From 5aebefe73f55112d4dea2ee23bcd39662aed1054 Mon Sep 17 00:00:00 2001
From: orignal <i2porignal@yandex.ru>
Date: Sun, 1 May 2022 10:33:25 -0400
Subject: [PATCH] connect through introducer

---
 libi2pd/SSU2.cpp | 73 ++++++++++++++++++++++++++++++++++++++++++------
 libi2pd/SSU2.h   | 14 ++++++++--
 2 files changed, 77 insertions(+), 10 deletions(-)

diff --git a/libi2pd/SSU2.cpp b/libi2pd/SSU2.cpp
index 919faf16..9310a172 100644
--- a/libi2pd/SSU2.cpp
+++ b/libi2pd/SSU2.cpp
@@ -28,7 +28,7 @@ namespace transport
 	}	
 	
 	SSU2Session::SSU2Session (SSU2Server& server, std::shared_ptr<const i2p::data::RouterInfo> in_RemoteRouter,
-		std::shared_ptr<const i2p::data::RouterInfo::Address> addr, bool peerTest):
+		std::shared_ptr<const i2p::data::RouterInfo::Address> addr):
 		TransportSession (in_RemoteRouter, SSU2_CONNECT_TIMEOUT),
 		m_Server (server), m_Address (addr), m_DestConnID (0), m_SourceConnID (0),
 		m_State (eSSU2SessionStateUnknown), m_SendPacketNum (0), m_ReceivePacketNum (0),
@@ -52,6 +52,7 @@ namespace transport
 	
 	SSU2Session::~SSU2Session ()
 	{	
+		Terminate ();
 	}
 
 	void SSU2Session::Connect ()
@@ -135,6 +136,7 @@ namespace transport
 		m_SessionConfirmedFragment1.reset (nullptr);
 		SetTerminationTimeout (SSU2_TERMINATION_TIMEOUT);
 		transports.PeerConnected (shared_from_this ());
+		if (m_OnEstablished) m_OnEstablished ();
 	}	
 
 	void SSU2Session::Done ()
@@ -1810,19 +1812,74 @@ namespace transport
 	{
 		if (router && address)
 		{
-			if (address->UsesIntroducer ()) return false; // not implemented yet
-			GetService ().post (
-				[this, router, address]()
-			    {
-					auto session = std::make_shared<SSU2Session> (*this, router, address);
-					session->Connect ();
-				});   
+			if (address->UsesIntroducer ()) 
+				GetService ().post (std::bind (&SSU2Server::ConnectThroughIntroducer, this, router, address));
+			else	
+				GetService ().post (
+					[this, router, address]()
+					{
+						auto session = std::make_shared<SSU2Session> (*this, router, address);
+						session->Connect ();
+					});   
 		}	
 		else
 			return false;
 		return true;
 	}	
 
+	void SSU2Server::ConnectThroughIntroducer (std::shared_ptr<const i2p::data::RouterInfo> router,
+		std::shared_ptr<const i2p::data::RouterInfo::Address> address)
+	{
+		auto session = std::make_shared<SSU2Session> (*this, router, address);
+		session->SetState (eSSU2SessionStateIntroduced);
+		// try to find existing session first
+		for (auto& it: address->ssu->introducers)
+		{
+			auto it1 = m_SessionsByRouterHash.find (it.iKey);
+			if (it1 != m_SessionsByRouterHash.end ())
+			{
+				it1->second->Introduce (session, it.iTag);
+				return;
+			}	
+		}	
+		// we have to start a new session to an introducer
+		std::shared_ptr<i2p::data::RouterInfo> r;
+		uint32_t relayTag = 0;
+		for (auto& it: address->ssu->introducers)
+		{
+			r = i2p::data::netdb.FindRouter (it.iKey);
+			if (r)
+			{
+				relayTag = it.iTag;
+				if (relayTag) break;
+			}	
+		}	
+		if (r)
+		{
+			if (relayTag)
+			{	
+				// introducer and tag  found connect to it through SSU2
+				auto addr = address->IsV6 () ? r->GetSSU2V6Address () : r->GetSSU2V4Address ();
+				if (addr)
+				{
+					auto s = std::make_shared<SSU2Session> (*this, r, addr);
+					s->SetOnEstablished (
+						[session, s, relayTag]()
+						{
+							s->Introduce (session, relayTag);
+						});	
+					s->Connect ();
+				}	
+			}	
+		}
+		else
+		{
+			// introducers not found, try to request them
+			for (auto& it: address->ssu->introducers)
+				i2p::data::netdb.RequestDestination (it.iKey);
+		}	
+	}	
+		
 	void SSU2Server::ScheduleTermination ()
 	{
 		m_TerminationTimer.expires_from_now (boost::posix_time::seconds(SSU2_TERMINATION_CHECK_TIMEOUT));
diff --git a/libi2pd/SSU2.h b/libi2pd/SSU2.h
index ea83b608..a7988054 100644
--- a/libi2pd/SSU2.h
+++ b/libi2pd/SSU2.h
@@ -10,6 +10,7 @@
 #define SSU2_H__
 
 #include <memory>
+#include <functional>
 #include <map>
 #include <set>
 #include <unordered_map>
@@ -130,15 +131,18 @@ namespace transport
 			uint8_t payload[SSU2_MAX_PAYLOAD_SIZE];
 			size_t payloadSize;
 		};	
+
+		typedef std::function<void ()> OnEstablished;
 		
 		public:
 
 			SSU2Session (SSU2Server& server, std::shared_ptr<const i2p::data::RouterInfo> in_RemoteRouter = nullptr,
-				std::shared_ptr<const i2p::data::RouterInfo::Address> addr = nullptr, bool peerTest = false);
+				std::shared_ptr<const i2p::data::RouterInfo::Address> addr = nullptr);
 			~SSU2Session ();
 
 			void SetRemoteEndpoint (const boost::asio::ip::udp::endpoint& ep) { m_RemoteEndpoint = ep; };
 			const boost::asio::ip::udp::endpoint& GetRemoteEndpoint () const { return m_RemoteEndpoint; };
+			void SetOnEstablished (OnEstablished e) { m_OnEstablished = e; };
 			
 			void Connect ();
 			bool Introduce (std::shared_ptr<SSU2Session> session, uint32_t relayTag);
@@ -151,6 +155,8 @@ namespace transport
 			void Resend (uint64_t ts);
 			bool IsEstablished () const { return m_State == eSSU2SessionStateEstablished; };
 			uint64_t GetConnID () const { return m_SourceConnID; };
+			SSU2SessionState GetState () const { return m_State; };
+			void SetState (SSU2SessionState state) { m_State = state; };
 			
 			void ProcessFirstIncomingMessage (uint64_t connID, uint8_t * buf, size_t len);
 			bool ProcessSessionCreated (uint8_t * buf, size_t len);
@@ -222,7 +228,8 @@ namespace transport
 			i2p::I2NPMessagesHandler m_Handler;
 			bool m_IsDataReceived;
 			size_t m_WindowSize;
-			uint32_t m_RelayTag;
+			uint32_t m_RelayTag; // between Bob and Charlie
+			OnEstablished m_OnEstablished; // callback from Established
 	};
 
 	class SSU2Server:  private i2p::util::RunnableServiceWithWork
@@ -290,6 +297,9 @@ namespace transport
 
 			void ScheduleResend ();
 			void HandleResendTimer (const boost::system::error_code& ecode);
+
+			void ConnectThroughIntroducer (std::shared_ptr<const i2p::data::RouterInfo> router,
+				std::shared_ptr<const i2p::data::RouterInfo::Address> address);
 			
 		private: