sldns_buffer_read_at
sldns_buffer_read_at(buffer, buffer->_position, data, count);
sldns_buffer_read_at(buf, sldns_buffer_limit(buf)-sizeof(expiry),
sldns_buffer_read_at(buf, lim-sizeof(expiry), &expiry, sizeof(expiry));
sldns_buffer_read_at(buf, lim-sizeof(expiry)-sizeof(timestamp),
sldns_buffer_read_at(buffer, buffer->_position, data, count);