Merge #11742: rpc: Add testmempoolaccept

b55555d rpc: Add testmempoolaccept (MarcoFalke)

Pull request description:

  To check if a single raw transaction makes it into the current transaction pool, one had to call `sendrawtransaction`. However, on success, this adds the transaction to the mempool with no easy way to undo.

  The call `testmempoolaccept` is introduced to provide a way to solely check the result without changing the mempool state.

Tree-SHA512: 5afd9311190135cee8fc1f229c7d39bf893f1028f29e28d34f70df820198ff97b4bf86b41cbbd6e6c36a5c30073cefa92d541c74a4939c7a2a6fa283dfd41b63

10 files changed, 399 insertions, 14 deletions

diff --git a/src/rpc/client.cpp b/src/rpc/client.cpp
index e12685da65..01f932dbb4 100644
--- a/src/rpc/client.cpp
+++ b/src/rpc/client.cpp
@@ -103,6 +103,8 @@ static const CRPCConvertParam vRPCConvertParams[] =
     { "signrawtransactionwithkey", 2, "prevtxs" },
     { "signrawtransactionwithwallet", 1, "prevtxs" },
     { "sendrawtransaction", 1, "allowhighfees" },
+    { "testmempoolaccept", 0, "rawtxs" },
+    { "testmempoolaccept", 1, "allowhighfees" },
     { "combinerawtransaction", 0, "txs" },
     { "fundrawtransaction", 1, "options" },
     { "fundrawtransaction", 2, "iswitness" },
diff --git a/src/rpc/rawtransaction.cpp b/src/rpc/rawtransaction.cpp
index 77040f75fd..9d7aa58894 100644
--- a/src/rpc/rawtransaction.cpp
+++ b/src/rpc/rawtransaction.cpp
@@ -1134,6 +1134,87 @@ UniValue sendrawtransaction(const JSONRPCRequest& request)
     return hashTx.GetHex();
 }
 
