xref: /openbmc/linux/net/sctp/associola.c (revision 643d1f7f)
1 /* SCTP kernel reference Implementation
2  * (C) Copyright IBM Corp. 2001, 2004
3  * Copyright (c) 1999-2000 Cisco, Inc.
4  * Copyright (c) 1999-2001 Motorola, Inc.
5  * Copyright (c) 2001 Intel Corp.
6  * Copyright (c) 2001 La Monte H.P. Yarroll
7  *
8  * This file is part of the SCTP kernel reference Implementation
9  *
10  * This module provides the abstraction for an SCTP association.
11  *
12  * The SCTP reference implementation is free software;
13  * you can redistribute it and/or modify it under the terms of
14  * the GNU General Public License as published by
15  * the Free Software Foundation; either version 2, or (at your option)
16  * any later version.
17  *
18  * The SCTP reference implementation is distributed in the hope that it
19  * will be useful, but WITHOUT ANY WARRANTY; without even the implied
20  *                 ************************
21  * warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.
22  * See the GNU General Public License for more details.
23  *
24  * You should have received a copy of the GNU General Public License
25  * along with GNU CC; see the file COPYING.  If not, write to
26  * the Free Software Foundation, 59 Temple Place - Suite 330,
27  * Boston, MA 02111-1307, USA.
28  *
29  * Please send any bug reports or fixes you make to the
30  * email address(es):
31  *    lksctp developers <lksctp-developers@lists.sourceforge.net>
32  *
33  * Or submit a bug report through the following website:
34  *    http://www.sf.net/projects/lksctp
35  *
36  * Written or modified by:
37  *    La Monte H.P. Yarroll <piggy@acm.org>
38  *    Karl Knutson          <karl@athena.chicago.il.us>
39  *    Jon Grimm             <jgrimm@us.ibm.com>
40  *    Xingang Guo           <xingang.guo@intel.com>
41  *    Hui Huang             <hui.huang@nokia.com>
42  *    Sridhar Samudrala	    <sri@us.ibm.com>
43  *    Daisy Chang	    <daisyc@us.ibm.com>
44  *    Ryan Layer	    <rmlayer@us.ibm.com>
45  *    Kevin Gao             <kevin.gao@intel.com>
46  *
47  * Any bugs reported given to us we will try to fix... any fixes shared will
48  * be incorporated into the next SCTP release.
49  */
50 
51 #include <linux/types.h>
52 #include <linux/fcntl.h>
53 #include <linux/poll.h>
54 #include <linux/init.h>
55 
56 #include <linux/slab.h>
57 #include <linux/in.h>
58 #include <net/ipv6.h>
59 #include <net/sctp/sctp.h>
60 #include <net/sctp/sm.h>
61 
62 /* Forward declarations for internal functions. */
63 static void sctp_assoc_bh_rcv(struct work_struct *work);
64 static void sctp_assoc_free_asconf_acks(struct sctp_association *asoc);
65 
66 
67 /* 1st Level Abstractions. */
68 
69 /* Initialize a new association from provided memory. */
70 static struct sctp_association *sctp_association_init(struct sctp_association *asoc,
71 					  const struct sctp_endpoint *ep,
72 					  const struct sock *sk,
73 					  sctp_scope_t scope,
74 					  gfp_t gfp)
75 {
76 	struct sctp_sock *sp;
77 	int i;
78 	sctp_paramhdr_t *p;
79 	int err;
80 
81 	/* Retrieve the SCTP per socket area.  */
82 	sp = sctp_sk((struct sock *)sk);
83 
84 	/* Init all variables to a known value.  */
85 	memset(asoc, 0, sizeof(struct sctp_association));
86 
87 	/* Discarding const is appropriate here.  */
88 	asoc->ep = (struct sctp_endpoint *)ep;
89 	sctp_endpoint_hold(asoc->ep);
90 
91 	/* Hold the sock.  */
92 	asoc->base.sk = (struct sock *)sk;
93 	sock_hold(asoc->base.sk);
94 
95 	/* Initialize the common base substructure.  */
96 	asoc->base.type = SCTP_EP_TYPE_ASSOCIATION;
97 
98 	/* Initialize the object handling fields.  */
99 	atomic_set(&asoc->base.refcnt, 1);
100 	asoc->base.dead = 0;
101 	asoc->base.malloced = 0;
102 
103 	/* Initialize the bind addr area.  */
104 	sctp_bind_addr_init(&asoc->base.bind_addr, ep->base.bind_addr.port);
105 
106 	asoc->state = SCTP_STATE_CLOSED;
107 
108 	/* Set these values from the socket values, a conversion between
109 	 * millsecons to seconds/microseconds must also be done.
110 	 */
111 	asoc->cookie_life.tv_sec = sp->assocparams.sasoc_cookie_life / 1000;
112 	asoc->cookie_life.tv_usec = (sp->assocparams.sasoc_cookie_life % 1000)
113 					* 1000;
114 	asoc->frag_point = 0;
115 
116 	/* Set the association max_retrans and RTO values from the
117 	 * socket values.
118 	 */
119 	asoc->max_retrans = sp->assocparams.sasoc_asocmaxrxt;
120 	asoc->rto_initial = msecs_to_jiffies(sp->rtoinfo.srto_initial);
121 	asoc->rto_max = msecs_to_jiffies(sp->rtoinfo.srto_max);
122 	asoc->rto_min = msecs_to_jiffies(sp->rtoinfo.srto_min);
123 
124 	asoc->overall_error_count = 0;
125 
126 	/* Initialize the association's heartbeat interval based on the
127 	 * sock configured value.
128 	 */
129 	asoc->hbinterval = msecs_to_jiffies(sp->hbinterval);
130 
131 	/* Initialize path max retrans value. */
132 	asoc->pathmaxrxt = sp->pathmaxrxt;
133 
134 	/* Initialize default path MTU. */
135 	asoc->pathmtu = sp->pathmtu;
136 
137 	/* Set association default SACK delay */
138 	asoc->sackdelay = msecs_to_jiffies(sp->sackdelay);
139 
140 	/* Set the association default flags controlling
141 	 * Heartbeat, SACK delay, and Path MTU Discovery.
142 	 */
143 	asoc->param_flags = sp->param_flags;
144 
145 	/* Initialize the maximum mumber of new data packets that can be sent
146 	 * in a burst.
147 	 */
148 	asoc->max_burst = sp->max_burst;
149 
150 	/* initialize association timers */
151 	asoc->timeouts[SCTP_EVENT_TIMEOUT_NONE] = 0;
152 	asoc->timeouts[SCTP_EVENT_TIMEOUT_T1_COOKIE] = asoc->rto_initial;
153 	asoc->timeouts[SCTP_EVENT_TIMEOUT_T1_INIT] = asoc->rto_initial;
154 	asoc->timeouts[SCTP_EVENT_TIMEOUT_T2_SHUTDOWN] = asoc->rto_initial;
155 	asoc->timeouts[SCTP_EVENT_TIMEOUT_T3_RTX] = 0;
156 	asoc->timeouts[SCTP_EVENT_TIMEOUT_T4_RTO] = 0;
157 
158 	/* sctpimpguide Section 2.12.2
159 	 * If the 'T5-shutdown-guard' timer is used, it SHOULD be set to the
160 	 * recommended value of 5 times 'RTO.Max'.
161 	 */
162 	asoc->timeouts[SCTP_EVENT_TIMEOUT_T5_SHUTDOWN_GUARD]
163 		= 5 * asoc->rto_max;
164 
165 	asoc->timeouts[SCTP_EVENT_TIMEOUT_HEARTBEAT] = 0;
166 	asoc->timeouts[SCTP_EVENT_TIMEOUT_SACK] = asoc->sackdelay;
167 	asoc->timeouts[SCTP_EVENT_TIMEOUT_AUTOCLOSE] =
168 		sp->autoclose * HZ;
169 
170 	/* Initilizes the timers */
171 	for (i = SCTP_EVENT_TIMEOUT_NONE; i < SCTP_NUM_TIMEOUT_TYPES; ++i)
172 		setup_timer(&asoc->timers[i], sctp_timer_events[i],
173 				(unsigned long)asoc);
174 
175 	/* Pull default initialization values from the sock options.
