xref: /openbmc/linux/net/dccp/input.c (revision d5cb9783536a41df9f9cba5b0a1d78047ed787f7)
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/config.h>
14 #include <linux/dccp.h>
15 #include <linux/skbuff.h>
16 
17 #include <net/sock.h>
18 
19 #include "ackvec.h"
20 #include "ccid.h"
21 #include "dccp.h"
22 
23 static void dccp_fin(struct sock *sk, struct sk_buff *skb)
24 {
25 	sk->sk_shutdown |= RCV_SHUTDOWN;
26 	sock_set_flag(sk, SOCK_DONE);
27 	__skb_pull(skb, dccp_hdr(skb)->dccph_doff * 4);
28 	__skb_queue_tail(&sk->sk_receive_queue, skb);
29 	skb_set_owner_r(skb, sk);
30 	sk->sk_data_ready(sk, 0);
31 }
32 
33 static void dccp_rcv_close(struct sock *sk, struct sk_buff *skb)
34 {
35 	dccp_v4_send_reset(sk, DCCP_RESET_CODE_CLOSED);
36 	dccp_fin(sk, skb);
37 	dccp_set_state(sk, DCCP_CLOSED);
38 	sk_wake_async(sk, 1, POLL_HUP);
39 }
40 
41 static void dccp_rcv_closereq(struct sock *sk, struct sk_buff *skb)
42 {
43 	/*
44 	 *   Step 7: Check for unexpected packet types
45 	 *      If (S.is_server and P.type == CloseReq)
46 	 *	  Send Sync packet acknowledging P.seqno
47 	 *	  Drop packet and return
48 	 */
49 	if (dccp_sk(sk)->dccps_role != DCCP_ROLE_CLIENT) {
50 		dccp_send_sync(sk, DCCP_SKB_CB(skb)->dccpd_seq, DCCP_PKT_SYNC);
51 		return;
52 	}
53 
54 	if (sk->sk_state != DCCP_CLOSING)
55 		dccp_set_state(sk, DCCP_CLOSING);
56 	dccp_send_close(sk, 0);
57 }
58 
59 static inline void dccp_event_ack_recv(struct sock *sk, struct sk_buff *skb)
60 {
61 	struct dccp_sock *dp = dccp_sk(sk);
62 
63 	if (dp->dccps_options.dccpo_send_ack_vector)
64 		dccp_ackvec_check_rcv_ackno(dp->dccps_hc_rx_ackvec, sk,
65 					    DCCP_SKB_CB(skb)->dccpd_ack_seq);
66 }
67 
68 static int dccp_check_seqno(struct sock *sk, struct sk_buff *skb)
69 {
70 	const struct dccp_hdr *dh = dccp_hdr(skb);
71 	struct dccp_sock *dp = dccp_sk(sk);
72 	u64 lswl, lawl;
73 
74 	/*
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
81 	 *		 Step 15 * /
82 	 *	     Update S.GSR, S.SWL, S.SWH
83 	 *	  Otherwise,
84 	 *	     Drop packet and return
85 	 */
86 	if (dh->dccph_type == DCCP_PKT_SYNC ||
87 	    dh->dccph_type == DCCP_PKT_SYNCACK) {
88 		if (between48(DCCP_SKB_CB(skb)->dccpd_ack_seq,
89 			      dp->dccps_awl, dp->dccps_awh) &&
90 		    !before48(DCCP_SKB_CB(skb)->dccpd_seq, dp->dccps_swl))
91 			dccp_update_gsr(sk, DCCP_SKB_CB(skb)->dccpd_seq);
92 		else
93 			return -1;
94 	}
95 
96 	/*
97 	 *   Step 6: Check sequence numbers
98 	 *      Let LSWL = S.SWL and LAWL = S.AWL
99 	 *      If P.type == CloseReq or P.type == Close or P.type == Reset,
100 	 *	  LSWL := S.GSR + 1, LAWL := S.GAR
101 	 *      If LSWL <= P.seqno <= S.SWH
102 	 *	     and (P.ackno does not exist or LAWL <= P.ackno <= S.AWH),
103 	 *	  Update S.GSR, S.SWL, S.SWH
104 	 *	  If P.type != Sync,
