WSASendDisconnect function (winsock2.h)

Article
10/13/2021

The WSASendDisconnect function initiates termination of the connection for the socket and sends disconnect data.

Syntax

int WSAAPI WSASendDisconnect(
  [in] SOCKET   s,
  [in] LPWSABUF lpOutboundDisconnectData
);

Parameters

[in] s

Descriptor identifying a socket.

[in] lpOutboundDisconnectData

A pointer to the outgoing disconnect data.

Return value

If no error occurs, WSASendDisconnect returns zero. Otherwise, a value of SOCKET_ERROR is returned, and a specific error code can be retrieved by calling WSAGetLastError.

Error code	Meaning
WSANOTINITIALISED	A successful WSAStartup call must occur before using this function.
WSAENETDOWN	The network subsystem has failed.
WSAENOPROTOOPT	The parameter lpOutboundDisconnectData is not NULL, and the disconnect data is not supported by the service provider.
WSAEINPROGRESS	A blocking Windows Sockets 1.1 call is in progress, or the service provider is still processing a callback function.
WSAENOTCONN	The socket is not connected (connection-oriented sockets only).
WSAENOTSOCK	The descriptor is not a socket.
WSAEFAULT	The lpOutboundDisconnectData parameter is not completely contained in a valid part of the user address space.

Remarks

The WSASendDisconnect function is used on connection-oriented sockets to disable transmission and to initiate termination of the connection along with the transmission of disconnect data, if any. This is equivalent to a shutdown (SD_SEND), except that WSASendDisconnect also allows sending disconnect data (in protocols that support it).

After this function has been successfully issued, subsequent sends are disallowed.

The lpOutboundDisconnectData parameter, if not NULL, points to a buffer containing the outgoing disconnect data to be sent to the remote party for retrieval by using WSARecvDisconnect.

Note The native implementation of TCP/IP on Windows does not support disconnect data. Disconnect data is only supported with Windows Sockets providers that have the XP1_DISCONNECT_DATA flag in their WSAPROTOCOL_INFO structure. Use the WSAEnumProtocols function to obtain WSAPROTOCOL_INFO structures for all installed providers.

The WSASendDisconnect function does not close the socket, and resources attached to the socket will not be freed until closesocket is invoked.

The WSASendDisconnect function does not block regardless of the SO_LINGER setting on the socket.

An application should not rely on being able to reuse a socket after calling WSASendDisconnect. In particular, a Windows Sockets provider is not required to support the use of connect/WSAConnect on such a socket.

Note When issuing a blocking Winsock call such as WSASendDisconnect, Winsock may need to wait for a network event before the call can complete. Winsock performs an alertable wait in this situation, which can be interrupted by an asynchronous procedure call (APC) scheduled on the same thread. Issuing another blocking Winsock call inside an APC that interrupted an ongoing blocking Winsock call on the same thread will lead to undefined behavior, and must never be attempted by Winsock clients.

Requirements

Requirement	Value
Minimum supported client	Windows 2000 Professional [desktop apps only]
Minimum supported server	Windows 2000 Server [desktop apps only]
Target Platform	Windows
Header	winsock2.h
Library	Ws2_32.lib
DLL	Ws2_32.dll