From 6d0a2f28e5145efe506ae7413477260d404bd3e7 Mon Sep 17 00:00:00 2001
From: Nick Krecklow <hello@github.nklow.com>
Date: Mon, 30 Mar 2020 01:31:35 -0500
Subject: [PATCH] prevent high player counts from crashing browsers

---
 lib/ping.js | 19 +++++++++++++++++--
 1 file changed, 17 insertions(+), 2 deletions(-)

diff --git a/lib/ping.js b/lib/ping.js
index 3d53087..8305c9e 100644
--- a/lib/ping.js
+++ b/lib/ping.js
@@ -1,6 +1,7 @@
 var mcpe_ping = require('mcpe-ping-fixed');
 var mcpc_ping = require('mc-ping-updated');
 
+var logger = require('./logger');
 var util = require('./util');
 
 // This is a wrapper function for mc-ping-updated, mainly used to convert the data structure of the result.
@@ -21,7 +22,7 @@ function pingMinecraftPC(host, port, timeout, callback, version) {
 
 	        callback(null, {
 				players: {
-					online: parseInt(res.players.online),
+					online: capPlayerCount(host, parseInt(res.players.online)),
 					max: parseInt(res.players.max)
 				},
 				version: parseInt(res.version.protocol),
@@ -43,7 +44,7 @@ function pingMinecraftPE(host, port, timeout, callback) {
 			// Remap our JSON into our custom structure.
 			callback(err, {
 				players: {
-					online: parseInt(res.currentPlayers),
+					online: capPlayerCount(host, parseInt(res.currentPlayers)),
 					max: parseInt(res.maxPlayers)
 				},
 				version: res.version,
@@ -53,6 +54,20 @@ function pingMinecraftPE(host, port, timeout, callback) {
 	}, timeout);
 }
 
+// player count can be up to 1^32-1, which is a massive scale and destroys browser performance when rendering graphs
+// Artificially cap and warn to prevent propogating garbage
+function capPlayerCount(host, playerCount) {
+	const maxPlayerCount = 250000;
+	if (playerCount !== Math.min(playerCount, maxPlayerCount)) {
+		logger.log('warn', '%s returned a player count of %d, Minetrack has capped it to %d to prevent browser performance issues with graph rendering. If this is in error, please edit maxPlayerCount in ping.js!', host, playerCount, maxPlayerCount);
+		return maxPlayerCount;
+	} else if (playerCount !== Math.max(playerCount, 0)) {
+		logger.log('warn', '%s returned an invalid player count of %d, setting to 0.', host, playerCount);
+		return 0;
+	}
+	return playerCount;
+}
+
 exports.ping = function(host, port, type, timeout, callback, version) {
 	if (type === 'PC') {
 		util.unfurlSRV(host, port, function(host, port){