node_rpc_proxy: allow caching daemon RPC version

src/wallet/node_rpc_proxy.cpp

@@ -45,6 +45,7 @@ NodeRPCProxy::NodeRPCProxy(epee::net_utils::http::http_simple_client &http_clien
   , m_dynamic_per_kb_fee_estimate(0)
   , m_dynamic_per_kb_fee_estimate_cached_height(0)
   , m_dynamic_per_kb_fee_estimate_grace_blocks(0)
+  , m_rpc_version(0)
 {}
 
 void NodeRPCProxy::invalidate()
@@ -56,6 +57,29 @@ void NodeRPCProxy::invalidate()
   m_dynamic_per_kb_fee_estimate = 0;
   m_dynamic_per_kb_fee_estimate_cached_height = 0;
   m_dynamic_per_kb_fee_estimate_grace_blocks = 0;
+  m_rpc_version = 0;
+}
+
+boost::optional<std::string> NodeRPCProxy::get_rpc_version(uint32_t &rpc_version)
+{
+  const time_t now = time(NULL);
+  if (m_rpc_version == 0)
+  {
+    epee::json_rpc::request<cryptonote::COMMAND_RPC_GET_VERSION::request> req_t = AUTO_VAL_INIT(req_t);
+    epee::json_rpc::response<cryptonote::COMMAND_RPC_GET_VERSION::response, std::string> resp_t = AUTO_VAL_INIT(resp_t);
+    req_t.jsonrpc = "2.0";
+    req_t.id = epee::serialization::storage_entry(0);
+    req_t.method = "get_version";
+    m_daemon_rpc_mutex.lock();
+    bool r = net_utils::invoke_http_json("/json_rpc", req_t, resp_t, m_http_client);
+    m_daemon_rpc_mutex.unlock();
+    CHECK_AND_ASSERT_MES(r, std::string(), "Failed to connect to daemon");
+    CHECK_AND_ASSERT_MES(resp_t.result.status != CORE_RPC_STATUS_BUSY, resp_t.result.status, "Failed to connect to daemon");
+    CHECK_AND_ASSERT_MES(resp_t.result.status == CORE_RPC_STATUS_OK, resp_t.result.status, "Failed to get daemon RPC version");
+    m_rpc_version = resp_t.result.version;
+  }
+  rpc_version = m_rpc_version;
+  return boost::optional<std::string>();
 }
 
 boost::optional<std::string> NodeRPCProxy::get_height(uint64_t &height)

src/wallet/node_rpc_proxy.h

@@ -43,6 +43,7 @@ public:
 
   void invalidate();
 
+  boost::optional<std::string> get_rpc_version(uint32_t &version);
   boost::optional<std::string> get_height(uint64_t &height);
   void set_height(uint64_t h);
   boost::optional<std::string> get_earliest_height(uint8_t version, uint64_t &earliest_height);
@@ -58,6 +59,7 @@ private:
   uint64_t m_dynamic_per_kb_fee_estimate;
   uint64_t m_dynamic_per_kb_fee_estimate_cached_height;
   uint64_t m_dynamic_per_kb_fee_estimate_grace_blocks;
+  uint32_t m_rpc_version;
 };
 
 }