Minetrack/lib/dns.js

79 lines
2.4 KiB
JavaScript
Raw Normal View History

const dns = require('dns')
const logger = require('./logger')
const { TimeTracker } = require('./time')
const config = require('../config')
const SKIP_SRV_TIMEOUT = config.skipSrvTimeout || 60 * 60 * 1000
class DNSResolver {
constructor (ip, port) {
this._ip = ip
this._port = port
}
_skipSrv () {
this._skipSrvUntil = TimeTracker.getEpochMillis() + SKIP_SRV_TIMEOUT
}
_isSkipSrv () {
2020-05-15 01:43:55 +00:00
return this._skipSrvUntil && TimeTracker.getEpochMillis() <= this._skipSrvUntil
}
resolve (callback) {
if (this._isSkipSrv()) {
callback(this._ip, this._port, config.rates.connectTimeout)
return
}
const startTime = TimeTracker.getEpochMillis()
let callbackFired = false
const fireCallback = (ip, port) => {
if (!callbackFired) {
callbackFired = true
// Send currentTime - startTime to provide remaining connectionTime allowance
const remainingTime = config.rates.connectTimeout - (TimeTracker.getEpochMillis() - startTime)
callback(ip || this._ip, port || this._port, remainingTime)
}
}
const timeoutCallback = setTimeout(fireCallback, config.rates.connectTimeout)
dns.resolveSrv('_minecraft._tcp.' + this._ip, (err, records) => {
// Cancel the timeout handler if not already fired
if (!callbackFired) {
clearTimeout(timeoutCallback)
}
// Test if the error indicates a miss, or if the records returned are empty
if ((err && (err.code === 'ENOTFOUND' || err.code === 'ENODATA')) || !records || records.length === 0) {
2020-05-15 01:43:14 +00:00
// Compare config.skipSrvTimeout directly since SKIP_SRV_TIMEOUT has an or'd value
// isSkipSrvTimeoutDisabled == whether the config has a valid skipSrvTimeout value set
const isSkipSrvTimeoutDisabled = typeof config.skipSrvTimeout === 'number' && config.skipSrvTimeout === 0
2020-05-15 01:43:14 +00:00
// Only activate _skipSrv if the skipSrvTimeout value is either NaN or > 0
// 0 represents a disabled flag
if (!this._isSkipSrv() && !isSkipSrvTimeoutDisabled) {
this._skipSrv()
logger.log('warn', 'No SRV records were resolved for %s. Minetrack will skip attempting to resolve %s SRV records for %d minutes.', this._ip, this._ip, SKIP_SRV_TIMEOUT / (60 * 1000))
}
fireCallback()
} else {
// Only fires if !err && records.length > 0
fireCallback(records[0].name, records[0].port)
}
})
}
}
module.exports = DNSResolver