Add operational discovery and continuous query support in linux platf…

…orm mdns

src/lib/dnssd/Discovery_ImplPlatform.cpp

@@ -50,7 +50,17 @@ static void HandleNodeResolve(void * context, DnssdService * result, const Span<
     }
 
     DiscoveredNodeData nodeData;
-    result->ToDiscoveredNodeData(addresses, nodeData);
+
+    if (0 == strncmp(result->mType, kOperationalServiceName, sizeof(kOperationalServiceName)))
+    {
+        result->ToDiscoveredOperationalNodeBrowseData(nodeData);
+
+        nodeData.Get<OperationalNodeBrowseData>().LogDetail();
+        discoveryContext->OnNodeDiscovered(nodeData);
+        return;
+    }
+
+    result->ToDiscoveredCommissionNodeData(addresses, nodeData);
 
     nodeData.Get<CommissionNodeData>().LogDetail();
     discoveryContext->OnNodeDiscovered(nodeData);
@@ -75,8 +85,9 @@ static void HandleNodeBrowse(void * context, DnssdService * services, size_t ser
 
         auto & ipAddress = services[i].mAddress;
 
-        // Check if SRV, TXT and AAAA records were received in DNS responses
-        if (strlen(services[i].mHostName) == 0 || services[i].mTextEntrySize == 0 || !ipAddress.has_value())
+        // Check that this is not operational browse result and if SRV, TXT and AAAA records were received in DNS responses
+        if (strncmp(services[i].mType, kOperationalServiceName, sizeof(kOperationalServiceName)) != 0
+            && (strlen(services[i].mHostName) == 0 || services[i].mTextEntrySize == 0 || !ipAddress.has_value()))
         {
             ChipDnssdResolve(&services[i], services[i].mInterface, HandleNodeResolve, context);
         }
@@ -340,7 +351,15 @@ void DiscoveryImplPlatform::HandleNodeIdResolve(void * context, DnssdService * r
     impl->mOperationalDelegate->OnOperationalNodeResolved(nodeData);
 }
 
-void DnssdService::ToDiscoveredNodeData(const Span<Inet::IPAddress> & addresses, DiscoveredNodeData & nodeData)
+void DnssdService::ToDiscoveredOperationalNodeBrowseData(DiscoveredNodeData & nodeData)
+{
+    nodeData.Set<OperationalNodeBrowseData>();
+
+    ExtractIdFromInstanceName(mName, &nodeData.Get<OperationalNodeBrowseData>().peerId);
+    nodeData.Get<OperationalNodeBrowseData>().hasZeroTTL = (mTtlSeconds == 0);
+}
+
+void DnssdService::ToDiscoveredCommissionNodeData(const Span<Inet::IPAddress> & addresses, DiscoveredNodeData & nodeData)
 {
     nodeData.Set<CommissionNodeData>();
     auto & discoveredData = nodeData.Get<CommissionNodeData>();
@@ -746,6 +765,31 @@ CHIP_ERROR DiscoveryImplPlatform::DiscoverCommissioners(DiscoveryFilter filter,
     return error;
 }
 
+CHIP_ERROR DiscoveryImplPlatform::DiscoverOperational(DiscoveryFilter filter, DiscoveryContext & context)
+{
+    ReturnErrorOnFailure(InitImpl());
+    StopDiscovery(context);
+
+    char serviceName[kMaxCommissionerServiceNameSize];
+    ReturnErrorOnFailure(MakeServiceTypeName(serviceName, sizeof(serviceName), filter, DiscoveryType::kOperational));
+
+    intptr_t browseIdentifier;
+    // Increase the reference count of the context to keep it alive until HandleNodeBrowse is called back.
+    CHIP_ERROR error = ChipDnssdBrowse(serviceName, DnssdServiceProtocol::kDnssdProtocolTcp, Inet::IPAddressType::kAny,
+                                       Inet::InterfaceId::Null(), HandleNodeBrowse, context.Retain(), &browseIdentifier);
+
+    if (error == CHIP_NO_ERROR)
+    {
+        context.SetBrowseIdentifier(browseIdentifier);
+    }
+    else
+    {
+        context.Release();
+    }
+
+    return error;
+}
+
 CHIP_ERROR DiscoveryImplPlatform::StartDiscovery(DiscoveryType type, DiscoveryFilter filter, DiscoveryContext & context)
 {
     switch (type)
@@ -755,7 +799,7 @@ CHIP_ERROR DiscoveryImplPlatform::StartDiscovery(DiscoveryType type, DiscoveryFi
     case DiscoveryType::kCommissionerNode:
         return DiscoverCommissioners(filter, context);
     case DiscoveryType::kOperational:
-        return CHIP_ERROR_NOT_IMPLEMENTED;
+        return DiscoverOperational(filter, context);
     default:
         return CHIP_ERROR_INVALID_ARGUMENT;
     }

src/lib/dnssd/Discovery_ImplPlatform.h

@@ -55,6 +55,7 @@ class DiscoveryImplPlatform : public ServiceAdvertiser, public Resolver
     void NodeIdResolutionNoLongerNeeded(const PeerId & peerId) override;
     CHIP_ERROR DiscoverCommissionableNodes(DiscoveryFilter filter, DiscoveryContext & context);
     CHIP_ERROR DiscoverCommissioners(DiscoveryFilter filter, DiscoveryContext & context);
+    CHIP_ERROR DiscoverOperational(DiscoveryFilter filter, DiscoveryContext & context);
     CHIP_ERROR StartDiscovery(DiscoveryType type, DiscoveryFilter filter, DiscoveryContext & context) override;
     CHIP_ERROR StopDiscovery(DiscoveryContext & context) override;
     CHIP_ERROR ReconfirmRecord(const char * hostname, Inet::IPAddress address, Inet::InterfaceId interfaceId) override;

src/lib/dnssd/ServiceNaming.cpp

@@ -162,6 +162,10 @@ CHIP_ERROR MakeServiceTypeName(char * buffer, size_t bufferLen, DiscoveryFilter
         {
             requiredSize = snprintf(buffer, bufferLen, kCommissionerServiceName);
         }
+        else if (type == DiscoveryType::kOperational)
+        {
+            requiredSize = snprintf(buffer, bufferLen, kOperationalServiceName);
+        }
         else
         {
             return CHIP_ERROR_NOT_IMPLEMENTED;

src/lib/dnssd/platform/Dnssd.h

@@ -81,7 +81,8 @@ struct DnssdService
     // Time to live in seconds. Per rfc6762 section 10, because we have a hostname, our default TTL is 120 seconds
     uint32_t mTtlSeconds = 120;
 
-    void ToDiscoveredNodeData(const Span<Inet::IPAddress> & addresses, DiscoveredNodeData & nodeData);
+    void ToDiscoveredCommissionNodeData(const Span<Inet::IPAddress> & addresses, DiscoveredNodeData & nodeData);
+    void ToDiscoveredOperationalNodeBrowseData(DiscoveredNodeData & nodeData);
 };
 
 /**

src/lib/shell/commands/Dns.cpp

@@ -261,6 +261,13 @@ CHIP_ERROR BrowseOperationalHandler(int argc, char ** argv)
     return sResolverProxy.DiscoverOperationalNodes(filter);
 }
 
+CHIP_ERROR BrowseStopHandler(int argc, char ** argv)
+{
+    streamer_printf(streamer_get(), "Stopping browse...\r\n");
+
+    return sResolverProxy.StopDiscovery();
+}
+
 } // namespace
 
 void RegisterDnsCommands()
@@ -270,18 +277,14 @@ void RegisterDnsCommands()
           "Browse Matter commissionables. Usage: dns browse commissionable [subtype]" },
         { &BrowseCommissionerHandler, "commissioner", "Browse Matter commissioners. Usage: dns browse commissioner [subtype]" },
         { &BrowseOperationalHandler, "operational", "Browse Matter operational nodes. Usage: dns browse operational" },
+        { &BrowseStopHandler, "stop", "Stop ongoing browse. USage: dns browse stop"},
+
     };
 
     static constexpr Command subCommands[] = {
         { &ResolveHandler, "resolve",
           "Resolve Matter operational service. Usage: dns resolve fabricid nodeid (e.g. dns resolve 5544332211 1)" },
         { &SubShellCommand<ArraySize(browseSubCommands), browseSubCommands>, "browse", "Browse Matter DNS services" },
-    };
 
     static constexpr Command dnsCommand = { &SubShellCommand<ArraySize(subCommands), subCommands>, "dns", "DNS client commands" };
-
-    Engine::Root().RegisterCommands(&dnsCommand, 1);
-}
-
-} // namespace Shell
 } // namespace chip

src/platform/Darwin/DnssdContexts.cpp

@@ -607,7 +607,7 @@ bool ResolveContext::TryReportingResultsForInterfaceIndex(uint32_t interfaceInde
     {
         auto delegate = static_cast<DiscoverNodeDelegate *>(context);
         DiscoveredNodeData nodeData;
-        service.ToDiscoveredNodeData(addresses, nodeData);
+        service.ToDiscoveredCommissionNodeData(addresses, nodeData);
         delegate->OnNodeDiscovered(nodeData);
     }
     else

