Remove "IsErrorResumable" and SocketAbstraction.Send{Async}

Some methods in SocketAbstraction have code to retry a socket operation if it
returns certain error codes. However AFAIK, these errors are only pertinent to
nonblocking sockets, which we do not use.

For blocking sockets, Socket.Send{Async} only returns when all of the bytes are
sent. There is no need for a loop.

These changes combined mean there is no need for Send methods in SocketAbstraction.

Author: Rob-Hague

src/Renci.SshNet/Abstractions/SocketAbstraction.Async.cs

@@ -1,7 +1,5 @@
 #if NET6_0_OR_GREATER
 
-using System;
-using System.Diagnostics;
 using System.Net.Sockets;
 using System.Threading;
 using System.Threading.Tasks;
@@ -14,37 +12,6 @@ public static ValueTask<int> ReadAsync(Socket socket, byte[] buffer, Cancellatio
         {
             return socket.ReceiveAsync(buffer, SocketFlags.None, cancellationToken);
         }
-
-        public static ValueTask SendAsync(Socket socket, ReadOnlyMemory<byte> data, CancellationToken cancellationToken = default)
-        {
-            Debug.Assert(socket != null);
-            Debug.Assert(data.Length > 0);
-
-            if (cancellationToken.IsCancellationRequested)
-            {
-                return ValueTask.FromCanceled(cancellationToken);
-            }
-
-            return SendAsyncCore(socket, data, cancellationToken);
-
-            static async ValueTask SendAsyncCore(Socket socket, ReadOnlyMemory<byte> data, CancellationToken cancellationToken)
-            {
-                do
-                {
-                    try
-                    {
-                        var bytesSent = await socket.SendAsync(data, SocketFlags.None, cancellationToken).ConfigureAwait(false);
-                        data = data.Slice(bytesSent);
-                    }
-                    catch (SocketException ex) when (IsErrorResumable(ex.SocketErrorCode))
-                    {
-                        // Buffer may be full; attempt a short delay and retry
-                        await Task.Delay(30, cancellationToken).ConfigureAwait(false);
-                    }
-                }
-                while (data.Length > 0);
-            }
-        }
     }
 }
 #endif // NET6_0_OR_GREATER

src/Renci.SshNet/Abstractions/SocketAbstraction.cs

@@ -6,7 +6,6 @@
 using System.Threading.Tasks;
 
 using Renci.SshNet.Common;
-using Renci.SshNet.Messages.Transport;
 
 namespace Renci.SshNet.Abstractions
 {
@@ -167,11 +166,6 @@ public static void ReadContinuous(Socket socket, byte[] buffer, int offset, int
                 }
                 catch (SocketException ex)
                 {
-                    if (IsErrorResumable(ex.SocketErrorCode))
-                    {
-                        continue;
-                    }
-
 #pragma warning disable IDE0010 // Add missing cases
                     switch (ex.SocketErrorCode)
                     {
@@ -221,7 +215,7 @@ public static int ReadByte(Socket socket, TimeSpan timeout)
         public static void SendByte(Socket socket, byte value)
         {
             var buffer = new[] { value };
-            Send(socket, buffer, 0, 1);
+            _ = socket.Send(buffer);
         }
 
         /// <summary>
@@ -288,22 +282,12 @@ public static int Read(Socket socket, byte[] buffer, int offset, int size, TimeS
 
                     totalBytesRead += bytesRead;
                 }
-                catch (SocketException ex)
+                catch (SocketException ex) when (ex.SocketErrorCode == SocketError.TimedOut)
                 {
-                    if (IsErrorResumable(ex.SocketErrorCode))
-                    {
-                        ThreadAbstraction.Sleep(30);
-                        continue;
-                    }
-
-                    if (ex.SocketErrorCode == SocketError.TimedOut)
-                    {
-                        throw new SshOperationTimeoutException(string.Format(CultureInfo.InvariantCulture,
-                                                               "Socket read operation has timed out after {0:F0} milliseconds.",
-                                                               readTimeout.TotalMilliseconds));
-                    }
-
-                    throw;
+                    throw new SshOperationTimeoutException(string.Format(CultureInfo.InvariantCulture,
+                                                            "Socket read operation has timed out after {0:F0} milliseconds.",
+                                                            readTimeout.TotalMilliseconds),
+                                                            ex);
                 }
             }
             while (totalBytesRead < totalBytesToRead);
@@ -317,61 +301,6 @@ public static ValueTask<int> ReadAsync(Socket socket, byte[] buffer, Cancellatio
             return socket.ReceiveAsync(new ArraySegment<byte>(buffer, 0, buffer.Length), SocketFlags.None, cancellationToken);
         }
 #endif
-
-        public static void Send(Socket socket, byte[] data)
-        {
-            Send(socket, data, 0, data.Length);
-        }
-
-        public static void Send(Socket socket, byte[] data, int offset, int size)
-        {
-            var totalBytesSent = 0;  // how many bytes are already sent
-            var totalBytesToSend = size;
-
-            do
-            {
-                try
-                {
-                    var bytesSent = socket.Send(data, offset + totalBytesSent, totalBytesToSend - totalBytesSent, SocketFlags.None);
-                    if (bytesSent == 0)
-                    {
-                        throw new SshConnectionException("An established connection was aborted by the server.",
-                                                         DisconnectReason.ConnectionLost);
-                    }
-
-                    totalBytesSent += bytesSent;
-                }
-                catch (SocketException ex)
-                {
-                    if (IsErrorResumable(ex.SocketErrorCode))
-                    {
-                        // socket buffer is probably full, wait and try again
-                        ThreadAbstraction.Sleep(30);
-                    }
-                    else
-                    {
-                        throw; // any serious error occurr
-                    }
-                }
-            }
-            while (totalBytesSent < totalBytesToSend);
-        }
-
-        public static bool IsErrorResumable(SocketError socketError)
-        {
-#pragma warning disable IDE0010 // Add missing cases
-            switch (socketError)
-            {
-                case SocketError.WouldBlock:
-                case SocketError.IOPending:
-                case SocketError.NoBufferSpaceAvailable:
-                    return true;
-                default:
-                    return false;
-            }
-#pragma warning restore IDE0010 // Add missing cases
-        }
-
         private static void ConnectCompleted(object sender, SocketAsyncEventArgs e)
         {
             var eventWaitHandle = (ManualResetEvent) e.UserToken;

