Merge #18466: rpc: fix invalid parameter error codes for {sign,verify}message RPCs

a5cfb40e27bd281354bd0d14d91f83efb6bfce9f doc: release note for changed {sign,verify}message error codes (Sebastian Falbesoner)
9e399b9b2d386b28c0c0ff59fc75d31dbec31d9c test: check parameter validity in rpc_signmessage.py (Sebastian Falbesoner)
e62f0c71f10def124b1c1219d790cef246a32c3e rpc: fix {sign,message}verify RPC errors for invalid address/signature (Sebastian Falbesoner)

Pull request description:

  RPCs that accept address parameters usually return the intended error code `RPC_INVALID_ADDRESS_OR_KEY` (-5) if a passed address is invalid. The two exceptions to the rule are `signmessage` and `verifymessage`, which return `RPC_TYPE_ERROR` (-3) in this case instead. Oddly enough `verifymessage` returns `RPC_INVALID_ADDRESS_OR_KEY` when the _signature_ was malformed, where `RPC_TYPE_ERROR` would be more approriate.

  This PR fixes these inaccuracies and as well adds tests to `rpc_signmessage.py` that check the parameter validity and error codes for the related RPCs `signmessagewithprivkey`, `signmessage` and `verifymessage`.

  master branch:
  ```
  $ ./bitcoin-cli signmessage invalid_addr message
  error code: -3
  error message:
  Invalid address
  $ ./bitcoin-cli verifymessage invalid_addr dummy_sig message
  error code: -3
  error message:
  Invalid address
  $ ./bitcoin-cli verifymessage 12c6DSiU4Rq3P4ZxziKxzrL5LmMBrzjrJX invalid_sig message
  error code: -5
  error message:
  Malformed base64 encoding
  ```
  PR branch:
  ```
  $ ./bitcoin-cli signmessage invalid_addr message
  error code: -5
  error message:
  Invalid address
  $ ./bitcoin-cli verifymessage invalid_addr dummy_sig message
  error code: -5
  error message:
  Invalid address
  $ ./bitcoin-cli verifymessage 12c6DSiU4Rq3P4ZxziKxzrL5LmMBrzjrJX invalid_sig message
  error code: -3
  error message:
  Malformed base64 encoding
  ```

ACKs for top commit:
  laanwj:
    Code review ACK a5cfb40e27bd281354bd0d14d91f83efb6bfce9f
  meshcollider:
    utACK a5cfb40e27bd281354bd0d14d91f83efb6bfce9f

Tree-SHA512: bae0c4595a2603cea66090f6033785601837b45fd853052312b3a39d8520566c581994b68f693dd247c22586c638c3b7689c849085cce548cc36b9bf0e119d2d

4 files changed, 34 insertions, 4 deletions

diff --git a/doc/release-notes-18466.md b/doc/release-notes-18466.md
new file mode 100644
index 0000000000..e46d5064a3
--- /dev/null
+++ b/doc/release-notes-18466.md
@@ -0,0 +1,10 @@
+Low-level RPC changes
+---------------------
+
+- Error codes have been updated to be more accurate for the following error cases (#18466):
+  - `signmessage` now returns RPC_INVALID_ADDRESS_OR_KEY (-5) if the
+    passed address is invalid. Previously returned RPC_TYPE_ERROR (-3).
+  - `verifymessage` now returns RPC_INVALID_ADDRESS_OR_KEY (-5) if the
+    passed address is invalid. Previously returned RPC_TYPE_ERROR (-3).
+  - `verifymessage` now returns RPC_TYPE_ERROR (-3) if the passed signature
+    is malformed. Previously returned RPC_INVALID_ADDRESS_OR_KEY (-5).
diff --git a/src/rpc/misc.cpp b/src/rpc/misc.cpp
index 38a0bddddb..143be1274e 100644
--- a/src/rpc/misc.cpp
+++ b/src/rpc/misc.cpp
@@ -305,11 +305,11 @@ static RPCHelpMan verifymessage()
 
