From 563df7dd56fb044071bba8dbb6759938d7e6e427 Mon Sep 17 00:00:00 2001
From: Abtin Keshavarzian <abtink@google.com>
Date: Wed, 20 Nov 2024 10:08:31 -0800
Subject: [PATCH] [secure-transport] reorder member variables to avoid
 alignment gaps (#10946)

This commit reorders the member variables in `SecureTransport`,
grouping booleans and variables of the same size closer to each other
to avoid alignment gaps and allow for better code optimization.
---
 src/core/meshcop/secure_transport.cpp | 17 +++---
 src/core/meshcop/secure_transport.hpp | 74 +++++++++++----------------
 2 files changed, 38 insertions(+), 53 deletions(-)

diff --git a/src/core/meshcop/secure_transport.cpp b/src/core/meshcop/secure_transport.cpp
index 307804e3b..aa2c69c6f 100644
--- a/src/core/meshcop/secure_transport.cpp
+++ b/src/core/meshcop/secure_transport.cpp
@@ -74,20 +74,21 @@ const int SecureTransport::kCipherSuites[][2] = {
 
 SecureTransport::SecureTransport(Instance &aInstance, LinkSecurityMode aLayerTwoSecurity, bool aDatagramTransport)
     : InstanceLocator(aInstance)
-    , mState(kStateClosed)
-    , mCipherSuite(kUnspecifiedCipherSuite)
-    , mPskLength(0)
-    , mVerifyPeerCertificate(true)
-    , mTimer(aInstance, SecureTransport::HandleTimer, this)
-    , mTimerIntermediate(0)
-    , mTimerSet(false)
     , mLayerTwoSecurity(aLayerTwoSecurity)
     , mDatagramTransport(aDatagramTransport)
+    , mTimerSet(false)
+    , mVerifyPeerCertificate(true)
+    , mState(kStateClosed)
+    , mCipherSuite(kUnspecifiedCipherSuite)
+    , mMessageSubType(Message::kSubTypeNone)
+    , mConnectEvent(kDisconnectedError)
+    , mPskLength(0)
     , mMaxConnectionAttempts(0)
     , mRemainingConnectionAttempts(0)
     , mReceiveMessage(nullptr)
     , mSocket(aInstance, *this)
-    , mMessageSubType(Message::kSubTypeNone)
+    , mTimer(aInstance, SecureTransport::HandleTimer, this)
+    , mTimerIntermediate(0)
 {
     ClearAllBytes(mPsk);
     ClearAllBytes(mSsl);
diff --git a/src/core/meshcop/secure_transport.hpp b/src/core/meshcop/secure_transport.hpp
index d31ae7655..ad1be46bc 100644
--- a/src/core/meshcop/secure_transport.hpp
+++ b/src/core/meshcop/secure_transport.hpp
@@ -605,54 +605,38 @@ private:
 
     static const int kCipherSuites[][2];
 
-    State       mState;
-    CipherSuite mCipherSuite;
-
-    uint8_t mPsk[kPskMaxLength];
-    uint8_t mPskLength;
-
-#if OPENTHREAD_CONFIG_TLS_API_ENABLE && defined(MBEDTLS_KEY_EXCHANGE_ECDHE_ECDSA_ENABLED)
-    EcdheEcdsaInfo mEcdheEcdsaInfo;
-#endif
-
-#if OPENTHREAD_CONFIG_TLS_API_ENABLE && defined(MBEDTLS_KEY_EXCHANGE_PSK_ENABLED)
-    PskInfo mPskInfo;
-#endif
-
-    bool mVerifyPeerCertificate;
-
-    mbedtls_ssl_context mSsl;
-    mbedtls_ssl_config  mConf;
-
+    bool                        mLayerTwoSecurity : 1;
+    bool                        mDatagramTransport : 1;
+    bool                        mTimerSet : 1;
+    bool                        mVerifyPeerCertificate : 1;
+    State                       mState;
+    CipherSuite                 mCipherSuite;
+    Message::SubType            mMessageSubType;
+    ConnectEvent                mConnectEvent;
+    uint8_t                     mPskLength;
+    uint16_t                    mMaxConnectionAttempts;
+    uint16_t                    mRemainingConnectionAttempts;
+    Message                    *mReceiveMessage;
+    Ip6::MessageInfo            mMessageInfo;
+    TransportSocket             mSocket;
+    uint8_t                     mPsk[kPskMaxLength];
+    TimerMilliContext           mTimer;
+    TimeMilli                   mTimerIntermediate;
+    Callback<AutoCloseCallback> mAutoCloseCallback;
+    Callback<ConnectedHandler>  mConnectedCallback;
+    Callback<ReceiveHandler>    mReceiveCallback;
+    Callback<TransportCallback> mTransportCallback;
+    mbedtls_ssl_context         mSsl;
+    mbedtls_ssl_config          mConf;
 #if defined(MBEDTLS_SSL_SRV_C) && defined(MBEDTLS_SSL_COOKIE_C)
     mbedtls_ssl_cookie_ctx mCookieCtx;
 #endif
-
-    TimerMilliContext mTimer;
-
-    TimeMilli mTimerIntermediate;
-    bool      mTimerSet : 1;
-
-    bool mLayerTwoSecurity : 1;
-    bool mDatagramTransport : 1;
-
-    uint16_t                    mMaxConnectionAttempts;
-    uint16_t                    mRemainingConnectionAttempts;
-    Callback<AutoCloseCallback> mAutoCloseCallback;
-
-    Message *mReceiveMessage;
-
-    Callback<ConnectedHandler> mConnectedCallback;
-    Callback<ReceiveHandler>   mReceiveCallback;
-
-    Ip6::MessageInfo mMessageInfo;
-    TransportSocket  mSocket;
-
-    Callback<TransportCallback> mTransportCallback;
-
-    Message::SubType mMessageSubType;
-
-    ConnectEvent mConnectEvent;
+#if OPENTHREAD_CONFIG_TLS_API_ENABLE && defined(MBEDTLS_KEY_EXCHANGE_ECDHE_ECDSA_ENABLED)
+    EcdheEcdsaInfo mEcdheEcdsaInfo;
+#endif
+#if OPENTHREAD_CONFIG_TLS_API_ENABLE && defined(MBEDTLS_KEY_EXCHANGE_PSK_ENABLED)
+    PskInfo mPskInfo;
+#endif
 };
 
 } // namespace MeshCoP