How do boundaries work in multipart post requests?

Question

I trying to upload a file from an iPhone to a server. I'm trying to avoid using any libraries that aren't made by apple, and from what I can tell it looks like I'll need to go pretty low level on constructing my request. Can someone tell me what the "boundary" is in a multipart/form-data request and how to use it properly?

Answer 1

Here's the IETF Form-based File Upload in HTML RFC.