Refactor of checkPlayer logic to fix potential concurrency issues. This was a poor design. Also implemented gradle tooling for debugging velocity plugins

.gitignore

@@ -295,4 +295,5 @@ $RECYCLE.BIN/
 
 # End of https://www.toptal.com/developers/gitignore/api/windows,macos,linux,maven,java,intellij,eclipse,netbeans
 /.gradle/
-.grade/**
+.grade/**
+/run/

Bukkit/Plugin/src/main/java/dev/brighten/antivpn/bukkit/BukkitListener.java

@@ -18,6 +18,7 @@ package dev.brighten.antivpn.bukkit;
 
 import dev.brighten.antivpn.AntiVPN;
 import dev.brighten.antivpn.api.APIPlayer;
+import dev.brighten.antivpn.api.CheckResult;
 import dev.brighten.antivpn.api.OfflinePlayer;
 import dev.brighten.antivpn.api.VPNExecutor;
 import dev.brighten.antivpn.utils.StringUtil;
@@ -82,28 +83,28 @@ public class BukkitListener extends VPNExecutor implements Listener {
                         event.getAddress()
                 ));
 
-        player.checkPlayer(result -> {
+        CheckResult result = player.checkPlayer();
-            if(!result.resultType().isShouldBlock()) return;
 
-            if(!AntiVPN.getInstance().getVpnConfig().isKickPlayers()) {
+        if(!result.resultType().isShouldBlock()) return;
-                return;
-            }
 
-            event.setResult(PlayerLoginEvent.Result.KICK_BANNED);
+        if(!AntiVPN.getInstance().getVpnConfig().isKickPlayers()) {
-            event.setKickMessage(switch (result.resultType()) {
+            return;
-                case DENIED_COUNTRY -> StringUtil.varReplace(
+        }
-                        AntiVPN.getInstance().getVpnConfig().getCountryVanillaKickReason(),
+
-                        player,
+        event.setResult(PlayerLoginEvent.Result.KICK_BANNED);
-                        result.response()
+        event.setKickMessage(switch (result.resultType()) {
-                );
+            case DENIED_COUNTRY -> StringUtil.varReplace(
-                case DENIED_PROXY ->
+                    AntiVPN.getInstance().getVpnConfig().getCountryVanillaKickReason(),
-                        StringUtil.varReplace(
+                    player,
-                                AntiVPN.getInstance().getVpnConfig().getKickMessage(),
+                    result.response()
-                                player,
+            );
-                                result.response()
+            case DENIED_PROXY ->
-                        );
+                    StringUtil.varReplace(
-                default -> "You were kicked by KauriVPN for an unknown reason!";
+                            AntiVPN.getInstance().getVpnConfig().getKickMessage(),
-            });
+                            player,
+                            result.response()
+                    );
+            default -> "You were kicked by KauriVPN for an unknown reason!";
         });
     }
 

Bungee/BungeePlugin/src/main/java/dev/brighten/antivpn/bungee/BungeeListener.java

@@ -77,7 +77,6 @@ public class BungeeListener extends VPNExecutor implements Listener {
 
     @EventHandler(priority = EventPriority.HIGH)
     public void onListener(final PreLoginEvent event) {
-
         APIPlayer player = AntiVPN.getInstance().getPlayerExecutor().getPlayer(event.getConnection().getUniqueId())
                 .orElseGet(() -> {
                     UUID uuid = MiscUtils.lookupUUID(event.getConnection().getName());
@@ -88,22 +87,22 @@ public class BungeeListener extends VPNExecutor implements Listener {
                             ((InetSocketAddress) event.getConnection().getSocketAddress()).getAddress());
                 });
 
-        player.checkPlayer(result -> {
+        CheckResult result = player.checkPlayer();
-            if (!result.resultType().isShouldBlock()) return;
 
-            if(!AntiVPN.getInstance().getVpnConfig().isKickPlayers()) {
+        if (!result.resultType().isShouldBlock()) return;
-                return;
-            }
 
-            event.setCancelled(true);
+        if(!AntiVPN.getInstance().getVpnConfig().isKickPlayers()) {
-            event.setReason(TextComponent.fromLegacy(StringUtil.varReplace(switch (result.resultType()) {
+            return;
-                case DENIED_PROXY -> StringUtil.varReplace(AntiVPN.getInstance().getVpnConfig()
+        }
-                        .getKickMessage(), player, result.response());
+
-                case DENIED_COUNTRY -> StringUtil.varReplace(AntiVPN.getInstance().getVpnConfig()
+        event.setCancelled(true);
-                        .getCountryVanillaKickReason(), player, result.response());
+        event.setReason(TextComponent.fromLegacy(StringUtil.varReplace(switch (result.resultType()) {
-                default -> "You were kicked by KauriVPN for an unknown reason!";
+            case DENIED_PROXY -> StringUtil.varReplace(AntiVPN.getInstance().getVpnConfig()
-            }, player, result.response())));
+                    .getKickMessage(), player, result.response());
-        });
+            case DENIED_COUNTRY -> StringUtil.varReplace(AntiVPN.getInstance().getVpnConfig()
+                    .getCountryVanillaKickReason(), player, result.response());
+            default -> "You were kicked by KauriVPN for an unknown reason!";
+        }, player, result.response())));
     }
 
