[dnssd] Make sure initialization is not run twice

Currently, the platform implementation of DNS-SD uses a boolean member to indicate if the backend has already been initialized, but the initialization is asynchronous so it may happen that the initialization is invoked twice. Add another "initializing" state to handle that case.
project-chip · Jan 27, 2023 · 37365d8 · 37365d8
1 parent 9dbf432
commit 37365d8
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Showing 2 changed files with 16 additions and 12 deletions.
diff --git a/src/lib/dnssd/Discovery_ImplPlatform.cpp b/src/lib/dnssd/Discovery_ImplPlatform.cpp
@@ -358,20 +358,21 @@ DiscoveryImplPlatform::DiscoveryImplPlatform() = default;
 
 CHIP_ERROR DiscoveryImplPlatform::InitImpl()
 {
-    ReturnErrorCodeIf(mDnssdInitialized, CHIP_NO_ERROR);
-    ReturnErrorOnFailure(ChipDnssdInit(HandleDnssdInit, HandleDnssdError, this));
+    VerifyOrReturnError(mState == State::kUninitialized, CHIP_NO_ERROR);
+    mState = State::kInitializing;
 
+    ReturnErrorOnFailure(ChipDnssdInit(HandleDnssdInit, HandleDnssdError, this));
     UpdateCommissionableInstanceName();
 
     return CHIP_NO_ERROR;
 }
 
 void DiscoveryImplPlatform::Shutdown()
 {
-    VerifyOrReturn(mDnssdInitialized);
+    VerifyOrReturn(mState != State::kUninitialized);
     mResolverProxy.Shutdown();
     ChipDnssdShutdown();
-    mDnssdInitialized = false;
+    mState = State::kUninitialized;
 }
 
 void DiscoveryImplPlatform::HandleDnssdInit(void * context, CHIP_ERROR initError)
@@ -380,7 +381,7 @@ void DiscoveryImplPlatform::HandleDnssdInit(void * context, CHIP_ERROR initError
 
     if (initError == CHIP_NO_ERROR)
     {
-        publisher->mDnssdInitialized = true;
+        publisher->mState = State::kInitialized;
 
         // TODO: this is wrong, however we need resolverproxy initialized
         // otherwise DiscoveryImplPlatform is not usable.
@@ -409,14 +410,12 @@ void DiscoveryImplPlatform::HandleDnssdInit(void * context, CHIP_ERROR initError
     else
     {
         ChipLogError(Discovery, "DNS-SD initialization failed with %" CHIP_ERROR_FORMAT, initError.Format());
-        publisher->mDnssdInitialized = false;
+        publisher->mState = State::kUninitialized;
     }
 }
 
 void DiscoveryImplPlatform::HandleDnssdError(void * context, CHIP_ERROR error)
 {
-    DiscoveryImplPlatform * publisher = static_cast<DiscoveryImplPlatform *>(context);
-
     if (error == CHIP_ERROR_FORCED_RESET)
     {
         DeviceLayer::ChipDeviceEvent event;
@@ -487,7 +486,7 @@ CHIP_ERROR DiscoveryImplPlatform::PublishService(const char * serviceType, TextE
                                                  Inet::InterfaceId interfaceId, const chip::ByteSpan & mac,
                                                  DnssdServiceProtocol protocol, PeerId peerId)
 {
-    ReturnErrorCodeIf(mDnssdInitialized == false, CHIP_ERROR_INCORRECT_STATE);
+    VerifyOrReturnError(mState == State::kInitialized, CHIP_ERROR_INCORRECT_STATE);
 
     DnssdService service;
     ReturnErrorOnFailure(MakeHostName(service.mHostName, sizeof(service.mHostName), mac));

diff --git a/src/lib/dnssd/Discovery_ImplPlatform.h b/src/lib/dnssd/Discovery_ImplPlatform.h
@@ -64,6 +64,13 @@ class DiscoveryImplPlatform : public ServiceAdvertiser, public Resolver
     static DiscoveryImplPlatform & GetInstance();
 
 private:
+    enum class State : uint8_t
+    {
+        kUninitialized,
+        kInitializing,
+        kInitialized
+    };
+
     DiscoveryImplPlatform();
 
     DiscoveryImplPlatform(const DiscoveryImplPlatform &) = delete;
@@ -83,10 +90,8 @@ class DiscoveryImplPlatform : public ServiceAdvertiser, public Resolver
                               size_t subTypeSize, uint16_t port, Inet::InterfaceId interfaceId, const chip::ByteSpan & mac,
                               DnssdServiceProtocol procotol, PeerId peerId);
 
+    State mState = State::kUninitialized;
     uint8_t mCommissionableInstanceName[sizeof(uint64_t)];
-
-    bool mDnssdInitialized = false;
-
     ResolverProxy mResolverProxy;
 
     static DiscoveryImplPlatform sManager;