+UniValue testmempoolaccept(const JSONRPCRequest& request)
+{
+    if (request.fHelp || request.params.size() < 1 || request.params.size() > 2) {
+        throw std::runtime_error(
+            // clang-format off
+            "testmempoolaccept [\"rawtxs\"] ( allowhighfees )\n"
+            "\nReturns if raw transaction (serialized, hex-encoded) would be accepted by mempool.\n"
+            "\nThis checks if the transaction violates the consensus or policy rules.\n"
+            "\nSee sendrawtransaction call.\n"
+            "\nArguments:\n"
+            "1. [\"rawtxs\"]       (array, required) An array of hex strings of raw transactions.\n"
+            "                                        Length must be one for now.\n"
+            "2. allowhighfees    (boolean, optional, default=false) Allow high fees\n"
+            "\nResult:\n"
+            "[                   (array) The result of the mempool acceptance test for each raw transaction in the input array.\n"
+            "                            Length is exactly one for now.\n"
+            " {\n"
+            "  \"txid\"           (string) The transaction hash in hex\n"
+            "  \"allowed\"        (boolean) If the mempool allows this tx to be inserted\n"
+            "  \"reject-reason\"  (string) Rejection string (only present when 'allowed' is false)\n"
+            " }\n"
+            "]\n"
+            "\nExamples:\n"
+            "\nCreate a transaction\n"
+            + HelpExampleCli("createrawtransaction", "\"[{\\\"txid\\\" : \\\"mytxid\\\",\\\"vout\\\":0}]\" \"{\\\"myaddress\\\":0.01}\"") +
+            "Sign the transaction, and get back the hex\n"
+            + HelpExampleCli("signrawtransaction", "\"myhex\"") +
+            "\nTest acceptance of the transaction (signed hex)\n"
+            + HelpExampleCli("testmempoolaccept", "\"signedhex\"") +
+            "\nAs a json rpc call\n"
+            + HelpExampleRpc("testmempoolaccept", "[\"signedhex\"]")
+            // clang-format on
+            );
+    }
+
+    ObserveSafeMode();
+
+    RPCTypeCheck(request.params, {UniValue::VARR, UniValue::VBOOL});
+    if (request.params[0].get_array().size() != 1) {
+        throw JSONRPCError(RPC_INVALID_PARAMETER, "Array must contain exactly one raw transaction for now");
+    }
+
+    CMutableTransaction mtx;
+    if (!DecodeHexTx(mtx, request.params[0].get_array()[0].get_str())) {
+        throw JSONRPCError(RPC_DESERIALIZATION_ERROR, "TX decode failed");
+    }
+    CTransactionRef tx(MakeTransactionRef(std::move(mtx)));
+    const uint256& tx_hash = tx->GetHash();
+
+    CAmount max_raw_tx_fee = ::maxTxFee;
+    if (!request.params[1].isNull() && request.params[1].get_bool()) {
+        max_raw_tx_fee = 0;
+    }
+
+    UniValue result(UniValue::VARR);
+    UniValue result_0(UniValue::VOBJ);
+    result_0.pushKV("txid", tx_hash.GetHex());
+
+    CValidationState state;
+    bool missing_inputs;
+    bool test_accept_res;
+    {
+        LOCK(cs_main);
+        test_accept_res = AcceptToMemoryPool(mempool, state, std::move(tx), &missing_inputs,
+            nullptr /* plTxnReplaced */, false /* bypass_limits */, max_raw_tx_fee, /* test_accpet */ true);
+    }
+    result_0.pushKV("allowed", test_accept_res);
+    if (!test_accept_res) {
+        if (state.IsInvalid()) {
+            result_0.pushKV("reject-reason", strprintf("%i: %s", state.GetRejectCode(), state.GetRejectReason()));
+        } else if (missing_inputs) {
+            result_0.pushKV("reject-reason", "missing-inputs");
+        } else {
+            result_0.pushKV("reject-reason", state.GetRejectReason());
+        }
+    }
+
+    result.push_back(std::move(result_0));
+    return result;
+}
+
 static const CRPCCommand commands[] =
 { //  category              name                            actor (function)            argNames
   //  --------------------- ------------------------        -----------------------     ----------
@@ -1145,6 +1226,7 @@ static const CRPCCommand commands[] =
     { "rawtransactions",    "combinerawtransaction",        &combinerawtransaction,     {"txs"} },
     { "rawtransactions",    "signrawtransaction",           &signrawtransaction,        {"hexstring","prevtxs","privkeys","sighashtype"} }, /* uses wallet if enabled */
     { "rawtransactions",    "signrawtransactionwithkey",    &signrawtransactionwithkey, {"hexstring","privkeys","prevtxs","sighashtype"} },
+    { "rawtransactions",    "testmempoolaccept",            &testmempoolaccept,         {"rawtxs","allowhighfees"} },
 
     { "blockchain",         "gettxoutproof",                &gettxoutproof,             {"txids", "blockhash"} },
     { "blockchain",         "verifytxoutproof",             &verifytxoutproof,          {"proof"} },
diff --git a/src/txmempool.cpp b/src/txmempool.cpp
index cc639288d3..d03429ca81 100644
--- a/src/txmempool.cpp
+++ b/src/txmempool.cpp
@@ -447,7 +447,7 @@ void CTxMemPool::removeUnchecked(txiter it, MemPoolRemovalReason reason)
 // Also assumes that if an entry is in setDescendants already, then all
 // in-mempool descendants of it are already in setDescendants as well, so that we
 // can save time by not iterating over those entries.
-void CTxMemPool::CalculateDescendants(txiter entryit, setEntries &setDescendants)
+void CTxMemPool::CalculateDescendants(txiter entryit, setEntries& setDescendants) const
 {
     setEntries stage;
     if (setDescendants.count(entryit) == 0) {
diff --git a/src/txmempool.h b/src/txmempool.h
index 699f6b554b..a1cde6f779 100644
--- a/src/txmempool.h
+++ b/src/txmempool.h
@@ -600,7 +600,7 @@ public:
     /** Populate setDescendants with all in-mempool descendants of hash.
      *  Assumes that setDescendants includes all in-mempool descendants of anything
      *  already in it.  */
-    void CalculateDescendants(txiter it, setEntries &setDescendants);
+    void CalculateDescendants(txiter it, setEntries& setDescendants) const;
 
