`Request::parse()` accepts invalid methods.

[maxbailly]

This issue seems to be related to #161.

---

Consider this example :

#[test]
fn invalid_methods() {
    let src = "\"some,unvalid%GET{}:; / HTTP/1.1\r\nHost: 127.0.0.1:80\r\n\r\n";

    let mut headers = [httparse::EMPTY_HEADER; 32];
    let mut req = httparse::Request::new(&mut headers);

    let status = req.parse(src.as_bytes()).unwrap();
    assert!(status.is_complete());
    assert_eq!(req.method, Some("\"some,unvalid%GET{}:;"))
}

From the MDN and my understanding of the RFC, methods MUST be defined by the following grammar:

tchar = "!" / "#" / "$" / "%" / "&" / "'" / "*" / "+" / "-" / "." /
        "^" / "_" / "`" / "|" / "~" / DIGIT / ALPHA

[nikneym]

AFAIK this is intentional to support user-defined HTTP methods.

[maxbailly]

Took a look at the RFC 2616 which gives the following grammar rule in the 5.1.1 section regarding HTTP methods (including user-defined ones):

Method         = "OPTIONS"
                      | "GET"
                      | "HEAD"
                      | "POST"
                      | "PUT"
                      | "DELETE"
                      | "TRACE" 
                      | "CONNECT"
                      | extension-method
       extension-method = token

The token grammar is defined in the 2.2 section as:

       token          = 1*<any CHAR except CTLs or separators>
       separators     = "(" | ")" | "<" | ">" | "@"
                      | "," | ";" | ":" | "\" | <">
                      | "/" | "[" | "]" | "?" | "="
                      | "{" | "}" | SP | HT

My previous example contained characters that were separators and AFAIU, the parse() method should have rejected it but here's another example where all of the method's characters are separators:

#[test]
fn invalid_methods() {
    let src = "()<>@,;:\\\"/[]?={} / HTTP/1.1\r\nHost: 127.0.0.1:80\r\n\r\n";

    let mut headers = [httparse::EMPTY_HEADER; 32];
    let mut req = httparse::Request::new(&mut headers);

    let status = req.parse(src.as_bytes()).unwrap();
    assert!(status.is_complete());
    assert_eq!(req.method, Some("()<>@,;:\\\"/[]?={}"))
}