traceroute.tproj/findsaddr-socket.c

   1 /*
   2  * Copyright (c) 2008-2009 Apple Inc. All rights reserved.
   3  *
   4  * @APPLE_OSREFERENCE_LICENSE_HEADER_START@
   5  *
   6  * This file contains Original Code and/or Modifications of Original Code
   7  * as defined in and that are subject to the Apple Public Source License
   8  * Version 2.0 (the 'License'). You may not use this file except in
   9  * compliance with the License. The rights granted to you under the License
  10  * may not be used to create, or enable the creation or redistribution of,
  11  * unlawful or unlicensed copies of an Apple operating system, or to
  12  * circumvent, violate, or enable the circumvention or violation of, any
  13  * terms of an Apple operating system software license agreement.
  14  *
  15  * Please obtain a copy of the License at
  16  * http://www.opensource.apple.com/apsl/ and read it before using this file.
  17  *
  18  * The Original Code and all software distributed under the License are
  19  * distributed on an 'AS IS' basis, WITHOUT WARRANTY OF ANY KIND, EITHER
  20  * EXPRESS OR IMPLIED, AND APPLE HEREBY DISCLAIMS ALL SUCH WARRANTIES,
  21  * INCLUDING WITHOUT LIMITATION, ANY WARRANTIES OF MERCHANTABILITY,
  22  * FITNESS FOR A PARTICULAR PURPOSE, QUIET ENJOYMENT OR NON-INFRINGEMENT.
  23  * Please see the License for the specific language governing rights and
  24  * limitations under the License.
  25  *
  26  * @APPLE_OSREFERENCE_LICENSE_HEADER_END@
  27  */
  28
  29 /*
  30  * Copyright (c) 2000
  31  *      The Regents of the University of California.  All rights reserved.
  32  *
  33  * Redistribution and use in source and binary forms, with or without
  34  * modification, are permitted provided that the following conditions
  35  * are met:
  36  * 1. Redistributions of source code must retain the above copyright
  37  *    notice, this list of conditions and the following disclaimer.
  38  * 2. Redistributions in binary form must reproduce the above copyright
  39  *    notice, this list of conditions and the following disclaimer in the
  40  *    documentation and/or other materials provided with the distribution.
  41  * 3. All advertising materials mentioning features or use of this software
  42  *    must display the following acknowledgement:
  43  *      This product includes software developed by the Computer Systems
  44  *      Engineering Group at Lawrence Berkeley Laboratory.
  45  * 4. Neither the name of the University nor of the Laboratory may be used
  46  *    to endorse or promote products derived from this software without
  47  *    specific prior written permission.
  48  *
  49  * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
  50  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
  51  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
  52  * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
  53  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
  54  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
  55  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
  56  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
  57  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
  58  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
  59  * SUCH DAMAGE.
  60  *
  61  * $FreeBSD: src/contrib/traceroute/findsaddr-socket.c,v 1.2 2002/07/30 04:49:13 fenner Exp $
  62  */
  63
  64 /* XXX Yes this is WAY too complicated */
  65
  66 #ifndef lint
  67 static const char rcsid[] =
  68     "@(#) $Id: findsaddr-socket.c,v 1.3 2005/02/12 00:04:09 lindak Exp $ (LBL)";
  69 #endif
  70
  71 #include <sys/param.h>
  72 #include <sys/file.h>
  73 #include <sys/ioctl.h>
  74 #include <sys/socket.h>
  75 #ifdef HAVE_SYS_SOCKIO_H
  76 #include <sys/sockio.h>
  77 #endif
  78 #include <sys/time.h>                           /* concession to AIX */
  79
  80 #if __STDC__
  81 struct mbuf;
  82 struct rtentry;
  83 #endif
  84
  85 #include <net/if.h>
  86 #include <net/if_dl.h>
  87 #include <net/route.h>
  88 #include <netinet/in.h>
  89
  90 #include <errno.h>
  91 #include <stdio.h>
  92 #include <stdlib.h>
  93 #include <string.h>
  94 #include <unistd.h>
  95
  96 #include "gnuc.h"
  97 #ifdef HAVE_OS_PROTO_H
  98 #include "os-proto.h"
  99 #endif
 100
 101 #include "findsaddr.h"
 102
 103 #ifdef HAVE_SOCKADDR_SA_LEN
 104 #define SALEN(sa) ((sa)->sa_len)
 105 #else
 106 #define SALEN(sa) salen(sa)
 107 #endif
 108
 109 #ifndef roundup
 110 #define roundup(x, y)   ((((x)+((y)-1))/(y))*(y))  /* to any y */
 111 #endif
 112
 113 struct rtmsg {
 114         struct rt_msghdr rtmsg;
 115         u_char data[512];
 116 };
 117
