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 #include <linux/slab.h>
  16
  17 #include <net/sock.h>
  18
  19 #include "ackvec.h"
  20 #include "ccid.h"
  21 #include "dccp.h"
  22
  23 /* rate-limit for syncs in reply to sequence-invalid packets; RFC 4340, 7.5.4 */
  24 int sysctl_dccp_sync_ratelimit  __read_mostly = HZ / 8;
  25
  26 static void dccp_enqueue_skb(struct sock *sk, struct sk_buff *skb)
  27 {
  28         __skb_pull(skb, dccp_hdr(skb)->dccph_doff * 4);
  29         __skb_queue_tail(&sk->sk_receive_queue, skb);
  30         skb_set_owner_r(skb, sk);
  31         sk->sk_data_ready(sk, 0);
  32 }
  33
  34 static void dccp_fin(struct sock *sk, struct sk_buff *skb)
  35 {
  36         /*
  37          * On receiving Close/CloseReq, both RD/WR shutdown are performed.
  38          * RFC 4340, 8.3 says that we MAY send further Data/DataAcks after
  39          * receiving the closing segment, but there is no guarantee that such
  40          * data will be processed at all.
  41          */
  42         sk->sk_shutdown = SHUTDOWN_MASK;
  43         sock_set_flag(sk, SOCK_DONE);
  44         dccp_enqueue_skb(sk, skb);
  45 }
  46
  47 static int dccp_rcv_close(struct sock *sk, struct sk_buff *skb)
  48 {
  49         int queued = 0;
  50
  51         switch (sk->sk_state) {
  52         /*
  53          * We ignore Close when received in one of the following states:
  54          *  - CLOSED            (may be a late or duplicate packet)
  55          *  - PASSIVE_CLOSEREQ  (the peer has sent a CloseReq earlier)
  56          *  - RESPOND           (already handled by dccp_check_req)
  57          */
  58         case DCCP_CLOSING:
  59                 /*
  60                  * Simultaneous-close: receiving a Close after sending one. This
  61                  * can happen if both client and server perform active-close and
  62                  * will result in an endless ping-pong of crossing and retrans-
  63                  * mitted Close packets, which only terminates when one of the
  64                  * nodes times out (min. 64 seconds). Quicker convergence can be
  65                  * achieved when one of the nodes acts as tie-breaker.
  66                  * This is ok as both ends are done with data transfer and each
  67                  * end is just waiting for the other to acknowledge termination.
  68                  */
  69                 if (dccp_sk(sk)->dccps_role != DCCP_ROLE_CLIENT)
  70                         break;
  71                 /* fall through */
  72         case DCCP_REQUESTING:
  73         case DCCP_ACTIVE_CLOSEREQ:
  74                 dccp_send_reset(sk, DCCP_RESET_CODE_CLOSED);
  75                 dccp_done(sk);
  76                 break;
  77         case DCCP_OPEN:
  78         case DCCP_PARTOPEN:
  79                 /* Give waiting application a chance to read pending data */
  80                 queued = 1;
  81                 dccp_fin(sk, skb);
  82                 dccp_set_state(sk, DCCP_PASSIVE_CLOSE);
  83                 /* fall through */
  84         case DCCP_PASSIVE_CLOSE:
  85                 /*
  86                  * Retransmitted Close: we have already enqueued the first one.
