From 674bff37fa2807b294eefaac71a8c945129048a5 Mon Sep 17 00:00:00 2001
From: Jonathan Hui <jonhui@nestlabs.com>
Date: Tue, 23 Aug 2016 20:47:33 -0700
Subject: [PATCH] Implement a method for removing a neighbor. (#454)

---
 src/core/mac/mac.cpp           | 12 +-------
 src/core/thread/mle_router.cpp | 56 +++++++++++++++++++++++++++++-----
 src/core/thread/mle_router.hpp | 21 +++++++++++++
 3 files changed, 71 insertions(+), 18 deletions(-)

diff --git a/src/core/mac/mac.cpp b/src/core/mac/mac.cpp
index be6609b2c..4b500942a 100644
--- a/src/core/mac/mac.cpp
+++ b/src/core/mac/mac.cpp
@@ -648,7 +648,6 @@ void Mac::SentFrame(bool aAcked)
 {
     Frame &sendFrame(*static_cast<Frame *>(otPlatRadioGetTransmitBuffer()));
     Address destination;
-    Neighbor *neighbor;
     Sender *sender;
 
     if (sendFrame.GetAckRequest() && !aAcked)
@@ -666,16 +665,7 @@ void Mac::SentFrame(bool aAcked)
         }
 
         sendFrame.GetDstAddr(destination);
-
-        if ((neighbor = mMle.GetNeighbor(destination)) != NULL)
-        {
-            if (neighbor->mState == Neighbor::kStateValid && !mMle.IsActiveRouter(neighbor->mValid.mRloc16))
-            {
-                mNetif.SetStateChangedFlags(OT_THREAD_CHILD_REMOVED);
-            }
-
-            neighbor->mState = Neighbor::kStateInvalid;
-        }
+        mMle.RemoveNeighbor(destination);
     }
 
     mTransmitAttempts = 0;
diff --git a/src/core/thread/mle_router.cpp b/src/core/thread/mle_router.cpp
index 157b71cd9..4b8a0d2f8 100644
--- a/src/core/thread/mle_router.cpp
+++ b/src/core/thread/mle_router.cpp
@@ -623,7 +623,7 @@ ThreadError MleRouter::HandleLinkRequest(const Message &aMessage, const Ip6::Mes
         if ((neighbor = GetNeighbor(macAddr)) != NULL && neighbor->mValid.mRloc16 != rloc16)
         {
             // remove stale neighbors
-            neighbor->mState = Neighbor::kStateInvalid;
+            RemoveNeighbor(*neighbor);
             neighbor = NULL;
         }
 
@@ -807,7 +807,7 @@ ThreadError MleRouter::HandleLinkAccept(const Message &aMessage, const Ip6::Mess
     if ((neighbor = GetNeighbor(macAddr)) != NULL &&
         neighbor->mValid.mRloc16 != sourceAddress.GetRloc16())
     {
-        neighbor->mState = Neighbor::kStateInvalid;
+        RemoveNeighbor(*neighbor);
         neighbor = NULL;
     }
 
@@ -1218,7 +1218,7 @@ ThreadError MleRouter::HandleAdvertisement(const Message &aMessage, const Ip6::M
     if ((neighbor = GetNeighbor(macAddr)) != NULL &&
         neighbor->mValid.mRloc16 != sourceAddress.GetRloc16())
     {
-        neighbor->mState = Neighbor::kStateInvalid;
+        RemoveNeighbor(*neighbor);
     }
 
     // Leader Data
@@ -1608,8 +1608,7 @@ void MleRouter::HandleStateUpdateTimer(void)
 
         if ((Timer::GetNow() - mChildren[i].mLastHeard) >= Timer::SecToMsec(mChildren[i].mTimeout))
         {
-            mChildren[i].mState = Neighbor::kStateInvalid;
-            mNetif.SetStateChangedFlags(OT_THREAD_CHILD_REMOVED);
+            RemoveNeighbor(mChildren[i]);
         }
     }
 
@@ -1828,7 +1827,7 @@ ThreadError MleRouter::HandleChildIdRequest(const Message &aMessage, const Ip6::
         if (mRouters[i].mState != Neighbor::kStateInvalid &&
             memcmp(&mRouters[i].mMacAddr, &macAddr, sizeof(mRouters[i].mMacAddr)) == 0)
         {
-            mRouters[i].mState = Neighbor::kStateInvalid;
+            RemoveNeighbor(mRouters[i]);
             break;
         }
     }
@@ -2282,6 +2281,49 @@ Child *MleRouter::GetChildren(uint8_t *numChildren)
     return mChildren;
 }
 
+ThreadError MleRouter::RemoveNeighbor(const Mac::Address &aAddress)
+{
+    ThreadError error = kThreadError_None;
+    Neighbor *neighbor;
+
+    VerifyOrExit((neighbor = GetNeighbor(aAddress)) != NULL, error = kThreadError_NotFound);
+    SuccessOrExit(error = RemoveNeighbor(*neighbor));
+
+exit:
+    return error;
+}
+
+ThreadError MleRouter::RemoveNeighbor(Neighbor &aNeighbor)
+{
+    switch (mDeviceState)
+    {
+    case kDeviceStateDisabled:
+    case kDeviceStateDetached:
+        break;
+
+    case kDeviceStateChild:
+        if (&aNeighbor == &mParent)
+        {
+            BecomeDetached();
+        }
+
+        break;
+
+    case kDeviceStateRouter:
+    case kDeviceStateLeader:
+        if (aNeighbor.mState == Neighbor::kStateValid && !IsActiveRouter(aNeighbor.mValid.mRloc16))
+        {
+            mNetif.SetStateChangedFlags(OT_THREAD_CHILD_REMOVED);
+        }
+
+        break;
+    }
+
+    aNeighbor.mState = Neighbor::kStateInvalid;
+
+    return kThreadError_None;
+}
+
 Neighbor *MleRouter::GetNeighbor(uint16_t aAddress)
 {
     Neighbor *rval = NULL;
@@ -2885,7 +2927,7 @@ void MleRouter::HandleAddressSolicitResponse(Message &aMessage)
         case Neighbor::kStateValid:
             if (GetRouterId(mChildren[i].mValid.mRloc16) != mRouterId)
             {
-                mChildren[i].mState = Neighbor::kStateInvalid;
+                RemoveNeighbor(mChildren[i]);
             }
 
             break;
diff --git a/src/core/thread/mle_router.hpp b/src/core/thread/mle_router.hpp
index d70ffb1de..67fee82c2 100644
--- a/src/core/thread/mle_router.hpp
+++ b/src/core/thread/mle_router.hpp
@@ -245,6 +245,27 @@ public:
      */
     ThreadError ReleaseRouterId(uint8_t aRouterId);
 
+    /**
+     * This method removes a link to a neighbor.
+     *
+     * @param[in]  aAddress  The link address of the neighbor.
+     *
+     * @retval kThreadError_None      Successfully removed the neighbor.
+     * @retval kThreadError_NotFound  Could not find the neighbor.
+     *
+     */
+    ThreadError RemoveNeighbor(const Mac::Address &aAddress);
+
+    /**
+     * This method removes a link to a neighbor.
+     *
+     * @param[in]  aNeighbor  A reference to the neighbor object.
+     *
+     * @retval kThreadError_None      Successfully removed the neighbor.
+     *
+     */
+    ThreadError RemoveNeighbor(Neighbor &aNeighbor);
+
     /**
      * This method returns a pointer to a Child object.
      *