Merge bitcoin/bitcoin#18554: wallet: ensure wallet files are not reused across chains

5f213213cb tests: add tests for cross-chain wallet use prevention (Seibart Nedor)
968765973b wallet: ensure wallet files are not reused across chains (Seibart Nedor)

Pull request description:

  This implements a proposal in #12805 and is a rebase of #14533.

  This seems to be a working approach, but I'm not sure why the `p2p_segwit.py` functional test needed a change, so I'll look into it more.

ACKs for top commit:
  achow101:
    ACK 5f213213cb
  dongcarl:
    Code Review ACK 5f213213cb
  [deleted]:
    tACK 5f213213cb

Tree-SHA512: 2c934300f113e772fc31c16ef5588526300bbc36e4dcef7d77bd0760c5c8f0ec77f766b1bed5503eb0157fa26dc900ed54d2ad1b41863c1f736ce5c1f3b67bec

test/functional/test_runner.py

@@ -255,6 +255,7 @@ BASE_SCRIPTS = [
     'rpc_bind.py --ipv4',
     'rpc_bind.py --ipv6',
     'rpc_bind.py --nonloopback',
+    'wallet_crosschain.py',
     'mining_basic.py',
     'feature_signet.py',
     'wallet_bumpfee.py --legacy-wallet',

test/functional/wallet_crosschain.py

@@ -0,0 +1,60 @@
+#!/usr/bin/env python3
+# Copyright (c) 2020 The Bitcoin Core developers
+# Distributed under the MIT software license, see the accompanying
+# file COPYING or http://www.opensource.org/licenses/mit-license.php.
+
+import os
+
+from test_framework.test_framework import BitcoinTestFramework
+from test_framework.util import assert_raises_rpc_error
+
+class WalletCrossChain(BitcoinTestFramework):
+    def set_test_params(self):
+        self.num_nodes = 2
+        self.setup_clean_chain = True
+
+    def skip_test_if_missing_module(self):
+        self.skip_if_no_wallet()
+
+    def setup_network(self):
+        self.add_nodes(self.num_nodes)
+
+        # Switch node 1 to testnet before starting it.
+        self.nodes[1].chain = 'testnet3'
+        self.nodes[1].extra_args = ['-maxconnections=0'] # disable testnet sync
+        with open(self.nodes[1].bitcoinconf, 'r', encoding='utf8') as conf:
+            conf_data = conf.read()
+        with open (self.nodes[1].bitcoinconf, 'w', encoding='utf8') as conf:
+            conf.write(conf_data.replace('regtest=', 'testnet=').replace('[regtest]', '[test]'))
+
+        self.start_nodes()
+
+    def run_test(self):
+        self.log.info("Creating wallets")
+
+        node0_wallet = os.path.join(self.nodes[0].datadir, 'node0_wallet')
+        self.nodes[0].createwallet(node0_wallet)
+        self.nodes[0].unloadwallet(node0_wallet)
+        node1_wallet = os.path.join(self.nodes[1].datadir, 'node1_wallet')
+        self.nodes[1].createwallet(node1_wallet)
+        self.nodes[1].unloadwallet(node1_wallet)
+
+        self.log.info("Loading wallets into nodes with a different genesis blocks")
+
+        if self.options.descriptors:
+            assert_raises_rpc_error(-18, 'Wallet file verification failed.', self.nodes[0].loadwallet, node1_wallet)
+            assert_raises_rpc_error(-18, 'Wallet file verification failed.', self.nodes[1].loadwallet, node0_wallet)
+        else:
+            assert_raises_rpc_error(-4, 'Wallet files should not be reused across chains.', self.nodes[0].loadwallet, node1_wallet)
+            assert_raises_rpc_error(-4, 'Wallet files should not be reused across chains.', self.nodes[1].loadwallet, node0_wallet)
+
+        if not self.options.descriptors:
+            self.log.info("Override cross-chain wallet load protection")
+            self.stop_nodes()
+            self.start_nodes([['-walletcrosschain']] * self.num_nodes)
+            self.nodes[0].loadwallet(node1_wallet)
+            self.nodes[1].loadwallet(node0_wallet)
+
+
+if __name__ == '__main__':
+    WalletCrossChain().main()