2004-11-21 jrandom

* Only allow small clock skews after the first 10 minutes of operation
      (to prevent later network lag bouncing us way off course - yes, we
      really need an NTP impl to balance out the network burps...)
    * Revamp the I2PTunnel web interface startup process so that everything
      is shown immediately, so that different pieces hanging don't hang
      the rest, and other minor bugfixes.
    * Take note of SAM startup error (in case you're already running a SAM
      bridge...)
    * Increase the bandwidth limiter burst values available to 10-60s (or
      whatever is placed in /configadvanced.jsp, of course)

core/java/src/net/i2p/util/Clock.java

@@ -17,6 +17,7 @@ import net.i2p.time.Timestamper;
 public class Clock implements Timestamper.UpdateListener {
     private I2PAppContext _context;
     private Timestamper _timestamper;
+    private long _startedOn;
     
     public Clock(I2PAppContext context) {
         _context = context;
@@ -24,6 +25,7 @@ public class Clock implements Timestamper.UpdateListener {
         _alreadyChanged = false;
         _listeners = new HashSet(64);
         _timestamper = new Timestamper(context, this);
+        _startedOn = System.currentTimeMillis();
     }
     public static Clock getInstance() {
         return I2PAppContext.getGlobalContext().clock();
@@ -40,6 +42,8 @@ public class Clock implements Timestamper.UpdateListener {
 
     /** if the clock is skewed by 3+ days, fuck 'em */
     public final static long MAX_OFFSET = 3 * 24 * 60 * 60 * 1000;
+    /** after we've started up and shifted the clock, don't allow shifts of more than a minute */
+    public final static long MAX_LIVE_OFFSET = 60 * 1000;
     /** if the clock skewed changes by less than 1s, ignore the update (so we don't slide all over the place) */
     public final static long MIN_OFFSET_CHANGE = 10 * 1000;
 
@@ -60,6 +64,15 @@ public class Clock implements Timestamper.UpdateListener {
                 return;
             }
             
+            // only allow substantial modifications before the first 10 minutes
+            if (_alreadyChanged && (System.currentTimeMillis() - _startedOn > 10 * 60 * 1000)) {
+                if ( (offsetMs > MAX_LIVE_OFFSET) || (offsetMs < 0 - MAX_LIVE_OFFSET) ) {
+                    getLog().log(Log.CRIT, "The clock has already been updated, but you want to change it by "
+                                           + offsetMs + "?  Did something break?");
+                    return;
+                }
+            }
+            
             if ((delta < MIN_OFFSET_CHANGE) && (delta > 0 - MIN_OFFSET_CHANGE)) {
                 getLog().debug("Not changing offset since it is only " + delta + "ms");
                 return;