CSHARP-1994: Enable and configure TCP Keepalive by default.

Author: rstam

src/MongoDB.Driver.Core/Core/Connections/KeepAliveValues.cs

@@ -0,0 +1,35 @@
+/* Copyright 2018-present MongoDB Inc.
+*
+* Licensed under the Apache License, Version 2.0 (the "License");
+* you may not use this file except in compliance with the License.
+* You may obtain a copy of the License at
+*
+* http://www.apache.org/licenses/LICENSE-2.0
+*
+* Unless required by applicable law or agreed to in writing, software
+* distributed under the License is distributed on an "AS IS" BASIS,
+* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+* See the License for the specific language governing permissions and
+* limitations under the License.
+*/
+
+using System;
+
+namespace MongoDB.Driver.Core.Connections
+{
+    internal struct KeepAliveValues
+    {
+        public ulong OnOff { get; set; }
+        public ulong KeepAliveTime { get; set; }
+        public ulong KeepAliveInterval { get; set; }
+
+        public byte[] ToBytes()
+        {
+            var bytes = new byte[24];
+            Array.Copy(BitConverter.GetBytes(OnOff), 0, bytes, 0, 8);
+            Array.Copy(BitConverter.GetBytes(KeepAliveTime), 0, bytes, 8, 8);
+            Array.Copy(BitConverter.GetBytes(KeepAliveInterval), 0, bytes, 16, 8);
+            return bytes;
+        }
+    }
+}

src/MongoDB.Driver.Core/Core/Connections/TcpStreamFactory.cs

@@ -249,7 +249,16 @@ private Socket CreateSocket(EndPoint endPoint)
                 addressFamily = _settings.AddressFamily;
             }
 
-            return new Socket(addressFamily, SocketType.Stream, ProtocolType.Tcp);
+            var socket = new Socket(addressFamily, SocketType.Stream, ProtocolType.Tcp);
+            var keepAliveValues = new KeepAliveValues
+            {
+                OnOff = 1,
+                KeepAliveTime = 300000, // 300 seconds in milliseconds
+                KeepAliveInterval = 10000 // 10 seconds in milliseconds
+            };
+            socket.IOControl(IOControlCode.KeepAliveValues, keepAliveValues.ToBytes(), null);
+
+            return socket;
         }
 
         private async Task<EndPoint[]> ResolveEndPointsAsync(EndPoint initial)

src/MongoDB.Driver.Core/MongoDB.Driver.Core.csproj

@@ -122,6 +122,7 @@
     <Compile Include="Core\Configuration\SdamLoggingSettings.cs" />
     <Compile Include="Core\Connections\ClientDocumentHelper.cs" />
     <Compile Include="Core\Connections\IsMasterHelper.cs" />
+    <Compile Include="Core\Connections\KeepAliveValues.cs" />
     <Compile Include="Core\Events\Diagnostics\TraceSourceSdamEventSubscriber.cs" />
     <Compile Include="Core\Events\SdamInformationEvent.cs" />
     <Compile Include="Core\Misc\ArrayFiltersFeature.cs" />