114 lines
2.5 KiB
C
114 lines
2.5 KiB
C
/* A very simple subnet calculator in C, written by
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* Jack-Benny Persson (jack-benny@cyberinfo.se).
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* Released under GNU GPLv2.
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*/
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#include <stdio.h>
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#include <math.h>
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#include <stdlib.h>
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#include <string.h>
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int checkInput(char input[]);
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long int calcAddr(int netmask);
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long int calcHosts(int netmask);
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void printAddr(int netmask);
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void printHelp(char progname[]);
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int main(int argc, char *argv[])
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{
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char input[3] = { 0 };
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int net;
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if (argc == 1) /* User didn't supply an argument, go interactive */
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{
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printf("Enter netmask in slash-notation without the slash: ");
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scanf("%2c", input);
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if (checkInput(input))
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{
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net = atoi(input);
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printAddr(net);
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return 0;
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}
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else /* If the user entered anything else than 0-32 */
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{
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printHelp(argv[0]);
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return 1;
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}
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}
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else if (argc == 2) /* User supplied exactly one argument */
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{
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if (checkInput(argv[1]))
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{
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net = atoi(argv[1]);
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printAddr(net);
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}
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else
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{
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printHelp(argv[0]);
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return 1;
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}
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}
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else /* User supplied to many arguments */
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{
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printHelp(argv[0]);
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return 1;
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}
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return 0;
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}
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int checkInput(char input[])
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{
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int netmask;
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/* Sanity check the user input */
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if( strspn(input, "0123456789.-\n") == strlen(input) )
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{
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netmask = atoi(input);
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if (netmask >= 0 && netmask <= 32)
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{
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return 1;
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}
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else
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{
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printf("Only values between 0 and 32 are accepted\n\n");
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return 0;
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}
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}
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else
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{
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printf("Only values between 0 and 32 are accepted\n\n");
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return 0;
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}
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}
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long int calcAddr(int netmask)
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{
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return pow(2, 32-netmask);
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}
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long int calcHosts(int netmask)
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{
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long int hosts;
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hosts = (pow(2, 32-netmask))-2;
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if (hosts < 0) /* If usables hosts < 0, set to 0 */
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{
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hosts = 0;
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}
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return hosts;
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}
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void printAddr(int netmask)
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{
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printf("Netmask bit: %d\n\n", netmask);
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printf("%ld total addresses\n", calcAddr(netmask));
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printf("%ld usable addresses for hosts\n", calcHosts(netmask));
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}
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void printHelp(char progname[])
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{
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printf("Usage: %s [netmask]\n", progname);
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printf("If the program is started without any arguments, "
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"it's started in interactive mode.\n");
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printf("Optionally, a netmask can be supplied as a "
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"argument.\n");
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printf("Examle: %s 24\n", progname);
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} |