Correctly handle HEAD requests.

WalletWasabi.Backend/Middlewares/HeadMethodMiddleware.cs

@@ -0,0 +1,55 @@
+using Microsoft.AspNetCore.Http;
+using System;
+using System.Collections.Generic;
+using System.IO;
+using System.Linq;
+using System.Threading.Tasks;
+
+namespace WalletWasabi.Backend.Middlewares
+{
+	/// <summary>
+	/// https://www.tpeczek.com/2017/10/exploring-head-method-behavior-in.html
+	/// https://github.com/tpeczek/Demo.AspNetCore.Mvc.CosmosDB/blob/master/Demo.AspNetCore.Mvc.CosmosDB/Middlewares/HeadMethodMiddleware.cs
+	/// </summary>
+	public class HeadMethodMiddleware
+	{
+		#region Fields
+
+		private readonly RequestDelegate _next;
+
+		#endregion Fields
+
+		#region Constructor
+
+		public HeadMethodMiddleware(RequestDelegate next)
+		{
+			_next = next ?? throw new ArgumentNullException(nameof(next));
+		}
+
+		#endregion Constructor
+
+		#region Methods
+
+		public async Task InvokeAsync(HttpContext context)
+		{
+			bool methodSwitched = false;
+
+			if (HttpMethods.IsHead(context.Request.Method))
+			{
+				methodSwitched = true;
+
+				context.Request.Method = HttpMethods.Get;
+				context.Response.Body = Stream.Null;
+			}
+
+			await _next(context);
+
+			if (methodSwitched)
+			{
+				context.Request.Method = HttpMethods.Head;
+			}
+		}
+
+		#endregion Methods
+	}
+}

WalletWasabi.Backend/Startup.cs

@@ -11,6 +11,7 @@
 using WalletWasabi.Logging;
 using WalletWasabi.Interfaces;
 using Microsoft.AspNetCore.HttpOverrides;
+using WalletWasabi.Backend.Middlewares;
 
 namespace WalletWasabi.Backend
 {
@@ -58,6 +59,11 @@ public void Configure(IApplicationBuilder app, IHostingEnvironment env)
 				c.SwaggerEndpoint("/swagger/v2/swagger.json", "Wasabi Wallet API V2");
 			});
 
+			// So to correctly handle HEAD requests.
+			// https://www.tpeczek.com/2017/10/exploring-head-method-behavior-in.html
+			// https://github.com/tpeczek/Demo.AspNetCore.Mvc.CosmosDB/blob/master/Demo.AspNetCore.Mvc.CosmosDB/Middlewares/HeadMethodMiddleware.cs
+			app.UseMiddleware<HeadMethodMiddleware>();
+
 			app.UseMvc();
 
 			var applicationLifetime = app.ApplicationServices.GetRequiredService<IApplicationLifetime>();