Merge bitcoin/bitcoin#26186: rpc: Sanitize label name in various RPCs with tests

65e78bda7cd23ad7b6ede63c6bf5ffe6f552c71d test: Invalid label name coverage (Aurèle Oulès)
552b51e682b5a52d9e2fbe64e44e623451692bd3 refactor: Add sanity checks in LabelFromValue (Aurèle Oulès)
67e7ba8e1aea58fc864f9bb1fc0e56b70777185e rpc: Sanitize label name in various RPCs (Aurèle Oulès)

Pull request description:

  The following RPCs did not sanitize the optional label name:
  - importprivkey
  - importaddress
  - importpubkey
  - importmulti
  - importdescriptors
  - listsinceblock

  Thus is was possible to import an address with a label `*` which should not be possible.
  The wildcard label is used for backwards compatibility in the `listtransactions` rpc.
  I added test coverage for these RPCs.

ACKs for top commit:
  ajtowns:
    ACK 65e78bda7cd23ad7b6ede63c6bf5ffe6f552c71d
  achow101:
    ACK 65e78bda7cd23ad7b6ede63c6bf5ffe6f552c71d
  furszy:
    diff ACK 65e78bd
  stickies-v:
    re-ACK 65e78bda7cd23ad7b6ede63c6bf5ffe6f552c71d
  theStack:
    re-ACK 65e78bda7cd23ad7b6ede63c6bf5ffe6f552c71d

Tree-SHA512: ad99f2824d4cfae352166b76da4ca0069b7c2eccf81aaa0654be25bbb3c6e5d6b005d93960f3f4154155f80e12be2d0cebd5529922ae3d2a36ee4eed82440b31

1 files changed, 3 insertions, 4 deletions

diff --git a/src/wallet/rpc/transactions.cpp b/src/wallet/rpc/transactions.cpp
index c257af13c4..f571f8bcb2 100644
--- a/src/wallet/rpc/transactions.cpp
+++ b/src/wallet/rpc/transactions.cpp
@@ -486,7 +486,7 @@ RPCHelpMan listtransactions()
 
     std::optional<std::string> filter_label;
     if (!request.params[0].isNull() && request.params[0].get_str() != "*") {
-        filter_label = request.params[0].get_str();
+        filter_label.emplace(LabelFromValue(request.params[0]));
         if (filter_label.value().empty()) {
             throw JSONRPCError(RPC_INVALID_PARAMETER, "Label argument must be a valid label name or \"*\".");
         }
@@ -634,10 +634,9 @@ RPCHelpMan listsinceblock()
     bool include_removed = (request.params[3].isNull() || request.params[3].get_bool());
     bool include_change = (!request.params[4].isNull() && request.params[4].get_bool());
 
+    // Only set it if 'label' was provided.
     std::optional<std::string> filter_label;
-    if (!request.params[5].isNull()) {
-        filter_label = request.params[5].get_str();
-    }
+    if (!request.params[5].isNull()) filter_label.emplace(LabelFromValue(request.params[5]));
 
     int depth = height ? wallet.GetLastBlockHeight() + 1 - *height : -1;