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: releng/5.3/sys/netgraph/ng_l2tp.c 136588 2004-10-16 08:43:07Z cvs2svn $
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 <netgraph/ng_message.h>
61 #include <netgraph/netgraph.h>
62 #include <netgraph/ng_parse.h>
63 #include <netgraph/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 16 /* 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 /*
105 * Sequence number state
106 *
107 * Invariants:
108 * - If cwnd < ssth, we're doing slow start, otherwise congestion avoidance
109 * - The number of unacknowledged xmit packets is (ns - rack) <= seq->wmax
110 * - The first (ns - rack) mbuf's in xwin[] array are copies of these
111 * unacknowledged packets; the remainder of xwin[] consists first of
112 * zero or more further untransmitted packets in the transmit queue
113 * - We try to keep the peer's receive window as full as possible.
114 * Therefore, (i < cwnd && xwin[i] != NULL) implies (ns - rack) > i.
115 * - rack_timer is running iff (ns - rack) > 0 (unack'd xmit'd pkts)
116 * - If xack != nr, there are unacknowledged recv packet(s) (delayed ack)
117 * - xack_timer is running iff xack != nr (unack'd rec'd pkts)
118 */
119 struct l2tp_seq {
120 u_int16_t ns; /* next xmit seq we send */
121 u_int16_t nr; /* next recv seq we expect */
122 u_int16_t rack; /* last 'nr' we rec'd */
123 u_int16_t xack; /* last 'nr' we sent */
124 u_int16_t wmax; /* peer's max recv window */
125 u_int16_t cwnd; /* current congestion window */
126 u_int16_t ssth; /* slow start threshold */
127 u_int16_t acks; /* # consecutive acks rec'd */
128 u_int16_t rexmits; /* # retransmits sent */
129 u_int16_t max_rexmits; /* max # retransmits sent */
130 u_int16_t max_rexmit_to; /* max retransmit timeout */
131 struct callout rack_timer; /* retransmit timer */
132 struct callout xack_timer; /* delayed ack timer */
133 u_char rack_timer_running; /* xmit timer running */
134 u_char xack_timer_running; /* ack timer running */
135 struct mbuf *xwin[L2TP_MAX_XWIN]; /* transmit window */
136 };
137
138 /* Node private data */
139 struct ng_l2tp_private {
140 node_p node; /* back pointer to node */
141 hook_p ctrl; /* hook to upper layers */
142 hook_p lower; /* hook to lower layers */
143 struct ng_l2tp_config conf; /* node configuration */
144 struct ng_l2tp_stats stats; /* node statistics */
145 struct l2tp_seq seq; /* ctrl sequence number state */
146 ng_ID_t ftarget; /* failure message target */
147 };
148 typedef struct ng_l2tp_private *priv_p;
149
150 /* Hook private data (data session hooks only) */
151 struct ng_l2tp_hook_private {
152 struct ng_l2tp_sess_config conf; /* hook/session config */
153 struct ng_l2tp_session_stats stats; /* per sessions statistics */
154 u_int16_t ns; /* data ns sequence number */
155 u_int16_t nr; /* data nr sequence number */
156 };
157 typedef struct ng_l2tp_hook_private *hookpriv_p;
158
159 /* Netgraph node methods */
160 static ng_constructor_t ng_l2tp_constructor;
161 static ng_rcvmsg_t ng_l2tp_rcvmsg;
162 static ng_shutdown_t ng_l2tp_shutdown;
163 static ng_newhook_t ng_l2tp_newhook;
164 static ng_rcvdata_t ng_l2tp_rcvdata;
165 static ng_disconnect_t ng_l2tp_disconnect;
166
167 /* Internal functions */
168 static int ng_l2tp_recv_lower(node_p node, item_p item);
169 static int ng_l2tp_recv_ctrl(node_p node, item_p item);
170 static int ng_l2tp_recv_data(node_p node, item_p item, hookpriv_p hpriv);
171
172 static int ng_l2tp_xmit_ctrl(priv_p priv, struct mbuf *m, u_int16_t ns);
173
174 static void ng_l2tp_seq_init(priv_p priv);
175 static int ng_l2tp_seq_set(priv_p priv,
176 const struct ng_l2tp_seq_config *conf);
177 static int ng_l2tp_seq_adjust(priv_p priv,
178 const struct ng_l2tp_config *conf);
179 static void ng_l2tp_seq_reset(priv_p priv);
180 static void ng_l2tp_seq_failure(priv_p priv);
181 static void ng_l2tp_seq_recv_nr(priv_p priv, u_int16_t nr);
182 static int ng_l2tp_seq_recv_ns(priv_p priv, u_int16_t ns);
183 static void ng_l2tp_seq_xack_timeout(void *arg);
184 static void ng_l2tp_seq_rack_timeout(void *arg);
185
186 static ng_fn_eachhook ng_l2tp_find_session;
187 static ng_fn_eachhook ng_l2tp_reset_session;
188
189 #ifdef INVARIANTS
190 static void ng_l2tp_seq_check(struct l2tp_seq *seq);
191 #endif
192
193 /* Parse type for struct ng_l2tp_seq_config. */
194 static const struct ng_parse_struct_field
195 ng_l2tp_seq_config_fields[] = NG_L2TP_SEQ_CONFIG_TYPE_INFO;
196 static const struct ng_parse_type ng_l2tp_seq_config_type = {
197 &ng_parse_struct_type,
198 &ng_l2tp_seq_config_fields
199 };
200
201 /* Parse type for struct ng_l2tp_config */
202 static const struct ng_parse_struct_field
203 ng_l2tp_config_type_fields[] = NG_L2TP_CONFIG_TYPE_INFO;
204 static const struct ng_parse_type ng_l2tp_config_type = {
205 &ng_parse_struct_type,
206 &ng_l2tp_config_type_fields,
207 };
208
209 /* Parse type for struct ng_l2tp_sess_config */
210 static const struct ng_parse_struct_field
211 ng_l2tp_sess_config_type_fields[] = NG_L2TP_SESS_CONFIG_TYPE_INFO;
212 static const struct ng_parse_type ng_l2tp_sess_config_type = {
213 &ng_parse_struct_type,
214 &ng_l2tp_sess_config_type_fields,
215 };
216
217 /* Parse type for struct ng_l2tp_stats */
218 static const struct ng_parse_struct_field
