1 /*-
2 * Copyright (c) 2001-2002 Packet Design, LLC.
3 * All rights reserved.
4 *
5 * Subject to the following obligations and disclaimer of warranty,
6 * use and redistribution of this software, in source or object code
7 * forms, with or without modifications are expressly permitted by
8 * Packet Design; provided, however, that:
9 *
10 * (i) Any and all reproductions of the source or object code
11 * must include the copyright notice above and the following
12 * disclaimer of warranties; and
13 * (ii) No rights are granted, in any manner or form, to use
14 * Packet Design trademarks, including the mark "PACKET DESIGN"
15 * on advertising, endorsements, or otherwise except as such
16 * appears in the above copyright notice or in the software.
17 *
18 * THIS SOFTWARE IS BEING PROVIDED BY PACKET DESIGN "AS IS", AND
19 * TO THE MAXIMUM EXTENT PERMITTED BY LAW, PACKET DESIGN MAKES NO
20 * REPRESENTATIONS OR WARRANTIES, EXPRESS OR IMPLIED, REGARDING
21 * THIS SOFTWARE, INCLUDING WITHOUT LIMITATION, ANY AND ALL IMPLIED
22 * WARRANTIES OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE,
23 * OR NON-INFRINGEMENT. PACKET DESIGN DOES NOT WARRANT, GUARANTEE,
24 * OR MAKE ANY REPRESENTATIONS REGARDING THE USE OF, OR THE RESULTS
25 * OF THE USE OF THIS SOFTWARE IN TERMS OF ITS CORRECTNESS, ACCURACY,
26 * RELIABILITY OR OTHERWISE. IN NO EVENT SHALL PACKET DESIGN BE
27 * LIABLE FOR ANY DAMAGES RESULTING FROM OR ARISING OUT OF ANY USE
28 * OF THIS SOFTWARE, INCLUDING WITHOUT LIMITATION, ANY DIRECT,
29 * INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, PUNITIVE, OR CONSEQUENTIAL
30 * DAMAGES, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES, LOSS OF
31 * USE, DATA OR PROFITS, HOWEVER CAUSED AND UNDER ANY THEORY OF
32 * LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
33 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF
34 * THE USE OF THIS SOFTWARE, EVEN IF PACKET DESIGN IS ADVISED OF
35 * THE POSSIBILITY OF SUCH DAMAGE.
36 *
37 * Author: Archie Cobbs <archie@freebsd.org>
38 *
39 * $FreeBSD: releng/8.2/sys/netgraph/ng_l2tp.c 206658 2010-04-15 12:40:02Z mav $
40 */
41
42 /*
43 * L2TP netgraph node type.
44 *
45 * This node type implements the lower layer of the
46 * L2TP protocol as specified in RFC 2661.
47 */
48
49 #include <sys/param.h>
50 #include <sys/systm.h>
51 #include <sys/kernel.h>
52 #include <sys/time.h>
53 #include <sys/conf.h>
54 #include <sys/mbuf.h>
55 #include <sys/malloc.h>
56 #include <sys/errno.h>
57 #include <sys/libkern.h>
58
59 #include <netgraph/ng_message.h>
60 #include <netgraph/netgraph.h>
61 #include <netgraph/ng_parse.h>
62 #include <netgraph/ng_l2tp.h>
63
64 #ifdef NG_SEPARATE_MALLOC
65 MALLOC_DEFINE(M_NETGRAPH_L2TP, "netgraph_l2tp", "netgraph l2tp node");
66 #else
67 #define M_NETGRAPH_L2TP M_NETGRAPH
68 #endif
69
70 /* L2TP header format (first 2 bytes only) */
71 #define L2TP_HDR_CTRL 0x8000 /* control packet */
72 #define L2TP_HDR_LEN 0x4000 /* has length field */
73 #define L2TP_HDR_SEQ 0x0800 /* has ns, nr fields */
74 #define L2TP_HDR_OFF 0x0200 /* has offset field */
75 #define L2TP_HDR_PRIO 0x0100 /* give priority */
76 #define L2TP_HDR_VERS_MASK 0x000f /* version field mask */
77 #define L2TP_HDR_VERSION 0x0002 /* version field */
78
79 /* Bits that must be zero or one in first two bytes of header */
80 #define L2TP_CTRL_0BITS 0x030d /* ctrl: must be 0 */
81 #define L2TP_CTRL_1BITS 0xc802 /* ctrl: must be 1 */
82 #define L2TP_DATA_0BITS 0x800d /* data: must be 0 */
83 #define L2TP_DATA_1BITS 0x0002 /* data: must be 1 */
84
85 /* Standard xmit ctrl and data header bits */
86 #define L2TP_CTRL_HDR (L2TP_HDR_CTRL | L2TP_HDR_LEN \
87 | L2TP_HDR_SEQ | L2TP_HDR_VERSION)
88 #define L2TP_DATA_HDR (L2TP_HDR_VERSION) /* optional: len, seq */
89
90 /* Some hard coded values */
91 #define L2TP_MAX_XWIN 128 /* my max xmit window */
92 #define L2TP_MAX_REXMIT 5 /* default max rexmit */
93 #define L2TP_MAX_REXMIT_TO 30 /* default rexmit to */
94 #define L2TP_DELAYED_ACK ((hz + 19) / 20) /* delayed ack: 50 ms */
95
96 /* Default data sequence number configuration for new sessions */
97 #define L2TP_CONTROL_DSEQ 1 /* we are the lns */
98 #define L2TP_ENABLE_DSEQ 1 /* enable data seq # */
99
100 /* Compare sequence numbers using circular math */
101 #define L2TP_SEQ_DIFF(x, y) ((int)((int16_t)(x) - (int16_t)(y)))
102
103 #define SESSHASHSIZE 0x0020
104 #define SESSHASH(x) (((x) ^ ((x) >> 8)) & (SESSHASHSIZE - 1))
105
106 /* Hook private data (data session hooks only) */
107 struct ng_l2tp_hook_private {
108 struct ng_l2tp_sess_config conf; /* hook/session config */
109 struct ng_l2tp_session_stats stats; /* per sessions statistics */
110 hook_p hook; /* hook reference */
111 u_int16_t ns; /* data ns sequence number */
112 u_int16_t nr; /* data nr sequence number */
113 LIST_ENTRY(ng_l2tp_hook_private) sessions;
114 };
115 typedef struct ng_l2tp_hook_private *hookpriv_p;
116
117 /*
118 * Sequence number state
119 *
120 * Invariants:
121 * - If cwnd < ssth, we're doing slow start, otherwise congestion avoidance
122 * - The number of unacknowledged xmit packets is (ns - rack) <= seq->wmax
123 * - The first (ns - rack) mbuf's in xwin[] array are copies of these
124 * unacknowledged packets; the remainder of xwin[] consists first of
125 * zero or more further untransmitted packets in the transmit queue
126 * - We try to keep the peer's receive window as full as possible.
127 * Therefore, (i < cwnd && xwin[i] != NULL) implies (ns - rack) > i.
