* tcpsent timew null >=0 irrelevant zero any
*
* child childw set >=0 irrelevant irrelevant irrelevant
+ * child NONE null >=0 irrelevant irrelevant irrelevant
* done output null -1 irrelevant irrelevant irrelevant
*
+ * Queries are only not on a queue when they are actually being processed.
+ *
* +------------------------+
* START -----> | udp/NONE |
* +------------------------+
* succeeds or fails (if it succeeds, the vbuf is reused for qu->vb).
*
* *ctx is copied byte-for-byte into the query.
+ *
+ * When the child query is done, ctx->callback will be called. The
+ * child will already have been taken off both the global list of
+ * queries in ads and the list of children in the parent. The child
+ * will be freed when the callback returns. The parent will have been
+ * taken off the global childw queue iff this is the last child for
+ * that parent. If there is no error detected in the callback, then
+ * it should call adns__query_done if and only if there are no more
+ * children (by checking parent->children.head). If an error is
+ * detected in the callback it should call adns__query_fail and any
+ * remaining children will automatically be cancelled.
*/
void adns__search_next(adns_state ads, adns_query qu, struct timeval now);