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IOControlCode Enumeration

Specifies the IO control codes supported by the IOControl method.

Namespace:  System.Net.Sockets
Assembly:  System (in System.dll)
public enum IOControlCode
Member nameDescription
AbsorbRouterAlertThis value is equal to the Winsock 2 SIO_ABSORB_RTRALERT constant.
AddMulticastGroupOnInterfaceJoin a multicast group using an interface identified by its index. This control code is supported on Windows 2000 and later operating systems. This value is equal to the Winsock 2 SIO_INDEX_ADD_MCAST constant.
AddressListChangeEnable receiving notification when the list of local interfaces for the socket's protocol family changes. This control code is supported on Windows 2000 and later operating systems. This value is equal to the Winsock 2 SIO_ADDRESS_LIST_CHANGE constant.
AddressListQueryReturn the list of local interfaces that the socket can bind to. This control code is supported on Windows 2000 and later operating systems. This value is equal to the Winsock 2 SIO_ADDRESS_LIST_QUERY constant.
AddressListSortSort the structure returned by the AddressListQuery field and add scope ID information for IPv6 addresses. This control code is supported on Windows XP and later operating systems. This value is equal to the Winsock 2 SIO_ADDRESS_LIST_SORT constant.
AssociateHandleAssociate this socket with the specified handle of a companion interface. Refer to the appropriate protocol-specific annex in the Winsock 2 reference or documentation for the particular companion interface for additional details. It is recommended that the Component Object Model (COM) be used instead of this IOCTL to discover and track other interfaces that might be supported by a socket. This control code is present for backward compatibility with systems where COM is not available or cannot be used for some other reason. This value is equal to the Winsock 2 SIO_ASSOCIATE_HANDLE constant.
AsyncIOEnable notification for when data is waiting to be received. This value is equal to the Winsock 2 FIOASYNC constant.
BindToInterfaceBind the socket to a specified interface index. This control code is supported on Windows 2000 and later operating systems. This value is equal to the Winsock 2 SIO_INDEX_BIND constant.
DataToReadReturn the number of bytes available for reading. This value is equal to the Winsock 2 FIONREAD constant.
DeleteMulticastGroupFromInterfaceRemove the socket from a multicast group. This control code is supported on Windows 2000 and later operating systems. This value is equal to the Winsock 2 SIO_INDEX_ADD_MCAST constant.
EnableCircularQueuingReplace the oldest queued datagram with an incoming datagram when the incoming message queues are full. This value is equal to the Winsock 2 SIO_ENABLE_CIRCULAR_QUEUEING constant.
FlushDiscard the contents of the sending queue. This value is equal to the Winsock 2 SIO_FLUSH constant.
GetBroadcastAddressReturn a SOCKADDR structure that contains the broadcast address for the address family of the current socket. The returned address can be used with the SendTo method. This value is equal to the Winsock 2 SIO_GET_BROADCAST_ADDRESS constant. This value can be used on User Datagram Protocol (UDP) sockets only.
GetExtensionFunctionPointerObtain provider-specific functions that are not part of the Winsock specification. Functions are specified using their provider-assigned GUID. This value is equal to the Winsock 2 SIO_GET_EXTENSION_FUNCTION_POINTER constant.
GetGroupQosReturn the Quality of Service (QOS) attributes for the socket group. This value is reserved for future use, and is equal to the Winsock 2 SIO_GET_GROUP_QOS constant.
GetQosRetrieve the QOS structure associated with the socket. This control is only supported on platforms that provide a QOS capable transport (Windows Me, Windows 2000, and later.) This value is equal to the Winsock 2 SIO_GET_QOS constant.
KeepAliveValuesControl sending TCP keep-alive packets and the interval at which they are sent. This control code is supported on Windows 2000 and later operating systems. For additional information, see RFC 1122 section 4.2.3.6. This value is equal to the Winsock 2 SIO_KEEPALIVE_VALS constant.
LimitBroadcastsThis value is equal to the Winsock 2 SIO_LIMIT_BROADCASTS constant.
MulticastInterfaceSet the interface used for outgoing multicast packets. The interface is identified by its index. This control code is supported on Windows 2000 and later operating systems. This value is equal to the Winsock 2 SIO_INDEX_MCASTIF constant.
MulticastScopeControl the number of times a multicast packet can be forwarded by a router, also known as the Time to Live (TTL), or hop count. This value is equal to the Winsock 2 SIO_MULTICAST_SCOPE constant.
MultipointLoopbackControl whether multicast data sent by the socket appears as incoming data in the sockets receive queue. This value is equal to the Winsock 2 SIO_MULTIPOINT_LOOPBACK constant.
NamespaceChangeControl whether the socket receives notification when a namespace query becomes invalid. This control code is supported on Windows XP and later operating systems. This value is equal to the Winsock 2 SIO_NSP_NOTIFY_CHANGE constant.
NonBlockingIOControl the blocking behavior of the socket. If the argument specified with this control code is zero, the socket is placed in blocking mode. If the argument is nonzero, the socket is placed in nonblocking mode. This value is equal to the Winsock 2 FIONBIO constant.
OobDataReadReturn information about out-of-band data waiting to be received. When using this control code on stream sockets, the return value indicates the number of bytes available.
QueryTargetPnpHandleRetrieve the underlying provider's SOCKET handle. This handle can be used to receive plug-and-play event notification. This control code is supported on Windows 2000 and later operating systems. This value is equal to the Winsock 2 SIO_QUERY_TARGET_PNP_HANDLE constant.
ReceiveAllEnable receiving all IPv4 packets on the network. The socket must have address family InterNetwork, the socket type must be Raw, and the protocol type must be IP. The current user must belong to the Administrators group on the local computer, and the socket must be bound to a specific port. This control code is supported on Windows 2000 and later operating systems. This value is equal to the Winsock 2 SIO_RCVALL constant.
ReceiveAllIgmpMulticastEnable receiving all Internet Group Management Protocol (IGMP) packets on the network. The socket must have address family InterNetwork, the socket type must be Raw, and the protocol type must be Igmp. The current user must belong to the Administrators group on the local computer, and the socket must be bound to a specific port. This control code is supported on Windows 2000 and later operating systems. This value is equal to the Winsock 2 SIO_RCVALL_IGMPMCAST constant.
ReceiveAllMulticastEnable receiving all multicast IPv4 packets on the network. These are packets with destination addresses in the range 224.0.0.0 through 239.255.255.255. The socket must have address family InterNetwork, the socket type must be Raw, and the protocol type must be Udp. The current user must belong to the Administrators group on the local computer, and the socket must be bound to a specific port. This control code is supported on Windows 2000 and later operating systems. This value is equal to the Winsock 2 SIO_RCVALL_MCAST constant.
RoutingInterfaceChangeEnable receiving notification when the local interface used to access a remote endpoint changes. This value is equal to the Winsock 2 SIO_ROUTING_INTERFACE_CHANGE constant.
RoutingInterfaceQueryReturn the interface addresses that can be used to connect to the specified remote address. This value is equal to the Winsock 2 SIO_ROUTING_INTERFACE_QUERY constant.
SetGroupQosSet the Quality of Service (QOS) attributes for the socket group. This value is reserved for future use and is equal to the Winsock 2 SIO_SET_GROUP_QOS constant.
SetQosSet the Quality of Service (QOS) attributes for the socket. QOS defines the bandwidth requirements for the socket. This control code is supported on Windows Me, Windows 2000, and later operating systems. This value is equal to the Winsock 2 SIO_SET_QOS constant.
TranslateHandleReturn a handle for the socket that is valid in the context of a companion interface. This value is equal to the Winsock 2 SIO_TRANSLATE_HANDLE constant.
UnicastInterfaceSet the interface used for outgoing unicast packets. This value is equal to the Winsock 2 SIO_UCAST_IF constant.

