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