5e7cc4144b test: add unit test for CConnman::AddedNodesContain() (Jon Atack)
cc62716920 p2p: do not make automatic outbound connections to addnode peers (Jon Atack)
Pull request description:
to allocate our limited outbound slots correctly, and to ensure addnode
connections benefit from their intended protections.
Our addnode logic usually connects the addnode peers before the automatic
outbound logic does, but not always, as a connection race can occur. If an
addnode peer disconnects us and if it was the only one from its network, there
can be a race between reconnecting to it with the addnode thread, and it being
picked as automatic network-specific outbound peer. Or our internet connection
or router or the addnode peer could be temporarily offline, and then return
online during the automatic outbound thread. Or we could add a new manual peer
using the addnode RPC at that time.
The race can be more apparent when our node doesn't know many peers, or with
networks like cjdns that currently have few bitcoin peers.
When an addnode peer is connected as an automatic outbound peer and is the only
connection we have to a network, it can be protected by our new outbound
eviction logic and persist in the "wrong role".
Finally, there does not seem to be a reason to make block-relay or short-lived
feeler connections to addnode peers, as the addnode logic will ensure we connect
to them if they are up, within the addnode connection limit.
Fix these issues by checking if the address is an addnode peer in our automatic
outbound connection logic.
ACKs for top commit:
mzumsande:
Tested ACK 5e7cc4144b
brunoerg:
utACK 5e7cc4144b
vasild:
ACK 5e7cc4144b
guggero:
utACK 5e7cc4144b
Tree-SHA512: 2438c3ec92e98aebca2a0da960534e4655a9c6e1192a24a085fc01326d95cdb1b67d8c44e4ee706bc1d8af8564126d446a21b5579dcbec61bdea5fce2f0115ee
for initial partial unit test coverage of these CConnman class methods:
- AddNode()
- ConnectNode()
- GetAddedNodeInfo()
- AlreadyConnectedToAddress()
- ThreadOpenAddedConnections()
and of the GetAddedNodeInfo() call in RPC addnode.
