ether.c revision 68846 
1/*-
2 * Copyright (c) 1999 Brian Somers <brian@Awfulhak.org>
3 * All rights reserved.
4 *
5 * Redistribution and use in source and binary forms, with or without
6 * modification, are permitted provided that the following conditions
7 * are met:
8 * 1. Redistributions of source code must retain the above copyright
9 *    notice, this list of conditions and the following disclaimer.
10 * 2. Redistributions in binary form must reproduce the above copyright
11 *    notice, this list of conditions and the following disclaimer in the
12 *    documentation and/or other materials provided with the distribution.
13 *
14 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
15 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
16 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
17 * ARE DISCLAIMED.  IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
18 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
19 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
20 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
21 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
22 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
23 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
24 * SUCH DAMAGE.
25 *
26 * $FreeBSD: head/usr.sbin/ppp/ether.c 68846 2000-11-16 23:15:42Z brian $
27 */
28
29#include <sys/param.h>
30#include <sys/socket.h>
31#include <sys/un.h>
32#include <netinet/in.h>
33#include <arpa/inet.h>
34#include <netdb.h>
35#include <netgraph.h>
36#include <net/ethernet.h>
37#include <netinet/in_systm.h>
38#include <netinet/ip.h>
39#include <netgraph/ng_ether.h>
40#include <netgraph/ng_message.h>
41#include <netgraph/ng_pppoe.h>
42#include <netgraph/ng_socket.h>
43
44#include <errno.h>
45#include <stdio.h>
46#include <stdlib.h>
47#include <string.h>
48#include <sysexits.h>
49#include <sys/fcntl.h>
50#if defined(__FreeBSD__) && !defined(NOKLDLOAD)
51#include <sys/linker.h>
52#include <sys/module.h>
53#endif
54#include <sys/uio.h>
55#include <termios.h>
56#include <sys/time.h>
57#include <unistd.h>
58
59#include "layer.h"
60#include "defs.h"
61#include "mbuf.h"
62#include "log.h"
63#include "timer.h"
64#include "lqr.h"
65#include "hdlc.h"
66#include "throughput.h"
67#include "fsm.h"
68#include "lcp.h"
69#include "ccp.h"
70#include "link.h"
71#include "async.h"
72#include "descriptor.h"
73#include "physical.h"
74#include "main.h"
75#include "mp.h"
76#include "chat.h"
77#include "auth.h"
78#include "chap.h"
79#include "cbcp.h"
80#include "datalink.h"
81#include "slcompress.h"
82#include "iplist.h"
83#include "ipcp.h"
84#include "filter.h"
85#ifndef NORADIUS
86#include "radius.h"
87#endif
88#include "bundle.h"
89#include "id.h"
90#include "ether.h"
91
92
93#define PPPOE_NODE_TYPE_LEN (sizeof NG_PPPOE_NODE_TYPE - 1) /* "PPPoE" */
94
95struct etherdevice {
96  struct device dev;			/* What struct physical knows about */
97  int cs;				/* Control socket */
98  int connected;			/* Are we connected yet ? */
99  int timeout;				/* Seconds attempting to connect */
100  char hook[sizeof TUN_NAME + 11];	/* Our socket node hook */
101};
102
103#define device2ether(d) \
104  ((d)->type == ETHER_DEVICE ? (struct etherdevice *)d : NULL)
105
106int
107ether_DeviceSize(void)
108{
109  return sizeof(struct etherdevice);
110}
111
112static ssize_t
