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input.c
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1 /*
2  * net/dccp/input.c
3  *
4  * An implementation of the DCCP protocol
5  * Arnaldo Carvalho de Melo <[email protected]>
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 */
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  */
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:
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);
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);
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);
120  /* fall through */
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 */
133 
138 
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);
161 }
162 
163 static void dccp_handle_ackvec_processing(struct sock *sk, struct sk_buff *skb)
164 {
165  struct dccp_ackvec *av = dccp_sk(sk)->dccps_hc_rx_ackvec;
166 
167  if (av == NULL)
168  return;
169  if (DCCP_SKB_CB(skb)->dccpd_ack_seq != DCCP_PKT_WITHOUT_ACK_SEQ)
170  dccp_ackvec_clear_state(av, DCCP_SKB_CB(skb)->dccpd_ack_seq);
171  dccp_ackvec_input(av, skb);
172 }
173 
174 static void dccp_deliver_input_to_ccids(struct sock *sk, struct sk_buff *skb)
175 {
176  const struct dccp_sock *dp = dccp_sk(sk);
177 
178  /* Don't deliver to RX CCID when node has shut down read end. */
179  if (!(sk->sk_shutdown & RCV_SHUTDOWN))
180  ccid_hc_rx_packet_recv(dp->dccps_hc_rx_ccid, sk, skb);
181  /*
182  * Until the TX queue has been drained, we can not honour SHUT_WR, since
183  * we need received feedback as input to adjust congestion control.
184  */
185  if (sk->sk_write_queue.qlen > 0 || !(sk->sk_shutdown & SEND_SHUTDOWN))
186  ccid_hc_tx_packet_recv(dp->dccps_hc_tx_ccid, sk, skb);
187 }
188 
189 static int dccp_check_seqno(struct sock *sk, struct sk_buff *skb)
190 {
191  const struct dccp_hdr *dh = dccp_hdr(skb);
192  struct dccp_sock *dp = dccp_sk(sk);
193  u64 lswl, lawl, seqno = DCCP_SKB_CB(skb)->dccpd_seq,
194  ackno = DCCP_SKB_CB(skb)->dccpd_ack_seq;
195 
196  /*
197  * Step 5: Prepare sequence numbers for Sync
198  * If P.type == Sync or P.type == SyncAck,
199  * If S.AWL <= P.ackno <= S.AWH and P.seqno >= S.SWL,
200  * / * P is valid, so update sequence number variables
201  * accordingly. After this update, P will pass the tests
202  * in Step 6. A SyncAck is generated if necessary in
203  * Step 15 * /
204  * Update S.GSR, S.SWL, S.SWH
205  * Otherwise,
206  * Drop packet and return
207  */
208  if (dh->dccph_type == DCCP_PKT_SYNC ||
209  dh->dccph_type == DCCP_PKT_SYNCACK) {
210  if (between48(ackno, dp->dccps_awl, dp->dccps_awh) &&
211  dccp_delta_seqno(dp->dccps_swl, seqno) >= 0)
212  dccp_update_gsr(sk, seqno);
213  else
214  return -1;
215  }
216 
217  /*
218  * Step 6: Check sequence numbers
219  * Let LSWL = S.SWL and LAWL = S.AWL
220  * If P.type == CloseReq or P.type == Close or P.type == Reset,
221  * LSWL := S.GSR + 1, LAWL := S.GAR
222  * If LSWL <= P.seqno <= S.SWH
