Merge remote-tracking branch 'upstream/develop' into admin-create-users

[akkoma] / lib / pleroma / web / media_proxy / media_proxy.ex

diff --git a/lib/pleroma/web/media_proxy/media_proxy.ex b/lib/pleroma/web/media_proxy/media_proxy.ex
index 0fc0a07b269d3bb6af0baf5897e73ffc0bf8c459..cee6d8481a33942d1d41d51a0cb16ba6fb98ac0b 100644 (file)
--- a/lib/pleroma/web/media_proxy/media_proxy.ex
+++ b/lib/pleroma/web/media_proxy/media_proxy.ex
@@ -1,3 +1,7 @@
+# Pleroma: A lightweight social networking server
+# Copyright © 2017-2019 Pleroma Authors <https://pleroma.social/>
+# SPDX-License-Identifier: AGPL-3.0-only
+
 defmodule Pleroma.Web.MediaProxy do
   @base64_opts [padding: false]
 
@@ -5,27 +9,52 @@ defmodule Pleroma.Web.MediaProxy do
 
   def url(""), do: nil
 
-  def url(url = "/" <> _), do: url
+  def url("/" <> _ = url), do: url
 
   def url(url) do
-    config = Application.get_env(:pleroma, :media_proxy, [])
-
-    if !Keyword.get(config, :enabled, false) or String.starts_with?(url, Pleroma.Web.base_url()) do
+    if !enabled?() or local?(url) or whitelisted?(url) do
       url
     else
-      secret = Application.get_env(:pleroma, Pleroma.Web.Endpoint)[:secret_key_base]
-      base64 = Base.url_encode64(url, @base64_opts)
-      sig = :crypto.hmac(:sha, secret, base64)
-      sig64 = sig |> Base.url_encode64(@base64_opts)
-      filename = if path = URI.parse(url).path, do: "/" <> Path.basename(path), else: ""
-
-      Keyword.get(config, :base_url, Pleroma.Web.base_url()) <>
-        "/proxy/#{sig64}/#{base64}#{filename}"
+      encode_url(url)
     end
   end
 
+  defp enabled?, do: Pleroma.Config.get([:media_proxy, :enabled], false)
+
+  defp local?(url), do: String.starts_with?(url, Pleroma.Web.base_url())
+
+  defp whitelisted?(url) do
+    %{host: domain} = URI.parse(url)
+
+    Enum.any?(Pleroma.Config.get([:media_proxy, :whitelist]), fn pattern ->
+      String.equivalent?(domain, pattern)
+    end)
+  end
+
+  def encode_url(url) do
+    secret = Pleroma.Config.get([Pleroma.Web.Endpoint, :secret_key_base])
+
+    # Must preserve `%2F` for compatibility with S3
+    # https://git.pleroma.social/pleroma/pleroma/issues/580
+    replacement = get_replacement(url, ":2F:")
+
+    # The URL is url-decoded and encoded again to ensure it is correctly encoded and not twice.
+    base64 =
+      url
+      |> String.replace("%2F", replacement)
+      |> URI.decode()
+      |> URI.encode()
+      |> String.replace(replacement, "%2F")
+      |> Base.url_encode64(@base64_opts)
+
+    sig = :crypto.hmac(:sha, secret, base64)
+    sig64 = sig |> Base.url_encode64(@base64_opts)
+
+    build_url(sig64, base64, filename(url))
+  end
+
   def decode_url(sig, url) do
-    secret = Application.get_env(:pleroma, Pleroma.Web.Endpoint)[:secret_key_base]
+    secret = Pleroma.Config.get([Pleroma.Web.Endpoint, :secret_key_base])
     sig = Base.url_decode64!(sig, @base64_opts)
     local_sig = :crypto.hmac(:sha, secret, url)
 
@@ -35,4 +64,28 @@ defmodule Pleroma.Web.MediaProxy do
       {:error, :invalid_signature}
     end
   end
+
+  def filename(url_or_path) do
+    if path = URI.parse(url_or_path).path, do: Path.basename(path)
+  end
+
+  def build_url(sig_base64, url_base64, filename \\ nil) do
+    [
+      Pleroma.Config.get([:media_proxy, :base_url], Pleroma.Web.base_url()),
+      "proxy",
+      sig_base64,
+      url_base64,
+      filename
+    ]
+    |> Enum.filter(fn value -> value end)
+    |> Path.join()
+  end
+
+  defp get_replacement(url, replacement) do
+    if String.contains?(url, replacement) do
+      get_replacement(url, replacement <> replacement)
+    else
+      replacement
+    end
+  end
 end