Custom methods should be supported

[nazar-pc]

Initially reported here: nghttp2/nghttp2#602

I see in sources big switch with hardcoded HTTP methods and rejects any custom methods, however, there is nothing in specs that forbids usage of custom methods (see referred issue for examples).

[indutny]

@nazar-pc what about Content-Length and Transfer-Encoding should it be accepted for custom methods, or should we reject methods that pass them? There are some protocol driven semantics that may be very important to implement additional methods.

[nazar-pc]

I do not think there is something fundamentally different here.
As per https://tools.ietf.org/html/rfc7231#section-4 I suppose methods not listed in spec are:

• not safe
• not idempotent
• not cacheable (I feel like caching might actually apply if corresponding headers are present though)

Content-Length and Transfer-Encoding do not seem to be specifically tied to methods. So I'd expect custom methods to support them if present. This is what Apache2 and Nginx at least both do in practice and modern browsers also do not have any issues with this. So I'm using custom methods in API when sending AJAX requests sometimes with request body, sometimes without. When body is present there is correct Content-Length, if no body - Content-Length header is not present at all.

[indutny]

What about Upgrade header? Should it still work as usual with custom methods?

Is it safe to assume that there are no "no-body" methods like HEAD?

[nazar-pc]

I'm completely confident about Upgrade. It is allowed for some other methods besides GET? Didn't found anything about this.

I think yes, HEAD is pretty special in this meaning, but, obviously, response might have empty body.

[tatsuhiro-t]

If we pretend that custom methods do not require special treatment of HEAD, then we can follow the rule described in https://tools.ietf.org/html/rfc7230#section-3.3.3, to determine the content length.
Of course, this would break if someone standardizes new method which requires special treatment like HEAD or CONNECT.

[tatsuhiro-t]

Here is my PoC #311
I made nghttpx proxy use this new on_method callback, and it works fine.

[Fr0sT-Brutal]

Any changes on this? Can't wait to see this update applied to have Node parse custom headers.