[mle] fix partition merging with REEDs (openthread#2476)

REEDs periodically transmit MLE Advertisement messages to support merging partitions. However, REEDs do not include Route64 TLVs in their MLE Advertisement messages. This commit removes the strict requirement check when handling MLE Advertisement messages, allowing such messages sent by REEDs to trigger the partition merging process.
osaboh · Jan 15, 2018 · 3306509 · 3306509
1 parent 15885dc
commit 3306509
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Showing 2 changed files with 40 additions and 16 deletions.
diff --git a/src/core/thread/mle_router.cpp b/src/core/thread/mle_router.cpp
@@ -1308,6 +1308,30 @@ uint8_t MleRouter::GetActiveNeighborRouterCount(void) const
     return rval;
 }
 
+bool MleRouter::IsSingleton(const RouteTlv &aRouteTlv)
+{
+    bool rval = true;
+    uint8_t count = 0;
+
+    // REEDs do not include a Route TLV and indicate not a singleton
+    if (!aRouteTlv.IsValid())
+    {
+        ExitNow(rval = false);
+    }
+
+    // Check if 2 or more active routers
+    for (uint8_t i = 0; i <= kMaxRouterId; i++)
+    {
+        if (aRouteTlv.IsRouterIdSet(i) && (++count >= 2))
+        {
+            ExitNow(rval = false);
+        }
+    }
+
+exit:
+    return rval;
+}
+
 otError MleRouter::HandleAdvertisement(const Message &aMessage, const Ip6::MessageInfo &aMessageInfo)
 {
     ThreadNetif &netif = GetNetif();
@@ -1341,9 +1365,16 @@ otError MleRouter::HandleAdvertisement(const Message &aMessage, const Ip6::Messa
     SuccessOrExit(error = Tlv::GetTlv(aMessage, Tlv::kLeaderData, sizeof(leaderData), leaderData));
     VerifyOrExit(leaderData.IsValid(), error = OT_ERROR_PARSE);
 
-    // Route Data
-    SuccessOrExit(error = Tlv::GetTlv(aMessage, Tlv::kRoute, sizeof(route), route));
-    VerifyOrExit(route.IsValid(), error = OT_ERROR_PARSE);
+    // Route Data (optional)
+    if (Tlv::GetTlv(aMessage, Tlv::kRoute, sizeof(route), route) == OT_ERROR_NONE)
+    {
+        VerifyOrExit(route.IsValid(), error = OT_ERROR_PARSE);
+    }
+    else
+    {
+        // mark that a Route TLV was not included
+        route.SetLength(0);
+    }
 
     partitionId = leaderData.GetPartitionId();
 
@@ -1354,7 +1385,8 @@ otError MleRouter::HandleAdvertisement(const Message &aMessage, const Ip6::Messa
 
         VerifyOrExit(linkMargin >= OPENTHREAD_CONFIG_MLE_PARTITION_MERGE_MARGIN_MIN, error = OT_ERROR_LINK_MARGIN_LOW);
 
-        if ((mDeviceMode & ModeTlv::kModeFFD) &&
+        if (route.IsValid() &&
+            (mDeviceMode & ModeTlv::kModeFFD) &&
             (mLastPartitionIdTimeout > 0) &&
             (partitionId == mLastPartitionId))
         {
@@ -1368,17 +1400,7 @@ otError MleRouter::HandleAdvertisement(const Message &aMessage, const Ip6::Messa
             ExitNow();
         }
 
-        routerCount = 0;
-
-        for (uint8_t i = 0; i <= kMaxRouterId; i++)
-        {
-            if (route.IsRouterIdSet(i))
-            {
-                routerCount++;
-            }
-        }
-
-        if (ComparePartitions(routerCount <= 1, leaderData, IsSingleton(), mLeaderData) > 0)
+        if (ComparePartitions(IsSingleton(route), leaderData, IsSingleton(), mLeaderData) > 0)
         {
             BecomeChild(kAttachBetter);
         }
@@ -1397,7 +1419,7 @@ otError MleRouter::HandleAdvertisement(const Message &aMessage, const Ip6::Messa
         ExitNow();
     }
 
-    VerifyOrExit(IsActiveRouter(sourceAddress.GetRloc16()));
+    VerifyOrExit(IsActiveRouter(sourceAddress.GetRloc16()) && route.IsValid());
     routerId = GetRouterId(sourceAddress.GetRloc16());
     router = GetRouter(routerId);
     VerifyOrExit(router != NULL, error = OT_ERROR_PARSE);

diff --git a/src/core/thread/mle_router_ftd.hpp b/src/core/thread/mle_router_ftd.hpp
@@ -813,6 +813,8 @@ class MleRouter: public Mle
 
     static uint8_t LinkQualityToCost(uint8_t aLinkQuality);
 
+    static bool IsSingleton(const RouteTlv &aRouteTlv);
+
     Child *NewChild(void);
     Child *FindChild(uint16_t aChildId);
     Child *FindChild(const Mac::ExtAddress &aMacAddr);