  87                  */
  88                 sk_wake_async(sk, SOCK_WAKE_WAITD, POLL_HUP);
  89         }
  90         return queued;
  91 }
  92
  93 static int dccp_rcv_closereq(struct sock *sk, struct sk_buff *skb)
  94 {
  95         int queued = 0;
  96
  97         /*
  98          *   Step 7: Check for unexpected packet types
  99          *      If (S.is_server and P.type == CloseReq)
 100          *        Send Sync packet acknowledging P.seqno
 101          *        Drop packet and return
 102          */
 103         if (dccp_sk(sk)->dccps_role != DCCP_ROLE_CLIENT) {
 104                 dccp_send_sync(sk, DCCP_SKB_CB(skb)->dccpd_seq, DCCP_PKT_SYNC);
 105                 return queued;
 106         }
 107
 108         /* Step 13: process relevant Client states < CLOSEREQ */
 109         switch (sk->sk_state) {
 110         case DCCP_REQUESTING:
 111                 dccp_send_close(sk, 0);
 112                 dccp_set_state(sk, DCCP_CLOSING);
 113                 break;
 114         case DCCP_OPEN:
 115         case DCCP_PARTOPEN:
 116                 /* Give waiting application a chance to read pending data */
 117                 queued = 1;
 118                 dccp_fin(sk, skb);
 119                 dccp_set_state(sk, DCCP_PASSIVE_CLOSEREQ);
 120                 /* fall through */
 121         case DCCP_PASSIVE_CLOSEREQ:
 122                 sk_wake_async(sk, SOCK_WAKE_WAITD, POLL_HUP);
 123         }
 124         return queued;
 125 }
 126
 127 static u16 dccp_reset_code_convert(const u8 code)
 128 {
 129         const u16 error_code[] = {
 130         [DCCP_RESET_CODE_CLOSED]             = 0,       /* normal termination */
 131         [DCCP_RESET_CODE_UNSPECIFIED]        = 0,       /* nothing known */
 132         [DCCP_RESET_CODE_ABORTED]            = ECONNRESET,
 133
 134         [DCCP_RESET_CODE_NO_CONNECTION]      = ECONNREFUSED,
 135         [DCCP_RESET_CODE_CONNECTION_REFUSED] = ECONNREFUSED,
 136         [DCCP_RESET_CODE_TOO_BUSY]           = EUSERS,
 137         [DCCP_RESET_CODE_AGGRESSION_PENALTY] = EDQUOT,
 138
 139         [DCCP_RESET_CODE_PACKET_ERROR]       = ENOMSG,
 140         [DCCP_RESET_CODE_BAD_INIT_COOKIE]    = EBADR,
 141         [DCCP_RESET_CODE_BAD_SERVICE_CODE]   = EBADRQC,
 142         [DCCP_RESET_CODE_OPTION_ERROR]       = EILSEQ,
 143         [DCCP_RESET_CODE_MANDATORY_ERROR]    = EOPNOTSUPP,
 144         };
 145
 146         return code >= DCCP_MAX_RESET_CODES ? 0 : error_code[code];
 147 }
 148
 149 static void dccp_rcv_reset(struct sock *sk, struct sk_buff *skb)
 150 {
 151         u16 err = dccp_reset_code_convert(dccp_hdr_reset(skb)->dccph_reset_code);
 152
 153         sk->sk_err = err;
 154
 155         /* Queue the equivalent of TCP fin so that dccp_recvmsg exits the loop */
 156         dccp_fin(sk, skb);
 157
 158         if (err && !sock_flag(sk, SOCK_DEAD))
 159                 sk_wake_async(sk, SOCK_WAKE_IO, POLL_ERR);
 160         dccp_time_wait(sk, DCCP_TIME_WAIT, 0);
 161 }
 162
 163 static void dccp_event_ack_recv(struct sock *sk, struct sk_buff *skb)
 164 {
 165         struct dccp_sock *dp = dccp_sk(sk);
 166
 167         if (dp->dccps_hc_rx_ackvec != NULL)
 168                 dccp_ackvec_check_rcv_ackno(dp->dccps_hc_rx_ackvec, sk,
 169                                             DCCP_SKB_CB(skb)->dccpd_ack_seq);
 170 }
 171
 172 static void dccp_deliver_input_to_ccids(struct sock *sk, struct sk_buff *skb)
 173 {
 174         const struct dccp_sock *dp = dccp_sk(sk);
 175
 176         /* Don't deliver to RX CCID when node has shut down read end. */
 177         if (!(sk->sk_shutdown & RCV_SHUTDOWN))
 178                 ccid_hc_rx_packet_recv(dp->dccps_hc_rx_ccid, sk, skb);
 179         /*
 180          * Until the TX queue has been drained, we can not honour SHUT_WR, since
 181          * we need received feedback as input to adjust congestion control.
