Flesh out allowlist handling

Addresses comments from https://github.com/LOOHP/Limbo/pull/57#issuecomment-1304543589

In particular:

* Functionality now matches other server types

* only enforce the allowlist if a new "enforce-allowlist"
  boolean in server.properties is set to true

* Loads and process the allowlist only once when the server starts (or
  the reload command is executed), instead of every time a user connects.

* Add a new command & associated permissions "allowlist reload"
  to reload the allowlist

src/main/java/com/loohp/limbo/Limbo.java

@@ -432,6 +432,31 @@ public class Limbo {
 	public ServerProperties getServerProperties() {
 		return properties;
 	}
+
+	public void reloadAllowlist() {
+		properties.reloadAllowlist();
+	}
+
+	public boolean uuidIsAllowed(UUID requestedUuid) {
+		if (!properties.isEnforceAllowlist()) {
+			return true;
+		}
+
+		for (UUID allowedUuid : properties.getAllowlist()) {
+			if (requestedUuid.equals(allowedUuid)) {
+				if(!properties.isReducedDebugInfo()) {
+					Limbo.getInstance().getConsole().sendMessage(String.format("allowlist: %s allowed", requestedUuid.toString()));
+				}
+				return true;
+			}
+		}
+
+		if(!properties.isReducedDebugInfo()) {
+			Limbo.getInstance().getConsole().sendMessage(String.format("allowlist: %s not allowed", requestedUuid.toString()));
+		}
+
+		return false;
+	}
 	
 	public ServerConnection getServerConnection() {
 		return server;

src/main/java/com/loohp/limbo/commands/DefaultCommands.java

@@ -165,6 +165,20 @@ public class DefaultCommands implements CommandExecutor, TabCompletor {
 			}
 			return;
 		}
+		if (args[0].equalsIgnoreCase("allowlist")) {
+			if (sender.hasPermission("limboserver.allowlist")) {
+				if (args.length != 2) {
+					sender.sendMessage(ChatColor.RED + "Invalid usage!");
+				} else if (!args[1].equalsIgnoreCase("reload")) {
+					sender.sendMessage(ChatColor.RED + "Invalid usage!");
+				} else {
+					Limbo.getInstance().reloadAllowlist();
+				}
+			} else {
+				sender.sendMessage(ChatColor.RED + "You do not have permission to use that command!");
+			}
+			return;
+		}
 	}
 	
 	@Override

src/main/java/com/loohp/limbo/file/ServerProperties.java

@@ -22,20 +22,31 @@ package com.loohp.limbo.file;
 import java.awt.image.BufferedImage;
 import java.io.File;
 import java.io.FileInputStream;
+import java.io.FileNotFoundException;
 import java.io.FileOutputStream;
+import java.io.FileReader;
 import java.io.IOException;
 import java.io.InputStreamReader;
 import java.io.OutputStreamWriter;
 import java.io.PrintWriter;
 import java.nio.charset.StandardCharsets;
+import java.util.ArrayList;
+import java.util.Iterator;
 import java.util.List;
 import java.util.Map.Entry;
 import java.util.Optional;
 import java.util.Properties;
+import java.util.UUID;
 
 import javax.imageio.ImageIO;
 
+import org.json.simple.JSONArray;
+import org.json.simple.JSONObject;
+import org.json.simple.parser.JSONParser;
+import org.json.simple.parser.ParseException;
+
 import com.google.common.collect.Lists;
+import com.loohp.limbo.Console;
 import com.loohp.limbo.Limbo;
 import com.loohp.limbo.location.Location;
 import com.loohp.limbo.utils.GameMode;
@@ -72,6 +83,8 @@ public class ServerProperties {
 	private int viewDistance;
 	private double ticksPerSecond;
 	private boolean handshakeVerbose;
+	private boolean enforceAllowlist;
+	private ArrayList<UUID> allowlist;
 	
 	private String resourcePackSHA1;
 	private String resourcePackLink;
@@ -184,9 +197,65 @@ public class ServerProperties {
 			favicon = Optional.empty();
 		}
 
+		enforceAllowlist = Boolean.parseBoolean(prop.getProperty("enforce-allowlist"));
+		if (enforceAllowlist) {
+			reloadAllowlist();
+		}
+
 		Limbo.getInstance().getConsole().sendMessage("Loaded server.properties");
 	}
-	
+
+	public void reloadAllowlist() {
+        Console console = Limbo.getInstance().getConsole();
+
+		allowlist = new ArrayList<UUID>();
+        try {
+            JSONParser parser = new JSONParser();
+            Object obj = parser.parse(new FileReader("allowlist.json"));
+
+            if (!(obj instanceof JSONArray)) {
+                console.sendMessage("allowlist: expected [] got {}");
+                return;
+            }
+
+            JSONArray array = (JSONArray) obj;
+
+            Iterator<?> iter = array.iterator();
+            while (iter.hasNext()) {
+                Object o = iter.next();
+                if (!(o instanceof JSONObject)) {
+                    console.sendMessage("allowlist: array element is not an object");
+                    continue;
+                }
+
+                JSONObject element = (JSONObject) o;
+                o = element.get("uuid");
+                if (o == null) {
+                    console.sendMessage("allowlist: missing uuid attribute");
+                    continue;
+                }
+                if (!(o instanceof String)) {
+                    console.sendMessage("allowlist: uuid is not a string");
+                    continue;
+                }
+
+				String uuidStr = (String) o;
+                UUID allowedUuid = UUID.fromString(uuidStr);
+				allowlist.add(allowedUuid);
+            }
+        } catch (IllegalArgumentException e) {
+                console.sendMessage(e.toString());
+        } catch (FileNotFoundException e) {
+                console.sendMessage(String.format("allowlist: %s", e.toString()));
+        } catch (IOException e) {
+                console.sendMessage(String.format("allowlist: %s", e.toString()));
+        } catch (ParseException e) {
+                console.sendMessage(String.format(" allowlist: parse: %s", e.toString()));
+        }
+
+		console.sendMessage("allowlist: reloaded");
+	}
+
 	public String getServerImplementationVersion() {
 		return Limbo.getInstance().SERVER_IMPLEMENTATION_VERSION;
 	}
@@ -294,6 +363,14 @@ public class ServerProperties {
 	public boolean handshakeVerboseEnabled() {
 		return handshakeVerbose;
 	}
+
+	public boolean isEnforceAllowlist() {
+		return enforceAllowlist;
+	}
+
+	public ArrayList<UUID> getAllowlist() {
+		return allowlist;
+	}
 	
