Merge pull request zeromq#1132 from chrbauer/feature/linux-tcp-keepalive

Support Tcp KeepAlive under Linux (.net8 only)

Author: drewnoakes

src/NetMQ.Tests/SocketOptionsTests.cs

@@ -77,8 +77,8 @@ public void GetAndSetAllProperties()
                 socket.Options.TcpKeepalive = true;
                 Assert.True(socket.Options.TcpKeepalive);
 
-//                socket.Options.TcpKeepaliveCnt = 100;
-//                Assert.Equal(100, socket.Options.TcpKeepaliveCnt);
+                socket.Options.TcpKeepaliveCnt = 100;
+                Assert.Equal(100, socket.Options.TcpKeepaliveCnt);
 
                 socket.Options.TcpKeepaliveIdle = TimeSpan.FromMilliseconds(100);
                 Assert.Equal(TimeSpan.FromMilliseconds(100), socket.Options.TcpKeepaliveIdle);

src/NetMQ/Core/Options.cs

@@ -452,6 +452,10 @@ public void SetSocketOption(ZmqSocketOption option, object? optionValue)
                     TcpKeepalive = tcpKeepalive;
                     break;
 
+                case ZmqSocketOption.TcpKeepaliveCnt:
+                    TcpKeepaliveCnt = Get<int>();
+                    break;
+
                 case ZmqSocketOption.DelayAttachOnConnect:
                     DelayAttachOnConnect = Get<bool>();
                     break;
@@ -649,6 +653,9 @@ public void SetSocketOption(ZmqSocketOption option, object? optionValue)
                 case ZmqSocketOption.TcpKeepalive:
                     return TcpKeepalive;
 
+                case ZmqSocketOption.TcpKeepaliveCnt:
+                    return TcpKeepaliveCnt;
+
                 case ZmqSocketOption.DelayAttachOnConnect:
                     return DelayAttachOnConnect;
 

src/NetMQ/Core/Transports/Tcp/TcpConnector.cs

@@ -248,6 +248,14 @@ public void OutCompleted(SocketError socketError, int bytesTransferred)
                     // Set the TCP keep-alive option values to the underlying socket.
                     m_s.SetSocketOption(SocketOptionLevel.Socket, SocketOptionName.KeepAlive, m_options.TcpKeepalive);
 
+#if NET
+                    if (m_options.TcpKeepaliveIdle != -1)
+                        m_s.SetSocketOption(SocketOptionLevel.Tcp, SocketOptionName.TcpKeepAliveTime, m_options.TcpKeepaliveIdle / 1000);
+                    if (m_options.TcpKeepaliveIntvl != -1)
+                        m_s.SetSocketOption(SocketOptionLevel.Tcp, SocketOptionName.TcpKeepAliveInterval, m_options.TcpKeepaliveIntvl / 1000);
+                    if (m_options.TcpKeepaliveCnt != -1)
+                        m_s.SetSocketOption(SocketOptionLevel.Tcp, SocketOptionName.TcpKeepAliveRetryCount, m_options.TcpKeepaliveCnt);
+#else
                     if (m_options.TcpKeepaliveIdle != -1 && m_options.TcpKeepaliveIntvl != -1)
                     {
                         // Write the TCP keep-alive options to a byte-array, to feed to the IOControl method..
@@ -259,16 +267,9 @@ public void OutCompleted(SocketError socketError, int bytesTransferred)
                         bytes.PutInteger(endian, m_options.TcpKeepaliveIdle, 4);
                         bytes.PutInteger(endian, m_options.TcpKeepaliveIntvl, 8);
 
-#if NET
-                        if (!OperatingSystem.IsWindows())
-                        {
-                            throw new InvalidOperationException("Not supported on you platform"); // There is a pull request for .net8.0
-
-                        }
-#endif
                         m_s.IOControl(IOControlCode.KeepAliveValues, (byte[])bytes, null);
-
                     }
+#endif
                 }
 
