Bridge USB host to device

In a nutshell, I'm developing an embedded system that requires, amongst other things, a bridge from a USB host port to a device port (this is just a first step, later the information transmitted will be filtered and altered).

Considering that this is basically a USB snooper/sniffer I figured that someone should have written a module capable of this, but my search has proven futile.

So, to the question: What's the simplest way to redirect a USB host to a USB device in Linux? The data must be identical, all descriptors and endpoints must match. It must be Linux friendly, I can code in C/C++ and have some experience with coding kernel modules, drivers, etc.