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 switch (sk->sk_state) {
37 dccp_v4_send_reset(sk, DCCP_RESET_CODE_CLOSED);
39 dccp_set_state(sk, DCCP_CLOSED);
44 static void dccp_rcv_closereq(struct sock *sk, struct sk_buff *skb)
47 * Step 7: Check for unexpected packet types
48 * If (S.is_server and P.type == CloseReq)
49 * Send Sync packet acknowledging P.seqno
50 * Drop packet and return
52 if (dccp_sk(sk)->dccps_role != DCCP_ROLE_CLIENT) {
53 dccp_send_sync(sk, DCCP_SKB_CB(skb)->dccpd_seq);
57 switch (sk->sk_state) {
60 dccp_set_state(sk, DCCP_CLOSING);
66 static inline void dccp_event_ack_recv(struct sock *sk, struct sk_buff *skb)
68 struct dccp_sock *dp = dccp_sk(sk);
70 if (dp->dccps_options.dccpo_send_ack_vector)
71 dccp_ackpkts_check_rcv_ackno(dp->dccps_hc_rx_ackpkts, sk,
72 DCCP_SKB_CB(skb)->dccpd_ack_seq);
75 static int dccp_check_seqno(struct sock *sk, struct sk_buff *skb)
77 const struct dccp_hdr *dh = dccp_hdr(skb);
78 struct dccp_sock *dp = dccp_sk(sk);
79 u64 lswl = dp->dccps_swl;
80 u64 lawl = dp->dccps_awl;
83 * Step 5: Prepare sequence numbers for Sync
84 * If P.type == Sync or P.type == SyncAck,
85 * If S.AWL <= P.ackno <= S.AWH and P.seqno >= S.SWL,
86 * / * P is valid, so update sequence number variables
87 * accordingly. After this update, P will pass the tests
88 * in Step 6. A SyncAck is generated if necessary in
90 * Update S.GSR, S.SWL, S.SWH
92 * Drop packet and return
94 if (dh->dccph_type == DCCP_PKT_SYNC ||
95 dh->dccph_type == DCCP_PKT_SYNCACK) {
96 if (between48(DCCP_SKB_CB(skb)->dccpd_ack_seq,
97 dp->dccps_awl, dp->dccps_awh) &&
98 !before48(DCCP_SKB_CB(skb)->dccpd_seq, dp->dccps_swl))
99 dccp_update_gsr(sk, DCCP_SKB_CB(skb)->dccpd_seq);
103 * Step 6: Check sequence numbers
104 * Let LSWL = S.SWL and LAWL = S.AWL
105 * If P.type == CloseReq or P.type == Close or P.type == Reset,
106 * LSWL := S.GSR + 1, LAWL := S.GAR
107 * If LSWL <= P.seqno <= S.SWH
108 * and (P.ackno does not exist or LAWL <= P.ackno <= S.AWH),
109 * Update S.GSR, S.SWL, S.SWH
113 * Send Sync packet acknowledging P.seqno
114 * Drop packet and return
116 } else if (dh->dccph_type == DCCP_PKT_CLOSEREQ ||
117 dh->dccph_type == DCCP_PKT_CLOSE ||
118 dh->dccph_type == DCCP_PKT_RESET) {
119 lswl = dp->dccps_gsr;
120 dccp_inc_seqno(&lswl);
121 lawl = dp->dccps_gar;
124 if (between48(DCCP_SKB_CB(skb)->dccpd_seq, lswl, dp->dccps_swh) &&
125 (DCCP_SKB_CB(skb)->dccpd_ack_seq == DCCP_PKT_WITHOUT_ACK_SEQ ||
126 between48(DCCP_SKB_CB(skb)->dccpd_ack_seq,
127 lawl, dp->dccps_awh))) {
128 dccp_update_gsr(sk, DCCP_SKB_CB(skb)->dccpd_seq);
130 if (dh->dccph_type != DCCP_PKT_SYNC &&
131 (DCCP_SKB_CB(skb)->dccpd_ack_seq !=
132 DCCP_PKT_WITHOUT_ACK_SEQ))
133 dp->dccps_gar = DCCP_SKB_CB(skb)->dccpd_ack_seq;
135 dccp_pr_debug("Step 6 failed, sending SYNC...\n");
136 dccp_send_sync(sk, DCCP_SKB_CB(skb)->dccpd_seq);
143 int dccp_rcv_established(struct sock *sk, struct sk_buff *skb,
144 const struct dccp_hdr *dh, const unsigned len)
146 struct dccp_sock *dp = dccp_sk(sk);
148 if (dccp_check_seqno(sk, skb))
151 if (dccp_parse_options(sk, skb))
154 if (DCCP_SKB_CB(skb)->dccpd_ack_seq != DCCP_PKT_WITHOUT_ACK_SEQ)
155 dccp_event_ack_recv(sk, skb);
158 * FIXME: check ECN to see if we should use
159 * DCCP_ACKPKTS_STATE_ECN_MARKED
