From 3e9b8c2cbb0212159b3fdd01859adb26a9503d52 Mon Sep 17 00:00:00 2001
From: Bin Wu <46450037+wu-bin@users.noreply.github.com>
Date: Thu, 1 Aug 2024 11:30:25 -0400
Subject: [PATCH] Ensure every instance of StreamFilter and PassThroughFilter
 to contain only one copy of StreamFilterBase. (#35341)

Change Stream(Decode|Encode)Filter to inherit from StreamFilterBase
virtually.
Move the default implementation of
PassThrough(Decoder|Encode)Filter::onDestroy into StreamFilterBase.

---------

Signed-off-by: Bin Wu <wub@google.com>
Signed-off-by: asingh-g <abhisinghx@google.com>
---
 envoy/http/filter.h                                         | 4 ++--
 source/extensions/filters/http/common/pass_through_filter.h | 6 +++++-
 2 files changed, 7 insertions(+), 3 deletions(-)

diff --git a/envoy/http/filter.h b/envoy/http/filter.h
index 1caebab6a46c..49d2609a1152 100644
--- a/envoy/http/filter.h
+++ b/envoy/http/filter.h
@@ -896,7 +896,7 @@ class StreamFilterBase {
 /**
  * Stream decoder filter interface.
  */
-class StreamDecoderFilter : public StreamFilterBase {
+class StreamDecoderFilter : public virtual StreamFilterBase {
 public:
   /**
    * Called with decoded headers, optionally indicating end of stream.
@@ -1112,7 +1112,7 @@ class StreamEncoderFilterCallbacks : public virtual StreamFilterCallbacks {
 /**
  * Stream encoder filter interface.
  */
-class StreamEncoderFilter : public StreamFilterBase {
+class StreamEncoderFilter : public virtual StreamFilterBase {
 public:
   /**
    * Called with supported 1xx headers.
diff --git a/source/extensions/filters/http/common/pass_through_filter.h b/source/extensions/filters/http/common/pass_through_filter.h
index ad299e47da15..e6291b9e3dd1 100644
--- a/source/extensions/filters/http/common/pass_through_filter.h
+++ b/source/extensions/filters/http/common/pass_through_filter.h
@@ -62,6 +62,10 @@ class PassThroughEncoderFilter : public virtual StreamEncoderFilter {
 // A filter which passes all data through with Continue status.
 class PassThroughFilter : public StreamFilter,
                           public PassThroughDecoderFilter,
-                          public PassThroughEncoderFilter {};
+                          public PassThroughEncoderFilter {
+public:
+  // Http::StreamFilterBase
+  void onDestroy() override {}
+};
 } // namespace Http
 } // namespace Envoy