1
2 /*
3 * Copyright (c) 2001-2002 Packet Design, LLC.
4 * All rights reserved.
5 *
6 * Subject to the following obligations and disclaimer of warranty,
7 * use and redistribution of this software, in source or object code
8 * forms, with or without modifications are expressly permitted by
9 * Packet Design; provided, however, that:
10 *
11 * (i) Any and all reproductions of the source or object code
12 * must include the copyright notice above and the following
13 * disclaimer of warranties; and
14 * (ii) No rights are granted, in any manner or form, to use
15 * Packet Design trademarks, including the mark "PACKET DESIGN"
16 * on advertising, endorsements, or otherwise except as such
17 * appears in the above copyright notice or in the software.
18 *
19 * THIS SOFTWARE IS BEING PROVIDED BY PACKET DESIGN "AS IS", AND
20 * TO THE MAXIMUM EXTENT PERMITTED BY LAW, PACKET DESIGN MAKES NO
21 * REPRESENTATIONS OR WARRANTIES, EXPRESS OR IMPLIED, REGARDING
22 * THIS SOFTWARE, INCLUDING WITHOUT LIMITATION, ANY AND ALL IMPLIED
23 * WARRANTIES OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE,
24 * OR NON-INFRINGEMENT. PACKET DESIGN DOES NOT WARRANT, GUARANTEE,
25 * OR MAKE ANY REPRESENTATIONS REGARDING THE USE OF, OR THE RESULTS
26 * OF THE USE OF THIS SOFTWARE IN TERMS OF ITS CORRECTNESS, ACCURACY,
27 * RELIABILITY OR OTHERWISE. IN NO EVENT SHALL PACKET DESIGN BE
28 * LIABLE FOR ANY DAMAGES RESULTING FROM OR ARISING OUT OF ANY USE
29 * OF THIS SOFTWARE, INCLUDING WITHOUT LIMITATION, ANY DIRECT,
30 * INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, PUNITIVE, OR CONSEQUENTIAL
31 * DAMAGES, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES, LOSS OF
32 * USE, DATA OR PROFITS, HOWEVER CAUSED AND UNDER ANY THEORY OF
33 * LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
34 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF
35 * THE USE OF THIS SOFTWARE, EVEN IF PACKET DESIGN IS ADVISED OF
36 * THE POSSIBILITY OF SUCH DAMAGE.
37 *
38 * Author: Archie Cobbs <archie@freebsd.org>
39 *
40 * $FreeBSD$
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
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 u_char rack_timer_running; /* xmit timer running */
133 u_char xack_timer_running; /* ack timer running */
134 struct mbuf *xwin[L2TP_MAX_XWIN]; /* transmit window */
135 };
136
137 /* Node private data */
138 struct ng_l2tp_private {
139 node_p node; /* back pointer to node */
140 hook_p ctrl; /* hook to upper layers */
141 hook_p lower; /* hook to lower layers */
142 struct ng_l2tp_config conf; /* node configuration */
143 struct ng_l2tp_stats stats; /* node statistics */
144 struct l2tp_seq seq; /* ctrl sequence number state */
145 char *ftarget; /* failure message target */
146 };
147 typedef struct ng_l2tp_private *priv_p;
148
149 /* Hook private data (data session hooks only) */
150 struct ng_l2tp_hook_private {
151 struct ng_l2tp_sess_config conf; /* hook/session config */
152 u_int16_t ns; /* data ns sequence number */
153 u_int16_t nr; /* data nr sequence number */
154 };
155 typedef struct ng_l2tp_hook_private *hookpriv_p;
156
157 /* Netgraph node methods */
158 static ng_constructor_t ng_l2tp_constructor;
159 static ng_rcvmsg_t ng_l2tp_rcvmsg;
160 static ng_shutdown_t ng_l2tp_shutdown;
161 static ng_newhook_t ng_l2tp_newhook;
162 static ng_rcvdata_t ng_l2tp_rcvdata;
163 static ng_disconnect_t ng_l2tp_disconnect;
164
165 /* Internal functions */
166 static int ng_l2tp_recv_lower(node_p node, struct mbuf *m, meta_p meta);
167 static int ng_l2tp_recv_ctrl(node_p node, struct mbuf *m, meta_p meta);
168 static int ng_l2tp_recv_data(node_p node,
169 struct mbuf *m, meta_p meta, hookpriv_p hpriv);
170
171 static int ng_l2tp_xmit_ctrl(priv_p priv, struct mbuf *m, u_int16_t ns);
172
173 static void ng_l2tp_seq_init(priv_p priv);
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(void *arg);
181 static void ng_l2tp_seq_rack_timeout(void *arg);
182
183 #ifdef INVARIANTS
184 static void ng_l2tp_seq_check(struct l2tp_seq *seq);
185 #endif
186
187 /* Parse type for struct ng_l2tp_config */
188 static const struct ng_parse_struct_field
189 ng_l2tp_config_type_fields[] = NG_L2TP_CONFIG_TYPE_INFO;
190 static const struct ng_parse_type ng_l2tp_config_type = {
191 &ng_parse_struct_type,
192 &ng_l2tp_config_type_fields,
193 };
194
195 /* Parse type for struct ng_l2tp_sess_config */
196 static const struct ng_parse_struct_field
197 ng_l2tp_sess_config_type_fields[] = NG_L2TP_SESS_CONFIG_TYPE_INFO;
198 static const struct ng_parse_type ng_l2tp_sess_config_type = {
199 &ng_parse_struct_type,
200 &ng_l2tp_sess_config_type_fields,
201 };
202
