Capturing Webpages of with a Rust-based Web Crawler: A Step-by-Step Guide

Here is a sample implementation of a Rust web crawler that captures all the webpages of and finds all its subdomains using or other certificate transparency registries:

use std::collections::HashSet;
use reqwest::Client;
use select::document::Document;
use select::predicate::Name;

fn main() {
    let base_url = "";
    let mut visited_pages = HashSet::new();
    let mut queue = Vec::new();
    let client = Client::new();

    while let Some(url) = queue.pop() {
        if visited_pages.contains(&url) {

        let res = match client.get(url).send() {
            Ok(res) => res,
            Err(e) => {
                println!("Error getting page: {}", e);

        if !res.status().is_success() {

        let document = Document::from_read(res).unwrap();
        for node in document.find(Name("a")) {
            let link = node.attr("href").unwrap_or("");
            if link.starts_with("/") {
                queue.push(base_url.to_owned() + link);
            } else if link.starts_with(base_url) {

    // Use certificate transparency registries such as to find all subdomains of
    let crt_sh_search_url = format!("{}&output=json", "");
    let subdomains_json = reqwest::get(&crt_sh_search_url).unwrap().text().unwrap();
    let subdomains: Vec<&str> = serde_json::from_str(&subdomains_json).unwrap();
    println!("Subdomains of {:?}", subdomains);

In this code, we first create a Client object from the reqwest library to make HTTP requests. Then, we use a breadth-first search algorithm to traverse all the pages on the website, and we store the visited pages in a HashSet to avoid visiting the same page multiple times.

To find all the subdomains of, we use the certificate transparency registry We construct a URL with a search query that returns all the subdomains of in JSON format, and we make a GET request to this URL using the reqwest library. We then parse the JSON response into a Vec of subdomains.

This is a basic implementation of a web crawler for the website, and it can be further extended or optimized as needed.