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/config.h>
14 #include <linux/dccp.h>
15 #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_v4_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 dccp_set_state(sk
, DCCP_CLOSING
);
54 dccp_send_close(sk
, 0);
57 static inline void dccp_event_ack_recv(struct sock
*sk
, struct sk_buff
*skb
)
59 struct dccp_sock
*dp
= dccp_sk(sk
);
61 if (dp
->dccps_options
.dccpo_send_ack_vector
)
62 dccp_ackpkts_check_rcv_ackno(dp
->dccps_hc_rx_ackpkts
, sk
,
63 DCCP_SKB_CB(skb
)->dccpd_ack_seq
);
66 static int dccp_check_seqno(struct sock
*sk
, struct sk_buff
*skb
)
68 const struct dccp_hdr
*dh
= dccp_hdr(skb
);
69 struct dccp_sock
*dp
= dccp_sk(sk
);
73 * Step 5: Prepare sequence numbers for Sync
74 * If P.type == Sync or P.type == SyncAck,
75 * If S.AWL <= P.ackno <= S.AWH and P.seqno >= S.SWL,
76 * / * P is valid, so update sequence number variables
77 * accordingly. After this update, P will pass the tests
78 * in Step 6. A SyncAck is generated if necessary in
80 * Update S.GSR, S.SWL, S.SWH
82 * Drop packet and return
84 if (dh
->dccph_type
== DCCP_PKT_SYNC
||
85 dh
->dccph_type
== DCCP_PKT_SYNCACK
) {
86 if (between48(DCCP_SKB_CB(skb
)->dccpd_ack_seq
,
87 dp
->dccps_awl
, dp
->dccps_awh
) &&
88 !before48(DCCP_SKB_CB(skb
)->dccpd_seq
, dp
->dccps_swl
))
89 dccp_update_gsr(sk
, DCCP_SKB_CB(skb
)->dccpd_seq
);
95 * Step 6: Check sequence numbers
96 * Let LSWL = S.SWL and LAWL = S.AWL
97 * If P.type == CloseReq or P.type == Close or P.type == Reset,
98 * LSWL := S.GSR + 1, LAWL := S.GAR
99 * If LSWL <= P.seqno <= S.SWH
100 * and (P.ackno does not exist or LAWL <= P.ackno <= S.AWH),
101 * Update S.GSR, S.SWL, S.SWH
105 * Send Sync packet acknowledging P.seqno
106 * Drop packet and return
108 lswl
= dp
->dccps_swl
;
109 lawl
= dp
->dccps_awl
;
111 if (dh
->dccph_type
== DCCP_PKT_CLOSEREQ
||
112 dh
->dccph_type
== DCCP_PKT_CLOSE
||
113 dh
->dccph_type
== DCCP_PKT_RESET
) {
114 lswl
= dp
->dccps_gsr
;
115 dccp_inc_seqno(&lswl
);
116 lawl
= dp
->dccps_gar
;
119 if (between48(DCCP_SKB_CB(skb
)->dccpd_seq
, lswl
, dp
->dccps_swh
) &&
120 (DCCP_SKB_CB(skb
)->dccpd_ack_seq
== DCCP_PKT_WITHOUT_ACK_SEQ
||
121 between48(DCCP_SKB_CB(skb
)->dccpd_ack_seq
,
122 lawl
, dp
->dccps_awh
))) {
123 dccp_update_gsr(sk
, DCCP_SKB_CB(skb
)->dccpd_seq
);
125 if (dh
->dccph_type
!= DCCP_PKT_SYNC
&&
126 (DCCP_SKB_CB(skb
)->dccpd_ack_seq
!=
127 DCCP_PKT_WITHOUT_ACK_SEQ
))
128 dp
->dccps_gar
= DCCP_SKB_CB(skb
)->dccpd_ack_seq
;
130 LIMIT_NETDEBUG(KERN_WARNING
"DCCP: Step 6 failed for %s packet, "
131 "(LSWL(%llu) <= P.seqno(%llu) <= S.SWH(%llu)) and "
132 "(P.ackno %s or LAWL(%llu) <= P.ackno(%llu) <= S.AWH(%llu), "
134 dccp_packet_name(dh
->dccph_type
),
135 (unsigned long long) lswl
,
137 DCCP_SKB_CB(skb
)->dccpd_seq
,
138 (unsigned long long) dp
->dccps_swh
,
139 (DCCP_SKB_CB(skb
)->dccpd_ack_seq
==
140 DCCP_PKT_WITHOUT_ACK_SEQ
) ? "doesn't exist" : "exists",
