From 3a4773c3c2bd0bbef244eb519b07208da9108e49 Mon Sep 17 00:00:00 2001
From: dcc <dcc@logografos.com>
Date: Sat, 2 Sep 2023 00:52:52 -0700
Subject: First

---
 lib/pleroma/web/rich_media/helpers.ex | 130 ++++++++++++++++++++++++++++++++++
 1 file changed, 130 insertions(+)
 create mode 100644 lib/pleroma/web/rich_media/helpers.ex

(limited to 'lib/pleroma/web/rich_media/helpers.ex')

diff --git a/lib/pleroma/web/rich_media/helpers.ex b/lib/pleroma/web/rich_media/helpers.ex
new file mode 100644
index 0000000..0488df3
--- /dev/null
+++ b/lib/pleroma/web/rich_media/helpers.ex
@@ -0,0 +1,130 @@
+# Pleroma: A lightweight social networking server
+# Copyright © 2017-2022 Pleroma Authors <https://pleroma.social/>
+# SPDX-License-Identifier: AGPL-3.0-only
+
+defmodule Pleroma.Web.RichMedia.Helpers do
+  alias Pleroma.Activity
+  alias Pleroma.Config
+  alias Pleroma.HTML
+  alias Pleroma.Object
+  alias Pleroma.Web.RichMedia.Parser
+
+  @options [
+    pool: :media,
+    max_body: 2_000_000,
+    recv_timeout: 2_000
+  ]
+
+  @spec validate_page_url(URI.t() | binary()) :: :ok | :error
+  defp validate_page_url(page_url) when is_binary(page_url) do
+    validate_tld = Config.get([Pleroma.Formatter, :validate_tld])
+
+    page_url
+    |> Linkify.Parser.url?(validate_tld: validate_tld)
+    |> parse_uri(page_url)
+  end
+
+  defp validate_page_url(%URI{host: host, scheme: "https", authority: authority})
+       when is_binary(authority) do
+    cond do
+      host in Config.get([:rich_media, :ignore_hosts], []) ->
+        :error
+
+      get_tld(host) in Config.get([:rich_media, :ignore_tld], []) ->
+        :error
+
+      true ->
+        :ok
+    end
+  end
+
+  defp validate_page_url(_), do: :error
+
+  defp parse_uri(true, url) do
+    url
+    |> URI.parse()
+    |> validate_page_url
+  end
+
+  defp parse_uri(_, _), do: :error
+
+  defp get_tld(host) do
+    host
+    |> String.split(".")
+    |> Enum.reverse()
+    |> hd
+  end
+
+  def fetch_data_for_object(object) do
+    with true <- Config.get([:rich_media, :enabled]),
+         {:ok, page_url} <-
+           HTML.extract_first_external_url_from_object(object),
+         :ok <- validate_page_url(page_url),
+         {:ok, rich_media} <- Parser.parse(page_url) do
+      %{page_url: page_url, rich_media: rich_media}
+    else
+      _ -> %{}
+    end
+  end
+
+  def fetch_data_for_activity(%Activity{data: %{"type" => "Create"}} = activity) do
+    with true <- Config.get([:rich_media, :enabled]),
+         %Object{} = object <- Object.normalize(activity, fetch: false) do
+      fetch_data_for_object(object)
+    else
+      _ -> %{}
+    end
+  end
+
+  def fetch_data_for_activity(_), do: %{}
+
+  def rich_media_get(url) do
+    headers = [{"user-agent", Pleroma.Application.user_agent() <> "; Bot"}]
+
+    head_check =
+      case Pleroma.HTTP.head(url, headers, @options) do
+        # If the HEAD request didn't reach the server for whatever reason,
+        # we assume the GET that comes right after won't either
+        {:error, _} = e ->
+          e
+
+        {:ok, %Tesla.Env{status: 200, headers: headers}} ->
+          with :ok <- check_content_type(headers),
+               :ok <- check_content_length(headers),
+               do: :ok
+
+        _ ->
+          :ok
+      end
+
+    with :ok <- head_check, do: Pleroma.HTTP.get(url, headers, @options)
+  end
+
+  defp check_content_type(headers) do
+    case List.keyfind(headers, "content-type", 0) do
+      {_, content_type} ->
+        case Plug.Conn.Utils.media_type(content_type) do
+          {:ok, "text", "html", _} -> :ok
+          _ -> {:error, {:content_type, content_type}}
+        end
+
+      _ ->
+        :ok
+    end
+  end
+
+  @max_body @options[:max_body]
+  defp check_content_length(headers) do
+    case List.keyfind(headers, "content-length", 0) do
+      {_, maybe_content_length} ->
+        case Integer.parse(maybe_content_length) do
+          {content_length, ""} when content_length <= @max_body -> :ok
+          {_, ""} -> {:error, :body_too_large}
+          _ -> :ok
+        end
+
+      _ ->
+        :ok
+    end
+  end
+end
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