     /** The minimum fee to get into the mempool, which may itself not be enough
       *  for larger-sized transactions.
diff --git a/src/validation.cpp b/src/validation.cpp
index 77764ff923..df8729e382 100644
--- a/src/validation.cpp
+++ b/src/validation.cpp
@@ -543,7 +543,7 @@ static bool CheckInputsFromMempoolAndCache(const CTransaction& tx, CValidationSt
 
 static bool AcceptToMemoryPoolWorker(const CChainParams& chainparams, CTxMemPool& pool, CValidationState& state, const CTransactionRef& ptx,
                               bool* pfMissingInputs, int64_t nAcceptTime, std::list<CTransactionRef>* plTxnReplaced,
-                              bool bypass_limits, const CAmount& nAbsurdFee, std::vector<COutPoint>& coins_to_uncache)
+                              bool bypass_limits, const CAmount& nAbsurdFee, std::vector<COutPoint>& coins_to_uncache, bool test_accept)
 {
     const CTransaction& tx = *ptx;
     const uint256 hash = tx.GetHash();
@@ -935,6 +935,11 @@ static bool AcceptToMemoryPoolWorker(const CChainParams& chainparams, CTxMemPool
             }
         }
 
+        if (test_accept) {
+            // Tx was accepted, but not added
+            return true;
+        }
+
         // Remove conflicting transactions from the mempool
         for (const CTxMemPool::txiter it : allConflicting)
         {
@@ -974,10 +979,10 @@ static bool AcceptToMemoryPoolWorker(const CChainParams& chainparams, CTxMemPool
 /** (try to) add transaction to memory pool with a specified acceptance time **/
 static bool AcceptToMemoryPoolWithTime(const CChainParams& chainparams, CTxMemPool& pool, CValidationState &state, const CTransactionRef &tx,
                         bool* pfMissingInputs, int64_t nAcceptTime, std::list<CTransactionRef>* plTxnReplaced,
-                        bool bypass_limits, const CAmount nAbsurdFee)
+                        bool bypass_limits, const CAmount nAbsurdFee, bool test_accept)
 {
     std::vector<COutPoint> coins_to_uncache;
-    bool res = AcceptToMemoryPoolWorker(chainparams, pool, state, tx, pfMissingInputs, nAcceptTime, plTxnReplaced, bypass_limits, nAbsurdFee, coins_to_uncache);
+    bool res = AcceptToMemoryPoolWorker(chainparams, pool, state, tx, pfMissingInputs, nAcceptTime, plTxnReplaced, bypass_limits, nAbsurdFee, coins_to_uncache, test_accept);
     if (!res) {
         for (const COutPoint& hashTx : coins_to_uncache)
             pcoinsTip->Uncache(hashTx);
@@ -990,10 +995,10 @@ static bool AcceptToMemoryPoolWithTime(const CChainParams& chainparams, CTxMemPo
 
 bool AcceptToMemoryPool(CTxMemPool& pool, CValidationState &state, const CTransactionRef &tx,
                         bool* pfMissingInputs, std::list<CTransactionRef>* plTxnReplaced,
-                        bool bypass_limits, const CAmount nAbsurdFee)
+                        bool bypass_limits, const CAmount nAbsurdFee, bool test_accept)
 {
     const CChainParams& chainparams = Params();
-    return AcceptToMemoryPoolWithTime(chainparams, pool, state, tx, pfMissingInputs, GetTime(), plTxnReplaced, bypass_limits, nAbsurdFee);
+    return AcceptToMemoryPoolWithTime(chainparams, pool, state, tx, pfMissingInputs, GetTime(), plTxnReplaced, bypass_limits, nAbsurdFee, test_accept);
 }
 