203 /* Parse type for struct ng_l2tp_stats */
204 static const struct ng_parse_struct_field
205 ng_l2tp_stats_type_fields[] = NG_L2TP_STATS_TYPE_INFO;
206 static const struct ng_parse_type ng_l2tp_stats_type = {
207 &ng_parse_struct_type,
208 &ng_l2tp_stats_type_fields
209 };
210
211 /* List of commands and how to convert arguments to/from ASCII */
212 static const struct ng_cmdlist ng_l2tp_cmdlist[] = {
213 {
214 NGM_L2TP_COOKIE,
215 NGM_L2TP_SET_CONFIG,
216 "setconfig",
217 &ng_l2tp_config_type,
218 NULL
219 },
220 {
221 NGM_L2TP_COOKIE,
222 NGM_L2TP_GET_CONFIG,
223 "getconfig",
224 NULL,
225 &ng_l2tp_config_type
226 },
227 {
228 NGM_L2TP_COOKIE,
229 NGM_L2TP_SET_SESS_CONFIG,
230 "setsessconfig",
231 &ng_l2tp_sess_config_type,
232 NULL
233 },
234 {
235 NGM_L2TP_COOKIE,
236 NGM_L2TP_GET_SESS_CONFIG,
237 "getsessconfig",
238 &ng_parse_hint16_type,
239 &ng_l2tp_sess_config_type
240 },
241 {
242 NGM_L2TP_COOKIE,
243 NGM_L2TP_GET_STATS,
244 "getstats",
245 NULL,
246 &ng_l2tp_stats_type
247 },
248 {
249 NGM_L2TP_COOKIE,
250 NGM_L2TP_CLR_STATS,
251 "clrstats",
252 NULL,
253 NULL
254 },
255 {
256 NGM_L2TP_COOKIE,
257 NGM_L2TP_GETCLR_STATS,
258 "getclrstats",
259 NULL,
260 &ng_l2tp_stats_type
261 },
262 {
263 NGM_L2TP_COOKIE,
264 NGM_L2TP_ACK_FAILURE,
265 "ackfailure",
266 NULL,
267 NULL
268 },
269 { 0 }
270 };
271
272 /* Node type descriptor */
273 static struct ng_type ng_l2tp_typestruct = {
274 NG_VERSION,
275 NG_L2TP_NODE_TYPE,
276 NULL,
277 ng_l2tp_constructor,
278 ng_l2tp_rcvmsg,
279 ng_l2tp_shutdown,
280 ng_l2tp_newhook,
281 NULL,
282 NULL,
283 ng_l2tp_rcvdata,
284 ng_l2tp_rcvdata,
285 ng_l2tp_disconnect,
286 ng_l2tp_cmdlist
287 };
288 NETGRAPH_INIT(l2tp, &ng_l2tp_typestruct);
289
290 /* Sequence number state sanity checking */
291 #ifdef INVARIANTS
292 #define L2TP_SEQ_CHECK(seq) ng_l2tp_seq_check(seq)
293 #else
294 #define L2TP_SEQ_CHECK(x) do { } while (0)
295 #endif
296
297 /* mem*() macros */
298 #define memmove(d, s, l) ovbcopy(s, d, l)
299 #define memset(d, z, l) bzero(d, l) /* XXX */
300
301 /* Whether to use m_copypacket() or m_dup() */
302 #define L2TP_COPY_MBUF m_copypacket
303
304 /************************************************************************
305 NETGRAPH NODE STUFF
306 ************************************************************************/
307
308 /*
309 * Node type constructor
310 */
311 static int
312 ng_l2tp_constructor(node_p *nodep)
313 {
314 priv_p priv;
315 int error;
316
317 /* Allocate private structure */
318 MALLOC(priv, priv_p, sizeof(*priv), M_NETGRAPH_L2TP, M_NOWAIT | M_ZERO);
319 if (priv == NULL)
320 return (ENOMEM);
321
322 /* Apply a semi-reasonable default configuration */
323 priv->conf.peer_win = 1;
324 priv->conf.rexmit_max = L2TP_MAX_REXMIT;
325 priv->conf.rexmit_max_to = L2TP_MAX_REXMIT_TO;
326
327 /* Initialize sequence number state */
328 ng_l2tp_seq_init(priv);
329
330 /* Call generic node constructor */
331 if ((error = ng_make_node_common(&ng_l2tp_typestruct, nodep))) {
332 FREE(priv, M_NETGRAPH_L2TP);
333 return (error);
334 }
335 NG_NODE_SET_PRIVATE(*nodep, priv);
336 priv->node = *nodep;
337
338 /* Done */
339 return (0);
340 }
341
342 /*
343 * Give our OK for a hook to be added.
344 */
345 static int
346 ng_l2tp_newhook(node_p node, hook_p hook, const char *name)
347 {
348 const priv_p priv = NG_NODE_PRIVATE(node);
349
350 /* Check hook name */
351 if (strcmp(name, NG_L2TP_HOOK_CTRL) == 0) {
352 if (priv->ctrl != NULL)
353 return (EISCONN);
354 priv->ctrl = hook;
355 } else if (strcmp(name, NG_L2TP_HOOK_LOWER) == 0) {
356 if (priv->lower != NULL)
357 return (EISCONN);
358 priv->lower = hook;
359 } else {
360 static const char hexdig[16] = "0123456789abcdef";
361 u_int16_t session_id;
362 hookpriv_p hpriv;
363 const char *hex;
364 int i;
365 int j;
366
367 /* Parse hook name to get session ID */
368 if (strncmp(name, NG_L2TP_HOOK_SESSION_P,
369 sizeof(NG_L2TP_HOOK_SESSION_P) - 1) != 0)
370 return (EINVAL);
371 hex = name + sizeof(NG_L2TP_HOOK_SESSION_P) - 1;
372 for (session_id = i = 0; i < 4; i++) {
373 for (j = 0; j < 16 && hex[i] != hexdig[j]; j++);
374 if (j == 16)
375 return (EINVAL);
376 session_id = (session_id << 4) | j;
377 }
378 if (hex[i] != '\0')
379 return (EINVAL);
380
381 /* Create hook private structure */
382 MALLOC(hpriv, hookpriv_p,
383 sizeof(*hpriv), M_NETGRAPH_L2TP, M_NOWAIT | M_ZERO);
384 if (hpriv == NULL)
385 return (ENOMEM);
386 hpriv->conf.session_id = htons(session_id);
387 hpriv->conf.control_dseq = L2TP_CONTROL_DSEQ;
388 hpriv->conf.enable_dseq = L2TP_ENABLE_DSEQ;
389 NG_HOOK_SET_PRIVATE(hook, hpriv);
390 }
391
392 /* Done */
393 return (0);
394 }
395
396 /*
397 * Receive a control message.
