From 919d303c754718a68ba11a51219cf29d56853956 Mon Sep 17 00:00:00 2001
From: Jonathan Hui <jonhui@nestlabs.com>
Date: Mon, 17 Apr 2017 10:55:20 -0700
Subject: [PATCH] Restrict 15.4 Beacon transmissions to REEDs/Routers/Leaders.
 (#1591)

---
 src/core/mac/mac.cpp           | 16 ++++++++++------
 src/core/mac/mac.hpp           | 17 +++++++++++++++++
 src/core/thread/mle.cpp        |  2 ++
 src/core/thread/mle_router.cpp | 26 ++++++++++++++++++++++++--
 4 files changed, 53 insertions(+), 8 deletions(-)

diff --git a/src/core/mac/mac.cpp b/src/core/mac/mac.cpp
index a257f235d..edb66c0a8 100644
--- a/src/core/mac/mac.cpp
+++ b/src/core/mac/mac.cpp
@@ -132,6 +132,7 @@ Mac::Mac(ThreadNetif &aThreadNetif):
     mCsmaAttempts = 0;
     mTransmitAttempts = 0;
     mTransmitBeacon = false;
+    mBeaconsEnabled = false;
 
     mPendingScanRequest = kScanTypeNone;
     mScanChannel = kPhyMinChannel;
@@ -1536,13 +1537,16 @@ ThreadError Mac::HandleMacCommand(Frame &aFrame)
         mCounters.mRxBeaconRequest++;
         otLogDebgMac(GetInstance(), "Received Beacon Request");
 
-        mTransmitBeacon = true;
-
-        if (mState == kStateIdle)
+        if (mBeaconsEnabled)
         {
-            mState = kStateTransmitBeacon;
-            mTransmitBeacon = false;
-            StartCsmaBackoff();
+            mTransmitBeacon = true;
+
+            if (mState == kStateIdle)
+            {
+                mState = kStateTransmitBeacon;
+                mTransmitBeacon = false;
+                StartCsmaBackoff();
+            }
         }
 
         ExitNow(error = kThreadError_Drop);
diff --git a/src/core/mac/mac.hpp b/src/core/mac/mac.hpp
index 92f8458b4..37423d7f2 100644
--- a/src/core/mac/mac.hpp
+++ b/src/core/mac/mac.hpp
@@ -281,6 +281,22 @@ public:
      */
     void EnergyScanDone(int8_t aEnergyScanMaxRssi);
 
+    /**
+     * This method indicates whether or not IEEE 802.15.4 Beacon transmissions are enabled.
+     *
+     * @retval TRUE if IEEE 802.15.4 Beacon transmissions are enabled, FALSE otherwise.
+     *
+     */
+    bool IsBeaconEnabled(void) const { return mBeaconsEnabled; }
+
+    /**
+     * This method enables/disables IEEE 802.15.4 Beacon transmissions.
+     *
+     * @param[in]  aEnabled  TRUE to enable IEEE 802.15.4 Beacon transmissions, FALSE otherwise.
+     *
+     */
+    void SetBeaconEnabled(bool aEnabled) { mBeaconsEnabled = aEnabled; }
+
     /**
      * This method indicates whether or not rx-on-when-idle is enabled.
      *
@@ -662,6 +678,7 @@ private:
     uint8_t mCsmaAttempts;
     uint8_t mTransmitAttempts;
     bool mTransmitBeacon;
+    bool mBeaconsEnabled;
 
     ScanType mPendingScanRequest;
     uint8_t mScanChannel;
diff --git a/src/core/thread/mle.cpp b/src/core/thread/mle.cpp
index 57728e7cb..476830e10 100644
--- a/src/core/thread/mle.cpp
+++ b/src/core/thread/mle.cpp
@@ -551,6 +551,7 @@ ThreadError Mle::SetStateDetached(void)
     mParentRequestState = kParentIdle;
     mParentRequestTimer.Stop();
     mNetif.GetMeshForwarder().SetRxOff();
+    mNetif.GetMac().SetBeaconEnabled(false);
     mNetif.GetMle().HandleDetachStart();
     mNetif.GetIp6().SetForwardingEnabled(false);
     mNetif.GetIp6().mMpl.SetTimerExpirations(0);
@@ -575,6 +576,7 @@ ThreadError Mle::SetStateChild(uint16_t aRloc16)
     mDeviceState = kDeviceStateChild;
     mParentRequestState = kParentIdle;
     mChildUpdateAttempts = 0;
+    mNetif.GetMac().SetBeaconEnabled(false);
 
     if ((mDeviceMode & ModeTlv::kModeRxOnWhenIdle) != 0)
     {
diff --git a/src/core/thread/mle_router.cpp b/src/core/thread/mle_router.cpp
index 1e0e8cfcd..a9a60a242 100644
--- a/src/core/thread/mle_router.cpp
+++ b/src/core/thread/mle_router.cpp
@@ -90,9 +90,24 @@ void MleRouter::SetRouterRoleEnabled(bool aEnabled)
 {
     mRouterRoleEnabled = aEnabled;
 
-    if (!mRouterRoleEnabled && (mDeviceState == kDeviceStateRouter || mDeviceState == kDeviceStateLeader))
+    switch (mDeviceState)
     {
-        BecomeDetached();
+    case kDeviceStateDisabled:
+    case kDeviceStateDetached:
+        break;
+
+    case kDeviceStateChild:
+        mNetif.GetMac().SetBeaconEnabled(mRouterRoleEnabled);
+        break;
+
+    case kDeviceStateRouter:
+    case kDeviceStateLeader:
+        if (!mRouterRoleEnabled)
+        {
+            BecomeDetached();
+        }
+
+        break;
     }
 }
 
@@ -329,6 +344,11 @@ ThreadError MleRouter::HandleChildStart(otMleAttachFilter aFilter)
     StopLeader();
     mStateUpdateTimer.Start(kStateUpdatePeriod);
 
+    if (mRouterRoleEnabled)
+    {
+        mNetif.GetMac().SetBeaconEnabled(true);
+    }
+
     mNetif.SubscribeAllRoutersMulticast();
 
     VerifyOrExit(IsRouterIdValid(mPreviousRouterId));
@@ -401,6 +421,7 @@ ThreadError MleRouter::SetStateRouter(uint16_t aRloc16)
     mStateUpdateTimer.Start(kStateUpdatePeriod);
     mNetif.GetIp6().SetForwardingEnabled(true);
     mNetif.GetIp6().mMpl.SetTimerExpirations(kMplRouterDataMessageTimerExpirations);
+    mNetif.GetMac().SetBeaconEnabled(true);
 
     for (int i = 0; i < mMaxChildrenAllowed; i++)
     {
@@ -442,6 +463,7 @@ ThreadError MleRouter::SetStateLeader(uint16_t aRloc16)
     mNetif.GetCoapServer().AddResource(mAddressRelease);
     mNetif.GetIp6().SetForwardingEnabled(true);
     mNetif.GetIp6().mMpl.SetTimerExpirations(kMplRouterDataMessageTimerExpirations);
+    mNetif.GetMac().SetBeaconEnabled(true);
 
     for (int i = 0; i < mMaxChildrenAllowed; i++)
     {