161 if (dp->dccps_options.dccpo_send_ack_vector) {
162 struct dccp_ackpkts *ap = dp->dccps_hc_rx_ackpkts;
164 if (dccp_ackpkts_add(dp->dccps_hc_rx_ackpkts,
165 DCCP_SKB_CB(skb)->dccpd_seq,
166 DCCP_ACKPKTS_STATE_RECEIVED)) {
167 LIMIT_NETDEBUG(KERN_INFO "DCCP: acknowledgeable "
168 "packets buffer full!\n");
169 ap->dccpap_ack_seqno = DCCP_MAX_SEQNO + 1;
170 inet_csk_schedule_ack(sk);
171 inet_csk_reset_xmit_timer(sk, ICSK_TIME_DACK,
178 * FIXME: this activation is probably wrong, have to study more
179 * TCP delack machinery and how it fits into DCCP draft, but
180 * for now it kinda "works" 8)
182 if (!inet_csk_ack_scheduled(sk)) {
183 inet_csk_schedule_ack(sk);
184 inet_csk_reset_xmit_timer(sk, ICSK_TIME_DACK, 5 * HZ,
189 ccid_hc_rx_packet_recv(dp->dccps_hc_rx_ccid, sk, skb);
190 ccid_hc_tx_packet_recv(dp->dccps_hc_tx_ccid, sk, skb);
192 switch (dccp_hdr(skb)->dccph_type) {
193 case DCCP_PKT_DATAACK:
196 * FIXME: check if sk_receive_queue is full, schedule DATA_DROPPED
199 __skb_pull(skb, dh->dccph_doff * 4);
200 __skb_queue_tail(&sk->sk_receive_queue, skb);
201 skb_set_owner_r(skb, sk);
202 sk->sk_data_ready(sk, 0);
208 * Step 9: Process Reset
209 * If P.type == Reset,
210 * Tear down connection
211 * S.state := TIMEWAIT
213 * Drop packet and return
216 dccp_time_wait(sk, DCCP_TIME_WAIT, 0);
218 case DCCP_PKT_CLOSEREQ:
219 dccp_rcv_closereq(sk, skb);
222 dccp_rcv_close(sk, skb);
224 case DCCP_PKT_REQUEST:
226 * or (S.is_server and P.type == Response)
227 * or (S.is_client and P.type == Request)
228 * or (S.state >= OPEN and P.type == Request
229 * and P.seqno >= S.OSR)
230 * or (S.state >= OPEN and P.type == Response
231 * and P.seqno >= S.OSR)
232 * or (S.state == RESPOND and P.type == Data),
233 * Send Sync packet acknowledging P.seqno
234 * Drop packet and return
236 if (dp->dccps_role != DCCP_ROLE_LISTEN)
239 case DCCP_PKT_RESPONSE:
240 if (dp->dccps_role != DCCP_ROLE_CLIENT)
243 if (!before48(DCCP_SKB_CB(skb)->dccpd_seq, dp->dccps_osr)) {
245 dccp_send_sync(sk, DCCP_SKB_CB(skb)->dccpd_seq);
250 DCCP_INC_STATS_BH(DCCP_MIB_INERRS);
256 static int dccp_rcv_request_sent_state_process(struct sock *sk,
258 const struct dccp_hdr *dh,
262 * Step 4: Prepare sequence numbers in REQUEST
263 * If S.state == REQUEST,
264 * If (P.type == Response or P.type == Reset)
265 * and S.AWL <= P.ackno <= S.AWH,
266 * / * Set sequence number variables corresponding to the
267 * other endpoint, so P will pass the tests in Step 6 * /
268 * Set S.GSR, S.ISR, S.SWL, S.SWH
269 * / * Response processing continues in Step 10; Reset
270 * processing continues in Step 9 * /
272 if (dh->dccph_type == DCCP_PKT_RESPONSE) {
273 const struct inet_connection_sock *icsk = inet_csk(sk);
274 struct dccp_sock *dp = dccp_sk(sk);
276 /* Stop the REQUEST timer */
277 inet_csk_clear_xmit_timer(sk, ICSK_TIME_RETRANS);
278 BUG_TRAP(sk->sk_send_head != NULL);
279 __kfree_skb(sk->sk_send_head);
280 sk->sk_send_head = NULL;
282 if (!between48(DCCP_SKB_CB(skb)->dccpd_ack_seq,
283 dp->dccps_awl, dp->dccps_awh)) {
284 dccp_pr_debug("invalid ackno: S.AWL=%llu, "
285 "P.ackno=%llu, S.AWH=%llu \n",
286 (unsigned long long)dp->dccps_awl,
287 (unsigned long long)DCCP_SKB_CB(skb)->dccpd_ack_seq,
288 (unsigned long long)dp->dccps_awh);
