128 lines
4.4 KiB
Ruby
128 lines
4.4 KiB
Ruby
# frozen_string_literal: true
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# Gitlab::Middleware::Multipart - a Rack::Multipart replacement
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#
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# Rack::Multipart leaves behind tempfiles in /tmp and uses valuable Ruby
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# process time to copy files around. This alternative solution uses
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# gitlab-workhorse to clean up the tempfiles and puts the tempfiles in a
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# location where copying should not be needed.
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#
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# When gitlab-workhorse finds files in a multipart MIME body it sends
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# a signed message via a request header. This message lists the names of
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# the multipart entries that gitlab-workhorse filtered out of the
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# multipart structure and saved to tempfiles. Workhorse adds new entries
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# in the multipart structure with paths to the tempfiles.
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#
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# The job of this Rack middleware is to detect and decode the message
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# from workhorse. If present, it walks the Rack 'params' hash for the
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# current request, opens the respective tempfiles, and inserts the open
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# Ruby File objects in the params hash where Rack::Multipart would have
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# put them. The goal is that application code deeper down can keep
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# working the way it did with Rack::Multipart without changes.
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#
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# CAVEAT: the code that modifies the params hash is a bit complex. It is
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# conceivable that certain Rack params structures will not be modified
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# correctly. We are not aware of such bugs at this time though.
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#
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module Gitlab
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module Middleware
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class Multipart
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RACK_ENV_KEY = 'HTTP_GITLAB_WORKHORSE_MULTIPART_FIELDS'
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class Handler
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def initialize(env, message)
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@request = Rack::Request.new(env)
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@rewritten_fields = message['rewritten_fields']
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@open_files = []
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end
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def with_open_files
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@rewritten_fields.each do |field, tmp_path|
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parsed_field = Rack::Utils.parse_nested_query(field)
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raise "unexpected field: #{field.inspect}" unless parsed_field.count == 1
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key, value = parsed_field.first
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if value.nil?
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value = open_file(@request.params, key)
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@open_files << value
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else
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value = decorate_params_value(value, @request.params[key])
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end
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update_param(key, value)
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end
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yield
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ensure
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@open_files.each(&:close)
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end
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# This function calls itself recursively
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def decorate_params_value(path_hash, value_hash)
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unless path_hash.is_a?(Hash) && path_hash.count == 1
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raise "invalid path: #{path_hash.inspect}"
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end
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path_key, path_value = path_hash.first
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unless value_hash.is_a?(Hash) && value_hash[path_key]
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raise "invalid value hash: #{value_hash.inspect}"
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end
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case path_value
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when nil
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value_hash[path_key] = open_file(value_hash.dig(path_key), '')
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@open_files << value_hash[path_key]
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value_hash
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when Hash
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decorate_params_value(path_value, value_hash[path_key])
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value_hash
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else
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raise "unexpected path value: #{path_value.inspect}"
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end
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end
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def open_file(params, key)
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allowed_paths = [
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::FileUploader.root,
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Gitlab.config.uploads.storage_path,
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File.join(Rails.root, 'public/uploads/tmp')
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]
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::UploadedFile.from_params(params, key, allowed_paths)
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end
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# update_params ensures that both rails controllers and rack middleware can find
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# workhorse accelerate files in the request
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def update_param(key, value)
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# we make sure we have key in POST otherwise update_params will add it in GET
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@request.POST[key] ||= value
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# this will force Rack::Request to properly update env keys
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@request.update_param(key, value)
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# ActionDispatch::Request is based on Rack::Request but it caches params
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# inside other env keys, here we ensure everything is updated correctly
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ActionDispatch::Request.new(@request.env).update_param(key, value)
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end
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end
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def initialize(app)
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@app = app
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end
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def call(env)
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encoded_message = env.delete(RACK_ENV_KEY)
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return @app.call(env) if encoded_message.blank?
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message = Gitlab::Workhorse.decode_jwt(encoded_message)[0]
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Handler.new(env, message).with_open_files do
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@app.call(env)
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end
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end
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end
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end
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end
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