105 	 *	     Update S.GAR
106 	 *      Otherwise,
107 	 *	  Send Sync packet acknowledging P.seqno
108 	 *	  Drop packet and return
109 	 */
110 	lswl = dp->dccps_swl;
111 	lawl = dp->dccps_awl;
112 
113 	if (dh->dccph_type == DCCP_PKT_CLOSEREQ ||
114 	    dh->dccph_type == DCCP_PKT_CLOSE ||
115 	    dh->dccph_type == DCCP_PKT_RESET) {
116 		lswl = dp->dccps_gsr;
117 		dccp_inc_seqno(&lswl);
118 		lawl = dp->dccps_gar;
119 	}
120 
121 	if (between48(DCCP_SKB_CB(skb)->dccpd_seq, lswl, dp->dccps_swh) &&
122 	    (DCCP_SKB_CB(skb)->dccpd_ack_seq == DCCP_PKT_WITHOUT_ACK_SEQ ||
123 	     between48(DCCP_SKB_CB(skb)->dccpd_ack_seq,
124 		       lawl, dp->dccps_awh))) {
125 		dccp_update_gsr(sk, DCCP_SKB_CB(skb)->dccpd_seq);
126 
127 		if (dh->dccph_type != DCCP_PKT_SYNC &&
128 		    (DCCP_SKB_CB(skb)->dccpd_ack_seq !=
129 		     DCCP_PKT_WITHOUT_ACK_SEQ))
130 			dp->dccps_gar = DCCP_SKB_CB(skb)->dccpd_ack_seq;
131 	} else {
132 		LIMIT_NETDEBUG(KERN_WARNING "DCCP: Step 6 failed for %s packet, "
133 					    "(LSWL(%llu) <= P.seqno(%llu) <= S.SWH(%llu)) and "
134 					    "(P.ackno %s or LAWL(%llu) <= P.ackno(%llu) <= S.AWH(%llu), "
135 					    "sending SYNC...\n",
136 			       dccp_packet_name(dh->dccph_type),
137 			       (unsigned long long) lswl,
138 			       (unsigned long long)
139 			       DCCP_SKB_CB(skb)->dccpd_seq,
140 			       (unsigned long long) dp->dccps_swh,
141 			       (DCCP_SKB_CB(skb)->dccpd_ack_seq ==
142 			        DCCP_PKT_WITHOUT_ACK_SEQ) ? "doesn't exist" : "exists",
143 			       (unsigned long long) lawl,
144 			       (unsigned long long)
145 			       DCCP_SKB_CB(skb)->dccpd_ack_seq,
146 			       (unsigned long long) dp->dccps_awh);
147 		dccp_send_sync(sk, DCCP_SKB_CB(skb)->dccpd_seq, DCCP_PKT_SYNC);
148 		return -1;
149 	}
150 
151 	return 0;
152 }
153 
154 int dccp_rcv_established(struct sock *sk, struct sk_buff *skb,
155 			 const struct dccp_hdr *dh, const unsigned len)
156 {
157 	struct dccp_sock *dp = dccp_sk(sk);
158 
159 	if (dccp_check_seqno(sk, skb))
160 		goto discard;
161 
162 	if (dccp_parse_options(sk, skb))
163 		goto discard;
164 
165 	if (DCCP_SKB_CB(skb)->dccpd_ack_seq != DCCP_PKT_WITHOUT_ACK_SEQ)
166 		dccp_event_ack_recv(sk, skb);
167 
168 	if (dp->dccps_options.dccpo_send_ack_vector &&
169 	    dccp_ackvec_add(dp->dccps_hc_rx_ackvec, sk,
170 			    DCCP_SKB_CB(skb)->dccpd_seq,
171 			    DCCP_ACKVEC_STATE_RECEIVED))
172 		goto discard;
173 
174 	ccid_hc_rx_packet_recv(dp->dccps_hc_rx_ccid, sk, skb);
175 	ccid_hc_tx_packet_recv(dp->dccps_hc_tx_ccid, sk, skb);
176 
177 	switch (dccp_hdr(skb)->dccph_type) {
178 	case DCCP_PKT_DATAACK:
179 	case DCCP_PKT_DATA:
180 		/*
181 		 * FIXME: check if sk_receive_queue is full, schedule DATA_DROPPED
182 		 * option if it is.
