[wallet] Move maxTxFee to wallet

This commit moves the maxtxfee setting to the wallet. There is only
one minor behavior change:

- an error message in feebumper now refers to -maxtxfee instead of
maxTxFee.

17 files changed, 45 insertions, 50 deletions

diff --git a/src/dummywallet.cpp b/src/dummywallet.cpp
index 8a76021a5b..f5141e4962 100644
--- a/src/dummywallet.cpp
+++ b/src/dummywallet.cpp
@@ -24,7 +24,7 @@ public:
 void DummyWalletInit::AddWalletOptions() const
 {
     std::vector<std::string> opts = {"-addresstype", "-changetype", "-disablewallet", "-discardfee=<amt>", "-fallbackfee=<amt>",
-        "-keypool=<n>", "-mintxfee=<amt>", "-paytxfee=<amt>", "-rescan", "-salvagewallet", "-spendzeroconfchange",  "-txconfirmtarget=<n>",
+        "-keypool=<n>", "-maxtxfee=<amt>", "-mintxfee=<amt>", "-paytxfee=<amt>", "-rescan", "-salvagewallet", "-spendzeroconfchange",  "-txconfirmtarget=<n>",
         "-upgradewallet", "-wallet=<path>", "-walletbroadcast", "-walletdir=<dir>", "-walletnotify=<cmd>", "-walletrbf", "-zapwallettxes=<mode>",
         "-dblogsize=<n>", "-flushwallet", "-privdb", "-walletrejectlongchains"};
     gArgs.AddHiddenArgs(opts);
diff --git a/src/init.cpp b/src/init.cpp
index 2b538fb836..5b194add12 100644
--- a/src/init.cpp
+++ b/src/init.cpp
@@ -502,8 +502,6 @@ void SetupServerArgs()
     gArgs.AddArg("-mocktime=<n>", "Replace actual time with <n> seconds since epoch (default: 0)", true, OptionsCategory::DEBUG_TEST);
     gArgs.AddArg("-maxsigcachesize=<n>", strprintf("Limit sum of signature cache and script execution cache sizes to <n> MiB (default: %u)", DEFAULT_MAX_SIG_CACHE_SIZE), true, OptionsCategory::DEBUG_TEST);
     gArgs.AddArg("-maxtipage=<n>", strprintf("Maximum tip age in seconds to consider node in initial block download (default: %u)", DEFAULT_MAX_TIP_AGE), true, OptionsCategory::DEBUG_TEST);
-    gArgs.AddArg("-maxtxfee=<amt>", strprintf("Maximum total fees (in %s) to use in a single wallet transaction; setting this too low may abort large transactions (default: %s)", // TODO move setting to wallet
-        CURRENCY_UNIT, FormatMoney(DEFAULT_TRANSACTION_MAXFEE)), false, OptionsCategory::DEBUG_TEST);
     gArgs.AddArg("-printpriority", strprintf("Log transaction fee per kB when mining blocks (default: %u)", DEFAULT_PRINTPRIORITY), true, OptionsCategory::DEBUG_TEST);
     gArgs.AddArg("-printtoconsole", "Send trace/debug info to console (default: 1 when no -daemon. To disable logging to file, set -nodebuglogfile)", false, OptionsCategory::DEBUG_TEST);
     gArgs.AddArg("-shrinkdebugfile", "Shrink debug.log file on client startup (default: 1 when no -debug)", false, OptionsCategory::DEBUG_TEST);
@@ -1123,22 +1121,6 @@ bool AppInitParameterInteraction()
         dustRelayFee = CFeeRate(n);
     }
 