398 */
399 static int
400 ng_l2tp_rcvmsg(node_p node, struct ng_mesg *msg,
401 const char *raddr, struct ng_mesg **rptr)
402 {
403 const priv_p priv = NG_NODE_PRIVATE(node);
404 struct ng_mesg *resp = NULL;
405 int error = 0;
406
407 switch (msg->header.typecookie) {
408 case NGM_L2TP_COOKIE:
409 switch (msg->header.cmd) {
410 case NGM_L2TP_SET_CONFIG:
411 {
412 struct ng_l2tp_config *const conf =
413 (struct ng_l2tp_config *)msg->data;
414
415 /* Check for invalid or illegal config */
416 if (msg->header.arglen != sizeof(*conf)) {
417 error = EINVAL;
418 break;
419 }
420 conf->enabled = !!conf->enabled;
421 conf->match_id = !!conf->match_id;
422 conf->tunnel_id = htons(conf->tunnel_id);
423 conf->peer_id = htons(conf->peer_id);
424 if (priv->conf.enabled
425 && ((priv->conf.tunnel_id != 0
426 && conf->tunnel_id != priv->conf.tunnel_id)
427 || ((priv->conf.peer_id != 0
428 && conf->peer_id != priv->conf.peer_id)))) {
429 error = EBUSY;
430 break;
431 }
432
433 /* Save calling node as failure target */
434 if (priv->ftarget != NULL)
435 FREE(priv->ftarget, M_NETGRAPH_L2TP);
436 MALLOC(priv->ftarget, char *,
437 strlen(raddr) + 1, M_NETGRAPH_L2TP, M_NOWAIT);
438 if (priv->ftarget == NULL) {
439 error = ENOMEM;
440 break;
441 }
442 strcpy(priv->ftarget, raddr);
443
444 /* Adjust sequence number state */
445 if ((error = ng_l2tp_seq_adjust(priv, conf)) != 0)
446 break;
447
448 /* Update node's config */
449 priv->conf = *conf;
450 break;
451 }
452 case NGM_L2TP_GET_CONFIG:
453 {
454 struct ng_l2tp_config *conf;
455
456 NG_MKRESPONSE(resp, msg, sizeof(*conf), M_NOWAIT);
457 if (resp == NULL) {
458 error = ENOMEM;
459 break;
460 }
461 conf = (struct ng_l2tp_config *)resp->data;
462 *conf = priv->conf;
463
464 /* Put ID's in host order */
465 conf->tunnel_id = ntohs(conf->tunnel_id);
466 conf->peer_id = ntohs(conf->peer_id);
467 break;
468 }
469 case NGM_L2TP_SET_SESS_CONFIG:
470 {
471 struct ng_l2tp_sess_config *const conf =
472 (struct ng_l2tp_sess_config *)msg->data;
473 hookpriv_p hpriv = NULL;
474 hook_p hook;
475
476 /* Check for invalid or illegal config */
477 if (msg->header.arglen != sizeof(*conf)) {
478 error = EINVAL;
479 break;
480 }
481
482 /* Put ID's in network order */
483 conf->session_id = htons(conf->session_id);
484 conf->peer_id = htons(conf->peer_id);
485
486 /* Find matching hook */
487 LIST_FOREACH(hook, &node->hooks, hooks) {
488 if ((hpriv = NG_HOOK_PRIVATE(hook)) == NULL)
489 continue;
490 if (hpriv->conf.session_id == conf->session_id)
491 break;
492 }
493 if (hook == NULL) {
494 error = ENOENT;
495 break;
496 }
497
498 /* Update hook's config */
499 hpriv->conf = *conf;
500 break;
501 }
502 case NGM_L2TP_GET_SESS_CONFIG:
503 {
504 struct ng_l2tp_sess_config *conf;
505 hookpriv_p hpriv = NULL;
506 u_int16_t session_id;
507 hook_p hook;
508
509 /* Get session ID */
510 if (msg->header.arglen != sizeof(session_id)) {
511 error = EINVAL;
512 break;
513 }
514 memcpy(&session_id, msg->data, 2);
515 session_id = htons(session_id);
516
517 /* Find matching hook */
518 LIST_FOREACH(hook, &node->hooks, hooks) {
519 if ((hpriv = NG_HOOK_PRIVATE(hook)) == NULL)
520 continue;
521 if (hpriv->conf.session_id == session_id)
522 break;
523 }
524 if (hook == NULL) {
525 error = ENOENT;
526 break;
527 }
528
529 /* Send response */
530 NG_MKRESPONSE(resp, msg, sizeof(hpriv->conf), M_NOWAIT);
531 if (resp == NULL) {
532 error = ENOMEM;
533 break;
534 }
535 conf = (struct ng_l2tp_sess_config *)resp->data;
536 *conf = hpriv->conf;
537
538 /* Put ID's in host order */
539 conf->session_id = ntohs(conf->session_id);
540 conf->peer_id = ntohs(conf->peer_id);
541 break;
542 }
543 case NGM_L2TP_GET_STATS:
544 case NGM_L2TP_CLR_STATS:
545 case NGM_L2TP_GETCLR_STATS:
546 {
547 if (msg->header.cmd != NGM_L2TP_CLR_STATS) {
548 NG_MKRESPONSE(resp, msg,
549 sizeof(priv->stats), M_NOWAIT);
550 if (resp == NULL) {
551 error = ENOMEM;
552 break;
553 }
554 memcpy(resp->data,
555 &priv->stats, sizeof(priv->stats));
556 }
557 if (msg->header.cmd != NGM_L2TP_GET_STATS)
558 memset(&priv->stats, 0, sizeof(priv->stats));
559 break;
560 }
561 default:
562 error = EINVAL;
563 break;
564 }
565 break;
566 default:
567 error = EINVAL;
568 break;
569 }
570 if (rptr)
571 *rptr = resp;
572 else if (resp)
573 FREE(resp, M_NETGRAPH);
574 FREE(msg, M_NETGRAPH);
575 return (error);
576 }
577
578 /*
579 * Receive incoming data on a hook.
