unbound/doc/TODO

TODO items.
o use real entropy to make random (ID, port) numbers more random.
o in production mode, do not free memory on exit. In debug mode, test leaks.
o profile memory allocation, and if performance issues, use special memory
  allocator. For example, with caches per thread.
o #define BIT_... different on bigendian and smallendian systems so that
  the htons on flags is not needed to send a message from the cache.
o possible optimization with delayed malloc of msgreply after parse
  (reuse parse structures and ptrs to packet in meantime).
o possible optimization, so that precious id number resource is not depleted
  by parsing of messages. Delay malloc, as above, or try to reverse release
  special id numbers, and if you release the next_id number for the thread
  it reuses that id number.
o use rbtree to compress domain names in messages, sorted AXFRs of 16Kb
  and so on. For current packets, even worstcase, list, is ok. Only if we
  start to send out compressed AXFRs then it becomes a problem.
  We can cap AXFR packets on 256 or 1024 domain names, for example.
o speed up pkt domain name decompression loop detection using counter perhaps.
o detect OS/400 pthreads implementation that allows upgrading to writelock
  on pthreads rwlocks and use it to examine-rd before storing-wr rrset cache.
o understand synthesized DNAMEs, so those TTL=0 packets are cached properly.
o understand NSEC/NSEC3, aggressive negative caching, so that updates to
  NSEC/NSEC3 will result in proper negative responses.
o fallback without EDNS if result is NOTIMPL, now only on FORMERR like in java.
o scrubber has slow pkt_subdomain and pkt_strict_subdomain functions.
o get serverselection algorithm out of local optimum.
o donotqueryaddresses allow specification of subnets, use trie to store.
o memory profile; and if needed put serviced queries under qstate->region
  and special purpose region code, reuse blocks, shrink if too big.
o check query, option to enforce presence of qdsection in noerror answers.
o configuration option where port 53 is used for send and receive, no other
  ports are used.