simple ip calculator

network-calculator.cpp

#include <iostream>
#include <cstdlib>
#include <cstdio>
#include <arpa/inet.h>
#include <getopt.h>
#include <sys/types.h>

static unsigned char short_opts[] = "i:n:";

static struct option long_options[] = {
  {"ip",        required_argument, 0, 'i'},
  {"netmask",   required_argument, 0, 'n'},
};

int main(int argc, char** argv){

  struct in_addr ip;
  struct in_addr netmask;

  int long_index = 0;
  while(true){
    auto c = getopt_long(argc, argv, (char*)short_opts, long_options, &long_index);
    if( c == -1 ){ break; }
    switch(c){
      case 'i':
        inet_aton(optarg, &ip);
        break;
      case 'n':
        inet_aton(optarg, &netmask);
        break;
      default:
        break;
    }
  }


  int subnet_ones = 0;

  u_int32_t n = (u_int32_t)netmask.s_addr;
  while(n){
    subnet_ones += n & 0x1u;
    n >>= 1;
  }
  struct in_addr network;
  network.s_addr = ip.s_addr & netmask.s_addr;

  struct in_addr broadcast;
  broadcast.s_addr = ip.s_addr | ~(netmask.s_addr);

  printf("network:\t %s/%d\n", inet_ntoa(network), subnet_ones);
  printf("broadcast:\t %s\n", inet_ntoa(broadcast)); 

  
  return 0;
}