feat: Add Options Verb Handler to work with preflight requests

Author: drwatson1

ProjectTemplates/AspNetCore.WebApi/ReferenceProject/ReferenceProject/Middleware/OptionsVerbMiddleware.cs

@@ -0,0 +1,29 @@
+using Microsoft.AspNetCore.Http;
+using System.Threading.Tasks;
+
+namespace ReferenceProject.Middleware
+{
+    // https://developer.mozilla.org/en-US/docs/Web/HTTP/CORS
+    // https://developer.mozilla.org/en-US/docs/Web/HTTP/CORS#Preflighted_requests
+    // https://developer.mozilla.org/ru/docs/Web/HTTP/Methods/OPTIONS
+    public class OptionsVerbMiddleware
+    {
+        RequestDelegate Next { get; }
+
+        public OptionsVerbMiddleware(RequestDelegate next)
+        {
+            Next = next;
+        }
+
+        public Task InvokeAsync(HttpContext context)
+        {
+            if (context.Request.Method == "OPTIONS")
+            {
+                context.Response.StatusCode = StatusCodes.Status200OK;
+                context.Response.Headers.Add("Access-Control-Allow-Methods", "*");
+                return Task.CompletedTask;
+            }
+            return Next.Invoke(context);
+        }
+    }
+}

ProjectTemplates/AspNetCore.WebApi/ReferenceProject/ReferenceProject/Middleware/OptionsVerbMiddlewareExtensions.cs

@@ -0,0 +1,13 @@
+using Microsoft.AspNetCore.Builder;
+
+namespace ReferenceProject
+{
+    public static class OptionsVerbMiddlewareExtensions
+    {
+        public static IApplicationBuilder UseOptionsVerbHandler(
+            this IApplicationBuilder builder)
+        {
+            return builder.UseMiddleware<Middleware.OptionsVerbMiddleware>();
+        }
+    }
+}

ProjectTemplates/AspNetCore.WebApi/ReferenceProject/ReferenceProject/Startup.cs

@@ -14,9 +14,12 @@
 using Newtonsoft.Json;
 using Newtonsoft.Json.Serialization;
 using ReferenceProject.Filters;
-using ReferenceProject.Middleware;
 using ReferenceProject.Modules;
 
+// TODO: Create and validate configuration in web.config:
+// https://www.talkingdotnet.com/how-to-increase-file-upload-size-asp-net-core/
+// https://docs.microsoft.com/en-us/aspnet/core/host-and-deploy/iis/?view=aspnetcore-2.1&tabs=aspnetcore2x#webconfig-file
+
 namespace ReferenceProject
 {
     public class Startup
@@ -119,6 +122,9 @@ public void Configure(IApplicationBuilder app/*, IHostingEnvironment env*/)
                 .AllowAnyHeader()
                 .AllowCredentials());
 
+            // Options verb handler must be added after CORS
+            app.UseOptionsVerbHandler();
+
             app.UseMvcWithDefaultRoute();
 
             Logger.LogInformation("Server started");

ProjectTemplates/AspNetCore.WebApi/ReferenceProject/ReferenceProject/web.config

@@ -6,16 +6,24 @@
         </system.web>
 
         <system.webServer>
+            <modules runAllManagedModulesForAllRequests="false">
+                <remove name="WebDAVModule" />
+            </modules>            
+
             <handlers>
+                <clear/>
                 <add name="aspNetCore" path="*" verb="*" modules="AspNetCoreModule" resourceType="Unspecified" />
             </handlers>
+            
             <aspNetCore processPath="%LAUNCHER_PATH%" arguments="%LAUNCHER_ARGS%" stdoutLogEnabled="false" stdoutLogFile=".\logs\stdout" forwardWindowsAuthToken="false"/>
+            
             <httpProtocol>
                 <customHeaders>
                     <!-- X-Powered-By - Remove the HTTP header for added security and a slight performance increase. -->
                     <clear />
                 </customHeaders>
             </httpProtocol>
+            
             <security>
                 <requestFiltering>
                     <!-- maxAllowedContentLength - Specifies the maximum length of content in a request, in bytes. The default value is 30000000 (~28.6 MB) and has