ELEMENTS: cherry-picked before ElementsProject/elements#1472 for ease of
merge
16bd283b3a Reapply "test: p2p: check that connecting to ourself leads to disconnect" (Sebastian Falbesoner)
0dbcd4c148 net: prevent sending messages in `NetEventsInterface::InitializeNode` (Sebastian Falbesoner)
66673f1c13 net: fix race condition in self-connect detection (Sebastian Falbesoner)
Pull request description:
This PR fixes a recently discovered race condition in the self-connect detection (see #30362 and #30368).
Initiating an outbound network connection currently involves the following steps after the socket connection is established (see [`CConnman::OpenNetworkConnection`](bd5d1688b4/src/net.cpp (L2923-L2930)) method):
1. set up node state
2. queue VERSION message (both steps 1 and 2 happen in [`InitializeNode`](bd5d1688b4/src/net_processing.cpp (L1662-L1683)))
3. add new node to vector `m_nodes`
If we connect to ourself, it can happen that the sent VERSION message (step 2) is received and processed locally *before* the node object is added to the connection manager's `m_nodes` vector (step 3). In this case, the self-connect remains undiscovered, as the detection doesn't find the outbound peer in `m_nodes` yet (see `CConnman::CheckIncomingNonce`).
Fix this by swapping the order of 2. and 3., by taking the `PushNodeVersion` call out of `InitializeNode` and doing that in the `SendMessages` method instead, which is only called for `CNode` instances in `m_nodes`.
The temporarily reverted test introduced in #30362 is readded. Fixes#30368.
Thanks go to vasild, mzumsande and dergoegge for suggestions on how to fix this (see https://github.com/bitcoin/bitcoin/issues/30368#issuecomment-2200625017 ff. and https://github.com/bitcoin/bitcoin/pull/30394#discussion_r1668290789).
ACKs for top commit:
naiyoma:
tested ACK [https://github.com/bitcoin/bitcoin/pull/30394/commits/16bd283b3ad05daa41259a062aee0fc05b463fa6](https://github.com/bitcoin/bitcoin/pull/30394/commits/16bd283b3ad05daa41259a062aee0fc05b463fa6), built and tested locally, test passes successfully.
mzumsande:
ACK 16bd283b3a
tdb3:
ACK 16bd283b3a
glozow:
ACK 16bd283b3a
dergoegge:
ACK 16bd283b3a
Tree-SHA512: 5b8aced6cda8deb38d4cd3fe4980b8af505d37ffa0925afaa734c5d81efe9d490dc48a42e1d0d45dd2961c0e1172a3d5b6582ae9a2d642f2592a17fbdc184445
(cherry picked from commit 35dddbccf1)