 182          */
 183         if (sk->sk_write_queue.qlen > 0 || !(sk->sk_shutdown & SEND_SHUTDOWN))
 184                 ccid_hc_tx_packet_recv(dp->dccps_hc_tx_ccid, sk, skb);
 185 }
 186
 187 static int dccp_check_seqno(struct sock *sk, struct sk_buff *skb)
 188 {
 189         const struct dccp_hdr *dh = dccp_hdr(skb);
 190         struct dccp_sock *dp = dccp_sk(sk);
 191         u64 lswl, lawl, seqno = DCCP_SKB_CB(skb)->dccpd_seq,
 192                         ackno = DCCP_SKB_CB(skb)->dccpd_ack_seq;
 193
 194         /*
 195          *   Step 5: Prepare sequence numbers for Sync
 196          *     If P.type == Sync or P.type == SyncAck,
 197          *        If S.AWL <= P.ackno <= S.AWH and P.seqno >= S.SWL,
 198          *           / * P is valid, so update sequence number variables
 199          *               accordingly.  After this update, P will pass the tests
 200          *               in Step 6.  A SyncAck is generated if necessary in
 201          *               Step 15 * /
 202          *           Update S.GSR, S.SWL, S.SWH
 203          *        Otherwise,
 204          *           Drop packet and return
 205          */
 206         if (dh->dccph_type == DCCP_PKT_SYNC ||
 207             dh->dccph_type == DCCP_PKT_SYNCACK) {
 208                 if (between48(ackno, dp->dccps_awl, dp->dccps_awh) &&
 209                     dccp_delta_seqno(dp->dccps_swl, seqno) >= 0)
 210                         dccp_update_gsr(sk, seqno);
 211                 else
 212                         return -1;
 213         }
 214
 215         /*
 216          *   Step 6: Check sequence numbers
 217          *      Let LSWL = S.SWL and LAWL = S.AWL
 218          *      If P.type == CloseReq or P.type == Close or P.type == Reset,
 219          *        LSWL := S.GSR + 1, LAWL := S.GAR
 220          *      If LSWL <= P.seqno <= S.SWH
 221          *           and (P.ackno does not exist or LAWL <= P.ackno <= S.AWH),
 222          *        Update S.GSR, S.SWL, S.SWH
 223          *        If P.type != Sync,
 224          *           Update S.GAR
 225          */
 226         lswl = dp->dccps_swl;
 227         lawl = dp->dccps_awl;
 228
 229         if (dh->dccph_type == DCCP_PKT_CLOSEREQ ||
 230             dh->dccph_type == DCCP_PKT_CLOSE ||
 231             dh->dccph_type == DCCP_PKT_RESET) {
 232                 lswl = ADD48(dp->dccps_gsr, 1);
 233                 lawl = dp->dccps_gar;
 234         }
 235
 236         if (between48(seqno, lswl, dp->dccps_swh) &&
 237             (ackno == DCCP_PKT_WITHOUT_ACK_SEQ ||
 238              between48(ackno, lawl, dp->dccps_awh))) {
 239                 dccp_update_gsr(sk, seqno);
 240
 241                 if (dh->dccph_type != DCCP_PKT_SYNC &&
 242                     ackno != DCCP_PKT_WITHOUT_ACK_SEQ &&
 243                     after48(ackno, dp->dccps_gar))
 244                         dp->dccps_gar = ackno;
 245         } else {
 246                 unsigned long now = jiffies;
 247                 /*
 248                  *   Step 6: Check sequence numbers
 249                  *      Otherwise,
 250                  *         If P.type == Reset,
 251                  *            Send Sync packet acknowledging S.GSR
 252                  *         Otherwise,
 253                  *            Send Sync packet acknowledging P.seqno
 254                  *      Drop packet and return
 255                  *
 256                  *   These Syncs are rate-limited as per RFC 4340, 7.5.4:
 257                  *   at most 1 / (dccp_sync_rate_limit * HZ) Syncs per second.
