Merge #17985: net: Remove forcerelay of rejected txs

facb71576cd4d2e90fd03e09d29b42fa3d730e8c net: Remove forcerelay of rejected txs (MarcoFalke)

Pull request description:

  This removes the code that supposedly handled the forced relay of txs from a permissioned peer that were rejected from our mempool. The removal should be fine, because it is dead code for the following reasons:

  * While `RelayTransaction` enqueues the inv for all peers, the inv is never processed because it can not be found in the mempool. See https://github.com/bitcoin/bitcoin/blob/4a072330763b3ff2d1b5c5b8d30a9517873ac6de/src/net_processing.cpp#L3862-L3866

  * Even if the peers we intended to send the inv to can somehow reply with a getdata to the never-received inv, they won't receive the tx as a reply because it was never added to the "relay memory" (`mapRelay`)

  The dead code is (obviously) untested: https://marcofalke.github.io/btc_cov/total.coverage/src/net_processing.cpp.gcov.html#2574

  This feature was (intentionally or accidentally) removed in 4d8993b3469915d8c9ba4cd3b918f16782edf0de, which was released in Bitcoin Core 0.13.0. So all currently supported versions of Bitcoin Core ship without this feature. I am not aware of any complaints about this feature or actual documented use-cases. So instead of reviving an unneeded feature, just remove the dead code.

ACKs for top commit:
  hebasto:
    ACK facb71576cd4d2e90fd03e09d29b42fa3d730e8c, locally running the unit and functional tests.

Tree-SHA512: bfceae6f2983c1510fa0649a9a63c343cbbc1c4ab3a3698039cccf454c81e58c8f5114b147ed42a1bc867da74c43a5b53764ab14f942e191b6f59079044108b5

1 files changed, 6 insertions, 24 deletions

diff --git a/src/net_processing.cpp b/src/net_processing.cpp
index cf4aee064..1c1046b6f 100644
--- a/src/net_processing.cpp
+++ b/src/net_processing.cpp
@@ -987,15 +987,6 @@ void Misbehaving(NodeId pnode, int howmuch, const std::string& message) EXCLUSIV
 }
 
 /**
- * Returns true if the given validation state result may result in a peer
- * banning/disconnecting us. We use this to determine which unaccepted
- * transactions from a whitelisted peer that we can safely relay.
- */
-static bool TxRelayMayResultInDisconnect(const TxValidationState& state) {
-    return state.GetResult() == TxValidationResult::TX_CONSENSUS;
-}
-
-/**
  * Potentially ban a node based on the contents of a BlockValidationState object
  *
  * @param[in] via_compact_block this bool is passed in because net_processing should
@@ -1064,10 +1055,9 @@ static bool MaybePunishNodeForBlock(NodeId nodeid, const BlockValidationState& s
  * Potentially ban a node based on the contents of a TxValidationState object
  *
  * @return Returns true if the peer was punished (probably disconnected)
- *
- * Changes here may need to be reflected in TxRelayMayResultInDisconnect().
  */
-static bool MaybePunishNodeForTx(NodeId nodeid, const TxValidationState& state, const std::string& message = "") {
+static bool MaybePunishNodeForTx(NodeId nodeid, const TxValidationState& state, const std::string& message = "")
+{
     switch (state.GetResult()) {
     case TxValidationResult::TX_RESULT_UNSET:
         break;
@@ -1095,11 +1085,6 @@ static bool MaybePunishNodeForTx(NodeId nodeid, const TxValidationState& state,
 }
 
 
-
-
-
-
-
 //////////////////////////////////////////////////////////////////////////////
 //
 // blockchain -> download logic notification
@@ -2615,14 +2600,11 @@ bool static ProcessMessage(CNode* pfrom, const std::string& strCommand, CDataStr
 
             if (pfrom->HasPermission(PF_FORCERELAY)) {
                 // Always relay transactions received from whitelisted peers, even
-                // if they were already in the mempool or rejected from it due
-                // to policy, allowing the node to function as a gateway for
+                // if they were already in the mempool,
+                // allowing the node to function as a gateway for
                 // nodes hidden behind it.
-                //
-                // Never relay transactions that might result in being
-                // disconnected (or banned).
-                if (state.IsInvalid() && TxRelayMayResultInDisconnect(state)) {
-                    LogPrintf("Not relaying invalid transaction %s from whitelisted peer=%d (%s)\n", tx.GetHash().ToString(), pfrom->GetId(), FormatStateMessage(state));
+                if (!mempool.exists(tx.GetHash())) {
+                    LogPrintf("Not relaying non-mempool transaction %s from whitelisted peer=%d\n", tx.GetHash().ToString(), pfrom->GetId());
                 } else {
                     LogPrintf("Force relaying tx %s from whitelisted peer=%d\n", tx.GetHash().ToString(), pfrom->GetId());
                     RelayTransaction(tx.GetHash(), *connman);