update introducer's iTag is session to introducer was replaced to new one

libi2pd/RouterContext.cpp

@@ -557,6 +557,12 @@ namespace i2p
 			UpdateRouterInfo ();
 	}
 
+	void RouterContext::UpdateSSU2Introducer (const i2p::data::IdentHash& h, bool v4, uint32_t iTag, uint32_t iExp)
+	{
+		if (m_RouterInfo.UpdateSSU2Introducer (h, v4, iTag, iExp))
+			UpdateRouterInfo ();
+	}	
+		
 	void RouterContext::ClearSSU2Introducers (bool v4)
 	{
 		auto addr = m_RouterInfo.GetSSU2Address (v4);

libi2pd/RouterContext.h

@@ -154,6 +154,7 @@ namespace garlic
 			void PublishSSU2Address (int port, bool publish, bool v4, bool v6);
 			bool AddSSU2Introducer (const i2p::data::RouterInfo::Introducer& introducer, bool v4);
 			void RemoveSSU2Introducer (const i2p::data::IdentHash& h, bool v4);
+			void UpdateSSU2Introducer (const i2p::data::IdentHash& h, bool v4, uint32_t iTag, uint32_t iExp);
 			void ClearSSU2Introducers (bool v4);
 			bool IsUnreachable () const;
 			void SetUnreachable (bool v4, bool v6);

libi2pd/RouterInfo.cpp

@@ -1554,5 +1554,23 @@ namespace data
 		}
 		return false;
 	}
+
+	bool LocalRouterInfo::UpdateSSU2Introducer (const IdentHash& h, bool v4, uint32_t iTag, uint32_t iExp)
+	{
+		auto addresses = GetAddresses ();
+		if (!addresses) return false;
+		auto addr = (*addresses)[v4 ? eSSU2V4Idx : eSSU2V6Idx];
+		if (addr)
+		{
+			for (auto& it: addr->ssu->introducers)
+				if (h == it.iH)
+				{
+					it.iTag = iTag;
+					it.iExp = iExp;
+					return true;
+				}	
+		}
+		return false;
+	}	
 }
 }

libi2pd/RouterInfo.h

@@ -380,6 +380,7 @@ namespace data
 			
 			bool AddSSU2Introducer (const Introducer& introducer, bool v4);
 			bool RemoveSSU2Introducer (const IdentHash& h, bool v4);
+			bool UpdateSSU2Introducer (const IdentHash& h, bool v4, uint32_t iTag, uint32_t iExp);
 
 		private:
 

libi2pd/SSU2.cpp

@@ -1212,14 +1212,14 @@ namespace transport
 	void SSU2Server::UpdateIntroducers (bool v4)
 	{
 		uint32_t ts = i2p::util::GetSecondsSinceEpoch ();
-		std::list<i2p::data::IdentHash> newList, impliedList;
+		std::list<std::pair<i2p::data::IdentHash, uint32_t> > newList, impliedList;
 		auto& introducers = v4 ? m_Introducers : m_IntroducersV6;
 		std::unordered_set<i2p::data::IdentHash> excluded;
-		for (const auto& it : introducers)
+		for (const auto& [ident, tag] : introducers)
 		{
-			std::shared_ptr<SSU2Session> session = FindSession (it);
+			std::shared_ptr<SSU2Session> session = FindSession (ident);
 			if (session)
-				excluded.insert (it);
+				excluded.insert (ident);
 			if (session)
 			{	
 				if (session->IsEstablished () && session->GetRelayTag () && session->IsOutgoing () && // still session with introducer?
@@ -1227,19 +1227,27 @@ namespace transport
 				{	
 					session->SendKeepAlive ();
 					if (ts < session->GetCreationTime () + SSU2_TO_INTRODUCER_SESSION_DURATION)	
-						newList.push_back (it);
+					{	
+						newList.push_back ({ident, session->GetRelayTag ()});
+						if (tag != session->GetRelayTag ())
+						{
+							LogPrint (eLogDebug, "SSU2: Introducer session to  ", session->GetIdentHashBase64() , " was replaced. iTag ", tag, "->", session->GetRelayTag ());
+							i2p::context.UpdateSSU2Introducer (ident, v4, session->GetRelayTag (),
+								session->GetCreationTime () + SSU2_TO_INTRODUCER_SESSION_EXPIRATION);
+						}	
+					}
 					else	
 					{	
-						impliedList.push_back (it); // keep in introducers list, but not publish
+						impliedList.push_back ({ident, session->GetRelayTag ()}); // keep in introducers list, but not publish
 						session = nullptr;	
-					}		
+					}
 				}	
 				else
 					session = nullptr;
 			}	
 			
 			if (!session)
-				i2p::context.RemoveSSU2Introducer (it, v4);
+				i2p::context.RemoveSSU2Introducer (ident, v4);
 		}
 		if (newList.size () < SSU2_MAX_NUM_INTRODUCERS)
 		{
@@ -1249,13 +1257,14 @@ namespace transport
 				// bump creation time for previous introducers if no new sessions found
 				LogPrint (eLogDebug, "SSU2: No new introducers found. Trying to reuse existing");
 				impliedList.clear ();
-				for (auto& it : introducers)
+				for (const auto& [ident, tag] : introducers)
 				{
-					auto session = FindSession (it);
+					auto session = FindSession (ident);
 					if (session && session->IsEstablished () && session->GetRelayTag () && session->IsOutgoing ())
 					{
 						session->SetCreationTime (session->GetCreationTime () + SSU2_TO_INTRODUCER_SESSION_DURATION);
-						if (std::find (newList.begin (), newList.end (), it) == newList.end ())
+						if (std::find_if (newList.begin (), newList.end (), 
+						    [&ident](const auto& s){ return ident == s.first; }) == newList.end ())
 							sessions.push_back (session);
 					}
 				}
@@ -1276,7 +1285,7 @@ namespace transport
 				{
 					LogPrint (eLogDebug, "SSU2: Introducer added ", it->GetRelayTag (), " at ",
 						i2p::data::GetIdentHashAbbreviation (it->GetRemoteIdentity ()->GetIdentHash ()));
-					newList.push_back (it->GetRemoteIdentity ()->GetIdentHash ());
+					newList.push_back ({ it->GetRemoteIdentity ()->GetIdentHash (), tag });
 					if (newList.size () >= SSU2_MAX_NUM_INTRODUCERS) break;
 				}
 			}

libi2pd/SSU2.h

@@ -170,7 +170,7 @@ namespace transport
 			mutable std::mutex m_PendingOutgoingSessionsMutex;
 			std::map<boost::asio::ip::udp::endpoint, std::pair<uint64_t, uint32_t> > m_IncomingTokens, m_OutgoingTokens; // remote endpoint -> (token, expires in seconds)
 			std::unordered_map<uint32_t, std::weak_ptr<SSU2Session> > m_Relays; // we are introducer, relay tag -> session
-			std::list<i2p::data::IdentHash> m_Introducers, m_IntroducersV6; // introducers we are connected to
+			std::list<std::pair<i2p::data::IdentHash, uint32_t> > m_Introducers, m_IntroducersV6; // introducers we are connected to
 			i2p::util::MemoryPoolMt<Packet> m_PacketsPool;
 			i2p::util::MemoryPool<SSU2SentPacket> m_SentPacketsPool;
 			i2p::util::MemoryPool<SSU2IncompleteMessage> m_IncompleteMessagesPool;