int dns_resource_key_equal(const DnsResourceKey *a, const DnsResourceKey *b);
int dns_resource_key_match_rr(const DnsResourceKey *key, const DnsResourceRecord *rr, const char *search_domain);
int dns_resource_key_match_cname(const DnsResourceKey *key, const DnsResourceRecord *rr, const char *search_domain);
+int dns_resource_key_match_soa(const DnsResourceKey *key, const DnsResourceKey *soa);
int dns_resource_key_to_string(const DnsResourceKey *key, char **ret);
DEFINE_TRIVIAL_CLEANUP_FUNC(DnsResourceKey*, dns_resource_key_unref);