Merge #19339: validation: re-delegate absurd fee checking from mempool to clients

b048b275d9711f70847afaea5450f17a0f7e673a [validation] Remove absurdfee from accepttomempool (John Newbery)
932564b9cfda8446a957649c2316a52e868ad5d4 scripted-diff: update max-fee-exceeded error message to include RPC (gzhao408)
8f1290c60159a3171c27250bc95687548c5c1b84 [rpc/node] check for high fee before ATMP in clients (gzhao408)

Pull request description:

  Picked up from #15810. Add separate fee-checking logic for clients that need to enforce max fee rates, then remove the `absurdFee` logic from ATMP.

  ATMP's `nAbsurdFee` argument is used to enforce user-specific behavior (it is not policy since it isn't applied consistently: it is only ever used in RPC and wallet, and set to 0 everywhere else internally). It should be removed from `AcceptToMemoryPool` because (1) validation results/mempool behavior should not be user-specific and (2) enforcing a max fee rate should be the responsibility of the client instead of the mempool.

  Note: this PR does not intend to _remove_ protection from high fees, just re-delegate the responsibility to clients.

ACKs for top commit:
  jnewbery:
    utACK b048b275d9711f70847afaea5450f17a0f7e673a
  LarryRuane:
    re-ACK b048b275d9711f70847afaea5450f17a0f7e673a
  MarcoFalke:
    re-ACK b048b275d9 , only change is squashing one commit 🏦
  instagibbs:
    utACK https://github.com/bitcoin/bitcoin/pull/19339/commits/b048b275d9711f70847afaea5450f17a0f7e673a

Tree-SHA512: 57c17ba16d230a4cae2896dd6a64c924f307757824e35784bf96da7b10aff2d8ea910710edf35e981035623a155f8766209a92a0fdb856549fde78bc3eaae4d2

1 files changed, 6 insertions, 12 deletions

diff --git a/src/validation.cpp b/src/validation.cpp
index e9c0607ce..06b9b36fc 100644
--- a/src/validation.cpp
+++ b/src/validation.cpp
@@ -384,7 +384,7 @@ static void UpdateMempoolForReorg(CTxMemPool& mempool, DisconnectedBlockTransact
         TxValidationState stateDummy;
         if (!fAddToMempool || (*it)->IsCoinBase() ||
             !AcceptToMemoryPool(mempool, stateDummy, *it,
-                                nullptr /* plTxnReplaced */, true /* bypass_limits */, 0 /* nAbsurdFee */)) {
+                                nullptr /* plTxnReplaced */, true /* bypass_limits */)) {
             // If the transaction doesn't make it in to the mempool, remove any
             // transactions that depend on it (which would now be orphans).
             mempool.removeRecursive(**it, MemPoolRemovalReason::REORG);
@@ -463,7 +463,6 @@ public:
         const int64_t m_accept_time;
         std::list<CTransactionRef>* m_replaced_transactions;
         const bool m_bypass_limits;
-        const CAmount& m_absurd_fee;
         /*
          * Return any outpoints which were not previously present in the coins
          * cache, but were added as a result of validating the tx for mempool
@@ -558,7 +557,6 @@ bool MemPoolAccept::PreChecks(ATMPArgs& args, Workspace& ws)
     TxValidationState &state = args.m_state;
     const int64_t nAcceptTime = args.m_accept_time;
     const bool bypass_limits = args.m_bypass_limits;
-    const CAmount& nAbsurdFee = args.m_absurd_fee;
     std::vector<COutPoint>& coins_to_uncache = args.m_coins_to_uncache;
 
     // Alias what we need out of ws
@@ -729,10 +727,6 @@ bool MemPoolAccept::PreChecks(ATMPArgs& args, Workspace& ws)
     // blocks
     if (!bypass_limits && !CheckFeeRate(nSize, nModifiedFees, state)) return false;
 
-    if (nAbsurdFee && nFees > nAbsurdFee)
-        return state.Invalid(TxValidationResult::TX_NOT_STANDARD,
-                "absurdly-high-fee", strprintf("%d > %d", nFees, nAbsurdFee));
-
     const CTxMemPool::setEntries setIterConflicting = m_pool.GetIterSet(setConflicts);
     // Calculate in-mempool ancestors, up to a limit.
     if (setConflicts.size() == 1) {
@@ -1065,10 +1059,10 @@ bool MemPoolAccept::AcceptSingleTransaction(const CTransactionRef& ptx, ATMPArgs
 /** (try to) add transaction to memory pool with a specified acceptance time **/
 static bool AcceptToMemoryPoolWithTime(const CChainParams& chainparams, CTxMemPool& pool, TxValidationState &state, const CTransactionRef &tx,
                         int64_t nAcceptTime, std::list<CTransactionRef>* plTxnReplaced,
-                        bool bypass_limits, const CAmount nAbsurdFee, bool test_accept, CAmount* fee_out=nullptr) EXCLUSIVE_LOCKS_REQUIRED(cs_main)
+                        bool bypass_limits, bool test_accept, CAmount* fee_out=nullptr) EXCLUSIVE_LOCKS_REQUIRED(cs_main)
 {
     std::vector<COutPoint> coins_to_uncache;
-    MemPoolAccept::ATMPArgs args { chainparams, state, nAcceptTime, plTxnReplaced, bypass_limits, nAbsurdFee, coins_to_uncache, test_accept, fee_out };
+    MemPoolAccept::ATMPArgs args { chainparams, state, nAcceptTime, plTxnReplaced, bypass_limits, coins_to_uncache, test_accept, fee_out };
     bool res = MemPoolAccept(pool).AcceptSingleTransaction(tx, args);
     if (!res) {
         // Remove coins that were not present in the coins cache before calling ATMPW;
@@ -1087,10 +1081,10 @@ static bool AcceptToMemoryPoolWithTime(const CChainParams& chainparams, CTxMemPo
 
 bool AcceptToMemoryPool(CTxMemPool& pool, TxValidationState &state, const CTransactionRef &tx,
                         std::list<CTransactionRef>* plTxnReplaced,
-                        bool bypass_limits, const CAmount nAbsurdFee, bool test_accept, CAmount* fee_out)
+                        bool bypass_limits, bool test_accept, CAmount* fee_out)
 {
     const CChainParams& chainparams = Params();
-    return AcceptToMemoryPoolWithTime(chainparams, pool, state, tx, GetTime(), plTxnReplaced, bypass_limits, nAbsurdFee, test_accept, fee_out);
+    return AcceptToMemoryPoolWithTime(chainparams, pool, state, tx, GetTime(), plTxnReplaced, bypass_limits, test_accept, fee_out);
 }
 
 CTransactionRef GetTransaction(const CBlockIndex* const block_index, const CTxMemPool* const mempool, const uint256& hash, const Consensus::Params& consensusParams, uint256& hashBlock)
@@ -5079,7 +5073,7 @@ bool LoadMempool(CTxMemPool& pool)
             if (nTime + nExpiryTimeout > nNow) {
                 LOCK(cs_main);
                 AcceptToMemoryPoolWithTime(chainparams, pool, state, tx, nTime,
-                                           nullptr /* plTxnReplaced */, false /* bypass_limits */, 0 /* nAbsurdFee */,
+                                           nullptr /* plTxnReplaced */, false /* bypass_limits */,
                                            false /* test_accept */);
                 if (state.IsValid()) {
                     ++count;