From 2b0d1a2190743135f3a412c0d106b2e520e304d0 Mon Sep 17 00:00:00 2001
From: orignal <i2porignal@yandex.ru>
Date: Tue, 15 Sep 2020 19:39:18 -0400
Subject: [PATCH] implement DatabaseLookupTagSet

---
 libi2pd/ECIESX25519AEADRatchetSession.cpp | 50 +++++++++++++++++++++++
 libi2pd/ECIESX25519AEADRatchetSession.h   | 21 +++++++++-
 libi2pd/Garlic.cpp                        |  3 +-
 3 files changed, 70 insertions(+), 4 deletions(-)

diff --git a/libi2pd/ECIESX25519AEADRatchetSession.cpp b/libi2pd/ECIESX25519AEADRatchetSession.cpp
index 885dc1fc..aef273ed 100644
--- a/libi2pd/ECIESX25519AEADRatchetSession.cpp
+++ b/libi2pd/ECIESX25519AEADRatchetSession.cpp
@@ -99,6 +99,56 @@ namespace garlic
 			m_ExpirationTimestamp = i2p::util::GetSecondsSinceEpoch () + ECIESX25519_PREVIOUS_TAGSET_EXPIRATION_TIMEOUT;
 	}
 
+	bool RatchetTagSet::HandleNextMessage (uint8_t * buf, size_t len, int index)
+	{
+		auto session = GetSession ();
+		if (!session) return false;
+		return session->HandleNextMessage (buf, len, shared_from_this (), index);
+	}	
+
+	DatabaseLookupTagSet::DatabaseLookupTagSet (GarlicDestination * destination, const uint8_t * key):
+		RatchetTagSet (nullptr), m_Destination (destination) 
+	{ 
+		memcpy (m_Key, key, 32); 
+		Expire ();	
+	}
+	
+	bool DatabaseLookupTagSet::HandleNextMessage (uint8_t * buf, size_t len, int index)
+	{
+		if (len < 24) return false;
+		uint8_t nonce[12];
+		memset (nonce, 0, 12); // n = 0
+		size_t offset = 8; // first 8 bytes is reply tag used as AD	
+		len -= 16; // poly1305
+		if (!i2p::crypto::AEADChaCha20Poly1305 (buf + offset, len - offset, buf, 8, m_Key, nonce, buf + offset, len - offset, false)) // decrypt
+		{
+			LogPrint (eLogWarning, "Garlic: Lookup reply AEAD decryption failed");
+			return false;
+		}
+		// we assume 1 I2NP block with delivery type local
+		if (offset + 3 > len) 
+		{	
+			LogPrint (eLogWarning, "Garlic: Lookup reply is too short ", len);
+			return false;
+		}	
+		if (buf[offset] != eECIESx25519BlkGalicClove)
+		{
+			LogPrint (eLogWarning, "Garlic: Lookup reply unexpected block ", (int)buf[offset]);
+			return false;
+		}	
+		offset++;
+		auto size = bufbe16toh (buf + offset);
+		offset += 2;
+		if (offset + size > len) 
+		{
+			LogPrint (eLogWarning, "Garlic: Lookup reply block is too long ", size);
+			return false;
+		}	
+		if (m_Destination)
+			m_Destination->HandleECIESx25519GarlicClove (buf + offset, size);	
+		return true;
+	}	
+	
 	ECIESX25519AEADRatchetSession::ECIESX25519AEADRatchetSession (GarlicDestination * owner, bool attachLeaseSet):
 		GarlicRoutingSession (owner, attachLeaseSet)
 	{
diff --git a/libi2pd/ECIESX25519AEADRatchetSession.h b/libi2pd/ECIESX25519AEADRatchetSession.h
index c7451b98..af0b5de5 100644
--- a/libi2pd/ECIESX25519AEADRatchetSession.h
+++ b/libi2pd/ECIESX25519AEADRatchetSession.h
@@ -40,7 +40,7 @@ namespace garlic
 	// - 16 /* I2NP header */ - 16 /* poly hash */ - 8 /* tag */ - 4 /* garlic length */
 
 	class ECIESX25519AEADRatchetSession;
-	class RatchetTagSet
+	class RatchetTagSet: public std::enable_shared_from_this<RatchetTagSet>
 	{
 		public:
 
@@ -61,7 +61,9 @@ namespace garlic
 
 			void Expire ();
 			bool IsExpired (uint64_t ts) const { return m_ExpirationTimestamp && ts > m_ExpirationTimestamp; };
-			bool IsIndexExpired (int index) const { return m_Session.expired () || index < m_TrimBehindIndex; };
+			virtual bool IsIndexExpired (int index) const { return m_Session.expired () || index < m_TrimBehindIndex; };
+
+			virtual bool HandleNextMessage (uint8_t * buf, size_t len, int index);
 			
 		private:
 
@@ -94,6 +96,21 @@ namespace garlic
 
 			std::shared_ptr<ECIESX25519AEADRatchetSession> m_DummySession; // we need a strong pointer for NS
 	};	
+
+	class DatabaseLookupTagSet: public RatchetTagSet
+	{
+		public:
+
+			DatabaseLookupTagSet (GarlicDestination * destination, const uint8_t * key);
+
+			bool IsIndexExpired (int index) const { return false; };
+			bool HandleNextMessage (uint8_t * buf, size_t len, int index);
+			
+		private:
+
+			GarlicDestination * m_Destination;
+			uint8_t m_Key[32];
+	};	
 	
 	enum ECIESx25519BlockType
 	{
diff --git a/libi2pd/Garlic.cpp b/libi2pd/Garlic.cpp
index 6bdbb630..05d7fd3e 100644
--- a/libi2pd/Garlic.cpp
+++ b/libi2pd/Garlic.cpp
@@ -507,8 +507,7 @@ namespace garlic
 				if (it1 != m_ECIESx25519Tags.end ())
 				{
 					found = true;
-					auto session = it1->second.tagset->GetSession ();
-					if (!session || !session->HandleNextMessage (buf, length, it1->second.tagset, it1->second.index))
+					if (!it1->second.tagset->HandleNextMessage (buf, length, it1->second.index))
 						LogPrint (eLogError, "Garlic: can't handle ECIES-X25519-AEAD-Ratchet message");
 					m_ECIESx25519Tags.erase (it1);
 				}