Query Path MTU on every instruction because Linux is not so reliable about EMSGSIZE

network.hpp

@@ -71,8 +71,6 @@ namespace Network {
     Base64Key key;
     Session session;
 
-    void update_MTU( void );
-
     void setup( void );
 
     Direction direction;
@@ -94,6 +92,7 @@ namespace Network {
     void send( string s );
     string recv( void );
     int fd( void ) { return sock; }
+    void update_MTU( void );
     int get_MTU( void ) { return MTU; }
 
     int port( void );

transportsender.cpp

@@ -246,6 +246,7 @@ void TransportSender<MyState>::send_in_fragments( string diff, uint64_t new_num
     shutdown_tries++;
   }
 
+  connection->update_MTU();
   vector<Fragment> fragments = fragmenter.make_fragments( inst, connection->get_MTU() );
 
   for ( auto i = fragments.begin(); i != fragments.end(); i++ ) {