push_prefix
push_prefix(r, FLOWSPEC_TYPE_DEST, &r->flow.dst, r->flow.dstlen);
push_prefix(r, FLOWSPEC_TYPE_SOURCE, &r->flow.src, r->flow.srclen);
if (push_prefix(&$1.prefix, $1.len) == -1)
static int push_prefix(struct bgpd_addr *, uint8_t);