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diff --git a/lib/fast_sanitize/sanitizer/meta.ex b/lib/fast_sanitize/sanitizer/meta.ex
index b41555e..65cecf6 100644
--- a/lib/fast_sanitize/sanitizer/meta.ex
+++ b/lib/fast_sanitize/sanitizer/meta.ex
@@ -1,187 +1,188 @@
# Based on HtmlSanitizeEx.Scrubber.Meta
# Copyright (c) 2015-2019 René Föhring (@rrrene)
defmodule FastSanitize.Sanitizer.Meta do
@moduledoc """
This module contains some meta-programming magic to define your own rules
for scrubbers.
The StripTags scrubber is a good starting point:
defmodule FastSanitize.Sanitizer.StripTags do
require FastSanitize.Sanitizer.Meta
alias FastSanitize.Sanitizer.Meta
Meta.strip_comments
Meta.strip_everything_not_covered
end
You can use the `allow_tag_with_uri_attributes/3` and
`allow_tag_with_these_attributes/2` macros to define what is allowed:
defmodule FastSanitize.Sanitizer.StripTags do
require FastSanitize.Sanitizer.Meta
alias FastSanitize.Sanitizer.Meta
Meta.strip_comments
Meta.allow_tag_with_uri_attributes "img", ["src"], ["http", "https"]
Meta.allow_tag_with_these_attributes "img", ["width", "height"]
Meta.strip_everything_not_covered
end
You can stack these if convenient:
Meta.allow_tag_with_uri_attributes "img", ["src"], ["http", "https"]
Meta.allow_tag_with_these_attributes "img", ["width", "height"]
Meta.allow_tag_with_these_attributes "img", ["title", "alt"]
"""
@doc """
Allow these tags and use the regular `scrub_attribute/2` function to scrub
the attributes.
"""
defmacro allow_tags_and_scrub_their_attributes(list) do
Enum.map(list, fn tag_name ->
allow_this_tag_and_scrub_its_attributes(tag_name)
end)
end
@doc """
Allow the given +list+ of attributes for the specified +tag+.
Meta.allow_tag_with_these_attributes "a", ["name", "title"]
Meta.allow_tag_with_these_attributes "img", ["title", "alt"]
"""
defmacro allow_tag_with_these_attributes(tag_name, list \\ []) do
list
|> Enum.map(fn attr_name ->
allow_this_tag_with_this_attribute(tag_name, attr_name)
end)
|> Enum.concat([allow_this_tag_and_scrub_its_attributes(tag_name)])
end
@doc """
Allow the given list of +values+ for the given +attribute+ on the
specified +tag+.
Meta.allow_tag_with_this_attribute_values "a", "target", ["_blank"]
"""
defmacro allow_tag_with_this_attribute_values(tag_name, attribute, values) do
quote do
def scrub_attribute(unquote(tag_name), {unquote(attribute), value})
when value in unquote(values) do
{unquote(attribute), value}
end
end
end
@doc """
Allow the given +list+ of attributes to contain URI information for the
specified +tag+.
# Only allow SSL-enabled and mailto links
Meta.allow_tag_with_uri_attributes "a", ["href"], ["https", "mailto"]
# Only allow none-SSL images
Meta.allow_tag_with_uri_attributes "img", ["src"], ["http"]
"""
defmacro allow_tag_with_uri_attributes(tag, list, valid_schemes) do
list
|> Enum.map(fn name ->
allow_tag_with_uri_attribute(tag, name, valid_schemes)
end)
end
@doc """
"""
defmacro allow_tags_with_style_attributes(list) do
list
|> Enum.map(fn tag_name -> allow_this_tag_with_style_attribute(tag_name) end)
end
@doc """
Strips all comments.
"""
defmacro strip_comments do
quote do
def scrub({:comment, _, _}), do: nil
end
end
@doc """
Ensures any tags/attributes not explicitly whitelisted until this
statement are stripped.
"""
defmacro strip_everything_not_covered do
quote do
# If we haven't covered the attribute until here, we just scrap it.
def scrub_attribute(_tag, _attribute), do: nil
# If we haven't covered the attribute until here, we just scrap it.
def scrub({_tag, _attributes, children}), do: children
# Text is left alone
def scrub("" <> text), do: text
end
end
@doc """
Ensures any tags/attributes that are explicitly disallowed have
their children dropped.
"""
defmacro strip_children_of(tag_name) do
quote do
def scrub({unquote(tag_name), _attributes, _children}), do: nil
end
end
defp allow_this_tag_and_scrub_its_attributes(tag_name) do
quote do
def scrub({unquote(tag_name), attributes, children}) do
{unquote(tag_name), scrub_attributes(unquote(tag_name), attributes), children}
end
defp scrub_attributes(unquote(tag_name), attributes) do
- Enum.map(attributes, fn attr ->
+ attributes
+ |> Enum.map(fn attr ->
scrub_attribute(unquote(tag_name), attr)
end)
|> Enum.reject(&is_nil(&1))
end
end
end
defp allow_this_tag_with_this_attribute(tag_name, attr_name) do
quote do
def scrub_attribute(unquote(tag_name), {unquote(attr_name), value}) do
{unquote(attr_name), value}
end
end
end
defp allow_this_tag_with_style_attribute(tag_name) do
quote do
def scrub_attribute(unquote(tag_name), {"style", value}) do
{"style", scrub_css(value)}
end
end
end
defp allow_tag_with_uri_attribute(tag_name, attr_name, valid_schemes) do
quote do
def scrub_attribute(unquote(tag_name), {unquote(attr_name), "&" <> value}) do
nil
end
def scrub_attribute(unquote(tag_name), {unquote(attr_name), uri} = attr) do
uri = URI.parse(uri)
if uri.scheme == nil or uri.scheme in unquote(valid_schemes), do: attr
end
end
end
end

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