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 34 /* XXX Yes this is WAY too complicated */ 35 36 #include <sys/param.h> 37 #include <sys/file.h> 38 #include <sys/ioctl.h> 39 #include <sys/socket.h> 40 #include <sys/sockio.h> 41 #include <sys/time.h> /* concession to AIX */ 42 43 #if __STDC__ 44 struct mbuf; 45 struct rtentry; 46 #endif 47 48 #include <net/if.h> 49 #include <net/if_dl.h> 50 #include <net/route.h> 51 #include <netinet/in.h> 52 53 #include <errno.h> 54 #include <stdio.h> 55 #include <stdlib.h> 56 #include <string.h> 57 #include <unistd.h> 58 59 #include "gnuc.h" 60 #include "os-proto.h" 61 62 #include "findsaddr.h" 63 64 #define SALEN(sa) ((sa)->sa_len) 65 66 #ifndef roundup 67 #define roundup(x, y) ((((x)+((y)-1))/(y))*(y)) /* to any y */ 68 #endif 69 70 struct rtmsg { 71 struct rt_msghdr rtmsg; 72 u_char data[512]; 73 }; 74 75 static struct rtmsg rtmsg = { 76 { 0, RTM_VERSION, RTM_GET, 0, 77 RTF_UP | RTF_GATEWAY | RTF_HOST | RTF_STATIC, 78 RTA_DST | RTA_IFA, 0, 0, 0, 0, 0, { 0 } }, 79 { 0 } 80 }; 81 82 /* 83 * Return the source address for the given destination address 84 */ 85 const char * 86 findsaddr(register const struct sockaddr_in *to, 87 register struct sockaddr_in *from) 88 { 89 register struct rt_msghdr *rp; 90 register u_char *cp; 91 92 register struct sockaddr_in *sp, *ifa; 93 register struct sockaddr *sa; 94 register int s, size, cc, seq, i; 95 register pid_t pid; 96 static char errbuf[512]; 97 98 s = socket(PF_ROUTE, SOCK_RAW, AF_UNSPEC); 99 if (s < 0) { 100 sprintf(errbuf, "socket: %.128s", strerror(errno)); 101 return (errbuf); 102 } 103 104 seq = 0; 105 pid = getpid(); 106 107 rp = &rtmsg.rtmsg; 108 rp->rtm_seq = ++seq; 109 cp = (u_char *)(rp + 1); 110 111 sp = (struct sockaddr_in *)cp; 112 *sp = *to; 113 cp += roundup(SALEN((struct sockaddr *)sp), sizeof(u_int32_t)); 114 115 size = cp - (u_char *)rp; 116 rp->rtm_msglen = size; 117 118 cc = write(s, (char *)rp, size); 119 if (cc < 0) { 120 sprintf(errbuf, "write: %.128s", strerror(errno)); 121 close(s); 122 return (errbuf); 123 } 124 if (cc != size) { 125 sprintf(errbuf, "short write (%d != %d)", cc, size); 126 close(s); 127 return (errbuf); 128 } 129 130 size = sizeof(rtmsg); 131 do { 132 memset(rp, 0, size); 133 cc = read(s, (char *)rp, size); 134 if (cc < 0) { 135 sprintf(errbuf, "read: %.128s", strerror(errno)); 136 close(s); 137 return (errbuf); 138 } 139 140 } while (rp->rtm_type != RTM_GET || rp->rtm_seq != seq || 141 rp->rtm_pid != pid); 142 close(s); 143 144 145 if (rp->rtm_version != RTM_VERSION) { 146 sprintf(errbuf, "bad version %d", rp->rtm_version); 147 return (errbuf); 148 } 149 if (rp->rtm_msglen > cc) { 150 sprintf(errbuf, "bad msglen %d > %d", rp->rtm_msglen, cc); 151 return (errbuf); 152 } 153 if (rp->rtm_errno != 0) { 154 sprintf(errbuf, "rtm_errno: %.128s", strerror(rp->rtm_errno)); 155 return (errbuf); 156 } 157 158 /* Find the interface sockaddr */ 159 cp = (u_char *)(rp + 1); 160 for (i = 1; i != 0; i <<= 1) 161 if ((i & rp->rtm_addrs) != 0) { 162 sa = (struct sockaddr *)cp; 163 switch (i) { 164 165 case RTA_IFA: 166 if (sa->sa_family == AF_INET) { 167 ifa = (struct sockaddr_in *)cp; 168 if (ifa->sin_addr.s_addr != 0) { 169 *from = *ifa; 170 return (NULL); 171 } 172 } 173 break; 174 175 } 176 177 if (SALEN(sa) == 0) 178 cp += sizeof(long); 179 else 180 cp += roundup(SALEN(sa), sizeof(long)); 181 } 182 183 return ("failed!"); 184 } 185