usr.sbin/rarpd/mkarp.c

   1 /*      $NetBSD: mkarp.c,v 1.7 2008/07/21 13:36:59 lukem Exp $ */
   2
   3 /*
   4  * Copyright (c) 1984, 1993
   5  *      The Regents of the University of California.  All rights reserved.
   6  *
   7  * This code is derived from software contributed to Berkeley by
   8  * Sun Microsystems, Inc.
   9  *
  10  * Redistribution and use in source and binary forms, with or without
  11  * modification, are permitted provided that the following conditions
  12  * are met:
  13  * 1. Redistributions of source code must retain the above copyright
  14  *    notice, this list of conditions and the following disclaimer.
  15  * 2. Redistributions in binary form must reproduce the above copyright
  16  *    notice, this list of conditions and the following disclaimer in the
  17  *    documentation and/or other materials provided with the distribution.
  18  * 3. Neither the name of the University nor the names of its contributors
  19  *    may be used to endorse or promote products derived from this software
  20  *    without specific prior written permission.
  21  *
  22  * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
  23  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
  24  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
  25  * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
  26  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
  27  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
  28  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
  29  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
  30  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
  31  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
  32  * SUCH DAMAGE.
  33  */
  34
  35 #include <sys/cdefs.h>
  36 #ifndef lint
  37 __COPYRIGHT("@(#) Copyright (c) 1984, 1993\
  38  The Regents of the University of California.  All rights reserved.");
  39 #endif /* not lint */
  40
  41 #ifndef lint
  42 #if 0
  43 static char sccsid[] = "@(#)arp.c       8.3 (Berkeley) 4/28/95";
  44 #else
  45 __RCSID("$NetBSD: mkarp.c,v 1.7 2008/07/21 13:36:59 lukem Exp $");
  46 #endif
  47 #endif /* not lint */
  48
  49 /*
  50  * mkarp - set an arp table entry
  51  */
  52
  53 #include <sys/param.h>
  54 #include <sys/file.h>
  55 #include <sys/socket.h>
  56 #include <sys/sysctl.h>
  57
  58 #include <net/if.h>
  59 #include <net/if_dl.h>
  60 #include <net/if_ether.h>
  61 #include <net/if_types.h>
  62 #include <net/route.h>
  63 #include <netinet/in.h>
  64 #include <netinet/if_inarp.h>
  65 #include <arpa/inet.h>
  66
  67 #include <err.h>
  68 #include <errno.h>
  69 #include <netdb.h>
  70 #include <nlist.h>
  71 #include <paths.h>
  72 #include <stdio.h>
  73 #include <stdlib.h>
  74 #include <string.h>
  75 #include <unistd.h>
  76
  77 #include "mkarp.h"
  78
  79 /* Roundup the same way rt_xaddrs does */
  80 #define ROUNDUP(a) \
  81        ((a) > 0 ? (1 + (((a) - 1) | (sizeof(long) - 1))) : sizeof(long))
  82
  83 int     rtmsg(int, int, struct rt_msghdr *, struct sockaddr_inarp *,
  84               struct sockaddr_dl *);
  85 struct  {
  86         struct  rt_msghdr m_rtm;
  87         char    m_space[512];
  88 }       m_rtmsg;
  89
  90 /*
  91  * Set an individual arp entry
  92  */
  93 int
  94 mkarp(u_char *haddr, u_int32_t ipaddr)
  95 {
  96         static struct sockaddr_inarp blank_sin = {
  97                 sizeof(blank_sin), AF_INET, 0, { 0 }, { 0 }, 0, 0  };
  98         static struct sockaddr_dl blank_sdl = {
  99                 sizeof(blank_sdl), AF_LINK, 0, 0, 0, 0, 0, { 0 } };
 100
 101         struct sockaddr_inarp *sin;
 102         struct sockaddr_dl *sdl;
 103         struct rt_msghdr *rtm;
 104         u_int8_t *p, *endp;
 105         int result;
 106         int s;
 107
 108         struct sockaddr_inarp sin_m;
 109         struct sockaddr_dl sdl_m;
 110
 111         sin = &sin_m;
 112         rtm = &(m_rtmsg.m_rtm);
 113
 114         sdl_m = blank_sdl;              /* struct copy */
 115         sin_m = blank_sin;              /* struct copy */
 116
 117         sin->sin_addr.s_addr = ipaddr;
 118
 119         p = LLADDR(&sdl_m);
 120         endp = ((caddr_t)&sdl_m) + sdl_m.sdl_len;
