Add Virtualhost support for server list pings (#1265)

* Add virtualhost support for server list pings

* Add virtualhost support to ping public API

* Applied suggestions

* fixed checkstyle

* Added nullable annotation

---------

Co-authored-by: Adrian <adriangonzalesval@gmail.com>

api/src/main/java/com/velocitypowered/api/proxy/server/PingOptions.java

@@ -15,6 +15,7 @@ import java.util.Objects;
 import java.util.concurrent.TimeUnit;
 import net.kyori.adventure.builder.AbstractBuilder;
 import org.jetbrains.annotations.NotNull;
+import org.jetbrains.annotations.Nullable;
 
 /**
  * Contains the parameters used to ping a {@link RegisteredServer}.
@@ -30,10 +31,12 @@ public final class PingOptions {
   public static final PingOptions DEFAULT = PingOptions.builder().build();
   private final ProtocolVersion protocolVersion;
   private final long timeout;
+  private final String virtualHost;
 
   private PingOptions(final Builder builder) {
     this.protocolVersion = builder.protocolVersion;
     this.timeout = builder.timeout;
+    this.virtualHost = builder.virtualHost;
   }
 
   /**
@@ -54,6 +57,16 @@ public final class PingOptions {
     return this.timeout;
   }
 
+  /**
+   * The virtual host to pass to the server for the ping.
+   *
+   * @return the virtual hostname to pass to the server for the ping
+   * @since 3.4.0
+   */
+  public @Nullable String getVirtualHost() {
+    return this.virtualHost;
+  }
+
   /**
    * Create a new builder to assign values to a new PingOptions.
    *
@@ -68,10 +81,9 @@ public final class PingOptions {
     if (o == null) {
       return false;
     }
-    if (!(o instanceof PingOptions)) {
+    if (!(o instanceof final PingOptions other)) {
       return false;
     }
-    final PingOptions other = (PingOptions) o;
     return Objects.equals(this.protocolVersion, other.protocolVersion)
             && Objects.equals(this.timeout, other.timeout);
   }
@@ -97,6 +109,7 @@ public final class PingOptions {
   public static final class Builder implements AbstractBuilder<PingOptions> {
     private ProtocolVersion protocolVersion = ProtocolVersion.UNKNOWN;
     private long timeout = 0;
+    private String virtualHost = null;
 
     private Builder() {
     }
@@ -146,6 +159,18 @@ public final class PingOptions {
       return this;
     }
 
+    /**
+     * Sets the virtual host to pass to the server for the ping.
+     *
+     * @param virtualHost the virtual hostname to pass to the server for the ping
+     * @return this builder
+     * @since 3.4.0
+     */
+    public Builder virtualHost(final @Nullable String virtualHost) {
+      this.virtualHost = virtualHost;
+      return this;
+    }
+
     /**
      * Create a new {@link PingOptions} with the values of this Builder.
      *

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

@@ -63,7 +63,7 @@ public class ServerListPingHandler {
   }
 
   private CompletableFuture<ServerPing> attemptPingPassthrough(VelocityInboundConnection connection,
-      PingPassthroughMode mode, List<String> servers, ProtocolVersion responseProtocolVersion) {
+      PingPassthroughMode mode, List<String> servers, ProtocolVersion responseProtocolVersion, String virtualHostStr) {
     ServerPing fallback = constructLocalPing(connection.getProtocolVersion());
     List<CompletableFuture<ServerPing>> pings = new ArrayList<>();
     for (String s : servers) {
@@ -73,7 +73,7 @@ public class ServerListPingHandler {
       }
       VelocityRegisteredServer vrs = (VelocityRegisteredServer) rs.get();
       pings.add(vrs.ping(connection.getConnection().eventLoop(), PingOptions.builder()
-              .version(responseProtocolVersion).build()));
+              .version(responseProtocolVersion).virtualHost(virtualHostStr).build()));
     }
     if (pings.isEmpty()) {
       return CompletableFuture.completedFuture(fallback);
@@ -155,7 +155,7 @@ public class ServerListPingHandler {
           .orElse("");
       List<String> serversToTry = server.getConfiguration().getForcedHosts().getOrDefault(
           virtualHostStr, server.getConfiguration().getAttemptConnectionOrder());
-      return attemptPingPassthrough(connection, passthroughMode, serversToTry, shownVersion);
+      return attemptPingPassthrough(connection, passthroughMode, serversToTry, shownVersion, virtualHostStr);
     }
   }
 }

proxy/src/main/java/com/velocitypowered/proxy/server/PingSessionHandler.java

@@ -43,20 +43,23 @@ public class PingSessionHandler implements MinecraftSessionHandler {
   private final MinecraftConnection connection;
   private final ProtocolVersion version;
   private boolean completed = false;
+  private final String virtualHostString;
 
   PingSessionHandler(CompletableFuture<ServerPing> result, RegisteredServer server,
-      MinecraftConnection connection, ProtocolVersion version) {
+      MinecraftConnection connection, ProtocolVersion version, String virtualHostString) {
     this.result = result;
     this.server = server;
     this.connection = connection;
     this.version = version;
+    this.virtualHostString = virtualHostString;
   }
 
   @Override
   public void activated() {
     HandshakePacket handshake = new HandshakePacket();
     handshake.setIntent(HandshakeIntent.STATUS);
-    handshake.setServerAddress(server.getServerInfo().getAddress().getHostString());
+    handshake.setServerAddress(this.virtualHostString == null || this.virtualHostString.isEmpty()
+            ? server.getServerInfo().getAddress().getHostString() : this.virtualHostString);
     handshake.setPort(server.getServerInfo().getAddress().getPort());
     handshake.setProtocolVersion(version);
     connection.delayedWrite(handshake);

proxy/src/main/java/com/velocitypowered/proxy/server/VelocityRegisteredServer.java

@@ -129,7 +129,7 @@ public class VelocityRegisteredServer implements RegisteredServer, ForwardingAud
       if (future.isSuccess()) {
         MinecraftConnection conn = future.channel().pipeline().get(MinecraftConnection.class);
         PingSessionHandler handler = new PingSessionHandler(pingFuture,
-            VelocityRegisteredServer.this, conn, pingOptions.getProtocolVersion());
+            VelocityRegisteredServer.this, conn, pingOptions.getProtocolVersion(), pingOptions.getVirtualHost());
         conn.setActiveSessionHandler(StateRegistry.HANDSHAKE, handler);
       } else {
         pingFuture.completeExceptionally(future.cause());