128 * - rack_timer is running iff (ns - rack) > 0 (unack'd xmit'd pkts)
129 * - If xack != nr, there are unacknowledged recv packet(s) (delayed ack)
130 * - xack_timer is running iff xack != nr (unack'd rec'd pkts)
131 */
132 struct l2tp_seq {
133 u_int16_t ns; /* next xmit seq we send */
134 u_int16_t nr; /* next recv seq we expect */
135 u_int16_t inproc; /* packet is in processing */
136 u_int16_t rack; /* last 'nr' we rec'd */
137 u_int16_t xack; /* last 'nr' we sent */
138 u_int16_t wmax; /* peer's max recv window */
139 u_int16_t cwnd; /* current congestion window */
140 u_int16_t ssth; /* slow start threshold */
141 u_int16_t acks; /* # consecutive acks rec'd */
142 u_int16_t rexmits; /* # retransmits sent */
143 struct callout rack_timer; /* retransmit timer */
144 struct callout xack_timer; /* delayed ack timer */
145 struct mbuf *xwin[L2TP_MAX_XWIN]; /* transmit window */
146 struct mtx mtx; /* seq mutex */
147 };
148
149 /* Node private data */
150 struct ng_l2tp_private {
151 node_p node; /* back pointer to node */
152 hook_p ctrl; /* hook to upper layers */
153 hook_p lower; /* hook to lower layers */
154 struct ng_l2tp_config conf; /* node configuration */
155 struct ng_l2tp_stats stats; /* node statistics */
156 struct l2tp_seq seq; /* ctrl sequence number state */
157 ng_ID_t ftarget; /* failure message target */
158 LIST_HEAD(, ng_l2tp_hook_private) sesshash[SESSHASHSIZE];
159 };
160 typedef struct ng_l2tp_private *priv_p;
161
162 /* Netgraph node methods */
163 static ng_constructor_t ng_l2tp_constructor;
164 static ng_rcvmsg_t ng_l2tp_rcvmsg;
165 static ng_shutdown_t ng_l2tp_shutdown;
166 static ng_newhook_t ng_l2tp_newhook;
167 static ng_rcvdata_t ng_l2tp_rcvdata;
168 static ng_rcvdata_t ng_l2tp_rcvdata_lower;
169 static ng_rcvdata_t ng_l2tp_rcvdata_ctrl;
170 static ng_disconnect_t ng_l2tp_disconnect;
171
172 /* Internal functions */
173 static int ng_l2tp_xmit_ctrl(priv_p priv, struct mbuf *m, u_int16_t ns);
174
175 static void ng_l2tp_seq_init(priv_p priv);
176 static int ng_l2tp_seq_set(priv_p priv,
177 const struct ng_l2tp_seq_config *conf);
178 static int ng_l2tp_seq_adjust(priv_p priv,
179 const struct ng_l2tp_config *conf);
180 static void ng_l2tp_seq_reset(priv_p priv);
181 static void ng_l2tp_seq_failure(priv_p priv);
182 static void ng_l2tp_seq_recv_nr(priv_p priv, u_int16_t nr);
183 static void ng_l2tp_seq_xack_timeout(node_p node, hook_p hook,
184 void *arg1, int arg2);
185 static void ng_l2tp_seq_rack_timeout(node_p node, hook_p hook,
186 void *arg1, int arg2);
187
188 static hookpriv_p ng_l2tp_find_session(priv_p privp, u_int16_t sid);
189 static ng_fn_eachhook ng_l2tp_reset_session;
190
191 #ifdef INVARIANTS
192 static void ng_l2tp_seq_check(struct l2tp_seq *seq);
193 #endif
194
195 /* Parse type for struct ng_l2tp_seq_config. */
196 static const struct ng_parse_struct_field
197 ng_l2tp_seq_config_fields[] = NG_L2TP_SEQ_CONFIG_TYPE_INFO;
198 static const struct ng_parse_type ng_l2tp_seq_config_type = {
199 &ng_parse_struct_type,
200 &ng_l2tp_seq_config_fields
201 };
202
203 /* Parse type for struct ng_l2tp_config */
204 static const struct ng_parse_struct_field
205 ng_l2tp_config_type_fields[] = NG_L2TP_CONFIG_TYPE_INFO;
206 static const struct ng_parse_type ng_l2tp_config_type = {
207 &ng_parse_struct_type,
208 &ng_l2tp_config_type_fields,
209 };
210
211 /* Parse type for struct ng_l2tp_sess_config */
212 static const struct ng_parse_struct_field
213 ng_l2tp_sess_config_type_fields[] = NG_L2TP_SESS_CONFIG_TYPE_INFO;
214 static const struct ng_parse_type ng_l2tp_sess_config_type = {
215 &ng_parse_struct_type,
216 &ng_l2tp_sess_config_type_fields,
217 };
218
219 /* Parse type for struct ng_l2tp_stats */
220 static const struct ng_parse_struct_field
221 ng_l2tp_stats_type_fields[] = NG_L2TP_STATS_TYPE_INFO;
222 static const struct ng_parse_type ng_l2tp_stats_type = {
223 &ng_parse_struct_type,
224 &ng_l2tp_stats_type_fields
225 };
226
227 /* Parse type for struct ng_l2tp_session_stats. */
228 static const struct ng_parse_struct_field
229 ng_l2tp_session_stats_type_fields[] = NG_L2TP_SESSION_STATS_TYPE_INFO;
230 static const struct ng_parse_type ng_l2tp_session_stats_type = {
231 &ng_parse_struct_type,
232 &ng_l2tp_session_stats_type_fields
233 };
234
235 /* List of commands and how to convert arguments to/from ASCII */
236 static const struct ng_cmdlist ng_l2tp_cmdlist[] = {
237 {
238 NGM_L2TP_COOKIE,
239 NGM_L2TP_SET_CONFIG,
240 "setconfig",
241 &ng_l2tp_config_type,
242 NULL
243 },
244 {
245 NGM_L2TP_COOKIE,
246 NGM_L2TP_GET_CONFIG,
247 "getconfig",
248 NULL,
249 &ng_l2tp_config_type
250 },
251 {
252 NGM_L2TP_COOKIE,
253 NGM_L2TP_SET_SESS_CONFIG,
254 "setsessconfig",
255 &ng_l2tp_sess_config_type,
256 NULL
257 },
258 {
259 NGM_L2TP_COOKIE,
260 NGM_L2TP_GET_SESS_CONFIG,
261 "getsessconfig",
262 &ng_parse_hint16_type,
263 &ng_l2tp_sess_config_type
264 },
265 {
266 NGM_L2TP_COOKIE,
267 NGM_L2TP_GET_STATS,
268 "getstats",
269 NULL,
270 &ng_l2tp_stats_type
271 },
272 {
273 NGM_L2TP_COOKIE,
274 NGM_L2TP_CLR_STATS,
275 "clrstats",
276 NULL,
277 NULL
278 },
279 {
280 NGM_L2TP_COOKIE,
281 NGM_L2TP_GETCLR_STATS,
282 "getclrstats",
283 NULL,
284 &ng_l2tp_stats_type
285 },
286 {
287 NGM_L2TP_COOKIE,
288 NGM_L2TP_GET_SESSION_STATS,
289 "getsessstats",
290 &ng_parse_int16_type,
291 &ng_l2tp_session_stats_type
292 },
293 {
294 NGM_L2TP_COOKIE,
295 NGM_L2TP_CLR_SESSION_STATS,
296 "clrsessstats",
297 &ng_parse_int16_type,
298 NULL
299 },
300 {
301 NGM_L2TP_COOKIE,
302 NGM_L2TP_GETCLR_SESSION_STATS,
303 "getclrsessstats",
304 &ng_parse_int16_type,
305 &ng_l2tp_session_stats_type
306 },
307 {
308 NGM_L2TP_COOKIE,
309 NGM_L2TP_ACK_FAILURE,
310 "ackfailure",
311 NULL,
312 NULL
313 },
314 {
315 NGM_L2TP_COOKIE,
316 NGM_L2TP_SET_SEQ,
317 "setsequence",
318 &ng_l2tp_seq_config_type,
319 NULL
320 },
321 { 0 }
322 };
323
324 /* Node type descriptor */
325 static struct ng_type ng_l2tp_typestruct = {
326 .version = NG_ABI_VERSION,
327 .name = NG_L2TP_NODE_TYPE,
328 .constructor = ng_l2tp_constructor,
329 .rcvmsg = ng_l2tp_rcvmsg,
330 .shutdown = ng_l2tp_shutdown,
331 .newhook = ng_l2tp_newhook,
332 .rcvdata = ng_l2tp_rcvdata,
333 .disconnect = ng_l2tp_disconnect,
334 .cmdlist = ng_l2tp_cmdlist,
335 };
336 NETGRAPH_INIT(l2tp, &ng_l2tp_typestruct);
337
338 /* Sequence number state sanity checking */
339 #ifdef INVARIANTS
340 #define L2TP_SEQ_CHECK(seq) ng_l2tp_seq_check(seq)
341 #else
342 #define L2TP_SEQ_CHECK(x) do { } while (0)
343 #endif
344
345 /* Whether to use m_copypacket() or m_dup() */
346 #define L2TP_COPY_MBUF m_copypacket
347
348 #define ERROUT(x) do { error = (x); goto done; } while (0)
349
350 /************************************************************************
351 NETGRAPH NODE STUFF
352 ************************************************************************/
353
354 /*
355 * Node type constructor
356 */
357 static int
358 ng_l2tp_constructor(node_p node)
359 {
360 priv_p priv;
361 int i;
362
363 /* Allocate private structure */
364 priv = malloc(sizeof(*priv), M_NETGRAPH_L2TP, M_NOWAIT | M_ZERO);
365 if (priv == NULL)
366 return (ENOMEM);
367 NG_NODE_SET_PRIVATE(node, priv);
368 priv->node = node;
369
370 /* Apply a semi-reasonable default configuration */
371 priv->conf.peer_win = 1;
372 priv->conf.rexmit_max = L2TP_MAX_REXMIT;
373 priv->conf.rexmit_max_to = L2TP_MAX_REXMIT_TO;
374
375 /* Initialize sequence number state */
376 ng_l2tp_seq_init(priv);
377
378 for (i = 0; i < SESSHASHSIZE; i++)
379 LIST_INIT(&priv->sesshash[i]);
380
381 /* Done */
382 return (0);
383 }
384
385 /*
386 * Give our OK for a hook to be added.
