1 /* $NetBSD: mkarp.c,v 1.8 2009/04/18 08:50:23 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 1.8 2009/04/18 08:50:23 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 } 241