Merge pull request #2274 from esdrubal/udpclientreceive
[mono.git] / mcs / class / System / System.Net.Sockets / Socket.cs
index fd67393e0d614358497abe3ad00cf374e055cb3f..8d48b675ae8cf9ed8a03cab67569bb1c49d9033d 100644 (file)
@@ -6,6 +6,7 @@
 //     Gonzalo Paniagua Javier (gonzalo@ximian.com)
 //     Sridhar Kulkarni (sridharkulkarni@gmail.com)
 //     Brian Nickel (brian.nickel@gmail.com)
+//     Ludovic Henry (ludovic@xamarin.com)
 //
 // Copyright (C) 2001, 2002 Phillip Pearson and Ximian, Inc.
 //    http://www.myelin.co.nz
@@ -69,13 +70,13 @@ namespace System.Net.Sockets
 
                int linger_timeout;
 
-               /* the field "safe_handle" is looked up by name by the runtime */
-               SafeSocketHandle safe_handle;
-
                AddressFamily address_family;
                SocketType socket_type;
                ProtocolType protocol_type;
 
+               /* the field "safe_handle" is looked up by name by the runtime */
+               internal SafeSocketHandle safe_handle;
+
                /*
                 * This EndPoint is used when creating new endpoints. Because
                 * there are many types of EndPoints possible,
@@ -85,8 +86,8 @@ namespace System.Net.Sockets
                 */
                internal EndPoint seed_endpoint = null;
 
-               internal Queue readQ = new Queue (2);
-               internal Queue writeQ = new Queue (2);
+               internal Queue<KeyValuePair<IntPtr, IOSelectorJob>> readQ = new Queue<KeyValuePair<IntPtr, IOSelectorJob>> (2);
+               internal Queue<KeyValuePair<IntPtr, IOSelectorJob>> writeQ = new Queue<KeyValuePair<IntPtr, IOSelectorJob>> (2);
 
                internal bool is_blocking = true;
                internal bool is_bound;
@@ -155,10 +156,16 @@ namespace System.Net.Sockets
                        }
                }
 
-               [MonoTODO ("Currently hardcoded to IPv4. Ideally, support v4/v6 dual-stack.")]
+               //
+               // This constructor is used by servers that want to listen for instance on both
+               // ipv4 and ipv6.   Mono has historically done that if you use InterNetworkV6 (at
+               // least on Unix), because that is the default behavior unless the IPV6_V6ONLY
+               // option is explicitly set by using setsockopt (sock, IPPROTO_IPV6, IPV6_ONLY)
+               //
                public Socket (SocketType socketType, ProtocolType protocolType)
-                       : this (AddressFamily.InterNetwork, socketType, protocolType)
+                       : this (AddressFamily.InterNetworkV6, socketType, protocolType)
                {
+                       DualMode = true;
                }
                
                public Socket(AddressFamily addressFamily, SocketType socketType, ProtocolType protocolType)
@@ -194,11 +201,9 @@ namespace System.Net.Sockets
                        this.address_family = addressFamily;
                        this.socket_type = socketType;
                        this.protocol_type = protocolType;
-                       
-                       int error;
-                       var handle = Socket_internal (addressFamily, socketType, protocolType, out error);
 
-                       this.safe_handle = new SafeSocketHandle (handle, true);
+                       int error;
+                       this.safe_handle = new SafeSocketHandle (Socket_internal (addressFamily, socketType, protocolType, out error), true);
 
                        if (error != 0)
                                throw new SocketException (error);
@@ -274,6 +279,7 @@ namespace System.Net.Sockets
 
 #region Properties
 
+               [ObsoleteAttribute ("Use OSSupportsIPv4 instead")]
                public static bool SupportsIPv4 {
                        get { return ipv4_supported == 1; }
                }
@@ -287,6 +293,19 @@ namespace System.Net.Sockets
                public static bool OSSupportsIPv4 {
                        get { return ipv4_supported == 1; }
                }
+#else
+               public static bool OSSupportsIPv4 {
+                       get {
+                               NetworkInterface[] nics = NetworkInterface.GetAllNetworkInterfaces ();
+
+                               foreach (NetworkInterface adapter in nics) {
+                                       if (adapter.Supports (NetworkInterfaceComponent.IPv4))
+                                               return true;
+                               }
+
+                               return false;
+                       }
+               }
 #endif
 
 #if NET_2_1
@@ -465,6 +484,27 @@ namespace System.Net.Sockets
                        }
                }
 
+               public bool DualMode {
+                       get {
+                               if (AddressFamily != AddressFamily.InterNetworkV6) 
+                                       throw new NotSupportedException("This protocol version is not supported");
+
+                               return ((int)GetSocketOption(SocketOptionLevel.IPv6, SocketOptionName.IPv6Only) == 0);
+                       }
+                       set {
+                               if (AddressFamily != AddressFamily.InterNetworkV6) 
+                                       throw new NotSupportedException("This protocol version is not supported");
+
+                               SetSocketOption(SocketOptionLevel.IPv6, SocketOptionName.IPv6Only, value ? 0 : 1);
+                       }
+               }
+
+               private bool IsDualMode {
+                       get {
+                               return AddressFamily == AddressFamily.InterNetworkV6 && DualMode;
+                       }
+               }
+
                [MonoTODO ("This doesn't do anything on Mono yet")]
                public bool UseOnlyOverlappedIO {
                        get { return use_overlapped_io; }
@@ -799,6 +839,48 @@ namespace System.Net.Sockets
 
 #endregion
 
+#region Poll
+
+               public bool Poll (int time_us, SelectMode mode)
+               {
+                       ThrowIfDisposedAndClosed ();
+
+                       if (mode != SelectMode.SelectRead && mode != SelectMode.SelectWrite && mode != SelectMode.SelectError)
+                               throw new NotSupportedException ("'mode' parameter is not valid.");
+
+                       int error;
+                       bool result = Poll_internal (safe_handle, mode, time_us, out error);
+
+                       if (error != 0)
+                               throw new SocketException (error);
+
+                       if (mode == SelectMode.SelectWrite && result && !is_connected) {
+                               /* Update the is_connected state; for non-blocking Connect()
+                                * this is when we can find out that the connect succeeded. */
+                               if ((int) GetSocketOption (SocketOptionLevel.Socket, SocketOptionName.Error) == 0)
+                                       is_connected = true;
+                       }
+
+                       return result;
+               }
+
+               static bool Poll_internal (SafeSocketHandle safeHandle, SelectMode mode, int timeout, out int error)
+               {
+                       bool release = false;
+                       try {
+                               safeHandle.DangerousAddRef (ref release);
+                               return Poll_internal (safeHandle.DangerousGetHandle (), mode, timeout, out error);
+                       } finally {
+                               if (release)
+                                       safeHandle.DangerousRelease ();
+                       }
+               }
+
+               [MethodImplAttribute(MethodImplOptions.InternalCall)]
+               extern static bool Poll_internal (IntPtr socket, SelectMode mode, int timeout, out int error);
+
+#endregion
+
 #region Accept
 
                public Socket Accept()
@@ -867,23 +949,32 @@ namespace System.Net.Sockets
                                        throw new InvalidOperationException ("AcceptSocket: The socket must not be bound or connected.");
                        }
 
-                       e.curSocket = this;
-                       e.Worker.Init (this, e, SocketOperation.Accept);
-
-                       SocketAsyncResult sockares = e.Worker.result;
-
-                       int count;
-                       lock (readQ) {
-                               readQ.Enqueue (e.Worker);
-                               count = readQ.Count;
-                       }
+                       InitSocketAsyncEventArgs (e, AcceptAsyncCallback, e, SocketOperation.Accept);
 
-                       if (count == 1)
-                               socket_pool_queue (SocketAsyncWorker.Dispatcher, sockares);
+                       QueueIOSelectorJob (readQ, e.socket_async_result.Handle, new IOSelectorJob (IOOperation.Read, BeginAcceptCallback, e.socket_async_result));
 
                        return true;
                }
 
+               static AsyncCallback AcceptAsyncCallback = new AsyncCallback (ares => {
+                       SocketAsyncEventArgs e = (SocketAsyncEventArgs) ((SocketAsyncResult) ares).AsyncState;
+
+                       if (Interlocked.Exchange (ref e.in_progress, 0) != 1)
+                               throw new InvalidOperationException ("No operation in progress");
+
+                       try {
+                               e.AcceptSocket = e.current_socket.EndAccept (ares);
+                       } catch (SocketException ex) {
+                               e.SocketError = ex.SocketErrorCode;
+                       } catch (ObjectDisposedException) {
+                               e.SocketError = SocketError.OperationAborted;
+                       } finally {
+                               if (e.AcceptSocket == null)
+                                       e.AcceptSocket = new Socket (e.current_socket.AddressFamily, e.current_socket.SocketType, e.current_socket.ProtocolType, null);
+                               e.Complete ();
+                       }
+               });
+
                public IAsyncResult BeginAccept(AsyncCallback callback, object state)
                {
                        ThrowIfDisposedAndClosed ();
@@ -891,20 +982,27 @@ namespace System.Net.Sockets
                        if (!is_bound || !is_listening)
                                throw new InvalidOperationException ();
 
-                       SocketAsyncResult sockares = new SocketAsyncResult (this, state, callback, SocketOperation.Accept);
+                       SocketAsyncResult sockares = new SocketAsyncResult (this, callback, state, SocketOperation.Accept);
 
-                       int count;
-                       lock (readQ) {
-                               readQ.Enqueue (sockares.Worker);
-                               count = readQ.Count;
-                       }
-
-                       if (count == 1)
-                               socket_pool_queue (SocketAsyncWorker.Dispatcher, sockares);
+                       QueueIOSelectorJob (readQ, sockares.Handle, new IOSelectorJob (IOOperation.Read, BeginAcceptCallback, sockares));
 
                        return sockares;
                }
 
+               static IOAsyncCallback BeginAcceptCallback = new IOAsyncCallback (ares => {
+                       SocketAsyncResult sockares = (SocketAsyncResult) ares;
+                       Socket socket = null;
+
+                       try {
+                               socket = sockares.socket.Accept ();
+                       } catch (Exception e) {
+                               sockares.Complete (e);
+                               return;
+                       }
+
+                       sockares.Complete (socket);
+               });
+
                public IAsyncResult BeginAccept (int receiveSize, AsyncCallback callback, object state)
                {
                        ThrowIfDisposedAndClosed ();
@@ -912,21 +1010,14 @@ namespace System.Net.Sockets
                        if (receiveSize < 0)
                                throw new ArgumentOutOfRangeException ("receiveSize", "receiveSize is less than zero");
 
-                       SocketAsyncResult sockares = new SocketAsyncResult (this, state, callback, SocketOperation.AcceptReceive) {
+                       SocketAsyncResult sockares = new SocketAsyncResult (this, callback, state, SocketOperation.AcceptReceive) {
                                Buffer = new byte [receiveSize],
                                Offset = 0,
                                Size = receiveSize,
                                SockFlags = SocketFlags.None,
                        };
 
-                       int count;
-                       lock (readQ) {
-                               readQ.Enqueue (sockares.Worker);
-                               count = readQ.Count;
-                       }
-
-                       if (count == 1)
-                               socket_pool_queue (SocketAsyncWorker.Dispatcher, sockares);
+                       QueueIOSelectorJob (readQ, sockares.Handle, new IOSelectorJob (IOOperation.Read, BeginAcceptReceiveCallback, sockares));
 
                        return sockares;
                }
@@ -952,8 +1043,8 @@ namespace System.Net.Sockets
                                if (acceptSocket.ProtocolType != ProtocolType.Tcp)
                                        throw new SocketException ((int)SocketError.InvalidArgument);
                        }
-                       
-                       SocketAsyncResult sockares = new SocketAsyncResult (this, state, callback, SocketOperation.AcceptReceive) {
+
+                       SocketAsyncResult sockares = new SocketAsyncResult (this, callback, state, SocketOperation.AcceptReceive) {
                                Buffer = new byte [receiveSize],
                                Offset = 0,
                                Size = receiveSize,
@@ -961,18 +1052,46 @@ namespace System.Net.Sockets
                                AcceptSocket = acceptSocket,
                        };
 
-                       int count;
-                       lock (readQ) {
-                               readQ.Enqueue (sockares.Worker);
-                               count = readQ.Count;
-                       }
-
-                       if (count == 1)
-                               socket_pool_queue (SocketAsyncWorker.Dispatcher, sockares);
+                       QueueIOSelectorJob (readQ, sockares.Handle, new IOSelectorJob (IOOperation.Read, BeginAcceptReceiveCallback, sockares));
 
