fix: Fixed java.lang.IndexOutOfBoundsException on large payloads

Author: BirknerAlex

src/main/java/com/gportal/a2s/QueryClient.java

@@ -32,6 +32,8 @@ public QueryClient() {
 		Bootstrap bootstrap = new Bootstrap()
 			.group(worker)
 			.channel(NioDatagramChannel.class)
+			.option(io.netty.channel.ChannelOption.SO_RCVBUF, 65535)
+			.option(io.netty.channel.ChannelOption.RCVBUF_ALLOCATOR, new io.netty.channel.FixedRecvByteBufAllocator(65535))
 			.handler(new ChannelInitializer<NioDatagramChannel>() {
 				protected void initChannel(NioDatagramChannel ch) throws Exception {
 					ch.pipeline().addLast(

src/main/java/com/gportal/a2s/QueryServer.java

@@ -36,6 +36,8 @@ public QueryServer(InetSocketAddress address, ServerInfo info) {
 		Bootstrap bootstrap = new Bootstrap()
 			.group(worker)
 			.channel(NioDatagramChannel.class)
+			.option(io.netty.channel.ChannelOption.SO_RCVBUF, 65535)
+			.option(io.netty.channel.ChannelOption.RCVBUF_ALLOCATOR, new io.netty.channel.FixedRecvByteBufAllocator(65535))
 			.handler(new ChannelInitializer<NioDatagramChannel>() {
 				protected void initChannel(NioDatagramChannel ch) throws Exception {
 					ch.pipeline().addLast(

src/main/java/com/gportal/a2s/messages/PlayerQuery.java

@@ -12,8 +12,8 @@ public record PlayerQuery(InetSocketAddress remoteAddress, Integer challenge) im
 	public PlayerQuery withChallenge(int challenge) { return new PlayerQuery(remoteAddress(), challenge); }
 
 	public static PlayerQuery read(InetSocketAddress remoteAddress, ByteBuf buffer) {
-		Integer challenge = buffer.readIntLE();
-		if(challenge==0) challenge = null;
+		Integer challenge = buffer.readableBytes()>=4?buffer.readIntLE():null;
+		if(challenge!=null && challenge==0) challenge = null;
 		return new PlayerQuery(remoteAddress, challenge);
 	}
 	public PlayerQuery write(ByteBuf buffer) {

src/main/java/com/gportal/a2s/messages/PlayerReply.java

@@ -13,7 +13,7 @@ public record PlayerReply(InetSocketAddress remoteAddress, List<PlayerInfo> payl
 	public static final byte OP = 0x44;
 
 	public static PlayerReply read(InetSocketAddress remoteAddress, ByteBuf buffer) {
-		byte count = buffer.readByte();
+		int count = buffer.readUnsignedByte();
 		List<PlayerInfo> payload = new ArrayList<PlayerInfo>();
 		for(int i = 0; i < count; i++) {
 			payload.add(PlayerInfo.read(buffer));

src/main/java/com/gportal/a2s/messages/RulesQuery.java

@@ -12,8 +12,8 @@ public record RulesQuery(InetSocketAddress remoteAddress, Integer challenge) imp
 	public RulesQuery withChallenge(int challenge) { return new RulesQuery(remoteAddress(), challenge); }
 
 	public static RulesQuery read(InetSocketAddress remoteAddress, ByteBuf buffer) {
-		Integer challenge = buffer.readIntLE();
-		if(challenge==0) challenge = null;
+		Integer challenge = buffer.readableBytes()>=4?buffer.readIntLE():null;
+		if(challenge!=null && challenge==0) challenge = null;
 		return new RulesQuery(remoteAddress, challenge);
 	}
 	public RulesQuery write(ByteBuf buffer) {

src/main/java/com/gportal/a2s/messages/RulesReply.java

@@ -15,7 +15,7 @@ public record RulesReply(InetSocketAddress remoteAddress, Map<String, String> pa
 	public static final byte OP = 0x45;
 
