Question

I’m developing an application that uses windows sockets. My socket class has a method named Disconnect that uses DisconnectEx, but i get the following error at linking time:

undefined reference to `DisconnectEx@16'

I’m using MinGW and i’m linking my application with the following libs:

-lws2_32 -lwsock32 -lmswsock

On msdn says that the minimum version required for this function is Windows XP or Windows Server 2003, so i defined WINVER with 0x0502, but i still get the same error.

What i’m missing here?

Thanks in advance!

Answer 1

What you apparently missed is this note in the MSDN documentation for the DisconnectEx() function:

Note: The function pointer for the DisconnectEx function must be
obtained at run time by making a call to the WSAIoctl function with
the SIO_GET_EXTENSION_FUNCTION_POINTER opcode specified. The input
buffer passed to the WSAIoctl function must contain
WSAID_DISCONNECTEX, a globally unique identifier (GUID) whose value
identifies the DisconnectEx extension function. On success, the
output returned by the WSAIoctl function contains a pointer to the
DisconnectEx function. The WSAID_DISCONNECTEX GUID is defined in
the Mswsock.h header file.

Note that the MSDN documentation for DisconnectEx() doesn’t specify a library under the Requirements section. That implies that you have to load this function dynamically at runtime via the WSAIoctl()function to obtain a function pointer.