223  * and (P.ackno does not exist or LAWL <= P.ackno <= S.AWH),
224  * Update S.GSR, S.SWL, S.SWH
225  * If P.type != Sync,
226  * Update S.GAR
227  */
228  lswl = dp->dccps_swl;
229  lawl = dp->dccps_awl;
230 
231  if (dh->dccph_type == DCCP_PKT_CLOSEREQ ||
232  dh->dccph_type == DCCP_PKT_CLOSE ||
233  dh->dccph_type == DCCP_PKT_RESET) {
234  lswl = ADD48(dp->dccps_gsr, 1);
235  lawl = dp->dccps_gar;
236  }
237 
238  if (between48(seqno, lswl, dp->dccps_swh) &&
239  (ackno == DCCP_PKT_WITHOUT_ACK_SEQ ||
240  between48(ackno, lawl, dp->dccps_awh))) {
241  dccp_update_gsr(sk, seqno);
242 
243  if (dh->dccph_type != DCCP_PKT_SYNC &&
244  ackno != DCCP_PKT_WITHOUT_ACK_SEQ &&
245  after48(ackno, dp->dccps_gar))
246  dp->dccps_gar = ackno;
247  } else {
248  unsigned long now = jiffies;
249  /*
250  * Step 6: Check sequence numbers
251  * Otherwise,
252  * If P.type == Reset,
253  * Send Sync packet acknowledging S.GSR
254  * Otherwise,
255  * Send Sync packet acknowledging P.seqno
256  * Drop packet and return
257  *
258  * These Syncs are rate-limited as per RFC 4340, 7.5.4:
259  * at most 1 / (dccp_sync_rate_limit * HZ) Syncs per second.
260  */
261  if (time_before(now, (dp->dccps_rate_last +
262  sysctl_dccp_sync_ratelimit)))
263  return -1;
264 
265  DCCP_WARN("Step 6 failed for %s packet, "
266  "(LSWL(%llu) <= P.seqno(%llu) <= S.SWH(%llu)) and "
267  "(P.ackno %s or LAWL(%llu) <= P.ackno(%llu) <= S.AWH(%llu), "
268  "sending SYNC...\n", dccp_packet_name(dh->dccph_type),
269  (unsigned long long) lswl, (unsigned long long) seqno,
270  (unsigned long long) dp->dccps_swh,
271  (ackno == DCCP_PKT_WITHOUT_ACK_SEQ) ? "doesn't exist"
272  : "exists",
273  (unsigned long long) lawl, (unsigned long long) ackno,
274  (unsigned long long) dp->dccps_awh);
275 
276  dp->dccps_rate_last = now;
277 
278  if (dh->dccph_type == DCCP_PKT_RESET)
279  seqno = dp->dccps_gsr;
280  dccp_send_sync(sk, seqno, DCCP_PKT_SYNC);
281  return -1;
282  }
283 
284  return 0;
285 }
286 
287 static int __dccp_rcv_established(struct sock *sk, struct sk_buff *skb,
288  const struct dccp_hdr *dh, const unsigned int len)
289 {
290  struct dccp_sock *dp = dccp_sk(sk);
291 
292  switch (dccp_hdr(skb)->dccph_type) {
293  case DCCP_PKT_DATAACK:
294  case DCCP_PKT_DATA:
295  /*
296  * FIXME: schedule DATA_DROPPED (RFC 4340, 11.7.2) if and when
297  * - sk_shutdown == RCV_SHUTDOWN, use Code 1, "Not Listening"
298  * - sk_receive_queue is full, use Code 2, "Receive Buffer"
299  */
300  dccp_enqueue_skb(sk, skb);
301  return 0;
302  case DCCP_PKT_ACK:
303  goto discard;
304  case DCCP_PKT_RESET:
305  /*
306  * Step 9: Process Reset
307  * If P.type == Reset,
308  * Tear down connection
309  * S.state := TIMEWAIT
310  * Set TIMEWAIT timer
311  * Drop packet and return
312  */
313  dccp_rcv_reset(sk, skb);
314  return 0;
315  case DCCP_PKT_CLOSEREQ:
316  if (dccp_rcv_closereq(sk, skb))
317  return 0;
318  goto discard;
319  case DCCP_PKT_CLOSE:
320  if (dccp_rcv_close(sk, skb))
321  return 0;
