Merge bitcoin/bitcoin#23631: p2p: Don't use timestamps from inbound peers for Adjusted Time

0c85dc30e6b628f7538a67776c7eefcb84ef4f82 p2p: Don't use timestamps from inbound peers (Martin Zumsande)

Pull request description:

  `GetAdjustedTime()` (used e.g. in validation and addrman) returns a time with an offset that is influenced by timestamps that our peers have sent us in their version message.

  Currently, timestamps from all peers are used for this.
  However, I think that it would make sense to ignore the timedata samples from inbound peers, making it much harder for others to influence the Adjusted Time in a targeted way.
  With the extra feeler connections (every 2 minutes on average) and extra block-relay-only connections (every 5 minutes on average) there are also now plenty of opportunities to gather a meaningful number of timedata samples from outbound peers.

  There are some measures in place to prevent abuse: the `-maxtimeadjustment` parameter with a default of 70 minutes, warnings in cases of large deviations, only using the first 200 samples ([explanation](383d350bd5/src/timedata.cpp (L57-L72))), but I think that only using samples from outbound connections in the first place would be an additional safety measure that would make sense.

  See also issue #4521 for further context and links: There have been several discussions in the past about replacing or abolishing the existing timedata system.

ACKs for top commit:
  jnewbery:
    Concept and code review ACK 0c85dc30e6b628f7538a67776c7eefcb84ef4f82
  naumenkogs:
    ACK 0c85dc30e6b628f7538a67776c7eefcb84ef4f82
  vasild:
    ACK 0c85dc30e6b628f7538a67776c7eefcb84ef4f82

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This commit is contained in:
Vijay 2024-11-24 21:02:27 +05:30
parent abfa8c0bd4
commit e101fd8e3b
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@ -3651,7 +3651,11 @@ void PeerManagerImpl::ProcessMessage(
int64_t nTimeOffset = nTime - GetTime(); int64_t nTimeOffset = nTime - GetTime();
pfrom.nTimeOffset = nTimeOffset; pfrom.nTimeOffset = nTimeOffset;
AddTimeData(pfrom.addr, nTimeOffset); if (!pfrom.IsInboundConn()) {
// Don't use timedata samples from inbound peers to make it
// harder for others to tamper with our adjusted time.
AddTimeData(pfrom.addr, nTimeOffset);
}
// Feeler connections exist only to verify if address is online. // Feeler connections exist only to verify if address is online.
if (pfrom.IsFeelerConn()) { if (pfrom.IsFeelerConn()) {