4 * An implementation of the DCCP protocol
5 * Arnaldo Carvalho de Melo <acme@conectiva.com.br>
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.
13 #include <linux/dccp.h>
14 #include <linux/skbuff.h>
22 static void dccp_fin(struct sock
*sk
, struct sk_buff
*skb
)
24 sk
->sk_shutdown
|= RCV_SHUTDOWN
;
25 sock_set_flag(sk
, SOCK_DONE
);
26 __skb_pull(skb
, dccp_hdr(skb
)->dccph_doff
* 4);
27 __skb_queue_tail(&sk
->sk_receive_queue
, skb
);
28 skb_set_owner_r(skb
, sk
);
29 sk
->sk_data_ready(sk
, 0);
32 static void dccp_rcv_close(struct sock
*sk
, struct sk_buff
*skb
)
34 dccp_send_reset(sk
, DCCP_RESET_CODE_CLOSED
);
36 dccp_set_state(sk
, DCCP_CLOSED
);
37 sk_wake_async(sk
, 1, POLL_HUP
);
40 static void dccp_rcv_closereq(struct sock
*sk
, struct sk_buff
*skb
)
43 * Step 7: Check for unexpected packet types
44 * If (S.is_server and P.type == CloseReq)
45 * Send Sync packet acknowledging P.seqno
46 * Drop packet and return
48 if (dccp_sk(sk
)->dccps_role
!= DCCP_ROLE_CLIENT
) {
49 dccp_send_sync(sk
, DCCP_SKB_CB(skb
)->dccpd_seq
, DCCP_PKT_SYNC
);
53 if (sk
->sk_state
!= DCCP_CLOSING
)
54 dccp_set_state(sk
, DCCP_CLOSING
);
55 dccp_send_close(sk
, 0);
58 static void dccp_event_ack_recv(struct sock
*sk
, struct sk_buff
*skb
)
60 struct dccp_sock
*dp
= dccp_sk(sk
);
62 if (dccp_msk(sk
)->dccpms_send_ack_vector
)
63 dccp_ackvec_check_rcv_ackno(dp
->dccps_hc_rx_ackvec
, sk
,
64 DCCP_SKB_CB(skb
)->dccpd_ack_seq
);
67 static int dccp_check_seqno(struct sock
*sk
, struct sk_buff
*skb
)
69 const struct dccp_hdr
*dh
= dccp_hdr(skb
);
70 struct dccp_sock
*dp
= dccp_sk(sk
);
71 u64 lswl
, lawl
, seqno
= DCCP_SKB_CB(skb
)->dccpd_seq
,
72 ackno
= DCCP_SKB_CB(skb
)->dccpd_ack_seq
;
75 * Step 5: Prepare sequence numbers for Sync
76 * If P.type == Sync or P.type == SyncAck,
77 * If S.AWL <= P.ackno <= S.AWH and P.seqno >= S.SWL,
78 * / * P is valid, so update sequence number variables
79 * accordingly. After this update, P will pass the tests
80 * in Step 6. A SyncAck is generated if necessary in
82 * Update S.GSR, S.SWL, S.SWH
84 * Drop packet and return
86 if (dh
->dccph_type
== DCCP_PKT_SYNC
||
87 dh
->dccph_type
== DCCP_PKT_SYNCACK
) {
88 if (between48(ackno
, dp
->dccps_awl
, dp
->dccps_awh
) &&
89 dccp_delta_seqno(dp
->dccps_swl
, seqno
) >= 0)
90 dccp_update_gsr(sk
, seqno
);
96 * Step 6: Check sequence numbers
97 * Let LSWL = S.SWL and LAWL = S.AWL
98 * If P.type == CloseReq or P.type == Close or P.type == Reset,
99 * LSWL := S.GSR + 1, LAWL := S.GAR
100 * If LSWL <= P.seqno <= S.SWH
101 * and (P.ackno does not exist or LAWL <= P.ackno <= S.AWH),
102 * Update S.GSR, S.SWL, S.SWH
106 lswl
= dp
->dccps_swl
;
107 lawl
= dp
->dccps_awl
;
109 if (dh
->dccph_type
== DCCP_PKT_CLOSEREQ
||
110 dh
->dccph_type
== DCCP_PKT_CLOSE
||
111 dh
->dccph_type
== DCCP_PKT_RESET
) {
