189 Zeilen
7.6 KiB
Diff
189 Zeilen
7.6 KiB
Diff
From 0000000000000000000000000000000000000000 Mon Sep 17 00:00:00 2001
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From: Minecrell <minecrell@minecrell.net>
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Date: Wed, 11 Oct 2017 18:22:50 +0200
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Subject: [PATCH] Make legacy ping handler more reliable
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The Minecraft server often fails to respond to old ("legacy") pings
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from old Minecraft versions using the protocol used before the switch
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to Netty in Minecraft 1.7.
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Due to packet fragmentation[1], we might not have all needed bytes
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available when the LegacyPingHandler is called. In this case, it will
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run into an error, remove the handler and continue using the modern
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protocol.
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This is unlikely to happen for the first two revisions of the legacy
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ping protocol (used in Minecraft 1.5.x and older) since the request
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consists of only one or two bytes, but happens frequently for the
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last/third revision introduced in Minecraft 1.6.
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It has much larger, variable packet sizes due to the inclusion of
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the virtual host (the hostname/port used to connect to the server).
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The solution[2] is simple: If we find more than two matching bytes,
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we buffer the remaining bytes until we have enough to fully read and
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respond to the request.
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[1]: https://netty.io/wiki/user-guide-for-4.x.html#wiki-h3-11
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[2]: https://netty.io/wiki/user-guide-for-4.x.html#wiki-h4-13
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diff --git a/src/main/java/net/minecraft/server/network/LegacyQueryHandler.java b/src/main/java/net/minecraft/server/network/LegacyQueryHandler.java
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index 33e3a81f8ec18f0ba7170d885c4717640bf40eab..738da83f82bf01bde94c956ac22525a638db3906 100644
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--- a/src/main/java/net/minecraft/server/network/LegacyQueryHandler.java
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+++ b/src/main/java/net/minecraft/server/network/LegacyQueryHandler.java
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@@ -15,6 +15,7 @@ public class LegacyQueryHandler extends ChannelInboundHandlerAdapter {
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private static final Logger LOGGER = LogUtils.getLogger();
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private final ServerInfo server;
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+ private ByteBuf buf; // Paper
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public LegacyQueryHandler(ServerInfo server) {
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this.server = server;
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@@ -23,6 +24,16 @@ public class LegacyQueryHandler extends ChannelInboundHandlerAdapter {
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public void channelRead(ChannelHandlerContext channelhandlercontext, Object object) {
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ByteBuf bytebuf = (ByteBuf) object;
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+ // Paper start - Make legacy ping handler more reliable
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+ if (this.buf != null) {
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+ try {
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+ readLegacy1_6(channelhandlercontext, bytebuf);
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+ } finally {
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+ bytebuf.release();
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+ }
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+ return;
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+ }
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+ // Paper end
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bytebuf.markReaderIndex();
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boolean flag = true;
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@@ -34,7 +45,7 @@ public class LegacyQueryHandler extends ChannelInboundHandlerAdapter {
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SocketAddress socketaddress = channelhandlercontext.channel().remoteAddress();
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int i = bytebuf.readableBytes();
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- String s;
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+ String s = null; // Paper
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org.bukkit.event.server.ServerListPingEvent event = org.bukkit.craftbukkit.event.CraftEventFactory.callServerListPingEvent(socketaddress, this.server.getMotd(), this.server.getPlayerCount(), this.server.getMaxPlayers()); // CraftBukkit
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if (i == 0) {
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@@ -47,16 +58,24 @@ public class LegacyQueryHandler extends ChannelInboundHandlerAdapter {
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}
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if (bytebuf.isReadable()) {
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- if (!LegacyQueryHandler.readCustomPayloadPacket(bytebuf)) {
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- return;
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+ // Paper start - Replace with improved version below
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+ if (bytebuf.readUnsignedByte() != 250) {
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+ s = this.readLegacy1_6(channelhandlercontext, bytebuf);
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+ if (s == null) {
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+ return;
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+ }
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}
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-
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- LegacyQueryHandler.LOGGER.debug("Ping: (1.6) from {}", socketaddress);
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+ // if (!LegacyQueryHandler.readCustomPayloadPacket(bytebuf)) {
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+ // return;
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+ // }
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+ //
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+ // LegacyQueryHandler.LOGGER.debug("Ping: (1.6) from {}", socketaddress);
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+ // Paper end
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} else {
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LegacyQueryHandler.LOGGER.debug("Ping: (1.4-1.5.x) from {}", socketaddress);
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}
