p2p/simulations: introduce dialBan
- Refactor simulations/network connection getters to support
avoiding simultaneous dials between two peers If two peers dial
simultaneously, the connection will be dropped to help avoid
that, we essentially lock the connection object with a
timestamp which serves as a ban on dialing for a period of time
(dialBanTimeout).
- The connection getter InitConn can be wrapped and passed to the
nodes via adapters.NodeConfig#Reachable field and then used by
the respective services when they initiate connections. This
massively stablise the emerging connectivity when running with
hundreds of nodes bootstrapping a network.
p2p: add Inbound public method to p2p.Peer
p2p/simulations: Add server id to logs to support debugging
in-memory network simulations when multiple peers are logging.
p2p: SetupConn now returns error. The dialer checks the error and
only calls resolve if the actual TCP dial fails.
This commit introduces a network simulation framework which
can be used to run simulated networks of devp2p nodes. The
intention is to use this for testing protocols, performing
benchmarks and visualising emergent network behaviour.
The p2p packages can now be configured to restrict all communication to
a certain subset of IP networks. This feature is meant to be used for
private networks.
This change makes it possible to add peers without providing their IP
address. The endpoint of the target node is resolved using the discovery
protocol.
Lookup calls would spin out of control when network connectivity was
lost. The throttling that was in place only took effect when the table
returned zero results, which doesn't happen very often.
The new throttling should not have a negative impact when the host is
online. Lookups against the network take some time and dials for all
results must complete or hit the cache before a new one is started. This
usually takes longer than four seconds, leaving online lookups
unaffected.
Fixes#1296
The most visible change is event-based dialing, which should be an
improvement over the timer-based system that we have at the moment.
The dialer gets a chance to compute new tasks whenever peers change or
dials complete. This is better than checking peers on a timer because
dials happen faster. The dialer can now make more precise decisions
about whom to dial based on the peer set and we can test those
decisions without actually opening any sockets.
Peer management is easier to test because the tests can inject
connections at checkpoints (after enc handshake, after protocol
handshake).
Most of the handshake stuff is now part of the RLPx code. It could be
exported or move to its own package because it is no longer entangled
with Server logic.
