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 *
findsaddr(register const struct sockaddr_in * to,register struct sockaddr_in * from)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