utils.c

//
// Created by Ben on 7/21/22.
//

#include "utils.h"
#include <sys/socket.h>
#include <arpa/inet.h>
#include <stdint.h>
#include <string.h>

void layer2_fill_with_broadcast_mac(char *mac_array){
    mac_array[0] = 0xFF;
    mac_array[1] = 0xFF;
    mac_array[2] = 0xFF;
    mac_array[3] = 0xFF;
    mac_array[4] = 0xFF;
    mac_array[5] = 0xFF;
}

void apply_mask(char *prefix, char mask, char *str_prefix){

    uint32_t binary_prefix = 0;
    uint32_t subnet_mask = 0xFFFFFFFF;

    if(mask == 32){
        strncpy(str_prefix, prefix, 16);
        str_prefix[15] = '\0';
        return;
    }
    /*Convert Given IP address into binary format*/
    inet_pton(AF_INET, prefix, &binary_prefix);
    binary_prefix = htonl(binary_prefix);

    /*Compute Mask in binary format as well*/
    subnet_mask = subnet_mask << (32 - mask);

    /*Perform logical AND to apply mask on IP address*/
    binary_prefix = binary_prefix & subnet_mask;

    /*Convert the Final IP into string format again*/
    binary_prefix = htonl(binary_prefix);
    inet_ntop(AF_INET, &binary_prefix, str_prefix, 16);
    str_prefix[15] = '\0';
}

char *tcp_ip_covert_ip_n_to_p(uint32_t ip_addr, char *output_buffer){
    char *out = NULL;
    static char str_ip[16];
    out = !output_buffer ? str_ip : output_buffer;
    memset(out, 0, 16);
    ip_addr = htonl(ip_addr);
    inet_ntop(AF_INET, &ip_addr, out, 16);
    out[15] = '\0';
    return out;
}

uint32_t tcp_ip_covert_ip_p_to_n(char *ip_addr){
    uint32_t binary_prefix = 0;
    inet_pton(AF_INET, ip_addr, &binary_prefix);
    binary_prefix = htonl(binary_prefix);
    return binary_prefix;
}