check_alive.c

// check_alive by Rodizio. Checks for incoming wifibroadcast packets. GPL2 licensed.
#include <stdio.h>
#include <stdlib.h>
#include <errno.h>
#include <resolv.h>
#include <string.h>
#include <utime.h>
#include <unistd.h>
#include <getopt.h>
#include <pcap.h>
#include <endian.h>
#include <fcntl.h>
#include <sys/mman.h>
#include "lib.h"

wifibroadcast_rx_status_t *status_memory_open(void) {
	int fd;

	for(;;) {
		fd = shm_open("/wifibroadcast_rx_status_0", O_RDWR, S_IRUSR | S_IWUSR);
		if(fd > 0) { break; }
		usleep(100000);
	}

	if (ftruncate(fd, sizeof(wifibroadcast_rx_status_t)) == -1) {
		perror("ftruncate");
		exit(1);
	}

	void *retval = mmap(NULL, sizeof(wifibroadcast_rx_status_t), PROT_READ | PROT_WRITE, MAP_SHARED, fd, 0);
	if (retval == MAP_FAILED) {
		perror("mmap");
		exit(1);
	}
	
	return (wifibroadcast_rx_status_t*)retval;
}


int main(int argc, char *argv[]) {
    int packets1 = 0;
    int packets2 = 0;

    wifibroadcast_rx_status_t *t = status_memory_open();

    packets1 = t->received_packet_cnt;
    usleep(900000);
    packets2 = t->received_packet_cnt;

//    printf("Packets1:%d, Packets2:%d\n",packets1,packets2);

    if (packets1 == packets2) {
        printf("0\n");
    } else {
        printf("1\n");
    }
    return 0;
}