1 /* $NetBSD: mkarp.c,v 1.11 2016/04/04 07:37:08 ozaki-r 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 1.11 2016/04/04 07:37:08 ozaki-r 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 static struct { 86 struct rt_msghdr m_rtm; 87 char m_space[512]; 88 } m_rtmsg; 89 90 static int 91 is_llinfo(const struct sockaddr_dl *sdl, int rtflags) 92 { 93 if (sdl->sdl_family != AF_LINK || 94 (rtflags & (RTF_LLDATA|RTF_GATEWAY)) != RTF_LLDATA) 95 return 0; 96 97 switch (sdl->sdl_type) { 98 case IFT_ETHER: 99 case IFT_FDDI: 100 case IFT_ISO88023: 101 case IFT_ISO88024: 102 case IFT_ISO88025: 103 case IFT_ARCNET: 104 return 1; 105 default: 106 return 0; 107 } 108 } 109 110 /* 111 * Set an individual arp entry 112 */ 113 int 114 mkarp(u_char *haddr, u_int32_t ipaddr) 115 { 116 static struct sockaddr_inarp blank_sin = { 117 .sin_len = sizeof(blank_sin), 118 .sin_family = AF_INET, 119 }; 120 static struct sockaddr_dl blank_sdl = { 121 .sdl_len = sizeof(blank_sdl), 122 .sdl_family = AF_LINK, 123 }; 124 125 struct sockaddr_inarp *sin; 126 struct sockaddr_dl *sdl; 127 struct rt_msghdr *rtm; 128 u_int8_t *p, *endp; 129 int result; 130 int s; 131 132 struct sockaddr_inarp sin_m; 133 struct sockaddr_dl sdl_m; 134 135 sin = &sin_m; 136 rtm = &(m_rtmsg.m_rtm); 137 138 sdl_m = blank_sdl; /* struct copy */ 139 sin_m = blank_sin; /* struct copy */ 140 141 sin->sin_addr.s_addr = ipaddr; 142 143 p = LLADDR(&sdl_m); 144 endp = ((caddr_t)&sdl_m) + sdl_m.sdl_len; 145 if (endp > (p + ETHER_ADDR_LEN)) 146 endp = p + ETHER_ADDR_LEN; 147 148 while (p < endp) { 149 *p++ = *haddr++; 150 } 151 sdl_m.sdl_alen = ETHER_ADDR_LEN; 152 153 /* 154 * We need to close and open the socket to prevent routing updates 155 * building up such that when we send our message we never see our 156 * reply (and hang) 157 */ 158 s = socket(PF_ROUTE, SOCK_RAW, 0); 159 if (s < 0) 160 err(1, "socket"); 161 162 rtm->rtm_flags = 0; 163 164 if (rtmsg(RTM_GET, s, rtm, &sin_m, &sdl_m) < 0) { 165 #if 0 166 warn("%s", host); 167 #endif 168 close(s); 169 return (1); 170 } 171 sin = (struct sockaddr_inarp *)(rtm + 1); 172 sdl = (struct sockaddr_dl *)(sin->sin_len + (char *)sin); 173 if (sin->sin_addr.s_addr == sin_m.sin_addr.s_addr) { 174 if (is_llinfo(sdl, rtm->rtm_flags)) 175 goto overwrite; 176 #if 0 177 (void)printf("set: can only proxy for %s\n", host); 178 #endif 179 close(s); 180 return (1); 181 } 182 overwrite: 183 if (sdl->sdl_family != AF_LINK) { 184 #if 0 185 (void)printf("cannot intuit interface index and type for %s\n", 186 host); 187 #endif 188 close(s); 189 return (1); 190 } 191 sdl_m.sdl_type = sdl->sdl_type; 192 sdl_m.sdl_index = sdl->sdl_index; 193 result = rtmsg(RTM_ADD, s, rtm, &sin_m, &sdl_m); 194 close(s); 195 return (result); 196 } 197 198 int 199 rtmsg(int cmd, int s, struct rt_msghdr *rtm, struct sockaddr_inarp *sin_m, 200 struct sockaddr_dl *sdl_m) 201 { 202 static int seq; 203 int rlen; 204 char *cp; 205 int l; 206 pid_t pid; 207 struct timeval tv; 208 209 rtm = &m_rtmsg.m_rtm; 210 cp = m_rtmsg.m_space; 211 errno = 0; 212 213 pid = getpid(); 214 215 (void)memset(&m_rtmsg, 0, sizeof(m_rtmsg)); 216 rtm->rtm_version = RTM_VERSION; 217 218 switch (cmd) { 219 default: 220 errx(1, "internal wrong cmd"); 221 /*NOTREACHED*/ 222 case RTM_ADD: 223 rtm->rtm_addrs |= RTA_GATEWAY; 224 (void)gettimeofday(&tv, 0); 225 rtm->rtm_rmx.rmx_expire = tv.tv_sec + 20 * 60; 226 rtm->rtm_inits = RTV_EXPIRE; 227 rtm->rtm_flags |= (RTF_HOST | RTF_STATIC | RTF_LLDATA); 228 sin_m->sin_other = 0; 229 230 /* FALLTHROUGH */ 231 case RTM_GET: 232 rtm->rtm_addrs |= RTA_DST; 233 } 234 #define NEXTADDR(w, s) \ 235 if (rtm->rtm_addrs & (w)) { \ 236 (void)memcpy(cp, s, ((struct sockaddr *)s)->sa_len); \ 237 cp += ROUNDUP(((struct sockaddr *)s)->sa_len);} 238 239 NEXTADDR(RTA_DST, sin_m); 240 NEXTADDR(RTA_GATEWAY, sdl_m); 241 242 rtm->rtm_msglen = cp - (char *)&m_rtmsg; 243 244 l = rtm->rtm_msglen; 245 rtm->rtm_seq = ++seq; 246 rtm->rtm_type = cmd; 247 if ((rlen = write(s, (char *)&m_rtmsg, l)) < 0) { 248 if (errno != ESRCH && errno != EEXIST) { 249 warn("writing to routing socket"); 250 return (-1); 251 } 252 } 253 do { 254 l = read(s, (char *)&m_rtmsg, sizeof(m_rtmsg)); 255 } while (l > 0 && (rtm->rtm_seq != seq || rtm->rtm_pid != pid)); 256 if (l < 0) 257 warn("read from routing socket"); 258 return (0); 259 } 260