rpc: signerdisplayaddress

src/wallet/external_signer.cpp

@@ -55,6 +55,11 @@ bool ExternalSigner::Enumerate(const std::string& command, std::vector<ExternalS
     return true;
 }
 
+UniValue ExternalSigner::DisplayAddress(const std::string& descriptor) const
+{
+    return RunCommandParseJSON(m_command + " --fingerprint \"" + m_fingerprint + "\"" + NetworkArg() + " displayaddress --desc \"" + descriptor + "\"");
+}
+
 UniValue ExternalSigner::GetDescriptors(int account)
 {
     return RunCommandParseJSON(m_command + " --fingerprint \"" + m_fingerprint + "\"" + NetworkArg() + " getdescriptors --account " + strprintf("%d", account));

src/wallet/external_signer.h

@@ -49,6 +49,11 @@ public:
     //! @param[out] success     Boolean
     static bool Enumerate(const std::string& command, std::vector<ExternalSigner>& signers, std::string chain, bool ignore_errors = false);
 
+    //! Display address on the device. Calls `<command> displayaddress --desc <descriptor>`.
+    //! @param[in] descriptor Descriptor specifying which address to display.
+    //!            Must include a public key or xpub, as well as key origin.
+    UniValue DisplayAddress(const std::string& descriptor) const;
+
     //! Get receive and change Descriptor(s) from device for a given account.
     //! Calls `<command> getdescriptors --account <account>`
     //! @param[in] account  which BIP32 account to use (e.g. `m/44'/0'/account'`)

src/wallet/external_signer_scriptpubkeyman.cpp

@@ -43,4 +43,39 @@ ExternalSigner ExternalSignerScriptPubKeyMan::GetExternalSigner() {
     return signers[0];
 }
 
+bool ExternalSignerScriptPubKeyMan::DisplayAddress(const CScript scriptPubKey, const ExternalSigner &signer) const
+{
+    // TODO: avoid the need to infer a descriptor from inside a descriptor wallet
+    auto provider = GetSolvingProvider(scriptPubKey);
+    auto descriptor = InferDescriptor(scriptPubKey, *provider);
+
+    signer.DisplayAddress(descriptor->ToString());
+    // TODO inspect result
+    return true;
+}
+
+// If sign is true, transaction must previously have been filled
+TransactionError ExternalSignerScriptPubKeyMan::FillPSBT(PartiallySignedTransaction& psbt, int sighash_type, bool sign, bool bip32derivs, int* n_signed) const
+{
+    if (!sign) {
+        return DescriptorScriptPubKeyMan::FillPSBT(psbt, sighash_type, false, bip32derivs, n_signed);
+    }
+
+    // Already complete if every input is now signed
+    bool complete = true;
+    for (const auto& input : psbt.inputs) {
+        // TODO: for multisig wallets, we should only care if all _our_ inputs are signed
+        complete &= PSBTInputSigned(input);
+    }
+    if (complete) return TransactionError::OK;
+
+    std::string strFailReason;
+    if(!GetExternalSigner().SignTransaction(psbt, strFailReason)) {
+        tfm::format(std::cerr, "Failed to sign: %s\n", strFailReason);
+        return TransactionError::EXTERNAL_SIGNER_FAILED;
+    }
+    FinalizePSBT(psbt); // This won't work in a multisig setup
+    return TransactionError::OK;
+}
+
 #endif

src/wallet/external_signer_scriptpubkeyman.h

@@ -25,6 +25,7 @@ class ExternalSignerScriptPubKeyMan : public DescriptorScriptPubKeyMan
 
   static ExternalSigner GetExternalSigner();
 
+  bool DisplayAddress(const CScript scriptPubKey, const ExternalSigner &signer) const;
 };
 #endif
 

src/wallet/rpcsigner.cpp

@@ -3,6 +3,7 @@
 // file COPYING or http://www.opensource.org/licenses/mit-license.php.
 
 #include <chainparamsbase.h>
+#include <key_io.h>
 #include <rpc/server.h>
 #include <rpc/util.h>
 #include <util/strencodings.h>
@@ -57,6 +58,41 @@ static RPCHelpMan enumeratesigners()
     };
 }
 
+static RPCHelpMan signerdisplayaddress()
+{
+    return RPCHelpMan{
+        "signerdisplayaddress",
+        "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::NONE,"",""},
+        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_WALLET_ERROR, "Failed to display address");
+            }
+
+            UniValue result(UniValue::VOBJ);
+            result.pushKV("address", request.params[0].get_str());
+            return result;
+        }
+    };
+}
+
 Span<const CRPCCommand> GetSignerRPCCommands()
 {
 