322  goto discard;
323  case DCCP_PKT_REQUEST:
324  /* Step 7
325  * or (S.is_server and P.type == Response)
326  * or (S.is_client and P.type == Request)
327  * or (S.state >= OPEN and P.type == Request
328  * and P.seqno >= S.OSR)
329  * or (S.state >= OPEN and P.type == Response
330  * and P.seqno >= S.OSR)
331  * or (S.state == RESPOND and P.type == Data),
332  * Send Sync packet acknowledging P.seqno
333  * Drop packet and return
334  */
335  if (dp->dccps_role != DCCP_ROLE_LISTEN)
336  goto send_sync;
337  goto check_seq;
338  case DCCP_PKT_RESPONSE:
339  if (dp->dccps_role != DCCP_ROLE_CLIENT)
340  goto send_sync;
341 check_seq:
342  if (dccp_delta_seqno(dp->dccps_osr,
343  DCCP_SKB_CB(skb)->dccpd_seq) >= 0) {
344 send_sync:
345  dccp_send_sync(sk, DCCP_SKB_CB(skb)->dccpd_seq,
346  DCCP_PKT_SYNC);
347  }
348  break;
349  case DCCP_PKT_SYNC:
350  dccp_send_sync(sk, DCCP_SKB_CB(skb)->dccpd_seq,
352  /*
353  * From RFC 4340, sec. 5.7
354  *
355  * As with DCCP-Ack packets, DCCP-Sync and DCCP-SyncAck packets
356  * MAY have non-zero-length application data areas, whose
357  * contents receivers MUST ignore.
358  */
359  goto discard;
360  }
361 
363 discard:
364  __kfree_skb(skb);
365  return 0;
366 }
367 
368 int dccp_rcv_established(struct sock *sk, struct sk_buff *skb,
369  const struct dccp_hdr *dh, const unsigned int len)
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  dccp_handle_ackvec_processing(sk, skb);
378  dccp_deliver_input_to_ccids(sk, skb);
379 
380  return __dccp_rcv_established(sk, skb, dh, len);
381 discard:
382  __kfree_skb(skb);
383  return 0;
384 }
385 
387 
388 static int dccp_rcv_request_sent_state_process(struct sock *sk,
389  struct sk_buff *skb,
390  const struct dccp_hdr *dh,
391  const unsigned int len)
392 {
393  /*
394  * Step 4: Prepare sequence numbers in REQUEST
395  * If S.state == REQUEST,
396  * If (P.type == Response or P.type == Reset)
397  * and S.AWL <= P.ackno <= S.AWH,
398  * / * Set sequence number variables corresponding to the
399  * other endpoint, so P will pass the tests in Step 6 * /
400  * Set S.GSR, S.ISR, S.SWL, S.SWH
401  * / * Response processing continues in Step 10; Reset
402  * processing continues in Step 9 * /
403  */
404  if (dh->dccph_type == DCCP_PKT_RESPONSE) {
405  const struct inet_connection_sock *icsk = inet_csk(sk);
406  struct dccp_sock *dp = dccp_sk(sk);
407  long tstamp = dccp_timestamp();
408 
409  if (!between48(DCCP_SKB_CB(skb)->dccpd_ack_seq,
410  dp->dccps_awl, dp->dccps_awh)) {
411  dccp_pr_debug("invalid ackno: S.AWL=%llu, "
412  "P.ackno=%llu, S.AWH=%llu\n",
413  (unsigned long long)dp->dccps_awl,
414  (unsigned long long)DCCP_SKB_CB(skb)->dccpd_ack_seq,
415  (unsigned long long)dp->dccps_awh);
416  goto out_invalid_packet;
417  }
418 
419  /*
420  * If option processing (Step 8) failed, return 1 here so that
421  * dccp_v4_do_rcv() sends a Reset. The Reset code depends on
422  * the option type and is set in dccp_parse_options().
423  */
424  if (dccp_parse_options(sk, NULL, skb))
425  return 1;
426 
427  /* Obtain usec RTT sample from SYN exchange (used by TFRC). */
428  if (likely(dp->dccps_options_received.dccpor_timestamp_echo))
429  dp->dccps_syn_rtt = dccp_sample_rtt(sk, 10 * (tstamp -
430  dp->dccps_options_received.dccpor_timestamp_echo));
431 
432  /* Stop the REQUEST timer */
433  inet_csk_clear_xmit_timer(sk, ICSK_TIME_RETRANS);
434  WARN_ON(sk->sk_send_head == NULL);
435  kfree_skb(sk->sk_send_head);
436  sk->sk_send_head = NULL;
437 
438  /*
439  * Set ISR, GSR from packet. ISS was set in dccp_v{4,6}_connect
440  * and GSS in dccp_transmit_skb(). Setting AWL/AWH and SWL/SWH
441  * is done as part of activating the feature values below, since
442  * these settings depend on the local/remote Sequence Window
443  * features, which were undefined or not confirmed until now.
444  */
445  dp->dccps_gsr = dp->dccps_isr = DCCP_SKB_CB(skb)->dccpd_seq;
446 
447  dccp_sync_mss(sk, icsk->icsk_pmtu_cookie);
448 
449  /*
450  * Step 10: Process REQUEST state (second part)
451  * If S.state == REQUEST,
452  * / * If we get here, P is a valid Response from the
453  * server (see Step 4), and we should move to
454  * PARTOPEN state. PARTOPEN means send an Ack,
455  * don't send Data packets, retransmit Acks
456  * periodically, and always include any Init Cookie
457  * from the Response * /
458  * S.state := PARTOPEN
459  * Set PARTOPEN timer
460  * Continue with S.state == PARTOPEN
461  * / * Step 12 will send the Ack completing the
462  * three-way handshake * /
463  */
465 
466  /*
467  * If feature negotiation was successful, activate features now;
468  * an activation failure means that this host could not activate
469  * one ore more features (e.g. insufficient memory), which would
470  * leave at least one feature in an undefined state.
471  */
473  goto unable_to_proceed;
474 
475  /* Make sure socket is routed, for correct metrics. */
476  icsk->icsk_af_ops->rebuild_header(sk);
477 
478  if (!sock_flag(sk, SOCK_DEAD)) {
479  sk->sk_state_change(sk);
480  sk_wake_async(sk, SOCK_WAKE_IO, POLL_OUT);
481  }
482 
483  if (sk->sk_write_pending || icsk->icsk_ack.pingpong ||
484  icsk->icsk_accept_queue.rskq_defer_accept) {
485  /* Save one ACK. Data will be ready after
486  * several ticks, if write_pending is set.
487  *
488  * It may be deleted, but with this feature tcpdumps
489  * look so _wonderfully_ clever, that I was not able
490  * to stand against the temptation 8) --ANK
491  */
492  /*
493  * OK, in DCCP we can as well do a similar trick, its
494  * even in the draft, but there is no need for us to
495  * schedule an ack here, as dccp_sendmsg does this for
496  * us, also stated in the draft. -acme
497  */
498  __kfree_skb(skb);
499  return 0;
500  }
501  dccp_send_ack(sk);
502  return -1;
503  }
504 
505 out_invalid_packet:
506  /* dccp_v4_do_rcv will send a reset */
507  DCCP_SKB_CB(skb)->dccpd_reset_code = DCCP_RESET_CODE_PACKET_ERROR;
508  return 1;
509 
510 unable_to_proceed:
511  DCCP_SKB_CB(skb)->dccpd_reset_code = DCCP_RESET_CODE_ABORTED;
512  /*
513  * We mark this socket as no longer usable, so that the loop in
514  * dccp_sendmsg() terminates and the application gets notified.
