mirror of
https://github.com/PaperMC/Waterfall.git
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5d64a21724
Upstream has released updates that appears to apply and compile correctly. This update has not been tested by PaperMC and as with ANY update, please do your own testing BungeeCord Changes: c96628b7 #3094: Fix TO_CLIENT max Chat string length e5ded9a2 Apply stricter length limits to client strings
246 lines
12 KiB
Diff
246 lines
12 KiB
Diff
From 27dd755c7d2ca99b302ae28b61a9e4a00823130e Mon Sep 17 00:00:00 2001
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From: "Five (Xer)" <admin@fivepb.me>
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Date: Sat, 30 Jan 2021 18:04:14 +0100
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Subject: [PATCH] Additional DoS mitigations
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Some stricter length checks and cached exceptions to withstand more illegitimate connections
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Courtesy of Tux and the Velocity Contributors. See:
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https://github.com/VelocityPowered/Velocity/commit/5ceac16a821ea35572ff11412ace8929fd06e278
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diff --git a/protocol/src/main/java/net/md_5/bungee/protocol/DefinedPacket.java b/protocol/src/main/java/net/md_5/bungee/protocol/DefinedPacket.java
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index d10cf2ed..31a95495 100644
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--- a/protocol/src/main/java/net/md_5/bungee/protocol/DefinedPacket.java
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+++ b/protocol/src/main/java/net/md_5/bungee/protocol/DefinedPacket.java
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@@ -44,6 +44,7 @@ public abstract class DefinedPacket
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int len = readVarInt( buf );
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if ( len > maxLen * 4 )
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{
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+ if(!MinecraftDecoder.DEBUG) throw STRING_TOO_MANY_BYTES_EXCEPTION; // Waterfall start: Additional DoS mitigations
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throw new OverflowPacketException( String.format( "Cannot receive string longer than %d (got %d bytes)", maxLen * 4, len ) );
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}
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@@ -53,6 +54,7 @@ public abstract class DefinedPacket
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String s = new String( b, Charsets.UTF_8 );
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if ( s.length() > maxLen )
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{
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+ if(!MinecraftDecoder.DEBUG) throw STRING_TOO_LONG_EXCEPTION; // Waterfall start: Additional DoS mitigations
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throw new OverflowPacketException( String.format( "Cannot receive string longer than %d (got %d characters)", maxLen, s.length() ) );
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}
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@@ -284,4 +286,21 @@ public abstract class DefinedPacket
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@Override
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public abstract String toString();
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+
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+ // Waterfall start: Additional DoS mitigations, courtesy of Velocity
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+ private static final OverflowPacketException STRING_TOO_LONG_EXCEPTION
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+ = new OverflowPacketException("A string was longer than allowed. For more "
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+ + "information, launch Waterfall with -Dwaterfall.packet-decode-logging=true");
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+ private static final OverflowPacketException STRING_TOO_MANY_BYTES_EXCEPTION
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+ = new OverflowPacketException("A string had more data than allowed. For more "
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+ + "information, launch Waterfall with -Dwaterfall.packet-decode-logging=true");
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+
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+ public int expectedMaxLength(ByteBuf buf, ProtocolConstants.Direction direction, int protocolVersion) {
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+ return -1;
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+ }
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+
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+ public int expectedMinLength(ByteBuf buf, ProtocolConstants.Direction direction, int protocolVersion) {
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+ return 0;
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+ }
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+ // Waterfall end
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}
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diff --git a/protocol/src/main/java/net/md_5/bungee/protocol/MinecraftDecoder.java b/protocol/src/main/java/net/md_5/bungee/protocol/MinecraftDecoder.java
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index 37d28c01..01d35f41 100644
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--- a/protocol/src/main/java/net/md_5/bungee/protocol/MinecraftDecoder.java
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+++ b/protocol/src/main/java/net/md_5/bungee/protocol/MinecraftDecoder.java
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@@ -3,7 +3,7 @@ package net.md_5.bungee.protocol;
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import io.netty.buffer.ByteBuf;
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import io.netty.buffer.ByteBufUtil;
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import io.netty.channel.ChannelHandlerContext;
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-import io.netty.handler.codec.DecoderException;
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+import io.netty.handler.codec.CorruptedFrameException;
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import io.netty.handler.codec.MessageToMessageDecoder;
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import java.util.List;
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import lombok.AllArgsConstructor;
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@@ -56,10 +56,16 @@ public class MinecraftDecoder extends MessageToMessageDecoder<ByteBuf>
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if ( packet != null )
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{
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packetTypeInfo = packet.getClass();
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+ doLengthSanityChecks(in, packet, prot.getDirection(), packetId); // Waterfall: Additional DoS mitigations
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packet.read( in, prot.getDirection(), protocolVersion );
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if ( in.isReadable() )
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{
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+ // Waterfall start: Additional DoS mitigations
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+ if(!DEBUG) {
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+ throw PACKET_NOT_READ_TO_END;
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+ }
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+ // Waterfall end