387 */
388 static int
389 ng_l2tp_newhook(node_p node, hook_p hook, const char *name)
390 {
391 const priv_p priv = NG_NODE_PRIVATE(node);
392
393 /* Check hook name */
394 if (strcmp(name, NG_L2TP_HOOK_CTRL) == 0) {
395 if (priv->ctrl != NULL)
396 return (EISCONN);
397 priv->ctrl = hook;
398 NG_HOOK_SET_RCVDATA(hook, ng_l2tp_rcvdata_ctrl);
399 } else if (strcmp(name, NG_L2TP_HOOK_LOWER) == 0) {
400 if (priv->lower != NULL)
401 return (EISCONN);
402 priv->lower = hook;
403 NG_HOOK_SET_RCVDATA(hook, ng_l2tp_rcvdata_lower);
404 } else {
405 static const char hexdig[16] = "0123456789abcdef";
406 u_int16_t session_id;
407 hookpriv_p hpriv;
408 uint16_t hash;
409 const char *hex;
410 int i;
411 int j;
412
413 /* Parse hook name to get session ID */
414 if (strncmp(name, NG_L2TP_HOOK_SESSION_P,
415 sizeof(NG_L2TP_HOOK_SESSION_P) - 1) != 0)
416 return (EINVAL);
417 hex = name + sizeof(NG_L2TP_HOOK_SESSION_P) - 1;
418 for (session_id = i = 0; i < 4; i++) {
419 for (j = 0; j < 16 && hex[i] != hexdig[j]; j++);
420 if (j == 16)
421 return (EINVAL);
422 session_id = (session_id << 4) | j;
423 }
424 if (hex[i] != '\0')
425 return (EINVAL);
426
427 /* Create hook private structure */
428 hpriv = malloc(sizeof(*hpriv),
429 M_NETGRAPH_L2TP, M_NOWAIT | M_ZERO);
430 if (hpriv == NULL)
431 return (ENOMEM);
432 hpriv->conf.session_id = session_id;
433 hpriv->conf.control_dseq = L2TP_CONTROL_DSEQ;
434 hpriv->conf.enable_dseq = L2TP_ENABLE_DSEQ;
435 hpriv->hook = hook;
436 NG_HOOK_SET_PRIVATE(hook, hpriv);
437 hash = SESSHASH(hpriv->conf.session_id);
438 LIST_INSERT_HEAD(&priv->sesshash[hash], hpriv, sessions);
439 }
440
441 /* Done */
442 return (0);
443 }
444
445 /*
446 * Receive a control message.
447 */
448 static int
449 ng_l2tp_rcvmsg(node_p node, item_p item, hook_p lasthook)
450 {
451 const priv_p priv = NG_NODE_PRIVATE(node);
452 struct ng_mesg *resp = NULL;
453 struct ng_mesg *msg;
454 int error = 0;
455
456 NGI_GET_MSG(item, msg);
457 switch (msg->header.typecookie) {
458 case NGM_L2TP_COOKIE:
459 switch (msg->header.cmd) {
460 case NGM_L2TP_SET_CONFIG:
461 {
462 struct ng_l2tp_config *const conf =
463 (struct ng_l2tp_config *)msg->data;
464
465 /* Check for invalid or illegal config */
466 if (msg->header.arglen != sizeof(*conf)) {
467 error = EINVAL;
468 break;
469 }
470 conf->enabled = !!conf->enabled;
471 conf->match_id = !!conf->match_id;
472 if (priv->conf.enabled
473 && ((priv->conf.tunnel_id != 0
474 && conf->tunnel_id != priv->conf.tunnel_id)
475 || ((priv->conf.peer_id != 0
476 && conf->peer_id != priv->conf.peer_id)))) {
477 error = EBUSY;
478 break;
479 }
480
481 /* Save calling node as failure target */
482 priv->ftarget = NGI_RETADDR(item);
483
484 /* Adjust sequence number state */
485 if ((error = ng_l2tp_seq_adjust(priv, conf)) != 0)
486 break;
487
488 /* Update node's config */
489 priv->conf = *conf;
490 break;
491 }
492 case NGM_L2TP_GET_CONFIG:
493 {
494 struct ng_l2tp_config *conf;
495
496 NG_MKRESPONSE(resp, msg, sizeof(*conf), M_NOWAIT);
497 if (resp == NULL) {
498 error = ENOMEM;
499 break;
500 }
501 conf = (struct ng_l2tp_config *)resp->data;
502 *conf = priv->conf;
503 break;
504 }
505 case NGM_L2TP_SET_SESS_CONFIG:
506 {
507 struct ng_l2tp_sess_config *const conf =
508 (struct ng_l2tp_sess_config *)msg->data;
509 hookpriv_p hpriv;
510
511 /* Check for invalid or illegal config. */
512 if (msg->header.arglen != sizeof(*conf)) {
513 error = EINVAL;
514 break;
515 }
516
517 /* Find matching hook */
518 hpriv = ng_l2tp_find_session(priv, conf->session_id);
519 if (hpriv == NULL) {
520 error = ENOENT;
521 break;
522 }
523
524 /* Update hook's config */
525 hpriv->conf = *conf;
526 break;
527 }
528 case NGM_L2TP_GET_SESS_CONFIG:
529 {
530 struct ng_l2tp_sess_config *conf;
531 u_int16_t session_id;
532 hookpriv_p hpriv;
533
534 /* Get session ID */
535 if (msg->header.arglen != sizeof(session_id)) {
536 error = EINVAL;
537 break;
538 }
539 memcpy(&session_id, msg->data, 2);
540
541 /* Find matching hook */
542 hpriv = ng_l2tp_find_session(priv, session_id);
543 if (hpriv == NULL) {
544 error = ENOENT;
545 break;
546 }
547
548 /* Send response */
549 NG_MKRESPONSE(resp, msg, sizeof(hpriv->conf), M_NOWAIT);
550 if (resp == NULL) {
551 error = ENOMEM;
552 break;
553 }
554 conf = (struct ng_l2tp_sess_config *)resp->data;
555 *conf = hpriv->conf;