176 	 * Note: This assumes that the values have already been
177 	 * validated in the sock.
178 	 */
179 	asoc->c.sinit_max_instreams = sp->initmsg.sinit_max_instreams;
180 	asoc->c.sinit_num_ostreams  = sp->initmsg.sinit_num_ostreams;
181 	asoc->max_init_attempts	= sp->initmsg.sinit_max_attempts;
182 
183 	asoc->max_init_timeo =
184 		 msecs_to_jiffies(sp->initmsg.sinit_max_init_timeo);
185 
186 	/* Allocate storage for the ssnmap after the inbound and outbound
187 	 * streams have been negotiated during Init.
188 	 */
189 	asoc->ssnmap = NULL;
190 
191 	/* Set the local window size for receive.
192 	 * This is also the rcvbuf space per association.
193 	 * RFC 6 - A SCTP receiver MUST be able to receive a minimum of
194 	 * 1500 bytes in one SCTP packet.
195 	 */
196 	if ((sk->sk_rcvbuf/2) < SCTP_DEFAULT_MINWINDOW)
197 		asoc->rwnd = SCTP_DEFAULT_MINWINDOW;
198 	else
199 		asoc->rwnd = sk->sk_rcvbuf/2;
200 
201 	asoc->a_rwnd = asoc->rwnd;
202 
203 	asoc->rwnd_over = 0;
204 
205 	/* Use my own max window until I learn something better.  */
206 	asoc->peer.rwnd = SCTP_DEFAULT_MAXWINDOW;
207 
208 	/* Set the sndbuf size for transmit.  */
209 	asoc->sndbuf_used = 0;
210 
211 	/* Initialize the receive memory counter */
212 	atomic_set(&asoc->rmem_alloc, 0);
213 
214 	init_waitqueue_head(&asoc->wait);
215 
216 	asoc->c.my_vtag = sctp_generate_tag(ep);
217 	asoc->peer.i.init_tag = 0;     /* INIT needs a vtag of 0. */
218 	asoc->c.peer_vtag = 0;
219 	asoc->c.my_ttag   = 0;
220 	asoc->c.peer_ttag = 0;
221 	asoc->c.my_port = ep->base.bind_addr.port;
222 
223 	asoc->c.initial_tsn = sctp_generate_tsn(ep);
224 
225 	asoc->next_tsn = asoc->c.initial_tsn;
226 
227 	asoc->ctsn_ack_point = asoc->next_tsn - 1;
228 	asoc->adv_peer_ack_point = asoc->ctsn_ack_point;
229 	asoc->highest_sacked = asoc->ctsn_ack_point;
230 	asoc->last_cwr_tsn = asoc->ctsn_ack_point;
231 	asoc->unack_data = 0;
232 
233 	/* ADDIP Section 4.1 Asconf Chunk Procedures
234 	 *
235 	 * When an endpoint has an ASCONF signaled change to be sent to the
236 	 * remote endpoint it should do the following:
237 	 * ...
238 	 * A2) a serial number should be assigned to the chunk. The serial
239 	 * number SHOULD be a monotonically increasing number. The serial
240 	 * numbers SHOULD be initialized at the start of the
241 	 * association to the same value as the initial TSN.
242 	 */
243 	asoc->addip_serial = asoc->c.initial_tsn;
244 
245 	INIT_LIST_HEAD(&asoc->addip_chunk_list);
246 	INIT_LIST_HEAD(&asoc->asconf_ack_list);
247 
248 	/* Make an empty list of remote transport addresses.  */
249 	INIT_LIST_HEAD(&asoc->peer.transport_addr_list);
250 	asoc->peer.transport_count = 0;
251 
252 	/* RFC 2960 5.1 Normal Establishment of an Association
253 	 *
254 	 * After the reception of the first data chunk in an
255 	 * association the endpoint must immediately respond with a
256 	 * sack to acknowledge the data chunk.  Subsequent
257 	 * acknowledgements should be done as described in Section
258 	 * 6.2.
259 	 *
260 	 * [We implement this by telling a new association that it
261 	 * already received one packet.]
262 	 */
263 	asoc->peer.sack_needed = 1;
264 
265 	/* Assume that the peer will tell us if he recognizes ASCONF
266 	 * as part of INIT exchange.
267 	 * The sctp_addip_noauth option is there for backward compatibilty
268 	 * and will revert old behavior.
269 	 */
270 	asoc->peer.asconf_capable = 0;
271 	if (sctp_addip_noauth)
272 		asoc->peer.asconf_capable = 1;
273 
274 	/* Create an input queue.  */
275 	sctp_inq_init(&asoc->base.inqueue);
276 	sctp_inq_set_th_handler(&asoc->base.inqueue, sctp_assoc_bh_rcv);
277 
278 	/* Create an output queue.  */
279 	sctp_outq_init(asoc, &asoc->outqueue);
280 
281 	if (!sctp_ulpq_init(&asoc->ulpq, asoc))
282 		goto fail_init;
283 
284 	/* Set up the tsn tracking. */
285 	sctp_tsnmap_init(&asoc->peer.tsn_map, SCTP_TSN_MAP_SIZE, 0);
286 
287 	asoc->need_ecne = 0;
288 
289 	asoc->assoc_id = 0;
290 
291 	/* Assume that peer would support both address types unless we are
292 	 * told otherwise.
293 	 */
294 	asoc->peer.ipv4_address = 1;
295 	asoc->peer.ipv6_address = 1;
296 	INIT_LIST_HEAD(&asoc->asocs);
297 
298 	asoc->autoclose = sp->autoclose;
299 
300 	asoc->default_stream = sp->default_stream;
301 	asoc->default_ppid = sp->default_ppid;
302 	asoc->default_flags = sp->default_flags;
303 	asoc->default_context = sp->default_context;
304 	asoc->default_timetolive = sp->default_timetolive;
305 	asoc->default_rcv_context = sp->default_rcv_context;
306 
307 	/* AUTH related initializations */
308 	INIT_LIST_HEAD(&asoc->endpoint_shared_keys);
309 	err = sctp_auth_asoc_copy_shkeys(ep, asoc, gfp);
310 	if (err)
311 		goto fail_init;
312 
313 	asoc->active_key_id = ep->active_key_id;
314 	asoc->asoc_shared_key = NULL;
315 
316 	asoc->default_hmac_id = 0;
317 	/* Save the hmacs and chunks list into this association */
318 	if (ep->auth_hmacs_list)
319 		memcpy(asoc->c.auth_hmacs, ep->auth_hmacs_list,
320 			ntohs(ep->auth_hmacs_list->param_hdr.length));
321 	if (ep->auth_chunk_list)
322 		memcpy(asoc->c.auth_chunks, ep->auth_chunk_list,
323 			ntohs(ep->auth_chunk_list->param_hdr.length));
324 
325 	/* Get the AUTH random number for this association */
326 	p = (sctp_paramhdr_t *)asoc->c.auth_random;
327 	p->type = SCTP_PARAM_RANDOM;
328 	p->length = htons(sizeof(sctp_paramhdr_t) + SCTP_AUTH_RANDOM_LENGTH);
329 	get_random_bytes(p+1, SCTP_AUTH_RANDOM_LENGTH);
330 
331 	return asoc;
332 
333 fail_init:
334 	sctp_endpoint_put(asoc->ep);
335 	sock_put(asoc->base.sk);
336 	return NULL;
337 }
338 
339 /* Allocate and initialize a new association */
340 struct sctp_association *sctp_association_new(const struct sctp_endpoint *ep,
341 					 const struct sock *sk,
342 					 sctp_scope_t scope,
343 					 gfp_t gfp)
344 {
345 	struct sctp_association *asoc;
346 
347 	asoc = t_new(struct sctp_association, gfp);
348 	if (!asoc)
349 		goto fail;
350 
351 	if (!sctp_association_init(asoc, ep, sk, scope, gfp))
352 		goto fail_init;
353 
354 	asoc->base.malloced = 1;
355 	SCTP_DBG_OBJCNT_INC(assoc);
356 	SCTP_DEBUG_PRINTK("Created asoc %p\n", asoc);
357 
358 	return asoc;
359 
360 fail_init:
361 	kfree(asoc);
362 fail:
363 	return NULL;
364 }
365 
366 /* Free this association if possible.  There may still be users, so
367  * the actual deallocation may be delayed.
368  */
369 void sctp_association_free(struct sctp_association *asoc)
370 {
371 	struct sock *sk = asoc->base.sk;
372 	struct sctp_transport *transport;
373 	struct list_head *pos, *temp;
374 	int i;
375 
376 	/* Only real associations count against the endpoint, so
377 	 * don't bother for if this is a temporary association.
378 	 */
379 	if (!asoc->temp) {
380 		list_del(&asoc->asocs);
381 
382 		/* Decrement the backlog value for a TCP-style listening
383 		 * socket.
384 		 */
385 		if (sctp_style(sk, TCP) && sctp_sstate(sk, LISTENING))
386 			sk->sk_ack_backlog--;
387 	}
388 
389 	/* Mark as dead, so other users can know this structure is
390 	 * going away.
391 	 */
392 	asoc->base.dead = 1;
393 
394 	/* Dispose of any data lying around in the outqueue. */
395 	sctp_outq_free(&asoc->outqueue);
396 
397 	/* Dispose of any pending messages for the upper layer. */
398 	sctp_ulpq_free(&asoc->ulpq);
399 
400 	/* Dispose of any pending chunks on the inqueue. */
401 	sctp_inq_free(&asoc->base.inqueue);
402 
403 	/* Free ssnmap storage. */
404 	sctp_ssnmap_free(asoc->ssnmap);
405 
406 	/* Clean up the bound address list. */
407 	sctp_bind_addr_free(&asoc->base.bind_addr);
408 
409 	/* Do we need to go through all of our timers and
410 	 * delete them?   To be safe we will try to delete all, but we
411 	 * should be able to go through and make a guess based
412 	 * on our state.
413 	 */
414 	for (i = SCTP_EVENT_TIMEOUT_NONE; i < SCTP_NUM_TIMEOUT_TYPES; ++i) {
415 		if (timer_pending(&asoc->timers[i]) &&
416 		    del_timer(&asoc->timers[i]))
417 			sctp_association_put(asoc);
418 	}
419 
420 	/* Free peer's cached cookie. */
421 	kfree(asoc->peer.cookie);
422 	kfree(asoc->peer.peer_random);
423 	kfree(asoc->peer.peer_chunks);
424 	kfree(asoc->peer.peer_hmacs);
425 
426 	/* Release the transport structures. */
427 	list_for_each_safe(pos, temp, &asoc->peer.transport_addr_list) {
428 		transport = list_entry(pos, struct sctp_transport, transports);
429 		list_del(pos);
430 		sctp_transport_free(transport);
431 	}
432 
433 	asoc->peer.transport_count = 0;
434 
435 	/* Free any cached ASCONF_ACK chunk. */
436 	sctp_assoc_free_asconf_acks(asoc);
437 
438 	/* Free any cached ASCONF chunk. */
439 	if (asoc->addip_last_asconf)
440 		sctp_chunk_free(asoc->addip_last_asconf);
441 
442 	/* AUTH - Free the endpoint shared keys */
443 	sctp_auth_destroy_keys(&asoc->endpoint_shared_keys);
444 
445 	/* AUTH - Free the association shared key */
446 	sctp_auth_key_put(asoc->asoc_shared_key);
447 
448 	sctp_association_put(asoc);
449 }
450 
451 /* Cleanup and free up an association. */
452 static void sctp_association_destroy(struct sctp_association *asoc)
453 {
454 	SCTP_ASSERT(asoc->base.dead, "Assoc is not dead", return);
455 
456 	sctp_endpoint_put(asoc->ep);
457 	sock_put(asoc->base.sk);
458 
459 	if (asoc->assoc_id != 0) {
460 		spin_lock_bh(&sctp_assocs_id_lock);
461 		idr_remove(&sctp_assocs_id, asoc->assoc_id);
462 		spin_unlock_bh(&sctp_assocs_id_lock);
463 	}
464 
465 	BUG_TRAP(!atomic_read(&asoc->rmem_alloc));
466 
467 	if (asoc->base.malloced) {
468 		kfree(asoc);
469 		SCTP_DBG_OBJCNT_DEC(assoc);
470 	}
471 }
472 
473 /* Change the primary destination address for the peer. */
474 void sctp_assoc_set_primary(struct sctp_association *asoc,
475 			    struct sctp_transport *transport)
476 {
477 	asoc->peer.primary_path = transport;
478 
479 	/* Set a default msg_name for events. */
480 	memcpy(&asoc->peer.primary_addr, &transport->ipaddr,
481 	       sizeof(union sctp_addr));
482 
483 	/* If the primary path is changing, assume that the
484 	 * user wants to use this new path.
485 	 */
486 	if ((transport->state == SCTP_ACTIVE) ||
487 	    (transport->state == SCTP_UNKNOWN))
488 		asoc->peer.active_path = transport;
489 
490 	/*
491 	 * SFR-CACC algorithm:
492 	 * Upon the receipt of a request to change the primary
493 	 * destination address, on the data structure for the new
494 	 * primary destination, the sender MUST do the following:
495 	 *
496 	 * 1) If CHANGEOVER_ACTIVE is set, then there was a switch
497 	 * to this destination address earlier. The sender MUST set
498 	 * CYCLING_CHANGEOVER to indicate that this switch is a
499 	 * double switch to the same destination address.
500 	 */
501 	if (transport->cacc.changeover_active)
502 		transport->cacc.cycling_changeover = 1;
503 
504 	/* 2) The sender MUST set CHANGEOVER_ACTIVE to indicate that
505 	 * a changeover has occurred.
506 	 */
507 	transport->cacc.changeover_active = 1;
508 
509 	/* 3) The sender MUST store the next TSN to be sent in
510 	 * next_tsn_at_change.
511 	 */
512 	transport->cacc.next_tsn_at_change = asoc->next_tsn;
513 }
514 
515 /* Remove a transport from an association.  */
516 void sctp_assoc_rm_peer(struct sctp_association *asoc,
517 			struct sctp_transport *peer)
518 {
519 	struct list_head	*pos;
520 	struct sctp_transport	*transport;
521 
522 	SCTP_DEBUG_PRINTK_IPADDR("sctp_assoc_rm_peer:association %p addr: ",
523 				 " port: %d\n",
524 				 asoc,
525 				 (&peer->ipaddr),
526 				 ntohs(peer->ipaddr.v4.sin_port));
527 
528 	/* If we are to remove the current retran_path, update it
529 	 * to the next peer before removing this peer from the list.
530 	 */
531 	if (asoc->peer.retran_path == peer)
532 		sctp_assoc_update_retran_path(asoc);
533 
534 	/* Remove this peer from the list. */
535 	list_del(&peer->transports);
536 
537 	/* Get the first transport of asoc. */
538 	pos = asoc->peer.transport_addr_list.next;
539 	transport = list_entry(pos, struct sctp_transport, transports);
540 
541 	/* Update any entries that match the peer to be deleted. */
542 	if (asoc->peer.primary_path == peer)
543 		sctp_assoc_set_primary(asoc, transport);
544 	if (asoc->peer.active_path == peer)
545 		asoc->peer.active_path = transport;
546 	if (asoc->peer.last_data_from == peer)
547 		asoc->peer.last_data_from = transport;
548 
549 	/* If we remove the transport an INIT was last sent to, set it to
550 	 * NULL. Combined with the update of the retran path above, this
551 	 * will cause the next INIT to be sent to the next available
552 	 * transport, maintaining the cycle.