112 lswl
= ADD48(dp
->dccps_gsr
, 1);
113 lawl
= dp
->dccps_gar
;
116 if (between48(seqno
, lswl
, dp
->dccps_swh
) &&
117 (ackno
== DCCP_PKT_WITHOUT_ACK_SEQ
||
118 between48(ackno
, lawl
, dp
->dccps_awh
))) {
119 dccp_update_gsr(sk
, seqno
);
121 if (dh
->dccph_type
!= DCCP_PKT_SYNC
&&
122 (ackno
!= DCCP_PKT_WITHOUT_ACK_SEQ
))
123 dp
->dccps_gar
= ackno
;
125 DCCP_WARN("DCCP: Step 6 failed for %s packet, "
126 "(LSWL(%llu) <= P.seqno(%llu) <= S.SWH(%llu)) and "
127 "(P.ackno %s or LAWL(%llu) <= P.ackno(%llu) <= S.AWH(%llu), "
128 "sending SYNC...\n", dccp_packet_name(dh
->dccph_type
),
129 (unsigned long long) lswl
, (unsigned long long) seqno
,
130 (unsigned long long) dp
->dccps_swh
,
131 (ackno
== DCCP_PKT_WITHOUT_ACK_SEQ
) ? "doesn't exist"
133 (unsigned long long) lawl
, (unsigned long long) ackno
,
134 (unsigned long long) dp
->dccps_awh
);
136 * Step 6: Check sequence numbers
138 * If P.type == Reset,
139 * Send Sync packet acknowledging S.GSR
141 * Send Sync packet acknowledging P.seqno
142 * Drop packet and return
144 if (dh
->dccph_type
== DCCP_PKT_RESET
)
145 seqno
= dp
->dccps_gsr
;
146 dccp_send_sync(sk
, seqno
, DCCP_PKT_SYNC
);
153 static int __dccp_rcv_established(struct sock
*sk
, struct sk_buff
*skb
,
154 const struct dccp_hdr
*dh
, const unsigned len
)
156 struct dccp_sock
*dp
= dccp_sk(sk
);
158 switch (dccp_hdr(skb
)->dccph_type
) {
159 case DCCP_PKT_DATAACK
:
162 * FIXME: check if sk_receive_queue is full, schedule DATA_DROPPED
165 __skb_pull(skb
, dh
->dccph_doff
* 4);
166 __skb_queue_tail(&sk
->sk_receive_queue
, skb
);
167 skb_set_owner_r(skb
, sk
);
168 sk
->sk_data_ready(sk
, 0);
174 * Step 9: Process Reset
175 * If P.type == Reset,
176 * Tear down connection
177 * S.state := TIMEWAIT
179 * Drop packet and return
182 dccp_time_wait(sk
, DCCP_TIME_WAIT
, 0);
184 case DCCP_PKT_CLOSEREQ
:
185 dccp_rcv_closereq(sk
, skb
);
188 dccp_rcv_close(sk
, skb
);
190 case DCCP_PKT_REQUEST
:
192 * or (S.is_server and P.type == Response)
193 * or (S.is_client and P.type == Request)
194 * or (S.state >= OPEN and P.type == Request
195 * and P.seqno >= S.OSR)
196 * or (S.state >= OPEN and P.type == Response
197 * and P.seqno >= S.OSR)
198 * or (S.state == RESPOND and P.type == Data),
199 * Send Sync packet acknowledging P.seqno
200 * Drop packet and return
202 if (dp
->dccps_role
!= DCCP_ROLE_LISTEN
)
205 case DCCP_PKT_RESPONSE
:
206 if (dp
->dccps_role
!= DCCP_ROLE_CLIENT
)
209 if (dccp_delta_seqno(dp
->dccps_osr
,
210 DCCP_SKB_CB(skb
)->dccpd_seq
) >= 0) {
212 dccp_send_sync(sk
, DCCP_SKB_CB(skb
)->dccpd_seq
,
217 dccp_send_sync(sk
, DCCP_SKB_CB(skb
)->dccpd_seq
,
220 * From RFC 4340, sec. 5.7
222 * As with DCCP-Ack packets, DCCP-Sync and DCCP-SyncAck packets
223 * MAY have non-zero-length application data areas, whose
224 * contents receivers MUST ignore.
