_check_seqno(sk, skb))
 237                 goto discard;
 238
 239         if (dccp_parse_options(sk, skb))
 240                 goto discard;
 241
 242         if (DCCP_SKB_CB(skb)->dccpd_ack_seq != DCCP_PKT_WITHOUT_ACK_SEQ)
 243                 dccp_event_ack_recv(sk, skb);
 244
 245         if (dccp_msk(sk)->dccpms_send_ack_vector &&
 246             dccp_ackvec_add(dp->dccps_hc_rx_ackvec, sk,
 247                             DCCP_SKB_CB(skb)->dccpd_seq,
 248                             DCCP_ACKVEC_STATE_RECEIVED))
 249                 goto discard;
 250
 251         ccid_hc_rx_packet_recv(dp->dccps_hc_rx_ccid, sk, skb);
 252         ccid_hc_tx_packet_recv(dp->dccps_hc_tx_ccid, sk, skb);
 253
 254         return __dccp_rcv_established(sk, skb, dh, len);
 255 discard:
 256         __kfree_skb(skb);
 257         return 0;
 258 }
 259
 260 EXPORT_SYMBOL_GPL(dccp_rcv_established);
 261
 262 static int dccp_rcv_request_sent_state_process(struct sock *sk,
 263                                                struct sk_buff *skb,
 264                                                const struct dccp_hdr *dh,
 265                                                const unsigned len)
 266 {
 267         /*
 268          *  Step 4: Prepare sequence numbers in REQUEST
 269          *     If S.state == REQUEST,
 270          *        If (P.type == Response or P.type == Reset)
 271          *              and S.AWL <= P.ackno <= S.AWH,
 272          *           / * Set sequence number variables corresponding to the
 273          *              other endpoint, so P will pass the tests in Step 6 * /
 274          *           Set S.GSR, S.ISR, S.SWL, S.SWH
 275          *           / * Response processing continues in Step 10; Reset
 276          *              processing continues in Step 9 * /
 277         */
 278         if (dh->dccph_type == DCCP_PKT_RESPONSE) {
 279                 const struct inet_connection_sock *icsk = inet_csk(sk);
 280                 struct dccp_sock *dp = dccp_sk(sk);
 281
 282                 /* Stop the REQUEST timer */
 283                 inet_csk_clear_xmit_timer(sk, ICSK_TIME_RETRANS);
 284                 BUG_TRAP(sk->sk_send_head != NULL);
 285                 __kfree_skb(sk->sk_send_head);
 286                 sk->sk_send_head = NULL;
 287
 288                 if (!between48(DCCP_SKB_CB(skb)->dccpd_ack_seq,
 289                                dp->dccps_awl, dp->dccps_awh)) {
 290                         dccp_pr_debug("invalid ackno: S.AWL=%llu, "
 291                                       "P.ackno=%llu, S.AWH=%llu \n",
 292                                       (unsigned long long)dp->dccps_awl,
 293                            (unsigned long long)DCCP_SKB_CB(skb)->dccpd_ack_seq,
 294                                       (unsigned long long)dp->dccps_awh);
 295                         goto out_invalid_packet;
 296                 }
 297
 298                 if (dccp_parse_options(sk, skb))
 299                         goto out_invalid_packet;
 300
 301                 if (dccp_msk(sk)->dccpms_send_ack_vector &&
 302                     dccp_ackvec_add(dp->dccps_hc_rx_ackvec, sk,
 303                                     DCCP_SKB_CB(skb)->dccpd_seq,
 304                                     DCCP_ACKVEC_STATE_RECEIVED))
 305                         goto out_invalid_packet; /* FIXME: change error code */
 306
 307                 dp->dccps_isr = DCCP_SKB_CB(skb)->dccpd_seq;
 308                 dccp_update_gsr(sk, dp->dccps_isr);
 309                 /*
 310                  * SWL and AWL are initially adjusted so that they are not less than
 311                  * the initial Sequence Numbers received and sent, respectively:
 312                  *      SWL := max(GSR + 1 - floor(W/4), ISR),
 313                  *      AWL := max(GSS - W' + 1, ISS).
