315 lines
8.3 KiB
Elixir
315 lines
8.3 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.HTML do
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defp get_scrubbers(scrubber) when is_atom(scrubber), do: [scrubber]
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defp get_scrubbers(scrubbers) when is_list(scrubbers), do: scrubbers
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defp get_scrubbers(_), do: [Pleroma.HTML.Scrubber.Default]
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def get_scrubbers do
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Pleroma.Config.get([:markup, :scrub_policy])
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|> get_scrubbers
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end
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def filter_tags(html, nil) do
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filter_tags(html, get_scrubbers())
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end
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def filter_tags(html, scrubbers) when is_list(scrubbers) do
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Enum.reduce(scrubbers, html, fn scrubber, html ->
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filter_tags(html, scrubber)
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end)
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end
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def filter_tags(html, scrubber) do
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{:ok, content} = FastSanitize.Sanitizer.scrub(html, scrubber)
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content
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end
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def filter_tags(html), do: filter_tags(html, nil)
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def strip_tags(html), do: filter_tags(html, FastSanitize.Sanitizer.StripTags)
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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 = Pleroma.Object.normalize(activity)
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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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def ensure_scrubbed_html(
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content,
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scrubbers,
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fake,
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callback
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) do
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content =
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content
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|> filter_tags(scrubbers)
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|> callback.()
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if fake do
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{:ignore, content}
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else
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{:commit, content}
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end
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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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def extract_first_external_url(_, nil), do: {:error, "No content"}
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def extract_first_external_url(object, content) do
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key = "URL|#{object.id}"
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Cachex.fetch!(:scrubber_cache, key, fn _key ->
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result =
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content
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|> Floki.filter_out("a.mention,a.hashtag,a[rel~=\"tag\"]")
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|> Floki.attribute("a", "href")
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|> Enum.at(0)
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{:commit, {:ok, result}}
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end)
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end
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end
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defmodule Pleroma.HTML.Scrubber.TwitterText do
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@moduledoc """
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An HTML scrubbing policy which limits to twitter-style text. Only
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paragraphs, breaks and links are allowed through the filter.
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"""
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@valid_schemes Pleroma.Config.get([:uri_schemes, :valid_schemes], [])
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require FastSanitize.Sanitizer.Meta
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alias FastSanitize.Sanitizer.Meta
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Meta.strip_comments()
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# links
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Meta.allow_tag_with_uri_attributes(:a, ["href", "data-user", "data-tag"], @valid_schemes)
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Meta.allow_tag_with_this_attribute_values(:a, "class", [
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"hashtag",
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"u-url",
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"mention",
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"u-url mention",
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"mention u-url"
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])
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Meta.allow_tag_with_this_attribute_values(:a, "rel", [
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"tag",
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"nofollow",
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"noopener",
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"noreferrer"
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])
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Meta.allow_tag_with_these_attributes(:a, ["name", "title"])
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# paragraphs and linebreaks
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Meta.allow_tag_with_these_attributes(:br, [])
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Meta.allow_tag_with_these_attributes(:p, [])
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# microformats
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Meta.allow_tag_with_this_attribute_values(:span, "class", ["h-card"])
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Meta.allow_tag_with_these_attributes(:span, [])
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# allow inline images for custom emoji
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if Pleroma.Config.get([:markup, :allow_inline_images]) do
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# restrict img tags to http/https only, because of MediaProxy.
