Cant read json request params if content-length header not set

[lamyseba]

Hi ! I'm trying to connect my roda app to an external webhook. The external website sends me a "POST" request, with json in the body (request header "CONTENT_TYPE"=>"application/json"). I do not control the request it is sending, and sometimes the "CONTENT_LENGTH" header is set, sometimes not. If it isn't, trying to access request.params will make Roda halt the request and returns a 400 status without throwing any exception.

I then configured my app to use invalid_request_body plugin

plugin :invalid_request_body, :raise

With no success. Still request halt, still no exceptions.

Getting the exception is not my main goal, through : I just want to be able to read the request.params even if "CONTENT_LENGTH" is not set. (I was hopping an exception could have this params embedded somewhere in it.).

Any help welcome ! I'm stuck.

[jeremyevans]

My guess is you are using the json_parser plugin. If so, you probably want to provide the :error_handler plugin option to specify how to handle errors. The default is an empty 400 response. You may also want to provide a :json_parser option, so you can see the request body that was read:

plugin :json_parser, error_handler: proc { raise $! }, parser: proc{|body| p body; JSON.parse(body)}

If I had to guess, attempting to read the JSON input returns an empty string or nil, and then parsing that as JSON fails.

If that isn't it, can you provide a minimal self-contained reproducible example showing this issue (or a failing spec)?

[lamyseba]

Thank you very much @jeremyevans for your answer.

With your suggestion I could have some debug info and see the body of the request. It turns out this is a Phusion Passenger Bug. When sending data to this server with no content-length header and transfer-encoding: chunked header, Phusion Passenger does not strip out the content length informations from the body when it transmits request to roda app.

"chunked" transfer means that the requester does not tell the total content-length of its request. Instead it send body in packets, giving packet length at the beginning of each. The last packet you send must have no content and a length of zero.

So the json body that Phusion Passenger passed to my app looked like :

45
{
     "email": "email@email.com",
     "event": "unsubscribe"
}
0

As you can see, the "content-length" infos "45" (at the beginning) and "0" (at the end) are able to get you into trouble when trying to parse json.

So, I could not reproduce this bug in my dev environment where server is webrick.

Think I should open a bug at Phusion Passenger, and meanwhile manually strip this infos for simple short requests with just one packet like this one.

[lamyseba]

Opened the bug here: phusion/passenger#2632