From f22d9dbcec70fa863d87de916a07c71ae1149118 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Hubert=20Mi=C5=9B?= <hubert.mis@nordicsemi.no>
Date: Thu, 9 Feb 2017 18:40:09 +0100
Subject: [PATCH] Add delay to unsolicited Data Response sent by Router (not
 Leader) (#1293)

---
 src/core/thread/mle_router.cpp     | 22 ++++++++++++++++------
 src/core/thread/mle_router_ftd.hpp |  4 +++-
 2 files changed, 19 insertions(+), 7 deletions(-)

diff --git a/src/core/thread/mle_router.cpp b/src/core/thread/mle_router.cpp
index 00968b654..8a1617446 100644
--- a/src/core/thread/mle_router.cpp
+++ b/src/core/thread/mle_router.cpp
@@ -2476,7 +2476,7 @@ ThreadError MleRouter::HandleDataRequest(const Message &aMessage, const Ip6::Mes
         tlvs[numTlvs++] = Tlv::kPendingDataset;
     }
 
-    SendDataResponse(aMessageInfo.GetPeerAddr(), tlvs, numTlvs);
+    SendDataResponse(aMessageInfo.GetPeerAddr(), tlvs, numTlvs, 0);
 
 exit:
     return error;
@@ -2486,6 +2486,7 @@ ThreadError MleRouter::HandleNetworkDataUpdateRouter(void)
 {
     static const uint8_t tlvs[] = {Tlv::kNetworkData};
     Ip6::Address destination;
+    uint16_t delay;
 
     VerifyOrExit(mDeviceState == kDeviceStateRouter || mDeviceState == kDeviceStateLeader, ;);
 
@@ -2493,7 +2494,8 @@ ThreadError MleRouter::HandleNetworkDataUpdateRouter(void)
     destination.mFields.m16[0] = HostSwap16(0xff02);
     destination.mFields.m16[7] = HostSwap16(0x0001);
 
-    SendDataResponse(destination, tlvs, sizeof(tlvs));
+    delay = (mDeviceState == kDeviceStateLeader) ? 0 : (otPlatRandomGet() % kUnsolicitedDataResponseJitter);
+    SendDataResponse(destination, tlvs, sizeof(tlvs), delay);
 
     for (uint8_t i = 0; i < mMaxChildrenAllowed; i++)
     {
@@ -2512,7 +2514,7 @@ ThreadError MleRouter::HandleNetworkDataUpdateRouter(void)
         {
             if (child->mNetworkDataVersion != mNetif.GetNetworkDataLeader().GetVersion())
             {
-                SendDataResponse(destination, tlvs, sizeof(tlvs));
+                SendDataResponse(destination, tlvs, sizeof(tlvs), 0);
             }
         }
         else
@@ -2521,7 +2523,7 @@ ThreadError MleRouter::HandleNetworkDataUpdateRouter(void)
             {
                 static const uint8_t responseTlvs[] = {Tlv::kNetworkData, Tlv::kActiveDataset, Tlv::kPendingDataset};
 
-                SendDataResponse(destination, responseTlvs, sizeof(responseTlvs));
+                SendDataResponse(destination, responseTlvs, sizeof(responseTlvs), 0);
             }
         }
     }
@@ -2879,7 +2881,8 @@ exit:
     return kThreadError_None;
 }
 
-ThreadError MleRouter::SendDataResponse(const Ip6::Address &aDestination, const uint8_t *aTlvs, uint8_t aTlvsLength)
+ThreadError MleRouter::SendDataResponse(const Ip6::Address &aDestination, const uint8_t *aTlvs, uint8_t aTlvsLength,
+                                        uint16_t aDelay)
 {
     ThreadError error = kThreadError_None;
     Message *message;
@@ -2913,7 +2916,14 @@ ThreadError MleRouter::SendDataResponse(const Ip6::Address &aDestination, const
         }
     }
 
-    SuccessOrExit(error = SendMessage(*message, aDestination));
+    if (aDelay)
+    {
+        SuccessOrExit(error = AddDelayedResponse(*message, aDestination, aDelay));
+    }
+    else
+    {
+        SuccessOrExit(error = SendMessage(*message, aDestination));
+    }
 
     otLogInfoMle("Sent Data Response");
 
diff --git a/src/core/thread/mle_router_ftd.hpp b/src/core/thread/mle_router_ftd.hpp
index 2d4e19713..cce3e0ce8 100644
--- a/src/core/thread/mle_router_ftd.hpp
+++ b/src/core/thread/mle_router_ftd.hpp
@@ -720,6 +720,7 @@ private:
     {
         kDiscoveryMaxJitter = 250u,  ///< Maximum jitter time used to delay Discovery Responses in milliseconds.
         kStateUpdatePeriod = 1000u,  ///< State update period in milliseconds.
+        kUnsolicitedDataResponseJitter = 500u,  ///< Maximum delay before unsolicited Data Response in milliseconds.
     };
 
     ThreadError AppendConnectivity(Message &aMessage);
@@ -762,7 +763,8 @@ private:
     ThreadError SendChildUpdateRequest(Child *aChild);
     ThreadError SendChildUpdateResponse(Child *aChild, const Ip6::MessageInfo &aMessageInfo,
                                         const uint8_t *aTlvs, uint8_t aTlvsLength,  const ChallengeTlv *challenge);
-    ThreadError SendDataResponse(const Ip6::Address &aDestination, const uint8_t *aTlvs, uint8_t aTlvsLength);
+    ThreadError SendDataResponse(const Ip6::Address &aDestination, const uint8_t *aTlvs, uint8_t aTlvsLength,
+                                 uint16_t aDelay);
     ThreadError SendDiscoveryResponse(const Ip6::Address &aDestination, uint16_t aPanId);
 
     ThreadError SetStateRouter(uint16_t aRloc16);