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/5.4/sys/netgraph/ng_l2tp.c 141090 2005-01-31 23:27:04Z imp $
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 16 /* 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 /*
104 * Sequence number state
105 *
106 * Invariants:
107 * - If cwnd < ssth, we're doing slow start, otherwise congestion avoidance
108 * - The number of unacknowledged xmit packets is (ns - rack) <= seq->wmax
109 * - The first (ns - rack) mbuf's in xwin[] array are copies of these
110 * unacknowledged packets; the remainder of xwin[] consists first of
111 * zero or more further untransmitted packets in the transmit queue
112 * - We try to keep the peer's receive window as full as possible.
113 * Therefore, (i < cwnd && xwin[i] != NULL) implies (ns - rack) > i.
114 * - rack_timer is running iff (ns - rack) > 0 (unack'd xmit'd pkts)
115 * - If xack != nr, there are unacknowledged recv packet(s) (delayed ack)
116 * - xack_timer is running iff xack != nr (unack'd rec'd pkts)
117 */
118 struct l2tp_seq {
119 u_int16_t ns; /* next xmit seq we send */
120 u_int16_t nr; /* next recv seq we expect */
121 u_int16_t rack; /* last 'nr' we rec'd */
122 u_int16_t xack; /* last 'nr' we sent */
123 u_int16_t wmax; /* peer's max recv window */
124 u_int16_t cwnd; /* current congestion window */
125 u_int16_t ssth; /* slow start threshold */
126 u_int16_t acks; /* # consecutive acks rec'd */
127 u_int16_t rexmits; /* # retransmits sent */
128 u_int16_t max_rexmits; /* max # retransmits sent */
129 u_int16_t max_rexmit_to; /* max retransmit timeout */
130 struct callout rack_timer; /* retransmit timer */
131 struct callout xack_timer; /* delayed ack timer */
132 struct mbuf *xwin[L2TP_MAX_XWIN]; /* transmit window */
133 };
134
135 /* Node private data */
136 struct ng_l2tp_private {
137 node_p node; /* back pointer to node */
138 hook_p ctrl; /* hook to upper layers */
139 hook_p lower; /* hook to lower layers */
140 struct ng_l2tp_config conf; /* node configuration */
141 struct ng_l2tp_stats stats; /* node statistics */
142 struct l2tp_seq seq; /* ctrl sequence number state */
143 ng_ID_t ftarget; /* failure message target */
144 };
145 typedef struct ng_l2tp_private *priv_p;
146
147 /* Hook private data (data session hooks only) */
148 struct ng_l2tp_hook_private {
149 struct ng_l2tp_sess_config conf; /* hook/session config */
150 struct ng_l2tp_session_stats stats; /* per sessions statistics */
151 u_int16_t ns; /* data ns sequence number */
152 u_int16_t nr; /* data nr sequence number */
153 };
154 typedef struct ng_l2tp_hook_private *hookpriv_p;
155
156 /* Netgraph node methods */
157 static ng_constructor_t ng_l2tp_constructor;
158 static ng_rcvmsg_t ng_l2tp_rcvmsg;
159 static ng_shutdown_t ng_l2tp_shutdown;
160 static ng_newhook_t ng_l2tp_newhook;
161 static ng_rcvdata_t ng_l2tp_rcvdata;
162 static ng_disconnect_t ng_l2tp_disconnect;
163
164 /* Internal functions */
165 static int ng_l2tp_recv_lower(node_p node, item_p item);
166 static int ng_l2tp_recv_ctrl(node_p node, item_p item);
167 static int ng_l2tp_recv_data(node_p node, item_p item, hookpriv_p hpriv);
168
169 static int ng_l2tp_xmit_ctrl(priv_p priv, struct mbuf *m, u_int16_t ns);
170
171 static void ng_l2tp_seq_init(priv_p priv);
172 static int ng_l2tp_seq_set(priv_p priv,
173 const struct ng_l2tp_seq_config *conf);
174 static int ng_l2tp_seq_adjust(priv_p priv,
175 const struct ng_l2tp_config *conf);
176 static void ng_l2tp_seq_reset(priv_p priv);
177 static void ng_l2tp_seq_failure(priv_p priv);
178 static void ng_l2tp_seq_recv_nr(priv_p priv, u_int16_t nr);
179 static int ng_l2tp_seq_recv_ns(priv_p priv, u_int16_t ns);
180 static void ng_l2tp_seq_xack_timeout(node_p node, hook_p hook,
181 void *arg1, int arg2);
182 static void ng_l2tp_seq_rack_timeout(node_p node, hook_p hook,
183 void *arg1, int arg2);
184
185 static ng_fn_eachhook ng_l2tp_find_session;
186 static ng_fn_eachhook ng_l2tp_reset_session;
187
188 #ifdef INVARIANTS
189 static void ng_l2tp_seq_check(struct l2tp_seq *seq);
190 #endif
191
192 /* Parse type for struct ng_l2tp_seq_config. */
193 static const struct ng_parse_struct_field
194 ng_l2tp_seq_config_fields[] = NG_L2TP_SEQ_CONFIG_TYPE_INFO;
195 static const struct ng_parse_type ng_l2tp_seq_config_type = {
196 &ng_parse_struct_type,
197 &ng_l2tp_seq_config_fields
198 };
199
200 /* Parse type for struct ng_l2tp_config */
201 static const struct ng_parse_struct_field
202 ng_l2tp_config_type_fields[] = NG_L2TP_CONFIG_TYPE_INFO;
203 static const struct ng_parse_type ng_l2tp_config_type = {
204 &ng_parse_struct_type,
205 &ng_l2tp_config_type_fields,
206 };
207
208 /* Parse type for struct ng_l2tp_sess_config */
209 static const struct ng_parse_struct_field
210 ng_l2tp_sess_config_type_fields[] = NG_L2TP_SESS_CONFIG_TYPE_INFO;
211 static const struct ng_parse_type ng_l2tp_sess_config_type = {
212 &ng_parse_struct_type,
213 &ng_l2tp_sess_config_type_fields,
214 };
215
216 /* Parse type for struct ng_l2tp_stats */
217 static const struct ng_parse_struct_field
218 ng_l2tp_stats_type_fields[] = NG_L2TP_STATS_TYPE_INFO;
219 static const struct ng_parse_type ng_l2tp_stats_type = {