113ether_Write(struct physical *p, const void *v, size_t n)
114{
115  struct etherdevice *dev = device2ether(p->handler);
116
117  return NgSendData(p->fd, dev->hook, v, n) == -1 ? -1 : n;
118}
119
120static ssize_t
121ether_Read(struct physical *p, void *v, size_t n)
122{
123  char hook[sizeof TUN_NAME + 11];
124
125  return NgRecvData(p->fd, v, n, hook);
126}
127
128static int
129ether_RemoveFromSet(struct physical *p, fd_set *r, fd_set *w, fd_set *e)
130{
131  struct etherdevice *dev = device2ether(p->handler);
132  int result;
133
134  if (r && dev->cs >= 0 && FD_ISSET(dev->cs, r)) {
135    FD_CLR(dev->cs, r);
136    log_Printf(LogTIMER, "%s: fdunset(ctrl) %d\n", p->link.name, dev->cs);
137    result = 1;
138  } else
139    result = 0;
140
141  /* Careful... physical_RemoveFromSet() called us ! */
142
143  p->handler->removefromset = NULL;
144  result += physical_RemoveFromSet(p, r, w, e);
145  p->handler->removefromset = ether_RemoveFromSet;
146
147  return result;
148}
149
150static void
151ether_Free(struct physical *p)
152{
153  struct etherdevice *dev = device2ether(p->handler);
154
155  physical_SetDescriptor(p);
156  if (dev->cs != -1)
157    close(dev->cs);
158  free(dev);
159}
160
161static const char *
162ether_OpenInfo(struct physical *p)
163{
164  struct etherdevice *dev = device2ether(p->handler);
165
166  switch (dev->connected) {
167    case CARRIER_PENDING:
168      return "negotiating";
169    case CARRIER_OK:
170      return "established";
171  }
172
173  return "disconnected";
174}
175
176static void
177ether_device2iov(struct device *d, struct iovec *iov, int *niov,
178                 int maxiov, int *auxfd, int *nauxfd)
179{
180  struct etherdevice *dev = device2ether(d);
181  int sz = physical_MaxDeviceSize();
182
183  iov[*niov].iov_base = realloc(d, sz);
184  if (iov[*niov].iov_base == NULL) {
185    log_Printf(LogALERT, "Failed to allocate memory: %d\n", sz);
186    AbortProgram(EX_OSERR);
187  }
188  iov[*niov].iov_len = sz;
189  (*niov)++;
190
191  if (dev->cs >= 0) {
192    *auxfd = dev->cs;
193    (*nauxfd)++;
194  }
195}
196
197static void
198ether_MessageIn(struct etherdevice *dev)
199{
200  char msgbuf[sizeof(struct ng_mesg) + sizeof(struct ngpppoe_sts)];
201  struct ng_mesg *rep = (struct ng_mesg *)msgbuf;
202  struct ngpppoe_sts *sts = (struct ngpppoe_sts *)(msgbuf + sizeof *rep);
203  char unknown[14];
204  const char *msg;
205  struct timeval t;
206  fd_set *r;
207  int ret;
208
209  if (dev->cs < 0)
210    return;
211
212  if ((r = mkfdset()) == NULL) {
213    log_Printf(LogERROR, "DoLoop: Cannot create fd_set\n");
214    return;
215  }
216  zerofdset(r);
217  FD_SET(dev->cs, r);
218  t.tv_sec = t.tv_usec = 0;
219  ret = select(dev->cs + 1, r, NULL, NULL, &t);
220  free(r);
221
222  if (ret <= 0)
223    return;
224
225  if (NgRecvMsg(dev->cs, rep, sizeof msgbuf, NULL) < 0)
226    return;
227
228  if (rep->header.version != NG_VERSION) {
229    log_Printf(LogWARN, "%ld: Unexpected netgraph version, expected %ld\n",
230               (long)rep->header.version, (long)NG_VERSION);
231    return;
232  }
233
234  if (rep->header.typecookie != NGM_PPPOE_COOKIE) {
235    log_Printf(LogWARN, "%ld: Unexpected netgraph cookie, expected %ld\n",
236               (long)rep->header.typecookie, (long)NGM_PPPOE_COOKIE);