556 break;
557 }
558 case NGM_L2TP_GET_STATS:
559 case NGM_L2TP_CLR_STATS:
560 case NGM_L2TP_GETCLR_STATS:
561 {
562 if (msg->header.cmd != NGM_L2TP_CLR_STATS) {
563 NG_MKRESPONSE(resp, msg,
564 sizeof(priv->stats), M_NOWAIT);
565 if (resp == NULL) {
566 error = ENOMEM;
567 break;
568 }
569 memcpy(resp->data,
570 &priv->stats, sizeof(priv->stats));
571 }
572 if (msg->header.cmd != NGM_L2TP_GET_STATS)
573 memset(&priv->stats, 0, sizeof(priv->stats));
574 break;
575 }
576 case NGM_L2TP_GET_SESSION_STATS:
577 case NGM_L2TP_CLR_SESSION_STATS:
578 case NGM_L2TP_GETCLR_SESSION_STATS:
579 {
580 uint16_t session_id;
581 hookpriv_p hpriv;
582
583 /* Get session ID. */
584 if (msg->header.arglen != sizeof(session_id)) {
585 error = EINVAL;
586 break;
587 }
588 bcopy(msg->data, &session_id, sizeof(uint16_t));
589
590 /* Find matching hook. */
591 hpriv = ng_l2tp_find_session(priv, session_id);
592 if (hpriv == NULL) {
593 error = ENOENT;
594 break;
595 }
596
597 if (msg->header.cmd != NGM_L2TP_CLR_SESSION_STATS) {
598 NG_MKRESPONSE(resp, msg,
599 sizeof(hpriv->stats), M_NOWAIT);
600 if (resp == NULL) {
601 error = ENOMEM;
602 break;
603 }
604 bcopy(&hpriv->stats, resp->data,
605 sizeof(hpriv->stats));
606 }
607 if (msg->header.cmd != NGM_L2TP_GET_SESSION_STATS)
608 bzero(&hpriv->stats, sizeof(hpriv->stats));
609 break;
610 }
611 case NGM_L2TP_SET_SEQ:
612 {
613 struct ng_l2tp_seq_config *const conf =
614 (struct ng_l2tp_seq_config *)msg->data;
615
616 /* Check for invalid or illegal seq config. */
617 if (msg->header.arglen != sizeof(*conf)) {
618 error = EINVAL;
619 break;
620 }
621 conf->ns = htons(conf->ns);
622 conf->nr = htons(conf->nr);
623 conf->rack = htons(conf->rack);
624 conf->xack = htons(conf->xack);
625
626 /* Set sequence numbers. */
627 error = ng_l2tp_seq_set(priv, conf);
628 break;
629 }
630 default:
631 error = EINVAL;
632 break;
633 }
634 break;
635 default:
636 error = EINVAL;
637 break;
638 }
639
640 /* Done */
641 NG_RESPOND_MSG(error, node, item, resp);
642 NG_FREE_MSG(msg);
643 return (error);
644 }
645
646 /*
647 * Destroy node
648 */
649 static int
650 ng_l2tp_shutdown(node_p node)
651 {
652 const priv_p priv = NG_NODE_PRIVATE(node);
653 struct l2tp_seq *const seq = &priv->seq;
654
655 /* Sanity check */
656 L2TP_SEQ_CHECK(seq);
657
658 /* Reset sequence number state */
659 ng_l2tp_seq_reset(priv);
660
661 /* Free private data if neither timer is running */
662 ng_uncallout(&seq->rack_timer, node);
663 ng_uncallout(&seq->xack_timer, node);
664
665 mtx_destroy(&seq->mtx);
666
667 free(priv, M_NETGRAPH_L2TP);
668
669 /* Unref node */
670 NG_NODE_UNREF(node);
671 return (0);
672 }
673
674 /*
675 * Hook disconnection
676 */
677 static int
678 ng_l2tp_disconnect(hook_p hook)
679 {
680 const node_p node = NG_HOOK_NODE(hook);
681 const priv_p priv = NG_NODE_PRIVATE(node);
682
683 /* Zero out hook pointer */
684 if (hook == priv->ctrl)
685 priv->ctrl = NULL;
686 else if (hook == priv->lower)
687 priv->lower = NULL;
688 else {
689 const hookpriv_p hpriv = NG_HOOK_PRIVATE(hook);
690 LIST_REMOVE(hpriv, sessions);
691 free(hpriv, M_NETGRAPH_L2TP);
692 NG_HOOK_SET_PRIVATE(hook, NULL);
693 }
694
695 /* Go away if no longer connected to anything */
696 if (NG_NODE_NUMHOOKS(node) == 0 && NG_NODE_IS_VALID(node))
697 ng_rmnode_self(node);
698 return (0);
699 }
700
701 /*************************************************************************
702 INTERNAL FUNCTIONS
703 *************************************************************************/
704
705 /*
706 * Find the hook with a given session ID.
707 */
708 static hookpriv_p
709 ng_l2tp_find_session(priv_p privp, u_int16_t sid)
710 {
711 uint16_t hash = SESSHASH(sid);
712 hookpriv_p hpriv = NULL;
713
714 LIST_FOREACH(hpriv, &privp->sesshash[hash], sessions) {
715 if (hpriv->conf.session_id == sid)
716 break;
717 }
718
719 return (hpriv);
720 }
721
722 /*
723 * Reset a hook's session state.
724 */
725 static int
726 ng_l2tp_reset_session(hook_p hook, void *arg)
727 {
728 const hookpriv_p hpriv = NG_HOOK_PRIVATE(hook);
729
730 if (hpriv != NULL) {
731 hpriv->conf.control_dseq = 0;
732 hpriv->conf.enable_dseq = 0;
733 bzero(&hpriv->stats, sizeof(struct ng_l2tp_session_stats));
734 hpriv->nr = 0;
735 hpriv->ns = 0;
736 }
737 return (-1);
738 }
739
740 /*
741 * Handle an incoming frame from below.