-    // This is required by both the wallet and node
-    if (gArgs.IsArgSet("-maxtxfee"))
-    {
-        CAmount nMaxFee = 0;
-        if (!ParseMoney(gArgs.GetArg("-maxtxfee", ""), nMaxFee))
-            return InitError(AmountErrMsg("maxtxfee", gArgs.GetArg("-maxtxfee", "")));
-        if (nMaxFee > HIGH_MAX_TX_FEE)
-            InitWarning(_("-maxtxfee is set very high! Fees this large could be paid on a single transaction."));
-        maxTxFee = nMaxFee;
-        if (CFeeRate(maxTxFee, 1000) < ::minRelayTxFee)
-        {
-            return InitError(strprintf(_("Invalid amount for -maxtxfee=<amount>: '%s' (must be at least the minrelay fee of %s to prevent stuck transactions)"),
-                                       gArgs.GetArg("-maxtxfee", ""), ::minRelayTxFee.ToString()));
-        }
-    }
-
     fRequireStandard = !gArgs.GetBoolArg("-acceptnonstdtxn", !chainparams.RequireStandard());
     if (chainparams.RequireStandard() && !fRequireStandard)
         return InitError(strprintf("acceptnonstdtxn is not currently supported for %s chain", chainparams.NetworkIDString()));
diff --git a/src/interfaces/chain.cpp b/src/interfaces/chain.cpp
index b61a51b235..16e0d1d6c0 100644
--- a/src/interfaces/chain.cpp
+++ b/src/interfaces/chain.cpp
@@ -339,7 +339,6 @@ public:
     CFeeRate relayMinFee() override { return ::minRelayTxFee; }
     CFeeRate relayIncrementalFee() override { return ::incrementalRelayFee; }
     CFeeRate relayDustFee() override { return ::dustRelayFee; }
-    CAmount maxTxFee() override { return ::maxTxFee; }
     bool getPruneMode() override { return ::fPruneMode; }
     bool p2pEnabled() override { return g_connman != nullptr; }
     bool isReadyToBroadcast() override { return !::fImporting && !::fReindex && !IsInitialBlockDownload(); }
diff --git a/src/interfaces/chain.h b/src/interfaces/chain.h
index 17d7b6d8f1..d62ee683fa 100644
--- a/src/interfaces/chain.h
+++ b/src/interfaces/chain.h
@@ -216,12 +216,6 @@ public:
     //! Relay dust fee setting (-dustrelayfee), reflecting lowest rate it's economical to spend.
     virtual CFeeRate relayDustFee() = 0;
 
-    //! Node max tx fee setting (-maxtxfee).
-    //! This could be replaced by a per-wallet max fee, as proposed at
-    //! https://github.com/bitcoin/bitcoin/issues/15355
-    //! But for the time being, wallets call this to access the node setting.
-    virtual CAmount maxTxFee() = 0;
-
     //! Check if pruning is enabled.
     virtual bool getPruneMode() = 0;
 
diff --git a/src/interfaces/node.cpp b/src/interfaces/node.cpp
index 73a5074133..f3ee8fe364 100644
--- a/src/interfaces/node.cpp
+++ b/src/interfaces/node.cpp
@@ -207,7 +207,6 @@ public:
         }
     }
     bool getNetworkActive() override { return g_connman && g_connman->GetNetworkActive(); }
-    CAmount getMaxTxFee() override { return ::maxTxFee; }
     CFeeRate estimateSmartFee(int num_blocks, bool conservative, int* returned_target = nullptr) override
     {
         FeeCalculation fee_calc;
diff --git a/src/interfaces/node.h b/src/interfaces/node.h
index 76b93af234..1ccd2a31b7 100644
--- a/src/interfaces/node.h
+++ b/src/interfaces/node.h
@@ -159,9 +159,6 @@ public:
     //! Get network active.
     virtual bool getNetworkActive() = 0;
 
-    //! Get max tx fee.
-    virtual CAmount getMaxTxFee() = 0;
-
     //! Estimate smart fee.
     virtual CFeeRate estimateSmartFee(int num_blocks, bool conservative, int* returned_target = nullptr) = 0;
 
diff --git a/src/interfaces/wallet.cpp b/src/interfaces/wallet.cpp
index f98a49f9b1..e5aee2d806 100644
--- a/src/interfaces/wallet.cpp
+++ b/src/interfaces/wallet.cpp
@@ -464,6 +464,7 @@ public:
     bool IsWalletFlagSet(uint64_t flag) override { return m_wallet->IsWalletFlagSet(flag); }
     OutputType getDefaultAddressType() override { return m_wallet->m_default_address_type; }
     OutputType getDefaultChangeType() override { return m_wallet->m_default_change_type; }
+    CAmount getDefaultMaxTxFee() override { return m_wallet->m_default_max_tx_fee; }
     void remove() override
     {
         RemoveWallet(m_wallet);
diff --git a/src/interfaces/wallet.h b/src/interfaces/wallet.h
index cabc455b1f..7096f54047 100644
--- a/src/interfaces/wallet.h
+++ b/src/interfaces/wallet.h
@@ -247,6 +247,9 @@ public:
     // Get default change type.
     virtual OutputType getDefaultChangeType() = 0;
 
