Work around HTTP/2 decompression padding issue.

vietj · vietj · commit cdca04b1b1bc · 2026-02-12T09:24:54.000+01:00
Motivation:

It seems that Netty HTTP/2 decompression accounts for padding twice, failing the decompression of a response when padding is not zero.

Changes:

When processing a compressed entity, set padding to zero and refund the padding to the original flow controller immediately.
diff --git a/vertx-core/src/main/java/io/vertx/core/http/impl/VertxHttp2ConnectionHandler.java b/vertx-core/src/main/java/io/vertx/core/http/impl/VertxHttp2ConnectionHandler.java
@@ -45,6 +45,7 @@ class VertxHttp2ConnectionHandler<C extends Http2ConnectionBase> extends Http2Co
   private final boolean useDecompressor;
   private final Http2Settings initialSettings;
   public boolean upgraded;
+  private final Http2LocalFlowController defaultController;
 
   public VertxHttp2ConnectionHandler(
       Function<VertxHttp2ConnectionHandler<C>, C> connectionFactory,
@@ -53,6 +54,7 @@ public VertxHttp2ConnectionHandler(
       Http2ConnectionEncoder encoder,
       Http2Settings initialSettings) {
     super(decoder, encoder, initialSettings);
+    this.defaultController = decoder.flowController();
     this.connectionFactory = connectionFactory;
     this.useDecompressor = useDecompressor;
     this.initialSettings = initialSettings;
@@ -386,7 +388,19 @@ public void onSettingsAckRead(ChannelHandlerContext ctx) throws Http2Exception {
   @Override
   public void onSettingsRead(ChannelHandlerContext ctx, Http2Settings settings) throws Http2Exception {
     if (useDecompressor) {
-      decoder().frameListener(new DelegatingDecompressorFrameListener(decoder().connection(), connection));
+      decoder().frameListener(new DelegatingDecompressorFrameListener(decoder().connection(), connection) {
+        @Override
+        public int onDataRead(ChannelHandlerContext ctx, int streamId, ByteBuf data, int padding, boolean endOfStream) throws Http2Exception {
+          // Work around padded decompression
+          // this should be removed when response decompression is fixed
+          if (padding > 0) {
+            VertxHttp2Stream<?> stream = connection.stream(streamId);
+            defaultController.consumeBytes(stream.stream, padding);
+            padding = 0;
+          }
+          return super.onDataRead(ctx, streamId, data, padding, endOfStream);
+        }
+      });
     } else {
       decoder().frameListener(connection);
     }