 /**
@@ -4640,7 +4645,8 @@ bool LoadMempool(void)
             if (nTime + nExpiryTimeout > nNow) {
                 LOCK(cs_main);
                 AcceptToMemoryPoolWithTime(chainparams, mempool, state, tx, nullptr /* pfMissingInputs */, nTime,
-                                           nullptr /* plTxnReplaced */, false /* bypass_limits */, 0 /* nAbsurdFee */);
+                                           nullptr /* plTxnReplaced */, false /* bypass_limits */, 0 /* nAbsurdFee */,
+                                           false /* test_accept */);
                 if (state.IsValid()) {
                     ++count;
                 } else {
diff --git a/src/validation.h b/src/validation.h
index 4031989f00..95c31bf0fc 100644
--- a/src/validation.h
+++ b/src/validation.h
@@ -308,7 +308,7 @@ void PruneBlockFilesManual(int nManualPruneHeight);
  * plTxnReplaced will be appended to with all transactions replaced from mempool **/
 bool AcceptToMemoryPool(CTxMemPool& pool, CValidationState &state, const CTransactionRef &tx,
                         bool* pfMissingInputs, std::list<CTransactionRef>* plTxnReplaced,
-                        bool bypass_limits, const CAmount nAbsurdFee);
+                        bool bypass_limits, const CAmount nAbsurdFee, bool test_accept=false);
 