                        return sockares;
                }
 
+               static IOAsyncCallback BeginAcceptReceiveCallback = new IOAsyncCallback (ares => {
+                       SocketAsyncResult sockares = (SocketAsyncResult) ares;
+                       Socket acc_socket = null;
+
+                       try {
+                               if (sockares.AcceptSocket == null) {
+                                       acc_socket = sockares.socket.Accept ();
+                               } else {
+                                       acc_socket = sockares.AcceptSocket;
+                                       sockares.socket.Accept (acc_socket);
+                               }
+                       } catch (Exception e) {
+                               sockares.Complete (e);
+                               return;
+                       }
+
+                       /* It seems the MS runtime special-cases 0-length requested receive data.  See bug 464201. */
+                       int total = 0;
+                       if (sockares.Size > 0) {
+                               try {
+                                       SocketError error;
+                                       total = acc_socket.Receive_nochecks (sockares.Buffer, sockares.Offset, sockares.Size, sockares.SockFlags, out error);
+                                       if (error != 0) {
+                                               sockares.Complete (new SocketException ((int) error));
+                                               return;
+                                       }
+                               } catch (Exception e) {
+                                       sockares.Complete (e);
+                                       return;
+                               }
+                       }
+
+                       sockares.Complete (acc_socket, total);
+               });
+
                public Socket EndAccept (IAsyncResult result)
                {
                        int bytes;
@@ -1000,7 +1119,7 @@ namespace System.Net.Sockets
                        buffer = sockares.Buffer;
                        bytesTransferred = sockares.Total;
 
-                       return sockares.Socket;
+                       return sockares.AcceptedSocket;
                }
 
                static SafeSocketHandle Accept_internal (SafeSocketHandle safeHandle, out int error, bool blocking)
@@ -1020,6 +1139,79 @@ namespace System.Net.Sockets
 
 #endregion
 
+#region Bind
+
+               public void Bind (EndPoint local_end)
+               {
+                       ThrowIfDisposedAndClosed ();
+
+                       if (local_end == null)
+                               throw new ArgumentNullException("local_end");
+
+                       int error;
+                       Bind_internal (safe_handle, local_end.Serialize(), out error);
+
+                       if (error != 0)
+                               throw new SocketException (error);
+                       if (error == 0)
+                               is_bound = true;
+
+                       seed_endpoint = local_end;
+               }
+
+               private static void Bind_internal (SafeSocketHandle safeHandle, SocketAddress sa, out int error)
+               {
+                       bool release = false;
+                       try {
+                               safeHandle.DangerousAddRef (ref release);
+                               Bind_internal (safeHandle.DangerousGetHandle (), sa, out error);
+                       } finally {
+                               if (release)
+                                       safeHandle.DangerousRelease ();
+                       }
+               }
+
+               // Creates a new system socket, returning the handle
+               [MethodImplAttribute(MethodImplOptions.InternalCall)]
+               private extern static void Bind_internal(IntPtr sock, SocketAddress sa, out int error);
+
+#endregion
+
+#region Listen
+
+               public void Listen (int backlog)
+               {
+                       ThrowIfDisposedAndClosed ();
+
+                       if (!is_bound)
+                               throw new SocketException ((int) SocketError.InvalidArgument);
+
+                       int error;
+                       Listen_internal(safe_handle, backlog, out error);
+
+                       if (error != 0)
+                               throw new SocketException (error);
+
+                       is_listening = true;
+               }
+
+               static void Listen_internal (SafeSocketHandle safeHandle, int backlog, out int error)
+               {
+                       bool release = false;
+                       try {
+                               safeHandle.DangerousAddRef (ref release);
+                               Listen_internal (safeHandle.DangerousGetHandle (), backlog, out error);
+                       } finally {
+                               if (release)
+                                       safeHandle.DangerousRelease ();
+                       }
+               }
+
+               [MethodImplAttribute(MethodImplOptions.InternalCall)]
+               extern static void Listen_internal (IntPtr sock, int backlog, out int error);
+
+#endregion
+
 #region Connect
 
                public void Connect (IPAddress address, int port)
@@ -1121,37 +1313,51 @@ namespace System.Net.Sockets
                        if (e.RemoteEndPoint == null)
                                throw new ArgumentNullException ("remoteEP");
 
-                       e.curSocket = this;
-                       e.Worker.Init (this, e, SocketOperation.Connect);
-
-                       SocketAsyncResult result = e.Worker.result;
+                       InitSocketAsyncEventArgs (e, ConnectAsyncCallback, e, SocketOperation.Connect);
 
                        try {
                                IPAddress [] addresses;
-                               IAsyncResult ares;
+                               SocketAsyncResult ares;
 
                                if (!GetCheckedIPs (e, out addresses)) {
-                                       result.EndPoint = e.RemoteEndPoint;
-                                       ares = BeginConnect (e.RemoteEndPoint, SocketAsyncEventArgs.Dispatcher, e);
+                                       e.socket_async_result.EndPoint = e.RemoteEndPoint;
+                                       ares = (SocketAsyncResult) BeginConnect (e.RemoteEndPoint, ConnectAsyncCallback, e);
                                } else {
                                        DnsEndPoint dep = (e.RemoteEndPoint as DnsEndPoint);
-                                       result.Addresses = addresses;
-                                       result.Port = dep.Port;
-                                       ares = BeginConnect (addresses, dep.Port, SocketAsyncEventArgs.Dispatcher, e);
+                                       e.socket_async_result.Addresses = addresses;
+                                       e.socket_async_result.Port = dep.Port;
+                                       ares = (SocketAsyncResult) BeginConnect (addresses, dep.Port, ConnectAsyncCallback, e);
                                }
 
                                if (ares.IsCompleted && ares.CompletedSynchronously) {
-                                       ((SocketAsyncResult) ares).CheckIfThrowDelayedException ();
+                                       ares.CheckIfThrowDelayedException ();
                                        return false;
                                }
                        } catch (Exception exc) {
-                               result.Complete (exc, true);
+                               e.socket_async_result.Complete (exc, true);
                                return false;
                        }
 
                        return true;
                }
 
+               static AsyncCallback ConnectAsyncCallback = new AsyncCallback (ares => {
+                       SocketAsyncEventArgs e = (SocketAsyncEventArgs) ((SocketAsyncResult) ares).AsyncState;
+
+                       if (Interlocked.Exchange (ref e.in_progress, 0) != 1)
+                               throw new InvalidOperationException ("No operation in progress");
+
+                       try {
+                               e.current_socket.EndConnect (ares);
+                       } catch (SocketException se) {
+                               e.SocketError = se.SocketErrorCode;
+                       } catch (ObjectDisposedException) {
+                               e.SocketError = SocketError.OperationAborted;
+                       } finally {
+                               e.Complete ();
+                       }
+               });
+
                public IAsyncResult BeginConnect (IPAddress address, int port, AsyncCallback callback, object state)
                {
                        ThrowIfDisposedAndClosed ();
@@ -1191,7 +1397,7 @@ namespace System.Net.Sockets
                        if (end_point == null)
                                throw new ArgumentNullException ("end_point");
 
-                       SocketAsyncResult sockares = new SocketAsyncResult (this, state, callback, SocketOperation.Connect) {
+                       SocketAsyncResult sockares = new SocketAsyncResult (this, callback, state, SocketOperation.Connect) {
                                EndPoint = end_point,
                        };
 
@@ -1212,8 +1418,7 @@ namespace System.Net.Sockets
                                // an error. Better to just close the socket and move on.
                                connect_in_progress = false;
                                safe_handle.Dispose ();
-                               var handle = Socket_internal (address_family, socket_type, protocol_type, out error);
-                               safe_handle = new SafeSocketHandle (handle, true);
+                               safe_handle = new SafeSocketHandle (Socket_internal (address_family, socket_type, protocol_type, out error), true);
                                if (error != 0)
                                        throw new SocketException (error);
                        }
@@ -1246,7 +1451,7 @@ namespace System.Net.Sockets
                        is_bound = false;
                        connect_in_progress = true;
 
-                       socket_pool_queue (SocketAsyncWorker.Dispatcher, sockares);
+                       IOSelector.Add (sockares.Handle, new IOSelectorJob (IOOperation.Write, BeginConnectCallback, sockares));
 
                        return sockares;
                }
@@ -1266,7 +1471,7 @@ namespace System.Net.Sockets
                        if (is_listening)
                                throw new InvalidOperationException ();
 
-                       SocketAsyncResult sockares = new SocketAsyncResult (this, state, callback, SocketOperation.Connect) {
+                       SocketAsyncResult sockares = new SocketAsyncResult (this, callback, state, SocketOperation.Connect) {
                                Addresses = addresses,
                                Port = port,
                        };
@@ -1278,17 +1483,21 @@ namespace System.Net.Sockets
 
                internal IAsyncResult BeginMConnect (SocketAsyncResult sockares)
                {
-                       IAsyncResult ares = null;
+                       SocketAsyncResult ares = null;
                        Exception exc = null;
+                       AsyncCallback callback;
 
                        for (int i = sockares.CurrentAddress; i < sockares.Addresses.Length; i++) {
                                try {
                                        sockares.CurrentAddress++;
 
-                                       ares = BeginConnect (new IPEndPoint (sockares.Addresses [i], sockares.Port), null, sockares);
+                                       ares = (SocketAsyncResult) BeginConnect (new IPEndPoint (sockares.Addresses [i], sockares.Port), null, sockares);
                                        if (ares.IsCompleted && ares.CompletedSynchronously) {
-                                               ((SocketAsyncResult) ares).CheckIfThrowDelayedException ();
-                                               sockares.DoMConnectCallback ();
+                                               ares.CheckIfThrowDelayedException ();
+
+                                               callback = ares.AsyncCallback;
+                                               if (callback != null)
+                                                       ThreadPool.UnsafeQueueUserWorkItem (_ => callback (ares), null);
                                        }
 
                                        break;
@@ -1304,6 +1513,57 @@ namespace System.Net.Sockets
                        return sockares;
                }
 
+               static IOAsyncCallback BeginConnectCallback = new IOAsyncCallback (ares => {
+                       SocketAsyncResult sockares = (SocketAsyncResult) ares;
+
+                       if (sockares.EndPoint == null) {
+                               sockares.Complete (new SocketException ((int)SocketError.AddressNotAvailable));
+                               return;
+                       }
+
+                       SocketAsyncResult mconnect = sockares.AsyncState as SocketAsyncResult;
+                       bool is_mconnect = mconnect != null && mconnect.Addresses != null;
+
+                       try {
+                               EndPoint ep = sockares.EndPoint;
+                               int error_code = (int) sockares.socket.GetSocketOption (SocketOptionLevel.Socket, SocketOptionName.Error);
+
+                               if (error_code == 0) {
+                                       if (is_mconnect)
+                                               sockares = mconnect;
+
+                                       sockares.socket.seed_endpoint = ep;
+                                       sockares.socket.is_connected = true;
+                                       sockares.socket.is_bound = true;
+                                       sockares.socket.connect_in_progress = false;
+                                       sockares.error = 0;
+                                       sockares.Complete ();
+                                       return;
+                               }
+
+                               if (!is_mconnect) {
+                                       sockares.socket.connect_in_progress = false;
+                                       sockares.Complete (new SocketException (error_code));
+                                       return;
+                               }
+
+                               if (mconnect.CurrentAddress >= mconnect.Addresses.Length) {
+                                       mconnect.Complete (new SocketException (error_code));
+                                       return;
+                               }
+
+                               mconnect.socket.BeginMConnect (mconnect);
+                       } catch (Exception e) {
+                               sockares.socket.connect_in_progress = false;
+
+                               if (is_mconnect)
+                                       sockares = mconnect;
+
+                               sockares.Complete (e);
+                               return;
+                       }
+               });
+
                public void EndConnect (IAsyncResult result)
                {
                        ThrowIfDisposedAndClosed ();
@@ -1384,30 +1644,56 @@ namespace System.Net.Sockets
 
                        ThrowIfDisposedAndClosed ();
 
-                       e.curSocket = this;
-                       e.Worker.Init (this, e, SocketOperation.Disconnect);
-
-                       SocketAsyncResult sockares = e.Worker.result;
+                       InitSocketAsyncEventArgs (e, DisconnectAsyncCallback, e, SocketOperation.Disconnect);
 
-                       socket_pool_queue (SocketAsyncWorker.Dispatcher, sockares);
+                       IOSelector.Add (e.socket_async_result.Handle, new IOSelectorJob (IOOperation.Write, BeginDisconnectCallback, e.socket_async_result));
 
                        return true;
                }
 
+               static AsyncCallback DisconnectAsyncCallback = new AsyncCallback (ares => {
+                       SocketAsyncEventArgs e = (SocketAsyncEventArgs) ((SocketAsyncResult) ares).AsyncState;
+
+                       if (Interlocked.Exchange (ref e.in_progress, 0) != 1)
+                               throw new InvalidOperationException ("No operation in progress");
+
+                       try {
+                               e.current_socket.EndDisconnect (ares);
+                       } catch (SocketException ex) {
+                               e.SocketError = ex.SocketErrorCode;
+                       } catch (ObjectDisposedException) {
+                               e.SocketError = SocketError.OperationAborted;
+                       } finally {
+                               e.Complete ();
+                       }
+               });
 
                public IAsyncResult BeginDisconnect (bool reuseSocket, AsyncCallback callback, object state)
                {
                        ThrowIfDisposedAndClosed ();
 
-                       SocketAsyncResult sockares = new SocketAsyncResult (this, state, callback, SocketOperation.Disconnect) {
+                       SocketAsyncResult sockares = new SocketAsyncResult (this, callback, state, SocketOperation.Disconnect) {
                                ReuseSocket = reuseSocket,
                        };
 