183 		 */
184 		__skb_pull(skb, dh->dccph_doff * 4);
185 		__skb_queue_tail(&sk->sk_receive_queue, skb);
186 		skb_set_owner_r(skb, sk);
187 		sk->sk_data_ready(sk, 0);
188 		return 0;
189 	case DCCP_PKT_ACK:
190 		goto discard;
191 	case DCCP_PKT_RESET:
192 		/*
193 		 *  Step 9: Process Reset
194 		 *	If P.type == Reset,
195 		 *		Tear down connection
196 		 *		S.state := TIMEWAIT
197 		 *		Set TIMEWAIT timer
198 		 *		Drop packet and return
199 		*/
200 		dccp_fin(sk, skb);
201 		dccp_time_wait(sk, DCCP_TIME_WAIT, 0);
202 		return 0;
203 	case DCCP_PKT_CLOSEREQ:
204 		dccp_rcv_closereq(sk, skb);
205 		goto discard;
206 	case DCCP_PKT_CLOSE:
207 		dccp_rcv_close(sk, skb);
208 		return 0;
209 	case DCCP_PKT_REQUEST:
210 		/* Step 7
211             	 *   or (S.is_server and P.type == Response)
212 		 *   or (S.is_client and P.type == Request)
213 		 *   or (S.state >= OPEN and P.type == Request
214 		 *	and P.seqno >= S.OSR)
215 		 *    or (S.state >= OPEN and P.type == Response
216 		 *	and P.seqno >= S.OSR)
217 		 *    or (S.state == RESPOND and P.type == Data),
218 		 *  Send Sync packet acknowledging P.seqno
219 		 *  Drop packet and return
220 		 */
221 		if (dp->dccps_role != DCCP_ROLE_LISTEN)
222 			goto send_sync;
223 		goto check_seq;
224 	case DCCP_PKT_RESPONSE:
225 		if (dp->dccps_role != DCCP_ROLE_CLIENT)
226 			goto send_sync;
227 check_seq:
228 		if (!before48(DCCP_SKB_CB(skb)->dccpd_seq, dp->dccps_osr)) {
229 send_sync:
230 			dccp_send_sync(sk, DCCP_SKB_CB(skb)->dccpd_seq,
231 				       DCCP_PKT_SYNC);
232 		}
233 		break;
234 	case DCCP_PKT_SYNC:
235 		dccp_send_sync(sk, DCCP_SKB_CB(skb)->dccpd_seq,
236 			       DCCP_PKT_SYNCACK);
237 		/*
238 		 * From the draft:
239 		 *
240 		 * As with DCCP-Ack packets, DCCP-Sync and DCCP-SyncAck packets
241 		 * MAY have non-zero-length application data areas, whose
242 		 * contents * receivers MUST ignore.
243 		 */
244 		goto discard;
245 	}
246 
247 	DCCP_INC_STATS_BH(DCCP_MIB_INERRS);
248 discard:
249 	__kfree_skb(skb);
250 	return 0;
251 }
252 
253 static int dccp_rcv_request_sent_state_process(struct sock *sk,
254 					       struct sk_buff *skb,
255 					       const struct dccp_hdr *dh,
256 					       const unsigned len)
257 {
258 	/*
259 	 *  Step 4: Prepare sequence numbers in REQUEST
260 	 *     If S.state == REQUEST,
261 	 *	  If (P.type == Response or P.type == Reset)
262 	 *		and S.AWL <= P.ackno <= S.AWH,
263 	 *	     / * Set sequence number variables corresponding to the
264 	 *		other endpoint, so P will pass the tests in Step 6 * /
265 	 *	     Set S.GSR, S.ISR, S.SWL, S.SWH
266 	 *	     / * Response processing continues in Step 10; Reset
267 	 *		processing continues in Step 9 * /
268 	*/
269 	if (dh->dccph_type == DCCP_PKT_RESPONSE) {
270 		const struct inet_connection_sock *icsk = inet_csk(sk);
271 		struct dccp_sock *dp = dccp_sk(sk);
272 
273 		/* Stop the REQUEST timer */
274 		inet_csk_clear_xmit_timer(sk, ICSK_TIME_RETRANS);
275 		BUG_TRAP(sk->sk_send_head != NULL);
276 		__kfree_skb(sk->sk_send_head);
277 		sk->sk_send_head = NULL;
278 
279 		if (!between48(DCCP_SKB_CB(skb)->dccpd_ack_seq,
280 			       dp->dccps_awl, dp->dccps_awh)) {
281 			dccp_pr_debug("invalid ackno: S.AWL=%llu, "
282 				      "P.ackno=%llu, S.AWH=%llu \n",
283 				      (unsigned long long)dp->dccps_awl,
284 			   (unsigned long long)DCCP_SKB_CB(skb)->dccpd_ack_seq,
285 				      (unsigned long long)dp->dccps_awh);
286 			goto out_invalid_packet;
287 		}
288 
289 		dp->dccps_isr = DCCP_SKB_CB(skb)->dccpd_seq;
290 		dccp_update_gsr(sk, dp->dccps_isr);
291 		/*
292 		 * SWL and AWL are initially adjusted so that they are not less than
293 		 * the initial Sequence Numbers received and sent, respectively:
294 		 *	SWL := max(GSR + 1 - floor(W/4), ISR),
295 		 *	AWL := max(GSS - W' + 1, ISS).
