feat: Add more options for ping passthrough

proxy/src/main/java/com/velocitypowered/proxy/config/LegacyPingPassthroughMode.java

@@ -0,0 +1,28 @@
+/*
+ * Copyright (C) 2018-2023 Velocity Contributors
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <https://www.gnu.org/licenses/>.
+ */
+
+package com.velocitypowered.proxy.config;
+
+/**
+ * Legacy modes for ping passthrough.
+ */
+public enum LegacyPingPassthroughMode {
+  DISABLED,
+  MODS,
+  DESCRIPTION,
+  ALL
+}

proxy/src/main/java/com/velocitypowered/proxy/config/PingPassthroughMode.java

@@ -18,11 +18,36 @@
 package com.velocitypowered.proxy.config;
 
 /**
- * Supported passthrough modes for ping passthrough.
+ * Object to contain all the things that can be toggled for ping passthrough.
  */
-public enum PingPassthroughMode {
-  DISABLED,
-  MODS,
-  DESCRIPTION,
-  ALL
+public class PingPassthroughMode {
+  public boolean version;
+  public boolean players;
+  public boolean description;
+  public boolean favicon;
+  public boolean modinfo;
+
+  /**
+   * Passthrough mode constructor.
+   * Looking at other code, I'm not sure the constructor is supposed to need a javadoc style comment,
+   * but checkstyle was yelling at me because I didn't include one.
+   * Probably for the best.
+   *
+   * @param version Whether the version should be passed through.
+   * @param players Whether the player count should be passed through.
+   * @param description Whether the description should be passed through.
+   * @param favicon Whether the favicon should be passed through.
+   * @param modinfo Whether the modinfo should be passed through.
+   */
+  public PingPassthroughMode(boolean version, boolean players, boolean description, boolean favicon, boolean modinfo) {
+    this.version = version;
+    this.players = players;
+    this.description = description;
+    this.favicon = favicon;
+    this.modinfo = modinfo;
+  }
+
+  public boolean enabled() {
+    return this.version || this.players || this.description || this.favicon || this.modinfo;
+  }
 }

proxy/src/main/java/com/velocitypowered/proxy/config/VelocityConfiguration.java

@@ -30,6 +30,7 @@
 import com.velocitypowered.proxy.config.migration.ForwardingMigration;
 import com.velocitypowered.proxy.config.migration.KeyAuthenticationMigration;
 import com.velocitypowered.proxy.config.migration.MotdMigration;
+import com.velocitypowered.proxy.config.migration.PingPassthroughMigration;
 import com.velocitypowered.proxy.config.migration.TransferIntegrationMigration;
 import com.velocitypowered.proxy.util.AddressUtil;
 import edu.umd.cs.findbugs.annotations.SuppressFBWarnings;
@@ -77,7 +78,7 @@ public class VelocityConfiguration implements ProxyConfig {
   @Expose
   private boolean onlineModeKickExistingPlayers = false;
   @Expose
-  private PingPassthroughMode pingPassthrough = PingPassthroughMode.DISABLED;
+  private PingPassthroughMode pingPassthrough = new PingPassthroughMode(false, false, false, false, false);
   @Expose
   private boolean samplePlayersInPing = false;
   private final Servers servers;
@@ -108,8 +109,7 @@ private VelocityConfiguration(String bind, String motd, int showMaxPlayers, bool
       PlayerInfoForwarding playerInfoForwardingMode, byte[] forwardingSecret,
       boolean onlineModeKickExistingPlayers, PingPassthroughMode pingPassthrough,
       boolean samplePlayersInPing, boolean enablePlayerAddressLogging, Servers servers,
-      ForcedHosts forcedHosts, Advanced advanced, Query query, Metrics metrics,
-      boolean forceKeyAuthentication) {
+      ForcedHosts forcedHosts, Advanced advanced, Query query, Metrics metrics, boolean forceKeyAuthentication) {
     this.bind = bind;
     this.motd = motd;
     this.showMaxPlayers = showMaxPlayers;
@@ -504,7 +504,8 @@ public static VelocityConfiguration read(Path path) throws IOException {
           new ForwardingMigration(),
           new KeyAuthenticationMigration(),
           new MotdMigration(),
-          new TransferIntegrationMigration()
+          new TransferIntegrationMigration(),
+          new PingPassthroughMigration()
       };
 