219 ng_l2tp_stats_type_fields[] = NG_L2TP_STATS_TYPE_INFO;
220 static const struct ng_parse_type ng_l2tp_stats_type = {
221 &ng_parse_struct_type,
222 &ng_l2tp_stats_type_fields
223 };
224
225 /* Parse type for struct ng_l2tp_session_stats. */
226 static const struct ng_parse_struct_field
227 ng_l2tp_session_stats_type_fields[] = NG_L2TP_SESSION_STATS_TYPE_INFO;
228 static const struct ng_parse_type ng_l2tp_session_stats_type = {
229 &ng_parse_struct_type,
230 &ng_l2tp_session_stats_type_fields
231 };
232
233 /* List of commands and how to convert arguments to/from ASCII */
234 static const struct ng_cmdlist ng_l2tp_cmdlist[] = {
235 {
236 NGM_L2TP_COOKIE,
237 NGM_L2TP_SET_CONFIG,
238 "setconfig",
239 &ng_l2tp_config_type,
240 NULL
241 },
242 {
243 NGM_L2TP_COOKIE,
244 NGM_L2TP_GET_CONFIG,
245 "getconfig",
246 NULL,
247 &ng_l2tp_config_type
248 },
249 {
250 NGM_L2TP_COOKIE,
251 NGM_L2TP_SET_SESS_CONFIG,
252 "setsessconfig",
253 &ng_l2tp_sess_config_type,
254 NULL
255 },
256 {
257 NGM_L2TP_COOKIE,
258 NGM_L2TP_GET_SESS_CONFIG,
259 "getsessconfig",
260 &ng_parse_hint16_type,
261 &ng_l2tp_sess_config_type
262 },
263 {
264 NGM_L2TP_COOKIE,
265 NGM_L2TP_GET_STATS,
266 "getstats",
267 NULL,
268 &ng_l2tp_stats_type
269 },
270 {
271 NGM_L2TP_COOKIE,
272 NGM_L2TP_CLR_STATS,
273 "clrstats",
274 NULL,
275 NULL
276 },
277 {
278 NGM_L2TP_COOKIE,
279 NGM_L2TP_GETCLR_STATS,
280 "getclrstats",
281 NULL,
282 &ng_l2tp_stats_type
283 },
284 {
285 NGM_L2TP_COOKIE,
286 NGM_L2TP_GET_SESSION_STATS,
287 "getsessstats",
288 &ng_parse_int16_type,
289 &ng_l2tp_session_stats_type
290 },
291 {
292 NGM_L2TP_COOKIE,
293 NGM_L2TP_CLR_SESSION_STATS,
294 "clrsessstats",
295 &ng_parse_int16_type,
296 NULL
297 },
298 {
299 NGM_L2TP_COOKIE,
300 NGM_L2TP_GETCLR_SESSION_STATS,
301 "getclrsessstats",
302 &ng_parse_int16_type,
303 &ng_l2tp_session_stats_type
304 },
305 {
306 NGM_L2TP_COOKIE,
307 NGM_L2TP_ACK_FAILURE,
308 "ackfailure",
309 NULL,
310 NULL
311 },
312 {
313 NGM_L2TP_COOKIE,
314 NGM_L2TP_SET_SEQ,
315 "setsequence",
316 &ng_l2tp_seq_config_type,
317 NULL
318 },
319 { 0 }
320 };
321
322 /* Node type descriptor */
323 static struct ng_type ng_l2tp_typestruct = {
324 .version = NG_ABI_VERSION,
325 .name = NG_L2TP_NODE_TYPE,
326 .constructor = ng_l2tp_constructor,
327 .rcvmsg = ng_l2tp_rcvmsg,
328 .shutdown = ng_l2tp_shutdown,
329 .newhook = ng_l2tp_newhook,
330 .rcvdata = ng_l2tp_rcvdata,
331 .disconnect = ng_l2tp_disconnect,
332 .cmdlist = ng_l2tp_cmdlist,
333 };
334 NETGRAPH_INIT(l2tp, &ng_l2tp_typestruct);
335
336 /* Sequence number state sanity checking */
337 #ifdef INVARIANTS
338 #define L2TP_SEQ_CHECK(seq) ng_l2tp_seq_check(seq)
339 #else
340 #define L2TP_SEQ_CHECK(x) do { } while (0)
341 #endif
342
343 /* memmove macro */
344 #define memmove(d, s, l) bcopy(s, d, l)
345
346 /* Whether to use m_copypacket() or m_dup() */
347 #define L2TP_COPY_MBUF m_copypacket
348
349 /************************************************************************
350 NETGRAPH NODE STUFF
351 ************************************************************************/
352
353 /*
354 * Node type constructor
355 */
356 static int
357 ng_l2tp_constructor(node_p node)
358 {
359 priv_p priv;
360
361 /* Allocate private structure */
362 MALLOC(priv, priv_p, sizeof(*priv), M_NETGRAPH_L2TP, M_NOWAIT | M_ZERO);
363 if (priv == NULL)
364 return (ENOMEM);
365 NG_NODE_SET_PRIVATE(node, priv);
366 priv->node = node;
367
368 /* Apply a semi-reasonable default configuration */
369 priv->conf.peer_win = 1;
370 priv->conf.rexmit_max = L2TP_MAX_REXMIT;
371 priv->conf.rexmit_max_to = L2TP_MAX_REXMIT_TO;
372
373 /* Initialize sequence number state */
374 ng_l2tp_seq_init(priv);
375
376 /* Done */
377 return (0);
378 }
379
380 /*
381 * Give our OK for a hook to be added.
382 */
383 static int
384 ng_l2tp_newhook(node_p node, hook_p hook, const char *name)
385 {
386 const priv_p priv = NG_NODE_PRIVATE(node);
387
388 /* Check hook name */
389 if (strcmp(name, NG_L2TP_HOOK_CTRL) == 0) {
390 if (priv->ctrl != NULL)
391 return (EISCONN);
392 priv->ctrl = hook;
393 } else if (strcmp(name, NG_L2TP_HOOK_LOWER) == 0) {
394 if (priv->lower != NULL)
395 return (EISCONN);
396 priv->lower = hook;
397 } else {
398 static const char hexdig[16] = "0123456789abcdef";
399 u_int16_t session_id;
400 hookpriv_p hpriv;
401 const char *hex;
402 int i;
403 int j;
404
405 /* Parse hook name to get session ID */
406 if (strncmp(name, NG_L2TP_HOOK_SESSION_P,
407 sizeof(NG_L2TP_HOOK_SESSION_P) - 1) != 0)
408 return (EINVAL);
409 hex = name + sizeof(NG_L2TP_HOOK_SESSION_P) - 1;
410 for (session_id = i = 0; i < 4; i++) {
411 for (j = 0; j < 16 && hex[i] != hexdig[j]; j++);
412 if (j == 16)
413 return (EINVAL);
414 session_id = (session_id << 4) | j;
415 }
416 if (hex[i] != '\0')
417 return (EINVAL);
418
419 /* Create hook private structure */
420 MALLOC(hpriv, hookpriv_p,
421 sizeof(*hpriv), M_NETGRAPH_L2TP, M_NOWAIT | M_ZERO);
422 if (hpriv == NULL)
423 return (ENOMEM);
424 hpriv->conf.session_id = htons(session_id);
425 hpriv->conf.control_dseq = L2TP_CONTROL_DSEQ;
426 hpriv->conf.enable_dseq = L2TP_ENABLE_DSEQ;
427 NG_HOOK_SET_PRIVATE(hook, hpriv);
428 }
429
430 /* Done */
431 return (0);
432 }
433
434 /*
435 * Receive a control message.
