arp.c revision 124815 
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 124815 2004-01-21 22:00:50Z brooks $
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 "ncpaddr.h"
61#include "ipcp.h"
62#include "ipv6cp.h"
63#include "descriptor.h"
64#include "lcp.h"
65#include "ccp.h"
66#include "link.h"
67#include "mp.h"
68#include "ncp.h"
69#include "filter.h"
70#ifndef NORADIUS
71#include "radius.h"
72#endif
73#include "bundle.h"
74#include "iface.h"
75#include "arp.h"
76
77/*
78 * SET_SA_FAMILY - set the sa_family field of a struct sockaddr,
79 * if it exists.
80 */
81#define SET_SA_FAMILY(addr, family)		\
82    memset((char *) &(addr), '\0', sizeof(addr));	\
83    addr.sa_family = (family); 			\
84    addr.sa_len = sizeof(addr);
85
86
87#if RTM_VERSION >= 3
88
89/*
90 * arp_SetProxy - Make a proxy ARP entry for the peer.
91 */
92static struct {
93  struct rt_msghdr hdr;
94  struct sockaddr_inarp dst;
95  struct sockaddr_dl hwa;
96  char extra[128];
97} arpmsg;
98
99static int
100arp_ProxySub(struct bundle *bundle, struct in_addr addr, int add, int s)
101{
102  int routes;
103
104  /*
105   * Get the hardware address of an interface on the same subnet as our local
106   * address.
107   */
108
109  memset(&arpmsg, 0, sizeof arpmsg);
110  if (!arp_EtherAddr(s, addr, &arpmsg.hwa, 0)) {
111    log_Printf(LogWARN, "%s: Cannot determine ethernet address for proxy ARP\n",
112	       inet_ntoa(addr));
113    return 0;
114  }
115  routes = ID0socket(PF_ROUTE, SOCK_RAW, AF_INET);
116  if (routes < 0) {
117    log_Printf(LogERROR, "arp_SetProxy: opening routing socket: %s\n",
118	      strerror(errno));
119    return 0;
120  }
121  arpmsg.hdr.rtm_type = add ? RTM_ADD : RTM_DELETE;
122  arpmsg.hdr.rtm_flags = RTF_ANNOUNCE | RTF_HOST | RTF_STATIC;
123  arpmsg.hdr.rtm_version = RTM_VERSION;
124  arpmsg.hdr.rtm_seq = ++bundle->routing_seq;
125  arpmsg.hdr.rtm_addrs = RTA_DST | RTA_GATEWAY;
126  arpmsg.hdr.rtm_inits = RTV_EXPIRE;
127  arpmsg.dst.sin_len = sizeof(struct sockaddr_inarp);
128  arpmsg.dst.sin_family = AF_INET;
129  arpmsg.dst.sin_addr.s_addr = addr.s_addr;
130  arpmsg.dst.sin_other = SIN_PROXY;
131
132  arpmsg.hdr.rtm_msglen = (char *) &arpmsg.hwa - (char *) &arpmsg
133    + arpmsg.hwa.sdl_len;
134
135
136  if (ID0write(routes, &arpmsg, arpmsg.hdr.rtm_msglen) < 0 &&
137      !(!add && errno == ESRCH)) {
138    log_Printf(LogERROR, "%s proxy arp entry %s: %s\n",
139	add ? "Add" : "Delete", inet_ntoa(addr), strerror(errno));
140    close(routes);
141    return 0;
142  }
143  close(routes);
144  return 1;
145}
146
147int
148arp_SetProxy(struct bundle *bundle, struct in_addr addr, int s)
149{
150  return (arp_ProxySub(bundle, addr, 1, s));
151}
152
153/*
154 * arp_ClearProxy - Delete the proxy ARP entry for the peer.
155 */
156int
157arp_ClearProxy(struct bundle *bundle, struct in_addr addr, int s)
158{
159  return (arp_ProxySub(bundle, addr, 0, s));
160}
161
162#else				/* RTM_VERSION */
163
164/*
165 * arp_SetProxy - Make a proxy ARP entry for the peer.
166 */
167int
168arp_SetProxy(struct bundle *bundle, struct in_addr addr, int s)
169{
170  struct arpreq arpreq;
171  struct {
172    struct sockaddr_dl sdl;
173    char space[128];
174  }      dls;
175
176  memset(&arpreq, '\0', sizeof arpreq);
177
178  /*
179   * Get the hardware address of an interface on the same subnet as our local
180   * address.
181   */
182  if (!arp_EtherAddr(s, addr, &dls.sdl, 1)) {
183    log_Printf(LOG_PHASE_BIT, "Cannot determine ethernet address for "
184               "proxy ARP\n");
185    return 0;
186  }
187  arpreq.arp_ha.sa_len = sizeof(struct sockaddr);
188  arpreq.arp_ha.sa_family = AF_UNSPEC;
189  memcpy(arpreq.arp_ha.sa_data, LLADDR(&dls.sdl), dls.sdl.sdl_alen);
190  SET_SA_FAMILY(arpreq.arp_pa, AF_INET);
191  ((struct sockaddr_in *)&arpreq.arp_pa)->sin_addr.s_addr = addr.s_addr;
192  arpreq.arp_flags = ATF_PERM | ATF_PUBL;
193  if (ID0ioctl(s, SIOCSARP, (caddr_t) & arpreq) < 0) {
194    log_Printf(LogERROR, "arp_SetProxy: ioctl(SIOCSARP): %s\n",
195               strerror(errno));
196    return 0;
197  }
198  return 1;
199}
200
201/*
202 * arp_ClearProxy - Delete the proxy ARP entry for the peer.
