1 /* $OpenBSD: arptab.c,v 1.22 2013/11/12 19:49:42 deraadt 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 /* 36 * set arp table entries 37 */ 38 39 40 #include <sys/param.h> 41 #include <sys/file.h> 42 #include <sys/socket.h> 43 #include <sys/sysctl.h> 44 45 #include <net/if.h> 46 #include <net/if_dl.h> 47 #include <net/if_types.h> 48 #include <net/route.h> 49 50 #include <netinet/in.h> 51 #include <netinet/if_ether.h> 52 53 #include <arpa/inet.h> 54 55 #include <netdb.h> 56 #include <errno.h> 57 #include <stdio.h> 58 #include <unistd.h> 59 #include <stdlib.h> 60 #include <paths.h> 61 #include <syslog.h> 62 #include <string.h> 63 #include <err.h> 64 65 static pid_t pid; 66 static int s = -1; 67 68 static void 69 getsocket(void) 70 { 71 s = socket(PF_ROUTE, SOCK_RAW, 0); 72 if (s < 0) 73 err(1, "arp: socket"); 74 } 75 76 struct sockaddr_in so_mask = {8, 0, 0, { 0xffffffff}}; 77 struct sockaddr_inarp blank_sin = {sizeof(blank_sin), AF_INET }, sin_m; 78 struct sockaddr_dl blank_sdl = {sizeof(blank_sdl), AF_LINK }, sdl_m; 79 time_t expire_time; 80 int flags, export_only, doing_proxy; 81 82 struct { 83 struct rt_msghdr m_rtm; 84 char m_space[512]; 85 } m_rtmsg; 86 87 int arptab_set(u_char *, u_int32_t); 88 int rtmsg(int); 89 90 /* 91 * Set an individual arp entry 92 */ 93 int 94 arptab_set(u_char *eaddr, u_int32_t host) 95 { 96 struct sockaddr_inarp *sin = &sin_m; 97 struct rt_msghdr *rtm = &(m_rtmsg.m_rtm); 98 struct sockaddr_dl *sdl; 99 struct timeval now; 100 int rt; 101 102 getsocket(); 103 pid = getpid(); 104 105 sdl_m = blank_sdl; 106 sin_m = blank_sin; 107 sin->sin_addr.s_addr = host; 108 memcpy((u_char *)LLADDR(&sdl_m), (char *)eaddr, 6); 109 sdl_m.sdl_alen = 6; 110 expire_time = 0; 111 doing_proxy = flags = export_only = 0; 112 gettimeofday(&now, 0); 113 expire_time = now.tv_sec + 20 * 60; 114 115 tryagain: 116 if (rtmsg(RTM_GET) < 0) { 117 syslog(LOG_ERR,"%s: %m", inet_ntoa(sin->sin_addr)); 118 close(s); 119 s = -1; 120 return (1); 121 } 122 sin = (struct sockaddr_inarp *)((char *)rtm + rtm->rtm_hdrlen); 123 sdl = (struct sockaddr_dl *)(sin->sin_len + (char *)sin); 124 if (sin->sin_addr.s_addr == sin_m.sin_addr.s_addr) { 125 if (sdl->sdl_family == AF_LINK && 126 (rtm->rtm_flags & RTF_LLINFO) && 127 !(rtm->rtm_flags & RTF_GATEWAY)) 128 switch (sdl->sdl_type) { 129 case IFT_ETHER: 130 case IFT_FDDI: 131 case IFT_ISO88023: 132 case IFT_ISO88024: 133 case IFT_ISO88025: 134 goto overwrite; 135 default: 136 break; 137 } 138 if (doing_proxy == 0) { 139 syslog(LOG_ERR, "arptab_set: can only proxy for %s", 140 inet_ntoa(sin->sin_addr)); 141 close(s); 142 s = -1; 143 return (1); 144 } 145 if (sin_m.sin_other & SIN_PROXY) { 146 syslog(LOG_ERR, 147 "arptab_set: proxy entry exists for non 802 device"); 148 close(s); 149 s = -1; 150 return(1); 151 } 152 sin_m.sin_other = SIN_PROXY; 153 export_only = 1; 154 goto tryagain; 155 } 156 overwrite: 157 if (sdl->sdl_family != AF_LINK) { 158 syslog(LOG_ERR, 159 "arptab_set: cannot intuit interface index and type for %s", 160 inet_ntoa(sin->sin_addr)); 161 close(s); 162 s = -1; 163 return (1); 164 } 165 sdl_m.sdl_type = sdl->sdl_type; 166 sdl_m.sdl_index = sdl->sdl_index; 167 rt = rtmsg(RTM_ADD); 168 close(s); 169 s = -1; 170 return (rt); 171 } 172 173 int 174 rtmsg(int cmd) 175 { 176 static int seq; 177 struct rt_msghdr *rtm = &m_rtmsg.m_rtm; 178 char *cp = m_rtmsg.m_space; 179 int l; 180 181 errno = 0; 182 if (cmd == RTM_DELETE) 183 goto doit; 184 memset((char *)&m_rtmsg, 0, sizeof(m_rtmsg)); 185 rtm->rtm_flags = flags; 186 rtm->rtm_version = RTM_VERSION; 187 188 switch (cmd) { 189 default: 190 syslog(LOG_ERR, "arptab_set: internal wrong cmd"); 191 exit(1); 192 case RTM_ADD: 193 rtm->rtm_addrs |= RTA_GATEWAY; 194 rtm->rtm_rmx.rmx_expire = expire_time; 195 rtm->rtm_inits = RTV_EXPIRE; 196 rtm->rtm_flags |= (RTF_HOST | RTF_STATIC); 197 sin_m.sin_other = 0; 198 if (doing_proxy) { 199 if (export_only) 200 sin_m.sin_other = SIN_PROXY; 201 else { 202 rtm->rtm_addrs |= RTA_NETMASK; 203 rtm->rtm_flags &= ~RTF_HOST; 204 } 205 } 206 /* FALLTHROUGH */ 207 case RTM_GET: 208 rtm->rtm_addrs |= RTA_DST; 209 } 210 #define NEXTADDR(w, s) \ 211 if (rtm->rtm_addrs & (w)) { \ 212 memcpy(cp, (char *)&s, sizeof(s)); \ 213 cp += sizeof(s); \ 214 } 215 216 NEXTADDR(RTA_DST, sin_m); 217 NEXTADDR(RTA_GATEWAY, sdl_m); 218 NEXTADDR(RTA_NETMASK, so_mask); 219 220 rtm->rtm_msglen = cp - (char *)&m_rtmsg; 221 doit: 222 l = rtm->rtm_msglen; 223 rtm->rtm_seq = ++seq; 224 rtm->rtm_type = cmd; 225 if (write(s, (char *)&m_rtmsg, l) < 0) { 226 if (errno != ESRCH && errno != EEXIST) { 227 syslog(LOG_ERR, "writing to routing socket: %m"); 228 return (-1); 229 } 230 } 231 do { 232 l = read(s, (char *)&m_rtmsg, sizeof(m_rtmsg)); 233 } while (l > 0 && (rtm->rtm_version != RTM_VERSION || 234 rtm->rtm_seq != seq || rtm->rtm_pid != pid)); 235 if (l < 0) 236 syslog(LOG_ERR, "arptab_set: read from routing socket: %m"); 237 return (0); 238 } 239