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 /* rate-limit for syncs in reply to sequence-invalid packets; RFC 4340, 7.5.4 */
  23 int sysctl_dccp_sync_ratelimit  __read_mostly = HZ / 8;
  24
  25 static void dccp_fin(struct sock *sk, struct sk_buff *skb)
  26 {
  27         sk->sk_shutdown |= RCV_SHUTDOWN;
  28         sock_set_flag(sk, SOCK_DONE);
  29         __skb_pull(skb, dccp_hdr(skb)->dccph_doff * 4);
  30         __skb_queue_tail(&sk->sk_receive_queue, skb);
  31         skb_set_owner_r(skb, sk);
  32         sk->sk_data_ready(sk, 0);
  33 }
  34
  35 static void dccp_rcv_close(struct sock *sk, struct sk_buff *skb)
  36 {
  37         dccp_send_reset(sk, DCCP_RESET_CODE_CLOSED);
  38         dccp_fin(sk, skb);
  39         dccp_set_state(sk, DCCP_CLOSED);
  40         sk_wake_async(sk, 1, POLL_HUP);
  41 }
  42
  43 static void dccp_rcv_closereq(struct sock *sk, struct sk_buff *skb)
  44 {
  45         /*
  46          *   Step 7: Check for unexpected packet types
  47          *      If (S.is_server and P.type == CloseReq)
  48          *        Send Sync packet acknowledging P.seqno
  49          *        Drop packet and return
  50          */
  51         if (dccp_sk(sk)->dccps_role != DCCP_ROLE_CLIENT) {
  52                 dccp_send_sync(sk, DCCP_SKB_CB(skb)->dccpd_seq, DCCP_PKT_SYNC);
  53                 return;
  54         }
  55
  56         if (sk->sk_state != DCCP_CLOSING)
  57                 dccp_set_state(sk, DCCP_CLOSING);
  58         dccp_send_close(sk, 0);
  59 }
  60
  61 static u8 dccp_reset_code_convert(const u8 code)
  62 {
  63         const u8 error_code[] = {
  64         [DCCP_RESET_CODE_CLOSED]             = 0,       /* normal termination */
  65         [DCCP_RESET_CODE_UNSPECIFIED]        = 0,       /* nothing known */
  66         [DCCP_RESET_CODE_ABORTED]            = ECONNRESET,
  67
  68         [DCCP_RESET_CODE_NO_CONNECTION]      = ECONNREFUSED,
  69         [DCCP_RESET_CODE_CONNECTION_REFUSED] = ECONNREFUSED,
  70         [DCCP_RESET_CODE_TOO_BUSY]           = EUSERS,
  71         [DCCP_RESET_CODE_AGGRESSION_PENALTY] = EDQUOT,
  72
  73         [DCCP_RESET_CODE_PACKET_ERROR]       = ENOMSG,
  74         [DCCP_RESET_CODE_BAD_INIT_COOKIE]    = EBADR,
  75         [DCCP_RESET_CODE_BAD_SERVICE_CODE]   = EBADRQC,
  76         [DCCP_RESET_CODE_OPTION_ERROR]       = EILSEQ,
  77         [DCCP_RESET_CODE_MANDATORY_ERROR]    = EOPNOTSUPP,
  78         };
  79
  80         return code >= DCCP_MAX_RESET_CODES ? 0 : error_code[code];
  81 }
  82
  83 static void dccp_rcv_reset(struct sock *sk, struct sk_buff *skb)
  84 {
  85         u8 err = dccp_reset_code_convert(dccp_hdr_reset(skb)->dccph_reset_code);
  86
  87         sk->sk_err = err;
  88
  89         /* Queue the equivalent of TCP fin so that dccp_recvmsg exits the loop */
  90         dccp_fin(sk, skb);
  91
  92         if (err && !sock_flag(sk, SOCK_DEAD))
  93                 sk_wake_async(sk, 0, POLL_ERR);
  94         dccp_time_wait(sk, DCCP_TIME_WAIT, 0);
  95 }
  96
  97 static void dccp_event_ack_recv(struct sock *sk, struct sk_buff *skb)
  98 {
  99         struct dccp_sock *dp = dccp_sk(sk);
 100
 101         if (dccp_msk(sk)->dccpms_send_ack_vector)
 102                 dccp_ackvec_check_rcv_ackno(dp->dccps_hc_rx_ackvec, sk,
 103                                             DCCP_SKB_CB(skb)->dccpd_ack_seq);
