contrib/traceroute/findsaddr-socket.c

   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
  39 static 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__
  53 struct mbuf;
  54 struct 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
  85 struct rtmsg {
  86         struct rt_msghdr rtmsg;
  87         u_char data[512];
  88 };
  89
  90 static 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
  98 static int salen(struct sockaddr *);
  99 #endif
 100
 101 /*
 102  * Return the source address for the given destination address
 103  */
 104 const char *
 105 findsaddr(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
 205 static int
 206 salen(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