Implement basic udp query to close #185

api/src/main/java/net/md_5/bungee/api/config/ListenerInfo.java

@@ -61,4 +61,12 @@ public class ListenerInfo
      * server (force default server).
      */
     private final boolean pingPassthrough;
+    /**
+     * What port to run udp query on.
+     */
+    private final int queryPort;
+    /**
+     * Whether to enable udp query.
+     */
+    private final boolean queryEnabled;
 }

pom.xml

@@ -42,6 +42,7 @@
         <module>event</module>
         <module>protocol</module>
         <module>proxy</module>
+        <module>query</module>
     </modules>
 
     <scm>

proxy/pom.xml

@@ -53,6 +53,12 @@
             <version>${project.version}</version>
             <scope>compile</scope>
         </dependency>
+        <dependency>
+            <groupId>net.md-5</groupId>
+            <artifactId>bungeecord-query</artifactId>
+            <version>${project.version}</version>
+            <scope>compile</scope>
+        </dependency>
         <dependency>
             <groupId>net.sf.trove4j</groupId>
             <artifactId>trove4j</artifactId>

proxy/src/main/java/net/md_5/bungee/BungeeCord.java

@@ -60,6 +60,7 @@ import net.md_5.bungee.protocol.packet.DefinedPacket;
 import net.md_5.bungee.protocol.packet.Packet3Chat;
 import net.md_5.bungee.protocol.packet.PacketFAPluginMessage;
 import net.md_5.bungee.protocol.Vanilla;
+import net.md_5.bungee.query.RemoteQuery;
 import net.md_5.bungee.tab.Custom;
 import net.md_5.bungee.util.CaseInsensitiveMap;
 import org.fusesource.jansi.AnsiConsole;
@@ -269,6 +270,26 @@ public class BungeeCord extends ProxyServer
                     .group( eventLoops )
                     .localAddress( info.getHost() )
                     .bind().addListener( listener );
+
+            if ( info.isQueryEnabled() )
+            {
+                ChannelFutureListener bindListener = new ChannelFutureListener()
+                {
+                    @Override
+                    public void operationComplete(ChannelFuture future) throws Exception
+                    {
+                        if ( future.isSuccess() )
+                        {
+                            listeners.add( future.channel() );
+                            getLogger().info( "Started query on " + future.channel().localAddress() );
+                        } else
+                        {
+                            getLogger().log( Level.WARNING, "Could not bind to host " + future.channel().remoteAddress(), future.cause() );
+                        }
+                    }
+                };
+                new RemoteQuery( this, info ).start( new InetSocketAddress( info.getHost().getAddress(), info.getQueryPort() ), eventLoops, bindListener );
+            }
         }
     }
 

proxy/src/main/java/net/md_5/bungee/config/YamlConfig.java

@@ -215,7 +215,10 @@ public class YamlConfig implements ConfigurationAdapter
             boolean setLocalAddress = get( "bind_local_address", true, val );
             boolean pingPassthrough = get( "ping_passthrough", false, val );
 
-            ListenerInfo info = new ListenerInfo( address, motd, maxPlayers, tabListSize, defaultServer, fallbackServer, forceDefault, forced, value.clazz, setLocalAddress, pingPassthrough );
+            boolean query = get( "guery_enabled", false, val );
+            int queryPort = get( "query_port", 25577, val );
+
+            ListenerInfo info = new ListenerInfo( address, motd, maxPlayers, tabListSize, defaultServer, fallbackServer, forceDefault, forced, value.clazz, setLocalAddress, pingPassthrough, queryPort, query );
             ret.add( info );
         }
 

