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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/config.h>
  14 #include <linux/dccp.h>
  15 #include <linux/skbuff.h>
  16
  17 #include <net/sock.h>
  18
  19 #include "ackvec.h"
  20 #include "ccid.h"
  21 #include "dccp.h"
  22
  23 static void dccp_fin(struct sock *sk, struct sk_buff *skb)
  24 {
  25         sk->sk_shutdown |= RCV_SHUTDOWN;
  26         sock_set_flag(sk, SOCK_DONE);
  27         __skb_pull(skb, dccp_hdr(skb)->dccph_doff * 4);
  28         __skb_queue_tail(&sk->sk_receive_queue, skb);
  29         skb_set_owner_r(skb, sk);
  30         sk->sk_data_ready(sk, 0);
  31 }
  32
  33 static void dccp_rcv_close(struct sock *sk, struct sk_buff *skb)
  34 {
  35         dccp_v4_send_reset(sk, DCCP_RESET_CODE_CLOSED);
  36         dccp_fin(sk, skb);
  37         dccp_set_state(sk, DCCP_CLOSED);
  38         sk_wake_async(sk, 1, POLL_HUP);
  39 }
  40
  41 static void dccp_rcv_closereq(struct sock *sk, struct sk_buff *skb)
  42 {
  43         /*
  44          *   Step 7: Check for unexpected packet types
  45          *      If (S.is_server and P.type == CloseReq)
  46          *        Send Sync packet acknowledging P.seqno
  47          *        Drop packet and return
  48          */
  49         if (dccp_sk(sk)->dccps_role != DCCP_ROLE_CLIENT) {
  50                 dccp_send_sync(sk, DCCP_SKB_CB(skb)->dccpd_seq, DCCP_PKT_SYNC);
  51                 return;
  52         }
  53
  54         if (sk->sk_state != DCCP_CLOSING)
  55                 dccp_set_state(sk, DCCP_CLOSING);
  56         dccp_send_close(sk, 0);
  57 }
  58
  59 static inline void dccp_event_ack_recv(struct sock *sk, struct sk_buff *skb)
  60 {
  61         struct dccp_sock *dp = dccp_sk(sk);
  62
  63         if (dp->dccps_options.dccpo_send_ack_vector)
  64                 dccp_ackvec_check_rcv_ackno(dp->dccps_hc_rx_ackvec, sk,
  65                                             DCCP_SKB_CB(skb)->dccpd_ack_seq);
  66 }
  67
  68 static int dccp_check_seqno(struct sock *sk, struct sk_buff *skb)
  69 {
  70         const struct dccp_hdr *dh = dccp_hdr(skb);
  71         struct dccp_sock *dp = dccp_sk(sk);
  72         u64 lswl, lawl;
  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(DCCP_SKB_CB(skb)->dccpd_ack_seq,
  89                               dp->dccps_awl, dp->dccps_awh) &&
  90                     !before48(DCCP_SKB_CB(skb)->dccpd_seq, dp->dccps_swl))
  91                         dccp_update_gsr(sk, DCCP_SKB_CB(skb)->dccpd_seq);
  92                 else
  93                         return -1;
  94         }
  95
  96         /*
  97          *   Step 6: Check sequence numbers
  98          *      Let LSWL = S.SWL and LAWL = S.AWL
  99          *      If P.type == CloseReq or P.type == Close or P.type == Reset,
 100          *        LSWL := S.GSR + 1, LAWL := S.GAR
 101          *      If LSWL <= P.seqno <= S.SWH
 102          *           and (P.ackno does not exist or LAWL <= P.ackno <= S.AWH),
 103          *        Update S.GSR, S.SWL, S.SWH
 104          *        If P.type != Sync,
 105          *           Update S.GAR
 106          *      Otherwise,
 107          *        Send Sync packet acknowledging P.seqno
 108          *        Drop packet and return
 109          */
 110         lswl = dp->dccps_swl;
 111         lawl = dp->dccps_awl;
 112
 113         if (dh->dccph_type == DCCP_PKT_CLOSEREQ ||