515  */
517  sk->sk_err = ECOMM;
518  return 1;
519 }
520 
521 static int dccp_rcv_respond_partopen_state_process(struct sock *sk,
522  struct sk_buff *skb,
523  const struct dccp_hdr *dh,
524  const unsigned int len)
525 {
526  struct dccp_sock *dp = dccp_sk(sk);
527  u32 sample = dp->dccps_options_received.dccpor_timestamp_echo;
528  int queued = 0;
529 
530  switch (dh->dccph_type) {
531  case DCCP_PKT_RESET:
532  inet_csk_clear_xmit_timer(sk, ICSK_TIME_DACK);
533  break;
534  case DCCP_PKT_DATA:
535  if (sk->sk_state == DCCP_RESPOND)
536  break;
537  case DCCP_PKT_DATAACK:
538  case DCCP_PKT_ACK:
539  /*
540  * FIXME: we should be reseting the PARTOPEN (DELACK) timer
541  * here but only if we haven't used the DELACK timer for
542  * something else, like sending a delayed ack for a TIMESTAMP
543  * echo, etc, for now were not clearing it, sending an extra
544  * ACK when there is nothing else to do in DELACK is not a big
545  * deal after all.
546  */
547 
548  /* Stop the PARTOPEN timer */
549  if (sk->sk_state == DCCP_PARTOPEN)
550  inet_csk_clear_xmit_timer(sk, ICSK_TIME_DACK);
551 
552  /* Obtain usec RTT sample from SYN exchange (used by TFRC). */
553  if (likely(sample)) {
554  long delta = dccp_timestamp() - sample;
555 
556  dp->dccps_syn_rtt = dccp_sample_rtt(sk, 10 * delta);
557  }
558 
559  dp->dccps_osr = DCCP_SKB_CB(skb)->dccpd_seq;
561 
562  if (dh->dccph_type == DCCP_PKT_DATAACK ||
563  dh->dccph_type == DCCP_PKT_DATA) {
564  __dccp_rcv_established(sk, skb, dh, len);
565  queued = 1; /* packet was queued
566  (by __dccp_rcv_established) */
567  }
568  break;
569  }
570 
571  return queued;
572 }
573 
574 int dccp_rcv_state_process(struct sock *sk, struct sk_buff *skb,
575  struct dccp_hdr *dh, unsigned int len)
576 {
577  struct dccp_sock *dp = dccp_sk(sk);
578  struct dccp_skb_cb *dcb = DCCP_SKB_CB(skb);
579  const int old_state = sk->sk_state;
580  int queued = 0;
581 
582  /*
583  * Step 3: Process LISTEN state
584  *
585  * If S.state == LISTEN,
586  * If P.type == Request or P contains a valid Init Cookie option,
587  * (* Must scan the packet's options to check for Init
588  * Cookies. Only Init Cookies are processed here,
589  * however; other options are processed in Step 8. This
590  * scan need only be performed if the endpoint uses Init
591  * Cookies *)
592  * (* Generate a new socket and switch to that socket *)
593  * Set S := new socket for this port pair
594  * S.state = RESPOND
595  * Choose S.ISS (initial seqno) or set from Init Cookies
596  * Initialize S.GAR := S.ISS
597  * Set S.ISR, S.GSR, S.SWL, S.SWH from packet or Init
598  * Cookies Continue with S.state == RESPOND
599  * (* A Response packet will be generated in Step 11 *)
600  * Otherwise,
601  * Generate Reset(No Connection) unless P.type == Reset
602  * Drop packet and return
603  */
604  if (sk->sk_state == DCCP_LISTEN) {
605  if (dh->dccph_type == DCCP_PKT_REQUEST) {
606  if (inet_csk(sk)->icsk_af_ops->conn_request(sk,
607  skb) < 0)
608  return 1;
609  goto discard;
610  }
611  if (dh->dccph_type == DCCP_PKT_RESET)
