Method: Rack::Cors#call

Defined in:
lib/rack/cors.rb

#call(env) ⇒ Object

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# File 'lib/rack/cors.rb', line 66

def call(env)
  env[HTTP_ORIGIN] ||= env[HTTP_X_ORIGIN] if env[HTTP_X_ORIGIN]

  path = evaluate_path(env)

  add_headers = nil
  if env[HTTP_ORIGIN]
    debug(env) do
      ['Incoming Headers:',
       "  Origin: #{env[HTTP_ORIGIN]}",
       "  Path-Info: #{path}",
       "  Access-Control-Request-Method: #{env[HTTP_ACCESS_CONTROL_REQUEST_METHOD]}",
       "  Access-Control-Request-Headers: #{env[HTTP_ACCESS_CONTROL_REQUEST_HEADERS]}"].join("\n")
    end

    if env[REQUEST_METHOD] == OPTIONS && env[HTTP_ACCESS_CONTROL_REQUEST_METHOD]
      return [400, {}, []] unless Rack::Utils.valid_path?(path)

      headers = process_preflight(env, path)
      debug(env) do
        "Preflight Headers:\n" +
          headers.collect { |kv| "  #{kv.join(': ')}" }.join("\n")
      end
      return [200, headers, []]
    else
      add_headers = process_cors(env, path)
    end
  else
    Result.miss(env, Result::MISS_NO_ORIGIN)
  end

  # This call must be done BEFORE calling the app because for some reason
  # env[PATH_INFO] gets changed after that and it won't match. (At least
  # in rails 4.1.6)
  vary_resource = resource_for_path(path)

  status, headers, body = @app.call env

  if add_headers
    headers = add_headers.merge(headers)
    debug(env) do
      add_headers.each_pair do |key, value|
        headers["x-rack-cors-original-#{key}"] = value if headers.key?(key)
      end
    end
  end

  # Vary header should ALWAYS mention Origin if there's ANY chance for the
  # response to be different depending on the Origin header value.
  # Better explained here: http://www.fastly.com/blog/best-practices-for-using-the-vary-header/
  if vary_resource
    vary = headers['vary']
    cors_vary_headers = if vary_resource.vary_headers&.any?
                          vary_resource.vary_headers
                        else
                          DEFAULT_VARY_HEADERS
                        end
    headers['vary'] = ((vary ? [vary].flatten.map { |v| v.split(/,\s*/) }.flatten : []) + cors_vary_headers).uniq.join(', ')
  end

  result = env[ENV_KEY]
  result.append_header(headers) if debug? && result

  [status, headers, body]
end