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MFC r1.27:
[dragonfly.git] / sys / netgraph7 / ng_l2tp.c
blob1458e5c6720089dca43bc8fd1097de61e2904aef
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: src/sys/netgraph/ng_l2tp.c,v 1.25 2008/03/16 21:33:12 mav Exp $
40 * $DragonFly: src/sys/netgraph7/ng_l2tp.c,v 1.2 2008/06/26 23:05:35 dillon Exp $
41 */
42
43 /*
44 * L2TP netgraph node type.
45 *
46 * This node type implements the lower layer of the
47 * L2TP protocol as specified in RFC 2661.
48 */
49
50 #include <sys/param.h>
51 #include <sys/systm.h>
52 #include <sys/kernel.h>
53 #include <sys/time.h>
54 #include <sys/conf.h>
55 #include <sys/mbuf.h>
56 #include <sys/malloc.h>
57 #include <sys/errno.h>
58 #include <sys/libkern.h>
59
60 #include "ng_message.h"
61 #include "netgraph.h"
62 #include "ng_parse.h"
63 #include "ng_l2tp.h"
64
65 #ifdef NG_SEPARATE_MALLOC
66 MALLOC_DEFINE(M_NETGRAPH_L2TP, "netgraph_l2tp", "netgraph l2tp node");
67 #else
68 #define M_NETGRAPH_L2TP M_NETGRAPH
69 #endif
70
71 /* L2TP header format (first 2 bytes only) */
72 #define L2TP_HDR_CTRL 0x8000 /* control packet */
73 #define L2TP_HDR_LEN 0x4000 /* has length field */
74 #define L2TP_HDR_SEQ 0x0800 /* has ns, nr fields */
75 #define L2TP_HDR_OFF 0x0200 /* has offset field */
76 #define L2TP_HDR_PRIO 0x0100 /* give priority */
77 #define L2TP_HDR_VERS_MASK 0x000f /* version field mask */
78 #define L2TP_HDR_VERSION 0x0002 /* version field */
79
80 /* Bits that must be zero or one in first two bytes of header */
81 #define L2TP_CTRL_0BITS 0x030d /* ctrl: must be 0 */
82 #define L2TP_CTRL_1BITS 0xc802 /* ctrl: must be 1 */
83 #define L2TP_DATA_0BITS 0x800d /* data: must be 0 */
84 #define L2TP_DATA_1BITS 0x0002 /* data: must be 1 */
85
86 /* Standard xmit ctrl and data header bits */
87 #define L2TP_CTRL_HDR (L2TP_HDR_CTRL | L2TP_HDR_LEN \
88 | L2TP_HDR_SEQ | L2TP_HDR_VERSION)
89 #define L2TP_DATA_HDR (L2TP_HDR_VERSION) /* optional: len, seq */
90
91 /* Some hard coded values */
92 #define L2TP_MAX_XWIN 128 /* my max xmit window */
93 #define L2TP_MAX_REXMIT 5 /* default max rexmit */
94 #define L2TP_MAX_REXMIT_TO 30 /* default rexmit to */
95 #define L2TP_DELAYED_ACK ((hz + 19) / 20) /* delayed ack: 50 ms */
96
97 /* Default data sequence number configuration for new sessions */
98 #define L2TP_CONTROL_DSEQ 1 /* we are the lns */
99 #define L2TP_ENABLE_DSEQ 1 /* enable data seq # */
100
101 /* Compare sequence numbers using circular math */
102 #define L2TP_SEQ_DIFF(x, y) ((int)((int16_t)(x) - (int16_t)(y)))
103
104 #define SESSHASHSIZE 0x0020
105 #define SESSHASH(x) (((x) ^ ((x) >> 8)) & (SESSHASHSIZE - 1))
106
107 /* Hook private data (data session hooks only) */
108 struct ng_l2tp_hook_private {
109 struct ng_l2tp_sess_config conf; /* hook/session config */
110 struct ng_l2tp_session_stats stats; /* per sessions statistics */
111 hook_p hook; /* hook reference */
112 u_int16_t ns; /* data ns sequence number */
113 u_int16_t nr; /* data nr sequence number */
114 LIST_ENTRY(ng_l2tp_hook_private) sessions;
115 };
116 typedef struct ng_l2tp_hook_private *hookpriv_p;
117
118 /*
119 * Sequence number state
120 *
121 * Invariants:
122 * - If cwnd < ssth, we're doing slow start, otherwise congestion avoidance
123 * - The number of unacknowledged xmit packets is (ns - rack) <= seq->wmax
124 * - The first (ns - rack) mbuf's in xwin[] array are copies of these
125 * unacknowledged packets; the remainder of xwin[] consists first of
126 * zero or more further untransmitted packets in the transmit queue
127 * - We try to keep the peer's receive window as full as possible.
128 * Therefore, (i < cwnd && xwin[i] != NULL) implies (ns - rack) > i.
129 * - rack_timer is running iff (ns - rack) > 0 (unack'd xmit'd pkts)
130 * - If xack != nr, there are unacknowledged recv packet(s) (delayed ack)
131 * - xack_timer is running iff xack != nr (unack'd rec'd pkts)
132 */
133 struct l2tp_seq {
134 u_int16_t ns; /* next xmit seq we send */
135 u_int16_t nr; /* next recv seq we expect */
136 u_int16_t inproc; /* packet is in processing */
137 u_int16_t rack; /* last 'nr' we rec'd */
138 u_int16_t xack; /* last 'nr' we sent */
139 u_int16_t wmax; /* peer's max recv window */
140 u_int16_t cwnd; /* current congestion window */
141 u_int16_t ssth; /* slow start threshold */
142 u_int16_t acks; /* # consecutive acks rec'd */
143 u_int16_t rexmits; /* # retransmits sent */
144 struct callout rack_timer; /* retransmit timer */
145 struct callout xack_timer; /* delayed ack timer */
146 struct mbuf *xwin[L2TP_MAX_XWIN]; /* transmit window */
147 struct mtx mtx; /* seq mutex */
148 };
149
150 /* Node private data */
151 struct ng_l2tp_private {
152 node_p node; /* back pointer to node */
153 hook_p ctrl; /* hook to upper layers */
154 hook_p lower; /* hook to lower layers */
155 struct ng_l2tp_config conf; /* node configuration */
156 struct ng_l2tp_stats stats; /* node statistics */
157 struct l2tp_seq seq; /* ctrl sequence number state */
158 ng_ID_t ftarget; /* failure message target */
159 LIST_HEAD(, ng_l2tp_hook_private) sesshash[SESSHASHSIZE];
160 };
161 typedef struct ng_l2tp_private *priv_p;
162
163 /* Netgraph node methods */
164 static ng_constructor_t ng_l2tp_constructor;
165 static ng_rcvmsg_t ng_l2tp_rcvmsg;
166 static ng_shutdown_t ng_l2tp_shutdown;
167 static ng_newhook_t ng_l2tp_newhook;
168 static ng_rcvdata_t ng_l2tp_rcvdata;
169 static ng_rcvdata_t ng_l2tp_rcvdata_lower;
170 static ng_rcvdata_t ng_l2tp_rcvdata_ctrl;
171 static ng_disconnect_t ng_l2tp_disconnect;
172
173 /* Internal functions */
174 static int ng_l2tp_xmit_ctrl(priv_p priv, struct mbuf *m, u_int16_t ns);
175
176 static void ng_l2tp_seq_init(priv_p priv);