553 	 */
554 	if (asoc->init_last_sent_to == peer)
555 		asoc->init_last_sent_to = NULL;
556 
557 	asoc->peer.transport_count--;
558 
559 	sctp_transport_free(peer);
560 }
561 
562 /* Add a transport address to an association.  */
563 struct sctp_transport *sctp_assoc_add_peer(struct sctp_association *asoc,
564 					   const union sctp_addr *addr,
565 					   const gfp_t gfp,
566 					   const int peer_state)
567 {
568 	struct sctp_transport *peer;
569 	struct sctp_sock *sp;
570 	unsigned short port;
571 
572 	sp = sctp_sk(asoc->base.sk);
573 
574 	/* AF_INET and AF_INET6 share common port field. */
575 	port = ntohs(addr->v4.sin_port);
576 
577 	SCTP_DEBUG_PRINTK_IPADDR("sctp_assoc_add_peer:association %p addr: ",
578 				 " port: %d state:%d\n",
579 				 asoc,
580 				 addr,
581 				 port,
582 				 peer_state);
583 
584 	/* Set the port if it has not been set yet.  */
585 	if (0 == asoc->peer.port)
586 		asoc->peer.port = port;
587 
588 	/* Check to see if this is a duplicate. */
589 	peer = sctp_assoc_lookup_paddr(asoc, addr);
590 	if (peer) {
591 		if (peer->state == SCTP_UNKNOWN) {
592 			if (peer_state == SCTP_ACTIVE)
593 				peer->state = SCTP_ACTIVE;
594 			if (peer_state == SCTP_UNCONFIRMED)
595 				peer->state = SCTP_UNCONFIRMED;
596 		}
597 		return peer;
598 	}
599 
600 	peer = sctp_transport_new(addr, gfp);
601 	if (!peer)
602 		return NULL;
603 
604 	sctp_transport_set_owner(peer, asoc);
605 
606 	/* Initialize the peer's heartbeat interval based on the
607 	 * association configured value.
608 	 */
609 	peer->hbinterval = asoc->hbinterval;
610 
611 	/* Set the path max_retrans.  */
612 	peer->pathmaxrxt = asoc->pathmaxrxt;
613 
614 	/* Initialize the peer's SACK delay timeout based on the
615 	 * association configured value.
616 	 */
617 	peer->sackdelay = asoc->sackdelay;
618 
619 	/* Enable/disable heartbeat, SACK delay, and path MTU discovery
620 	 * based on association setting.
621 	 */
622 	peer->param_flags = asoc->param_flags;
623 
624 	/* Initialize the pmtu of the transport. */
625 	if (peer->param_flags & SPP_PMTUD_ENABLE)
626 		sctp_transport_pmtu(peer);
627 	else if (asoc->pathmtu)
628 		peer->pathmtu = asoc->pathmtu;
629 	else
630 		peer->pathmtu = SCTP_DEFAULT_MAXSEGMENT;
631 
632 	/* If this is the first transport addr on this association,
633 	 * initialize the association PMTU to the peer's PMTU.
634 	 * If not and the current association PMTU is higher than the new
635 	 * peer's PMTU, reset the association PMTU to the new peer's PMTU.
636 	 */
637 	if (asoc->pathmtu)
638 		asoc->pathmtu = min_t(int, peer->pathmtu, asoc->pathmtu);
639 	else
640 		asoc->pathmtu = peer->pathmtu;
641 
642 	SCTP_DEBUG_PRINTK("sctp_assoc_add_peer:association %p PMTU set to "
643 			  "%d\n", asoc, asoc->pathmtu);
644 
645 	asoc->frag_point = sctp_frag_point(sp, asoc->pathmtu);
646 
647 	/* The asoc->peer.port might not be meaningful yet, but
648 	 * initialize the packet structure anyway.
649 	 */
650 	sctp_packet_init(&peer->packet, peer, asoc->base.bind_addr.port,
651 			 asoc->peer.port);
652 
653 	/* 7.2.1 Slow-Start
654 	 *
655 	 * o The initial cwnd before DATA transmission or after a sufficiently
656 	 *   long idle period MUST be set to
657 	 *      min(4*MTU, max(2*MTU, 4380 bytes))
658 	 *
659 	 * o The initial value of ssthresh MAY be arbitrarily high
660 	 *   (for example, implementations MAY use the size of the
661 	 *   receiver advertised window).
662 	 */
663 	peer->cwnd = min(4*asoc->pathmtu, max_t(__u32, 2*asoc->pathmtu, 4380));
664 
665 	/* At this point, we may not have the receiver's advertised window,
666 	 * so initialize ssthresh to the default value and it will be set
667 	 * later when we process the INIT.
668 	 */
669 	peer->ssthresh = SCTP_DEFAULT_MAXWINDOW;
670 
671 	peer->partial_bytes_acked = 0;
672 	peer->flight_size = 0;
673 
674 	/* Set the transport's RTO.initial value */
675 	peer->rto = asoc->rto_initial;
676 
677 	/* Set the peer's active state. */
678 	peer->state = peer_state;
679 
680 	/* Attach the remote transport to our asoc.  */
681 	list_add_tail(&peer->transports, &asoc->peer.transport_addr_list);
682 	asoc->peer.transport_count++;
683 
684 	/* If we do not yet have a primary path, set one.  */
685 	if (!asoc->peer.primary_path) {
686 		sctp_assoc_set_primary(asoc, peer);
687 		asoc->peer.retran_path = peer;
688 	}
689 
690 	if (asoc->peer.active_path == asoc->peer.retran_path) {
691 		asoc->peer.retran_path = peer;
692 	}
693 
694 	return peer;
695 }
696 
697 /* Delete a transport address from an association.  */
698 void sctp_assoc_del_peer(struct sctp_association *asoc,
699 			 const union sctp_addr *addr)
700 {
701 	struct list_head	*pos;
702 	struct list_head	*temp;
703 	struct sctp_transport	*transport;
704 
705 	list_for_each_safe(pos, temp, &asoc->peer.transport_addr_list) {
706 		transport = list_entry(pos, struct sctp_transport, transports);
707 		if (sctp_cmp_addr_exact(addr, &transport->ipaddr)) {
708 			/* Do book keeping for removing the peer and free it. */
709 			sctp_assoc_rm_peer(asoc, transport);
710 			break;
711 		}
712 	}
713 }
714 
715 /* Lookup a transport by address. */
716 struct sctp_transport *sctp_assoc_lookup_paddr(
717 					const struct sctp_association *asoc,
718 					const union sctp_addr *address)
719 {
720 	struct sctp_transport *t;
721 	struct list_head *pos;
722 
723 	/* Cycle through all transports searching for a peer address. */
724 
725 	list_for_each(pos, &asoc->peer.transport_addr_list) {
726 		t = list_entry(pos, struct sctp_transport, transports);
727 		if (sctp_cmp_addr_exact(address, &t->ipaddr))
728 			return t;
729 	}
730 
731 	return NULL;
732 }
733 
734 /* Remove all transports except a give one */
735 void sctp_assoc_del_nonprimary_peers(struct sctp_association *asoc,
736 				     struct sctp_transport *primary)
737 {
738 	struct sctp_transport	*temp;
739 	struct sctp_transport	*t;
740 
741 	list_for_each_entry_safe(t, temp, &asoc->peer.transport_addr_list,
742 				 transports) {
743 		/* if the current transport is not the primary one, delete it */
744 		if (t != primary)
745 			sctp_assoc_rm_peer(asoc, t);
746 	}
747 
748 	return;
749 }
750 
751 /* Engage in transport control operations.
752  * Mark the transport up or down and send a notification to the user.
753  * Select and update the new active and retran paths.