 104 }
 105
 106 static void dccp_deliver_input_to_ccids(struct sock *sk, struct sk_buff *skb)
 107 {
 108         const struct dccp_sock *dp = dccp_sk(sk);
 109
 110         /* Don't deliver to RX CCID when node has shut down read end. */
 111         if (!(sk->sk_shutdown & RCV_SHUTDOWN))
 112                 ccid_hc_rx_packet_recv(dp->dccps_hc_rx_ccid, sk, skb);
 113         /*
 114          * Until the TX queue has been drained, we can not honour SHUT_WR, since
 115          * we need received feedback as input to adjust congestion control.
 116          */
 117         if (sk->sk_write_queue.qlen > 0 || !(sk->sk_shutdown & SEND_SHUTDOWN))
 118                 ccid_hc_tx_packet_recv(dp->dccps_hc_tx_ccid, sk, skb);
 119 }
 120
 121 static int dccp_check_seqno(struct sock *sk, struct sk_buff *skb)
 122 {
 123         const struct dccp_hdr *dh = dccp_hdr(skb);
 124         struct dccp_sock *dp = dccp_sk(sk);
 125         u64 lswl, lawl, seqno = DCCP_SKB_CB(skb)->dccpd_seq,
 126                         ackno = DCCP_SKB_CB(skb)->dccpd_ack_seq;
 127
 128         /*
 129          *   Step 5: Prepare sequence numbers for Sync
 130          *     If P.type == Sync or P.type == SyncAck,
 131          *        If S.AWL <= P.ackno <= S.AWH and P.seqno >= S.SWL,
 132          *           / * P is valid, so update sequence number variables
 133          *               accordingly.  After this update, P will pass the tests
 134          *               in Step 6.  A SyncAck is generated if necessary in
 135          *               Step 15 * /
 136          *           Update S.GSR, S.SWL, S.SWH
 137          *        Otherwise,
 138          *           Drop packet and return
 139          */
 140         if (dh->dccph_type == DCCP_PKT_SYNC ||
 141             dh->dccph_type == DCCP_PKT_SYNCACK) {
 142                 if (between48(ackno, dp->dccps_awl, dp->dccps_awh) &&
 143                     dccp_delta_seqno(dp->dccps_swl, seqno) >= 0)
 144                         dccp_update_gsr(sk, seqno);
 145                 else
 146                         return -1;
 147         }
 148
 149         /*
 150          *   Step 6: Check sequence numbers
 151          *      Let LSWL = S.SWL and LAWL = S.AWL
 152          *      If P.type == CloseReq or P.type == Close or P.type == Reset,
 153          *        LSWL := S.GSR + 1, LAWL := S.GAR
 154          *      If LSWL <= P.seqno <= S.SWH
 155          *           and (P.ackno does not exist or LAWL <= P.ackno <= S.AWH),
 156          *        Update S.GSR, S.SWL, S.SWH
 157          *        If P.type != Sync,
 158          *           Update S.GAR
 159          */
 160         lswl = dp->dccps_swl;
 161         lawl = dp->dccps_awl;
 162
 163         if (dh->dccph_type == DCCP_PKT_CLOSEREQ ||
 164             dh->dccph_type == DCCP_PKT_CLOSE ||
 165             dh->dccph_type == DCCP_PKT_RESET) {
 166                 lswl = ADD48(dp->dccps_gsr, 1);
 167                 lawl = dp->dccps_gar;
 168         }
 169
 170         if (between48(seqno, lswl, dp->dccps_swh) &&
 171             (ackno == DCCP_PKT_WITHOUT_ACK_SEQ ||
 172              between48(ackno, lawl, dp->dccps_awh))) {
 173                 dccp_update_gsr(sk, seqno);
 174
 175                 if (dh->dccph_type != DCCP_PKT_SYNC &&
 176                     (ackno != DCCP_PKT_WITHOUT_ACK_SEQ))
 177                         dp->dccps_gar = ackno;
