1/*-
2 * Copyright (c) 2015 George V. Neville-Neil
3 * All rights reserved.
4 *
5 * Redistribution and use in source and binary forms, with or without
6 * modification, are permitted provided that the following conditions
7 * are met:
8 * 1. Redistributions of source code must retain the above copyright
9 *    notice, this list of conditions and the following disclaimer.
10 * 2. Redistributions in binary form must reproduce the above copyright
11 *    notice, this list of conditions and the following disclaimer in the
12 *    documentation and/or other materials provided with the distribution.
13 *
14 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
15 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
16 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
17 * ARE DISCLAIMED.  IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
18 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
19 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
20 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
21 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
22 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
23 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
24 * SUCH DAMAGE.
25 */
26
27#include <err.h>
28#include <stdio.h>
29#include <stdlib.h>
30#include <strings.h>
31#include <sysexits.h>
32#include <unistd.h>
33
34#include <sys/socket.h>
35#include <sys/types.h>
36#include <netinet/in.h>
37
38#define PORT 6969 /* Default port */
39#define LISTEN 5  /* Default backlog */
40#define RECV_LIMIT 64 /* When do we move listen to 0? */
41
42void usage(void);
43
44void usage()
45{
46	err(EX_USAGE, "listen [-p port] [-l limit]\n");
47}
48
49int main(int argc, char **argv)
50{
51
52	int ch, srv_sock, cli_sock, recvd = 0;
53	int port = PORT;
54	int limit = LISTEN;
55	struct sockaddr_in localaddr;
56
57	while ((ch = getopt(argc, argv, "p:l:")) != -1) {
58		switch (ch) {
59		case 'p':
60			port = atoi(optarg);
61			break;
62		case 'l':
63			limit = atoi(optarg);
64                     break;
65		case 'h':
66		default:
67			usage();
68		}
69	}
70
71	bzero(&localaddr, sizeof(localaddr));
72	localaddr.sin_len = sizeof(localaddr);
73	localaddr.sin_family = AF_INET;
74	localaddr.sin_port = htons(port);
75	localaddr.sin_addr.s_addr = INADDR_ANY;
76
77	srv_sock = socket(AF_INET, SOCK_STREAM, 0);
78
79	if (bind(srv_sock, (struct sockaddr *)&localaddr,
80		 sizeof(struct sockaddr_in)) < 0)
81		err(EX_OSERR, "Could not bind to INADDR_ANY:%d", port);
82
83	if (listen(srv_sock, limit) < 0)
84		err(EX_OSERR, "Failed to listen with depth of %d\n", limit);
85
86	while (((cli_sock = accept(srv_sock, NULL, NULL)) >= 0)
87	       && (recvd < RECV_LIMIT)) {
88		close(cli_sock);
89		recvd++;
90	}
91
92	listen(srv_sock, 0);
93
94	while (((cli_sock = accept(srv_sock, NULL, NULL)) >= 0)
95	    && (recvd <= (RECV_LIMIT + limit + 1))) {
96		close(cli_sock);
97		recvd++;
98	}
99
100	if (accept(srv_sock, NULL, NULL) >= 0)
101		printf ("Late connection at %d\n", recvd);
102	else
103		printf("recvd %d\n", recvd);
104}
105