Merge bitcoin/bitcoin#28950: RPC: Add maxfeerate and maxburnamount args to submitpackage

38f70ba6ac86fb96c60571d2e1f316315c1c73cc RPC: Add maxfeerate and maxburnamount args to submitpackage (Greg Sanders)

Pull request description:

  Resolves https://github.com/bitcoin/bitcoin/issues/28949

  I couldn't manage to do it very cleanly outside of (sub)package evaluation itself, since it would change the current interface very heavily. Instead I threaded through the max fee argument and used that directly via ATMPArgs. From that perspective, this is somewhat a reversion from https://github.com/bitcoin/bitcoin/pull/19339. In a post-cluster mempool world, these checks could be consolidated to right after the given (ancestor) package is linearized/chunked, by just checking the feerate of the top chunk and rejecting the submission entirely if the top chunk is too high.

  The implication here is that subpackages can be submitted to the mempool prior to hitting this new fee-based error condition.

ACKs for top commit:
  ismaelsadeeq:
    Re-ACK https://github.com/bitcoin/bitcoin/commit/38f70ba6ac86fb96c60571d2e1f316315c1c73cc 👍🏾
  glozow:
    ACK 38f70ba6ac with some non-blocking nits
  murchandamus:
    LGTM, code review ACK 38f70ba6ac86fb96c60571d2e1f316315c1c73cc

Tree-SHA512: 38212aa9de25730944cee58b0806a3d37097e42719af8dd7de91ce86bb5d9770b6f7c37354bf418bd8ba571c52947da1dcdbb968bf429dd1dbdf8715315af18f

2 files changed, 32 insertions, 3 deletions

diff --git a/src/rpc/client.cpp b/src/rpc/client.cpp
index 5825efdf82..eb05f33b42 100644
--- a/src/rpc/client.cpp
+++ b/src/rpc/client.cpp
@@ -128,6 +128,8 @@ static const CRPCConvertParam vRPCConvertParams[] =
     { "testmempoolaccept", 0, "rawtxs" },
     { "testmempoolaccept", 1, "maxfeerate" },
     { "submitpackage", 0, "package" },
+    { "submitpackage", 1, "maxfeerate" },
+    { "submitpackage", 2, "maxburnamount" },
     { "combinerawtransaction", 0, "txs" },
     { "fundrawtransaction", 1, "options" },
     { "fundrawtransaction", 1, "add_inputs"},
diff --git a/src/rpc/mempool.cpp b/src/rpc/mempool.cpp
index 25bfec2d45..8539506f2f 100644
--- a/src/rpc/mempool.cpp
+++ b/src/rpc/mempool.cpp
@@ -28,6 +28,7 @@
 
 using kernel::DumpMempool;
 