-                       socket_pool_queue (SocketAsyncWorker.Dispatcher, sockares);
+                       IOSelector.Add (sockares.Handle, new IOSelectorJob (IOOperation.Write, BeginDisconnectCallback, sockares));
 
                        return sockares;
                }
 
+               static IOAsyncCallback BeginDisconnectCallback = new IOAsyncCallback (ares => {
+                       SocketAsyncResult sockares = (SocketAsyncResult) ares;
+
+                       try {
+                               sockares.socket.Disconnect (sockares.ReuseSocket);
+                       } catch (Exception e) {
+                               sockares.Complete (e);
+                               return;
+                       }
+
+                       sockares.Complete ();
+               });
+
                public void EndDisconnect (IAsyncResult asyncResult)
                {
                        ThrowIfDisposedAndClosed ();
@@ -1585,55 +1871,56 @@ namespace System.Net.Sockets
                        if (e.Buffer == null && e.BufferList == null)
                                throw new NullReferenceException ("Either e.Buffer or e.BufferList must be valid buffers.");
 
-                       e.curSocket = this;
-                       e.Worker.Init (this, e, e.Buffer != null ? SocketOperation.Receive : SocketOperation.ReceiveGeneric);
+                       if (e.Buffer == null) {
+                               InitSocketAsyncEventArgs (e, ReceiveAsyncCallback, e, SocketOperation.ReceiveGeneric);
 
-                       SocketAsyncResult sockares = e.Worker.result;
-                       sockares.SockFlags = e.SocketFlags;
+                               e.socket_async_result.Buffers = e.BufferList;
 
-                       if (e.Buffer != null) {
-                               sockares.Buffer = e.Buffer;
-                               sockares.Offset = e.Offset;
-                               sockares.Size = e.Count;
+                               QueueIOSelectorJob (readQ, e.socket_async_result.Handle, new IOSelectorJob (IOOperation.Read, BeginReceiveGenericCallback, e.socket_async_result));
                        } else {
-                               sockares.Buffers = e.BufferList;
-                       }
+                               InitSocketAsyncEventArgs (e, ReceiveAsyncCallback, e, SocketOperation.Receive);
 
-                       int count;
-                       lock (readQ) {
-                               readQ.Enqueue (e.Worker);
-                               count = readQ.Count;
-                       }
+                               e.socket_async_result.Buffer = e.Buffer;
+                               e.socket_async_result.Offset = e.Offset;
+                               e.socket_async_result.Size = e.Count;
 
-                       if (count == 1) {
-                               // Receive takes care of ReceiveGeneric
-                               socket_pool_queue (SocketAsyncWorker.Dispatcher, sockares);
+                               QueueIOSelectorJob (readQ, e.socket_async_result.Handle, new IOSelectorJob (IOOperation.Read, BeginReceiveCallback, e.socket_async_result));
                        }
 
                        return true;
                }
 
+               static AsyncCallback ReceiveAsyncCallback = new AsyncCallback (ares => {
+                       SocketAsyncEventArgs e = (SocketAsyncEventArgs) ((SocketAsyncResult) ares).AsyncState;
+
+                       if (Interlocked.Exchange (ref e.in_progress, 0) != 1)
+                               throw new InvalidOperationException ("No operation in progress");
+
+                       try {
+                               e.BytesTransferred = e.current_socket.EndReceive (ares);
+                       } catch (SocketException se){
+                               e.SocketError = se.SocketErrorCode;
+                       } catch (ObjectDisposedException) {
+                               e.SocketError = SocketError.OperationAborted;
+                       } finally {
+                               e.Complete ();
+                       }
+               });
+
                public IAsyncResult BeginReceive (byte[] buffer, int offset, int size, SocketFlags socket_flags, AsyncCallback callback, object state)
                {
                        ThrowIfDisposedAndClosed ();
                        ThrowIfBufferNull (buffer);
                        ThrowIfBufferOutOfRange (buffer, offset, size);
 
-                       SocketAsyncResult sockares = new SocketAsyncResult (this, state, callback, SocketOperation.Receive) {
+                       SocketAsyncResult sockares = new SocketAsyncResult (this, callback, state, SocketOperation.Receive) {
                                Buffer = buffer,
                                Offset = offset,
                                Size = size,
                                SockFlags = socket_flags,
                        };
 
-                       int count;
-                       lock (readQ) {
-                               readQ.Enqueue (sockares.Worker);
-                               count = readQ.Count;
-                       }
-
-                       if (count == 1)
-                               socket_pool_queue (SocketAsyncWorker.Dispatcher, sockares);
+                       QueueIOSelectorJob (readQ, sockares.Handle, new IOSelectorJob (IOOperation.Read, BeginReceiveCallback, sockares));
 
                        return sockares;
                }
@@ -1647,6 +1934,20 @@ namespace System.Net.Sockets
                        return BeginReceive (buffer, offset, size, flags, callback, state);
                }
 
+               static IOAsyncCallback BeginReceiveCallback = new IOAsyncCallback (ares => {
+                       SocketAsyncResult sockares = (SocketAsyncResult) ares;
+                       int total = 0;
+
+                       try {
+                               total = Receive_internal (sockares.socket.safe_handle, sockares.Buffer, sockares.Offset, sockares.Size, sockares.SockFlags, out sockares.error);
+                       } catch (Exception e) {
+                               sockares.Complete (e);
+                               return;
+                       }
+
+                       sockares.Complete (total);
+               });
+
                [CLSCompliant (false)]
                public IAsyncResult BeginReceive (IList<ArraySegment<byte>> buffers, SocketFlags socketFlags, AsyncCallback callback, object state)
                {
@@ -1655,19 +1956,12 @@ namespace System.Net.Sockets
                        if (buffers == null)
                                throw new ArgumentNullException ("buffers");
 
-                       SocketAsyncResult sockares = new SocketAsyncResult (this, state, callback, SocketOperation.ReceiveGeneric) {
+                       SocketAsyncResult sockares = new SocketAsyncResult (this, callback, state, SocketOperation.ReceiveGeneric) {
                                Buffers = buffers,
                                SockFlags = socketFlags,
                        };
 
-                       int count;
-                       lock(readQ) {
-                               readQ.Enqueue (sockares.Worker);
-                               count = readQ.Count;
-                       }
-
-                       if (count == 1)
-                               socket_pool_queue (SocketAsyncWorker.Dispatcher, sockares);
+                       QueueIOSelectorJob (readQ, sockares.Handle, new IOSelectorJob (IOOperation.Read, BeginReceiveGenericCallback, sockares));
 
                        return sockares;
                }
@@ -1680,6 +1974,20 @@ namespace System.Net.Sockets
                        return BeginReceive (buffers, socketFlags, callback, state);
                }
 
+               static IOAsyncCallback BeginReceiveGenericCallback = new IOAsyncCallback (ares => {
+                       SocketAsyncResult sockares = (SocketAsyncResult) ares;
+                       int total = 0;
+
+                       try {
+                               total = sockares.socket.Receive (sockares.Buffers, sockares.SockFlags);
+                       } catch (Exception e) {
+                               sockares.Complete (e);
+                               return;
+                       }
+
+                       sockares.Complete (total);
+               });
+
                public int EndReceive (IAsyncResult result)
                {
                        SocketError error;
@@ -1711,7 +2019,7 @@ namespace System.Net.Sockets
                        return sockares.Total;
                }
 
-               internal int Receive_nochecks (byte [] buf, int offset, int size, SocketFlags flags, out SocketError error)
+               int Receive_nochecks (byte [] buf, int offset, int size, SocketFlags flags, out SocketError error)
                {
                        int nativeError;
                        int ret = Receive_internal (safe_handle, buf, offset, size, flags, out nativeError);
@@ -1761,24 +2069,16 @@ namespace System.Net.Sockets
                {
                        ThrowIfDisposedAndClosed ();
                        ThrowIfBufferNull (buffer);
-                       ThrowIfBufferOutOfRange (buffer, 0, buffer.Length);
-
-                       if (remoteEP == null)
-                               throw new ArgumentNullException ("remoteEP");
 
-                       return ReceiveFrom_nochecks (buffer, 0, buffer.Length, SocketFlags.None, ref remoteEP);
+                       return ReceiveFrom (buffer, 0, buffer.Length, SocketFlags.None, ref remoteEP);
                }
 
                public int ReceiveFrom (byte [] buffer, SocketFlags flags, ref EndPoint remoteEP)
                {
                        ThrowIfDisposedAndClosed ();
                        ThrowIfBufferNull (buffer);
-                       ThrowIfBufferOutOfRange (buffer, 0, buffer.Length);
-
-                       if (remoteEP == null)
-                               throw new ArgumentNullException ("remoteEP");
 
-                       return ReceiveFrom_nochecks (buffer, 0, buffer.Length, flags, ref remoteEP);
+                       return ReceiveFrom (buffer, 0, buffer.Length, flags, ref remoteEP);
                }
 
                public int ReceiveFrom (byte [] buffer, int size, SocketFlags flags, ref EndPoint remoteEP)
@@ -1787,10 +2087,7 @@ namespace System.Net.Sockets
                        ThrowIfBufferNull (buffer);
                        ThrowIfBufferOutOfRange (buffer, 0, size);
 
-                       if (remoteEP == null)
-                               throw new ArgumentNullException ("remoteEP");
-
-                       return ReceiveFrom_nochecks (buffer, 0, size, flags, ref remoteEP);
+                       return ReceiveFrom (buffer, 0, size, flags, ref remoteEP);
                }
 
                public int ReceiveFrom (byte [] buffer, int offset, int size, SocketFlags flags, ref EndPoint remoteEP)
@@ -1802,7 +2099,8 @@ namespace System.Net.Sockets
                        if (remoteEP == null)
                                throw new ArgumentNullException ("remoteEP");
 
-                       return ReceiveFrom_nochecks (buffer, offset, size, flags, ref remoteEP);
+                       int error;
+                       return ReceiveFrom_nochecks_exc (buffer, offset, size, flags, ref remoteEP, true, out error);
                }
 
                public bool ReceiveFromAsync (SocketAsyncEventArgs e)
@@ -1815,28 +2113,36 @@ namespace System.Net.Sockets
                        if (e.RemoteEndPoint == null)
                                throw new ArgumentNullException ("remoteEP", "Value cannot be null.");
 
-                       e.curSocket = this;
-                       e.Worker.Init (this, e, SocketOperation.ReceiveFrom);
+                       InitSocketAsyncEventArgs (e, ReceiveFromAsyncCallback, e, SocketOperation.ReceiveFrom);
 
-                       SocketAsyncResult sockares = e.Worker.result;
-                       sockares.Buffer = e.Buffer;
-                       sockares.Offset = e.Offset;
-                       sockares.Size = e.Count;
-                       sockares.EndPoint = e.RemoteEndPoint;
-                       sockares.SockFlags = e.SocketFlags;
-
-                       int count;
-                       lock (readQ) {
-                               readQ.Enqueue (e.Worker);
-                               count = readQ.Count;
-                       }
+                       e.socket_async_result.Buffer = e.Buffer;
+                       e.socket_async_result.Offset = e.Offset;
+                       e.socket_async_result.Size = e.Count;
+                       e.socket_async_result.EndPoint = e.RemoteEndPoint;
+                       e.socket_async_result.SockFlags = e.SocketFlags;
 
-                       if (count == 1)
-                               socket_pool_queue (SocketAsyncWorker.Dispatcher, sockares);
+                       QueueIOSelectorJob (readQ, e.socket_async_result.Handle, new IOSelectorJob (IOOperation.Read, BeginReceiveFromCallback, e.socket_async_result));
 
                        return true;
                }
 
+               static AsyncCallback ReceiveFromAsyncCallback = new AsyncCallback (ares => {
+                       SocketAsyncEventArgs e = (SocketAsyncEventArgs) ((SocketAsyncResult) ares).AsyncState;
+
+                       if (Interlocked.Exchange (ref e.in_progress, 0) != 1)
+                               throw new InvalidOperationException ("No operation in progress");
+
+                       try {
+                               e.BytesTransferred = e.current_socket.EndReceiveFrom (ares, ref e.remote_ep);
+                       } catch (SocketException ex) {
+                               e.SocketError = ex.SocketErrorCode;
+                       } catch (ObjectDisposedException) {
+                               e.SocketError = SocketError.OperationAborted;
+                       } finally {
+                               e.Complete ();
+                       }
+               });
+
                public IAsyncResult BeginReceiveFrom (byte[] buffer, int offset, int size, SocketFlags socket_flags, ref EndPoint remote_end, AsyncCallback callback, object state)
                {
                        ThrowIfDisposedAndClosed ();
@@ -1846,7 +2152,7 @@ namespace System.Net.Sockets
                        if (remote_end == null)
                                throw new ArgumentNullException ("remote_end");
 
-                       SocketAsyncResult sockares = new SocketAsyncResult (this, state, callback, SocketOperation.ReceiveFrom) {
+                       SocketAsyncResult sockares = new SocketAsyncResult (this, callback, state, SocketOperation.ReceiveFrom) {
                                Buffer = buffer,
                                Offset = offset,
                                Size = size,
@@ -1854,18 +2160,26 @@ namespace System.Net.Sockets
                                EndPoint = remote_end,
                        };
 