     @EventHandler(priority = EventPriority.HIGH)

Common/Source/src/main/java/dev/brighten/antivpn/api/APIPlayer.java

@@ -26,7 +26,6 @@ import lombok.Setter;
 import java.net.InetAddress;
 import java.util.UUID;
 import java.util.concurrent.TimeUnit;
-import java.util.function.Consumer;
 import java.util.logging.Level;
 
 @Getter
@@ -74,7 +73,12 @@ public abstract class APIPlayer {
         );
     }
 
-    public void checkPlayer(Consumer<CheckResult> onResult) {
+    /***
+     * The result is only returned if it is cached. Otherwise, there is an asynchronous call to the API
+     * and will handle kicking the player if necessary.
+     * @return CheckResult - The cached result of the check if it exists.
+     */
+    public CheckResult checkPlayer() {
         if (hasPermission("antivpn.bypass") //Has bypass permission
                 //Is exempt
                 || (uuid != null && AntiVPN.getInstance().getExecutor().isWhitelisted(uuid))
@@ -82,8 +86,7 @@ public abstract class APIPlayer {
                 || AntiVPN.getInstance().getExecutor().isWhitelisted(ip.getHostAddress() + "/32")
                 || AntiVPN.getInstance().getVpnConfig().getPrefixWhitelists().stream()
                 .anyMatch(name::startsWith)) {
-            onResult.accept(new CheckResult(null, ResultType.WHITELISTED, false));
+            return new CheckResult(null, ResultType.WHITELISTED, false);
-            return;
         }
 
         CheckResult cachedResult = checkResultCache.getIfPresent(ip.getHostAddress());
@@ -94,8 +97,7 @@ public abstract class APIPlayer {
                 if(cachedResult.resultType().isShouldBlock()) {
                     AntiVPN.getInstance().getExecutor().handleKickingOfPlayer(cachedResult, this);
                 }
-                onResult.accept(cachedResult);
+                return cachedResult;
-                return;
             }
         }
 
@@ -105,7 +107,6 @@ public abstract class APIPlayer {
                         AntiVPN.getInstance().getExecutor().log(Level.WARNING, "The API query was not a success! " +
                                 "You may need to upgrade your license on " +
                                 "https://funkemunky.cc/shop");
-                        onResult.accept(new CheckResult(null, ResultType.API_FAILURE, false));
                         return;
                     }
                     // If the countryList() size is zero, no need to check.
@@ -137,9 +138,8 @@ public abstract class APIPlayer {
                     if(checkResult.resultType().isShouldBlock()) {
                         AntiVPN.getInstance().getExecutor().handleKickingOfPlayer(checkResult, this);
                     }
-                    onResult.accept(checkResult);
                     AntiVPN.getInstance().checked++;
                 });
-        onResult.accept(new CheckResult(null, ResultType.UNKNOWN, false));
+       return new CheckResult(null, ResultType.UNKNOWN, false);
     }
 }

Common/Source/src/main/java/dev/brighten/antivpn/utils/Suppliers.java

@@ -16,6 +16,7 @@
 
 package dev.brighten.antivpn.utils;
 
+import java.io.Serial;
 import java.io.Serializable;
 
 import static dev.brighten.antivpn.utils.NullnessCasts.uncheckedCastNullableTToT;
@@ -36,7 +37,7 @@ public final class Suppliers {
 
     /**
      * Returns a supplier which caches the instance retrieved during the first call to {@code get()}
-     * and returns that value on subsequent calls to {@code get()}. See: <a
+     * and returns that value on later calls to {@code get()}. See: <a
      * href="http://en.wikipedia.org/wiki/Memoization">memoization</a>
      *
      * <p>The returned supplier is thread-safe. The delegate's {@code get()} method will be invoked at
@@ -44,7 +45,7 @@ public final class Suppliers {
      * form does not contain the cached value, which will be recalculated when {@code get()} is called
      * on the reserialized instance.
      *
-     * <p>When the underlying delegate throws an exception then this memoizing supplier will keep
+     * <p>When the underlying delegate throws an exception then this memorizing supplier will keep
      * delegating calls until it returns valid data.
      *
      * <p>If {@code delegate} is an instance created by an earlier call to {@code memoize}, it is
@@ -95,6 +96,7 @@ public final class Suppliers {
                     + ")";
         }
 
+        @Serial
         private static final long serialVersionUID = 0;
     }
 

README.md

@@ -8,3 +8,18 @@ Just a simple plugin using an incredibly fast and accurate API.
 