754  */
755 void sctp_assoc_control_transport(struct sctp_association *asoc,
756 				  struct sctp_transport *transport,
757 				  sctp_transport_cmd_t command,
758 				  sctp_sn_error_t error)
759 {
760 	struct sctp_transport *t = NULL;
761 	struct sctp_transport *first;
762 	struct sctp_transport *second;
763 	struct sctp_ulpevent *event;
764 	struct sockaddr_storage addr;
765 	struct list_head *pos;
766 	int spc_state = 0;
767 
768 	/* Record the transition on the transport.  */
769 	switch (command) {
770 	case SCTP_TRANSPORT_UP:
771 		/* If we are moving from UNCONFIRMED state due
772 		 * to heartbeat success, report the SCTP_ADDR_CONFIRMED
773 		 * state to the user, otherwise report SCTP_ADDR_AVAILABLE.
774 		 */
775 		if (SCTP_UNCONFIRMED == transport->state &&
776 		    SCTP_HEARTBEAT_SUCCESS == error)
777 			spc_state = SCTP_ADDR_CONFIRMED;
778 		else
779 			spc_state = SCTP_ADDR_AVAILABLE;
780 		transport->state = SCTP_ACTIVE;
781 		break;
782 
783 	case SCTP_TRANSPORT_DOWN:
784 		/* if the transort was never confirmed, do not transition it
785 		 * to inactive state.
786 		 */
787 		if (transport->state != SCTP_UNCONFIRMED)
788 			transport->state = SCTP_INACTIVE;
789 
790 		spc_state = SCTP_ADDR_UNREACHABLE;
791 		break;
792 
793 	default:
794 		return;
795 	}
796 
797 	/* Generate and send a SCTP_PEER_ADDR_CHANGE notification to the
798 	 * user.
799 	 */
800 	memset(&addr, 0, sizeof(struct sockaddr_storage));
801 	memcpy(&addr, &transport->ipaddr, transport->af_specific->sockaddr_len);
802 	event = sctp_ulpevent_make_peer_addr_change(asoc, &addr,
803 				0, spc_state, error, GFP_ATOMIC);
804 	if (event)
805 		sctp_ulpq_tail_event(&asoc->ulpq, event);
806 
807 	/* Select new active and retran paths. */
808 
809 	/* Look for the two most recently used active transports.
810 	 *
811 	 * This code produces the wrong ordering whenever jiffies
812 	 * rolls over, but we still get usable transports, so we don't
813 	 * worry about it.
814 	 */
815 	first = NULL; second = NULL;
816 
817 	list_for_each(pos, &asoc->peer.transport_addr_list) {
818 		t = list_entry(pos, struct sctp_transport, transports);
819 
820 		if ((t->state == SCTP_INACTIVE) ||
821 		    (t->state == SCTP_UNCONFIRMED))
822 			continue;
823 		if (!first || t->last_time_heard > first->last_time_heard) {
824 			second = first;
825 			first = t;
826 		}
827 		if (!second || t->last_time_heard > second->last_time_heard)
828 			second = t;
829 	}
830 
831 	/* RFC 2960 6.4 Multi-Homed SCTP Endpoints
832 	 *
833 	 * By default, an endpoint should always transmit to the
834 	 * primary path, unless the SCTP user explicitly specifies the
835 	 * destination transport address (and possibly source
836 	 * transport address) to use.
837 	 *
838 	 * [If the primary is active but not most recent, bump the most
839 	 * recently used transport.]
840 	 */
841 	if (((asoc->peer.primary_path->state == SCTP_ACTIVE) ||
842 	     (asoc->peer.primary_path->state == SCTP_UNKNOWN)) &&
843 	    first != asoc->peer.primary_path) {
844 		second = first;
845 		first = asoc->peer.primary_path;
846 	}
847 
848 	/* If we failed to find a usable transport, just camp on the
849 	 * primary, even if it is inactive.
850 	 */
851 	if (!first) {
852 		first = asoc->peer.primary_path;
853 		second = asoc->peer.primary_path;
854 	}
855 
856 	/* Set the active and retran transports.  */
857 	asoc->peer.active_path = first;
858 	asoc->peer.retran_path = second;
859 }
860 
861 /* Hold a reference to an association. */
862 void sctp_association_hold(struct sctp_association *asoc)
863 {
864 	atomic_inc(&asoc->base.refcnt);
865 }
866 
867 /* Release a reference to an association and cleanup
868  * if there are no more references.
869  */
870 void sctp_association_put(struct sctp_association *asoc)
871 {
872 	if (atomic_dec_and_test(&asoc->base.refcnt))
873 		sctp_association_destroy(asoc);
874 }
875 
876 /* Allocate the next TSN, Transmission Sequence Number, for the given
877  * association.
878  */
879 __u32 sctp_association_get_next_tsn(struct sctp_association *asoc)
880 {
881 	/* From Section 1.6 Serial Number Arithmetic:
882 	 * Transmission Sequence Numbers wrap around when they reach
883 	 * 2**32 - 1.  That is, the next TSN a DATA chunk MUST use
884 	 * after transmitting TSN = 2*32 - 1 is TSN = 0.
885 	 */
886 	__u32 retval = asoc->next_tsn;
887 	asoc->next_tsn++;
888 	asoc->unack_data++;
889 
890 	return retval;
891 }
892 
893 /* Compare two addresses to see if they match.  Wildcard addresses
894  * only match themselves.
895  */
896 int sctp_cmp_addr_exact(const union sctp_addr *ss1,
897 			const union sctp_addr *ss2)
898 {
899 	struct sctp_af *af;
900 
901 	af = sctp_get_af_specific(ss1->sa.sa_family);
902 	if (unlikely(!af))
903 		return 0;
904 
905 	return af->cmp_addr(ss1, ss2);
906 }
907 
908 /* Return an ecne chunk to get prepended to a packet.
909  * Note:  We are sly and return a shared, prealloced chunk.  FIXME:
910  * No we don't, but we could/should.
911  */
912 struct sctp_chunk *sctp_get_ecne_prepend(struct sctp_association *asoc)
913 {
914 	struct sctp_chunk *chunk;
915 
916 	/* Send ECNE if needed.
917 	 * Not being able to allocate a chunk here is not deadly.
918 	 */
919 	if (asoc->need_ecne)
920 		chunk = sctp_make_ecne(asoc, asoc->last_ecne_tsn);
921 	else
922 		chunk = NULL;
923 
924 	return chunk;
925 }
926 
927 /*
928  * Find which transport this TSN was sent on.
929  */
930 struct sctp_transport *sctp_assoc_lookup_tsn(struct sctp_association *asoc,
931 					     __u32 tsn)
932 {
933 	struct sctp_transport *active;
934 	struct sctp_transport *match;
935 	struct list_head *entry, *pos;
936 	struct sctp_transport *transport;
937 	struct sctp_chunk *chunk;
938 	__be32 key = htonl(tsn);
939 
940 	match = NULL;
941 
942 	/*
943 	 * FIXME: In general, find a more efficient data structure for
944 	 * searching.
945 	 */
946 
947 	/*
948 	 * The general strategy is to search each transport's transmitted
949 	 * list.   Return which transport this TSN lives on.
950 	 *
951 	 * Let's be hopeful and check the active_path first.
952 	 * Another optimization would be to know if there is only one
953 	 * outbound path and not have to look for the TSN at all.