-                       int count;
-                       lock (readQ) {
-                               readQ.Enqueue (sockares.Worker);
-                               count = readQ.Count;
-                       }
-
-                       if (count == 1)
-                               socket_pool_queue (SocketAsyncWorker.Dispatcher, sockares);
+                       QueueIOSelectorJob (readQ, sockares.Handle, new IOSelectorJob (IOOperation.Read, BeginReceiveFromCallback, sockares));
 
                        return sockares;
                }
 
+               static IOAsyncCallback BeginReceiveFromCallback = new IOAsyncCallback (ares => {
+                       SocketAsyncResult sockares = (SocketAsyncResult) ares;
+                       int total = 0;
+
+                       try {
+                               int error;
+                               total = sockares.socket.ReceiveFrom_nochecks_exc (sockares.Buffer, sockares.Offset, sockares.Size, sockares.SockFlags, ref sockares.EndPoint, true, out error);
+                       } catch (Exception e) {
+                               sockares.Complete (e);
+                               return;
+                       }
+
+                       sockares.Complete (total);
+               });
+
                public int EndReceiveFrom(IAsyncResult result, ref EndPoint end_point)
                {
                        ThrowIfDisposedAndClosed ();
@@ -1885,12 +2199,6 @@ namespace System.Net.Sockets
                        return sockares.Total;
                }
 
-               internal int ReceiveFrom_nochecks (byte [] buf, int offset, int size, SocketFlags flags, ref EndPoint remote_end)
-               {
-                       int error;
-                       return ReceiveFrom_nochecks_exc (buf, offset, size, flags, ref remote_end, true, out error);
-               }
-
                internal int ReceiveFrom_nochecks_exc (byte [] buf, int offset, int size, SocketFlags flags, ref EndPoint remote_end, bool throwOnError, out int error)
                {
                        SocketAddress sockaddr = remote_end.Serialize();
@@ -1998,592 +2306,558 @@ namespace System.Net.Sockets
 
 #endregion
 
-               void CheckRange (byte[] buffer, int offset, int size)
+#region Send
+
+               public int Send (byte [] buffer)
                {
-                       if (offset < 0)
-                               throw new ArgumentOutOfRangeException ("offset", "offset must be >= 0");
-                       if (offset > buffer.Length)
-                               throw new ArgumentOutOfRangeException ("offset", "offset must be <= buffer.Length");
-                       if (size < 0)
-                               throw new ArgumentOutOfRangeException ("size", "size must be >= 0");
-                       if (size > buffer.Length - offset)
-                               throw new ArgumentOutOfRangeException ("size", "size must be <= buffer.Length - offset");
+                       ThrowIfDisposedAndClosed ();
+                       ThrowIfBufferNull (buffer);
+                       ThrowIfBufferOutOfRange (buffer, 0, buffer.Length);
+
+                       SocketError error;
+                       int ret = Send_nochecks (buffer, 0, buffer.Length, SocketFlags.None, out error);
+
+                       if (error != SocketError.Success)
+                               throw new SocketException ((int) error);
+
+                       return ret;
                }
 
+               public int Send (byte [] buffer, SocketFlags flags)
+               {
+                       ThrowIfDisposedAndClosed ();
+                       ThrowIfBufferNull (buffer);
+                       ThrowIfBufferOutOfRange (buffer, 0, buffer.Length);
+
+                       SocketError error;
+                       int ret = Send_nochecks (buffer, 0, buffer.Length, flags, out error);
+
+                       if (error != SocketError.Success)
+                               throw new SocketException ((int) error);
+
+                       return ret;
+               }
 
-               public IAsyncResult BeginSend (byte[] buffer, int offset, int size, SocketFlags socket_flags,
-                                              AsyncCallback callback, object state)
+               public int Send (byte [] buffer, int size, SocketFlags flags)
                {
-                       if (is_disposed && is_closed)
-                               throw new ObjectDisposedException (GetType ().ToString ());
+                       ThrowIfDisposedAndClosed ();
+                       ThrowIfBufferNull (buffer);
+                       ThrowIfBufferOutOfRange (buffer, 0, size);
 
-                       if (buffer == null)
-                               throw new ArgumentNullException ("buffer");
+                       SocketError error;
+                       int ret = Send_nochecks (buffer, 0, size, flags, out error);
 
-                       CheckRange (buffer, offset, size);
+                       if (error != SocketError.Success)
+                               throw new SocketException ((int) error);
 
-                       if (!is_connected)
-                               throw new SocketException ((int)SocketError.NotConnected);
+                       return ret;
+               }
 
-                       SocketAsyncResult req = new SocketAsyncResult (this, state, callback, SocketOperation.Send);
-                       req.Buffer = buffer;
-                       req.Offset = offset;
-                       req.Size = size;
-                       req.SockFlags = socket_flags;
-                       int count;
-                       lock (writeQ) {
-                               writeQ.Enqueue (req.Worker);
-                               count = writeQ.Count;
-                       }
-                       if (count == 1)
-                               socket_pool_queue (SocketAsyncWorker.Dispatcher, req);
-                       return req;
+               public int Send (byte [] buffer, int offset, int size, SocketFlags flags)
+               {
+                       ThrowIfDisposedAndClosed ();
+                       ThrowIfBufferNull (buffer);
+                       ThrowIfBufferOutOfRange (buffer, offset, size);
+
+                       SocketError error;
+                       int ret = Send_nochecks (buffer, offset, size, flags, out error);
+
+                       if (error != SocketError.Success)
+                               throw new SocketException ((int) error);
+
+                       return ret;
                }
 
-               public IAsyncResult BeginSend (byte[] buffer, int offset,
-                                              int size,
-                                              SocketFlags socketFlags,
-                                              out SocketError errorCode,
-                                              AsyncCallback callback,
-                                              object state)
+               public int Send (byte [] buffer, int offset, int size, SocketFlags flags, out SocketError error)
                {
-                       if (!is_connected) {
-                               errorCode = SocketError.NotConnected;
-                               throw new SocketException ((int)errorCode);
-                       }
-                       
-                       errorCode = SocketError.Success;
-                       
-                       return (BeginSend (buffer, offset, size, socketFlags, callback,
-                               state));
+                       ThrowIfDisposedAndClosed ();
+                       ThrowIfBufferNull (buffer);
+                       ThrowIfBufferOutOfRange (buffer, offset, size);
+
+                       return Send_nochecks (buffer, offset, size, flags, out error);
                }
 
-               public IAsyncResult BeginSend (IList<ArraySegment<byte>> buffers,
-                                              SocketFlags socketFlags,
-                                              AsyncCallback callback,
-                                              object state)
+               public
+               int Send (IList<ArraySegment<byte>> buffers)
                {
-                       if (is_disposed && is_closed)
-                               throw new ObjectDisposedException (GetType ().ToString ());
+                       SocketError error;
+                       int ret = Send (buffers, SocketFlags.None, out error);
 
-                       if (buffers == null)
-                               throw new ArgumentNullException ("buffers");
+                       if (error != SocketError.Success)
+                               throw new SocketException ((int) error);
 
-                       if (!is_connected)
-                               throw new SocketException ((int)SocketError.NotConnected);
+                       return ret;
+               }
 
-                       SocketAsyncResult req = new SocketAsyncResult (this, state, callback, SocketOperation.SendGeneric);
-                       req.Buffers = buffers;
-                       req.SockFlags = socketFlags;
-                       int count;
-                       lock (writeQ) {
-                               writeQ.Enqueue (req.Worker);
-                               count = writeQ.Count;
-                       }
-                       if (count == 1)
-                               socket_pool_queue (SocketAsyncWorker.Dispatcher, req);
-                       return req;
+               public
+               int Send (IList<ArraySegment<byte>> buffers, SocketFlags socketFlags)
+               {
+                       SocketError error;
+                       int ret = Send (buffers, socketFlags, out error);
+
+                       if (error != SocketError.Success)
+                               throw new SocketException ((int) error);
+
+                       return ret;
                }
 
                [CLSCompliant (false)]
-               public IAsyncResult BeginSend (IList<ArraySegment<byte>> buffers,
-                                              SocketFlags socketFlags,
-                                              out SocketError errorCode,
-                                              AsyncCallback callback,
-                                              object state)
+               public int Send (IList<ArraySegment<byte>> buffers, SocketFlags socketFlags, out SocketError errorCode)
                {
-                       if (!is_connected) {
-                               errorCode = SocketError.NotConnected;
-                               throw new SocketException ((int)errorCode);
-                       }
-                       
-                       errorCode = SocketError.Success;
-                       return (BeginSend (buffers, socketFlags, callback, state));
-               }
+                       ThrowIfDisposedAndClosed ();
 
-               delegate void SendFileHandler (string fileName, byte [] preBuffer, byte [] postBuffer, TransmitFileOptions flags);
+                       if (buffers == null)
+                               throw new ArgumentNullException ("buffers");
+                       if (buffers.Count == 0)
+                               throw new ArgumentException ("Buffer is empty", "buffers");
 
-               sealed class SendFileAsyncResult : IAsyncResult {
-                       IAsyncResult ares;
-                       SendFileHandler d;
+                       int numsegments = buffers.Count;
+                       int nativeError;
+                       int ret;
 
-                       public SendFileAsyncResult (SendFileHandler d, IAsyncResult ares)
-                       {
-                               this.d = d;
-                               this.ares = ares;
-                       }
+                       WSABUF[] bufarray = new WSABUF[numsegments];
+                       GCHandle[] gch = new GCHandle[numsegments];
 
-                       public object AsyncState {
-                               get { return ares.AsyncState; }
-                       }
+                       for(int i = 0; i < numsegments; i++) {
+                               ArraySegment<byte> segment = buffers[i];
 
-                       public WaitHandle AsyncWaitHandle {
-                               get { return ares.AsyncWaitHandle; }
-                       }
+                               if (segment.Offset < 0 || segment.Count < 0 || segment.Count > segment.Array.Length - segment.Offset)
+                                       throw new ArgumentOutOfRangeException ("segment");
 
-                       public bool CompletedSynchronously {
-                               get { return ares.CompletedSynchronously; }
+                               gch[i] = GCHandle.Alloc (segment.Array, GCHandleType.Pinned);
+                               bufarray[i].len = segment.Count;
+                               bufarray[i].buf = Marshal.UnsafeAddrOfPinnedArrayElement (segment.Array, segment.Offset);
                        }
 
-                       public bool IsCompleted {
-                               get { return ares.IsCompleted; }
+                       try {
+                               ret = Send_internal (safe_handle, bufarray, socketFlags, out nativeError);
+                       } finally {
+                               for(int i = 0; i < numsegments; i++) {
+                                       if (gch[i].IsAllocated) {
+                                               gch[i].Free ();
+                                       }
+                               }
                        }
 
-                       public SendFileHandler Delegate {
-                               get { return d; }
-                       }
+                       errorCode = (SocketError)nativeError;
 
-                       public IAsyncResult Original {
-                               get { return ares; }
-                       }
+                       return ret;
                }
 
-               public IAsyncResult BeginSendFile (string fileName,
-                                                  AsyncCallback callback,
-                                                  object state)
+               int Send_nochecks (byte [] buf, int offset, int size, SocketFlags flags, out SocketError error)
                {
-                       if (is_disposed && is_closed)
-                               throw new ObjectDisposedException (GetType ().ToString ());
+                       if (size == 0) {
+                               error = SocketError.Success;
+                               return 0;
+                       }
 
-                       if (!is_connected)
-                               throw new NotSupportedException ();
+                       int nativeError;
+                       int ret = Send_internal (safe_handle, buf, offset, size, flags, out nativeError);
 
-                       if (!File.Exists (fileName))
-                               throw new FileNotFoundException ();
+                       error = (SocketError)nativeError;
 
-                       return BeginSendFile (fileName, null, null, 0, callback, state);
+                       if (error != SocketError.Success && error != SocketError.WouldBlock && error != SocketError.InProgress) {
+                               is_connected = false;
+                               is_bound = false;
+                       } else {
+                               is_connected = true;
+                       }
+
+                       return ret;
                }
 
-               public IAsyncResult BeginSendFile (string fileName,
-                                                  byte[] preBuffer,
-                                                  byte[] postBuffer,
-                                                  TransmitFileOptions flags,
-                                                  AsyncCallback callback,
-                                                  object state)
+               public bool SendAsync (SocketAsyncEventArgs e)
                {
-                       if (is_disposed && is_closed)
-                               throw new ObjectDisposedException (GetType ().ToString ());
+                       // NO check is made whether e != null in MS.NET (NRE is thrown in such case)
 
-                       if (!is_connected)
-                               throw new NotSupportedException ();
+                       ThrowIfDisposedAndClosed ();
 
-                       if (!File.Exists (fileName))
-                               throw new FileNotFoundException ();
+                       if (e.Buffer == null && e.BufferList == null)
+                               throw new NullReferenceException ("Either e.Buffer or e.BufferList must be valid buffers.");
 
-                       SendFileHandler d = new SendFileHandler (SendFile);
-                       return new SendFileAsyncResult (d, d.BeginInvoke (fileName, preBuffer, postBuffer, flags, ar => {
-                               SendFileAsyncResult sfar = new SendFileAsyncResult (d, ar);
-                               callback (sfar);
-                       }, state));
-               }
+                       if (e.Buffer == null) {
+                               InitSocketAsyncEventArgs (e, SendAsyncCallback, e, SocketOperation.SendGeneric);
 