237    return;
238  }
239
240  switch (rep->header.cmd) {
241    case NGM_PPPOE_SET_FLAG:	msg = "SET_FLAG";	break;
242    case NGM_PPPOE_CONNECT:	msg = "CONNECT";	break;
243    case NGM_PPPOE_LISTEN:	msg = "LISTEN";		break;
244    case NGM_PPPOE_OFFER:	msg = "OFFER";		break;
245    case NGM_PPPOE_SUCCESS:	msg = "SUCCESS";	break;
246    case NGM_PPPOE_FAIL:	msg = "FAIL";		break;
247    case NGM_PPPOE_CLOSE:	msg = "CLOSE";		break;
248    case NGM_PPPOE_GET_STATUS:	msg = "GET_STATUS";	break;
249    default:
250      snprintf(unknown, sizeof unknown, "<%d>", (int)rep->header.cmd);
251      msg = unknown;
252      break;
253  }
254
255  log_Printf(LogPHASE, "Received NGM_PPPOE_%s (hook \"%s\")\n", msg, sts->hook);
256
257  switch (rep->header.cmd) {
258    case NGM_PPPOE_SUCCESS:
259      dev->connected = CARRIER_OK;
260      break;
261    case NGM_PPPOE_FAIL:
262    case NGM_PPPOE_CLOSE:
263      dev->connected = CARRIER_LOST;
264      break;
265  }
266}
267
268static int
269ether_AwaitCarrier(struct physical *p)
270{
271  struct etherdevice *dev = device2ether(p->handler);
272
273  if (dev->connected != CARRIER_OK && !dev->timeout--)
274    dev->connected = CARRIER_LOST;
275  else if (dev->connected == CARRIER_PENDING)
276    ether_MessageIn(dev);
277
278  return dev->connected;
279}
280
281static const struct device baseetherdevice = {
282  ETHER_DEVICE,
283  "ether",
284  { CD_REQUIRED, DEF_ETHERCDDELAY },
285  ether_AwaitCarrier,
286  ether_RemoveFromSet,
287  NULL,
288  NULL,
289  NULL,
290  NULL,
291  ether_Free,
292  ether_Read,
293  ether_Write,
294  ether_device2iov,
295  NULL,
296  ether_OpenInfo
297};
298
299struct device *
300ether_iov2device(int type, struct physical *p, struct iovec *iov, int *niov,
301                 int maxiov, int *auxfd, int *nauxfd)
302{
303  if (type == ETHER_DEVICE) {
304    struct etherdevice *dev = (struct etherdevice *)iov[(*niov)++].iov_base;
305
306    dev = realloc(dev, sizeof *dev);	/* Reduce to the correct size */
307    if (dev == NULL) {
308      log_Printf(LogALERT, "Failed to allocate memory: %d\n",
309                 (int)(sizeof *dev));
310      AbortProgram(EX_OSERR);
311    }
312
313    if (*nauxfd) {
314      dev->cs = *auxfd;
315      (*nauxfd)--;
316    } else
317      dev->cs = -1;
318
319    /* Refresh function pointers etc */
320    memcpy(&dev->dev, &baseetherdevice, sizeof dev->dev);
321
322    physical_SetupStack(p, dev->dev.name, PHYSICAL_FORCE_SYNCNOACF);
323    return &dev->dev;
324  }
325
326  return NULL;
327}
328
329static int
330ether_UpdateSet(struct fdescriptor *d, fd_set *r, fd_set *w, fd_set *e, int *n)
331{
332  struct physical *p = descriptor2physical(d);
333  struct etherdevice *dev = device2ether(p->handler);
334  int result;
335
336  if (r && dev->cs >= 0) {
337    FD_SET(dev->cs, r);
338    log_Printf(LogTIMER, "%s(ctrl): fdset(r) %d\n", p->link.name, dev->cs);
339    result = 1;
340  } else
341    result = 0;
342
343  result += physical_doUpdateSet(d, r, w, e, n, 0);
344
345  return result;
346}
347
348static int
349ether_IsSet(struct fdescriptor *d, const fd_set *fdset)
350{
351  struct physical *p = descriptor2physical(d);
352  struct etherdevice *dev = device2ether(p->handler);
353  int result;
354
355  result = dev->cs >= 0 && FD_ISSET(dev->cs, fdset);
356  result += physical_IsSet(d, fdset);
