92 lines
2.4 KiB
Elixir
92 lines
2.4 KiB
Elixir
# Pleroma: A lightweight social networking server
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# Copyright © 2017-2019 Pleroma Authors <https://pleroma.social/>
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# SPDX-License-Identifier: AGPL-3.0-only
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defmodule Pleroma.Web.MediaProxy do
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@base64_opts [padding: false]
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def url(nil), do: nil
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def url(""), do: nil
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def url("/" <> _ = url), do: url
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def url(url) do
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if !enabled?() or local?(url) or whitelisted?(url) do
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url
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else
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encode_url(url)
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end
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end
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defp enabled?, do: Pleroma.Config.get([:media_proxy, :enabled], false)
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defp local?(url), do: String.starts_with?(url, Pleroma.Web.base_url())
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defp whitelisted?(url) do
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%{host: domain} = URI.parse(url)
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Enum.any?(Pleroma.Config.get([:media_proxy, :whitelist]), fn pattern ->
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String.equivalent?(domain, pattern)
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end)
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end
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def encode_url(url) do
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secret = Pleroma.Config.get([Pleroma.Web.Endpoint, :secret_key_base])
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# Must preserve `%2F` for compatibility with S3
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# https://git.pleroma.social/pleroma/pleroma/issues/580
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replacement = get_replacement(url, ":2F:")
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# The URL is url-decoded and encoded again to ensure it is correctly encoded and not twice.
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base64 =
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url
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|> String.replace("%2F", replacement)
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|> URI.decode()
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|> URI.encode()
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|> String.replace(replacement, "%2F")
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|> Base.url_encode64(@base64_opts)
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sig = :crypto.hmac(:sha, secret, base64)
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sig64 = sig |> Base.url_encode64(@base64_opts)
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build_url(sig64, base64, filename(url))
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end
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def decode_url(sig, url) do
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secret = Pleroma.Config.get([Pleroma.Web.Endpoint, :secret_key_base])
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sig = Base.url_decode64!(sig, @base64_opts)
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local_sig = :crypto.hmac(:sha, secret, url)
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if local_sig == sig do
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{:ok, Base.url_decode64!(url, @base64_opts)}
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else
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{:error, :invalid_signature}
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end
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end
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def filename(url_or_path) do
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if path = URI.parse(url_or_path).path, do: Path.basename(path)
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end
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def build_url(sig_base64, url_base64, filename \\ nil) do
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[
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Pleroma.Config.get([:media_proxy, :base_url], Pleroma.Web.base_url()),
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"proxy",
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sig_base64,
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url_base64,
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filename
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]
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|> Enum.filter(fn value -> value end)
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|> Path.join()
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end
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defp get_replacement(url, replacement) do
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if String.contains?(url, replacement) do
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get_replacement(url, replacement <> replacement)
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else
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replacement
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end
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end
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end
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