I am hoping this is the right place to ask this question but if not please redirect me.
That's the right place :)
I am working on a custom C dissector and need to keep some data around for the lifetime of the current file. At the moment I allocate my structures using various wmem_ functions with a wmem_file_scope() scope and keep them in conversations with conversation_get_proto_data() and conversation_add_proto_data(). It works great for conversation-related data but is not ideal for file-related data.
The wmem file scope is definitely the right memory pool.
Is there a way for a dissector to know a new file is being worked on and it’s time to reinitialize data structures? Or is there an equivalent to conversation_get_proto_data() but for a file?
Did you look at the register_cleanup_routine() found in epan/packet.h? It seems to be what you are looking for. To quote the comments:
/**
* Allows protocols to register "cleanup" routines which are called
* after closing a capture file (or when preferences are changed, in
* that case these routines are called before the init routines are
* executed). It can be used to release resources that are allocated in
* register_init_routine.
*/
You can find multiple dissectors using it in our code base that should give you plenty of examples.
Best regards,
Pascal.