src/Renci.SshNet/Channels/ChannelDirectTcpip.cs

@@ -201,7 +201,7 @@ protected override void OnData(byte[] data)
                 {
                     if (_socket.IsConnected())
                     {
-                        SocketAbstraction.Send(_socket, data, 0, data.Length);
+                        _ = _socket.Send(data);
                     }
                 }
             }

src/Renci.SshNet/Channels/ChannelForwardedTcpip.cs

@@ -201,7 +201,7 @@ protected override void OnData(byte[] data)
             var socket = _socket;
             if (socket.IsConnected())
             {
-                SocketAbstraction.Send(socket, data, 0, data.Length);
+                _ = socket.Send(data);
             }
         }
     }

src/Renci.SshNet/Connection/HttpConnector.cs

@@ -3,6 +3,7 @@
 using System.Globalization;
 using System.Net;
 using System.Net.Sockets;
+using System.Text;
 using System.Text.RegularExpressions;
 
 using Renci.SshNet.Abstractions;
@@ -41,7 +42,7 @@ protected override void HandleProxyConnect(IConnectionInfo connectionInfo, Socke
             var httpResponseRe = new Regex(@"HTTP/(?<version>\d[.]\d) (?<statusCode>\d{3}) (?<reasonPhrase>.+)$");
             var httpHeaderRe = new Regex(@"(?<fieldName>[^\[\]()<>@,;:\""/?={} \t]+):(?<fieldValue>.+)?");
 
-            SocketAbstraction.Send(socket, SshData.Ascii.GetBytes(string.Format(CultureInfo.InvariantCulture,
+            _ = socket.Send(Encoding.ASCII.GetBytes(string.Format(CultureInfo.InvariantCulture,
                                                                                 "CONNECT {0}:{1} HTTP/1.0\r\n",
                                                                                 connectionInfo.Host,
                                                                                 connectionInfo.Port)));
@@ -51,11 +52,11 @@ protected override void HandleProxyConnect(IConnectionInfo connectionInfo, Socke
             {
                 var authorization = string.Format(CultureInfo.InvariantCulture,
                                                   "Proxy-Authorization: Basic {0}\r\n",
-                                                  Convert.ToBase64String(SshData.Ascii.GetBytes($"{connectionInfo.ProxyUsername}:{connectionInfo.ProxyPassword}")));
-                SocketAbstraction.Send(socket, SshData.Ascii.GetBytes(authorization));
+                                                  Convert.ToBase64String(Encoding.ASCII.GetBytes($"{connectionInfo.ProxyUsername}:{connectionInfo.ProxyPassword}")));
+                _ = socket.Send(Encoding.ASCII.GetBytes(authorization));
             }
 
-            SocketAbstraction.Send(socket, SshData.Ascii.GetBytes("\r\n"));
+            _ = socket.Send(Encoding.ASCII.GetBytes("\r\n"));
 
             HttpStatusCode? statusCode = null;
             var contentLength = 0;

src/Renci.SshNet/Connection/ProtocolVersionExchange.cs

@@ -38,7 +38,7 @@ public SshIdentification Start(string clientVersion, Socket socket, TimeSpan tim
         {
             // Immediately send the identification string since the spec states both sides MUST send an identification string
             // when the connection has been established
-            SocketAbstraction.Send(socket, Encoding.UTF8.GetBytes(clientVersion + "\x0D\x0A"));
+            _ = socket.Send(Encoding.UTF8.GetBytes(clientVersion + "\x0D\x0A"));
 
             var bytesReceived = new List<byte>();
 