@@ -65,6 +101,7 @@ static const CRPCCommand commands[] =
 { // category              actor (function)
   // --------------------- ------------------------
   { "signer",              &enumeratesigners,      },
+  { "signer",              &signerdisplayaddress,  },
 };
 // clang-format on
     return MakeSpan(commands);

src/wallet/wallet.cpp

@@ -3587,6 +3587,25 @@ ExternalSigner CWallet::GetExternalSigner()
 }
 #endif
 
+bool CWallet::DisplayAddress(const CTxDestination& dest)
+{
+#ifdef ENABLE_EXTERNAL_SIGNER
+    CScript scriptPubKey = GetScriptForDestination(dest);
+    const auto spk_man = GetScriptPubKeyMan(scriptPubKey);
+    if (spk_man == nullptr) {
+        return false;
+    }
+    auto signer_spk_man = dynamic_cast<ExternalSignerScriptPubKeyMan*>(spk_man);
+    if (signer_spk_man == nullptr) {
+        return false;
+    }
+    ExternalSigner signer = GetExternalSigner(); // TODO: move signer in spk_man
+    return signer_spk_man->DisplayAddress(scriptPubKey, signer);
+#else
+    return false;
+#endif
+}
+
 void CWallet::LockCoin(const COutPoint& output)
 {
     AssertLockHeld(cs_wallet);

src/wallet/wallet.h

@@ -842,6 +842,9 @@ public:
 #ifdef ENABLE_EXTERNAL_SIGNER
     ExternalSigner GetExternalSigner() EXCLUSIVE_LOCKS_REQUIRED(cs_wallet);
 #endif
+    /** Display address on an external signer. Returns false if external signer support is not compiled */
+    bool DisplayAddress(const CTxDestination& dest) EXCLUSIVE_LOCKS_REQUIRED(cs_wallet);
+
     bool IsLockedCoin(uint256 hash, unsigned int n) const EXCLUSIVE_LOCKS_REQUIRED(cs_wallet);
     void LockCoin(const COutPoint& output) EXCLUSIVE_LOCKS_REQUIRED(cs_wallet);
     void UnlockCoin(const COutPoint& output) EXCLUSIVE_LOCKS_REQUIRED(cs_wallet);

test/functional/mocks/signer.py

@@ -37,6 +37,20 @@ def getdescriptors(args):
     }))
 
 
+def displayaddress(args):
+    # Several descriptor formats are acceptable, so allowing for potential
+    # changes to InferDescriptor:
+    if args.fingerprint != "00000001":
+        return sys.stdout.write(json.dumps({"error": "Unexpected fingerprint", "fingerprint": args.fingerprint}))
+
+    expected_desc = [
+        "wpkh([00000001/84'/1'/0'/0/0]02c97dc3f4420402e01a113984311bf4a1b8de376cac0bdcfaf1b3ac81f13433c7)#0yneg42r"
+    ]
+    if args.desc not in expected_desc:
+        return sys.stdout.write(json.dumps({"error": "Unexpected descriptor", "desc": args.desc}))
+
+    return sys.stdout.write(json.dumps({"address": "bcrt1qm90ugl4d48jv8n6e5t9ln6t9zlpm5th68x4f8g"}))
+
 parser = argparse.ArgumentParser(prog='./signer.py', description='External signer mock')
 parser.add_argument('--fingerprint')
 parser.add_argument('--chain', default='main')
@@ -51,6 +65,10 @@ parser_getdescriptors = subparsers.add_parser('getdescriptors')
 parser_getdescriptors.set_defaults(func=getdescriptors)
 parser_getdescriptors.add_argument('--account', metavar='account')
 
+parser_displayaddress = subparsers.add_parser('displayaddress', help='display address on signer')
+parser_displayaddress.add_argument('--desc', metavar='desc')
+parser_displayaddress.set_defaults(func=displayaddress)
+
 args = parser.parse_args()
 
 perform_pre_checks()

test/functional/wallet_signer.py

@@ -123,5 +123,16 @@ class SignerTest(BitcoinTestFramework):
         assert_equal(address_info['ismine'], True)
         assert_equal(address_info['hdkeypath'], "m/44'/1'/0'/0/0")
 
+        self.log.info('Test signerdisplayaddress')
+        result = hww.signerdisplayaddress(address1)
+        assert_equal(result, {"address": address1})
+
+        # Handle error thrown by script
+        self.set_mock_result(self.nodes[1], "2")
+        assert_raises_rpc_error(-1, 'RunCommandParseJSON error',
+            hww.signerdisplayaddress, address1
+        )
+        self.clear_mock_result(self.nodes[1])
+
 if __name__ == '__main__':
     SignerTest().main()