580 */
581 static int
582 ng_l2tp_rcvdata(hook_p hook, struct mbuf *m, meta_p meta)
583 {
584 const node_p node = NG_HOOK_NODE(hook);
585 const priv_p priv = NG_NODE_PRIVATE(node);
586 int error;
587
588 /* Sanity check */
589 L2TP_SEQ_CHECK(&priv->seq);
590
591 /* If not configured, reject */
592 if (!priv->conf.enabled) {
593 NG_FREE_DATA(m, meta);
594 return (ENXIO);
595 }
596
597 /* Handle incoming frame from below */
598 if (hook == priv->lower) {
599 error = ng_l2tp_recv_lower(node, m, meta);
600 goto done;
601 }
602
603 /* Handle outgoing control frame */
604 if (hook == priv->ctrl) {
605 error = ng_l2tp_recv_ctrl(node, m, meta);
606 goto done;
607 }
608
609 /* Handle outgoing data frame */
610 error = ng_l2tp_recv_data(node, m, meta, NG_HOOK_PRIVATE(hook));
611
612 done:
613 /* Done */
614 L2TP_SEQ_CHECK(&priv->seq);
615 return (error);
616 }
617
618 /*
619 * Destroy node
620 */
621 static int
622 ng_l2tp_shutdown(node_p node)
623 {
624 const priv_p priv = NG_NODE_PRIVATE(node);
625 struct l2tp_seq *const seq = &priv->seq;
626
627 /* Sanity check */
628 L2TP_SEQ_CHECK(seq);
629
630 /* Reset sequence number state */
631 node->flags |= NG_INVALID;
632 ng_l2tp_seq_reset(priv);
633 ng_cutlinks(node);
634 ng_unname(node);
635
636 /* Free private data if neither timer is running */
637 if (!seq->rack_timer_running && !seq->xack_timer_running) {
638 if (priv->ftarget != NULL)
639 FREE(priv->ftarget, M_NETGRAPH_L2TP);
640 FREE(priv, M_NETGRAPH_L2TP);
641 NG_NODE_SET_PRIVATE(node, NULL);
642 }
643
644 /* Unref node */
645 NG_NODE_UNREF(node);
646 return (0);
647 }
648
649 /*
650 * Hook disconnection
651 */
652 static int
653 ng_l2tp_disconnect(hook_p hook)
654 {
655 const node_p node = NG_HOOK_NODE(hook);
656 const priv_p priv = NG_NODE_PRIVATE(node);
657
658 /* Zero out hook pointer */
659 if (hook == priv->ctrl)
660 priv->ctrl = NULL;
661 else if (hook == priv->lower)
662 priv->lower = NULL;
663 else {
664 FREE(NG_HOOK_PRIVATE(hook), M_NETGRAPH_L2TP);
665 NG_HOOK_SET_PRIVATE(hook, NULL);
666 }
667
668 /* Go away if no longer connected to anything */
669 if (node->numhooks == 0)
670 ng_rmnode(node);
671 return (0);
672 }
673
674 /*************************************************************************
675 INTERNAL FUNCTIONS
676 *************************************************************************/
677
678 /*
679 * Handle an incoming frame from below.
680 */
681 static int
682 ng_l2tp_recv_lower(node_p node, struct mbuf *m, meta_p meta)
683 {
684 static const u_int16_t req_bits[2][2] = {
685 { L2TP_DATA_0BITS, L2TP_DATA_1BITS },
686 { L2TP_CTRL_0BITS, L2TP_CTRL_1BITS },
687 };
688 const priv_p priv = NG_NODE_PRIVATE(node);
689 hookpriv_p hpriv = NULL;
690 hook_p hook = NULL;
691 u_int16_t ids[2];
692 u_int16_t hdr;
693 u_int16_t ns;
694 u_int16_t nr;
695 int is_ctrl;
696 int error;
697 int len;
698
699 /* Update stats */
700 priv->stats.recvPackets++;
701 priv->stats.recvOctets += m->m_pkthdr.len;
702
703 /* Get initial header */
704 if (m->m_pkthdr.len < 6) {
705 priv->stats.recvRunts++;
706 NG_FREE_DATA(m, meta);
707 return (EINVAL);
708 }
709 if (m->m_len < 2 && (m = m_pullup(m, 2)) == NULL) {
710 priv->stats.memoryFailures++;
711 NG_FREE_META(meta);
712 return (EINVAL);
713 }
714 hdr = ntohs(*mtod(m, u_int16_t *));
715 m_adj(m, 2);
716
717 /* Check required header bits and minimum length */
718 is_ctrl = (hdr & L2TP_HDR_CTRL) != 0;
719 if ((hdr & req_bits[is_ctrl][0]) != 0
720 || (~hdr & req_bits[is_ctrl][1]) != 0) {
721 priv->stats.recvInvalid++;
722 NG_FREE_DATA(m, meta);
723 return (EINVAL);
724 }
725 if (m->m_pkthdr.len < 4 /* tunnel, session id */
726 + (2 * ((hdr & L2TP_HDR_LEN) != 0)) /* length field */
727 + (4 * ((hdr & L2TP_HDR_SEQ) != 0)) /* seq # fields */
728 + (2 * ((hdr & L2TP_HDR_OFF) != 0))) { /* offset field */
729 priv->stats.recvRunts++;
730 NG_FREE_DATA(m, meta);
731 return (EINVAL);
732 }
733
734 /* Get and validate length field if present */
735 if ((hdr & L2TP_HDR_LEN) != 0) {
736 if (m->m_len < 2 && (m = m_pullup(m, 2)) == NULL) {
737 priv->stats.memoryFailures++;
738 NG_FREE_META(meta);
739 return (EINVAL);
740 }
741 len = (u_int16_t)ntohs(*mtod(m, u_int16_t *)) - 4;
742 m_adj(m, 2);
743 if (len < 0 || len > m->m_pkthdr.len) {
744 priv->stats.recvInvalid++;
745 NG_FREE_DATA(m, meta);
746 return (EINVAL);
747 }
748 if (len < m->m_pkthdr.len) /* trim extra bytes */
749 m_adj(m, -(m->m_pkthdr.len - len));
750 }
751
752 /* Get tunnel ID and session ID */
753 if (m->m_len < 4 && (m = m_pullup(m, 4)) == NULL) {
754 priv->stats.memoryFailures++;
755 NG_FREE_META(meta);
756 return (EINVAL);
757 }
758 memcpy(ids, mtod(m, u_int16_t *), 4);
759 m_adj(m, 4);
760
761 /* Check tunnel ID */
762 if (ids[0] != priv->conf.tunnel_id
763 && (priv->conf.match_id || ids[0] != 0)) {
764 priv->stats.recvWrongTunnel++;
765 NG_FREE_DATA(m, meta);
766 return (EADDRNOTAVAIL);
767 }
768
769 /* Check session ID (for data packets only) */
770 if ((hdr & L2TP_HDR_CTRL) == 0) {
771 LIST_FOREACH(hook, &node->hooks, hooks) {
772 if ((hpriv = NG_HOOK_PRIVATE(hook)) == NULL)
773 continue;
774 if (hpriv->conf.session_id == ids[1])
775 break;
776 }
777 if (hook == NULL) {
778 priv->stats.recvUnknownSID++;
779 NG_FREE_DATA(m, meta);
780 return (ENOTCONN);
781 }
782 hpriv = NG_HOOK_PRIVATE(hook);
783 }
784
785 /* Get Ns, Nr fields if present */
786 if ((hdr & L2TP_HDR_SEQ) != 0) {
787 if (m->m_len < 4 && (m = m_pullup(m, 4)) == NULL) {
788 priv->stats.memoryFailures++;
789 NG_FREE_META(meta);
790 return (EINVAL);
791 }
792 memcpy(&ns, &mtod(m, u_int16_t *)[0], 2);
793 ns = ntohs(ns);
794 memcpy(&nr, &mtod(m, u_int16_t *)[1], 2);
795 nr = ntohs(nr);
796 m_adj(m, 4);
797 }
798
799 /* Strip offset padding if present */
800 if ((hdr & L2TP_HDR_OFF) != 0) {
801 u_int16_t offset;
802
803 /* Get length of offset padding */
804 if (m->m_len < 2 && (m = m_pullup(m, 2)) == NULL) {
805 priv->stats.memoryFailures++;
806 NG_FREE_META(meta);
807 return (EINVAL);
808 }
809 memcpy(&offset, mtod(m, u_int16_t *), 2);
810 offset = ntohs(offset);
811
812 /* Trim offset padding */
813 if ((2+offset) > m->m_pkthdr.len) {
814 priv->stats.recvInvalid++;
815 NG_FREE_DATA(m, meta);
816 return (EINVAL);
817 }
818 m_adj(m, 2+offset);
819 }
820
821 /* Handle control packets */
822 if ((hdr & L2TP_HDR_CTRL) != 0) {
823
824 /* Handle receive ack sequence number Nr */
825 ng_l2tp_seq_recv_nr(priv, nr);
826
827 /* Discard ZLB packets */
828 if (m->m_pkthdr.len == 0) {
829 priv->stats.recvZLBs++;
830 NG_FREE_DATA(m, meta);
831 return (0);
832 }
833
834 /*
835 * Prepend session ID to packet here: we don't want to accept
836 * the send sequence number Ns if we have to drop the packet
837 * later because of a memory error, because then the upper
838 * layer would never get the packet.