     switch (MessageVerify(strAddress, strSign, strMessage)) {
     case MessageVerificationResult::ERR_INVALID_ADDRESS:
-        throw JSONRPCError(RPC_TYPE_ERROR, "Invalid address");
+        throw JSONRPCError(RPC_INVALID_ADDRESS_OR_KEY, "Invalid address");
     case MessageVerificationResult::ERR_ADDRESS_NO_KEY:
         throw JSONRPCError(RPC_TYPE_ERROR, "Address does not refer to key");
     case MessageVerificationResult::ERR_MALFORMED_SIGNATURE:
-        throw JSONRPCError(RPC_INVALID_ADDRESS_OR_KEY, "Malformed base64 encoding");
+        throw JSONRPCError(RPC_TYPE_ERROR, "Malformed base64 encoding");
     case MessageVerificationResult::ERR_PUBKEY_NOT_RECOVERED:
     case MessageVerificationResult::ERR_NOT_SIGNED:
         return false;
diff --git a/src/wallet/rpcwallet.cpp b/src/wallet/rpcwallet.cpp
index bfc42ac1b0..6d6cdedb2b 100644
--- a/src/wallet/rpcwallet.cpp
+++ b/src/wallet/rpcwallet.cpp
@@ -630,7 +630,7 @@ static RPCHelpMan signmessage()
 
     CTxDestination dest = DecodeDestination(strAddress);
     if (!IsValidDestination(dest)) {
-        throw JSONRPCError(RPC_TYPE_ERROR, "Invalid address");
+        throw JSONRPCError(RPC_INVALID_ADDRESS_OR_KEY, "Invalid address");
     }
 
     const PKHash* pkhash = std::get_if<PKHash>(&dest);
diff --git a/test/functional/rpc_signmessage.py b/test/functional/rpc_signmessage.py
index 0cb3ce4215..1c71732a61 100755
--- a/test/functional/rpc_signmessage.py
+++ b/test/functional/rpc_signmessage.py
@@ -5,7 +5,10 @@
 """Test RPC commands for signing and verifying messages."""
 
 from test_framework.test_framework import BitcoinTestFramework
-from test_framework.util import assert_equal
+from test_framework.util import (
+    assert_equal,
+    assert_raises_rpc_error,
+)
 
 class SignMessagesTest(BitcoinTestFramework):
     def set_test_params(self):
@@ -38,5 +41,22 @@ class SignMessagesTest(BitcoinTestFramework):
         assert not self.nodes[0].verifymessage(other_address, signature, message)
         assert not self.nodes[0].verifymessage(address, other_signature, message)
 
+        self.log.info('test parameter validity and error codes')
+        # signmessage(withprivkey) have two required parameters
+        for num_params in [0, 1, 3, 4, 5]:
+            param_list = ["dummy"]*num_params
+            assert_raises_rpc_error(-1, "signmessagewithprivkey", self.nodes[0].signmessagewithprivkey, *param_list)
+            assert_raises_rpc_error(-1, "signmessage", self.nodes[0].signmessage, *param_list)
+        # verifymessage has three required parameters
+        for num_params in [0, 1, 2, 4, 5]:
+            param_list = ["dummy"]*num_params
+            assert_raises_rpc_error(-1, "verifymessage", self.nodes[0].verifymessage, *param_list)
+        # invalid key or address provided
+        assert_raises_rpc_error(-5, "Invalid private key", self.nodes[0].signmessagewithprivkey, "invalid_key", message)
+        assert_raises_rpc_error(-5, "Invalid address", self.nodes[0].signmessage, "invalid_addr", message)
+        assert_raises_rpc_error(-5, "Invalid address", self.nodes[0].verifymessage, "invalid_addr", signature, message)
+        # malformed signature provided
+        assert_raises_rpc_error(-3, "Malformed base64 encoding", self.nodes[0].verifymessage, self.nodes[0].getnewaddress(), "invalid_sig", message)
+
 if __name__ == '__main__':
     SignMessagesTest().main()