954 	 *
955 	 */
956 
957 	active = asoc->peer.active_path;
958 
959 	list_for_each(entry, &active->transmitted) {
960 		chunk = list_entry(entry, struct sctp_chunk, transmitted_list);
961 
962 		if (key == chunk->subh.data_hdr->tsn) {
963 			match = active;
964 			goto out;
965 		}
966 	}
967 
968 	/* If not found, go search all the other transports. */
969 	list_for_each(pos, &asoc->peer.transport_addr_list) {
970 		transport = list_entry(pos, struct sctp_transport, transports);
971 
972 		if (transport == active)
973 			break;
974 		list_for_each(entry, &transport->transmitted) {
975 			chunk = list_entry(entry, struct sctp_chunk,
976 					   transmitted_list);
977 			if (key == chunk->subh.data_hdr->tsn) {
978 				match = transport;
979 				goto out;
980 			}
981 		}
982 	}
983 out:
984 	return match;
985 }
986 
987 /* Is this the association we are looking for? */
988 struct sctp_transport *sctp_assoc_is_match(struct sctp_association *asoc,
989 					   const union sctp_addr *laddr,
990 					   const union sctp_addr *paddr)
991 {
992 	struct sctp_transport *transport;
993 
994 	if ((htons(asoc->base.bind_addr.port) == laddr->v4.sin_port) &&
995 	    (htons(asoc->peer.port) == paddr->v4.sin_port)) {
996 		transport = sctp_assoc_lookup_paddr(asoc, paddr);
997 		if (!transport)
998 			goto out;
999 
1000 		if (sctp_bind_addr_match(&asoc->base.bind_addr, laddr,
1001 					 sctp_sk(asoc->base.sk)))
1002 			goto out;
1003 	}
1004 	transport = NULL;
1005 
1006 out:
1007 	return transport;
1008 }
1009 
1010 /* Do delayed input processing.  This is scheduled by sctp_rcv(). */
1011 static void sctp_assoc_bh_rcv(struct work_struct *work)
1012 {
1013 	struct sctp_association *asoc =
1014 		container_of(work, struct sctp_association,
1015 			     base.inqueue.immediate);
1016 	struct sctp_endpoint *ep;
1017 	struct sctp_chunk *chunk;
1018 	struct sock *sk;
1019 	struct sctp_inq *inqueue;
1020 	int state;
1021 	sctp_subtype_t subtype;
1022 	int error = 0;
1023 
1024 	/* The association should be held so we should be safe. */
1025 	ep = asoc->ep;
1026 	sk = asoc->base.sk;
1027 
1028 	inqueue = &asoc->base.inqueue;
1029 	sctp_association_hold(asoc);
1030 	while (NULL != (chunk = sctp_inq_pop(inqueue))) {
1031 		state = asoc->state;
1032 		subtype = SCTP_ST_CHUNK(chunk->chunk_hdr->type);
1033 
1034 		/* SCTP-AUTH, Section 6.3:
1035 		 *    The receiver has a list of chunk types which it expects
1036 		 *    to be received only after an AUTH-chunk.  This list has
1037 		 *    been sent to the peer during the association setup.  It
1038 		 *    MUST silently discard these chunks if they are not placed
1039 		 *    after an AUTH chunk in the packet.
1040 		 */
1041 		if (sctp_auth_recv_cid(subtype.chunk, asoc) && !chunk->auth)
1042 			continue;
1043 
1044 		/* Remember where the last DATA chunk came from so we
1045 		 * know where to send the SACK.
1046 		 */
1047 		if (sctp_chunk_is_data(chunk))
1048 			asoc->peer.last_data_from = chunk->transport;
1049 		else
1050 			SCTP_INC_STATS(SCTP_MIB_INCTRLCHUNKS);
1051 
1052 		if (chunk->transport)
1053 			chunk->transport->last_time_heard = jiffies;
1054 
1055 		/* Run through the state machine. */
1056 		error = sctp_do_sm(SCTP_EVENT_T_CHUNK, subtype,
1057 				   state, ep, asoc, chunk, GFP_ATOMIC);
1058 
1059 		/* Check to see if the association is freed in response to
1060 		 * the incoming chunk.  If so, get out of the while loop.
1061 		 */
1062 		if (asoc->base.dead)
1063 			break;
1064 
1065 		/* If there is an error on chunk, discard this packet. */
1066 		if (error && chunk)
1067 			chunk->pdiscard = 1;
1068 	}
1069 	sctp_association_put(asoc);
1070 }
1071 
1072 /* This routine moves an association from its old sk to a new sk.  */
1073 void sctp_assoc_migrate(struct sctp_association *assoc, struct sock *newsk)
1074 {
1075 	struct sctp_sock *newsp = sctp_sk(newsk);
1076 	struct sock *oldsk = assoc->base.sk;
1077 
1078 	/* Delete the association from the old endpoint's list of
1079 	 * associations.
1080 	 */
1081 	list_del_init(&assoc->asocs);
1082 
1083 	/* Decrement the backlog value for a TCP-style socket. */
1084 	if (sctp_style(oldsk, TCP))
1085 		oldsk->sk_ack_backlog--;
1086 
1087 	/* Release references to the old endpoint and the sock.  */
1088 	sctp_endpoint_put(assoc->ep);
1089 	sock_put(assoc->base.sk);
1090 
1091 	/* Get a reference to the new endpoint.  */
1092 	assoc->ep = newsp->ep;
1093 	sctp_endpoint_hold(assoc->ep);
1094 
1095 	/* Get a reference to the new sock.  */
1096 	assoc->base.sk = newsk;
1097 	sock_hold(assoc->base.sk);
1098 
1099 	/* Add the association to the new endpoint's list of associations.  */
1100 	sctp_endpoint_add_asoc(newsp->ep, assoc);
1101 }
1102 
1103 /* Update an association (possibly from unexpected COOKIE-ECHO processing).  */
1104 void sctp_assoc_update(struct sctp_association *asoc,
1105 		       struct sctp_association *new)
1106 {
1107 	struct sctp_transport *trans;
1108 	struct list_head *pos, *temp;
1109 
1110 	/* Copy in new parameters of peer. */
1111 	asoc->c = new->c;
1112 	asoc->peer.rwnd = new->peer.rwnd;
1113 	asoc->peer.sack_needed = new->peer.sack_needed;
1114 	asoc->peer.i = new->peer.i;
1115 	sctp_tsnmap_init(&asoc->peer.tsn_map, SCTP_TSN_MAP_SIZE,
1116 			 asoc->peer.i.initial_tsn);
1117 
1118 	/* Remove any peer addresses not present in the new association. */
1119 	list_for_each_safe(pos, temp, &asoc->peer.transport_addr_list) {
1120 		trans = list_entry(pos, struct sctp_transport, transports);
1121 		if (!sctp_assoc_lookup_paddr(new, &trans->ipaddr))
1122 			sctp_assoc_del_peer(asoc, &trans->ipaddr);
1123 
1124 		if (asoc->state >= SCTP_STATE_ESTABLISHED)
1125 			sctp_transport_reset(trans);
1126 	}
1127 
1128 	/* If the case is A (association restart), use
1129 	 * initial_tsn as next_tsn. If the case is B, use
1130 	 * current next_tsn in case data sent to peer
1131 	 * has been discarded and needs retransmission.
1132 	 */
1133 	if (asoc->state >= SCTP_STATE_ESTABLISHED) {
1134 		asoc->next_tsn = new->next_tsn;
1135 		asoc->ctsn_ack_point = new->ctsn_ack_point;
1136 		asoc->adv_peer_ack_point = new->adv_peer_ack_point;
1137 
1138 		/* Reinitialize SSN for both local streams
1139 		 * and peer's streams.
1140 		 */
1141 		sctp_ssnmap_clear(asoc->ssnmap);
1142 
1143 		/* Flush the ULP reassembly and ordered queue.
1144 		 * Any data there will now be stale and will
1145 		 * cause problems.
1146 		 */
1147 		sctp_ulpq_flush(&asoc->ulpq);
1148 
1149 		/* reset the overall association error count so
1150 		 * that the restarted association doesn't get torn
1151 		 * down on the next retransmission timer.
1152 		 */
1153 		asoc->overall_error_count = 0;
1154 
1155 	} else {
1156 		/* Add any peer addresses from the new association. */
1157 		list_for_each(pos, &new->peer.transport_addr_list) {
1158 			trans = list_entry(pos, struct sctp_transport,
1159 					   transports);
1160 			if (!sctp_assoc_lookup_paddr(asoc, &trans->ipaddr))
1161 				sctp_assoc_add_peer(asoc, &trans->ipaddr,
1162 						    GFP_ATOMIC, trans->state);
1163 		}
1164 
1165 		asoc->ctsn_ack_point = asoc->next_tsn - 1;
1166 		asoc->adv_peer_ack_point = asoc->ctsn_ack_point;
1167 		if (!asoc->ssnmap) {
1168 			/* Move the ssnmap. */
1169 			asoc->ssnmap = new->ssnmap;
1170 			new->ssnmap = NULL;
1171 		}
1172 
1173 		if (!asoc->assoc_id) {
1174 			/* get a new association id since we don't have one
1175 			 * yet.
