diff --git a/include/ascs/ext/unpacker.h b/include/ascs/ext/unpacker.h
index 46e3c3297ea7a002a1d7c295154dc66c1db05d3a..ad5fdcf5b8754c95c057c62ab16682a8da118af8 100644
--- a/include/ascs/ext/unpacker.h
+++ b/include/ascs/ext/unpacker.h
@@ -197,7 +197,13 @@ public:
 	{
 		if (0 == step) //the head been received
 		{
-			assert(!raw_buff.empty());
+			assert(raw_buff.empty() && ASCS_HEAD_LEN == bytes_transferred);
+
+			auto cur_msg_len = ASCS_HEAD_N2H(head) - ASCS_HEAD_LEN;
+			if (cur_msg_len > ASCS_MSG_BUFFER_SIZE - ASCS_HEAD_LEN) //invalid msg, stop reading
+				return false;
+
+			raw_buff.assign(cur_msg_len); assert(!raw_buff.empty());
 			step = 1;
 		}
 		else if (1 == step) //the body been received
@@ -211,7 +217,7 @@ public:
 			step = 0;
 		}
 
-		return -1 != step;
+		return true;
 	}
 
 	//a return value of 0 indicates that the read operation is complete. a non-zero value indicates the maximum number
@@ -224,16 +230,7 @@ public:
 		if (0 == step) //want the head
 		{
 			assert(raw_buff.empty());
-
-			if (bytes_transferred < ASCS_HEAD_LEN)
-				return asio::detail::default_max_transfer_size;
-
-			assert(ASCS_HEAD_LEN == bytes_transferred);
-			auto cur_msg_len = ASCS_HEAD_N2H(head) - ASCS_HEAD_LEN;
-			if (cur_msg_len > ASCS_MSG_BUFFER_SIZE - ASCS_HEAD_LEN) //invalid msg, stop reading
-				step = -1;
-			else
-				raw_buff.assign(cur_msg_len);
+			return asio::detail::default_max_transfer_size;
 		}
 		else if (1 == step) //want the body
 		{
diff --git a/include/ascs/service_pump.h b/include/ascs/service_pump.h
index 0ba8a0aa0bd7520abee14c7694a4c497cf90d827..f9efeaef8f6f81040a55b236e93ff917eeeb6c3a 100644
--- a/include/ascs/service_pump.h
+++ b/include/ascs/service_pump.h
@@ -175,14 +175,14 @@ protected:
 	virtual bool on_exception(const std::exception& e)
 	{
 		unified_out::error_out("service pump exception: %s.", e.what());
-		return true; //continue this io_service::run, if needed, rewrite this to decide whether to continue or not
+		return true; //continue this asio::io_service::run, if needed, rewrite this to decide whether to continue or not
 	}
 
 	size_t run(asio::error_code& ec)
 	{
 		while (true)
 		{
-			try {return io_service::run(ec);}
+			try {return asio::io_service::run(ec);}
 			catch (const std::exception& e) {if (!on_exception(e)) return 0;}
 		}
 	}