feat: new RPC migratewallet to migrate legacy wallets to backport wallets

doc/managing-wallets.md

@@ -121,3 +121,24 @@ $ dash-cli -rpcwallet="restored-wallet" getwalletinfo
 ```
 
 The restored wallet can also be loaded in the GUI via `File` ->`Open wallet`.
+
+## Migrating Legacy Wallets to Descriptor Wallets
+
+Legacy wallets (traditional non-descriptor wallets) can be migrated to become Descriptor wallets
+through the use of the `migratewallet` RPC. Migrated wallets will have all of their addresses and private keys added to
+a newly created Descriptor wallet that has the same name as the original wallet. Because Descriptor
+wallets do not support having private keys and watch-only scripts, there may be up to two
+additional wallets created after migration. In addition to a descriptor wallet of the same name,
+there may also be a wallet named `<name>_watchonly` and `<name>_solvables`. `<name>_watchonly`
+contains all of the watchonly scripts. `<name>_solvables` contains any scripts which the wallet
+knows but is not watching the corresponding P2SH scripts.
+
+Given that there is an extremely large number of possible configurations for the scripts that
+Legacy wallets can know about, be watching for, and be able to sign for, `migratewallet` only
+makes a best effort attempt to capture all of these things into Descriptor wallets. There may be
+unforeseen configurations which result in some scripts being excluded. If a migration fails
+unexpectedly or otherwise misses any scripts, please create an issue on GitHub. A backup of the
+original wallet can be found in the wallet directory with the name `<name>-<timestamp>.legacy.bak`.
+
+The backup can be restored using the `restorewallet` command as discussed in the
+[Restoring the Wallet From a Backup](#16-restoring-the-wallet-from-a-backup) section

doc/release-notes-19602.md

@@ -0,0 +1,9 @@
+Wallet
+======
+
+Migrating Legacy Wallets to Descriptor Wallets
+---------------------------------------------
+
+An experimental RPC `migratewallet` has been added to migrate Legacy (non-descriptor) wallets to
+Descriptor wallets. More information about the migration process is available in the
+[documentation](https://github.com/dashpay/dash/blob/master/doc/managing-wallets.md#migrating-legacy-wallets-to-descriptor-wallets).

src/script/descriptor.cpp

@@ -587,7 +587,7 @@ class DescriptorImpl : public Descriptor
         return AddChecksum(ret);
     }
 
-    bool ToPrivateString(const SigningProvider& arg, std::string& out) const override final
+    bool ToPrivateString(const SigningProvider& arg, std::string& out) const override
     {
         bool ret = ToStringHelper(&arg, out, StringType::PRIVATE);
         out = AddChecksum(out);
@@ -677,6 +677,7 @@ class AddressDescriptor final : public DescriptorImpl
         }
     }
     bool IsSingleType() const final { return true; }
+    bool ToPrivateString(const SigningProvider& arg, std::string& out) const final { return false; }
 };
 
 /** A parsed raw(H) descriptor. */
@@ -702,6 +703,7 @@ class RawDescriptor final : public DescriptorImpl
         }
     }
     bool IsSingleType() const final { return true; }
+    bool ToPrivateString(const SigningProvider& arg, std::string& out) const final { return false; }
 };
 
 /** A parsed pk(P) descriptor. */

src/wallet/rpc/wallet.cpp

@@ -1103,6 +1103,74 @@ RPCHelpMan simulaterawtransaction()
     };
 }
 
+static RPCHelpMan migratewallet()
+{
+    return RPCHelpMan{"migratewallet",
+        "EXPERIMENTAL warning: This call may not work as expected and may be changed in future releases\n"
+        "\nMigrate the wallet to a descriptor wallet.\n"
+        "A new wallet backup will need to be made.\n"
+        "\nThe migration process will create a backup of the wallet before migrating. This backup\n"
+        "file will be named <wallet name>-<timestamp>.legacy.bak and can be found in the directory\n"
+        "for this wallet. In the event of an incorrect migration, the backup can be restored using restorewallet."
+        "\nEncrypted wallets must have the passphrase provided as an argument to this call.",
+        {
+            {"wallet_name", RPCArg::Type::STR, RPCArg::DefaultHint{"the wallet name from the RPC endpoint"}, "The name of the wallet to migrate. If provided both here and in the RPC endpoint, the two must be identical."},
+            {"passphrase", RPCArg::Type::STR, RPCArg::Optional::OMITTED, "The wallet passphrase"},
+        },
+        RPCResult{
+            RPCResult::Type::OBJ, "", "",
+            {
+                {RPCResult::Type::STR, "wallet_name", "The name of the primary migrated wallet"},
+                {RPCResult::Type::STR, "watchonly_name", /*optional=*/true, "The name of the migrated wallet containing the watchonly scripts"},
+                {RPCResult::Type::STR, "solvables_name", /*optional=*/true, "The name of the migrated wallet containing solvable but not watched scripts"},
+                {RPCResult::Type::STR, "backup_path", "The location of the backup of the original wallet"},
+            }
+        },
+        RPCExamples{
+            HelpExampleCli("migratewallet", "")
+            + HelpExampleRpc("migratewallet", "")
+        },
+        [&](const RPCHelpMan& self, const JSONRPCRequest& request) -> UniValue
+        {
+            std::string wallet_name;
+            if (GetWalletNameFromJSONRPCRequest(request, wallet_name)) {
+                if (!(request.params[0].isNull() || request.params[0].get_str() == wallet_name)) {
+                    throw JSONRPCError(RPC_INVALID_PARAMETER, "RPC endpoint wallet and wallet_name parameter specify different wallets");
+                }
+            } else {
+                if (request.params[0].isNull()) {
+                    throw JSONRPCError(RPC_INVALID_PARAMETER, "Either RPC endpoint wallet or wallet_name parameter must be provided");
+                }
+                wallet_name = request.params[0].get_str();
+            }
+
+            SecureString wallet_pass;
+            wallet_pass.reserve(100);
+            if (!request.params[1].isNull()) {
+                wallet_pass = std::string_view{request.params[1].get_str()};
+            }
+
+            WalletContext& context = EnsureWalletContext(request.context);
+            util::Result<MigrationResult> res = MigrateLegacyToDescriptor(wallet_name, wallet_pass, context);
+            if (!res) {
+                throw JSONRPCError(RPC_WALLET_ERROR, util::ErrorString(res).original);
+            }
+
+            UniValue r{UniValue::VOBJ};
+            r.pushKV("wallet_name", res->wallet_name);
+            if (res->watchonly_wallet) {
+                r.pushKV("watchonly_name", res->watchonly_wallet->GetName());
+            }
+            if (res->solvables_wallet) {
+                r.pushKV("solvables_name", res->solvables_wallet->GetName());
+            }
+            r.pushKV("backup_path", fs::PathToString(res->backup_path));
+
+            return r;
+        },
+    };
+}
+
 // addresses
 RPCHelpMan getaddressinfo();
 RPCHelpMan getnewaddress();
@@ -1223,6 +1291,7 @@ Span<const CRPCCommand> GetWalletRPCCommands()
         {"wallet", &listwallets},
         {"wallet", &loadwallet},
         {"wallet", &lockunspent},
+        {"wallet", &migratewallet},
         {"wallet", &newkeypool},
         {"wallet", &removeprunedfunds},
         {"wallet", &rescanblockchain},