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# frozen_string_literal: true
#
# Copyright, 2018, by Samuel G. D. Williams. <http://www.codeotaku.com>
#
# Permission is hereby granted, free of charge, to any person obtaining a copy
# of this software and associated documentation files (the "Software"), to deal
# in the Software without restriction, including without limitation the rights
# to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
# copies of the Software, and to permit persons to whom the Software is
# furnished to do so, subject to the following conditions:
#
# The above copyright notice and this permission notice shall be included in
# all copies or substantial portions of the Software.
#
# THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
# IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
# FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
# AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
# LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
# OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
# THE SOFTWARE.
require_relative 'writable'
require 'async/clock'
module Async
module HTTP
module Body
# A dynamic body which you can write to and read from.
class Slowloris < Writable
class ThroughputError < StandardError
def initialize(throughput, minimum_throughput, time_since_last_write)
super("Slow write: #{throughput.round(1)}bytes/s less than required #{minimum_throughput.round}bytes/s.")
end
end
# In order for this implementation to work correctly, you need to use a LimitedQueue.
# @param minimum_throughput [Integer] the minimum bytes per second otherwise this body will be forcefully closed.
def initialize(*arguments, minimum_throughput: 1024, **options)
super(*arguments, **options)
@minimum_throughput = minimum_throughput
@last_write_at = nil
@last_chunk_size = nil
end
attr :minimum_throughput
# If #read is called regularly to maintain throughput, that is good. If #read is not called, that is a problem. Throughput is dependent on data being available, from #write, so it doesn't seem particularly problimatic to do this check in #write.
def write(chunk)
if @last_chunk_size
time_since_last_write = Async::Clock.now - @last_write_at
throughput = @last_chunk_size / time_since_last_write
if throughput < @minimum_throughput
error = ThroughputError.new(throughput, @minimum_throughput, time_since_last_write)
self.close(error)
end
end
super.tap do
@last_write_at = Async::Clock.now
@last_chunk_size = chunk&.bytesize
end
end
end
end
end
end
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