1*570de052Spamela /* $OpenBSD: srcaddr.c,v 1.1 2020/04/13 03:09:29 pamela Exp $ */
2*570de052Spamela
3*570de052Spamela /*
4*570de052Spamela * Copyright (c) 2020 Pamela Mosiejczuk <pamela@openbsd.org>
5*570de052Spamela * Copyright (c) 2020 Florian Obser <florian@openbsd.org>
6*570de052Spamela *
7*570de052Spamela * Permission to use, copy, modify, and distribute this software for any
8*570de052Spamela * purpose with or without fee is hereby granted, provided that the above
9*570de052Spamela * copyright notice and this permission notice appear in all copies.
10*570de052Spamela *
11*570de052Spamela * THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
12*570de052Spamela * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
13*570de052Spamela * MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
14*570de052Spamela * ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
15*570de052Spamela * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
16*570de052Spamela * ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
17*570de052Spamela * OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
18*570de052Spamela */
19*570de052Spamela
20*570de052Spamela #include <sys/types.h>
21*570de052Spamela #include <sys/socket.h>
22*570de052Spamela
23*570de052Spamela #include <err.h>
24*570de052Spamela #include <netdb.h>
25*570de052Spamela #include <stdio.h>
26*570de052Spamela #include <stdlib.h>
27*570de052Spamela #include <string.h>
28*570de052Spamela #include <unistd.h>
29*570de052Spamela
30*570de052Spamela __dead void usage(void);
31*570de052Spamela
32*570de052Spamela /* given an IPv6 destination address, return the source address selected */
33*570de052Spamela int
main(int argc,char * argv[])34*570de052Spamela main(int argc, char *argv[])
35*570de052Spamela {
36*570de052Spamela struct addrinfo hints, *res;
37*570de052Spamela struct sockaddr_storage ss;
38*570de052Spamela socklen_t len;
39*570de052Spamela int ch, error, s;
40*570de052Spamela char *target, src[NI_MAXHOST];
41*570de052Spamela
42*570de052Spamela while ((ch = getopt(argc, argv, "")) != -1) {
43*570de052Spamela switch (ch) {
44*570de052Spamela default:
45*570de052Spamela usage();
46*570de052Spamela }
47*570de052Spamela }
48*570de052Spamela argc -= optind;
49*570de052Spamela argv += optind;
50*570de052Spamela
51*570de052Spamela if (argc != 1)
52*570de052Spamela usage();
53*570de052Spamela
54*570de052Spamela target = *argv;
55*570de052Spamela
56*570de052Spamela memset(&hints, 0, sizeof(hints));
57*570de052Spamela hints.ai_flags = AI_NUMERICHOST | AI_NUMERICSERV;
58*570de052Spamela hints.ai_family = AF_INET6;
59*570de052Spamela hints.ai_socktype = SOCK_DGRAM;
60*570de052Spamela
61*570de052Spamela if ((error = getaddrinfo(target, "8888", &hints, &res)))
62*570de052Spamela errx(1, "%s", gai_strerror(error));
63*570de052Spamela
64*570de052Spamela s = socket(res->ai_family, res->ai_socktype, res->ai_protocol);
65*570de052Spamela if (s == -1)
66*570de052Spamela err(1, "socket");
67*570de052Spamela
68*570de052Spamela if (connect(s, res->ai_addr, res->ai_addrlen) == -1)
69*570de052Spamela err(1, "connect");
70*570de052Spamela freeaddrinfo(res);
71*570de052Spamela
72*570de052Spamela len = sizeof(ss);
73*570de052Spamela if (getsockname(s, (struct sockaddr *)&ss, &len) == -1)
74*570de052Spamela err(1, "getsockname");
75*570de052Spamela
76*570de052Spamela if ((error = getnameinfo((struct sockaddr *)&ss, ss.ss_len, src,
77*570de052Spamela sizeof(src), NULL, 0, NI_NUMERICHOST | NI_NUMERICSERV)))
78*570de052Spamela errx(1, "%s", gai_strerror(error));
79*570de052Spamela
80*570de052Spamela printf("%s\n", src);
81*570de052Spamela
82*570de052Spamela return (0);
83*570de052Spamela }
84*570de052Spamela
85*570de052Spamela __dead void
usage(void)86*570de052Spamela usage(void)
87*570de052Spamela {
88*570de052Spamela fprintf(stderr, "usage: srcaddr destination\n");
89*570de052Spamela exit (1);
90*570de052Spamela }
91