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/config.h>
  14 #include <linux/dccp.h>
  15 #include <linux/skbuff.h>
  16
  17 #include <net/sock.h>
  18
  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         switch (sk->sk_state) {
  35         case DCCP_PARTOPEN:
  36         case DCCP_OPEN:
  37                 dccp_v4_send_reset(sk, DCCP_RESET_CODE_CLOSED);
  38                 dccp_fin(sk, skb);
  39                 dccp_set_state(sk, DCCP_CLOSED);
  40                 break;
  41         }
  42 }
  43
  44 static void dccp_rcv_closereq(struct sock *sk, struct sk_buff *skb)
  45 {
  46         /*
  47          *   Step 7: Check for unexpected packet types
  48          *      If (S.is_server and P.type == CloseReq)
  49          *        Send Sync packet acknowledging P.seqno
  50          *        Drop packet and return
  51          */
  52         if (dccp_sk(sk)->dccps_role != DCCP_ROLE_CLIENT) {
  53                 dccp_send_sync(sk, DCCP_SKB_CB(skb)->dccpd_seq, DCCP_PKT_SYNC);
  54                 return;
  55         }
  56
  57         switch (sk->sk_state) {
  58         case DCCP_PARTOPEN:
  59         case DCCP_OPEN:
  60                 dccp_set_state(sk, DCCP_CLOSING);
  61                 dccp_send_close(sk);
  62                 break;
  63         }
  64 }
  65
  66 static inline void dccp_event_ack_recv(struct sock *sk, struct sk_buff *skb)
  67 {
  68         struct dccp_sock *dp = dccp_sk(sk);
  69
  70         if (dp->dccps_options.dccpo_send_ack_vector)
  71                 dccp_ackpkts_check_rcv_ackno(dp->dccps_hc_rx_ackpkts, sk,
  72                                              DCCP_SKB_CB(skb)->dccpd_ack_seq);
  73 }
  74
  75 static int dccp_check_seqno(struct sock *sk, struct sk_buff *skb)
  76 {
  77         const struct dccp_hdr *dh = dccp_hdr(skb);
  78         struct dccp_sock *dp = dccp_sk(sk);
  79         u64 lswl, lawl;
  80
  81         /*
  82          *   Step 5: Prepare sequence numbers for Sync
  83          *     If P.type == Sync or P.type == SyncAck,
  84          *        If S.AWL <= P.ackno <= S.AWH and P.seqno >= S.SWL,
  85          *           / * P is valid, so update sequence number variables
  86          *               accordingly.  After this update, P will pass the tests
  87          *               in Step 6.  A SyncAck is generated if necessary in
  88          *               Step 15 * /
  89          *           Update S.GSR, S.SWL, S.SWH
  90          *        Otherwise,
  91          *           Drop packet and return
  92          */
  93         if (dh->dccph_type == DCCP_PKT_SYNC ||
  94             dh->dccph_type == DCCP_PKT_SYNCACK) {
  95                 if (between48(DCCP_SKB_CB(skb)->dccpd_ack_seq,
  96                               dp->dccps_awl, dp->dccps_awh) &&
  97                     !before48(DCCP_SKB_CB(skb)->dccpd_seq, dp->dccps_swl))
  98                         dccp_update_gsr(sk, DCCP_SKB_CB(skb)->dccpd_seq);
  99                 else
 100                         return -1;
 101         }
 102
 103         /*
 104          *   Step 6: Check sequence numbers
 105          *      Let LSWL = S.SWL and LAWL = S.AWL
 106          *      If P.type == CloseReq or P.type == Close or P.type == Reset,
 107          *        LSWL := S.GSR + 1, LAWL := S.GAR
 108          *      If LSWL <= P.seqno <= S.SWH
 109          *           and (P.ackno does not exist or LAWL <= P.ackno <= S.AWH),
 110          *        Update S.GSR, S.SWL, S.SWH
 111          *        If P.type != Sync,
 112          *           Update S.GAR
 113          *      Otherwise,
 114          *        Send Sync packet acknowledging P.seqno
 115          *        Drop packet and return
 116          */
 117         lswl = dp->dccps_swl;
 118         lawl = dp->dccps_awl;
 119