 ## SpigotMC Page
 Rate and support the project on SpigotMC: https://www.spigotmc.org/resources/kaurivpn-anti-proxy-tor-and-vpn-free-api.93355/
+
+## Velocity Debugging
+Run a generated local Velocity proxy with the AntiVPN Velocity loader installed:
+
+```bash
+./gradlew runVelocity
+```
+
+Run the proxy suspended for IDE debugger attach on port `5005`:
+
+```bash
+./gradlew debugVelocity
+```
+
+In IntelliJ IDEA, use the Gradle `debugVelocity` task and attach a remote JVM debugger to `localhost:5005`.

Sponge/SpongePlugin/src/main/java/dev/brighten/antivpn/sponge/SpongeListener.java

@@ -41,22 +41,22 @@ public class SpongeListener extends VPNExecutor {
                         event.connection().address().getAddress()
                 )));
 
-        player.get().checkPlayer(result -> {
+        CheckResult result = player.get().checkPlayer();
-            if(!result.resultType().isShouldBlock()) return;
 
-            if(!AntiVPN.getInstance().getVpnConfig().isKickPlayers()) {
+        if(!result.resultType().isShouldBlock()) return;
-                return;
-            }
 
-            event.setCancelled(true);
+        if(!AntiVPN.getInstance().getVpnConfig().isKickPlayers()) {
-            event.setMessage(Component.text(switch (result.resultType()) {
+            return;
-                case DENIED_PROXY -> StringUtil.varReplace(AntiVPN.getInstance().getVpnConfig()
+        }
-                        .getKickMessage(), player.get(), result.response());
+
-                case DENIED_COUNTRY -> StringUtil.varReplace(AntiVPN.getInstance().getVpnConfig()
+        event.setCancelled(true);
-                        .getCountryVanillaKickReason(), player.get(), result.response());
+        event.setMessage(Component.text(switch (result.resultType()) {
-                default -> "You were kicked by KauriVPN for an unknown reason!";
+            case DENIED_PROXY -> StringUtil.varReplace(AntiVPN.getInstance().getVpnConfig()
-            }));
+                    .getKickMessage(), player.get(), result.response());
-        });
+            case DENIED_COUNTRY -> StringUtil.varReplace(AntiVPN.getInstance().getVpnConfig()
+                    .getCountryVanillaKickReason(), player.get(), result.response());
+            default -> "You were kicked by KauriVPN for an unknown reason!";
+        }));
     }
 
     @Listener

Velocity/VelocityLoader/build.gradle

@@ -1,5 +1,6 @@
 plugins {
     id 'com.gradleup.shadow'
+    id 'xyz.jpenilla.run-velocity'
 }
 
 evaluationDependsOn(':Velocity:VelocityPlugin')
@@ -25,16 +26,44 @@ shadowJar {
         rename { 'antivpn-velocity.jarinjar' }
     }
 
+    // Include the shared shaded source jar required by JarInJarClassLoader.
+    from(project(':Common:Source').tasks.named('shadowJar')) {
+        rename { 'antivpn-source.jarinjar' }
+    }
+
     relocate 'org.bstats', 'dev.brighten.antivpn.velocity.org.bstats'
     relocate 'org.yaml.snakeyaml', 'dev.brighten.antivpn.shaded.org.yaml.snakeyaml'
 }
 
 tasks.named('shadowJar') {
+    dependsOn(':Common:Source:shadowJar')
     dependsOn(':Velocity:VelocityPlugin:shadowJar')
 }
 
 tasks.build.dependsOn shadowJar
 
+tasks.named('runVelocity') {
+    velocityVersion('3.4.0-SNAPSHOT')
+    runDirectory.set(rootProject.layout.projectDirectory.dir('run/velocity'))
+    pluginJars.from(tasks.named('shadowJar'))
+    dependsOn(tasks.named('shadowJar'))
+}
+
+tasks.register('debugVelocity', xyz.jpenilla.runvelocity.task.RunVelocity) {
+    group = 'Run Velocity'
+    description = 'Run a local Velocity proxy for plugin debugging on port 5005.'
+    velocityVersion('3.4.0-SNAPSHOT')
+    runDirectory.set(rootProject.layout.projectDirectory.dir('run/velocity'))
+    pluginJars.from(tasks.named('shadowJar'))
+    dependsOn(tasks.named('shadowJar'))
+    debugOptions {
+        enabled = true
+        port = 5005
+        server = true
+        suspend = true
+    }
+}
+
 jar {
     archiveClassifier.set('raw')
 }