 314                  * These adjustments MUST be applied only at the beginning of the
 315                  * connection.
 316                  *
 317                  * AWL was adjusted in dccp_v4_connect -acme
 318                  */
 319                 dccp_set_seqno(&dp->dccps_swl,
 320                                max48(dp->dccps_swl, dp->dccps_isr));
 321
 322                 dccp_sync_mss(sk, icsk->icsk_pmtu_cookie);
 323
 324                 /*
 325                  *    Step 10: Process REQUEST state (second part)
 326                  *       If S.state == REQUEST,
 327                  *        / * If we get here, P is a valid Response from the
 328                  *            server (see Step 4), and we should move to
 329                  *            PARTOPEN state. PARTOPEN means send an Ack,
 330                  *            don't send Data packets, retransmit Acks
 331                  *            periodically, and always include any Init Cookie
 332                  *            from the Response * /
 333                  *        S.state := PARTOPEN
 334                  *        Set PARTOPEN timer
 335                  *        Continue with S.state == PARTOPEN
 336                  *        / * Step 12 will send the Ack completing the
 337                  *            three-way handshake * /
 338                  */
 339                 dccp_set_state(sk, DCCP_PARTOPEN);
 340
 341                 /* Make sure socket is routed, for correct metrics. */
 342                 icsk->icsk_af_ops->rebuild_header(sk);
 343
 344                 if (!sock_flag(sk, SOCK_DEAD)) {
 345                         sk->sk_state_change(sk);
 346                         sk_wake_async(sk, 0, POLL_OUT);
 347                 }
 348
 349                 if (sk->sk_write_pending || icsk->icsk_ack.pingpong ||
 350                     icsk->icsk_accept_queue.rskq_defer_accept) {
 351                         /* Save one ACK. Data will be ready after
 352                          * several ticks, if write_pending is set.
 353                          *
 354                          * It may be deleted, but with this feature tcpdumps
 355                          * look so _wonderfully_ clever, that I was not able
 356                          * to stand against the temptation 8)     --ANK
 357                          */
 358                         /*
 359                          * OK, in DCCP we can as well do a similar trick, its
 360                          * even in the draft, but there is no need for us to
 361                          * schedule an ack here, as dccp_sendmsg does this for
 362                          * us, also stated in the draft. -acme
 363                          */
 364                         __kfree_skb(skb);
 365                         return 0;
 366                 }
 367                 dccp_send_ack(sk);
 368                 return -1;
 369         }
 370
 371 out_invalid_packet:
 372         /* dccp_v4_do_rcv will send a reset */
 373         DCCP_SKB_CB(skb)->dccpd_reset_code = DCCP_RESET_CODE_PACKET_ERROR;
 374         return 1;
 375 }
 376
 377 static int dccp_rcv_respond_partopen_state_process(struct sock *sk,
 378                                                    struct sk_buff *skb,
 379                                                    const struct dccp_hdr *dh,
 380                                                    const unsigned len)
 381 {
 382         int queued = 0;
 383
 384         switch (dh->dccph_type) {
 385         case DCCP_PKT_RESET:
 386                 inet_csk_clear_xmit_timer(sk, ICSK_TIME_DACK);
 387                 break;
 388         case DCCP_PKT_DATA:
 389                 if (sk->sk_state == DCCP_RESPOND)
 390                         break;
 391         case DCCP_PKT_DATAACK:
 392         case DCCP_PKT_ACK:
 393                 /*
 394                  * FIXME: we should be reseting the PARTOPEN (DELACK) timer
 395                  * here but only if we haven't used the DELACK timer for
 396                  * something else, like sending a delayed ack for a TIMESTAMP
 397                  * echo, etc, for now were not clearing it, sending an extra
 398                  * ACK when there is nothing else to do in DELACK is not a big
 399                  * deal after all.
