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   1 # Pleroma: A lightweight social networking server
   2 # Copyright © 2017-2020 Pleroma Authors <https://pleroma.social/>
   3 # SPDX-License-Identifier: AGPL-3.0-only
   4
   5 defmodule Pleroma.Web.RichMedia.Parser.TTL.AwsSignedUrl do
   6   @behaviour Pleroma.Web.RichMedia.Parser.TTL
   7
   8   @impl Pleroma.Web.RichMedia.Parser.TTL
   9   def ttl(data, _url) do
  10     image = Map.get(data, :image)
  11
  12     if is_aws_signed_url(image) do
  13       image
  14       |> parse_query_params()
  15       |> format_query_params()
  16       |> get_expiration_timestamp()
  17     else
  18       {:error, "Not aws signed url #{inspect(image)}"}
  19     end
  20   end
  21
  22   defp is_aws_signed_url(image) when is_binary(image) and image != "" do
  23     %URI{host: host, query: query} = URI.parse(image)
  24
  25     String.contains?(host, "amazonaws.com") and String.contains?(query, "X-Amz-Expires")
  26   end
  27
  28   defp is_aws_signed_url(_), do: nil
  29
  30   defp parse_query_params(image) do
  31     %URI{query: query} = URI.parse(image)
  32     query
  33   end
  34
  35   defp format_query_params(query) do
  36     query
  37     |> String.split(~r/&|=/)
  38     |> Enum.chunk_every(2)
  39     |> Map.new(fn [k, v] -> {k, v} end)
  40   end
  41
  42   defp get_expiration_timestamp(params) when is_map(params) do
  43     {:ok, date} =
  44       params
  45       |> Map.get("X-Amz-Date")
  46       |> Timex.parse("{ISO:Basic:Z}")
  47
  48     {:ok, Timex.to_unix(date) + String.to_integer(Map.get(params, "X-Amz-Expires"))}
  49   end
  50 end