arp.c revision 80730 
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 * $FreeBSD: head/usr.sbin/ppp/arp.c 80730 2001-07-31 15:19:07Z brian $
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 <termios.h>
46#include <unistd.h>
47
48#include "layer.h"
49#include "mbuf.h"
50#include "log.h"
51#include "id.h"
52#include "timer.h"
53#include "fsm.h"
54#include "defs.h"
55#include "iplist.h"
56#include "throughput.h"
57#include "slcompress.h"
58#include "lqr.h"
59#include "hdlc.h"
60#include "ipcp.h"
61#include "filter.h"
62#include "descriptor.h"
63#include "lcp.h"
64#include "ccp.h"
65#include "link.h"
66#include "mp.h"
67#ifndef NORADIUS
68#include "radius.h"
69#endif
70#include "bundle.h"
71#include "iface.h"
72#include "arp.h"
73
74/*
75 * SET_SA_FAMILY - set the sa_family field of a struct sockaddr,
76 * if it exists.
77 */
78#define SET_SA_FAMILY(addr, family)		\
79    memset((char *) &(addr), '\0', sizeof(addr));	\
80    addr.sa_family = (family); 			\
81    addr.sa_len = sizeof(addr);
82
83
84#if RTM_VERSION >= 3
85
86/*
87 * arp_SetProxy - Make a proxy ARP entry for the peer.
88 */
89static struct {
90  struct rt_msghdr hdr;
91  struct sockaddr_inarp dst;
92  struct sockaddr_dl hwa;
93  char extra[128];
94} arpmsg;
95
96static int
97arp_ProxySub(struct bundle *bundle, struct in_addr addr, int add, int s)
98{
99  int routes;
100
101  /*
102   * Get the hardware address of an interface on the same subnet as our local
103   * address.
104   */
105
106  memset(&arpmsg, 0, sizeof arpmsg);
107  if (!arp_EtherAddr(s, addr, &arpmsg.hwa, 0)) {
108    log_Printf(LogWARN, "%s: Cannot determine ethernet address for proxy ARP\n",
109	       inet_ntoa(addr));
110    return 0;
111  }
112  routes = ID0socket(PF_ROUTE, SOCK_RAW, AF_INET);
113  if (routes < 0) {
114    log_Printf(LogERROR, "arp_SetProxy: opening routing socket: %s\n",
115	      strerror(errno));
116    return 0;
117  }
118  arpmsg.hdr.rtm_type = add ? RTM_ADD : RTM_DELETE;
119  arpmsg.hdr.rtm_flags = RTF_ANNOUNCE | RTF_HOST | RTF_STATIC;
120  arpmsg.hdr.rtm_version = RTM_VERSION;
121  arpmsg.hdr.rtm_seq = ++bundle->routing_seq;
122  arpmsg.hdr.rtm_addrs = RTA_DST | RTA_GATEWAY;
123  arpmsg.hdr.rtm_inits = RTV_EXPIRE;
124  arpmsg.dst.sin_len = sizeof(struct sockaddr_inarp);
125  arpmsg.dst.sin_family = AF_INET;
126  arpmsg.dst.sin_addr.s_addr = addr.s_addr;
127  arpmsg.dst.sin_other = SIN_PROXY;
128
129  arpmsg.hdr.rtm_msglen = (char *) &arpmsg.hwa - (char *) &arpmsg
130    + arpmsg.hwa.sdl_len;
131
132
133  if (write(routes, &arpmsg, arpmsg.hdr.rtm_msglen) < 0 &&
134      !(!add && errno == ESRCH)) {
135    log_Printf(LogERROR, "%s proxy arp entry %s: %s\n",
136	add ? "Add" : "Delete", inet_ntoa(addr), strerror(errno));
137    close(routes);
138    return 0;
139  }
140  close(routes);
141  return 1;
142}
143
144int
145arp_SetProxy(struct bundle *bundle, struct in_addr addr, int s)
146{
147  return (arp_ProxySub(bundle, addr, 1, s));
148}
149
150/*
151 * arp_ClearProxy - Delete the proxy ARP entry for the peer.
152 */
153int
154arp_ClearProxy(struct bundle *bundle, struct in_addr addr, int s)
155{
156  return (arp_ProxySub(bundle, addr, 0, s));
157}
158
159#else				/* RTM_VERSION */
160
161/*
162 * arp_SetProxy - Make a proxy ARP entry for the peer.
163 */
164int
165arp_SetProxy(struct bundle *bundle, struct in_addr addr, int s)
166{
167  struct arpreq arpreq;
168  struct {
169    struct sockaddr_dl sdl;
170    char space[128];
171  }      dls;
172
173  memset(&arpreq, '\0', sizeof arpreq);
174
175  /*
176   * Get the hardware address of an interface on the same subnet as our local
177   * address.
178   */
179  if (!arp_EtherAddr(s, addr, &dls.sdl, 1)) {
180    log_Printf(LOG_PHASE_BIT, "Cannot determine ethernet address for "
181               "proxy ARP\n");
182    return 0;
183  }
184  arpreq.arp_ha.sa_len = sizeof(struct sockaddr);
185  arpreq.arp_ha.sa_family = AF_UNSPEC;
186  memcpy(arpreq.arp_ha.sa_data, LLADDR(&dls.sdl), dls.sdl.sdl_alen);
187  SET_SA_FAMILY(arpreq.arp_pa, AF_INET);
188  ((struct sockaddr_in *)&arpreq.arp_pa)->sin_addr.s_addr = addr.s_addr;
189  arpreq.arp_flags = ATF_PERM | ATF_PUBL;
190  if (ID0ioctl(s, SIOCSARP, (caddr_t) & arpreq) < 0) {
191    log_Printf(LogERROR, "arp_SetProxy: ioctl(SIOCSARP): %s\n",
192               strerror(errno));
193    return 0;
194  }
195  return 1;
196}
197
198/*
199 * arp_ClearProxy - Delete the proxy ARP entry for the peer.
