StandardSocketsHttpHandler: Added SocketCreated Event

The subscriber will be able to configure the socket to send TCP Keepalive

Author: TalAloni

StandardSocketsHttpHandler/Net/Http/SocketsHttpHandler/ConnectHelper.cs

@@ -14,6 +14,8 @@
 
 namespace System.Net.Http
 {
+    internal delegate void ConfigureSocket(Socket socket);
+
     internal static class ConnectHelper
     {
         /// <summary>Pool of event args to use to establish connections.</summary>
@@ -37,7 +39,7 @@ public CertificateCallbackMapper(Func<HttpRequestMessage, X509Certificate2, X509
             }
         }
 
-        public static async Task<(Socket, Stream)> ConnectAsync(string host, int port, CancellationToken cancellationToken)
+        public static async Task<(Socket, Stream)> ConnectAsync(string host, int port, ConfigureSocket configureSocket, CancellationToken cancellationToken)
         {
             // Rather than creating a new Socket and calling ConnectAsync on it, we use the static
             // Socket.ConnectAsync with a SocketAsyncEventArgs, as we can then use Socket.CancelConnectAsync
@@ -76,6 +78,7 @@ public CertificateCallbackMapper(Func<HttpRequestMessage, X509Certificate2, X509
                 // Configure the socket and return a stream for it.
                 Socket socket = saea.ConnectSocket;
                 socket.NoDelay = true;
+                configureSocket(socket);
                 return (socket, new NetworkStream(socket, ownsSocket: true));
             }
             catch (Exception error)

StandardSocketsHttpHandler/Net/Http/SocketsHttpHandler/HttpConnectionPool.cs

@@ -359,11 +359,11 @@ public Task<HttpResponseMessage> SendAsync(HttpRequestMessage request, bool doRe
                     case HttpConnectionKind.Http:
                     case HttpConnectionKind.Https:
                     case HttpConnectionKind.ProxyConnect:
-                        (socket, stream) = await ConnectHelper.ConnectAsync(_host, _port, cancellationToken).ConfigureAwait(false);
+                        (socket, stream) = await ConnectHelper.ConnectAsync(_host, _port, _poolManager.Settings._configureSocket, cancellationToken).ConfigureAwait(false);
                         break;
 
                     case HttpConnectionKind.Proxy:
-                        (socket, stream) = await ConnectHelper.ConnectAsync(_proxyUri.IdnHost, _proxyUri.Port, cancellationToken).ConfigureAwait(false);
+                        (socket, stream) = await ConnectHelper.ConnectAsync(_proxyUri.IdnHost, _proxyUri.Port, _poolManager.Settings._configureSocket, cancellationToken).ConfigureAwait(false);
                         break;
 
                     case HttpConnectionKind.ProxyTunnel:

StandardSocketsHttpHandler/Net/Http/SocketsHttpHandler/HttpConnectionSettings.cs

@@ -38,6 +38,7 @@ internal sealed class HttpConnectionSettings
         internal SslClientAuthenticationOptions _sslOptions;
 
         internal IDictionary<string, object> _properties;
+        internal ConfigureSocket _configureSocket = (_) => { };
 
         public HttpConnectionSettings Clone()
         {
@@ -67,6 +68,7 @@ public HttpConnectionSettings Clone()
                 _properties = _properties,
                 _proxy = _proxy,
                 _sslOptions = _sslOptions?.ShallowClone(), // shallow clone the options for basic prevention of mutation issues while processing
+                _configureSocket = _configureSocket,
                 _useCookies = _useCookies,
                 _useProxy = _useProxy,
             };

StandardSocketsHttpHandler/Net/Http/SocketsHttpHandler/StandardSocketsHttpHandler.cs

@@ -4,6 +4,7 @@
 
 using System.Collections.Generic;
 using System.Net.Security;
+using System.Net.Sockets;
 using System.Threading;
 using System.Threading.Tasks;
 
@@ -14,6 +15,16 @@ public sealed class StandardSocketsHttpHandler : HttpMessageHandler
         private readonly HttpConnectionSettings _settings = new HttpConnectionSettings();
         private StandardHttpMessageHandler _handler;
         private bool _disposed;
+        
+        public event EventHandler<Socket> SocketCreated;
+
+        public StandardSocketsHttpHandler()
+        {
+            _settings._configureSocket = (Socket socket) =>
+            {
+                SocketCreated?.Invoke(this, socket);
+            };
+        }
 
         private void CheckDisposed()
         {