Merge #16624: wallet: encapsulate transactions state

442a87cc0ae43ebc9b6654a6165778eecb931f74 Add a test wallet_reorgsrestore (Antoine Riard)
40ede992d97df38282919693dfe851c975c3b1d8 Modify wallet tx status if has been reorged out (Antoine Riard)
7e89994133725125dddbfa8d45484e3b9ed51c6e Remove SyncTransaction for conflicted txn in CWallet::BlockConnected (Antoine Riard)
a31be09bfd77eed497a8e251d31358e16e2f2eb1 Encapsulate tx status in a Confirmation struct (Antoine Riard)

Pull request description:

  While working on #15931, I've tried to rationalize tx state management to ease integration of block height tracking per-wallet tx. We currently rely on a combination of `hashBlock` and `nIndex` with magic value to determine tx confirmation, conflicted or abandoned state. It's hard to reason and error-prone.  To solve that, we encapsulate these fields in a `TxConfirmation` struct and introduce a `TxState` member that we update accordingly at block connection/disconnection.

  Following jnewbery [recommendation](https://github.com/bitcoin/bitcoin/pull/15931#discussion_r312576506), I've taken these changes in its own commit, and open a PR to get them first. It would ease review of aforementioned PR, but above all should ease fixing of long-term issues like :
  * https://github.com/bitcoin/bitcoin/issues/7315 (but maybe we should abandon abandontransaction or relieve it to only free outpoints not track the transaction as abandoned in itself, need its own discussion)
  * https://github.com/bitcoin/bitcoin/issues/8692 where we should cancel conflicted state of transactions chain smoothly
  * `MarkConflicted` in `LoadToWallet` is likely useless if we track conflicts rights at block connection

  Main changes of this PR to get right are tx update in `AddToWallet` and serialization/deserialization logic.

ACKs for top commit:
  meshcollider:
    Light re-Code Review ACK 442a87cc0ae43ebc9b6654a6165778eecb931f74
  ryanofsky:
    utACK 442a87cc0ae43ebc9b6654a6165778eecb931f74. Changes since last review are switching from `hasChain` to `LockChain` and removing chain lock in `WalletBatch::LoadWallet` that's redundant with the new lock still added in `CWallet::LoadWallet`, and fixing python test race condition.

Tree-SHA512: 029209e006de0240436817204e69e548c5665e2b0721b214510e7aba7eba130a5eab441d3a1ad95bd6426114dd27390492c77bf4560a9610009b32cd0a1f72f7

