arp.c revision 46085 
1/*
2 * sys-bsd.c - System-dependent procedures for setting up
3 * PPP interfaces on bsd-4.4-ish systems (including 386BSD, NetBSD, etc.)
4 *
5 * Copyright (c) 1989 Carnegie Mellon University.
6 * All rights reserved.
7 *
8 * Redistribution and use in source and binary forms are permitted
9 * provided that the above copyright notice and this paragraph are
10 * duplicated in all such forms and that any documentation,
11 * advertising materials, and other materials related to such
12 * distribution and use acknowledge that the software was developed
13 * by Carnegie Mellon University.  The name of the
14 * University may not be used to endorse or promote products derived
15 * from this software without specific prior written permission.
16 * THIS SOFTWARE IS PROVIDED ``AS IS'' AND WITHOUT ANY EXPRESS OR
17 * IMPLIED WARRANTIES, INCLUDING, WITHOUT LIMITATION, THE IMPLIED
18 * WARRANTIES OF MERCHANTIBILITY AND FITNESS FOR A PARTICULAR PURPOSE.
19 *
20 * $Id: arp.c,v 1.32 1999/01/28 01:56:30 brian Exp $
21 *
22 */
23
24/*
25 * TODO:
26 */
27
28#include <sys/param.h>
29#include <sys/socket.h>
30#include <net/if.h>
31#include <net/route.h>
32#include <net/if_dl.h>
33#include <netinet/in.h>
34#include <netinet/if_ether.h>
35#include <arpa/inet.h>
36#include <netinet/in_systm.h>
37#include <netinet/ip.h>
38#include <sys/un.h>
39
40#include <errno.h>
41#include <stdio.h>
42#include <stdlib.h>
43#include <string.h>
44#include <sys/sysctl.h>
45#include <unistd.h>
46
47#include "mbuf.h"
48#include "log.h"
49#include "id.h"
50#include "timer.h"
51#include "fsm.h"
52#include "defs.h"
53#include "iplist.h"
54#include "throughput.h"
55#include "slcompress.h"
56#include "lqr.h"
57#include "hdlc.h"
58#include "ipcp.h"
59#include "filter.h"
60#include "descriptor.h"
61#include "lcp.h"
62#include "ccp.h"
63#include "link.h"
64#include "mp.h"
65#ifndef NORADIUS
66#include "radius.h"
67#endif
68#include "bundle.h"
69#include "arp.h"
70
71/*
72 * SET_SA_FAMILY - set the sa_family field of a struct sockaddr,
73 * if it exists.
74 */
75#define SET_SA_FAMILY(addr, family)		\
76    memset((char *) &(addr), '\0', sizeof(addr));	\
77    addr.sa_family = (family); 			\
78    addr.sa_len = sizeof(addr);
79
80
81#if RTM_VERSION >= 3
82
83/*
84 * arp_SetProxy - Make a proxy ARP entry for the peer.
85 */
86static struct {
87  struct rt_msghdr hdr;
88  struct sockaddr_inarp dst;
89  struct sockaddr_dl hwa;
90  char extra[128];
91} arpmsg;
92
93static int
94arp_ProxySub(struct bundle *bundle, struct in_addr addr, int add, int s)
95{
96  int routes;
97
98  /*
99   * Get the hardware address of an interface on the same subnet as our local
100   * address.
