commit 2117dae5f816027db772a577d544e095503384c9
author Rongli Sun <rongli@google.com> Mon Jul 27 13:16:13 2020 +0800
committer GitHub <noreply@github.com> Sun Jul 26 22:16:13 2020 -0700
tree a691667fcb6adf457eb0bf10a135b26a5e583911
parent c5e7252fed253760e76097179a1078f410bcd641

[mle] kAppendMeshLocalOnly for Child Update Request when detached (#5295)

When the child reboot, only register the mesh local address to avoid
possible large Child Update Response which would be fragmented, thus
avoiding reattach process.

src/core/thread/mle.cpp

diff --git a/src/core/thread/mle.cpp b/src/core/thread/mle.cpp
index 68c78d0..1a6584d 100644
--- a/src/core/thread/mle.cpp
+++ b/src/core/thread/mle.cpp
@@ -2220,9 +2220,10 @@
 
 otError Mle::SendChildUpdateRequest(void)
 {
-    otError      error = OT_ERROR_NONE;
-    Ip6::Address destination;
-    Message *    message = nullptr;
+    otError                 error = OT_ERROR_NONE;
+    Ip6::Address            destination;
+    Message *               message = nullptr;
+    AddressRegistrationMode mode    = kAppendAllAddresses;
 
     if (!mParent.IsStateValidOrRestoring())
     {
@@ -2239,16 +2240,12 @@
     SuccessOrExit(error = AppendHeader(*message, Header::kCommandChildUpdateRequest));
     SuccessOrExit(error = AppendMode(*message, mDeviceMode));
 
-    if (!IsFullThreadDevice())
-    {
-        SuccessOrExit(error = AppendAddressRegistration(*message));
-    }
-
     switch (mRole)
     {
     case kRoleDetached:
         mParentRequestChallenge.GenerateRandom();
         SuccessOrExit(error = AppendChallenge(*message, mParentRequestChallenge));
+        mode = kAppendMeshLocalOnly;
         break;
 
     case kRoleChild:
@@ -2264,6 +2261,11 @@
         OT_UNREACHABLE_CODE(break);
     }
 
+    if (!IsFullThreadDevice())
+    {
+        SuccessOrExit(error = AppendAddressRegistration(*message, mode));
+    }
+
     destination.SetToLinkLocalAddress(mParent.GetExtAddress());
     SuccessOrExit(error = SendMessage(*message, destination));