1/* 2 * Copyright (c) 2000 3 * The Regents of the University of California. All rights reserved. 4 * 5 * Redistribution and use in source and binary forms, with or without 6 * modification, are permitted provided that the following conditions 7 * are met: 8 * 1. Redistributions of source code must retain the above copyright 9 * notice, this list of conditions and the following disclaimer. 10 * 2. Redistributions in binary form must reproduce the above copyright 11 * notice, this list of conditions and the following disclaimer in the 12 * documentation and/or other materials provided with the distribution. 13 * 3. All advertising materials mentioning features or use of this software 14 * must display the following acknowledgement: 15 * This product includes software developed by the Computer Systems 16 * Engineering Group at Lawrence Berkeley Laboratory. 17 * 4. Neither the name of the University nor of the Laboratory may be used 18 * to endorse or promote products derived from this software without 19 * specific prior written permission. 20 * 21 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND 22 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 23 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 24 * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE 25 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 26 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 27 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 28 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 29 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 30 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 31 * SUCH DAMAGE. 32 * 33 * $FreeBSD$ 34 */ 35 36/* XXX Yes this is WAY too complicated */ 37 38#ifndef lint 39static const char rcsid[] = 40 "@(#) $Id: findsaddr-socket.c,v 1.1 2000/11/23 20:17:12 leres Exp $ (LBL)"; 41#endif 42 43#include <sys/param.h> 44#include <sys/file.h> 45#include <sys/ioctl.h> 46#include <sys/socket.h> 47#ifdef HAVE_SYS_SOCKIO_H 48#include <sys/sockio.h> 49#endif 50#include <sys/time.h> /* concession to AIX */ 51 52#if __STDC__ 53struct mbuf; 54struct rtentry; 55#endif 56 57#include <net/if.h> 58#include <net/if_dl.h> 59#include <net/route.h> 60#include <netinet/in.h> 61 62#include <errno.h> 63#include <stdio.h> 64#include <stdlib.h> 65#include <string.h> 66#include <unistd.h> 67 68#include "gnuc.h" 69#ifdef HAVE_OS_PROTO_H 70#include "os-proto.h" 71#endif 72 73#include "findsaddr.h" 74 75#ifdef HAVE_SOCKADDR_SA_LEN 76#define SALEN(sa) ((sa)->sa_len) 77#else 78#define SALEN(sa) salen(sa) 79#endif 80 81#ifndef roundup 82#define roundup(x, y) ((((x)+((y)-1))/(y))*(y)) /* to any y */ 83#endif 84 85struct rtmsg { 86 struct rt_msghdr rtmsg; 87 u_char data[512]; 88}; 89 90static struct rtmsg rtmsg = { 91 { 0, RTM_VERSION, RTM_GET, 0, 92 RTF_UP | RTF_GATEWAY | RTF_HOST | RTF_STATIC, 93 RTA_DST | RTA_IFA, 0, 0, 0, 0, 0, { 0 } }, 94 { 0 } 95}; 96 97#ifndef HAVE_SOCKADDR_SA_LEN 98static int salen(struct sockaddr *); 99#endif 100 101/* 102 * Return the source address for the given destination address 103 */ 104const char * 105findsaddr(register const struct sockaddr_in *to, 106 register struct sockaddr_in *from) 107{ 108 register struct rt_msghdr *rp; 109 register u_char *cp; 110 111 register struct sockaddr_in *sp, *ifa; 112 register struct sockaddr *sa; 113 register int s, size, cc, seq, i; 114 register pid_t pid; 115 static char errbuf[512]; 116 117 s = socket(PF_ROUTE, SOCK_RAW, AF_UNSPEC); 118 if (s < 0) { 119 sprintf(errbuf, "socket: %.128s", strerror(errno)); 120 return (errbuf); 121 } 122 123 seq = 0; 124 pid = getpid(); 125 126 rp = &rtmsg.rtmsg; 127 rp->rtm_seq = ++seq; 128 cp = (u_char *)(rp + 1); 129 130 sp = (struct sockaddr_in *)cp; 131 *sp = *to; 132 cp += roundup(SALEN((struct sockaddr *)sp), sizeof(u_int32_t)); 133 134 size = cp - (u_char *)rp; 135 rp->rtm_msglen = size; 136 137 cc = write(s, (char *)rp, size); 138 if (cc < 0) { 139 sprintf(errbuf, "write: %.128s", strerror(errno)); 140 close(s); 141 return (errbuf); 142 } 143 if (cc != size) { 144 sprintf(errbuf, "short write (%d != %d)", cc, size); 145 close(s); 146 return (errbuf); 147 } 148 149 size = sizeof(rtmsg); 150 do { 151 memset(rp, 0, size); 152 cc = read(s, (char *)rp, size); 153 if (cc < 0) { 154 sprintf(errbuf, "read: %.128s", strerror(errno)); 155 close(s); 156 return (errbuf); 157 } 158 159 } while (rp->rtm_seq != seq || rp->rtm_pid != pid); 160 close(s); 161 162 163 if (rp->rtm_version != RTM_VERSION) { 164 sprintf(errbuf, "bad version %d", rp->rtm_version); 165 return (errbuf); 166 } 167 if (rp->rtm_msglen > cc) { 168 sprintf(errbuf, "bad msglen %d > %d", rp->rtm_msglen, cc); 169 return (errbuf); 170 } 171 if (rp->rtm_errno != 0) { 172 sprintf(errbuf, "rtm_errno: %.128s", strerror(rp->rtm_errno)); 173 return (errbuf); 174 } 175 176 /* Find the interface sockaddr */ 177 cp = (u_char *)(rp + 1); 178 for (i = 1; i != 0; i <<= 1) 179 if ((i & rp->rtm_addrs) != 0) { 180 sa = (struct sockaddr *)cp; 181 switch (i) { 182 183 case RTA_IFA: 184 if (sa->sa_family == AF_INET) { 185 ifa = (struct sockaddr_in *)cp; 186 if (ifa->sin_addr.s_addr != 0) { 187 *from = *ifa; 188 return (NULL); 189 } 190 } 191 break; 192 193 } 194 195 if (SALEN(sa) == 0) 196 cp += sizeof(long); 197 else 198 cp += roundup(SALEN(sa), sizeof(long)); 199 } 200 201 return ("failed!"); 202} 203 204#ifndef HAVE_SOCKADDR_SA_LEN 205static int 206salen(struct sockaddr *sa) 207{ 208 switch (sa->sa_family) { 209 210 case AF_INET: 211 return (sizeof(struct sockaddr_in)); 212 213 case AF_LINK: 214 return (sizeof(struct sockaddr_dl)); 215 216 default: 217 return (sizeof(struct sockaddr)); 218 } 219} 220#endif 221