query/nb-configuration.xml

@@ -0,0 +1,31 @@
+<?xml version="1.0" encoding="UTF-8"?>
+<project-shared-configuration>
+    <!--
+    This file contains additional configuration written by modules in the NetBeans IDE.
+    The configuration is intended to be shared among all the users of project and
+    therefore it is assumed to be part of version control checkout.
+    Without this configuration present, some functionality in the IDE may be limited or fail altogether.
+    -->
+    <properties xmlns="http://www.netbeans.org/ns/maven-properties-data/1">
+        <!--
+        Properties that influence various parts of the IDE, especially code formatting and the like. 
+        You can copy and paste the single properties, into the pom.xml file and the IDE will pick them up.
+        That way multiple projects can share the same settings (useful for formatting rules for example).
+        Any value defined here will override the pom.xml file value but is only applicable to the current project.
+        -->
+        <org-netbeans-modules-editor-indent.CodeStyle.usedProfile>project</org-netbeans-modules-editor-indent.CodeStyle.usedProfile>
+        <org-netbeans-modules-editor-indent.text.x-java.CodeStyle.project.classDeclBracePlacement>NEW_LINE</org-netbeans-modules-editor-indent.text.x-java.CodeStyle.project.classDeclBracePlacement>
+        <org-netbeans-modules-editor-indent.text.x-java.CodeStyle.project.otherBracePlacement>NEW_LINE</org-netbeans-modules-editor-indent.text.x-java.CodeStyle.project.otherBracePlacement>
+        <org-netbeans-modules-editor-indent.text.x-java.CodeStyle.project.methodDeclBracePlacement>NEW_LINE</org-netbeans-modules-editor-indent.text.x-java.CodeStyle.project.methodDeclBracePlacement>
+        <org-netbeans-modules-editor-indent.text.x-java.CodeStyle.project.spaceWithinMethodCallParens>true</org-netbeans-modules-editor-indent.text.x-java.CodeStyle.project.spaceWithinMethodCallParens>
+        <org-netbeans-modules-editor-indent.text.x-java.CodeStyle.project.spaceWithinSwitchParens>true</org-netbeans-modules-editor-indent.text.x-java.CodeStyle.project.spaceWithinSwitchParens>
+        <org-netbeans-modules-editor-indent.text.x-java.CodeStyle.project.spaceWithinCatchParens>true</org-netbeans-modules-editor-indent.text.x-java.CodeStyle.project.spaceWithinCatchParens>
+        <org-netbeans-modules-editor-indent.text.x-java.CodeStyle.project.spaceWithinTryParens>true</org-netbeans-modules-editor-indent.text.x-java.CodeStyle.project.spaceWithinTryParens>
+        <org-netbeans-modules-editor-indent.text.x-java.CodeStyle.project.spaceWithinSynchronizedParens>true</org-netbeans-modules-editor-indent.text.x-java.CodeStyle.project.spaceWithinSynchronizedParens>
+        <org-netbeans-modules-editor-indent.text.x-java.CodeStyle.project.spaceWithinArrayInitBrackets>true</org-netbeans-modules-editor-indent.text.x-java.CodeStyle.project.spaceWithinArrayInitBrackets>
+        <org-netbeans-modules-editor-indent.text.x-java.CodeStyle.project.spaceWithinParens>true</org-netbeans-modules-editor-indent.text.x-java.CodeStyle.project.spaceWithinParens>
+        <org-netbeans-modules-editor-indent.text.x-java.CodeStyle.project.spaceWithinWhileParens>true</org-netbeans-modules-editor-indent.text.x-java.CodeStyle.project.spaceWithinWhileParens>
+        <org-netbeans-modules-editor-indent.text.x-java.CodeStyle.project.spaceWithinIfParens>true</org-netbeans-modules-editor-indent.text.x-java.CodeStyle.project.spaceWithinIfParens>
+        <org-netbeans-modules-editor-indent.text.x-java.CodeStyle.project.spaceWithinForParens>true</org-netbeans-modules-editor-indent.text.x-java.CodeStyle.project.spaceWithinForParens>
+    </properties>
+</project-shared-configuration>

query/pom.xml

@@ -0,0 +1,35 @@
+
+<project xmlns="http://maven.apache.org/POM/4.0.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
+         xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">
+    <modelVersion>4.0.0</modelVersion>
+
+    <parent>
+        <groupId>net.md-5</groupId>
+        <artifactId>bungeecord-parent</artifactId>
+        <version>1.6.4-SNAPSHOT</version>
+        <relativePath>../pom.xml</relativePath>
+    </parent>
+
+    <groupId>net.md-5</groupId>
+    <artifactId>bungeecord-query</artifactId>
+    <version>1.6.4-SNAPSHOT</version>
+    <packaging>jar</packaging>
+
+    <name>BungeeCord-Query</name>
+    <description>Minecraft query implementation based on the BungeeCord API.</description>
+
+    <dependencies>
+        <dependency>
+            <groupId>io.netty</groupId>
+            <artifactId>netty-transport</artifactId>
+            <version>${netty.version}</version>
+            <scope>compile</scope>
+        </dependency>
+        <dependency>
+            <groupId>net.md-5</groupId>
+            <artifactId>bungeecord-api</artifactId>
+            <version>${project.version}</version>
+            <scope>compile</scope>
+        </dependency>
+    </dependencies>
+</project>