 /** Convert CValidationState to a human-readable message for logging */
 std::string FormatStateMessage(const CValidationState &state);
diff --git a/test/functional/mempool_accept.py b/test/functional/mempool_accept.py
new file mode 100755
index 0000000000..7cdb24c6a5
--- /dev/null
+++ b/test/functional/mempool_accept.py
@@ -0,0 +1,293 @@
+#!/usr/bin/env python3
+# Copyright (c) 2017 The Bitcoin Core developers
+# Distributed under the MIT software license, see the accompanying
+# file COPYING or http://www.opensource.org/licenses/mit-license.php.
+"""Test mempool acceptance of raw transactions."""
+
+from io import BytesIO
+from test_framework.test_framework import BitcoinTestFramework
+from test_framework.messages import (
+    BIP125_SEQUENCE_NUMBER,
+    COIN,
+    COutPoint,
+    CTransaction,
+    CTxOut,
+    MAX_BLOCK_BASE_SIZE,
+)
+from test_framework.script import (
+    hash160,
+    CScript,
+    OP_0,
+    OP_EQUAL,
+    OP_HASH160,
+    OP_RETURN,
+)
+from test_framework.util import (
+    assert_equal,
+    assert_raises_rpc_error,
+    bytes_to_hex_str,
+    hex_str_to_bytes,
+    wait_until,
+)
+
+
+class MempoolAcceptanceTest(BitcoinTestFramework):
+    def set_test_params(self):
+        self.num_nodes = 1
+        self.extra_args = [[
+            '-checkmempool',
+            '-txindex',
+            '-reindex',  # Need reindex for txindex
+            '-acceptnonstdtxn=0',  # Try to mimic main-net
+        ]] * self.num_nodes
+
+    def check_mempool_result(self, result_expected, *args, **kwargs):
+        """Wrapper to check result of testmempoolaccept on node_0's mempool"""
+        result_test = self.nodes[0].testmempoolaccept(*args, **kwargs)
+        assert_equal(result_expected, result_test)
+        assert_equal(self.nodes[0].getmempoolinfo()['size'], self.mempool_size)  # Must not change mempool state
+
+    def run_test(self):
+        node = self.nodes[0]
+
+        self.log.info('Start with empty mempool, and 200 blocks')
+        self.mempool_size = 0
+        wait_until(lambda: node.getblockcount() == 200)
+        assert_equal(node.getmempoolinfo()['size'], self.mempool_size)
+
+        self.log.info('Should not accept garbage to testmempoolaccept')
+        assert_raises_rpc_error(-3, 'Expected type array, got string', lambda: node.testmempoolaccept(rawtxs='ff00baar'))
+        assert_raises_rpc_error(-8, 'Array must contain exactly one raw transaction for now', lambda: node.testmempoolaccept(rawtxs=['ff00baar', 'ff22']))
+        assert_raises_rpc_error(-22, 'TX decode failed', lambda: node.testmempoolaccept(rawtxs=['ff00baar']))
+
+        self.log.info('A transaction already in the blockchain')
+        coin = node.listunspent()[0]  # Pick a random coin(base) to spend
+        raw_tx_in_block = node.signrawtransactionwithwallet(node.createrawtransaction(
+            inputs=[{'txid': coin['txid'], 'vout': coin['vout']}],
+            outputs=[{node.getnewaddress(): 0.3}, {node.getnewaddress(): 49}],
+        ))['hex']
+        txid_in_block = node.sendrawtransaction(hexstring=raw_tx_in_block, allowhighfees=True)
+        node.generate(1)
+        self.check_mempool_result(
+            result_expected=[{'txid': txid_in_block, 'allowed': False, 'reject-reason': '18: txn-already-known'}],
+            rawtxs=[raw_tx_in_block],
+        )
+
+        self.log.info('A transaction not in the mempool')
+        fee = 0.00000700
+        raw_tx_0 = node.signrawtransactionwithwallet(node.createrawtransaction(
+            inputs=[{"txid": txid_in_block, "vout": 0, "sequence": BIP125_SEQUENCE_NUMBER}],  # RBF is used later
+            outputs=[{node.getnewaddress(): 0.3 - fee}],
+        ))['hex']
+        tx = CTransaction()
+        tx.deserialize(BytesIO(hex_str_to_bytes(raw_tx_0)))
+        txid_0 = tx.rehash()
+        self.check_mempool_result(
+            result_expected=[{'txid': txid_0, 'allowed': True}],
+            rawtxs=[raw_tx_0],
+        )
+
+        self.log.info('A transaction in the mempool')
+        node.sendrawtransaction(hexstring=raw_tx_0)
+        self.mempool_size = 1
+        self.check_mempool_result(
+            result_expected=[{'txid': txid_0, 'allowed': False, 'reject-reason': '18: txn-already-in-mempool'}],
+            rawtxs=[raw_tx_0],
+        )
+
+        self.log.info('A transaction that replaces a mempool transaction')
+        tx.deserialize(BytesIO(hex_str_to_bytes(raw_tx_0)))
+        tx.vout[0].nValue -= int(fee * COIN)  # Double the fee
+        tx.vin[0].nSequence = BIP125_SEQUENCE_NUMBER + 1  # Now, opt out of RBF
+        raw_tx_0 = node.signrawtransactionwithwallet(bytes_to_hex_str(tx.serialize()))['hex']
+        tx.deserialize(BytesIO(hex_str_to_bytes(raw_tx_0)))
+        txid_0 = tx.rehash()
+        self.check_mempool_result(
+            result_expected=[{'txid': txid_0, 'allowed': True}],
+            rawtxs=[raw_tx_0],
+        )
+
+        self.log.info('A transaction that conflicts with an unconfirmed tx')
+        # Send the transaction that replaces the mempool transaction and opts out of replaceability
