Added a docker container IP warning (#584)

* Added a docker container IP warning

* Corrected messages

* Moved to normal java file read instead of starting cat

* Fixed capitalisation on method name

connector/src/main/java/org/geysermc/connector/GeyserConnector.java

@@ -40,6 +40,7 @@ import org.geysermc.connector.network.session.GeyserSession;
 import org.geysermc.connector.network.translators.Translators;
 import org.geysermc.connector.network.translators.world.WorldManager;
 import org.geysermc.connector.thread.PingPassthroughThread;
+import org.geysermc.connector.utils.DockerCheck;
 import org.geysermc.connector.utils.Toolbox;
 
 import java.net.InetSocketAddress;
@@ -102,6 +103,10 @@ public class GeyserConnector {
         Toolbox.init();
         Translators.start();
 
+        if (platformType != PlatformType.STANDALONE) {
+            DockerCheck.check(bootstrap);
+        }
+
         remoteServer = new RemoteServer(config.getRemote().getAddress(), config.getRemote().getPort());
         authType = AuthType.getByName(config.getRemote().getAuthType());
 

connector/src/main/java/org/geysermc/connector/utils/DockerCheck.java

@@ -0,0 +1,58 @@
+/*
+ * Copyright (c) 2019-2020 GeyserMC. http://geysermc.org
+ *
+ *  Permission is hereby granted, free of charge, to any person obtaining a copy
+ *  of this software and associated documentation files (the "Software"), to deal
+ *  in the Software without restriction, including without limitation the rights
+ *  to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+ *  copies of the Software, and to permit persons to whom the Software is
+ *  furnished to do so, subject to the following conditions:
+ *
+ *  The above copyright notice and this permission notice shall be included in
+ *  all copies or substantial portions of the Software.
+ *
+ *  THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ *  IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+ *  FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+ *  AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+ *  LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+ *  OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
+ *  THE SOFTWARE.
+ *
+ *  @author GeyserMC
+ *  @link https://github.com/GeyserMC/Geyser
+ *
+ */
+
+package org.geysermc.connector.utils;
+
+import org.geysermc.connector.bootstrap.GeyserBootstrap;
+
+import java.net.InetAddress;
+import java.nio.file.Files;
+import java.nio.file.Paths;
+
+public class DockerCheck {
+    public static void check(GeyserBootstrap bootstrap) {
+        try {
+            String OS = System.getProperty("os.name").toLowerCase();
+            String ipAddress = InetAddress.getLocalHost().getHostAddress();
+
+            // Check if the user is already using the recommended IP
+            if (ipAddress.equals(bootstrap.getGeyserConfig().getRemote().getAddress())) {
+                return;
+            }
+
+            if (OS.indexOf("nix") >= 0 || OS.indexOf("nux") >= 0 || OS.indexOf("aix") > 0) {
+                bootstrap.getGeyserLogger().debug("We are on a Unix system, checking for Docker...");
+
+                String output = new String(Files.readAllBytes(Paths.get("/proc/1/cgroup")));
+
+                if (output.contains("docker")) {
+                    bootstrap.getGeyserLogger().warning("You are most likely in a Docker container, this may cause connection issues from Geyser to the Java server");
+                    bootstrap.getGeyserLogger().warning("We recommended using the following IP as the remote address: " + ipAddress);
+                }
+            }
+        } catch (Exception e) { } // Ignore any errors, inc ip failed to fetch, process could not run or access denied
+    }
+}