229 DCCP_INC_STATS_BH(DCCP_MIB_INERRS
);
235 int dccp_rcv_established(struct sock
*sk
, struct sk_buff
*skb
,
236 const struct dccp_hdr
*dh
, const unsigned len
)
238 struct dccp_sock
*dp
= dccp_sk(sk
);
240 if (dccp_check_seqno(sk
, skb
))
243 if (dccp_parse_options(sk
, skb
))
246 if (DCCP_SKB_CB(skb
)->dccpd_ack_seq
!= DCCP_PKT_WITHOUT_ACK_SEQ
)
247 dccp_event_ack_recv(sk
, skb
);
249 if (dccp_msk(sk
)->dccpms_send_ack_vector
&&
250 dccp_ackvec_add(dp
->dccps_hc_rx_ackvec
, sk
,
251 DCCP_SKB_CB(skb
)->dccpd_seq
,
252 DCCP_ACKVEC_STATE_RECEIVED
))
255 ccid_hc_rx_packet_recv(dp
->dccps_hc_rx_ccid
, sk
, skb
);
256 ccid_hc_tx_packet_recv(dp
->dccps_hc_tx_ccid
, sk
, skb
);
258 return __dccp_rcv_established(sk
, skb
, dh
, len
);
264 EXPORT_SYMBOL_GPL(dccp_rcv_established
);
266 static int dccp_rcv_request_sent_state_process(struct sock
*sk
,
268 const struct dccp_hdr
*dh
,
272 * Step 4: Prepare sequence numbers in REQUEST
273 * If S.state == REQUEST,
274 * If (P.type == Response or P.type == Reset)
275 * and S.AWL <= P.ackno <= S.AWH,
276 * / * Set sequence number variables corresponding to the
277 * other endpoint, so P will pass the tests in Step 6 * /
278 * Set S.GSR, S.ISR, S.SWL, S.SWH
279 * / * Response processing continues in Step 10; Reset
280 * processing continues in Step 9 * /
282 if (dh
->dccph_type
== DCCP_PKT_RESPONSE
) {
283 const struct inet_connection_sock
*icsk
= inet_csk(sk
);
284 struct dccp_sock
*dp
= dccp_sk(sk
);
285 long tstamp
= dccp_timestamp();
287 /* Stop the REQUEST timer */
288 inet_csk_clear_xmit_timer(sk
, ICSK_TIME_RETRANS
);
289 BUG_TRAP(sk
->sk_send_head
!= NULL
);
290 __kfree_skb(sk
->sk_send_head
);
291 sk
->sk_send_head
= NULL
;
293 if (!between48(DCCP_SKB_CB(skb
)->dccpd_ack_seq
,
294 dp
->dccps_awl
, dp
->dccps_awh
)) {
295 dccp_pr_debug("invalid ackno: S.AWL=%llu, "
296 "P.ackno=%llu, S.AWH=%llu \n",
297 (unsigned long long)dp
->dccps_awl
,
298 (unsigned long long)DCCP_SKB_CB(skb
)->dccpd_ack_seq
,
299 (unsigned long long)dp
->dccps_awh
);
300 goto out_invalid_packet
;
303 if (dccp_parse_options(sk
, skb
))
304 goto out_invalid_packet
;
306 /* Obtain usec RTT sample from SYN exchange (used by CCID 3) */
307 if (likely(dp
->dccps_options_received
.dccpor_timestamp_echo
))
308 dp
->dccps_syn_rtt
= dccp_sample_rtt(sk
, 10 * (tstamp
-
309 dp
->dccps_options_received
.dccpor_timestamp_echo
));
311 if (dccp_msk(sk
)->dccpms_send_ack_vector
&&
312 dccp_ackvec_add(dp
->dccps_hc_rx_ackvec
, sk
,
313 DCCP_SKB_CB(skb
)->dccpd_seq
,
314 DCCP_ACKVEC_STATE_RECEIVED
))
315 goto out_invalid_packet
; /* FIXME: change error code */
317 dp
->dccps_isr
= DCCP_SKB_CB(skb
)->dccpd_seq
;
318 dccp_update_gsr(sk
, dp
->dccps_isr
);
320 * SWL and AWL are initially adjusted so that they are not less than
321 * the initial Sequence Numbers received and sent, respectively:
322 * SWL := max(GSR + 1 - floor(W/4), ISR),
323 * AWL := max(GSS - W' + 1, ISS).
324 * These adjustments MUST be applied only at the beginning of the
327 * AWL was adjusted in dccp_v4_connect -acme
329 dccp_set_seqno(&dp
->dccps_swl
,
330 max48(dp
->dccps_swl
, dp
->dccps_isr
));
332 dccp_sync_mss(sk
, icsk
->icsk_pmtu_cookie
);
335 * Step 10: Process REQUEST state (second part)
336 * If S.state == REQUEST,
337 * / * If we get here, P is a valid Response from the
338 * server (see Step 4), and we should move to
339 * PARTOPEN state. PARTOPEN means send an Ack,
340 * don't send Data packets, retransmit Acks
341 * periodically, and always include any Init Cookie
342 * from the Response * /
343 * S.state := PARTOPEN
345 * Continue with S.state == PARTOPEN
346 * / * Step 12 will send the Ack completing the
347 * three-way handshake * /
349 dccp_set_state(sk
, DCCP_PARTOPEN
);
351 /* Make sure socket is routed, for correct metrics. */
352 icsk
->icsk_af_ops
->rebuild_header(sk
);
354 if (!sock_flag(sk
, SOCK_DEAD
)) {
355 sk
->sk_state_change(sk
);
356 sk_wake_async(sk
, 0, POLL_OUT
);
359 if (sk
->sk_write_pending
|| icsk
->icsk_ack
.pingpong
||
360 icsk
->icsk_accept_queue
.rskq_defer_accept
) {
361 /* Save one ACK. Data will be ready after
362 * several ticks, if write_pending is set.
