Allow to adjust the handler and client used by the reverse proxy (#621)

Author: Kaliumhexacyanoferrat

Modules/ReverseProxy/Provider/ReverseProxyBuilder.cs

@@ -1,4 +1,6 @@
-using GenHTTP.Api.Content;
+using System.Net;
+
+using GenHTTP.Api.Content;
 using GenHTTP.Api.Infrastructure;
 
 namespace GenHTTP.Modules.ReverseProxy.Provider;
@@ -12,8 +14,15 @@ public sealed class ReverseProxyBuilder : IHandlerBuilder<ReverseProxyBuilder>
 
     private string? _Upstream;
 
+    private Action<SocketsHttpHandler>? _HandlerAdjustments;
+    private Action<HttpClient>? _ClientAdjustments;
+
     #region Functionality
 
+    /// <summary>
+    /// Sets the server to pass the incoming requests to.
+    /// </summary>
+    /// <param name="upstream">The URL of the server to pass requests to</param>
     public ReverseProxyBuilder Upstream(string upstream)
     {
         _Upstream = upstream;
@@ -26,18 +35,46 @@ public ReverseProxyBuilder Upstream(string upstream)
         return this;
     }
 
+    /// <summary>
+    /// The time allowed to try connecting to the upstream server (defaults to 10 seconds).
+    /// </summary>
+    /// <param name="connectTimeout">The connection timeout to be set</param>
     public ReverseProxyBuilder ConnectTimeout(TimeSpan connectTimeout)
     {
         _ConnectTimeout = connectTimeout;
         return this;
     }
 
+    /// <summary>
+    /// The time allowed for the upstream server to generate a response (defaults to 60 seconds).
+    /// </summary>
+    /// <param name="readTimeout">The read timeout to be set</param>
     public ReverseProxyBuilder ReadTimeout(TimeSpan readTimeout)
     {
         _ReadTimeout = readTimeout;
         return this;
     }
 
+    /// <summary>
+    /// A callback to be invoked to configure the socket HTTP handler used by the handler.
+    /// </summary>
+    /// <param name="adjustment">The callback to be invoked</param>
+    public ReverseProxyBuilder AdjustHandler(Action<SocketsHttpHandler> adjustment)
+    {
+        _HandlerAdjustments = adjustment;
+        return this;
+    }
+
+    /// <summary>
+    /// A callback to be invoked to configure the HTTP client used by the handler.
+    /// </summary>
+    /// <param name="adjustment">The callback to be invoked</param>
+    public ReverseProxyBuilder AdjustClient(Action<HttpClient> adjustment)
+    {
+        _ClientAdjustments = adjustment;
+        return this;
+    }
+
     public ReverseProxyBuilder Add(IConcernBuilder concern)
     {
         _Concerns.Add(concern);
@@ -51,7 +88,23 @@ public IHandler Build()
             throw new BuilderMissingPropertyException("Upstream");
         }
 
-        return Concerns.Chain(_Concerns,  new ReverseProxyProvider( _Upstream, _ConnectTimeout, _ReadTimeout));
+        var handler = new SocketsHttpHandler
+        {
+            AllowAutoRedirect = false,
+            AutomaticDecompression = DecompressionMethods.None,
+            ConnectTimeout = _ConnectTimeout
+        };
+
+        _HandlerAdjustments?.Invoke(handler);
+
+        var client = new HttpClient(handler)
+        {
+            Timeout = _ReadTimeout
+        };
+
+        _ClientAdjustments?.Invoke(client);
+
+        return Concerns.Chain(_Concerns, new ReverseProxyProvider(_Upstream, client));
     }
 
     #endregion

Modules/ReverseProxy/Provider/ReverseProxyProvider.cs

@@ -1,9 +1,10 @@
 using System.Globalization;
-using System.Net;
 using System.Net.Http.Headers;
 using System.Web;
+
 using GenHTTP.Api.Content;
 using GenHTTP.Api.Protocol;
+
 using GenHTTP.Modules.Basics;
 
 namespace GenHTTP.Modules.ReverseProxy.Provider;
@@ -40,21 +41,10 @@ public sealed class ReverseProxyProvider : IHandler
 
     #region Initialization
 
-    public ReverseProxyProvider(string upstream, TimeSpan connectTimeout, TimeSpan readTimeout)
+    public ReverseProxyProvider(string upstream, HttpClient client)
     {
         Upstream = upstream;
-
-        var handler = new SocketsHttpHandler
-        {
-            AllowAutoRedirect = false,
-            AutomaticDecompression = DecompressionMethods.None,
-            ConnectTimeout = connectTimeout
-        };
-
-        Client = new HttpClient(handler)
-        {
-            Timeout = readTimeout
-        };
+        Client = client;
     }
 
     #endregion

Modules/ReverseProxy/Proxy.cs

@@ -5,5 +5,11 @@ namespace GenHTTP.Modules.ReverseProxy;
 public static class Proxy
 {
 
+    /// <summary>
+    /// Creates a handler that will route incoming requests to
+    /// the specified upstream server.
+    /// </summary>
+    /// <returns>The newly created handler</returns>
     public static ReverseProxyBuilder Create() => new();
+
 }

Testing/Acceptance/Modules/ReverseProxy/ReverseProxyTests.cs

@@ -287,6 +287,21 @@ public async Task TestCompression(TestEngine engine)
         Assert.AreEqual("br", response.GetContentHeader("Content-Encoding"));
     }
 
+    [TestMethod]
+    public void TestAdjustments()
+    {
+        var i = 0;
+
+        var proxy = Proxy.Create()
+                         .Upstream("https://google.com")
+                         .AdjustHandler(h => i++)
+                         .AdjustClient(c => i++);
+
+        proxy.Build();
+
+        Assert.AreEqual(2, i);
+    }
+
     #region Supporting data structures
 
     private class TestSetup : IAsyncDisposable