436 */
437 static int
438 ng_l2tp_rcvmsg(node_p node, item_p item, hook_p lasthook)
439 {
440 const priv_p priv = NG_NODE_PRIVATE(node);
441 struct ng_mesg *resp = NULL;
442 struct ng_mesg *msg;
443 int error = 0;
444
445 NGI_GET_MSG(item, msg);
446 switch (msg->header.typecookie) {
447 case NGM_L2TP_COOKIE:
448 switch (msg->header.cmd) {
449 case NGM_L2TP_SET_CONFIG:
450 {
451 struct ng_l2tp_config *const conf =
452 (struct ng_l2tp_config *)msg->data;
453
454 /* Check for invalid or illegal config */
455 if (msg->header.arglen != sizeof(*conf)) {
456 error = EINVAL;
457 break;
458 }
459 conf->enabled = !!conf->enabled;
460 conf->match_id = !!conf->match_id;
461 conf->tunnel_id = htons(conf->tunnel_id);
462 conf->peer_id = htons(conf->peer_id);
463 if (priv->conf.enabled
464 && ((priv->conf.tunnel_id != 0
465 && conf->tunnel_id != priv->conf.tunnel_id)
466 || ((priv->conf.peer_id != 0
467 && conf->peer_id != priv->conf.peer_id)))) {
468 error = EBUSY;
469 break;
470 }
471
472 /* Save calling node as failure target */
473 priv->ftarget = NGI_RETADDR(item);
474
475 /* Adjust sequence number state */
476 if ((error = ng_l2tp_seq_adjust(priv, conf)) != 0)
477 break;
478
479 /* Update node's config */
480 priv->conf = *conf;
481 break;
482 }
483 case NGM_L2TP_GET_CONFIG:
484 {
485 struct ng_l2tp_config *conf;
486
487 NG_MKRESPONSE(resp, msg, sizeof(*conf), M_NOWAIT);
488 if (resp == NULL) {
489 error = ENOMEM;
490 break;
491 }
492 conf = (struct ng_l2tp_config *)resp->data;
493 *conf = priv->conf;
494
495 /* Put ID's in host order */
496 conf->tunnel_id = ntohs(conf->tunnel_id);
497 conf->peer_id = ntohs(conf->peer_id);
498 break;
499 }
500 case NGM_L2TP_SET_SESS_CONFIG:
501 {
502 struct ng_l2tp_sess_config *const conf =
503 (struct ng_l2tp_sess_config *)msg->data;
504 hookpriv_p hpriv;
505 hook_p hook;
506
507 /* Check for invalid or illegal config. */
508 if (msg->header.arglen != sizeof(*conf)) {
509 error = EINVAL;
510 break;
511 }
512
513 /* Put ID's in network order */
514 conf->session_id = htons(conf->session_id);
515 conf->peer_id = htons(conf->peer_id);
516
517 /* Find matching hook */
518 NG_NODE_FOREACH_HOOK(node, ng_l2tp_find_session,
519 (void *)(uintptr_t)conf->session_id, hook);
520 if (hook == NULL) {
521 error = ENOENT;
522 break;
523 }
524 hpriv = NG_HOOK_PRIVATE(hook);
525
526 /* Update hook's config */
527 hpriv->conf = *conf;
528 break;
529 }
530 case NGM_L2TP_GET_SESS_CONFIG:
531 {
532 struct ng_l2tp_sess_config *conf;
533 u_int16_t session_id;
534 hookpriv_p hpriv;
535 hook_p hook;
536
537 /* Get session ID */
538 if (msg->header.arglen != sizeof(session_id)) {
539 error = EINVAL;
540 break;
541 }
542 memcpy(&session_id, msg->data, 2);
543 session_id = htons(session_id);
544
545 /* Find matching hook */
546 NG_NODE_FOREACH_HOOK(node, ng_l2tp_find_session,
547 (void *)(uintptr_t)session_id, hook);
548 if (hook == NULL) {
549 error = ENOENT;
550 break;
551 }
552 hpriv = NG_HOOK_PRIVATE(hook);
553
554 /* Send response */
555 NG_MKRESPONSE(resp, msg, sizeof(hpriv->conf), M_NOWAIT);
556 if (resp == NULL) {
557 error = ENOMEM;
558 break;
559 }
560 conf = (struct ng_l2tp_sess_config *)resp->data;
561 *conf = hpriv->conf;
562
563 /* Put ID's in host order */
564 conf->session_id = ntohs(conf->session_id);
565 conf->peer_id = ntohs(conf->peer_id);
566 break;
567 }
568 case NGM_L2TP_GET_STATS:
569 case NGM_L2TP_CLR_STATS:
570 case NGM_L2TP_GETCLR_STATS:
571 {
572 if (msg->header.cmd != NGM_L2TP_CLR_STATS) {
573 NG_MKRESPONSE(resp, msg,
574 sizeof(priv->stats), M_NOWAIT);
575 if (resp == NULL) {
576 error = ENOMEM;
577 break;
578 }
579 memcpy(resp->data,
580 &priv->stats, sizeof(priv->stats));
581 }
582 if (msg->header.cmd != NGM_L2TP_GET_STATS)
583 memset(&priv->stats, 0, sizeof(priv->stats));
584 break;
585 }
586 case NGM_L2TP_GET_SESSION_STATS:
587 case NGM_L2TP_CLR_SESSION_STATS:
588 case NGM_L2TP_GETCLR_SESSION_STATS:
589 {
590 uint16_t session_id;
591 hookpriv_p hpriv;
592 hook_p hook;
593
594 /* Get session ID. */
595 if (msg->header.arglen != sizeof(session_id)) {
596 error = EINVAL;
597 break;
598 }
599 bcopy(msg->data, &session_id, sizeof(uint16_t));
600 session_id = htons(session_id);
601
602 /* Find matching hook. */
603 NG_NODE_FOREACH_HOOK(node, ng_l2tp_find_session,
604 (void *)(uintptr_t)session_id, hook);
605 if (hook == NULL) {
606 error = ENOENT;
607 break;
608 }
609 hpriv = NG_HOOK_PRIVATE(hook);
610
611 if (msg->header.cmd != NGM_L2TP_CLR_SESSION_STATS) {
612 NG_MKRESPONSE(resp, msg,
613 sizeof(hpriv->stats), M_NOWAIT);
614 if (resp == NULL) {
615 error = ENOMEM;
616 break;
617 }
618 bcopy(&hpriv->stats, resp->data,
619 sizeof(hpriv->stats));
620 }
621 if (msg->header.cmd != NGM_L2TP_GET_SESSION_STATS)
622 bzero(&hpriv->stats, sizeof(hpriv->stats));
623 break;
624 }
625 case NGM_L2TP_SET_SEQ:
626 {
627 struct ng_l2tp_seq_config *const conf =
628 (struct ng_l2tp_seq_config *)msg->data;
629
630 /* Check for invalid or illegal seq config. */
631 if (msg->header.arglen != sizeof(*conf)) {
632 error = EINVAL;
633 break;
634 }
635 conf->ns = htons(conf->ns);
636 conf->nr = htons(conf->nr);
637 conf->rack = htons(conf->rack);
638 conf->xack = htons(conf->xack);
639
640 /* Set sequence numbers. */
641 error = ng_l2tp_seq_set(priv, conf);
642 break;
643 }
644 default:
645 error = EINVAL;
646 break;
647 }
648 break;
649 default:
650 error = EINVAL;
651 break;
652 }
653
654 /* Done */
655 NG_RESPOND_MSG(error, node, item, resp);
656 NG_FREE_MSG(msg);
657 return (error);
658 }
659
660 /*
661 * Receive incoming data on a hook.