220 &ng_parse_struct_type,
221 &ng_l2tp_stats_type_fields
222 };
223
224 /* Parse type for struct ng_l2tp_session_stats. */
225 static const struct ng_parse_struct_field
226 ng_l2tp_session_stats_type_fields[] = NG_L2TP_SESSION_STATS_TYPE_INFO;
227 static const struct ng_parse_type ng_l2tp_session_stats_type = {
228 &ng_parse_struct_type,
229 &ng_l2tp_session_stats_type_fields
230 };
231
232 /* List of commands and how to convert arguments to/from ASCII */
233 static const struct ng_cmdlist ng_l2tp_cmdlist[] = {
234 {
235 NGM_L2TP_COOKIE,
236 NGM_L2TP_SET_CONFIG,
237 "setconfig",
238 &ng_l2tp_config_type,
239 NULL
240 },
241 {
242 NGM_L2TP_COOKIE,
243 NGM_L2TP_GET_CONFIG,
244 "getconfig",
245 NULL,
246 &ng_l2tp_config_type
247 },
248 {
249 NGM_L2TP_COOKIE,
250 NGM_L2TP_SET_SESS_CONFIG,
251 "setsessconfig",
252 &ng_l2tp_sess_config_type,
253 NULL
254 },
255 {
256 NGM_L2TP_COOKIE,
257 NGM_L2TP_GET_SESS_CONFIG,
258 "getsessconfig",
259 &ng_parse_hint16_type,
260 &ng_l2tp_sess_config_type
261 },
262 {
263 NGM_L2TP_COOKIE,
264 NGM_L2TP_GET_STATS,
265 "getstats",
266 NULL,
267 &ng_l2tp_stats_type
268 },
269 {
270 NGM_L2TP_COOKIE,
271 NGM_L2TP_CLR_STATS,
272 "clrstats",
273 NULL,
274 NULL
275 },
276 {
277 NGM_L2TP_COOKIE,
278 NGM_L2TP_GETCLR_STATS,
279 "getclrstats",
280 NULL,
281 &ng_l2tp_stats_type
282 },
283 {
284 NGM_L2TP_COOKIE,
285 NGM_L2TP_GET_SESSION_STATS,
286 "getsessstats",
287 &ng_parse_int16_type,
288 &ng_l2tp_session_stats_type
289 },
290 {
291 NGM_L2TP_COOKIE,
292 NGM_L2TP_CLR_SESSION_STATS,
293 "clrsessstats",
294 &ng_parse_int16_type,
295 NULL
296 },
297 {
298 NGM_L2TP_COOKIE,
299 NGM_L2TP_GETCLR_SESSION_STATS,
300 "getclrsessstats",
301 &ng_parse_int16_type,
302 &ng_l2tp_session_stats_type
303 },
304 {
305 NGM_L2TP_COOKIE,
306 NGM_L2TP_ACK_FAILURE,
307 "ackfailure",
308 NULL,
309 NULL
310 },
311 {
312 NGM_L2TP_COOKIE,
313 NGM_L2TP_SET_SEQ,
314 "setsequence",
315 &ng_l2tp_seq_config_type,
316 NULL
317 },
318 { 0 }
319 };
320
321 /* Node type descriptor */
322 static struct ng_type ng_l2tp_typestruct = {
323 .version = NG_ABI_VERSION,
324 .name = NG_L2TP_NODE_TYPE,
325 .constructor = ng_l2tp_constructor,
326 .rcvmsg = ng_l2tp_rcvmsg,
327 .shutdown = ng_l2tp_shutdown,
328 .newhook = ng_l2tp_newhook,
329 .rcvdata = ng_l2tp_rcvdata,
330 .disconnect = ng_l2tp_disconnect,
331 .cmdlist = ng_l2tp_cmdlist,
332 };
333 NETGRAPH_INIT(l2tp, &ng_l2tp_typestruct);
334
335 /* Sequence number state sanity checking */
336 #ifdef INVARIANTS
337 #define L2TP_SEQ_CHECK(seq) ng_l2tp_seq_check(seq)
338 #else
339 #define L2TP_SEQ_CHECK(x) do { } while (0)
340 #endif
341
342 /* memmove macro */
343 #define memmove(d, s, l) bcopy(s, d, l)
344
345 /* Whether to use m_copypacket() or m_dup() */
346 #define L2TP_COPY_MBUF m_copypacket
347
348 /************************************************************************
349 NETGRAPH NODE STUFF
350 ************************************************************************/
351
352 /*
353 * Node type constructor
354 */
355 static int
356 ng_l2tp_constructor(node_p node)
357 {
358 priv_p priv;
359
360 /* Allocate private structure */
361 MALLOC(priv, priv_p, sizeof(*priv), M_NETGRAPH_L2TP, M_NOWAIT | M_ZERO);
362 if (priv == NULL)
363 return (ENOMEM);
364 NG_NODE_SET_PRIVATE(node, priv);
365 priv->node = node;
366
367 /* Apply a semi-reasonable default configuration */
368 priv->conf.peer_win = 1;
369 priv->conf.rexmit_max = L2TP_MAX_REXMIT;
370 priv->conf.rexmit_max_to = L2TP_MAX_REXMIT_TO;
371
372 /* Initialize sequence number state */
373 ng_l2tp_seq_init(priv);
374
375 /* Done */
376 return (0);
377 }
378
379 /*
380 * Give our OK for a hook to be added.
381 */
382 static int
383 ng_l2tp_newhook(node_p node, hook_p hook, const char *name)
384 {
385 const priv_p priv = NG_NODE_PRIVATE(node);
386
387 /* Check hook name */
388 if (strcmp(name, NG_L2TP_HOOK_CTRL) == 0) {
389 if (priv->ctrl != NULL)
390 return (EISCONN);
391 priv->ctrl = hook;
392 } else if (strcmp(name, NG_L2TP_HOOK_LOWER) == 0) {
393 if (priv->lower != NULL)
394 return (EISCONN);
395 priv->lower = hook;
396 } else {
397 static const char hexdig[16] = "0123456789abcdef";
398 u_int16_t session_id;
399 hookpriv_p hpriv;
400 const char *hex;
401 int i;
402 int j;
403
404 /* Parse hook name to get session ID */
405 if (strncmp(name, NG_L2TP_HOOK_SESSION_P,
406 sizeof(NG_L2TP_HOOK_SESSION_P) - 1) != 0)
407 return (EINVAL);
408 hex = name + sizeof(NG_L2TP_HOOK_SESSION_P) - 1;
409 for (session_id = i = 0; i < 4; i++) {
410 for (j = 0; j < 16 && hex[i] != hexdig[j]; j++);
411 if (j == 16)
412 return (EINVAL);
413 session_id = (session_id << 4) | j;
414 }
415 if (hex[i] != '\0')
416 return (EINVAL);
417
418 /* Create hook private structure */
419 MALLOC(hpriv, hookpriv_p,
420 sizeof(*hpriv), M_NETGRAPH_L2TP, M_NOWAIT | M_ZERO);
421 if (hpriv == NULL)
422 return (ENOMEM);
423 hpriv->conf.session_id = htons(session_id);
424 hpriv->conf.control_dseq = L2TP_CONTROL_DSEQ;
425 hpriv->conf.enable_dseq = L2TP_ENABLE_DSEQ;
426 NG_HOOK_SET_PRIVATE(hook, hpriv);
427 }
428
429 /* Done */
430 return (0);
431 }
432
433 /*
434 * Receive a control message.
