talk(1): Raise WARNS to 6 and fix warnings.
[dragonfly.git] / usr.bin / talk / get_iface.c
CommitLineData
984263bc
MD
1/*
2 * Copyright 1994, 1995 Massachusetts Institute of Technology
3 *
4 * Permission to use, copy, modify, and distribute this software and
5 * its documentation for any purpose and without fee is hereby
6 * granted, provided that both the above copyright notice and this
7 * permission notice appear in all copies, that both the above
8 * copyright notice and this permission notice appear in all
9 * supporting documentation, and that the name of M.I.T. not be used
10 * in advertising or publicity pertaining to distribution of the
11 * software without specific, written prior permission. M.I.T. makes
12 * no representations about the suitability of this software for any
13 * purpose. It is provided "as is" without express or implied
14 * warranty.
15 *
16 * THIS SOFTWARE IS PROVIDED BY M.I.T. ``AS IS''. M.I.T. DISCLAIMS
17 * ALL EXPRESS OR IMPLIED WARRANTIES WITH REGARD TO THIS SOFTWARE,
18 * INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF
19 * MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE. IN NO EVENT
20 * SHALL M.I.T. BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
21 * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
22 * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF
23 * USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND
24 * ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
25 * OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT
26 * OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
27 * SUCH DAMAGE.
28 *
29 * From:
30 * Id: find_interface.c,v 1.1 1995/08/14 16:08:39 wollman Exp
1de703da
MD
31 *
32 * $FreeBSD: src/usr.bin/talk/get_iface.c,v 1.7 1999/08/28 01:06:12 peter Exp $
984263bc
MD
33 */
34
984263bc
MD
35#include <errno.h>
36#include <string.h>
37#include "talk.h"
38
39/*
40 * Try to find the interface address that is used to route an IP
41 * packet to a remote peer.
42 */
43
44int
1d1731fa 45get_iface(struct in_addr *dst, struct in_addr *iface)
984263bc
MD
46{
47 static struct sockaddr_in local;
48 struct sockaddr_in remote;
984263bc
MD
49 int s, rv, namelen;
50
51 memcpy(&remote.sin_addr, dst, sizeof remote.sin_addr);
52 remote.sin_port = htons(60000);
53 remote.sin_family = AF_INET;
54 remote.sin_len = sizeof remote;
55
56 local.sin_addr.s_addr = htonl(INADDR_ANY);
57 local.sin_port = htons(60000);
58 local.sin_family = AF_INET;
59 local.sin_len = sizeof local;
60
61 s = socket(PF_INET, SOCK_DGRAM, 0);
62 if (s < 0)
63 return -1;
64
65 do {
66 rv = bind(s, (struct sockaddr *)&local, sizeof local);
67 local.sin_port = htons(ntohs(local.sin_port) + 1);
68 } while(rv < 0 && errno == EADDRINUSE);
69
70 if (rv < 0) {
71 close(s);
72 return -1;
73 }
74
75 do {
76 rv = connect(s, (struct sockaddr *)&remote, sizeof remote);
77 remote.sin_port = htons(ntohs(remote.sin_port) + 1);
78 } while(rv < 0 && errno == EADDRINUSE);
79
80 if (rv < 0) {
81 close(s);
82 return -1;
83 }
84
85 namelen = sizeof local;
86 rv = getsockname(s, (struct sockaddr *)&local, &namelen);
87 close(s);
88 if (rv < 0)
89 return -1;
90
91 memcpy(iface, &local.sin_addr, sizeof local.sin_addr);
92 return 0;
93}