From 80f982301ca199edfacdd8176f037822a3d144fc Mon Sep 17 00:00:00 2001
From: Yakun Xu <xyk@google.com>
Date: Tue, 13 Aug 2019 01:46:51 +0800
Subject: [PATCH] [dtls] remove unnecessary member variables (#4090)

---
 src/core/meshcop/dtls.cpp | 20 ++++++++------------
 src/core/meshcop/dtls.hpp |  9 ++-------
 2 files changed, 10 insertions(+), 19 deletions(-)

diff --git a/src/core/meshcop/dtls.cpp b/src/core/meshcop/dtls.cpp
index 7079cfbc8..eb3a1d8d8 100644
--- a/src/core/meshcop/dtls.cpp
+++ b/src/core/meshcop/dtls.cpp
@@ -66,8 +66,6 @@ Dtls::Dtls(Instance &aInstance, bool aLayerTwoSecurity)
     , mTimerSet(false)
     , mLayerTwoSecurity(aLayerTwoSecurity)
     , mReceiveMessage(NULL)
-    , mReceiveOffset(0)
-    , mReceiveLength(0)
     , mConnectedHandler(NULL)
     , mReceiveHandler(NULL)
     , mSendHandler(NULL)
@@ -207,7 +205,7 @@ void Dtls::HandleUdpReceive(Message &aMessage, const Ip6::MessageInfo &aMessageI
     }
 #endif
 
-    Receive(aMessage, aMessage.GetOffset(), aMessage.GetLength() - aMessage.GetOffset());
+    Receive(aMessage);
 
 exit:
     return;
@@ -568,11 +566,9 @@ exit:
     return error;
 }
 
-void Dtls::Receive(Message &aMessage, uint16_t aOffset, uint16_t aLength)
+void Dtls::Receive(Message &aMessage)
 {
     mReceiveMessage = &aMessage;
-    mReceiveOffset  = aOffset;
-    mReceiveLength  = aLength;
 
     Process();
 
@@ -644,16 +640,16 @@ int Dtls::HandleMbedtlsReceive(unsigned char *aBuf, size_t aLength)
     }
 #endif // OPENTHREAD_CONFIG_COAP_SECURE_API_ENABLE
 
-    VerifyOrExit(mReceiveMessage != NULL && mReceiveLength != 0, rval = MBEDTLS_ERR_SSL_WANT_READ);
+    VerifyOrExit(mReceiveMessage != NULL && (rval = mReceiveMessage->GetLength() - mReceiveMessage->GetOffset()) > 0,
+                 rval = MBEDTLS_ERR_SSL_WANT_READ);
 
-    if (aLength > mReceiveLength)
+    if (aLength > static_cast<size_t>(rval))
     {
-        aLength = mReceiveLength;
+        aLength = static_cast<size_t>(rval);
     }
 
-    rval = mReceiveMessage->Read(mReceiveOffset, static_cast<uint16_t>(aLength), aBuf);
-    mReceiveOffset += static_cast<uint16_t>(rval);
-    mReceiveLength -= static_cast<uint16_t>(rval);
+    rval = mReceiveMessage->Read(mReceiveMessage->GetOffset(), static_cast<uint16_t>(aLength), aBuf);
+    mReceiveMessage->MoveOffset(rval);
 
 exit:
     return rval;
diff --git a/src/core/meshcop/dtls.hpp b/src/core/meshcop/dtls.hpp
index 31a56bba7..f133eb038 100644
--- a/src/core/meshcop/dtls.hpp
+++ b/src/core/meshcop/dtls.hpp
@@ -364,11 +364,9 @@ public:
      * This method provides a received DTLS message to the DTLS object.
      *
      * @param[in]  aMessage  A reference to the message.
-     * @param[in]  aOffset   The offset within @p aMessage where the DTLS message starts.
-     * @param[in]  aLength   The size of the DTLS message (bytes).
      *
      */
-    void Receive(Message &aMessage, uint16_t aOffset, uint16_t aLength);
+    void Receive(Message &aMessage);
 
     /**
      * This method sets the default message sub-type that will be used for all messages without defined
@@ -488,10 +486,7 @@ private:
 
     bool mLayerTwoSecurity : 1;
 
-    const Message *mReceiveMessage;
-
-    uint16_t mReceiveOffset;
-    uint16_t mReceiveLength;
+    Message *mReceiveMessage;
 
     ConnectedHandler mConnectedHandler;
     ReceiveHandler   mReceiveHandler;