435 */
436 static int
437 ng_l2tp_rcvmsg(node_p node, item_p item, hook_p lasthook)
438 {
439 const priv_p priv = NG_NODE_PRIVATE(node);
440 struct ng_mesg *resp = NULL;
441 struct ng_mesg *msg;
442 int error = 0;
443
444 NGI_GET_MSG(item, msg);
445 switch (msg->header.typecookie) {
446 case NGM_L2TP_COOKIE:
447 switch (msg->header.cmd) {
448 case NGM_L2TP_SET_CONFIG:
449 {
450 struct ng_l2tp_config *const conf =
451 (struct ng_l2tp_config *)msg->data;
452
453 /* Check for invalid or illegal config */
454 if (msg->header.arglen != sizeof(*conf)) {
455 error = EINVAL;
456 break;
457 }
458 conf->enabled = !!conf->enabled;
459 conf->match_id = !!conf->match_id;
460 conf->tunnel_id = htons(conf->tunnel_id);
461 conf->peer_id = htons(conf->peer_id);
462 if (priv->conf.enabled
463 && ((priv->conf.tunnel_id != 0
464 && conf->tunnel_id != priv->conf.tunnel_id)
465 || ((priv->conf.peer_id != 0
466 && conf->peer_id != priv->conf.peer_id)))) {
467 error = EBUSY;
468 break;
469 }
470
471 /* Save calling node as failure target */
472 priv->ftarget = NGI_RETADDR(item);
473
474 /* Adjust sequence number state */
475 if ((error = ng_l2tp_seq_adjust(priv, conf)) != 0)
476 break;
477
478 /* Update node's config */
479 priv->conf = *conf;
480 break;
481 }
482 case NGM_L2TP_GET_CONFIG:
483 {
484 struct ng_l2tp_config *conf;
485
486 NG_MKRESPONSE(resp, msg, sizeof(*conf), M_NOWAIT);
487 if (resp == NULL) {
488 error = ENOMEM;
489 break;
490 }
491 conf = (struct ng_l2tp_config *)resp->data;
492 *conf = priv->conf;
493
494 /* Put ID's in host order */
495 conf->tunnel_id = ntohs(conf->tunnel_id);
496 conf->peer_id = ntohs(conf->peer_id);
497 break;
498 }
499 case NGM_L2TP_SET_SESS_CONFIG:
500 {
501 struct ng_l2tp_sess_config *const conf =
502 (struct ng_l2tp_sess_config *)msg->data;
503 hookpriv_p hpriv;
504 hook_p hook;
505
506 /* Check for invalid or illegal config. */
507 if (msg->header.arglen != sizeof(*conf)) {
508 error = EINVAL;
509 break;
510 }
511
512 /* Put ID's in network order */
513 conf->session_id = htons(conf->session_id);
514 conf->peer_id = htons(conf->peer_id);
515
516 /* Find matching hook */
517 NG_NODE_FOREACH_HOOK(node, ng_l2tp_find_session,
518 (void *)(uintptr_t)conf->session_id, hook);
519 if (hook == NULL) {
520 error = ENOENT;
521 break;
522 }
523 hpriv = NG_HOOK_PRIVATE(hook);
524
525 /* Update hook's config */
526 hpriv->conf = *conf;
527 break;
528 }
529 case NGM_L2TP_GET_SESS_CONFIG:
530 {
531 struct ng_l2tp_sess_config *conf;
532 u_int16_t session_id;
533 hookpriv_p hpriv;
534 hook_p hook;
535
536 /* Get session ID */
537 if (msg->header.arglen != sizeof(session_id)) {
538 error = EINVAL;
539 break;
540 }
541 memcpy(&session_id, msg->data, 2);
542 session_id = htons(session_id);
543
544 /* Find matching hook */
545 NG_NODE_FOREACH_HOOK(node, ng_l2tp_find_session,
546 (void *)(uintptr_t)session_id, hook);
547 if (hook == NULL) {
548 error = ENOENT;
549 break;
550 }
551 hpriv = NG_HOOK_PRIVATE(hook);
552
553 /* Send response */
554 NG_MKRESPONSE(resp, msg, sizeof(hpriv->conf), M_NOWAIT);
555 if (resp == NULL) {
556 error = ENOMEM;
557 break;
558 }
559 conf = (struct ng_l2tp_sess_config *)resp->data;
560 *conf = hpriv->conf;
561
562 /* Put ID's in host order */
563 conf->session_id = ntohs(conf->session_id);
564 conf->peer_id = ntohs(conf->peer_id);
565 break;
566 }
567 case NGM_L2TP_GET_STATS:
568 case NGM_L2TP_CLR_STATS:
569 case NGM_L2TP_GETCLR_STATS:
570 {
571 if (msg->header.cmd != NGM_L2TP_CLR_STATS) {
572 NG_MKRESPONSE(resp, msg,
573 sizeof(priv->stats), M_NOWAIT);
574 if (resp == NULL) {
575 error = ENOMEM;
576 break;
577 }
578 memcpy(resp->data,
579 &priv->stats, sizeof(priv->stats));
580 }
581 if (msg->header.cmd != NGM_L2TP_GET_STATS)
582 memset(&priv->stats, 0, sizeof(priv->stats));
583 break;
584 }
585 case NGM_L2TP_GET_SESSION_STATS:
586 case NGM_L2TP_CLR_SESSION_STATS:
587 case NGM_L2TP_GETCLR_SESSION_STATS:
588 {
589 uint16_t session_id;
590 hookpriv_p hpriv;
591 hook_p hook;
592
593 /* Get session ID. */
594 if (msg->header.arglen != sizeof(session_id)) {
595 error = EINVAL;
596 break;
597 }
598 bcopy(msg->data, &session_id, sizeof(uint16_t));
599 session_id = htons(session_id);
600
601 /* Find matching hook. */
602 NG_NODE_FOREACH_HOOK(node, ng_l2tp_find_session,
603 (void *)(uintptr_t)session_id, hook);
604 if (hook == NULL) {
605 error = ENOENT;
606 break;
607 }
608 hpriv = NG_HOOK_PRIVATE(hook);
609
610 if (msg->header.cmd != NGM_L2TP_CLR_SESSION_STATS) {
611 NG_MKRESPONSE(resp, msg,
612 sizeof(hpriv->stats), M_NOWAIT);
613 if (resp == NULL) {
614 error = ENOMEM;
615 break;
616 }
617 bcopy(&hpriv->stats, resp->data,
618 sizeof(hpriv->stats));
619 }
620 if (msg->header.cmd != NGM_L2TP_GET_SESSION_STATS)
621 bzero(&hpriv->stats, sizeof(hpriv->stats));
622 break;
623 }
624 case NGM_L2TP_SET_SEQ:
625 {
626 struct ng_l2tp_seq_config *const conf =
627 (struct ng_l2tp_seq_config *)msg->data;
628
629 /* Check for invalid or illegal seq config. */
630 if (msg->header.arglen != sizeof(*conf)) {
631 error = EINVAL;
632 break;
633 }
634 conf->ns = htons(conf->ns);
635 conf->nr = htons(conf->nr);
636 conf->rack = htons(conf->rack);
637 conf->xack = htons(conf->xack);
638
639 /* Set sequence numbers. */
640 error = ng_l2tp_seq_set(priv, conf);
641 break;
642 }
643 default:
644 error = EINVAL;
645 break;
646 }
647 break;
648 default:
649 error = EINVAL;
650 break;
651 }
652
653 /* Done */
654 NG_RESPOND_MSG(error, node, item, resp);
655 NG_FREE_MSG(msg);
656 return (error);
657 }
658
659 /*
660 * Receive incoming data on a hook.
