Merge bitcoin/bitcoin#24021: Rename and move PoissonNextSend functions

9b8dcb25b57ad31b77c9f37d9a1f5b07dc6378b4 [net processing] Rename PoissonNextSendInbound to NextInvToInbounds (John Newbery)
ea99f5d01e56ab0192d211da1034ffb299876937 [net processing] Move PoissonNextSendInbound to PeerManager (John Newbery)
bb060746df22c956b8f44e5b8cd1ae4ed73faddc scripted-diff: replace PoissonNextSend with GetExponentialRand (John Newbery)
03cfa1b6035dbcf6a414f9bc432bd9e612801ebb [refactor] Use uint64_t and std namespace in PoissonNextSend (John Newbery)
9e64d69bf74c8a381fb59841519cc3736bce14d4 [move] Move PoissonNextSend to src/random and update comment (John Newbery)

Pull request description:

  `PoissonNextSend` and `PoissonNextSendInbound` are used in the p2p code to obfuscate various regularly occurring processes, in order to make it harder for others to get timing-based information deterministically.

  The naming of these functions has been confusing to several people (including myself, see also #23347) because the resulting random timestamps don't follow a Poisson distribution but an exponential distribution (related to events in a Poisson process, hence the name). This PR
  - moves `PoissonNextSend()` out of `net` to `random` and renames it to `GetExponentialRand()`
  - moves `PoissonNextSendInbound()` out of `CConnman` to `PeerManager` and renames it to `NextInvToInbounds()`
  - adds documentation for these functions

  This is work by jnewbery - due to him being less active currently, I opened the PR and will address feedback.

ACKs for top commit:
  jnewbery:
    ACK 9b8dcb25b5
  hebasto:
    ACK 9b8dcb25b57ad31b77c9f37d9a1f5b07dc6378b4, I have reviewed the code and it looks OK, I agree it can be merged.
  theStack:
    ACK 9b8dcb25b57ad31b77c9f37d9a1f5b07dc6378b4 📊

Tree-SHA512: 85c366c994e7147f9981fe863fb9838502643fa61ffd32d55a43feef96a38b79a5daa2c4d38ce01074897cc95fa40c76779816edad53f5265b81b05c3a1f4f50

1 files changed, 0 insertions, 11 deletions

diff --git a/src/net.h b/src/net.h
index 1f0ebedcf9..24725840cf 100644
--- a/src/net.h
+++ b/src/net.h
@@ -936,12 +936,6 @@ public:
 
     void WakeMessageHandler();
 
-    /** Attempts to obfuscate tx time through exponentially distributed emitting.
-        Works assuming that a single interval is used.
-        Variable intervals will result in privacy decrease.
-    */
-    std::chrono::microseconds PoissonNextSendInbound(std::chrono::microseconds now, std::chrono::seconds average_interval);
-
     /** Return true if we should disconnect the peer for failing an inactivity check. */
     bool ShouldRunInactivityChecks(const CNode& node, std::chrono::seconds now) const;
 
@@ -1221,8 +1215,6 @@ private:
      */
     std::atomic_bool m_start_extra_block_relay_peers{false};
 
-    std::atomic<std::chrono::microseconds> m_next_send_inv_to_incoming{0us};
-
     /**
      * A vector of -bind=<address>:<port>=onion arguments each of which is
      * an address and port that are designated for incoming Tor connections.
@@ -1270,9 +1262,6 @@ private:
     friend struct ConnmanTestMsg;
 };
 
-/** Return a timestamp in the future (in microseconds) for exponentially distributed events. */
-std::chrono::microseconds PoissonNextSend(std::chrono::microseconds now, std::chrono::seconds average_interval);
-
 /** Dump binary message to file, with timestamp */
 void CaptureMessage(const CAddress& addr, const std::string& msg_type, const Span<const unsigned char>& data, bool is_incoming);