From 5dbfe2af460e5f3ee4631afc983f6f298a324659 Mon Sep 17 00:00:00 2001
From: Jonathan Hui <jonhui@nestlabs.com>
Date: Tue, 16 Aug 2016 19:10:09 -0700
Subject: [PATCH] Only enable IPv6 forwarding for Router and Leader roles.
 (#390)

---
 src/core/net/ip6.cpp           | 12 ++++++++++++
 src/core/net/ip6.hpp           |  8 ++++++++
 src/core/thread/mle.cpp        |  4 ++++
 src/core/thread/mle_router.cpp |  2 ++
 4 files changed, 26 insertions(+)

diff --git a/src/core/net/ip6.cpp b/src/core/net/ip6.cpp
index 037e7136a..f51b19283 100644
--- a/src/core/net/ip6.cpp
+++ b/src/core/net/ip6.cpp
@@ -49,6 +49,7 @@ namespace Ip6 {
 
 static otDEFINE_ALIGNED_VAR(sMplBuf, sizeof(Mpl), uint64_t);
 static Mpl *sMpl;
+static bool sForwardingEnabled;
 
 static otReceiveIp6DatagramCallback sReceiveIp6DatagramCallback = NULL;
 
@@ -63,6 +64,12 @@ Message *Ip6::NewMessage(uint16_t reserved)
 void Ip6::Init(void)
 {
     sMpl = new(&sMplBuf) Mpl;
+    sForwardingEnabled = false;
+}
+
+void Ip6::SetForwardingEnabled(bool aEnable)
+{
+    sForwardingEnabled = aEnable;
 }
 
 uint16_t Ip6::UpdateChecksum(uint16_t checksum, uint16_t val)
@@ -405,6 +412,11 @@ ThreadError Ip6::HandleDatagram(Message &message, Netif *netif, int8_t interface
         }
     }
 
+    if (!sForwardingEnabled && netif != NULL)
+    {
+        forward = false;
+    }
+
     message.SetOffset(sizeof(header));
 
     // process IPv6 Extension Headers
diff --git a/src/core/net/ip6.hpp b/src/core/net/ip6.hpp
index 4fc89a3e5..7af67f8a2 100644
--- a/src/core/net/ip6.hpp
+++ b/src/core/net/ip6.hpp
@@ -583,6 +583,14 @@ public:
      */
     static void SetReceiveDatagramCallback(otReceiveIp6DatagramCallback aCallback);
 
+    /**
+     * This static method enables/disables IPv6 forwarding.
+     *
+     * @param[in]  aEnable  TRUE to enable IPv6 forwarding, FALSE otherwise.
+     *
+     */
+    static void SetForwardingEnabled(bool aEnable);
+
 private:
     static void ProcessReceiveCallback(Message &aMessage);
 };
diff --git a/src/core/thread/mle.cpp b/src/core/thread/mle.cpp
index 8850abae2..659a91519 100644
--- a/src/core/thread/mle.cpp
+++ b/src/core/thread/mle.cpp
@@ -331,6 +331,8 @@ ThreadError Mle::SetStateDetached(void)
     mParentRequestTimer.Stop();
     mMesh.SetRxOnWhenIdle(true);
     mMleRouter.HandleDetachStart();
+    Ip6::Ip6::SetForwardingEnabled(false);
+
     otLogInfoMle("Mode -> Detached\n");
     return kThreadError_None;
 }
@@ -356,6 +358,8 @@ ThreadError Mle::SetStateChild(uint16_t aRloc16)
         mMleRouter.HandleChildStart(mParentRequestMode);
     }
 
+    Ip6::Ip6::SetForwardingEnabled(false);
+
     otLogInfoMle("Mode -> Child\n");
     return kThreadError_None;
 }
diff --git a/src/core/thread/mle_router.cpp b/src/core/thread/mle_router.cpp
index b5d423e0c..915a9ceb9 100644
--- a/src/core/thread/mle_router.cpp
+++ b/src/core/thread/mle_router.cpp
@@ -338,6 +338,7 @@ ThreadError MleRouter::SetStateRouter(uint16_t aRloc16)
     mRouters[mRouterId].mNextHop = mRouterId;
     mNetworkData.Stop();
     mStateUpdateTimer.Start(kStateUpdatePeriod);
+    Ip6::Ip6::SetForwardingEnabled(true);
 
     otLogInfoMle("Mode -> Router\n");
     return kThreadError_None;
@@ -364,6 +365,7 @@ ThreadError MleRouter::SetStateLeader(uint16_t aRloc16)
     mNetif.GetPendingDataset().ApplyLocalToNetwork();
     mCoapServer.AddResource(mAddressSolicit);
     mCoapServer.AddResource(mAddressRelease);
+    Ip6::Ip6::SetForwardingEnabled(true);
 
     otLogInfoMle("Mode -> Leader %d\n", mLeaderData.GetPartitionId());
     return kThreadError_None;