661 */
662 static int
663 ng_l2tp_rcvdata(hook_p hook, item_p item)
664 {
665 const node_p node = NG_HOOK_NODE(hook);
666 const priv_p priv = NG_NODE_PRIVATE(node);
667 int error;
668
669 /* Sanity check */
670 L2TP_SEQ_CHECK(&priv->seq);
671
672 /* If not configured, reject */
673 if (!priv->conf.enabled) {
674 NG_FREE_ITEM(item);
675 return (ENXIO);
676 }
677
678 /* Handle incoming frame from below */
679 if (hook == priv->lower) {
680 error = ng_l2tp_recv_lower(node, item);
681 goto done;
682 }
683
684 /* Handle outgoing control frame */
685 if (hook == priv->ctrl) {
686 error = ng_l2tp_recv_ctrl(node, item);
687 goto done;
688 }
689
690 /* Handle outgoing data frame */
691 error = ng_l2tp_recv_data(node, item, NG_HOOK_PRIVATE(hook));
692
693 done:
694 /* Done */
695 L2TP_SEQ_CHECK(&priv->seq);
696 return (error);
697 }
698
699 /*
700 * Destroy node
701 */
702 static int
703 ng_l2tp_shutdown(node_p node)
704 {
705 const priv_p priv = NG_NODE_PRIVATE(node);
706 struct l2tp_seq *const seq = &priv->seq;
707
708 /* Sanity check */
709 L2TP_SEQ_CHECK(seq);
710
711 /* Reset sequence number state */
712 ng_l2tp_seq_reset(priv);
713
714 /* Free private data if neither timer is running */
715 ng_uncallout(&seq->rack_timer, node);
716 ng_uncallout(&seq->xack_timer, node);
717
718 FREE(priv, M_NETGRAPH_L2TP);
719
720 /* Unref node */
721 NG_NODE_UNREF(node);
722 return (0);
723 }
724
725 /*
726 * Hook disconnection
727 */
728 static int
729 ng_l2tp_disconnect(hook_p hook)
730 {
731 const node_p node = NG_HOOK_NODE(hook);
732 const priv_p priv = NG_NODE_PRIVATE(node);
733
734 /* Zero out hook pointer */
735 if (hook == priv->ctrl)
736 priv->ctrl = NULL;
737 else if (hook == priv->lower)
738 priv->lower = NULL;
739 else {
740 FREE(NG_HOOK_PRIVATE(hook), M_NETGRAPH_L2TP);
741 NG_HOOK_SET_PRIVATE(hook, NULL);
742 }
743
744 /* Go away if no longer connected to anything */
745 if (NG_NODE_NUMHOOKS(node) == 0 && NG_NODE_IS_VALID(node))
746 ng_rmnode_self(node);
747 return (0);
748 }
749
750 /*************************************************************************
751 INTERNAL FUNCTIONS
752 *************************************************************************/
753
754 /*
755 * Find the hook with a given session ID.
756 */
757 static int
758 ng_l2tp_find_session(hook_p hook, void *arg)
759 {
760 const hookpriv_p hpriv = NG_HOOK_PRIVATE(hook);
761 const u_int16_t sid = (u_int16_t)(uintptr_t)arg;
762
763 if (hpriv == NULL || hpriv->conf.session_id != sid)
764 return (-1);
765 return (0);
766 }
767
768 /*
769 * Reset a hook's session state.
770 */
771 static int
772 ng_l2tp_reset_session(hook_p hook, void *arg)
773 {
774 const hookpriv_p hpriv = NG_HOOK_PRIVATE(hook);
775
776 if (hpriv != NULL) {
777 hpriv->conf.control_dseq = 0;
778 hpriv->conf.enable_dseq = 0;
779 bzero(&hpriv->conf, sizeof(struct ng_l2tp_session_stats));
780 hpriv->nr = 0;
781 hpriv->ns = 0;
782 }
783 return (-1);
784 }
785
786 /*
787 * Handle an incoming frame from below.
788 */
789 static int
790 ng_l2tp_recv_lower(node_p node, item_p item)
791 {
792 static const u_int16_t req_bits[2][2] = {
793 { L2TP_DATA_0BITS, L2TP_DATA_1BITS },
794 { L2TP_CTRL_0BITS, L2TP_CTRL_1BITS },
795 };
796 const priv_p priv = NG_NODE_PRIVATE(node);
797 hookpriv_p hpriv = NULL;
798 hook_p hook = NULL;
799 u_int16_t ids[2];
800 struct mbuf *m;
801 u_int16_t hdr;
802 u_int16_t ns;
803 u_int16_t nr;
804 int is_ctrl;
805 int error;
806 int len, plen;
807
808 /* Grab mbuf */
809 NGI_GET_M(item, m);
810
811 /* Remember full packet length; needed for per session accounting. */
812 plen = m->m_pkthdr.len;
813
814 /* Update stats */
815 priv->stats.recvPackets++;
816 priv->stats.recvOctets += plen;
817
818 /* Get initial header */
819 if (m->m_pkthdr.len < 6) {
820 priv->stats.recvRunts++;
821 NG_FREE_ITEM(item);
822 NG_FREE_M(m);
823 return (EINVAL);
824 }
825 if (m->m_len < 2 && (m = m_pullup(m, 2)) == NULL) {
826 priv->stats.memoryFailures++;
827 NG_FREE_ITEM(item);
828 return (EINVAL);
829 }
830 hdr = ntohs(*mtod(m, u_int16_t *));
831 m_adj(m, 2);
832
833 /* Check required header bits and minimum length */
834 is_ctrl = (hdr & L2TP_HDR_CTRL) != 0;
835 if ((hdr & req_bits[is_ctrl][0]) != 0
836 || (~hdr & req_bits[is_ctrl][1]) != 0) {
837 priv->stats.recvInvalid++;
838 NG_FREE_ITEM(item);
839 NG_FREE_M(m);
840 return (EINVAL);
841 }
842 if (m->m_pkthdr.len < 4 /* tunnel, session id */
843 + (2 * ((hdr & L2TP_HDR_LEN) != 0)) /* length field */
