node-gamedig/lib/DnsResolver.js

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const dns = require('dns'),
Logger = require('./Logger'),
util = require('util'),
dnsLookupAsync = util.promisify(dns.lookup),
dnsResolveAsync = util.promisify(dns.resolve),
punycode = require('punycode');
class DnsResolver {
/**
* @param {Logger} logger
*/
constructor(logger) {
this.logger = logger;
}
isIp(host) {
return !!host.match(/\d+\.\d+\.\d+\.\d+/);
}
/**
* Response port will only be present if srv record was involved.
* @param {string} host
* @param {number} ipFamily
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* @param {string=} srvRecordPrefix
* @returns {Promise<{address:string, port:number=}>}
*/
async resolve(host, ipFamily, srvRecordPrefix) {
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this.logger.debug("DNS Lookup: " + host);
if(this.isIp(host)) {
this.logger.debug("Raw IP Address: " + host);
return {address: host};
}
const asciiForm = punycode.toASCII(host);
if (asciiForm !== host) {
this.logger.debug("Encoded punycode: " + host + " -> " + asciiForm);
host = asciiForm;
}
if (srvRecordPrefix) {
this.logger.debug("SRV Resolve: " + srvRecordPrefix + '.' + host);
let records;
try {
records = await dnsResolveAsync(srvRecordPrefix + '.' + host, 'SRV');
if (records.length >= 1) {
this.logger.debug("Found SRV Records: ", records);
const record = records[0];
const srvPort = record.port;
const srvHost = record.name;
if (srvHost === host) {
throw new Error('Loop in DNS SRV records');
}
return {
port: srvPort,
...await this.resolve(srvHost, ipFamily, srvRecordPrefix)
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};
}
this.logger.debug("No SRV Record");
} catch (e) {
this.logger.debug(e);
}
}
this.logger.debug("Standard Resolve: " + host);
const dnsResult = await dnsLookupAsync(host, ipFamily);
// For some reason, this sometimes returns a string address rather than an object.
// I haven't been able to reproduce, but it's been reported on the issue tracker.
let address;
if (typeof dnsResult === 'string') {
address = dnsResult;
} else {
address = dnsResult.address;
}
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this.logger.debug("Found address: " + address);
return {address: address};
}
}
module.exports = DnsResolver;