PRInt32 port; nsresult rv = m_url->GetPort(&port); if (NS_FAILED(rv)) return rv;  rv = NS_CheckPortSafety(port, "mailto"); if (NS_FAILED(rv)) return rv;
NS_IMETHODIMP nsMailtoChannel::AsyncOpen(nsIStreamListener *listener, nsISupports *ctxt){  PRInt32 port;  nsresult rv = m_url->GetPort(&port);  if (NS_FAILED(rv))      return rv;   rv = NS_CheckPortSafety(port, "mailto");  if (NS_FAILED(rv))      return rv;  mStatus = listener->OnStartRequest(this, ctxt);  // If OnStartRequest(...) failed, then propagate the error code...  if (NS_SUCCEEDED(mStatus)) {    // Otherwise, indicate that no content is available...    mStatus = NS_ERROR_NO_CONTENT;  }  // Call OnStopRequest(...) for correct-ness.  (void) listener->OnStopRequest(this, ctxt, mStatus);  // Always return NS_ERROR_NO_CONTENT since this channel never provides  // data...  return NS_ERROR_NO_CONTENT;}