 178         } else {
 179                 unsigned long now = jiffies;
 180                 /*
 181                  *   Step 6: Check sequence numbers
 182                  *      Otherwise,
 183                  *         If P.type == Reset,
 184                  *            Send Sync packet acknowledging S.GSR
 185                  *         Otherwise,
 186                  *            Send Sync packet acknowledging P.seqno
 187                  *      Drop packet and return
 188                  *
 189                  *   These Syncs are rate-limited as per RFC 4340, 7.5.4:
 190                  *   at most 1 / (dccp_sync_rate_limit * HZ) Syncs per second.
 191                  */
 192                 if (time_before(now, (dp->dccps_rate_last +
 193                                       sysctl_dccp_sync_ratelimit)))
 194                         return 0;
 195
 196                 DCCP_WARN("DCCP: Step 6 failed for %s packet, "
 197                           "(LSWL(%llu) <= P.seqno(%llu) <= S.SWH(%llu)) and "
 198                           "(P.ackno %s or LAWL(%llu) <= P.ackno(%llu) <= S.AWH(%llu), "
 199                           "sending SYNC...\n",  dccp_packet_name(dh->dccph_type),
 200                           (unsigned long long) lswl, (unsigned long long) seqno,
 201                           (unsigned long long) dp->dccps_swh,
 202                           (ackno == DCCP_PKT_WITHOUT_ACK_SEQ) ? "doesn't exist"
 203                                                               : "exists",
 204                           (unsigned long long) lawl, (unsigned long long) ackno,
 205                           (unsigned long long) dp->dccps_awh);
 206
 207                 dp->dccps_rate_last = now;
 208
 209                 if (dh->dccph_type == DCCP_PKT_RESET)
 210                         seqno = dp->dccps_gsr;
 211                 dccp_send_sync(sk, seqno, DCCP_PKT_SYNC);
 212                 return -1;
 213         }
 214
 215         return 0;
 216 }
 217
 218 static int __dccp_rcv_established(struct sock *sk, struct sk_buff *skb,
 219                                   const struct dccp_hdr *dh, const unsigned len)
 220 {
 221         struct dccp_sock *dp = dccp_sk(sk);
 222
 223         switch (dccp_hdr(skb)->dccph_type) {
 224         case DCCP_PKT_DATAACK:
 225         case DCCP_PKT_DATA:
 226                 /*
 227                  * FIXME: schedule DATA_DROPPED (RFC 4340, 11.7.2) if and when
 228                  * - sk_shutdown == RCV_SHUTDOWN, use Code 1, "Not Listening"
 229                  * - sk_receive_queue is full, use Code 2, "Receive Buffer"
 230                  */
 231                 __skb_pull(skb, dh->dccph_doff * 4);
 232                 __skb_queue_tail(&sk->sk_receive_queue, skb);
 233                 skb_set_owner_r(skb, sk);
 234                 sk->sk_data_ready(sk, 0);
 235                 return 0;
 236         case DCCP_PKT_ACK:
 237                 goto discard;
 238         case DCCP_PKT_RESET:
 239                 /*
 240                  *  Step 9: Process Reset
 241                  *      If P.type == Reset,
 242                  *              Tear down connection
 243                  *              S.state := TIMEWAIT
 244                  *              Set TIMEWAIT timer
 245                  *              Drop packet and return
 246                  */
