Merge #21141: wallet: Add new format string placeholders for walletnotify

06e1fb0b170a69996a7ce1ef5203785a7bc6b278 Add new format string placeholders for walletnotify to include relevant block information for transactions (Maayan Keshet)

Pull request description:

  This patch includes two new format placeholders for walletnotify:
  %b - the hash of the block containting the transaction (zeroed if a mempool transaction)
  %h - the height of the block containing the transaction (zero if a mempool transaction)

  I've included test suite changes to check and validate the above functional requirements as well as doc/help description changes.

  **Motivation**
  The walletnotify option is used to be notified of new transactions relevant to the wallet of the node.
  A common usage pattern is to perform afterwards additional RPC calls to determine:
  1. If this is a mempool transaction or not (i.e. are there any confirmations?)
  2. What block was it included in?
  3. Did this transaction was seen before and is now seen again because of a fork?

  All of these questions can be answered with the current features, but the resulting RPC calls may be expensive in a heavily used node. As this information is readily available when calling the walletnotify callback, it makes sense to save expensive round trips by optionally sending this information at that point in time. I can definitely say we would like to use it in Fireblocks, my employer.

  Please let me know of any questions and suggestions.

ACKs for top commit:
  laanwj:
    ACK 06e1fb0b170a69996a7ce1ef5203785a7bc6b278

Tree-SHA512: d2744e2a7a883f9c3a9fd32237110e048c4b6b11fea8221c33d10b74157f65bbc4351211f441e8c1a4af5d5d38e2ba6b1943a7673dc18860c0553d7b41e00775

2 files changed, 9 insertions, 1 deletions

diff --git a/src/wallet/init.cpp b/src/wallet/init.cpp
index f3e24384df..fdeead1fa5 100644
--- a/src/wallet/init.cpp
+++ b/src/wallet/init.cpp
@@ -70,7 +70,7 @@ void WalletInit::AddWalletOptions(ArgsManager& argsman) const
     argsman.AddArg("-walletbroadcast",  strprintf("Make the wallet broadcast transactions (default: %u)", DEFAULT_WALLETBROADCAST), ArgsManager::ALLOW_ANY, OptionsCategory::WALLET);
     argsman.AddArg("-walletdir=<dir>", "Specify directory to hold wallets (default: <datadir>/wallets if it exists, otherwise <datadir>)", ArgsManager::ALLOW_ANY | ArgsManager::NETWORK_ONLY, OptionsCategory::WALLET);
 #if HAVE_SYSTEM
-    argsman.AddArg("-walletnotify=<cmd>", "Execute command when a wallet transaction changes. %s in cmd is replaced by TxID and %w is replaced by wallet name. %w is not currently implemented on windows. On systems where %w is supported, it should NOT be quoted because this would break shell escaping used to invoke the command.", ArgsManager::ALLOW_ANY, OptionsCategory::WALLET);
+    argsman.AddArg("-walletnotify=<cmd>", "Execute command when a wallet transaction changes. %s in cmd is replaced by TxID, %w is replaced by wallet name, %b is replaced by the hash of the block including the transaction (set to 'unconfirmed' if the transaction is not included) and %h is replaced by the block height (-1 if not included). %w is not currently implemented on windows. On systems where %w is supported, it should NOT be quoted because this would break shell escaping used to invoke the command.", ArgsManager::ALLOW_ANY, OptionsCategory::WALLET);
 #endif
     argsman.AddArg("-walletrbf", strprintf("Send transactions with full-RBF opt-in enabled (RPC only, default: %u)", DEFAULT_WALLET_RBF), ArgsManager::ALLOW_ANY, OptionsCategory::WALLET);
 
diff --git a/src/wallet/wallet.cpp b/src/wallet/wallet.cpp
index 58ab124061..ac1b2a4c0a 100644
--- a/src/wallet/wallet.cpp
+++ b/src/wallet/wallet.cpp
@@ -944,6 +944,14 @@ CWalletTx* CWallet::AddToWallet(CTransactionRef tx, const CWalletTx::Confirmatio
     if (!strCmd.empty())
     {
         boost::replace_all(strCmd, "%s", hash.GetHex());
+        if (confirm.status == CWalletTx::Status::CONFIRMED)
+        {
+            boost::replace_all(strCmd, "%b", confirm.hashBlock.GetHex());
+            boost::replace_all(strCmd, "%h", ToString(confirm.block_height));
+        } else {
+            boost::replace_all(strCmd, "%b", "unconfirmed");
+            boost::replace_all(strCmd, "%h", "-1");
+        }
 #ifndef WIN32
         // Substituting the wallet name isn't currently supported on windows
         // because windows shell escaping has not been implemented yet: