Minetrack/lib/ping.js

const minecraftJavaPing = require("mcping-js");
const minecraftBedrockPing = require("mcpe-ping-fixed");

const logger = require("./logger");
const MessageOf = require("./message");
const { TimeTracker } = require("./time");

const { getPlayerCountOrNull } = require("./util");

const config = require("../config");

function ping(serverRegistration, timeout, callback, version) {
  switch (serverRegistration.data.type) {
    case "PC":
      serverRegistration.dnsResolver.resolve((host, port, remainingTimeout) => {
        const server = new minecraftJavaPing.MinecraftServer(
          host,
          port || 25565
        );

        server.ping(remainingTimeout, version, (err, res) => {
          if (err) {
            callback(err);
          } else {
            const payload = {
              players: {
                online: capPlayerCount(
                  serverRegistration.data.ip,
                  parseInt(res.players.online)
                ),
              },
              version: parseInt(res.version.protocol),
            };

            // Ensure the returned favicon is a data URI
            if (res.favicon && res.favicon.startsWith("data:image/")) {
              payload.favicon = res.favicon;
            }

            callback(null, payload);
          }
        });
      });
      break;

    case "PE":
      minecraftBedrockPing(
        serverRegistration.data.ip,
        serverRegistration.data.port || 19132,
        (err, res) => {
          if (err) {
            callback(err);
          } else {
            callback(null, {
              players: {
                online: capPlayerCount(
                  serverRegistration.data.ip,
                  parseInt(res.currentPlayers)
                ),
              },
            });
          }
        },
        timeout
      );
      break;

    default:
      throw new Error("Unsupported type: " + serverRegistration.data.type);
  }
}

// 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;
}

class PingController {
  constructor(app) {
    this._app = app;
    this._isRunningTasks = false;
  }

  schedule() {
    setInterval(this.pingAll, config.rates.pingAll);
    // todo: make this a cron job?

    this.pingAll();
  }

  pingAll = () => {
    const { timestamp, updateHistoryGraph } =
      this._app.timeTracker.newPointTimestamp();

    this.startPingTasks((results) => {
      const updates = [];

      for (const serverRegistration of this._app.serverRegistrations) {
        const result = results[serverRegistration.serverId];

        // Log to database if enabled
        // Use null to represent a failed ping
        if (config.logToDatabase) {
          const unsafePlayerCount = getPlayerCountOrNull(result.resp);

          this._app.database.insertPing(
            serverRegistration.data.ip,
            timestamp,
            unsafePlayerCount
          );
        }

        // Generate a combined update payload
        // This includes any modified fields and flags used by the frontend
        // This will not be cached and can contain live metadata
        const update = serverRegistration.handlePing(
          timestamp,
          result.resp,
          result.err,
          result.version,
          updateHistoryGraph
        );

        updates[serverRegistration.serverId] = update;
      }

      // Send object since updates uses serverIds as keys
      // Send a single timestamp entry since it is shared
      this._app.server.broadcast(
        MessageOf("updateServers", {
          timestamp: TimeTracker.toSeconds(timestamp),
          updateHistoryGraph,
          updates,
        })
      );
    });
  };

  startPingTasks = (callback) => {
    if (this._isRunningTasks) {
      logger.log(
        "warn",
        'Started re-pinging servers before the last loop has finished! You may need to increase "rates.pingAll" in config.json'
      );

      return;
    }

    this._isRunningTasks = true;

    const results = [];

    for (const serverRegistration of this._app.serverRegistrations) {
      const version = serverRegistration.getNextProtocolVersion();

      ping(
        serverRegistration,
        config.rates.connectTimeout,
        (err, resp) => {
          if (err && config.logFailedPings !== false) {
            logger.log(
              "error",
              "Failed to ping %s: %s",
              serverRegistration.data.ip,
              err.message
            );
          }

          results[serverRegistration.serverId] = {
            resp,
            err,
            version,
          };

          if (
            Object.keys(results).length === this._app.serverRegistrations.length
          ) {
            // Loop has completed, release the locking flag
            this._isRunningTasks = false;

            callback(results);
          }
        },
        version.protocolId
      );
    }
  };
}

module.exports = PingController;