Move external signer out of wallet module

This commit moves the ExternalSigner class and RPC methods out of the wallet module.

The enumeratesigners RPC can be used without a wallet since #21417.
With additional modifications external signers could be used without a wallet in general, e.g. via signrawtransaction.

The signerdisplayaddress RPC is ranamed to walletdisplayaddress because it requires wallet context.
A future displayaddress RPC call without wallet context could take a descriptor argument.

This commit fixes a rpc_help.py failure when configured with --disable-wallet.

1 files changed, 45 insertions, 0 deletions

diff --git a/src/wallet/rpcwallet.cpp b/src/wallet/rpcwallet.cpp
index 672ee3e7a4..dc821dc06d 100644
--- a/src/wallet/rpcwallet.cpp
+++ b/src/wallet/rpcwallet.cpp
@@ -4526,6 +4526,48 @@ static RPCHelpMan upgradewallet()
     };
 }
 
+#ifdef ENABLE_EXTERNAL_SIGNER
+static RPCHelpMan walletdisplayaddress()
+{
+    return RPCHelpMan{
+        "walletdisplayaddress",
+        "Display address on an external signer for verification.\n",
+        {
+            {"address",     RPCArg::Type::STR, RPCArg::Optional::NO, /* default_val */ "", "bitcoin address to display"},
+        },
+        RPCResult{
+            RPCResult::Type::OBJ,"","",
+            {
+                {RPCResult::Type::STR, "address", "The address as confirmed by the signer"},
+            }
+        },
+        RPCExamples{""},
+        [](const RPCHelpMan& self, const JSONRPCRequest& request) -> UniValue {
+            std::shared_ptr<CWallet> const wallet = GetWalletForJSONRPCRequest(request);
+            if (!wallet) return NullUniValue;
+            CWallet* const pwallet = wallet.get();
+
+            LOCK(pwallet->cs_wallet);
+
+            CTxDestination dest = DecodeDestination(request.params[0].get_str());
+
+            // Make sure the destination is valid
+            if (!IsValidDestination(dest)) {
+                throw JSONRPCError(RPC_INVALID_ADDRESS_OR_KEY, "Invalid address");
+            }
+
+            if (!pwallet->DisplayAddress(dest)) {
+                throw JSONRPCError(RPC_MISC_ERROR, "Failed to display address");
+            }
+
+            UniValue result(UniValue::VOBJ);
+            result.pushKV("address", request.params[0].get_str());
+            return result;
+        }
+    };
+}
+#endif // ENABLE_EXTERNAL_SIGNER
+
 RPCHelpMan abortrescan();
 RPCHelpMan dumpprivkey();
 RPCHelpMan importprivkey();
@@ -4602,6 +4644,9 @@ static const CRPCCommand commands[] =
     { "wallet",             &unloadwallet,                   },
     { "wallet",             &upgradewallet,                  },
     { "wallet",             &walletcreatefundedpsbt,         },
+#ifdef ENABLE_EXTERNAL_SIGNER
+    { "wallet",             &walletdisplayaddress,           },
+#endif // ENABLE_EXTERNAL_SIGNER
     { "wallet",             &walletlock,                     },
     { "wallet",             &walletpassphrase,               },
     { "wallet",             &walletpassphrasechange,         },