177 static int ng_l2tp_seq_set(priv_p priv,
178 const struct ng_l2tp_seq_config *conf);
179 static int ng_l2tp_seq_adjust(priv_p priv,
180 const struct ng_l2tp_config *conf);
181 static void ng_l2tp_seq_reset(priv_p priv);
182 static void ng_l2tp_seq_failure(priv_p priv);
183 static void ng_l2tp_seq_recv_nr(priv_p priv, u_int16_t nr);
184 static void ng_l2tp_seq_xack_timeout(node_p node, hook_p hook,
185 void *arg1, int arg2);
186 static void ng_l2tp_seq_rack_timeout(node_p node, hook_p hook,
187 void *arg1, int arg2);
188
189 static hookpriv_p ng_l2tp_find_session(priv_p privp, u_int16_t sid);
190 static ng_fn_eachhook ng_l2tp_reset_session;
191
192 #ifdef INVARIANTS
193 static void ng_l2tp_seq_check(struct l2tp_seq *seq);
194 #endif
195
196 /* Parse type for struct ng_l2tp_seq_config. */
197 static const struct ng_parse_struct_field
198 ng_l2tp_seq_config_fields[] = NG_L2TP_SEQ_CONFIG_TYPE_INFO;
199 static const struct ng_parse_type ng_l2tp_seq_config_type = {
200 &ng_parse_struct_type,
201 &ng_l2tp_seq_config_fields
202 };
203
204 /* Parse type for struct ng_l2tp_config */
205 static const struct ng_parse_struct_field
206 ng_l2tp_config_type_fields[] = NG_L2TP_CONFIG_TYPE_INFO;
207 static const struct ng_parse_type ng_l2tp_config_type = {
208 &ng_parse_struct_type,
209 &ng_l2tp_config_type_fields,
210 };
211
212 /* Parse type for struct ng_l2tp_sess_config */
213 static const struct ng_parse_struct_field
214 ng_l2tp_sess_config_type_fields[] = NG_L2TP_SESS_CONFIG_TYPE_INFO;
215 static const struct ng_parse_type ng_l2tp_sess_config_type = {
216 &ng_parse_struct_type,
217 &ng_l2tp_sess_config_type_fields,
218 };
219
220 /* Parse type for struct ng_l2tp_stats */
221 static const struct ng_parse_struct_field
222 ng_l2tp_stats_type_fields[] = NG_L2TP_STATS_TYPE_INFO;
223 static const struct ng_parse_type ng_l2tp_stats_type = {
224 &ng_parse_struct_type,
225 &ng_l2tp_stats_type_fields
226 };
227
228 /* Parse type for struct ng_l2tp_session_stats. */
229 static const struct ng_parse_struct_field
230 ng_l2tp_session_stats_type_fields[] = NG_L2TP_SESSION_STATS_TYPE_INFO;
231 static const struct ng_parse_type ng_l2tp_session_stats_type = {
232 &ng_parse_struct_type,
233 &ng_l2tp_session_stats_type_fields
234 };
235
236 /* List of commands and how to convert arguments to/from ASCII */
237 static const struct ng_cmdlist ng_l2tp_cmdlist[] = {
238 {
239 NGM_L2TP_COOKIE,
240 NGM_L2TP_SET_CONFIG,
241 "setconfig",
242 &ng_l2tp_config_type,
243 NULL
244 },
245 {
246 NGM_L2TP_COOKIE,
247 NGM_L2TP_GET_CONFIG,
248 "getconfig",
249 NULL,
250 &ng_l2tp_config_type
251 },
252 {
253 NGM_L2TP_COOKIE,
254 NGM_L2TP_SET_SESS_CONFIG,
255 "setsessconfig",
256 &ng_l2tp_sess_config_type,
257 NULL
258 },
259 {
260 NGM_L2TP_COOKIE,
261 NGM_L2TP_GET_SESS_CONFIG,
262 "getsessconfig",
263 &ng_parse_hint16_type,
264 &ng_l2tp_sess_config_type
265 },
266 {
267 NGM_L2TP_COOKIE,
268 NGM_L2TP_GET_STATS,
269 "getstats",
270 NULL,
271 &ng_l2tp_stats_type
272 },
273 {
274 NGM_L2TP_COOKIE,
275 NGM_L2TP_CLR_STATS,
276 "clrstats",
277 NULL,
278 NULL
279 },
280 {
281 NGM_L2TP_COOKIE,
282 NGM_L2TP_GETCLR_STATS,
283 "getclrstats",
284 NULL,
285 &ng_l2tp_stats_type
286 },
287 {
288 NGM_L2TP_COOKIE,
289 NGM_L2TP_GET_SESSION_STATS,
290 "getsessstats",
291 &ng_parse_int16_type,
292 &ng_l2tp_session_stats_type
293 },
294 {
295 NGM_L2TP_COOKIE,
296 NGM_L2TP_CLR_SESSION_STATS,
297 "clrsessstats",
298 &ng_parse_int16_type,
299 NULL
300 },
301 {
302 NGM_L2TP_COOKIE,
303 NGM_L2TP_GETCLR_SESSION_STATS,
304 "getclrsessstats",
305 &ng_parse_int16_type,
306 &ng_l2tp_session_stats_type
307 },
308 {
309 NGM_L2TP_COOKIE,
310 NGM_L2TP_ACK_FAILURE,
311 "ackfailure",
312 NULL,
313 NULL
314 },
315 {
316 NGM_L2TP_COOKIE,
317 NGM_L2TP_SET_SEQ,
318 "setsequence",
319 &ng_l2tp_seq_config_type,
320 NULL
321 },
322 { 0 }
323 };
324
325 /* Node type descriptor */
326 static struct ng_type ng_l2tp_typestruct = {
327 .version = NG_ABI_VERSION,
328 .name = NG_L2TP_NODE_TYPE,
329 .constructor = ng_l2tp_constructor,
330 .rcvmsg = ng_l2tp_rcvmsg,
331 .shutdown = ng_l2tp_shutdown,
332 .newhook = ng_l2tp_newhook,
333 .rcvdata = ng_l2tp_rcvdata,
334 .disconnect = ng_l2tp_disconnect,
335 .cmdlist = ng_l2tp_cmdlist,
336 };
337 NETGRAPH_INIT(l2tp, &ng_l2tp_typestruct);
338
339 /* Sequence number state sanity checking */
340 #ifdef INVARIANTS
341 #define L2TP_SEQ_CHECK(seq) ng_l2tp_seq_check(seq)
342 #else
343 #define L2TP_SEQ_CHECK(x) do { } while (0)
344 #endif
345
346 /* memmove macro */
347 #define memmove(d, s, l) bcopy(s, d, l)
348
349 /* Whether to use m_copypacket() or m_dup() */
350 #define L2TP_COPY_MBUF m_copypacket
351
352 #define ERROUT(x) do { error = (x); goto done; } while (0)
353
354 /************************************************************************
355 NETGRAPH NODE STUFF
356 ************************************************************************/
357
358 /*
359 * Node type constructor
360 */
361 static int
362 ng_l2tp_constructor(node_p node)
363 {
364 priv_p priv;
365 int i;
366
367 /* Allocate private structure */
368 MALLOC(priv, priv_p, sizeof(*priv), M_NETGRAPH_L2TP, M_WAITOK | M_NULLOK | M_ZERO);
369 if (priv == NULL)
370 return (ENOMEM);
371 NG_NODE_SET_PRIVATE(node, priv);
372 priv->node = node;
373
374 /* Apply a semi-reasonable default configuration */
375 priv->conf.peer_win = 1;
376 priv->conf.rexmit_max = L2TP_MAX_REXMIT;
377 priv->conf.rexmit_max_to = L2TP_MAX_REXMIT_TO;
378
379 /* Initialize sequence number state */
380 ng_l2tp_seq_init(priv);
381
382 for (i = 0; i < SESSHASHSIZE; i++)
383 LIST_INIT(&priv->sesshash[i]);
384
385 /* Done */
386 return (0);
387 }
388
389 /*
390 * Give our OK for a hook to be added.
391 */
392 static int
393 ng_l2tp_newhook(node_p node, hook_p hook, const char *name)
394 {
395 const priv_p priv = NG_NODE_PRIVATE(node);
396
397 /* Check hook name */
398 if (strcmp(name, NG_L2TP_HOOK_CTRL) == 0) {
399 if (priv->ctrl != NULL)
400 return (EISCONN);
401 priv->ctrl = hook;
402 NG_HOOK_SET_RCVDATA(hook, ng_l2tp_rcvdata_ctrl);
403 } else if (strcmp(name, NG_L2TP_HOOK_LOWER) == 0) {
404 if (priv->lower != NULL)
405 return (EISCONN);
406 priv->lower = hook;
407 NG_HOOK_SET_RCVDATA(hook, ng_l2tp_rcvdata_lower);
408 } else {
409 static const char hexdig[16] = "0123456789abcdef";
410 u_int16_t session_id;
411 hookpriv_p hpriv;
412 uint16_t hash;
413 const char *hex;
414 int i;
415 int j;
416
417 /* Parse hook name to get session ID */
418 if (strncmp(name, NG_L2TP_HOOK_SESSION_P,
419 sizeof(NG_L2TP_HOOK_SESSION_P) - 1) != 0)
420 return (EINVAL);
421 hex = name + sizeof(NG_L2TP_HOOK_SESSION_P) - 1;
422 for (session_id = i = 0; i < 4; i++) {
423 for (j = 0; j < 16 && hex[i] != hexdig[j]; j++);
424 if (j == 16)
425 return (EINVAL);
426 session_id = (session_id << 4) | j;
427 }
428 if (hex[i] != '\0')
429 return (EINVAL);
430
431 /* Create hook private structure */
432 MALLOC(hpriv, hookpriv_p,
433 sizeof(*hpriv), M_NETGRAPH_L2TP, M_WAITOK | M_NULLOK | M_ZERO);
434 if (hpriv == NULL)
435 return (ENOMEM);
436 hpriv->conf.session_id = htons(session_id);
437 hpriv->conf.control_dseq = L2TP_CONTROL_DSEQ;
438 hpriv->conf.enable_dseq = L2TP_ENABLE_DSEQ;
439 hpriv->hook = hook;
440 NG_HOOK_SET_PRIVATE(hook, hpriv);
441 hash = SESSHASH(hpriv->conf.session_id);
442 LIST_INSERT_HEAD(&priv->sesshash[hash], hpriv, sessions);
443 }
444
445 /* Done */
446 return (0);
447 }
448
449 /*
450 * Receive a control message.
451 */
452 static int
453 ng_l2tp_rcvmsg(node_p node, item_p item, hook_p lasthook)
454 {
455 const priv_p priv = NG_NODE_PRIVATE(node);
456 struct ng_mesg *resp = NULL;
457 struct ng_mesg *msg;
458 int error = 0;
459
460 NGI_GET_MSG(item, msg);
461 switch (msg->header.typecookie) {
462 case NGM_L2TP_COOKIE:
463 switch (msg->header.cmd) {
464 case NGM_L2TP_SET_CONFIG:
465 {
466 struct ng_l2tp_config *const conf =
467 (struct ng_l2tp_config *)msg->data;
468
469 /* Check for invalid or illegal config */
470 if (msg->header.arglen != sizeof(*conf)) {
471 error = EINVAL;
472 break;
473 }
474 conf->enabled = !!conf->enabled;
475 conf->match_id = !!conf->match_id;
476 conf->tunnel_id = htons(conf->tunnel_id);
477 conf->peer_id = htons(conf->peer_id);
478 if (priv->conf.enabled
479 && ((priv->conf.tunnel_id != 0
480 && conf->tunnel_id != priv->conf.tunnel_id)
481 || ((priv->conf.peer_id != 0
482 && conf->peer_id != priv->conf.peer_id)))) {
483 error = EBUSY;
484 break;
485 }
486
487 /* Save calling node as failure target */
488 priv->ftarget = NGI_RETADDR(item);
489
490 /* Adjust sequence number state */
491 if ((error = ng_l2tp_seq_adjust(priv, conf)) != 0)
492 break;
493
494 /* Update node's config */
495 priv->conf = *conf;
496 break;
497 }
498 case NGM_L2TP_GET_CONFIG:
499 {
500 struct ng_l2tp_config *conf;
501
502 NG_MKRESPONSE(resp, msg, sizeof(*conf), M_WAITOK | M_NULLOK);
503 if (resp == NULL) {
504 error = ENOMEM;
505 break;
506 }
507 conf = (struct ng_l2tp_config *)resp->data;
508 *conf = priv->conf;
509
510 /* Put ID's in host order */
511 conf->tunnel_id = ntohs(conf->tunnel_id);
512 conf->peer_id = ntohs(conf->peer_id);
513 break;
514 }
515 case NGM_L2TP_SET_SESS_CONFIG:
516 {
517 struct ng_l2tp_sess_config *const conf =
518 (struct ng_l2tp_sess_config *)msg->data;
519 hookpriv_p hpriv;
520
521 /* Check for invalid or illegal config. */
522 if (msg->header.arglen != sizeof(*conf)) {
523 error = EINVAL;
524 break;
525 }
526
527 /* Put ID's in network order */
528 conf->session_id = htons(conf->session_id);
529 conf->peer_id = htons(conf->peer_id);
530
531 /* Find matching hook */
532 hpriv = ng_l2tp_find_session(priv, conf->session_id);
533 if (hpriv == NULL) {
534 error = ENOENT;
535 break;
536 }
537
538 /* Update hook's config */
539 hpriv->conf = *conf;
540 break;
541 }
542 case NGM_L2TP_GET_SESS_CONFIG:
543 {
544 struct ng_l2tp_sess_config *conf;
545 u_int16_t session_id;
546 hookpriv_p hpriv;
547
548 /* Get session ID */
549 if (msg->header.arglen != sizeof(session_id)) {
550 error = EINVAL;
551 break;
552 }
553 memcpy(&session_id, msg->data, 2);
554 session_id = htons(session_id);
555
556 /* Find matching hook */
557 hpriv = ng_l2tp_find_session(priv, session_id);
558 if (hpriv == NULL) {
559 error = ENOENT;
560 break;
561 }
562
563 /* Send response */
564 NG_MKRESPONSE(resp, msg, sizeof(hpriv->conf), M_WAITOK | M_NULLOK);
565 if (resp == NULL) {
566 error = ENOMEM;
567 break;
568 }
569 conf = (struct ng_l2tp_sess_config *)resp->data;
570 *conf = hpriv->conf;
571
572 /* Put ID's in host order */
573 conf->session_id = ntohs(conf->session_id);
574 conf->peer_id = ntohs(conf->peer_id);
575 break;
576 }
577 case NGM_L2TP_GET_STATS:
578 case NGM_L2TP_CLR_STATS:
579 case NGM_L2TP_GETCLR_STATS:
580 {
581 if (msg->header.cmd != NGM_L2TP_CLR_STATS) {
582 NG_MKRESPONSE(resp, msg,
583 sizeof(priv->stats), M_WAITOK | M_NULLOK);
584 if (resp == NULL) {
585 error = ENOMEM;
586 break;
587 }
588 memcpy(resp->data,
589 &priv->stats, sizeof(priv->stats));
590 }
591 if (msg->header.cmd != NGM_L2TP_GET_STATS)
592 memset(&priv->stats, 0, sizeof(priv->stats));
593 break;
594 }
595 case NGM_L2TP_GET_SESSION_STATS:
596 case NGM_L2TP_CLR_SESSION_STATS:
597 case NGM_L2TP_GETCLR_SESSION_STATS:
598 {
599 uint16_t session_id;
600 hookpriv_p hpriv;
601
602 /* Get session ID. */
603 if (msg->header.arglen != sizeof(session_id)) {
604 error = EINVAL;
605 break;
606 }
607 bcopy(msg->data, &session_id, sizeof(uint16_t));
608 session_id = htons(session_id);
609
610 /* Find matching hook. */
611 hpriv = ng_l2tp_find_session(priv, session_id);
612 if (hpriv == NULL) {
613 error = ENOENT;
614 break;
615 }
616
617 if (msg->header.cmd != NGM_L2TP_CLR_SESSION_STATS) {
618 NG_MKRESPONSE(resp, msg,
619 sizeof(hpriv->stats), M_WAITOK | M_NULLOK);
620 if (resp == NULL) {
621 error = ENOMEM;
622 break;
623 }
624 bcopy(&hpriv->stats, resp->data,
625 sizeof(hpriv->stats));
626 }
627 if (msg->header.cmd != NGM_L2TP_GET_SESSION_STATS)
628 bzero(&hpriv->stats, sizeof(hpriv->stats));
629 break;
630 }
631 case NGM_L2TP_SET_SEQ:
632 {
633 struct ng_l2tp_seq_config *const conf =
634 (struct ng_l2tp_seq_config *)msg->data;
635
636 /* Check for invalid or illegal seq config. */
637 if (msg->header.arglen != sizeof(*conf)) {
638 error = EINVAL;
639 break;
640 }
641 conf->ns = htons(conf->ns);
642 conf->nr = htons(conf->nr);
643 conf->rack = htons(conf->rack);
644 conf->xack = htons(conf->xack);
645
646 /* Set sequence numbers. */
647 error = ng_l2tp_seq_set(priv, conf);
648 break;
649 }
650 default:
651 error = EINVAL;
652 break;
653 }
654 break;
655 default:
656 error = EINVAL;
657 break;
658 }
659
660 /* Done */
661 NG_RESPOND_MSG(error, node, item, resp);
662 NG_FREE_MSG(msg);
663 return (error);
664 }
665
666 /*
667 * Destroy node
668 */
669 static int
670 ng_l2tp_shutdown(node_p node)
671 {
672 const priv_p priv = NG_NODE_PRIVATE(node);
673 struct l2tp_seq *const seq = &priv->seq;
674
675 /* Sanity check */
676 L2TP_SEQ_CHECK(seq);
677
678 /* Reset sequence number state */
679 ng_l2tp_seq_reset(priv);
680
681 /* Free private data if neither timer is running */
682 ng_uncallout(&seq->rack_timer, node);
683 ng_uncallout(&seq->xack_timer, node);
684
685 mtx_destroy(&seq->mtx);
686
687 FREE(priv, M_NETGRAPH_L2TP);
688
689 /* Unref node */
690 NG_NODE_UNREF(node);
691 return (0);
692 }
693
694 /*
695 * Hook disconnection
696 */
697 static int
698 ng_l2tp_disconnect(hook_p hook)
699 {
700 const node_p node = NG_HOOK_NODE(hook);
701 const priv_p priv = NG_NODE_PRIVATE(node);
702
703 /* Zero out hook pointer */
704 if (hook == priv->ctrl)
705 priv->ctrl = NULL;
706 else if (hook == priv->lower)
707 priv->lower = NULL;
708 else {
709 const hookpriv_p hpriv = NG_HOOK_PRIVATE(hook);
710 LIST_REMOVE(hpriv, sessions);
711 FREE(hpriv, M_NETGRAPH_L2TP);
712 NG_HOOK_SET_PRIVATE(hook, NULL);
713 }
714
715 /* Go away if no longer connected to anything */
716 if (NG_NODE_NUMHOOKS(node) == 0 && NG_NODE_IS_VALID(node))
717 ng_rmnode_self(node);
718 return (0);
719 }
720
721 /*************************************************************************
722 INTERNAL FUNCTIONS
723 *************************************************************************/
724
725 /*
726 * Find the hook with a given session ID (in network order).
727 */
728 static hookpriv_p
729 ng_l2tp_find_session(priv_p privp, u_int16_t sid)
730 {
731 uint16_t hash = SESSHASH(sid);
732 hookpriv_p hpriv = NULL;
733
734 LIST_FOREACH(hpriv, &privp->sesshash[hash], sessions) {
735 if (hpriv->conf.session_id == sid)
736 break;
737 }
738
739 return (hpriv);
740 }
741
742 /*
743 * Reset a hook's session state.
744 */
745 static int
746 ng_l2tp_reset_session(hook_p hook, void *arg)
747 {
748 const hookpriv_p hpriv = NG_HOOK_PRIVATE(hook);
749
750 if (hpriv != NULL) {
751 hpriv->conf.control_dseq = 0;
752 hpriv->conf.enable_dseq = 0;
753 bzero(&hpriv->conf, sizeof(struct ng_l2tp_session_stats));
754 hpriv->nr = 0;
755 hpriv->ns = 0;
756 }
757 return (-1);
758 }
759
760 /*
761 * Handle an incoming frame from below.
762 */
763 static int
764 ng_l2tp_rcvdata_lower(hook_p h, item_p item)
765 {
766 static const u_int16_t req_bits[2][2] = {
767 { L2TP_DATA_0BITS, L2TP_DATA_1BITS },
768 { L2TP_CTRL_0BITS, L2TP_CTRL_1BITS },
769 };
770 const node_p node = NG_HOOK_NODE(h);
771 const priv_p priv = NG_NODE_PRIVATE(node);
772 hookpriv_p hpriv = NULL;
773 hook_p hook = NULL;
774 u_int16_t ids[2];
775 struct mbuf *m;
776 u_int16_t hdr;
777 u_int16_t ns;
778 u_int16_t nr;
779 int is_ctrl;
780 int error;
781 int len, plen;
782
783 /* Sanity check */
784 L2TP_SEQ_CHECK(&priv->seq);
785
786 /* If not configured, reject */
787 if (!priv->conf.enabled) {
788 NG_FREE_ITEM(item);
789 ERROUT(ENXIO);
790 }
791
792 /* Grab mbuf */
793 NGI_GET_M(item, m);
794
795 /* Remember full packet length; needed for per session accounting. */
796 plen = m->m_pkthdr.len;
797
798 /* Update stats */
799 priv->stats.recvPackets++;
800 priv->stats.recvOctets += plen;
801
802 /* Get initial header */
803 if (m->m_pkthdr.len < 6) {
804 priv->stats.recvRunts++;
805 NG_FREE_ITEM(item);
806 NG_FREE_M(m);
807 ERROUT(EINVAL);
808 }
809 if (m->m_len < 2 && (m = m_pullup(m, 2)) == NULL) {
810 priv->stats.memoryFailures++;
811 NG_FREE_ITEM(item);
812 ERROUT(EINVAL);
813 }
814 hdr = ntohs(*mtod(m, u_int16_t *));
815 m_adj(m, 2);
816
817 /* Check required header bits and minimum length */
818 is_ctrl = (hdr & L2TP_HDR_CTRL) != 0;
819 if ((hdr & req_bits[is_ctrl][0]) != 0
820 || (~hdr & req_bits[is_ctrl][1]) != 0) {
821 priv->stats.recvInvalid++;
822 NG_FREE_ITEM(item);
823 NG_FREE_M(m);