357
358  return result;
359}
360
361static void
362ether_DescriptorRead(struct fdescriptor *d, struct bundle *bundle,
363                     const fd_set *fdset)
364{
365  struct physical *p = descriptor2physical(d);
366  struct etherdevice *dev = device2ether(p->handler);
367
368  if (dev->cs >= 0 && FD_ISSET(dev->cs, fdset)) {
369    ether_MessageIn(dev);
370    if (dev->connected == CARRIER_LOST) {
371      log_Printf(LogPHASE, "%s: Device disconnected\n", p->link.name);
372      datalink_Down(p->dl, CLOSE_NORMAL);
373      return;
374    }
375  }
376
377  if (physical_IsSet(d, fdset))
378    physical_DescriptorRead(d, bundle, fdset);
379}
380
381static struct device *
382ether_Abandon(struct etherdevice *dev, struct physical *p)
383{
384  /* Abandon our node construction */
385  close(dev->cs);
386  close(p->fd);
387  p->fd = -2;	/* Nobody else need try.. */
388  free(dev);
389
390  return NULL;
391}
392
393struct device *
394ether_Create(struct physical *p)
395{
396  u_char rbuf[2048];
397  struct etherdevice *dev;
398  struct ng_mesg *resp;
399  const struct hooklist *hlist;
400  const struct nodeinfo *ninfo;
401  int f;
402
403  dev = NULL;
404  if (p->fd < 0 && !strncasecmp(p->name.full, NG_PPPOE_NODE_TYPE,
405                                PPPOE_NODE_TYPE_LEN) &&
406      p->name.full[PPPOE_NODE_TYPE_LEN] == ':') {
407    const struct linkinfo *nlink;
408    struct ngpppoe_init_data *data;
409    struct ngm_mkpeer mkp;
410    struct ngm_connect ngc;
411    const char *iface, *provider;
412    char *path, etherid[12];
413    int ifacelen, providerlen;
414    char connectpath[sizeof dev->hook + 2];	/* .:<hook> */
415
416    p->fd--;				/* We own the device - change fd */
417
418#if defined(__FreeBSD__) && !defined(NOKLDLOAD)
419    if (modfind("netgraph") == -1) {
420      log_Printf(LogWARN, "Netgraph is not built into the kernel\n");
421      return NULL;
422    }
423
424    if (modfind("ng_ether") == -1 && ID0kldload("ng_ether") == -1)
425      /*
426       * Don't treat this as an error as older kernels have this stuff
427       * built in as part of the netgraph node itself.
428       */
429      log_Printf(LogWARN, "kldload: ng_ether: %s\n", strerror(errno));
430
431    if (modfind("ng_socket") == -1 && ID0kldload("ng_socket") == -1) {
432      log_Printf(LogWARN, "kldload: ng_socket: %s\n", strerror(errno));
433      return NULL;
434    }
435#endif
436
437    if ((dev = malloc(sizeof *dev)) == NULL)
438      return NULL;
439
440    iface = p->name.full + PPPOE_NODE_TYPE_LEN + 1;
441
442    provider = strchr(iface, ':');
443    if (provider) {
444      ifacelen = provider - iface;
445      provider++;
446      providerlen = strlen(provider);
447    } else {
448      ifacelen = strlen(iface);
449      provider = "";
450      providerlen = 0;
451    }
452
453    /*
454     * We're going to do this (where tunN is our tunnel device):
455     *
456     * .---------.
457     * |  ether  |
458     * | <iface> |                         dev->cs
459     * `---------'                           |
460     *  (orphan)                     p->fd   |
461     *     |                           |     |
462     *     |                           |     |
463     * (ethernet)                      |     |
464     * .---------.                  .-----------.
