commit 4dc58da9276db97ef76546f105bd94c9a9d81bc5
author Simon Lin <simonlin@google.com> Thu Sep 12 23:51:39 2019 +0800
committer Jonathan Hui <jonhui@google.com> Thu Sep 12 08:51:39 2019 -0700
tree 6755bd14a875d1b9bb7ece9472beff02d960a2d7
parent 8595924e6c37eb0b8f3b92c04632022bf5ef70ab

[mle] always echo back AR TLV in Child ID/Update Response (#4162)

This commit ensures that a Child ID/Update Response message always
includes an Address Registration TLV when the Child ID/Update Request
message	includes an Address Registration TLV, even when there are no
IPv6 addresses to include.

This commit reverts a change in commit 1133983.

src/core/thread/mle_router.cpp

diff --git a/src/core/thread/mle_router.cpp b/src/core/thread/mle_router.cpp
index ecbc45b..c7646d7 100644
--- a/src/core/thread/mle_router.cpp
+++ b/src/core/thread/mle_router.cpp
@@ -4355,16 +4355,8 @@
         length += entry.GetLength();
     }
 
-    if (length > 0)
-    {
-        tlv.SetLength(length);
-        aMessage.Write(startOffset, sizeof(tlv), &tlv);
-    }
-    else
-    {
-        // remove AddressRegistrationTlv if no address to be echoed back
-        aMessage.SetLength(startOffset);
-    }
+    tlv.SetLength(length);
+    aMessage.Write(startOffset, sizeof(tlv), &tlv);
 
 exit:
     return error;