296 		 * These adjustments MUST be applied only at the beginning of the
297 		 * connection.
298 		 *
299 		 * AWL was adjusted in dccp_v4_connect -acme
300 		 */
301 		dccp_set_seqno(&dp->dccps_swl,
302 			       max48(dp->dccps_swl, dp->dccps_isr));
303 
304 		if (ccid_hc_rx_init(dp->dccps_hc_rx_ccid, sk) != 0 ||
305 		    ccid_hc_tx_init(dp->dccps_hc_tx_ccid, sk) != 0) {
306 			ccid_hc_rx_exit(dp->dccps_hc_rx_ccid, sk);
307 			ccid_hc_tx_exit(dp->dccps_hc_tx_ccid, sk);
308 			/* FIXME: send appropriate RESET code */
309 			goto out_invalid_packet;
310 		}
311 
312 		dccp_sync_mss(sk, dp->dccps_pmtu_cookie);
313 
314 		/*
315 		 *    Step 10: Process REQUEST state (second part)
316 		 *       If S.state == REQUEST,
317 		 *	  / * If we get here, P is a valid Response from the
318 		 *	      server (see Step 4), and we should move to
319 		 *	      PARTOPEN state. PARTOPEN means send an Ack,
320 		 *	      don't send Data packets, retransmit Acks
321 		 *	      periodically, and always include any Init Cookie
322 		 *	      from the Response * /
323 		 *	  S.state := PARTOPEN
324 		 *	  Set PARTOPEN timer
325 		 * 	  Continue with S.state == PARTOPEN
326 		 *	  / * Step 12 will send the Ack completing the
327 		 *	      three-way handshake * /
328 		 */
329 		dccp_set_state(sk, DCCP_PARTOPEN);
330 
331 		/* Make sure socket is routed, for correct metrics. */
332 		inet_sk_rebuild_header(sk);
333 
334 		if (!sock_flag(sk, SOCK_DEAD)) {
335 			sk->sk_state_change(sk);
336 			sk_wake_async(sk, 0, POLL_OUT);
337 		}
338 
339 		if (sk->sk_write_pending || icsk->icsk_ack.pingpong ||
340 		    icsk->icsk_accept_queue.rskq_defer_accept) {
341 			/* Save one ACK. Data will be ready after
342 			 * several ticks, if write_pending is set.
343 			 *
344 			 * It may be deleted, but with this feature tcpdumps
345 			 * look so _wonderfully_ clever, that I was not able
346 			 * to stand against the temptation 8)     --ANK
347 			 */
348 			/*
349 			 * OK, in DCCP we can as well do a similar trick, its
350 			 * even in the draft, but there is no need for us to
351 			 * schedule an ack here, as dccp_sendmsg does this for
352 			 * us, also stated in the draft. -acme
353 			 */
354 			__kfree_skb(skb);
355 			return 0;
356 		}
357 		dccp_send_ack(sk);
358 		return -1;
359 	}
360 
361 out_invalid_packet:
362 	/* dccp_v4_do_rcv will send a reset */
363 	DCCP_SKB_CB(skb)->dccpd_reset_code = DCCP_RESET_CODE_PACKET_ERROR;
364 	return 1;
365 }
366 
367 static int dccp_rcv_respond_partopen_state_process(struct sock *sk,
368 						   struct sk_buff *skb,
369 						   const struct dccp_hdr *dh,
370 						   const unsigned len)
371 {
372 	int queued = 0;
373 
374 	switch (dh->dccph_type) {
375 	case DCCP_PKT_RESET:
376 		inet_csk_clear_xmit_timer(sk, ICSK_TIME_DACK);
377 		break;
378 	case DCCP_PKT_DATA:
379 		if (sk->sk_state == DCCP_RESPOND)
380 			break;
381 	case DCCP_PKT_DATAACK:
382 	case DCCP_PKT_ACK:
383 		/*
384 		 * FIXME: we should be reseting the PARTOPEN (DELACK) timer
385 		 * here but only if we haven't used the DELACK timer for
386 		 * something else, like sending a delayed ack for a TIMESTAMP
387 		 * echo, etc, for now were not clearing it, sending an extra
388 		 * ACK when there is nothing else to do in DELACK is not a big
389 		 * deal after all.
