[dht] concurrent queries

More code encapsulated in objects method is better for keeping consistent
behavior.

The code preceding this would just not take multiple concurrent queries for a
same search into account. This is a bug fix for a bad behavior since the
queries.

The criteria has been rewritten (again) exploiting the idea behind the parameter
'update' to take into account the case where we have new distinct requests to
send, then bypass some checks.

Simon Désaulniers authored 8 years ago and Adrien Béraud committed 8 years ago

The 'put' operation will now first check if nodes already store the value we
have to announce. If so, we don't announce it to that node.

dht: Dht::insertNode has to really insert

crypto: drop support for GnuTLS < 3.3

crypto: add length parameters

dht: fail pending operations before clearing them

* add Prefix Hash Tree (PHT) for data indexation (Nicolas Reynaud, Simon Désaulniers)
* add Queries (Simon Désaulniers)
* add long-term data persistance (Simon Désaulniers)
* add data pagination (Simon Désaulniers)
* reduced bandwith usage

kaldoran authored 8 years ago and Adrien Béraud committed 8 years ago

When the put is performed just after a get, then the get will not include the value which was in the put.