 400                  */
 401
 402                 /* Stop the PARTOPEN timer */
 403                 if (sk->sk_state == DCCP_PARTOPEN)
 404                         inet_csk_clear_xmit_timer(sk, ICSK_TIME_DACK);
 405
 406                 dccp_sk(sk)->dccps_osr = DCCP_SKB_CB(skb)->dccpd_seq;
 407                 dccp_set_state(sk, DCCP_OPEN);
 408
 409                 if (dh->dccph_type == DCCP_PKT_DATAACK ||
 410                     dh->dccph_type == DCCP_PKT_DATA) {
 411                         __dccp_rcv_established(sk, skb, dh, len);
 412                         queued = 1; /* packet was queued
 413                                        (by __dccp_rcv_established) */
 414                 }
 415                 break;
 416         }
 417
 418         return queued;
 419 }
 420
 421 int dccp_rcv_state_process(struct sock *sk, struct sk_buff *skb,
 422                            struct dccp_hdr *dh, unsigned len)
 423 {
 424         struct dccp_sock *dp = dccp_sk(sk);
 425         struct dccp_skb_cb *dcb = DCCP_SKB_CB(skb);
 426         const int old_state = sk->sk_state;
 427         int queued = 0;
 428
 429         /*
 430          *  Step 3: Process LISTEN state
 431          *
 432          *     If S.state == LISTEN,
 433          *       If P.type == Request or P contains a valid Init Cookie option,
 434          *            (* Must scan the packet's options to check for Init
 435          *               Cookies.  Only Init Cookies are processed here,
 436          *               however; other options are processed in Step 8.  This
 437          *               scan need only be performed if the endpoint uses Init
 438          *               Cookies *)
 439          *            (* Generate a new socket and switch to that socket *)
 440          *            Set S := new socket for this port pair
 441          *            S.state = RESPOND
 442          *            Choose S.ISS (initial seqno) or set from Init Cookies
 443          *            Initialize S.GAR := S.ISS
 444          *            Set S.ISR, S.GSR, S.SWL, S.SWH from packet or Init
 445          *            Cookies Continue with S.state == RESPOND
 446          *            (* A Response packet will be generated in Step 11 *)
 447          *       Otherwise,
 448          *            Generate Reset(No Connection) unless P.type == Reset
 449          *            Drop packet and return
 450          */
 451         if (sk->sk_state == DCCP_LISTEN) {
 452                 if (dh->dccph_type == DCCP_PKT_REQUEST) {
 453                         if (inet_csk(sk)->icsk_af_ops->conn_request(sk,
 454                                                                     skb) < 0)
 455                                 return 1;
 456
 457                         /* FIXME: do congestion control initialization */
 458                         goto discard;
 459                 }
 460                 if (dh->dccph_type == DCCP_PKT_RESET)
 461                         goto discard;
 462
 463                 /* Caller (dccp_v4_do_rcv) will send Reset */
 464                 dcb->dccpd_reset_code = DCCP_RESET_CODE_NO_CONNECTION;
 465                 return 1;
 466         }
 467
 468         if (sk->sk_state != DCCP_REQUESTING) {
 469                 if (dccp_check_seqno(sk, skb))
 470                         goto discard;
 471
 472                 /*
 473                  * Step 8: Process options and mark acknowledgeable
 474                  */
 475                 if (dccp_parse_options(sk, skb))
 476                         goto discard;
 477
 478                 if (dcb->dccpd_ack_seq != DCCP_PKT_WITHOUT_ACK_SEQ)
 479                         dccp_event_ack_recv(sk, skb);
 480
 481                 if (dccp_msk(sk)->dccpms_send_ack_vector &&
 482                     dccp_ackvec_add(dp->dccps_hc_rx_ackvec, sk,
 483                                     DCCP_SKB_CB(skb)->dccpd_seq,
