Merge bitcoin/bitcoin#25634: wallet, tests: Expand and test when the blank wallet flag should be un/set

cdba23db35 wallet: Document blank flag use in descriptor wallets (Ryan Ofsky)
43310200dc wallet: Ensure that the blank wallet flag is unset after imports (Andrew Chow)
e9379f1ffa rpc, wallet: Include information about blank flag (Andrew Chow)

Pull request description:

  The `blank` wallet flag is used to indicate that the wallet intentionally does not have any keys, scripts, or descriptors, and it prevents the automatic generation of those things for such a wallet. Once the wallet contains any of those data, it is unnecessary, and possibly incorrect, to have `blank` set. This PR fixes a few places where this was not properly happening. It also adds a test for this unset behavior.

ACKs for top commit:
  S3RK:
    reACK cdba23db35
  ryanofsky:
    Code review ACK cdba23db35. Only change since last review is dropping the commit which makes createwallet RPC set BLANK flag automatically when DISABLE_PRIVATE_KEYS flag is set

Tree-SHA512: 85bc2a9754df0531575d5c8f4ad7e8f38dcd50083dc29b3283dacf56feae842e81f34654c5e1781f2dadb0560ff80e454bbc8ca3b2d1fab1b236499ae9abd7da

src/wallet/rpc/wallet.cpp

@@ -68,6 +68,7 @@ static RPCHelpMan getwalletinfo()
                         }, /*skip_type_check=*/true},
                         {RPCResult::Type::BOOL, "descriptors", "whether this wallet uses descriptors for scriptPubKey management"},
                         {RPCResult::Type::BOOL, "external_signer", "whether this wallet is configured to use an external signer such as a hardware wallet"},
+                        {RPCResult::Type::BOOL, "blank", "Whether this wallet intentionally does not contain any keys, scripts, or descriptors"},
                         RESULT_LAST_PROCESSED_BLOCK,
                     }},
                 },
@@ -130,6 +131,7 @@ static RPCHelpMan getwalletinfo()
     }
     obj.pushKV("descriptors", pwallet->IsWalletFlagSet(WALLET_FLAG_DESCRIPTORS));
     obj.pushKV("external_signer", pwallet->IsWalletFlagSet(WALLET_FLAG_EXTERNAL_SIGNER));
+    obj.pushKV("blank", pwallet->IsWalletFlagSet(WALLET_FLAG_BLANK_WALLET));
 
     AppendLastProcessedBlock(obj, *pwallet);
     return obj;

src/wallet/scriptpubkeyman.cpp

@@ -757,12 +757,12 @@ bool LegacyScriptPubKeyMan::AddKeyPubKeyWithDB(WalletBatch& batch, const CKey& s
         RemoveWatchOnly(script);
     }
 
+    m_storage.UnsetBlankWalletFlag(batch);
     if (!m_storage.HasEncryptionKeys()) {
         return batch.WriteKey(pubkey,
                                                  secret.GetPrivKey(),
                                                  mapKeyMetadata[pubkey.GetID()]);
     }
-    m_storage.UnsetBlankWalletFlag(batch);
     return true;
 }
 

src/wallet/walletutil.h

@@ -53,10 +53,18 @@ enum WalletFlags : uint64_t {
     //! Flag set when a wallet contains no HD seed and no private keys, scripts,
     //! addresses, and other watch only things, and is therefore "blank."
     //!
-    //! The only function this flag serves is to distinguish a blank wallet from
+    //! The main function this flag serves is to distinguish a blank wallet from
     //! a newly created wallet when the wallet database is loaded, to avoid
     //! initialization that should only happen on first run.
     //!
+    //! A secondary function of this flag, which applies to descriptor wallets
+    //! only, is to serve as an ongoing indication that descriptors in the
+    //! wallet should be created manually, and that the wallet should not
+    //! generate automatically generate new descriptors if it is later
+    //! encrypted. To support this behavior, descriptor wallets unlike legacy
+    //! wallets do not automatically unset the BLANK flag when things are
+    //! imported.
+    //!
     //! This flag is also a mandatory flag to prevent previous versions of
     //! bitcoin from opening the wallet, thinking it was newly created, and
     //! then improperly reinitializing it.