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throw new BadPacketException( "Did not read all bytes from packet " + packet.getClass() + " " + packetId + " Protocol " + protocol + " Direction " + prot.getDirection() );
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}
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} else
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@@ -70,6 +76,11 @@ public class MinecraftDecoder extends MessageToMessageDecoder<ByteBuf>
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out.add( new PacketWrapper( packet, slice ) );
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slice = null;
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} catch (BadPacketException | IndexOutOfBoundsException e) {
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+ // Waterfall start: Additional DoS mitigations
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+ if(!DEBUG) {
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+ throw e;
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+ }
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+ // Waterfall end
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final String packetTypeStr;
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if (packetTypeInfo instanceof Integer) {
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packetTypeStr = "id " + Integer.toHexString((Integer) packetTypeInfo);
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@@ -87,4 +98,52 @@ public class MinecraftDecoder extends MessageToMessageDecoder<ByteBuf>
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}
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}
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}
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+
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+ // Waterfall start: Additional DoS mitigations, courtesy of Velocity
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+ public static final boolean DEBUG = Boolean.getBoolean("waterfall.packet-decode-logging");
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+
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+ // Cached Exceptions:
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+ private static final CorruptedFrameException PACKET_LENGTH_OVERSIZED =
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+ new CorruptedFrameException("A packet could not be decoded because it was too large. For more "
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+ + "information, launch Waterfall with -Dwaterfall.packet-decode-logging=true");
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+ private static final CorruptedFrameException PACKET_LENGTH_UNDERSIZED =
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+ new CorruptedFrameException("A packet could not be decoded because it was smaller than allowed. For more "
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+ + "information, launch Waterfall with -Dwaterfall.packet-decode-logging=true");
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+ private static final BadPacketException PACKET_NOT_READ_TO_END =
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+ new BadPacketException("Couldn't read all bytes from a packet. For more "
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+ + "information, launch Waterfall with -Dwaterfall.packet-decode-logging=true");
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+
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+
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+ private void doLengthSanityChecks(ByteBuf buf, DefinedPacket packet,
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+ ProtocolConstants.Direction direction, int packetId) throws Exception {
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+ int expectedMinLen = packet.expectedMinLength(buf, direction, protocolVersion);
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+ int expectedMaxLen = packet.expectedMaxLength(buf, direction, protocolVersion);
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+ if (expectedMaxLen != -1 && buf.readableBytes() > expectedMaxLen) {
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+ throw handleOverflow(packet, expectedMaxLen, buf.readableBytes(), packetId);
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+ }
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+ if (buf.readableBytes() < expectedMinLen) {
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+ throw handleUnderflow(packet, expectedMaxLen, buf.readableBytes(), packetId);
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+ }
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+ }
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+
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+ private Exception handleOverflow(DefinedPacket packet, int expected, int actual, int packetId) {
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+ if (DEBUG) {
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+ throw new CorruptedFrameException( "Packet " + packet.getClass() + " " + packetId
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+ + " Protocol " + protocolVersion + " was too big (expected "
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+ + expected + " bytes, got " + actual + " bytes)");
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+ } else {
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+ return PACKET_LENGTH_OVERSIZED;
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+ }
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+ }
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+
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+ private Exception handleUnderflow(DefinedPacket packet, int expected, int actual, int packetId) {
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+ if (DEBUG) {
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+ throw new CorruptedFrameException( "Packet " + packet.getClass() + " " + packetId
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+ + " Protocol " + protocolVersion + " was too small (expected "
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+ + expected + " bytes, got " + actual + " bytes)");
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+ } else {
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+ return PACKET_LENGTH_UNDERSIZED;
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+ }
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+ }
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+ // Waterfall end
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}
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diff --git a/protocol/src/main/java/net/md_5/bungee/protocol/packet/EncryptionResponse.java b/protocol/src/main/java/net/md_5/bungee/protocol/packet/EncryptionResponse.java
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index 388f6cdb..53575ce0 100644
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--- a/protocol/src/main/java/net/md_5/bungee/protocol/packet/EncryptionResponse.java
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+++ b/protocol/src/main/java/net/md_5/bungee/protocol/packet/EncryptionResponse.java
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@@ -38,4 +38,16 @@ public class EncryptionResponse extends DefinedPacket
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{
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handler.handle( this );
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}
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+
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+ // Waterfall start: Additional DoS mitigations, courtesy of Velocity
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+ public int expectedMaxLength(ByteBuf buf, ProtocolConstants.Direction direction, int protocolVersion) {
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+ // It turns out these come out to the same length, whether we're talking >=1.8 or not.