       for (final ConfigurationMigration migration : migrations) {
@@ -542,9 +543,12 @@ public static VelocityConfiguration read(Path path) throws IOException {
       final CommentedConfig metricsConfig = config.get("metrics");
       final PlayerInfoForwarding forwardingMode = config.getEnumOrElse(
               "player-info-forwarding-mode", PlayerInfoForwarding.NONE);
-      final PingPassthroughMode pingPassthroughMode = config.getEnumOrElse("ping-passthrough",
-              PingPassthroughMode.DISABLED);
-
+      final PingPassthroughMode pingPassthrough = new PingPassthroughMode(
+              config.getOrElse("ping-passthrough-version", false),
+              config.getOrElse("ping-passthrough-players", false),
+              config.getOrElse("ping-passthrough-description", false),
+              config.getOrElse("ping-passthrough-favicon", false),
+              config.getOrElse("ping-passthrough-modinfo", false));
       final boolean samplePlayersInPing = config.getOrElse("sample-players-in-ping", false);
 
       final String bind = config.getOrElse("bind", "0.0.0.0:25565");
@@ -576,7 +580,7 @@ public static VelocityConfiguration read(Path path) throws IOException {
               forwardingMode,
               forwardingSecret,
               kickExisting,
-              pingPassthroughMode,
+              pingPassthrough,
               samplePlayersInPing,
               enablePlayerAddressLogging,
               new Servers(serversConfig),

proxy/src/main/java/com/velocitypowered/proxy/config/migration/ConfigurationMigration.java

@@ -28,7 +28,8 @@ public sealed interface ConfigurationMigration
         permits ForwardingMigration,
                 KeyAuthenticationMigration,
                 MotdMigration,
-                TransferIntegrationMigration {
+                TransferIntegrationMigration,
+                PingPassthroughMigration {
   boolean shouldMigrate(CommentedFileConfig config);
 
   void migrate(CommentedFileConfig config, Logger logger) throws IOException;

proxy/src/main/java/com/velocitypowered/proxy/config/migration/PingPassthroughMigration.java

@@ -0,0 +1,87 @@
+/*
+ * Copyright (C) 2024 Velocity Contributors
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <https://www.gnu.org/licenses/>.
+ */
+
+package com.velocitypowered.proxy.config.migration;
+
+import com.electronwill.nightconfig.core.file.CommentedFileConfig;
+import com.velocitypowered.proxy.config.LegacyPingPassthroughMode;
+import org.apache.logging.log4j.Logger;
+
+/**
+ * Migrate the old ping passthrough entry to separate config entries.
+ */
+public final class PingPassthroughMigration implements ConfigurationMigration {
+  @Override
+  public boolean shouldMigrate(final CommentedFileConfig config) {
+    return configVersion(config) < 2.8;
+  }
+
+  @Override
+  public void migrate(final CommentedFileConfig config, final Logger logger) {
+    // Get legacy ping passthrough value
+    final LegacyPingPassthroughMode legacyMode = config.getEnumOrElse("ping-passthrough",
+        LegacyPingPassthroughMode.DISABLED);
+
+    config.removeComment("ping-passthrough");
+    config.remove("ping-passthrough");
+
+    // Create ping passthrough entry for the version
+    config.set("ping-passthrough-version", legacyMode.equals(LegacyPingPassthroughMode.ALL));
+    config.setComment(
+        "ping-passthrough-version",
+        " Should Velocity pass the version number from the backend server when responding to server list ping requests?"
+    );
+
+    // Create ping passthrough entry for the players
+    config.set("ping-passthrough-players", legacyMode.equals(LegacyPingPassthroughMode.ALL));
+    config.setComment(
+        "ping-passthrough-players",
+        " Should Velocity pass the player count from the backend server when responding to server list ping requests?"
+    );
+
+    // Create ping passthrough entry for the description
+    config.set("ping-passthrough-description",
+        legacyMode.equals(LegacyPingPassthroughMode.ALL)
+            || legacyMode.equals(LegacyPingPassthroughMode.DESCRIPTION)
+    );
+    config.setComment(
+        "ping-passthrough-description",
+        " Should Velocity pass the description from the backend server when responding to server list ping requests?"
+    );
+
+    // Create ping passthrough entry for the favicon
+    config.set("ping-passthrough-favicon", legacyMode.equals(LegacyPingPassthroughMode.ALL));
+    config.setComment(
+        "ping-passthrough-favicon",
+        " Should Velocity pass the favicon (also known as the server icon) from the backend server when responding to server list ping requests?"
+    );
+
+    // Create ping passthrough entry for the mods info
+    config.set("ping-passthrough-modinfo",
+        legacyMode.equals(LegacyPingPassthroughMode.ALL)
+            || legacyMode.equals(LegacyPingPassthroughMode.MODS)
+            || legacyMode.equals(LegacyPingPassthroughMode.DESCRIPTION)
+    );
+    config.setComment(
+        "ping-passthrough-modinfo",
+        " Should Velocity pass the mod list from the backend server when responding to server list ping requests?"
+    );
+
+    // Update config version
+    config.set("config-version", "2.8");
+  }
+}

proxy/src/main/java/com/velocitypowered/proxy/connection/util/ServerListPingHandler.java