 118 static struct rtmsg rtmsg = {
 119         { 0, RTM_VERSION, RTM_GET, 0,
 120         RTF_UP | RTF_GATEWAY | RTF_HOST | RTF_STATIC,
 121         RTA_DST | RTA_IFA, 0, 0, 0, 0, 0, { 0 } },
 122         { 0 }
 123 };
 124
 125 #ifndef HAVE_SOCKADDR_SA_LEN
 126 static int salen(struct sockaddr *);
 127 #endif
 128
 129 /*
 130  * Return the source address for the given destination address
 131  */
 132 const char *
 133 findsaddr(register const struct sockaddr_in *to,
 134     register struct sockaddr_in *from)
 135 {
 136         register struct rt_msghdr *rp;
 137         register u_char *cp;
 138
 139         register struct sockaddr_in *sp, *ifa;
 140         register struct sockaddr *sa;
 141         register int s, size, cc, seq, i;
 142         register pid_t pid;
 143         static char errbuf[512];
 144
 145         s = socket(PF_ROUTE, SOCK_RAW, AF_UNSPEC);
 146         if (s < 0) {
 147                 snprintf(errbuf, sizeof(errbuf), "socket: %.128s", strerror(errno));
 148                 return (errbuf);
 149         }
 150
 151         seq = 0;
 152         pid = getpid();
 153
 154         rp = &rtmsg.rtmsg;
 155         rp->rtm_seq = ++seq;
 156         cp = (u_char *)(rp + 1);
 157
 158         sp = (struct sockaddr_in *)cp;
 159         *sp = *to;
 160         cp += roundup(SALEN((struct sockaddr *)sp), sizeof(u_int32_t));
 161
 162         size = cp - (u_char *)rp;
 163         rp->rtm_msglen = size;
 164
 165         cc = write(s, (char *)rp, size);
 166         if (cc < 0) {
 167                 snprintf(errbuf, sizeof(errbuf), "write: %.128s", strerror(errno));
 168                 close(s);
 169                 return (errbuf);
 170         }
 171         if (cc != size) {
 172                 snprintf(errbuf, sizeof(errbuf), "short write (%d != %d)", cc, size);
 173                 close(s);
 174                 return (errbuf);
 175         }
 176
 177         size = sizeof(rtmsg);
 178         do {
 179                 memset(rp, 0, size);
 180                 cc = read(s, (char *)rp, size);
 181                 if (cc < 0) {
 182                         snprintf(errbuf, sizeof(errbuf), "read: %.128s", strerror(errno));
 183                         close(s);
 184                         return (errbuf);
 185                 }
 186
 187         } while (rp->rtm_seq != seq || rp->rtm_pid != pid);
 188         close(s);
 189
 190
 191         if (rp->rtm_version != RTM_VERSION) {
 192                 snprintf(errbuf, sizeof(errbuf), "bad version %d", rp->rtm_version);
 193                 return (errbuf);
 194         }
 195         if (rp->rtm_msglen > cc) {
 196                 snprintf(errbuf, sizeof(errbuf), "bad msglen %d > %d", rp->rtm_msglen, cc);
 197                 return (errbuf);
 198         }
 199         if (rp->rtm_errno != 0) {
 200                 snprintf(errbuf, sizeof(errbuf), "rtm_errno: %.128s", strerror(rp->rtm_errno));
 201                 return (errbuf);
 202         }
 203
 204         /* Find the interface sockaddr */
 205         cp = (u_char *)(rp + 1);
 206         for (i = 1; i != 0; i <<= 1)
 207                 if ((i & rp->rtm_addrs) != 0) {
 208                         sa = (struct sockaddr *)cp;
 209                         switch (i) {
 210
 211                         case RTA_IFA:
 212                                 if (sa->sa_family == AF_INET) {
 213                                         ifa = (struct sockaddr_in *)cp;
 214                                         if (ifa->sin_addr.s_addr != 0) {
 215                                                 *from = *ifa;
 216                                                 return (NULL);
 217                                         }
 218                                 }
 219                                 break;
 220
 221                         default:
 222                                 break;
 223                                 /* empty */
 224                         }
 225
 226                         if (SALEN(sa) == 0)
 227                                 cp += sizeof (u_int32_t);
 228                         else
 229                                 cp += roundup(SALEN(sa), sizeof (u_int32_t));
 230                 }
 231
 232         return ("failed!");
 233 }
 234
 235 #ifndef HAVE_SOCKADDR_SA_LEN
 236 static int
 237 salen(struct sockaddr *sa)
 238 {
 239         switch (sa->sa_family) {
 240
 241         case AF_INET:
 242                 return (sizeof(struct sockaddr_in));
 243
 244         case AF_LINK:
 245                 return (sizeof(struct sockaddr_dl));
 246
 247         default:
 248                 return (sizeof(struct sockaddr));
 249         }
 250 }
 251 #endif