839 */
840 M_PREPEND(m, 2, M_DONTWAIT);
841 if (m == NULL) {
842 priv->stats.memoryFailures++;
843 NG_FREE_META(meta);
844 return (ENOBUFS);
845 }
846 memcpy(mtod(m, u_int16_t *), &ids[1], 2);
847
848 /* Now handle send sequence number */
849 if (ng_l2tp_seq_recv_ns(priv, ns) == -1) {
850 NG_FREE_DATA(m, meta);
851 return (0);
852 }
853
854 /* Deliver packet to upper layers */
855 NG_SEND_DATA(error, priv->ctrl, m, meta);
856 return (error);
857 }
858
859 /* Follow peer's lead in data sequencing, if configured to do so */
860 if (!hpriv->conf.control_dseq)
861 hpriv->conf.enable_dseq = ((hdr & L2TP_HDR_SEQ) != 0);
862
863 /* Handle data sequence numbers if present and enabled */
864 if ((hdr & L2TP_HDR_SEQ) != 0) {
865 if (hpriv->conf.enable_dseq
866 && L2TP_SEQ_DIFF(ns, hpriv->nr) < 0) {
867 NG_FREE_DATA(m, meta); /* duplicate or out of order */
868 priv->stats.recvDataDrops++;
869 return (0);
870 }
871 hpriv->nr = ns + 1;
872 }
873
874 /* Drop empty data packets */
875 if (m->m_pkthdr.len == 0) {
876 NG_FREE_DATA(m, meta);
877 return (0);
878 }
879
880 /* Deliver data */
881 NG_SEND_DATA(error, hook, m, meta);
882 return (error);
883 }
884
885 /*
886 * Handle an outgoing control frame.
887 */
888 static int
889 ng_l2tp_recv_ctrl(node_p node, struct mbuf *m, meta_p meta)
890 {
891 const priv_p priv = NG_NODE_PRIVATE(node);
892 struct l2tp_seq *const seq = &priv->seq;
893 int i;
894
895 /* Discard meta XXX should queue meta's along with packet */
896 NG_FREE_META(meta);
897
898 /* Packet should have session ID prepended */
899 if (m->m_pkthdr.len < 2) {
900 priv->stats.xmitInvalid++;
901 m_freem(m);
902 return (EINVAL);
903 }
904
905 /* Check max length */
906 if (m->m_pkthdr.len >= 0x10000 - 14) {
907 priv->stats.xmitTooBig++;
908 m_freem(m);
909 return (EOVERFLOW);
910 }
911
912 /* Find next empty slot in transmit queue */
913 for (i = 0; i < L2TP_MAX_XWIN && seq->xwin[i] != NULL; i++);
914 if (i == L2TP_MAX_XWIN) {
915 priv->stats.xmitDrops++;
916 m_freem(m);
917 return (ENOBUFS);
918 }
919 seq->xwin[i] = m;
920
921 /* Sanity check receive ack timer state */
922 KASSERT((i == 0) ^ seq->rack_timer_running,
923 ("%s: xwin %d full but rack timer %srunning",
924 __FUNCTION__, i, seq->rack_timer_running ? "" : "not "));
925
926 /* If peer's receive window is already full, nothing else to do */
927 if (i >= seq->cwnd)
928 return (0);
929
930 /* Start retransmit timer if not already running */
931 if (!seq->rack_timer_running) {
932 callout_reset(&seq->rack_timer,
933 hz, ng_l2tp_seq_rack_timeout, node);
934 seq->rack_timer_running = 1;
935 NG_NODE_REF(node);
936 }
937
938 /* Copy packet */
939 if ((m = L2TP_COPY_MBUF(seq->xwin[i], M_NOWAIT)) == NULL) {
940 priv->stats.memoryFailures++;
941 return (ENOBUFS);
942 }
943
944 /* Send packet and increment xmit sequence number */
945 return (ng_l2tp_xmit_ctrl(priv, m, seq->ns++));
946 }
947
948 /*
949 * Handle an outgoing data frame.
950 */
951 static int
952 ng_l2tp_recv_data(node_p node, struct mbuf *m, meta_p meta, hookpriv_p hpriv)
953 {
954 const priv_p priv = NG_NODE_PRIVATE(node);
955 u_int16_t hdr;
956 int error;
957 int i = 1;
958
959 /* Check max length */
960 if (m->m_pkthdr.len >= 0x10000 - 12) {
961 priv->stats.xmitDataTooBig++;
962 NG_FREE_META(meta);
963 m_freem(m);
964 return (EOVERFLOW);
965 }
966
967 /* Prepend L2TP header */
968 M_PREPEND(m, 6
969 + (2 * (hpriv->conf.include_length != 0))
970 + (4 * (hpriv->conf.enable_dseq != 0)),
971 M_DONTWAIT);
972 if (m == NULL) {
973 priv->stats.memoryFailures++;
974 NG_FREE_META(meta);
975 return (ENOBUFS);
976 }
977 hdr = L2TP_DATA_HDR;
978 if (hpriv->conf.include_length) {
979 hdr |= L2TP_HDR_LEN;
980 mtod(m, u_int16_t *)[i++] = htons(m->m_pkthdr.len);
981 }
982 mtod(m, u_int16_t *)[i++] = priv->conf.peer_id;
983 mtod(m, u_int16_t *)[i++] = hpriv->conf.peer_id;
984 if (hpriv->conf.enable_dseq) {
985 hdr |= L2TP_HDR_SEQ;
986 mtod(m, u_int16_t *)[i++] = htons(hpriv->ns);
987 mtod(m, u_int16_t *)[i++] = htons(hpriv->nr);
988 hpriv->ns++;
989 }
990 mtod(m, u_int16_t *)[0] = htons(hdr);
991
992 /* Send packet */
993 NG_SEND_DATA(error, priv->lower, m, meta);
994 return (error);
995 }
996
997 /*
998 * Send a message to our controlling node that we've failed.
