message: add exec.php
diff: <file role="src" name="readfile.php" />
  <file role="src" name="write.php" />
  <file role="src" name="dns_lookup.php" />
  + <file role="src" name="exec.php" />
  </dir>
  <dir name="client">
  <file role="src" name="async.php" />
  