 	public String getResourcePackLink() {
 		return resourcePackLink;

src/main/java/com/loohp/limbo/network/ClientConnection.java

@@ -19,7 +19,6 @@
 
 package com.loohp.limbo.network;
 
-import com.loohp.limbo.Console;
 import com.loohp.limbo.Limbo;
 import com.loohp.limbo.events.player.PlayerJoinEvent;
 import com.loohp.limbo.events.player.PlayerSpawnEvent;
@@ -98,14 +97,11 @@ import net.md_5.bungee.api.chat.TranslatableComponent;
 import org.json.simple.JSONArray;
 import org.json.simple.JSONObject;
 import org.json.simple.parser.JSONParser;
-import org.json.simple.parser.ParseException;
 
 import java.io.ByteArrayOutputStream;
 import java.io.DataInput;
 import java.io.DataInputStream;
 import java.io.DataOutputStream;
-import java.io.FileNotFoundException;
-import java.io.FileReader;
 import java.io.IOException;
 import java.lang.reflect.Constructor;
 import java.net.InetAddress;
@@ -113,7 +109,6 @@ import java.net.Socket;
 import java.nio.charset.StandardCharsets;
 import java.util.ArrayList;
 import java.util.HashSet;
-import java.util.Iterator;
 import java.util.List;
 import java.util.Optional;
 import java.util.Random;
@@ -300,84 +295,6 @@ public class ClientConnection extends Thread {
         });
     }
 
-    public boolean uuidAllowed(UUID uuid, boolean verbose) {
-        Console console = Limbo.getInstance().getConsole();
-
-        try {
-            JSONParser parser = new JSONParser();
-            Object obj = parser.parse(new FileReader("allowlist.json"));
-
-            if (!(obj instanceof JSONArray)) {
-                if (verbose) {
-                    console.sendMessage("allowlist: expected [] got {}");
-                }
-                return false;
-            }
-
-            JSONArray array = (JSONArray) obj;
-
-            Iterator<?> iter = array.iterator();
-            while (iter.hasNext()) {
-                Object o = iter.next();
-                if (!(o instanceof JSONObject)) {
-                    if (verbose) {
-                        console.sendMessage("allowlist: array element is not an object");
-                    }
-                    continue;
-                }
-
-                JSONObject element = (JSONObject) o;
-                o = element.get("uuid");
-                if (o == null) {
-                    if (verbose) {
-                        console.sendMessage("allowlist: missing uuid attribute");
-                    }
-                    continue;
-                }
-                if (!(o instanceof String)) {
-                    if (verbose) {
-                        console.sendMessage("allowlist: uuid is not a string");
-                    }
-                    continue;
-                }
-                String uuidStr = (String) o;
-
-                UUID allowedUuid = UUID.fromString(uuidStr);
-                if (uuid.equals(allowedUuid)) {
-                    if(verbose) {
-                        console.sendMessage(String.format("allowlist: %s allowed", uuid.toString()));
-                    }
-                    return true;
-                }
-            }
-        } catch (IllegalArgumentException e) {
-            if (verbose) {
-                console.sendMessage(e.toString());
-            }
-            return false;
-        } catch (FileNotFoundException e) {
-            if (verbose) {
-                console.sendMessage(String.format("allowlist: no allowlist: %s allowed", uuid.toString()));
-            }
-            return true;
-        } catch (IOException e) {
-            if (verbose) {
-                console.sendMessage(String.format("allowlist: %s", e.toString()));
-            }
-            return false;
-        } catch (ParseException e) {
-            if (verbose) {
-                console.sendMessage(String.format(" allowlist: parse: %s", e.toString()));
-            }
-            return false;
-        }
-
-        if (verbose) {
-            console.sendMessage(String.format("allowlist: %s is not allowed", uuid.toString()));
-        }
-        return false;
-    }
-
     @SuppressWarnings("deprecation")
     @Override
     public void run() {
@@ -553,7 +470,7 @@ public class ClientConnection extends Thread {
 
                                 UUID uuid = isBungeecord || isBungeeGuard ? bungeeUUID : UUID.nameUUIDFromBytes(("OfflinePlayer:" + username).getBytes(StandardCharsets.UTF_8));
 
-                                if (!uuidAllowed(uuid, !properties.isReducedDebugInfo())) {
+                                if (!Limbo.getInstance().uuidIsAllowed(uuid)) {
                                     disconnectDuringLogin(TextComponent.fromLegacyText("You are not invited to this server"));
                                     break;
                                 }