test/functional/test_runner.py

@@ -166,6 +166,8 @@ BASE_SCRIPTS = [
     'p2p_compactblocks_blocksonly.py',
     'wallet_hd.py --legacy-wallet',
     'wallet_hd.py --descriptors',
+    'wallet_blank.py --legacy-wallet',
+    'wallet_blank.py --descriptors',
     'wallet_keypool_topup.py --legacy-wallet',
     'wallet_keypool_topup.py --descriptors',
     'wallet_fast_rescan.py --descriptors',

test/functional/wallet_blank.py

@@ -0,0 +1,170 @@
+#!/usr/bin/env python3
+# Copyright (c) 2022 The Bitcoin Core developers
+# Distributed under the MIT software license, see the accompanying
+# file COPYING or https://www.opensource.org/licenses/mit-license.php.
+
+import os
+
+from test_framework.test_framework import BitcoinTestFramework
+from test_framework.address import (
+    ADDRESS_BCRT1_UNSPENDABLE,
+    ADDRESS_BCRT1_UNSPENDABLE_DESCRIPTOR,
+)
+from test_framework.key import ECKey
+from test_framework.util import (
+    assert_equal,
+)
+from test_framework.wallet_util import bytes_to_wif
+
+
+class WalletBlankTest(BitcoinTestFramework):
+    def set_test_params(self):
+        self.num_nodes = 1
+
+    def skip_test_if_missing_module(self):
+        self.skip_if_no_wallet()
+
+    def add_options(self, options):
+        self.add_wallet_options(options)
+
+    def test_importaddress(self):
+        if self.options.descriptors:
+            return
+        self.log.info("Test that importaddress unsets the blank flag")
+        self.nodes[0].createwallet(wallet_name="iaddr", disable_private_keys=True, blank=True)
+        wallet = self.nodes[0].get_wallet_rpc("iaddr")
+        info = wallet.getwalletinfo()
+        assert_equal(info["descriptors"], False)
+        assert_equal(info["blank"], True)
+        wallet.importaddress(ADDRESS_BCRT1_UNSPENDABLE)
+        assert_equal(wallet.getwalletinfo()["blank"], False)
+
+    def test_importpubkey(self):
+        if self.options.descriptors:
+            return
+        self.log.info("Test that importpubkey unsets the blank flag")
+        for i, comp in enumerate([True, False]):
+            self.nodes[0].createwallet(wallet_name=f"ipub{i}", disable_private_keys=True, blank=True)
+            wallet = self.nodes[0].get_wallet_rpc(f"ipub{i}")
+            info = wallet.getwalletinfo()
+            assert_equal(info["descriptors"], False)
+            assert_equal(info["blank"], True)
+
+            eckey = ECKey()
+            eckey.generate(compressed=comp)
+
+            wallet.importpubkey(eckey.get_pubkey().get_bytes().hex())
+            assert_equal(wallet.getwalletinfo()["blank"], False)
+
+    def test_importprivkey(self):
+        if self.options.descriptors:
+            return
+        self.log.info("Test that importprivkey unsets the blank flag")
+        for i, comp in enumerate([True, False]):
+            self.nodes[0].createwallet(wallet_name=f"ipriv{i}", blank=True)
+            wallet = self.nodes[0].get_wallet_rpc(f"ipriv{i}")
+            info = wallet.getwalletinfo()
+            assert_equal(info["descriptors"], False)
+            assert_equal(info["blank"], True)
+
+            eckey = ECKey()
+            eckey.generate(compressed=comp)
+            wif = bytes_to_wif(eckey.get_bytes(), eckey.is_compressed)
+
+            wallet.importprivkey(wif)
+            assert_equal(wallet.getwalletinfo()["blank"], False)
+
+    def test_importmulti(self):
+        if self.options.descriptors:
+            return
+        self.log.info("Test that importmulti unsets the blank flag")
+        self.nodes[0].createwallet(wallet_name="imulti", disable_private_keys=True, blank=True)
