diff --git a/common.cpp b/common.cpp
index 93ad6c7..22e6796 100644
--- a/common.cpp
+++ b/common.cpp
@@ -21,7 +21,7 @@ unordered_map<int, const char*> raw_mode_tostring = {{mode_faketcp, "faketcp"},
 char iptables_rule[200]="";
 //int is_client = 0, is_server = 0;
 
-program_mode_t client_or_server=unset_mode;//0 unset; 1client 2server
+program_mode_t program_mode=unset_mode;//0 unset; 1client 2server
 
 working_mode_t working_mode=tunnel_mode;
 
diff --git a/common.h b/common.h
index 1708ece..fa89b67 100644
--- a/common.h
+++ b/common.h
@@ -152,7 +152,7 @@ extern int about_to_exit;
 enum raw_mode_t{mode_faketcp=0,mode_udp,mode_icmp,mode_end};
 extern raw_mode_t raw_mode;
 enum program_mode_t {unset_mode=0,client_mode,server_mode};
-extern program_mode_t client_or_server;
+extern program_mode_t program_mode;
 extern unordered_map<int, const char*> raw_mode_tostring ;
 
 enum working_mode_t {unset_working_mode=0,tunnel_mode,tun_dev_mode};
diff --git a/connection.h b/connection.h
index 10a5ecd..1a31b04 100644
--- a/connection.h
+++ b/connection.h
@@ -255,14 +255,38 @@ struct stat_t
 struct conn_info_t     //stores info for a raw connection.for client ,there is only one connection,for server there can be thousand of connection since server can
 //handle multiple clients
 {
-	struct  //conv_manager_t is here to avoid copying when a connection is recovered
-	//TODO maybe an unconstrained union is better, but struct is okay since conv_manger is small when no data is filled in.
+	union  tmp_union_t
 	{
 		conv_manager_t<address_t> c;
 		conv_manager_t<u64_t> s;
 		//avoid templates here and there, avoid pointer and type cast
+		tmp_union_t()
+		{
+			if(program_mode==client_mode)
+			{
+				new( &c ) conv_manager_t<address_t>();
+			}
+			else
+			{
+				assert(program_mode==server_mode);
+				new( &s ) conv_manager_t<u64_t>();
+			}
+		}
+		~tmp_union_t()
+		{
+			if(program_mode==client_mode)
+			{
+				c.~conv_manager_t<address_t>();
+			}
+			else
+			{
+				assert(program_mode==server_mode);
+				s.~conv_manager_t<u64_t>();
+			}
+		}
 	}conv_manager;
 
+
 	fec_encode_manager_t fec_encode_manager;
 	fec_decode_manager_t fec_decode_manager;
 	ev_timer timer;
diff --git a/main.cpp b/main.cpp
index 345c284..3c97180 100644
--- a/main.cpp
+++ b/main.cpp
@@ -153,7 +153,7 @@ int main(int argc, char *argv[])
 		sprintf(tun_dev,"tun%u",get_fake_random_number()%1000);
 	}
 
-	if(client_or_server==client_mode)
+	if(program_mode==client_mode)
 	{
 		tunnel_client_event_loop();
 	}
diff --git a/misc.cpp b/misc.cpp
index dffdf01..573d5e1 100644
--- a/misc.cpp
+++ b/misc.cpp
@@ -965,11 +965,11 @@ void process_arg(int argc, char *argv[])
 	}
 	if(is_client==1)
 	{
-		client_or_server=client_mode;
+		program_mode=client_mode;
 	}
 	else
 	{
-		client_or_server=server_mode;
+		program_mode=server_mode;
 	}
 
 
@@ -984,12 +984,12 @@ void process_arg(int argc, char *argv[])
 	}
 	else if(working_mode==tun_dev_mode)
 	{
-		if(client_or_server==client_mode&&no_r)
+		if(program_mode==client_mode&&no_r)
 		{
 			mylog(log_fatal,"error: -r not found\n");
 			myexit(-1);
 		}
-		else if(client_or_server==server_mode&&no_l)
+		else if(program_mode==server_mode&&no_l)
 		{
 			mylog(log_fatal,"error: -l not found\n");
 			myexit(-1);