824 ERROUT(EINVAL);
825 }
826 if (m->m_pkthdr.len < 4 /* tunnel, session id */
827 + (2 * ((hdr & L2TP_HDR_LEN) != 0)) /* length field */
828 + (4 * ((hdr & L2TP_HDR_SEQ) != 0)) /* seq # fields */
829 + (2 * ((hdr & L2TP_HDR_OFF) != 0))) { /* offset field */
830 priv->stats.recvRunts++;
831 NG_FREE_ITEM(item);
832 NG_FREE_M(m);
833 ERROUT(EINVAL);
834 }
835
836 /* Get and validate length field if present */
837 if ((hdr & L2TP_HDR_LEN) != 0) {
838 if (m->m_len < 2 && (m = m_pullup(m, 2)) == NULL) {
839 priv->stats.memoryFailures++;
840 NG_FREE_ITEM(item);
841 ERROUT(EINVAL);
842 }
843 len = (u_int16_t)ntohs(*mtod(m, u_int16_t *)) - 4;
844 m_adj(m, 2);
845 if (len < 0 || len > m->m_pkthdr.len) {
846 priv->stats.recvInvalid++;
847 NG_FREE_ITEM(item);
848 NG_FREE_M(m);
849 ERROUT(EINVAL);
850 }
851 if (len < m->m_pkthdr.len) /* trim extra bytes */
852 m_adj(m, -(m->m_pkthdr.len - len));
853 }
854
855 /* Get tunnel ID and session ID */
856 if (m->m_len < 4 && (m = m_pullup(m, 4)) == NULL) {
857 priv->stats.memoryFailures++;
858 NG_FREE_ITEM(item);
859 ERROUT(EINVAL);
860 }
861 memcpy(ids, mtod(m, u_int16_t *), 4);
862 m_adj(m, 4);
863
864 /* Check tunnel ID */
865 if (ids[0] != priv->conf.tunnel_id
866 && (priv->conf.match_id || ids[0] != 0)) {
867 priv->stats.recvWrongTunnel++;
868 NG_FREE_ITEM(item);
869 NG_FREE_M(m);
870 ERROUT(EADDRNOTAVAIL);
871 }
872
873 /* Check session ID (for data packets only) */
874 if ((hdr & L2TP_HDR_CTRL) == 0) {
875 hpriv = ng_l2tp_find_session(priv, ids[1]);
876 if (hpriv == NULL) {
877 priv->stats.recvUnknownSID++;
878 NG_FREE_ITEM(item);
879 NG_FREE_M(m);
880 ERROUT(ENOTCONN);
881 }
882 hook = hpriv->hook;
883 }
884
885 /* Get Ns, Nr fields if present */
886 if ((hdr & L2TP_HDR_SEQ) != 0) {
887 if (m->m_len < 4 && (m = m_pullup(m, 4)) == NULL) {
888 priv->stats.memoryFailures++;
889 NG_FREE_ITEM(item);
890 ERROUT(EINVAL);
891 }
892 memcpy(&ns, &mtod(m, u_int16_t *)[0], 2);
893 ns = ntohs(ns);
894 memcpy(&nr, &mtod(m, u_int16_t *)[1], 2);
895 nr = ntohs(nr);
896 m_adj(m, 4);
897 }
898
899 /* Strip offset padding if present */
900 if ((hdr & L2TP_HDR_OFF) != 0) {
901 u_int16_t offset;
902
903 /* Get length of offset padding */
904 if (m->m_len < 2 && (m = m_pullup(m, 2)) == NULL) {
905 priv->stats.memoryFailures++;
906 NG_FREE_ITEM(item);
907 ERROUT(EINVAL);
908 }
909 memcpy(&offset, mtod(m, u_int16_t *), 2);
910 offset = ntohs(offset);
911
912 /* Trim offset padding */
913 if ((2+offset) > m->m_pkthdr.len) {
914 priv->stats.recvInvalid++;
915 NG_FREE_ITEM(item);
916 NG_FREE_M(m);
917 ERROUT(EINVAL);
918 }
919 m_adj(m, 2+offset);
920 }
921
922 /* Handle control packets */
923 if ((hdr & L2TP_HDR_CTRL) != 0) {
924 struct l2tp_seq *const seq = &priv->seq;
925
926 /* Handle receive ack sequence number Nr */
927 ng_l2tp_seq_recv_nr(priv, nr);
928
929 /* Discard ZLB packets */
930 if (m->m_pkthdr.len == 0) {
931 priv->stats.recvZLBs++;
932 NG_FREE_ITEM(item);
933 NG_FREE_M(m);
934 ERROUT(0);
935 }
936
937 mtx_lock(&seq->mtx);
938 /*
939 * If not what we expect or we are busy, drop packet and
940 * send an immediate ZLB ack.
941 */
942 if (ns != seq->nr || seq->inproc) {
943 if (L2TP_SEQ_DIFF(ns, seq->nr) <= 0)
944 priv->stats.recvDuplicates++;
945 else
946 priv->stats.recvOutOfOrder++;
947 mtx_unlock(&seq->mtx);
948 ng_l2tp_xmit_ctrl(priv, NULL, seq->ns);
949 NG_FREE_ITEM(item);
950 NG_FREE_M(m);
951 ERROUT(0);
952 }
953 /*
954 * Until we deliver this packet we can't receive next one as
955 * we have no information for sending ack.
956 */
957 seq->inproc = 1;
958 mtx_unlock(&seq->mtx);
959
960 /* Prepend session ID to packet. */
961 M_PREPEND(m, 2, MB_DONTWAIT);
962 if (m == NULL) {
963 seq->inproc = 0;
964 priv->stats.memoryFailures++;
965 NG_FREE_ITEM(item);
966 ERROUT(ENOBUFS);
967 }
968 memcpy(mtod(m, u_int16_t *), &ids[1], 2);
969
970 /* Deliver packet to upper layers */
971 NG_FWD_NEW_DATA(error, item, priv->ctrl, m);
972
973 mtx_lock(&seq->mtx);
974 /* Ready to process next packet. */
975 seq->inproc = 0;
976
977 /* If packet was successfully delivered send ack. */
978 if (error == 0) {
979 /* Update recv sequence number */
980 seq->nr++;
981 /* Start receive ack timer, if not already running */
982 if (!callout_active(&seq->xack_timer)) {
983 ng_callout(&seq->xack_timer, priv->node, NULL,
984 L2TP_DELAYED_ACK, ng_l2tp_seq_xack_timeout,
985 NULL, 0);
986 }
987 }
988 mtx_unlock(&seq->mtx);
989
990 ERROUT(error);
991 }
992
993 /* Per session packet, account it. */
994 hpriv->stats.recvPackets++;
995 hpriv->stats.recvOctets += plen;
996
997 /* Follow peer's lead in data sequencing, if configured to do so */
998 if (!hpriv->conf.control_dseq)
999 hpriv->conf.enable_dseq = ((hdr & L2TP_HDR_SEQ) != 0);
1000
1001 /* Handle data sequence numbers if present and enabled */
1002 if ((hdr & L2TP_HDR_SEQ) != 0) {
1003 if (hpriv->conf.enable_dseq
1004 && L2TP_SEQ_DIFF(ns, hpriv->nr) < 0) {
1005 NG_FREE_ITEM(item); /* duplicate or out of order */
1006 NG_FREE_M(m);
1007 priv->stats.recvDataDrops++;
1008 ERROUT(0);
1009 }
1010 hpriv->nr = ns + 1;
1011 }
1012
1013 /* Drop empty data packets */
1014 if (m->m_pkthdr.len == 0) {
1015 NG_FREE_ITEM(item);
1016 NG_FREE_M(m);
1017 ERROUT(0);
1018 }
1019
1020 /* Deliver data */
1021 NG_FWD_NEW_DATA(error, item, hook, m);
1022 done:
1023 /* Done */
1024 L2TP_SEQ_CHECK(&priv->seq);
1025 return (error);
1026 }
1027
1028 /*
1029 * Handle an outgoing control frame.