+        node.sendrawtransaction(hexstring=bytes_to_hex_str(tx.serialize()), allowhighfees=True)
+        # take original raw_tx_0
+        tx.deserialize(BytesIO(hex_str_to_bytes(raw_tx_0)))
+        tx.vout[0].nValue -= int(4 * fee * COIN)  # Set more fee
+        # skip re-signing the tx
+        self.check_mempool_result(
+            result_expected=[{'txid': tx.rehash(), 'allowed': False, 'reject-reason': '18: txn-mempool-conflict'}],
+            rawtxs=[bytes_to_hex_str(tx.serialize())],
+            allowhighfees=True,
+        )
+
+        self.log.info('A transaction with missing inputs, that never existed')
+        tx.deserialize(BytesIO(hex_str_to_bytes(raw_tx_0)))
+        tx.vin[0].prevout = COutPoint(hash=int('ff' * 32, 16), n=14)
+        # skip re-signing the tx
+        self.check_mempool_result(
+            result_expected=[{'txid': tx.rehash(), 'allowed': False, 'reject-reason': 'missing-inputs'}],
+            rawtxs=[bytes_to_hex_str(tx.serialize())],
+        )
+
+        self.log.info('A transaction with missing inputs, that existed once in the past')
+        tx.deserialize(BytesIO(hex_str_to_bytes(raw_tx_0)))
+        tx.vin[0].prevout.n = 1  # Set vout to 1, to spend the other outpoint (49 coins) of the in-chain-tx we want to double spend
+        raw_tx_1 = node.signrawtransactionwithwallet(bytes_to_hex_str(tx.serialize()))['hex']
+        txid_1 = node.sendrawtransaction(hexstring=raw_tx_1, allowhighfees=True)
+        # Now spend both to "clearly hide" the outputs, ie. remove the coins from the utxo set by spending them
+        raw_tx_spend_both = node.signrawtransactionwithwallet(node.createrawtransaction(
+            inputs=[
+                {'txid': txid_0, 'vout': 0},
+                {'txid': txid_1, 'vout': 0},
+            ],
+            outputs=[{node.getnewaddress(): 0.1}]
+        ))['hex']
+        txid_spend_both = node.sendrawtransaction(hexstring=raw_tx_spend_both, allowhighfees=True)
+        node.generate(1)
+        self.mempool_size = 0
+        # Now see if we can add the coins back to the utxo set by sending the exact txs again
+        self.check_mempool_result(
+            result_expected=[{'txid': txid_0, 'allowed': False, 'reject-reason': 'missing-inputs'}],
+            rawtxs=[raw_tx_0],
+        )
+        self.check_mempool_result(
+            result_expected=[{'txid': txid_1, 'allowed': False, 'reject-reason': 'missing-inputs'}],
+            rawtxs=[raw_tx_1],
+        )
+
+        self.log.info('Create a signed "reference" tx for later use')
+        raw_tx_reference = node.signrawtransactionwithwallet(node.createrawtransaction(
+            inputs=[{'txid': txid_spend_both, 'vout': 0}],
+            outputs=[{node.getnewaddress(): 0.05}],
+        ))['hex']
+        tx.deserialize(BytesIO(hex_str_to_bytes(raw_tx_reference)))
+        # Reference tx should be valid on itself
+        self.check_mempool_result(
+            result_expected=[{'txid': tx.rehash(), 'allowed': True}],
+            rawtxs=[bytes_to_hex_str(tx.serialize())],
+        )
+
+        self.log.info('A transaction with no outputs')
+        tx.deserialize(BytesIO(hex_str_to_bytes(raw_tx_reference)))
+        tx.vout = []
+        # Skip re-signing the transaction for context independent checks from now on
+        # tx.deserialize(BytesIO(hex_str_to_bytes(node.signrawtransactionwithwallet(bytes_to_hex_str(tx.serialize()))['hex'])))
+        self.check_mempool_result(
+            result_expected=[{'txid': tx.rehash(), 'allowed': False, 'reject-reason': '16: bad-txns-vout-empty'}],
+            rawtxs=[bytes_to_hex_str(tx.serialize())],
+        )
+
+        self.log.info('A really large transaction')
+        tx.deserialize(BytesIO(hex_str_to_bytes(raw_tx_reference)))
+        tx.vin = [tx.vin[0]] * (MAX_BLOCK_BASE_SIZE // len(tx.vin[0].serialize()))
+        self.check_mempool_result(
+            result_expected=[{'txid': tx.rehash(), 'allowed': False, 'reject-reason': '16: bad-txns-oversize'}],
+            rawtxs=[bytes_to_hex_str(tx.serialize())],
+        )
+
+        self.log.info('A transaction with negative output value')
+        tx.deserialize(BytesIO(hex_str_to_bytes(raw_tx_reference)))
+        tx.vout[0].nValue *= -1
+        self.check_mempool_result(
+            result_expected=[{'txid': tx.rehash(), 'allowed': False, 'reject-reason': '16: bad-txns-vout-negative'}],
+            rawtxs=[bytes_to_hex_str(tx.serialize())],
+        )
+
+        self.log.info('A transaction with too large output value')
+        tx.deserialize(BytesIO(hex_str_to_bytes(raw_tx_reference)))
+        tx.vout[0].nValue = 21000000 * COIN + 1
+        self.check_mempool_result(
+            result_expected=[{'txid': tx.rehash(), 'allowed': False, 'reject-reason': '16: bad-txns-vout-toolarge'}],
+            rawtxs=[bytes_to_hex_str(tx.serialize())],
+        )
+
+        self.log.info('A transaction with too large sum of output values')
+        tx.deserialize(BytesIO(hex_str_to_bytes(raw_tx_reference)))
+        tx.vout = [tx.vout[0]] * 2
+        tx.vout[0].nValue = 21000000 * COIN
+        self.check_mempool_result(