999 */
1000 static void
1001 ng_l2tp_seq_failure(priv_p priv)
1002 {
1003 struct ng_mesg *msg;
1004
1005 NG_MKMESSAGE(msg, NGM_L2TP_COOKIE, NGM_L2TP_ACK_FAILURE, 0, M_NOWAIT);
1006 if (msg == NULL)
1007 return;
1008 (void)ng_send_msg(priv->node, msg, priv->ftarget, NULL);
1009 }
1010
1011 /************************************************************************
1012 SEQUENCE NUMBER HANDLING
1013 ************************************************************************/
1014
1015 /*
1016 * Initialize sequence number state.
1017 */
1018 static void
1019 ng_l2tp_seq_init(priv_p priv)
1020 {
1021 struct l2tp_seq *const seq = &priv->seq;
1022
1023 KASSERT(priv->conf.peer_win >= 1,
1024 ("%s: peer_win is zero", __FUNCTION__));
1025 memset(seq, 0, sizeof(*seq));
1026 seq->cwnd = 1;
1027 seq->wmax = priv->conf.peer_win;
1028 if (seq->wmax > L2TP_MAX_XWIN)
1029 seq->wmax = L2TP_MAX_XWIN;
1030 seq->ssth = seq->wmax;
1031 seq->max_rexmits = priv->conf.rexmit_max;
1032 seq->max_rexmit_to = priv->conf.rexmit_max_to;
1033 callout_init(&seq->rack_timer);
1034 callout_init(&seq->xack_timer);
1035 L2TP_SEQ_CHECK(seq);
1036 }
1037
1038 /*
1039 * Adjust sequence number state accordingly after reconfiguration.
1040 */
1041 static int
1042 ng_l2tp_seq_adjust(priv_p priv, const struct ng_l2tp_config *conf)
1043 {
1044 struct l2tp_seq *const seq = &priv->seq;
1045 u_int16_t new_wmax;
1046
1047 /* If disabling node, reset state sequence number */
1048 if (!conf->enabled) {
1049 ng_l2tp_seq_reset(priv);
1050 return (0);
1051 }
1052
1053 /* Adjust peer's max recv window; it can only increase */
1054 new_wmax = conf->peer_win;
1055 if (new_wmax > L2TP_MAX_XWIN)
1056 new_wmax = L2TP_MAX_XWIN;
1057 if (new_wmax == 0)
1058 return (EINVAL);
1059 if (new_wmax < seq->wmax)
1060 return (EBUSY);
1061 seq->wmax = new_wmax;
1062
1063 /* Update retransmit parameters */
1064 seq->max_rexmits = conf->rexmit_max;
1065 seq->max_rexmit_to = conf->rexmit_max_to;
1066
1067 /* Done */
1068 return (0);
1069 }
1070
1071 /*
1072 * Reset sequence number state.
1073 */
1074 static void
1075 ng_l2tp_seq_reset(priv_p priv)
1076 {
1077 struct l2tp_seq *const seq = &priv->seq;
1078 hookpriv_p hpriv = NULL;
1079 hook_p hook;
1080 int i;
1081
1082 /* Sanity check */
1083 L2TP_SEQ_CHECK(seq);
1084
1085 /* Stop timers */
1086 if (seq->rack_timer_running && callout_stop(&seq->rack_timer) == 1) {
1087 seq->rack_timer_running = 0;
1088 NG_NODE_UNREF(priv->node);
1089 }
1090 if (seq->xack_timer_running && callout_stop(&seq->xack_timer) == 1) {
1091 seq->xack_timer_running = 0;
1092 NG_NODE_UNREF(priv->node);
1093 }
1094
1095 /* Free retransmit queue */
1096 for (i = 0; i < L2TP_MAX_XWIN; i++) {
1097 if (seq->xwin[i] == NULL)
1098 break;
1099 m_freem(seq->xwin[i]);
1100 }
1101
1102 /* Reset session hooks' sequence number states */
1103 LIST_FOREACH(hook, &priv->node->hooks, hooks) {
1104 if ((hpriv = NG_HOOK_PRIVATE(hook)) == NULL)
1105 continue;
1106 hpriv->conf.control_dseq = 0;
1107 hpriv->conf.enable_dseq = 0;
1108 hpriv->nr = 0;
1109 hpriv->ns = 0;
1110 }
1111
1112 /* Reset node's sequence number state */
1113 memset(seq, 0, sizeof(*seq));
1114 seq->cwnd = 1;
1115 seq->wmax = L2TP_MAX_XWIN;
1116 seq->ssth = seq->wmax;
1117
1118 /* Done */
1119 L2TP_SEQ_CHECK(seq);
1120 }
1121
1122 /*
1123 * Handle receipt of an acknowledgement value (Nr) from peer.
1124 */
1125 static void
1126 ng_l2tp_seq_recv_nr(priv_p priv, u_int16_t nr)
1127 {
1128 struct l2tp_seq *const seq = &priv->seq;
1129 struct mbuf *m;
1130 int nack;
1131 int i;
1132
1133 /* Verify peer's ACK is in range */
1134 if ((nack = L2TP_SEQ_DIFF(nr, seq->rack)) <= 0)
1135 return; /* duplicate ack */
1136 if (L2TP_SEQ_DIFF(nr, seq->ns) > 0) {
1137 priv->stats.recvBadAcks++; /* ack for packet not sent */
1138 return;
1139 }
1140 KASSERT(nack <= L2TP_MAX_XWIN,
1141 ("%s: nack=%d > %d", __FUNCTION__, nack, L2TP_MAX_XWIN));
1142
1143 /* Update receive ack stats */
1144 seq->rack = nr;
1145 seq->rexmits = 0;
1146
1147 /* Free acknowledged packets and shift up packets in the xmit queue */
1148 for (i = 0; i < nack; i++)
1149 m_freem(seq->xwin[i]);
1150 memmove(seq->xwin, seq->xwin + nack,
1151 (L2TP_MAX_XWIN - nack) * sizeof(*seq->xwin));
1152 memset(seq->xwin + (L2TP_MAX_XWIN - nack), 0,
1153 nack * sizeof(*seq->xwin));
1154
1155 /*
1156 * Do slow-start/congestion avoidance windowing algorithm described
1157 * in RFC 2661, Appendix A. Here we handle a multiple ACK as if each
1158 * ACK had arrived separately.