Velocity/VelocityPlugin/src/main/java/dev/brighten/antivpn/velocity/VelocityListener.java

@@ -21,6 +21,7 @@ import com.velocitypowered.api.event.connection.DisconnectEvent;
 import com.velocitypowered.api.event.connection.LoginEvent;
 import dev.brighten.antivpn.AntiVPN;
 import dev.brighten.antivpn.api.APIPlayer;
+import dev.brighten.antivpn.api.CheckResult;
 import dev.brighten.antivpn.api.OfflinePlayer;
 import dev.brighten.antivpn.api.VPNExecutor;
 import dev.brighten.antivpn.utils.StringUtil;
@@ -52,35 +53,35 @@ public class VelocityListener extends VPNExecutor {
                         event.getPlayer().getRemoteAddress().getAddress()
                 ));
 
-        player.checkPlayer(result -> {
+        CheckResult result = player.checkPlayer();
-            if(!result.resultType().isShouldBlock()) return;
 
-            if(!AntiVPN.getInstance().getVpnConfig().isKickPlayers()) {
+        if(!result.resultType().isShouldBlock()) return;
-                return;
-            }
 
-            switch (result.resultType()) {
+        if(!AntiVPN.getInstance().getVpnConfig().isKickPlayers()) {
-                case DENIED_COUNTRY -> event.setResult(ResultedEvent.ComponentResult.denied(
+            return;
-                        LegacyComponentSerializer.builder()
+        }
-                                .character('&')
+
-                                .build().deserialize(AntiVPN.getInstance().getVpnConfig()
+        switch (result.resultType()) {
-                                        .getCountryVanillaKickReason()
+            case DENIED_COUNTRY -> event.setResult(ResultedEvent.ComponentResult.denied(
-                                        .replace("%player%", event.getPlayer().getUsername())
+                    LegacyComponentSerializer.builder()
-                                        .replace("%country%", result.response().getCountryName())
-                                        .replace("%code%", result.response().getCountryCode()))));
-                case DENIED_PROXY -> {
-                    VelocityPlugin.INSTANCE.getLogger().info(event.getPlayer().getUsername()
-                            + " joined on a VPN/Proxy (" + result.response().getMethod() + ")");
-                    event.setResult(ResultedEvent.ComponentResult.denied(LegacyComponentSerializer.builder()
                             .character('&')
                             .build().deserialize(AntiVPN.getInstance().getVpnConfig()
-                                    .getKickMessage()
+                                    .getCountryVanillaKickReason()
                                     .replace("%player%", event.getPlayer().getUsername())
                                     .replace("%country%", result.response().getCountryName())
                                     .replace("%code%", result.response().getCountryCode()))));
-                }
+            case DENIED_PROXY -> {
+                VelocityPlugin.INSTANCE.getLogger().info(event.getPlayer().getUsername()
+                        + " joined on a VPN/Proxy (" + result.response().getMethod() + ")");
+                event.setResult(ResultedEvent.ComponentResult.denied(LegacyComponentSerializer.builder()
+                        .character('&')
+                        .build().deserialize(AntiVPN.getInstance().getVpnConfig()
+                                .getKickMessage()
+                                .replace("%player%", event.getPlayer().getUsername())
+                                .replace("%country%", result.response().getCountryName())
+                                .replace("%code%", result.response().getCountryCode()))));
             }
-        });
+        }
     }
 
     @Override

build.gradle

@@ -1,6 +1,7 @@
 plugins {
     id 'java'
     id 'com.gradleup.shadow' version '9.4.1'
+    id 'xyz.jpenilla.run-velocity' version '3.0.2' apply false
 }
 
 def aggregateTestProjects = [
@@ -101,3 +102,15 @@ tasks.named('shadowJar') {
 }
 
 tasks.build.dependsOn shadowJar
+
+tasks.register('runVelocity') {
+    group = 'run'
+    description = 'Starts a local Velocity proxy with the AntiVPN Velocity loader installed.'
+    dependsOn(':Velocity:VelocityLoader:runVelocity')
+}
+
+tasks.register('debugVelocity') {
+    group = 'run'
+    description = 'Starts a local Velocity proxy suspended for debugger attach on port 5005.'
+    dependsOn(':Velocity:VelocityLoader:debugVelocity')
+}