3D Find Intersection in Rectangular Prism With Directional Vector


While writing a script to resolve 3D collisions, I encountered a problem and I can't quite figure it out!

I have a rectangular prism with varying width, height and depth. I also have a point located within this prism (A) and a normalized directional vector (d).
If a ray is cast from A and travels along the directional vector d, how do I calculate the point (B) where this ray intersects the outer bounds of the prism?

Any tips would be greatly appreciated :)