usr.sbin/ppp/arp.c

   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: src/usr.sbin/ppp/arp.c,v 1.37.2.3 2002/09/01 02:12:22 brian Exp $
  21  * $DragonFly: src/usr.sbin/ppp/arp.c,v 1.2 2003/06/17 04:30:00 dillon Exp $
  22  *
  23  */
  24
  25 /*
  26  * TODO:
  27  */
  28
  29 #include <sys/param.h>
  30 #include <sys/socket.h>
  31 #include <net/if.h>
  32 #include <net/route.h>
  33 #include <net/if_dl.h>
  34 #include <netinet/in.h>
  35 #include <netinet/if_ether.h>
  36 #include <arpa/inet.h>
  37 #include <netinet/in_systm.h>
  38 #include <netinet/ip.h>
  39 #include <sys/un.h>
  40
  41 #include <errno.h>
  42 #include <stdio.h>
  43 #include <stdlib.h>
  44 #include <string.h>
  45 #include <sys/sysctl.h>
  46 #include <termios.h>
  47 #include <unistd.h>
  48
  49 #include "layer.h"
  50 #include "mbuf.h"
  51 #include "log.h"
  52 #include "id.h"
  53 #include "timer.h"
  54 #include "fsm.h"
  55 #include "defs.h"
  56 #include "iplist.h"
  57 #include "throughput.h"
  58 #include "slcompress.h"
  59 #include "lqr.h"
  60 #include "hdlc.h"
  61 #include "ncpaddr.h"
  62 #include "ipcp.h"
  63 #include "ipv6cp.h"
  64 #include "descriptor.h"
  65 #include "lcp.h"
  66 #include "ccp.h"
  67 #include "link.h"
  68 #include "mp.h"
  69 #include "ncp.h"
  70 #include "filter.h"
  71 #ifndef NORADIUS
  72 #include "radius.h"
  73 #endif
  74 #include "bundle.h"
  75 #include "iface.h"
  76 #include "arp.h"
  77
  78 /*
  79  * SET_SA_FAMILY - set the sa_family field of a struct sockaddr,
  80  * if it exists.
  81  */
  82 #define SET_SA_FAMILY(addr, family)             \
  83     memset((char *) &(addr), '\0', sizeof(addr));       \
  84     addr.sa_family = (family);                  \
  85     addr.sa_len = sizeof(addr);
  86
  87
  88 #if RTM_VERSION >= 3
  89
  90 /*
  91  * arp_SetProxy - Make a proxy ARP entry for the peer.
  92  */
  93 static struct {
  94   struct rt_msghdr hdr;
  95   struct sockaddr_inarp dst;
  96   struct sockaddr_dl hwa;
  97   char extra[128];
  98 } arpmsg;
  99
 100 static int
 101 arp_ProxySub(struct bundle *bundle, struct in_addr addr, int add)
 102 {
 103   int routes;
 104
 105   /*
 106    * Get the hardware address of an interface on the same subnet as our local
 107    * address.
 108    */
 109
 110   memset(&arpmsg, 0, sizeof arpmsg);
 111   if (!arp_EtherAddr(addr, &arpmsg.hwa, 0)) {
 112     log_Printf(LogWARN, "%s: Cannot determine ethernet address for proxy ARP\n",
 113                inet_ntoa(addr));
 114     return 0;
 115   }
 116   routes = ID0socket(PF_ROUTE, SOCK_RAW, AF_INET);
 117   if (routes < 0) {
 118     log_Printf(LogERROR, "arp_SetProxy: opening routing socket: %s\n",
 119               strerror(errno));
 120     return 0;
 121   }
 122   arpmsg.hdr.rtm_type = add ? RTM_ADD : RTM_DELETE;
 123   arpmsg.hdr.rtm_flags = RTF_ANNOUNCE | RTF_HOST | RTF_STATIC;
 124   arpmsg.hdr.rtm_version = RTM_VERSION;
 125   arpmsg.hdr.rtm_seq = ++bundle->routing_seq;
 126   arpmsg.hdr.rtm_addrs = RTA_DST | RTA_GATEWAY;
 127   arpmsg.hdr.rtm_inits = RTV_EXPIRE;
 128   arpmsg.dst.sin_len = sizeof(struct sockaddr_inarp);
 129   arpmsg.dst.sin_family = AF_INET;
 130   arpmsg.dst.sin_addr.s_addr = addr.s_addr;
 131   arpmsg.dst.sin_other = SIN_PROXY;
 132
 133   arpmsg.hdr.rtm_msglen = (char *) &arpmsg.hwa - (char *) &arpmsg
 134     + arpmsg.hwa.sdl_len;
 135
 136
 137   if (ID0write(routes, &arpmsg, arpmsg.hdr.rtm_msglen) < 0 &&
 138       !(!add && errno == ESRCH)) {
 139     log_Printf(LogERROR, "%s proxy arp entry %s: %s\n",
 140         add ? "Add" : "Delete", inet_ntoa(addr), strerror(errno));
 141     close(routes);
 142     return 0;
 143   }
 144   close(routes);
 145   return 1;
 146 }
 147
 148 int
 149 arp_SetProxy(struct bundle *bundle, struct in_addr addr)
 150 {
 151   return (arp_ProxySub(bundle, addr, 1));
 152 }
 153
 154 /*
 155  * arp_ClearProxy - Delete the proxy ARP entry for the peer.