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- s = LegacyQueryHandler.createVersion1Response(this.server, event); // CraftBukkit
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+ if (s == null) s = LegacyQueryHandler.createVersion1Response(this.server, event); // CraftBukkit // Paper
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LegacyQueryHandler.sendFlushAndClose(channelhandlercontext, LegacyQueryHandler.createLegacyDisconnectPacket(channelhandlercontext.alloc(), s));
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}
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@@ -107,6 +126,90 @@ public class LegacyQueryHandler extends ChannelInboundHandlerAdapter {
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}
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}
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+ // Paper start
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+ private static String readLegacyString(ByteBuf buf) {
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+ int size = buf.readShort() * Character.BYTES;
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+ if (!buf.isReadable(size)) {
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+ return null;
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+ }
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+
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+ String result = buf.toString(buf.readerIndex(), size, java.nio.charset.StandardCharsets.UTF_16BE);
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+ buf.skipBytes(size); // toString doesn't increase readerIndex automatically
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+ return result;
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+ }
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+
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+ private String readLegacy1_6(ChannelHandlerContext ctx, ByteBuf part) {
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+ ByteBuf buf = this.buf;
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+
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+ if (buf == null) {
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+ this.buf = buf = ctx.alloc().buffer();
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+ buf.markReaderIndex();
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+ } else {
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+ buf.resetReaderIndex();
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+ }
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+
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+ buf.writeBytes(part);
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+
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+ if (!buf.isReadable(Short.BYTES + Short.BYTES + Byte.BYTES + Short.BYTES + Integer.BYTES)) {
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+ return null;
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+ }
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+
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+ String s = readLegacyString(buf);
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+ if (s == null) {
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+ return null;
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+ }
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+
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+ if (!s.equals("MC|PingHost")) {
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+ removeHandler(ctx);
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+ return null;
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+ }
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+
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+ if (!buf.isReadable(Short.BYTES) || !buf.isReadable(buf.readShort())) {
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+ return null;
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+ }
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+
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+ net.minecraft.server.MinecraftServer server = net.minecraft.server.MinecraftServer.getServer();
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+ int protocolVersion = buf.readByte();
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+ String host = readLegacyString(buf);
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+ if (host == null) {
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+ removeHandler(ctx);
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+ return null;
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+ }
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+ int port = buf.readInt();
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+
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+ if (buf.isReadable()) {
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+ removeHandler(ctx);
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+ return null;
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+ }
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+
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+ buf.release();
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+ this.buf = null;
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+
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+ LOGGER.debug("Ping: (1.6) from {}", ctx.channel().remoteAddress());
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+
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+ String response = String.format("\u00a71\u0000%d\u0000%s\u0000%s\u0000%d\u0000%d",
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+ Byte.MAX_VALUE, server.getServerVersion(), server.getMotd(), server.getPlayerCount(), server.getMaxPlayers());
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+ return response;
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+ }
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+
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+ private void removeHandler(ChannelHandlerContext ctx) {
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+ ByteBuf buf = this.buf;
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+ this.buf = null;
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+
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+ buf.resetReaderIndex();
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+ ctx.pipeline().remove(this);
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+ ctx.fireChannelRead(buf);
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+ }
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+
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+ @Override
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+ public void handlerRemoved(ChannelHandlerContext ctx) {
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+ if (this.buf != null) {
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+ this.buf.release();
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+ this.buf = null;
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+ }
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+ }
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+ // Paper end
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+
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// CraftBukkit start
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private static String createVersion0Response(ServerInfo serverinfo, org.bukkit.event.server.ServerListPingEvent event) {
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return String.format(Locale.ROOT, "%s\u00a7%d\u00a7%d", event.getMotd(), event.getNumPlayers(), event.getMaxPlayers());
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