get-dns.js

#!/usr/bin/env node

/**
 * Usage: node get-dns.js <domain>
 * Example: node get-dns.js crittercontrol.com
 *
 * This script:
 *  1. Queries DNS records for the apex domain and a list of possible subdomains.
 *  2. Ensures the apex domain (@) always has an SOA record, creating a default if none is found.
 *  3. Filters out invalid record conflicts (CNAME vs. A/AAAA/MX/etc. on the same label).
 *  4. Generates a zone file with $TTL and $ORIGIN at the top, referencing subdomains as relative labels.
 *  5. Outputs a summary of how many DNS records and how many domain labels were discovered.
 */

const dns = require("dns").promises;
const fs = require("fs");
const path = require("path");

// Default TTL (in seconds)
const DEFAULT_TTL = 3600;

// List of record types to query
const RECORD_TYPES = ["A", "AAAA", "CNAME", "MX", "NS", "TXT", "SOA", "SRV"];

// Expand our subdomain dictionary:
const SUBDOMAINS = [
  "_domainconnect",
  "about",
  "account",
  "accounts",
  "admin",
  "ads",
  "advertising",
  "alpha",
  "analysis",
  "analytics",
  "api",
  "app",
  "apps",
  "assets",
  "au",
  "auth",
  "autoconfig",
  "autodiscover",
  "backend",
  "beta",
  "billing",
  "blog",
  "board",
  "ca",
  "careers",
  "cart",
  "cdn",
  "chat",
  "checkout",
  "ci",
  "cicd",
  "cloud",
  "community",
  "console",
  "cpanel",
  "dashboard",
  "de",
  "demo",
  "dev",
  "developer",
  "developers",
  "development",
  "devops",
  "discussion",
  "docs",
  "download",
  "downloads",
  "en",
  "es",
  "events",
  "extranet",
  "faq",
  "feedback",
  "file",
  "files",
  "forum",
  "forums",
  "fr",
  "frontend",
  "ftp",
  "get",
  "git",
  "github",
  "gitlab",
  "go",
  "gql",
  "graphql",
  "help",
  "helpdesk",
  "hr",
  "images",
  "imap",
  "img",
  "internal",
  "intranet",
  "investor",
  "investors",
  "invoice",
  "invoices",
  "jobs",
  "join",
  "kb",
  "labs",
  "landing",
  "lists",
  "live",
  "login",
  "m",
  "mail",
  "market",
  "media",
  "metrics",
  "mobile",
  "monitor",
  "my",
  "news",
  "oauth",
  "opportunities",
  "panel",
  "partners",
  "payment",
  "payments",
  "pop",
  "portal",
  "pre-production",
  "preprod",
  "preprod-env",
  "press",
  "private",
  "promo",
  "qa",
  "register",
  "rss",
  "sandbox",
  "secure",
  "security",
  "server",
  "sftp",
  "shop",
  "signin",
  "signup",
  "slack",
  "smtp",
  "sso",
  "stage",
  "staging",
  "static",
  "statistics",
  "stats",
  "status",
  "store",
  "supplier",
  "support",
  "test",
  "testing",
  "tickets",
  "track",
  "tracking",
  "try",
  "uk",
  "upload",
  "uploads",
  "us",
  "vendors",
  "vpn",
  "webdisk",
  "webmail",
  "what",
  "whm",
  "who",
  "why",
  "www",
];

// Retrieve DNS records for a single domain across multiple record types
async function getAllRecordsForDomain(domain) {
  const results = {};

  for (const type of RECORD_TYPES) {
    try {
      const records = await dns.resolve(domain, type);
      if (records && records.length > 0) {
        results[type] = records;
      }
    } catch (err) {
      // Domain doesn't have that record type or there's an error. Ignore.
    }
  }

  return results;
}

/**
 * Convert a fully qualified hostname into a "relative" label for the apex domain.
 * E.g.:
 *   domain = "example.com"
 *   getRelativeName("example.com", "example.com") -> "@"
 *   getRelativeName("mail.example.com", "example.com") -> "mail"
 */
function getRelativeName(hostname, apexDomain) {
  if (hostname === apexDomain) return "@";
  const suffix = "." + apexDomain;
  if (hostname.endsWith(suffix)) {
    return hostname.slice(0, -suffix.length);
  }
  // Fallback: return the entire hostname if it doesn't match exactly
  return hostname;
}

/**
 * Generate a default SOA record object if none is found.
 * Adjust values (nsname, hostmaster, etc.) as desired.
 */
function generateDefaultSoa(domain) {
  const now = new Date();
  // Format an ISO-like date string: YYYYMMDDnn (nn = 2-digit counter)
  const datePart = now.toISOString().slice(0, 10).replace(/-/g, "");
  // Minimal approach: take today's date and add 01
  const serial = parseInt(`${datePart}01`, 10);

  return {
    nsname: `ns1.${domain}`, // Primary nameserver
    hostmaster: `hostmaster.${domain}`, // Hostmaster email -> hostmaster@domain
    serial,
    refresh: 7200, // 2 hours
    retry: 3600, // 1 hour
    expire: 1209600, // 14 days
    minttl: 3600, // 1 hour
  };
}

