nf_rec = ofpbuf_put_zeros(&nf->packet, sizeof *nf_rec);
nf_rec->src_addr = expired->flow.nw_src;
nf_rec->dst_addr = expired->flow.nw_dst;
nf_rec = ofpbuf_put_zeros(&nf->packet, sizeof *nf_rec);
nf_rec->src_addr = expired->flow.nw_src;
nf_rec->dst_addr = expired->flow.nw_dst;