Class: RuboCop::Cop::Gusto::RegexpBypass

Inherits:
Base
  • Object
show all
Extended by:
AutoCorrector
Defined in:
lib/rubocop/cop/gusto/regexp_bypass.rb

Overview

Ensures that regular expressions use ‘A` and `z` anchors instead of `^` and `$` when matching the start or end of a string. This is critical for security validations as `^` and `$` will match the start/end of any line in a string, not just the start/end of the entire string.

Examples:

# bad - validating only a single line of input which could be split across multiple lines
/^foo/
/foo$/
/^foo$/

# good
/\Afoo/
/foo\z/
/\Afoo\z/

# good - multiline mode is allowed
/^foo/m
/foo$/m

# okay - anchors in the middle of the pattern are not flagged
/foo^bar/
/foo$bar/

See Also:

Constant Summary collapse

MSG = 
'Regular expressions matching a single line should use \A instead of ^ and \z instead of $'
PROHIBITED_ANCHOR = 
"^"
PROHIBITED_END_ANCHOR = 
"$"

Instance Method Summary collapse

Instance Method Details

#on_regexp(node) ⇒ Object 



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# File 'lib/rubocop/cop/gusto/regexp_bypass.rb', line 45

def on_regexp(node)
  return if node.children.find(&:regopt_type?)&.source&.include?("m")

  first_child = node.children.first
  return unless first_child && !first_child.regopt_type?

  captureless_source = first_child.source.delete("()") # Remove parentheses to check actual content
  return unless captureless_source.start_with?(PROHIBITED_ANCHOR) || captureless_source.end_with?(PROHIBITED_END_ANCHOR)

  add_offense(first_child) do |corrector|
    source_buffer = first_child.source_range.source_buffer
    actual_source = first_child.source

    if captureless_source.start_with?(PROHIBITED_ANCHOR)
      # Find the position of ^ within the source, accounting for parentheses
      caret_pos = actual_source.index(PROHIBITED_ANCHOR)
      start_pos = first_child.source_range.begin_pos + caret_pos
      corrector.replace(
        Parser::Source::Range.new(
          source_buffer,
          start_pos,
          start_pos + 1
        ),
        '\A'
      )
    end

    if captureless_source.end_with?(PROHIBITED_END_ANCHOR)
      # Find the position of $ within the source, accounting for parentheses
      dollar_pos = actual_source.rindex(PROHIBITED_END_ANCHOR)
      end_pos = first_child.source_range.begin_pos + dollar_pos + 1
      corrector.replace(
        Parser::Source::Range.new(
          source_buffer,
          end_pos - 1,
          end_pos
        ),
        '\z'
      )
    end
  end
end