 121         if (endp > (p + ETHER_ADDR_LEN))
 122                 endp = p + ETHER_ADDR_LEN;
 123
 124         while (p < endp) {
 125                 *p++ = *haddr++;
 126         }
 127         sdl_m.sdl_alen = ETHER_ADDR_LEN;
 128
 129         /*
 130          * We need to close and open the socket to prevent routing updates
 131          * building up such that when we send our message we never see our
 132          * reply (and hang)
 133          */
 134         s = socket(PF_ROUTE, SOCK_RAW, 0);
 135         if (s < 0)
 136                 err(1, "socket");
 137
 138         rtm->rtm_flags = 0;
 139
 140         if (rtmsg(RTM_GET, s, rtm, &sin_m, &sdl_m) < 0) {
 141 #if 0
 142                 warn("%s", host);
 143 #endif
 144                 close(s);
 145                 return (1);
 146         }
 147         sin = (struct sockaddr_inarp *)(rtm + 1);
 148         sdl = (struct sockaddr_dl *)(sin->sin_len + (char *)sin);
 149         if (sin->sin_addr.s_addr == sin_m.sin_addr.s_addr) {
 150                 if (sdl->sdl_family == AF_LINK &&
 151                     (rtm->rtm_flags & RTF_LLINFO) &&
 152                     !(rtm->rtm_flags & RTF_GATEWAY)) switch (sdl->sdl_type) {
 153                 case IFT_ETHER: case IFT_FDDI: case IFT_ISO88023:
 154                 case IFT_ISO88024: case IFT_ISO88025: case IFT_ARCNET:
 155                         goto overwrite;
 156                 }
 157 #if 0
 158                 (void)printf("set: can only proxy for %s\n", host);
 159 #endif
 160                 close(s);
 161                 return (1);
 162         }
 163 overwrite:
 164         if (sdl->sdl_family != AF_LINK) {
 165 #if 0
 166                 (void)printf("cannot intuit interface index and type for %s\n",
 167                     host);
 168 #endif
 169                 close(s);
 170                 return (1);
 171         }
 172         sdl_m.sdl_type = sdl->sdl_type;
 173         sdl_m.sdl_index = sdl->sdl_index;
 174         result = rtmsg(RTM_ADD, s, rtm, &sin_m, &sdl_m);
 175         close(s);
 176         return (result);
 177 }
 178
 179 int
 180 rtmsg(int cmd, int s, struct rt_msghdr *rtm, struct sockaddr_inarp *sin_m,
 181       struct sockaddr_dl *sdl_m)
 182 {
 183         static int seq;
 184         int rlen;
 185         char *cp;
 186         int l;
 187         pid_t pid;
 188         struct timeval tv;
 189
 190         rtm = &m_rtmsg.m_rtm;
 191         cp = m_rtmsg.m_space;
 192         errno = 0;
 193
 194         pid = getpid();
 195
 196         (void)memset(&m_rtmsg, 0, sizeof(m_rtmsg));
 197         rtm->rtm_version = RTM_VERSION;
 198
 199         switch (cmd) {
 200         default:
 201                 errx(1, "internal wrong cmd");
 202                 /*NOTREACHED*/
 203         case RTM_ADD:
 204                 rtm->rtm_addrs |= RTA_GATEWAY;
 205                 (void)gettimeofday(&tv, 0);
 206                 rtm->rtm_rmx.rmx_expire = tv.tv_sec + 20 * 60;
 207                 rtm->rtm_inits = RTV_EXPIRE;
 208                 rtm->rtm_flags |= (RTF_HOST | RTF_STATIC);
 209                 sin_m->sin_other = 0;
 210
 211                 /* FALLTHROUGH */
 212         case RTM_GET:
 213                 rtm->rtm_addrs |= RTA_DST;
 214         }
 215 #define NEXTADDR(w, s) \
 216         if (rtm->rtm_addrs & (w)) { \
 217                 (void)memcpy(cp, s, ((struct sockaddr *)s)->sa_len); \
 218                 cp += ROUNDUP(((struct sockaddr *)s)->sa_len);}
 219
 220         NEXTADDR(RTA_DST, sin_m);
 221         NEXTADDR(RTA_GATEWAY, sdl_m);
 222
 223         rtm->rtm_msglen = cp - (char *)&m_rtmsg;
 224
 225         l = rtm->rtm_msglen;
 226         rtm->rtm_seq = ++seq;
 227         rtm->rtm_type = cmd;
 228         if ((rlen = write(s, (char *)&m_rtmsg, l)) < 0) {
 229                 if (errno != ESRCH && errno != EEXIST) {
 230                         warn("writing to routing socket");
 231                         return (-1);
 232                 }
 233         }
 234         do {
 235                 l = read(s, (char *)&m_rtmsg, sizeof(m_rtmsg));
 236         } while (l > 0 && (rtm->rtm_seq != seq || rtm->rtm_pid != pid));
 237         if (l < 0)
 238                 warn("read from routing socket");
 239         return (0);
 240 }