Would like some feedback on my first somewhat useful program (Subnet Calculator)

**digital_alchemy** · 07-20-2010

Hi all....

as part of our training we had to develop a subnet calculator; I feel that I'm pretty much done with it, just needs some fine tuning.

one issue specificly that I'm looking for feedback on is the validation of the IP address. I know there must be a better way of doing it that I'm currently using but I'm just not quite sure how.

Currently it works fine; except when the user inputs an IP address they can enter too many fields and incorrect seperators.

ex. 12.23.34.45.56.67 will be saved as 12.23.34.45/56
12/23/34/45/56 will be saved as 12.23.34.45/56

I'm not really sure how to force them to enter the information in the proper format.

here is the code ( warning it's kinda long... but it's my first attempt and didn't wanna focus on making in smaller until i get it working exactly the way i want )

platform: windows platform using code blocks as the IDE

Thanks for any help

Code:

#include <stdio.h>
#include <math.h>
#include <stdlib.h>
#include <windows.h>
#include <conio.h>

/******************************************************
DECLARE VARIABLES
*******************************************************/
int oct1, oct2, oct3, oct4, cidr;
int noct1=0, noct2=0, noct3=0, noct4=0;
int boct1=255, boct2=255, boct3=255, boct4=255;
int mask1=0, mask2=0, mask3=0, mask4=0;
int netbits=0,bitsbor, maskSum, hostbits, netinc, cond, ans, hosts, nets, i;
char classtype;

/******************************************************
START MAIN PROGRAM
*******************************************************/
int main (void)  {

    HANDLE  hConsole;
    hConsole = GetStdHandle(STD_OUTPUT_HANDLE);

    #define BLACK 0
    #define BLUE 1
    #define GREEN 2
    #define CYAN 3
    #define RED 4
    #define MAGENTA 5
    #define BROWN 6
    #define LIGHTGREY 7
    #define DARKGREY 8
    #define LIGHTBLUE 9
    #define LIGHTGREEN 10
    #define LIGHTCYAN 11
    #define LIGHTRED 12
    #define LIGHTMAGENTA 13
    #define YELLOW 14
    #define WHITE 15
    #define BLINK 128

/******************************************************
GET USER INPUT
*******************************************************/
    do{
        system ("cls");
        system ("title Subnet Calculator");
        system ("mode con cols=65 lines=40");
        SetConsoleTextAttribute(hConsole, 11);
        printf ("Enter your IP address and subnet mask using CIDR notation:\n\n");
        SetConsoleTextAttribute(hConsole, 10);
        printf (">>> ");
        SetConsoleTextAttribute(hConsole, 14);
        printf (" ");
        scanf ("%d %*c %d %*c %d %*c %d %*c %d", &oct1, &oct2, &oct3, &oct4, &cidr);

        if (oct1>223 || oct2>255 || oct3>255 || oct4>255 || cidr<8 || cidr>30){
            system ("cls");
            SetConsoleTextAttribute(hConsole, 12);
            printf ("\a\a\a\a\a\a\a\a\a\a\a\a\a\a\a\a\a\a\n\n\n            You have entered an invalid IP address or CIDR.\n\n\n                   ***PROGRAM WILL SELF DESTRUCT***\n\n\n");
            system ("pause");
            exit (0);
        }

/******************************************************
DETERMINE CLASS TYPE
*******************************************************/
        if (oct1>=1 && oct1<=127){
            classtype = 'A';
            netbits = 8;
        }
        else if (oct1>=128 && oct1<=191){
            classtype = 'B';
            netbits - 16;
        }
        else if (oct1>=192 && oct1<=223){
            classtype = 'C';
            netbits = 24;
        }

/******************************************************
DETERMINE BIT VALUE
*******************************************************/
        bitsbor = cidr-netbits;
        if (bitsbor>16 && bitsbor<24){
            cond=bitsbor-16;
        }
        else if (bitsbor>8 && bitsbor<16){
            cond=bitsbor-8;
        }
        else {
            cond=bitsbor;
        }
        switch (cond) {
            case 1:
                netinc = 128;
                maskSum = 128;
                break;
            case 2:
                netinc = 64;
                maskSum = 192;
                break;
            case 3:
                netinc = 32;
                maskSum = 224;
                break;
            case 4:
                netinc = 16;
                maskSum = 240;
                break;
            case 5:
                netinc = 8;
                maskSum = 248;
                break;
            case 6:
                netinc = 4;
                maskSum = 252;
                break;
            case 7:
                netinc = 2;
                maskSum = 254;
                break;
            case 8:
                netinc = 1;
                maskSum = 255;
                break;
        }

/******************************************************
DETERMINE SUBNET MASK, NETWORK ID, AND BROADCAST ID
*******************************************************/
        if (cidr>=24 && cidr<=30){
            mask1=255;
            mask2=255;
            mask3=255;
            mask4=maskSum;
            boct1=oct1;
            boct2=oct2;
            boct3=oct3;
            noct1=oct1;
            noct2=oct2;
            noct3=oct3;
            for (i=256; i>=oct4; i-=netinc){
            }
            noct4=i;
            boct4=noct4+netinc-1;
        }

        if (cidr>=16 && cidr <=23){
            mask1=255;
            mask2=255;
            mask3=maskSum;
            boct1=oct1;
            boct2=oct2;
            noct1=oct1;
            noct2=oct2;
            for (i=256; i>=oct3; i-=netinc){
            }
            noct3=i;
            boct3=noct3+netinc-1;
        }

        if (cidr>=8 && cidr<=15){
            mask1=255;
            mask2=maskSum;
            boct1=oct1;
            noct1=oct1;
            for (i=256; i>=oct2; i-=netinc){
            }
            noct2=i;
            boct2=noct2+netinc-1;
        }

