Co-authored-by: FloatingGhost <hannah@coffee-and-dreams.uk> Reviewed-on: https://akkoma.dev/AkkomaGang/akkoma/pulls/371
		
			
				
	
	
		
			85 lines
		
	
	
	
		
			2.6 KiB
		
	
	
	
		
			Elixir
		
	
	
	
	
	
			
		
		
	
	
			85 lines
		
	
	
	
		
			2.6 KiB
		
	
	
	
		
			Elixir
		
	
	
	
	
	
# Pleroma: A lightweight social networking server
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# Copyright © 2017-2021 Pleroma Authors <https://pleroma.social/>
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# SPDX-License-Identifier: AGPL-3.0-only
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defmodule Pleroma.Activity.HTML do
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  alias Pleroma.HTML
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  alias Pleroma.Object
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  @cachex Pleroma.Config.get([:cachex, :provider], Cachex)
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  # We store a list of cache keys related to an activity in a
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  # separate cache, scrubber_management_cache. It has the same
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  # size as scrubber_cache (see application.ex). Every time we add
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  # a cache to scrubber_cache, we update scrubber_management_cache.
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  #
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  # The most recent write of a certain key in the management cache
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  # is the same as the most recent write of any record related to that
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  # key in the main cache.
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  # Assuming LRW ( https://hexdocs.pm/cachex/Cachex.Policy.LRW.html ),
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  # this means when the management cache is evicted by cachex, all
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  # related records in the main cache will also have been evicted.
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  defp get_cache_keys_for(activity_id) do
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    with {:ok, list} when is_list(list) <- @cachex.get(:scrubber_management_cache, activity_id) do
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      list
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    else
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      _ -> []
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    end
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  end
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  defp add_cache_key_for(activity_id, additional_key) do
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    current = get_cache_keys_for(activity_id)
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    unless additional_key in current do
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      @cachex.put(:scrubber_management_cache, activity_id, [additional_key | current])
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    end
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  end
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  def invalidate_cache_for(activity_id) do
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    keys = get_cache_keys_for(activity_id)
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    for key <- keys do
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      @cachex.del(:scrubber_cache, key)
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    end
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    @cachex.del(:scrubber_management_cache, activity_id)
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  end
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  def get_cached_scrubbed_html_for_activity(
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        content,
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        scrubbers,
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        activity,
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        key \\ "",
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        callback \\ fn x -> x end
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      ) do
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    key = "#{key}#{generate_scrubber_signature(scrubbers)}|#{activity.id}"
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    @cachex.fetch!(:scrubber_cache, key, fn _key ->
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      object = Object.normalize(activity, fetch: false)
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      add_cache_key_for(activity.id, key)
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      HTML.ensure_scrubbed_html(content, scrubbers, object.data["fake"] || false, callback)
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    end)
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  end
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  def get_cached_stripped_html_for_activity(content, activity, key) do
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    get_cached_scrubbed_html_for_activity(
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      content,
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      FastSanitize.Sanitizer.StripTags,
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      activity,
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      key,
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      &HtmlEntities.decode/1
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    )
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  end
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  defp generate_scrubber_signature(scrubber) when is_atom(scrubber) do
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    generate_scrubber_signature([scrubber])
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  end
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  defp generate_scrubber_signature(scrubbers) do
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    Enum.reduce(scrubbers, "", fn scrubber, signature ->
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      "#{signature}#{to_string(scrubber)}"
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    end)
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  end
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end
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