From 0e42d0b8c9cb6464a68ee6aa8a0d9ae10f68f4d2 Mon Sep 17 00:00:00 2001
From: Zhanglong Xia <zhanglongxia@google.com>
Date: Fri, 4 Jan 2019 01:16:04 +0800
Subject: [PATCH] [mac] remove redundant checks (#3408)

---
 src/core/mac/channel_mask.hpp | 22 +++++++++++++++++++---
 src/core/mac/mac.cpp          |  2 --
 2 files changed, 19 insertions(+), 5 deletions(-)

diff --git a/src/core/mac/channel_mask.hpp b/src/core/mac/channel_mask.hpp
index b5189792e..584675315 100644
--- a/src/core/mac/channel_mask.hpp
+++ b/src/core/mac/channel_mask.hpp
@@ -36,6 +36,7 @@
 
 #include "openthread-core-config.h"
 
+#include <limits.h>
 #include <openthread/platform/radio.h>
 
 #include "common/string.hpp"
@@ -140,7 +141,10 @@ public:
      * @returns TRUE if the channel @p aChannel is included in the mask, FALSE otherwise.
      *
      */
-    bool ContainsChannel(uint8_t aChannel) const { return ((1UL << aChannel) & mMask) != 0; }
+    bool ContainsChannel(uint8_t aChannel) const
+    {
+        return (aChannel < sizeof(mMask) * CHAR_BIT) ? ((1UL << aChannel) & mMask) != 0 : false;
+    }
 
     /**
      * This method adds a channel to the channel mask.
@@ -148,7 +152,13 @@ public:
      * @param[in]  aChannel  A channel
      *
      */
-    void AddChannel(uint8_t aChannel) { mMask |= (1UL << aChannel); }
+    void AddChannel(uint8_t aChannel)
+    {
+        if (aChannel < sizeof(mMask) * CHAR_BIT)
+        {
+            mMask |= (1UL << aChannel);
+        }
+    }
 
     /**
      * This method removes a channel from the channel mask.
@@ -156,7 +166,13 @@ public:
      * @param[in]  aChannel  A channel
      *
      */
-    void RemoveChannel(uint8_t aChannel) { mMask &= ~(1UL << aChannel); }
+    void RemoveChannel(uint8_t aChannel)
+    {
+        if (aChannel < sizeof(mMask) * CHAR_BIT)
+        {
+            mMask &= ~(1UL << aChannel);
+        }
+    }
 
     /**
      * This method updates the channel mask by intersecting it with another mask.
diff --git a/src/core/mac/mac.cpp b/src/core/mac/mac.cpp
index 651301b5e..1ed3d8da8 100644
--- a/src/core/mac/mac.cpp
+++ b/src/core/mac/mac.cpp
@@ -355,7 +355,6 @@ otError Mac::SetPanChannel(uint8_t aChannel)
 {
     otError error = OT_ERROR_NONE;
 
-    VerifyOrExit(OT_RADIO_CHANNEL_MIN <= aChannel && aChannel <= OT_RADIO_CHANNEL_MAX, error = OT_ERROR_INVALID_ARGS);
     VerifyOrExit(mSupportedChannelMask.ContainsChannel(aChannel), error = OT_ERROR_INVALID_ARGS);
 
     VerifyOrExit(mPanChannel != aChannel, GetNotifier().SignalIfFirst(OT_CHANGED_THREAD_CHANNEL));
@@ -379,7 +378,6 @@ otError Mac::SetRadioChannel(uint16_t aAcquisitionId, uint8_t aChannel)
 {
     otError error = OT_ERROR_NONE;
 
-    VerifyOrExit(OT_RADIO_CHANNEL_MIN <= aChannel && aChannel <= OT_RADIO_CHANNEL_MAX, error = OT_ERROR_INVALID_ARGS);
     VerifyOrExit(mSupportedChannelMask.ContainsChannel(aChannel), error = OT_ERROR_INVALID_ARGS);
 
     VerifyOrExit(mRadioChannelAcquisitionId && aAcquisitionId == mRadioChannelAcquisitionId,