daemon: add '--no-sync' arg to optionally disable blockchain sync

src/cryptonote_protocol/cryptonote_protocol_handler.h

@@ -111,6 +111,7 @@ namespace cryptonote
     void stop();
     void on_connection_close(cryptonote_connection_context &context);
     void set_max_out_peers(unsigned int max) { m_max_out_peers = max; }
+    void set_no_sync(bool value) { m_no_sync = value; }
     std::string get_peers_overview() const;
     std::pair<uint32_t, uint32_t> get_next_needed_pruning_stripe() const;
     bool needs_new_sync_connections() const;
@@ -149,6 +150,7 @@ namespace cryptonote
     std::atomic<uint32_t> m_syncronized_connections_count;
     std::atomic<bool> m_synchronized;
     std::atomic<bool> m_stopping;
+    std::atomic<bool> m_no_sync;
     boost::mutex m_sync_lock;
     block_queue m_block_queue;
     epee::math_helper::once_a_time_seconds<30> m_idle_peer_kicker;

src/cryptonote_protocol/cryptonote_protocol_handler.inl

@@ -72,7 +72,8 @@ namespace cryptonote
                                                                                                               m_p2p(p_net_layout),
                                                                                                               m_syncronized_connections_count(0),
                                                                                                               m_synchronized(offline),
-                                                                                                              m_stopping(false)
+                                                                                                              m_stopping(false),
+                                                                                                              m_no_sync(false)
 
   {
     if(!m_p2p)
@@ -374,6 +375,13 @@ namespace cryptonote
     m_core.set_target_blockchain_height((hshd.current_height));
     }
     MINFO(context << "Remote blockchain height: " << hshd.current_height << ", id: " << hshd.top_id);
+
+    if (m_no_sync)
+    {
+      context.m_state = cryptonote_connection_context::state_normal;
+      return true;
+    }
+
     context.m_state = cryptonote_connection_context::state_synchronizing;
     //let the socket to send response to handshake, but request callback, to let send request data after response
     LOG_PRINT_CCONTEXT_L2("requesting callback");

src/p2p/net_node.cpp

@@ -128,6 +128,7 @@ namespace nodetool
     const command_line::arg_descriptor<std::vector<std::string> > arg_proxy = {"proxy", "<network-type>,<socks-ip:port>[,max_connections] i.e. \"tor,127.0.0.1:9050,100\""};
     const command_line::arg_descriptor<std::vector<std::string> > arg_anonymous_inbound = {"anonymous-inbound", "<hidden-service-address>,<[bind-ip:]port>[,max_connections] i.e. \"x.onion,127.0.0.1:18083,100\""};
     const command_line::arg_descriptor<bool> arg_p2p_hide_my_port   =    {"hide-my-port", "Do not announce yourself as peerlist candidate", false, true};
+    const command_line::arg_descriptor<bool> arg_no_sync = {"no-sync", "Don't synchronize the blockchain with other peers", false};
 
     const command_line::arg_descriptor<bool>        arg_no_igd  = {"no-igd", "Disable UPnP port mapping"};
     const command_line::arg_descriptor<int64_t>     arg_out_peers = {"out-peers", "set max number of out peers", -1};

src/p2p/net_node.h

@@ -478,6 +478,7 @@ namespace nodetool
     extern const command_line::arg_descriptor<std::vector<std::string> > arg_proxy;
     extern const command_line::arg_descriptor<std::vector<std::string> > arg_anonymous_inbound;
     extern const command_line::arg_descriptor<bool> arg_p2p_hide_my_port;
+    extern const command_line::arg_descriptor<bool> arg_no_sync;
 
     extern const command_line::arg_descriptor<bool>        arg_no_igd;
     extern const command_line::arg_descriptor<bool>        arg_offline;

src/p2p/net_node.inl

@@ -103,6 +103,7 @@ namespace nodetool
     command_line::add_arg(desc, arg_proxy);
     command_line::add_arg(desc, arg_anonymous_inbound);
     command_line::add_arg(desc, arg_p2p_hide_my_port);
+    command_line::add_arg(desc, arg_no_sync);
     command_line::add_arg(desc, arg_no_igd);
     command_line::add_arg(desc, arg_out_peers);
     command_line::add_arg(desc, arg_in_peers);
@@ -310,6 +311,9 @@ namespace nodetool
     if(command_line::has_arg(vm, arg_p2p_hide_my_port))
       m_hide_my_port = true;
 
+    if (command_line::has_arg(vm, arg_no_sync))
+      m_payload_handler.set_no_sync(true);
+
     if ( !set_max_out_peers(public_zone, command_line::get_arg(vm, arg_out_peers) ) )
       return false;
     else