465     * |  pppoe  |                  |  socket   |
466     * | <iface> |(tunN)<---->(tunN)| <unnamed> |
467     * `---------                   `-----------'
468     *   (tunX)
469     *     ^
470     *     |
471     *     `--->(tunX)
472     */
473
474    /* Create a socket node */
475    if (ID0NgMkSockNode(NULL, &dev->cs, &p->fd) == -1) {
476      log_Printf(LogWARN, "Cannot create netgraph socket node: %s\n",
477                 strerror(errno));
478      free(dev);
479      return NULL;
480    }
481
482    /*
483     * Ask for a list of hooks attached to the "ether" node.  This node should
484     * magically exist as a way of hooking stuff onto an ethernet device
485     */
486    path = (char *)alloca(ifacelen + 2);
487    sprintf(path, "%.*s:", ifacelen, iface);
488    if (NgSendMsg(dev->cs, path, NGM_GENERIC_COOKIE, NGM_LISTHOOKS,
489                  NULL, 0) < 0) {
490      log_Printf(LogWARN, "%s Cannot send a netgraph message: %s\n",
491                 path, strerror(errno));
492      return ether_Abandon(dev, p);
493    }
494
495    /* Get our list back */
496    resp = (struct ng_mesg *)rbuf;
497    if (NgRecvMsg(dev->cs, resp, sizeof rbuf, NULL) < 0) {
498      log_Printf(LogWARN, "Cannot get netgraph response: %s\n",
499                 strerror(errno));
500      return ether_Abandon(dev, p);
501    }
502
503    hlist = (const struct hooklist *)resp->data;
504    ninfo = &hlist->nodeinfo;
505
506    /* Make sure we've got the right type of node */
507    if (strncmp(ninfo->type, NG_ETHER_NODE_TYPE,
508                sizeof NG_ETHER_NODE_TYPE - 1)) {
509      log_Printf(LogWARN, "%s Unexpected node type ``%s'' (wanted ``"
510                 NG_ETHER_NODE_TYPE "'')\n", path, ninfo->type);
511      return ether_Abandon(dev, p);
512    }
513
514    log_Printf(LogDEBUG, "List of netgraph node ``%s'' (id %x) hooks:\n",
515               path, ninfo->id);
516
517    /* look for a hook already attached.  */
518    for (f = 0; f < ninfo->hooks; f++) {
519      nlink = &hlist->link[f];
520
521      log_Printf(LogDEBUG, "  Found %s -> %s\n", nlink->ourhook,
522                 nlink->peerhook);
523
524      if (!strcmp(nlink->ourhook, NG_ETHER_HOOK_ORPHAN) ||
525          !strcmp(nlink->ourhook, NG_ETHER_HOOK_DIVERT)) {
526        /*
527         * Something is using the data coming out of this ``ether'' node.
528         * If it's a PPPoE node, we use that node, otherwise we complain that
529         * someone else is using the node.
530         */
531        if (!strcmp(nlink->nodeinfo.type, NG_PPPOE_NODE_TYPE))
532          /* Use this PPPoE node ! */
533          snprintf(ngc.path, sizeof ngc.path, "[%x]:", nlink->nodeinfo.id);
534        else {
535          log_Printf(LogWARN, "%s Node type ``%s'' is currently active\n",
536                     path, nlink->nodeinfo.type);
537          return ether_Abandon(dev, p);
538        }
539        break;
540      }
541    }
542
543    if (f == ninfo->hooks) {
544      /*
545       * Create a new ``PPPoE'' node connected to the ``ether'' node using
546       * the magic ``orphan'' and ``ethernet'' hooks
547       */
548      snprintf(mkp.type, sizeof mkp.type, "%s", NG_PPPOE_NODE_TYPE);
549      snprintf(mkp.ourhook, sizeof mkp.ourhook, "%s", NG_ETHER_HOOK_ORPHAN);
550      snprintf(mkp.peerhook, sizeof mkp.peerhook, "%s", NG_PPPOE_HOOK_ETHERNET);
551      snprintf(etherid, sizeof etherid, "[%x]:", ninfo->id);
552
553      log_Printf(LogDEBUG, "Creating PPPoE netgraph node %s%s -> %s\n",
554                 etherid, mkp.ourhook, mkp.peerhook);
555
556      if (NgSendMsg(dev->cs, etherid, NGM_GENERIC_COOKIE,
557                    NGM_MKPEER, &mkp, sizeof mkp) < 0) {
558        log_Printf(LogWARN, "%s Cannot create PPPoE netgraph node: %s\n",
559                   etherid, strerror(errno));
560        return ether_Abandon(dev, p);
561      }
562
563      snprintf(ngc.path, sizeof ngc.path, "%s%s", path, NG_ETHER_HOOK_ORPHAN);
564    }
565
566    snprintf(dev->hook, sizeof dev->hook, "%s%d",
567             TUN_NAME, p->dl->bundle->unit);
568
569    /*
570     * Connect the PPPoE node to our socket node.
