def getServerPrincipalDetails(service, hostname):
    """
    This function returns the service principal for the server given a service
    type and hostname.
    Details are looked up via the C{/etc/keytab} file.

    @param service: A string containing the Kerberos service type for the
        server.

    @param hostname: A string containing the hostname of the server.

    @return: A string containing the service principal.
    """
