Can We initilize Winsock in DLL_DETACH ? actulay i want to send some data when a process get terminated(DLL_DETACH)

Question

Can We initialize Win sock in DLL_DETACH ? actulay i want to send some data when a process get terminated(DLL_DETACH)

Answer 1

DLL_DETACH is actually DLL_PROCESS_DETACH.

It is possible (i don't think that's any mechanism to prevent it) but it's not recommended. WSAStartup lies in ws2_32.dll. Here's a fragment from DllMain official doc (Remarks section):

Calling functions that require DLLs other than Kernel32.dll may result in problems that are difficult to diagnose. For example, calling User, Shell, and COM functions can cause access violation errors, because some functions load other system components. Conversely, calling functions such as these during termination can cause access violation errors because the corresponding component may already have been unloaded or uninitialized.

Also, from WSAStartup official doc (same Remarks section):

The WSAStartup function typically leads to protocol-specific helper DLLs being loaded. As a result, the WSAStartup function should not be called from the DllMain function in a application DLL. This can potentially cause deadlocks. For more information, please see the DLL Main Function.

As an alternative sending the data (including the overhead of initializing the socket engine, creating the connection, and uninitializing the socket engine) could be achieved at the end of main (WinMain).

Answer 2

Calling WSAStartup() in DllMain() will result in a deadlock due to the loader lock. WSAStartup() can result in DLLs being loaded.

A better solution would be to install a service that can do the sending for. Talk to the service from DllMain() using your preferred interprocess comms method (shared memory, named pipes, etc).