 484                                     DCCP_ACKVEC_STATE_RECEIVED))
 485                         goto discard;
 486
 487                 ccid_hc_rx_packet_recv(dp->dccps_hc_rx_ccid, sk, skb);
 488                 ccid_hc_tx_packet_recv(dp->dccps_hc_tx_ccid, sk, skb);
 489         }
 490
 491         /*
 492          *  Step 9: Process Reset
 493          *      If P.type == Reset,
 494          *              Tear down connection
 495          *              S.state := TIMEWAIT
 496          *              Set TIMEWAIT timer
 497          *              Drop packet and return
 498         */
 499         if (dh->dccph_type == DCCP_PKT_RESET) {
 500                 /*
 501                  * Queue the equivalent of TCP fin so that dccp_recvmsg
 502                  * exits the loop
 503                  */
 504                 dccp_fin(sk, skb);
 505                 dccp_time_wait(sk, DCCP_TIME_WAIT, 0);
 506                 return 0;
 507                 /*
 508                  *   Step 7: Check for unexpected packet types
 509                  *      If (S.is_server and P.type == CloseReq)
 510                  *          or (S.is_server and P.type == Response)
 511                  *          or (S.is_client and P.type == Request)
 512                  *          or (S.state == RESPOND and P.type == Data),
 513                  *        Send Sync packet acknowledging P.seqno
 514                  *        Drop packet and return
 515                  */
 516         } else if ((dp->dccps_role != DCCP_ROLE_CLIENT &&
 517                     (dh->dccph_type == DCCP_PKT_RESPONSE ||
 518                      dh->dccph_type == DCCP_PKT_CLOSEREQ)) ||
 519                     (dp->dccps_role == DCCP_ROLE_CLIENT &&
 520                      dh->dccph_type == DCCP_PKT_REQUEST) ||
 521                     (sk->sk_state == DCCP_RESPOND &&
 522                      dh->dccph_type == DCCP_PKT_DATA)) {
 523                 dccp_send_sync(sk, dcb->dccpd_seq, DCCP_PKT_SYNC);
 524                 goto discard;
 525         } else if (dh->dccph_type == DCCP_PKT_CLOSEREQ) {
 526                 dccp_rcv_closereq(sk, skb);
 527                 goto discard;
 528         } else if (dh->dccph_type == DCCP_PKT_CLOSE) {
 529                 dccp_rcv_close(sk, skb);
 530                 return 0;
 531         }
 532
 533         if (unlikely(dh->dccph_type == DCCP_PKT_SYNC)) {
 534                 dccp_send_sync(sk, dcb->dccpd_seq, DCCP_PKT_SYNCACK);
 535                 goto discard;
 536         }
 537
 538         switch (sk->sk_state) {
 539         case DCCP_CLOSED:
 540                 dcb->dccpd_reset_code = DCCP_RESET_CODE_NO_CONNECTION;
 541                 return 1;
 542
 543         case DCCP_REQUESTING:
 544                 /* FIXME: do congestion control initialization */
 545
 546                 queued = dccp_rcv_request_sent_state_process(sk, skb, dh, len);
 547                 if (queued >= 0)
 548                         return queued;
 549
 550                 __kfree_skb(skb);
 551                 return 0;
 552
 553         case DCCP_RESPOND:
 554         case DCCP_PARTOPEN:
 555                 queued = dccp_rcv_respond_partopen_state_process(sk, skb,
 556                                                                  dh, len);
 557                 break;
 558         }
 559
 560         if (dh->dccph_type == DCCP_PKT_ACK ||
 561             dh->dccph_type == DCCP_PKT_DATAACK) {
 562                 switch (old_state) {
 563                 case DCCP_PARTOPEN:
 564                         sk->sk_state_change(sk);
 565                         sk_wake_async(sk, 0, POLL_OUT);
 566                         break;
 567                 }
 568         }
 569
 570         if (!queued) {
 571 discard:
 572                 __kfree_skb(skb);
 573         }
 574         return 0;
 575 }
 576
 577 EXPORT_SYMBOL_GPL(dccp_rcv_state_process);