ExternalResourceClient CURLINFO_HEADER_SIZE

Hi,

I have the following line of code I have to replace with the ExternalResourceClient, but it is not really clear how to get the header size from the ExternalResourceClient...

$resp_header_size = curl_getinfo ( $ch, CURLINFO_HEADER_SIZE );

Any ideas how to get this and other useful header information?

Thanks in advance,

Stijn