390 		 */
391 
392 		/* Stop the PARTOPEN timer */
393 		if (sk->sk_state == DCCP_PARTOPEN)
394 			inet_csk_clear_xmit_timer(sk, ICSK_TIME_DACK);
395 
396 		dccp_sk(sk)->dccps_osr = DCCP_SKB_CB(skb)->dccpd_seq;
397 		dccp_set_state(sk, DCCP_OPEN);
398 
399 		if (dh->dccph_type == DCCP_PKT_DATAACK ||
400 		    dh->dccph_type == DCCP_PKT_DATA) {
401 			dccp_rcv_established(sk, skb, dh, len);
402 			queued = 1; /* packet was queued
403 				       (by dccp_rcv_established) */
404 		}
405 		break;
406 	}
407 
408 	return queued;
409 }
410 
411 int dccp_rcv_state_process(struct sock *sk, struct sk_buff *skb,
412 			   struct dccp_hdr *dh, unsigned len)
413 {
414 	struct dccp_sock *dp = dccp_sk(sk);
415 	struct dccp_skb_cb *dcb = DCCP_SKB_CB(skb);
416 	const int old_state = sk->sk_state;
417 	int queued = 0;
418 
419 	/*
420 	 *  Step 3: Process LISTEN state
421 	 *  	(Continuing from dccp_v4_do_rcv and dccp_v6_do_rcv)
422 	 *
423 	 *     If S.state == LISTEN,
424 	 *	  If P.type == Request or P contains a valid Init Cookie
425 	 *	  	option,
426 	 *	     * Must scan the packet's options to check for an Init
427 	 *		Cookie.  Only the Init Cookie is processed here,
428 	 *		however; other options are processed in Step 8.  This
429 	 *		scan need only be performed if the endpoint uses Init
430 	 *		Cookies *
431 	 *	     * Generate a new socket and switch to that socket *
432 	 *	     Set S := new socket for this port pair
433 	 *	     S.state = RESPOND
434 	 *	     Choose S.ISS (initial seqno) or set from Init Cookie
435 	 *	     Set S.ISR, S.GSR, S.SWL, S.SWH from packet or Init Cookie
436 	 *	     Continue with S.state == RESPOND
437 	 *	     * A Response packet will be generated in Step 11 *
438 	 *	  Otherwise,
439 	 *	     Generate Reset(No Connection) unless P.type == Reset
440 	 *	     Drop packet and return
441 	 *
442 	 * NOTE: the check for the packet types is done in
443 	 *	 dccp_rcv_state_process
444 	 */
445 	if (sk->sk_state == DCCP_LISTEN) {
446 		if (dh->dccph_type == DCCP_PKT_REQUEST) {
447 			if (dccp_v4_conn_request(sk, skb) < 0)
448 				return 1;
449 
450 			/* FIXME: do congestion control initialization */
451 			goto discard;
452 		}
453 		if (dh->dccph_type == DCCP_PKT_RESET)
454 			goto discard;
455 
456 		/* Caller (dccp_v4_do_rcv) will send Reset */
457 		dcb->dccpd_reset_code = DCCP_RESET_CODE_NO_CONNECTION;
458 		return 1;
459 	}
460 
461 	if (sk->sk_state != DCCP_REQUESTING) {
462 		if (dccp_check_seqno(sk, skb))
463 			goto discard;
464 
465 		/*
466 		 * Step 8: Process options and mark acknowledgeable
467 		 */
468 		if (dccp_parse_options(sk, skb))
469 			goto discard;
470 
471 		if (dcb->dccpd_ack_seq != DCCP_PKT_WITHOUT_ACK_SEQ)
472 			dccp_event_ack_recv(sk, skb);
473 
474 		ccid_hc_rx_packet_recv(dp->dccps_hc_rx_ccid, sk, skb);
