libalias unused var fix proposal

[devnexen_gmail.com]

Summary

reusing find_handler return for UDP/TCP

[donner]

Only alias_nbt.c may return any negative result. Even if no handler is suitable, the returned value from alias_mod.c would be positive (2). Every other handler always returns zero.

So the question is, what's the result of passing through a packet which can't be handled by a special purpose handler? Is it better to send out the packet with the un-natted original IP addresses or should be packet be processed without any internal inspection? Is PKT_ALIAS_ERROR more appropriate?