+    //! Get max tx fee.
+    virtual CAmount getDefaultMaxTxFee() = 0;
+
     // Remove wallet.
     virtual void remove() = 0;
 
diff --git a/src/qt/sendcoinsdialog.cpp b/src/qt/sendcoinsdialog.cpp
index 6e00ab755c..8a0b265834 100644
--- a/src/qt/sendcoinsdialog.cpp
+++ b/src/qt/sendcoinsdialog.cpp
@@ -578,7 +578,7 @@ void SendCoinsDialog::processSendCoinsReturn(const WalletModel::SendCoinsReturn
         msgParams.second = CClientUIInterface::MSG_ERROR;
         break;
     case WalletModel::AbsurdFee:
-        msgParams.first = tr("A fee higher than %1 is considered an absurdly high fee.").arg(BitcoinUnits::formatWithUnit(model->getOptionsModel()->getDisplayUnit(), model->node().getMaxTxFee()));
+        msgParams.first = tr("A fee higher than %1 is considered an absurdly high fee.").arg(BitcoinUnits::formatWithUnit(model->getOptionsModel()->getDisplayUnit(), model->wallet().getDefaultMaxTxFee()));
         break;
     case WalletModel::PaymentRequestExpired:
         msgParams.first = tr("Payment request expired.");
diff --git a/src/qt/walletmodel.cpp b/src/qt/walletmodel.cpp
index f4f3be8f43..fd392b7cf7 100644
--- a/src/qt/walletmodel.cpp
+++ b/src/qt/walletmodel.cpp
@@ -222,9 +222,9 @@ WalletModel::SendCoinsReturn WalletModel::prepareTransaction(WalletModelTransact
         }
 
         // reject absurdly high fee. (This can never happen because the
-        // wallet caps the fee at maxTxFee. This merely serves as a
+        // wallet caps the fee at m_default_max_tx_fee. This merely serves as a
         // belt-and-suspenders check)
-        if (nFeeRequired > m_node.getMaxTxFee())
+        if (nFeeRequired > m_wallet->getDefaultMaxTxFee())
             return AbsurdFee;
     }
 
diff --git a/src/validation.cpp b/src/validation.cpp
index be6257ea28..b8f3ee464e 100644
--- a/src/validation.cpp
+++ b/src/validation.cpp
@@ -252,7 +252,6 @@ uint256 hashAssumeValid;
 arith_uint256 nMinimumChainWork;
 
 CFeeRate minRelayTxFee = CFeeRate(DEFAULT_MIN_RELAY_TX_FEE);
-CAmount maxTxFee = DEFAULT_TRANSACTION_MAXFEE;
 
 CBlockPolicyEstimator feeEstimator;
 CTxMemPool mempool(&feeEstimator);
diff --git a/src/validation.h b/src/validation.h
index 9f00cab49e..fecff5bb80 100644
--- a/src/validation.h
+++ b/src/validation.h
@@ -53,12 +53,6 @@ static const bool DEFAULT_WHITELISTRELAY = true;
 static const bool DEFAULT_WHITELISTFORCERELAY = false;
 /** Default for -minrelaytxfee, minimum relay fee for transactions */
 static const unsigned int DEFAULT_MIN_RELAY_TX_FEE = 1000;
-//! -maxtxfee default
-static const CAmount DEFAULT_TRANSACTION_MAXFEE = COIN / 10;
-//! Discourage users to set fees higher than this amount (in satoshis) per kB
-static const CAmount HIGH_TX_FEE_PER_KB = COIN / 100;
-//! -maxtxfee will warn if called with a higher fee than this amount (in satoshis)
-static const CAmount HIGH_MAX_TX_FEE = 100 * HIGH_TX_FEE_PER_KB;
 /** Default for -limitancestorcount, max number of in-mempool ancestors */
 static const unsigned int DEFAULT_ANCESTOR_LIMIT = 25;
 /** Default for -limitancestorsize, maximum kilobytes of tx + all in-mempool ancestors */
@@ -162,8 +156,6 @@ extern bool fCheckpointsEnabled;
 extern size_t nCoinCacheUsage;
 /** A fee rate smaller than this is considered zero fee (for relaying, mining and transaction creation) */
 extern CFeeRate minRelayTxFee;
-/** Absolute maximum transaction fee (in satoshis) used by wallet and mempool (rejects high fee in sendrawtransaction) */
-extern CAmount maxTxFee;
 /** If the tip is older than this (in seconds), the node is considered to be in initial block download. */
 extern int64_t nMaxTipAge;
 extern bool fEnableReplacement;
diff --git a/src/wallet/feebumper.cpp b/src/wallet/feebumper.cpp
index b547ea21d9..7ffea3867d 100644
--- a/src/wallet/feebumper.cpp
+++ b/src/wallet/feebumper.cpp
@@ -162,9 +162,9 @@ Result CreateTransaction(const CWallet* wallet, const uint256& txid, const CCoin
     }
 
     // Check that in all cases the new fee doesn't violate maxTxFee
-     const CAmount max_tx_fee = wallet->chain().maxTxFee();
+     const CAmount max_tx_fee = wallet->m_default_max_tx_fee;
      if (new_fee > max_tx_fee) {
-         errors.push_back(strprintf("Specified or calculated fee %s is too high (cannot be higher than maxTxFee %s)",
+         errors.push_back(strprintf("Specified or calculated fee %s is too high (cannot be higher than -maxtxfee %s)",
                                FormatMoney(new_fee), FormatMoney(max_tx_fee)));
          return Result::WALLET_ERROR;
      }
diff --git a/src/wallet/fees.cpp b/src/wallet/fees.cpp
index 560c86a70a..d9ae18ed60 100644
--- a/src/wallet/fees.cpp
+++ b/src/wallet/fees.cpp
@@ -22,7 +22,7 @@ CAmount GetMinimumFee(const CWallet& wallet, unsigned int nTxBytes, const CCoinC
 {
     CAmount fee_needed = GetMinimumFeeRate(wallet, coin_control, feeCalc).GetFee(nTxBytes);
     // Always obey the maximum
-    const CAmount max_tx_fee = wallet.chain().maxTxFee();
+    const CAmount max_tx_fee = wallet.m_default_max_tx_fee;
     if (fee_needed > max_tx_fee) {
         fee_needed = max_tx_fee;
         if (feeCalc) feeCalc->reason = FeeReason::MAXTXFEE;
diff --git a/src/wallet/init.cpp b/src/wallet/init.cpp
index e7eea94e06..47ef01bfd1 100644
--- a/src/wallet/init.cpp
+++ b/src/wallet/init.cpp
@@ -48,6 +48,8 @@ void WalletInit::AddWalletOptions() const
     gArgs.AddArg("-fallbackfee=<amt>", strprintf("A fee rate (in %s/kB) that will be used when fee estimation has insufficient data (default: %s)",
                                                                CURRENCY_UNIT, FormatMoney(DEFAULT_FALLBACK_FEE)), false, OptionsCategory::WALLET);
     gArgs.AddArg("-keypool=<n>", strprintf("Set key pool size to <n> (default: %u)", DEFAULT_KEYPOOL_SIZE), false, OptionsCategory::WALLET);
+    gArgs.AddArg("-maxtxfee=<amt>", strprintf("Maximum total fees (in %s) to use in a single wallet transaction; setting this too low may abort large transactions (default: %s)",
+        CURRENCY_UNIT, FormatMoney(DEFAULT_TRANSACTION_MAXFEE)), false, OptionsCategory::DEBUG_TEST);
     gArgs.AddArg("-mintxfee=<amt>", strprintf("Fees (in %s/kB) smaller than this are considered zero fee for transaction creation (default: %s)",
                                                             CURRENCY_UNIT, FormatMoney(DEFAULT_TRANSACTION_MINFEE)), false, OptionsCategory::WALLET);
     gArgs.AddArg("-paytxfee=<amt>", strprintf("Fee (in %s/kB) to add to transactions you send (default: %s)",
@@ -124,10 +126,6 @@ bool WalletInit::ParameterInteraction() const
     if (gArgs.GetArg("-prune", 0) && gArgs.GetBoolArg("-rescan", false))
         return InitError(_("Rescans are not possible in pruned mode. You will need to use -reindex which will download the whole blockchain again."));
 
