Implement MLE Discovery Request Joiner flag filter. (#1665)

src/core/thread/mle_router.cpp

@@ -2493,6 +2493,12 @@ ThreadError MleRouter::HandleDiscoveryRequest(const Message &aMessage, const Ip6
         case MeshCoP::Tlv::kDiscoveryRequest:
             aMessage.Read(offset, sizeof(discoveryRequest), &discoveryRequest);
             VerifyOrExit(discoveryRequest.IsValid(), error = kThreadError_Parse);
+
+            if (discoveryRequest.IsJoiner())
+            {
+                VerifyOrExit(mNetif.GetNetworkDataLeader().IsJoiningEnabled());
+            }
+
             break;
 
         case MeshCoP::Tlv::kExtendedPanId:

src/core/thread/network_data_leader.cpp

@@ -494,6 +494,28 @@ exit:
     return rval;
 }
 
+bool LeaderBase::IsJoiningEnabled(void)
+{
+    MeshCoP::Tlv *steeringData;
+    bool rval = false;
+
+    VerifyOrExit(GetCommissioningDataSubTlv(MeshCoP::Tlv::kBorderAgentLocator) != NULL);
+
+    steeringData = GetCommissioningDataSubTlv(MeshCoP::Tlv::kSteeringData);
+    VerifyOrExit(steeringData != NULL);
+
+    for (int i = 0; i < steeringData->GetLength(); i++)
+    {
+        if (steeringData->GetValue()[i] != 0)
+        {
+            ExitNow(rval = true);
+        }
+    }
+
+exit:
+    return rval;
+}
+
 ThreadError LeaderBase::RemoveCommissioningData(void)
 {
     ThreadError error = kThreadError_NotFound;

src/core/thread/network_data_leader.hpp

@@ -187,6 +187,16 @@ public:
      */
     MeshCoP::Tlv *GetCommissioningDataSubTlv(MeshCoP::Tlv::Type aType);
 
+    /**
+     * This method indicates whether or not the Commissioning Data TLV indicates Joining is enabled.
+     *
+     * Joining is enabled if a Border Agent Locator TLV exist and the Steering Data TLV is non-zero.
+     *
+     * @returns TRUE if the Commissioning Data TLV says Joining is enabled, FALSE otherwise.
+     *
+     */
+    bool IsJoiningEnabled(void);
+
     /**
      * This method adds Commissioning Data to the Thread Network Data.
      *