From 9c9b723cf5b5f4e8a1cc1bea3cc2d505a796f7af Mon Sep 17 00:00:00 2001
From: orignal <i2porignal@yandex.ru>
Date: Thu, 20 Feb 2020 15:44:09 -0500
Subject: [PATCH] delete expired ECIESX25519AEADRatchet sessions and tags

---
 libi2pd/ECIESX25519AEADRatchetSession.cpp |  1 +
 libi2pd/ECIESX25519AEADRatchetSession.h   |  8 +++++
 libi2pd/Garlic.cpp                        | 36 +++++++++++++++++++++--
 libi2pd/Garlic.h                          |  1 +
 4 files changed, 43 insertions(+), 3 deletions(-)

diff --git a/libi2pd/ECIESX25519AEADRatchetSession.cpp b/libi2pd/ECIESX25519AEADRatchetSession.cpp
index 7f17130c..d2d07343 100644
--- a/libi2pd/ECIESX25519AEADRatchetSession.cpp
+++ b/libi2pd/ECIESX25519AEADRatchetSession.cpp
@@ -401,6 +401,7 @@ namespace garlic
 
 	bool ECIESX25519AEADRatchetSession::HandleNextMessage (const uint8_t * buf, size_t len, int index)
 	{
+		m_LastActivityTimestamp = i2p::util::GetSecondsSinceEpoch ();
 		switch (m_State)
 		{
 			case eSessionStateEstablished:
diff --git a/libi2pd/ECIESX25519AEADRatchetSession.h b/libi2pd/ECIESX25519AEADRatchetSession.h
index 90e21e8a..e5836cd4 100644
--- a/libi2pd/ECIESX25519AEADRatchetSession.h
+++ b/libi2pd/ECIESX25519AEADRatchetSession.h
@@ -55,6 +55,10 @@ namespace garlic
 		eECIESx25519BlkPadding = 254	
 	};	
 
+
+	const int ECIESX25519_RESTART_TIMEOUT = 120; // number of second of inactivity we should restart after
+	const int ECIESX25519_EXPIRATION_TIMEOUT = 600; // in seconds
+
     class ECIESX25519AEADRatchetSession: public GarlicRoutingSession, public std::enable_shared_from_this<ECIESX25519AEADRatchetSession>
     {
         enum SessionState
@@ -81,6 +85,9 @@ namespace garlic
 				if (!m_Destination) m_Destination.reset (new i2p::data::IdentHash (dest));
 			}
 			
+			bool IsExpired (uint64_t ts) const { return ts > m_LastActivityTimestamp + ECIESX25519_EXPIRATION_TIMEOUT; }
+			bool CanBeRestarted (uint64_t ts) const { return ts > m_LastActivityTimestamp + ECIESX25519_RESTART_TIMEOUT; }
+
         private:
 
 			void ResetKeys ();
@@ -109,6 +116,7 @@ namespace garlic
 			uint8_t m_Aepk[32]; // Alice's ephemeral keys TODO: for incoming only
             i2p::crypto::X25519Keys m_EphemeralKeys;
             SessionState m_State = eSessionStateNew;
+			uint64_t m_LastActivityTimestamp = 0; // incoming
             RatchetTagSet m_SendTagset, m_ReceiveTagset;
 			int m_NumReceiveTags = 0;
 			std::unique_ptr<i2p::data::IdentHash> m_Destination;// TODO: might not need it 
diff --git a/libi2pd/Garlic.cpp b/libi2pd/Garlic.cpp
index 14154eaf..4828ad67 100644
--- a/libi2pd/Garlic.cpp
+++ b/libi2pd/Garlic.cpp
@@ -739,7 +739,25 @@ namespace garlic
 					++it;
 			}
 		}
-		// TODO: cleanup ECIESx25519
+		// ECIESx25519
+		for (auto it = m_ECIESx25519Tags.begin (); it != m_ECIESx25519Tags.end ();)
+		{
+			if (ts > it->second.creationTime + INCOMING_TAGS_EXPIRATION_TIMEOUT)
+				it = m_ECIESx25519Tags.erase (it);
+			else
+				++it;	
+		}
+
+		for (auto it = m_ECIESx25519Sessions.begin (); it != m_ECIESx25519Sessions.end ();)
+		{
+			if (it->second->IsExpired (ts))
+			{
+				it->second->SetOwner (nullptr);
+				it = m_ECIESx25519Sessions.erase (it);
+			}	
+			else
+				++it;
+		}
 	}
 
 	void GarlicDestination::RemoveDeliveryStatusSession (uint32_t msgID)
@@ -940,12 +958,24 @@ namespace garlic
 
     void GarlicDestination::AddECIESx25519SessionTag (int index, uint64_t tag, ECIESX25519AEADRatchetSessionPtr session)
     {
-        m_ECIESx25519Tags.emplace (tag, ECIESX25519AEADRatchetIndexSession{index, session});
+        m_ECIESx25519Tags.emplace (tag, ECIESX25519AEADRatchetIndexSession{index, session, i2p::util::GetSecondsSinceEpoch ()});
     }
 
 	void GarlicDestination::AddECIESx25519Session (const uint8_t * staticKey, ECIESX25519AEADRatchetSessionPtr session)
 	{
-		m_ECIESx25519Sessions.emplace (staticKey, session);
+		i2p::data::Tag<32> staticKeyTag (staticKey);
+		auto it = m_ECIESx25519Sessions.find (staticKeyTag);
+		if (it != m_ECIESx25519Sessions.end ())
+		{	
+			if (it->second->CanBeRestarted (i2p::util::GetSecondsSinceEpoch ()))
+				m_ECIESx25519Sessions.erase (it);
+			else
+			{
+				LogPrint (eLogInfo, "Garlic:  ECIESx25519 session with static key ", staticKeyTag.ToBase64 (), " already exists");	
+				return;
+			}	
+		}
+		m_ECIESx25519Sessions.emplace (staticKeyTag, session);
 	}
 
 }
diff --git a/libi2pd/Garlic.h b/libi2pd/Garlic.h
index 4fdb299e..9c256b48 100644
--- a/libi2pd/Garlic.h
+++ b/libi2pd/Garlic.h
@@ -202,6 +202,7 @@ namespace garlic
 	{ 
 		int index; 
 		ECIESX25519AEADRatchetSessionPtr session; 
+		uint64_t creationTime; // seconds since epoch
 	};
 
 	class GarlicDestination: public i2p::data::LocalDestination