 120         if (dh->dccph_type == DCCP_PKT_CLOSEREQ ||
 121             dh->dccph_type == DCCP_PKT_CLOSE ||
 122             dh->dccph_type == DCCP_PKT_RESET) {
 123                 lswl = dp->dccps_gsr;
 124                 dccp_inc_seqno(&lswl);
 125                 lawl = dp->dccps_gar;
 126         }
 127
 128         if (between48(DCCP_SKB_CB(skb)->dccpd_seq, lswl, dp->dccps_swh) &&
 129             (DCCP_SKB_CB(skb)->dccpd_ack_seq == DCCP_PKT_WITHOUT_ACK_SEQ ||
 130              between48(DCCP_SKB_CB(skb)->dccpd_ack_seq,
 131                        lawl, dp->dccps_awh))) {
 132                 dccp_update_gsr(sk, DCCP_SKB_CB(skb)->dccpd_seq);
 133
 134                 if (dh->dccph_type != DCCP_PKT_SYNC &&
 135                     (DCCP_SKB_CB(skb)->dccpd_ack_seq !=
 136                      DCCP_PKT_WITHOUT_ACK_SEQ))
 137                         dp->dccps_gar = DCCP_SKB_CB(skb)->dccpd_ack_seq;
 138         } else {
 139                 LIMIT_NETDEBUG(KERN_WARNING "DCCP: Step 6 failed, "
 140                                             "sending SYNC...\n");
 141                 dccp_send_sync(sk, DCCP_SKB_CB(skb)->dccpd_seq, DCCP_PKT_SYNC);
 142                 return -1;
 143         }
 144
 145         return 0;
 146 }
 147
 148 int dccp_rcv_established(struct sock *sk, struct sk_buff *skb,
 149                          const struct dccp_hdr *dh, const unsigned len)
 150 {
 151         struct dccp_sock *dp = dccp_sk(sk);
 152
 153         if (dccp_check_seqno(sk, skb))
 154                 goto discard;
 155
 156         if (dccp_parse_options(sk, skb))
 157                 goto discard;
 158
 159         if (DCCP_SKB_CB(skb)->dccpd_ack_seq != DCCP_PKT_WITHOUT_ACK_SEQ)
 160                 dccp_event_ack_recv(sk, skb);
 161
 162         /*
 163          * FIXME: check ECN to see if we should use
 164          * DCCP_ACKPKTS_STATE_ECN_MARKED
 165          */
 166         if (dp->dccps_options.dccpo_send_ack_vector) {
 167                 struct dccp_ackpkts *ap = dp->dccps_hc_rx_ackpkts;
 168
 169                 if (dccp_ackpkts_add(dp->dccps_hc_rx_ackpkts,
 170                                      DCCP_SKB_CB(skb)->dccpd_seq,
 171                                      DCCP_ACKPKTS_STATE_RECEIVED)) {
 172                         LIMIT_NETDEBUG(KERN_WARNING "DCCP: acknowledgeable "
 173                                                     "packets buffer full!\n");
 174                         ap->dccpap_ack_seqno = DCCP_MAX_SEQNO + 1;
 175                         inet_csk_schedule_ack(sk);
 176                         inet_csk_reset_xmit_timer(sk, ICSK_TIME_DACK,
 177                                                   TCP_DELACK_MIN,
 178                                                   DCCP_RTO_MAX);
 179                         goto discard;
 180                 }
 181
 182                 /*
 183                  * FIXME: this activation is probably wrong, have to study more
 184                  * TCP delack machinery and how it fits into DCCP draft, but
 185                  * for now it kinda "works" 8)
 186                  */
 187                 if (!inet_csk_ack_scheduled(sk)) {
 188                         inet_csk_schedule_ack(sk);
 189                         inet_csk_reset_xmit_timer(sk, ICSK_TIME_DACK, 5 * HZ,
 190                                                   DCCP_RTO_MAX);
 191                 }
 192         }
 193
 194         ccid_hc_rx_packet_recv(dp->dccps_hc_rx_ccid, sk, skb);
 195         ccid_hc_tx_packet_recv(dp->dccps_hc_tx_ccid, sk, skb);
 196
 197         switch (dccp_hdr(skb)->dccph_type) {
 198         case DCCP_PKT_DATAACK:
 199         case DCCP_PKT_DATA:
 200                 /*
 201                  * FIXME: check if sk_receive_queue is full, schedule DATA_DROPPED
 202                  * option if it is.
