#include <sys/types.h>
#include <sys/socket.h>
#include <netinet/in.h>
#include <net/bpf.h>
#include <errno.h>

int main(int argc, char **argv)
{
	struct sockaddr_in sin;
	struct bpf_program bp;
	struct bpf_insn buf[10];
	char rcvbuf[2000];
	int i = 0;
	int fd;

	fd = socket(AF_INET, SOCK_DGRAM, IPPROTO_UDP);
	if (fd < 0) {
		perror("socket");
		exit(1);
	}

	memset(buf, 0, sizeof(buf));

	buf[i].code = BPF_LDX|BPF_B|BPF_MSH;
	buf[i].k    = (1<<31) + (1<<29);
	i++;
	
	buf[i].code = BPF_RET;
	i++;

	bp.bf_len = i;
	bp.bf_insns = buf;

	if (setsockopt(fd, SOL_SOCKET, SO_ATTACH_FILTER, &bp, sizeof(bp)) < 0) {
		perror("setsockopt");
		exit(1);
	}

	sin.sin_family      = AF_INET;
	sin.sin_addr.s_addr = INADDR_ANY;
	sin.sin_port        = htons(10000);

	if (bind(fd, (struct sockaddr *)&sin, sizeof(sin)) < 0) {
		perror("bind");
		exit(1);
	}

	if (recvfrom(fd, rcvbuf, sizeof(rcvbuf), 0, NULL, 0) < 0) {
		perror("recvfrom");
		exit(1);
	}
}