-struct IODNSQuery *iodns_getaddrinfo(char *hostname, int records, iodns_callback *callback);
-struct IODNSQuery *iodns_getnameinfo(const struct sockaddr *addr, size_t addrlen, iodns_callback *callback);
+struct IODNSQuery *iodns_getaddrinfo(char *hostname, int records, iodns_callback *callback, void *arg);
+struct IODNSQuery *iodns_getnameinfo(const struct sockaddr *addr, size_t addrlen, iodns_callback *callback, void *arg);