 258                  */
 259                 if (time_before(now, (dp->dccps_rate_last +
 260                                       sysctl_dccp_sync_ratelimit)))
 261                         return 0;
 262
 263                 DCCP_WARN("Step 6 failed for %s packet, "
 264                           "(LSWL(%llu) <= P.seqno(%llu) <= S.SWH(%llu)) and "
 265                           "(P.ackno %s or LAWL(%llu) <= P.ackno(%llu) <= S.AWH(%llu), "
 266                           "sending SYNC...\n",  dccp_packet_name(dh->dccph_type),
 267                           (unsigned long long) lswl, (unsigned long long) seqno,
 268                           (unsigned long long) dp->dccps_swh,
 269                           (ackno == DCCP_PKT_WITHOUT_ACK_SEQ) ? "doesn't exist"
 270                                                               : "exists",
 271                           (unsigned long long) lawl, (unsigned long long) ackno,
 272                           (unsigned long long) dp->dccps_awh);
 273
 274                 dp->dccps_rate_last = now;
 275
 276                 if (dh->dccph_type == DCCP_PKT_RESET)
 277                         seqno = dp->dccps_gsr;
 278                 dccp_send_sync(sk, seqno, DCCP_PKT_SYNC);
 279                 return -1;
 280         }
 281
 282         return 0;
 283 }
 284
 285 static int __dccp_rcv_established(struct sock *sk, struct sk_buff *skb,
 286                                   const struct dccp_hdr *dh, const unsigned len)
 287 {
 288         struct dccp_sock *dp = dccp_sk(sk);
 289
 290         switch (dccp_hdr(skb)->dccph_type) {
 291         case DCCP_PKT_DATAACK:
 292         case DCCP_PKT_DATA:
 293                 /*
 294                  * FIXME: schedule DATA_DROPPED (RFC 4340, 11.7.2) if and when
 295                  * - sk_shutdown == RCV_SHUTDOWN, use Code 1, "Not Listening"
 296                  * - sk_receive_queue is full, use Code 2, "Receive Buffer"
 297                  */
 298                 dccp_enqueue_skb(sk, skb);
 299                 return 0;
 300         case DCCP_PKT_ACK:
 301                 goto discard;
 302         case DCCP_PKT_RESET:
 303                 /*
 304                  *  Step 9: Process Reset
 305                  *      If P.type == Reset,
 306                  *              Tear down connection
 307                  *              S.state := TIMEWAIT
 308                  *              Set TIMEWAIT timer
 309                  *              Drop packet and return
 310                  */
 311                 dccp_rcv_reset(sk, skb);
 312                 return 0;
 313         case DCCP_PKT_CLOSEREQ:
 314                 if (dccp_rcv_closereq(sk, skb))
 315                         return 0;
 316                 goto discard;
 317         case DCCP_PKT_CLOSE:
 318                 if (dccp_rcv_close(sk, skb))
 319                         return 0;
 320                 goto discard;
 321         case DCCP_PKT_REQUEST:
 322                 /* Step 7
 323                  *   or (S.is_server and P.type == Response)
 324                  *   or (S.is_client and P.type == Request)
 325                  *   or (S.state >= OPEN and P.type == Request
 326                  *      and P.seqno >= S.OSR)
 327                  *    or (S.state >= OPEN and P.type == Response
 328                  *      and P.seqno >= S.OSR)
 329                  *    or (S.state == RESPOND and P.type == Data),
 330                  *  Send Sync packet acknowledging P.seqno
 331                  *  Drop packet and return
 332                  */
 333                 if (dp->dccps_role != DCCP_ROLE_LISTEN)
 334                         goto send_sync;
 335                 goto check_seq;
 336         case DCCP_PKT_RESPONSE:
 337                 if (dp->dccps_role != DCCP_ROLE_CLIENT)
 338                         goto send_sync;
 339 check_seq:
 340                 if (dccp_delta_seqno(dp->dccps_osr,
 341                                      DCCP_SKB_CB(skb)->dccpd_seq) >= 0) {
 342 send_sync:
 343                         dccp_send_sync(sk, DCCP_SKB_CB(skb)->dccpd_seq,
 344                                        DCCP_PKT_SYNC);
 345                 }
 346                 break;
 347         case DCCP_PKT_SYNC:
 348                 dccp_send_sync(sk, DCCP_SKB_CB(skb)->dccpd_seq,
 349                                DCCP_PKT_SYNCACK);
 350                 /*
 351                  * From RFC 4340, sec. 5.7
 352                  *
 353                  * As with DCCP-Ack packets, DCCP-Sync and DCCP-SyncAck packets
 354                  * MAY have non-zero-length application data areas, whose
 355                  * contents receivers MUST ignore.
