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