101   */
102
103  memset(&arpmsg, 0, sizeof arpmsg);
104  if (!get_ether_addr(s, addr, &arpmsg.hwa)) {
105    log_Printf(LogWARN, "%s: Cannot determine ethernet address for proxy ARP\n",
106	       inet_ntoa(addr));
107    return 0;
108  }
109  routes = ID0socket(PF_ROUTE, SOCK_RAW, AF_INET);
110  if (routes < 0) {
111    log_Printf(LogERROR, "arp_SetProxy: opening routing socket: %s\n",
112	      strerror(errno));
113    return 0;
114  }
115  arpmsg.hdr.rtm_type = add ? RTM_ADD : RTM_DELETE;
116  arpmsg.hdr.rtm_flags = RTF_ANNOUNCE | RTF_HOST | RTF_STATIC;
117  arpmsg.hdr.rtm_version = RTM_VERSION;
118  arpmsg.hdr.rtm_seq = ++bundle->routing_seq;
119  arpmsg.hdr.rtm_addrs = RTA_DST | RTA_GATEWAY;
120  arpmsg.hdr.rtm_inits = RTV_EXPIRE;
121  arpmsg.dst.sin_len = sizeof(struct sockaddr_inarp);
122  arpmsg.dst.sin_family = AF_INET;
123  arpmsg.dst.sin_addr.s_addr = addr.s_addr;
124  arpmsg.dst.sin_other = SIN_PROXY;
125
126  arpmsg.hdr.rtm_msglen = (char *) &arpmsg.hwa - (char *) &arpmsg
127    + arpmsg.hwa.sdl_len;
128
129
130  if (write(routes, &arpmsg, arpmsg.hdr.rtm_msglen) < 0 &&
131      !(!add && errno == ESRCH)) {
132    log_Printf(LogERROR, "%s proxy arp entry %s: %s\n",
133	add ? "Add" : "Delete", inet_ntoa(addr), strerror(errno));
134    close(routes);
135    return 0;
136  }
137  close(routes);
138  return 1;
139}
140
141int
142arp_SetProxy(struct bundle *bundle, struct in_addr addr, int s)
143{
144
145  return (arp_ProxySub(bundle, addr, 1, s));
146}
147
148/*
149 * arp_ClearProxy - Delete the proxy ARP entry for the peer.
150 */
151int
152arp_ClearProxy(struct bundle *bundle, struct in_addr addr, int s)
153{
154
155  return (arp_ProxySub(bundle, addr, 0, s));
156}
157
158#else				/* RTM_VERSION */
159
160/*
161 * arp_SetProxy - Make a proxy ARP entry for the peer.
162 */
163int
164arp_SetProxy(struct bundle *bundle, struct in_addr addr, int s)
165{
166  struct arpreq arpreq;
167  struct {
168    struct sockaddr_dl sdl;
169    char space[128];
170  }      dls;
171
172  memset(&arpreq, '\0', sizeof arpreq);
173
174  /*
175   * Get the hardware address of an interface on the same subnet as our local
176   * address.
177   */
178  if (!get_ether_addr(s, addr, &dls.sdl)) {
179    log_Printf(LOG_PHASE_BIT, "Cannot determine ethernet address for proxy ARP\n");
180    return 0;
181  }
182  arpreq.arp_ha.sa_len = sizeof(struct sockaddr);
183  arpreq.arp_ha.sa_family = AF_UNSPEC;
184  memcpy(arpreq.arp_ha.sa_data, LLADDR(&dls.sdl), dls.sdl.sdl_alen);
185  SET_SA_FAMILY(arpreq.arp_pa, AF_INET);
186  ((struct sockaddr_in *)&arpreq.arp_pa)->sin_addr.s_addr = addr.s_addr;
187  arpreq.arp_flags = ATF_PERM | ATF_PUBL;
188  if (ID0ioctl(s, SIOCSARP, (caddr_t) & arpreq) < 0) {
189    log_Printf(LogERROR, "arp_SetProxy: ioctl(SIOCSARP): %s\n",
190               strerror(errno));
191    return 0;
192  }
193  return 1;
194}
195
196/*
197 * arp_ClearProxy - Delete the proxy ARP entry for the peer.
198 */
199int
200arp_ClearProxy(struct bundle *bundle, struct in_addr addr, int s)
201{
202  struct arpreq arpreq;
203
204  memset(&arpreq, '\0', sizeof arpreq);
205  SET_SA_FAMILY(arpreq.arp_pa, AF_INET);
206  ((struct sockaddr_in *)&arpreq.arp_pa)->sin_addr.s_addr = addr.s_addr;
207  if (ID0ioctl(s, SIOCDARP, (caddr_t) & arpreq) < 0) {
208    log_Printf(LogERROR, "arp_ClearProxy: ioctl(SIOCDARP): %s\n",
209               strerror(errno));
210    return 0;
211  }
212  return 1;
213}
214
215#endif				/* RTM_VERSION */
216
217
218/*
219 * get_ether_addr - get the hardware address of an interface on the
220 * the same subnet as ipaddr.