query/src/main/java/net/md_5/bungee/query/QueryHandler.java

@@ -0,0 +1,145 @@
+package net.md_5.bungee.query;
+
+import io.netty.buffer.ByteBuf;
+import io.netty.channel.AddressedEnvelope;
+import io.netty.channel.ChannelHandlerContext;
+import io.netty.channel.SimpleChannelInboundHandler;
+import io.netty.channel.socket.DatagramPacket;
+import java.nio.ByteOrder;
+import java.util.HashMap;
+import java.util.Map;
+import java.util.Random;
+import java.util.concurrent.TimeUnit;
+import lombok.RequiredArgsConstructor;
+import net.md_5.bungee.api.ProxyServer;
+import net.md_5.bungee.api.config.ListenerInfo;
+import net.md_5.bungee.api.connection.ProxiedPlayer;
+
+@RequiredArgsConstructor
+public class QueryHandler extends SimpleChannelInboundHandler<DatagramPacket>
+{
+
+    private final ProxyServer bungee;
+    private final ListenerInfo listener;
+    /*========================================================================*/
+    private final Random random = new Random();
+    private final Map<Integer, Long> sessions = new HashMap<>();
+
+    private void writeShort(ByteBuf buf, int s)
+    {
+        buf.order( ByteOrder.LITTLE_ENDIAN ).writeShort( s );
+    }
+
+    private void writeNumber(ByteBuf buf, int i)
+    {
+        writeString( buf, Integer.toString( i ) );
+    }
+
+    private void writeString(ByteBuf buf, String s)
+    {
+        for ( char c : s.toCharArray() )
+        {
+            buf.writeChar( c );
+        }
+        buf.writeByte( 0x00 );
+    }
+
+    @Override
+    public void channelActive(ChannelHandlerContext ctx) throws Exception
+    {
+        super.channelActive( ctx ); //To change body of generated methods, choose Tools | Templates.
+    }
+
+    @Override
+    protected void channelRead0(ChannelHandlerContext ctx, DatagramPacket msg) throws Exception
+    {
+        ByteBuf in = msg.content();
+        if ( in.readUnsignedByte() != 0xFE && in.readUnsignedByte() != 0xFD )
+        {
+            throw new IllegalStateException( "Incorrect magic!" );
+        }
+
+        ByteBuf out = ctx.alloc().buffer();
+        AddressedEnvelope response = new DatagramPacket( out, msg.sender() );
+
+        byte type = in.readByte();
+        int sessionId = in.readInt();
+
+        if ( type == 0x09 )
+        {
+            out.writeByte( 0x09 );
+            out.writeInt( sessionId );
+
+            int challengeToken = random.nextInt();
+            sessions.put( challengeToken, System.currentTimeMillis() );
+
+            writeNumber( out, challengeToken );
+        }
+
+        if ( type == 0x00 )
+        {
+            int challengeToken = out.readInt();
+            Long session = sessions.get( challengeToken );
+            if ( session == null || System.currentTimeMillis() - session > TimeUnit.SECONDS.toMillis( 30 ) )
+            {
+                throw new IllegalStateException( "No session!" );
+            }
+
+            out.writeByte( 0x00 );
+            out.writeInt( sessionId );
+
+            if ( in.readableBytes() == 0 )
+            {
+                // Short response
+                writeString( out, listener.getMotd() ); // MOTD
+                writeString( out, "SMP" ); // Game Type
+                writeString( out, "BungeeCord_Proxy" ); // World Name
+                writeNumber( out, bungee.getOnlineCount() ); // Online Count
+                writeNumber( out, listener.getMaxPlayers() ); // Max Players
+                writeShort( out, listener.getHost().getPort() ); // Port
+                writeString( out, listener.getHost().getHostString() ); // IP
+            } else if ( in.readableBytes() == 8 )
+            {
+                // Long Response
+                out.writeBytes( new byte[ 11 ] );
+                Map<String, String> data = new HashMap<>();
+
+                data.put( "hostname", listener.getMotd() );
+                data.put( "gametype", "SMP" );
+                // Start Extra Info
+                data.put( "game_id", "MINECRAFT" );
+                data.put( "version", bungee.getGameVersion() );
+                // data.put( "plugins","");
+                // End Extra Info
+                data.put( "map", "BungeeCord_Proxy" );
+                data.put( "numplayers", Integer.toString( bungee.getOnlineCount() ) );
+                data.put( "maxplayers", Integer.toString( listener.getMaxPlayers() ) );
+                data.put( "hostport", Integer.toString( listener.getHost().getPort() ) );
+                data.put( "hostip", listener.getHost().getHostString() );
+
+                for ( Map.Entry<String, String> entry : data.entrySet() )
+                {
+                    writeString( out, entry.getKey() );
+                    writeString( out, entry.getValue() );
+
+                }
+                out.writeByte( 0x00 ); // Null                
+
+                // Padding
+                out.writeBytes( new byte[ 10 ] );
+                // Player List
+                for ( ProxiedPlayer p : bungee.getPlayers() )
+                {
+                    writeString( out, p.getName() );
+                }
+                out.writeByte( 0x00 ); // Null
+            } else
+            {
+                // Error!
+                throw new IllegalStateException( "Invalid data request packet" );
+            }
+        }
+
+        ctx.writeAndFlush( response );
+    }
+}

query/src/main/java/net/md_5/bungee/query/RemoteQuery.java

@@ -0,0 +1,29 @@
+package net.md_5.bungee.query;
+
+import io.netty.bootstrap.Bootstrap;
+import io.netty.channel.ChannelFuture;
+import io.netty.channel.ChannelFutureListener;
+import io.netty.channel.EventLoopGroup;
+import io.netty.channel.socket.nio.NioDatagramChannel;
+import java.net.InetSocketAddress;
+import lombok.RequiredArgsConstructor;
+import net.md_5.bungee.api.ProxyServer;
+import net.md_5.bungee.api.config.ListenerInfo;
+
+@RequiredArgsConstructor
+public class RemoteQuery
+{
+
+    private final ProxyServer bungee;
+    private final ListenerInfo listener;
+
+    public void start(InetSocketAddress address, EventLoopGroup eventLoop, ChannelFutureListener future)
+    {
+        new Bootstrap()
+                .channel( NioDatagramChannel.class )
+                .group( eventLoop )
+                .handler( new QueryHandler( bungee, listener ) )
+                .localAddress( address )
+                .bind().addListener( future );
+    }
+}