multiprocess: Add bitcoin-wallet -ipcconnect option

Add `-ipcconnect` option to `bitcoin-wallet` to allow connecting to a bitcoin
node process over IPC.  The `bitcoin-wallet` tool doesn't really do anything with its
connection to the node yet, but it could potentially run or serve RPCs that
require being online.

Example usage:

    src/bitcoin-node -regtest -debug -ipcbind=unix
    src/bitcoin-wallet -regtest -ipcconnect=unix info

src/bitcoin-wallet.cpp

@@ -10,7 +10,9 @@
 #include <common/args.h>
 #include <common/system.h>
 #include <compat/compat.h>
+#include <interfaces/chain.h>
 #include <interfaces/init.h>
+#include <interfaces/ipc.h>
 #include <key.h>
 #include <logging.h>
 #include <pubkey.h>
@@ -28,7 +30,7 @@ using util::Join;
 
 const std::function<std::string(const char*)> G_TRANSLATION_FUN = nullptr;
 
-static void SetupWalletToolArgs(ArgsManager& argsman)
+static void SetupWalletToolArgs(ArgsManager& argsman, bool can_connect_ipc)
 {
     SetupHelpOptions(argsman);
     SetupChainParamsBaseOptions(argsman);
@@ -43,6 +45,9 @@ static void SetupWalletToolArgs(ArgsManager& argsman)
     argsman.AddArg("-format=<format>", "The format of the wallet file to create. Either \"bdb\" or \"sqlite\". Only used with 'createfromdump'", ArgsManager::ALLOW_ANY, OptionsCategory::OPTIONS);
     argsman.AddArg("-printtoconsole", "Send trace/debug info to console (default: 1 when no -debug is true, 0 otherwise).", ArgsManager::ALLOW_ANY, OptionsCategory::DEBUG_TEST);
     argsman.AddArg("-withinternalbdb", "Use the internal Berkeley DB parser when dumping a Berkeley DB wallet file (default: false)", ArgsManager::ALLOW_ANY, OptionsCategory::DEBUG_TEST);
+    if (can_connect_ipc) {
+        argsman.AddArg("-ipcconnect=<address>", "Connect to bitcoin-node process in the background to perform online operations. Valid <address> values are 'auto' to try connecting to default socket in <datadir>/sockets/node.sock, but proceed offline if it isn't available, 'unix' to connect to the default socket and fail if it isn't available, 'unix:<socket path>' to connect to a socket at a nonstandard path, and -noipcconnect to not connect. Default value: auto", ArgsManager::ALLOW_ANY, OptionsCategory::IPC);
+    }
 
     argsman.AddCommand("info", "Get wallet info");
     argsman.AddCommand("create", "Create new wallet file");
@@ -53,7 +58,6 @@ static void SetupWalletToolArgs(ArgsManager& argsman)
 
 static std::optional<int> WalletAppInit(ArgsManager& args, int argc, char* argv[])
 {
-    SetupWalletToolArgs(args);
     std::string error_message;
     if (!args.ParseParameters(argc, argv, error_message)) {
         tfm::format(std::cerr, "Error parsing command line arguments: %s\n", error_message);
@@ -112,6 +116,7 @@ MAIN_FUNCTION
     SetupEnvironment();
     RandomInit();
     try {
+        SetupWalletToolArgs(args, init->canConnectIpc());
         if (const auto maybe_exit{WalletAppInit(args, argc, argv)}) return *maybe_exit;
     } catch (const std::exception& e) {
         PrintExceptionContinue(&e, "WalletAppInit()");
@@ -132,7 +137,18 @@ MAIN_FUNCTION
     }
 
     ECC_Context ecc_context{};
-    if (!wallet::WalletTool::ExecuteWalletToolFunc(args, command->command)) {
+
+    std::unique_ptr<interfaces::Chain> chain;
+    if (interfaces::Ipc* ipc = init->ipc()) {
+        std::string address = args.GetArg("-ipcconnect", "auto");
+        if (auto init = ipc->connectAddress(address)) {
+            tfm::format(std::cout, "Connected to IPC address %s\n", address);
+            chain = init->makeChain();
+            ipc->addCleanup(*chain, [init = init.release()] { delete init; });
+        }
+    }
+
+    if (!wallet::WalletTool::ExecuteWalletToolFunc(args, chain.get(), command->command)) {
         return EXIT_FAILURE;
     }
     return EXIT_SUCCESS;

