spec/lib/banzai/filter/syntax_highlight_filter_spec.rb


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
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199

# frozen_string_literal: true

require 'spec_helper'

RSpec.describe Banzai::Filter::SyntaxHighlightFilter do
  include FilterSpecHelper

  shared_examples "XSS prevention" do |lang|
    it "escapes HTML tags" do
      # This is how a script tag inside a code block is presented to this filter
      # after Markdown rendering.
      result = filter(%{<pre lang="#{lang}"><code>&lt;script&gt;alert(1)&lt;/script&gt;</code></pre>})

      # `(1)` symbols are wrapped by lexer tags.
      expect(result.to_html).not_to match(%r{<script>alert.*</script>})

      # `<>` stands for lexer tags like <span ...>, not &lt;s above.
      expect(result.to_html).to match(%r{alert(<.*>)?\((<.*>)?1(<.*>)?\)})
    end
  end

  context "when no language is specified" do
    it "highlights as plaintext" do
      result = filter('<pre><code>def fun end</code></pre>')

      expect(result.to_html.delete("\n")).to eq('<div class="gl-relative markdown-code-block js-markdown-code"><pre lang="plaintext" class="code highlight js-syntax-highlight language-plaintext" data-canonical-lang="" v-pre="true"><code><span id="LC1" class="line" lang="plaintext">def fun end</span></code></pre><copy-code></copy-code></div>')
    end

    include_examples "XSS prevention", ""
  end

  context "when contains mermaid diagrams" do
    it "ignores mermaid blocks" do
      result = filter('<pre data-mermaid-style="display" lang="mermaid"><code class="js-render-mermaid">mermaid code</code></pre>')

      expect(result.to_html.delete("\n")).to eq('<div class="gl-relative markdown-code-block js-markdown-code"><pre data-mermaid-style="display" lang="mermaid" class="code highlight js-syntax-highlight language-mermaid" v-pre="true"><code class="js-render-mermaid"><span id="LC1" class="line" lang="mermaid">mermaid code</span></code></pre><copy-code></copy-code></div>')
    end
  end

  context "when <pre> contains multiple <code> tags" do
    it "ignores the block" do
      result = filter('<pre><code>one</code> and <code>two</code></pre>')

      expect(result.to_html).to eq('<pre><code>one</code> and <code>two</code></pre>')
    end
  end

  # This can happen with the following markdown
  #
  # <div>
  # <pre><code>
  # something
  #
  #     else
  # </code></pre>
  # </div>
  #
  # The blank line causes markdown to process `    else` as a code block.
  # Which could lead to an orphaned node being replaced and failing
  context "when <pre><code> is a child of <pre><code> which is a child of a div " do
    it "captures all text and doesn't fail trying to replace a node with no parent" do
      text = "<div>\n<pre><code>\nsomething\n<pre><code>else\n</code></pre></code></pre>\n</div>"
      result = filter(text)

      expect(result.to_html.delete("\n")).to eq('<div><div class="gl-relative markdown-code-block js-markdown-code"><pre lang="plaintext" class="code highlight js-syntax-highlight language-plaintext" data-canonical-lang="" v-pre="true"><code><span id="LC1" class="line" lang="plaintext"></span><span id="LC2" class="line" lang="plaintext">something</span><span id="LC3" class="line" lang="plaintext">else</span></code></pre><copy-code></copy-code></div></div>')
    end
  end

  context "when a valid language is specified" do
    it "highlights as that language" do
      result = filter('<pre lang="ruby"><code>def fun end</code></pre>')

      expect(result.to_html.delete("\n")).to eq('<div class="gl-relative markdown-code-block js-markdown-code"><pre lang="ruby" class="code highlight js-syntax-highlight language-ruby" v-pre="true"><code><span id="LC1" class="line" lang="ruby"><span class="k">def</span> <span class="nf">fun</span> <span class="k">end</span></span></code></pre><copy-code></copy-code></div>')
    end

    include_examples "XSS prevention", "ruby"
  end

  context "when an invalid language is specified" do
    it "highlights as plaintext" do
      result = filter('<pre lang="gnuplot"><code>This is a test</code></pre>')

      expect(result.to_html.delete("\n")).to eq('<div class="gl-relative markdown-code-block js-markdown-code"><pre lang="plaintext" class="code highlight js-syntax-highlight language-plaintext" data-canonical-lang="gnuplot" v-pre="true"><code><span id="LC1" class="line" lang="plaintext">This is a test</span></code></pre><copy-code></copy-code></div>')
    end

    include_examples "XSS prevention", "gnuplot"
  end

  context "languages that should be passed through" do
    let(:delimiter) { described_class::LANG_PARAMS_DELIMITER }
    let(:data_attr) { described_class::LANG_PARAMS_ATTR }