 247                 dccp_rcv_reset(sk, skb);
 248                 return 0;
 249         case DCCP_PKT_CLOSEREQ:
 250                 dccp_rcv_closereq(sk, skb);
 251                 goto discard;
 252         case DCCP_PKT_CLOSE:
 253                 dccp_rcv_close(sk, skb);
 254                 return 0;
 255         case DCCP_PKT_REQUEST:
 256                 /* Step 7
 257                  *   or (S.is_server and P.type == Response)
 258                  *   or (S.is_client and P.type == Request)
 259                  *   or (S.state >= OPEN and P.type == Request
 260                  *      and P.seqno >= S.OSR)
 261                  *    or (S.state >= OPEN and P.type == Response
 262                  *      and P.seqno >= S.OSR)
 263                  *    or (S.state == RESPOND and P.type == Data),
 264                  *  Send Sync packet acknowledging P.seqno
 265                  *  Drop packet and return
 266                  */
 267                 if (dp->dccps_role != DCCP_ROLE_LISTEN)
 268                         goto send_sync;
 269                 goto check_seq;
 270         case DCCP_PKT_RESPONSE:
 271                 if (dp->dccps_role != DCCP_ROLE_CLIENT)
 272                         goto send_sync;
 273 check_seq:
 274                 if (dccp_delta_seqno(dp->dccps_osr,
 275                                      DCCP_SKB_CB(skb)->dccpd_seq) >= 0) {
 276 send_sync:
 277                         dccp_send_sync(sk, DCCP_SKB_CB(skb)->dccpd_seq,
 278                                        DCCP_PKT_SYNC);
 279                 }
 280                 break;
 281         case DCCP_PKT_SYNC:
 282                 dccp_send_sync(sk, DCCP_SKB_CB(skb)->dccpd_seq,
 283                                DCCP_PKT_SYNCACK);
 284                 /*
 285                  * From RFC 4340, sec. 5.7
 286                  *
 287                  * As with DCCP-Ack packets, DCCP-Sync and DCCP-SyncAck packets
 288                  * MAY have non-zero-length application data areas, whose
 289                  * contents receivers MUST ignore.
 290                  */
 291                 goto discard;
 292         }
 293
 294         DCCP_INC_STATS_BH(DCCP_MIB_INERRS);
 295 discard:
 296         __kfree_skb(skb);
 297         return 0;
 298 }
 299
 300 int dccp_rcv_established(struct sock *sk, struct sk_buff *skb,
 301                          const struct dccp_hdr *dh, const unsigned len)
 302 {
 303         struct dccp_sock *dp = dccp_sk(sk);
 304
 305         if (dccp_check_seqno(sk, skb))
 306                 goto discard;
 307
 308         if (dccp_parse_options(sk, skb))
 309                 goto discard;
 310
 311         if (DCCP_SKB_CB(skb)->dccpd_ack_seq != DCCP_PKT_WITHOUT_ACK_SEQ)
 312                 dccp_event_ack_recv(sk, skb);
 313
 314         if (dccp_msk(sk)->dccpms_send_ack_vector &&
 315             dccp_ackvec_add(dp->dccps_hc_rx_ackvec, sk,
 316                             DCCP_SKB_CB(skb)->dccpd_seq,
 317                             DCCP_ACKVEC_STATE_RECEIVED))
 318                 goto discard;
 319         dccp_deliver_input_to_ccids(sk, skb);
 320
 321         return __dccp_rcv_established(sk, skb, dh, len);
 322 discard:
 323         __kfree_skb(skb);
 324         return 0;
 325 }
 326
 327 EXPORT_SYMBOL_GPL(dccp_rcv_established);
 328
 329 static int dccp_rcv_request_sent_state_process(struct sock *sk,