203 */
204int
205arp_ClearProxy(struct bundle *bundle, struct in_addr addr, int s)
206{
207  struct arpreq arpreq;
208
209  memset(&arpreq, '\0', sizeof arpreq);
210  SET_SA_FAMILY(arpreq.arp_pa, AF_INET);
211  ((struct sockaddr_in *)&arpreq.arp_pa)->sin_addr.s_addr = addr.s_addr;
212  if (ID0ioctl(s, SIOCDARP, (caddr_t) & arpreq) < 0) {
213    log_Printf(LogERROR, "arp_ClearProxy: ioctl(SIOCDARP): %s\n",
214               strerror(errno));
215    return 0;
216  }
217  return 1;
218}
219
220#endif				/* RTM_VERSION */
221
222
223/*
224 * arp_EtherAddr - get the hardware address of an interface on the
225 * the same subnet as ipaddr.
226 */
227
228int
229arp_EtherAddr(int s, struct in_addr ipaddr, struct sockaddr_dl *hwaddr,
230              int verbose)
231{
232  int mib[6], skip;
233  size_t needed;
234  char *buf, *ptr, *end;
235  struct if_msghdr *ifm;
236  struct ifa_msghdr *ifam;
237  struct sockaddr_dl *dl;
238  struct sockaddr *sa[RTAX_MAX];
239
240  mib[0] = CTL_NET;
241  mib[1] = PF_ROUTE;
242  mib[2] = 0;
243  mib[3] = 0;
244  mib[4] = NET_RT_IFLIST;
245  mib[5] = 0;
246
247  if (sysctl(mib, 6, NULL, &needed, NULL, 0) < 0) {
248    log_Printf(LogERROR, "arp_EtherAddr: sysctl: estimate: %s\n",
249              strerror(errno));
250    return 0;
251  }
252
253  if ((buf = malloc(needed)) == NULL)
254    return 0;
255
256  if (sysctl(mib, 6, buf, &needed, NULL, 0) < 0) {
257    free(buf);
258    return 0;
259  }
260  end = buf + needed;
261
262  ptr = buf;
263  while (ptr < end) {
264    ifm = (struct if_msghdr *)ptr;		/* On if_msghdr */
265    if (ifm->ifm_type != RTM_IFINFO)
266      break;
267    dl = (struct sockaddr_dl *)(ifm + 1);	/* Single _dl at end */
268    skip = (ifm->ifm_flags & (IFF_UP | IFF_BROADCAST | IFF_POINTOPOINT |
269            IFF_NOARP | IFF_LOOPBACK)) != (IFF_UP | IFF_BROADCAST);
270    ptr += ifm->ifm_msglen;			/* First ifa_msghdr */
271    while (ptr < end) {
272      ifam = (struct ifa_msghdr *)ptr;	/* Next ifa_msghdr (alias) */
273      if (ifam->ifam_type != RTM_NEWADDR)	/* finished ? */
274        break;
275      ptr += ifam->ifam_msglen;
276      if (skip || (ifam->ifam_addrs & (RTA_NETMASK|RTA_IFA)) !=
277          (RTA_NETMASK|RTA_IFA))
278        continue;
279      /* Found a candidate.  Do the addresses match ? */
280      if (log_IsKept(LogDEBUG) &&
281          ptr == (char *)ifm + ifm->ifm_msglen + ifam->ifam_msglen)
282        log_Printf(LogDEBUG, "%.*s interface is a candidate for proxy\n",
283                  dl->sdl_nlen, dl->sdl_data);
284
285      iface_ParseHdr(ifam, sa);
286
287      if (sa[RTAX_IFA]->sa_family == AF_INET) {
288        struct sockaddr_in *ifa, *netmask;
289
290        ifa = (struct sockaddr_in *)sa[RTAX_IFA];
291        netmask = (struct sockaddr_in *)sa[RTAX_NETMASK];
292
293        if (log_IsKept(LogDEBUG)) {
294          char a[16];
295
296          strncpy(a, inet_ntoa(netmask->sin_addr), sizeof a - 1);
297          a[sizeof a - 1] = '\0';
298          log_Printf(LogDEBUG, "Check addr %s, mask %s\n",
299                     inet_ntoa(ifa->sin_addr), a);
300        }
301
302        if ((ifa->sin_addr.s_addr & netmask->sin_addr.s_addr) ==
303            (ipaddr.s_addr & netmask->sin_addr.s_addr)) {
304          log_Printf(verbose ? LogPHASE : LogDEBUG,
305                     "Found interface %.*s for %s\n", dl->sdl_nlen,
306                     dl->sdl_data, inet_ntoa(ipaddr));
307          memcpy(hwaddr, dl, dl->sdl_len);
308          free(buf);
309          return 1;
310        }
311      }
312    }
313  }
314  free(buf);
315
316  return 0;
317}
318