Added comment on CHIP_CONFIG_MDNS_CACHE_SIZE that if 0, builtin cache

is not used

adding a cast to tests for (NodeId) for clang++.

fixed typos and missing header files for darwin.

removed initializing nullPeerID as per suggestion by as per suggestion
by Damian-Nordic.

restyled whitespace
restyle clang-format

src/lib/core/CHIPConfig.h

@@ -2397,7 +2397,11 @@ extern const char CHIP_NON_PRODUCTION_MARKER[];
 /**
  * @def CHIP_CONFIG_MDNS_CACHE_SIZE
  *
- * @brief Define the size of the MDNS cache
+ * @brief
+ *      Define the size of the MDNS cache
+ *
+ *      If CHIP_CONFIG_MDNS_CACHE_SIZE is 0, the builtin cache is not used.
+ *
  */
 #ifndef CHIP_CONFIG_MDNS_CACHE_SIZE
 #define CHIP_CONFIG_MDNS_CACHE_SIZE 20

src/lib/mdns/Discovery_ImplPlatform.cpp

@@ -20,6 +20,7 @@
 
 #include <inttypes.h>
 
+#include "core/CHIPConfig.h"
 #include "ServiceNaming.h"
 #include "lib/core/CHIPSafeCasts.h"
 #include "lib/mdns/TxtFields.h"
@@ -36,7 +37,9 @@ namespace chip {
 namespace Mdns {
 
 DiscoveryImplPlatform DiscoveryImplPlatform::sManager;
+#if CHIP_CONFIG_MDNS_CACHE_SIZE > 0
 MdnsCache<CHIP_CONFIG_MDNS_CACHE_SIZE> DiscoveryImplPlatform::sMdnsCache;
+#endif
 
 DiscoveryImplPlatform::DiscoveryImplPlatform() = default;
 
@@ -439,11 +442,13 @@ CHIP_ERROR DiscoveryImplPlatform::ResolveNodeId(const PeerId & peerId, Inet::IPA
 {
     ReturnErrorOnFailure(Init());
 
-    Inet::IPaAddress addr;
+#if CHIP_CONFIG_MDNS_CACHE_SIZE > 0
+    Inet::IPAddress addr;
     uint16_t port;
     Inet::InterfaceId iface;
 
     /* see if the entry is cached and use it.... */
+
     if (sMdnsCache.Lookup(peerId, addr, port, iface) == CHIP_NO_ERROR)
     {
         ResolvedNodeData nodeData;
@@ -457,6 +462,7 @@ CHIP_ERROR DiscoveryImplPlatform::ResolveNodeId(const PeerId & peerId, Inet::IPA
 
         return CHIP_NO_ERROR;
     }
+#endif
 
     MdnsService service;
 
@@ -560,6 +566,7 @@ void DiscoveryImplPlatform::HandleNodeIdResolve(void * context, MdnsService * re
         return;
     }
 
+#if CHIP_CONFIG_MDNS_CACHE_SIZE > 0
     // TODO --  define appropriate TTL, for now use 2000 msec (rfc default)
     // figure out way to use TTL value from mDNS packet in  future update
     error = mgr->sMdnsCache.Insert(nodeData.mPeerId, result->mAddress.Value(), result->mPort, result->mInterface, 2 * 1000);
@@ -568,6 +575,7 @@ void DiscoveryImplPlatform::HandleNodeIdResolve(void * context, MdnsService * re
     {
         ChipLogError(Discovery, "MdnsCache insert failed with %s", chip::ErrorStr(error));
     }
+#endif
 
     Platform::CopyString(nodeData.mHostName, result->mHostName);
     nodeData.mInterfaceId = result->mInterface;

src/lib/mdns/Discovery_ImplPlatform.h

@@ -18,11 +18,13 @@
 #pragma once
 
 #include <core/CHIPError.h>
+#include <core/CHIPConfig.h>
 #include <inet/InetInterface.h>
 #include <lib/mdns/Advertiser.h>
 #include <lib/mdns/Resolver.h>
 #include <lib/mdns/platform/Mdns.h>
 #include <platform/CHIPDeviceConfig.h>
+#include <lib/mdns/MdnsCache.h>
 
 // Enable detailed mDNS logging for publish
 #undef DETAIL_LOGGING
@@ -97,6 +99,9 @@ class DiscoveryImplPlatform : public ServiceAdvertiser, public Resolver
     ResolverDelegate * mResolverDelegate = nullptr;
 
     static DiscoveryImplPlatform sManager;
+#if CHIP_CONFIG_MDNS_CACHE_SIZE > 0
+    static MdnsCache <CHIP_CONFIG_MDNS_CACHE_SIZE> sMdnsCache;
+#endif
 };
 
