Merge bitcoin/bitcoin#28920: wallet: birth time update during tx scanning

1ce45baed7 rpc: getwalletinfo, return wallet 'birthtime' (furszy)
83c66444d0 test: coverage for wallet birth time interaction with -reindex (furszy)
6f497377aa wallet: fix legacy spkm default birth time (furszy)
75fbf444c1 wallet: birth time update during tx scanning (furszy)
b4306e3c8d refactor: rename FirstKeyTimeChanged to MaybeUpdateBirthTime (furszy)

Pull request description:

  Fixing #28897.

  As the user may have imported a descriptor with a timestamp newer
  than the actual birth time of the first key (by setting 'timestamp=now'),
  the wallet needs to update the birth time when it detects a transaction
  older than the oldest descriptor timestamp.

  Testing Notes:
  Can cherry-pick the test commit on top of master. It will fail there.

ACKs for top commit:
  Sjors:
    re-utACK 1ce45baed7
  achow101:
    ACK 1ce45baed7

Tree-SHA512: 10c2382f87356ae9ea3fcb637d7edc5ed0e51e13cc2729c314c9ffb57c684b9ac3c4b757b85810c0a674020b7287c43d3be8273bcf75e2aff0cc1c037f1159f9

test/functional/test_runner.py

@@ -207,6 +207,8 @@ BASE_SCRIPTS = [
     'wallet_createwallet.py --descriptors',
     'wallet_watchonly.py --legacy-wallet',
     'wallet_watchonly.py --usecli --legacy-wallet',
+    'wallet_reindex.py --legacy-wallet',
+    'wallet_reindex.py --descriptors',
     'wallet_reorgsrestore.py',
     'wallet_conflicts.py --legacy-wallet',
     'wallet_conflicts.py --descriptors',

test/functional/wallet_reindex.py

@@ -0,0 +1,108 @@
+#!/usr/bin/env python3
+# Copyright (c) 2023-present The Bitcoin Core developers
+# Distributed under the MIT software license, see the accompanying
+# file COPYING or https://www.opensource.org/licenses/mit-license.php.
+
+"""Test wallet-reindex interaction"""
+
+import time
+
+from test_framework.blocktools import COINBASE_MATURITY
+from test_framework.test_framework import BitcoinTestFramework
+from test_framework.util import (
+    assert_equal,
+)
+BLOCK_TIME = 60 * 10
+
+class WalletReindexTest(BitcoinTestFramework):
+    def add_options(self, parser):
+        self.add_wallet_options(parser)
+
+    def set_test_params(self):
+        self.num_nodes = 1
+        self.setup_clean_chain = True
+
+    def skip_test_if_missing_module(self):
+        self.skip_if_no_wallet()
+
+    def advance_time(self, node, secs):
+        self.node_time += secs
+        node.setmocktime(self.node_time)
+
+    # Verify the wallet updates the birth time accordingly when it detects a transaction
+    # with a time older than the oldest descriptor timestamp.
+    # This could happen when the user blindly imports a descriptor with 'timestamp=now'.
+    def birthtime_test(self, node, miner_wallet):
+        self.log.info("Test birth time update during tx scanning")
+        # Fund address to test
+        wallet_addr = miner_wallet.getnewaddress()
+        tx_id = miner_wallet.sendtoaddress(wallet_addr, 2)
+
+        # Generate 50 blocks, one every 10 min to surpass the 2 hours rescan window the wallet has
+        for _ in range(50):
+            self.generate(node, 1)
+            self.advance_time(node, BLOCK_TIME)
+
+        # Now create a new wallet, and import the descriptor
+        node.createwallet(wallet_name='watch_only', disable_private_keys=True, load_on_startup=True)
+        wallet_watch_only = node.get_wallet_rpc('watch_only')
+        # Blank wallets don't have a birth time
+        assert 'birthtime' not in wallet_watch_only.getwalletinfo()
+
+        # For a descriptors wallet: Import address with timestamp=now.
+        # For legacy wallet: There is no way of importing a script/address with a custom time. The wallet always imports it with birthtime=1.
+        # In both cases, disable rescan to not detect the transaction.
+        wallet_watch_only.importaddress(wallet_addr, rescan=False)
+        assert_equal(len(wallet_watch_only.listtransactions()), 0)
+
+        # Depending on the wallet type, the birth time changes.
+        wallet_birthtime = wallet_watch_only.getwalletinfo()['birthtime']
+        if self.options.descriptors:
+            # As blocks were generated every 10 min, the chain MTP timestamp is node_time - 60 min.
+            assert_equal(self.node_time - BLOCK_TIME * 6, wallet_birthtime)
+        else:
+            # No way of importing scripts/addresses with a custom time on a legacy wallet.
+            # It's always set to the beginning of time.
+            assert_equal(wallet_birthtime, 1)
+
+        # Rescan the wallet to detect the missing transaction
+        wallet_watch_only.rescanblockchain()
+        assert_equal(wallet_watch_only.gettransaction(tx_id)['confirmations'], 50)
+        assert_equal(wallet_watch_only.getbalances()['mine' if self.options.descriptors else 'watchonly']['trusted'], 2)
+
+        # Reindex and wait for it to finish
+        with node.assert_debug_log(expected_msgs=["initload thread exit"]):
+            self.restart_node(0, extra_args=['-reindex=1', f'-mocktime={self.node_time}'])
+        node.syncwithvalidationinterfacequeue()
+
+        # Verify the transaction is still 'confirmed' after reindex
+        wallet_watch_only = node.get_wallet_rpc('watch_only')
+        tx_info = wallet_watch_only.gettransaction(tx_id)
+        assert_equal(tx_info['confirmations'], 50)
+
+        # Depending on the wallet type, the birth time changes.
+        if self.options.descriptors:
+            # For descriptors, verify the wallet updated the birth time to the transaction time
+            assert_equal(tx_info['time'], wallet_watch_only.getwalletinfo()['birthtime'])
+        else:
+            # For legacy, as the birth time was set to the beginning of time, verify it did not change
+            assert_equal(wallet_birthtime, 1)
+
+        wallet_watch_only.unloadwallet()
+
+    def run_test(self):
+        node = self.nodes[0]
+        self.node_time = int(time.time())
+        node.setmocktime(self.node_time)
+
+        # Fund miner
+        node.createwallet(wallet_name='miner', load_on_startup=True)
+        miner_wallet = node.get_wallet_rpc('miner')
+        self.generatetoaddress(node, COINBASE_MATURITY + 10, miner_wallet.getnewaddress())
+
+        # Tests
+        self.birthtime_test(node, miner_wallet)
+
+
+if __name__ == '__main__':
+    WalletReindexTest().main()