844 + (4 * ((hdr & L2TP_HDR_SEQ) != 0)) /* seq # fields */
845 + (2 * ((hdr & L2TP_HDR_OFF) != 0))) { /* offset field */
846 priv->stats.recvRunts++;
847 NG_FREE_ITEM(item);
848 NG_FREE_M(m);
849 return (EINVAL);
850 }
851
852 /* Get and validate length field if present */
853 if ((hdr & L2TP_HDR_LEN) != 0) {
854 if (m->m_len < 2 && (m = m_pullup(m, 2)) == NULL) {
855 priv->stats.memoryFailures++;
856 NG_FREE_ITEM(item);
857 return (EINVAL);
858 }
859 len = (u_int16_t)ntohs(*mtod(m, u_int16_t *)) - 4;
860 m_adj(m, 2);
861 if (len < 0 || len > m->m_pkthdr.len) {
862 priv->stats.recvInvalid++;
863 NG_FREE_ITEM(item);
864 NG_FREE_M(m);
865 return (EINVAL);
866 }
867 if (len < m->m_pkthdr.len) /* trim extra bytes */
868 m_adj(m, -(m->m_pkthdr.len - len));
869 }
870
871 /* Get tunnel ID and session ID */
872 if (m->m_len < 4 && (m = m_pullup(m, 4)) == NULL) {
873 priv->stats.memoryFailures++;
874 NG_FREE_ITEM(item);
875 return (EINVAL);
876 }
877 memcpy(ids, mtod(m, u_int16_t *), 4);
878 m_adj(m, 4);
879
880 /* Check tunnel ID */
881 if (ids[0] != priv->conf.tunnel_id
882 && (priv->conf.match_id || ids[0] != 0)) {
883 priv->stats.recvWrongTunnel++;
884 NG_FREE_ITEM(item);
885 NG_FREE_M(m);
886 return (EADDRNOTAVAIL);
887 }
888
889 /* Check session ID (for data packets only) */
890 if ((hdr & L2TP_HDR_CTRL) == 0) {
891 NG_NODE_FOREACH_HOOK(node, ng_l2tp_find_session,
892 (void *)(uintptr_t)ids[1], hook);
893 if (hook == NULL) {
894 priv->stats.recvUnknownSID++;
895 NG_FREE_ITEM(item);
896 NG_FREE_M(m);
897 return (ENOTCONN);
898 }
899 hpriv = NG_HOOK_PRIVATE(hook);
900 }
901
902 /* Get Ns, Nr fields if present */
903 if ((hdr & L2TP_HDR_SEQ) != 0) {
904 if (m->m_len < 4 && (m = m_pullup(m, 4)) == NULL) {
905 priv->stats.memoryFailures++;
906 NG_FREE_ITEM(item);
907 return (EINVAL);
908 }
909 memcpy(&ns, &mtod(m, u_int16_t *)[0], 2);
910 ns = ntohs(ns);
911 memcpy(&nr, &mtod(m, u_int16_t *)[1], 2);
912 nr = ntohs(nr);
913 m_adj(m, 4);
914 }
915
916 /* Strip offset padding if present */
917 if ((hdr & L2TP_HDR_OFF) != 0) {
918 u_int16_t offset;
919
920 /* Get length of offset padding */
921 if (m->m_len < 2 && (m = m_pullup(m, 2)) == NULL) {
922 priv->stats.memoryFailures++;
923 NG_FREE_ITEM(item);
924 return (EINVAL);
925 }
926 memcpy(&offset, mtod(m, u_int16_t *), 2);
927 offset = ntohs(offset);
928
929 /* Trim offset padding */
930 if ((2+offset) > m->m_pkthdr.len) {
931 priv->stats.recvInvalid++;
932 NG_FREE_ITEM(item);
933 NG_FREE_M(m);
934 return (EINVAL);
935 }
936 m_adj(m, 2+offset);
937 }
938
939 /* Handle control packets */
940 if ((hdr & L2TP_HDR_CTRL) != 0) {
941
942 /* Handle receive ack sequence number Nr */
943 ng_l2tp_seq_recv_nr(priv, nr);
944
945 /* Discard ZLB packets */
946 if (m->m_pkthdr.len == 0) {
947 priv->stats.recvZLBs++;
948 NG_FREE_ITEM(item);
949 NG_FREE_M(m);
950 return (0);
951 }
952
953 /*
954 * Prepend session ID to packet here: we don't want to accept
955 * the send sequence number Ns if we have to drop the packet
956 * later because of a memory error, because then the upper
957 * layer would never get the packet.
958 */
959 M_PREPEND(m, 2, M_DONTWAIT);
960 if (m == NULL) {
961 priv->stats.memoryFailures++;
962 NG_FREE_ITEM(item);
963 return (ENOBUFS);
964 }
965 memcpy(mtod(m, u_int16_t *), &ids[1], 2);
966
967 /* Now handle send sequence number */
968 if (ng_l2tp_seq_recv_ns(priv, ns) == -1) {
969 NG_FREE_ITEM(item);
970 NG_FREE_M(m);
971 return (0);
972 }
973
974 /* Deliver packet to upper layers */
975 NG_FWD_NEW_DATA(error, item, priv->ctrl, m);
976 return (error);
977 }
978
979 /* Per session packet, account it. */
980 hpriv->stats.recvPackets++;
981 hpriv->stats.recvOctets += plen;
982
983 /* Follow peer's lead in data sequencing, if configured to do so */
984 if (!hpriv->conf.control_dseq)
985 hpriv->conf.enable_dseq = ((hdr & L2TP_HDR_SEQ) != 0);
986
987 /* Handle data sequence numbers if present and enabled */
988 if ((hdr & L2TP_HDR_SEQ) != 0) {
989 if (hpriv->conf.enable_dseq
990 && L2TP_SEQ_DIFF(ns, hpriv->nr) < 0) {
991 NG_FREE_ITEM(item); /* duplicate or out of order */
992 NG_FREE_M(m);
993 priv->stats.recvDataDrops++;
994 return (0);
995 }
996 hpriv->nr = ns + 1;
997 }
998
999 /* Drop empty data packets */
1000 if (m->m_pkthdr.len == 0) {
1001 NG_FREE_ITEM(item);
1002 NG_FREE_M(m);
1003 return (0);
1004 }
1005
1006 /* Deliver data */
1007 NG_FWD_NEW_DATA(error, item, hook, m);
1008 return (error);
1009 }
1010
1011 /*
1012 * Handle an outgoing control frame.
