dns_lookups.js

const axios = require("axios").create({ proxy: false });
const dns = require("dns");
const privateIp = require("private-ip");

const { headers } = require("./get");
const logger = require("./logger");

// do not pass user input unsanitized! this is only for demo purposes.
const getNext = (nextLocation) => {
  dns.lookup(nextLocation, {}, (err, address, family) => {
    if (err || address === null || family === null) {
      logger.error(err);
    } else {
      // don't do this
      const loc = !address.startsWith("http") ? "http://" + address : address;
      axios
        .get(loc)
        .then((response) => {
          logger.info("Requested " + loc);
          logger.debug(response);
        })
        .catch((err) => {
          logger.error("UH OH: request (to " + loc + ") failed: ");
          logger.error(err.errno);
          logger.error(err.config);
        });
    }
  });
};

const requestHost = (hostHeader, response) => {
  dns.lookup(hostHeader, {}, (err, address) => {
    if (err || address === null) {
      logger.error(err);
    } else if (privateIp(address)) {
      const loc = !address.startsWith("http") ? "http://" + address : address;
      axios
        .get(loc)
        .then((response) => {
          logger.info("Requested " + loc);
          logger.debug(response);
        })
        .catch((err) => {
          logger.error("UH OH: request (to " + loc + ") failed");
          logger.error(err.errno);
          logger.error(err.config);
        });
    } else {
      let msg = "requested host did not resolve to private ip";
      response.writeHead(400, headers);
      response.end(msg);
    }
  });
};

const patch = (request, response) => {
  requestHost(request.headers.host, response);
};

module.exports.getNext = getNext;
module.exports.patch = patch;