90 lines
2.8 KiB
Ruby
90 lines
2.8 KiB
Ruby
# frozen_string_literal: true
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# This module allows us to hijack a request and send it to the client in the deferred job queue
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# For cases where we are making remote calls like onebox or proxying files and so on this helps
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# free up a unicorn worker while the remote IO is happening
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module Hijack
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def hijack(&blk)
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controller_class = self.class
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if hijack = request.env['rack.hijack']
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request.env['discourse.request_tracker.skip'] = true
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request_tracker = request.env['discourse.request_tracker']
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# unicorn will re-cycle env, this ensures we keep the original copy
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env_copy = request.env.dup
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request_copy = ActionDispatch::Request.new(env_copy)
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transfer_timings = MethodProfiler.transfer if defined? MethodProfiler
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io = hijack.call
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Scheduler::Defer.later("hijack #{params["controller"]} #{params["action"]}") do
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MethodProfiler.start(transfer_timings) if defined? MethodProfiler
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begin
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# do this first to confirm we have a working connection
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# before doing any work
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io.write "HTTP/1.1 "
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# this trick avoids double render, also avoids any litter that the controller hooks
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# place on the response
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instance = controller_class.new
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response = ActionDispatch::Response.new
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instance.response = response
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instance.request = request_copy
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begin
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instance.instance_eval(&blk)
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rescue => e
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Rails.logger.warn("Failed to process hijacked response correctly #{e}")
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end
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unless instance.response_body || response.committed?
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instance.status = 500
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end
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response.commit!
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body = response.body
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headers = response.headers
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headers['Content-Length'] = body.bytesize
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headers['Content-Type'] = response.content_type || "text/plain"
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headers['Connection'] = "close"
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status_string = Rack::Utils::HTTP_STATUS_CODES[instance.status.to_i] || "Unknown"
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io.write "#{instance.status} #{status_string}\r\n"
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headers.each do |name, val|
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io.write "#{name}: #{val}\r\n"
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end
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io.write "\r\n"
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io.write body
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rescue Errno::EPIPE, IOError
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# happens if client terminated before we responded, ignore
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io = nil
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ensure
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io.close if io rescue nil
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if request_tracker
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status = instance.status rescue 500
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timings = MethodProfiler.stop if defined? MethodProfiler
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request_tracker.log_request_info(env_copy, [status, headers || {}, []], timings)
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end
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end
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end
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# not leaked out, we use 418 ... I am a teapot to denote that we are hijacked
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render plain: "", status: 418
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else
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blk.call
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end
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end
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end
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