-    if (::minRelayTxFee.GetFeePerK() > HIGH_TX_FEE_PER_KB)
-        InitWarning(AmountHighWarn("-minrelaytxfee") + " " +
-                    _("The wallet will avoid paying less than the minimum relay fee."));
-
     return true;
 }
 
diff --git a/src/wallet/wallet.cpp b/src/wallet/wallet.cpp
index 9ee6329f8c..8a1cb83e74 100644
--- a/src/wallet/wallet.cpp
+++ b/src/wallet/wallet.cpp
@@ -4204,6 +4204,29 @@ std::shared_ptr<CWallet> CWallet::CreateWalletFromFile(interfaces::Chain& chain,
             return nullptr;
         }
     }
+
+    if (gArgs.IsArgSet("-maxtxfee"))
+    {
+        CAmount nMaxFee = 0;
+        if (!ParseMoney(gArgs.GetArg("-maxtxfee", ""), nMaxFee)) {
+            chain.initError(AmountErrMsg("maxtxfee", gArgs.GetArg("-maxtxfee", "")));
+            return nullptr;
+        }
+        if (nMaxFee > HIGH_MAX_TX_FEE) {
+            chain.initWarning(_("-maxtxfee is set very high! Fees this large could be paid on a single transaction."));
+        }
+        if (CFeeRate(nMaxFee, 1000) < chain.relayMinFee()) {
+            chain.initError(strprintf(_("Invalid amount for -maxtxfee=<amount>: '%s' (must be at least the minrelay fee of %s to prevent stuck transactions)"),
+                                       gArgs.GetArg("-maxtxfee", ""), chain.relayMinFee().ToString()));
+            return nullptr;
+        }
+        walletInstance->m_default_max_tx_fee = nMaxFee;
+    }
+
+    if (chain.relayMinFee().GetFeePerK() > HIGH_TX_FEE_PER_KB)
+        chain.initWarning(AmountHighWarn("-minrelaytxfee") + " " +
+                    _("The wallet will avoid paying less than the minimum relay fee."));
+
     walletInstance->m_confirm_target = gArgs.GetArg("-txconfirmtarget", DEFAULT_TX_CONFIRM_TARGET);
     walletInstance->m_spend_zero_conf_change = gArgs.GetBoolArg("-spendzeroconfchange", DEFAULT_SPEND_ZEROCONF_CHANGE);
     walletInstance->m_signal_rbf = gArgs.GetBoolArg("-walletrbf", DEFAULT_WALLET_RBF);
@@ -4394,7 +4417,7 @@ bool CWalletTx::AcceptToMemoryPool(interfaces::Chain::Lock& locked_chain, CValid
     // user could call sendmoney in a loop and hit spurious out of funds errors
     // because we think that this newly generated transaction's change is
     // unavailable as we're not yet aware that it is in the mempool.
-    bool ret = locked_chain.submitToMemoryPool(tx, pwallet->chain().maxTxFee(), state);
+    bool ret = locked_chain.submitToMemoryPool(tx, pwallet->m_default_max_tx_fee, state);
     fInMempool |= ret;
     return ret;
 }
diff --git a/src/wallet/wallet.h b/src/wallet/wallet.h
index 4cc6973802..008765bccc 100644
--- a/src/wallet/wallet.h
+++ b/src/wallet/wallet.h
@@ -73,6 +73,12 @@ static const unsigned int DEFAULT_TX_CONFIRM_TARGET = 6;
 static const bool DEFAULT_WALLET_RBF = false;
 static const bool DEFAULT_WALLETBROADCAST = true;
 static const bool DEFAULT_DISABLE_WALLET = false;
+//! -maxtxfee default
+constexpr CAmount DEFAULT_TRANSACTION_MAXFEE{COIN / 10};
+//! Discourage users to set fees higher than this amount (in satoshis) per kB
+constexpr CAmount HIGH_TX_FEE_PER_KB{COIN / 100};
+//! -maxtxfee will warn if called with a higher fee than this amount (in satoshis)
+constexpr CAmount HIGH_MAX_TX_FEE{100 * HIGH_TX_FEE_PER_KB};
 
 //! Pre-calculated constants for input size estimation in *virtual size*
 static constexpr size_t DUMMY_NESTED_P2WPKH_INPUT_SIZE = 91;
@@ -983,6 +989,8 @@ public:
     CFeeRate m_discard_rate{DEFAULT_DISCARD_FEE};
     OutputType m_default_address_type{DEFAULT_ADDRESS_TYPE};
     OutputType m_default_change_type{DEFAULT_CHANGE_TYPE};
+    /** Absolute maximum transaction fee (in satoshis) used by default for the wallet */
+    CAmount m_default_max_tx_fee{DEFAULT_TRANSACTION_MAXFEE};
 
     bool NewKeyPool();
     size_t KeypoolCountExternalKeys() EXCLUSIVE_LOCKS_REQUIRED(cs_wallet);