Use end-to-end-to-end connectivity (in transport layer) to control port hop.

Avoid playing games with network-layer timestamps.

src/network/network.h

@@ -91,6 +91,9 @@ namespace Network {
     static const int PORT_RANGE_LOW  = 60001;
     static const int PORT_RANGE_HIGH = 60999;
 
+    static const unsigned int SERVER_ASSOCIATION_TIMEOUT = 20000;
+    static const unsigned int PORT_HOP_INTERVAL          = 20000;
+
     static bool try_bind( int socket, uint32_t addr, int port );
 
     int sock;
@@ -112,6 +115,10 @@ namespace Network {
     uint64_t saved_timestamp_received_at;
     uint64_t expected_receiver_seq;
 
+    uint64_t last_heard;
+    uint64_t last_port_choice;
+    uint64_t last_roundtrip_success; /* transport layer needs to tell us this */
+
     bool RTT_hit;
     double SRTT;
     double RTTVAR;
@@ -123,6 +130,8 @@ namespace Network {
 
     Packet new_packet( string &s_payload );
 
+    void hop_port( void );
+
   public:
     Connection( const char *desired_ip, const char *desired_port ); /* server */
     Connection( const char *key_str, const char *ip, int port ); /* client */
@@ -147,7 +156,7 @@ namespace Network {
       return have_send_exception ? &send_exception : NULL;
     }
 
-    void reset( void );
+    void set_last_roundtrip_success( uint64_t s_success ) { last_roundtrip_success = s_success; }
   };
 }