#include <sys/types.h>
#include <sys/socket.h>
#include <netinet/in.h>
#include <unistd.h>
#include <stdio.h>
#include <stdlib.h>
#include <errno.h>
#include <string.h>
#include <time.h>
#include <sys/time.h>
#include <arpa/inet.h>
#include <signal.h>
#include <net/if.h>

#define E(x, y) if ((x) y) { fprintf(stderr, "%s:%d %s()\n\t%s\n[%d] %s\n", \
	__FILE__, __LINE__, __func__, #x, errno, strerror(errno)); exit(1); }

#ifndef MGROUP_DEFAULT
#define MGROUP_DEFAULT "233.252.88.24"
#endif
#ifndef MPORT_DEFAULT
#define MPORT_DEFAULT 31338
#endif


void usage(int status)
{
	FILE *out = status ? stderr : stdout;
	fprintf(out, "usage: mcrecv [-l <interface address>] [-b <bindaddress>] [-p <udp port>]\n"
		"\t[-i <interface name> | -s <source>] [<multicast group>]\n"
		"\n"
		"default:\n"
		"\t(-i none) -l 0.0.0.0 -b 0.0.0.0 -p %d (-s none) " MGROUP_DEFAULT "\n",
		MPORT_DEFAULT);
	exit(1);
}

struct in_addr maddr;
unsigned numpkts = 0;
unsigned bytes = 0;

void sigint(int signal)
{
	printf("--- %s beacon statistics ---\n"
		"%d packets received, %d bytes total\n",
		inet_ntoa(maddr), numpkts, bytes);
	exit(0);
}

void loop(int sock)
{
	struct sockaddr_in from;
	socklen_t fromlen;
	char buf[2048];
	ssize_t size;

	signal(SIGINT, sigint);

	fromlen = sizeof(from);
	while ((size = recvfrom(sock, buf, sizeof(buf) - 1, 0, (struct sockaddr *)&from, &fromlen)) > 0) {
		buf[size] = '\0';
		printf("%ld bytes from %s:%d: %s\n",
			size, inet_ntoa(from.sin_addr), ntohs(from.sin_port), buf);

		bytes += size;
		numpkts++;
		
		fromlen = sizeof(from);
	}
	E("read",);
}

int main(int argc, char **argv)
{
	struct sockaddr_in rcvr;
	struct in_addr laddr = { INADDR_ANY };
	struct in_addr saddr = { INADDR_ANY };
	int sock;
	int c, ifindex = 0;
	int one = 1;

	maddr.s_addr = inet_addr(MGROUP_DEFAULT);

	rcvr.sin_family = AF_INET;
	rcvr.sin_port = htons(MPORT_DEFAULT);
	rcvr.sin_addr.s_addr = INADDR_ANY;

	while (1) {
		c = getopt(argc, argv, "i:l:b:p:s:h");
		if (c == -1)
			break;
		switch (c) {
		case 'b':
			if (!inet_aton(optarg, &rcvr.sin_addr)) {
				fprintf(stderr, "invalid address %s\n", optarg);
				return 1;
			}
			break;
		case 'l':
			if (!inet_aton(optarg, &laddr)) {
				fprintf(stderr, "invalid address %s\n", optarg);
				return 1;
			}
			break;
		case 's':
			if (ifindex) {
				fprintf(stderr, "can't combine -s and -i\n"
					"(interface is looked up from routing table for SSM joins)\n");
				return 1;
			}
			if (!inet_aton(optarg, &saddr)) {
				fprintf(stderr, "invalid address %s\n", optarg);
				return 1;
			}
			break;
		case 'i':
			if (saddr.s_addr) {
				fprintf(stderr, "can't combine -l and -i\n"
					"(interface is looked up from routing table for SSM joins)\n");
				return 1;
			}
			ifindex = if_nametoindex(optarg);
			if (ifindex <= 0) {
				fprintf(stderr, "invalid interface name %s\n", optarg);
				return 1;
			}
			break;
		case 'p':
			rcvr.sin_port = htons(atoi(optarg));
			break;
		case 'h':
			usage(0);
		case 0:
		default:
			usage(1);
		}
	}

	if (optind < argc - 1) {
		fprintf(stderr, "too many arguments\n");
		return 1;
	}
	if (optind < argc) {
		if (!inet_aton(argv[optind], &maddr)) {
			fprintf(stderr, "invalid address %s\n", optarg);
			return 1;
		}
	}

	E(sock = socket(AF_INET, SOCK_DGRAM, 0), == -1);
	E(setsockopt(sock, SOL_SOCKET, SO_REUSEADDR, &one, sizeof(one)), );
	E(bind(sock, (struct sockaddr *)&rcvr, sizeof(rcvr)), );

	if (saddr.s_addr) {
		struct ip_mreq_source req;
		char buf0[16], buf1[16], buf2[16];
		strcpy(buf0, inet_ntoa(maddr));
		strcpy(buf1, inet_ntoa(saddr));
		strcpy(buf2, laddr.s_addr ? inet_ntoa(laddr) : "*");
		printf("BEACON (%s,%s) on %s\n", buf0, buf1, buf2);
		req.imr_multiaddr.s_addr = maddr.s_addr;
		req.imr_interface.s_addr = laddr.s_addr;
		req.imr_sourceaddr.s_addr = saddr.s_addr;
		E(setsockopt(sock, SOL_IP, IP_ADD_SOURCE_MEMBERSHIP, &req, sizeof(req)), );
	} else {
		struct ip_mreqn req;
		char buf0[16], buf1[16], buf2[16];
		strcpy(buf0, inet_ntoa(maddr));
		strcpy(buf1, laddr.s_addr ? inet_ntoa(laddr) : "*");
		printf("BEACON (%s,*) on %s%%%s\n", buf0, buf1, ifindex ? if_indextoname(ifindex, buf2) : "*");
		req.imr_multiaddr.s_addr = maddr.s_addr;
		req.imr_address.s_addr = laddr.s_addr;
		req.imr_ifindex = ifindex;
		E(setsockopt(sock, SOL_IP, IP_ADD_MEMBERSHIP, &req, sizeof(req)), );
	}

	loop(sock);
	
	E(close(sock),);
	return 0;
}