 330                                                struct sk_buff *skb,
 331                                                const struct dccp_hdr *dh,
 332                                                const unsigned len)
 333 {
 334         /*
 335          *  Step 4: Prepare sequence numbers in REQUEST
 336          *     If S.state == REQUEST,
 337          *        If (P.type == Response or P.type == Reset)
 338          *              and S.AWL <= P.ackno <= S.AWH,
 339          *           / * Set sequence number variables corresponding to the
 340          *              other endpoint, so P will pass the tests in Step 6 * /
 341          *           Set S.GSR, S.ISR, S.SWL, S.SWH
 342          *           / * Response processing continues in Step 10; Reset
 343          *              processing continues in Step 9 * /
 344         */
 345         if (dh->dccph_type == DCCP_PKT_RESPONSE) {
 346                 const struct inet_connection_sock *icsk = inet_csk(sk);
 347                 struct dccp_sock *dp = dccp_sk(sk);
 348                 long tstamp = dccp_timestamp();
 349
 350                 /* Stop the REQUEST timer */
 351                 inet_csk_clear_xmit_timer(sk, ICSK_TIME_RETRANS);
 352                 BUG_TRAP(sk->sk_send_head != NULL);
 353                 __kfree_skb(sk->sk_send_head);
 354                 sk->sk_send_head = NULL;
 355
 356                 if (!between48(DCCP_SKB_CB(skb)->dccpd_ack_seq,
 357                                dp->dccps_awl, dp->dccps_awh)) {
 358                         dccp_pr_debug("invalid ackno: S.AWL=%llu, "
 359                                       "P.ackno=%llu, S.AWH=%llu \n",
 360                                       (unsigned long long)dp->dccps_awl,
 361                            (unsigned long long)DCCP_SKB_CB(skb)->dccpd_ack_seq,
 362                                       (unsigned long long)dp->dccps_awh);
 363                         goto out_invalid_packet;
 364                 }
 365
 366                 if (dccp_parse_options(sk, skb))
 367                         goto out_invalid_packet;
 368
 369                 /* Obtain usec RTT sample from SYN exchange (used by CCID 3) */
 370                 if (likely(dp->dccps_options_received.dccpor_timestamp_echo))
 371                         dp->dccps_syn_rtt = dccp_sample_rtt(sk, 10 * (tstamp -
 372                             dp->dccps_options_received.dccpor_timestamp_echo));
 373
 374                 if (dccp_msk(sk)->dccpms_send_ack_vector &&
 375                     dccp_ackvec_add(dp->dccps_hc_rx_ackvec, sk,
 376                                     DCCP_SKB_CB(skb)->dccpd_seq,
 377                                     DCCP_ACKVEC_STATE_RECEIVED))
 378                         goto out_invalid_packet; /* FIXME: change error code */
 379
 380                 dp->dccps_isr = DCCP_SKB_CB(skb)->dccpd_seq;
 381                 dccp_update_gsr(sk, dp->dccps_isr);
 382                 /*
 383                  * SWL and AWL are initially adjusted so that they are not less than
 384                  * the initial Sequence Numbers received and sent, respectively:
 385                  *      SWL := max(GSR + 1 - floor(W/4), ISR),
 386                  *      AWL := max(GSS - W' + 1, ISS).
 387                  * These adjustments MUST be applied only at the beginning of the
 388                  * connection.