 356                  */
 357                 goto discard;
 358         }
 359
 360         DCCP_INC_STATS_BH(DCCP_MIB_INERRS);
 361 discard:
 362         __kfree_skb(skb);
 363         return 0;
 364 }
 365
 366 int dccp_rcv_established(struct sock *sk, struct sk_buff *skb,
 367                          const struct dccp_hdr *dh, const unsigned len)
 368 {
 369         struct dccp_sock *dp = dccp_sk(sk);
 370
 371         if (dccp_check_seqno(sk, skb))
 372                 goto discard;
 373
 374         if (dccp_parse_options(sk, NULL, skb))
 375                 return 1;
 376
 377         if (DCCP_SKB_CB(skb)->dccpd_ack_seq != DCCP_PKT_WITHOUT_ACK_SEQ)
 378                 dccp_event_ack_recv(sk, skb);
 379
 380         if (dp->dccps_hc_rx_ackvec != NULL &&
 381             dccp_ackvec_add(dp->dccps_hc_rx_ackvec, sk,
 382                             DCCP_SKB_CB(skb)->dccpd_seq,
 383                             DCCP_ACKVEC_STATE_RECEIVED))
 384                 goto discard;
 385         dccp_deliver_input_to_ccids(sk, skb);
 386
 387         return __dccp_rcv_established(sk, skb, dh, len);
 388 discard:
 389         __kfree_skb(skb);
 390         return 0;
 391 }
 392
 393 EXPORT_SYMBOL_GPL(dccp_rcv_established);
 394
 395 static int dccp_rcv_request_sent_state_process(struct sock *sk,
 396                                                struct sk_buff *skb,
 397                                                const struct dccp_hdr *dh,
 398                                                const unsigned len)
 399 {
 400         /*
 401          *  Step 4: Prepare sequence numbers in REQUEST
 402          *     If S.state == REQUEST,
 403          *        If (P.type == Response or P.type == Reset)
 404          *              and S.AWL <= P.ackno <= S.AWH,
 405          *           / * Set sequence number variables corresponding to the
 406          *              other endpoint, so P will pass the tests in Step 6 * /
 407          *           Set S.GSR, S.ISR, S.SWL, S.SWH
 408          *           / * Response processing continues in Step 10; Reset
 409          *              processing continues in Step 9 * /
 410         */
 411         if (dh->dccph_type == DCCP_PKT_RESPONSE) {
 412                 const struct inet_connection_sock *icsk = inet_csk(sk);
 413                 struct dccp_sock *dp = dccp_sk(sk);
 414                 long tstamp = dccp_timestamp();
 415
 416                 if (!between48(DCCP_SKB_CB(skb)->dccpd_ack_seq,
 417                                dp->dccps_awl, dp->dccps_awh)) {
 418                         dccp_pr_debug("invalid ackno: S.AWL=%llu, "
 419                                       "P.ackno=%llu, S.AWH=%llu\n",
 420                                       (unsigned long long)dp->dccps_awl,
 421                            (unsigned long long)DCCP_SKB_CB(skb)->dccpd_ack_seq,
 422                                       (unsigned long long)dp->dccps_awh);
 423                         goto out_invalid_packet;
 424                 }
 425
 426                 /*
 427                  * If option processing (Step 8) failed, return 1 here so that
 428                  * dccp_v4_do_rcv() sends a Reset. The Reset code depends on
 429                  * the option type and is set in dccp_parse_options().
 430                  */
 431                 if (dccp_parse_options(sk, NULL, skb))
 432                         return 1;
 433
 434                 /* Obtain usec RTT sample from SYN exchange (used by TFRC). */
 435                 if (likely(dp->dccps_options_received.dccpor_timestamp_echo))
 436                         dp->dccps_syn_rtt = dccp_sample_rtt(sk, 10 * (tstamp -
 437                             dp->dccps_options_received.dccpor_timestamp_echo));
 438
 439                 /* Stop the REQUEST timer */
 440                 inet_csk_clear_xmit_timer(sk, ICSK_TIME_RETRANS);
 441                 WARN_ON(sk->sk_send_head == NULL);
 442                 kfree_skb(sk->sk_send_head);
 443                 sk->sk_send_head = NULL;
 444
 445                 /*
 446                  * Set ISR, GSR from packet. ISS was set in dccp_v{4,6}_connect
 447                  * and GSS in dccp_transmit_skb(). Setting AWL/AWH and SWL/SWH
 448                  * is done as part of activating the feature values below, since
 449                  * these settings depend on the local/remote Sequence Window
 450                  * features, which were undefined or not confirmed until now.