1030 */
1031 static int
1032 ng_l2tp_rcvdata_ctrl(hook_p hook, item_p item)
1033 {
1034 const node_p node = NG_HOOK_NODE(hook);
1035 const priv_p priv = NG_NODE_PRIVATE(node);
1036 struct l2tp_seq *const seq = &priv->seq;
1037 struct mbuf *m;
1038 int error;
1039 int i;
1040 u_int16_t ns;
1041
1042 /* Sanity check */
1043 L2TP_SEQ_CHECK(&priv->seq);
1044
1045 /* If not configured, reject */
1046 if (!priv->conf.enabled) {
1047 NG_FREE_ITEM(item);
1048 ERROUT(ENXIO);
1049 }
1050
1051 /* Grab mbuf and discard other stuff XXX */
1052 NGI_GET_M(item, m);
1053 NG_FREE_ITEM(item);
1054
1055 /* Packet should have session ID prepended */
1056 if (m->m_pkthdr.len < 2) {
1057 priv->stats.xmitInvalid++;
1058 m_freem(m);
1059 ERROUT(EINVAL);
1060 }
1061
1062 /* Check max length */
1063 if (m->m_pkthdr.len >= 0x10000 - 14) {
1064 priv->stats.xmitTooBig++;
1065 m_freem(m);
1066 ERROUT(EOVERFLOW);
1067 }
1068
1069 mtx_lock(&seq->mtx);
1070
1071 /* Find next empty slot in transmit queue */
1072 for (i = 0; i < L2TP_MAX_XWIN && seq->xwin[i] != NULL; i++);
1073 if (i == L2TP_MAX_XWIN) {
1074 mtx_unlock(&seq->mtx);
1075 priv->stats.xmitDrops++;
1076 m_freem(m);
1077 ERROUT(ENOBUFS);
1078 }
1079 seq->xwin[i] = m;
1080
1081 /* If peer's receive window is already full, nothing else to do */
1082 if (i >= seq->cwnd) {
1083 mtx_unlock(&seq->mtx);
1084 ERROUT(0);
1085 }
1086
1087 /* Start retransmit timer if not already running */
1088 if (!callout_active(&seq->rack_timer))
1089 ng_callout(&seq->rack_timer, node, NULL,
1090 hz, ng_l2tp_seq_rack_timeout, NULL, 0);
1091
1092 ns = seq->ns++;
1093
1094 mtx_unlock(&seq->mtx);
1095
1096 /* Copy packet */
1097 if ((m = L2TP_COPY_MBUF(m, MB_DONTWAIT)) == NULL) {
1098 priv->stats.memoryFailures++;
1099 ERROUT(ENOBUFS);
1100 }
1101
1102 /* Send packet and increment xmit sequence number */
1103 error = ng_l2tp_xmit_ctrl(priv, m, ns);
1104 done:
1105 /* Done */
1106 L2TP_SEQ_CHECK(&priv->seq);
1107 return (error);
1108 }
1109
1110 /*
1111 * Handle an outgoing data frame.
1112 */
1113 static int
1114 ng_l2tp_rcvdata(hook_p hook, item_p item)
1115 {
1116 const priv_p priv = NG_NODE_PRIVATE(NG_HOOK_NODE(hook));
1117 const hookpriv_p hpriv = NG_HOOK_PRIVATE(hook);
1118 struct mbuf *m;
1119 u_int16_t hdr;
1120 int error;
1121 int i = 1;
1122
1123 /* Sanity check */
1124 L2TP_SEQ_CHECK(&priv->seq);
1125
1126 /* If not configured, reject */
1127 if (!priv->conf.enabled) {
1128 NG_FREE_ITEM(item);
1129 ERROUT(ENXIO);
1130 }
1131
1132 /* Get mbuf */
1133 NGI_GET_M(item, m);
1134
1135 /* Check max length */
1136 if (m->m_pkthdr.len >= 0x10000 - 12) {
1137 priv->stats.xmitDataTooBig++;
1138 NG_FREE_ITEM(item);
1139 NG_FREE_M(m);
1140 ERROUT(EOVERFLOW);
1141 }
1142
1143 /* Prepend L2TP header */
1144 M_PREPEND(m, 6
1145 + (2 * (hpriv->conf.include_length != 0))
1146 + (4 * (hpriv->conf.enable_dseq != 0)),
1147 MB_DONTWAIT);
1148 if (m == NULL) {
1149 priv->stats.memoryFailures++;
1150 NG_FREE_ITEM(item);
1151 ERROUT(ENOBUFS);
1152 }
1153 hdr = L2TP_DATA_HDR;
1154 if (hpriv->conf.include_length) {
1155 hdr |= L2TP_HDR_LEN;
1156 mtod(m, u_int16_t *)[i++] = htons(m->m_pkthdr.len);
1157 }
1158 mtod(m, u_int16_t *)[i++] = priv->conf.peer_id;
1159 mtod(m, u_int16_t *)[i++] = hpriv->conf.peer_id;
1160 if (hpriv->conf.enable_dseq) {
1161 hdr |= L2TP_HDR_SEQ;
1162 mtod(m, u_int16_t *)[i++] = htons(hpriv->ns);
1163 mtod(m, u_int16_t *)[i++] = htons(hpriv->nr);
1164 hpriv->ns++;
1165 }
1166 mtod(m, u_int16_t *)[0] = htons(hdr);
1167
1168 /* Update per session stats. */
1169 hpriv->stats.xmitPackets++;
1170 hpriv->stats.xmitOctets += m->m_pkthdr.len;
1171
1172 /* And the global one. */
1173 priv->stats.xmitPackets++;
1174 priv->stats.xmitOctets += m->m_pkthdr.len;
1175
1176 /* Send packet */
1177 NG_FWD_NEW_DATA(error, item, priv->lower, m);
1178 done:
1179 /* Done */
1180 L2TP_SEQ_CHECK(&priv->seq);
1181 return (error);
1182 }
1183
1184 /*
1185 * Send a message to our controlling node that we've failed.
1186 */
1187 static void
1188 ng_l2tp_seq_failure(priv_p priv)
1189 {
1190 struct ng_mesg *msg;
1191 int error;
1192
1193 NG_MKMESSAGE(msg, NGM_L2TP_COOKIE, NGM_L2TP_ACK_FAILURE, 0, M_WAITOK | M_NULLOK);
1194 if (msg == NULL)
1195 return;
1196 NG_SEND_MSG_ID(error, priv->node, msg, priv->ftarget, 0);
1197 }
1198
1199 /************************************************************************
1200 SEQUENCE NUMBER HANDLING
1201 ************************************************************************/
1202
1203 /*
1204 * Initialize sequence number state.
1205 */
1206 static void
1207 ng_l2tp_seq_init(priv_p priv)
1208 {
1209 struct l2tp_seq *const seq = &priv->seq;
1210
1211 KASSERT(priv->conf.peer_win >= 1,
1212 ("%s: peer_win is zero", __func__));
1213 memset(seq, 0, sizeof(*seq));
1214 seq->cwnd = 1;
1215 seq->wmax = priv->conf.peer_win;
1216 if (seq->wmax > L2TP_MAX_XWIN)
1217 seq->wmax = L2TP_MAX_XWIN;
1218 seq->ssth = seq->wmax;
1219 ng_callout_init(&seq->rack_timer);
1220 ng_callout_init(&seq->xack_timer);
1221 mtx_init(&seq->mtx, "ng_l2tp", NULL, MTX_DEF);
1222 L2TP_SEQ_CHECK(seq);
1223 }
1224
1225 /*
1226 * Set sequence number state as given from user.