364 * It may be deleted, but with this feature tcpdumps
365 * look so _wonderfully_ clever, that I was not able
366 * to stand against the temptation 8) --ANK
369 * OK, in DCCP we can as well do a similar trick, its
370 * even in the draft, but there is no need for us to
371 * schedule an ack here, as dccp_sendmsg does this for
372 * us, also stated in the draft. -acme
382 /* dccp_v4_do_rcv will send a reset */
383 DCCP_SKB_CB(skb
)->dccpd_reset_code
= DCCP_RESET_CODE_PACKET_ERROR
;
387 static int dccp_rcv_respond_partopen_state_process(struct sock
*sk
,
389 const struct dccp_hdr
*dh
,
394 switch (dh
->dccph_type
) {
396 inet_csk_clear_xmit_timer(sk
, ICSK_TIME_DACK
);
399 if (sk
->sk_state
== DCCP_RESPOND
)
401 case DCCP_PKT_DATAACK
:
404 * FIXME: we should be reseting the PARTOPEN (DELACK) timer
405 * here but only if we haven't used the DELACK timer for
406 * something else, like sending a delayed ack for a TIMESTAMP
407 * echo, etc, for now were not clearing it, sending an extra
408 * ACK when there is nothing else to do in DELACK is not a big
412 /* Stop the PARTOPEN timer */
413 if (sk
->sk_state
== DCCP_PARTOPEN
)
414 inet_csk_clear_xmit_timer(sk
, ICSK_TIME_DACK
);
416 dccp_sk(sk
)->dccps_osr
= DCCP_SKB_CB(skb
)->dccpd_seq
;
417 dccp_set_state(sk
, DCCP_OPEN
);
419 if (dh
->dccph_type
== DCCP_PKT_DATAACK
||
420 dh
->dccph_type
== DCCP_PKT_DATA
) {
421 __dccp_rcv_established(sk
, skb
, dh
, len
);
422 queued
= 1; /* packet was queued
423 (by __dccp_rcv_established) */
431 int dccp_rcv_state_process(struct sock
*sk
, struct sk_buff
*skb
,
432 struct dccp_hdr
*dh
, unsigned len
)
434 struct dccp_sock
*dp
= dccp_sk(sk
);
435 struct dccp_skb_cb
*dcb
= DCCP_SKB_CB(skb
);
436 const int old_state
= sk
->sk_state
;
440 * Step 3: Process LISTEN state
442 * If S.state == LISTEN,
443 * If P.type == Request or P contains a valid Init Cookie option,
444 * (* Must scan the packet's options to check for Init
445 * Cookies. Only Init Cookies are processed here,
446 * however; other options are processed in Step 8. This
447 * scan need only be performed if the endpoint uses Init
449 * (* Generate a new socket and switch to that socket *)
450 * Set S := new socket for this port pair
452 * Choose S.ISS (initial seqno) or set from Init Cookies
453 * Initialize S.GAR := S.ISS
454 * Set S.ISR, S.GSR, S.SWL, S.SWH from packet or Init
455 * Cookies Continue with S.state == RESPOND
456 * (* A Response packet will be generated in Step 11 *)
458 * Generate Reset(No Connection) unless P.type == Reset
459 * Drop packet and return
461 if (sk
->sk_state
== DCCP_LISTEN
) {
462 if (dh
->dccph_type
== DCCP_PKT_REQUEST
) {
463 if (inet_csk(sk
)->icsk_af_ops
->conn_request(sk
,
467 /* FIXME: do congestion control initialization */
470 if (dh
->dccph_type
== DCCP_PKT_RESET
)
473 /* Caller (dccp_v4_do_rcv) will send Reset */
474 dcb
->dccpd_reset_code
= DCCP_RESET_CODE_NO_CONNECTION
;
478 if (sk
->sk_state
!= DCCP_REQUESTING
) {
479 if (dccp_check_seqno(sk
, skb
))
483 * Step 8: Process options and mark acknowledgeable