 114             dh->dccph_type == DCCP_PKT_CLOSE ||
 115             dh->dccph_type == DCCP_PKT_RESET) {
 116                 lswl = dp->dccps_gsr;
 117                 dccp_inc_seqno(&lswl);
 118                 lawl = dp->dccps_gar;
 119         }
 120
 121         if (between48(DCCP_SKB_CB(skb)->dccpd_seq, lswl, dp->dccps_swh) &&
 122             (DCCP_SKB_CB(skb)->dccpd_ack_seq == DCCP_PKT_WITHOUT_ACK_SEQ ||
 123              between48(DCCP_SKB_CB(skb)->dccpd_ack_seq,
 124                        lawl, dp->dccps_awh))) {
 125                 dccp_update_gsr(sk, DCCP_SKB_CB(skb)->dccpd_seq);
 126
 127                 if (dh->dccph_type != DCCP_PKT_SYNC &&
 128                     (DCCP_SKB_CB(skb)->dccpd_ack_seq !=
 129                      DCCP_PKT_WITHOUT_ACK_SEQ))
 130                         dp->dccps_gar = DCCP_SKB_CB(skb)->dccpd_ack_seq;
 131         } else {
 132                 LIMIT_NETDEBUG(KERN_WARNING "DCCP: Step 6 failed for %s packet, "
 133                                             "(LSWL(%llu) <= P.seqno(%llu) <= S.SWH(%llu)) and "
 134                                             "(P.ackno %s or LAWL(%llu) <= P.ackno(%llu) <= S.AWH(%llu), "
 135                                             "sending SYNC...\n",
 136                                dccp_packet_name(dh->dccph_type),
 137                                (unsigned long long) lswl,
 138                                (unsigned long long)
 139                                DCCP_SKB_CB(skb)->dccpd_seq,
 140                                (unsigned long long) dp->dccps_swh,
 141                                (DCCP_SKB_CB(skb)->dccpd_ack_seq ==
 142                                 DCCP_PKT_WITHOUT_ACK_SEQ) ? "doesn't exist" : "exists",
 143                                (unsigned long long) lawl,
 144                                (unsigned long long)
 145                                DCCP_SKB_CB(skb)->dccpd_ack_seq,
 146                                (unsigned long long) dp->dccps_awh);
 147                 dccp_send_sync(sk, DCCP_SKB_CB(skb)->dccpd_seq, DCCP_PKT_SYNC);
 148                 return -1;
 149         }
 150
 151         return 0;
 152 }
 153
 154 int dccp_rcv_established(struct sock *sk, struct sk_buff *skb,
 155                          const struct dccp_hdr *dh, const unsigned len)
 156 {
 157         struct dccp_sock *dp = dccp_sk(sk);
 158
 159         if (dccp_check_seqno(sk, skb))
 160                 goto discard;
 161
 162         if (dccp_parse_options(sk, skb))
 163                 goto discard;
 164
 165         if (DCCP_SKB_CB(skb)->dccpd_ack_seq != DCCP_PKT_WITHOUT_ACK_SEQ)
 166                 dccp_event_ack_recv(sk, skb);
 167
 168         if (dp->dccps_options.dccpo_send_ack_vector &&
 169             dccp_ackvec_add(dp->dccps_hc_rx_ackvec, sk,
 170                             DCCP_SKB_CB(skb)->dccpd_seq,
 171                             DCCP_ACKVEC_STATE_RECEIVED))
 172                 goto discard;
 173
 174         ccid_hc_rx_packet_recv(dp->dccps_hc_rx_ccid, sk, skb);
 175         ccid_hc_tx_packet_recv(dp->dccps_hc_tx_ccid, sk, skb);
 176
 177         switch (dccp_hdr(skb)->dccph_type) {
 178         case DCCP_PKT_DATAACK:
 179         case DCCP_PKT_DATA:
 180                 /*
 181                  * FIXME: check if sk_receive_queue is full, schedule DATA_DROPPED
 182                  * option if it is.