 203                  */
 204                 __skb_pull(skb, dh->dccph_doff * 4);
 205                 __skb_queue_tail(&sk->sk_receive_queue, skb);
 206                 skb_set_owner_r(skb, sk);
 207                 sk->sk_data_ready(sk, 0);
 208                 return 0;
 209         case DCCP_PKT_ACK:
 210                 goto discard;
 211         case DCCP_PKT_RESET:
 212                 /*
 213                  *  Step 9: Process Reset
 214                  *      If P.type == Reset,
 215                  *              Tear down connection
 216                  *              S.state := TIMEWAIT
 217                  *              Set TIMEWAIT timer
 218                  *              Drop packet and return
 219                 */
 220                 dccp_fin(sk, skb);
 221                 dccp_time_wait(sk, DCCP_TIME_WAIT, 0);
 222                 return 0;
 223         case DCCP_PKT_CLOSEREQ:
 224                 dccp_rcv_closereq(sk, skb);
 225                 goto discard;
 226         case DCCP_PKT_CLOSE:
 227                 dccp_rcv_close(sk, skb);
 228                 return 0;
 229         case DCCP_PKT_REQUEST:
 230                 /* Step 7
 231                  *   or (S.is_server and P.type == Response)
 232                  *   or (S.is_client and P.type == Request)
 233                  *   or (S.state >= OPEN and P.type == Request
 234                  *      and P.seqno >= S.OSR)
 235                  *    or (S.state >= OPEN and P.type == Response
 236                  *      and P.seqno >= S.OSR)
 237                  *    or (S.state == RESPOND and P.type == Data),
 238                  *  Send Sync packet acknowledging P.seqno
 239                  *  Drop packet and return
 240                  */
 241                 if (dp->dccps_role != DCCP_ROLE_LISTEN)
 242                         goto send_sync;
 243                 goto check_seq;
 244         case DCCP_PKT_RESPONSE:
 245                 if (dp->dccps_role != DCCP_ROLE_CLIENT)
 246                         goto send_sync;
 247 check_seq:
 248                 if (!before48(DCCP_SKB_CB(skb)->dccpd_seq, dp->dccps_osr)) {
 249 send_sync:
 250                         dccp_send_sync(sk, DCCP_SKB_CB(skb)->dccpd_seq,
 251                                        DCCP_PKT_SYNC);
 252                 }
 253                 break;
 254         case DCCP_PKT_SYNC:
 255                 dccp_send_sync(sk, DCCP_SKB_CB(skb)->dccpd_seq,
 256                                DCCP_PKT_SYNCACK);
 257                 /*
 258                  * From the draft:
 259                  *
 260                  * As with DCCP-Ack packets, DCCP-Sync and DCCP-SyncAck packets
 261                  * MAY have non-zero-length application data areas, whose
 262                  * contents * receivers MUST ignore.
 263                  */
 264                 goto discard;
 265         }
 266
 267         DCCP_INC_STATS_BH(DCCP_MIB_INERRS);
 268 discard:
 269         __kfree_skb(skb);
 270         return 0;
 271 }
 272
 273 static int dccp_rcv_request_sent_state_process(struct sock *sk,
 274                                                struct sk_buff *skb,
 275                                                const struct dccp_hdr *dh,
 276                                                const unsigned len)
 277 {
 278         /*
 279          *  Step 4: Prepare sequence numbers in REQUEST
 280          *     If S.state == REQUEST,
 281          *        If (P.type == Response or P.type == Reset)
 282          *              and S.AWL <= P.ackno <= S.AWH,
 283          *           / * Set sequence number variables corresponding to the
 284          *              other endpoint, so P will pass the tests in Step 6 * /
 285          *           Set S.GSR, S.ISR, S.SWL, S.SWH
 286          *           / * Response processing continues in Step 10; Reset
 287          *              processing continues in Step 9 * /
 288         */
 289         if (dh->dccph_type == DCCP_PKT_RESPONSE) {
 290                 const struct inet_connection_sock *icsk = inet_csk(sk);
 291                 struct dccp_sock *dp = dccp_sk(sk);