571     * ngc.path has already been set up
572     */
573    snprintf(ngc.ourhook, sizeof ngc.ourhook, "%s", dev->hook);
574    memcpy(ngc.peerhook, ngc.ourhook, sizeof ngc.peerhook);
575
576    log_Printf(LogDEBUG, "Connecting netgraph socket .:%s -> %s:%s\n",
577               ngc.ourhook, ngc.path, ngc.peerhook);
578    if (NgSendMsg(dev->cs, ".:", NGM_GENERIC_COOKIE,
579                  NGM_CONNECT, &ngc, sizeof ngc) < 0) {
580      log_Printf(LogWARN, "Cannot connect PPPoE and socket netgraph "
581                 "nodes: %s\n", strerror(errno));
582      return ether_Abandon(dev, p);
583    }
584
585    /* And finally, request a connection to the given provider */
586
587    data = (struct ngpppoe_init_data *)alloca(sizeof *data + providerlen);
588    snprintf(data->hook, sizeof data->hook, "%s", dev->hook);
589    memcpy(data->data, provider, providerlen);
590    data->data_len = providerlen;
591
592    snprintf(connectpath, sizeof connectpath, ".:%s", dev->hook);
593    log_Printf(LogDEBUG, "Sending PPPOE_CONNECT to %s\n", connectpath);
594    if (NgSendMsg(dev->cs, connectpath, NGM_PPPOE_COOKIE,
595                  NGM_PPPOE_CONNECT, data, sizeof *data + providerlen) == -1) {
596      log_Printf(LogWARN, "``%s'': Cannot start netgraph node: %s\n",
597                 connectpath, strerror(errno));
598      return ether_Abandon(dev, p);
599    }
600
601    /* Hook things up so that we monitor dev->cs */
602    p->desc.UpdateSet = ether_UpdateSet;
603    p->desc.IsSet = ether_IsSet;
604    p->desc.Read = ether_DescriptorRead;
605
606    memcpy(&dev->dev, &baseetherdevice, sizeof dev->dev);
607    switch (p->cfg.cd.necessity) {
608      case CD_VARIABLE:
609        dev->dev.cd.delay = p->cfg.cd.delay;
610        break;
611      case CD_REQUIRED:
612        dev->dev.cd = p->cfg.cd;
613        break;
614      case CD_NOTREQUIRED:
615        log_Printf(LogWARN, "%s: Carrier must be set, using ``set cd %d!''\n",
616                   p->link.name, dev->dev.cd.delay);
617      case CD_DEFAULT:
618        break;
619    }
620
621    dev->timeout = dev->dev.cd.delay;
622    dev->connected = CARRIER_PENDING;
623
624  } else {
625    /* See if we're a netgraph socket */
626    struct sockaddr_ng ngsock;
627    struct sockaddr *sock = (struct sockaddr *)&ngsock;
628    int sz;
629
630    sz = sizeof ngsock;
631    if (getsockname(p->fd, sock, &sz) != -1 && sock->sa_family == AF_NETGRAPH) {
632      /*
633       * It's a netgraph node... We can't determine hook names etc, so we
634       * stay pretty impartial....
635       */
636      log_Printf(LogPHASE, "%s: Link is a netgraph node\n", p->link.name);
637
638      if ((dev = malloc(sizeof *dev)) == NULL) {
639        log_Printf(LogWARN, "%s: Cannot allocate an ether device: %s\n",
640                   p->link.name, strerror(errno));
641        return NULL;
642      }
643
644      memcpy(&dev->dev, &baseetherdevice, sizeof dev->dev);
645      dev->cs = -1;
646      dev->timeout = 0;
647      dev->connected = CARRIER_OK;
648      *dev->hook = '\0';
649    }
650  }
651
652  if (dev) {
653    physical_SetupStack(p, dev->dev.name, PHYSICAL_FORCE_SYNCNOACF);
654
655    /* Moan about (and fix) invalid LCP configurations */
656    if (p->link.lcp.cfg.mru > 1492) {
657      log_Printf(LogWARN, "%s: Reducing MRU to 1492\n", p->link.name);
658      p->link.lcp.cfg.mru = 1492;
659    }
660    if (p->dl->bundle->cfg.mtu > 1492) {
661      log_Printf(LogWARN, "%s: Reducing MTU to 1492\n", p->link.name);
662      p->dl->bundle->cfg.mtu = 1492;
663    }
664
665    return &dev->dev;
666  }
667
668  return NULL;
669}
670