/* udprecv.c
 * Simon Kirby <sim@netnation.com>, 2018-07-13
 *
 * Test IP_MULTICAST_ALL functionality.
 *
 * Compile with:
 *
 *	gcc -o udprecv udprecv.c -O2 -Wall
 */

#include <sys/types.h>
#include <sys/time.h>
#include <sys/errno.h>
#include <sys/socket.h>
#include <netinet/in.h>
#include <netdb.h>
#include <arpa/inet.h>
#include <unistd.h>
#include <fcntl.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
			 
/* Globals */

#define PAYLOAD_SIZE 65536
static char payload[PAYLOAD_SIZE];

/* Socket functions */

static int get_socket(){
	int fd,option;

	fd = socket(AF_INET,SOCK_RAW,112); // 112 == VRRP
//	fd = socket(AF_INET,SOCK_DGRAM,0);
	if (fd == -1){
		fprintf(stderr,"Unable to create datagram socket: %s\n",
			strerror(errno));
		return -1;
	}

	option = 0;
	if (setsockopt(fd,SOL_SOCKET,SO_REUSEADDR,(void *)&option,sizeof(option))){
		fprintf(stderr,"Unable to setsockopt() on udp listening socket: %s\n",
		 strerror(errno));
		return -1;
	}

	option = 0;
	setsockopt(fd,SOL_SOCKET,SO_BROADCAST,(void *)&option,sizeof(option));

	option = 1;
	setsockopt(fd,SOL_IP,IP_HDRINCL,(void *)&option,sizeof(option));

	option = 0;
	setsockopt(fd,SOL_IP,IP_MULTICAST_ALL,(void *)&option,sizeof(option));

	struct sockaddr_in udp;
	udp.sin_addr.s_addr = htonl(INADDR_ANY);
	udp.sin_port = htons(8848);
	udp.sin_family = AF_INET;
	if (bind(fd,(struct sockaddr *)&udp,sizeof(udp))){
		fprintf(stderr,"Unable to bind() udp socket: %s\n",
		 strerror(errno));
		return -1;
	}

	return fd;
}

int main(int argc,char *argv[]){
	int fd, r;
	struct sockaddr_in remote;
	socklen_t addrlen = sizeof(remote);

	fd = get_socket();
	if (fd == -1)
		exit(-1);

	while (1) {
		r = recvfrom(fd,payload,PAYLOAD_SIZE,0,(struct sockaddr *)&remote,&addrlen);
		if (r > 0) {
			fprintf(stderr, "recv %u\n", r);
		}
	}

	exit(0);
}