From b7211d5d67f33b4bc69525c0a1ff4860f3336d43 Mon Sep 17 00:00:00 2001
From: Florian Schmaus <flo@geekplace.eu>
Date: Sun, 22 May 2016 12:02:12 +0200
Subject: [PATCH] Report illegal Stream Management state

Fixes SMACK-721.
---
 smack-tcp/src/main/java/org/jivesoftware/smack/sm/SMUtils.java | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/smack-tcp/src/main/java/org/jivesoftware/smack/sm/SMUtils.java b/smack-tcp/src/main/java/org/jivesoftware/smack/sm/SMUtils.java
index ac79f118b..c432637be 100644
--- a/smack-tcp/src/main/java/org/jivesoftware/smack/sm/SMUtils.java
+++ b/smack-tcp/src/main/java/org/jivesoftware/smack/sm/SMUtils.java
@@ -47,6 +47,9 @@ public class SMUtils {
      * @return the delta
      */
     public static long calculateDelta(long reportedHandledCount, long lastKnownHandledCount) {
+        if (lastKnownHandledCount > reportedHandledCount) {
+            throw new IllegalStateException("Illegal Stream Management State: Last known handled count (" + lastKnownHandledCount + ") is greater than reported handled count (" + reportedHandledCount + ')');
+        }
         return (reportedHandledCount - lastKnownHandledCount) & MASK_32_BIT;
     }
 }