From 5e5011e98dd7e2f18d4d799be5b7a8adfbdccd02 Mon Sep 17 00:00:00 2001
From: Mark Junker <m.junker@fubar-dev.de>
Date: Mon, 22 Nov 2021 09:42:11 +0100
Subject: [PATCH] New attribute WebDavAnyExceptionFilterAttribute

Ensures that - in the sample server - all exceptions are returned as multi-status responses.

Incorporates the changes from #38. Maybe we need to return the error element too?
---
 .../Controllers/WebDavController.cs           |  2 ++
 .../WebDavAnyExceptionFilterAttribute.cs      | 35 +++++++++++++++++++
 .../Filters/WebDavExceptionFilterAttribute.cs | 18 ++++++----
 .../Model/WebDavStatusCode.cs                 |  5 +++
 4 files changed, 54 insertions(+), 6 deletions(-)
 create mode 100644 src/FubarDev.WebDavServer.AspNetCore/Filters/WebDavAnyExceptionFilterAttribute.cs

diff --git a/sample/FubarDev.WebDavServer.Sample.AspNetCore/Controllers/WebDavController.cs b/sample/FubarDev.WebDavServer.Sample.AspNetCore/Controllers/WebDavController.cs
index 7882caba..bc11ae3a 100644
--- a/sample/FubarDev.WebDavServer.Sample.AspNetCore/Controllers/WebDavController.cs
+++ b/sample/FubarDev.WebDavServer.Sample.AspNetCore/Controllers/WebDavController.cs
@@ -1,4 +1,5 @@
 using FubarDev.WebDavServer.AspNetCore;
+using FubarDev.WebDavServer.AspNetCore.Filters;
 
 using Microsoft.AspNetCore.Authorization;
 using Microsoft.AspNetCore.Mvc;
@@ -8,6 +9,7 @@ namespace FubarDev.WebDavServer.Sample.AspNetCore.Controllers
 {
     [Route("_dav/{*path}")]
     [Authorize]
+    [WebDavAnyExceptionFilter]
     public class WebDavController : WebDavControllerBase
     {
         public WebDavController(
diff --git a/src/FubarDev.WebDavServer.AspNetCore/Filters/WebDavAnyExceptionFilterAttribute.cs b/src/FubarDev.WebDavServer.AspNetCore/Filters/WebDavAnyExceptionFilterAttribute.cs
new file mode 100644
index 00000000..c087cc5c
--- /dev/null
+++ b/src/FubarDev.WebDavServer.AspNetCore/Filters/WebDavAnyExceptionFilterAttribute.cs
@@ -0,0 +1,35 @@
+// <copyright file="WebDavAnyExceptionFilterAttribute.cs" company="Fubar Development Junker">
+// Copyright (c) Fubar Development Junker. All rights reserved.
+// </copyright>
+
+using System.Threading.Tasks;
+
+using FubarDev.WebDavServer.Model;
+
+using Microsoft.AspNetCore.Mvc.Filters;
+
+namespace FubarDev.WebDavServer.AspNetCore.Filters
+{
+    /// <summary>
+    /// Attribute to handle exception filtering for WebDAV requests.
+    /// </summary>
+    public class WebDavAnyExceptionFilterAttribute : WebDavExceptionFilterAttribute
+    {
+        /// <inheritdoc />
+        public override async Task OnExceptionAsync(ExceptionContext context)
+        {
+            await base.OnExceptionAsync(context);
+
+            if (context.ExceptionHandled)
+            {
+                return;
+            }
+
+            // Return an internal server error status for all other exceptions
+            context.Result = BuildResultForStatusCode(
+                context,
+                WebDavStatusCode.InternalServerError);
+            context.ExceptionHandled = true;
+        }
+    }
+}
diff --git a/src/FubarDev.WebDavServer.AspNetCore/Filters/WebDavExceptionFilterAttribute.cs b/src/FubarDev.WebDavServer.AspNetCore/Filters/WebDavExceptionFilterAttribute.cs
index 0decf517..a83df403 100644
--- a/src/FubarDev.WebDavServer.AspNetCore/Filters/WebDavExceptionFilterAttribute.cs
+++ b/src/FubarDev.WebDavServer.AspNetCore/Filters/WebDavExceptionFilterAttribute.cs
@@ -15,6 +15,9 @@
 
 namespace FubarDev.WebDavServer.AspNetCore.Filters
 {
+    /// <summary>
+    /// Attribute to handle exception filtering for WebDAV requests.
+    /// </summary>
     public class WebDavExceptionFilterAttribute : ExceptionFilterAttribute
     {
         /// <inheritdoc />
@@ -33,11 +36,11 @@ public override void OnException(ExceptionContext context)
                     context.ExceptionHandled = true;
                     return;
                 case WebDavException webDavException:
-                    context.Result = BuildResultForStatusCode(context, webDavException.StatusCode, webDavException.Message);
+                    context.Result = BuildResultForStatusCode(context, webDavException.StatusCode);
                     context.ExceptionHandled = true;
                     return;
-                case UnauthorizedAccessException unauthorizedAccessException:
-                    context.Result = BuildResultForStatusCode(context, WebDavStatusCode.Forbidden, unauthorizedAccessException.Message);
+                case UnauthorizedAccessException:
+                    context.Result = BuildResultForStatusCode(context, WebDavStatusCode.Forbidden);
                     context.ExceptionHandled = true;
                     return;
             }
@@ -50,10 +53,10 @@ public override void OnException(ExceptionContext context)
                 context.Exception.Message);
         }
 
-        private IActionResult BuildResultForStatusCode(
+        protected static IActionResult BuildResultForStatusCode(
             ExceptionContext context,
             WebDavStatusCode statusCode,
-            string optionalMessage)
+            string? optionalMessage = null)
         {
             switch (statusCode)
             {
@@ -74,7 +77,10 @@ private IActionResult BuildResultForStatusCode(
                             ItemsElementName = new[] { ItemsChoiceType2.status, },
                             Items = new object[]
                             {
-                                new Status(context.HttpContext.Request.Protocol, statusCode, optionalMessage).ToString(),
+                                new Status(
+                                    context.HttpContext.Request.Protocol,
+                                    statusCode,
+                                    optionalMessage ?? context.Exception.Message).ToString(),
                             },
                         },
                     },
diff --git a/src/FubarDev.WebDavServer/Model/WebDavStatusCode.cs b/src/FubarDev.WebDavServer/Model/WebDavStatusCode.cs
index e254f03d..ebbae099 100644
--- a/src/FubarDev.WebDavServer/Model/WebDavStatusCode.cs
+++ b/src/FubarDev.WebDavServer/Model/WebDavStatusCode.cs
@@ -101,6 +101,11 @@ public enum WebDavStatusCode
         /// </summary>
         FailedDependency = 424,
 
+        /// <summary>
+        /// The <c>Internal Server Error</c> (500) status code
+        /// </summary>
+        InternalServerError = HttpStatusCode.InternalServerError,
+
         /// <summary>
         /// The <c>Not Implemented</c> (501) status code
         /// </summary>