 } // namespace Mdns

src/lib/mdns/MdnsCache.h

@@ -1,3 +1,20 @@
+/*
+ *
+ *    Copyright (c) 2021 Project CHIP Authors
+ *
+ *    Licensed under the Apache License, Version 2.0 (the "License");
+ *    you may not use this file except in compliance with the License.
+ *    You may obtain a copy of the License at
+ *
+ *        http://www.apache.org/licenses/LICENSE-2.0
+ *
+ *    Unless required by applicable law or agreed to in writing, software
+ *    distributed under the License is distributed on an "AS IS" BASIS,
+ *    WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ *    See the License for the specific language governing permissions and
+ *    limitations under the License.
+ */
+
 #pragma once
 
 #include <cstdint>
@@ -26,9 +43,6 @@ class MdnsCache
 public:
     MdnsCache() : elementsUsed(CACHE_SIZE)
     {
-        nullPeerId.SetFabricId(kUndefinedFabricId);
-        nullPeerId.SetNodeId(kUndefinedNodeId);
-
         for (MdnsCacheEntry & e : mLookupTable)
         {
             // each unused entry decrements the count
@@ -130,7 +144,7 @@ class MdnsCache
         uint64_t TTL;        // from mdns record -- units?
         uint64_t expiryTime; // units?
     };
-    PeerId nullPeerId; // indicates a cache entr is unused
+    PeerId nullPeerId; // indicates a cache entry is unused
     int elementsUsed;  // running count of how many entries are used -- for a sanity check
 
     MdnsCacheEntry mLookupTable[CACHE_SIZE];
@@ -157,9 +171,17 @@ class MdnsCache
         for (MdnsCacheEntry & entry : mLookupTable)
         {
             if (entry.peerId == peerId)
-                return &entry;
-            if (entry.peerId != nullPeerId && entry.expiryTime <= current_time)
-            { // ml -- should I use < or <=?
+            {
+                if (entry.expiryTime < current_time)
+                {
+                    MarkEntryUnused(entry);
+                    break; // return nullptr
+                }
+                else
+                    return &entry;
+            }
+            if (entry.peerId != nullPeerId && entry.expiryTime < current_time)
+            {
                 MarkEntryUnused(entry);
             }
         }
@@ -176,7 +198,7 @@ class MdnsCache
 };
 
 #ifndef MDNS_LOGGING
-#undef ChipLogProgress
+#undef MdnsLogProgress
 #endif
 
 } // namespace Mdns

src/lib/mdns/tests/TestMdnsCache.cpp

@@ -69,7 +69,7 @@ void TestInsert(nlTestSuite * inSuite, void * inContext)
         CHIP_ERROR result;
 
         // ml -- why doesn't adding 2 uint16_t give a uint16_t?
-        peerId.SetNodeId(id + i);
+        peerId.SetNodeId((NodeId) id + i);
         result = tMdnsCache.Insert(peerId, addr, (uint16_t)(port + i), iface, 1000 * ttl);
         if (i < sizeOfCache)
         {
@@ -89,7 +89,7 @@ void TestInsert(nlTestSuite * inSuite, void * inContext)
     {
         CHIP_ERROR result;
 
-        peerId.SetNodeId(id + i);
+        peerId.SetNodeId((NodeId) id + i);
         result = tMdnsCache.Insert(peerId, addr, (uint16_t)(port + i), iface, 1000 * ttl);
         NL_TEST_ASSERT(inSuite, result == CHIP_NO_ERROR);
     }
@@ -99,7 +99,7 @@ void TestInsert(nlTestSuite * inSuite, void * inContext)
     {
         CHIP_ERROR result;
 
-        peerId.SetNodeId(id + i);
+        peerId.SetNodeId((NodeId) id + i);
         result = tMdnsCache.Delete(peerId);
         NL_TEST_ASSERT(inSuite, result == CHIP_NO_ERROR);
     }
@@ -113,7 +113,7 @@ void TestInsert(nlTestSuite * inSuite, void * inContext)
     {
         CHIP_ERROR result;
 
-        peerId.SetNodeId(id + i);
+        peerId.SetNodeId((NodeId) id + i);
         result = tMdnsCache.Insert(peerId, addrV6, (uint16_t)(port + i), iface, 1000 * ttl);
         NL_TEST_ASSERT(inSuite, result == CHIP_NO_ERROR);
     }