475 		ccid_hc_tx_packet_recv(dp->dccps_hc_tx_ccid, sk, skb);
476 
477  		if (dp->dccps_options.dccpo_send_ack_vector &&
478 		    dccp_ackvec_add(dp->dccps_hc_rx_ackvec, sk,
479  				    DCCP_SKB_CB(skb)->dccpd_seq,
480  				    DCCP_ACKVEC_STATE_RECEIVED))
481  			goto discard;
482 	}
483 
484 	/*
485 	 *  Step 9: Process Reset
486 	 *	If P.type == Reset,
487 	 *		Tear down connection
488 	 *		S.state := TIMEWAIT
489 	 *		Set TIMEWAIT timer
490 	 *		Drop packet and return
491 	*/
492 	if (dh->dccph_type == DCCP_PKT_RESET) {
493 		/*
494 		 * Queue the equivalent of TCP fin so that dccp_recvmsg
495 		 * exits the loop
496 		 */
497 		dccp_fin(sk, skb);
498 		dccp_time_wait(sk, DCCP_TIME_WAIT, 0);
499 		return 0;
500 		/*
501 		 *   Step 7: Check for unexpected packet types
502 		 *      If (S.is_server and P.type == CloseReq)
503 		 *	    or (S.is_server and P.type == Response)
504 		 *	    or (S.is_client and P.type == Request)
505 		 *	    or (S.state == RESPOND and P.type == Data),
506 		 *	  Send Sync packet acknowledging P.seqno
507 		 *	  Drop packet and return
508 		 */
509 	} else if ((dp->dccps_role != DCCP_ROLE_CLIENT &&
510 		    (dh->dccph_type == DCCP_PKT_RESPONSE ||
511 		     dh->dccph_type == DCCP_PKT_CLOSEREQ)) ||
512 		    (dp->dccps_role == DCCP_ROLE_CLIENT &&
513 		     dh->dccph_type == DCCP_PKT_REQUEST) ||
514 		    (sk->sk_state == DCCP_RESPOND &&
515 		     dh->dccph_type == DCCP_PKT_DATA)) {
516 		dccp_send_sync(sk, dcb->dccpd_seq, DCCP_PKT_SYNC);
517 		goto discard;
518 	} else if (dh->dccph_type == DCCP_PKT_CLOSEREQ) {
519 		dccp_rcv_closereq(sk, skb);
520 		goto discard;
521 	} else if (dh->dccph_type == DCCP_PKT_CLOSE) {
522 		dccp_rcv_close(sk, skb);
523 		return 0;
524 	}
525 
526 	if (unlikely(dh->dccph_type == DCCP_PKT_SYNC)) {
527 		dccp_send_sync(sk, dcb->dccpd_seq, DCCP_PKT_SYNCACK);
528 		goto discard;
529 	}
530 
531 	switch (sk->sk_state) {
532 	case DCCP_CLOSED:
533 		dcb->dccpd_reset_code = DCCP_RESET_CODE_NO_CONNECTION;
534 		return 1;
535 
536 	case DCCP_REQUESTING:
537 		/* FIXME: do congestion control initialization */
538 
539 		queued = dccp_rcv_request_sent_state_process(sk, skb, dh, len);
540 		if (queued >= 0)
541 			return queued;
542 
543 		__kfree_skb(skb);
544 		return 0;
545 
546 	case DCCP_RESPOND:
547 	case DCCP_PARTOPEN:
548 		queued = dccp_rcv_respond_partopen_state_process(sk, skb,
549 								 dh, len);
550 		break;
551 	}
552 
553 	if (dh->dccph_type == DCCP_PKT_ACK ||
554 	    dh->dccph_type == DCCP_PKT_DATAACK) {
555 		switch (old_state) {
556 		case DCCP_PARTOPEN:
557 			sk->sk_state_change(sk);
558 			sk_wake_async(sk, 0, POLL_OUT);
559 			break;
560 		}
561 	}
562 
563 	if (!queued) {
564 discard:
565 		__kfree_skb(skb);
566 	}
567 	return 0;
568 }
569