ignore root tstamp updates if we just updated, to throttle the rate at which updates (and new signatures) can propagate

src/yggdrasil/switch.go

@@ -11,11 +11,6 @@ package yggdrasil
 // TODO? use a pre-computed lookup table (python version had this)
 //  A little annoying to do with constant changes from bandwidth estimates
 
-// FIXME (!) throttle how often root updates are accepted
-//  If the root starts spaming with new timestamps, it should only affect their neighbors
-//  The rest of the network should see announcements at a somewhat reasonable rate
-//  Maybe no faster than 2x the usual update interval
-
 import "time"
 import "sync"
 import "sync/atomic"
@@ -23,6 +18,8 @@ import "sync/atomic"
 //import "fmt"
 
 const switch_timeout = time.Minute
+const switch_updateInterval = switch_timeout / 2
+const switch_throttle = switch_updateInterval / 2
 
 // You should be able to provide crypto signatures for this
 // 1 signature per coord, from the *sender* to that coord
@@ -219,7 +216,7 @@ func (t *switchTable) cleanRoot() {
 	}
 	// Or, if we are the root, possibly update our timestamp
 	if t.data.locator.root == t.key &&
-		now.Sub(t.time) > switch_timeout/2 {
+		now.Sub(t.time) > switch_updateInterval {
 		//fmt.Println("root is self and old, updating", t.data.locator.Root)
 		doUpdate = true
 	}
@@ -343,9 +340,11 @@ func (t *switchTable) handleMessage(msg *switchMessage, fromPort switchPort, sig
 		updateRoot = true
 	case cost < pCost:
 		updateRoot = true
-	case sender.port == t.parent &&
-		(msg.locator.tstamp > t.data.locator.tstamp ||
-			!equiv(&msg.locator, &t.data.locator)):
+	case sender.port != t.parent: // do nothing
+	case !equiv(&msg.locator, &t.data.locator):
+		updateRoot = true
+	case now.Sub(t.time) < switch_throttle: // do nothing
+	case msg.locator.tstamp > t.data.locator.tstamp:
 		updateRoot = true
 	}
 	if updateRoot {