From 728d695ce14174b0e4cdb116ba3d3f9260fae2cb Mon Sep 17 00:00:00 2001
From: Kusal Kithul-Godage <git@kusal.io>
Date: Wed, 17 Jan 2024 19:26:03 +1100
Subject: [PATCH] WW-5352 Add debug logging for parameter rejections

---
 .../parameter/ParametersInterceptor.java      | 25 ++++++++++++++++---
 1 file changed, 21 insertions(+), 4 deletions(-)

diff --git a/core/src/main/java/org/apache/struts2/interceptor/parameter/ParametersInterceptor.java b/core/src/main/java/org/apache/struts2/interceptor/parameter/ParametersInterceptor.java
index c91aea87a..9c7013b7c 100644
--- a/core/src/main/java/org/apache/struts2/interceptor/parameter/ParametersInterceptor.java
+++ b/core/src/main/java/org/apache/struts2/interceptor/parameter/ParametersInterceptor.java
@@ -399,8 +399,11 @@ public class ParametersInterceptor extends MethodFilterInterceptor {
         if (relevantMethod == null) {
             return false;
         }
-        StrutsParameter annotation = getParameterAnnotation(relevantMethod);
-        if (annotation == null || annotation.depth() < paramDepth) {
+        if (getPermittedInjectionDepth(relevantMethod) < paramDepth) {
+            LOG.debug(
+                    "Parameter injection for method [{}] on action [{}] rejected. Ensure it is annotated with @StrutsParameter with an appropriate 'depth'.",
+                    relevantMethod.getName(),
+                    relevantMethod.getDeclaringClass().getName());
             return false;
         }
         if (paramDepth >= 1) {
@@ -450,8 +453,11 @@ public class ParametersInterceptor extends MethodFilterInterceptor {
         if (!Modifier.isPublic(field.getModifiers())) {
             return false;
         }
-        StrutsParameter annotation = getParameterAnnotation(field);
-        if (annotation == null || annotation.depth() < paramDepth) {
+        if (getPermittedInjectionDepth(field) < paramDepth) {
+            LOG.debug(
+                    "Parameter injection for field [{}] on action [{}] rejected. Ensure it is annotated with @StrutsParameter with an appropriate 'depth'.",
+                    fieldName,
+                    action.getClass().getName());
             return false;
         }
         if (paramDepth >= 1) {
@@ -467,6 +473,17 @@ public class ParametersInterceptor extends MethodFilterInterceptor {
         allowlistParameterizedTypeArg(field.getGenericType());
     }
 
+    /**
+     * @return permitted injection depth where -1 indicates not permitted
+     */
+    protected int getPermittedInjectionDepth(AnnotatedElement element) {
+        StrutsParameter annotation = getParameterAnnotation(element);
+        if (annotation == null) {
+            return -1;
+        }
+        return annotation.depth();
+    }
+
     /**
      * Annotation retrieval logic. Can be overridden to support extending annotations or some other form of annotation
      * inheritance.