(async function main() {
  if (process.argv.length < 3) {
    console.error("Usage: node get-dns.js <domain>");
    process.exit(1);
  }

  const domain = process.argv[2].toLowerCase().trim();

  // 1. Gather DNS records for the apex domain
  const recordsMap = {};
  recordsMap[domain] = await getAllRecordsForDomain(domain);

  // 2. Gather DNS records for subdomains
  const subdomainList = SUBDOMAINS.map((sub) => `${sub}.${domain}`);
  for (const sub of subdomainList) {
    const subRecords = await getAllRecordsForDomain(sub);
    if (Object.keys(subRecords).length > 0) {
      recordsMap[sub] = subRecords;
    }
  }

  // 3. If apex domain does not have an SOA record, add a default
  if (!recordsMap[domain].SOA) {
    recordsMap[domain].SOA = [generateDefaultSoa(domain)];
  }

  // 4. Remove invalid record conflicts
  //    If a label has a CNAME, we discard other record types for that label
  for (const [hostname, recordTypes] of Object.entries(recordsMap)) {
    if (recordTypes.CNAME && recordTypes.CNAME.length > 0) {
      // Keep the CNAME; discard the rest
      const cnameRecords = recordTypes.CNAME;
      Object.keys(recordTypes).forEach((type) => delete recordTypes[type]);
      recordTypes.CNAME = cnameRecords;
    }
  }

  // 5. Build a single zone file with a single $ORIGIN and $TTL
  const zoneLines = [];
  zoneLines.push(`$TTL ${DEFAULT_TTL}`);
  zoneLines.push(`$ORIGIN ${domain}.`);

  // We'll collect lines for each label
  const recordLines = [];
  for (const [hostname, recordSet] of Object.entries(recordsMap)) {
    const relativeName = getRelativeName(hostname, domain);

    for (const [type, values] of Object.entries(recordSet)) {
      for (const val of values) {
        switch (type) {
          case "A":
          case "AAAA":
            recordLines.push(`${relativeName} IN ${type} ${val}`);
            break;

          case "CNAME":
            // Must ensure it ends with a dot if referencing a FQDN
            recordLines.push(
              `${relativeName} IN CNAME ${val.endsWith(".") ? val : val + "."}`
            );
            break;

          case "MX":
            // E.g. "mail  IN MX priority mailhost."
            if (typeof val === "object" && val.exchange) {
              recordLines.push(
                `${relativeName} IN MX ${val.priority} ${
                  val.exchange.endsWith(".") ? val.exchange : val.exchange + "."
                }`
              );
            } else {
              recordLines.push(`${relativeName} IN MX ${val}`);
            }
            break;

          case "NS":
            recordLines.push(
              `${relativeName} IN NS ${val.endsWith(".") ? val : val + "."}`
            );
            break;

          case "SOA":
            // Node returns an object: { nsname, hostmaster, serial, refresh, retry, expire, minttl }
            if (typeof val === "object") {
              const {
                nsname,
                hostmaster,
                serial,
                refresh,
                retry,
                expire,
                minttl,
              } = val;
              recordLines.push(
                `${relativeName} IN SOA ${nsname}. ${hostmaster}. (` +
                  `${serial} ${refresh} ${retry} ${expire} ${minttl})`
              );
            } else {
              recordLines.push(`${relativeName} IN SOA ${val}`);
            }
            break;

          case "SRV":
            // E.g. "service IN SRV priority weight port target."
            if (typeof val === "object") {
              const { priority, weight, port, name } = val;
              recordLines.push(
                `${relativeName} IN SRV ${priority} ${weight} ${port} ${
                  name.endsWith(".") ? name : name + "."
                }`
              );
            } else {
              recordLines.push(`${relativeName} IN SRV ${val}`);
            }
            break;

          case "TXT":
            // Node returns arrays of arrays for TXT
            if (Array.isArray(val)) {
              const textValue = val.join("");
              recordLines.push(`${relativeName} IN TXT "${textValue}"`);
            } else {
              recordLines.push(`${relativeName} IN TXT "${val}"`);
            }
            break;

          default:
            recordLines.push(`${relativeName} IN ${type} ${val}`);
        }
      }
    }
  }

  // 6. Sort the records so that '@' is at the top, optionally
  recordLines.sort((a, b) => {
    // Put lines starting with '@' first
    if (a.startsWith("@") && !b.startsWith("@")) return -1;
    if (!a.startsWith("@") && b.startsWith("@")) return 1;
    return a.localeCompare(b);
  });

  zoneLines.push(...recordLines);

  // 7. Write the zone data to a file
  const zoneFileName = `${domain}.zone`;
  fs.writeFileSync(
    path.join(process.cwd(), zoneFileName),
    zoneLines.join("\n") + "\n"
  );

  // 8. Summarize
  let totalRecords = 0;
  for (const recordObj of Object.values(recordsMap)) {
    totalRecords += Object.values(recordObj).reduce(
      (sum, arr) => sum + arr.length,
      0
    );
  }
  const totalHostnames = Object.keys(recordsMap).length;

  console.log(
    `Found ${totalRecords} DNS entries across ${totalHostnames} domain(s) for ${domain} and generated ${zoneFileName}`
  );
})();