Error on a Sinatra's middleware - ruby

Question

In my Sinatra app, I've created the following middleware to ensure the incoming request contains the parameter "token" in the query string
class CheckMandatoryParams
def initialize(app)
#app = app
end
def call(env)
# Get token from query string
h = Hash[*env["QUERY_STRING"].split('&').map {|s| s.split('=')}.flatten]
token = h["token"]
# Do not authorize request unless both parameters are not null
if token.nil? then
Log.instance.error("CheckMandatoryParams - token not provided")
[401, {"Content-Type" => "text/plain", "Content-Length" => body.length.to_s}, ["Unauthorized"]]
else
Log.instance.debug("CheckMandatoryParams - token provided")
#app.call(env)
end
end
end
In the case the params exists, the next app is calls and everything goes fine.
In the case the params is not in the query string, the response is not sent, I receive a huge html file indicating an error at the line ' [401, {"Content-Type" => "text/plain", "Content-Length" => body.length.to_s}, ["Unauthorized"]]' but I cannot figure out what is wrong.
Any idea?
UPDATE
This is working better like that :)
body = "Unauthorized"
[401, {"Content-Type" => "text/plain", "Content-Length" => body.length.to_s}, [body]]
I did not manage to retrieve the param with the following code though:
request = Rack::Request.new(env)
token = request.params["token"]

Answer 1

It looks like the "body" variable may be undefined. One possible way to rewrite your code would be as follows:
class CheckMandatoryParams
def initialize(app)
#app = app
end
def call(env)
request = Rack::Request.new(env)
token = request.params["token"]
if token.nil?
[401, {"Content-Type" => "text/plain", "Content-Length" => request.body.length.to_s}, ["Unauthorized"]]
else
#app.call(env)
end
end
end