How can I get request headers in their original format from Rack?

Question

I'm trying to get request headers in their original format from Rack using Ruby, but haven't been able to figure it out yet. The hash I get back from request.env isn't what I want. In that hash, the header keys are upcased and have underscores instead of dashes, like so:

"CONTENT_TYPE"=>"application/json; charset=utf-8"

What I want is the headers before they get processed, I'm looking for:

"Content_Type"=>"application/json; charset=utf-8"

I can easily enough loop through request.env looking for headers that start with HTTP_ and split them, capitalize each word and gsub to replace underscores with dashes to get them into the format I want. It becomes trickier to retain original format this way when dealing with headers such as:

"X-BT-RequestId"

I feel that I ought to be able to get at the pre-processed headers somehow.

I'm writing a HTTP listener that will wrap a request and forward it on to another service and I want to preserve headers in their original format. I know headers are supposed to be case insensitive, but if I can forward them in their original format, I can hopefully prevent case-sensitive issues later on when my database users are querying for values based on these headers.

Any ideas?

Answer 1

You can get the raw headers in webrick/httpserver.rb from the raw_header instance variable of WEBrick::HTTPRequest:

p req.instance_variable_get("@raw_header")
si.service(req, res)

You can also get it from inside the service method in handler/webrick.rb.