Response with multiple `Transfer-Encoding: chunked` header fields not parsed as chunk

[nham]

I've adapted this code from client/response.rs:

fn main() {
    let stream = MockStream::with_input(b"\
        HTTP/1.1 200 OK\r\n\
        Transfer-Encoding: chunked\r\n\
        Transfer-Encoding: chunked\r\n\
        \r\n\
        1\r\n\
        q\r\n\
        2\r\n\
        we\r\n\
        2\r\n\
        rt\r\n\
        0\r\n\
        \r\n"
    );

    let url = Url::parse("http://hyper.rs").unwrap();
    let mut res = Response::new(url, Box::new(stream)).unwrap();

    let mut s = String::new();
    res.read_to_string(&mut s).unwrap();
    println!("{:?}", s);
}

The result is:

"1\r\nq\r\n2\r\nwe\r\n2\r\nrt\r\n0\r\n\r\n"

Unless I'm misreading the HTTP spec, it seems

HTTP/1.1 200 OK\r\n
Transfer-Encoding: chunked\r\n
Transfer-Encoding: chunked\r\n

should be the same as

HTTP/1.1 200 OK\r\n
Transfer-Encoding: chunked, chunked\r\n

The latter correctly results in "qwert" being printed out.

[seanmonstar]

Indeed, it would seem the bug is in the parsing of the TransferEncoding header. It should handle more than 1 field occurrence.

[dignifiedquire]

@seanmonstar I'm running into this issue myself, but I'm not sure how/where to best fix it. Any pointers where I should start looking?

[seanmonstar]

This occurs in the parsing. TransferEncoding uses parsing::from_comma_delimited(), which currently only allows 1 line of a header.

I cannot recall if there are any headers that are comma separated but should be rejected if there is more than one line. If not, then the fix would be in the from_comma_delimited method to check all the lines, not just the first.

[pyfisch]

I have written a parser for comma-delimited headers that should catch all cases like multiline headers, too much whitespace and superfluos commas.
https://github.com/pyfisch/kinglet/blob/master/src/headers.rs#L54-L100