 183                  */
 184                 __skb_pull(skb, dh->dccph_doff * 4);
 185                 __skb_queue_tail(&sk->sk_receive_queue, skb);
 186                 skb_set_owner_r(skb, sk);
 187                 sk->sk_data_ready(sk, 0);
 188                 return 0;
 189         case DCCP_PKT_ACK:
 190                 goto discard;
 191         case DCCP_PKT_RESET:
 192                 /*
 193                  *  Step 9: Process Reset
 194                  *      If P.type == Reset,
 195                  *              Tear down connection
 196                  *              S.state := TIMEWAIT
 197                  *              Set TIMEWAIT timer
 198                  *              Drop packet and return
 199                 */
 200                 dccp_fin(sk, skb);
 201                 dccp_time_wait(sk, DCCP_TIME_WAIT, 0);
 202                 return 0;
 203         case DCCP_PKT_CLOSEREQ:
 204                 dccp_rcv_closereq(sk, skb);
 205                 goto discard;
 206         case DCCP_PKT_CLOSE:
 207                 dccp_rcv_close(sk, skb);
 208                 return 0;
 209         case DCCP_PKT_REQUEST:
 210                 /* Step 7
 211                  *   or (S.is_server and P.type == Response)
 212                  *   or (S.is_client and P.type == Request)
 213                  *   or (S.state >= OPEN and P.type == Request
 214                  *      and P.seqno >= S.OSR)
 215                  *    or (S.state >= OPEN and P.type == Response
 216                  *      and P.seqno >= S.OSR)
 217                  *    or (S.state == RESPOND and P.type == Data),
 218                  *  Send Sync packet acknowledging P.seqno
 219                  *  Drop packet and return
 220                  */
 221                 if (dp->dccps_role != DCCP_ROLE_LISTEN)
 222                         goto send_sync;
 223                 goto check_seq;
 224         case DCCP_PKT_RESPONSE:
 225                 if (dp->dccps_role != DCCP_ROLE_CLIENT)
 226                         goto send_sync;
 227 check_seq:
 228                 if (!before48(DCCP_SKB_CB(skb)->dccpd_seq, dp->dccps_osr)) {
 229 send_sync:
 230                         dccp_send_sync(sk, DCCP_SKB_CB(skb)->dccpd_seq,
 231                                        DCCP_PKT_SYNC);
 232                 }
 233                 break;
 234         case DCCP_PKT_SYNC:
 235                 dccp_send_sync(sk, DCCP_SKB_CB(skb)->dccpd_seq,
 236                                DCCP_PKT_SYNCACK);
 237                 /*
 238                  * From the draft:
 239                  *
 240                  * As with DCCP-Ack packets, DCCP-Sync and DCCP-SyncAck packets
 241                  * MAY have non-zero-length application data areas, whose
 242                  * contents * receivers MUST ignore.
 243                  */
 244                 goto discard;
 245         }
 246
 247         DCCP_INC_STATS_BH(DCCP_MIB_INERRS);
 248 discard:
 249         __kfree_skb(skb);
 250         return 0;
 251 }
 252
 253 static int dccp_rcv_request_sent_state_process(struct sock *sk,
 254                                                struct sk_buff *skb,
 255                                                const struct dccp_hdr *dh,
 256                                                const unsigned len)
 257 {
 258         /*
 259          *  Step 4: Prepare sequence numbers in REQUEST
 260          *     If S.state == REQUEST,
 261          *        If (P.type == Response or P.type == Reset)
 262          *              and S.AWL <= P.ackno <= S.AWH,
 263          *           / * Set sequence number variables corresponding to the
 264          *              other endpoint, so P will pass the tests in Step 6 * /
 265          *           Set S.GSR, S.ISR, S.SWL, S.SWH
 266          *           / * Response processing continues in Step 10; Reset
 267          *              processing continues in Step 9 * /
 268         */
 269         if (dh->dccph_type == DCCP_PKT_RESPONSE) {
 270                 const struct inet_connection_sock *icsk = inet_csk(sk);
 271                 struct dccp_sock *dp = dccp_sk(sk);
 272
 273                 /* Stop the REQUEST timer */
 274                 inet_csk_clear_xmit_timer(sk, ICSK_TIME_RETRANS);
 275                 BUG_TRAP(sk->sk_send_head != NULL);
 276                 __kfree_skb(sk->sk_send_head);
 277                 sk->sk_send_head = NULL;
 278
 279                 if (!between48(DCCP_SKB_CB(skb)->dccpd_ack_seq,
 280                                dp->dccps_awl, dp->dccps_awh)) {
 281                         dccp_pr_debug("invalid ackno: S.AWL=%llu, "
 282                                       "P.ackno=%llu, S.AWH=%llu \n",
 283                                       (unsigned long long)dp->dccps_awl,
 284                            (unsigned long long)DCCP_SKB_CB(skb)->dccpd_ack_seq,
 285                                       (unsigned long long)dp->dccps_awh);
 286                         goto out_invalid_packet;
 287                 }
 288
 289                 dp->dccps_isr = DCCP_SKB_CB(skb)->dccpd_seq;
 290                 dccp_update_gsr(sk, dp->dccps_isr);
 291                 /*
 292                  * SWL and AWL are initially adjusted so that they are not less than
 293                  * the initial Sequence Numbers received and sent, respectively:
 294                  *      SWL := max(GSR + 1 - floor(W/4), ISR),
 295                  *      AWL := max(GSS - W' + 1, ISS).
 296                  * These adjustments MUST be applied only at the beginning of the
 297                  * connection.
 298                  *
 299                  * AWL was adjusted in dccp_v4_connect -acme
 300                  */
 301                 dccp_set_seqno(&dp->dccps_swl,
 302                                max48(dp->dccps_swl, dp->dccps_isr));
 303
 304                 if (ccid_hc_rx_init(dp->dccps_hc_rx_ccid, sk) != 0 ||
 305                     ccid_hc_tx_init(dp->dccps_hc_tx_ccid, sk) != 0) {
 306                         ccid_hc_rx_exit(dp->dccps_hc_rx_ccid, sk);
 307                         ccid_hc_tx_exit(dp->dccps_hc_tx_ccid, sk);
 308                         /* FIXME: send appropriate RESET code */
 309                         goto out_invalid_packet;
 310                 }
 311
 312                 dccp_sync_mss(sk, dp->dccps_pmtu_cookie);
 313
 314                 /*
 315                  *    Step 10: Process REQUEST state (second part)
 316                  *       If S.state == REQUEST,
 317                  *        / * If we get here, P is a valid Response from the
 318                  *            server (see Step 4), and we should move to
 319                  *            PARTOPEN state. PARTOPEN means send an Ack,
 320                  *            don't send Data packets, retransmit Acks
 321                  *            periodically, and always include any Init Cookie
 322                  *            from the Response * /
 323                  *        S.state := PARTOPEN
 324                  *        Set PARTOPEN timer
 325                  *        Continue with S.state == PARTOPEN
 326                  *        / * Step 12 will send the Ack completing the
 327                  *            three-way handshake * /
 328                  */
 329                 dccp_set_state(sk, DCCP_PARTOPEN);
 330
 331                 /* Make sure socket is routed, for correct metrics. */
 332                 inet_sk_rebuild_header(sk);
 333
 334                 if (!sock_flag(sk, SOCK_DEAD)) {
 335                         sk->sk_state_change(sk);
 336                         sk_wake_async(sk, 0, POLL_OUT);
 337                 }
 338
 339                 if (sk->sk_write_pending || icsk->icsk_ack.pingpong ||
 340                     icsk->icsk_accept_queue.rskq_defer_accept) {
 341                         /* Save one ACK. Data will be ready after
 342                          * several ticks, if write_pending is set.
 343                          *
 344                          * It may be deleted, but with this feature tcpdumps
 345                          * look so _wonderfully_ clever, that I was not able
 346                          * to stand against the temptation 8)     --ANK
 347                          */
 348                         /*
 349                          * OK, in DCCP we can as well do a similar trick, its
 350                          * even in the draft, but there is no need for us to
 351                          * schedule an ack here, as dccp_sendmsg does this for
 352                          * us, also stated in the draft. -acme
 353                          */
 354                         __kfree_skb(skb);
 355                         return 0;
 356                 }
 357                 dccp_send_ack(sk);
 358                 return -1;
 359         }
 360
 361 out_invalid_packet:
 362         /* dccp_v4_do_rcv will send a reset */
 363         DCCP_SKB_CB(skb)->dccpd_reset_code = DCCP_RESET_CODE_PACKET_ERROR;
 364         return 1;
 365 }
 366
 367 static int dccp_rcv_respond_partopen_state_process(struct sock *sk,
 368                                                    struct sk_buff *skb,
 369                                                    const struct dccp_hdr *dh,
 370                                                    const unsigned len)
 371 {
 372         int queued = 0;
 373
 374         switch (dh->dccph_type) {
 375         case DCCP_PKT_RESET:
 376                 inet_csk_clear_xmit_timer(sk, ICSK_TIME_DACK);
 377                 break;
 378         case DCCP_PKT_DATAACK:
 379         case DCCP_PKT_ACK:
 380                 /*
 381                  * FIXME: we should be reseting the PARTOPEN (DELACK) timer
 382                  * here but only if we haven't used the DELACK timer for
 383                  * something else, like sending a delayed ack for a TIMESTAMP
 384                  * echo, etc, for now were not clearing it, sending an extra
 385                  * ACK when there is nothing else to do in DELACK is not a big
 386                  * deal after all.
