Merge #20226: wallet, rpc: add listdescriptors command

647b81b70938dc4dbcf32399c56f78be395c721a wallet, rpc: add listdescriptors command (Ivan Metlushko)

Pull request description:

  Looking for concept ACKs

  **Rationale**: allow users to inspect the contents of their newly created descriptor wallets.

  Currently the command only returns xpubs which is not very useful in itself, but there are multiples ways to extend it:
   * add an option to export xprv
   * with #19136 it'll be possible to return normalised descriptors suitable for a watch-only purposes

  The output is compatible with `importdescriptors` command so it could be easily used for backup/recover purposes.

  **Output example:**
  ```json
  [
    {
      "desc": "wpkh(tpubD6NzVbkrYhZ4WW6E2ZETFyNfq2hfF23SKxqSGFvUpPAY58jmmuBybwqwFihAyQPk9KnwTt5516NDZRJ7k5QPeKjy7wuVd5WvXNxwwAs5tUD/*)#nhavpr5h",
      "timestamp": 1296688602,
      "active": false,
      "range": [
        0,
        999
      ],
      "next": 0
    }
  ]
  ```

ACKs for top commit:
  jonatack:
    re-ACK 647b81b70938dc4dbcf32399c56f78be395c721a rebased to master, debug builds cleanly, reviewed diff since last review, tested with a descriptor wallet (and with a legacy wallet)
  achow101:
    re-ACK 647b81b

Tree-SHA512: 51a3620bb17c836c52cecb066d4fa9d5ff418af56809046eaee0528c4dc240a4e90fff5711ba96e399c6664e00b9ee8194e33852b1b9e75af18061296e19a8a7

4 files changed, 139 insertions, 0 deletions

diff --git a/src/wallet/rpcdump.cpp b/src/wallet/rpcdump.cpp
index 6b46868d10..8505ddc309 100644
--- a/src/wallet/rpcdump.cpp
+++ b/src/wallet/rpcdump.cpp
@@ -1740,3 +1740,72 @@ RPCHelpMan importdescriptors()
 },
     };
 }
+
+RPCHelpMan listdescriptors()
+{
+    return RPCHelpMan{
+        "listdescriptors",
+        "\nList descriptors imported into a descriptor-enabled wallet.",
+        {},
+        RPCResult{
+            RPCResult::Type::ARR, "", "Response is an array of descriptor objects",
+            {
+                {RPCResult::Type::OBJ, "", "", {
+                    {RPCResult::Type::STR, "desc", "Descriptor string representation"},
+                    {RPCResult::Type::NUM, "timestamp", "The creation time of the descriptor"},
+                    {RPCResult::Type::BOOL, "active", "Activeness flag"},
+                    {RPCResult::Type::BOOL, "internal", true, "Whether this is internal or external descriptor; defined only for active descriptors"},
+                    {RPCResult::Type::ARR_FIXED, "range", true, "Defined only for ranged descriptors", {
+                        {RPCResult::Type::NUM, "", "Range start inclusive"},
+                        {RPCResult::Type::NUM, "", "Range end inclusive"},
+                    }},
+                    {RPCResult::Type::NUM, "next", true, "The next index to generate addresses from; defined only for ranged descriptors"},
+                }},
+            }
+        },
+        RPCExamples{
+            HelpExampleCli("listdescriptors", "") + HelpExampleRpc("listdescriptors", "")
+        },
+        [&](const RPCHelpMan& self, const JSONRPCRequest& request) -> UniValue
+{
+    std::shared_ptr<CWallet> const wallet = GetWalletForJSONRPCRequest(request);
+    if (!wallet) return NullUniValue;
+
+    if (!wallet->IsWalletFlagSet(WALLET_FLAG_DESCRIPTORS)) {
+        throw JSONRPCError(RPC_WALLET_ERROR, "listdescriptors is not available for non-descriptor wallets");
+    }
+
+    LOCK(wallet->cs_wallet);
+
+    UniValue response(UniValue::VARR);
+    const auto active_spk_mans = wallet->GetActiveScriptPubKeyMans();
+    for (const auto& spk_man : wallet->GetAllScriptPubKeyMans()) {
+        const auto desc_spk_man = dynamic_cast<DescriptorScriptPubKeyMan*>(spk_man);
+        if (!desc_spk_man) {
+            throw JSONRPCError(RPC_WALLET_ERROR, "Unexpected ScriptPubKey manager type.");
+        }
+        UniValue spk(UniValue::VOBJ);
+        LOCK(desc_spk_man->cs_desc_man);
+        const auto& wallet_descriptor = desc_spk_man->GetWalletDescriptor();
+        spk.pushKV("desc", wallet_descriptor.descriptor->ToString());
+        spk.pushKV("timestamp", wallet_descriptor.creation_time);
+        const bool active = active_spk_mans.count(desc_spk_man) != 0;
+        spk.pushKV("active", active);
+        const auto& type = wallet_descriptor.descriptor->GetOutputType();
+        if (active && type != nullopt) {
+            spk.pushKV("internal", wallet->GetScriptPubKeyMan(*type, true) == desc_spk_man);
+        }
+        if (wallet_descriptor.descriptor->IsRange()) {
+            UniValue range(UniValue::VARR);
+            range.push_back(wallet_descriptor.range_start);
+            range.push_back(wallet_descriptor.range_end - 1);
+            spk.pushKV("range", range);
+            spk.pushKV("next", wallet_descriptor.next_index);
+        }
+        response.push_back(spk);
+    }
+
+    return response;
+},
+    };
+}
diff --git a/src/wallet/rpcwallet.cpp b/src/wallet/rpcwallet.cpp
index ec51ba0453..75888cfd66 100644
--- a/src/wallet/rpcwallet.cpp
+++ b/src/wallet/rpcwallet.cpp
@@ -4551,6 +4551,7 @@ RPCHelpMan importprunedfunds();
 RPCHelpMan removeprunedfunds();
 RPCHelpMan importmulti();
 RPCHelpMan importdescriptors();
+RPCHelpMan listdescriptors();
 