662 */
663 static int
664 ng_l2tp_rcvdata(hook_p hook, item_p item)
665 {
666 const node_p node = NG_HOOK_NODE(hook);
667 const priv_p priv = NG_NODE_PRIVATE(node);
668 int error;
669
670 /* Sanity check */
671 L2TP_SEQ_CHECK(&priv->seq);
672
673 /* If not configured, reject */
674 if (!priv->conf.enabled) {
675 NG_FREE_ITEM(item);
676 return (ENXIO);
677 }
678
679 /* Handle incoming frame from below */
680 if (hook == priv->lower) {
681 error = ng_l2tp_recv_lower(node, item);
682 goto done;
683 }
684
685 /* Handle outgoing control frame */
686 if (hook == priv->ctrl) {
687 error = ng_l2tp_recv_ctrl(node, item);
688 goto done;
689 }
690
691 /* Handle outgoing data frame */
692 error = ng_l2tp_recv_data(node, item, NG_HOOK_PRIVATE(hook));
693
694 done:
695 /* Done */
696 L2TP_SEQ_CHECK(&priv->seq);
697 return (error);
698 }
699
700 /*
701 * Destroy node
702 */
703 static int
704 ng_l2tp_shutdown(node_p node)
705 {
706 const priv_p priv = NG_NODE_PRIVATE(node);
707 struct l2tp_seq *const seq = &priv->seq;
708
709 /* Sanity check */
710 L2TP_SEQ_CHECK(seq);
711
712 /* Reset sequence number state */
713 ng_l2tp_seq_reset(priv);
714
715 /* Free private data if neither timer is running */
716 if (!seq->rack_timer_running && !seq->xack_timer_running) {
717 FREE(priv, M_NETGRAPH_L2TP);
718 NG_NODE_SET_PRIVATE(node, NULL);
719 }
720
721 /* Unref node */
722 NG_NODE_UNREF(node);
723 return (0);
724 }
725
726 /*
727 * Hook disconnection
728 */
729 static int
730 ng_l2tp_disconnect(hook_p hook)
731 {
732 const node_p node = NG_HOOK_NODE(hook);
733 const priv_p priv = NG_NODE_PRIVATE(node);
734
735 /* Zero out hook pointer */
736 if (hook == priv->ctrl)
737 priv->ctrl = NULL;
738 else if (hook == priv->lower)
739 priv->lower = NULL;
740 else {
741 FREE(NG_HOOK_PRIVATE(hook), M_NETGRAPH_L2TP);
742 NG_HOOK_SET_PRIVATE(hook, NULL);
743 }
744
745 /* Go away if no longer connected to anything */
746 if (NG_NODE_NUMHOOKS(node) == 0 && NG_NODE_IS_VALID(node))
747 ng_rmnode_self(node);
748 return (0);
749 }
750
751 /*************************************************************************
752 INTERNAL FUNCTIONS
753 *************************************************************************/
754
755 /*
756 * Find the hook with a given session ID.
757 */
758 static int
759 ng_l2tp_find_session(hook_p hook, void *arg)
760 {
761 const hookpriv_p hpriv = NG_HOOK_PRIVATE(hook);
762 const u_int16_t sid = (u_int16_t)(uintptr_t)arg;
763
764 if (hpriv == NULL || hpriv->conf.session_id != sid)
765 return (-1);
766 return (0);
767 }
768
769 /*
770 * Reset a hook's session state.
771 */
772 static int
773 ng_l2tp_reset_session(hook_p hook, void *arg)
774 {
775 const hookpriv_p hpriv = NG_HOOK_PRIVATE(hook);
776
777 if (hpriv != NULL) {
778 hpriv->conf.control_dseq = 0;
779 hpriv->conf.enable_dseq = 0;
780 bzero(&hpriv->conf, sizeof(struct ng_l2tp_session_stats));
781 hpriv->nr = 0;
782 hpriv->ns = 0;
783 }
784 return (-1);
785 }
786
787 /*
788 * Handle an incoming frame from below.
789 */
790 static int
791 ng_l2tp_recv_lower(node_p node, item_p item)
792 {
793 static const u_int16_t req_bits[2][2] = {
794 { L2TP_DATA_0BITS, L2TP_DATA_1BITS },
795 { L2TP_CTRL_0BITS, L2TP_CTRL_1BITS },
796 };
797 const priv_p priv = NG_NODE_PRIVATE(node);
798 hookpriv_p hpriv = NULL;
799 hook_p hook = NULL;
800 u_int16_t ids[2];
801 struct mbuf *m;
802 u_int16_t hdr;
803 u_int16_t ns;
804 u_int16_t nr;
805 int is_ctrl;
806 int error;
807 int len, plen;
808
809 /* Grab mbuf */
810 NGI_GET_M(item, m);
811
812 /* Remember full packet length; needed for per session accounting. */
813 plen = m->m_pkthdr.len;
814
815 /* Update stats */
816 priv->stats.recvPackets++;
817 priv->stats.recvOctets += plen;
818
819 /* Get initial header */
820 if (m->m_pkthdr.len < 6) {
821 priv->stats.recvRunts++;
822 NG_FREE_ITEM(item);
823 NG_FREE_M(m);
824 return (EINVAL);
825 }
826 if (m->m_len < 2 && (m = m_pullup(m, 2)) == NULL) {
827 priv->stats.memoryFailures++;
828 NG_FREE_ITEM(item);
829 return (EINVAL);
830 }
831 hdr = ntohs(*mtod(m, u_int16_t *));
832 m_adj(m, 2);
833
834 /* Check required header bits and minimum length */
835 is_ctrl = (hdr & L2TP_HDR_CTRL) != 0;
836 if ((hdr & req_bits[is_ctrl][0]) != 0
837 || (~hdr & req_bits[is_ctrl][1]) != 0) {
838 priv->stats.recvInvalid++;
839 NG_FREE_ITEM(item);
840 NG_FREE_M(m);
841 return (EINVAL);
842 }
843 if (m->m_pkthdr.len < 4 /* tunnel, session id */
844 + (2 * ((hdr & L2TP_HDR_LEN) != 0)) /* length field */
845 + (4 * ((hdr & L2TP_HDR_SEQ) != 0)) /* seq # fields */
846 + (2 * ((hdr & L2TP_HDR_OFF) != 0))) { /* offset field */
847 priv->stats.recvRunts++;
848 NG_FREE_ITEM(item);
849 NG_FREE_M(m);
850 return (EINVAL);
851 }
852
853 /* Get and validate length field if present */
854 if ((hdr & L2TP_HDR_LEN) != 0) {
855 if (m->m_len < 2 && (m = m_pullup(m, 2)) == NULL) {
856 priv->stats.memoryFailures++;
857 NG_FREE_ITEM(item);
858 return (EINVAL);
859 }
860 len = (u_int16_t)ntohs(*mtod(m, u_int16_t *)) - 4;
861 m_adj(m, 2);
862 if (len < 0 || len > m->m_pkthdr.len) {
863 priv->stats.recvInvalid++;
864 NG_FREE_ITEM(item);
865 NG_FREE_M(m);
866 return (EINVAL);
867 }
868 if (len < m->m_pkthdr.len) /* trim extra bytes */
869 m_adj(m, -(m->m_pkthdr.len - len));
870 }
871
872 /* Get tunnel ID and session ID */
873 if (m->m_len < 4 && (m = m_pullup(m, 4)) == NULL) {
874 priv->stats.memoryFailures++;
