3 files changed, 26 insertions, 10 deletions
diff --git a/src/commander.cpp b/src/commander.cpp
index 98fc0d0..5c15ef9 100644
--- a/src/commander.cpp
+++ b/src/commander.cpp
@@ -25,7 +25,7 @@ void commander::start()
             m_connection = wanda::make_control_connection(std::move(m_socket));
             m_connection->add(this);
             m_connection->start();
-            m_connection->send({"C", "HELLO", "1.0.0"});
+            m_connection->send({message_source_controller, message_command_hello, message_argument_hello});
         }
     });
 }
diff --git a/src/control_interface.cpp b/src/control_interface.cpp
index 92d5def..85d1dca 100644
--- a/src/control_interface.cpp
+++ b/src/control_interface.cpp
@@ -100,14 +100,20 @@ void control_interface::on_received(control_connection::pointer connection, mess
         return;
     }
 
-    switch (connection->current_state())
+    if (message.source != message_source_controller)
     {
-    case control_connection::state::fresh:
-        if (message.command == "HELLO")
-        {
-            connection->send({"D", "HELLO", "1.0.0"});
-            connection->update(control_connection::state::established);
-        }
+        // TODO: Handle illegal message source
+        return;
+    }
+
+    if (auto state = connection->current_state(); message.command == message_command_hello && state == control_connection::state::fresh)
+    {
+        connection->send({message_source_daemon, message_command_hello, message_argument_hello});
+        connection->update(control_connection::state::established);
+    }
+    else
+    {
+        // TODO: Handle unexpected message
     }
 }
 
diff --git a/src/message.hpp b/src/message.hpp
index f34d19c..a834b15 100644
--- a/src/message.hpp
+++ b/src/message.hpp
@@ -9,6 +9,16 @@
 namespace wanda
 {
 
+inline namespace v1
+{
+auto constexpr message_argument_hello = "1.0.0";
+}
+
+auto constexpr message_source_controller = "C";
+auto constexpr message_source_daemon = "D";
+
+auto constexpr message_command_hello = "HELLO";
+
 struct message
 {
     explicit operator std::string() const;
@@ -20,8 +30,8 @@ struct message
     std::optional<std::string> argument;
 };
 
-std::istream & operator>>(std::istream & in, message & message);
-std::ostream & operator<<(std::ostream & out, message const & message);
+std::istream &operator>>(std::istream &in, message &message);
+std::ostream &operator<<(std::ostream &out, message const &message);
 
 } // namespace wanda