This change adds adds an ability to use different source of time for whisper:
when envelope is created it is used to set expiry
to track when envelope needs to be expired
This time is then used to check validity of the envelope when it is received. Currently If we receive an envelope that is sent from future - peer will get disconnected. If envelope that was received has an expiry less then now it will be simply dropped, if expiry is less than now + 10*2 seconds peer will get dropped.
So, it is clear that whisper depends on time. And any time we get a skew with peers that is > 20s reliability will be grealy reduced.
In this change another source of time for whisper will be used. This time source will use ntp servers from pool.ntp.org to compute offset. When whisper queries time - this offset will be added/substracted from current time.
Query is executed every 2 mins, queries 5 different servers, cut offs min and max and the computes mean value. pool.ntp.org is resolved to different servers and according to documentation you will rarely hit the same.
Closes: #687
* Rebase on 1.8.5
* Remove outdated patches and apply all others
* Use shh_post that returns hash
* Use bloom filter for request to mailserver
* Remove tests for sending messages without subbing first
* Fix deadlock in ethdb
* Expect null if receipt is not yet created
* Subscribe to messages before sending them in whisper test
* Implement shh api extension that allows to confirm that message is sent
* Add a patch
* Fix linter
* Add readme
* Add tests for tracker
* Address review
* Update project to use Whisper v6. Part of #638
* Revert "Add patch to downgrade usage of Whisper v6 to v5 in some geth 1.8.1 vendor files. Part of #665" - this reverts commit 6aefb4c8fd02dbcfffac6b69e8bb22b13ef86b6b.
* Enable light mode on Whisper v6 for non-mail servers. Part of #638
* Fix race condition in whisperv6/peer.go. Part of #665 (PR already accepted upstream for 1.8.2)
* Update bootnode addresses in staticnodes.json. Part of #638
* Add `shh.lightclient` flag and tests for bloom filter setting logic. Part of #638
* Move MakeTestNodeConfig to utils. Part of #638
* Reduce PoW in `whisper_jail_test.go` to fix flaky test. Part of #638
Dmitry Shulyak
Igor Mandrigin
Evgeny Danienko
Pedro Pombeiro
Alex Kohler
Ivan Daniluk