The IOControlCode enumeration provides named values for specifying socket operational modes. These values are the control codes passed to the Windows Sockets 2 (Winsock 2) WSAIoctl function.

The following code example calls the IOControl(IOControlCode, Byte[], Byte[]) method with a DataToRead parameter value and compares the result with accessing the.Available property.

static void DisplayPendingByteCount(Socket s)
{
    byte[] outValue = BitConverter.GetBytes(0);

    // Check how many bytes have been received.
    s.IOControl(IOControlCode.DataToRead, null, outValue);

    uint bytesAvailable = BitConverter.ToUInt32(outValue, 0);
    Console.Write("server has {0} bytes pending. ", 
        bytesAvailable);
    Console.WriteLine("Available property says {1}.",
                     s.Available);

    return;
}

.NET Framework

Supported in: 4.5.1, 4.5, 4, 3.5, 3.0, 2.0

.NET Framework Client Profile

Supported in: 4, 3.5 SP1

Windows Phone 8.1, Windows Phone 8, Windows 8.1, Windows Server 2012 R2, Windows 8, Windows Server 2012, Windows 7, Windows Vista SP2, Windows Server 2008 (Server Core Role not supported), Windows Server 2008 R2 (Server Core Role supported with SP1 or later; Itanium not supported)

The .NET Framework does not support all versions of every platform. For a list of the supported versions, see .NET Framework System Requirements.

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