742 */
743 static int
744 ng_l2tp_rcvdata_lower(hook_p h, item_p item)
745 {
746 static const u_int16_t req_bits[2][2] = {
747 { L2TP_DATA_0BITS, L2TP_DATA_1BITS },
748 { L2TP_CTRL_0BITS, L2TP_CTRL_1BITS },
749 };
750 const node_p node = NG_HOOK_NODE(h);
751 const priv_p priv = NG_NODE_PRIVATE(node);
752 hookpriv_p hpriv = NULL;
753 hook_p hook = NULL;
754 struct mbuf *m;
755 u_int16_t tid, sid;
756 u_int16_t hdr;
757 u_int16_t ns, nr;
758 int is_ctrl;
759 int error;
760 int len, plen;
761
762 /* Sanity check */
763 L2TP_SEQ_CHECK(&priv->seq);
764
765 /* If not configured, reject */
766 if (!priv->conf.enabled) {
767 NG_FREE_ITEM(item);
768 ERROUT(ENXIO);
769 }
770
771 /* Grab mbuf */
772 NGI_GET_M(item, m);
773
774 /* Remember full packet length; needed for per session accounting. */
775 plen = m->m_pkthdr.len;
776
777 /* Update stats */
778 priv->stats.recvPackets++;
779 priv->stats.recvOctets += plen;
780
781 /* Get initial header */
782 if (m->m_pkthdr.len < 6) {
783 priv->stats.recvRunts++;
784 NG_FREE_ITEM(item);
785 NG_FREE_M(m);
786 ERROUT(EINVAL);
787 }
788 if (m->m_len < 2 && (m = m_pullup(m, 2)) == NULL) {
789 priv->stats.memoryFailures++;
790 NG_FREE_ITEM(item);
791 ERROUT(EINVAL);
792 }
793 hdr = (mtod(m, uint8_t *)[0] << 8) + mtod(m, uint8_t *)[1];
794 m_adj(m, 2);
795
796 /* Check required header bits and minimum length */
797 is_ctrl = (hdr & L2TP_HDR_CTRL) != 0;
798 if ((hdr & req_bits[is_ctrl][0]) != 0
799 || (~hdr & req_bits[is_ctrl][1]) != 0) {
800 priv->stats.recvInvalid++;
801 NG_FREE_ITEM(item);
802 NG_FREE_M(m);
803 ERROUT(EINVAL);
804 }
805 if (m->m_pkthdr.len < 4 /* tunnel, session id */
806 + (2 * ((hdr & L2TP_HDR_LEN) != 0)) /* length field */
807 + (4 * ((hdr & L2TP_HDR_SEQ) != 0)) /* seq # fields */
808 + (2 * ((hdr & L2TP_HDR_OFF) != 0))) { /* offset field */
809 priv->stats.recvRunts++;
810 NG_FREE_ITEM(item);
811 NG_FREE_M(m);
812 ERROUT(EINVAL);
813 }
814
815 /* Get and validate length field if present */
816 if ((hdr & L2TP_HDR_LEN) != 0) {
817 if (m->m_len < 2 && (m = m_pullup(m, 2)) == NULL) {
818 priv->stats.memoryFailures++;
819 NG_FREE_ITEM(item);
820 ERROUT(EINVAL);
821 }
822 len = (mtod(m, uint8_t *)[0] << 8) + mtod(m, uint8_t *)[1] - 4;
823 m_adj(m, 2);
824 if (len < 0 || len > m->m_pkthdr.len) {
825 priv->stats.recvInvalid++;
826 NG_FREE_ITEM(item);
827 NG_FREE_M(m);
828 ERROUT(EINVAL);
829 }
830 if (len < m->m_pkthdr.len) /* trim extra bytes */
831 m_adj(m, -(m->m_pkthdr.len - len));
832 }
833
834 /* Get tunnel ID and session ID */
835 if (m->m_len < 4 && (m = m_pullup(m, 4)) == NULL) {
836 priv->stats.memoryFailures++;
837 NG_FREE_ITEM(item);
838 ERROUT(EINVAL);
839 }
840 tid = (mtod(m, u_int8_t *)[0] << 8) + mtod(m, u_int8_t *)[1];
841 sid = (mtod(m, u_int8_t *)[2] << 8) + mtod(m, u_int8_t *)[3];
842 m_adj(m, 4);
843
844 /* Check tunnel ID */
845 if (tid != priv->conf.tunnel_id &&
846 (priv->conf.match_id || tid != 0)) {
847 priv->stats.recvWrongTunnel++;
848 NG_FREE_ITEM(item);
849 NG_FREE_M(m);
850 ERROUT(EADDRNOTAVAIL);
851 }
852
853 /* Check session ID (for data packets only) */
854 if ((hdr & L2TP_HDR_CTRL) == 0) {
855 hpriv = ng_l2tp_find_session(priv, sid);
856 if (hpriv == NULL) {
857 priv->stats.recvUnknownSID++;
858 NG_FREE_ITEM(item);
859 NG_FREE_M(m);
860 ERROUT(ENOTCONN);
861 }
862 hook = hpriv->hook;
863 }
864
865 /* Get Ns, Nr fields if present */
866 if ((hdr & L2TP_HDR_SEQ) != 0) {
867 if (m->m_len < 4 && (m = m_pullup(m, 4)) == NULL) {
868 priv->stats.memoryFailures++;
869 NG_FREE_ITEM(item);
870 ERROUT(EINVAL);
871 }
872 ns = (mtod(m, u_int8_t *)[0] << 8) + mtod(m, u_int8_t *)[1];
873 nr = (mtod(m, u_int8_t *)[2] << 8) + mtod(m, u_int8_t *)[3];
874 m_adj(m, 4);
875 } else
876 ns = nr = 0;
877
878 /* Strip offset padding if present */
879 if ((hdr & L2TP_HDR_OFF) != 0) {
880 u_int16_t offset;
881
882 /* Get length of offset padding */
883 if (m->m_len < 2 && (m = m_pullup(m, 2)) == NULL) {
884 priv->stats.memoryFailures++;
885 NG_FREE_ITEM(item);
886 ERROUT(EINVAL);
887 }
888 offset = (mtod(m, u_int8_t *)[0] << 8) + mtod(m, u_int8_t *)[1];
889
890 /* Trim offset padding */
891 if ((2+offset) > m->m_pkthdr.len) {
892 priv->stats.recvInvalid++;
893 NG_FREE_ITEM(item);
894 NG_FREE_M(m);
895 ERROUT(EINVAL);
896 }
897 m_adj(m, 2+offset);
898 }
899
900 /* Handle control packets */
901 if ((hdr & L2TP_HDR_CTRL) != 0) {
902 struct l2tp_seq *const seq = &priv->seq;
903
904 /* Handle receive ack sequence number Nr */
905 ng_l2tp_seq_recv_nr(priv, nr);
906
907 /* Discard ZLB packets */
908 if (m->m_pkthdr.len == 0) {
909 priv->stats.recvZLBs++;
910 NG_FREE_ITEM(item);
911 NG_FREE_M(m);
912 ERROUT(0);
913 }
914
915 mtx_lock(&seq->mtx);
916 /*
917 * If not what we expect or we are busy, drop packet and
918 * send an immediate ZLB ack.
919 */
920 if (ns != seq->nr || seq->inproc) {
921 if (L2TP_SEQ_DIFF(ns, seq->nr) <= 0)
922 priv->stats.recvDuplicates++;
923 else
924 priv->stats.recvOutOfOrder++;
925 mtx_unlock(&seq->mtx);
926 ng_l2tp_xmit_ctrl(priv, NULL, seq->ns);
927 NG_FREE_ITEM(item);
928 NG_FREE_M(m);
929 ERROUT(0);
930 }
931 /*
932 * Until we deliver this packet we can't receive next one as
933 * we have no information for sending ack.
934 */
935 seq->inproc = 1;
936 mtx_unlock(&seq->mtx);
937
938 /* Prepend session ID to packet. */
939 M_PREPEND(m, 2, M_DONTWAIT);
940 if (m == NULL) {
941 seq->inproc = 0;
942 priv->stats.memoryFailures++;
943 NG_FREE_ITEM(item);
944 ERROUT(ENOBUFS);
945 }
946 mtod(m, u_int8_t *)[0] = sid >> 8;
947 mtod(m, u_int8_t *)[1] = sid & 0xff;
948
949 /* Deliver packet to upper layers */
950 NG_FWD_NEW_DATA(error, item, priv->ctrl, m);
951
952 mtx_lock(&seq->mtx);
953 /* Ready to process next packet. */
954 seq->inproc = 0;
955
956 /* If packet was successfully delivered send ack. */
957 if (error == 0) {
958 /* Update recv sequence number */
959 seq->nr++;
960 /* Start receive ack timer, if not already running */
961 if (!callout_active(&seq->xack_timer)) {
962 ng_callout(&seq->xack_timer, priv->node, NULL,
963 L2TP_DELAYED_ACK, ng_l2tp_seq_xack_timeout,
964 NULL, 0);
965 }
966 }
967 mtx_unlock(&seq->mtx);
968
969 ERROUT(error);
970 }
971
972 /* Per session packet, account it. */
973 hpriv->stats.recvPackets++;
974 hpriv->stats.recvOctets += plen;
975
976 /* Follow peer's lead in data sequencing, if configured to do so */
977 if (!hpriv->conf.control_dseq)
978 hpriv->conf.enable_dseq = ((hdr & L2TP_HDR_SEQ) != 0);
979
980 /* Handle data sequence numbers if present and enabled */
981 if ((hdr & L2TP_HDR_SEQ) != 0) {
982 if (hpriv->conf.enable_dseq
983 && L2TP_SEQ_DIFF(ns, hpriv->nr) < 0) {
984 NG_FREE_ITEM(item); /* duplicate or out of order */
985 NG_FREE_M(m);
986 priv->stats.recvDataDrops++;
987 ERROUT(0);
988 }
989 hpriv->nr = ns + 1;
990 }
991
992 /* Drop empty data packets */
993 if (m->m_pkthdr.len == 0) {
994 NG_FREE_ITEM(item);
995 NG_FREE_M(m);
996 ERROUT(0);
997 }
998
999 /* Deliver data */
1000 NG_FWD_NEW_DATA(error, item, hook, m);
1001 done:
1002 /* Done */
1003 L2TP_SEQ_CHECK(&priv->seq);
1004 return (error);
1005 }
1006
1007 /*
1008 * Handle an outgoing control frame.