141 (unsigned long long) lawl
,
143 DCCP_SKB_CB(skb
)->dccpd_ack_seq
,
144 (unsigned long long) dp
->dccps_awh
);
145 dccp_send_sync(sk
, DCCP_SKB_CB(skb
)->dccpd_seq
, DCCP_PKT_SYNC
);
152 int dccp_rcv_established(struct sock
*sk
, struct sk_buff
*skb
,
153 const struct dccp_hdr
*dh
, const unsigned len
)
155 struct dccp_sock
*dp
= dccp_sk(sk
);
157 if (dccp_check_seqno(sk
, skb
))
160 if (dccp_parse_options(sk
, skb
))
163 if (DCCP_SKB_CB(skb
)->dccpd_ack_seq
!= DCCP_PKT_WITHOUT_ACK_SEQ
)
164 dccp_event_ack_recv(sk
, skb
);
167 * FIXME: check ECN to see if we should use
168 * DCCP_ACKPKTS_STATE_ECN_MARKED
170 if (dp
->dccps_options
.dccpo_send_ack_vector
) {
171 struct dccp_ackpkts
*ap
= dp
->dccps_hc_rx_ackpkts
;
173 if (dccp_ackpkts_add(dp
->dccps_hc_rx_ackpkts
,
174 DCCP_SKB_CB(skb
)->dccpd_seq
,
175 DCCP_ACKPKTS_STATE_RECEIVED
)) {
176 LIMIT_NETDEBUG(KERN_WARNING
"DCCP: acknowledgeable "
177 "packets buffer full!\n");
178 ap
->dccpap_ack_seqno
= DCCP_MAX_SEQNO
+ 1;
179 inet_csk_schedule_ack(sk
);
180 inet_csk_reset_xmit_timer(sk
, ICSK_TIME_DACK
,
187 * FIXME: this activation is probably wrong, have to study more
188 * TCP delack machinery and how it fits into DCCP draft, but
189 * for now it kinda "works" 8)
191 if (!inet_csk_ack_scheduled(sk
)) {
192 inet_csk_schedule_ack(sk
);
193 inet_csk_reset_xmit_timer(sk
, ICSK_TIME_DACK
, 5 * HZ
,
198 ccid_hc_rx_packet_recv(dp
->dccps_hc_rx_ccid
, sk
, skb
);
199 ccid_hc_tx_packet_recv(dp
->dccps_hc_tx_ccid
, sk
, skb
);
201 switch (dccp_hdr(skb
)->dccph_type
) {
202 case DCCP_PKT_DATAACK
:
205 * FIXME: check if sk_receive_queue is full, schedule DATA_DROPPED
208 __skb_pull(skb
, dh
->dccph_doff
* 4);
209 __skb_queue_tail(&sk
->sk_receive_queue
, skb
);
210 skb_set_owner_r(skb
, sk
);
211 sk
->sk_data_ready(sk
, 0);
217 * Step 9: Process Reset
218 * If P.type == Reset,
219 * Tear down connection
220 * S.state := TIMEWAIT
222 * Drop packet and return
225 dccp_time_wait(sk
, DCCP_TIME_WAIT
, 0);
227 case DCCP_PKT_CLOSEREQ
:
228 dccp_rcv_closereq(sk
, skb
);
231 dccp_rcv_close(sk
, skb
);
233 case DCCP_PKT_REQUEST
:
235 * or (S.is_server and P.type == Response)
236 * or (S.is_client and P.type == Request)
237 * or (S.state >= OPEN and P.type == Request
238 * and P.seqno >= S.OSR)
239 * or (S.state >= OPEN and P.type == Response
240 * and P.seqno >= S.OSR)
241 * or (S.state == RESPOND and P.type == Data),
242 * Send Sync packet acknowledging P.seqno
243 * Drop packet and return
245 if (dp
->dccps_role
!= DCCP_ROLE_LISTEN
)
248 case DCCP_PKT_RESPONSE
:
249 if (dp
->dccps_role
!= DCCP_ROLE_CLIENT
)
252 if (!before48(DCCP_SKB_CB(skb
)->dccpd_seq
, dp
->dccps_osr
)) {
254 dccp_send_sync(sk
, DCCP_SKB_CB(skb
)->dccpd_seq
,
259 dccp_send_sync(sk
, DCCP_SKB_CB(skb
)->dccpd_seq
,
264 * As with DCCP-Ack packets, DCCP-Sync and DCCP-SyncAck packets
265 * MAY have non-zero-length application data areas, whose
266 * contents * receivers MUST ignore.
