Increment the Commissioner Session ID when the Leader resigns an active Commissioner (#1010)

src/core/meshcop/leader.cpp

@@ -181,8 +181,7 @@ void Leader::HandleKeepAlive(Coap::Header &aHeader, Message &aMessage, const Ip6
     {
         responseState = StateTlv::kReject;
         mTimer.Stop();
-        mNetworkData.SetCommissioningData(NULL, 0);
-        otLogInfoMeshCoP("commissioner inactive");
+        ResignCommissioner();
     }
     else
     {
@@ -267,12 +266,24 @@ void Leader::HandleTimer(void)
 {
     VerifyOrExit(mNetif.GetMle().GetDeviceState() == Mle::kDeviceStateLeader, ;);
 
-    otLogInfoMeshCoP("commissioner inactive");
-    mNetworkData.SetCommissioningData(NULL, 0);
+    ResignCommissioner();
 
 exit:
     return;
 }
 
+void Leader::ResignCommissioner(void)
+{
+    CommissionerSessionIdTlv mCommissionerSessionId;
+
+    mCommissionerSessionId.Init();
+    mCommissionerSessionId.SetCommissionerSessionId(++mSessionId);
+
+    mNetworkData.SetCommissioningData(reinterpret_cast<uint8_t *>(&mCommissionerSessionId),
+                                      sizeof(Tlv) + mCommissionerSessionId.GetLength());
+
+    otLogInfoMeshCoP("commissioner inactive");
+}
+
 }  // namespace MeshCoP
 }  // namespace Thread

src/core/meshcop/leader_ftd.hpp

@@ -104,6 +104,8 @@ private:
 
     static void HandleUdpReceive(void *aContext, otMessage aMessage, const otMessageInfo *aMessageInfo);
 
+    void ResignCommissioner(void);
+
     Coap::Resource mPetition;
     Coap::Resource mKeepAlive;
     Coap::Server &mCoapServer;