1009 */
1010 static int
1011 ng_l2tp_rcvdata_ctrl(hook_p hook, item_p item)
1012 {
1013 const node_p node = NG_HOOK_NODE(hook);
1014 const priv_p priv = NG_NODE_PRIVATE(node);
1015 struct l2tp_seq *const seq = &priv->seq;
1016 struct mbuf *m;
1017 int error;
1018 int i;
1019 u_int16_t ns;
1020
1021 /* Sanity check */
1022 L2TP_SEQ_CHECK(&priv->seq);
1023
1024 /* If not configured, reject */
1025 if (!priv->conf.enabled) {
1026 NG_FREE_ITEM(item);
1027 ERROUT(ENXIO);
1028 }
1029
1030 /* Grab mbuf and discard other stuff XXX */
1031 NGI_GET_M(item, m);
1032 NG_FREE_ITEM(item);
1033
1034 /* Packet should have session ID prepended */
1035 if (m->m_pkthdr.len < 2) {
1036 priv->stats.xmitInvalid++;
1037 m_freem(m);
1038 ERROUT(EINVAL);
1039 }
1040
1041 /* Check max length */
1042 if (m->m_pkthdr.len >= 0x10000 - 14) {
1043 priv->stats.xmitTooBig++;
1044 m_freem(m);
1045 ERROUT(EOVERFLOW);
1046 }
1047
1048 mtx_lock(&seq->mtx);
1049
1050 /* Find next empty slot in transmit queue */
1051 for (i = 0; i < L2TP_MAX_XWIN && seq->xwin[i] != NULL; i++);
1052 if (i == L2TP_MAX_XWIN) {
1053 mtx_unlock(&seq->mtx);
1054 priv->stats.xmitDrops++;
1055 m_freem(m);
1056 ERROUT(ENOBUFS);
1057 }
1058 seq->xwin[i] = m;
1059
1060 /* If peer's receive window is already full, nothing else to do */
1061 if (i >= seq->cwnd) {
1062 mtx_unlock(&seq->mtx);
1063 ERROUT(0);
1064 }
1065
1066 /* Start retransmit timer if not already running */
1067 if (!callout_active(&seq->rack_timer))
1068 ng_callout(&seq->rack_timer, node, NULL,
1069 hz, ng_l2tp_seq_rack_timeout, NULL, 0);
1070
1071 ns = seq->ns++;
1072
1073 mtx_unlock(&seq->mtx);
1074
1075 /* Copy packet */
1076 if ((m = L2TP_COPY_MBUF(m, M_DONTWAIT)) == NULL) {
1077 priv->stats.memoryFailures++;
1078 ERROUT(ENOBUFS);
1079 }
1080
1081 /* Send packet and increment xmit sequence number */
1082 error = ng_l2tp_xmit_ctrl(priv, m, ns);
1083 done:
1084 /* Done */
1085 L2TP_SEQ_CHECK(&priv->seq);
1086 return (error);
1087 }
1088
1089 /*
1090 * Handle an outgoing data frame.
1091 */
1092 static int
1093 ng_l2tp_rcvdata(hook_p hook, item_p item)
1094 {
1095 const priv_p priv = NG_NODE_PRIVATE(NG_HOOK_NODE(hook));
1096 const hookpriv_p hpriv = NG_HOOK_PRIVATE(hook);
1097 struct mbuf *m;
1098 uint8_t *p;
1099 u_int16_t hdr;
1100 int error;
1101 int i = 2;
1102
1103 /* Sanity check */
1104 L2TP_SEQ_CHECK(&priv->seq);
1105
1106 /* If not configured, reject */
1107 if (!priv->conf.enabled) {
1108 NG_FREE_ITEM(item);
1109 ERROUT(ENXIO);
1110 }
1111
1112 /* Get mbuf */
1113 NGI_GET_M(item, m);
1114
1115 /* Check max length */
1116 if (m->m_pkthdr.len >= 0x10000 - 12) {
1117 priv->stats.xmitDataTooBig++;
1118 NG_FREE_ITEM(item);
1119 NG_FREE_M(m);
1120 ERROUT(EOVERFLOW);
1121 }
1122
1123 /* Prepend L2TP header */
1124 M_PREPEND(m, 6
1125 + (2 * (hpriv->conf.include_length != 0))
1126 + (4 * (hpriv->conf.enable_dseq != 0)),
1127 M_DONTWAIT);
1128 if (m == NULL) {
1129 priv->stats.memoryFailures++;
1130 NG_FREE_ITEM(item);
1131 ERROUT(ENOBUFS);
1132 }
1133 p = mtod(m, uint8_t *);
1134 hdr = L2TP_DATA_HDR;
1135 if (hpriv->conf.include_length) {
1136 hdr |= L2TP_HDR_LEN;
1137 p[i++] = m->m_pkthdr.len >> 8;
1138 p[i++] = m->m_pkthdr.len & 0xff;
1139 }
1140 p[i++] = priv->conf.peer_id >> 8;
1141 p[i++] = priv->conf.peer_id & 0xff;
1142 p[i++] = hpriv->conf.peer_id >> 8;
1143 p[i++] = hpriv->conf.peer_id & 0xff;
1144 if (hpriv->conf.enable_dseq) {
1145 hdr |= L2TP_HDR_SEQ;
1146 p[i++] = hpriv->ns >> 8;
1147 p[i++] = hpriv->ns & 0xff;
1148 p[i++] = hpriv->nr >> 8;
1149 p[i++] = hpriv->nr & 0xff;
1150 hpriv->ns++;
1151 }
1152 p[0] = hdr >> 8;
1153 p[1] = hdr & 0xff;
1154
1155 /* Update per session stats. */
1156 hpriv->stats.xmitPackets++;
1157 hpriv->stats.xmitOctets += m->m_pkthdr.len;
1158
1159 /* And the global one. */
1160 priv->stats.xmitPackets++;
1161 priv->stats.xmitOctets += m->m_pkthdr.len;
1162
1163 /* Send packet */
1164 NG_FWD_NEW_DATA(error, item, priv->lower, m);
1165 done:
1166 /* Done */
1167 L2TP_SEQ_CHECK(&priv->seq);
1168 return (error);
1169 }
1170
1171 /*
1172 * Send a message to our controlling node that we've failed.
1173 */
1174 static void
1175 ng_l2tp_seq_failure(priv_p priv)
1176 {
1177 struct ng_mesg *msg;
1178 int error;
1179
1180 NG_MKMESSAGE(msg, NGM_L2TP_COOKIE, NGM_L2TP_ACK_FAILURE, 0, M_NOWAIT);
1181 if (msg == NULL)
1182 return;
1183 NG_SEND_MSG_ID(error, priv->node, msg, priv->ftarget, 0);
1184 }
1185
1186 /************************************************************************
1187 SEQUENCE NUMBER HANDLING
1188 ************************************************************************/
1189
1190 /*
1191 * Initialize sequence number state.
1192 */
1193 static void
1194 ng_l2tp_seq_init(priv_p priv)
1195 {
1196 struct l2tp_seq *const seq = &priv->seq;
1197
1198 KASSERT(priv->conf.peer_win >= 1,
1199 ("%s: peer_win is zero", __func__));
1200 memset(seq, 0, sizeof(*seq));
1201 seq->cwnd = 1;
1202 seq->wmax = priv->conf.peer_win;
1203 if (seq->wmax > L2TP_MAX_XWIN)
1204 seq->wmax = L2TP_MAX_XWIN;
1205 seq->ssth = seq->wmax;
1206 ng_callout_init(&seq->rack_timer);
1207 ng_callout_init(&seq->xack_timer);
1208 mtx_init(&seq->mtx, "ng_l2tp", NULL, MTX_DEF);
1209 L2TP_SEQ_CHECK(seq);
1210 }
1211
1212 /*
1213 * Set sequence number state as given from user.
