wallet, rpc: Disallow importing unused() to wallets without privkeys

Author: achow101

src/wallet/rpc/backup.cpp

@@ -1575,6 +1575,9 @@ static UniValue ProcessDescriptorImport(CWallet& wallet, const UniValue& data, c
 
             // If this is an unused(KEY) descriptor, check that the wallet doesn't already have other descriptors with this key
             if (!parsed_desc->HasScripts()) {
+                if (wallet.IsWalletFlagSet(WALLET_FLAG_DISABLE_PRIVATE_KEYS)) {
+                    throw JSONRPCError(RPC_WALLET_ERROR, "Cannot import unused() to wallet without private keys enabled");
+                }
                 // Unused descriptors must contain a single key.
                 // Earlier checks will have enforced that this key is either a private key when private keys are enabled,
                 // or that this key is a public key when private keys are disabled.

test/functional/wallet_importdescriptors.py

@@ -100,6 +100,20 @@ def test_import_unused_key_existing(self):
                              wallet=wallet)
         wallet.unloadwallet()
 
+    def test_import_unused_noprivs(self):
+        self.log.info("Test import of unused(KEY) to wallet without privkeys")
+        self.nodes[0].createwallet(wallet_name="import_unused_noprivs", disable_private_keys=True)
+        wallet = self.nodes[0].get_wallet_rpc("import_unused_noprivs")
+
+        xpub = "tpubD6NzVbkrYhZ4YNXVQbNhMK1WqguFsUXceaVJKbmno2aZ3B6QfbMeraaYvnBSGpV3vxLyTTK9DYT1yoEck4XUScMzXoQ2U2oSmE2JyMedq3H"
+        self.test_importdesc({"timestamp": "now", "desc": descsum_create(f"unused({xpub})")},
+                             success=False,
+                             error_code=-4,
+                             error_message="Cannot import unused() to wallet without private keys enabled",
+                             wallet=wallet)
+        wallet.unloadwallet()
+
+
     def run_test(self):
         self.log.info('Setting up wallets')
         self.nodes[0].createwallet(wallet_name='w0', disable_private_keys=False, descriptors=True)
@@ -795,6 +809,7 @@ def run_test(self):
 
         self.test_import_unused_key()
         self.test_import_unused_key_existing()
+        self.test_import_unused_noprivs()
 
 if __name__ == '__main__':
     ImportDescriptorsTest(__file__).main()