1013 */
1014 static int
1015 ng_l2tp_recv_ctrl(node_p node, item_p item)
1016 {
1017 const priv_p priv = NG_NODE_PRIVATE(node);
1018 struct l2tp_seq *const seq = &priv->seq;
1019 struct mbuf *m;
1020 int i;
1021
1022 /* Grab mbuf and discard other stuff XXX */
1023 NGI_GET_M(item, m);
1024 NG_FREE_ITEM(item);
1025
1026 /* Packet should have session ID prepended */
1027 if (m->m_pkthdr.len < 2) {
1028 priv->stats.xmitInvalid++;
1029 m_freem(m);
1030 return (EINVAL);
1031 }
1032
1033 /* Check max length */
1034 if (m->m_pkthdr.len >= 0x10000 - 14) {
1035 priv->stats.xmitTooBig++;
1036 m_freem(m);
1037 return (EOVERFLOW);
1038 }
1039
1040 /* Find next empty slot in transmit queue */
1041 for (i = 0; i < L2TP_MAX_XWIN && seq->xwin[i] != NULL; i++);
1042 if (i == L2TP_MAX_XWIN) {
1043 priv->stats.xmitDrops++;
1044 m_freem(m);
1045 return (ENOBUFS);
1046 }
1047 seq->xwin[i] = m;
1048
1049 /* Sanity check receive ack timer state */
1050 KASSERT((i == 0) ^ callout_pending(&seq->rack_timer),
1051 ("%s: xwin %d full but rack timer %s running",
1052 __FUNCTION__, i, callout_pending(&seq->rack_timer) ? "" : "not "));
1053
1054 /* If peer's receive window is already full, nothing else to do */
1055 if (i >= seq->cwnd)
1056 return (0);
1057
1058 /* Start retransmit timer if not already running */
1059 if (!callout_pending(&seq->rack_timer))
1060 ng_callout(&seq->rack_timer, node, NULL,
1061 hz, ng_l2tp_seq_rack_timeout, NULL, 0);
1062
1063 /* Copy packet */
1064 if ((m = L2TP_COPY_MBUF(seq->xwin[i], M_DONTWAIT)) == NULL) {
1065 priv->stats.memoryFailures++;
1066 return (ENOBUFS);
1067 }
1068
1069 /* Send packet and increment xmit sequence number */
1070 return (ng_l2tp_xmit_ctrl(priv, m, seq->ns++));
1071 }
1072
1073 /*
1074 * Handle an outgoing data frame.
1075 */
1076 static int
1077 ng_l2tp_recv_data(node_p node, item_p item, hookpriv_p hpriv)
1078 {
1079 const priv_p priv = NG_NODE_PRIVATE(node);
1080 struct mbuf *m;
1081 u_int16_t hdr;
1082 int error;
1083 int i = 1;
1084
1085 /* Get mbuf */
1086 NGI_GET_M(item, m);
1087
1088 /* Check max length */
1089 if (m->m_pkthdr.len >= 0x10000 - 12) {
1090 priv->stats.xmitDataTooBig++;
1091 NG_FREE_ITEM(item);
1092 NG_FREE_M(m);
1093 return (EOVERFLOW);
1094 }
1095
1096 /* Prepend L2TP header */
1097 M_PREPEND(m, 6
1098 + (2 * (hpriv->conf.include_length != 0))
1099 + (4 * (hpriv->conf.enable_dseq != 0)),
1100 M_DONTWAIT);
1101 if (m == NULL) {
1102 priv->stats.memoryFailures++;
1103 NG_FREE_ITEM(item);
1104 return (ENOBUFS);
1105 }
1106 hdr = L2TP_DATA_HDR;
1107 if (hpriv->conf.include_length) {
1108 hdr |= L2TP_HDR_LEN;
1109 mtod(m, u_int16_t *)[i++] = htons(m->m_pkthdr.len);
1110 }
1111 mtod(m, u_int16_t *)[i++] = priv->conf.peer_id;
1112 mtod(m, u_int16_t *)[i++] = hpriv->conf.peer_id;
1113 if (hpriv->conf.enable_dseq) {
1114 hdr |= L2TP_HDR_SEQ;
1115 mtod(m, u_int16_t *)[i++] = htons(hpriv->ns);
1116 mtod(m, u_int16_t *)[i++] = htons(hpriv->nr);
1117 hpriv->ns++;
1118 }
1119 mtod(m, u_int16_t *)[0] = htons(hdr);
1120
1121 /* Update per session stats. */
1122 hpriv->stats.xmitPackets++;
1123 hpriv->stats.xmitOctets += m->m_pkthdr.len;
1124
1125 /* Send packet */
1126 NG_FWD_NEW_DATA(error, item, priv->lower, m);
1127 return (error);
1128 }
1129
1130 /*
1131 * Send a message to our controlling node that we've failed.
1132 */
1133 static void
1134 ng_l2tp_seq_failure(priv_p priv)
1135 {
1136 struct ng_mesg *msg;
1137 int error;
1138
1139 NG_MKMESSAGE(msg, NGM_L2TP_COOKIE, NGM_L2TP_ACK_FAILURE, 0, M_NOWAIT);
1140 if (msg == NULL)
1141 return;
1142 NG_SEND_MSG_ID(error, priv->node, msg, priv->ftarget, 0);
1143 }
1144
1145 /************************************************************************
1146 SEQUENCE NUMBER HANDLING
1147 ************************************************************************/
1148
1149 /*
1150 * Initialize sequence number state.
1151 */
1152 static void
1153 ng_l2tp_seq_init(priv_p priv)
1154 {
1155 struct l2tp_seq *const seq = &priv->seq;
1156
1157 KASSERT(priv->conf.peer_win >= 1,
1158 ("%s: peer_win is zero", __FUNCTION__));
1159 memset(seq, 0, sizeof(*seq));
1160 seq->cwnd = 1;
1161 seq->wmax = priv->conf.peer_win;
1162 if (seq->wmax > L2TP_MAX_XWIN)
1163 seq->wmax = L2TP_MAX_XWIN;
1164 seq->ssth = seq->wmax;
1165 seq->max_rexmits = priv->conf.rexmit_max;
1166 seq->max_rexmit_to = priv->conf.rexmit_max_to;
1167 ng_callout_init(&seq->rack_timer);
1168 ng_callout_init(&seq->xack_timer);
1169 L2TP_SEQ_CHECK(seq);
1170 }
1171
1172 /*
1173 * Set sequence number state as given from user.
1174 */
1175 static int
1176 ng_l2tp_seq_set(priv_p priv, const struct ng_l2tp_seq_config *conf)
1177 {
1178 struct l2tp_seq *const seq = &priv->seq;
1179
1180 /* If node is enabled, deny update to sequence numbers. */
1181 if (priv->conf.enabled)
1182 return (EBUSY);
1183
1184 /* We only can handle the simple cases. */
1185 if (conf->xack != conf->nr || conf->ns != conf->rack)
1186 return (EINVAL);
1187
1188 /* Set ns,nr,rack,xack parameters. */
1189 seq->ns = conf->ns;
1190 seq->nr = conf->nr;
1191 seq->rack = conf->rack;
1192 seq->xack = conf->xack;
1193
1194 return (0);
1195 }
1196
1197 /*
1198 * Adjust sequence number state accordingly after reconfiguration.
1199 */
1200 static int
1201 ng_l2tp_seq_adjust(priv_p priv, const struct ng_l2tp_config *conf)
1202 {
1203 struct l2tp_seq *const seq = &priv->seq;
1204 u_int16_t new_wmax;
1205
1206 /* If disabling node, reset state sequence number */
1207 if (!conf->enabled) {
1208 ng_l2tp_seq_reset(priv);
1209 return (0);
1210 }
1211
1212 /* Adjust peer's max recv window; it can only increase */
1213 new_wmax = conf->peer_win;
1214 if (new_wmax > L2TP_MAX_XWIN)
1215 new_wmax = L2TP_MAX_XWIN;
1216 if (new_wmax == 0)
1217 return (EINVAL);
1218 if (new_wmax < seq->wmax)
1219 return (EBUSY);
1220 seq->wmax = new_wmax;
1221
1222 /* Update retransmit parameters */
1223 seq->max_rexmits = conf->rexmit_max;
1224 seq->max_rexmit_to = conf->rexmit_max_to;
1225
1226 /* Done */
1227 return (0);
1228 }
1229
1230 /*
1231 * Reset sequence number state.