+using node::DEFAULT_MAX_BURN_AMOUNT;
 using node::DEFAULT_MAX_RAW_TX_FEE_RATE;
 using node::MempoolPath;
 using node::NodeContext;
@@ -46,7 +47,7 @@ static RPCHelpMan sendrawtransaction()
             {"maxfeerate", RPCArg::Type::AMOUNT, RPCArg::Default{FormatMoney(DEFAULT_MAX_RAW_TX_FEE_RATE.GetFeePerK())},
              "Reject transactions whose fee rate is higher than the specified value, expressed in " + CURRENCY_UNIT +
                  "/kvB.\nFee rates larger than 1BTC/kvB are rejected.\nSet to 0 to accept any fee rate."},
-            {"maxburnamount", RPCArg::Type::AMOUNT, RPCArg::Default{FormatMoney(0)},
+            {"maxburnamount", RPCArg::Type::AMOUNT, RPCArg::Default{FormatMoney(DEFAULT_MAX_BURN_AMOUNT)},
              "Reject transactions with provably unspendable outputs (e.g. 'datacarrier' outputs that use the OP_RETURN opcode) greater than the specified value, expressed in " + CURRENCY_UNIT + ".\n"
              "If burning funds through unspendable outputs is desired, increase this value.\n"
              "This check is based on heuristics and does not guarantee spendability of outputs.\n"},
@@ -180,7 +181,7 @@ static RPCHelpMan testmempoolaccept()
             Chainstate& chainstate = chainman.ActiveChainstate();
             const PackageMempoolAcceptResult package_result = [&] {
                 LOCK(::cs_main);
-                if (txns.size() > 1) return ProcessNewPackage(chainstate, mempool, txns, /*test_accept=*/true);
+                if (txns.size() > 1) return ProcessNewPackage(chainstate, mempool, txns, /*test_accept=*/true, /*max_sane_feerate=*/{});
                 return PackageMempoolAcceptResult(txns[0]->GetWitnessHash(),
                                                   chainman.ProcessTransaction(txns[0], /*test_accept=*/true));
             }();
@@ -823,6 +824,14 @@ static RPCHelpMan submitpackage()
                     {"rawtx", RPCArg::Type::STR_HEX, RPCArg::Optional::OMITTED, ""},
                 },
             },
+            {"maxfeerate", RPCArg::Type::AMOUNT, RPCArg::Default{FormatMoney(DEFAULT_MAX_RAW_TX_FEE_RATE.GetFeePerK())},
+             "Reject transactions whose fee rate is higher than the specified value, expressed in " + CURRENCY_UNIT +
+                 "/kvB.\nFee rates larger than 1BTC/kvB are rejected.\nSet to 0 to accept any fee rate."},
+            {"maxburnamount", RPCArg::Type::AMOUNT, RPCArg::Default{FormatMoney(DEFAULT_MAX_BURN_AMOUNT)},
+             "Reject transactions with provably unspendable outputs (e.g. 'datacarrier' outputs that use the OP_RETURN opcode) greater than the specified value, expressed in " + CURRENCY_UNIT + ".\n"
+             "If burning funds through unspendable outputs is desired, increase this value.\n"
+             "This check is based on heuristics and does not guarantee spendability of outputs.\n"
+            },
         },
         RPCResult{
             RPCResult::Type::OBJ, "", "",
@@ -862,6 +871,17 @@ static RPCHelpMan submitpackage()
                                    "Array must contain between 1 and " + ToString(MAX_PACKAGE_COUNT) + " transactions.");
             }
 
+            // Fee check needs to be run with chainstate and package context
+            const CFeeRate max_raw_tx_fee_rate = ParseFeeRate(self.Arg<UniValue>(1));
+            std::optional<CFeeRate> max_sane_feerate{max_raw_tx_fee_rate};
+            // 0-value is special; it's mapped to no sanity check
+            if (max_raw_tx_fee_rate == CFeeRate(0)) {
+                max_sane_feerate = std::nullopt;
+            }
+
+            // Burn sanity check is run with no context
+            const CAmount max_burn_amount = request.params[2].isNull() ? 0 : AmountFromValue(request.params[2]);
+
             std::vector<CTransactionRef> txns;
             txns.reserve(raw_transactions.size());
             for (const auto& rawtx : raw_transactions.getValues()) {
@@ -870,6 +890,13 @@ static RPCHelpMan submitpackage()
                     throw JSONRPCError(RPC_DESERIALIZATION_ERROR,
                                        "TX decode failed: " + rawtx.get_str() + " Make sure the tx has at least one input.");
                 }
+
+                for (const auto& out : mtx.vout) {
+                    if((out.scriptPubKey.IsUnspendable() || !out.scriptPubKey.HasValidOps()) && out.nValue > max_burn_amount) {
+                        throw JSONRPCTransactionError(TransactionError::MAX_BURN_EXCEEDED);
+                    }
+                }
+
                 txns.emplace_back(MakeTransactionRef(std::move(mtx)));
             }
             if (!IsChildWithParentsTree(txns)) {
@@ -879,7 +906,7 @@ static RPCHelpMan submitpackage()
             NodeContext& node = EnsureAnyNodeContext(request.context);
             CTxMemPool& mempool = EnsureMemPool(node);
             Chainstate& chainstate = EnsureChainman(node).ActiveChainstate();
-            const auto package_result = WITH_LOCK(::cs_main, return ProcessNewPackage(chainstate, mempool, txns, /*test_accept=*/ false));
+            const auto package_result = WITH_LOCK(::cs_main, return ProcessNewPackage(chainstate, mempool, txns, /*test_accept=*/ false, max_sane_feerate));
 
             std::string package_msg = "success";