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/* $OpenBSD: nonxt-reflect.c,v 1.2 2018/05/21 01:19:21 bluhm Exp $ */
/*
* Copyright (c) Alexander Bluhm <bluhm@genua.de>
*
* 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 <netdb.h>
#include <err.h>
#include <errno.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <unistd.h>
void __dead usage(void);
void
usage(void)
{
fprintf(stderr, "usage: nonxt-reflect localaddr\n"
"Daemonize, wait for protocol 59 packets, and answer them.\n");
exit(1);
}
int
main(int argc, char *argv[])
{
struct addrinfo hints, *res, *res0;
const char *cause = NULL, *local;
int error;
int save_errno;
int s;
char buf[1024];
switch (argc) {
case 2:
local = argv[1];
break;
default:
usage();
}
if (pledge("stdio inet dns proc", NULL) == -1)
err(1, "pledge");
/* Create socket and bind it to local address. */
memset(&hints, 0, sizeof(hints));
hints.ai_family = AF_UNSPEC;
hints.ai_socktype = SOCK_RAW;
hints.ai_protocol = IPPROTO_NONE;
hints.ai_flags = AI_PASSIVE;
error = getaddrinfo(local, NULL, &hints, &res0);
if (error)
errx(1, "getaddrinfo local: %s", gai_strerror(error));
for (res = res0; res; res = res->ai_next) {
s = socket(res->ai_family, res->ai_socktype, res->ai_protocol);
if (s == -1) {
cause = "socket";
continue;
}
if (bind(s, res->ai_addr, res->ai_addrlen) == -1) {
cause = "bind";
save_errno = errno;
close(s);
errno = save_errno;
continue;
}
break;
}
if (res == NULL)
err(1, "%s", cause);
freeaddrinfo(res0);
/* Socket is ready to receive, parent process may proceed. */
daemon(1, 1);
if (pledge("stdio inet", NULL) == -1)
err(1, "pledge");
for (;;) {
struct sockaddr_storage ss;
socklen_t slen;
/* Receive a protocol 59 packet. */
slen = sizeof(ss);
if (recvfrom(s, buf, sizeof(buf), 0, (struct sockaddr *)&ss,
&slen) == -1)
err(1, "recv");
/* Send back a reply packet. */
if (sendto(s, buf, 0, 0, (struct sockaddr *)&ss, slen) == -1)
err(1, "send");
}
/* NOTREACHED */
return 0;
}
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