271 DCCP_INC_STATS_BH(DCCP_MIB_INERRS
);
277 static int dccp_rcv_request_sent_state_process(struct sock
*sk
,
279 const struct dccp_hdr
*dh
,
283 * Step 4: Prepare sequence numbers in REQUEST
284 * If S.state == REQUEST,
285 * If (P.type == Response or P.type == Reset)
286 * and S.AWL <= P.ackno <= S.AWH,
287 * / * Set sequence number variables corresponding to the
288 * other endpoint, so P will pass the tests in Step 6 * /
289 * Set S.GSR, S.ISR, S.SWL, S.SWH
290 * / * Response processing continues in Step 10; Reset
291 * processing continues in Step 9 * /
293 if (dh
->dccph_type
== DCCP_PKT_RESPONSE
) {
294 const struct inet_connection_sock
*icsk
= inet_csk(sk
);
295 struct dccp_sock
*dp
= dccp_sk(sk
);
297 /* Stop the REQUEST timer */
298 inet_csk_clear_xmit_timer(sk
, ICSK_TIME_RETRANS
);
299 BUG_TRAP(sk
->sk_send_head
!= NULL
);
300 __kfree_skb(sk
->sk_send_head
);
301 sk
->sk_send_head
= NULL
;
303 if (!between48(DCCP_SKB_CB(skb
)->dccpd_ack_seq
,
304 dp
->dccps_awl
, dp
->dccps_awh
)) {
305 dccp_pr_debug("invalid ackno: S.AWL=%llu, "
306 "P.ackno=%llu, S.AWH=%llu \n",
307 (unsigned long long)dp
->dccps_awl
,
308 (unsigned long long)DCCP_SKB_CB(skb
)->dccpd_ack_seq
,
309 (unsigned long long)dp
->dccps_awh
);
310 goto out_invalid_packet
;
313 dp
->dccps_isr
= DCCP_SKB_CB(skb
)->dccpd_seq
;
314 dccp_update_gsr(sk
, dp
->dccps_isr
);
316 * SWL and AWL are initially adjusted so that they are not less than
317 * the initial Sequence Numbers received and sent, respectively:
318 * SWL := max(GSR + 1 - floor(W/4), ISR),
319 * AWL := max(GSS - W' + 1, ISS).