 389                  *
 390                  * AWL was adjusted in dccp_v4_connect -acme
 391                  */
 392                 dccp_set_seqno(&dp->dccps_swl,
 393                                max48(dp->dccps_swl, dp->dccps_isr));
 394
 395                 dccp_sync_mss(sk, icsk->icsk_pmtu_cookie);
 396
 397                 /*
 398                  *    Step 10: Process REQUEST state (second part)
 399                  *       If S.state == REQUEST,
 400                  *        / * If we get here, P is a valid Response from the
 401                  *            server (see Step 4), and we should move to
 402                  *            PARTOPEN state. PARTOPEN means send an Ack,
 403                  *            don't send Data packets, retransmit Acks
 404                  *            periodically, and always include any Init Cookie
 405                  *            from the Response * /
 406                  *        S.state := PARTOPEN
 407                  *        Set PARTOPEN timer
 408                  *        Continue with S.state == PARTOPEN
 409                  *        / * Step 12 will send the Ack completing the
 410                  *            three-way handshake * /
 411                  */
 412                 dccp_set_state(sk, DCCP_PARTOPEN);
 413
 414                 /* Make sure socket is routed, for correct metrics. */
 415                 icsk->icsk_af_ops->rebuild_header(sk);
 416
 417                 if (!sock_flag(sk, SOCK_DEAD)) {
 418                         sk->sk_state_change(sk);
 419                         sk_wake_async(sk, 0, POLL_OUT);
 420                 }
 421
 422                 if (sk->sk_write_pending || icsk->icsk_ack.pingpong ||
 423                     icsk->icsk_accept_queue.rskq_defer_accept) {
 424                         /* Save one ACK. Data will be ready after
 425                          * several ticks, if write_pending is set.
 426                          *
 427                          * It may be deleted, but with this feature tcpdumps
 428                          * look so _wonderfully_ clever, that I was not able
 429                          * to stand against the temptation 8)     --ANK
 430                          */
 431                         /*
 432                          * OK, in DCCP we can as well do a similar trick, its
 433                          * even in the draft, but there is no need for us to
 434                          * schedule an ack here, as dccp_sendmsg does this for
 435                          * us, also stated in the draft. -acme
 436                          */
 437                         __kfree_skb(skb);
 438                         return 0;
 439                 }
 440                 dccp_send_ack(sk);
 441                 return -1;
 442         }
 443
 444 out_invalid_packet:
 445         /* dccp_v4_do_rcv will send a reset */
 446         DCCP_SKB_CB(skb)->dccpd_reset_code = DCCP_RESET_CODE_PACKET_ERROR;
 447         return 1;
 448 }
 449
 450 static int dccp_rcv_respond_partopen_state_process(struct sock *sk,
 451                                                    struct sk_buff *skb,
 452                                                    const struct dccp_hdr *dh,
 453                                                    const unsigned len)
 454 {
 455         int queued = 0;
 456
 457         switch (dh->dccph_type) {
 458         case DCCP_PKT_RESET:
 459                 inet_csk_clear_xmit_timer(sk, ICSK_TIME_DACK);
 460                 break;
 461         case DCCP_PKT_DATA:
 462                 if (sk->sk_state == DCCP_RESPOND)
 463                         break;
 464         case DCCP_PKT_DATAACK:
 465         case DCCP_PKT_ACK:
 466                 /*
 467                  * FIXME: we should be reseting the PARTOPEN (DELACK) timer
 468                  * here but only if we haven't used the DELACK timer for
 469                  * something else, like sending a delayed ack for a TIMESTAMP
 470                  * echo, etc, for now were not clearing it, sending an extra
 471                  * ACK when there is nothing else to do in DELACK is not a big
 472                  * deal after all.
