about summary refs log tree commit diff
path: root/lib/sanitize_ext/sanitize_config.rb
blob: 27e1eb92fc43a484da1de9d349537d24e9f74114 (plain) (blame)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
# frozen_string_literal: true

class Sanitize
  module Config
    HTTP_PROTOCOLS = %w(
      http
      https
    ).freeze

    LINK_PROTOCOLS = %w(
      http
      https
      dat
      dweb
      ipfs
      ipns
      ssb
      gemini
      gopher
      xmpp
      magnet
      gemini
    ).freeze

    CLASS_WHITELIST_TRANSFORMER = lambda do |env|
      node = env[:node]
      class_list = node['class']&.split(/[\t\n\f\r ]/)

      return unless class_list

      class_list.keep_if do |e|
        next true if /^(h|p|u|dt|e)-/.match?(e) # microformats classes
        next true if /^(mention|hashtag)$/.match?(e) # semantic classes
        next true if /^(ellipsis|invisible)$/.match?(e) # link formatting classes
      end

      node['class'] = class_list.join(' ')
    end

    IMG_TAG_TRANSFORMER = lambda do |env|
      node = env[:node]

      return unless env[:node_name] == 'img'

      node.name = 'a'

      node['href'] = node['src']
      if node['alt'].present?
        node.content = "[🖼  #{node['alt']}]"
      else
        url = node['href']
        prefix = url.match(/\Ahttps?:\/\/(www\.)?/).to_s
        text   = url[prefix.length, 30]
        text   = text + "…" if url[prefix.length..-1].length > 30
        node.content = "[🖼  #{text}]"
      end
    end

    UNSUPPORTED_HREF_TRANSFORMER = lambda do |env|
      return unless env[:node_name] == 'a'

      current_node = env[:node]

      scheme = begin
        if current_node['href'] =~ Sanitize::REGEX_PROTOCOL
          Regexp.last_match(1).downcase
        else
          :relative
        end
      end

      current_node.replace(current_node.text) unless LINK_PROTOCOLS.include?(scheme)
    end

    MASTODON_STRICT ||= freeze_config(
      elements: %w(p br span a abbr del pre blockquote code b strong u sub sup i em h1 h2 h3 h4 h5 ul ol li details summary),

      attributes: {
        'a'          => %w(href rel class title),
        'span'       => %w(class),
        'abbr'       => %w(title),
        'blockquote' => %w(cite),
        'ol'         => %w(start reversed),
        'li'         => %w(value),
      },

      add_attributes: {
        'a' => {
          'rel' => 'nofollow noopener noreferrer',
          'target' => '_blank',
        },
      },

      protocols: {
        'a'          => { 'href' => LINK_PROTOCOLS },
        'blockquote' => { 'cite' => LINK_PROTOCOLS },
      },

      transformers: [
        CLASS_WHITELIST_TRANSFORMER,
        IMG_TAG_TRANSFORMER,
        UNSUPPORTED_HREF_TRANSFORMER,
      ]
    )

    MASTODON_OEMBED ||= freeze_config merge(
      RELAXED,
      elements: RELAXED[:elements] + %w(audio embed iframe source video),

      attributes: merge(
        RELAXED[:attributes],
        'audio'  => %w(controls),
        'embed'  => %w(height src type width),
        'iframe' => %w(allowfullscreen frameborder height scrolling src width),
        'source' => %w(src type),
        'video'  => %w(controls height loop width),
        'div'    => [:data]
      ),

      protocols: merge(
        RELAXED[:protocols],
        'embed'  => { 'src' => HTTP_PROTOCOLS },
        'iframe' => { 'src' => HTTP_PROTOCOLS },
        'source' => { 'src' => HTTP_PROTOCOLS }
      )
    )

    LINK_REL_TRANSFORMER = lambda do |env|
      return unless env[:node_name] == 'a' && env[:node]['href']

      node = env[:node]

      rel = (node['rel'] || '').split(' ') & ['tag']
      rel += ['nofollow', 'noopener', 'noreferrer'] unless TagManager.instance.local_url?(node['href'])

      if rel.empty?
        node.remove_attribute('rel')
      else
        node['rel'] = rel.join(' ')
      end
    end

    LINK_TARGET_TRANSFORMER = lambda do |env|
      return unless env[:node_name] == 'a' && env[:node]['href']

      node = env[:node]
      if node['target'] != '_blank' && TagManager.instance.local_url?(node['href'])
        node.remove_attribute('target')
      else
        node['target'] = '_blank'
      end
    end

    MASTODON_OUTGOING ||= freeze_config MASTODON_STRICT.merge(
      attributes: merge(
        MASTODON_STRICT[:attributes],
        'a' => %w(href rel class title target)
      ),

      add_attributes: {},

      transformers: [
        CLASS_WHITELIST_TRANSFORMER,
        IMG_TAG_TRANSFORMER,
        UNSUPPORTED_HREF_TRANSFORMER,
        LINK_REL_TRANSFORMER,
        LINK_TARGET_TRANSFORMER,
      ]
    )
  end
end