uniqdn
RB_ENTRY(uniqdn) link;
RB_HEAD(dn_tree, uniqdn);
RB_PROTOTYPE(dn_tree, uniqdn, link, uniqdn_cmp);
struct uniqdn *dn, *next;
struct uniqdn *udn;
struct uniqdn find;
uniqdn_cmp(struct uniqdn *a, struct uniqdn *b)
RB_GENERATE(dn_tree, uniqdn, link, uniqdn_cmp);