Add tests for transaction replacement

qa/replace-by-fee/.gitignore

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+python-bitcoinlib

qa/replace-by-fee/README.md

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+Replace-by-fee regression tests
+===============================
+
+First get version v0.5.0 of the python-bitcoinlib library. In this directory
+run:
+
+    git clone -n https://github.com/petertodd/python-bitcoinlib
+    (cd python-bitcoinlib && git checkout 8270bfd9c6ac37907d75db3d8b9152d61c7255cd)
+
+Then run the tests themselves with a bitcoind available running in regtest
+mode:
+
+    ./rbf-tests.py

qa/replace-by-fee/rbf-tests.py

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+#!/usr/bin/env python3
+# Copyright (c) 2015 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 replace-by-fee
+#
+
+import os
+import sys
+
+# Add python-bitcoinlib to module search path:
+sys.path.append(os.path.join(os.path.dirname(os.path.abspath(__file__)), "python-bitcoinlib"))
+
+import unittest
+
+import bitcoin
+bitcoin.SelectParams('regtest')
+
+import bitcoin.rpc
+
+from bitcoin.core import *
+from bitcoin.core.script import *
+from bitcoin.wallet import *
+
+MAX_REPLACEMENT_LIMIT = 100
+
+class Test_ReplaceByFee(unittest.TestCase):
+    proxy = None
+
+    @classmethod
+    def setUpClass(cls):
+        if cls.proxy is None:
+            cls.proxy = bitcoin.rpc.Proxy()
+
+    @classmethod
+    def tearDownClass(cls):
+        # Make sure mining works
+        mempool_size = 1
+        while mempool_size:
+            cls.proxy.call('generate',1)
+            new_mempool_size = len(cls.proxy.getrawmempool())
+
+            # It's possible to get stuck in a loop here if the mempool has
+            # transactions that can't be mined.
+            assert(new_mempool_size != mempool_size)
+            mempool_size = new_mempool_size
+
+    def make_txout(self, amount, scriptPubKey=CScript([1])):
+        """Create a txout with a given amount and scriptPubKey
+
+        Mines coins as needed.
+        """
+        fee = 1*COIN
+        while self.proxy.getbalance() < amount + fee:
+            self.proxy.call('generate', 100)
+
+        addr = P2SHBitcoinAddress.from_redeemScript(CScript([]))
+        txid = self.proxy.sendtoaddress(addr, amount + fee)
+
+        tx1 = self.proxy.getrawtransaction(txid)
+
+        i = None
+        for i, txout in enumerate(tx1.vout):
+            if txout.scriptPubKey == addr.to_scriptPubKey():
+                break
+        assert i is not None
+
+        tx2 = CTransaction([CTxIn(COutPoint(txid, i), CScript([1, CScript([])]), nSequence=0)],
+                           [CTxOut(amount, scriptPubKey)])
+
+        tx2_txid = self.proxy.sendrawtransaction(tx2, True)
+
+        return COutPoint(tx2_txid, 0)
+
+    def test_simple_doublespend(self):
+        """Simple doublespend"""
+        tx0_outpoint = self.make_txout(1.1*COIN)
+
+        tx1a = CTransaction([CTxIn(tx0_outpoint, nSequence=0)],
+                            [CTxOut(1*COIN, CScript([b'a']))])
+        tx1a_txid = self.proxy.sendrawtransaction(tx1a, True)
+
+        # Should fail because we haven't changed the fee
+        tx1b = CTransaction([CTxIn(tx0_outpoint, nSequence=0)],
+                            [CTxOut(1*COIN, CScript([b'b']))])
+
+        try:
+            tx1b_txid = self.proxy.sendrawtransaction(tx1b, True)
+        except bitcoin.rpc.JSONRPCException as exp:
+            self.assertEqual(exp.error['code'], -26) # insufficient fee
+        else:
+            self.fail()
+
+        # Extra 0.1 BTC fee
+        tx1b = CTransaction([CTxIn(tx0_outpoint, nSequence=0)],
+                            [CTxOut(0.9*COIN, CScript([b'b']))])