221 */
222
223int
224get_ether_addr(int s, struct in_addr ipaddr, struct sockaddr_dl *hwaddr)
225{
226  int mib[6], sa_len, skip, b;
227  size_t needed;
228  char *buf, *ptr, *end;
229  struct if_msghdr *ifm;
230  struct ifa_msghdr *ifam;
231  struct sockaddr *sa;
232  struct sockaddr_dl *dl;
233  struct sockaddr_in *ifa, *mask;
234
235  mib[0] = CTL_NET;
236  mib[1] = PF_ROUTE;
237  mib[2] = 0;
238  mib[3] = 0;
239  mib[4] = NET_RT_IFLIST;
240  mib[5] = 0;
241
242  if (sysctl(mib, 6, NULL, &needed, NULL, 0) < 0) {
243    log_Printf(LogERROR, "get_ether_addr: sysctl: estimate: %s\n",
244              strerror(errno));
245    return 0;
246  }
247
248  if ((buf = malloc(needed)) == NULL)
249    return 0;
250
251  if (sysctl(mib, 6, buf, &needed, NULL, 0) < 0) {
252    free(buf);
253    return 0;
254  }
255  end = buf + needed;
256
257  ptr = buf;
258  while (ptr < end) {
259    ifm = (struct if_msghdr *)ptr;		/* On if_msghdr */
260    if (ifm->ifm_type != RTM_IFINFO)
261      break;
262    dl = (struct sockaddr_dl *)(ifm + 1);	/* Single _dl at end */
263    skip = (ifm->ifm_flags & (IFF_UP | IFF_BROADCAST | IFF_POINTOPOINT |
264            IFF_NOARP | IFF_LOOPBACK)) != (IFF_UP | IFF_BROADCAST);
265    ptr += ifm->ifm_msglen;			/* First ifa_msghdr */
266    while (ptr < end) {
267      ifam = (struct ifa_msghdr *)ptr;	/* Next ifa_msghdr (alias) */
268      if (ifam->ifam_type != RTM_NEWADDR)	/* finished ? */
269        break;
270      sa = (struct sockaddr *)(ifam+1);	/* pile of sa's at end */
271      ptr += ifam->ifam_msglen;
272      if (skip || (ifam->ifam_addrs & (RTA_NETMASK|RTA_IFA)) !=
273          (RTA_NETMASK|RTA_IFA))
274        continue;
275      /* Found a candidate.  Do the addresses match ? */
276      if (log_IsKept(LogDEBUG) &&
277          ptr == (char *)ifm + ifm->ifm_msglen + ifam->ifam_msglen)
278        log_Printf(LogDEBUG, "%.*s interface is a candidate for proxy\n",
279                  dl->sdl_nlen, dl->sdl_data);
280      b = 1;
281      ifa = mask = NULL;
282      while (b < (RTA_NETMASK|RTA_IFA) && sa < (struct sockaddr *)ptr) {
283        switch (b) {
284        case RTA_IFA:
285          ifa = (struct sockaddr_in *)sa;
286          break;
287        case RTA_NETMASK:
288          /*
289           * Careful here !  this sockaddr doesn't have sa_family set to
290           * AF_INET, and is only 8 bytes big !  I have no idea why !
291           */
292          mask = (struct sockaddr_in *)sa;
293          break;
294        }
295        if (ifam->ifam_addrs & b) {
296#define ALN sizeof(ifa->sin_addr.s_addr)
297          sa_len = sa->sa_len > 0 ? ((sa->sa_len-1)|(ALN-1))+1 : ALN;
298          sa = (struct sockaddr *)((char *)sa + sa_len);
299        }
300        b <<= 1;
301      }
302      if (log_IsKept(LogDEBUG)) {
303        char a[16];
304        strncpy(a, inet_ntoa(mask->sin_addr), sizeof a - 1);
305        a[sizeof a - 1] = '\0';
306        log_Printf(LogDEBUG, "Check addr %s, mask %s\n",
307                  inet_ntoa(ifa->sin_addr), a);
308      }
309      if (ifa->sin_family == AF_INET &&
310          (ifa->sin_addr.s_addr & mask->sin_addr.s_addr) ==
311          (ipaddr.s_addr & mask->sin_addr.s_addr)) {
312        log_Printf(LogPHASE, "Found interface %.*s for %s\n",
313                  dl->sdl_alen, dl->sdl_data, inet_ntoa(ipaddr));
314        memcpy(hwaddr, dl, dl->sdl_len);
315        free(buf);
316        return 1;
317      }
318    }
319  }
320  free(buf);
321
322  return 0;
323}
324