//
// Created by ako on 8/22/25.
//
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <unistd.h>
#include <sys/socket.h>
#include <arpa/inet.h>
#include <netinet/ip.h>
#include <netinet/if_ether.h>
#include <netpacket/packet.h>
#include <net/ethernet.h>
#include <errno.h>
#include "nethdr.h"
#include "npcap_handle.h"
#include <netpacket/packet.h>
#include <net/if.h> // if_nametoindex()

void cleanup(int socket, unsigned char* buffer) {
    close(socket);
    free(buffer);
}

int main()
{
    if (geteuid() != 0)
    {
        printf("Please run me as root.\n");
        return 1;
    }

    int sock_raw = socket(AF_PACKET, SOCK_RAW, htons(ETH_P_ALL));
    if (sock_raw < 0)
    {
        fprintf(stderr, "Unable to connect to network socket.\n");
        return -1;
    }

    unsigned char *buffer = (unsigned char *) calloc(65536, sizeof(unsigned char));

    if (buffer == NULL) {
        fprintf(stderr, "Unable to connect to allocate memory.\n");
        cleanup(sock_raw, buffer);
        return 1;
    }

    struct sockaddr_ll sourceaddr;
    socklen_t sourceaddr_len = sizeof(sourceaddr);

    int loopback_ifindex = if_nametoindex("lo");
    if (loopback_ifindex == 0) {
        perror("if_nametoindex for lo");
        cleanup(sock_raw, buffer);
        return 1;
    }

    while (1) {
        ssize_t buflen = recvfrom(sock_raw, buffer, 65536, 0, (struct sockaddr *)&sourceaddr, &sourceaddr_len);

        if (buflen == -1) {
            perror("Couldn't read from socket");
            cleanup(sock_raw, buffer);
            return 1;
        }

        if (sourceaddr.sll_ifindex == loopback_ifindex) {
            continue;
        }
        printf("\n===== Paquet reçu =====\n");
        printf("Paquet de %ld octets\n", buflen);

        // Debug
        printf("Hexdump des 32 premiers octets:\n");
        for (int i = 0; i < 32 && i < buflen; i++) {
            printf("%02x ", buffer[i]);
            if ((i + 1) % 8 == 0) printf("  ");
        }
        printf("\n");

        //
        // COUCHE 2
        //
        // Décodage entête Ethernet
        struct ethhdr *eth = (struct ethhdr *)buffer;
        handle_eth(eth);


        //
        // COUCHE 3
        //
        switch (ntohs(eth->h_proto)) 
        {
            // Décodage entête ARP
            case ETH_P_ARP:
                struct arphdr_c *arp = (struct arphdr_c *) (buffer + sizeof(struct ethhdr));
                handle_arp(arp);
                break;

            case ETH_P_IP:
                struct iphdr *ip = (struct iphdr *) (buffer + sizeof(struct ethhdr));
                handle_ip(ip);

                switch (ip->protocol) {
                    case 0x01:
                        handle_icmp();
                        break;
                    case 0x06:
                        handle_tcp();
                        break;
                    case 0x11:
                        handle_udp();
                        break;
                    default:
                        break;
                }
                
                break;
        }

        // printf("\n=======================\n");
    }
    cleanup(sock_raw, buffer);
}