added handshake for dos protection

repertory/librepertory/include/comm/packet/packet_client.hpp

@@ -57,6 +57,7 @@ private:
       resolve_results_;
   std::mutex clients_mutex_;
   std::vector<std::shared_ptr<client>> clients_;
+  std::vector<std::thread> service_threads_;
 
 private:
   static void close(client &cli);

repertory/librepertory/src/comm/packet/packet_client.cpp

@@ -33,14 +33,25 @@ using namespace repertory::comm;
 
 namespace repertory {
 packet_client::packet_client(remote::remote_config cfg)
-    : cfg_(std::move(cfg)), unique_id_(utils::create_uuid_string()) {}
+    : cfg_(std::move(cfg)), unique_id_(utils::create_uuid_string()) {
+  for (std::uint8_t idx = 0U; idx < cfg.max_connections; ++idx) {
+    service_threads_.emplace_back([this]() { io_context_.run(); });
+  }
+}
 
 packet_client::~packet_client() {
   allow_connections_ = false;
   close_all();
+
+  for (std::size_t idx = 0U; idx < service_threads_.size(); ++idx) {
     io_context_.stop();
   }
 
+  for (auto &thread : service_threads_) {
+    thread.join();
+  }
+}
+
 void packet_client::close(client &cli) {
   try {
     cli.socket.shutdown(boost::asio::socket_base::shutdown_both);
@@ -58,7 +69,9 @@ void packet_client::close_all() {
   }
 
   clients_.clear();
+  for (std::size_t idx = 0U; idx < service_threads_.size(); ++idx) {
     io_context_.restart();
+  }
   resolve_results_ = {};
   unique_id_ = utils::create_uuid_string();
 }