289 goto out_invalid_packet;
292 dp->dccps_isr = DCCP_SKB_CB(skb)->dccpd_seq;
293 dccp_update_gsr(sk, DCCP_SKB_CB(skb)->dccpd_seq);
295 if (ccid_hc_rx_init(dp->dccps_hc_rx_ccid, sk) != 0 ||
296 ccid_hc_tx_init(dp->dccps_hc_tx_ccid, sk) != 0) {
297 ccid_hc_rx_exit(dp->dccps_hc_rx_ccid, sk);
298 ccid_hc_tx_exit(dp->dccps_hc_tx_ccid, sk);
299 /* FIXME: send appropriate RESET code */
300 goto out_invalid_packet;
303 dccp_sync_mss(sk, dp->dccps_pmtu_cookie);
306 * Step 10: Process REQUEST state (second part)
307 * If S.state == REQUEST,
308 * / * If we get here, P is a valid Response from the
309 * server (see Step 4), and we should move to
310 * PARTOPEN state. PARTOPEN means send an Ack,
311 * don't send Data packets, retransmit Acks
312 * periodically, and always include any Init Cookie
313 * from the Response * /
314 * S.state := PARTOPEN
316 * Continue with S.state == PARTOPEN
317 * / * Step 12 will send the Ack completing the
318 * three-way handshake * /
320 dccp_set_state(sk, DCCP_PARTOPEN);
322 /* Make sure socket is routed, for correct metrics. */
323 inet_sk_rebuild_header(sk);
325 if (!sock_flag(sk, SOCK_DEAD)) {
326 sk->sk_state_change(sk);
327 sk_wake_async(sk, 0, POLL_OUT);
330 if (sk->sk_write_pending || icsk->icsk_ack.pingpong ||
331 icsk->icsk_accept_queue.rskq_defer_accept) {
332 /* Save one ACK. Data will be ready after
333 * several ticks, if write_pending is set.
335 * It may be deleted, but with this feature tcpdumps
336 * look so _wonderfully_ clever, that I was not able
337 * to stand against the temptation 8) --ANK
340 * OK, in DCCP we can as well do a similar trick, its
341 * even in the draft, but there is no need for us to
342 * schedule an ack here, as dccp_sendmsg does this for
343 * us, also stated in the draft. -acme
353 return 1; /* dccp_v4_do_rcv will send a reset, but...
354 FIXME: the reset code should be
355 DCCP_RESET_CODE_PACKET_ERROR */
358 static int dccp_rcv_respond_partopen_state_process(struct sock *sk,
360 const struct dccp_hdr *dh,
365 switch (dh->dccph_type) {
367 inet_csk_clear_xmit_timer(sk, ICSK_TIME_DACK);
369 case DCCP_PKT_DATAACK:
372 * FIXME: we should be reseting the PARTOPEN (DELACK) timer
373 * here but only if we haven't used the DELACK timer for
374 * something else, like sending a delayed ack for a TIMESTAMP
375 * echo, etc, for now were not clearing it, sending an extra
376 * ACK when there is nothing else to do in DELACK is not a big
380 /* Stop the PARTOPEN timer */
381 if (sk->sk_state == DCCP_PARTOPEN)
382 inet_csk_clear_xmit_timer(sk, ICSK_TIME_DACK);
384 dccp_sk(sk)->dccps_osr = DCCP_SKB_CB(skb)->dccpd_seq;
385 dccp_set_state(sk, DCCP_OPEN);
387 if (dh->dccph_type == DCCP_PKT_DATAACK) {
388 dccp_rcv_established(sk, skb, dh, len);
389 queued = 1; /* packet was queued
390 (by dccp_rcv_established) */
398 int dccp_rcv_state_process(struct sock *sk, struct sk_buff *skb,
399 struct dccp_hdr *dh, unsigned len)
401 struct dccp_sock *dp = dccp_sk(sk);
402 const int old_state = sk->sk_state;
406 * Step 3: Process LISTEN state
407 * (Continuing from dccp_v4_do_rcv and dccp_v6_do_rcv)
409 * If S.state == LISTEN,
410 * If P.type == Request or P contains a valid Init Cookie
412 * * Must scan the packet's options to check for an Init
413 * Cookie. Only the Init Cookie is processed here,