 	public static RulesReply read(InetSocketAddress remoteAddress, ByteBuf buffer) {
-		short count = buffer.readShortLE();
+		int count = buffer.readUnsignedShortLE();
 		Map<String, String> payload = new HashMap<String, String>();
 		for(int i = 0; i < count; i++) {
 			payload.put(readString(buffer), readString(buffer));

src/test/java/LargePayloadETETest.java

@@ -0,0 +1,96 @@
+import java.net.InetAddress;
+import java.net.InetSocketAddress;
+import java.util.ArrayList;
+import java.util.List;
+import java.util.Map;
+import java.util.concurrent.TimeUnit;
+
+import com.gportal.a2s.PlayerInfo;
+import com.gportal.a2s.QueryClient;
+import com.gportal.a2s.QueryServer;
+import com.gportal.a2s.ServerInfo;
+
+import org.junit.jupiter.api.AfterAll;
+import org.junit.jupiter.api.BeforeAll;
+import org.junit.jupiter.api.Test;
+import static org.junit.jupiter.api.Assertions.*;
+
+public class LargePayloadETETest {
+	private static QueryClient client;
+	private static QueryServer server;
+	private static final int PORT = 27016;
+
+	@BeforeAll
+	public static void init() throws Exception {
+		client = new QueryClient();
+		
+		// Create a very long server name (2000 chars)
+		StringBuilder longName = new StringBuilder();
+		for (int i = 0; i < 2000; i++) {
+			longName.append("A");
+		}
+
+		ServerInfo info = new ServerInfo(
+			new InetSocketAddress(InetAddress.getLocalHost(), PORT),
+			(byte) 17,
+			longName.toString(),
+			"Map",
+			"Folder",
+			"Game",
+			(short) 0,
+			(byte) 0, // players - will be updated by server.players.size() if it was dynamic, but here it's static in ServerInfo
+			(byte) 255,
+			(byte) 0,
+			'd',
+			'l',
+			false,
+			true,
+			"1.0.0.0",
+			null, null, null, null, null, null
+		);
+
+		server = new QueryServer(new InetSocketAddress(InetAddress.getLocalHost(), PORT), info);
+
+		// Add 200 players to exceed typical MTU/buffer limits
+		for (int i = 0; i < 200; i++) {
+			server.players.add(new PlayerInfo((byte) i, "Player " + i, i * 10, 100.0f));
+		}
+		
+		// Update player count in info to reflect actual players
+		server.info.setPlayers((byte) 200);
+
+		// Add many rules
+		for (int i = 0; i < 200; i++) {
+			server.rules.put("RuleKey" + i, "RuleValue" + i);
+		}
+	}
+
+	@Test
+	public void testLargeInfoReply() throws Exception {
+		ServerInfo info = client.queryServer(new InetSocketAddress(InetAddress.getLocalHost(), PORT)).get(5, TimeUnit.SECONDS);
+		assertNotNull(info);
+		assertEquals(2000, info.name().length());
+	}
+
+	@Test
+	public void testLargePlayerReply() throws Exception {
+		List<PlayerInfo> players = client.queryPlayers(new InetSocketAddress(InetAddress.getLocalHost(), PORT)).get(5, TimeUnit.SECONDS);
+		assertNotNull(players);
+		assertEquals(200, players.size());
+		assertEquals("Player 199", players.get(199).name());
+	}
+
+	@Test
+	public void testLargeRulesReply() throws Exception {
+		Map<String, String> rules = client.queryRules(new InetSocketAddress(InetAddress.getLocalHost(), PORT)).get(5, TimeUnit.SECONDS);
+		assertNotNull(rules);
+		assertEquals(200, rules.size());
+		assertEquals("RuleValue199", rules.get("RuleKey199"));
+	}
+
+	@AfterAll
+	public static void cleanup() {
+		if (client != null) client.shutdown();
+		if (server != null) server.shutdown();
+	}
+}