1159 */
1160 if (seq->cwnd < seq->wmax) {
1161
1162 /* Handle slow start phase */
1163 if (seq->cwnd < seq->ssth) {
1164 seq->cwnd += nack;
1165 nack = 0;
1166 if (seq->cwnd > seq->ssth) { /* into cg.av. phase */
1167 nack = seq->cwnd - seq->ssth;
1168 seq->cwnd = seq->ssth;
1169 }
1170 }
1171
1172 /* Handle congestion avoidance phase */
1173 if (seq->cwnd >= seq->ssth) {
1174 seq->acks += nack;
1175 while (seq->acks >= seq->cwnd) {
1176 seq->acks -= seq->cwnd;
1177 if (seq->cwnd < seq->wmax)
1178 seq->cwnd++;
1179 }
1180 }
1181 }
1182
1183 /* Stop xmit timer */
1184 if (seq->rack_timer_running && callout_stop(&seq->rack_timer) == 1) {
1185 seq->rack_timer_running = 0;
1186 NG_NODE_UNREF(priv->node);
1187 }
1188
1189 /* If transmit queue is empty, we're done for now */
1190 if (seq->xwin[0] == NULL)
1191 return;
1192
1193 /* Start restransmit timer again */
1194 callout_reset(&seq->rack_timer,
1195 hz, ng_l2tp_seq_rack_timeout, priv->node);
1196 seq->rack_timer_running = 1;
1197 NG_NODE_REF(priv->node);
1198
1199 /*
1200 * Send more packets, trying to keep peer's receive window full.
1201 * If there is a memory error, pretend packet was sent, as it
1202 * will get retransmitted later anyway.
1203 */
1204 while ((i = L2TP_SEQ_DIFF(seq->ns, seq->rack)) < seq->cwnd
1205 && seq->xwin[i] != NULL) {
1206 if ((m = L2TP_COPY_MBUF(seq->xwin[i], M_NOWAIT)) == NULL)
1207 priv->stats.memoryFailures++;
1208 else
1209 ng_l2tp_xmit_ctrl(priv, m, seq->ns);
1210 seq->ns++;
1211 }
1212 }
1213
1214 /*
1215 * Handle receipt of a sequence number value (Ns) from peer.
1216 * We make no attempt to re-order out of order packets.
1217 *
1218 * This function should only be called for non-ZLB packets.
1219 *
1220 * Returns:
1221 * 0 Accept packet
1222 * -1 Drop packet
1223 */
1224 static int
1225 ng_l2tp_seq_recv_ns(priv_p priv, u_int16_t ns)
1226 {
1227 struct l2tp_seq *const seq = &priv->seq;
1228
1229 /* If not what we expect, drop packet and send an immediate ZLB ack */
1230 if (ns != seq->nr) {
1231 if (L2TP_SEQ_DIFF(ns, seq->nr) < 0)
1232 priv->stats.recvDuplicates++;
1233 else
1234 priv->stats.recvOutOfOrder++;
1235 ng_l2tp_xmit_ctrl(priv, NULL, seq->ns);
1236 return (-1);
1237 }
1238
1239 /* Update recv sequence number */
1240 seq->nr++;
1241
1242 /* Start receive ack timer, if not already running */
1243 if (!seq->xack_timer_running) {
1244 callout_reset(&seq->xack_timer,
1245 L2TP_DELAYED_ACK, ng_l2tp_seq_xack_timeout, priv->node);
1246 seq->xack_timer_running = 1;
1247 NG_NODE_REF(priv->node);
1248 }
1249
1250 /* Accept packet */
1251 return (0);
1252 }
1253
1254 /*
1255 * Handle an ack timeout. We have an outstanding ack that we
1256 * were hoping to piggy-back, but haven't, so send a ZLB.
1257 */
1258 static void
1259 ng_l2tp_seq_xack_timeout(void *arg)
1260 {
1261 const node_p node = arg;
1262 const priv_p priv = NG_NODE_PRIVATE(node);
1263 struct l2tp_seq *const seq = &priv->seq;
1264 int s;
1265
1266 /* Check if node is going away */
1267 s = splnet();
1268 if (NG_NODE_NOT_VALID(node)) {
1269 seq->xack_timer_running = 0;
1270 if (!seq->rack_timer_running) {
1271 if (priv->ftarget != NULL)
1272 FREE(priv->ftarget, M_NETGRAPH_L2TP);
1273 FREE(priv, M_NETGRAPH_L2TP);
1274 NG_NODE_SET_PRIVATE(node, NULL);
1275 }
1276 NG_NODE_UNREF(node);
1277 splx(s);
1278 return;
1279 }
1280
1281 /* Sanity check */
1282 L2TP_SEQ_CHECK(seq);
1283
1284 /* If ack is still outstanding, send a ZLB */
1285 if (seq->xack != seq->nr)
1286 ng_l2tp_xmit_ctrl(priv, NULL, seq->ns);
1287
1288 /* Done */
1289 seq->xack_timer_running = 0;
1290 NG_NODE_UNREF(node);
1291 L2TP_SEQ_CHECK(seq);
1292 splx(s);
1293 }
1294
1295 /*
1296 * Handle a transmit timeout. The peer has failed to respond
1297 * with an ack for our packet, so retransmit it.