2 files changed, 106 insertions, 0 deletions

diff --git a/test/functional/test_runner.py b/test/functional/test_runner.py
index ad5673e03a..dd61efa757 100755
--- a/test/functional/test_runner.py
+++ b/test/functional/test_runner.py
@@ -131,6 +131,7 @@ BASE_SCRIPTS = [
     'wallet_createwallet.py --usecli',
     'wallet_watchonly.py',
     'wallet_watchonly.py --usecli',
+    'wallet_reorgsrestore.py',
     'interface_http.py',
     'interface_rpc.py',
     'rpc_psbt.py',
diff --git a/test/functional/wallet_reorgsrestore.py b/test/functional/wallet_reorgsrestore.py
new file mode 100755
index 0000000000..f48018e9fb
--- /dev/null
+++ b/test/functional/wallet_reorgsrestore.py
@@ -0,0 +1,105 @@
+#!/usr/bin/env python3
+# Copyright (c) 2019 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 tx status in case of reorgs while wallet being shutdown.
+
+Wallet txn status rely on block connection/disconnection for its
+accuracy. In case of reorgs happening while wallet being shutdown
+block updates are not going to be received. At wallet loading, we
+check against chain if confirmed txn are still in chain and change
+their status if block in which they have been included has been
+disconnected.
+"""
+
+from decimal import Decimal
+import os
+import shutil
+
+from test_framework.test_framework import BitcoinTestFramework
+from test_framework.util import (
+        assert_equal,
+        connect_nodes,
+        disconnect_nodes,
+)
+
+class ReorgsRestoreTest(BitcoinTestFramework):
+    def set_test_params(self):
+        self.num_nodes = 3
+
+    def skip_test_if_missing_module(self):
+        self.skip_if_no_wallet()
+
+    def run_test(self):
+        # Send a tx from which to conflict outputs later
+        txid_conflict_from = self.nodes[0].sendtoaddress(self.nodes[0].getnewaddress(), Decimal("10"))
+        self.nodes[0].generate(1)
+        self.sync_blocks()
+
+        # Disconnect node1 from others to reorg its chain later
+        disconnect_nodes(self.nodes[0], 1)
+        disconnect_nodes(self.nodes[1], 2)
+        connect_nodes(self.nodes[0], 2)
+
+        # Send a tx to be unconfirmed later
+        txid = self.nodes[0].sendtoaddress(self.nodes[0].getnewaddress(), Decimal("10"))
+        tx = self.nodes[0].gettransaction(txid)
+        self.nodes[0].generate(4)
+        tx_before_reorg = self.nodes[0].gettransaction(txid)
+        assert_equal(tx_before_reorg["confirmations"], 4)
+
+        # Disconnect node0 from node2 to broadcast a conflict on their respective chains
+        disconnect_nodes(self.nodes[0], 2)
+        nA = next(tx_out["vout"] for tx_out in self.nodes[0].gettransaction(txid_conflict_from)["details"] if tx_out["amount"] == Decimal("10"))
+        inputs = []
+        inputs.append({"txid": txid_conflict_from, "vout": nA})
+        outputs_1 = {}
+        outputs_2 = {}
+
+        # Create a conflicted tx broadcast on node0 chain and conflicting tx broadcast on node1 chain. Both spend from txid_conflict_from
+        outputs_1[self.nodes[0].getnewaddress()] = Decimal("9.99998")
+        outputs_2[self.nodes[0].getnewaddress()] = Decimal("9.99998")
+        conflicted = self.nodes[0].signrawtransactionwithwallet(self.nodes[0].createrawtransaction(inputs, outputs_1))
+        conflicting = self.nodes[0].signrawtransactionwithwallet(self.nodes[0].createrawtransaction(inputs, outputs_2))
+
+        conflicted_txid = self.nodes[0].sendrawtransaction(conflicted["hex"])
+        self.nodes[0].generate(1)
+        conflicting_txid = self.nodes[2].sendrawtransaction(conflicting["hex"])
+        self.nodes[2].generate(9)
+
+        # Reconnect node0 and node2 and check that conflicted_txid is effectively conflicted
+        connect_nodes(self.nodes[0], 2)
+        self.sync_blocks([self.nodes[0], self.nodes[2]])
+        conflicted = self.nodes[0].gettransaction(conflicted_txid)
+        conflicting = self.nodes[0].gettransaction(conflicting_txid)
+        assert_equal(conflicted["confirmations"], -9)
+        assert_equal(conflicted["walletconflicts"][0], conflicting["txid"])
+
+        # Node0 wallet is shutdown
+        self.stop_node(0)
+        self.start_node(0)
+
+        # The block chain re-orgs and the tx is included in a different block
+        self.nodes[1].generate(9)
+        self.nodes[1].sendrawtransaction(tx["hex"])
+        self.nodes[1].generate(1)
+        self.nodes[1].sendrawtransaction(conflicted["hex"])
+        self.nodes[1].generate(1)
+
+        # Node0 wallet file is loaded on longest sync'ed node1
+        self.stop_node(1)
+        self.nodes[0].backupwallet(os.path.join(self.nodes[0].datadir, 'wallet.bak'))
+        shutil.copyfile(os.path.join(self.nodes[0].datadir, 'wallet.bak'), os.path.join(self.nodes[1].datadir, 'regtest', 'wallet.dat'))
+        self.start_node(1)
+        tx_after_reorg = self.nodes[1].gettransaction(txid)
+        # Check that normal confirmed tx is confirmed again but with different blockhash
+        assert_equal(tx_after_reorg["confirmations"], 2)
+        assert(tx_before_reorg["blockhash"] != tx_after_reorg["blockhash"])
+        conflicted_after_reorg = self.nodes[1].gettransaction(conflicted_txid)
+        # Check that conflicted tx is confirmed again with blockhash different than previously conflicting tx
+        assert_equal(conflicted_after_reorg["confirmations"], 1)
+        assert(conflicting["blockhash"] != conflicted_after_reorg["blockhash"])
+
+if __name__ == '__main__':
+    ReorgsRestoreTest().main()