 387                  */
 388
 389                 /* Stop the PARTOPEN timer */
 390                 if (sk->sk_state == DCCP_PARTOPEN)
 391                         inet_csk_clear_xmit_timer(sk, ICSK_TIME_DACK);
 392
 393                 dccp_sk(sk)->dccps_osr = DCCP_SKB_CB(skb)->dccpd_seq;
 394                 dccp_set_state(sk, DCCP_OPEN);
 395
 396                 if (dh->dccph_type == DCCP_PKT_DATAACK) {
 397                         dccp_rcv_established(sk, skb, dh, len);
 398                         queued = 1; /* packet was queued
 399                                        (by dccp_rcv_established) */
 400                 }
 401                 break;
 402         }
 403
 404         return queued;
 405 }
 406
 407 int dccp_rcv_state_process(struct sock *sk, struct sk_buff *skb,
 408                            struct dccp_hdr *dh, unsigned len)
 409 {
 410         struct dccp_sock *dp = dccp_sk(sk);
 411         struct dccp_skb_cb *dcb = DCCP_SKB_CB(skb);
 412         const int old_state = sk->sk_state;
 413         int queued = 0;
 414
 415         /*
 416          *  Step 3: Process LISTEN state
 417          *      (Continuing from dccp_v4_do_rcv and dccp_v6_do_rcv)
 418          *
 419          *     If S.state == LISTEN,
 420          *        If P.type == Request or P contains a valid Init Cookie
 421          *              option,
 422          *           * Must scan the packet's options to check for an Init
 423          *              Cookie.  Only the Init Cookie is processed here,
 424          *              however; other options are processed in Step 8.  This
 425          *              scan need only be performed if the endpoint uses Init
 426          *              Cookies *
 427          *           * Generate a new socket and switch to that socket *
 428          *           Set S := new socket for this port pair
 429          *           S.state = RESPOND
 430          *           Choose S.ISS (initial seqno) or set from Init Cookie
 431          *           Set S.ISR, S.GSR, S.SWL, S.SWH from packet or Init Cookie
 432          *           Continue with S.state == RESPOND
 433          *           * A Response packet will be generated in Step 11 *
 434          *        Otherwise,
 435          *           Generate Reset(No Connection) unless P.type == Reset
 436          *           Drop packet and return
 437          *
 438          * NOTE: the check for the packet types is done in
 439          *       dccp_rcv_state_process
 440          */
 441         if (sk->sk_state == DCCP_LISTEN) {
 442                 if (dh->dccph_type == DCCP_PKT_REQUEST) {
 443                         if (dccp_v4_conn_request(sk, skb) < 0)
 444                                 return 1;
 445
 446                         /* FIXME: do congestion control initialization */
 447                         goto discard;
 448                 }
 449                 if (dh->dccph_type == DCCP_PKT_RESET)
 450                         goto discard;
 451
 452                 /* Caller (dccp_v4_do_rcv) will send Reset */
 453                 dcb->dccpd_reset_code = DCCP_RESET_CODE_NO_CONNECTION;
 454                 return 1;
 455         }
 456
 457         if (sk->sk_state != DCCP_REQUESTING) {
 458                 if (dccp_check_seqno(sk, skb))
 459                         goto discard;
 460
 461                 /*
 462                  * Step 8: Process options and mark acknowledgeable
 463                  */
 464                 if (dccp_parse_options(sk, skb))
 465                         goto discard;
 466
 467                 if (dcb->dccpd_ack_seq != DCCP_PKT_WITHOUT_ACK_SEQ)
 468                         dccp_event_ack_recv(sk, skb);
 469
 470                 ccid_hc_rx_packet_recv(dp->dccps_hc_rx_ccid, sk, skb);
 471                 ccid_hc_tx_packet_recv(dp->dccps_hc_tx_ccid, sk, skb);
 472