 292
 293                 /* Stop the REQUEST timer */
 294                 inet_csk_clear_xmit_timer(sk, ICSK_TIME_RETRANS);
 295                 BUG_TRAP(sk->sk_send_head != NULL);
 296                 __kfree_skb(sk->sk_send_head);
 297                 sk->sk_send_head = NULL;
 298
 299                 if (!between48(DCCP_SKB_CB(skb)->dccpd_ack_seq,
 300                                dp->dccps_awl, dp->dccps_awh)) {
 301                         dccp_pr_debug("invalid ackno: S.AWL=%llu, "
 302                                       "P.ackno=%llu, S.AWH=%llu \n",
 303                                       (unsigned long long)dp->dccps_awl,
 304                            (unsigned long long)DCCP_SKB_CB(skb)->dccpd_ack_seq,
 305                                       (unsigned long long)dp->dccps_awh);
 306                         goto out_invalid_packet;
 307                 }
 308
 309                 dp->dccps_isr = DCCP_SKB_CB(skb)->dccpd_seq;
 310                 dccp_update_gsr(sk, DCCP_SKB_CB(skb)->dccpd_seq);
 311
 312                 if (ccid_hc_rx_init(dp->dccps_hc_rx_ccid, sk) != 0 ||
 313                     ccid_hc_tx_init(dp->dccps_hc_tx_ccid, sk) != 0) {
 314                         ccid_hc_rx_exit(dp->dccps_hc_rx_ccid, sk);
 315                         ccid_hc_tx_exit(dp->dccps_hc_tx_ccid, sk);
 316                         /* FIXME: send appropriate RESET code */
 317                         goto out_invalid_packet;
 318                 }
 319
 320                 dccp_sync_mss(sk, dp->dccps_pmtu_cookie);
 321
 322                 /*
 323                  *    Step 10: Process REQUEST state (second part)
 324                  *       If S.state == REQUEST,
 325                  *        / * If we get here, P is a valid Response from the
 326                  *            server (see Step 4), and we should move to
 327                  *            PARTOPEN state. PARTOPEN means send an Ack,
 328                  *            don't send Data packets, retransmit Acks
 329                  *            periodically, and always include any Init Cookie
 330                  *            from the Response * /
 331                  *        S.state := PARTOPEN
 332                  *        Set PARTOPEN timer
 333                  *        Continue with S.state == PARTOPEN
 334                  *        / * Step 12 will send the Ack completing the
 335                  *            three-way handshake * /
 336                  */
 337                 dccp_set_state(sk, DCCP_PARTOPEN);
 338
 339                 /* Make sure socket is routed, for correct metrics. */
 340                 inet_sk_rebuild_header(sk);
 341
 342                 if (!sock_flag(sk, SOCK_DEAD)) {
 343                         sk->sk_state_change(sk);
 344                         sk_wake_async(sk, 0, POLL_OUT);
 345                 }
 346
 347                 if (sk->sk_write_pending || icsk->icsk_ack.pingpong ||
 348                     icsk->icsk_accept_queue.rskq_defer_accept) {
 349                         /* Save one ACK. Data will be ready after
 350                          * several ticks, if write_pending is set.
 351                          *
 352                          * It may be deleted, but with this feature tcpdumps
 353                          * look so _wonderfully_ clever, that I was not able
 354                          * to stand against the temptation 8)     --ANK
 355                          */
 356                         /*
 357                          * OK, in DCCP we can as well do a similar trick, its
 358                          * even in the draft, but there is no need for us to
 359                          * schedule an ack here, as dccp_sendmsg does this for
 360                          * us, also stated in the draft. -acme
 361                          */
 362                         __kfree_skb(skb);
 363                         return 0;
 364                 }
 365                 dccp_send_ack(sk);
 366                 return -1;
 367         }
 368
 369 out_invalid_packet:
 370         return 1; /* dccp_v4_do_rcv will send a reset, but...
