From 44bc15db409226d39ca0330ac01bb1295da34424 Mon Sep 17 00:00:00 2001
From: Shane Freeder <theboyetronic@gmail.com>
Date: Sat, 14 Jun 2025 20:29:12 +0100
Subject: [PATCH] Add system property to skip packet compression threshold
 validation

---
 .../proxy/protocol/netty/MinecraftCompressDecoder.java   | 9 ++++++---
 1 file changed, 6 insertions(+), 3 deletions(-)

diff --git a/proxy/src/main/java/com/velocitypowered/proxy/protocol/netty/MinecraftCompressDecoder.java b/proxy/src/main/java/com/velocitypowered/proxy/protocol/netty/MinecraftCompressDecoder.java
index 5321b6ac..1fe38e50 100644
--- a/proxy/src/main/java/com/velocitypowered/proxy/protocol/netty/MinecraftCompressDecoder.java
+++ b/proxy/src/main/java/com/velocitypowered/proxy/protocol/netty/MinecraftCompressDecoder.java
@@ -39,6 +39,7 @@ public class MinecraftCompressDecoder extends MessageToMessageDecoder<ByteBuf> {
   private static final int UNCOMPRESSED_CAP =
       Boolean.getBoolean("velocity.increased-compression-cap")
           ? HARD_MAXIMUM_UNCOMPRESSED_SIZE : VANILLA_MAXIMUM_UNCOMPRESSED_SIZE;
+  private static final boolean SKIP_COMPRESSION_VALIDATION = Boolean.getBoolean("velocity.skip-uncompressed-packet-size-validation");
 
   private int threshold;
   private final VelocityCompressor compressor;
@@ -52,9 +53,11 @@ public class MinecraftCompressDecoder extends MessageToMessageDecoder<ByteBuf> {
   protected void decode(ChannelHandlerContext ctx, ByteBuf in, List<Object> out) throws Exception {
     int claimedUncompressedSize = ProtocolUtils.readVarInt(in);
     if (claimedUncompressedSize == 0) {
-      int actualUncompressedSize = in.readableBytes();
-      checkFrame(actualUncompressedSize < threshold, "Actual uncompressed size %s is greater than"
-              + " threshold %s", actualUncompressedSize, threshold);
+      if (!SKIP_COMPRESSION_VALIDATION) {
+        int actualUncompressedSize = in.readableBytes();
+        checkFrame(actualUncompressedSize < threshold, "Actual uncompressed size %s is greater than"
+            + " threshold %s", actualUncompressedSize, threshold);
+      }
       // This message is not compressed.
       out.add(in.retain());
       return;