From 87d8940abfc379c0748055fc0bf6f4870d5e73ce Mon Sep 17 00:00:00 2001
From: Jonathan Hui <jonhui@nestlabs.com>
Date: Fri, 12 Jan 2018 01:04:55 +0000
Subject: [PATCH] [mle] request network data on child reattach after reboot
 (#2466)

This commit adds a Network Data TLV request to the MLE Child Update Request
message when trying to resynchronize with a parent after reset.  This
eliminates the need for an MLE Data Request/Response exchange following the
MLE Child Update Request/Response exchange.
---
 src/core/thread/mle.cpp | 8 ++++++--
 1 file changed, 6 insertions(+), 2 deletions(-)

diff --git a/src/core/thread/mle.cpp b/src/core/thread/mle.cpp
index e14099c24..3270e5eee 100644
--- a/src/core/thread/mle.cpp
+++ b/src/core/thread/mle.cpp
@@ -1807,14 +1807,18 @@ otError Mle::SendChildUpdateRequest(void)
     switch (mRole)
     {
     case OT_DEVICE_ROLE_DETACHED:
+    {
+        static const uint8_t tlvs[] = {Tlv::kNetworkData};
+
         for (uint8_t i = 0; i < sizeof(mParentRequest.mChallenge); i++)
         {
             mParentRequest.mChallenge[i] = static_cast<uint8_t>(otPlatRandomGet());
         }
 
-        SuccessOrExit(error = AppendChallenge(*message, mParentRequest.mChallenge,
-                                              sizeof(mParentRequest.mChallenge)));
+        SuccessOrExit(error = AppendChallenge(*message, mParentRequest.mChallenge, sizeof(mParentRequest.mChallenge)));
+        SuccessOrExit(error = AppendTlvRequest(*message, tlvs, sizeof(tlvs)));
         break;
+    }
 
     case OT_DEVICE_ROLE_CHILD:
         SuccessOrExit(error = AppendSourceAddress(*message));