Class: Benedictus::SafetyGuard

Inherits:
Object
  • Object
show all
Defined in:
lib/benedictus/safety_guard.rb

Constant Summary collapse

DATA_MODIFYING_CTE = 
/\b(insert|update|delete|merge|truncate)\b/i

Class Method Summary collapse

Class Method Details

.active_record_class?(klass) ⇒ Boolean

Returns:

  • (Boolean) 


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# File 'lib/benedictus/safety_guard.rb', line 34

def self.active_record_class?(klass)
  return false unless defined?(ActiveRecord::Base)
  return false unless klass.is_a?(Class)

  klass <= ActiveRecord::Base
rescue TypeError, ArgumentError
  false
end

.assert_select!(sql) ⇒ Object

Raises:



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# File 'lib/benedictus/safety_guard.rb', line 7

def self.assert_select!(sql)
  normalized = normalize(sql)

  reject_multi_statement!(normalized)

  keyword = first_keyword(normalized)

  return if keyword.casecmp("SELECT").zero?
  return if keyword.casecmp("WITH").zero? && contains_no_data_modifying_cte?(normalized)

  raise Benedictus::UnsafeQueryError,
        "--analyze can only be used with SELECT queries (got: #{keyword.empty? ? "?" : keyword}...)"
end

.contains_no_data_modifying_cte?(normalized) ⇒ Boolean

Returns:

  • (Boolean) 


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# File 'lib/benedictus/safety_guard.rb', line 92

def self.contains_no_data_modifying_cte?(normalized)
  !DATA_MODIFYING_CTE.match?(normalized)
end

.first_keyword(normalized) ⇒ Object 



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# File 'lib/benedictus/safety_guard.rb', line 78

def self.first_keyword(normalized)
  normalized.lstrip[/\A[A-Za-z_]+/].to_s
end

.match_dollar_tag(sql, i) ⇒ Object 



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# File 'lib/benedictus/safety_guard.rb', line 113

def self.match_dollar_tag(sql, i)
  m = sql[i..].match(/\A\$([A-Za-z_]\w*)?\$/)
  m && m[0]
end

.normalize(sql) ⇒ Object

Replaces SQL string literals (single-quoted, dollar-quoted) and comments (line ‘–`, nested block `/* */`) with single spaces, preserving token boundaries. The result has identical keyword structure to the original but cannot bypass keyword scans by hiding payloads in comments or string literals.



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# File 'lib/benedictus/safety_guard.rb', line 48

def self.normalize(sql)
  result = String.new
  i = 0
  n = sql.length

  while i < n
    c = sql[i]
    nxt = sql[i + 1]

    if c == "'"
      i = skip_single_quoted(sql, i)
      result << " "
    elsif c == "$" && (tag = match_dollar_tag(sql, i))
      i = skip_dollar_quoted(sql, i, tag)
      result << " "
    elsif c == "-" && nxt == "-"
      i = sql.index("\n", i + 2) || n
      result << " "
    elsif c == "/" && nxt == "*"
      i = skip_nested_block_comment(sql, i)
      result << " "
    else
      result << c
      i += 1
    end
  end

  result
end

.reject_multi_statement!(normalized) ⇒ Object

Raises:



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# File 'lib/benedictus/safety_guard.rb', line 82

def self.reject_multi_statement!(normalized)
  trimmed = normalized.rstrip
  trimmed = trimmed.chomp(";").rstrip if trimmed.end_with?(";")

  return unless trimmed.include?(";")

  raise Benedictus::UnsafeQueryError,
        "--analyze refuses multi-statement SQL (found ';' between statements)"
end

.skip_dollar_quoted(sql, start, tag) ⇒ Object 



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# File 'lib/benedictus/safety_guard.rb', line 118

def self.skip_dollar_quoted(sql, start, tag)
  i = start + tag.length
  end_idx = sql.index(tag, i)
  end_idx ? end_idx + tag.length : sql.length
end

.skip_nested_block_comment(sql, start) ⇒ Object 



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# File 'lib/benedictus/safety_guard.rb', line 124

def self.skip_nested_block_comment(sql, start)
  i = start + 2
  depth = 1
  n = sql.length

  while i < n && depth.positive?
    if sql[i] == "/" && sql[i + 1] == "*"
      depth += 1
      i += 2
    elsif sql[i] == "*" && sql[i + 1] == "/"
      depth -= 1
      i += 2
    else
      i += 1
    end
  end

  i
end

.skip_single_quoted(sql, start) ⇒ Object 



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# File 'lib/benedictus/safety_guard.rb', line 96

def self.skip_single_quoted(sql, start)
  i = start + 1
  n = sql.length

  while i < n
    if sql[i] == "'" && sql[i + 1] == "'"
      i += 2
    elsif sql[i] == "'"
      return i + 1
    else
      i += 1
    end
  end

  n
end

.with_rollback(klass) ⇒ Object 



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# File 'lib/benedictus/safety_guard.rb', line 21

def self.with_rollback(klass)
  unless klass.respond_to?(:transaction) && active_record_class?(klass)
    raise ArgumentError, "klass must be an ActiveRecord::Base subclass"
  end

  result = nil
  klass.transaction(requires_new: true) do
    result = yield
    raise ActiveRecord::Rollback
  end
  result
end