 473                  */
 474
 475                 /* Stop the PARTOPEN timer */
 476                 if (sk->sk_state == DCCP_PARTOPEN)
 477                         inet_csk_clear_xmit_timer(sk, ICSK_TIME_DACK);
 478
 479                 dccp_sk(sk)->dccps_osr = DCCP_SKB_CB(skb)->dccpd_seq;
 480                 dccp_set_state(sk, DCCP_OPEN);
 481
 482                 if (dh->dccph_type == DCCP_PKT_DATAACK ||
 483                     dh->dccph_type == DCCP_PKT_DATA) {
 484                         __dccp_rcv_established(sk, skb, dh, len);
 485                         queued = 1; /* packet was queued
 486                                        (by __dccp_rcv_established) */
 487                 }
 488                 break;
 489         }
 490
 491         return queued;
 492 }
 493
 494 int dccp_rcv_state_process(struct sock *sk, struct sk_buff *skb,
 495                            struct dccp_hdr *dh, unsigned len)
 496 {
 497         struct dccp_sock *dp = dccp_sk(sk);
 498         struct dccp_skb_cb *dcb = DCCP_SKB_CB(skb);
 499         const int old_state = sk->sk_state;
 500         int queued = 0;
 501
 502         /*
 503          *  Step 3: Process LISTEN state
 504          *
 505          *     If S.state == LISTEN,
 506          *       If P.type == Request or P contains a valid Init Cookie option,
 507          *            (* Must scan the packet's options to check for Init
 508          *               Cookies.  Only Init Cookies are processed here,
 509          *               however; other options are processed in Step 8.  This
 510          *               scan need only be performed if the endpoint uses Init
 511          *               Cookies *)
 512          *            (* Generate a new socket and switch to that socket *)
 513          *            Set S := new socket for this port pair
 514          *            S.state = RESPOND
 515          *            Choose S.ISS (initial seqno) or set from Init Cookies
 516          *            Initialize S.GAR := S.ISS
 517          *            Set S.ISR, S.GSR, S.SWL, S.SWH from packet or Init
 518          *            Cookies Continue with S.state == RESPOND
 519          *            (* A Response packet will be generated in Step 11 *)
 520          *       Otherwise,
 521          *            Generate Reset(No Connection) unless P.type == Reset
 522          *            Drop packet and return
 523          */
 524         if (sk->sk_state == DCCP_LISTEN) {
 525                 if (dh->dccph_type == DCCP_PKT_REQUEST) {
 526                         if (inet_csk(sk)->icsk_af_ops->conn_request(sk,
 527                                                                     skb) < 0)
 528                                 return 1;
 529
 530                         /* FIXME: do congestion control initialization */
 531                         goto discard;
 532                 }
 533                 if (dh->dccph_type == DCCP_PKT_RESET)
 534                         goto discard;
 535
 536                 /* Caller (dccp_v4_do_rcv) will send Reset */
 537                 dcb->dccpd_reset_code = DCCP_RESET_CODE_NO_CONNECTION;
 538                 return 1;
 539         }
 540
 541         if (sk->sk_state != DCCP_REQUESTING) {
 542                 if (dccp_check_seqno(sk, skb))
 543                         goto discard;
 544
 545                 /*
 546                  * Step 8: Process options and mark acknowledgeable
 547                  */
 548                 if (dccp_parse_options(sk, skb))
 549                         goto discard;
 550
 551                 if (dcb->dccpd_ack_seq != DCCP_PKT_WITHOUT_ACK_SEQ)
 552                         dccp_event_ack_recv(sk, skb);
 553
 554                 if (dccp_msk(sk)->dccpms_send_ack_vector &&
 555                     dccp_ackvec_add(dp->dccps_hc_rx_ackvec, sk,
 556                                     DCCP_SKB_CB(skb)->dccpd_seq,
 557                                     DCCP_ACKVEC_STATE_RECEIVED))
 558                         goto discard;
 559
 560                 dccp_deliver_input_to_ccids(sk, skb);
 561         }
 562
 563         /*
 564          *  Step 9: Process Reset
 565          *      If P.type == Reset,
 566          *              Tear down connection
