#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <stdarg.h>
#include <unistd.h>
#include <fcntl.h>
#include <errno.h>

#include <sys/socket.h>
#include <netdb.h>
#include <netinet/in.h>
#include <netinet6/in6.h>
#include <err.h>
#include <arpa/inet.h>

#include "sockfromto.h"

int listenudp(char *service, int family, char *bindaddr);
void usage(void);
int main(int argc, char *argv[]);


int
listenudp(service, family, bindaddr)
char *service;
int family;
char *bindaddr;
{
	int s;
	struct addrinfo hints;
	struct addrinfo *res;
	int rc, on;

	s = socket(family, SOCK_DGRAM, 0);

	on = 1;
	setsockopt(s, SOL_SOCKET, SO_REUSEADDR, (void *)&on, sizeof(on));

	memset(&hints, 0, sizeof(hints));
	hints.ai_family = family;
	hints.ai_flags = AI_PASSIVE;
	hints.ai_socktype = SOCK_DGRAM;
	rc = getaddrinfo(bindaddr, service, &hints, &res);
	if (rc) {
		errx(1, "getaddrinfo: %s: %s", service, gai_strerror(rc));
		exit(1);
	}

	rc = bind(s, (struct sockaddr *)res->ai_addr, res->ai_addrlen);
	if (rc < 0) {
		shutdown(s, 2);
		close(s);
		err(1, "bind");
	}

	return s;
}



void
usage()
{
	printf("usage: listen [opt] listen-port\n");
	printf("	-4	Use IPv4 only\n");
	printf("	-6	Use IPv6 only\n");
	exit(0);
}



int opt_4;
int opt_6;

int
main(argc, argv)
int argc;
char *argv[];
{
	int ch;
	int socket4, socket6, client;
	char *portp;

	while ((ch = getopt(argc, argv, "46")) != -1) {
		switch (ch) {
		case '4':
			opt_4 = 1;
			break;
		case '6':
			opt_6 = 1;
			break;
		case '?':
		default:
			usage();
		}
	}
	argc -= optind;
	argv += optind;

	if (argc != 1)
		usage();

	portp = argv[0];

	if (!(opt_4 || opt_6))
		opt_4 = opt_6 = 1;

	socket4 = socket6 = 0;
	if (opt_4) {
		socket4 = listenudp(portp, AF_INET, NULL);
		printf("starting UDP: listening port %s\n", portp);
	}
	if (opt_6) {
		socket6 = listenudp(portp, AF_INET6, NULL);
		printf("starting UDP6: listening port %s\n", portp);
	}



	if (setsockoptfromto(socket4) < 0)
		err(1, "setsockopt");
	if (setsockoptfromto(socket6) < 0)
		err(1, "setsockopt");


	while (1) {
		int nfds, nfound;
		fd_set readfds;

#define max(a, b)	(((a) > (b)) ? (a) : (b))
		nfds = max(socket4, socket6) + 1;

		for (;;) {
			FD_ZERO(&readfds);
			if (opt_4)
				FD_SET(socket4, &readfds);
			if (opt_6)
				FD_SET(socket6, &readfds);

			nfound = select(nfds, &readfds, NULL, NULL, NULL);
			if (nfound < 0)
				err(1, "select: ");

			if (FD_ISSET(socket4, &readfds)) {
				client = socket4;
				break;
			}

			if (FD_ISSET(socket6, &readfds)) {
				client = socket6;
				break;
			}
		}

		{
			char buf[1024];
			struct sockaddr_storage remote;
			struct sockaddr_storage local;
			socklen_t remote_len = sizeof(remote);
			socklen_t local_len = sizeof(local);
			int rc;

			memset(&remote, 0, sizeof(remote));
			memset(&local, 0, sizeof(local));

			if (1) {
				rc = recvfromto(client, (void*)buf, sizeof(buf), 0,
				    (struct sockaddr *)&remote, &remote_len,
				    (struct sockaddr *)&local, &local_len);

				if (rc > 0)
					buf[rc] = '\0';
				printf("recvfromto: %d bytes received (\"%s\")\n", rc, buf);
				printf("          : from %s\n", remote_len ? strsockaddr((struct sockaddr *)&remote) : "unknown");
				printf("          : to   %s\n", local_len ? strsockaddr((struct sockaddr *)&local) : "unknown");

				if (rc > 0) {
					rc = sendfromto(client, buf, rc, 0, (struct sockaddr *)&local, (struct sockaddr *)&remote);
					if (rc < 0)
						err(1, "sendfromto: ");
				}
			}
		}
	}

	return 0;
}