1214 */
1215 static int
1216 ng_l2tp_seq_set(priv_p priv, const struct ng_l2tp_seq_config *conf)
1217 {
1218 struct l2tp_seq *const seq = &priv->seq;
1219
1220 /* If node is enabled, deny update to sequence numbers. */
1221 if (priv->conf.enabled)
1222 return (EBUSY);
1223
1224 /* We only can handle the simple cases. */
1225 if (conf->xack != conf->nr || conf->ns != conf->rack)
1226 return (EINVAL);
1227
1228 /* Set ns,nr,rack,xack parameters. */
1229 seq->ns = conf->ns;
1230 seq->nr = conf->nr;
1231 seq->rack = conf->rack;
1232 seq->xack = conf->xack;
1233
1234 return (0);
1235 }
1236
1237 /*
1238 * Adjust sequence number state accordingly after reconfiguration.
1239 */
1240 static int
1241 ng_l2tp_seq_adjust(priv_p priv, const struct ng_l2tp_config *conf)
1242 {
1243 struct l2tp_seq *const seq = &priv->seq;
1244 u_int16_t new_wmax;
1245
1246 /* If disabling node, reset state sequence number */
1247 if (!conf->enabled) {
1248 ng_l2tp_seq_reset(priv);
1249 return (0);
1250 }
1251
1252 /* Adjust peer's max recv window; it can only increase */
1253 new_wmax = conf->peer_win;
1254 if (new_wmax > L2TP_MAX_XWIN)
1255 new_wmax = L2TP_MAX_XWIN;
1256 if (new_wmax == 0)
1257 return (EINVAL);
1258 if (new_wmax < seq->wmax)
1259 return (EBUSY);
1260 seq->wmax = new_wmax;
1261
1262 /* Done */
1263 return (0);
1264 }
1265
1266 /*
1267 * Reset sequence number state.
1268 */
1269 static void
1270 ng_l2tp_seq_reset(priv_p priv)
1271 {
1272 struct l2tp_seq *const seq = &priv->seq;
1273 hook_p hook;
1274 int i;
1275
1276 /* Sanity check */
1277 L2TP_SEQ_CHECK(seq);
1278
1279 /* Stop timers */
1280 ng_uncallout(&seq->rack_timer, priv->node);
1281 ng_uncallout(&seq->xack_timer, priv->node);
1282
1283 /* Free retransmit queue */
1284 for (i = 0; i < L2TP_MAX_XWIN; i++) {
1285 if (seq->xwin[i] == NULL)
1286 break;
1287 m_freem(seq->xwin[i]);
1288 }
1289
1290 /* Reset session hooks' sequence number states */
1291 NG_NODE_FOREACH_HOOK(priv->node, ng_l2tp_reset_session, NULL, hook);
1292
1293 /* Reset node's sequence number state */
1294 seq->ns = 0;
1295 seq->nr = 0;
1296 seq->rack = 0;
1297 seq->xack = 0;
1298 seq->wmax = L2TP_MAX_XWIN;
1299 seq->cwnd = 1;
1300 seq->ssth = seq->wmax;
1301 seq->acks = 0;
1302 seq->rexmits = 0;
1303 bzero(seq->xwin, sizeof(seq->xwin));
1304
1305 /* Done */
1306 L2TP_SEQ_CHECK(seq);
1307 }
1308
1309 /*
1310 * Handle receipt of an acknowledgement value (Nr) from peer.
1311 */
1312 static void
1313 ng_l2tp_seq_recv_nr(priv_p priv, u_int16_t nr)
1314 {
1315 struct l2tp_seq *const seq = &priv->seq;
1316 struct mbuf *xwin[L2TP_MAX_XWIN]; /* partial local copy */
1317 int nack;
1318 int i, j;
1319 uint16_t ns;
1320
1321 mtx_lock(&seq->mtx);
1322
1323 /* Verify peer's ACK is in range */
1324 if ((nack = L2TP_SEQ_DIFF(nr, seq->rack)) <= 0) {
1325 mtx_unlock(&seq->mtx);
1326 return; /* duplicate ack */
1327 }
1328 if (L2TP_SEQ_DIFF(nr, seq->ns) > 0) {
1329 mtx_unlock(&seq->mtx);
1330 priv->stats.recvBadAcks++; /* ack for packet not sent */
1331 return;
1332 }
1333 KASSERT(nack <= L2TP_MAX_XWIN,
1334 ("%s: nack=%d > %d", __func__, nack, L2TP_MAX_XWIN));
1335
1336 /* Update receive ack stats */
1337 seq->rack = nr;
1338 seq->rexmits = 0;
1339
1340 /* Free acknowledged packets and shift up packets in the xmit queue */
1341 for (i = 0; i < nack; i++)
1342 m_freem(seq->xwin[i]);
1343 memmove(seq->xwin, seq->xwin + nack,
1344 (L2TP_MAX_XWIN - nack) * sizeof(*seq->xwin));
1345 memset(seq->xwin + (L2TP_MAX_XWIN - nack), 0,
1346 nack * sizeof(*seq->xwin));
1347
1348 /*
1349 * Do slow-start/congestion avoidance windowing algorithm described
1350 * in RFC 2661, Appendix A. Here we handle a multiple ACK as if each
1351 * ACK had arrived separately.
1352 */
1353 if (seq->cwnd < seq->wmax) {
1354
1355 /* Handle slow start phase */
1356 if (seq->cwnd < seq->ssth) {
1357 seq->cwnd += nack;
1358 nack = 0;
1359 if (seq->cwnd > seq->ssth) { /* into cg.av. phase */
1360 nack = seq->cwnd - seq->ssth;
1361 seq->cwnd = seq->ssth;
1362 }
1363 }
1364
1365 /* Handle congestion avoidance phase */
1366 if (seq->cwnd >= seq->ssth) {
1367 seq->acks += nack;
1368 while (seq->acks >= seq->cwnd) {
1369 seq->acks -= seq->cwnd;
1370 if (seq->cwnd < seq->wmax)
1371 seq->cwnd++;
1372 }
1373 }
1374 }
1375
1376 /* Stop xmit timer */
1377 if (callout_active(&seq->rack_timer))
1378 ng_uncallout(&seq->rack_timer, priv->node);
1379
1380 /* If transmit queue is empty, we're done for now */
1381 if (seq->xwin[0] == NULL) {
1382 mtx_unlock(&seq->mtx);
1383 return;
1384 }
1385
1386 /* Start restransmit timer again */
1387 ng_callout(&seq->rack_timer, priv->node, NULL,
1388 hz, ng_l2tp_seq_rack_timeout, NULL, 0);
1389
1390 /*
1391 * Send more packets, trying to keep peer's receive window full.
1392 * Make copy of everything we need before lock release.
1393 */
1394 ns = seq->ns;
1395 j = 0;
1396 while ((i = L2TP_SEQ_DIFF(seq->ns, seq->rack)) < seq->cwnd
1397 && seq->xwin[i] != NULL) {
1398 xwin[j++] = seq->xwin[i];
1399 seq->ns++;
1400 }
1401
1402 mtx_unlock(&seq->mtx);
1403
1404 /*
1405 * Send prepared.
1406 * If there is a memory error, pretend packet was sent, as it
1407 * will get retransmitted later anyway.
1408 */
1409 for (i = 0; i < j; i++) {
1410 struct mbuf *m;
1411 if ((m = L2TP_COPY_MBUF(xwin[i], M_DONTWAIT)) == NULL)
1412 priv->stats.memoryFailures++;
1413 else
1414 ng_l2tp_xmit_ctrl(priv, m, ns);
1415 ns++;
1416 }
1417 }
1418
1419 /*
1420 * Handle an ack timeout. We have an outstanding ack that we
1421 * were hoping to piggy-back, but haven't, so send a ZLB.