+        wallet = self.nodes[0].get_wallet_rpc("imulti")
+        info = wallet.getwalletinfo()
+        assert_equal(info["descriptors"], False)
+        assert_equal(info["blank"], True)
+        wallet.importmulti([{
+            "desc": ADDRESS_BCRT1_UNSPENDABLE_DESCRIPTOR,
+            "timestamp": "now",
+        }])
+        assert_equal(wallet.getwalletinfo()["blank"], False)
+
+    def test_importdescriptors(self):
+        if not self.options.descriptors:
+            return
+        self.log.info("Test that importdescriptors preserves the blank flag")
+        self.nodes[0].createwallet(wallet_name="idesc", disable_private_keys=True, blank=True)
+        wallet = self.nodes[0].get_wallet_rpc("idesc")
+        info = wallet.getwalletinfo()
+        assert_equal(info["descriptors"], True)
+        assert_equal(info["blank"], True)
+        wallet.importdescriptors([{
+            "desc": ADDRESS_BCRT1_UNSPENDABLE_DESCRIPTOR,
+            "timestamp": "now",
+        }])
+        assert_equal(wallet.getwalletinfo()["blank"], True)
+
+    def test_importwallet(self):
+        if self.options.descriptors:
+            return
+        self.log.info("Test that importwallet unsets the blank flag")
+        def_wallet = self.nodes[0].get_wallet_rpc(self.default_wallet_name)
+
+        self.nodes[0].createwallet(wallet_name="iwallet", blank=True)
+        wallet = self.nodes[0].get_wallet_rpc("iwallet")
+        info = wallet.getwalletinfo()
+        assert_equal(info["descriptors"], False)
+        assert_equal(info["blank"], True)
+
+        wallet_dump_path = os.path.join(self.nodes[0].datadir, "wallet.dump")
+        def_wallet.dumpwallet(wallet_dump_path)
+
+        wallet.importwallet(wallet_dump_path)
+        assert_equal(wallet.getwalletinfo()["blank"], False)
+
+    def test_encrypt_legacy(self):
+        if self.options.descriptors:
+            return
+        self.log.info("Test that encrypting a blank legacy wallet preserves the blank flag and does not generate a seed")
+        self.nodes[0].createwallet(wallet_name="encblanklegacy", blank=True)
+        wallet = self.nodes[0].get_wallet_rpc("encblanklegacy")
+
+        info = wallet.getwalletinfo()
+        assert_equal(info["descriptors"], False)
+        assert_equal(info["blank"], True)
+        assert "hdseedid" not in info
+
+        wallet.encryptwallet("pass")
+        info = wallet.getwalletinfo()
+        assert_equal(info["blank"], True)
+        assert "hdseedid" not in info
+
+    def test_encrypt_descriptors(self):
+        if not self.options.descriptors:
+            return
+        self.log.info("Test that encrypting a blank descriptor wallet preserves the blank flag and descriptors remain the same")
+        self.nodes[0].createwallet(wallet_name="encblankdesc", blank=True)
+        wallet = self.nodes[0].get_wallet_rpc("encblankdesc")
+
+        info = wallet.getwalletinfo()
+        assert_equal(info["descriptors"], True)
+        assert_equal(info["blank"], True)
+        descs = wallet.listdescriptors()
+
+        wallet.encryptwallet("pass")
+        assert_equal(wallet.getwalletinfo()["blank"], True)
+        assert_equal(descs, wallet.listdescriptors())
+
+    def run_test(self):
+        self.test_importaddress()
+        self.test_importpubkey()
+        self.test_importprivkey()
+        self.test_importmulti()
+        self.test_importdescriptors()
+        self.test_importwallet()
+        self.test_encrypt_legacy()
+        self.test_encrypt_descriptors()
+
+
+if __name__ == '__main__':
+    WalletBlankTest().main()