Make get_sn_state_changes admin-only

This call can make the node do a full tx scan for state change
transactions, which can be expensive.  It is currently only used in the
oxend CLI interface, so seems fine to make admin-restricted.

src/daemon/command_parser_executor.cpp

@@ -42,13 +42,23 @@ namespace daemonize {
 namespace log = oxen::log;
 static auto logcat = log::Cat("daemon");
 
+template <typename T>
+constexpr bool is_std_optional = false;
+template <typename T>
+inline constexpr bool is_std_optional<std::optional<T>> = true;
+
 // Consumes an argument from the given list, if present, parsing it into `var`.
 // Returns false upon parse failure, true otherwise.
 template <typename T>
-static bool parse_if_present(std::forward_list<std::string> &list, T &var, const char *name)
+static bool parse_if_present(std::forward_list<std::string>& list, T& var, const char* name)
 {
   if (list.empty()) return true;
-  if (epee::string_tools::get_xtype_from_string(var, list.front()))
+  bool good = false;
+  if constexpr (is_std_optional<T>)
+    good = epee::string_tools::get_xtype_from_string(var.emplace(), list.front());
+  else
+    good = epee::string_tools::get_xtype_from_string(var, list.front());
+  if (good)
   {
     list.pop_front();
     return true;

src/rpc/core_rpc_server.cpp

@@ -2760,22 +2760,15 @@ namespace cryptonote::rpc {
     std::vector<block_pair_t> blocks;
 
     const auto& db = m_core.get_blockchain_storage();
-    const uint64_t current_height = db.get_current_blockchain_height();
 
-    uint64_t end_height;
-    uint64_t start_height = get_sn_state_changes.request.start_height;
-    if (get_sn_state_changes.request.end_height == GET_SN_STATE_CHANGES::HEIGHT_SENTINEL_VALUE) {
-      // current height is the block being mined, so exclude it from the results
-      end_height = current_height - 1;
-    } else {
-      end_height = get_sn_state_changes.request.end_height;
-    }
+    auto start_height = get_sn_state_changes.request.start_height;
+    auto end_height = get_sn_state_changes.request.end_height.value_or(db.get_current_blockchain_height() - 1);
 
     if (end_height < start_height)
       throw rpc_error{ERROR_WRONG_PARAM, "The provided end_height needs to be higher than start_height"};
 
     if (!db.get_blocks(start_height, end_height - start_height + 1, blocks))
-      throw rpc_error{ERROR_INTERNAL, "Could not query block at requested height: " + std::to_string(start_height)};
+      throw rpc_error{ERROR_INTERNAL, "Could not query blocks at requested height {}"_format(start_height)};
 
     get_sn_state_changes.response["start_height"] = start_height;
     get_sn_state_changes.response["end_height"] = end_height;

src/rpc/core_rpc_server_command_parser.cpp

@@ -278,7 +278,7 @@ namespace cryptonote::rpc {
   void parse_request(GET_SN_STATE_CHANGES& get_sn_state_changes, rpc_input in) {
     get_values(in,
         "end_height", get_sn_state_changes.request.end_height,
-        "start_height", get_sn_state_changes.request.start_height);
+        "start_height", required{get_sn_state_changes.request.start_height});
   }
 
   void parse_request(REPORT_PEER_STATUS& report_peer_status, rpc_input in) {

src/rpc/core_rpc_server_commands_defs.h

@@ -1988,15 +1988,15 @@ namespace cryptonote::rpc {
     } request;
   };
 
-  /// Query hardcoded/service node checkpoints stored for the blockchain. Omit all arguments to
-  /// retrieve the latest "count" checkpoints.
+  /// Query recent service node state changes processed on the blockchain.
   ///
   /// Inputs:
   /// 
-  /// - \p start_height The starting block's height.
-  /// - \p end_height The ending block's height.
+  /// - \p start_height Returns counts starting from this block height.  Required.
+  /// - \p end_height Optional: returns count ending at this block height; if omitted, counts to the
+  ///   current height.
   ///
-  /// Output values available from a public RPC endpoint:
+  /// Output values available from a private/admin RPC endpoint:
   ///
   /// - \p status Generic RPC error code. "OK" is the success value.
   /// - \p total_deregister
@@ -2006,15 +2006,14 @@ namespace cryptonote::rpc {
   /// - \p total_unlock
   /// - \p start_height
   /// - \p end_height
-  struct GET_SN_STATE_CHANGES : PUBLIC
+  struct GET_SN_STATE_CHANGES : RPC_COMMAND
   {
     static constexpr auto names() { return NAMES("get_service_nodes_state_changes"); }
 
-    static constexpr uint64_t HEIGHT_SENTINEL_VALUE = std::numeric_limits<uint64_t>::max() - 1;
     struct request_parameters
     {
       uint64_t start_height;
-      uint64_t end_height;   // Optional: If omitted, the tally runs until the current block
+      std::optional<uint64_t> end_height;
     } request;
   };