+            result_expected=[{'txid': tx.rehash(), 'allowed': False, 'reject-reason': '16: bad-txns-txouttotal-toolarge'}],
+            rawtxs=[bytes_to_hex_str(tx.serialize())],
+        )
+
+        self.log.info('A transaction with duplicate inputs')
+        tx.deserialize(BytesIO(hex_str_to_bytes(raw_tx_reference)))
+        tx.vin = [tx.vin[0]] * 2
+        self.check_mempool_result(
+            result_expected=[{'txid': tx.rehash(), 'allowed': False, 'reject-reason': '16: bad-txns-inputs-duplicate'}],
+            rawtxs=[bytes_to_hex_str(tx.serialize())],
+        )
+
+        self.log.info('A coinbase transaction')
+        # Pick the input of the first tx we signed, so it has to be a coinbase tx
+        raw_tx_coinbase_spent = node.getrawtransaction(txid=node.decoderawtransaction(hexstring=raw_tx_in_block)['vin'][0]['txid'])
+        tx.deserialize(BytesIO(hex_str_to_bytes(raw_tx_coinbase_spent)))
+        self.check_mempool_result(
+            result_expected=[{'txid': tx.rehash(), 'allowed': False, 'reject-reason': '16: coinbase'}],
+            rawtxs=[bytes_to_hex_str(tx.serialize())],
+        )
+
+        self.log.info('Some nonstandard transactions')
+        tx.deserialize(BytesIO(hex_str_to_bytes(raw_tx_reference)))
+        tx.nVersion = 3  # A version currently non-standard
+        self.check_mempool_result(
+            result_expected=[{'txid': tx.rehash(), 'allowed': False, 'reject-reason': '64: version'}],
+            rawtxs=[bytes_to_hex_str(tx.serialize())],
+        )
+        tx.deserialize(BytesIO(hex_str_to_bytes(raw_tx_reference)))
+        tx.vout[0].scriptPubKey = CScript([OP_0])  # Some non-standard script
+        self.check_mempool_result(
+            result_expected=[{'txid': tx.rehash(), 'allowed': False, 'reject-reason': '64: scriptpubkey'}],
+            rawtxs=[bytes_to_hex_str(tx.serialize())],
+        )
+        tx.deserialize(BytesIO(hex_str_to_bytes(raw_tx_reference)))
+        tx.vin[0].scriptSig = CScript([OP_HASH160])  # Some not-pushonly scriptSig
+        self.check_mempool_result(
+            result_expected=[{'txid': tx.rehash(), 'allowed': False, 'reject-reason': '64: scriptsig-not-pushonly'}],
+            rawtxs=[bytes_to_hex_str(tx.serialize())],
+        )
+        tx.deserialize(BytesIO(hex_str_to_bytes(raw_tx_reference)))
+        output_p2sh_burn = CTxOut(nValue=540, scriptPubKey=CScript([OP_HASH160, hash160(b'burn'), OP_EQUAL]))
+        num_scripts = 100000 // len(output_p2sh_burn.serialize())  # Use enough outputs to make the tx too large for our policy
+        tx.vout = [output_p2sh_burn] * num_scripts
+        self.check_mempool_result(
+            result_expected=[{'txid': tx.rehash(), 'allowed': False, 'reject-reason': '64: tx-size'}],
+            rawtxs=[bytes_to_hex_str(tx.serialize())],
+        )
+        tx.deserialize(BytesIO(hex_str_to_bytes(raw_tx_reference)))
+        tx.vout[0] = output_p2sh_burn
+        tx.vout[0].nValue -= 1  # Make output smaller, such that it is dust for our policy
+        self.check_mempool_result(
+            result_expected=[{'txid': tx.rehash(), 'allowed': False, 'reject-reason': '64: dust'}],
+            rawtxs=[bytes_to_hex_str(tx.serialize())],
+        )
+        tx.deserialize(BytesIO(hex_str_to_bytes(raw_tx_reference)))
+        tx.vout[0].scriptPubKey = CScript([OP_RETURN, b'\xff'])
+        tx.vout = [tx.vout[0]] * 2
+        self.check_mempool_result(
+            result_expected=[{'txid': tx.rehash(), 'allowed': False, 'reject-reason': '64: multi-op-return'}],
+            rawtxs=[bytes_to_hex_str(tx.serialize())],
+        )
+
+        self.log.info('A timelocked transaction')
+        tx.deserialize(BytesIO(hex_str_to_bytes(raw_tx_reference)))
+        tx.vin[0].nSequence -= 1  # Should be non-max, so locktime is not ignored
+        tx.nLockTime = node.getblockcount() + 1
+        self.check_mempool_result(
+            result_expected=[{'txid': tx.rehash(), 'allowed': False, 'reject-reason': '64: non-final'}],
+            rawtxs=[bytes_to_hex_str(tx.serialize())],
+        )
+
+        self.log.info('A transaction that is locked by BIP68 sequence logic')
+        tx.deserialize(BytesIO(hex_str_to_bytes(raw_tx_reference)))
+        tx.vin[0].nSequence = 2  # We could include it in the second block mined from now, but not the very next one
+        # Can skip re-signing the tx because of early rejection
+        self.check_mempool_result(
+            result_expected=[{'txid': tx.rehash(), 'allowed': False, 'reject-reason': '64: non-BIP68-final'}],
+            rawtxs=[bytes_to_hex_str(tx.serialize())],
+            allowhighfees=True,
+        )
+
+
+if __name__ == '__main__':
+    MempoolAcceptanceTest().main()
diff --git a/test/functional/test_framework/messages.py b/test/functional/test_framework/messages.py
index ee573e01cc..ca2e425bd6 100755
--- a/test/functional/test_framework/messages.py
+++ b/test/functional/test_framework/messages.py
@@ -34,7 +34,9 @@ MY_RELAY = 1 # from version 70001 onwards, fRelay should be appended to version
 MAX_INV_SZ = 50000
 MAX_BLOCK_BASE_SIZE = 1000000
 
