From 864b170738c44248ad184a6451973aa59fab7ebe Mon Sep 17 00:00:00 2001
From: Pradip De <pradipd@google.com>
Date: Wed, 10 Jul 2024 13:06:33 -0700
Subject: [PATCH] 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                     |  3 +++
 src/app/server/Dnssd.h                       |  1 +
 src/lib/dnssd/Advertiser.h                   | 17 ++++++++++++-----
 src/lib/dnssd/Advertiser_ImplMinimalMdns.cpp |  6 +++---
 src/lib/dnssd/Discovery_ImplPlatform.cpp     |  3 ++-
 5 files changed, 21 insertions(+), 9 deletions(-)

diff --git a/src/app/server/Dnssd.cpp b/src/app/server/Dnssd.cpp
index 3cdcd35f9a7e98..2fc56614e3ab9e 100644
--- a/src/app/server/Dnssd.cpp
+++ b/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,
diff --git a/src/app/server/Dnssd.h b/src/app/server/Dnssd.h
index 105318ca5a08be..3103a2010c03f6 100644
--- a/src/app/server/Dnssd.h
+++ b/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();
 
diff --git a/src/lib/dnssd/Advertiser.h b/src/lib/dnssd/Advertiser.h
index 02888181f98181..88b86ef871b91d 100644
--- a/src/lib/dnssd/Advertiser.h
+++ b/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;
 };
 
diff --git a/src/lib/dnssd/Advertiser_ImplMinimalMdns.cpp b/src/lib/dnssd/Advertiser_ImplMinimalMdns.cpp
index 5ca002673cd4c9..ce46137c9a00e2 100644
--- a/src/lib/dnssd/Advertiser_ImplMinimalMdns.cpp
+++ b/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;
diff --git a/src/lib/dnssd/Discovery_ImplPlatform.cpp b/src/lib/dnssd/Discovery_ImplPlatform.cpp
index beb733b1276a3f..e214aed4f80da6 100644
--- a/src/lib/dnssd/Discovery_ImplPlatform.cpp
+++ b/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