1232 */
1233 static void
1234 ng_l2tp_seq_reset(priv_p priv)
1235 {
1236 struct l2tp_seq *const seq = &priv->seq;
1237 hook_p hook;
1238 int i;
1239
1240 /* Sanity check */
1241 L2TP_SEQ_CHECK(seq);
1242
1243 /* Stop timers */
1244 ng_uncallout(&seq->rack_timer, priv->node);
1245 ng_uncallout(&seq->xack_timer, priv->node);
1246
1247 /* Free retransmit queue */
1248 for (i = 0; i < L2TP_MAX_XWIN; i++) {
1249 if (seq->xwin[i] == NULL)
1250 break;
1251 m_freem(seq->xwin[i]);
1252 }
1253
1254 /* Reset session hooks' sequence number states */
1255 NG_NODE_FOREACH_HOOK(priv->node, ng_l2tp_reset_session, NULL, hook);
1256
1257 /* Reset node's sequence number state */
1258 memset(seq, 0, sizeof(*seq));
1259 seq->cwnd = 1;
1260 seq->wmax = L2TP_MAX_XWIN;
1261 seq->ssth = seq->wmax;
1262
1263 /* Done */
1264 L2TP_SEQ_CHECK(seq);
1265 }
1266
1267 /*
1268 * Handle receipt of an acknowledgement value (Nr) from peer.
1269 */
1270 static void
1271 ng_l2tp_seq_recv_nr(priv_p priv, u_int16_t nr)
1272 {
1273 struct l2tp_seq *const seq = &priv->seq;
1274 struct mbuf *m;
1275 int nack;
1276 int i;
1277
1278 /* Verify peer's ACK is in range */
1279 if ((nack = L2TP_SEQ_DIFF(nr, seq->rack)) <= 0)
1280 return; /* duplicate ack */
1281 if (L2TP_SEQ_DIFF(nr, seq->ns) > 0) {
1282 priv->stats.recvBadAcks++; /* ack for packet not sent */
1283 return;
1284 }
1285 KASSERT(nack <= L2TP_MAX_XWIN,
1286 ("%s: nack=%d > %d", __FUNCTION__, nack, L2TP_MAX_XWIN));
1287
1288 /* Update receive ack stats */
1289 seq->rack = nr;
1290 seq->rexmits = 0;
1291
1292 /* Free acknowledged packets and shift up packets in the xmit queue */
1293 for (i = 0; i < nack; i++)
1294 m_freem(seq->xwin[i]);
1295 memmove(seq->xwin, seq->xwin + nack,
1296 (L2TP_MAX_XWIN - nack) * sizeof(*seq->xwin));
1297 memset(seq->xwin + (L2TP_MAX_XWIN - nack), 0,
1298 nack * sizeof(*seq->xwin));
1299
1300 /*
1301 * Do slow-start/congestion avoidance windowing algorithm described
1302 * in RFC 2661, Appendix A. Here we handle a multiple ACK as if each
1303 * ACK had arrived separately.
1304 */
1305 if (seq->cwnd < seq->wmax) {
1306
1307 /* Handle slow start phase */
1308 if (seq->cwnd < seq->ssth) {
1309 seq->cwnd += nack;
1310 nack = 0;
1311 if (seq->cwnd > seq->ssth) { /* into cg.av. phase */
1312 nack = seq->cwnd - seq->ssth;
1313 seq->cwnd = seq->ssth;
1314 }
1315 }
1316
1317 /* Handle congestion avoidance phase */
1318 if (seq->cwnd >= seq->ssth) {
1319 seq->acks += nack;
1320 while (seq->acks >= seq->cwnd) {
1321 seq->acks -= seq->cwnd;
1322 if (seq->cwnd < seq->wmax)
1323 seq->cwnd++;
1324 }
1325 }
1326 }
1327
1328 /* Stop xmit timer */
1329 if (callout_pending(&seq->rack_timer))
1330 ng_uncallout(&seq->rack_timer, priv->node);
1331
1332 /* If transmit queue is empty, we're done for now */
1333 if (seq->xwin[0] == NULL)
1334 return;
1335
1336 /* Start restransmit timer again */
1337 ng_callout(&seq->rack_timer, priv->node, NULL,
1338 hz, ng_l2tp_seq_rack_timeout, NULL, 0);
1339
1340 /*
1341 * Send more packets, trying to keep peer's receive window full.
1342 * If there is a memory error, pretend packet was sent, as it
1343 * will get retransmitted later anyway.
1344 */
1345 while ((i = L2TP_SEQ_DIFF(seq->ns, seq->rack)) < seq->cwnd
1346 && seq->xwin[i] != NULL) {
1347 if ((m = L2TP_COPY_MBUF(seq->xwin[i], M_DONTWAIT)) == NULL)
1348 priv->stats.memoryFailures++;
1349 else
1350 ng_l2tp_xmit_ctrl(priv, m, seq->ns);
1351 seq->ns++;
1352 }
1353 }
1354
1355 /*
1356 * Handle receipt of a sequence number value (Ns) from peer.
1357 * We make no attempt to re-order out of order packets.
1358 *
1359 * This function should only be called for non-ZLB packets.
1360 *
1361 * Returns:
1362 * 0 Accept packet
1363 * -1 Drop packet
1364 */
1365 static int
1366 ng_l2tp_seq_recv_ns(priv_p priv, u_int16_t ns)
1367 {
1368 struct l2tp_seq *const seq = &priv->seq;
1369
1370 /* If not what we expect, drop packet and send an immediate ZLB ack */
1371 if (ns != seq->nr) {
1372 if (L2TP_SEQ_DIFF(ns, seq->nr) < 0)
1373 priv->stats.recvDuplicates++;
1374 else
1375 priv->stats.recvOutOfOrder++;
1376 ng_l2tp_xmit_ctrl(priv, NULL, seq->ns);
1377 return (-1);
1378 }
1379
1380 /* Update recv sequence number */
1381 seq->nr++;
1382
1383 /* Start receive ack timer, if not already running */
1384 if (!callout_pending(&seq->xack_timer))
1385 ng_callout(&seq->xack_timer, priv->node, NULL,
1386 L2TP_DELAYED_ACK, ng_l2tp_seq_xack_timeout, NULL, 0);
1387
1388 /* Accept packet */
1389 return (0);
1390 }
1391
1392 /*
1393 * Handle an ack timeout. We have an outstanding ack that we
1394 * were hoping to piggy-back, but haven't, so send a ZLB.
