Fix DNS-SD TCP advertisement to use a bitmap for Client and Server.

When TCP is enabled, a node, currently, advertises as both a Client and
Server.

src/app/server/Dnssd.cpp

@@ -213,6 +213,9 @@ CHIP_ERROR DnssdServer::AdvertiseOperational()
         AddICDKeyToAdvertisement(advertiseParameters);
 #endif
 
+#if INET_CONFIG_ENABLE_TCP_ENDPOINT
+        advertiseParameters.SetTCPSupportModes(chip::Dnssd::TCPModeAdvertise::kTCPClientServer);
+#endif
         auto & mdnsAdvertiser = chip::Dnssd::ServiceAdvertiser::Instance();
 
         ChipLogProgress(Discovery, "Advertise operational node " ChipLogFormatX64 "-" ChipLogFormatX64,

src/app/server/Dnssd.h

@@ -96,6 +96,7 @@ class DLL_EXPORT DnssdServer : public ICDStateObserver
 
     void SetICDManager(ICDManager * manager) { mICDManager = manager; };
 #endif
+
     /// Start operational advertising
     CHIP_ERROR AdvertiseOperational();
 

src/lib/dnssd/Advertiser.h

@@ -55,6 +55,14 @@ enum class ICDModeAdvertise : uint8_t
     kLIT,  // The ICD is currently operating as a LIT. ICD=1 in DNS-SD key/value pairs.
 };
 
+enum class TCPModeAdvertise : uint16_t
+{
+    kNone            = 0,                         // The device does not support TCP.
+    kTCPClient       = 1 << 1,                    // The device supports the TCP client.
+    kTCPServer       = 1 << 2,                    // The device supports the TCP server.
+    kTCPClientServer = (kTCPClient | kTCPServer), // The device supports both the TCP client and server.
+};
+
 template <class Derived>
 class BaseAdvertisingParams
 {
@@ -102,13 +110,12 @@ class BaseAdvertisingParams
     }
     const std::optional<ReliableMessageProtocolConfig> & GetLocalMRPConfig() const { return mLocalMRPConfig; }
 
-    // NOTE: The SetTcpSupported API is deprecated and not compliant with 1.3. T flag should not be set.
-    Derived & SetTcpSupported(std::optional<bool> tcpSupported)
+    Derived & SetTCPSupportModes(TCPModeAdvertise tcpSupportModes)
     {
-        mTcpSupported = tcpSupported;
+        mTcpSupportModes = tcpSupportModes;
         return *reinterpret_cast<Derived *>(this);
     }
-    std::optional<bool> GetTcpSupported() const { return mTcpSupported; }
+    TCPModeAdvertise GetTCPSupportModes() const { return mTcpSupportModes; }
 
     Derived & SetICDModeToAdvertise(ICDModeAdvertise operatingMode)
     {
@@ -124,7 +131,7 @@ class BaseAdvertisingParams
     uint8_t mMacStorage[kMaxMacSize] = {};
     size_t mMacLength                = 0;
     std::optional<ReliableMessageProtocolConfig> mLocalMRPConfig;
-    std::optional<bool> mTcpSupported;
+    TCPModeAdvertise mTcpSupportModes  = TCPModeAdvertise::kNone;
     ICDModeAdvertise mICDModeAdvertise = ICDModeAdvertise::kNone;
 };
 

src/lib/dnssd/Advertiser_ImplMinimalMdns.cpp

@@ -278,10 +278,10 @@ class AdvertiserMinMdns : public ServiceAdvertiser,
             }
         }
 
-        if (const auto & tcpSupported = params.GetTcpSupported(); tcpSupported.has_value())
+        if (params.GetTCPSupportModes() != TCPModeAdvertise::kNone)
         {
-            size_t writtenCharactersNumber =
-                static_cast<size_t>(snprintf(storage.tcpSupportedBuf, sizeof(storage.tcpSupportedBuf), "T=%d", *tcpSupported));
+            size_t writtenCharactersNumber = static_cast<size_t>(snprintf(storage.tcpSupportedBuf, sizeof(storage.tcpSupportedBuf),
+                                                                          "T=%d", static_cast<int>(params.GetTCPSupportModes())));
             VerifyOrReturnError((writtenCharactersNumber > 0) && (writtenCharactersNumber < sizeof(storage.tcpSupportedBuf)),
                                 CHIP_ERROR_INVALID_STRING_LENGTH);
             txtFields[numTxtFields++] = storage.tcpSupportedBuf;

src/lib/dnssd/Discovery_ImplPlatform.cpp

@@ -240,7 +240,8 @@ CHIP_ERROR CopyTxtRecord(TxtFieldKey key, char * buffer, size_t bufferLen, const
     switch (key)
     {
     case TxtFieldKey::kTcpSupported:
-        return CopyTextRecordValue(buffer, bufferLen, params.GetTcpSupported());
+        VerifyOrReturnError(params.GetTCPSupportModes() != TCPModeAdvertise::kNone, CHIP_ERROR_UNINITIALIZED);
+        return CopyTextRecordValue(buffer, bufferLen, to_underlying(params.GetTCPSupportModes()));
     case TxtFieldKey::kSessionIdleInterval:
 #if CHIP_CONFIG_ENABLE_ICD_SERVER
         // A ICD operating as a LIT should not advertise its slow polling interval