-               public IAsyncResult BeginSendTo(byte[] buffer, int offset,
-                                               int size,
-                                               SocketFlags socket_flags,
-                                               EndPoint remote_end,
-                                               AsyncCallback callback,
-                                               object state) {
-                       if (is_disposed && is_closed)
-                               throw new ObjectDisposedException (GetType ().ToString ());
+                               e.socket_async_result.Buffers = e.BufferList;
 
-                       if (buffer == null)
-                               throw new ArgumentNullException ("buffer");
+                               QueueIOSelectorJob (writeQ, e.socket_async_result.Handle, new IOSelectorJob (IOOperation.Write, BeginSendGenericCallback, e.socket_async_result));
+                       } else {
+                               InitSocketAsyncEventArgs (e, SendAsyncCallback, e, SocketOperation.Send);
 
-                       CheckRange (buffer, offset, size);
+                               e.socket_async_result.Buffer = e.Buffer;
+                               e.socket_async_result.Offset = e.Offset;
+                               e.socket_async_result.Size = e.Count;
 
-                       SocketAsyncResult req = new SocketAsyncResult (this, state, callback, SocketOperation.SendTo);
-                       req.Buffer = buffer;
-                       req.Offset = offset;
-                       req.Size = size;
-                       req.SockFlags = socket_flags;
-                       req.EndPoint = remote_end;
-                       int count;
-                       lock (writeQ) {
-                               writeQ.Enqueue (req.Worker);
-                               count = writeQ.Count;
+                               QueueIOSelectorJob (writeQ, e.socket_async_result.Handle, new IOSelectorJob (IOOperation.Write, s => BeginSendCallback ((SocketAsyncResult) s, 0), e.socket_async_result));
                        }
-                       if (count == 1)
-                               socket_pool_queue (SocketAsyncWorker.Dispatcher, req);
-                       return req;
+
+                       return true;
                }
 
-               // Creates a new system socket, returning the handle
-               [MethodImplAttribute(MethodImplOptions.InternalCall)]
-               private extern static void Bind_internal(IntPtr sock,
-                                                        SocketAddress sa,
-                                                        out int error);
+               static AsyncCallback SendAsyncCallback = new AsyncCallback (ares => {
+                       SocketAsyncEventArgs e = (SocketAsyncEventArgs) ((SocketAsyncResult) ares).AsyncState;
+
+                       if (Interlocked.Exchange (ref e.in_progress, 0) != 1)
+                               throw new InvalidOperationException ("No operation in progress");
 
-               private static void Bind_internal (SafeSocketHandle safeHandle,
-                                                        SocketAddress sa,
-                                                        out int error)
-               {
-                       bool release = false;
                        try {
-                               safeHandle.DangerousAddRef (ref release);
-                               Bind_internal (safeHandle.DangerousGetHandle (), sa, out error);
+                               e.BytesTransferred = e.current_socket.EndSend (ares);
+                       } catch (SocketException se){
+                               e.SocketError = se.SocketErrorCode;
+                       } catch (ObjectDisposedException) {
+                               e.SocketError = SocketError.OperationAborted;
                        } finally {
-                               if (release)
-                                       safeHandle.DangerousRelease ();
+                               e.Complete ();
                        }
-               }
+               });
 
-               public void Bind(EndPoint local_end) {
-                       if (is_disposed && is_closed)
-                               throw new ObjectDisposedException (GetType ().ToString ());
+               public IAsyncResult BeginSend (byte[] buffer, int offset, int size, SocketFlags socketFlags, out SocketError errorCode, AsyncCallback callback, object state)
+               {
+                       if (!is_connected) {
+                               errorCode = SocketError.NotConnected;
+                               throw new SocketException ((int) errorCode);
+                       }
 
-                       if (local_end == null)
-                               throw new ArgumentNullException("local_end");
-                       
-                       int error;
-                       
-                       Bind_internal (safe_handle, local_end.Serialize(), out error);
-                       if (error != 0)
-                               throw new SocketException (error);
-                       if (error == 0)
-                               is_bound = true;
-                       
-                       seed_endpoint = local_end;
+                       errorCode = SocketError.Success;
+                       return BeginSend (buffer, offset, size, socketFlags, callback, state);
                }
 
+               public IAsyncResult BeginSend (byte[] buffer, int offset, int size, SocketFlags socket_flags, AsyncCallback callback, object state)
+               {
+                       ThrowIfDisposedAndClosed ();
+                       ThrowIfBufferNull (buffer);
+                       ThrowIfBufferOutOfRange (buffer, offset, size);
+
+                       if (!is_connected)
+                               throw new SocketException ((int)SocketError.NotConnected);
+
+                       SocketAsyncResult sockares = new SocketAsyncResult (this, callback, state, SocketOperation.Send) {
+                               Buffer = buffer,
+                               Offset = offset,
+                               Size = size,
+                               SockFlags = socket_flags,
+                       };
 
+                       QueueIOSelectorJob (writeQ, sockares.Handle, new IOSelectorJob (IOOperation.Write, s => BeginSendCallback ((SocketAsyncResult) s, 0), sockares));
 
+                       return sockares;
+               }
 
-#if !MOBILE
-               [MonoLimitation ("We do not support passing sockets across processes, we merely allow this API to pass the socket across AppDomains")]
-               public SocketInformation DuplicateAndClose (int targetProcessId)
+               static void BeginSendCallback (SocketAsyncResult sockares, int sent_so_far)
                {
-                       var si = new SocketInformation ();
-                       si.Options =
-                               (is_listening      ? SocketInformationOptions.Listening : 0) |
-                               (is_connected      ? SocketInformationOptions.Connected : 0) |
-                               (is_blocking       ? 0 : SocketInformationOptions.NonBlocking) |
-                               (use_overlapped_io ? SocketInformationOptions.UseOnlyOverlappedIO : 0);
+                       int total = 0;
 
-                       si.ProtocolInformation = Mono.DataConverter.Pack ("iiiil", (int)address_family, (int)socket_type, (int)protocol_type, is_bound ? 1 : 0, (long)Handle);
-                       safe_handle = null;
-
-                       return si;
-               }
-#endif
+                       try {
+                               total = Socket.Send_internal (sockares.socket.safe_handle, sockares.Buffer, sockares.Offset, sockares.Size, sockares.SockFlags, out sockares.error);
+                       } catch (Exception e) {
+                               sockares.Complete (e);
+                               return;
+                       }
 
+                       if (sockares.error == 0) {
+                               sent_so_far += total;
+                               sockares.Offset += total;
+                               sockares.Size -= total;
 
-               public void EndSendFile (IAsyncResult asyncResult)
-               {
-                       if (is_disposed && is_closed)
-                               throw new ObjectDisposedException (GetType ().ToString ());
+                               if (sockares.socket.is_disposed) {
+                                       sockares.Complete (total);
+                                       return;
+                               }
 
-                       if (asyncResult == null)
-                               throw new ArgumentNullException ("asyncResult");
+                               if (sockares.Size > 0) {
+                                       IOSelector.Add (sockares.Handle, new IOSelectorJob (IOOperation.Write, s => BeginSendCallback ((SocketAsyncResult) s, sent_so_far), sockares));
+                                       return; // Have to finish writing everything. See bug #74475.
+                               }
 
-                       SendFileAsyncResult ares = asyncResult as SendFileAsyncResult;
-                       if (ares == null)
-                               throw new ArgumentException ("Invalid IAsyncResult", "asyncResult");
+                               sockares.Total = sent_so_far;
+                       }
 
-                       ares.Delegate.EndInvoke (ares.Original);
+                       sockares.Complete (total);
                }
 
-               public int EndSendTo (IAsyncResult result)
+               public IAsyncResult BeginSend (IList<ArraySegment<byte>> buffers, SocketFlags socketFlags, AsyncCallback callback, object state)
                {
-                       if (is_disposed && is_closed)
-                               throw new ObjectDisposedException (GetType ().ToString ());
+                       ThrowIfDisposedAndClosed ();
 
-                       if (result == null)
-                               throw new ArgumentNullException ("result");
+                       if (buffers == null)
+                               throw new ArgumentNullException ("buffers");
+                       if (!is_connected)
+                               throw new SocketException ((int)SocketError.NotConnected);
 
-                       SocketAsyncResult req = result as SocketAsyncResult;
-                       if (req == null)
-                               throw new ArgumentException ("Invalid IAsyncResult", "result");
+                       SocketAsyncResult sockares = new SocketAsyncResult (this, callback, state, SocketOperation.SendGeneric) {
+                               Buffers = buffers,
+                               SockFlags = socketFlags,
+                       };
 
-                       if (Interlocked.CompareExchange (ref req.EndCalled, 1, 0) == 1)
-                               throw InvalidAsyncOp ("EndSendTo");
-                       if (!result.IsCompleted)
-                               result.AsyncWaitHandle.WaitOne();
+                       QueueIOSelectorJob (writeQ, sockares.Handle, new IOSelectorJob (IOOperation.Write, BeginSendGenericCallback, sockares));
 
-                       req.CheckIfThrowDelayedException();
-                       return req.Total;
+                       return sockares;
                }
 
-               [MethodImplAttribute(MethodImplOptions.InternalCall)]
-               private extern static void GetSocketOption_arr_internal(IntPtr socket,
-                       SocketOptionLevel level, SocketOptionName name, ref byte[] byte_val,
-                       out int error);
-
-               private static void GetSocketOption_arr_internal (SafeSocketHandle safeHandle,
-                       SocketOptionLevel level, SocketOptionName name, ref byte[] byte_val,
-                       out int error)
+               [CLSCompliant (false)]
+               public IAsyncResult BeginSend (IList<ArraySegment<byte>> buffers, SocketFlags socketFlags, out SocketError errorCode, AsyncCallback callback, object state)
                {
-                       bool release = false;
-                       try {
-                               safeHandle.DangerousAddRef (ref release);
-                               GetSocketOption_arr_internal (safeHandle.DangerousGetHandle (), level, name, ref byte_val, out error);
-                       } finally {
-                               if (release)
-                                       safeHandle.DangerousRelease ();
+                       if (!is_connected) {
+                               errorCode = SocketError.NotConnected;
+                               throw new SocketException ((int)errorCode);
                        }
+
+                       errorCode = SocketError.Success;
+                       return BeginSend (buffers, socketFlags, callback, state);
                }
 
-               public void GetSocketOption (SocketOptionLevel optionLevel, SocketOptionName optionName, byte [] optionValue)
-               {
-                       if (is_disposed && is_closed)
-                               throw new ObjectDisposedException (GetType ().ToString ());
+               static IOAsyncCallback BeginSendGenericCallback = new IOAsyncCallback (ares => {
+                       SocketAsyncResult sockares = (SocketAsyncResult) ares;
+                       int total = 0;
 
-                       if (optionValue == null)
-                               throw new SocketException ((int) SocketError.Fault,
-                                       "Error trying to dereference an invalid pointer");
+                       try {
+                               total = sockares.socket.Send (sockares.Buffers, sockares.SockFlags);
+                       } catch (Exception e) {
+                               sockares.Complete (e);
+                               return;
+                       }
 
-                       int error;
+                       sockares.Complete (total);
+               });
 
-                       GetSocketOption_arr_internal (safe_handle, optionLevel, optionName, ref optionValue,
-                               out error);
-                       if (error != 0)
-                               throw new SocketException (error);
+               public int EndSend (IAsyncResult result)
+               {
+                       SocketError error;
+                       int bytesSent = EndSend (result, out error);
+
+                       if (error != SocketError.Success) {
+                               if (error != SocketError.WouldBlock && error != SocketError.InProgress)
+                                       is_connected = false;
+                               throw new SocketException ((int)error);
+                       }
+
+                       return bytesSent;
                }
 
-               public byte [] GetSocketOption (SocketOptionLevel optionLevel, SocketOptionName optionName, int length)
+               public int EndSend (IAsyncResult asyncResult, out SocketError errorCode)
                {
-                       if (is_disposed && is_closed)
-                               throw new ObjectDisposedException (GetType ().ToString ());
+                       ThrowIfDisposedAndClosed ();
 
-                       byte[] byte_val=new byte[length];
-                       int error;
+                       SocketAsyncResult sockares = ValidateEndIAsyncResult (asyncResult, "EndSend", "asyncResult");
 
-                       GetSocketOption_arr_internal (safe_handle, optionLevel, optionName, ref byte_val,
-                               out error);
-                       if (error != 0)
-                               throw new SocketException (error);
+                       if (!sockares.IsCompleted)
+                               sockares.AsyncWaitHandle.WaitOne ();
 
-                       return(byte_val);
-               }
+                       /* If no socket error occurred, call CheckIfThrowDelayedException in
+                        * case there are other kinds of exceptions that should be thrown.*/
+                       if ((errorCode = sockares.ErrorCode) == SocketError.Success)
+                               sockares.CheckIfThrowDelayedException ();
 