1422 */
1423 static void
1424 ng_l2tp_seq_xack_timeout(node_p node, hook_p hook, void *arg1, int arg2)
1425 {
1426 const priv_p priv = NG_NODE_PRIVATE(node);
1427 struct l2tp_seq *const seq = &priv->seq;
1428
1429 /* Make sure callout is still active before doing anything */
1430 if (callout_pending(&seq->xack_timer) ||
1431 (!callout_active(&seq->xack_timer)))
1432 return;
1433
1434 /* Sanity check */
1435 L2TP_SEQ_CHECK(seq);
1436
1437 /* Send a ZLB */
1438 ng_l2tp_xmit_ctrl(priv, NULL, seq->ns);
1439
1440 /* callout_deactivate() is not needed here
1441 as ng_uncallout() was called by ng_l2tp_xmit_ctrl() */
1442
1443 /* Sanity check */
1444 L2TP_SEQ_CHECK(seq);
1445 }
1446
1447 /*
1448 * Handle a transmit timeout. The peer has failed to respond
1449 * with an ack for our packet, so retransmit it.
1450 */
1451 static void
1452 ng_l2tp_seq_rack_timeout(node_p node, hook_p hook, void *arg1, int arg2)
1453 {
1454 const priv_p priv = NG_NODE_PRIVATE(node);
1455 struct l2tp_seq *const seq = &priv->seq;
1456 struct mbuf *m;
1457 u_int delay;
1458
1459 /* Make sure callout is still active before doing anything */
1460 if (callout_pending(&seq->rack_timer) ||
1461 (!callout_active(&seq->rack_timer)))
1462 return;
1463
1464 /* Sanity check */
1465 L2TP_SEQ_CHECK(seq);
1466
1467 priv->stats.xmitRetransmits++;
1468
1469 /* Have we reached the retransmit limit? If so, notify owner. */
1470 if (seq->rexmits++ >= priv->conf.rexmit_max)
1471 ng_l2tp_seq_failure(priv);
1472
1473 /* Restart timer, this time with an increased delay */
1474 delay = (seq->rexmits > 12) ? (1 << 12) : (1 << seq->rexmits);
1475 if (delay > priv->conf.rexmit_max_to)
1476 delay = priv->conf.rexmit_max_to;
1477 ng_callout(&seq->rack_timer, node, NULL,
1478 hz * delay, ng_l2tp_seq_rack_timeout, NULL, 0);
1479
1480 /* Do slow-start/congestion algorithm windowing algorithm */
1481 seq->ns = seq->rack;
1482 seq->ssth = (seq->cwnd + 1) / 2;
1483 seq->cwnd = 1;
1484 seq->acks = 0;
1485
1486 /* Retransmit oldest unack'd packet */
1487 if ((m = L2TP_COPY_MBUF(seq->xwin[0], M_DONTWAIT)) == NULL)
1488 priv->stats.memoryFailures++;
1489 else
1490 ng_l2tp_xmit_ctrl(priv, m, seq->ns++);
1491
1492 /* callout_deactivate() is not needed here
1493 as ng_callout() is getting called each time */
1494
1495 /* Sanity check */
1496 L2TP_SEQ_CHECK(seq);
1497 }
1498
1499 /*
1500 * Transmit a control stream packet, payload optional.
1501 * The transmit sequence number is not incremented.
1502 */
1503 static int
1504 ng_l2tp_xmit_ctrl(priv_p priv, struct mbuf *m, u_int16_t ns)
1505 {
1506 struct l2tp_seq *const seq = &priv->seq;
1507 uint8_t *p;
1508 u_int16_t session_id = 0;
1509 int error;
1510
1511 mtx_lock(&seq->mtx);
1512
1513 /* Stop ack timer: we're sending an ack with this packet.
1514 Doing this before to keep state predictable after error. */
1515 if (callout_active(&seq->xack_timer))
1516 ng_uncallout(&seq->xack_timer, priv->node);
1517
1518 seq->xack = seq->nr;
1519
1520 mtx_unlock(&seq->mtx);
1521
1522 /* If no mbuf passed, send an empty packet (ZLB) */
1523 if (m == NULL) {
1524
1525 /* Create a new mbuf for ZLB packet */
1526 MGETHDR(m, M_DONTWAIT, MT_DATA);
1527 if (m == NULL) {
1528 priv->stats.memoryFailures++;
1529 return (ENOBUFS);
1530 }
1531 m->m_len = m->m_pkthdr.len = 12;
1532 m->m_pkthdr.rcvif = NULL;
1533 priv->stats.xmitZLBs++;
1534 } else {
1535
1536 /* Strip off session ID */
1537 if (m->m_len < 2 && (m = m_pullup(m, 2)) == NULL) {
1538 priv->stats.memoryFailures++;
1539 return (ENOBUFS);
1540 }
1541 session_id = (mtod(m, u_int8_t *)[0] << 8) + mtod(m, u_int8_t *)[1];
1542
1543 /* Make room for L2TP header */
1544 M_PREPEND(m, 10, M_DONTWAIT); /* - 2 + 12 = 10 */
1545 if (m == NULL) {
1546 priv->stats.memoryFailures++;
1547 return (ENOBUFS);
1548 }
1549 }
1550
1551 /* Fill in L2TP header */
1552 p = mtod(m, u_int8_t *);
1553 p[0] = L2TP_CTRL_HDR >> 8;
1554 p[1] = L2TP_CTRL_HDR & 0xff;
1555 p[2] = m->m_pkthdr.len >> 8;
1556 p[3] = m->m_pkthdr.len & 0xff;
1557 p[4] = priv->conf.peer_id >> 8;
1558 p[5] = priv->conf.peer_id & 0xff;
1559 p[6] = session_id >> 8;
1560 p[7] = session_id & 0xff;
1561 p[8] = ns >> 8;
1562 p[9] = ns & 0xff;
1563 p[10] = seq->nr >> 8;
1564 p[11] = seq->nr & 0xff;
1565
1566 /* Update sequence number info and stats */
1567 priv->stats.xmitPackets++;
1568 priv->stats.xmitOctets += m->m_pkthdr.len;
1569
1570 /* Send packet */
1571 NG_SEND_DATA_ONLY(error, priv->lower, m);
1572 return (error);
1573 }
1574
1575 #ifdef INVARIANTS
1576 /*
1577 * Sanity check sequence number state.
1578 */
1579 static void
1580 ng_l2tp_seq_check(struct l2tp_seq *seq)
1581 {
1582 int self_unack, peer_unack;
1583 int i;
1584
1585 #define CHECK(p) KASSERT((p), ("%s: not: %s", __func__, #p))
1586
1587 mtx_lock(&seq->mtx);
1588
1589 self_unack = L2TP_SEQ_DIFF(seq->nr, seq->xack);
1590 peer_unack = L2TP_SEQ_DIFF(seq->ns, seq->rack);
1591 CHECK(seq->wmax <= L2TP_MAX_XWIN);
1592 CHECK(seq->cwnd >= 1);
1593 CHECK(seq->cwnd <= seq->wmax);
1594 CHECK(seq->ssth >= 1);
1595 CHECK(seq->ssth <= seq->wmax);
1596 if (seq->cwnd < seq->ssth)
1597 CHECK(seq->acks == 0);
1598 else
1599 CHECK(seq->acks <= seq->cwnd);
1600 CHECK(self_unack >= 0);
1601 CHECK(peer_unack >= 0);
1602 CHECK(peer_unack <= seq->wmax);
1603 CHECK((self_unack == 0) ^ callout_active(&seq->xack_timer));
1604 CHECK((peer_unack == 0) ^ callout_active(&seq->rack_timer));
1605 for (i = 0; i < peer_unack; i++)
1606 CHECK(seq->xwin[i] != NULL);
1607 for ( ; i < seq->cwnd; i++) /* verify peer's recv window full */
1608 CHECK(seq->xwin[i] == NULL);
1609
1610 mtx_unlock(&seq->mtx);
1611
1612 #undef CHECK
1613 }
1614 #endif /* INVARIANTS */
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