I'm looking at integrating multipart form-data parsing in a web server module so that I can relieve backend web applications (often written in dynamic languages) from parsing the multipart data themselves. The multipart grammar (RFC 2046) looks non-trivial and if I implement it by hand a lot of things can go wrong. Is there already a good, lightweight multipart/form-data parser written in C or C++? I'm looking for one with no external dependencies other than the C or C++ standard library. I don't need email attachment handling or buffered I/O classes or a portability runtime or whatever, just multipart/form-data parsing.
Things that I've considered:
I've also looked at writing a parser with Ragel, but I can't figure out how to do it because the grammar is not static: the boundary can change arbitrarily.
I know this question is a couple of years old now, but I needed the same and ended up using this: