From 7d9efbcb9068ceec3f548e34c6ff9ff9d3a8d904 Mon Sep 17 00:00:00 2001
From: Natalia Portillo <claunia@claunia.com>
Date: Sat, 14 Dec 2019 03:15:33 +0000
Subject: [PATCH] Add authentication to metrics.

---
 DiscImageChef.Server/BasicAuthMiddleware.cs | 71 +++++++++++++++++++++
 DiscImageChef.Server/Startup.cs             |  8 ++-
 2 files changed, 78 insertions(+), 1 deletion(-)
 create mode 100644 DiscImageChef.Server/BasicAuthMiddleware.cs

diff --git a/DiscImageChef.Server/BasicAuthMiddleware.cs b/DiscImageChef.Server/BasicAuthMiddleware.cs
new file mode 100644
index 00000000..8f181469
--- /dev/null
+++ b/DiscImageChef.Server/BasicAuthMiddleware.cs
@@ -0,0 +1,71 @@
+// -------------------------------------------------------------------------------------------------
+// Copyright (c) Johan Boström. All rights reserved.
+// Licensed under the Apache License, Version 2.0. See LICENSE in the project root for license information.
+// -------------------------------------------------------------------------------------------------
+
+using System;
+using System.Net;
+using System.Text;
+using System.Threading.Tasks;
+using Microsoft.AspNetCore.Http;
+
+namespace DiscImageChef.Server
+{
+    public class BasicAuthMiddleware
+    {
+        readonly RequestDelegate next;
+        readonly string          realm;
+
+        public BasicAuthMiddleware(RequestDelegate next, string realm)
+        {
+            this.next  = next;
+            this.realm = realm;
+        }
+
+        public async Task Invoke(HttpContext context)
+        {
+            string authHeader = context.Request.Headers["Authorization"];
+
+            if(authHeader != null &&
+               authHeader.StartsWith("Basic "))
+            {
+                // Get the encoded username and password
+                string encodedUsernamePassword =
+                    authHeader.Split(' ', 2, StringSplitOptions.RemoveEmptyEntries)[1]?.Trim();
+
+                // Decode from Base64 to string
+                string decodedUsernamePassword =
+                    Encoding.UTF8.GetString(Convert.FromBase64String(encodedUsernamePassword));
+
+                // Split username and password
+                string username = decodedUsernamePassword.Split(':', 2)[0];
+                string password = decodedUsernamePassword.Split(':', 2)[1];
+
+                // Check if login is correct
+                if(IsAuthorized(username, password))
+                {
+                    await next.Invoke(context);
+
+                    return;
+                }
+            }
+
+            // Return authentication type (causes browser to show login dialog)
+            context.Response.Headers["WWW-Authenticate"] = "Basic";
+
+            // Add realm if it is not null
+            if(!string.IsNullOrWhiteSpace(realm))
+            {
+                context.Response.Headers["WWW-Authenticate"] += $" realm=\"{realm}\"";
+            }
+
+            // Return unauthorized
+            context.Response.StatusCode = (int)HttpStatusCode.Unauthorized;
+        }
+
+        // Make your own implementation of this
+        // Check that username and password are correct
+        public bool IsAuthorized(string username, string password) =>
+            username.Equals("User1", StringComparison.InvariantCultureIgnoreCase) && password.Equals("SecretPassword!");
+    }
+}
\ No newline at end of file
diff --git a/DiscImageChef.Server/Startup.cs b/DiscImageChef.Server/Startup.cs
index c0e8796e..b83b014b 100644
--- a/DiscImageChef.Server/Startup.cs
+++ b/DiscImageChef.Server/Startup.cs
@@ -71,7 +71,13 @@ namespace DiscImageChef.Server
                 endpoints.MapRazorPages();
             });
 
-            app.UseMetricServer();
+            app.Map("/metrics", metricsApp =>
+            {
+                metricsApp.UseMiddleware<BasicAuthMiddleware>("DiscImageChef");
+
+                // We already specified URL prefix in .Map() above, no need to specify it again here.
+                metricsApp.UseMetricServer("");
+            });
         }
     }
 }
\ No newline at end of file