414 * however; other options are processed in Step 8. This
415 * scan need only be performed if the endpoint uses Init
417 * * Generate a new socket and switch to that socket *
418 * Set S := new socket for this port pair
420 * Choose S.ISS (initial seqno) or set from Init Cookie
421 * Set S.ISR, S.GSR, S.SWL, S.SWH from packet or Init Cookie
422 * Continue with S.state == RESPOND
423 * * A Response packet will be generated in Step 11 *
425 * Generate Reset(No Connection) unless P.type == Reset
426 * Drop packet and return
428 * NOTE: the check for the packet types is done in
429 * dccp_rcv_state_process
431 if (sk->sk_state == DCCP_LISTEN) {
432 if (dh->dccph_type == DCCP_PKT_REQUEST) {
433 if (dccp_v4_conn_request(sk, skb) < 0)
436 /* FIXME: do congestion control initialization */
439 if (dh->dccph_type == DCCP_PKT_RESET)
442 /* Caller (dccp_v4_do_rcv) will send Reset(No Connection)*/
446 if (sk->sk_state != DCCP_REQUESTING) {
447 if (dccp_check_seqno(sk, skb))
451 * Step 8: Process options and mark acknowledgeable
453 if (dccp_parse_options(sk, skb))
456 if (DCCP_SKB_CB(skb)->dccpd_ack_seq !=
457 DCCP_PKT_WITHOUT_ACK_SEQ)
458 dccp_event_ack_recv(sk, skb);
460 ccid_hc_rx_packet_recv(dp->dccps_hc_rx_ccid, sk, skb);
461 ccid_hc_tx_packet_recv(dp->dccps_hc_tx_ccid, sk, skb);
464 * FIXME: check ECN to see if we should use
465 * DCCP_ACKPKTS_STATE_ECN_MARKED
467 if (dp->dccps_options.dccpo_send_ack_vector) {
468 if (dccp_ackpkts_add(dp->dccps_hc_rx_ackpkts,
469 DCCP_SKB_CB(skb)->dccpd_seq,
470 DCCP_ACKPKTS_STATE_RECEIVED))
473 * FIXME: this activation is probably wrong, have to
474 * study more TCP delack machinery and how it fits into
475 * DCCP draft, but for now it kinda "works" 8)
477 if ((dp->dccps_hc_rx_ackpkts->dccpap_ack_seqno ==
478 DCCP_MAX_SEQNO + 1) &&
479 !inet_csk_ack_scheduled(sk)) {
480 inet_csk_schedule_ack(sk);
481 inet_csk_reset_xmit_timer(sk, ICSK_TIME_DACK,
489 * Step 9: Process Reset
490 * If P.type == Reset,
491 * Tear down connection
492 * S.state := TIMEWAIT
494 * Drop packet and return
496 if (dh->dccph_type == DCCP_PKT_RESET) {
498 * Queue the equivalent of TCP fin so that dccp_recvmsg
502 dccp_time_wait(sk, DCCP_TIME_WAIT, 0);
505 * Step 7: Check for unexpected packet types
506 * If (S.is_server and P.type == CloseReq)
507 * or (S.is_server and P.type == Response)
508 * or (S.is_client and P.type == Request)
509 * or (S.state == RESPOND and P.type == Data),
510 * Send Sync packet acknowledging P.seqno
511 * Drop packet and return
513 } else if ((dp->dccps_role != DCCP_ROLE_CLIENT &&
514 (dh->dccph_type == DCCP_PKT_RESPONSE ||
515 dh->dccph_type == DCCP_PKT_CLOSEREQ)) ||
516 (dp->dccps_role == DCCP_ROLE_CLIENT &&
517 dh->dccph_type == DCCP_PKT_REQUEST) ||
518 (sk->sk_state == DCCP_RESPOND &&
519 dh->dccph_type == DCCP_PKT_DATA)) {
520 dccp_send_sync(sk, DCCP_SKB_CB(skb)->dccpd_seq);
524 switch (sk->sk_state) {
528 case DCCP_REQUESTING:
529 /* FIXME: do congestion control initialization */
531 queued = dccp_rcv_request_sent_state_process(sk, skb, dh, len);
540 queued = dccp_rcv_respond_partopen_state_process(sk, skb,
545 if (dh->dccph_type == DCCP_PKT_ACK ||
546 dh->dccph_type == DCCP_PKT_DATAACK) {
549 sk->sk_state_change(sk);
550 sk_wake_async(sk, 0, POLL_OUT);