    %w(math mermaid plantuml suggestion).each do |lang|
      context "when #{lang} is specified" do
        it "highlights as plaintext but with the correct language attribute and class" do
          result = filter(%{<pre lang="#{lang}"><code>This is a test</code></pre>})

          expect(result.to_html.delete("\n")).to eq(%{<div class="gl-relative markdown-code-block js-markdown-code"><pre lang="#{lang}" class="code highlight js-syntax-highlight language-#{lang}" v-pre="true"><code><span id="LC1" class="line" lang="#{lang}">This is a test</span></code></pre><copy-code></copy-code></div>})
        end

        include_examples "XSS prevention", lang
      end

      context "when #{lang} has extra params" do
        let(:lang_params) { 'foo-bar-kux' }
        let(:xss_lang) { "#{lang} data-meta=\"foo-bar-kux\"&lt;script&gt;alert(1)&lt;/script&gt;" }

        it "includes data-lang-params tag with extra information" do
          result = filter(%{<pre lang="#{lang}" data-meta="#{lang_params}"><code>This is a test</code></pre>})

          expect(result.to_html.delete("\n")).to eq(%{<div class="gl-relative markdown-code-block js-markdown-code"><pre lang="#{lang}" class="code highlight js-syntax-highlight language-#{lang}" #{data_attr}="#{lang_params}" v-pre="true"><code><span id="LC1" class="line" lang="#{lang}">This is a test</span></code></pre><copy-code></copy-code></div>})
        end

        include_examples "XSS prevention", lang

        include_examples "XSS prevention",
                         "#{lang} data-meta=\"foo-bar-kux\"&lt;script&gt;alert(1)&lt;/script&gt;"

        include_examples "XSS prevention",
          "#{lang} data-meta=\"foo-bar-kux\"<script>alert(1)</script>"
      end
    end

    context 'when multiple param delimiters are used' do
      let(:lang) { 'suggestion' }
      let(:lang_params) { '-1+10' }

      let(:expected_result) do
        %{<div class="gl-relative markdown-code-block js-markdown-code"><pre lang="#{lang}" class="code highlight js-syntax-highlight language-#{lang}" #{data_attr}="#{lang_params} more-things" v-pre="true"><code><span id="LC1" class="line" lang="#{lang}">This is a test</span></code></pre><copy-code></copy-code></div>}
      end

      context 'when delimiter is space' do
        it 'delimits on the first appearance' do
          result = filter(%{<pre lang="#{lang}" data-meta="#{lang_params} more-things"><code>This is a test</code></pre>})

          expect(result.to_html.delete("\n")).to eq(expected_result)
        end
      end

      context 'when delimiter is colon' do
        it 'delimits on the first appearance' do
          result = filter(%{<pre lang="#{lang}#{delimiter}#{lang_params} more-things"><code>This is a test</code></pre>})

          expect(result.to_html.delete("\n")).to eq(expected_result)
        end
      end
    end
  end

  context "when sourcepos metadata is available" do
    it "includes it in the highlighted code block" do
      result = filter('<pre data-sourcepos="1:1-3:3"><code lang="plaintext">This is a test</code></pre>')

      expect(result.to_html.delete("\n")).to eq('<div class="gl-relative markdown-code-block js-markdown-code"><pre data-sourcepos="1:1-3:3" lang="plaintext" class="code highlight js-syntax-highlight language-plaintext" data-canonical-lang="" v-pre="true"><code lang="plaintext"><span id="LC1" class="line" lang="plaintext">This is a test</span></code></pre><copy-code></copy-code></div>')
    end

    it "escape sourcepos metadata to prevent XSS" do
      result = filter('<pre data-sourcepos="&#34;%22 href=&#34;x&#34;></pre><base href=http://unsafe-website.com/><pre x=&#34;"><code></code></pre>')

      expect(result.to_html.delete("\n")).to eq('<div class="gl-relative markdown-code-block js-markdown-code"><pre data-sourcepos=\'"%22 href="x"&gt;&lt;/pre&gt;&lt;base href=http://unsafe-website.com/&gt;&lt;pre x="\' lang="plaintext" class="code highlight js-syntax-highlight language-plaintext" data-canonical-lang="" v-pre="true"><code></code></pre><copy-code></copy-code></div>')
    end
  end

  context "when Rouge lexing fails" do
    before do
      allow_next_instance_of(Rouge::Lexers::Ruby) do |instance|
        allow(instance).to receive(:stream_tokens).and_raise(StandardError)
      end
    end

    it "highlights as plaintext" do
      result = filter('<pre lang="ruby"><code>This is a test</code></pre>')

      expect(result.to_html.delete("\n")).to eq('<div class="gl-relative markdown-code-block js-markdown-code"><pre lang="" class="code highlight js-syntax-highlight" data-canonical-lang="ruby" v-pre="true"><code><span id="LC1" class="line" lang="">This is a test</span></code></pre><copy-code></copy-code></div>')
    end

    include_examples "XSS prevention", "ruby"
  end

  context "when Rouge lexing fails after a retry" do
    before do
      allow_next_instance_of(Rouge::Lexers::PlainText) do |instance|
        allow(instance).to receive(:stream_tokens).and_raise(StandardError)
      end
    end

    it "does not add highlighting classes" do
      result = filter('<pre><code>This is a test</code></pre>')

      expect(result.to_html).to eq('<pre><code>This is a test</code></pre>')
    end

    include_examples "XSS prevention", "ruby"
  end

  it_behaves_like "filter timeout" do
    let(:text) { '<pre lang="ruby"><code>def fun end</code></pre>' }
  end
end