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+ // The length prefix always winds up being 2 bytes.
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+ return 260;
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+ }
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+
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+ public int expectedMinLength(ByteBuf buf, ProtocolConstants.Direction direction, int protocolVersion) {
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+ return expectedMaxLength(buf, direction, protocolVersion);
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+ }
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+ // Waterfall end
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}
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diff --git a/protocol/src/main/java/net/md_5/bungee/protocol/packet/LoginRequest.java b/protocol/src/main/java/net/md_5/bungee/protocol/packet/LoginRequest.java
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index 08ee376e..cfd8e64e 100644
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--- a/protocol/src/main/java/net/md_5/bungee/protocol/packet/LoginRequest.java
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+++ b/protocol/src/main/java/net/md_5/bungee/protocol/packet/LoginRequest.java
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@@ -7,6 +7,7 @@ import lombok.EqualsAndHashCode;
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import lombok.NoArgsConstructor;
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import net.md_5.bungee.protocol.AbstractPacketHandler;
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import net.md_5.bungee.protocol.DefinedPacket;
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+import net.md_5.bungee.protocol.ProtocolConstants;
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@Data
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@NoArgsConstructor
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@@ -34,4 +35,12 @@ public class LoginRequest extends DefinedPacket
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{
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handler.handle( this );
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}
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+
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+ // Waterfall start: Additional DoS mitigations, courtesy of Velocity
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+ public int expectedMaxLength(ByteBuf buf, ProtocolConstants.Direction direction, int protocolVersion) {
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+ // Accommodate the rare (but likely malicious) use of UTF-8 usernames, since it is technically
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+ // legal on the protocol level.
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+ return 1 + (16 * 4);
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+ }
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+ // Waterfall end
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}
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diff --git a/protocol/src/main/java/net/md_5/bungee/protocol/packet/PingPacket.java b/protocol/src/main/java/net/md_5/bungee/protocol/packet/PingPacket.java
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index 5f24d425..3163a771 100644
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--- a/protocol/src/main/java/net/md_5/bungee/protocol/packet/PingPacket.java
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+++ b/protocol/src/main/java/net/md_5/bungee/protocol/packet/PingPacket.java
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@@ -7,6 +7,7 @@ import lombok.EqualsAndHashCode;
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import lombok.NoArgsConstructor;
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import net.md_5.bungee.protocol.AbstractPacketHandler;
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import net.md_5.bungee.protocol.DefinedPacket;
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+import net.md_5.bungee.protocol.ProtocolConstants;
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@Data
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@NoArgsConstructor
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@@ -34,4 +35,14 @@ public class PingPacket extends DefinedPacket
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{
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handler.handle( this );
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}
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+
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+ // Waterfall start: Additional DoS mitigations, courtesy of Velocity
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+ public int expectedMaxLength(ByteBuf buf, ProtocolConstants.Direction direction, int protocolVersion) {
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+ return 8;
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+ }
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+
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+ public int expectedMinLength(ByteBuf buf, ProtocolConstants.Direction direction, int protocolVersion) {
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+ return 8;
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+ }
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+ // Waterfall end
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}
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diff --git a/protocol/src/main/java/net/md_5/bungee/protocol/packet/StatusRequest.java b/protocol/src/main/java/net/md_5/bungee/protocol/packet/StatusRequest.java
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index 738f0c92..ec33d337 100644
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--- a/protocol/src/main/java/net/md_5/bungee/protocol/packet/StatusRequest.java
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+++ b/protocol/src/main/java/net/md_5/bungee/protocol/packet/StatusRequest.java
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@@ -6,6 +6,7 @@ import lombok.EqualsAndHashCode;
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import lombok.NoArgsConstructor;
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import net.md_5.bungee.protocol.AbstractPacketHandler;
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import net.md_5.bungee.protocol.DefinedPacket;
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+import net.md_5.bungee.protocol.ProtocolConstants;
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@Data
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@NoArgsConstructor
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@@ -28,4 +29,10 @@ public class StatusRequest extends DefinedPacket
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{
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handler.handle( this );
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}
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+
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+ // Waterfall start: Additional DoS mitigations, courtesy of Velocity
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+ public int expectedMaxLength(ByteBuf buf, ProtocolConstants.Direction direction, int protocolVersion) {
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+ return 0;
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+ }
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+ // Waterfall end
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}
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--
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2.31.1
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