485 if (dccp_parse_options(sk
, skb
))
488 if (dcb
->dccpd_ack_seq
!= DCCP_PKT_WITHOUT_ACK_SEQ
)
489 dccp_event_ack_recv(sk
, skb
);
491 if (dccp_msk(sk
)->dccpms_send_ack_vector
&&
492 dccp_ackvec_add(dp
->dccps_hc_rx_ackvec
, sk
,
493 DCCP_SKB_CB(skb
)->dccpd_seq
,
494 DCCP_ACKVEC_STATE_RECEIVED
))
497 ccid_hc_rx_packet_recv(dp
->dccps_hc_rx_ccid
, sk
, skb
);
498 ccid_hc_tx_packet_recv(dp
->dccps_hc_tx_ccid
, sk
, skb
);
502 * Step 9: Process Reset
503 * If P.type == Reset,
504 * Tear down connection
505 * S.state := TIMEWAIT
507 * Drop packet and return
509 if (dh
->dccph_type
== DCCP_PKT_RESET
) {
511 * Queue the equivalent of TCP fin so that dccp_recvmsg
515 dccp_time_wait(sk
, DCCP_TIME_WAIT
, 0);
518 * Step 7: Check for unexpected packet types
519 * If (S.is_server and P.type == CloseReq)
520 * or (S.is_server and P.type == Response)
521 * or (S.is_client and P.type == Request)
522 * or (S.state == RESPOND and P.type == Data),
523 * Send Sync packet acknowledging P.seqno
524 * Drop packet and return
526 } else if ((dp
->dccps_role
!= DCCP_ROLE_CLIENT
&&
527 (dh
->dccph_type
== DCCP_PKT_RESPONSE
||
528 dh
->dccph_type
== DCCP_PKT_CLOSEREQ
)) ||
529 (dp
->dccps_role
== DCCP_ROLE_CLIENT
&&
530 dh
->dccph_type
== DCCP_PKT_REQUEST
) ||
531 (sk
->sk_state
== DCCP_RESPOND
&&
532 dh
->dccph_type
== DCCP_PKT_DATA
)) {
533 dccp_send_sync(sk
, dcb
->dccpd_seq
, DCCP_PKT_SYNC
);
535 } else if (dh
->dccph_type
== DCCP_PKT_CLOSEREQ
) {
536 dccp_rcv_closereq(sk
, skb
);
538 } else if (dh
->dccph_type
== DCCP_PKT_CLOSE
) {
539 dccp_rcv_close(sk
, skb
);
543 if (unlikely(dh
->dccph_type
== DCCP_PKT_SYNC
)) {
544 dccp_send_sync(sk
, dcb
->dccpd_seq
, DCCP_PKT_SYNCACK
);
548 switch (sk
->sk_state
) {
550 dcb
->dccpd_reset_code
= DCCP_RESET_CODE_NO_CONNECTION
;
553 case DCCP_REQUESTING
:
554 /* FIXME: do congestion control initialization */
556 queued
= dccp_rcv_request_sent_state_process(sk
, skb
, dh
, len
);
565 queued
= dccp_rcv_respond_partopen_state_process(sk
, skb
,
570 if (dh
->dccph_type
== DCCP_PKT_ACK
||
571 dh
->dccph_type
== DCCP_PKT_DATAACK
) {
574 sk
->sk_state_change(sk
);
575 sk_wake_async(sk
, 0, POLL_OUT
);
587 EXPORT_SYMBOL_GPL(dccp_rcv_state_process
);
590 * dccp_sample_rtt - Validate and finalise computation of RTT sample
591 * @delta: number of microseconds between packet and acknowledgment
592 * The routine is kept generic to work in different contexts. It should be
593 * called immediately when the ACK used for the RTT sample arrives.
595 u32
dccp_sample_rtt(struct sock
*sk
, long delta
)
597 /* dccpor_elapsed_time is either zeroed out or set and > 0 */
598 delta
-= dccp_sk(sk
)->dccps_options_received
.dccpor_elapsed_time
* 10;
600 if (unlikely(delta
<= 0)) {
601 DCCP_WARN("unusable RTT sample %ld, using min\n", delta
);
602 return DCCP_SANE_RTT_MIN
;
604 if (unlikely(delta
> DCCP_SANE_RTT_MAX
)) {
605 DCCP_WARN("RTT sample %ld too large, using max\n", delta
);
606 return DCCP_SANE_RTT_MAX
;
612 EXPORT_SYMBOL_GPL(dccp_sample_rtt
);