                 // Create the engine object for this connection.

src/NetMQ/Core/Transports/Tcp/TcpListener.cs

@@ -204,6 +204,14 @@ public void InCompleted(SocketError socketError, int bytesTransferred)
                     if (m_options.TcpKeepalive != -1)
                     {
                         acceptedSocket.SetSocketOption(SocketOptionLevel.Socket, SocketOptionName.KeepAlive, m_options.TcpKeepalive);
+#if NET
+                            if (m_options.TcpKeepaliveIdle != -1)
+                                acceptedSocket.SetSocketOption(SocketOptionLevel.Tcp, SocketOptionName.TcpKeepAliveTime, m_options.TcpKeepaliveIdle / 1000);
+                            if (m_options.TcpKeepaliveIntvl != -1)
+                                acceptedSocket.SetSocketOption(SocketOptionLevel.Tcp, SocketOptionName.TcpKeepAliveInterval, m_options.TcpKeepaliveIntvl / 1000);
+                            if (m_options.TcpKeepaliveCnt != -1)
+                                acceptedSocket.SetSocketOption(SocketOptionLevel.Tcp, SocketOptionName.TcpKeepAliveRetryCount, m_options.TcpKeepaliveCnt);
+#else
 
                         if (m_options.TcpKeepaliveIdle != -1 && m_options.TcpKeepaliveIntvl != -1)
                         {
@@ -214,15 +222,11 @@ public void InCompleted(SocketError socketError, int bytesTransferred)
                             bytes.PutInteger(endian, m_options.TcpKeepalive, 0);
                             bytes.PutInteger(endian, m_options.TcpKeepaliveIdle, 4);
                             bytes.PutInteger(endian, m_options.TcpKeepaliveIntvl, 8);
-#if NET
-                                if (!OperatingSystem.IsWindows())
-                                {
-                                    throw new InvalidOperationException("Not supported on you platform"); // There is a pull request for .net8.0
 
-                                }
-#endif
+
                             acceptedSocket.IOControl(IOControlCode.KeepAliveValues, (byte[])bytes, null);
                         }
+#endif
                     }
 
                     // Create the engine object for this connection.

src/NetMQ/Core/ZmqSocketOption.cs

@@ -197,6 +197,15 @@ internal enum ZmqSocketOption
         /// </summary>
         TcpKeepalive = 34,
 
+        /// <summary>
+        /// The maximum number of keepalive probes TCP should send before dropping the connection.
+        /// </summary>
+        /// <remarks>
+        /// This setting controls how many unacknowledged probes are sent before the connection is considered dead.
+        /// A value of -1 (the default) means to use the OS default setting.
+        /// </remarks>
+        TcpKeepaliveCnt = 35,
+
         /// <summary>
         /// The keep-alive time - the duration between two keepalive transmissions in idle condition.
         /// </summary>

src/NetMQ/SocketOptions.cs

@@ -283,6 +283,21 @@ public bool TcpKeepalive
             // See  http://api.zeromq.org/3-2:zmq-getsockopt
         }
 
+
+        /// <summary>
+        /// Get or set the maximum number of TCP keepalive probes to send before dropping the connection.
+        /// </summary>
+        /// <remarks>
+        /// This value determines how many unacknowledged keepalive probes TCP should send before assuming the connection is dead.
+        /// A lower value means faster detection of dead peers, while a higher value allows more tolerance for temporary disruptions.
+        /// A value of -1 (the default) means to use the OS default setting.
+        /// </remarks>
+        public int TcpKeepaliveCnt
+        {
+            get => m_socket.GetSocketOption(ZmqSocketOption.TcpKeepaliveCnt);
+            set => m_socket.SetSocketOption(ZmqSocketOption.TcpKeepaliveCnt, value);
+        }
+
         /// <summary>
         /// Get or set the keep-alive time - the duration between two keepalive transmissions in idle condition.
         /// The TCP keepalive period is required by socket implementers to be configurable and by default is