pcapng offers you a a pcapng parser in native rust code. A couple of variations on how to read pcapng files in from a file are in examples/.

Under the hood, it usees nom to implement it's parsing, which lets this library stay small and compact. It's currently in a very unstable state, and I'll probably shuffle a lot of interfaces around (Especially surrounding where the actual Block classes live), but if you build something atop it, please let me know and I'll attempt to accomodate.

At the highest level, the easiest way to get packets is to read the whole pcapng file into memory, and then run the parser over it:

let mut fh = fs::File::open("filename.pcapng").unwrap();
let mut buf: Vec<u8> = Vec::new();
let read = fh.read_to_end(&mut buf);
match pcapng::block::parse_blocks(&buf[..]) {
    IResult::Done(_, blocks) => {
        for i in blocks {
            println!("{:?}", i.parse());
        }
    }
    IResult::Error(e)      => panic!("Error: {:?}", e),
    IResult::Incomplete(i) => panic!("Incomplete: {:?}", i),
}

Other approaches using the actual Consumer infra are preferable if you want to stream, but involve writing much more code.

If you're using this, I would love to know. I'm reachable as richo on freenode or mozilla's irc.

Released under the terms of the MIT license.