#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <unistd.h>
#include <errno.h>
#include <sys/socket.h>
#include <netinet/in.h>
#include <arpa/inet.h>
#include <linux/mroute.h>

void die(const char *s) {
    perror(s);
    exit(1);
}

int main(int argc, char *argv[]) {
    if (argc != 3) {
        fprintf(stderr, "Usage: %s <input_if_index> <output_if_index>\n", argv[0]);
        exit(1);
    }

    int sock = socket(AF_INET, SOCK_RAW, IPPROTO_IGMP);
    if (sock < 0) {
        die("socket");
    }

    if (setsockopt(sock, IPPROTO_IP, MRT_INIT, &(int){1}, sizeof(int)) < 0) {
        die("setsockopt MRT_INIT");
    }

    struct vifctl vc_in;
    memset(&vc_in, 0, sizeof(vc_in));
    vc_in.vifc_vifi = 0;
    vc_in.vifc_flags = VIFF_USE_IFINDEX;
    vc_in.vifc_lcl_ifindex = atoi(argv[1]);
    if (setsockopt(sock, IPPROTO_IP, MRT_ADD_VIF, &vc_in, sizeof(vc_in)) < 0) {
        die("setsockopt MRT_ADD_VIF 0");
    }

    struct vifctl vc_out;
    memset(&vc_out, 0, sizeof(vc_out));
    vc_out.vifc_vifi = 1;
    vc_out.vifc_flags = VIFF_USE_IFINDEX;
    vc_out.vifc_lcl_ifindex = atoi(argv[2]);
    if (setsockopt(sock, IPPROTO_IP, MRT_ADD_VIF, &vc_out, sizeof(vc_out)) < 0) {
        die("setsockopt MRT_ADD_VIF 1");
    }

    struct mfcctl mfc;
    memset(&mfc, 0, sizeof(mfc));
    mfc.mfcc_origin.s_addr = inet_addr("192.168.1.1");
    mfc.mfcc_mcastgrp.s_addr = inet_addr("239.1.2.3");
    mfc.mfcc_parent = 0;
    mfc.mfcc_ttls[1] = 1;
    if (setsockopt(sock, IPPROTO_IP, MRT_ADD_MFC, &mfc, sizeof(mfc)) < 0) {
        die("setsockopt MRT_ADD_MFC");
    }

    printf("[C Tool] SUCCESS: VIFs and MFC entry added. Holding for 10s...\n");
    sleep(10);

    if (setsockopt(sock, IPPROTO_IP, MRT_DEL_MFC, &mfc, sizeof(mfc)) < 0) {
        die("setsockopt MRT_DEL_MFC");
    }

    if (setsockopt(sock, IPPROTO_IP, MRT_DEL_VIF, &vc_in, sizeof(vc_in)) < 0) {
        die("setsockopt MRT_DEL_VIF 0");
    }

    if (setsockopt(sock, IPPROTO_IP, MRT_DEL_VIF, &vc_out, sizeof(vc_out)) < 0) {
        die("setsockopt MRT_DEL_VIF 1");
    }

    if (setsockopt(sock, IPPROTO_IP, MRT_DONE, NULL, 0) < 0) {
        die("setsockopt MRT_DONE");
    }

    close(sock);

    return 0;
}