 451                  */
 452                 dp->dccps_gsr = dp->dccps_isr = DCCP_SKB_CB(skb)->dccpd_seq;
 453
 454                 dccp_sync_mss(sk, icsk->icsk_pmtu_cookie);
 455
 456                 /*
 457                  *    Step 10: Process REQUEST state (second part)
 458                  *       If S.state == REQUEST,
 459                  *        / * If we get here, P is a valid Response from the
 460                  *            server (see Step 4), and we should move to
 461                  *            PARTOPEN state. PARTOPEN means send an Ack,
 462                  *            don't send Data packets, retransmit Acks
 463                  *            periodically, and always include any Init Cookie
 464                  *            from the Response * /
 465                  *        S.state := PARTOPEN
 466                  *        Set PARTOPEN timer
 467                  *        Continue with S.state == PARTOPEN
 468                  *        / * Step 12 will send the Ack completing the
 469                  *            three-way handshake * /
 470                  */
 471                 dccp_set_state(sk, DCCP_PARTOPEN);
 472
 473                 /*
 474                  * If feature negotiation was successful, activate features now;
 475                  * an activation failure means that this host could not activate
 476                  * one ore more features (e.g. insufficient memory), which would
 477                  * leave at least one feature in an undefined state.
 478                  */
 479                 if (dccp_feat_activate_values(sk, &dp->dccps_featneg))
 480                         goto unable_to_proceed;
 481
 482                 /* Make sure socket is routed, for correct metrics. */
 483                 icsk->icsk_af_ops->rebuild_header(sk);
 484
 485                 if (!sock_flag(sk, SOCK_DEAD)) {
 486                         sk->sk_state_change(sk);
 487                         sk_wake_async(sk, SOCK_WAKE_IO, POLL_OUT);
 488                 }
 489
 490                 if (sk->sk_write_pending || icsk->icsk_ack.pingpong ||
 491                     icsk->icsk_accept_queue.rskq_defer_accept) {
 492                         /* Save one ACK. Data will be ready after
 493                          * several ticks, if write_pending is set.
 494                          *
 495                          * It may be deleted, but with this feature tcpdumps
 496                          * look so _wonderfully_ clever, that I was not able
 497                          * to stand against the temptation 8)     --ANK
 498                          */
 499                         /*
 500                          * OK, in DCCP we can as well do a similar trick, its
 501                          * even in the draft, but there is no need for us to
 502                          * schedule an ack here, as dccp_sendmsg does this for
 503                          * us, also stated in the draft. -acme
 504                          */
 505                         __kfree_skb(skb);
 506                         return 0;
 507                 }
 508                 dccp_send_ack(sk);
 509                 return -1;
 510         }
 511
 512 out_invalid_packet:
 513         /* dccp_v4_do_rcv will send a reset */
 514         DCCP_SKB_CB(skb)->dccpd_reset_code = DCCP_RESET_CODE_PACKET_ERROR;
 515         return 1;
 516
 517 unable_to_proceed:
 518         DCCP_SKB_CB(skb)->dccpd_reset_code = DCCP_RESET_CODE_ABORTED;
 519         /*
 520          * We mark this socket as no longer usable, so that the loop in
 521          * dccp_sendmsg() terminates and the application gets notified.
 522          */
 523         dccp_set_state(sk, DCCP_CLOSED);
 524         sk->sk_err = ECOMM;
 525         return 1;
 526 }
 527
 528 static int dccp_rcv_respond_partopen_state_process(struct sock *sk,
 529                                                    struct sk_buff *skb,
 530                                                    const struct dccp_hdr *dh,
 531                                                    const unsigned len)
 532 {
 533         struct dccp_sock *dp = dccp_sk(sk);
 534         u32 sample = dp->dccps_options_received.dccpor_timestamp_echo;
 535         int queued = 0;
 536
 537         switch (dh->dccph_type) {
 538         case DCCP_PKT_RESET:
 539                 inet_csk_clear_xmit_timer(sk, ICSK_TIME_DACK);
 540                 break;
 541         case DCCP_PKT_DATA:
 542                 if (sk->sk_state == DCCP_RESPOND)
 543                         break;
 544         case DCCP_PKT_DATAACK:
 545         case DCCP_PKT_ACK:
 546                 /*
 547                  * FIXME: we should be reseting the PARTOPEN (DELACK) timer
 548                  * here but only if we haven't used the DELACK timer for
 549                  * something else, like sending a delayed ack for a TIMESTAMP
 550                  * echo, etc, for now were not clearing it, sending an extra
 551                  * ACK when there is nothing else to do in DELACK is not a big
 552                  * deal after all.
