/*-
 * SPDX-License-Identifier: BSD-2-Clause
 *
 * Copyright (c) 2022 Bjoern A. Zeeb
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in the
 *    documentation and/or other materials provided with the distribution.
 *
 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
 * ARE DISCLAIMED.  IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
 * SUCH DAMAGE.
 */
#include <sys/types.h>
#include <sys/socket.h>
#include <netinet/in.h>
#include <arpa/inet.h>

#include <err.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <sysexits.h>
#include <unistd.h>

static void
getaddrport(const char *a, const char *p, struct sockaddr_in *sin)
{
	const char *errstr;
	long long l;
	int rc;

	if (sin->sin_family != AF_INET)
		errx(EX_SOFTWARE, "Only AF_INET supported currently\n");

	rc = inet_pton(sin->sin_family, a, &sin->sin_addr);
	switch (rc) {
	case 1:
		break;
	case 0:
		errx(EX_DATAERR, "IPv4 address '%s' not parseable\n", a);
		/* NOT REACHED */
	case -1:
		err(EX_OSERR, "inet_pton failed\n");
		/* NOT REACHED */
	default:
		errx(EX_SOFTWARE, "inet_pton returned %d\n", rc);
		/* NOT REACHED */
	}

	errstr = NULL;
	l = strtonum(p, 1, 65535, &errstr);
	if (l == 0 && errstr != NULL)
		err(EX_USAGE, "strtonum returned '%s'\n", errstr);
	sin->sin_port = htons((in_port_t)l);
}

int
main(int argc, char *argv[])
{
	struct sockaddr_in laddr4, faddr4;
	int rc, s, sopt;

	if (argc != 3 && argc != 5)
		errx(EX_USAGE, "usage: %s <laddr4> <lport 1..> [<faddr4> <fport 1..>]\n", argv[0]);

	memset(&laddr4, 0, sizeof(laddr4));
	laddr4.sin_len = sizeof(laddr4);
	laddr4.sin_family = AF_INET;

	memset(&faddr4, 0, sizeof(faddr4));
	faddr4.sin_len = sizeof(faddr4);
	faddr4.sin_family = AF_INET;

	getaddrport(argv[1], argv[2], &laddr4);
	if (argc == 5)
		getaddrport(argv[3], argv[4], &faddr4);

	s = socket(PF_INET, SOCK_STREAM, 0);
	if (s == -1)
		err(EX_UNAVAILABLE, "socket\n");
	
	sopt = 1;
	rc = setsockopt(s, SOL_SOCKET, SO_REUSEPORT, &sopt, sizeof(sopt));
	if (rc == -1)
		err(EX_UNAVAILABLE, "setsockopt\n");
	
	rc = bind(s, (const struct sockaddr *)&laddr4, sizeof(laddr4));
	if (rc == -1)
		err(EX_UNAVAILABLE, "bind\n");

	if (argc == 3) {
		rc = listen(s, 1000);
		if (rc == -1)
			err(EX_UNAVAILABLE, "listen\n");

		printf("%s pid %d listening on [%s %u]\n", argv[0], getpid(),
		    inet_ntoa(laddr4.sin_addr), ntohs(laddr4.sin_port));

		do {
			socklen_t flen;

			flen = sizeof(faddr4);
			rc = accept(s, (struct sockaddr *)&faddr4, &flen);
			if (rc == -1)
				err(EX_UNAVAILABLE, "accept\n");

			if (flen == sizeof(faddr4))
				printf("%s pid %d accepted [%s %u]\n", argv[0], getpid(),
				    inet_ntoa(faddr4.sin_addr), ntohs(faddr4.sin_port));
			else {
				printf("%s pid %d accepted connection\n", argv[0], getpid());
				rc = -1;
			}
		} while (rc != -1);
	}
	if (argc == 5) {
		rc = connect(s, (const struct sockaddr *)&faddr4, sizeof(faddr4));
		if (rc == -1)
			err(EX_UNAVAILABLE, "connect\n");
	}

	printf("%s pid %d [%s %u] sleeping 60.\n", argv[0], getpid(), argv[1], ntohs(laddr4.sin_port));
	sleep(60);
	printf("%s pid %d done.\n", argv[0], getpid());

	close(s);

	return (0);
}