 371                      FIXME: the reset code should be
 372                             DCCP_RESET_CODE_PACKET_ERROR */
 373 }
 374
 375 static int dccp_rcv_respond_partopen_state_process(struct sock *sk,
 376                                                    struct sk_buff *skb,
 377                                                    const struct dccp_hdr *dh,
 378                                                    const unsigned len)
 379 {
 380         int queued = 0;
 381
 382         switch (dh->dccph_type) {
 383         case DCCP_PKT_RESET:
 384                 inet_csk_clear_xmit_timer(sk, ICSK_TIME_DACK);
 385                 break;
 386         case DCCP_PKT_DATAACK:
 387         case DCCP_PKT_ACK:
 388                 /*
 389                  * FIXME: we should be reseting the PARTOPEN (DELACK) timer
 390                  * here but only if we haven't used the DELACK timer for
 391                  * something else, like sending a delayed ack for a TIMESTAMP
 392                  * echo, etc, for now were not clearing it, sending an extra
 393                  * ACK when there is nothing else to do in DELACK is not a big
 394                  * deal after all.
 395                  */
 396
 397                 /* Stop the PARTOPEN timer */
 398                 if (sk->sk_state == DCCP_PARTOPEN)
 399                         inet_csk_clear_xmit_timer(sk, ICSK_TIME_DACK);
 400
 401                 dccp_sk(sk)->dccps_osr = DCCP_SKB_CB(skb)->dccpd_seq;
 402                 dccp_set_state(sk, DCCP_OPEN);
 403
 404                 if (dh->dccph_type == DCCP_PKT_DATAACK) {
 405                         dccp_rcv_established(sk, skb, dh, len);
 406                         queued = 1; /* packet was queued
 407                                        (by dccp_rcv_established) */
 408                 }
 409                 break;
 410         }
 411
 412         return queued;
 413 }
 414
 415 int dccp_rcv_state_process(struct sock *sk, struct sk_buff *skb,
 416                            struct dccp_hdr *dh, unsigned len)
 417 {
 418         struct dccp_sock *dp = dccp_sk(sk);
 419         const int old_state = sk->sk_state;
 420         int queued = 0;
 421
 422         /*
 423          *  Step 3: Process LISTEN state
 424          *      (Continuing from dccp_v4_do_rcv and dccp_v6_do_rcv)
 425          *
 426          *     If S.state == LISTEN,
 427          *        If P.type == Request or P contains a valid Init Cookie
 428          *              option,
 429          *           * Must scan the packet's options to check for an Init
 430          *              Cookie.  Only the Init Cookie is processed here,
 431          *              however; other options are processed in Step 8.  This
 432          *              scan need only be performed if the endpoint uses Init
 433          *              Cookies *
 434          *           * Generate a new socket and switch to that socket *
 435          *           Set S := new socket for this port pair
 436          *           S.state = RESPOND
 437          *           Choose S.ISS (initial seqno) or set from Init Cookie
 438          *           Set S.ISR, S.GSR, S.SWL, S.SWH from packet or Init Cookie
 439          *           Continue with S.state == RESPOND
 440          *           * A Response packet will be generated in Step 11 *
 441          *        Otherwise,
 442          *           Generate Reset(No Connection) unless P.type == Reset
 443          *           Drop packet and return
 444          *
 445          * NOTE: the check for the packet types is done in
 446          *       dccp_rcv_state_process
 447          */
 448         if (sk->sk_state == DCCP_LISTEN) {
 449                 if (dh->dccph_type == DCCP_PKT_REQUEST) {
 450                         if (dccp_v4_conn_request(sk, skb) < 0)
 451                                 return 1;
 452
 453                         /* FIXME: do congestion control initialization */
 454                         goto discard;
 455                 }
 456                 if (dh->dccph_type == DCCP_PKT_RESET)
 457                         goto discard;
 458
 459                 /* Caller (dccp_v4_do_rcv) will send Reset(No Connection)*/
 460                 return 1;
 461         }
 462
 463         if (sk->sk_state != DCCP_REQUESTING) {
 464                 if (dccp_check_seqno(sk, skb))
 465                         goto discard;
 466
 467                 /*
 468                  * Step 8: Process options and mark acknowledgeable
 469                  */
 470                 if (dccp_parse_options(sk, skb))
 471                         goto discard;
 472
 473                 if (DCCP_SKB_CB(skb)->dccpd_ack_seq !=