 553                  */
 554
 555                 /* Stop the PARTOPEN timer */
 556                 if (sk->sk_state == DCCP_PARTOPEN)
 557                         inet_csk_clear_xmit_timer(sk, ICSK_TIME_DACK);
 558
 559                 /* Obtain usec RTT sample from SYN exchange (used by TFRC). */
 560                 if (likely(sample)) {
 561                         long delta = dccp_timestamp() - sample;
 562
 563                         dp->dccps_syn_rtt = dccp_sample_rtt(sk, 10 * delta);
 564                 }
 565
 566                 dp->dccps_osr = DCCP_SKB_CB(skb)->dccpd_seq;
 567                 dccp_set_state(sk, DCCP_OPEN);
 568
 569                 if (dh->dccph_type == DCCP_PKT_DATAACK ||
 570                     dh->dccph_type == DCCP_PKT_DATA) {
 571                         __dccp_rcv_established(sk, skb, dh, len);
 572                         queued = 1; /* packet was queued
 573                                        (by __dccp_rcv_established) */
 574                 }
 575                 break;
 576         }
 577
 578         return queued;
 579 }
 580
 581 int dccp_rcv_state_process(struct sock *sk, struct sk_buff *skb,
 582                            struct dccp_hdr *dh, unsigned len)
 583 {
 584         struct dccp_sock *dp = dccp_sk(sk);
 585         struct dccp_skb_cb *dcb = DCCP_SKB_CB(skb);
 586         const int old_state = sk->sk_state;
 587         int queued = 0;
 588
 589         /*
 590          *  Step 3: Process LISTEN state
 591          *
 592          *     If S.state == LISTEN,
 593          *       If P.type == Request or P contains a valid Init Cookie option,
 594          *            (* Must scan the packet's options to check for Init
 595          *               Cookies.  Only Init Cookies are processed here,
 596          *               however; other options are processed in Step 8.  This
 597          *               scan need only be performed if the endpoint uses Init
 598          *               Cookies *)
 599          *            (* Generate a new socket and switch to that socket *)
 600          *            Set S := new socket for this port pair
 601          *            S.state = RESPOND
 602          *            Choose S.ISS (initial seqno) or set from Init Cookies
 603          *            Initialize S.GAR := S.ISS
 604          *            Set S.ISR, S.GSR, S.SWL, S.SWH from packet or Init
 605          *            Cookies Continue with S.state == RESPOND
 606          *            (* A Response packet will be generated in Step 11 *)
 607          *       Otherwise,
 608          *            Generate Reset(No Connection) unless P.type == Reset
 609          *            Drop packet and return
 610          */
 611         if (sk->sk_state == DCCP_LISTEN) {
 612                 if (dh->dccph_type == DCCP_PKT_REQUEST) {
 613                         if (inet_csk(sk)->icsk_af_ops->conn_request(sk,
 614                                                                     skb) < 0)
 615                                 return 1;
 616                         goto discard;
 617                 }
 618                 if (dh->dccph_type == DCCP_PKT_RESET)
 619                         goto discard;
 620
 621                 /* Caller (dccp_v4_do_rcv) will send Reset */
 622                 dcb->dccpd_reset_code = DCCP_RESET_CODE_NO_CONNECTION;
 623                 return 1;
 624         }
 625
 626         if (sk->sk_state != DCCP_REQUESTING && sk->sk_state != DCCP_RESPOND) {
 627                 if (dccp_check_seqno(sk, skb))
 628                         goto discard;
 629
 630                 /*
 631                  * Step 8: Process options and mark acknowledgeable
 632                  */
 633                 if (dccp_parse_options(sk, NULL, skb))
 634                         return 1;
 635
 636                 if (dcb->dccpd_ack_seq != DCCP_PKT_WITHOUT_ACK_SEQ)
 637                         dccp_event_ack_recv(sk, skb);
 638
 639                 if (dp->dccps_hc_rx_ackvec != NULL &&
 640                     dccp_ackvec_add(dp->dccps_hc_rx_ackvec, sk,
 641                                     DCCP_SKB_CB(skb)->dccpd_seq,
 642                                     DCCP_ACKVEC_STATE_RECEIVED))
 643                         goto discard;
 644
