CDbConnection with attributes OCI_CRE_EXT oracle

Hi guys! I should pass the OCI_CRED_EXT attribute to the oci connection for external authentication via wallet. How can it be done ?

es.: $c1 = OCI_connect("/", “” , $db, NULL, OCI_CRED_EXT);

if anyone has any ideas or suggestions it would be greatly appreciated
Thank you so much