@@ -81,11 +81,7 @@ public async Task<SshIdentification> StartAsync(string clientVersion, Socket soc
         {
             // Immediately send the identification string since the spec states both sides MUST send an identification string
             // when the connection has been established
-#if NET6_0_OR_GREATER
-            await SocketAbstraction.SendAsync(socket, Encoding.UTF8.GetBytes(clientVersion + "\x0D\x0A"), cancellationToken).ConfigureAwait(false);
-#else
-            SocketAbstraction.Send(socket, Encoding.UTF8.GetBytes(clientVersion + "\x0D\x0A"));
-#endif // NET6_0_OR_GREATER
+            _ = await socket.SendAsync(Encoding.UTF8.GetBytes(clientVersion + "\x0D\x0A"), SocketFlags.None, cancellationToken).ConfigureAwait(false);
 
             var bytesReceived = new List<byte>();
 

src/Renci.SshNet/Connection/Socks4Connector.cs

@@ -3,7 +3,6 @@
 using System.Net.Sockets;
 using System.Text;
 
-using Renci.SshNet.Abstractions;
 using Renci.SshNet.Common;
 
 namespace Renci.SshNet.Connection
@@ -29,7 +28,7 @@ public Socks4Connector(ISocketFactory socketFactory)
         protected override void HandleProxyConnect(IConnectionInfo connectionInfo, Socket socket)
         {
             var connectionRequest = CreateSocks4ConnectionRequest(connectionInfo.Host, (ushort)connectionInfo.Port, connectionInfo.ProxyUsername);
-            SocketAbstraction.Send(socket, connectionRequest);
+            _ = socket.Send(connectionRequest);
 
             // Read reply version
             if (SocketReadByte(socket, connectionInfo.Timeout) != 0x00)

src/Renci.SshNet/Connection/Socks5Connector.cs

@@ -41,7 +41,7 @@ protected override void HandleProxyConnect(IConnectionInfo connectionInfo, Socke
                     // Username/Password authentication
                     0x02
                 };
-            SocketAbstraction.Send(socket, greeting);
+            _ = socket.Send(greeting);
 
             var socksVersion = SocketReadByte(socket);
             if (socksVersion != 0x05)
@@ -60,7 +60,7 @@ protected override void HandleProxyConnect(IConnectionInfo connectionInfo, Socke
                     var authenticationRequest = CreateSocks5UserNameAndPasswordAuthenticationRequest(connectionInfo.ProxyUsername, connectionInfo.ProxyPassword);
 
                     // Send authentication request
-                    SocketAbstraction.Send(socket, authenticationRequest);
+                    _ = socket.Send(authenticationRequest);
 
                     // Read authentication result
                     var authenticationResult = SocketAbstraction.Read(socket, 2, connectionInfo.Timeout);
@@ -83,7 +83,7 @@ protected override void HandleProxyConnect(IConnectionInfo connectionInfo, Socke
             }
 
             var connectionRequest = CreateSocks5ConnectionRequest(connectionInfo.Host, (ushort) connectionInfo.Port);
-            SocketAbstraction.Send(socket, connectionRequest);
+            _ = socket.Send(connectionRequest);
 
             // Read Server SOCKS5 version
             if (SocketReadByte(socket) != 5)

src/Renci.SshNet/ForwardedPortDynamic.cs

@@ -508,8 +508,8 @@ private bool HandleSocks4(Socket socket, IChannelDirectTcpip channel, TimeSpan t
             if (channel.IsOpen)
             {
                 SocketAbstraction.SendByte(socket, 0x5a);
-                SocketAbstraction.Send(socket, portBuffer, 0, portBuffer.Length);
-                SocketAbstraction.Send(socket, ipBuffer, 0, ipBuffer.Length);
+                _ = socket.Send(portBuffer);
+                _ = socket.Send(ipBuffer);
                 return true;
             }
 
@@ -538,12 +538,12 @@ private bool HandleSocks5(Socket socket, IChannelDirectTcpip channel, TimeSpan t
             {
                 // no user authentication is one of the authentication methods supported
                 // by the SOCKS client
-                SocketAbstraction.Send(socket, new byte[] { 0x05, 0x00 }, 0, 2);
+                _ = socket.Send([0x05, 0x00]);
             }
             else
             {
                 // the SOCKS client requires authentication, which we currently do not support
-                SocketAbstraction.Send(socket, new byte[] { 0x05, 0xFF }, 0, 2);
+                _ = socket.Send([0x05, 0xFF]);
 
                 // we continue business as usual but expect the client to close the connection
                 // so one of the subsequent reads should return -1 signaling that the client
@@ -610,7 +610,7 @@ private bool HandleSocks5(Socket socket, IChannelDirectTcpip channel, TimeSpan t
 
             var socksReply = CreateSocks5Reply(channel.IsOpen);
 
-            SocketAbstraction.Send(socket, socksReply, 0, socksReply.Length);
+            _ = socket.Send(socksReply);
 
             return true;
         }

src/Renci.SshNet/Session.cs

@@ -1160,7 +1160,7 @@ private void SendPacket(byte[] packet, int offset, int length)
                     throw new SshConnectionException("Client not connected.");
                 }
 
-                SocketAbstraction.Send(_socket, packet, offset, length);
+                _ = _socket.Send(packet, offset, length, SocketFlags.None);
             }
             finally
             {