Imported Upstream version 6.0.0.172

Former-commit-id: f3cc9b82f3e5bd8f0fd3ebc098f789556b44e9cd

mcs/class/System/System.Net.Sockets/Socket.cs

@@ -939,7 +939,7 @@ namespace System.Net.Sockets
 				throw new ArgumentNullException("e");
 
 			if (e.in_progress != 0 && e.LastOperation == SocketAsyncOperation.Connect)
-				e.current_socket.Close();
+				e.current_socket?.Close ();
 		}
 
 		static AsyncCallback ConnectAsyncCallback = new AsyncCallback (ares => {
@@ -1391,6 +1391,8 @@ namespace System.Net.Sockets
 			return ret;
 		}
 
+		public int Receive (Span<byte> buffer) => Receive (buffer, SocketFlags.None);
+
 		public bool ReceiveAsync (SocketAsyncEventArgs e)
 		{
 			// NO check is made whether e != null in MS.NET (NRE is thrown in such case)
@@ -1882,6 +1884,8 @@ namespace System.Net.Sockets
 			return Send (buffer.ToArray(), socketFlags);
 		}
 
+		public int Send (ReadOnlySpan<byte> buffer) => Send (buffer, SocketFlags.None);
+
 		public bool SendAsync (SocketAsyncEventArgs e)
 		{
 			// NO check is made whether e != null in MS.NET (NRE is thrown in such case)
@@ -2604,14 +2608,26 @@ namespace System.Net.Sockets
 
 		public void Shutdown (SocketShutdown how)
 		{
+			const int enotconn = 10057;
+
 			ThrowIfDisposedAndClosed ();
 
 			if (!is_connected)
-				throw new SocketException (10057); // Not connected
+				throw new SocketException (enotconn); // Not connected
 
 			int error;
 			Shutdown_internal (m_Handle, how, out error);
 
+			if (error == enotconn) {
+				// POSIX requires this error to be returned from shutdown in some cases,
+				//  even if the socket is actually connected.
+				// We have already checked is_connected so it isn't meaningful or useful for
+				//  us to throw if the OS says the socket was already closed when we tried to
+				//  shut it down.
+				// See https://bugs.freebsd.org/bugzilla/show_bug.cgi?id=227259
+				return;
+			}
+
 			if (error != 0)
 				throw new SocketException (error);
 		}