1 /* $NetBSD: mkarp.c,v 1.12 2017/04/12 16:57:14 roy 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 1.12 2017/04/12 16:57:14 roy 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 #ifdef RO_MSGFILTER 136 unsigned char msgfilter[] = { RTM_GET, RTM_ADD }; 137 #endif 138 139 sin = &sin_m; 140 rtm = &(m_rtmsg.m_rtm); 141 142 sdl_m = blank_sdl; /* struct copy */ 143 sin_m = blank_sin; /* struct copy */ 144 145 sin->sin_addr.s_addr = ipaddr; 146 147 p = LLADDR(&sdl_m); 148 endp = ((caddr_t)&sdl_m) + sdl_m.sdl_len; 149 if (endp > (p + ETHER_ADDR_LEN)) 150 endp = p + ETHER_ADDR_LEN; 151 152 while (p < endp) { 153 *p++ = *haddr++; 154 } 155 sdl_m.sdl_alen = ETHER_ADDR_LEN; 156 157 /* 158 * We need to close and open the socket to prevent routing updates 159 * building up such that when we send our message we never see our 160 * reply (and hang) 161 */ 162 s = socket(PF_ROUTE, SOCK_RAW, 0); 163 if (s < 0) 164 err(1, "socket"); 165 #ifdef RO_MSGFILTER 166 if (setsockopt(s, PF_ROUTE, RO_MSGFILTER, 167 &msgfilter, sizeof(msgfilter)) < 0) 168 warn("RO_MSGFILTER"); 169 #endif 170 171 rtm->rtm_flags = 0; 172 173 if (rtmsg(RTM_GET, s, rtm, &sin_m, &sdl_m) < 0) { 174 #if 0 175 warn("%s", host); 176 #endif 177 close(s); 178 return (1); 179 } 180 sin = (struct sockaddr_inarp *)(rtm + 1); 181 sdl = (struct sockaddr_dl *)(sin->sin_len + (char *)sin); 182 if (sin->sin_addr.s_addr == sin_m.sin_addr.s_addr) { 183 if (is_llinfo(sdl, rtm->rtm_flags)) 184 goto overwrite; 185 #if 0 186 (void)printf("set: can only proxy for %s\n", host); 187 #endif 188 close(s); 189 return (1); 190 } 191 overwrite: 192 if (sdl->sdl_family != AF_LINK) { 193 #if 0 194 (void)printf("cannot intuit interface index and type for %s\n", 195 host); 196 #endif 197 close(s); 198 return (1); 199 } 200 sdl_m.sdl_type = sdl->sdl_type; 201 sdl_m.sdl_index = sdl->sdl_index; 202 result = rtmsg(RTM_ADD, s, rtm, &sin_m, &sdl_m); 203 close(s); 204 return (result); 205 } 206 207 int 208 rtmsg(int cmd, int s, struct rt_msghdr *rtm, struct sockaddr_inarp *sin_m, 209 struct sockaddr_dl *sdl_m) 210 { 211 static int seq; 212 int rlen; 213 char *cp; 214 int l; 215 pid_t pid; 216 struct timeval tv; 217 218 rtm = &m_rtmsg.m_rtm; 219 cp = m_rtmsg.m_space; 220 errno = 0; 221 222 pid = getpid(); 223 224 (void)memset(&m_rtmsg, 0, sizeof(m_rtmsg)); 225 rtm->rtm_version = RTM_VERSION; 226 227 switch (cmd) { 228 default: 229 errx(1, "internal wrong cmd"); 230 /*NOTREACHED*/ 231 case RTM_ADD: 232 rtm->rtm_addrs |= RTA_GATEWAY; 233 (void)gettimeofday(&tv, 0); 234 rtm->rtm_rmx.rmx_expire = tv.tv_sec + 20 * 60; 235 rtm->rtm_inits = RTV_EXPIRE; 236 rtm->rtm_flags |= (RTF_HOST | RTF_STATIC | RTF_LLDATA); 237 sin_m->sin_other = 0; 238 239 /* FALLTHROUGH */ 240 case RTM_GET: 241 rtm->rtm_addrs |= RTA_DST; 242 } 243 #define NEXTADDR(w, s) \ 244 if (rtm->rtm_addrs & (w)) { \ 245 (void)memcpy(cp, s, ((struct sockaddr *)s)->sa_len); \ 246 cp += ROUNDUP(((struct sockaddr *)s)->sa_len);} 247 248 NEXTADDR(RTA_DST, sin_m); 249 NEXTADDR(RTA_GATEWAY, sdl_m); 250 251 rtm->rtm_msglen = cp - (char *)&m_rtmsg; 252 253 l = rtm->rtm_msglen; 254 rtm->rtm_seq = ++seq; 255 rtm->rtm_type = cmd; 256 if ((rlen = write(s, (char *)&m_rtmsg, l)) < 0) { 257 if (errno != ESRCH && errno != EEXIST) { 258 warn("writing to routing socket"); 259 return (-1); 260 } 261 } 262 do { 263 l = read(s, (char *)&m_rtmsg, sizeof(m_rtmsg)); 264 } while (l > 0 && (rtm->rtm_seq != seq || rtm->rtm_pid != pid)); 265 if (l < 0) 266 warn("read from routing socket"); 267 return (0); 268 } 269
Indexes created Sun Sep 21 20:09:37 GMT 2025