-COIN = 100000000 # 1 btc in satoshis
+COIN = 100000000  # 1 btc in satoshis
+
+BIP125_SEQUENCE_NUMBER = 0xfffffffd  # Sequence number that is BIP 125 opt-in and BIP 68-opt-out
 
 NODE_NETWORK = (1 << 0)
 # NODE_GETUTXO = (1 << 1)
@@ -470,6 +472,7 @@ class CTransaction():
     def rehash(self):
         self.sha256 = None
         self.calc_sha256()
+        return self.hash
 
     # We will only cache the serialization without witness in
     # self.sha256 and self.hash -- those are expected to be the txid.
diff --git a/test/functional/test_runner.py b/test/functional/test_runner.py
index a2e92dce3b..3cae4b1df3 100755
--- a/test/functional/test_runner.py
+++ b/test/functional/test_runner.py
@@ -55,7 +55,7 @@ TEST_EXIT_SKIPPED = 77
 # 20 minutes represented in seconds
 TRAVIS_TIMEOUT_DURATION = 20 * 60
 
-BASE_SCRIPTS= [
+BASE_SCRIPTS = [
     # Scripts that are run by the travis build process.
     # Longest test should go first, to favor running tests in parallel
     'wallet_hd.py',
@@ -118,6 +118,7 @@ BASE_SCRIPTS= [
     'wallet_importprunedfunds.py',
     'rpc_signmessage.py',
     'feature_nulldummy.py',
+    'mempool_accept.py',
     'wallet_import_rescan.py',
     'mining_basic.py',
     'wallet_bumpfee.py',
diff --git a/test/functional/wallet_bumpfee.py b/test/functional/wallet_bumpfee.py
index 3e496248fd..5efc846b6e 100755
--- a/test/functional/wallet_bumpfee.py
+++ b/test/functional/wallet_bumpfee.py
@@ -17,14 +17,12 @@ make assumptions about execution order.
 from test_framework.blocktools import send_to_witness
 from test_framework.test_framework import BitcoinTestFramework
 from test_framework import blocktools
+from test_framework.messages import BIP125_SEQUENCE_NUMBER
 from test_framework.mininode import CTransaction
 from test_framework.util import *
 
 import io
 
-# Sequence number that is BIP 125 opt-in and BIP 68-compliant
-BIP125_SEQUENCE_NUMBER = 0xfffffffd
-
 WALLET_PASSPHRASE = "test"
 WALLET_PASSPHRASE_TIMEOUT = 3600