 645                 dccp_deliver_input_to_ccids(sk, skb);
 646         }
 647
 648         /*
 649          *  Step 9: Process Reset
 650          *      If P.type == Reset,
 651          *              Tear down connection
 652          *              S.state := TIMEWAIT
 653          *              Set TIMEWAIT timer
 654          *              Drop packet and return
 655         */
 656         if (dh->dccph_type == DCCP_PKT_RESET) {
 657                 dccp_rcv_reset(sk, skb);
 658                 return 0;
 659                 /*
 660                  *   Step 7: Check for unexpected packet types
 661                  *      If (S.is_server and P.type == Response)
 662                  *          or (S.is_client and P.type == Request)
 663                  *          or (S.state == RESPOND and P.type == Data),
 664                  *        Send Sync packet acknowledging P.seqno
 665                  *        Drop packet and return
 666                  */
 667         } else if ((dp->dccps_role != DCCP_ROLE_CLIENT &&
 668                     dh->dccph_type == DCCP_PKT_RESPONSE) ||
 669                     (dp->dccps_role == DCCP_ROLE_CLIENT &&
 670                      dh->dccph_type == DCCP_PKT_REQUEST) ||
 671                     (sk->sk_state == DCCP_RESPOND &&
 672                      dh->dccph_type == DCCP_PKT_DATA)) {
 673                 dccp_send_sync(sk, dcb->dccpd_seq, DCCP_PKT_SYNC);
 674                 goto discard;
 675         } else if (dh->dccph_type == DCCP_PKT_CLOSEREQ) {
 676                 if (dccp_rcv_closereq(sk, skb))
 677                         return 0;
 678                 goto discard;
 679         } else if (dh->dccph_type == DCCP_PKT_CLOSE) {
 680                 if (dccp_rcv_close(sk, skb))
 681                         return 0;
 682                 goto discard;
 683         }
 684
 685         switch (sk->sk_state) {
 686         case DCCP_CLOSED:
 687                 dcb->dccpd_reset_code = DCCP_RESET_CODE_NO_CONNECTION;
 688                 return 1;
 689
 690         case DCCP_REQUESTING:
 691                 queued = dccp_rcv_request_sent_state_process(sk, skb, dh, len);
 692                 if (queued >= 0)
 693                         return queued;
 694
 695                 __kfree_skb(skb);
 696                 return 0;
 697
 698         case DCCP_RESPOND:
 699         case DCCP_PARTOPEN:
 700                 queued = dccp_rcv_respond_partopen_state_process(sk, skb,
 701                                                                  dh, len);
 702                 break;
 703         }
 704
 705         if (dh->dccph_type == DCCP_PKT_ACK ||
 706             dh->dccph_type == DCCP_PKT_DATAACK) {
 707                 switch (old_state) {
 708                 case DCCP_PARTOPEN:
 709                         sk->sk_state_change(sk);
 710                         sk_wake_async(sk, SOCK_WAKE_IO, POLL_OUT);
 711                         break;
 712                 }
 713         } else if (unlikely(dh->dccph_type == DCCP_PKT_SYNC)) {
 714                 dccp_send_sync(sk, dcb->dccpd_seq, DCCP_PKT_SYNCACK);
 715                 goto discard;
 716         }
 717
 718         if (!queued) {
 719 discard:
 720                 __kfree_skb(skb);
 721         }
 722         return 0;
 723 }
 724
 725 EXPORT_SYMBOL_GPL(dccp_rcv_state_process);
 726
 727 /**
 728  *  dccp_sample_rtt  -  Validate and finalise computation of RTT sample
 729  *  @delta:     number of microseconds between packet and acknowledgment
 730  *  The routine is kept generic to work in different contexts. It should be
 731  *  called immediately when the ACK used for the RTT sample arrives.
 732  */
 733 u32 dccp_sample_rtt(struct sock *sk, long delta)
 734 {
 735         /* dccpor_elapsed_time is either zeroed out or set and > 0 */
 736         delta -= dccp_sk(sk)->dccps_options_received.dccpor_elapsed_time * 10;
 737
 738         if (unlikely(delta <= 0)) {
 739                 DCCP_WARN("unusable RTT sample %ld, using min\n", delta);
 740                 return DCCP_SANE_RTT_MIN;
 741         }
 742         if (unlikely(delta > DCCP_SANE_RTT_MAX)) {
 743                 DCCP_WARN("RTT sample %ld too large, using max\n", delta);
 744                 return DCCP_SANE_RTT_MAX;
 745         }
 746
 747         return delta;
 748 }