src/platform/Linux/DnssdImpl.cpp

@@ -689,6 +689,11 @@ void CopyTypeWithoutProtocol(char (&dest)[N], const char * typeAndProtocol)
 void MdnsAvahi::BrowseRetryCallback(chip::System::Layer * aLayer, void * appState)
 {
     BrowseContext * context = static_cast<BrowseContext *>(appState);
+
+    // free existing browser handle
+    avahi_service_browser_free(context->mBrowser);
+    context->mBrowser = nullptr;
+
     // Don't schedule anything new if we've stopped.
     if (context->mStopped.load())
     {
@@ -743,20 +748,39 @@ void MdnsAvahi::HandleBrowse(AvahiServiceBrowser * browser, AvahiIfIndex interfa
     case AVAHI_BROWSER_ALL_FOR_NOW: {
         ChipLogProgress(DeviceLayer, "Avahi browse: all for now");
         bool needRetries = context->mBrowseRetries++ < kMaxBrowseRetries && !context->mStopped.load();
+
         // If we were already asked to stop, no need to send a callback - no one is listening.
         if (!context->mStopped.load())
         {
             context->mCallback(context->mContext, context->mServices.data(), context->mServices.size(), !needRetries,
                                CHIP_NO_ERROR);
+
+            // Clearing records/services already passed to application through delegate. Keeping it may cause 
+            // duplicates in next query / retry attempt as currently found will also come again from cache. 
+            context->mServices.clear();            
         }
-        avahi_service_browser_free(browser);
+        // hold on to browser handle so we don't lose out any message, this will be freed just before next query 
+        context->mBrowser = browser;
+
         if (needRetries)
         {
             context->mNextRetryDelay *= 2;
             // Hand the ownership of the context over to the timer. It will either schedule a new browse on the context,
             // triggering this function, or it will delete and not reschedule (if stopped).
             DeviceLayer::SystemLayer().StartTimer(context->mNextRetryDelay / 2, BrowseRetryCallback, context);
         }
+        else if (!context->mStopped.load())
+        {
+            // Re-trigger query until StopBrowse() is called
+
+            // Clear retry info and services.
+            context->mNextRetryDelay = chip::System::Clock::Seconds16(1);
+            context->mBrowseRetries = 0;
+            context->mServices.clear();
+            // Hand the ownership of the context over to the timer. It will either schedule a new browse on the context,
+            // triggering this function, or it will delete and not reschedule (if stopped).
+            DeviceLayer::SystemLayer().StartTimer(context->mNextQueryDelay, BrowseRetryCallback, context);
+        }
         else
         {
             // We didn't schedule a timer, so we're responsible for deleting the context
@@ -772,7 +796,24 @@ void MdnsAvahi::HandleBrowse(AvahiServiceBrowser * browser, AvahiIfIndex interfa
                 std::remove_if(context->mServices.begin(), context->mServices.end(), [name, type](const DnssdService & service) {
                     return strcmp(name, service.mName) == 0 && type == GetFullType(service.mType, service.mProtocol);
                 }));
+
+            DnssdService service = {};
+
+            Platform::CopyString(service.mName, name);
+            CopyTypeWithoutProtocol(service.mType, type);
+            service.mProtocol      = GetProtocolInType(type);
+            service.mAddressType   = context->mAddressType;
+            service.mTransportType = ToAddressType(protocol);
+            service.mInterface     = Inet::InterfaceId::Null();
+            if (interface != AVAHI_IF_UNSPEC)
+            {
+                service.mInterface = static_cast<chip::Inet::InterfaceId>(interface);
+            }
+            service.mType[kDnssdTypeMaxSize] = 0;
+            service.mTtlSeconds = 0;
+            context->mCallback(context->mContext, &service, 1, false, CHIP_NO_ERROR);
         }
+
         break;
     case AVAHI_BROWSER_CACHE_EXHAUSTED:
         ChipLogProgress(DeviceLayer, "Avahi browse: cache exhausted");

src/platform/Linux/DnssdImpl.h

@@ -135,7 +135,9 @@ class MdnsAvahi
         AvahiIfIndex mInterface;
         std::string mProtocol;
         chip::System::Clock::Timeout mNextRetryDelay = chip::System::Clock::Seconds16(1);
+        chip::System::Clock::Timeout mNextQueryDelay = chip::System::Clock::Seconds16(60);
         std::atomic_bool mStopped{ false };
+        AvahiServiceBrowser *mBrowser;
     };
 
     struct ResolveContext