Subdomain Finder In C Programming

subdomain-finder.c

#include <stdio.h>
#include <netdb.h>
#include <arpa/inet.h>
#include <string.h>

#define MAX_SUBDOMAINS 1000
#define MAX_HOSTNAME_LEN 100

int main(int argc, char *argv[])
{
    int i;
    char hostname[MAX_HOSTNAME_LEN];
    struct addrinfo hints, *res, *p;

    if (argc != 2) {
        fprintf(stderr, "Usage: %s <domain>\n", argv[0]);
        return 1;
    }

    memset(&hints, 0, sizeof hints);
    hints.ai_family = AF_UNSPEC; // allow IPv4 or IPv6
    hints.ai_socktype = SOCK_STREAM;

    for (i = 0; i < MAX_SUBDOMAINS; i++) {
        snprintf(hostname, MAX_HOSTNAME_LEN, "%d.%s", i, argv[1]);

        if (getaddrinfo(hostname, "http", &hints, &res) == 0) {
            printf("%s\n", hostname);
            freeaddrinfo(res);
        }
    }

    return 0;
}