 156  */
 157 int
 158 arp_ClearProxy(struct bundle *bundle, struct in_addr addr)
 159 {
 160   return (arp_ProxySub(bundle, addr, 0));
 161 }
 162
 163 #else                           /* RTM_VERSION */
 164
 165 /*
 166  * arp_SetProxy - Make a proxy ARP entry for the peer.
 167  */
 168 int
 169 arp_SetProxy(struct bundle *bundle, struct in_addr addr, int s)
 170 {
 171   struct arpreq arpreq;
 172   struct {
 173     struct sockaddr_dl sdl;
 174     char space[128];
 175   }      dls;
 176
 177   memset(&arpreq, '\0', sizeof arpreq);
 178
 179   /*
 180    * Get the hardware address of an interface on the same subnet as our local
 181    * address.
 182    */
 183   if (!arp_EtherAddr(addr, &dls.sdl, 1)) {
 184     log_Printf(LOG_PHASE_BIT, "Cannot determine ethernet address for "
 185                "proxy ARP\n");
 186     return 0;
 187   }
 188   arpreq.arp_ha.sa_len = sizeof(struct sockaddr);
 189   arpreq.arp_ha.sa_family = AF_UNSPEC;
 190   memcpy(arpreq.arp_ha.sa_data, LLADDR(&dls.sdl), dls.sdl.sdl_alen);
 191   SET_SA_FAMILY(arpreq.arp_pa, AF_INET);
 192   ((struct sockaddr_in *)&arpreq.arp_pa)->sin_addr.s_addr = addr.s_addr;
 193   arpreq.arp_flags = ATF_PERM | ATF_PUBL;
 194   if (ID0ioctl(s, SIOCSARP, (caddr_t) & arpreq) < 0) {
 195     log_Printf(LogERROR, "arp_SetProxy: ioctl(SIOCSARP): %s\n",
 196                strerror(errno));
 197     return 0;
 198   }
 199   return 1;
 200 }
 201
 202 /*
 203  * arp_ClearProxy - Delete the proxy ARP entry for the peer.
 204  */
 205 int
 206 arp_ClearProxy(struct bundle *bundle, struct in_addr addr, int s)
 207 {
 208   struct arpreq arpreq;
 209
 210   memset(&arpreq, '\0', sizeof arpreq);
 211   SET_SA_FAMILY(arpreq.arp_pa, AF_INET);
 212   ((struct sockaddr_in *)&arpreq.arp_pa)->sin_addr.s_addr = addr.s_addr;
 213   if (ID0ioctl(s, SIOCDARP, (caddr_t) & arpreq) < 0) {
 214     log_Printf(LogERROR, "arp_ClearProxy: ioctl(SIOCDARP): %s\n",
 215                strerror(errno));
 216     return 0;
 217   }
 218   return 1;
 219 }
 220
 221 #endif                          /* RTM_VERSION */
 222
 223
 224 /*
 225  * arp_EtherAddr - get the hardware address of an interface on the
 226  * the same subnet as ipaddr.