 567          *              S.state := TIMEWAIT
 568          *              Set TIMEWAIT timer
 569          *              Drop packet and return
 570         */
 571         if (dh->dccph_type == DCCP_PKT_RESET) {
 572                 dccp_rcv_reset(sk, skb);
 573                 return 0;
 574                 /*
 575                  *   Step 7: Check for unexpected packet types
 576                  *      If (S.is_server and P.type == CloseReq)
 577                  *          or (S.is_server and P.type == Response)
 578                  *          or (S.is_client and P.type == Request)
 579                  *          or (S.state == RESPOND and P.type == Data),
 580                  *        Send Sync packet acknowledging P.seqno
 581                  *        Drop packet and return
 582                  */
 583         } else if ((dp->dccps_role != DCCP_ROLE_CLIENT &&
 584                     (dh->dccph_type == DCCP_PKT_RESPONSE ||
 585                      dh->dccph_type == DCCP_PKT_CLOSEREQ)) ||
 586                     (dp->dccps_role == DCCP_ROLE_CLIENT &&
 587                      dh->dccph_type == DCCP_PKT_REQUEST) ||
 588                     (sk->sk_state == DCCP_RESPOND &&
 589                      dh->dccph_type == DCCP_PKT_DATA)) {
 590                 dccp_send_sync(sk, dcb->dccpd_seq, DCCP_PKT_SYNC);
 591                 goto discard;
 592         } else if (dh->dccph_type == DCCP_PKT_CLOSEREQ) {
 593                 dccp_rcv_closereq(sk, skb);
 594                 goto discard;
 595         } else if (dh->dccph_type == DCCP_PKT_CLOSE) {
 596                 dccp_rcv_close(sk, skb);
 597                 return 0;
 598         }
 599
 600         switch (sk->sk_state) {
 601         case DCCP_CLOSED:
 602                 dcb->dccpd_reset_code = DCCP_RESET_CODE_NO_CONNECTION;
 603                 return 1;
 604
 605         case DCCP_REQUESTING:
 606                 /* FIXME: do congestion control initialization */
 607
 608                 queued = dccp_rcv_request_sent_state_process(sk, skb, dh, len);
 609                 if (queued >= 0)
 610                         return queued;
 611
 612                 __kfree_skb(skb);
 613                 return 0;
 614
 615         case DCCP_RESPOND:
 616         case DCCP_PARTOPEN:
 617                 queued = dccp_rcv_respond_partopen_state_process(sk, skb,
 618                                                                  dh, len);
 619                 break;
 620         }
 621
 622         if (dh->dccph_type == DCCP_PKT_ACK ||
 623             dh->dccph_type == DCCP_PKT_DATAACK) {
 624                 switch (old_state) {
 625                 case DCCP_PARTOPEN:
 626                         sk->sk_state_change(sk);
 627                         sk_wake_async(sk, 0, POLL_OUT);
 628                         break;
 629                 }
 630         } else if (unlikely(dh->dccph_type == DCCP_PKT_SYNC)) {
 631                 dccp_send_sync(sk, dcb->dccpd_seq, DCCP_PKT_SYNCACK);
 632                 goto discard;
 633         }
 634
 635         if (!queued) {
 636 discard:
 637                 __kfree_skb(skb);
 638         }
 639         return 0;
 640 }
 641
 642 EXPORT_SYMBOL_GPL(dccp_rcv_state_process);
 643
 644 /**
 645  *  dccp_sample_rtt  -  Validate and finalise computation of RTT sample
 646  *  @delta:     number of microseconds between packet and acknowledgment
 647  *  The routine is kept generic to work in different contexts. It should be
 648  *  called immediately when the ACK used for the RTT sample arrives.
 649  */
 650 u32 dccp_sample_rtt(struct sock *sk, long delta)
 651 {
 652         /* dccpor_elapsed_time is either zeroed out or set and > 0 */
 653         delta -= dccp_sk(sk)->dccps_options_received.dccpor_elapsed_time * 10;
 654
 655         if (unlikely(delta <= 0)) {
 656                 DCCP_WARN("unusable RTT sample %ld, using min\n", delta);
 657                 return DCCP_SANE_RTT_MIN;
 658         }
 659         if (unlikely(delta > DCCP_SANE_RTT_MAX)) {
 660                 DCCP_WARN("RTT sample %ld too large, using max\n", delta);
 661                 return DCCP_SANE_RTT_MAX;
 662         }
 663
 664         return delta;
 665 }
 666
 667 EXPORT_SYMBOL_GPL(dccp_sample_rtt);