Set the cache-flush bit for "unique" records in minimal mdns. (#23933)

* Set the cache-flush bit for "unique" records in minimal mdns. There should only be one entity around with a given Matter instance name or Matter hostname, so all records which have those as the QName are part of the unique set. Fixes #23918 * Fix build issue.
project-chip · Dec 6, 2022 · 141df0c · 141df0c
1 parent f71e778
commit 141df0c
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Showing 3 changed files with 15 additions and 8 deletions.
diff --git a/src/lib/dnssd/Advertiser_ImplMinimalMdns.cpp b/src/lib/dnssd/Advertiser_ImplMinimalMdns.cpp
@@ -488,18 +488,19 @@ CHIP_ERROR AdvertiserMinMdns::Advertise(const OperationalAdvertisingParameters &
         return CHIP_ERROR_NO_MEMORY;
     }
 
-    if (!operationalAllocator->AddResponder<SrvResponder>(SrvResourceRecord(instanceName, hostName, params.GetPort()))
-             .SetReportAdditional(hostName)
-             .IsValid())
+    // We are the sole owner of our instanceName, so records keyed on the
+    // instanceName should have the cache-flush bit set.
+    SrvResourceRecord srvRecord(instanceName, hostName, params.GetPort());
+    srvRecord.SetCacheFlush(true);
+    if (!operationalAllocator->AddResponder<SrvResponder>(srvRecord).SetReportAdditional(hostName).IsValid())
     {
         ChipLogError(Discovery, "Failed to add SRV record mDNS responder");
         return CHIP_ERROR_NO_MEMORY;
     }
 
-    if (!operationalAllocator
-             ->AddResponder<TxtResponder>(TxtResourceRecord(instanceName, GetOperationalTxtEntries(operationalAllocator, params)))
-             .SetReportAdditional(hostName)
-             .IsValid())
+    TxtResourceRecord txtRecord(instanceName, GetOperationalTxtEntries(operationalAllocator, params));
+    txtRecord.SetCacheFlush(true);
+    if (!operationalAllocator->AddResponder<TxtResponder>(txtRecord).SetReportAdditional(hostName).IsValid())
     {
         ChipLogError(Discovery, "Failed to add TXT record mDNS responder");
         return CHIP_ERROR_NO_MEMORY;

diff --git a/src/lib/dnssd/minimal_mdns/responders/IP.cpp b/src/lib/dnssd/minimal_mdns/responders/IP.cpp
@@ -40,6 +40,9 @@ void IPv4Responder::AddAllResponses(const chip::Inet::IPPacketInfo * source, Res
         assert(addr.IsIPv4());
 
         IPResourceRecord record(GetQName(), addr);
+        // We're the only thing around with our hostname, so we should set the
+        // cache-flush bit.
+        record.SetCacheFlush(true);
         configuration.Adjust(record);
         delegate->AddResponse(record);
     }
@@ -59,6 +62,9 @@ void IPv6Responder::AddAllResponses(const chip::Inet::IPPacketInfo * source, Res
         assert(addr.IsIPv6());
 
         IPResourceRecord record(GetQName(), addr);
+        // We're the only thing around with our hostname, so we should set the
+        // cache-flush bit.
+        record.SetCacheFlush(true);
         configuration.Adjust(record);
         delegate->AddResponse(record);
     }

diff --git a/src/lib/dnssd/minimal_mdns/responders/tests/TestIPResponder.cpp b/src/lib/dnssd/minimal_mdns/responders/tests/TestIPResponder.cpp
@@ -42,7 +42,7 @@ class IPResponseAccumulator : public ResponderDelegate
     {
 
         NL_TEST_ASSERT(mSuite, (record.GetType() == QType::A) || (record.GetType() == QType::AAAA));
-        NL_TEST_ASSERT(mSuite, record.GetClass() == QClass::IN);
+        NL_TEST_ASSERT(mSuite, record.GetClass() == QClass::IN_FLUSH);
         NL_TEST_ASSERT(mSuite, record.GetName() == kNames);
     }