612  goto discard;
613 
614  /* Caller (dccp_v4_do_rcv) will send Reset */
616  return 1;
617  } else if (sk->sk_state == DCCP_CLOSED) {
619  return 1;
620  }
621 
622  /* Step 6: Check sequence numbers (omitted in LISTEN/REQUEST state) */
623  if (sk->sk_state != DCCP_REQUESTING && dccp_check_seqno(sk, skb))
624  goto discard;
625 
626  /*
627  * Step 7: Check for unexpected packet types
628  * If (S.is_server and P.type == Response)
629  * or (S.is_client and P.type == Request)
630  * or (S.state == RESPOND and P.type == Data),
631  * Send Sync packet acknowledging P.seqno
632  * Drop packet and return
633  */
634  if ((dp->dccps_role != DCCP_ROLE_CLIENT &&
635  dh->dccph_type == DCCP_PKT_RESPONSE) ||
636  (dp->dccps_role == DCCP_ROLE_CLIENT &&
637  dh->dccph_type == DCCP_PKT_REQUEST) ||
638  (sk->sk_state == DCCP_RESPOND && dh->dccph_type == DCCP_PKT_DATA)) {
640  goto discard;
641  }
642 
643  /* Step 8: Process options */
644  if (dccp_parse_options(sk, NULL, skb))
645  return 1;
646 
647  /*
648  * Step 9: Process Reset
649  * If P.type == Reset,
650  * Tear down connection
651  * S.state := TIMEWAIT
652  * Set TIMEWAIT timer
653  * Drop packet and return
654  */
655  if (dh->dccph_type == DCCP_PKT_RESET) {
656  dccp_rcv_reset(sk, skb);
657  return 0;
658  } else if (dh->dccph_type == DCCP_PKT_CLOSEREQ) { /* Step 13 */
659  if (dccp_rcv_closereq(sk, skb))
660  return 0;
661  goto discard;
662  } else if (dh->dccph_type == DCCP_PKT_CLOSE) { /* Step 14 */
663  if (dccp_rcv_close(sk, skb))
664  return 0;
665  goto discard;
666  }
667 
668  switch (sk->sk_state) {
669  case DCCP_REQUESTING:
670  queued = dccp_rcv_request_sent_state_process(sk, skb, dh, len);
671  if (queued >= 0)
672  return queued;
673 
674  __kfree_skb(skb);
675  return 0;
676 
677  case DCCP_PARTOPEN:
678  /* Step 8: if using Ack Vectors, mark packet acknowledgeable */
679  dccp_handle_ackvec_processing(sk, skb);
680  dccp_deliver_input_to_ccids(sk, skb);
681  /* fall through */
682  case DCCP_RESPOND:
683  queued = dccp_rcv_respond_partopen_state_process(sk, skb,
684  dh, len);
685  break;
686  }
687 
688  if (dh->dccph_type == DCCP_PKT_ACK ||
689  dh->dccph_type == DCCP_PKT_DATAACK) {
690  switch (old_state) {
691  case DCCP_PARTOPEN:
692  sk->sk_state_change(sk);
693  sk_wake_async(sk, SOCK_WAKE_IO, POLL_OUT);
694  break;
695  }
696  } else if (unlikely(dh->dccph_type == DCCP_PKT_SYNC)) {
698  goto discard;
699  }
700 
701  if (!queued) {
702 discard:
703  __kfree_skb(skb);
704  }
705  return 0;
706 }
707 
709 
717 u32 dccp_sample_rtt(struct sock *sk, long delta)
718 {
719  /* dccpor_elapsed_time is either zeroed out or set and > 0 */
720  delta -= dccp_sk(sk)->dccps_options_received.dccpor_elapsed_time * 10;
721 
722  if (unlikely(delta <= 0)) {
723  DCCP_WARN("unusable RTT sample %ld, using min\n", delta);
724  return DCCP_SANE_RTT_MIN;
725  }
726  if (unlikely(delta > DCCP_SANE_RTT_MAX)) {
727  DCCP_WARN("RTT sample %ld too large, using max\n", delta);
728  return DCCP_SANE_RTT_MAX;
729  }
730 
731  return delta;
732 }