1298 */
1299 static void
1300 ng_l2tp_seq_rack_timeout(void *arg)
1301 {
1302 const node_p node = arg;
1303 const priv_p priv = NG_NODE_PRIVATE(node);
1304 struct l2tp_seq *const seq = &priv->seq;
1305 struct mbuf *m;
1306 u_int delay;
1307 int s;
1308
1309 /* Check if node is going away */
1310 s = splnet();
1311 if (NG_NODE_NOT_VALID(node)) {
1312 seq->rack_timer_running = 0;
1313 if (!seq->xack_timer_running) {
1314 if (priv->ftarget != NULL)
1315 FREE(priv->ftarget, M_NETGRAPH_L2TP);
1316 FREE(priv, M_NETGRAPH_L2TP);
1317 NG_NODE_SET_PRIVATE(node, NULL);
1318 }
1319 NG_NODE_UNREF(node);
1320 splx(s);
1321 return;
1322 }
1323
1324 /* Sanity check */
1325 L2TP_SEQ_CHECK(seq);
1326
1327 /* Make sure peer's ack is still outstanding before doing anything */
1328 if (seq->rack == seq->ns) {
1329 seq->rack_timer_running = 0;
1330 NG_NODE_UNREF(node);
1331 goto done;
1332 }
1333 priv->stats.xmitRetransmits++;
1334
1335 /* Have we reached the retransmit limit? If so, notify owner. */
1336 if (seq->rexmits++ >= seq->max_rexmits)
1337 ng_l2tp_seq_failure(priv);
1338
1339 /* Restart timer, this time with an increased delay */
1340 delay = (seq->rexmits > 12) ? (1 << 12) : (1 << seq->rexmits);
1341 if (delay > seq->max_rexmit_to)
1342 delay = seq->max_rexmit_to;
1343 callout_reset(&seq->rack_timer,
1344 hz * delay, ng_l2tp_seq_rack_timeout, node);
1345
1346 /* Do slow-start/congestion algorithm windowing algorithm */
1347 seq->ssth = (seq->cwnd + 1) / 2;
1348 seq->cwnd = 1;
1349 seq->acks = 0;
1350
1351 /* Retransmit oldest unack'd packet */
1352 if ((m = L2TP_COPY_MBUF(seq->xwin[0], M_NOWAIT)) == NULL)
1353 priv->stats.memoryFailures++;
1354 else
1355 ng_l2tp_xmit_ctrl(priv, m, seq->rack);
1356
1357 done:
1358 /* Done */
1359 L2TP_SEQ_CHECK(seq);
1360 splx(s);
1361 }
1362
1363 /*
1364 * Transmit a control stream packet, payload optional.
1365 * The transmit sequence number is not incremented.
1366 */
1367 static int
1368 ng_l2tp_xmit_ctrl(priv_p priv, struct mbuf *m, u_int16_t ns)
1369 {
1370 struct l2tp_seq *const seq = &priv->seq;
1371 u_int16_t session_id = 0;
1372 meta_p meta = NULL;
1373 int error;
1374
1375 /* If no mbuf passed, send an empty packet (ZLB) */
1376 if (m == NULL) {
1377
1378 /* Create a new mbuf for ZLB packet */
1379 MGETHDR(m, M_DONTWAIT, MT_DATA);
1380 if (m == NULL) {
1381 priv->stats.memoryFailures++;
1382 return (ENOBUFS);
1383 }
1384 m->m_len = m->m_pkthdr.len = 12;
1385 m->m_pkthdr.rcvif = NULL;
1386 priv->stats.xmitZLBs++;
1387 } else {
1388
1389 /* Strip off session ID */
1390 if (m->m_len < 2 && (m = m_pullup(m, 2)) == NULL) {
1391 priv->stats.memoryFailures++;
1392 return (ENOBUFS);
1393 }
1394 memcpy(&session_id, mtod(m, u_int16_t *), 2);
1395 m_adj(m, 2);
1396
1397 /* Make room for L2TP header */
1398 M_PREPEND(m, 12, M_DONTWAIT);
1399 if (m == NULL) {
1400 priv->stats.memoryFailures++;
1401 return (ENOBUFS);
1402 }
1403 }
1404
1405 /* Fill in L2TP header */
1406 mtod(m, u_int16_t *)[0] = htons(L2TP_CTRL_HDR);
1407 mtod(m, u_int16_t *)[1] = htons(m->m_pkthdr.len);
1408 mtod(m, u_int16_t *)[2] = priv->conf.peer_id;
1409 mtod(m, u_int16_t *)[3] = session_id;
1410 mtod(m, u_int16_t *)[4] = htons(ns);
1411 mtod(m, u_int16_t *)[5] = htons(seq->nr);
1412
1413 /* Update sequence number info and stats */
1414 priv->stats.xmitPackets++;
1415 priv->stats.xmitOctets += m->m_pkthdr.len;
1416
1417 /* Stop ack timer: we're sending an ack with this packet */
1418 if (seq->xack_timer_running && callout_stop(&seq->xack_timer) == 1) {
1419 seq->xack_timer_running = 0;
1420 NG_NODE_UNREF(priv->node);
1421 }
1422 seq->xack = seq->nr;
1423
1424 /* Send packet */
1425 NG_SEND_DATA(error, priv->lower, m, meta);
1426 return (error);
1427 }
1428
1429 #ifdef INVARIANTS
1430 /*
1431 * Sanity check sequence number state.
1432 */
1433 static void
1434 ng_l2tp_seq_check(struct l2tp_seq *seq)
1435 {
1436 const int self_unack = L2TP_SEQ_DIFF(seq->nr, seq->xack);
1437 const int peer_unack = L2TP_SEQ_DIFF(seq->ns, seq->rack);
1438 int i;
1439
1440 #define CHECK(p) KASSERT((p), ("%s: not: %s", __FUNCTION__, #p))
1441
1442 CHECK(seq->wmax <= L2TP_MAX_XWIN);
1443 CHECK(seq->cwnd >= 1);
1444 CHECK(seq->cwnd <= seq->wmax);
1445 CHECK(seq->ssth >= 1);
1446 CHECK(seq->ssth <= seq->wmax);
1447 if (seq->cwnd < seq->ssth)
1448 CHECK(seq->acks == 0);
1449 else
1450 CHECK(seq->acks <= seq->cwnd);
1451 CHECK(self_unack >= 0);
1452 CHECK(peer_unack >= 0);
1453 CHECK(peer_unack <= seq->wmax);
1454 CHECK((self_unack == 0) ^ seq->xack_timer_running);
1455 CHECK((peer_unack == 0) ^ seq->rack_timer_running);
1456 CHECK(seq->rack_timer_running || !callout_pending(&seq->rack_timer));
1457 CHECK(seq->xack_timer_running || !callout_pending(&seq->xack_timer));
1458 for (i = 0; i < peer_unack; i++)
1459 CHECK(seq->xwin[i] != NULL);
1460 for ( ; i < seq->cwnd; i++) /* verify peer's recv window full */
1461 CHECK(seq->xwin[i] == NULL);
1462
1463 #undef CHECK
1464 }
1465 #endif /* INVARIANTS */
1466
1467
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