1395 */
1396 static void
1397 ng_l2tp_seq_xack_timeout(node_p node, hook_p hook, void *arg1, int arg2)
1398 {
1399 const priv_p priv = NG_NODE_PRIVATE(node);
1400 struct l2tp_seq *const seq = &priv->seq;
1401
1402 /* Sanity check */
1403 L2TP_SEQ_CHECK(seq);
1404
1405 /* If ack is still outstanding, send a ZLB */
1406 if (seq->xack != seq->nr)
1407 ng_l2tp_xmit_ctrl(priv, NULL, seq->ns);
1408
1409 /* Done */
1410 L2TP_SEQ_CHECK(seq);
1411 }
1412
1413 /*
1414 * Handle a transmit timeout. The peer has failed to respond
1415 * with an ack for our packet, so retransmit it.
1416 */
1417 static void
1418 ng_l2tp_seq_rack_timeout(node_p node, hook_p hook, void *arg1, int arg2)
1419 {
1420 const priv_p priv = NG_NODE_PRIVATE(node);
1421 struct l2tp_seq *const seq = &priv->seq;
1422 struct mbuf *m;
1423 u_int delay;
1424
1425 /* Sanity check */
1426 L2TP_SEQ_CHECK(seq);
1427
1428 /* Make sure peer's ack is still outstanding before doing anything */
1429 if (seq->rack == seq->ns)
1430 goto done;
1431
1432 priv->stats.xmitRetransmits++;
1433
1434 /* Have we reached the retransmit limit? If so, notify owner. */
1435 if (seq->rexmits++ >= seq->max_rexmits)
1436 ng_l2tp_seq_failure(priv);
1437
1438 /* Restart timer, this time with an increased delay */
1439 delay = (seq->rexmits > 12) ? (1 << 12) : (1 << seq->rexmits);
1440 if (delay > seq->max_rexmit_to)
1441 delay = seq->max_rexmit_to;
1442 ng_callout(&seq->rack_timer, node, NULL,
1443 hz * delay, ng_l2tp_seq_rack_timeout, NULL, 0);
1444
1445 /* Do slow-start/congestion algorithm windowing algorithm */
1446 seq->ssth = (seq->cwnd + 1) / 2;
1447 seq->cwnd = 1;
1448 seq->acks = 0;
1449
1450 /* Retransmit oldest unack'd packet */
1451 if ((m = L2TP_COPY_MBUF(seq->xwin[0], M_DONTWAIT)) == NULL)
1452 priv->stats.memoryFailures++;
1453 else
1454 ng_l2tp_xmit_ctrl(priv, m, seq->rack);
1455
1456 done:
1457 /* Done */
1458 L2TP_SEQ_CHECK(seq);
1459 }
1460
1461 /*
1462 * Transmit a control stream packet, payload optional.
1463 * The transmit sequence number is not incremented.
1464 */
1465 static int
1466 ng_l2tp_xmit_ctrl(priv_p priv, struct mbuf *m, u_int16_t ns)
1467 {
1468 struct l2tp_seq *const seq = &priv->seq;
1469 u_int16_t session_id = 0;
1470 int error;
1471
1472 /* If no mbuf passed, send an empty packet (ZLB) */
1473 if (m == NULL) {
1474
1475 /* Create a new mbuf for ZLB packet */
1476 MGETHDR(m, M_DONTWAIT, MT_DATA);
1477 if (m == NULL) {
1478 priv->stats.memoryFailures++;
1479 return (ENOBUFS);
1480 }
1481 m->m_len = m->m_pkthdr.len = 12;
1482 m->m_pkthdr.rcvif = NULL;
1483 priv->stats.xmitZLBs++;
1484 } else {
1485
1486 /* Strip off session ID */
1487 if (m->m_len < 2 && (m = m_pullup(m, 2)) == NULL) {
1488 priv->stats.memoryFailures++;
1489 return (ENOBUFS);
1490 }
1491 memcpy(&session_id, mtod(m, u_int16_t *), 2);
1492 m_adj(m, 2);
1493
1494 /* Make room for L2TP header */
1495 M_PREPEND(m, 12, M_DONTWAIT);
1496 if (m == NULL) {
1497 priv->stats.memoryFailures++;
1498 return (ENOBUFS);
1499 }
1500 }
1501
1502 /* Fill in L2TP header */
1503 mtod(m, u_int16_t *)[0] = htons(L2TP_CTRL_HDR);
1504 mtod(m, u_int16_t *)[1] = htons(m->m_pkthdr.len);
1505 mtod(m, u_int16_t *)[2] = priv->conf.peer_id;
1506 mtod(m, u_int16_t *)[3] = session_id;
1507 mtod(m, u_int16_t *)[4] = htons(ns);
1508 mtod(m, u_int16_t *)[5] = htons(seq->nr);
1509
1510 /* Update sequence number info and stats */
1511 priv->stats.xmitPackets++;
1512 priv->stats.xmitOctets += m->m_pkthdr.len;
1513
1514 /* Stop ack timer: we're sending an ack with this packet */
1515 if (callout_pending(&seq->xack_timer))
1516 ng_uncallout(&seq->xack_timer, priv->node);
1517
1518 seq->xack = seq->nr;
1519
1520 /* Send packet */
1521 NG_SEND_DATA_ONLY(error, priv->lower, m);
1522 return (error);
1523 }
1524
1525 #ifdef INVARIANTS
1526 /*
1527 * Sanity check sequence number state.
1528 */
1529 static void
1530 ng_l2tp_seq_check(struct l2tp_seq *seq)
1531 {
1532 const int self_unack = L2TP_SEQ_DIFF(seq->nr, seq->xack);
1533 const int peer_unack = L2TP_SEQ_DIFF(seq->ns, seq->rack);
1534 int i;
1535
1536 #define CHECK(p) KASSERT((p), ("%s: not: %s", __FUNCTION__, #p))
1537
1538 CHECK(seq->wmax <= L2TP_MAX_XWIN);
1539 CHECK(seq->cwnd >= 1);
1540 CHECK(seq->cwnd <= seq->wmax);
1541 CHECK(seq->ssth >= 1);
1542 CHECK(seq->ssth <= seq->wmax);
1543 if (seq->cwnd < seq->ssth)
1544 CHECK(seq->acks == 0);
1545 else
1546 CHECK(seq->acks <= seq->cwnd);
1547 CHECK(self_unack >= 0);
1548 CHECK(peer_unack >= 0);
1549 CHECK(peer_unack <= seq->wmax);
1550 CHECK((self_unack == 0) ^ callout_pending(&seq->xack_timer));
1551 CHECK((peer_unack == 0) ^ callout_pending(&seq->rack_timer));
1552 for (i = 0; i < peer_unack; i++)
1553 CHECK(seq->xwin[i] != NULL);
1554 for ( ; i < seq->cwnd; i++) /* verify peer's recv window full */
1555 CHECK(seq->xwin[i] == NULL);
1556
1557 #undef CHECK
1558 }
1559 #endif /* INVARIANTS */
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