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Meta.allow_tag_with_uri_attributes(:img, ["src"], ["http", "https"])
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Meta.allow_tag_with_these_attributes(:img, [
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"width",
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"height",
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"class",
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"title",
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"alt"
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])
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end
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Meta.strip_everything_not_covered()
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end
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defmodule Pleroma.HTML.Scrubber.Default do
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@doc "The default HTML scrubbing policy: no "
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require FastSanitize.Sanitizer.Meta
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alias FastSanitize.Sanitizer.Meta
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# credo:disable-for-previous-line
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# No idea how to fix this one…
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@valid_schemes Pleroma.Config.get([:uri_schemes, :valid_schemes], [])
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Meta.strip_comments()
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Meta.allow_tag_with_uri_attributes(:a, ["href", "data-user", "data-tag"], @valid_schemes)
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Meta.allow_tag_with_this_attribute_values(:a, "class", [
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"hashtag",
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"u-url",
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"mention",
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"u-url mention",
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"mention u-url"
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])
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Meta.allow_tag_with_this_attribute_values(:a, "rel", [
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"tag",
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"nofollow",
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"noopener",
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"noreferrer",
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"ugc"
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])
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Meta.allow_tag_with_these_attributes(:a, ["name", "title"])
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Meta.allow_tag_with_these_attributes(:abbr, ["title"])
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Meta.allow_tag_with_these_attributes(:b, [])
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Meta.allow_tag_with_these_attributes(:blockquote, [])
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Meta.allow_tag_with_these_attributes(:br, [])
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Meta.allow_tag_with_these_attributes(:code, [])
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Meta.allow_tag_with_these_attributes(:del, [])
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Meta.allow_tag_with_these_attributes(:em, [])
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Meta.allow_tag_with_these_attributes(:i, [])
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Meta.allow_tag_with_these_attributes(:li, [])
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Meta.allow_tag_with_these_attributes(:ol, [])
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Meta.allow_tag_with_these_attributes(:p, [])
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Meta.allow_tag_with_these_attributes(:pre, [])
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Meta.allow_tag_with_these_attributes(:strong, [])
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Meta.allow_tag_with_these_attributes(:sub, [])
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Meta.allow_tag_with_these_attributes(:sup, [])
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Meta.allow_tag_with_these_attributes(:u, [])
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Meta.allow_tag_with_these_attributes(:ul, [])
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Meta.allow_tag_with_this_attribute_values(:span, "class", ["h-card"])
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Meta.allow_tag_with_these_attributes(:span, [])
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@allow_inline_images Pleroma.Config.get([:markup, :allow_inline_images])
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if @allow_inline_images do
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# restrict img tags to http/https only, because of MediaProxy.
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Meta.allow_tag_with_uri_attributes(:img, ["src"], ["http", "https"])
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Meta.allow_tag_with_these_attributes(:img, [
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"width",
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"height",
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"class",
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"title",
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"alt"
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])
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end
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if Pleroma.Config.get([:markup, :allow_tables]) do
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Meta.allow_tag_with_these_attributes(:table, [])
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Meta.allow_tag_with_these_attributes(:tbody, [])
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Meta.allow_tag_with_these_attributes(:td, [])
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Meta.allow_tag_with_these_attributes(:th, [])
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Meta.allow_tag_with_these_attributes(:thead, [])
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Meta.allow_tag_with_these_attributes(:tr, [])
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end
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if Pleroma.Config.get([:markup, :allow_headings]) do
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Meta.allow_tag_with_these_attributes(:h1, [])
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Meta.allow_tag_with_these_attributes(:h2, [])
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Meta.allow_tag_with_these_attributes(:h3, [])
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Meta.allow_tag_with_these_attributes(:h4, [])
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Meta.allow_tag_with_these_attributes(:h5, [])
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end
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if Pleroma.Config.get([:markup, :allow_fonts]) do
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Meta.allow_tag_with_these_attributes(:font, ["face"])
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end
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Meta.strip_everything_not_covered()
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end
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defmodule Pleroma.HTML.Transform.MediaProxy do
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@moduledoc "Transforms inline image URIs to use MediaProxy."
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alias Pleroma.Web.MediaProxy
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def before_scrub(html), do: html
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def scrub_attribute(:img, {"src", "http" <> target}) do
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media_url =
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("http" <> target)
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|> MediaProxy.url()
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{"src", media_url}
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end
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def scrub_attribute(_tag, attribute), do: attribute
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def scrub({:img, attributes, children}) do
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attributes =
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attributes
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|> Enum.map(fn attr -> scrub_attribute(:img, attr) end)
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|> Enum.reject(&is_nil(&1))
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{:img, attributes, children}
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end
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def scrub({:comment, _text, _children}), do: ""
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def scrub({tag, attributes, children}), do: {tag, attributes, children}
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def scrub({_tag, children}), do: children
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def scrub(text), do: text
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end
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defmodule Pleroma.HTML.Scrubber.LinksOnly do
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@moduledoc """
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An HTML scrubbing policy which limits to links only.
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"""
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@valid_schemes Pleroma.Config.get([:uri_schemes, :valid_schemes], [])
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require FastSanitize.Sanitizer.Meta
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alias FastSanitize.Sanitizer.Meta
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Meta.strip_comments()
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# links
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Meta.allow_tag_with_uri_attributes(:a, ["href"], @valid_schemes)
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Meta.allow_tag_with_this_attribute_values(:a, "rel", [
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"tag",
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"nofollow",
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"noopener",
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"noreferrer",
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"me",
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"ugc"
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])
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Meta.allow_tag_with_these_attributes(:a, ["name", "title"])
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Meta.strip_everything_not_covered()
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end
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