rpc: require second argument only for scantxoutset start action

The second argument of scanobjects is only required for the start action.
Stop and abort actions do not need this.

1 files changed, 6 insertions, 1 deletions

diff --git a/src/rpc/blockchain.cpp b/src/rpc/blockchain.cpp
index 946152d9aa..caec316cd4 100644
--- a/src/rpc/blockchain.cpp
+++ b/src/rpc/blockchain.cpp
@@ -2055,7 +2055,7 @@ UniValue scantxoutset(const JSONRPCRequest& request)
             "                                      \"start\" for starting a scan\n"
             "                                      \"abort\" for aborting the current scan (returns true when abort was successful)\n"
             "                                      \"status\" for progress report (in %) of the current scan"},
-                    {"scanobjects", RPCArg::Type::ARR, RPCArg::Optional::NO, "Array of scan objects\n"
+                    {"scanobjects", RPCArg::Type::ARR, RPCArg::Optional::OMITTED, "Array of scan objects. Required for \"start\" action\n"
             "                                  Every scan object is either a string descriptor or an object:",
                         {
                             {"descriptor", RPCArg::Type::STR, RPCArg::Optional::OMITTED, "An output descriptor"},
@@ -2115,6 +2115,11 @@ UniValue scantxoutset(const JSONRPCRequest& request)
         if (!reserver.reserve()) {
             throw JSONRPCError(RPC_INVALID_PARAMETER, "Scan already in progress, use action \"abort\" or \"status\"");
         }
+
+        if (request.params.size() < 2) {
+            throw JSONRPCError(RPC_MISC_ERROR, "scanobjects argument is required for the start action");
+        }
+
         std::set<CScript> needles;
         std::map<CScript, std::string> descriptors;
         CAmount total_in = 0;