1227 */
1228 static int
1229 ng_l2tp_seq_set(priv_p priv, const struct ng_l2tp_seq_config *conf)
1230 {
1231 struct l2tp_seq *const seq = &priv->seq;
1232
1233 /* If node is enabled, deny update to sequence numbers. */
1234 if (priv->conf.enabled)
1235 return (EBUSY);
1236
1237 /* We only can handle the simple cases. */
1238 if (conf->xack != conf->nr || conf->ns != conf->rack)
1239 return (EINVAL);
1240
1241 /* Set ns,nr,rack,xack parameters. */
1242 seq->ns = conf->ns;
1243 seq->nr = conf->nr;
1244 seq->rack = conf->rack;
1245 seq->xack = conf->xack;
1246
1247 return (0);
1248 }
1249
1250 /*
1251 * Adjust sequence number state accordingly after reconfiguration.
1252 */
1253 static int
1254 ng_l2tp_seq_adjust(priv_p priv, const struct ng_l2tp_config *conf)
1255 {
1256 struct l2tp_seq *const seq = &priv->seq;
1257 u_int16_t new_wmax;
1258
1259 /* If disabling node, reset state sequence number */
1260 if (!conf->enabled) {
1261 ng_l2tp_seq_reset(priv);
1262 return (0);
1263 }
1264
1265 /* Adjust peer's max recv window; it can only increase */
1266 new_wmax = conf->peer_win;
1267 if (new_wmax > L2TP_MAX_XWIN)
1268 new_wmax = L2TP_MAX_XWIN;
1269 if (new_wmax == 0)
1270 return (EINVAL);
1271 if (new_wmax < seq->wmax)
1272 return (EBUSY);
1273 seq->wmax = new_wmax;
1274
1275 /* Done */
1276 return (0);
1277 }
1278
1279 /*
1280 * Reset sequence number state.
1281 */
1282 static void
1283 ng_l2tp_seq_reset(priv_p priv)
1284 {
1285 struct l2tp_seq *const seq = &priv->seq;
1286 hook_p hook;
1287 int i;
1288
1289 /* Sanity check */
1290 L2TP_SEQ_CHECK(seq);
1291
1292 /* Stop timers */
1293 ng_uncallout(&seq->rack_timer, priv->node);
1294 ng_uncallout(&seq->xack_timer, priv->node);
1295
1296 /* Free retransmit queue */
1297 for (i = 0; i < L2TP_MAX_XWIN; i++) {
1298 if (seq->xwin[i] == NULL)
1299 break;
1300 m_freem(seq->xwin[i]);
1301 }
1302
1303 /* Reset session hooks' sequence number states */
1304 NG_NODE_FOREACH_HOOK(priv->node, ng_l2tp_reset_session, NULL, hook);
1305
1306 /* Reset node's sequence number state */
1307 seq->ns = 0;
1308 seq->nr = 0;
1309 seq->rack = 0;
1310 seq->xack = 0;
1311 seq->wmax = L2TP_MAX_XWIN;
1312 seq->cwnd = 1;
1313 seq->ssth = seq->wmax;
1314 seq->acks = 0;
1315 seq->rexmits = 0;
1316 bzero(seq->xwin, sizeof(seq->xwin));
1317
1318 /* Done */
1319 L2TP_SEQ_CHECK(seq);
1320 }
1321
1322 /*
1323 * Handle receipt of an acknowledgement value (Nr) from peer.
1324 */
1325 static void
1326 ng_l2tp_seq_recv_nr(priv_p priv, u_int16_t nr)
1327 {
1328 struct l2tp_seq *const seq = &priv->seq;
1329 struct mbuf *xwin[L2TP_MAX_XWIN]; /* partial local copy */
1330 int nack;
1331 int i, j;
1332 uint16_t ns;
1333
1334 mtx_lock(&seq->mtx);
1335
1336 /* Verify peer's ACK is in range */
1337 if ((nack = L2TP_SEQ_DIFF(nr, seq->rack)) <= 0) {
1338 mtx_unlock(&seq->mtx);
1339 return; /* duplicate ack */
1340 }
1341 if (L2TP_SEQ_DIFF(nr, seq->ns) > 0) {
1342 mtx_unlock(&seq->mtx);
1343 priv->stats.recvBadAcks++; /* ack for packet not sent */
1344 return;
1345 }
1346 KASSERT(nack <= L2TP_MAX_XWIN,
1347 ("%s: nack=%d > %d", __func__, nack, L2TP_MAX_XWIN));
1348
1349 /* Update receive ack stats */
1350 seq->rack = nr;
1351 seq->rexmits = 0;
1352
1353 /* Free acknowledged packets and shift up packets in the xmit queue */
1354 for (i = 0; i < nack; i++)
1355 m_freem(seq->xwin[i]);
1356 memmove(seq->xwin, seq->xwin + nack,
1357 (L2TP_MAX_XWIN - nack) * sizeof(*seq->xwin));
1358 memset(seq->xwin + (L2TP_MAX_XWIN - nack), 0,
1359 nack * sizeof(*seq->xwin));
1360
1361 /*
1362 * Do slow-start/congestion avoidance windowing algorithm described
1363 * in RFC 2661, Appendix A. Here we handle a multiple ACK as if each
1364 * ACK had arrived separately.
1365 */
1366 if (seq->cwnd < seq->wmax) {
1367
1368 /* Handle slow start phase */
1369 if (seq->cwnd < seq->ssth) {
1370 seq->cwnd += nack;
1371 nack = 0;
1372 if (seq->cwnd > seq->ssth) { /* into cg.av. phase */
1373 nack = seq->cwnd - seq->ssth;
1374 seq->cwnd = seq->ssth;
1375 }
1376 }
1377
1378 /* Handle congestion avoidance phase */
1379 if (seq->cwnd >= seq->ssth) {
1380 seq->acks += nack;
1381 while (seq->acks >= seq->cwnd) {
1382 seq->acks -= seq->cwnd;
1383 if (seq->cwnd < seq->wmax)
1384 seq->cwnd++;
1385 }
1386 }
1387 }
1388
1389 /* Stop xmit timer */
1390 if (callout_active(&seq->rack_timer))
1391 ng_uncallout(&seq->rack_timer, priv->node);
1392
1393 /* If transmit queue is empty, we're done for now */
1394 if (seq->xwin[0] == NULL) {
1395 mtx_unlock(&seq->mtx);
1396 return;
1397 }
1398
1399 /* Start restransmit timer again */
1400 ng_callout(&seq->rack_timer, priv->node, NULL,
1401 hz, ng_l2tp_seq_rack_timeout, NULL, 0);
1402
1403 /*
1404 * Send more packets, trying to keep peer's receive window full.
1405 * Make copy of everything we need before lock release.
1406 */
1407 ns = seq->ns;
1408 j = 0;
1409 while ((i = L2TP_SEQ_DIFF(seq->ns, seq->rack)) < seq->cwnd
1410 && seq->xwin[i] != NULL) {
1411 xwin[j++] = seq->xwin[i];
1412 seq->ns++;
1413 }
1414
1415 mtx_unlock(&seq->mtx);
1416
1417 /*
1418 * Send prepared.
1419 * If there is a memory error, pretend packet was sent, as it
1420 * will get retransmitted later anyway.
1421 */
1422 for (i = 0; i < j; i++) {
1423 struct mbuf *m;
1424 if ((m = L2TP_COPY_MBUF(xwin[i], MB_DONTWAIT)) == NULL)
1425 priv->stats.memoryFailures++;
1426 else
1427 ng_l2tp_xmit_ctrl(priv, m, ns);
1428 ns++;
1429 }
1430 }
1431
1432 /*
1433 * Handle an ack timeout. We have an outstanding ack that we
1434 * were hoping to piggy-back, but haven't, so send a ZLB.
1435 */
1436 static void
1437 ng_l2tp_seq_xack_timeout(node_p node, hook_p hook, void *arg1, int arg2)
1438 {
1439 const priv_p priv = NG_NODE_PRIVATE(node);
1440 struct l2tp_seq *const seq = &priv->seq;
1441
1442 /* Make sure callout is still active before doing anything */
1443 if (callout_pending(&seq->xack_timer) ||
1444 (!callout_active(&seq->xack_timer)))
1445 return;
1446
1447 /* Sanity check */
1448 L2TP_SEQ_CHECK(seq);
1449
1450 /* Send a ZLB */
1451 ng_l2tp_xmit_ctrl(priv, NULL, seq->ns);
1452
1453 /* callout_deactivate() is not needed here
1454 as ng_uncallout() was called by ng_l2tp_xmit_ctrl() */
1455
1456 /* Sanity check */
1457 L2TP_SEQ_CHECK(seq);
1458 }
1459
1460 /*
1461 * Handle a transmit timeout. The peer has failed to respond
1462 * with an ack for our packet, so retransmit it.
1463 */
1464 static void
1465 ng_l2tp_seq_rack_timeout(node_p node, hook_p hook, void *arg1, int arg2)
1466 {
1467 const priv_p priv = NG_NODE_PRIVATE(node);
1468 struct l2tp_seq *const seq = &priv->seq;
1469 struct mbuf *m;
1470 u_int delay;
1471
1472 /* Make sure callout is still active before doing anything */
1473 if (callout_pending(&seq->rack_timer) ||
1474 (!callout_active(&seq->rack_timer)))
1475 return;
1476
1477 /* Sanity check */
1478 L2TP_SEQ_CHECK(seq);
1479
1480 priv->stats.xmitRetransmits++;
1481
1482 /* Have we reached the retransmit limit? If so, notify owner. */
1483 if (seq->rexmits++ >= priv->conf.rexmit_max)
1484 ng_l2tp_seq_failure(priv);
1485
1486 /* Restart timer, this time with an increased delay */
1487 delay = (seq->rexmits > 12) ? (1 << 12) : (1 << seq->rexmits);
1488 if (delay > priv->conf.rexmit_max_to)
1489 delay = priv->conf.rexmit_max_to;
1490 ng_callout(&seq->rack_timer, node, NULL,
1491 hz * delay, ng_l2tp_seq_rack_timeout, NULL, 0);
1492
1493 /* Do slow-start/congestion algorithm windowing algorithm */
1494 seq->ns = seq->rack;
1495 seq->ssth = (seq->cwnd + 1) / 2;
1496 seq->cwnd = 1;
1497 seq->acks = 0;
1498
1499 /* Retransmit oldest unack'd packet */
1500 if ((m = L2TP_COPY_MBUF(seq->xwin[0], MB_DONTWAIT)) == NULL)
1501 priv->stats.memoryFailures++;
1502 else
1503 ng_l2tp_xmit_ctrl(priv, m, seq->ns++);
1504
1505 /* callout_deactivate() is not needed here
1506 as ng_callout() is getting called each time */
1507
1508 /* Sanity check */
1509 L2TP_SEQ_CHECK(seq);
1510 }
1511
1512 /*
1513 * Transmit a control stream packet, payload optional.
1514 * The transmit sequence number is not incremented.
1515 */
1516 static int
1517 ng_l2tp_xmit_ctrl(priv_p priv, struct mbuf *m, u_int16_t ns)
1518 {
1519 struct l2tp_seq *const seq = &priv->seq;
1520 u_int16_t session_id = 0;
1521 int error;
1522
1523 mtx_lock(&seq->mtx);
1524
1525 /* Stop ack timer: we're sending an ack with this packet.
1526 Doing this before to keep state predictable after error. */
1527 if (callout_active(&seq->xack_timer))
1528 ng_uncallout(&seq->xack_timer, priv->node);
1529
1530 seq->xack = seq->nr;
1531
1532 mtx_unlock(&seq->mtx);
1533
1534 /* If no mbuf passed, send an empty packet (ZLB) */
1535 if (m == NULL) {
1536
1537 /* Create a new mbuf for ZLB packet */
1538 MGETHDR(m, MB_DONTWAIT, MT_DATA);
1539 if (m == NULL) {
1540 priv->stats.memoryFailures++;
1541 return (ENOBUFS);
1542 }
1543 m->m_len = m->m_pkthdr.len = 12;
1544 m->m_pkthdr.rcvif = NULL;
1545 priv->stats.xmitZLBs++;
1546 } else {
1547
1548 /* Strip off session ID */
1549 if (m->m_len < 2 && (m = m_pullup(m, 2)) == NULL) {
1550 priv->stats.memoryFailures++;
1551 return (ENOBUFS);
1552 }
1553 memcpy(&session_id, mtod(m, u_int16_t *), 2);
1554 m_adj(m, 2);
1555
1556 /* Make room for L2TP header */
1557 M_PREPEND(m, 12, MB_DONTWAIT);
1558 if (m == NULL) {
1559 priv->stats.memoryFailures++;
1560 return (ENOBUFS);
1561 }
1562 }
1563
1564 /* Fill in L2TP header */
1565 mtod(m, u_int16_t *)[0] = htons(L2TP_CTRL_HDR);
1566 mtod(m, u_int16_t *)[1] = htons(m->m_pkthdr.len);
1567 mtod(m, u_int16_t *)[2] = priv->conf.peer_id;
1568 mtod(m, u_int16_t *)[3] = session_id;
1569 mtod(m, u_int16_t *)[4] = htons(ns);
1570 mtod(m, u_int16_t *)[5] = htons(seq->nr);
1571
1572 /* Update sequence number info and stats */
1573 priv->stats.xmitPackets++;
1574 priv->stats.xmitOctets += m->m_pkthdr.len;
1575
1576 /* Send packet */
1577 NG_SEND_DATA_ONLY(error, priv->lower, m);
1578 return (error);
1579 }
1580
1581 #ifdef INVARIANTS
1582 /*
1583 * Sanity check sequence number state.
1584 */
1585 static void
1586 ng_l2tp_seq_check(struct l2tp_seq *seq)
1587 {
1588 int self_unack, peer_unack;
1589 int i;
1590
1591 #define CHECK(p) KASSERT((p), ("%s: not: %s", __func__, #p))
1592
1593 mtx_lock(&seq->mtx);
1594
1595 self_unack = L2TP_SEQ_DIFF(seq->nr, seq->xack);
1596 peer_unack = L2TP_SEQ_DIFF(seq->ns, seq->rack);
1597 CHECK(seq->wmax <= L2TP_MAX_XWIN);
1598 CHECK(seq->cwnd >= 1);
1599 CHECK(seq->cwnd <= seq->wmax);
1600 CHECK(seq->ssth >= 1);
1601 CHECK(seq->ssth <= seq->wmax);
1602 if (seq->cwnd < seq->ssth)
1603 CHECK(seq->acks == 0);
1604 else
1605 CHECK(seq->acks <= seq->cwnd);
1606 CHECK(self_unack >= 0);
1607 CHECK(peer_unack >= 0);
1608 CHECK(peer_unack <= seq->wmax);
1609 CHECK((self_unack == 0) ^ callout_active(&seq->xack_timer));
1610 CHECK((peer_unack == 0) ^ callout_active(&seq->rack_timer));
1611 for (i = 0; i < peer_unack; i++)
1612 CHECK(seq->xwin[i] != NULL);
1613 for ( ; i < seq->cwnd; i++) /* verify peer's recv window full */
1614 CHECK(seq->xwin[i] == NULL);
1615
1616 mtx_unlock(&seq->mtx);
1617
1618 #undef CHECK
1619 }
1620 #endif /* INVARIANTS */
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