+        tx1b_txid = self.proxy.sendrawtransaction(tx1b, True)
+
+        # tx1a is in fact replaced
+        with self.assertRaises(IndexError):
+            self.proxy.getrawtransaction(tx1a_txid)
+
+        self.assertEqual(tx1b, self.proxy.getrawtransaction(tx1b_txid))
+
+    def test_doublespend_chain(self):
+        """Doublespend of a long chain"""
+
+        initial_nValue = 50*COIN
+        tx0_outpoint = self.make_txout(initial_nValue)
+
+        prevout = tx0_outpoint
+        remaining_value = initial_nValue
+        chain_txids = []
+        while remaining_value > 10*COIN:
+            remaining_value -= 1*COIN
+            tx = CTransaction([CTxIn(prevout, nSequence=0)],
+                              [CTxOut(remaining_value, CScript([1]))])
+            txid = self.proxy.sendrawtransaction(tx, True)
+            chain_txids.append(txid)
+            prevout = COutPoint(txid, 0)
+
+        # Whether the double-spend is allowed is evaluated by including all
+        # child fees - 40 BTC - so this attempt is rejected.
+        dbl_tx = CTransaction([CTxIn(tx0_outpoint, nSequence=0)],
+                              [CTxOut(initial_nValue - 30*COIN, CScript([1]))])
+
+        try:
+            self.proxy.sendrawtransaction(dbl_tx, True)
+        except bitcoin.rpc.JSONRPCException as exp:
+            self.assertEqual(exp.error['code'], -26) # insufficient fee
+        else:
+            self.fail()
+
+        # Accepted with sufficient fee
+        dbl_tx = CTransaction([CTxIn(tx0_outpoint, nSequence=0)],
+                              [CTxOut(1*COIN, CScript([1]))])
+        self.proxy.sendrawtransaction(dbl_tx, True)
+
+        for doublespent_txid in chain_txids:
+            with self.assertRaises(IndexError):
+                self.proxy.getrawtransaction(doublespent_txid)
+
+    def test_doublespend_tree(self):
+        """Doublespend of a big tree of transactions"""
+
+        initial_nValue = 50*COIN
+        tx0_outpoint = self.make_txout(initial_nValue)
+
+        def branch(prevout, initial_value, max_txs, *, tree_width=5, fee=0.0001*COIN, _total_txs=None):
+            if _total_txs is None:
+                _total_txs = [0]
+            if _total_txs[0] >= max_txs:
+                return
+
+            txout_value = (initial_value - fee) // tree_width
+            if txout_value < fee:
+                return
+
+            vout = [CTxOut(txout_value, CScript([i+1]))
+                    for i in range(tree_width)]
+            tx = CTransaction([CTxIn(prevout, nSequence=0)],
+                              vout)
+
+            self.assertTrue(len(tx.serialize()) < 100000)
+            txid = self.proxy.sendrawtransaction(tx, True)
+            yield tx
+            _total_txs[0] += 1
+
+            for i, txout in enumerate(tx.vout):
+                yield from branch(COutPoint(txid, i), txout_value,
+                                  max_txs,
+                                  tree_width=tree_width, fee=fee,
+                                  _total_txs=_total_txs)
+
+        fee = 0.0001*COIN
+        n = MAX_REPLACEMENT_LIMIT
+        tree_txs = list(branch(tx0_outpoint, initial_nValue, n, fee=fee))
+        self.assertEqual(len(tree_txs), n)
+
+        # Attempt double-spend, will fail because too little fee paid
+        dbl_tx = CTransaction([CTxIn(tx0_outpoint, nSequence=0)],
+                              [CTxOut(initial_nValue - fee*n, CScript([1]))])
+        try:
+            self.proxy.sendrawtransaction(dbl_tx, True)
+        except bitcoin.rpc.JSONRPCException as exp:
+            self.assertEqual(exp.error['code'], -26) # insufficient fee
+        else:
+            self.fail()
+
+        # 1 BTC fee is enough