875 NG_FREE_ITEM(item);
876 return (EINVAL);
877 }
878 memcpy(ids, mtod(m, u_int16_t *), 4);
879 m_adj(m, 4);
880
881 /* Check tunnel ID */
882 if (ids[0] != priv->conf.tunnel_id
883 && (priv->conf.match_id || ids[0] != 0)) {
884 priv->stats.recvWrongTunnel++;
885 NG_FREE_ITEM(item);
886 NG_FREE_M(m);
887 return (EADDRNOTAVAIL);
888 }
889
890 /* Check session ID (for data packets only) */
891 if ((hdr & L2TP_HDR_CTRL) == 0) {
892 NG_NODE_FOREACH_HOOK(node, ng_l2tp_find_session,
893 (void *)(uintptr_t)ids[1], hook);
894 if (hook == NULL) {
895 priv->stats.recvUnknownSID++;
896 NG_FREE_ITEM(item);
897 NG_FREE_M(m);
898 return (ENOTCONN);
899 }
900 hpriv = NG_HOOK_PRIVATE(hook);
901 }
902
903 /* Get Ns, Nr fields if present */
904 if ((hdr & L2TP_HDR_SEQ) != 0) {
905 if (m->m_len < 4 && (m = m_pullup(m, 4)) == NULL) {
906 priv->stats.memoryFailures++;
907 NG_FREE_ITEM(item);
908 return (EINVAL);
909 }
910 memcpy(&ns, &mtod(m, u_int16_t *)[0], 2);
911 ns = ntohs(ns);
912 memcpy(&nr, &mtod(m, u_int16_t *)[1], 2);
913 nr = ntohs(nr);
914 m_adj(m, 4);
915 }
916
917 /* Strip offset padding if present */
918 if ((hdr & L2TP_HDR_OFF) != 0) {
919 u_int16_t offset;
920
921 /* Get length of offset padding */
922 if (m->m_len < 2 && (m = m_pullup(m, 2)) == NULL) {
923 priv->stats.memoryFailures++;
924 NG_FREE_ITEM(item);
925 return (EINVAL);
926 }
927 memcpy(&offset, mtod(m, u_int16_t *), 2);
928 offset = ntohs(offset);
929
930 /* Trim offset padding */
931 if ((2+offset) > m->m_pkthdr.len) {
932 priv->stats.recvInvalid++;
933 NG_FREE_ITEM(item);
934 NG_FREE_M(m);
935 return (EINVAL);
936 }
937 m_adj(m, 2+offset);
938 }
939
940 /* Handle control packets */
941 if ((hdr & L2TP_HDR_CTRL) != 0) {
942
943 /* Handle receive ack sequence number Nr */
944 ng_l2tp_seq_recv_nr(priv, nr);
945
946 /* Discard ZLB packets */
947 if (m->m_pkthdr.len == 0) {
948 priv->stats.recvZLBs++;
949 NG_FREE_ITEM(item);
950 NG_FREE_M(m);
951 return (0);
952 }
953
954 /*
955 * Prepend session ID to packet here: we don't want to accept
956 * the send sequence number Ns if we have to drop the packet
957 * later because of a memory error, because then the upper
958 * layer would never get the packet.
959 */
960 M_PREPEND(m, 2, M_DONTWAIT);
961 if (m == NULL) {
962 priv->stats.memoryFailures++;
963 NG_FREE_ITEM(item);
964 return (ENOBUFS);
965 }
966 memcpy(mtod(m, u_int16_t *), &ids[1], 2);
967
968 /* Now handle send sequence number */
969 if (ng_l2tp_seq_recv_ns(priv, ns) == -1) {
970 NG_FREE_ITEM(item);
971 NG_FREE_M(m);
972 return (0);
973 }
974
975 /* Deliver packet to upper layers */
976 NG_FWD_NEW_DATA(error, item, priv->ctrl, m);
977 return (error);
978 }
979
980 /* Per session packet, account it. */
981 hpriv->stats.recvPackets++;
982 hpriv->stats.recvOctets += plen;
983
984 /* Follow peer's lead in data sequencing, if configured to do so */
985 if (!hpriv->conf.control_dseq)
986 hpriv->conf.enable_dseq = ((hdr & L2TP_HDR_SEQ) != 0);
987
988 /* Handle data sequence numbers if present and enabled */
989 if ((hdr & L2TP_HDR_SEQ) != 0) {
990 if (hpriv->conf.enable_dseq
991 && L2TP_SEQ_DIFF(ns, hpriv->nr) < 0) {
992 NG_FREE_ITEM(item); /* duplicate or out of order */
993 NG_FREE_M(m);
994 priv->stats.recvDataDrops++;
995 return (0);
996 }
997 hpriv->nr = ns + 1;
998 }
999
1000 /* Drop empty data packets */
1001 if (m->m_pkthdr.len == 0) {
1002 NG_FREE_ITEM(item);
1003 NG_FREE_M(m);
1004 return (0);
1005 }
1006
1007 /* Deliver data */
1008 NG_FWD_NEW_DATA(error, item, hook, m);
1009 return (error);
1010 }
1011
1012 /*
1013 * Handle an outgoing control frame.
1014 */
1015 static int
1016 ng_l2tp_recv_ctrl(node_p node, item_p item)
1017 {
1018 const priv_p priv = NG_NODE_PRIVATE(node);
1019 struct l2tp_seq *const seq = &priv->seq;
1020 struct mbuf *m;
1021 int i;
1022
1023 /* Grab mbuf and discard other stuff XXX */
1024 NGI_GET_M(item, m);
1025 NG_FREE_ITEM(item);
1026
1027 /* Packet should have session ID prepended */
1028 if (m->m_pkthdr.len < 2) {
1029 priv->stats.xmitInvalid++;
1030 m_freem(m);
1031 return (EINVAL);
1032 }
1033
1034 /* Check max length */
1035 if (m->m_pkthdr.len >= 0x10000 - 14) {
1036 priv->stats.xmitTooBig++;
1037 m_freem(m);
1038 return (EOVERFLOW);
1039 }
1040
1041 /* Find next empty slot in transmit queue */
1042 for (i = 0; i < L2TP_MAX_XWIN && seq->xwin[i] != NULL; i++);
1043 if (i == L2TP_MAX_XWIN) {
1044 priv->stats.xmitDrops++;
1045 m_freem(m);
1046 return (ENOBUFS);
1047 }
1048 seq->xwin[i] = m;
1049
1050 /* Sanity check receive ack timer state */
1051 KASSERT((i == 0) ^ seq->rack_timer_running,
1052 ("%s: xwin %d full but rack timer %srunning",
1053 __FUNCTION__, i, seq->rack_timer_running ? "" : "not "));
1054
1055 /* If peer's receive window is already full, nothing else to do */
1056 if (i >= seq->cwnd)
1057 return (0);
1058
1059 /* Start retransmit timer if not already running */
1060 if (!seq->rack_timer_running) {
1061 callout_reset(&seq->rack_timer,
1062 hz, ng_l2tp_seq_rack_timeout, node);
1063 seq->rack_timer_running = 1;
1064 NG_NODE_REF(node);
1065 }
1066
1067 /* Copy packet */
1068 if ((m = L2TP_COPY_MBUF(seq->xwin[i], M_DONTWAIT)) == NULL) {
1069 priv->stats.memoryFailures++;
1070 return (ENOBUFS);
1071 }
1072
1073 /* Send packet and increment xmit sequence number */
1074 return (ng_l2tp_xmit_ctrl(priv, m, seq->ns++));
1075 }
1076
1077 /*
1078 * Handle an outgoing data frame.