/******************************************************
DETERMINE NUMBER OF AVAILABLE HOSTS & NETWORKS
*******************************************************/
        hostbits=32-cidr;
        hosts=pow (2, hostbits)-2;
        nets=pow(2, bitsbor);

/******************************************************
DISPLAY RESULTS
*******************************************************/
        printf ("\n\n\n");

        SetConsoleTextAttribute(hConsole, 10);
        printf ("You entered ............................... ");
        SetConsoleTextAttribute(hConsole, 13);
        printf ("%d.%d.%d.%d /%d\n", oct1, oct2, oct3, oct4, cidr);

        SetConsoleTextAttribute(hConsole, 10);
        printf ("Subnet Mask ............................... ");
        SetConsoleTextAttribute(hConsole, 13);
        printf ("%d.%d.%d.%d\n\n\n", mask1, mask2, mask3, mask4);

        SetConsoleTextAttribute(hConsole, 10);
        printf ("Class ..................................... ");
        SetConsoleTextAttribute(hConsole, 13);
        printf ("%c\n\n", classtype);

        SetConsoleTextAttribute(hConsole, 10);
        printf ("Network ID ................................ ");
        SetConsoleTextAttribute(hConsole, 13);
        printf ("%d.%d.%d.%d\n", noct1, noct2, noct3, noct4);

        SetConsoleTextAttribute(hConsole, 10);
        printf ("First assignable Address .................. ");
        SetConsoleTextAttribute(hConsole, 13);
        printf ("%d.%d.%d.%d\n", noct1, noct2, noct3, noct4+1);

        SetConsoleTextAttribute(hConsole, 10);
        printf ("Last assignable Address ................... ");
        SetConsoleTextAttribute(hConsole, 13);
        printf ("%d.%d.%d.%d\n", boct1, boct2, boct3, boct4-1);

        SetConsoleTextAttribute(hConsole, 10);
        printf ("Broadcast ID .............................. ");
        SetConsoleTextAttribute(hConsole, 13);
        printf ("%d.%d.%d.%d\n\n", boct1, boct2, boct3, boct4);

        SetConsoleTextAttribute(hConsole, 10);
        printf ("Borrowed bits ............................. ");
        SetConsoleTextAttribute(hConsole, 13);
        printf ("%d\n", bitsbor);

        SetConsoleTextAttribute(hConsole, 10);
        printf ("Subnet increments ......................... ");
        SetConsoleTextAttribute(hConsole, 13);
        printf ("%d\n", netinc);

        SetConsoleTextAttribute(hConsole, 10);
        printf ("Available subnets ......................... ");
        SetConsoleTextAttribute(hConsole, 13);
        printf ("%d\n", nets);

        SetConsoleTextAttribute(hConsole, 10);
        printf ("Available hosts per subnet ................ ");
        SetConsoleTextAttribute(hConsole, 13);
        printf ("%d\n\n\n", hosts);

        SetConsoleTextAttribute(hConsole, 11);
        printf ("Would you like to enter another IP address?\n\nEnter 1 to continue\nEnter 0 to exit\n\n");
        SetConsoleTextAttribute(hConsole, 10);
        printf (">>> ");
        SetConsoleTextAttribute(hConsole, 14);
        scanf ("%d", &ans);

    } while (ans==1);

    SetConsoleTextAttribute(hConsole, 10);
    printf ("\n\n\n\n");

    return 0;
}  //END MAIN PROGRAM

**Elysia** · 07-20-2010

Well, if you want basic feedback: your indentation is broken.
Code in main is not indented. Code inside loop is not indented.

**thefeedinghand** · 07-20-2010

Some comments would help other people understand your code more easily...

**digital_alchemy** · 07-21-2010

Originally Posted by Elysia

Well, if you want basic feedback: your indentation is broken.
Code in main is not indented. Code inside loop is not indented.

Well that's fine, but I mentioned a specific area that i'm looking for advice on as well.

**claudiu** · 07-21-2010

You can't force the user to do anything. The right approach is to decide what action you want to take on bogus input (ask him to reenter the input, etc.). The user can be a monkey hitting random keys on the keyboard, and usually it is (figuratively speaking).

**Elysia** · 07-21-2010

I'm sure people with experience with subnets will offer advice, as well, in due time.

**jimblumberg** · 07-22-2010

In your error checking routine after the

Code:

system("pause");

replace the

Code:

exit(0);

with

Code:

continue;

Also why are all of your variables global?

**digital_alchemy** · 07-22-2010

Originally Posted by jimblumberg

In your error checking routine after the

Code:

system("pause");

replace the

Code:

exit(0);

with

Code:

continue;

Also why are all of your variables global?

I tried replacing the code you suggested, but the only real difference is that it attempts to execute the rest of the program and exits anyway. I'm going to have to rewrite that section anyway.... I need to prompt the user to correct their input if they enter an invalid IP address.

as far as the global variables go... That's just the way I originally wrote it, and I didn't figure it would present a problem. (actually as I just tyed that I think I may have thought of an instance where that would present a problem... but I gotta run right now.. gotta get back to class).

Thanks

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