1176 			 */
1177 			sctp_assoc_set_id(asoc, GFP_ATOMIC);
1178 		}
1179 	}
1180 
1181 	/* SCTP-AUTH: Save the peer parameters from the new assocaitions
1182 	 * and also move the association shared keys over
1183 	 */
1184 	kfree(asoc->peer.peer_random);
1185 	asoc->peer.peer_random = new->peer.peer_random;
1186 	new->peer.peer_random = NULL;
1187 
1188 	kfree(asoc->peer.peer_chunks);
1189 	asoc->peer.peer_chunks = new->peer.peer_chunks;
1190 	new->peer.peer_chunks = NULL;
1191 
1192 	kfree(asoc->peer.peer_hmacs);
1193 	asoc->peer.peer_hmacs = new->peer.peer_hmacs;
1194 	new->peer.peer_hmacs = NULL;
1195 
1196 	sctp_auth_key_put(asoc->asoc_shared_key);
1197 	sctp_auth_asoc_init_active_key(asoc, GFP_ATOMIC);
1198 }
1199 
1200 /* Update the retran path for sending a retransmitted packet.
1201  * Round-robin through the active transports, else round-robin
1202  * through the inactive transports as this is the next best thing
1203  * we can try.
1204  */
1205 void sctp_assoc_update_retran_path(struct sctp_association *asoc)
1206 {
1207 	struct sctp_transport *t, *next;
1208 	struct list_head *head = &asoc->peer.transport_addr_list;
1209 	struct list_head *pos;
1210 
1211 	/* Find the next transport in a round-robin fashion. */
1212 	t = asoc->peer.retran_path;
1213 	pos = &t->transports;
1214 	next = NULL;
1215 
1216 	while (1) {
1217 		/* Skip the head. */
1218 		if (pos->next == head)
1219 			pos = head->next;
1220 		else
1221 			pos = pos->next;
1222 
1223 		t = list_entry(pos, struct sctp_transport, transports);
1224 
1225 		/* Try to find an active transport. */
1226 
1227 		if ((t->state == SCTP_ACTIVE) ||
1228 		    (t->state == SCTP_UNKNOWN)) {
1229 			break;
1230 		} else {
1231 			/* Keep track of the next transport in case
1232 			 * we don't find any active transport.
1233 			 */
1234 			if (!next)
1235 				next = t;
1236 		}
1237 
1238 		/* We have exhausted the list, but didn't find any
1239 		 * other active transports.  If so, use the next
1240 		 * transport.
1241 		 */
1242 		if (t == asoc->peer.retran_path) {
1243 			t = next;
1244 			break;
1245 		}
1246 	}
1247 
1248 	asoc->peer.retran_path = t;
1249 
1250 	SCTP_DEBUG_PRINTK_IPADDR("sctp_assoc_update_retran_path:association"
1251 				 " %p addr: ",
1252 				 " port: %d\n",
1253 				 asoc,
1254 				 (&t->ipaddr),
1255 				 ntohs(t->ipaddr.v4.sin_port));
1256 }
1257 
1258 /* Choose the transport for sending a INIT packet.  */
1259 struct sctp_transport *sctp_assoc_choose_init_transport(
1260 	struct sctp_association *asoc)
1261 {
1262 	struct sctp_transport *t;
1263 
1264 	/* Use the retran path. If the last INIT was sent over the
1265 	 * retran path, update the retran path and use it.
1266 	 */
1267 	if (!asoc->init_last_sent_to) {
1268 		t = asoc->peer.active_path;
1269 	} else {
1270 		if (asoc->init_last_sent_to == asoc->peer.retran_path)
1271 			sctp_assoc_update_retran_path(asoc);
1272 		t = asoc->peer.retran_path;
1273 	}
1274 
1275 	SCTP_DEBUG_PRINTK_IPADDR("sctp_assoc_update_retran_path:association"
1276 				 " %p addr: ",
1277 				 " port: %d\n",
1278 				 asoc,
1279 				 (&t->ipaddr),
1280 				 ntohs(t->ipaddr.v4.sin_port));
1281 
1282 	return t;
1283 }
1284 
1285 /* Choose the transport for sending a SHUTDOWN packet.  */
1286 struct sctp_transport *sctp_assoc_choose_shutdown_transport(
1287 	struct sctp_association *asoc)
1288 {
1289 	/* If this is the first time SHUTDOWN is sent, use the active path,
1290 	 * else use the retran path. If the last SHUTDOWN was sent over the
1291 	 * retran path, update the retran path and use it.
1292 	 */
1293 	if (!asoc->shutdown_last_sent_to)
1294 		return asoc->peer.active_path;
1295 	else {
1296 		if (asoc->shutdown_last_sent_to == asoc->peer.retran_path)
1297 			sctp_assoc_update_retran_path(asoc);
1298 		return asoc->peer.retran_path;
1299 	}
1300 
1301 }
1302 
1303 /* Update the association's pmtu and frag_point by going through all the
1304  * transports. This routine is called when a transport's PMTU has changed.
1305  */
1306 void sctp_assoc_sync_pmtu(struct sctp_association *asoc)
1307 {
1308 	struct sctp_transport *t;
1309 	struct list_head *pos;
1310 	__u32 pmtu = 0;
1311 
1312 	if (!asoc)
1313 		return;
1314 
1315 	/* Get the lowest pmtu of all the transports. */
1316 	list_for_each(pos, &asoc->peer.transport_addr_list) {
1317 		t = list_entry(pos, struct sctp_transport, transports);
1318 		if (t->pmtu_pending && t->dst) {
1319 			sctp_transport_update_pmtu(t, dst_mtu(t->dst));
1320 			t->pmtu_pending = 0;
1321 		}
1322 		if (!pmtu || (t->pathmtu < pmtu))
1323 			pmtu = t->pathmtu;
1324 	}
1325 
1326 	if (pmtu) {
1327 		struct sctp_sock *sp = sctp_sk(asoc->base.sk);
1328 		asoc->pathmtu = pmtu;
1329 		asoc->frag_point = sctp_frag_point(sp, pmtu);
1330 	}
1331 
1332 	SCTP_DEBUG_PRINTK("%s: asoc:%p, pmtu:%d, frag_point:%d\n",
1333 			  __FUNCTION__, asoc, asoc->pathmtu, asoc->frag_point);
1334 }
1335 
1336 /* Should we send a SACK to update our peer? */
1337 static inline int sctp_peer_needs_update(struct sctp_association *asoc)
1338 {
1339 	switch (asoc->state) {
1340 	case SCTP_STATE_ESTABLISHED:
1341 	case SCTP_STATE_SHUTDOWN_PENDING:
1342 	case SCTP_STATE_SHUTDOWN_RECEIVED:
1343 	case SCTP_STATE_SHUTDOWN_SENT:
1344 		if ((asoc->rwnd > asoc->a_rwnd) &&
1345 		    ((asoc->rwnd - asoc->a_rwnd) >=
1346 		     min_t(__u32, (asoc->base.sk->sk_rcvbuf >> 1), asoc->pathmtu)))
1347 			return 1;
1348 		break;
1349 	default:
1350 		break;
1351 	}
1352 	return 0;
1353 }
1354 
1355 /* Increase asoc's rwnd by len and send any window update SACK if needed. */
1356 void sctp_assoc_rwnd_increase(struct sctp_association *asoc, unsigned len)
1357 {
1358 	struct sctp_chunk *sack;
1359 	struct timer_list *timer;
1360 
1361 	if (asoc->rwnd_over) {
1362 		if (asoc->rwnd_over >= len) {
1363 			asoc->rwnd_over -= len;
1364 		} else {
1365 			asoc->rwnd += (len - asoc->rwnd_over);
1366 			asoc->rwnd_over = 0;
1367 		}
1368 	} else {
1369 		asoc->rwnd += len;
1370 	}
1371 
1372 	SCTP_DEBUG_PRINTK("%s: asoc %p rwnd increased by %d to (%u, %u) "
1373 			  "- %u\n", __FUNCTION__, asoc, len, asoc->rwnd,
1374 			  asoc->rwnd_over, asoc->a_rwnd);
1375 
1376 	/* Send a window update SACK if the rwnd has increased by at least the
1377 	 * minimum of the association's PMTU and half of the receive buffer.
