WSAEnumNetworkEvents (Windows CE 5.0)

Windows CE 5.0
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This function discovers occurrences of network events for the indicated socket, clear internal network event records, and reset event objects (optional).

int WSAEnumNetworkEvents(
  WSAEVENT hEventObject,


[in] Descriptor identifying the socket.
[in] Optional handle identifying an associated event object to be reset.
[out] Pointer to a WSANETWORKEVENTS structure that is filled with a record of network events that occurred and any associated error codes.

Return Values

If no error occurs, this function returns zero. If an error occurs, the value SOCKET_ERROR is returned, and a specific error number can be retrieved by calling WSAGetLastError. The following table shows a list of possible error codes.

Error code Description
WSANOTINITIALISED A successful WSAStartup call must occur before using this function.
WSAENETDOWN The network subsystem has failed.
WSAEINVAL One of the specified parameters was invalid.
WSAEINPROGRESS A blocking Winsock call is in progress, or the service provider is still processing a callback function.
WSAENOTSOCK The descriptor is not a socket.
WSAEFAULT The lpNetworkEvents argument is not a valid part of the user address space.


This function is used to discover which network events have occurred for the indicated socket since the last invocation of this function. It is intended for use in conjunction with the WSAEventSelect function, which associates an event object with one or more network events. The recording of network events commences when WSAEventSelect is called with a nonzero lNetworkEvents parameter and remains in effect until another call is made to WSAEventSelect with the lNetworkEvents parameter set to zero.

WSAEnumNetworkEvents only reports network activity and errors nominated through WSAEventSelect. See the descriptions of select to find out how those functions report network activity and errors.

The socket's internal record of network events is copied to the structure referenced by lpNetworkEvents, after which the internal network events record is cleared. If the hEventObject parameter is not NULL, the indicated event object is also reset. The Windows Sockets provider guarantees that the operations of copying the network event record, clearing it and resetting any associated event object are automatic, such that the next occurrence of a nominated network event will cause the event object to become set. In the case of this function returning SOCKET_ERROR, the associated event object is not reset and the record of network events is not cleared.

The lNetworkEvents member of the WSANETWORKEVENTS structure indicates which of the FD_XXX network events have occurred. The iErrorCode array is used to contain any associated error codes with the array index corresponding to the position of event bits in lNetworkEvents. Identifiers such as FD_READ_BIT and FD_WRITE_BIT can be used to index the iErrorCode array. Note that only those elements of the iErrorCode array are set that correspond to the bits set in lNetworkEvents parameter. Other parameters are not modified, which is important for backward compatibility with the applications that are not aware of new FD_ROUTING_INTERFACE_CHANGE and FD_ADDRESS_LIST_CHANGE events.

The following error codes can be returned along with the corresponding network event.


Error Description
WSAEAFNOSUPPORT Addresses in the specified family cannot be used with this socket.
WSAECONNREFUSED The attempt to connect was forcefully rejected.
WSAENETUNREACH The network cannot be reached from this host at this time.
WSAENOBUFS No buffer space is available. The socket cannot be connected.
WSAETIMEDOUT Attempt to connect timed out without establishing a connection


Error Description
WSAENETDOWN The network subsystem has failed.
WSAECONNRESET The connection was reset by the remote side.
WSAECONNABORTED The connection was terminated due to a time-out or other failure.

Event: FD_READ


Event: FD_OOB



Error Description
WSAENETDOWN The network subsystem has failed.


Error Description
WSAENETUNREACH The specified destination is no longer reachable.
WSAENETDOWN The network subsystem has failed.


OS Versions: Windows CE .NET 4.0 and later.
Header: Winsock2.h.
Link Library: Ws2.lib.

See Also

select | WSAEventSelect | WSAGetLastError | WSAStartup

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