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 MERCHANTABILITY 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  *
  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  */
  92 static struct {
  93   struct rt_msghdr hdr;
  94   struct sockaddr_inarp dst;
  95   struct sockaddr_dl hwa;
  96   char extra[128];
  97 } arpmsg;
  98
  99 static int
 100 arp_ProxySub(struct bundle *bundle, struct in_addr addr, int add)
 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(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
 147 int
 148 arp_SetProxy(struct bundle *bundle, struct in_addr addr)
 149 {
 150   return (arp_ProxySub(bundle, addr, 1));
 151 }
 152
 153 /*
 154  * arp_ClearProxy - Delete the proxy ARP entry for the peer.
 155  */
 156 int
 157 arp_ClearProxy(struct bundle *bundle, struct in_addr addr)
 158 {
 159   return (arp_ProxySub(bundle, addr, 0));
 160 }
 161
 162 #else                           /* RTM_VERSION */
 163
 164 /*
 165  * arp_SetProxy - Make a proxy ARP entry for the peer.
 166  */
 167 int
 168 arp_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(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  */
 204 int
 205 arp_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
 228 int
 229 arp_EtherAddr(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_alen,
 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 }