+        dbl_tx = CTransaction([CTxIn(tx0_outpoint, nSequence=0)],
+                              [CTxOut(initial_nValue - fee*n - 1*COIN, CScript([1]))])
+        self.proxy.sendrawtransaction(dbl_tx, True)
+
+        for tx in tree_txs:
+            with self.assertRaises(IndexError):
+                self.proxy.getrawtransaction(tx.GetHash())
+
+        # Try again, but with more total transactions than the "max txs
+        # double-spent at once" anti-DoS limit.
+        for n in (MAX_REPLACEMENT_LIMIT, MAX_REPLACEMENT_LIMIT*2):
+            fee = 0.0001*COIN
+            tx0_outpoint = self.make_txout(initial_nValue)
+            tree_txs = list(branch(tx0_outpoint, initial_nValue, n, fee=fee))
+            self.assertEqual(len(tree_txs), n)
+
+            dbl_tx = CTransaction([CTxIn(tx0_outpoint, nSequence=0)],
+                                  [CTxOut(initial_nValue - fee*n, CScript([1]))])
+            try:
+                self.proxy.sendrawtransaction(dbl_tx, True)
+            except bitcoin.rpc.JSONRPCException as exp:
+                self.assertEqual(exp.error['code'], -26)
+            else:
+                self.fail()
+
+            for tx in tree_txs:
+                self.proxy.getrawtransaction(tx.GetHash())
+
+    def test_replacement_feeperkb(self):
+        """Replacement requires overall fee-per-KB to be higher"""
+        tx0_outpoint = self.make_txout(1.1*COIN)
+
+        tx1a = CTransaction([CTxIn(tx0_outpoint, nSequence=0)],
+                            [CTxOut(1*COIN, CScript([b'a']))])
+        tx1a_txid = self.proxy.sendrawtransaction(tx1a, True)
+
+        # Higher fee, but the fee per KB is much lower, so the replacement is
+        # rejected.
+        tx1b = CTransaction([CTxIn(tx0_outpoint, nSequence=0)],
+                            [CTxOut(0.001*COIN,
+                                    CScript([b'a'*999000]))])
+
+        try:
+            tx1b_txid = self.proxy.sendrawtransaction(tx1b, True)
+        except bitcoin.rpc.JSONRPCException as exp:
+            self.assertEqual(exp.error['code'], -26) # insufficient fee
+        else:
+            self.fail()
+
+    def test_spends_of_conflicting_outputs(self):
+        """Replacements that spend conflicting tx outputs are rejected"""
+        utxo1 = self.make_txout(1.2*COIN)
+        utxo2 = self.make_txout(3.0*COIN)
+
+        tx1a = CTransaction([CTxIn(utxo1, nSequence=0)],
+                            [CTxOut(1.1*COIN, CScript([b'a']))])
+        tx1a_txid = self.proxy.sendrawtransaction(tx1a, True)
+
+        # Direct spend an output of the transaction we're replacing.
+        tx2 = CTransaction([CTxIn(utxo1, nSequence=0), CTxIn(utxo2, nSequence=0),
+                            CTxIn(COutPoint(tx1a_txid, 0), nSequence=0)],
+                           tx1a.vout)
+
+        try:
+            tx2_txid = self.proxy.sendrawtransaction(tx2, True)
+        except bitcoin.rpc.JSONRPCException as exp:
+            self.assertEqual(exp.error['code'], -26)
+        else:
+            self.fail()
+
+        # Spend tx1a's output to test the indirect case.
+        tx1b = CTransaction([CTxIn(COutPoint(tx1a_txid, 0), nSequence=0)],
+                            [CTxOut(1.0*COIN, CScript([b'a']))])
+        tx1b_txid = self.proxy.sendrawtransaction(tx1b, True)
+
+        tx2 = CTransaction([CTxIn(utxo1, nSequence=0), CTxIn(utxo2, nSequence=0),
+                            CTxIn(COutPoint(tx1b_txid, 0))],
+                           tx1a.vout)
+
+        try:
+            tx2_txid = self.proxy.sendrawtransaction(tx2, True)
+        except bitcoin.rpc.JSONRPCException as exp:
+            self.assertEqual(exp.error['code'], -26)
+        else:
+            self.fail()
+
+if __name__ == '__main__':
+    unittest.main()