src/init/bitcoin-wallet-ipc.cpp

@@ -72,6 +72,7 @@ class BitcoinWalletInit : public interfaces::Init
         return MakeWalletLoader(chain, gArgs);
     }
     interfaces::Ipc* ipc() override { return m_ipc.get(); }
+    bool canConnectIpc() override { return true; }
     std::unique_ptr<interfaces::Ipc> m_ipc;
     std::optional<kernel::Context> m_kernel;
     std::optional<ECC_Context> m_ecc_context;

src/interfaces/init.h

@@ -37,6 +37,7 @@ class Init
     virtual std::unique_ptr<WalletLoader> makeWalletLoader(Chain& chain) { return nullptr; }
     virtual std::unique_ptr<Echo> makeEcho() { return nullptr; }
     virtual Ipc* ipc() { return nullptr; }
+    virtual bool canConnectIpc() { return false; }
     virtual bool canListenIpc() { return false; }
 };
 

src/wallet/wallettool.cpp

@@ -45,7 +45,7 @@ static void WalletCreate(CWallet* wallet_instance, uint64_t wallet_creation_flag
     wallet_instance->TopUpKeyPool();
 }
 
-static std::shared_ptr<CWallet> MakeWallet(const std::string& name, const fs::path& path, DatabaseOptions options)
+static std::shared_ptr<CWallet> MakeWallet(const std::string& name, const fs::path& path, DatabaseOptions options, interfaces::Chain* chain)
 {
     DatabaseStatus status;
     bilingual_str error;
@@ -55,8 +55,7 @@ static std::shared_ptr<CWallet> MakeWallet(const std::string& name, const fs::pa
         return nullptr;
     }
 
-    // dummy chain interface
-    std::shared_ptr<CWallet> wallet_instance{new CWallet(/*chain=*/nullptr, name, std::move(database)), WalletToolReleaseWallet};
+    std::shared_ptr<CWallet> wallet_instance{new CWallet(chain, name, std::move(database)), WalletToolReleaseWallet};
     DBErrors load_wallet_ret;
     try {
         load_wallet_ret = wallet_instance->LoadWallet();
@@ -110,7 +109,7 @@ static void WalletShowInfo(CWallet* wallet_instance)
     tfm::format(std::cout, "Address Book: %zu\n", wallet_instance->m_address_book.size());
 }
 
-bool ExecuteWalletToolFunc(const ArgsManager& args, const std::string& command)
+bool ExecuteWalletToolFunc(const ArgsManager& args, interfaces::Chain* chain, const std::string& command)
 {
     if (args.IsArgSet("-format") && command != "createfromdump") {
         tfm::format(std::cerr, "The -format option can only be used with the \"createfromdump\" command.\n");
@@ -156,7 +155,7 @@ bool ExecuteWalletToolFunc(const ArgsManager& args, const std::string& command)
             options.require_format = DatabaseFormat::SQLITE;
         }
 
-        const std::shared_ptr<CWallet> wallet_instance = MakeWallet(name, path, options);
+        const std::shared_ptr<CWallet> wallet_instance = MakeWallet(name, path, options, chain);
         if (wallet_instance) {
             WalletShowInfo(wallet_instance.get());
             wallet_instance->Close();
@@ -165,7 +164,7 @@ bool ExecuteWalletToolFunc(const ArgsManager& args, const std::string& command)
         DatabaseOptions options;
         ReadDatabaseArgs(args, options);
         options.require_existing = true;
-        const std::shared_ptr<CWallet> wallet_instance = MakeWallet(name, path, options);
+        const std::shared_ptr<CWallet> wallet_instance = MakeWallet(name, path, options, chain);
         if (!wallet_instance) return false;
         WalletShowInfo(wallet_instance.get());
         wallet_instance->Close();

src/wallet/wallettool.h

@@ -9,10 +9,14 @@
 
 class ArgsManager;
 
+namespace interfaces {
+class Chain;
+} // namespace interfaces
+
 namespace wallet {
 namespace WalletTool {
 
-bool ExecuteWalletToolFunc(const ArgsManager& args, const std::string& command);
+bool ExecuteWalletToolFunc(const ArgsManager& args, interfaces::Chain* chain, const std::string& command);
 
 } // namespace WalletTool
 } // namespace wallet