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71 lines
3 KiB
Ruby
71 lines
3 KiB
Ruby
# frozen_string_literal: true
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require "action_dispatch/middleware/exception_wrapper"
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module ActionDispatch
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# This middleware rescues any exception returned by the application
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# and calls an exceptions app that will wrap it in a format for the end user.
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#
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# The exceptions app should be passed as parameter on initialization
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# of ShowExceptions. Every time there is an exception, ShowExceptions will
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# store the exception in env["action_dispatch.exception"], rewrite the
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# PATH_INFO to the exception status code and call the Rack app.
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#
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# If the application returns a "X-Cascade" pass response, this middleware
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# will send an empty response as result with the correct status code.
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# If any exception happens inside the exceptions app, this middleware
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# catches the exceptions and returns a failsafe response.
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class ShowExceptions
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def initialize(app, exceptions_app)
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@app = app
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@exceptions_app = exceptions_app
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end
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def call(env)
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request = ActionDispatch::Request.new env
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@app.call(env)
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rescue Exception => exception
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if request.show_exceptions?
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render_exception(request, exception)
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else
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raise exception
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end
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end
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private
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def render_exception(request, exception)
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backtrace_cleaner = request.get_header "action_dispatch.backtrace_cleaner"
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wrapper = ExceptionWrapper.new(backtrace_cleaner, exception)
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status = wrapper.status_code
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request.set_header "action_dispatch.exception", wrapper.unwrapped_exception
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request.set_header "action_dispatch.original_path", request.path_info
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request.set_header "action_dispatch.original_request_method", request.raw_request_method
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fallback_to_html_format_if_invalid_mime_type(request)
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request.path_info = "/#{status}"
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request.request_method = "GET"
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response = @exceptions_app.call(request.env)
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response[1]["X-Cascade"] == "pass" ? pass_response(status) : response
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rescue Exception => failsafe_error
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$stderr.puts "Error during failsafe response: #{failsafe_error}\n #{failsafe_error.backtrace * "\n "}"
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[500, { "Content-Type" => "text/plain" },
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["500 Internal Server Error\n" \
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"If you are the administrator of this website, then please read this web " \
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"application's log file and/or the web server's log file to find out what " \
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"went wrong."]]
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end
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def fallback_to_html_format_if_invalid_mime_type(request)
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# If the MIME type for the request is invalid then the
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# @exceptions_app may not be able to handle it. To make it
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# easier to handle, we switch to HTML.
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request.formats
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rescue ActionDispatch::Http::MimeNegotiation::InvalidType
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request.set_header "HTTP_ACCEPT", "text/html"
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end
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def pass_response(status)
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[status, { "Content-Type" => "text/html; charset=#{Response.default_charset}", "Content-Length" => "0" }, []]
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end
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end
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end
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