 473                 if (dp->dccps_options.dccpo_send_ack_vector &&
 474                     dccp_ackvec_add(dp->dccps_hc_rx_ackvec, sk,
 475                                     DCCP_SKB_CB(skb)->dccpd_seq,
 476                                     DCCP_ACKVEC_STATE_RECEIVED))
 477                         goto discard;
 478         }
 479
 480         /*
 481          *  Step 9: Process Reset
 482          *      If P.type == Reset,
 483          *              Tear down connection
 484          *              S.state := TIMEWAIT
 485          *              Set TIMEWAIT timer
 486          *              Drop packet and return
 487         */
 488         if (dh->dccph_type == DCCP_PKT_RESET) {
 489                 /*
 490                  * Queue the equivalent of TCP fin so that dccp_recvmsg
 491                  * exits the loop
 492                  */
 493                 dccp_fin(sk, skb);
 494                 dccp_time_wait(sk, DCCP_TIME_WAIT, 0);
 495                 return 0;
 496                 /*
 497                  *   Step 7: Check for unexpected packet types
 498                  *      If (S.is_server and P.type == CloseReq)
 499                  *          or (S.is_server and P.type == Response)
 500                  *          or (S.is_client and P.type == Request)
 501                  *          or (S.state == RESPOND and P.type == Data),
 502                  *        Send Sync packet acknowledging P.seqno
 503                  *        Drop packet and return
 504                  */
 505         } else if ((dp->dccps_role != DCCP_ROLE_CLIENT &&
 506                     (dh->dccph_type == DCCP_PKT_RESPONSE ||
 507                      dh->dccph_type == DCCP_PKT_CLOSEREQ)) ||
 508                     (dp->dccps_role == DCCP_ROLE_CLIENT &&
 509                      dh->dccph_type == DCCP_PKT_REQUEST) ||
 510                     (sk->sk_state == DCCP_RESPOND &&
 511                      dh->dccph_type == DCCP_PKT_DATA)) {
 512                 dccp_send_sync(sk, dcb->dccpd_seq, DCCP_PKT_SYNC);
 513                 goto discard;
 514         } else if (dh->dccph_type == DCCP_PKT_CLOSEREQ) {
 515                 dccp_rcv_closereq(sk, skb);
 516                 goto discard;
 517         } else if (dh->dccph_type == DCCP_PKT_CLOSE) {
 518                 dccp_rcv_close(sk, skb);
 519                 return 0;
 520         }
 521
 522         if (unlikely(dh->dccph_type == DCCP_PKT_SYNC)) {
 523                 dccp_send_sync(sk, dcb->dccpd_seq, DCCP_PKT_SYNCACK);
 524                 goto discard;
 525         }
 526
 527         switch (sk->sk_state) {
 528         case DCCP_CLOSED:
 529                 dcb->dccpd_reset_code = DCCP_RESET_CODE_NO_CONNECTION;
 530                 return 1;
 531
 532         case DCCP_REQUESTING:
 533                 /* FIXME: do congestion control initialization */
 534
 535                 queued = dccp_rcv_request_sent_state_process(sk, skb, dh, len);
 536                 if (queued >= 0)
 537                         return queued;
 538
 539                 __kfree_skb(skb);
 540                 return 0;
 541
 542         case DCCP_RESPOND:
 543         case DCCP_PARTOPEN:
 544                 queued = dccp_rcv_respond_partopen_state_process(sk, skb,
 545                                                                  dh, len);
 546                 break;
 547         }
 548
 549         if (dh->dccph_type == DCCP_PKT_ACK ||
 550             dh->dccph_type == DCCP_PKT_DATAACK) {
 551                 switch (old_state) {
 552                 case DCCP_PARTOPEN:
 553                         sk->sk_state_change(sk);
 554                         sk_wake_async(sk, 0, POLL_OUT);
 555                         break;
 556                 }
 557         }
 558
 559         if (!queued) {
 560 discard:
 561                 __kfree_skb(skb);
 562         }
 563         return 0;
 564 }