#include <pcap.h>
#include <stdio.h>
#include <stdlib.h>

void got_packet(u_char *args, const struct pcap_pkthdr *header, const u_char *packet) {
    printf("Got a packet\n");
}

int main() {
    pcap_t *handle;
    char errbuf[PCAP_ERRBUF_SIZE];
    struct bpf_program fp;
    char filter_exp[] = "icmp";
    bpf_u_int32 net;

    // Step 1: Open pcap session on the interface
    handle = pcap_open_live("br-c031fbf1a197", BUFSIZ, 1, 1000, errbuf);
    if (handle == NULL) {
        fprintf(stderr, "Couldn't open device: %s\n", errbuf);
        return 2;
    }

    // Step 2: Compile filter_exp into BPF code
    if (pcap_compile(handle, &fp, filter_exp, 0, net) == -1) {
        fprintf(stderr, "Couldn't parse filter %s: %s\n", filter_exp, pcap_geterr(handle));
        return 2;
    }
    if (pcap_setfilter(handle, &fp) == -1) {
        fprintf(stderr, "Couldn't install filter %s: %s\n", filter_exp, pcap_geterr(handle));
        return 2;
    }

    // Step 3: Capture packets
    printf("Sniffing ICMP packets using C and libpcap...\n");
    pcap_loop(handle, -1, got_packet, NULL);

    pcap_close(handle);
    return 0;
}