Previously, we would process any valid inventory or refs announcement.
This could cause problems for keeping sync statuses, as we could get
a refs announcement from a node that isn't in our database.
In practice, there is no good reason why we should receive a refs or
inventory announcement before the announcer's node announcement, unless
nodes are not following the protocol.
Implementing this change meant that many of the tests needed updating,
as it wasn't assumed that a node announcement was needed before
receiving inventories etc. from a peer.
We also had to implement a basic form of node address banning to make
the tests pass after this change.
Previously, we would always ask nodes for messages from one hour ago.
This meant that we could miss messages if our node was offline for more
than an hour. This change uses a variable backlog by checking the
timestamp of the last gossip message we received.
Instead of storing received gossip messages in an in-memory `BTreeMap`,
we persist them to the database (`addresses.db`). There are two reasons
for this:
1. Node restarts do not wipe the state, meaning that it is much less
likely that some gossip message will get lost before reaching all
nodes.
2. This will allow us in the next commit to know how far behind we are
after a restart, to be able to request the correct time range of
gossip messages that we missed while offline.
Note that we now share the addresses.db file between two connections and
stores, which we don't do anywhere else. Having multiple connections to
the same database is fine, but the way we're having to do it is a bit
awkward. In a future patch, we could pull out the database schema from the
`address` module and rename the database to make things clearer.
cloudhead