commit 8729bc4dacbb66c421a749974d7a2efb90c94228
author Abtin Keshavarzian <abtink@google.com> Thu Jan 30 19:41:45 2020 -0800
committer Jonathan Hui <jonhui@google.com> Mon Feb 03 09:13:27 2020 -0800
tree 20da6e41265ca5b8cddb12ed5d05e14da3b47d9f
parent c52ef80f4e3b085f18f2f50511ea9df6768e1452

[netif] add helper methods to identify in-use netif address entries (#4520)

src/core/net/netif.cpp

diff --git a/src/core/net/netif.cpp b/src/core/net/netif.cpp
index d401d77..6e14a0f 100644
--- a/src/core/net/netif.cpp
+++ b/src/core/net/netif.cpp
@@ -90,15 +90,13 @@
 {
     for (NetifUnicastAddress *entry = &mExtUnicastAddresses[0]; entry < OT_ARRAY_END(mExtUnicastAddresses); entry++)
     {
-        // To mark the address as unused/available, set the `mNext` to point back to itself.
-        entry->mNext = entry;
+        entry->MarkAsNotInUse();
     }
 
     for (NetifMulticastAddress *entry = &mExtMulticastAddresses[0]; entry < OT_ARRAY_END(mExtMulticastAddresses);
          entry++)
     {
-        // To mark the address as unused/available, set the `mNext` to point back to itself.
-        entry->mNext = entry;
+        entry->MarkAsNotInUse();
     }
 }
 
@@ -342,13 +340,11 @@
 
     VerifyOrExit(aIterator < num);
 
-    // Find an available entry in the `mExtMulticastAddresses` array.
     for (uint8_t i = aIterator; i < num; i++)
     {
         const NetifMulticastAddress &entry = mExtMulticastAddresses[i];
 
-        // In an unused/available entry, `mNext` points back to the entry itself.
-        if (entry.mNext != &entry)
+        if (entry.IsInUse())
         {
             aAddress  = entry.GetAddress();
             aIterator = i + 1;
@@ -378,11 +374,9 @@
 
     VerifyOrExit(!IsMulticastSubscribed(aAddress), error = OT_ERROR_ALREADY);
 
-    // Find an available entry in the `mExtMulticastAddresses` array.
     for (entry = &mExtMulticastAddresses[0]; entry < OT_ARRAY_END(mExtMulticastAddresses); entry++)
     {
-        // In an unused/available entry, `mNext` points back to the entry itself.
-        if (entry->mNext == entry)
+        if (!entry->IsInUse())
         {
             break;
         }
@@ -429,8 +423,7 @@
 
     VerifyOrExit(entry != NULL, error = OT_ERROR_NOT_FOUND);
 
-    // To mark the address entry as unused/available, set the `mNext` pointer back to the entry itself.
-    entry->mNext = entry;
+    entry->MarkAsNotInUse();
 
     Get<Notifier>().Signal(OT_CHANGED_IP6_MULTICAST_UNSUBSCRIBED);
 
@@ -443,8 +436,7 @@
     for (NetifMulticastAddress *entry = &mExtMulticastAddresses[0]; entry < OT_ARRAY_END(mExtMulticastAddresses);
          entry++)
     {
-        // In unused entries, the `mNext` points back to the entry itself.
-        if (entry->mNext != entry)
+        if (entry->IsInUse())
         {
             UnsubscribeExternalMulticast(entry->GetAddress());
         }
@@ -508,11 +500,9 @@
         }
     }
 
-    // Find an available entry in the `mExtUnicastAddresses` array.
     for (entry = &mExtUnicastAddresses[0]; entry < OT_ARRAY_END(mExtUnicastAddresses); entry++)
     {
-        // In an unused/available entry, `mNext` points back to the entry itself.
-        if (entry->mNext == entry)
+        if (!entry->IsInUse())
         {
             break;
         }
@@ -560,8 +550,7 @@
 
     VerifyOrExit(entry != NULL, error = OT_ERROR_NOT_FOUND);
 
-    // To mark the address entry as unused/available, set the `mNext` pointer back to the entry itself.
-    entry->mNext = entry;
+    entry->MarkAsNotInUse();
 
     Get<Notifier>().Signal(OT_CHANGED_IP6_ADDRESS_REMOVED);
 
@@ -573,8 +562,7 @@
 {
     for (NetifUnicastAddress *entry = &mExtUnicastAddresses[0]; entry < OT_ARRAY_END(mExtUnicastAddresses); entry++)
     {
-        // In unused entries, the `mNext` points back to the entry itself.
-        if (entry->mNext != entry)
+        if (entry->IsInUse())
         {
             RemoveExternalUnicastAddress(entry->GetAddress());
         }

src/core/net/netif.hpp

diff --git a/src/core/net/netif.hpp b/src/core/net/netif.hpp
index 853ab55..1dd4f8e 100644
--- a/src/core/net/netif.hpp
+++ b/src/core/net/netif.hpp
@@ -100,6 +100,12 @@
     {
         return mScopeOverrideValid ? static_cast<uint8_t>(mScopeOverride) : GetAddress().GetScope();
     }
+
+private:
+    // In an unused/available entry (i.e., entry not present in a linked
+    // list), the next pointer is set to point back to the entry itself.
+    bool IsInUse(void) const { return GetNext() != this; }
+    void MarkAsNotInUse(void) { SetNext(this); }
 };
 
 /**
@@ -151,6 +157,12 @@
     {
         return static_cast<NetifMulticastAddress *>(const_cast<otNetifMulticastAddress *>(mNext));
     }
+
+private:
+    // In an unused/available entry (i.e., entry not present in a linked
+    // list), the next pointer is set to point back to the entry itself.
+    bool IsInUse(void) const { return GetNext() != this; }
+    void MarkAsNotInUse(void) { mNext = this; }
 };
 
 /**