320 * These adjustments MUST be applied only at the beginning of the
323 * AWL was adjusted in dccp_v4_connect -acme
325 dccp_set_seqno(&dp
->dccps_swl
,
326 max48(dp
->dccps_swl
, dp
->dccps_isr
));
328 if (ccid_hc_rx_init(dp
->dccps_hc_rx_ccid
, sk
) != 0 ||
329 ccid_hc_tx_init(dp
->dccps_hc_tx_ccid
, sk
) != 0) {
330 ccid_hc_rx_exit(dp
->dccps_hc_rx_ccid
, sk
);
331 ccid_hc_tx_exit(dp
->dccps_hc_tx_ccid
, sk
);
332 /* FIXME: send appropriate RESET code */
333 goto out_invalid_packet
;
336 dccp_sync_mss(sk
, dp
->dccps_pmtu_cookie
);
339 * Step 10: Process REQUEST state (second part)
340 * If S.state == REQUEST,
341 * / * If we get here, P is a valid Response from the
342 * server (see Step 4), and we should move to
343 * PARTOPEN state. PARTOPEN means send an Ack,
344 * don't send Data packets, retransmit Acks
345 * periodically, and always include any Init Cookie
346 * from the Response * /
347 * S.state := PARTOPEN
349 * Continue with S.state == PARTOPEN
350 * / * Step 12 will send the Ack completing the
351 * three-way handshake * /
353 dccp_set_state(sk
, DCCP_PARTOPEN
);
355 /* Make sure socket is routed, for correct metrics. */
356 inet_sk_rebuild_header(sk
);
358 if (!sock_flag(sk
, SOCK_DEAD
)) {
359 sk
->sk_state_change(sk
);
360 sk_wake_async(sk
, 0, POLL_OUT
);
363 if (sk
->sk_write_pending
|| icsk
->icsk_ack
.pingpong
||
364 icsk
->icsk_accept_queue
.rskq_defer_accept
) {
365 /* Save one ACK. Data will be ready after
366 * several ticks, if write_pending is set.
368 * It may be deleted, but with this feature tcpdumps
369 * look so _wonderfully_ clever, that I was not able
370 * to stand against the temptation 8) --ANK
373 * OK, in DCCP we can as well do a similar trick, its
374 * even in the draft, but there is no need for us to
375 * schedule an ack here, as dccp_sendmsg does this for
376 * us, also stated in the draft. -acme
386 return 1; /* dccp_v4_do_rcv will send a reset, but...
387 FIXME: the reset code should be
388 DCCP_RESET_CODE_PACKET_ERROR */
391 static int dccp_rcv_respond_partopen_state_process(struct sock
*sk
,
393 const struct dccp_hdr
*dh
,
398 switch (dh
->dccph_type
) {
400 inet_csk_clear_xmit_timer(sk
, ICSK_TIME_DACK
);
402 case DCCP_PKT_DATAACK
:
405 * FIXME: we should be reseting the PARTOPEN (DELACK) timer
406 * here but only if we haven't used the DELACK timer for
407 * something else, like sending a delayed ack for a TIMESTAMP
408 * echo, etc, for now were not clearing it, sending an extra
409 * ACK when there is nothing else to do in DELACK is not a big
413 /* Stop the PARTOPEN timer */
414 if (sk
->sk_state
== DCCP_PARTOPEN
)
415 inet_csk_clear_xmit_timer(sk
, ICSK_TIME_DACK
);
417 dccp_sk(sk
)->dccps_osr
= DCCP_SKB_CB(skb
)->dccpd_seq
;
418 dccp_set_state(sk
, DCCP_OPEN
);
420 if (dh
->dccph_type
== DCCP_PKT_DATAACK
) {
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 const int old_state
= sk
->sk_state
;
439 * Step 3: Process LISTEN state
440 * (Continuing from dccp_v4_do_rcv and dccp_v6_do_rcv)
442 * If S.state == LISTEN,
443 * If P.type == Request or P contains a valid Init Cookie
445 * * Must scan the packet's options to check for an Init
446 * Cookie. Only the Init Cookie is processed here,
447 * however; other options are processed in Step 8. This