1079 */
1080 static int
1081 ng_l2tp_recv_data(node_p node, item_p item, hookpriv_p hpriv)
1082 {
1083 const priv_p priv = NG_NODE_PRIVATE(node);
1084 struct mbuf *m;
1085 u_int16_t hdr;
1086 int error;
1087 int i = 1;
1088
1089 /* Get mbuf */
1090 NGI_GET_M(item, m);
1091
1092 /* Check max length */
1093 if (m->m_pkthdr.len >= 0x10000 - 12) {
1094 priv->stats.xmitDataTooBig++;
1095 NG_FREE_ITEM(item);
1096 NG_FREE_M(m);
1097 return (EOVERFLOW);
1098 }
1099
1100 /* Prepend L2TP header */
1101 M_PREPEND(m, 6
1102 + (2 * (hpriv->conf.include_length != 0))
1103 + (4 * (hpriv->conf.enable_dseq != 0)),
1104 M_DONTWAIT);
1105 if (m == NULL) {
1106 priv->stats.memoryFailures++;
1107 NG_FREE_ITEM(item);
1108 return (ENOBUFS);
1109 }
1110 hdr = L2TP_DATA_HDR;
1111 if (hpriv->conf.include_length) {
1112 hdr |= L2TP_HDR_LEN;
1113 mtod(m, u_int16_t *)[i++] = htons(m->m_pkthdr.len);
1114 }
1115 mtod(m, u_int16_t *)[i++] = priv->conf.peer_id;
1116 mtod(m, u_int16_t *)[i++] = hpriv->conf.peer_id;
1117 if (hpriv->conf.enable_dseq) {
1118 hdr |= L2TP_HDR_SEQ;
1119 mtod(m, u_int16_t *)[i++] = htons(hpriv->ns);
1120 mtod(m, u_int16_t *)[i++] = htons(hpriv->nr);
1121 hpriv->ns++;
1122 }
1123 mtod(m, u_int16_t *)[0] = htons(hdr);
1124
1125 /* Update per session stats. */
1126 hpriv->stats.xmitPackets++;
1127 hpriv->stats.xmitOctets += m->m_pkthdr.len;
1128
1129 /* Send packet */
1130 NG_FWD_NEW_DATA(error, item, priv->lower, m);
1131 return (error);
1132 }
1133
1134 /*
1135 * Send a message to our controlling node that we've failed.
1136 */
1137 static void
1138 ng_l2tp_seq_failure(priv_p priv)
1139 {
1140 struct ng_mesg *msg;
1141 int error;
1142
1143 NG_MKMESSAGE(msg, NGM_L2TP_COOKIE, NGM_L2TP_ACK_FAILURE, 0, M_NOWAIT);
1144 if (msg == NULL)
1145 return;
1146 NG_SEND_MSG_ID(error, priv->node, msg, priv->ftarget, 0);
1147 }
1148
1149 /************************************************************************
1150 SEQUENCE NUMBER HANDLING
1151 ************************************************************************/
1152
1153 /*
1154 * Initialize sequence number state.
1155 */
1156 static void
1157 ng_l2tp_seq_init(priv_p priv)
1158 {
1159 struct l2tp_seq *const seq = &priv->seq;
1160
1161 KASSERT(priv->conf.peer_win >= 1,
1162 ("%s: peer_win is zero", __FUNCTION__));
1163 memset(seq, 0, sizeof(*seq));
1164 seq->cwnd = 1;
1165 seq->wmax = priv->conf.peer_win;
1166 if (seq->wmax > L2TP_MAX_XWIN)
1167 seq->wmax = L2TP_MAX_XWIN;
1168 seq->ssth = seq->wmax;
1169 seq->max_rexmits = priv->conf.rexmit_max;
1170 seq->max_rexmit_to = priv->conf.rexmit_max_to;
1171 callout_init(&seq->rack_timer, 0);
1172 callout_init(&seq->xack_timer, 0);
1173 L2TP_SEQ_CHECK(seq);
1174 }
1175
1176 /*
1177 * Set sequence number state as given from user.
1178 */
1179 static int
1180 ng_l2tp_seq_set(priv_p priv, const struct ng_l2tp_seq_config *conf)
1181 {
1182 struct l2tp_seq *const seq = &priv->seq;
1183
1184 /* If node is enabled, deny update to sequence numbers. */
1185 if (priv->conf.enabled)
1186 return (EBUSY);
1187
1188 /* We only can handle the simple cases. */
1189 if (conf->xack != conf->nr || conf->ns != conf->rack)
1190 return (EINVAL);
1191
1192 /* Set ns,nr,rack,xack parameters. */
1193 seq->ns = conf->ns;
1194 seq->nr = conf->nr;
1195 seq->rack = conf->rack;
1196 seq->xack = conf->xack;
1197
1198 return (0);
1199 }
1200
1201 /*
1202 * Adjust sequence number state accordingly after reconfiguration.
1203 */
1204 static int
1205 ng_l2tp_seq_adjust(priv_p priv, const struct ng_l2tp_config *conf)
1206 {
1207 struct l2tp_seq *const seq = &priv->seq;
1208 u_int16_t new_wmax;
1209
1210 /* If disabling node, reset state sequence number */
1211 if (!conf->enabled) {
1212 ng_l2tp_seq_reset(priv);
1213 return (0);
1214 }
1215
1216 /* Adjust peer's max recv window; it can only increase */
1217 new_wmax = conf->peer_win;
1218 if (new_wmax > L2TP_MAX_XWIN)
1219 new_wmax = L2TP_MAX_XWIN;
1220 if (new_wmax == 0)
1221 return (EINVAL);
1222 if (new_wmax < seq->wmax)
1223 return (EBUSY);
1224 seq->wmax = new_wmax;
1225
1226 /* Update retransmit parameters */
1227 seq->max_rexmits = conf->rexmit_max;
1228 seq->max_rexmit_to = conf->rexmit_max_to;
1229
1230 /* Done */
1231 return (0);
1232 }
1233
1234 /*
1235 * Reset sequence number state.
1236 */
1237 static void
1238 ng_l2tp_seq_reset(priv_p priv)
1239 {
1240 struct l2tp_seq *const seq = &priv->seq;
1241 hook_p hook;
1242 int i;
1243
1244 /* Sanity check */
1245 L2TP_SEQ_CHECK(seq);
1246
1247 /* Stop timers */
1248 if (seq->rack_timer_running && callout_stop(&seq->rack_timer) == 1) {
1249 seq->rack_timer_running = 0;
1250 NG_NODE_UNREF(priv->node);
1251 }
1252 if (seq->xack_timer_running && callout_stop(&seq->xack_timer) == 1) {
1253 seq->xack_timer_running = 0;
1254 NG_NODE_UNREF(priv->node);
1255 }
1256
1257 /* Free retransmit queue */
1258 for (i = 0; i < L2TP_MAX_XWIN; i++) {
1259 if (seq->xwin[i] == NULL)
1260 break;
1261 m_freem(seq->xwin[i]);
1262 }
1263
1264 /* Reset session hooks' sequence number states */
1265 NG_NODE_FOREACH_HOOK(priv->node, ng_l2tp_reset_session, NULL, hook);
1266
1267 /* Reset node's sequence number state */
1268 memset(seq, 0, sizeof(*seq));
1269 seq->cwnd = 1;
1270 seq->wmax = L2TP_MAX_XWIN;
1271 seq->ssth = seq->wmax;
1272
1273 /* Done */
1274 L2TP_SEQ_CHECK(seq);
1275 }
1276
1277 /*
1278 * Handle receipt of an acknowledgement value (Nr) from peer.