200 */
201int
202arp_ClearProxy(struct bundle *bundle, struct in_addr addr, int s)
203{
204  struct arpreq arpreq;
205
206  memset(&arpreq, '\0', sizeof arpreq);
207  SET_SA_FAMILY(arpreq.arp_pa, AF_INET);
208  ((struct sockaddr_in *)&arpreq.arp_pa)->sin_addr.s_addr = addr.s_addr;
209  if (ID0ioctl(s, SIOCDARP, (caddr_t) & arpreq) < 0) {
210    log_Printf(LogERROR, "arp_ClearProxy: ioctl(SIOCDARP): %s\n",
211               strerror(errno));
212    return 0;
213  }
214  return 1;
215}
216
217#endif				/* RTM_VERSION */
218
219
220/*
221 * arp_EtherAddr - get the hardware address of an interface on the
222 * the same subnet as ipaddr.
223 */
224
225int
226arp_EtherAddr(int s, struct in_addr ipaddr, struct sockaddr_dl *hwaddr,
227              int verbose)
228{
229  int mib[6], skip;
230  size_t needed;
231  char *buf, *ptr, *end;
232  struct if_msghdr *ifm;
233  struct ifa_msghdr *ifam;
234  struct sockaddr_dl *dl;
235  struct sockaddr *sa[RTAX_MAX];
236
237  mib[0] = CTL_NET;
238  mib[1] = PF_ROUTE;
239  mib[2] = 0;
240  mib[3] = 0;
241  mib[4] = NET_RT_IFLIST;
242  mib[5] = 0;
243
244  if (sysctl(mib, 6, NULL, &needed, NULL, 0) < 0) {
245    log_Printf(LogERROR, "arp_EtherAddr: sysctl: estimate: %s\n",
246              strerror(errno));
247    return 0;
248  }
249
250  if ((buf = malloc(needed)) == NULL)
251    return 0;
252
253  if (sysctl(mib, 6, buf, &needed, NULL, 0) < 0) {
254    free(buf);
255    return 0;
256  }
257  end = buf + needed;
258
259  ptr = buf;
260  while (ptr < end) {
261    ifm = (struct if_msghdr *)ptr;		/* On if_msghdr */
262    if (ifm->ifm_type != RTM_IFINFO)
263      break;
264    dl = (struct sockaddr_dl *)(ifm + 1);	/* Single _dl at end */
265    skip = (ifm->ifm_flags & (IFF_UP | IFF_BROADCAST | IFF_POINTOPOINT |
266            IFF_NOARP | IFF_LOOPBACK)) != (IFF_UP | IFF_BROADCAST);
267    ptr += ifm->ifm_msglen;			/* First ifa_msghdr */
268    while (ptr < end) {
269      ifam = (struct ifa_msghdr *)ptr;	/* Next ifa_msghdr (alias) */
270      if (ifam->ifam_type != RTM_NEWADDR)	/* finished ? */
271        break;
272      ptr += ifam->ifam_msglen;
273      if (skip || (ifam->ifam_addrs & (RTA_NETMASK|RTA_IFA)) !=
274          (RTA_NETMASK|RTA_IFA))
275        continue;
276      /* Found a candidate.  Do the addresses match ? */
277      if (log_IsKept(LogDEBUG) &&
278          ptr == (char *)ifm + ifm->ifm_msglen + ifam->ifam_msglen)
279        log_Printf(LogDEBUG, "%.*s interface is a candidate for proxy\n",
280                  dl->sdl_nlen, dl->sdl_data);
281
282      iface_ParseHdr(ifam, sa);
283
284      if (sa[RTAX_IFA]->sa_family == AF_INET) {
285        struct sockaddr_in *ifa, *netmask;
286
287        ifa = (struct sockaddr_in *)sa[RTAX_IFA];
288        netmask = (struct sockaddr_in *)sa[RTAX_NETMASK];
289
290        if (log_IsKept(LogDEBUG)) {
291          char a[16];
292
293          strncpy(a, inet_ntoa(netmask->sin_addr), sizeof a - 1);
294          a[sizeof a - 1] = '\0';
295          log_Printf(LogDEBUG, "Check addr %s, mask %s\n",
296                     inet_ntoa(ifa->sin_addr), a);
297        }
298
299        if ((ifa->sin_addr.s_addr & netmask->sin_addr.s_addr) ==
300            (ipaddr.s_addr & netmask->sin_addr.s_addr)) {
301          log_Printf(verbose ? LogPHASE : LogDEBUG,
302                     "Found interface %.*s for %s\n", dl->sdl_alen,
303                     dl->sdl_data, inet_ntoa(ipaddr));
304          memcpy(hwaddr, dl, dl->sdl_len);
305          free(buf);
306          return 1;
307        }
308      }
309    }
310  }
311  free(buf);
312
313  return 0;
314}
315