@@ -23,6 +23,7 @@
 import com.velocitypowered.api.proxy.server.PingOptions;
 import com.velocitypowered.api.proxy.server.RegisteredServer;
 import com.velocitypowered.api.proxy.server.ServerPing;
+import com.velocitypowered.api.util.Favicon;
 import com.velocitypowered.api.util.ModInfo;
 import com.velocitypowered.proxy.VelocityServer;
 import com.velocitypowered.proxy.config.PingPassthroughMode;
@@ -99,58 +100,64 @@ private CompletableFuture<ServerPing> attemptPingPassthrough(VelocityInboundConn
 
     CompletableFuture<List<ServerPing>> pingResponses = CompletableFutures.successfulAsList(pings,
         (ex) -> fallback);
-    switch (mode) {
-      case ALL:
-        return pingResponses.thenApply(responses -> {
-          // Find the first non-fallback
-          for (ServerPing response : responses) {
-            if (response == fallback) {
-              continue;
-            }
-            return response;
-          }
-          return fallback;
-        });
-      case MODS:
-        return pingResponses.thenApply(responses -> {
-          // Find the first non-fallback that contains a mod list
-          for (ServerPing response : responses) {
-            if (response == fallback) {
-              continue;
-            }
-            Optional<ModInfo> modInfo = response.getModinfo();
-            if (modInfo.isPresent()) {
-              return fallback.asBuilder().mods(modInfo.get()).build();
-            }
-          }
-          return fallback;
-        });
-      case DESCRIPTION:
-        return pingResponses.thenApply(responses -> {
-          // Find the first non-fallback. If it includes a modlist, add it too.
-          for (ServerPing response : responses) {
-            if (response == fallback) {
-              continue;
-            }
-
-            if (response.getDescriptionComponent() == null) {
-              continue;
-            }
-
-            return new ServerPing(
-                fallback.getVersion(),
-                fallback.getPlayers().orElse(null),
-                response.getDescriptionComponent(),
-                fallback.getFavicon().orElse(null),
-                response.getModinfo().orElse(null)
-            );
-          }
-          return fallback;
-        });
-      // Not possible, but covered for completeness.
-      default:
-        return CompletableFuture.completedFuture(fallback);
+
+    // Return early if ping passthrough is not enabled
+    if (!mode.enabled()) {
+      return CompletableFuture.completedFuture(fallback);
     }
+
+    return pingResponses.thenApply(responses -> {
+      // Find the first non-fallback
+      for (ServerPing response : responses) {
+        if (response == fallback) {
+          continue;
+        }
+
+        ServerPing.Version version;
+        if (mode.version) {
+          version = response.getVersion();
+        } else {
+          version = fallback.getVersion();
+        }
+
+        ServerPing.Players players;
+        if (mode.players) {
+          players = response.getPlayers().orElse(null);
+        } else {
+          players = fallback.getPlayers().orElse(null);
+        }
+
+        net.kyori.adventure.text.Component description;
+        if (mode.description && response.getDescriptionComponent() != null) {
+          description = response.getDescriptionComponent();
+        } else {
+          description = fallback.getDescriptionComponent();
+        }
+
+        Favicon favicon;
+        if (mode.favicon) {
+          favicon = response.getFavicon().orElse(null);
+        } else {
+          favicon = fallback.getFavicon().orElse(null);
+        }
+
+        ModInfo modinfo;
+        if (mode.modinfo) {
+          modinfo = response.getModinfo().orElse(null);
+        } else {
+          modinfo = fallback.getModinfo().orElse(null);
+        }
+
+        return new ServerPing(
+            version,
+            players,
+            description,
+            favicon,
+            modinfo
+        );
+      }
+      return fallback;
+    });
   }
 
   /**
@@ -165,7 +172,7 @@ public CompletableFuture<ServerPing> getInitialPing(VelocityInboundConnection co
         ? connection.getProtocolVersion() : ProtocolVersion.MAXIMUM_VERSION;
     PingPassthroughMode passthroughMode = configuration.getPingPassthrough();
 
-    if (passthroughMode == PingPassthroughMode.DISABLED) {
+    if (!passthroughMode.enabled()) {
       return CompletableFuture.completedFuture(constructLocalPing(shownVersion));
     } else {
       String virtualHostStr = connection.getVirtualHost().map(InetSocketAddress::getHostString)