1279 */
1280 static void
1281 ng_l2tp_seq_recv_nr(priv_p priv, u_int16_t nr)
1282 {
1283 struct l2tp_seq *const seq = &priv->seq;
1284 struct mbuf *m;
1285 int nack;
1286 int i;
1287
1288 /* Verify peer's ACK is in range */
1289 if ((nack = L2TP_SEQ_DIFF(nr, seq->rack)) <= 0)
1290 return; /* duplicate ack */
1291 if (L2TP_SEQ_DIFF(nr, seq->ns) > 0) {
1292 priv->stats.recvBadAcks++; /* ack for packet not sent */
1293 return;
1294 }
1295 KASSERT(nack <= L2TP_MAX_XWIN,
1296 ("%s: nack=%d > %d", __FUNCTION__, nack, L2TP_MAX_XWIN));
1297
1298 /* Update receive ack stats */
1299 seq->rack = nr;
1300 seq->rexmits = 0;
1301
1302 /* Free acknowledged packets and shift up packets in the xmit queue */
1303 for (i = 0; i < nack; i++)
1304 m_freem(seq->xwin[i]);
1305 memmove(seq->xwin, seq->xwin + nack,
1306 (L2TP_MAX_XWIN - nack) * sizeof(*seq->xwin));
1307 memset(seq->xwin + (L2TP_MAX_XWIN - nack), 0,
1308 nack * sizeof(*seq->xwin));
1309
1310 /*
1311 * Do slow-start/congestion avoidance windowing algorithm described
1312 * in RFC 2661, Appendix A. Here we handle a multiple ACK as if each
1313 * ACK had arrived separately.
1314 */
1315 if (seq->cwnd < seq->wmax) {
1316
1317 /* Handle slow start phase */
1318 if (seq->cwnd < seq->ssth) {
1319 seq->cwnd += nack;
1320 nack = 0;
1321 if (seq->cwnd > seq->ssth) { /* into cg.av. phase */
1322 nack = seq->cwnd - seq->ssth;
1323 seq->cwnd = seq->ssth;
1324 }
1325 }
1326
1327 /* Handle congestion avoidance phase */
1328 if (seq->cwnd >= seq->ssth) {
1329 seq->acks += nack;
1330 while (seq->acks >= seq->cwnd) {
1331 seq->acks -= seq->cwnd;
1332 if (seq->cwnd < seq->wmax)
1333 seq->cwnd++;
1334 }
1335 }
1336 }
1337
1338 /* Stop xmit timer */
1339 if (seq->rack_timer_running && callout_stop(&seq->rack_timer) == 1) {
1340 seq->rack_timer_running = 0;
1341 NG_NODE_UNREF(priv->node);
1342 }
1343
1344 /* If transmit queue is empty, we're done for now */
1345 if (seq->xwin[0] == NULL)
1346 return;
1347
1348 /* Start restransmit timer again */
1349 callout_reset(&seq->rack_timer,
1350 hz, ng_l2tp_seq_rack_timeout, priv->node);
1351 seq->rack_timer_running = 1;
1352 NG_NODE_REF(priv->node);
1353
1354 /*
1355 * Send more packets, trying to keep peer's receive window full.
1356 * If there is a memory error, pretend packet was sent, as it
1357 * will get retransmitted later anyway.
1358 */
1359 while ((i = L2TP_SEQ_DIFF(seq->ns, seq->rack)) < seq->cwnd
1360 && seq->xwin[i] != NULL) {
1361 if ((m = L2TP_COPY_MBUF(seq->xwin[i], M_DONTWAIT)) == NULL)
1362 priv->stats.memoryFailures++;
1363 else
1364 ng_l2tp_xmit_ctrl(priv, m, seq->ns);
1365 seq->ns++;
1366 }
1367 }
1368
1369 /*
1370 * Handle receipt of a sequence number value (Ns) from peer.
1371 * We make no attempt to re-order out of order packets.
1372 *
1373 * This function should only be called for non-ZLB packets.
1374 *
1375 * Returns:
1376 * 0 Accept packet
1377 * -1 Drop packet
1378 */
1379 static int
1380 ng_l2tp_seq_recv_ns(priv_p priv, u_int16_t ns)
1381 {
1382 struct l2tp_seq *const seq = &priv->seq;
1383
1384 /* If not what we expect, drop packet and send an immediate ZLB ack */
1385 if (ns != seq->nr) {
1386 if (L2TP_SEQ_DIFF(ns, seq->nr) < 0)
1387 priv->stats.recvDuplicates++;
1388 else
1389 priv->stats.recvOutOfOrder++;
1390 ng_l2tp_xmit_ctrl(priv, NULL, seq->ns);
1391 return (-1);
1392 }
1393
1394 /* Update recv sequence number */
1395 seq->nr++;
1396
1397 /* Start receive ack timer, if not already running */
1398 if (!seq->xack_timer_running) {
1399 callout_reset(&seq->xack_timer,
1400 L2TP_DELAYED_ACK, ng_l2tp_seq_xack_timeout, priv->node);
1401 seq->xack_timer_running = 1;
1402 NG_NODE_REF(priv->node);
1403 }
1404
1405 /* Accept packet */
1406 return (0);
1407 }
1408
1409 /*
1410 * Handle an ack timeout. We have an outstanding ack that we
1411 * were hoping to piggy-back, but haven't, so send a ZLB.
1412 */
1413 static void
1414 ng_l2tp_seq_xack_timeout(void *arg)
1415 {
1416 const node_p node = arg;
1417 const priv_p priv = NG_NODE_PRIVATE(node);
1418 struct l2tp_seq *const seq = &priv->seq;
1419 int s;
1420
1421 /* Check if node is going away */
1422 s = splnet();
1423 if (NG_NODE_NOT_VALID(node)) {
1424 seq->xack_timer_running = 0;
1425 if (!seq->rack_timer_running) {
1426 FREE(priv, M_NETGRAPH_L2TP);
1427 NG_NODE_SET_PRIVATE(node, NULL);
1428 }
1429 NG_NODE_UNREF(node);
1430 splx(s);
1431 return;
1432 }
1433
1434 /* Sanity check */
1435 L2TP_SEQ_CHECK(seq);
1436
1437 /* If ack is still outstanding, send a ZLB */
1438 if (seq->xack != seq->nr)
1439 ng_l2tp_xmit_ctrl(priv, NULL, seq->ns);
1440
1441 /* Done */
1442 seq->xack_timer_running = 0;
1443 NG_NODE_UNREF(node);
1444 L2TP_SEQ_CHECK(seq);
1445 splx(s);
1446 }
1447
1448 /*
1449 * Handle a transmit timeout. The peer has failed to respond
1450 * with an ack for our packet, so retransmit it.