-               // See Socket.IOControl, WSAIoctl documentation in MSDN. The
-               // common options between UNIX and Winsock are FIONREAD,
-               // FIONBIO and SIOCATMARK. Anything else will depend on the
-               // system except SIO_KEEPALIVE_VALS which is properly handled
-               // on both windows and linux.
-               [MethodImplAttribute(MethodImplOptions.InternalCall)]
-               extern static int WSAIoctl (IntPtr sock, int ioctl_code, byte [] input,
-                       byte [] output, out int error);
+                       return sockares.Total;
+               }
 
-               private static int WSAIoctl (SafeSocketHandle safeHandle, int ioctl_code, byte [] input,
-                       byte [] output, out int error)
+               static int Send_internal (SafeSocketHandle safeHandle, WSABUF[] bufarray, SocketFlags flags, out int error)
                {
                        bool release = false;
                        try {
                                safeHandle.DangerousAddRef (ref release);
-                               return WSAIoctl (safeHandle.DangerousGetHandle (), ioctl_code, input, output, out error);
+                               return Send_internal (safeHandle.DangerousGetHandle (), bufarray, flags, out error);
                        } finally {
                                if (release)
                                        safeHandle.DangerousRelease ();
                        }
                }
 
-               public int IOControl (int ioctl_code, byte [] in_value, byte [] out_value)
-               {
-                       if (is_disposed)
-                               throw new ObjectDisposedException (GetType ().ToString ());
-
-                       int error;
-                       int result = WSAIoctl (safe_handle, ioctl_code, in_value, out_value,
-                               out error);
-
-                       if (error != 0)
-                               throw new SocketException (error);
-                       
-                       if (result == -1)
-                               throw new InvalidOperationException ("Must use Blocking property instead.");
-
-                       return result;
-               }
-
-               public int IOControl (IOControlCode ioControlCode, byte[] optionInValue, byte[] optionOutValue)
-               {
-                       return IOControl ((int) ioControlCode, optionInValue, optionOutValue);
-               }
-
-               [MethodImplAttribute(MethodImplOptions.InternalCall)]
-               private extern static void Listen_internal(IntPtr sock, int backlog, out int error);
+               [MethodImplAttribute (MethodImplOptions.InternalCall)]
+               extern static int Send_internal (IntPtr sock, WSABUF[] bufarray, SocketFlags flags, out int error);
 
-               private static void Listen_internal (SafeSocketHandle safeHandle, int backlog, out int error)
+               static int Send_internal (SafeSocketHandle safeHandle, byte[] buf, int offset, int count, SocketFlags flags, out int error)
                {
-                       bool release = false;
                        try {
-                               safeHandle.DangerousAddRef (ref release);
-                               Listen_internal (safeHandle.DangerousGetHandle (), backlog, out error);
+                               safeHandle.RegisterForBlockingSyscall ();
+                               return Send_internal (safeHandle.DangerousGetHandle (), buf, offset, count, flags, out error);
                        } finally {
-                               if (release)
-                                       safeHandle.DangerousRelease ();
+                               safeHandle.UnRegisterForBlockingSyscall ();
                        }
                }
 
-               public void Listen (int backlog)
-               {
-                       if (is_disposed && is_closed)
-                               throw new ObjectDisposedException (GetType ().ToString ());
+               [MethodImplAttribute(MethodImplOptions.InternalCall)]
+               extern static int Send_internal(IntPtr sock, byte[] buf, int offset, int count, SocketFlags flags, out int error);
 
-                       if (!is_bound)
-                               throw new SocketException ((int)SocketError.InvalidArgument);
+#endregion
 
-                       int error;
-                       Listen_internal(safe_handle, backlog, out error);
+#region SendTo
 
-                       if (error != 0)
-                               throw new SocketException (error);
+               public int SendTo (byte [] buffer, EndPoint remote_end)
+               {
+                       ThrowIfDisposedAndClosed ();
+                       ThrowIfBufferNull (buffer);
 
-                       is_listening = true;
+                       return SendTo (buffer, 0, buffer.Length, SocketFlags.None, remote_end);
                }
 
-               public bool Poll (int time_us, SelectMode mode)
+               public int SendTo (byte [] buffer, SocketFlags flags, EndPoint remote_end)
                {
-                       if (is_disposed && is_closed)
-                               throw new ObjectDisposedException (GetType ().ToString ());
-
-                       if (mode != SelectMode.SelectRead &&
-                           mode != SelectMode.SelectWrite &&
-                           mode != SelectMode.SelectError)
-                               throw new NotSupportedException ("'mode' parameter is not valid.");
-
-                       int error;
-                       bool result = Poll_internal (safe_handle, mode, time_us, out error);
-                       if (error != 0)
-                               throw new SocketException (error);
+                       ThrowIfDisposedAndClosed ();
+                       ThrowIfBufferNull (buffer);
 
-                       if (mode == SelectMode.SelectWrite && result && !is_connected) {
-                               /* Update the is_connected state; for
-                                * non-blocking Connect()s this is
-                                * when we can find out that the
-                                * connect succeeded.
-                                */
-                               if ((int)GetSocketOption (SocketOptionLevel.Socket, SocketOptionName.Error) == 0) {
-                                       is_connected = true;
-                               }
-                       }
-                       
-                       return result;
+                       return SendTo (buffer, 0, buffer.Length, flags, remote_end);
                }
 
-               
-
-               [MonoTODO ("Not implemented")]
-               public bool SendPacketsAsync (SocketAsyncEventArgs e)
+               public int SendTo (byte [] buffer, int size, SocketFlags flags, EndPoint remote_end)
                {
-                       // NO check is made whether e != null in MS.NET (NRE is thrown in such case)
-                       
-                       if (is_disposed && is_closed)
-                               throw new ObjectDisposedException (GetType ().ToString ());
-                       
-                       throw new NotImplementedException ();
+                       return SendTo (buffer, 0, size, flags, remote_end);
                }
 
-               public int Send (byte [] buf)
+               public int SendTo (byte [] buffer, int offset, int size, SocketFlags flags, EndPoint remote_end)
                {
-                       if (is_disposed && is_closed)
-                               throw new ObjectDisposedException (GetType ().ToString ());
-
-                       if (buf == null)
-                               throw new ArgumentNullException ("buf");
-
-                       SocketError error;
-
-                       int ret = Send_nochecks (buf, 0, buf.Length, SocketFlags.None, out error);
+                       ThrowIfDisposedAndClosed ();
+                       ThrowIfBufferNull (buffer);
+                       ThrowIfBufferOutOfRange (buffer, offset, size);
 
-                       if (error != SocketError.Success)
-                               throw new SocketException ((int) error);
+                       if (remote_end == null)
+                               throw new ArgumentNullException("remote_end");
 
-                       return ret;
+                       return SendTo_nochecks (buffer, offset, size, flags, remote_end);
                }
 
-               public int Send (byte [] buf, SocketFlags flags)
+               public bool SendToAsync (SocketAsyncEventArgs e)
                {
-                       if (is_disposed && is_closed)
-                               throw new ObjectDisposedException (GetType ().ToString ());
+                       // NO check is made whether e != null in MS.NET (NRE is thrown in such case)
 
-                       if (buf == null)
-                               throw new ArgumentNullException ("buf");
+                       ThrowIfDisposedAndClosed ();
 
-                       SocketError error;
+                       if (e.BufferList != null)
+                               throw new NotSupportedException ("Mono doesn't support using BufferList at this point.");
+                       if (e.RemoteEndPoint == null)
+                               throw new ArgumentNullException ("remoteEP", "Value cannot be null.");
 
-                       int ret = Send_nochecks (buf, 0, buf.Length, flags, out error);
+                       InitSocketAsyncEventArgs (e, SendToAsyncCallback, e, SocketOperation.SendTo);
 
-                       if (error != SocketError.Success)
-                               throw new SocketException ((int) error);
+                       e.socket_async_result.Buffer = e.Buffer;
+                       e.socket_async_result.Offset = e.Offset;
+                       e.socket_async_result.Size = e.Count;
+                       e.socket_async_result.SockFlags = e.SocketFlags;
+                       e.socket_async_result.EndPoint = e.RemoteEndPoint;
 
-                       return ret;
+                       QueueIOSelectorJob (writeQ, e.socket_async_result.Handle, new IOSelectorJob (IOOperation.Write, s => BeginSendToCallback ((SocketAsyncResult) s, 0), e.socket_async_result));
+
+                       return true;
                }
 
-               public int Send (byte [] buf, int size, SocketFlags flags)
-               {
-                       if (is_disposed && is_closed)
-                               throw new ObjectDisposedException (GetType ().ToString ());
+               static AsyncCallback SendToAsyncCallback = new AsyncCallback (ares => {
+                       SocketAsyncEventArgs e = (SocketAsyncEventArgs) ((SocketAsyncResult) ares).AsyncState;
 
-                       if (buf == null)
-                               throw new ArgumentNullException ("buf");
+                       if (Interlocked.Exchange (ref e.in_progress, 0) != 1)
+                               throw new InvalidOperationException ("No operation in progress");
 
-                       CheckRange (buf, 0, size);
+                       try {
+                               e.BytesTransferred = e.current_socket.EndSendTo (ares);
+                       } catch (SocketException ex) {
+                               e.SocketError = ex.SocketErrorCode;
+                       } catch (ObjectDisposedException) {
+                               e.SocketError = SocketError.OperationAborted;
+                       } finally {
+                               e.Complete ();
+                       }
+               });
 
-                       SocketError error;
+               public IAsyncResult BeginSendTo(byte[] buffer, int offset, int size, SocketFlags socket_flags, EndPoint remote_end, AsyncCallback callback, object state)
+               {
+                       ThrowIfDisposedAndClosed ();
+                       ThrowIfBufferNull (buffer);
+                       ThrowIfBufferOutOfRange (buffer, offset, size);
 
-                       int ret = Send_nochecks (buf, 0, size, flags, out error);
+                       SocketAsyncResult sockares = new SocketAsyncResult (this, callback, state, SocketOperation.SendTo) {
+                               Buffer = buffer,
+                               Offset = offset,
+                               Size = size,
+                               SockFlags = socket_flags,
+                               EndPoint = remote_end,
+                       };
 
-                       if (error != SocketError.Success)
-                               throw new SocketException ((int) error);
+                       QueueIOSelectorJob (writeQ, sockares.Handle, new IOSelectorJob (IOOperation.Write, s => BeginSendToCallback ((SocketAsyncResult) s, 0), sockares));
 
-                       return ret;
+                       return sockares;
                }
 
-               public int Send (byte [] buf, int offset, int size, SocketFlags flags)
+               static void BeginSendToCallback (SocketAsyncResult sockares, int sent_so_far)
                {
-                       if (is_disposed && is_closed)
-                               throw new ObjectDisposedException (GetType ().ToString ());
+                       int total = 0;
+                       try {
+                               total = sockares.socket.SendTo_nochecks (sockares.Buffer, sockares.Offset, sockares.Size, sockares.SockFlags, sockares.EndPoint);
 
-                       if (buf == null)
-                               throw new ArgumentNullException ("buffer");
+                               if (sockares.error == 0) {
+                                       sent_so_far += total;
+                                       sockares.Offset += total;
+                                       sockares.Size -= total;
+                               }
 
-                       CheckRange (buf, offset, size);
+                               if (sockares.Size > 0) {
+                                       IOSelector.Add (sockares.Handle, new IOSelectorJob (IOOperation.Write, s => BeginSendToCallback ((SocketAsyncResult) s, sent_so_far), sockares));
+                                       return; // Have to finish writing everything. See bug #74475.
+                               }
 
-                       SocketError error;
+                               sockares.Total = sent_so_far;
+                       } catch (Exception e) {
+                               sockares.Complete (e);
+                               return;
+                       }
 
-                       int ret = Send_nochecks (buf, offset, size, flags, out error);
+                       sockares.Complete ();
+               }
 
-                       if (error != SocketError.Success)
-                               throw new SocketException ((int) error);
+               public int EndSendTo (IAsyncResult result)
+               {
+                       ThrowIfDisposedAndClosed ();
 
-                       return ret;
+                       SocketAsyncResult sockares = ValidateEndIAsyncResult (result, "EndSendTo", "result");
+
+                       if (!sockares.IsCompleted)
+                               sockares.AsyncWaitHandle.WaitOne();
+
+                       sockares.CheckIfThrowDelayedException();
+
+                       return sockares.Total;
                }
 
-               public int Send (byte [] buf, int offset, int size, SocketFlags flags, out SocketError error)
+               int SendTo_nochecks (byte [] buffer, int offset, int size, SocketFlags flags, EndPoint remote_end)
                {
-                       if (is_disposed && is_closed)
-                               throw new ObjectDisposedException (GetType ().ToString ());
+                       int error;
+                       int ret = SendTo_internal (safe_handle, buffer, offset, size, flags, remote_end.Serialize (), out error);
 
-                       if (buf == null)
-                               throw new ArgumentNullException ("buffer");
+                       SocketError err = (SocketError) error;
+                       if (err != 0) {
+                               if (err != SocketError.WouldBlock && err != SocketError.InProgress)
+                                       is_connected = false;
+                               throw new SocketException (error);
+                       }
 
-                       CheckRange (buf, offset, size);
+                       is_connected = true;
+                       is_bound = true;
+                       seed_endpoint = remote_end;
 
