Module: LogicaCompiler::SqlSafety

Defined in:
lib/logica_compiler/sql_safety.rb

Constant Summary collapse

PROHIBITED_KEYWORDS = 
%w[
  INSERT UPDATE DELETE MERGE
  CREATE ALTER DROP TRUNCATE
  GRANT REVOKE
].freeze

Class Method Summary collapse

Class Method Details

.parse_dollar_delimiter(s, start_index) ⇒ Object 



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# File 'lib/logica_compiler/sql_safety.rb', line 161

def parse_dollar_delimiter(s, start_index)
  return nil unless s[start_index] == "$"

  j = start_index + 1
  while j < s.length && s[j] != "$"
    return nil unless s[j].match?(/[A-Za-z0-9_]/)

    j += 1
  end

  return nil unless j < s.length && s[j] == "$"

  s[start_index..j]
end

.strip_leading_comments(sql) ⇒ Object 



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# File 'lib/logica_compiler/sql_safety.rb', line 36

def strip_leading_comments(sql)
  s = sql.lstrip

  loop do
    if s.start_with?("--")
      s = s.sub(/\A--.*(?:\n|\z)/, "").lstrip
      next
    end

    if s.start_with?("/*")
      s = s.sub(%r{\A/\*.*?\*/}m, "").lstrip
      next
    end

    break
  end

  s
end

.strip_strings_and_comments(sql) ⇒ Object 



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# File 'lib/logica_compiler/sql_safety.rb', line 56

def strip_strings_and_comments(sql)
  s = sql.to_s
  out = +""

  i = 0
  state = :normal
  dollar_delim = nil

  while i < s.length
    ch = s[i]

    case state
    when :normal
      if ch == "-" && s[i + 1] == "-"
        state = :line_comment
        out << "  "
        i += 2
      elsif ch == "/" && s[i + 1] == "*"
        state = :block_comment
        out << "  "
        i += 2
      elsif ch == "'"
        state = :single_quote
        out << " "
        i += 1
      elsif ch == "\""
        state = :double_quote
        out << " "
        i += 1
      elsif ch == "$"
        delim = parse_dollar_delimiter(s, i)
        if delim
          dollar_delim = delim
          state = :dollar_quote
          out << (" " * delim.length)
          i += delim.length
        else
          out << ch
          i += 1
        end
      else
        out << ch
        i += 1
      end
    when :line_comment
      if ch == "\n"
        state = :normal
        out << "\n"
      else
        out << " "
      end
      i += 1
    when :block_comment
      if ch == "*" && s[i + 1] == "/"
        state = :normal
        out << "  "
        i += 2
      else
        out << " "
        i += 1
      end
    when :single_quote
      if ch == "'"
        if s[i + 1] == "'"
          out << "  "
          i += 2
        else
          state = :normal
          out << " "
          i += 1
        end
      else
        out << " "
        i += 1
      end
    when :double_quote
      if ch == "\""
        if s[i + 1] == "\""
          out << "  "
          i += 2
        else
          state = :normal
          out << " "
          i += 1
        end
      else
        out << " "
        i += 1
      end
    when :dollar_quote
      if dollar_delim && s[i, dollar_delim.length] == dollar_delim
        out << (" " * dollar_delim.length)
        i += dollar_delim.length
        dollar_delim = nil
        state = :normal
      else
        out << " "
        i += 1
      end
    end
  end

  out
end

.validate!(sql) ⇒ Object

Raises:



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# File 'lib/logica_compiler/sql_safety.rb', line 15

def validate!(sql)
  stripped = strip_leading_comments(sql.to_s).lstrip
  raise UnsafeSqlError, "SQL is empty" if stripped.empty?

  raise UnsafeSqlError, "Unsafe SQL: must start with SELECT/WITH" unless stripped.match?(/\A(?:WITH|SELECT)\b/i)

  sanitized = strip_strings_and_comments(stripped)

  raise UnsafeSqlError, "Unsafe SQL: contains semicolon (multi-statement risk)" if sanitized.include?(";")

  if sanitized.match?(/\b(?:#{PROHIBITED_KEYWORDS.join("|")})\b/i)
    raise UnsafeSqlError, "Unsafe SQL: contains prohibited keyword"
  end

  if sanitized.match?(/\bFOR\s+(?:UPDATE|SHARE|NO\s+KEY\s+UPDATE|KEY\s+SHARE)\b/i)
    raise UnsafeSqlError, "Unsafe SQL: contains row locking clause"
  end

  true
end