1378 	 * The algorithm used is similar to the one described in
1379 	 * Section 4.2.3.3 of RFC 1122.
1380 	 */
1381 	if (sctp_peer_needs_update(asoc)) {
1382 		asoc->a_rwnd = asoc->rwnd;
1383 		SCTP_DEBUG_PRINTK("%s: Sending window update SACK- asoc: %p "
1384 				  "rwnd: %u a_rwnd: %u\n", __FUNCTION__,
1385 				  asoc, asoc->rwnd, asoc->a_rwnd);
1386 		sack = sctp_make_sack(asoc);
1387 		if (!sack)
1388 			return;
1389 
1390 		asoc->peer.sack_needed = 0;
1391 
1392 		sctp_outq_tail(&asoc->outqueue, sack);
1393 
1394 		/* Stop the SACK timer.  */
1395 		timer = &asoc->timers[SCTP_EVENT_TIMEOUT_SACK];
1396 		if (timer_pending(timer) && del_timer(timer))
1397 			sctp_association_put(asoc);
1398 	}
1399 }
1400 
1401 /* Decrease asoc's rwnd by len. */
1402 void sctp_assoc_rwnd_decrease(struct sctp_association *asoc, unsigned len)
1403 {
1404 	SCTP_ASSERT(asoc->rwnd, "rwnd zero", return);
1405 	SCTP_ASSERT(!asoc->rwnd_over, "rwnd_over not zero", return);
1406 	if (asoc->rwnd >= len) {
1407 		asoc->rwnd -= len;
1408 	} else {
1409 		asoc->rwnd_over = len - asoc->rwnd;
1410 		asoc->rwnd = 0;
1411 	}
1412 	SCTP_DEBUG_PRINTK("%s: asoc %p rwnd decreased by %d to (%u, %u)\n",
1413 			  __FUNCTION__, asoc, len, asoc->rwnd,
1414 			  asoc->rwnd_over);
1415 }
1416 
1417 /* Build the bind address list for the association based on info from the
1418  * local endpoint and the remote peer.
1419  */
1420 int sctp_assoc_set_bind_addr_from_ep(struct sctp_association *asoc,
1421 				     gfp_t gfp)
1422 {
1423 	sctp_scope_t scope;
1424 	int flags;
1425 
1426 	/* Use scoping rules to determine the subset of addresses from
1427 	 * the endpoint.
1428 	 */
1429 	scope = sctp_scope(&asoc->peer.active_path->ipaddr);
1430 	flags = (PF_INET6 == asoc->base.sk->sk_family) ? SCTP_ADDR6_ALLOWED : 0;
1431 	if (asoc->peer.ipv4_address)
1432 		flags |= SCTP_ADDR4_PEERSUPP;
1433 	if (asoc->peer.ipv6_address)
1434 		flags |= SCTP_ADDR6_PEERSUPP;
1435 
1436 	return sctp_bind_addr_copy(&asoc->base.bind_addr,
1437 				   &asoc->ep->base.bind_addr,
1438 				   scope, gfp, flags);
1439 }
1440 
1441 /* Build the association's bind address list from the cookie.  */
1442 int sctp_assoc_set_bind_addr_from_cookie(struct sctp_association *asoc,
1443 					 struct sctp_cookie *cookie,
1444 					 gfp_t gfp)
1445 {
1446 	int var_size2 = ntohs(cookie->peer_init->chunk_hdr.length);
1447 	int var_size3 = cookie->raw_addr_list_len;
1448 	__u8 *raw = (__u8 *)cookie->peer_init + var_size2;
1449 
1450 	return sctp_raw_to_bind_addrs(&asoc->base.bind_addr, raw, var_size3,
1451 				      asoc->ep->base.bind_addr.port, gfp);
1452 }
1453 
1454 /* Lookup laddr in the bind address list of an association. */
1455 int sctp_assoc_lookup_laddr(struct sctp_association *asoc,
1456 			    const union sctp_addr *laddr)
1457 {
1458 	int found = 0;
1459 
1460 	if ((asoc->base.bind_addr.port == ntohs(laddr->v4.sin_port)) &&
1461 	    sctp_bind_addr_match(&asoc->base.bind_addr, laddr,
1462 				 sctp_sk(asoc->base.sk)))
1463 		found = 1;
1464 
1465 	return found;
1466 }
1467 
1468 /* Set an association id for a given association */
1469 int sctp_assoc_set_id(struct sctp_association *asoc, gfp_t gfp)
1470 {
1471 	int assoc_id;
1472 	int error = 0;
1473 retry:
1474 	if (unlikely(!idr_pre_get(&sctp_assocs_id, gfp)))
1475 		return -ENOMEM;
1476 
1477 	spin_lock_bh(&sctp_assocs_id_lock);
1478 	error = idr_get_new_above(&sctp_assocs_id, (void *)asoc,
1479 				    1, &assoc_id);
1480 	spin_unlock_bh(&sctp_assocs_id_lock);
1481 	if (error == -EAGAIN)
1482 		goto retry;
1483 	else if (error)
1484 		return error;
1485 
1486 	asoc->assoc_id = (sctp_assoc_t) assoc_id;
1487 	return error;
1488 }
1489 
1490 /* Free asconf_ack cache */
1491 static void sctp_assoc_free_asconf_acks(struct sctp_association *asoc)
1492 {
1493 	struct sctp_chunk *ack;
1494 	struct sctp_chunk *tmp;
1495 
1496 	list_for_each_entry_safe(ack, tmp, &asoc->asconf_ack_list,
1497 				transmitted_list) {
1498 		list_del_init(&ack->transmitted_list);
1499 		sctp_chunk_free(ack);
1500 	}
1501 }
1502 
1503 /* Clean up the ASCONF_ACK queue */
1504 void sctp_assoc_clean_asconf_ack_cache(const struct sctp_association *asoc)
1505 {
1506 	struct sctp_chunk *ack;
1507 	struct sctp_chunk *tmp;
1508 
1509 	/* We can remove all the entries from the queue upto
1510 	 * the "Peer-Sequence-Number".
1511 	 */
1512 	list_for_each_entry_safe(ack, tmp, &asoc->asconf_ack_list,
1513 				transmitted_list) {
1514 		if (ack->subh.addip_hdr->serial ==
1515 				htonl(asoc->peer.addip_serial))
1516 			break;
1517 
1518 		list_del_init(&ack->transmitted_list);
1519 		sctp_chunk_free(ack);
1520 	}
1521 }
1522 
1523 /* Find the ASCONF_ACK whose serial number matches ASCONF */
1524 struct sctp_chunk *sctp_assoc_lookup_asconf_ack(
1525 					const struct sctp_association *asoc,
1526 					__be32 serial)
1527 {
1528 	struct sctp_chunk *ack = NULL;
1529 
1530 	/* Walk through the list of cached ASCONF-ACKs and find the
1531 	 * ack chunk whose serial number matches that of the request.
1532 	 */
1533 	list_for_each_entry(ack, &asoc->asconf_ack_list, transmitted_list) {
1534 		if (ack->subh.addip_hdr->serial == serial) {
1535 			sctp_chunk_hold(ack);
1536 			break;
1537 		}
1538 	}
1539 
1540 	return ack;
1541 }
1542