1451 */
1452 static void
1453 ng_l2tp_seq_rack_timeout(void *arg)
1454 {
1455 const node_p node = arg;
1456 const priv_p priv = NG_NODE_PRIVATE(node);
1457 struct l2tp_seq *const seq = &priv->seq;
1458 struct mbuf *m;
1459 u_int delay;
1460 int s;
1461
1462 /* Check if node is going away */
1463 s = splnet();
1464 if (NG_NODE_NOT_VALID(node)) {
1465 seq->rack_timer_running = 0;
1466 if (!seq->xack_timer_running) {
1467 FREE(priv, M_NETGRAPH_L2TP);
1468 NG_NODE_SET_PRIVATE(node, NULL);
1469 }
1470 NG_NODE_UNREF(node);
1471 splx(s);
1472 return;
1473 }
1474
1475 /* Sanity check */
1476 L2TP_SEQ_CHECK(seq);
1477
1478 /* Make sure peer's ack is still outstanding before doing anything */
1479 if (seq->rack == seq->ns) {
1480 seq->rack_timer_running = 0;
1481 NG_NODE_UNREF(node);
1482 goto done;
1483 }
1484 priv->stats.xmitRetransmits++;
1485
1486 /* Have we reached the retransmit limit? If so, notify owner. */
1487 if (seq->rexmits++ >= seq->max_rexmits)
1488 ng_l2tp_seq_failure(priv);
1489
1490 /* Restart timer, this time with an increased delay */
1491 delay = (seq->rexmits > 12) ? (1 << 12) : (1 << seq->rexmits);
1492 if (delay > seq->max_rexmit_to)
1493 delay = seq->max_rexmit_to;
1494 callout_reset(&seq->rack_timer,
1495 hz * delay, ng_l2tp_seq_rack_timeout, node);
1496
1497 /* Do slow-start/congestion algorithm windowing algorithm */
1498 seq->ssth = (seq->cwnd + 1) / 2;
1499 seq->cwnd = 1;
1500 seq->acks = 0;
1501
1502 /* Retransmit oldest unack'd packet */
1503 if ((m = L2TP_COPY_MBUF(seq->xwin[0], M_DONTWAIT)) == NULL)
1504 priv->stats.memoryFailures++;
1505 else
1506 ng_l2tp_xmit_ctrl(priv, m, seq->rack);
1507
1508 done:
1509 /* Done */
1510 L2TP_SEQ_CHECK(seq);
1511 splx(s);
1512 }
1513
1514 /*
1515 * Transmit a control stream packet, payload optional.
1516 * The transmit sequence number is not incremented.
1517 */
1518 static int
1519 ng_l2tp_xmit_ctrl(priv_p priv, struct mbuf *m, u_int16_t ns)
1520 {
1521 struct l2tp_seq *const seq = &priv->seq;
1522 u_int16_t session_id = 0;
1523 int error;
1524
1525 /* If no mbuf passed, send an empty packet (ZLB) */
1526 if (m == NULL) {
1527
1528 /* Create a new mbuf for ZLB packet */
1529 MGETHDR(m, M_DONTWAIT, MT_DATA);
1530 if (m == NULL) {
1531 priv->stats.memoryFailures++;
1532 return (ENOBUFS);
1533 }
1534 m->m_len = m->m_pkthdr.len = 12;
1535 m->m_pkthdr.rcvif = NULL;
1536 priv->stats.xmitZLBs++;
1537 } else {
1538
1539 /* Strip off session ID */
1540 if (m->m_len < 2 && (m = m_pullup(m, 2)) == NULL) {
1541 priv->stats.memoryFailures++;
1542 return (ENOBUFS);
1543 }
1544 memcpy(&session_id, mtod(m, u_int16_t *), 2);
1545 m_adj(m, 2);
1546
1547 /* Make room for L2TP header */
1548 M_PREPEND(m, 12, M_DONTWAIT);
1549 if (m == NULL) {
1550 priv->stats.memoryFailures++;
1551 return (ENOBUFS);
1552 }
1553 }
1554
1555 /* Fill in L2TP header */
1556 mtod(m, u_int16_t *)[0] = htons(L2TP_CTRL_HDR);
1557 mtod(m, u_int16_t *)[1] = htons(m->m_pkthdr.len);
1558 mtod(m, u_int16_t *)[2] = priv->conf.peer_id;
1559 mtod(m, u_int16_t *)[3] = session_id;
1560 mtod(m, u_int16_t *)[4] = htons(ns);
1561 mtod(m, u_int16_t *)[5] = htons(seq->nr);
1562
1563 /* Update sequence number info and stats */
1564 priv->stats.xmitPackets++;
1565 priv->stats.xmitOctets += m->m_pkthdr.len;
1566
1567 /* Stop ack timer: we're sending an ack with this packet */
1568 if (seq->xack_timer_running && callout_stop(&seq->xack_timer) == 1) {
1569 seq->xack_timer_running = 0;
1570 NG_NODE_UNREF(priv->node);
1571 }
1572 seq->xack = seq->nr;
1573
1574 /* Send packet */
1575 NG_SEND_DATA_ONLY(error, priv->lower, m);
1576 return (error);
1577 }
1578
1579 #ifdef INVARIANTS
1580 /*
1581 * Sanity check sequence number state.
1582 */
1583 static void
1584 ng_l2tp_seq_check(struct l2tp_seq *seq)
1585 {
1586 const int self_unack = L2TP_SEQ_DIFF(seq->nr, seq->xack);
1587 const int peer_unack = L2TP_SEQ_DIFF(seq->ns, seq->rack);
1588 int i;
1589
1590 #define CHECK(p) KASSERT((p), ("%s: not: %s", __FUNCTION__, #p))
1591
1592 CHECK(seq->wmax <= L2TP_MAX_XWIN);
1593 CHECK(seq->cwnd >= 1);
1594 CHECK(seq->cwnd <= seq->wmax);
1595 CHECK(seq->ssth >= 1);
1596 CHECK(seq->ssth <= seq->wmax);
1597 if (seq->cwnd < seq->ssth)
1598 CHECK(seq->acks == 0);
1599 else
1600 CHECK(seq->acks <= seq->cwnd);
1601 CHECK(self_unack >= 0);
1602 CHECK(peer_unack >= 0);
1603 CHECK(peer_unack <= seq->wmax);
1604 CHECK((self_unack == 0) ^ seq->xack_timer_running);
1605 CHECK((peer_unack == 0) ^ seq->rack_timer_running);
1606 CHECK(seq->rack_timer_running || !callout_pending(&seq->rack_timer));
1607 CHECK(seq->xack_timer_running || !callout_pending(&seq->xack_timer));
1608 for (i = 0; i < peer_unack; i++)
1609 CHECK(seq->xwin[i] != NULL);
1610 for ( ; i < seq->cwnd; i++) /* verify peer's recv window full */
1611 CHECK(seq->xwin[i] == NULL);
1612
1613 #undef CHECK
1614 }
1615 #endif /* INVARIANTS */
1616
1617
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