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/* $OpenBSD: srcaddr.c,v 1.1 2020/04/13 03:09:29 pamela Exp $ */
/*
* Copyright (c) 2020 Pamela Mosiejczuk <pamela@openbsd.org>
* Copyright (c) 2020 Florian Obser <florian@openbsd.org>
*
* Permission to use, copy, modify, and distribute this software for any
* purpose with or without fee is hereby granted, provided that the above
* copyright notice and this permission notice appear in all copies.
*
* THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
* WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
* MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
* ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
* WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
* ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
* OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
*/
#include <sys/types.h>
#include <sys/socket.h>
#include <err.h>
#include <netdb.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <unistd.h>
__dead void usage(void);
/* given an IPv6 destination address, return the source address selected */
int
main(int argc, char *argv[])
{
struct addrinfo hints, *res;
struct sockaddr_storage ss;
socklen_t len;
int ch, error, s;
char *target, src[NI_MAXHOST];
while ((ch = getopt(argc, argv, "")) != -1) {
switch (ch) {
default:
usage();
}
}
argc -= optind;
argv += optind;
if (argc != 1)
usage();
target = *argv;
memset(&hints, 0, sizeof(hints));
hints.ai_flags = AI_NUMERICHOST | AI_NUMERICSERV;
hints.ai_family = AF_INET6;
hints.ai_socktype = SOCK_DGRAM;
if ((error = getaddrinfo(target, "8888", &hints, &res)))
errx(1, "%s", gai_strerror(error));
s = socket(res->ai_family, res->ai_socktype, res->ai_protocol);
if (s == -1)
err(1, "socket");
if (connect(s, res->ai_addr, res->ai_addrlen) == -1)
err(1, "connect");
freeaddrinfo(res);
len = sizeof(ss);
if (getsockname(s, (struct sockaddr *)&ss, &len) == -1)
err(1, "getsockname");
if ((error = getnameinfo((struct sockaddr *)&ss, ss.ss_len, src,
sizeof(src), NULL, 0, NI_NUMERICHOST | NI_NUMERICSERV)))
errx(1, "%s", gai_strerror(error));
printf("%s\n", src);
return (0);
}
__dead void
usage(void)
{
fprintf(stderr, "usage: srcaddr destination\n");
exit (1);
}
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