 227  */
 228
 229 int
 230 arp_EtherAddr(struct in_addr ipaddr, struct sockaddr_dl *hwaddr,
 231               int verbose)
 232 {
 233   int mib[6], skip;
 234   size_t needed;
 235   char *buf, *ptr, *end;
 236   struct if_msghdr *ifm;
 237   struct ifa_msghdr *ifam;
 238   struct sockaddr_dl *dl;
 239   struct sockaddr *sa[RTAX_MAX];
 240
 241   mib[0] = CTL_NET;
 242   mib[1] = PF_ROUTE;
 243   mib[2] = 0;
 244   mib[3] = 0;
 245   mib[4] = NET_RT_IFLIST;
 246   mib[5] = 0;
 247
 248   if (sysctl(mib, 6, NULL, &needed, NULL, 0) < 0) {
 249     log_Printf(LogERROR, "arp_EtherAddr: sysctl: estimate: %s\n",
 250               strerror(errno));
 251     return 0;
 252   }
 253
 254   if ((buf = malloc(needed)) == NULL)
 255     return 0;
 256
 257   if (sysctl(mib, 6, buf, &needed, NULL, 0) < 0) {
 258     free(buf);
 259     return 0;
 260   }
 261   end = buf + needed;
 262
 263   ptr = buf;
 264   while (ptr < end) {
 265     ifm = (struct if_msghdr *)ptr;              /* On if_msghdr */
 266     if (ifm->ifm_type != RTM_IFINFO)
 267       break;
 268     dl = (struct sockaddr_dl *)(ifm + 1);       /* Single _dl at end */
 269     skip = (ifm->ifm_flags & (IFF_UP | IFF_BROADCAST | IFF_POINTOPOINT |
 270             IFF_NOARP | IFF_LOOPBACK)) != (IFF_UP | IFF_BROADCAST);
 271     ptr += ifm->ifm_msglen;                     /* First ifa_msghdr */
 272     while (ptr < end) {
 273       ifam = (struct ifa_msghdr *)ptr;  /* Next ifa_msghdr (alias) */
 274       if (ifam->ifam_type != RTM_NEWADDR)       /* finished ? */
 275         break;
 276       ptr += ifam->ifam_msglen;
 277       if (skip || (ifam->ifam_addrs & (RTA_NETMASK|RTA_IFA)) !=
 278           (RTA_NETMASK|RTA_IFA))
 279         continue;
 280       /* Found a candidate.  Do the addresses match ? */
 281       if (log_IsKept(LogDEBUG) &&
 282           ptr == (char *)ifm + ifm->ifm_msglen + ifam->ifam_msglen)
 283         log_Printf(LogDEBUG, "%.*s interface is a candidate for proxy\n",
 284                   dl->sdl_nlen, dl->sdl_data);
 285
 286       iface_ParseHdr(ifam, sa);
 287
 288       if (sa[RTAX_IFA]->sa_family == AF_INET) {
 289         struct sockaddr_in *ifa, *netmask;
 290
 291         ifa = (struct sockaddr_in *)sa[RTAX_IFA];
 292         netmask = (struct sockaddr_in *)sa[RTAX_NETMASK];
 293
 294         if (log_IsKept(LogDEBUG)) {
 295           char a[16];
 296
 297           strncpy(a, inet_ntoa(netmask->sin_addr), sizeof a - 1);
 298           a[sizeof a - 1] = '\0';
 299           log_Printf(LogDEBUG, "Check addr %s, mask %s\n",
 300                      inet_ntoa(ifa->sin_addr), a);
 301         }
 302
 303         if ((ifa->sin_addr.s_addr & netmask->sin_addr.s_addr) ==
 304             (ipaddr.s_addr & netmask->sin_addr.s_addr)) {
 305           log_Printf(verbose ? LogPHASE : LogDEBUG,
 306                      "Found interface %.*s for %s\n", dl->sdl_alen,
 307                      dl->sdl_data, inet_ntoa(ipaddr));
 308           memcpy(hwaddr, dl, dl->sdl_len);
 309           free(buf);
 310           return 1;
 311         }
 312       }
 313     }
 314   }
 315   free(buf);
 316
 317   return 0;
 318 }