448 * scan need only be performed if the endpoint uses Init
450 * * Generate a new socket and switch to that socket *
451 * Set S := new socket for this port pair
453 * Choose S.ISS (initial seqno) or set from Init Cookie
454 * Set S.ISR, S.GSR, S.SWL, S.SWH from packet or Init Cookie
455 * 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 * NOTE: the check for the packet types is done in
462 * dccp_rcv_state_process
464 if (sk
->sk_state
== DCCP_LISTEN
) {
465 if (dh
->dccph_type
== DCCP_PKT_REQUEST
) {
466 if (dccp_v4_conn_request(sk
, skb
) < 0)
469 /* FIXME: do congestion control initialization */
472 if (dh
->dccph_type
== DCCP_PKT_RESET
)
475 /* Caller (dccp_v4_do_rcv) will send Reset(No Connection)*/
479 if (sk
->sk_state
!= DCCP_REQUESTING
) {
480 if (dccp_check_seqno(sk
, skb
))
484 * Step 8: Process options and mark acknowledgeable
486 if (dccp_parse_options(sk
, skb
))
489 if (DCCP_SKB_CB(skb
)->dccpd_ack_seq
!=
490 DCCP_PKT_WITHOUT_ACK_SEQ
)
491 dccp_event_ack_recv(sk
, skb
);
493 ccid_hc_rx_packet_recv(dp
->dccps_hc_rx_ccid
, sk
, skb
);
494 ccid_hc_tx_packet_recv(dp
->dccps_hc_tx_ccid
, sk
, skb
);
497 * FIXME: check ECN to see if we should use
498 * DCCP_ACKPKTS_STATE_ECN_MARKED
500 if (dp
->dccps_options
.dccpo_send_ack_vector
) {
501 if (dccp_ackpkts_add(dp
->dccps_hc_rx_ackpkts
,
502 DCCP_SKB_CB(skb
)->dccpd_seq
,
503 DCCP_ACKPKTS_STATE_RECEIVED
))
506 * FIXME: this activation is probably wrong, have to
507 * study more TCP delack machinery and how it fits into
508 * DCCP draft, but for now it kinda "works" 8)
510 if ((dp
->dccps_hc_rx_ackpkts
->dccpap_ack_seqno
==
511 DCCP_MAX_SEQNO
+ 1) &&
512 !inet_csk_ack_scheduled(sk
)) {
513 inet_csk_schedule_ack(sk
);
514 inet_csk_reset_xmit_timer(sk
, ICSK_TIME_DACK
,
522 * Step 9: Process Reset
523 * If P.type == Reset,
524 * Tear down connection
525 * S.state := TIMEWAIT
527 * Drop packet and return
529 if (dh
->dccph_type
== DCCP_PKT_RESET
) {
531 * Queue the equivalent of TCP fin so that dccp_recvmsg
535 dccp_time_wait(sk
, DCCP_TIME_WAIT
, 0);
538 * Step 7: Check for unexpected packet types
539 * If (S.is_server and P.type == CloseReq)
540 * or (S.is_server and P.type == Response)
541 * or (S.is_client and P.type == Request)
542 * or (S.state == RESPOND and P.type == Data),
543 * Send Sync packet acknowledging P.seqno
544 * Drop packet and return
546 } else if ((dp
->dccps_role
!= DCCP_ROLE_CLIENT
&&
547 (dh
->dccph_type
== DCCP_PKT_RESPONSE
||
548 dh
->dccph_type
== DCCP_PKT_CLOSEREQ
)) ||
549 (dp
->dccps_role
== DCCP_ROLE_CLIENT
&&
550 dh
->dccph_type
== DCCP_PKT_REQUEST
) ||
551 (sk
->sk_state
== DCCP_RESPOND
&&
552 dh
->dccph_type
== DCCP_PKT_DATA
)) {
553 dccp_send_sync(sk
, DCCP_SKB_CB(skb
)->dccpd_seq
,
556 } else if (dh
->dccph_type
== DCCP_PKT_CLOSEREQ
) {
557 dccp_rcv_closereq(sk
, skb
);
559 } else if (dh
->dccph_type
== DCCP_PKT_CLOSE
) {
560 dccp_rcv_close(sk
, skb
);
564 switch (sk
->sk_state
) {
568 case DCCP_REQUESTING
:
569 /* FIXME: do congestion control initialization */
571 queued
= dccp_rcv_request_sent_state_process(sk
, skb
, dh
, len
);
580 queued
= dccp_rcv_respond_partopen_state_process(sk
, skb
,
585 if (dh
->dccph_type
== DCCP_PKT_ACK
||
586 dh
->dccph_type
== DCCP_PKT_DATAACK
) {
589 sk
->sk_state_change(sk
);
590 sk_wake_async(sk
, 0, POLL_OUT
);