 Span<const CRPCCommand> GetWalletRPCCommands()
 {
@@ -4589,6 +4590,7 @@ static const CRPCCommand commands[] =
     { "wallet",             "importwallet",                     &importwallet,                  {"filename"} },
     { "wallet",             "keypoolrefill",                    &keypoolrefill,                 {"newsize"} },
     { "wallet",             "listaddressgroupings",             &listaddressgroupings,          {} },
+    { "wallet",             "listdescriptors",                  &listdescriptors,               {} },
     { "wallet",             "listlabels",                       &listlabels,                    {"purpose"} },
     { "wallet",             "listlockunspent",                  &listlockunspent,               {} },
     { "wallet",             "listreceivedbyaddress",            &listreceivedbyaddress,         {"minconf","include_empty","include_watchonly","address_filter"} },
diff --git a/test/functional/test_runner.py b/test/functional/test_runner.py
index 898d4bfe17..c652ac0a06 100755
--- a/test/functional/test_runner.py
+++ b/test/functional/test_runner.py
@@ -238,6 +238,7 @@ BASE_SCRIPTS = [
     'rpc_named_arguments.py',
     'wallet_listsinceblock.py',
     'wallet_listsinceblock.py --descriptors',
+    'wallet_listdescriptors.py --descriptors',
     'p2p_leak.py',
     'wallet_encryption.py',
     'wallet_encryption.py --descriptors',
diff --git a/test/functional/wallet_listdescriptors.py b/test/functional/wallet_listdescriptors.py
new file mode 100755
index 0000000000..9f8c341bc7
--- /dev/null
+++ b/test/functional/wallet_listdescriptors.py
@@ -0,0 +1,67 @@
+#!/usr/bin/env python3
+# Copyright (c) 2014-2021 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 the listdescriptors RPC."""
+
+from test_framework.descriptors import (
+    descsum_create
+)
+from test_framework.test_framework import BitcoinTestFramework
+from test_framework.util import (
+    assert_equal,
+    assert_raises_rpc_error,
+)
+
+
+class ListDescriptorsTest(BitcoinTestFramework):
+    def set_test_params(self):
+        self.num_nodes = 1
+
+    def skip_test_if_missing_module(self):
+        self.skip_if_no_wallet()
+        self.skip_if_no_sqlite()
+
+    # do not create any wallet by default
+    def init_wallet(self, i):
+        return
+
+    def run_test(self):
+        node = self.nodes[0]
+        assert_raises_rpc_error(-18, 'No wallet is loaded.', node.listdescriptors)
+
+        self.log.info('Test that the command is not available for legacy wallets.')
+        node.createwallet(wallet_name='w1', descriptors=False)
+        assert_raises_rpc_error(-4, 'listdescriptors is not available for non-descriptor wallets', node.listdescriptors)
+
+        self.log.info('Test the command for empty descriptors wallet.')
+        node.createwallet(wallet_name='w2', blank=True, descriptors=True)
+        assert_equal(0, len(node.get_wallet_rpc('w2').listdescriptors()))
+
+        self.log.info('Test the command for a default descriptors wallet.')
+        node.createwallet(wallet_name='w3', descriptors=True)
+        result = node.get_wallet_rpc('w3').listdescriptors()
+        assert_equal(6, len(result))
+        assert_equal(6, len([d for d in result if d['active']]))
+        assert_equal(3, len([d for d in result if d['internal']]))
+        for item in result:
+            assert item['desc'] != ''
+            assert item['next'] == 0
+            assert item['range'] == [0, 0]
+            assert item['timestamp'] is not None
+
+        self.log.info('Test non-active non-range combo descriptor')
+        node.createwallet(wallet_name='w4', blank=True, descriptors=True)
+        wallet = node.get_wallet_rpc('w4')
+        wallet.importdescriptors([{
+            'desc': descsum_create('combo(' + node.get_deterministic_priv_key().key + ')'),
+            'timestamp': 1296688602,
+        }])
+        expected = [{'active': False,
+                     'desc': 'combo(0227d85ba011276cf25b51df6a188b75e604b38770a462b2d0e9fb2fc839ef5d3f)#np574htj',
+                     'timestamp': 1296688602}]
+        assert_equal(expected, wallet.listdescriptors())
+
+
+if __name__ == '__main__':
+    ListDescriptorsTest().main()