-                       return Send_nochecks (buf, offset, size, flags, out error);
+                       return ret;
                }
 
-               [MethodImplAttribute(MethodImplOptions.InternalCall)]
-               private extern static bool SendFile (IntPtr sock, string filename, byte [] pre_buffer, byte [] post_buffer, TransmitFileOptions flags);
-
-               private static bool SendFile (SafeSocketHandle safeHandle, string filename, byte [] pre_buffer, byte [] post_buffer, TransmitFileOptions flags)
+               static int SendTo_internal (SafeSocketHandle safeHandle, byte[] buffer, int offset, int count, SocketFlags flags, SocketAddress sa, out int error)
                {
                        try {
                                safeHandle.RegisterForBlockingSyscall ();
-                               return SendFile (safeHandle.DangerousGetHandle (), filename, pre_buffer, post_buffer, flags);
+                               return SendTo_internal (safeHandle.DangerousGetHandle (), buffer, offset, count, flags, sa, out error);
                        } finally {
                                safeHandle.UnRegisterForBlockingSyscall ();
                        }
                }
 
+               [MethodImplAttribute(MethodImplOptions.InternalCall)]
+               extern static int SendTo_internal (IntPtr sock, byte[] buffer, int offset, int count, SocketFlags flags, SocketAddress sa, out int error);
+
+#endregion
+
+#region SendFile
+
                public void SendFile (string fileName)
                {
-                       if (is_disposed && is_closed)
-                               throw new ObjectDisposedException (GetType ().ToString ());
+                       ThrowIfDisposedAndClosed ();
 
                        if (!is_connected)
                                throw new NotSupportedException ();
-
                        if (!is_blocking)
                                throw new InvalidOperationException ();
 
@@ -2592,16 +2866,14 @@ namespace System.Net.Sockets
 
                public void SendFile (string fileName, byte[] preBuffer, byte[] postBuffer, TransmitFileOptions flags)
                {
-                       if (is_disposed && is_closed)
-                               throw new ObjectDisposedException (GetType ().ToString ());
+                       ThrowIfDisposedAndClosed ();
 
                        if (!is_connected)
                                throw new NotSupportedException ();
-
                        if (!is_blocking)
                                throw new InvalidOperationException ();
 
-                       if (!SendFile (safe_handle, fileName, preBuffer, postBuffer, flags)) {
+                       if (!SendFile_internal (safe_handle, fileName, preBuffer, postBuffer, flags)) {
                                SocketException exc = new SocketException ();
                                if (exc.ErrorCode == 2 || exc.ErrorCode == 3)
                                        throw new FileNotFoundException ();
@@ -2609,159 +2881,229 @@ namespace System.Net.Sockets
                        }
                }
 
-               public bool SendToAsync (SocketAsyncEventArgs e)
+               public IAsyncResult BeginSendFile (string fileName, AsyncCallback callback, object state)
+               {
+                       ThrowIfDisposedAndClosed ();
+
+                       if (!is_connected)
+                               throw new NotSupportedException ();
+                       if (!File.Exists (fileName))
+                               throw new FileNotFoundException ();
+
+                       return BeginSendFile (fileName, null, null, 0, callback, state);
+               }
+
+               public IAsyncResult BeginSendFile (string fileName, byte[] preBuffer, byte[] postBuffer, TransmitFileOptions flags, AsyncCallback callback, object state)
+               {
+                       ThrowIfDisposedAndClosed ();
+
+                       if (!is_connected)
+                               throw new NotSupportedException ();
+                       if (!File.Exists (fileName))
+                               throw new FileNotFoundException ();
+
+                       SendFileHandler handler = new SendFileHandler (SendFile);
+
+                       return new SendFileAsyncResult (handler, handler.BeginInvoke (fileName, preBuffer, postBuffer, flags, ar => callback (new SendFileAsyncResult (handler, ar)), state));
+               }
+
+               public void EndSendFile (IAsyncResult asyncResult)
+               {
+                       ThrowIfDisposedAndClosed ();
+
+                       if (asyncResult == null)
+                               throw new ArgumentNullException ("asyncResult");
+
+                       SendFileAsyncResult ares = asyncResult as SendFileAsyncResult;
+                       if (ares == null)
+                               throw new ArgumentException ("Invalid IAsyncResult", "asyncResult");
+
+                       ares.Delegate.EndInvoke (ares.Original);
+               }
+
+               static bool SendFile_internal (SafeSocketHandle safeHandle, string filename, byte [] pre_buffer, byte [] post_buffer, TransmitFileOptions flags)
+               {
+                       try {
+                               safeHandle.RegisterForBlockingSyscall ();
+                               return SendFile_internal (safeHandle.DangerousGetHandle (), filename, pre_buffer, post_buffer, flags);
+                       } finally {
+                               safeHandle.UnRegisterForBlockingSyscall ();
+                       }
+               }
+
+               [MethodImplAttribute(MethodImplOptions.InternalCall)]
+               extern static bool SendFile_internal (IntPtr sock, string filename, byte [] pre_buffer, byte [] post_buffer, TransmitFileOptions flags);
+
+               delegate void SendFileHandler (string fileName, byte [] preBuffer, byte [] postBuffer, TransmitFileOptions flags);
+
+               sealed class SendFileAsyncResult : IAsyncResult {
+                       IAsyncResult ares;
+                       SendFileHandler d;
+
+                       public SendFileAsyncResult (SendFileHandler d, IAsyncResult ares)
+                       {
+                               this.d = d;
+                               this.ares = ares;
+                       }
+
+                       public object AsyncState {
+                               get { return ares.AsyncState; }
+                       }
+
+                       public WaitHandle AsyncWaitHandle {
+                               get { return ares.AsyncWaitHandle; }
+                       }
+
+                       public bool CompletedSynchronously {
+                               get { return ares.CompletedSynchronously; }
+                       }
+
+                       public bool IsCompleted {
+                               get { return ares.IsCompleted; }
+                       }
+
+                       public SendFileHandler Delegate {
+                               get { return d; }
+                       }
+
+                       public IAsyncResult Original {
+                               get { return ares; }
+                       }
+               }
+
+#endregion
+
+#region SendPackets
+
+               [MonoTODO ("Not implemented")]
+               public bool SendPacketsAsync (SocketAsyncEventArgs e)
                {
                        // NO check is made whether e != null in MS.NET (NRE is thrown in such case)
-                       
-                       if (is_disposed && is_closed)
-                               throw new ObjectDisposedException (GetType ().ToString ());
-                       if (e.BufferList != null)
-                               throw new NotSupportedException ("Mono doesn't support using BufferList at this point.");
-                       if (e.RemoteEndPoint == null)
-                               throw new ArgumentNullException ("remoteEP", "Value cannot be null.");
 
-                       e.curSocket = this;
-                       e.Worker.Init (this, e, SocketOperation.SendTo);
-                       SocketAsyncResult res = e.Worker.result;
-                       res.Buffer = e.Buffer;
-                       res.Offset = e.Offset;
-                       res.Size = e.Count;
-                       res.SockFlags = e.SocketFlags;
-                       res.EndPoint = e.RemoteEndPoint;
-                       int count;
-                       lock (writeQ) {
-                               writeQ.Enqueue (e.Worker);
-                               count = writeQ.Count;
-                       }
-                       if (count == 1)
-                               socket_pool_queue (SocketAsyncWorker.Dispatcher, res);
-                       return true;
+                       ThrowIfDisposedAndClosed ();
+
+                       throw new NotImplementedException ();
+               }
+
+#endregion
+
+#region DuplicateAndClose
+
+#if !MOBILE
+               [MonoLimitation ("We do not support passing sockets across processes, we merely allow this API to pass the socket across AppDomains")]
+               public SocketInformation DuplicateAndClose (int targetProcessId)
+               {
+                       var si = new SocketInformation ();
+                       si.Options =
+                               (is_listening      ? SocketInformationOptions.Listening : 0) |
+                               (is_connected      ? SocketInformationOptions.Connected : 0) |
+                               (is_blocking       ? 0 : SocketInformationOptions.NonBlocking) |
+                               (use_overlapped_io ? SocketInformationOptions.UseOnlyOverlappedIO : 0);
+
+                       si.ProtocolInformation = Mono.DataConverter.Pack ("iiiil", (int)address_family, (int)socket_type, (int)protocol_type, is_bound ? 1 : 0, (long)Handle);
+                       safe_handle = null;
+
+                       return si;
                }
-               
-               public int SendTo (byte [] buffer, EndPoint remote_end)
+#endif
+
+#endregion
+
+#region GetSocketOption
+
+               public void GetSocketOption (SocketOptionLevel optionLevel, SocketOptionName optionName, byte [] optionValue)
                {
-                       if (is_disposed && is_closed)
-                               throw new ObjectDisposedException (GetType ().ToString ());
+                       ThrowIfDisposedAndClosed ();
 
-                       if (buffer == null)
-                               throw new ArgumentNullException ("buffer");
+                       if (optionValue == null)
+                               throw new SocketException ((int) SocketError.Fault, "Error trying to dereference an invalid pointer");
 
-                       if (remote_end == null)
-                               throw new ArgumentNullException ("remote_end");
+                       int error;
+                       GetSocketOption_arr_internal (safe_handle, optionLevel, optionName, ref optionValue, out error);
 
-                       return SendTo_nochecks (buffer, 0, buffer.Length, SocketFlags.None, remote_end);
+                       if (error != 0)
+                               throw new SocketException (error);
                }
 
-               public int SendTo (byte [] buffer, SocketFlags flags, EndPoint remote_end)
+               public byte [] GetSocketOption (SocketOptionLevel optionLevel, SocketOptionName optionName, int length)
                {
-                       if (is_disposed && is_closed)
-                               throw new ObjectDisposedException (GetType ().ToString ());
+                       ThrowIfDisposedAndClosed ();
 
-                       if (buffer == null)
-                               throw new ArgumentNullException ("buffer");
+                       int error;
+                       byte[] byte_val = new byte [length];
+                       GetSocketOption_arr_internal (safe_handle, optionLevel, optionName, ref byte_val, out error);
 
-                       if (remote_end == null)
-                               throw new ArgumentNullException ("remote_end");
-                               
-                       return SendTo_nochecks (buffer, 0, buffer.Length, flags, remote_end);
+                       if (error != 0)
+                               throw new SocketException (error);
+
+                       return byte_val;
                }
 
-               public int SendTo (byte [] buffer, int size, SocketFlags flags, EndPoint remote_end)
+               public object GetSocketOption (SocketOptionLevel optionLevel, SocketOptionName optionName)
                {
-                       if (is_disposed && is_closed)
-                               throw new ObjectDisposedException (GetType ().ToString ());
-
-                       if (buffer == null)
-                               throw new ArgumentNullException ("buffer");
+                       ThrowIfDisposedAndClosed ();
 
-                       if (remote_end == null)
-                               throw new ArgumentNullException ("remote_end");
+                       int error;
+                       object obj_val;
+                       GetSocketOption_obj_internal (safe_handle, optionLevel, optionName, out obj_val, out error);
 
-                       CheckRange (buffer, 0, size);
+                       if (error != 0)
+                               throw new SocketException (error);
 
-                       return SendTo_nochecks (buffer, 0, size, flags, remote_end);
+                       if (optionName == SocketOptionName.Linger)
+                               return (LingerOption) obj_val;
+                       else if (optionName == SocketOptionName.AddMembership || optionName == SocketOptionName.DropMembership)
+                               return (MulticastOption) obj_val;
+                       else if (obj_val is int)
+                               return (int) obj_val;
+                       else
+                               return obj_val;
                }
 
-               [MethodImplAttribute(MethodImplOptions.InternalCall)]
-               private extern static int SendTo_internal(IntPtr sock,
-                                                         byte[] buffer,
-                                                         int offset,
-                                                         int count,
-                                                         SocketFlags flags,
-                                                         SocketAddress sa,
-                                                         out int error);
-
-               private static int SendTo_internal (SafeSocketHandle safeHandle,
-                                                         byte[] buffer,
-                                                         int offset,
-                                                         int count,
-                                                         SocketFlags flags,
-                                                         SocketAddress sa,
-                                                         out int error)
+               static void GetSocketOption_arr_internal (SafeSocketHandle safeHandle, SocketOptionLevel level, SocketOptionName name, ref byte[] byte_val, out int error)
                {
+                       bool release = false;
                        try {
-                               safeHandle.RegisterForBlockingSyscall ();
-                               return SendTo_internal (safeHandle.DangerousGetHandle (), buffer, offset, count, flags, sa, out error);
+                               safeHandle.DangerousAddRef (ref release);
+                               GetSocketOption_arr_internal (safeHandle.DangerousGetHandle (), level, name, ref byte_val, out error);
                        } finally {
-                               safeHandle.UnRegisterForBlockingSyscall ();
+                               if (release)
+                                       safeHandle.DangerousRelease ();
                        }
                }
 