 474                     DCCP_PKT_WITHOUT_ACK_SEQ)
 475                         dccp_event_ack_recv(sk, skb);
 476
 477                 ccid_hc_rx_packet_recv(dp->dccps_hc_rx_ccid, sk, skb);
 478                 ccid_hc_tx_packet_recv(dp->dccps_hc_tx_ccid, sk, skb);
 479
 480                 /*
 481                  * FIXME: check ECN to see if we should use
 482                  * DCCP_ACKPKTS_STATE_ECN_MARKED
 483                  */
 484                 if (dp->dccps_options.dccpo_send_ack_vector) {
 485                         if (dccp_ackpkts_add(dp->dccps_hc_rx_ackpkts,
 486                                              DCCP_SKB_CB(skb)->dccpd_seq,
 487                                              DCCP_ACKPKTS_STATE_RECEIVED))
 488                                 goto discard;
 489                         /*
 490                          * FIXME: this activation is probably wrong, have to
 491                          * study more TCP delack machinery and how it fits into
 492                          * DCCP draft, but for now it kinda "works" 8)
 493                          */
 494                         if ((dp->dccps_hc_rx_ackpkts->dccpap_ack_seqno ==
 495                              DCCP_MAX_SEQNO + 1) &&
 496                             !inet_csk_ack_scheduled(sk)) {
 497                                 inet_csk_schedule_ack(sk);
 498                                 inet_csk_reset_xmit_timer(sk, ICSK_TIME_DACK,
 499                                                           TCP_DELACK_MIN,
 500                                                           DCCP_RTO_MAX);
 501                         }
 502                 }
 503         }
 504
 505         /*
 506          *  Step 9: Process Reset
 507          *      If P.type == Reset,
 508          *              Tear down connection
 509          *              S.state := TIMEWAIT
 510          *              Set TIMEWAIT timer
 511          *              Drop packet and return
 512         */
 513         if (dh->dccph_type == DCCP_PKT_RESET) {
 514                 /*
 515                  * Queue the equivalent of TCP fin so that dccp_recvmsg
 516                  * exits the loop
 517                  */
 518                 dccp_fin(sk, skb);
 519                 dccp_time_wait(sk, DCCP_TIME_WAIT, 0);
 520                 return 0;
 521                 /*
 522                  *   Step 7: Check for unexpected packet types
 523                  *      If (S.is_server and P.type == CloseReq)
 524                  *          or (S.is_server and P.type == Response)
 525                  *          or (S.is_client and P.type == Request)
 526                  *          or (S.state == RESPOND and P.type == Data),
 527                  *        Send Sync packet acknowledging P.seqno
 528                  *        Drop packet and return
 529                  */
 530         } else if ((dp->dccps_role != DCCP_ROLE_CLIENT &&
 531                     (dh->dccph_type == DCCP_PKT_RESPONSE ||
 532                      dh->dccph_type == DCCP_PKT_CLOSEREQ)) ||
 533                     (dp->dccps_role == DCCP_ROLE_CLIENT &&
 534                      dh->dccph_type == DCCP_PKT_REQUEST) ||
 535                     (sk->sk_state == DCCP_RESPOND &&
 536                      dh->dccph_type == DCCP_PKT_DATA)) {
 537                 dccp_send_sync(sk, DCCP_SKB_CB(skb)->dccpd_seq,
 538                                DCCP_PKT_SYNC);
 539                 goto discard;
 540         }
 541
 542         switch (sk->sk_state) {
 543         case DCCP_CLOSED:
 544                 return 1;
 545
 546         case DCCP_REQUESTING:
 547                 /* FIXME: do congestion control initialization */
 548
 549                 queued = dccp_rcv_request_sent_state_process(sk, skb, dh, len);
 550                 if (queued >= 0)
 551                         return queued;
 552
 553                 __kfree_skb(skb);
 554                 return 0;
 555
 556         case DCCP_RESPOND:
 557         case DCCP_PARTOPEN:
 558                 queued = dccp_rcv_respond_partopen_state_process(sk, skb,
 559                                                                  dh, len);
 560                 break;
 561         }
 562
 563         if (dh->dccph_type == DCCP_PKT_ACK ||
 564             dh->dccph_type == DCCP_PKT_DATAACK) {
 565                 switch (old_state) {
 566                 case DCCP_PARTOPEN:
 567                         sk->sk_state_change(sk);
 568                         sk_wake_async(sk, 0, POLL_OUT);
 569                         break;
 570                 }
 571         }
 572
 573         if (!queued) {
 574 discard:
 575                 __kfree_skb(skb);
 576         }
 577         return 0;
 578 }