Merge bitcoin/bitcoin#25353: Add a `-mempoolfullrbf` node setting

4c9666bd73645b94ae81be1faf7a0b8237dd6e99 Mention `mempoolfullrbf` in policy/mempool-replacements.md (Antoine Riard)
aae66ab43d794bdfaa2dade91760cc55861c9693 Update getmempoolinfo RPC with `mempoolfullrbf` (Antoine Riard)
3e27e317270fdc2dd02794fea9da016387699636 Introduce `mempoolfullrbf` node setting. (Antoine Riard)

Pull request description:

  This is ready for review.

  Recent discussions among LN devs have brought back on the surface concerns about the security of multi-party funded transactions against pinnings attacks and other mempool-based nuisances. The lack of full-rbf transaction-relay topology connected to miners open the way to cheap and naive DoS against multi-party funded transactions (e.g coinjoins, dual-funded channels, on-chain DLCs, ...) without solutions introducing an overhead cost or centralization vectors afaik . For more details, see [0].

  This PR implements a simple `fullrbf` setting, where the node always allows transaction replacement, ignoring BIP125 opt-in flag. The default value of the setting stays **false**, therefore opt-in replacement is still the default Bitcoin Core replacement policy. Contrary to a previous proposal of mine and listening to feedbacks collected since then [1], I think this new setting simply offers more flexibility in a node transaction-relay policy suiting one's application requirements, without arguing a change of the default behavior.

  I [posted](https://lists.linuxfoundation.org/pipermail/bitcoin-dev/2022-June/020557.html) on the ML to invite operators with a bitcoin application sensitive to full-rbf (e.g dual-funded LN channels service providers) or mempool researchers to join a bootstrapped full-rbf activated peers network for experimentation and learning. If people have strong opinions against the existence of such full-rbf transaction-relay network, I'm proposing to express them on the future thread.

  [0] https://lists.linuxfoundation.org/pipermail/lightning-dev/2021-May/003033.html
  [1] https://lists.linuxfoundation.org/pipermail/bitcoin-dev/2021-June/019074.html

  Follow-up suggestions :
  - soft-enable opt-in RBF in the wallet : https://github.com/bitcoin/bitcoin/pull/25353#issuecomment-1154918789
  - p2p discovery and additional outbound connection to full-rbf peers : https://github.com/bitcoin/bitcoin/pull/25353#issuecomment-1156044401
  - match the code between RPC, wallet and mempool about disregard of inherited signaling : #22698

ACKs for top commit:
  instagibbs:
    reACK https://github.com/bitcoin/bitcoin/pull/25353/commits/4c9666bd73645b94ae81be1faf7a0b8237dd6e99
  glozow:
    ACK 4c9666bd73645b94ae81be1faf7a0b8237dd6e99, a few nits which are non-blocking.
  w0xlt:
    ACK https://github.com/bitcoin/bitcoin/pull/25353/commits/4c9666bd73645b94ae81be1faf7a0b8237dd6e99

Tree-SHA512: 9e288bf22e06a9808804e58178444ef1830c3fdd42fd8a7cd7ffb101f8f586e08b000679be407d63ca76a56f7216227b368ff630c81f3fac3243db1a1202ab1c

1 files changed, 1 insertions, 0 deletions

diff --git a/src/init.cpp b/src/init.cpp
index d844e9b169..eff37e1a83 100644
--- a/src/init.cpp
+++ b/src/init.cpp
@@ -558,6 +558,7 @@ void SetupServerArgs(ArgsManager& argsman)
     argsman.AddArg("-bytespersigop", strprintf("Equivalent bytes per sigop in transactions for relay and mining (default: %u)", DEFAULT_BYTES_PER_SIGOP), ArgsManager::ALLOW_ANY, OptionsCategory::NODE_RELAY);
     argsman.AddArg("-datacarrier", strprintf("Relay and mine data carrier transactions (default: %u)", DEFAULT_ACCEPT_DATACARRIER), ArgsManager::ALLOW_ANY, OptionsCategory::NODE_RELAY);
     argsman.AddArg("-datacarriersize", strprintf("Maximum size of data in data carrier transactions we relay and mine (default: %u)", MAX_OP_RETURN_RELAY), ArgsManager::ALLOW_ANY, OptionsCategory::NODE_RELAY);
+    argsman.AddArg("-mempoolfullrbf", strprintf("Accept transaction replace-by-fee without requiring replaceability signaling (default: %u)", DEFAULT_MEMPOOL_FULL_RBF), ArgsManager::ALLOW_ANY, OptionsCategory::NODE_RELAY);
     argsman.AddArg("-minrelaytxfee=<amt>", strprintf("Fees (in %s/kvB) smaller than this are considered zero fee for relaying, mining and transaction creation (default: %s)",
         CURRENCY_UNIT, FormatMoney(DEFAULT_MIN_RELAY_TX_FEE)), ArgsManager::ALLOW_ANY, OptionsCategory::NODE_RELAY);
     argsman.AddArg("-whitelistforcerelay", strprintf("Add 'forcerelay' permission to whitelisted inbound peers with default permissions. This will relay transactions even if the transactions were already in the mempool. (default: %d)", DEFAULT_WHITELISTFORCERELAY), ArgsManager::ALLOW_ANY, OptionsCategory::NODE_RELAY);