-               public int SendTo (byte [] buffer, int offset, int size, SocketFlags flags,
-                                  EndPoint remote_end)
-               {
-                       if (is_disposed && is_closed)
-                               throw new ObjectDisposedException (GetType ().ToString ());
-
-                       if (buffer == null)
-                               throw new ArgumentNullException ("buffer");
-
-                       if (remote_end == null)
-                               throw new ArgumentNullException("remote_end");
-
-                       CheckRange (buffer, offset, size);
-
-                       return SendTo_nochecks (buffer, offset, size, flags, remote_end);
-               }
+               [MethodImplAttribute(MethodImplOptions.InternalCall)]
+               extern static void GetSocketOption_arr_internal(IntPtr socket, SocketOptionLevel level, SocketOptionName name, ref byte[] byte_val, out int error);
 
-               internal int SendTo_nochecks (byte [] buffer, int offset, int size, SocketFlags flags,
-                                             EndPoint remote_end)
+               static void GetSocketOption_obj_internal (SafeSocketHandle safeHandle, SocketOptionLevel level, SocketOptionName name, out object obj_val, out int error)
                {
-                       SocketAddress sockaddr = remote_end.Serialize ();
-
-                       int ret, error;
-
-                       ret = SendTo_internal (safe_handle, buffer, offset, size, flags, sockaddr, out error);
+                       bool release = false;
+                       try {
+                               safeHandle.DangerousAddRef (ref release);
+                               GetSocketOption_obj_internal (safeHandle.DangerousGetHandle (), level, name, out obj_val, out error);
+                       } finally {
+                               if (release)
+                                       safeHandle.DangerousRelease ();
+                       }
+               }
 
-                       SocketError err = (SocketError) error;
-                       if (err != 0) {
-                               if (err != SocketError.WouldBlock && err != SocketError.InProgress)
-                                       is_connected = false;
+               [MethodImplAttribute(MethodImplOptions.InternalCall)]
+               extern static void GetSocketOption_obj_internal(IntPtr socket, SocketOptionLevel level, SocketOptionName name, out object obj_val, out int error);
 
-                               throw new SocketException (error);
-                       }
+#endregion
 
-                       is_connected = true;
-                       is_bound = true;
-                       seed_endpoint = remote_end;
-                       
-                       return ret;
-               }
+#region SetSocketOption
 
                public void SetSocketOption (SocketOptionLevel optionLevel, SocketOptionName optionName, byte [] optionValue)
                {
-                       if (is_disposed && is_closed)
-                               throw new ObjectDisposedException (GetType ().ToString ());
+                       ThrowIfDisposedAndClosed ();
 
                        // I'd throw an ArgumentNullException, but this is what MS does.
                        if (optionValue == null)
-                               throw new SocketException ((int) SocketError.Fault,
-                                       "Error trying to dereference an invalid pointer");
-                       
-                       int error;
+                               throw new SocketException ((int) SocketError.Fault, "Error trying to dereference an invalid pointer");
 
-                       SetSocketOption_internal (safe_handle, optionLevel, optionName, null,
-                                                optionValue, 0, out error);
+                       int error;
+                       SetSocketOption_internal (safe_handle, optionLevel, optionName, null, optionValue, 0, out error);
 
                        if (error != 0) {
                                if (error == (int) SocketError.InvalidArgument)
@@ -2772,13 +3114,12 @@ namespace System.Net.Sockets
 
                public void SetSocketOption (SocketOptionLevel optionLevel, SocketOptionName optionName, object optionValue)
                {
-                       if (is_disposed && is_closed)
-                               throw new ObjectDisposedException (GetType ().ToString ());
+                       ThrowIfDisposedAndClosed ();
 
                        // NOTE: if a null is passed, the byte[] overload is used instead...
                        if (optionValue == null)
                                throw new ArgumentNullException("optionValue");
-                       
+
                        int error;
 
                        if (optionLevel == SocketOptionLevel.Socket && optionName == SocketOptionName.Linger) {
@@ -2809,12 +3150,12 @@ namespace System.Net.Sockets
 
                public void SetSocketOption (SocketOptionLevel optionLevel, SocketOptionName optionName, bool optionValue)
                {
-                       if (is_disposed && is_closed)
-                               throw new ObjectDisposedException (GetType ().ToString ());
+                       ThrowIfDisposedAndClosed ();
 
                        int error;
-                       int int_val = (optionValue) ? 1 : 0;
+                       int int_val = optionValue ? 1 : 0;
                        SetSocketOption_internal (safe_handle, optionLevel, optionName, null, null, int_val, out error);
+
                        if (error != 0) {
                                if (error == (int) SocketError.InvalidArgument)
                                        throw new ArgumentException ();
@@ -2822,6 +3163,190 @@ namespace System.Net.Sockets
                        }
                }
 
+               public void SetSocketOption (SocketOptionLevel optionLevel, SocketOptionName optionName, int optionValue)
+               {
+                       ThrowIfDisposedAndClosed ();
+
+                       int error;
+                       SetSocketOption_internal (safe_handle, optionLevel, optionName, null, null, optionValue, out error);
+
+                       if (error != 0) {
+                               throw new SocketException (error);
+                       }
+               }
+
+               static void SetSocketOption_internal (SafeSocketHandle safeHandle, SocketOptionLevel level, SocketOptionName name, object obj_val, byte [] byte_val, int int_val, out int error)
+               {
+                       bool release = false;
+                       try {
+                               safeHandle.DangerousAddRef (ref release);
+                               SetSocketOption_internal (safeHandle.DangerousGetHandle (), level, name, obj_val, byte_val, int_val, out error);
+                       } finally {
+                               if (release)
+                                       safeHandle.DangerousRelease ();
+                       }
+               }
+
+               [MethodImplAttribute(MethodImplOptions.InternalCall)]
+               extern static void SetSocketOption_internal (IntPtr socket, SocketOptionLevel level, SocketOptionName name, object obj_val, byte [] byte_val, int int_val, out int error);
+
+#endregion
+
+#region IOControl
+
+               public int IOControl (int ioctl_code, byte [] in_value, byte [] out_value)
+               {
+                       if (is_disposed)
+                               throw new ObjectDisposedException (GetType ().ToString ());
+
+                       int error;
+                       int result = IOControl_internal (safe_handle, ioctl_code, in_value, out_value, out error);
+
+                       if (error != 0)
+                               throw new SocketException (error);
+                       if (result == -1)
+                               throw new InvalidOperationException ("Must use Blocking property instead.");
+
+                       return result;
+               }
+
+               public int IOControl (IOControlCode ioControlCode, byte[] optionInValue, byte[] optionOutValue)
+               {
+                       return IOControl ((int) ioControlCode, optionInValue, optionOutValue);
+               }
+
+               static int IOControl_internal (SafeSocketHandle safeHandle, int ioctl_code, byte [] input, byte [] output, out int error)
+               {
+                       bool release = false;
+                       try {
+                               safeHandle.DangerousAddRef (ref release);
+                               return IOControl_internal (safeHandle.DangerousGetHandle (), ioctl_code, input, output, out error);
+                       } finally {
+                               if (release)
+                                       safeHandle.DangerousRelease ();
+                       }
+               }
+
+               /* See Socket.IOControl, WSAIoctl documentation in MSDN. The common options between UNIX
+                * and Winsock are FIONREAD, FIONBIO and SIOCATMARK. Anything else will depend on the system
+                * except SIO_KEEPALIVE_VALS which is properly handled on both windows and linux. */
+               [MethodImplAttribute(MethodImplOptions.InternalCall)]
+               extern static int IOControl_internal (IntPtr sock, int ioctl_code, byte [] input, byte [] output, out int error);
+
+#endregion
+
+#region Close
+
+               public void Close ()
+               {
+                       linger_timeout = 0;
+                       Dispose ();
+               }
+
+               public void Close (int timeout)
+               {
+                       linger_timeout = timeout;
+                       Dispose ();
+               }
+
+               [MethodImplAttribute(MethodImplOptions.InternalCall)]
+               internal extern static void Close_internal (IntPtr socket, out int error);
+
+#endregion
+
+#region Shutdown
+
+               public void Shutdown (SocketShutdown how)
+               {
+                       ThrowIfDisposedAndClosed ();
+
+                       if (!is_connected)
+                               throw new SocketException (10057); // Not connected
+
+                       int error;
+                       Shutdown_internal (safe_handle, how, out error);
+
+                       if (error != 0)
+                               throw new SocketException (error);
+               }
+
+               static void Shutdown_internal (SafeSocketHandle safeHandle, SocketShutdown how, out int error)
+               {
+                       bool release = false;
+                       try {
+                               safeHandle.DangerousAddRef (ref release);
+                               Shutdown_internal (safeHandle.DangerousGetHandle (), how, out error);
+                       } finally {
+                               if (release)
+                                       safeHandle.DangerousRelease ();
+                       }
+               }
+
+               [MethodImplAttribute (MethodImplOptions.InternalCall)]
+               internal extern static void Shutdown_internal (IntPtr socket, SocketShutdown how, out int error);
+
+#endregion
+
+#region Dispose
+
+               protected virtual void Dispose (bool disposing)
+               {
+                       if (is_disposed)
+                               return;
+
+                       is_disposed = true;
+                       bool was_connected = is_connected;
+                       is_connected = false;
+
+                       if (safe_handle != null) {
+                               is_closed = true;
+                               IntPtr x = Handle;
+
+                               if (was_connected)
+                                       Linger (x);
+
+                               safe_handle.Dispose ();
+                       }
+               }
+
+               public void Dispose ()
+               {
+                       Dispose (true);
+                       GC.SuppressFinalize (this);
+               }
+
+               void Linger (IntPtr handle)
+               {
+                       if (!is_connected || linger_timeout <= 0)
+                               return;
+
+                       /* We don't want to receive any more data */
+                       int error;
+                       Shutdown_internal (handle, SocketShutdown.Receive, out error);
+
+                       if (error != 0)
+                               return;
+
+                       int seconds = linger_timeout / 1000;
+                       int ms = linger_timeout % 1000;
+                       if (ms > 0) {
+                               /* If the other end closes, this will return 'true' with 'Available' == 0 */
+                               Poll_internal (handle, SelectMode.SelectRead, ms * 1000, out error);
+                               if (error != 0)
+                                       return;
+                       }
+
+                       if (seconds > 0) {
+                               LingerOption linger = new LingerOption (true, seconds);
+                               SetSocketOption_internal (handle, SocketOptionLevel.Socket, SocketOptionName.Linger, linger, null, 0, out error);
+                               /* Not needed, we're closing upon return */
+                               //if (error != 0)
+                               //      return;
+                       }
+               }
+
+#endregion
+
                void ThrowIfDisposedAndClosed (Socket socket)
                {
                        if (socket.is_disposed && socket.is_closed)
@@ -2869,10 +3394,68 @@ namespace System.Net.Sockets
                        if (sockares == null)
                                throw new ArgumentException ("Invalid IAsyncResult", argName);
                        if (Interlocked.CompareExchange (ref sockares.EndCalled, 1, 0) == 1)
-                               throw InvalidAsyncOp (methodName);
+                               throw new InvalidOperationException (methodName + " can only be called once per asynchronous operation");
 
                        return sockares;
                }
+
+               void QueueIOSelectorJob (Queue<KeyValuePair<IntPtr, IOSelectorJob>> queue, IntPtr handle, IOSelectorJob job)
+               {
+                       int count;
+                       lock (queue) {
+                               queue.Enqueue (new KeyValuePair<IntPtr, IOSelectorJob> (handle, job));
+                               count = queue.Count;
+                       }
+
+                       if (count == 1)
+                               IOSelector.Add (handle, job);
+               }
+
+               void InitSocketAsyncEventArgs (SocketAsyncEventArgs e, AsyncCallback callback, object state, SocketOperation operation)
+               {
+                       e.socket_async_result.Init (this, callback, state, operation);
+
+                       e.current_socket = this;
+                       e.SetLastOperation (SocketOperationToSocketAsyncOperation (operation));
+                       e.SocketError = SocketError.Success;
+                       e.BytesTransferred = 0;
+               }
+
+               SocketAsyncOperation SocketOperationToSocketAsyncOperation (SocketOperation op)
+               {
+                       switch (op) {
+                       case SocketOperation.Connect:
+                               return SocketAsyncOperation.Connect;
+                       case SocketOperation.Accept:
+                               return SocketAsyncOperation.Accept;
+                       case SocketOperation.Disconnect:
+                               return SocketAsyncOperation.Disconnect;
+                       case SocketOperation.Receive:
+                       case SocketOperation.ReceiveGeneric:
+                               return SocketAsyncOperation.Receive;
+                       case SocketOperation.ReceiveFrom:
+                               return SocketAsyncOperation.ReceiveFrom;
+                       case SocketOperation.Send:
+                       case SocketOperation.SendGeneric:
+                               return SocketAsyncOperation.Send;
+                       case SocketOperation.SendTo:
+                               return SocketAsyncOperation.SendTo;
+                       default:
+                               throw new NotImplementedException (String.Format ("Operation {0} is not implemented", op));
+                       }
+               }
+
+               [StructLayout (LayoutKind.Sequential)]
+               struct WSABUF {
+                       public int len;
+                       public IntPtr buf;
+               }
+
+               [MethodImplAttribute(MethodImplOptions.InternalCall)]
+               internal static extern void cancel_blocking_socket_operation (Thread thread);
+
+               [MethodImplAttribute(MethodImplOptions.InternalCall)]
+               internal static extern bool SupportsPortReuse ();
        }
 }