From 9f1a125ed921220e0bdd21a0c5d045612efa91e6 Mon Sep 17 00:00:00 2001
From: orignal <i2porignal@yandex.ru>
Date: Sun, 27 Feb 2022 20:15:14 -0500
Subject: [PATCH] decrypt connID for incoming packet

---
 libi2pd/SSU2.cpp | 34 +++++++++++++++++++++++++++-------
 libi2pd/SSU2.h   | 25 +++++++++++++++++++++++--
 2 files changed, 50 insertions(+), 9 deletions(-)

diff --git a/libi2pd/SSU2.cpp b/libi2pd/SSU2.cpp
index 68921340..7041543b 100644
--- a/libi2pd/SSU2.cpp
+++ b/libi2pd/SSU2.cpp
@@ -8,6 +8,7 @@
 
 #include <string.h>
 #include <openssl/rand.h>
+#include "RouterContext.h"
 #include "Transports.h"
 #include "SSU2.h"
 
@@ -15,10 +16,10 @@ namespace i2p
 {
 namespace transport
 {
-	SSU2Session::SSU2Session (std::shared_ptr<const i2p::data::RouterInfo> in_RemoteRouter,
+	SSU2Session::SSU2Session (SSU2Server& server, std::shared_ptr<const i2p::data::RouterInfo> in_RemoteRouter,
 		std::shared_ptr<const i2p::data::RouterInfo::Address> addr, bool peerTest):
 		TransportSession (in_RemoteRouter, SSU2_TERMINATION_TIMEOUT),
-		m_Address (addr)
+		m_Server (server), m_Address (addr)
 	{
 		m_NoiseState.reset (new i2p::crypto::NoiseSymmetricState);
 		if (in_RemoteRouter && addr)
@@ -41,7 +42,8 @@ namespace transport
 		m_NoiseState->MixKey (sharedSecret);
 
 		Header header;
-		uint8_t headerX[48], payload[1200]; // TODO: correct payload size
+		uint64_t headerX[6];
+		uint8_t payload[1200]; // TODO: correct payload size
 		size_t payloadSize = 8;
 		// fill packet
 		RAND_bytes (header.h.connID, 8);
@@ -50,16 +52,17 @@ namespace transport
 		header.h.flags[0] = 2; // ver
 		header.h.flags[1] = 2; // netID TODO:
 		header.h.flags[2] = 0; // flag
-		RAND_bytes (headerX, 8); // source id
-		memset (headerX + 8, 0, 8); // token
-		memcpy (headerX + 16, m_EphemeralKeys->GetPublicKey (), 32); // X
+		RAND_bytes ((uint8_t *)headerX, 8); // source id
+		memset (headerX + 1, 0, 8); // token
+		memcpy (headerX + 2, m_EphemeralKeys->GetPublicKey (), 32); // X
+		m_Server.AddSession (headerX[0], shared_from_this ());
 		// encrypt
 		const uint8_t nonce[12] = {0};
 		i2p::crypto::AEADChaCha20Poly1305 (payload, payloadSize, m_NoiseState->m_H, 32, m_NoiseState->m_CK + 32, nonce, payload, payloadSize + 16, true);
 		payloadSize += 16;
 		CreateHeaderMask (m_Address->i, payload + (payloadSize - 24), m_Address->i, payload + (payloadSize - 12));
 		EncryptHeader (header);
-		i2p::crypto::ChaCha20 (headerX, 48, m_Address->i, nonce, headerX);
+		i2p::crypto::ChaCha20 ((uint8_t *)headerX, 48, m_Address->i, nonce, (uint8_t *)headerX);
 		
 	}	
 
@@ -76,5 +79,22 @@ namespace transport
 		i2p::crypto::ChaCha20 (data, 8, kh1, nonce1, m_HeaderMask.buf);
 		i2p::crypto::ChaCha20 (data, 8, kh2, nonce2, m_HeaderMask.buf + 8);
 	}	
+
+	void SSU2Server::AddSession (uint64_t connID, std::shared_ptr<SSU2Session> session)
+	{
+		m_Sessions.emplace (connID, session);
+	}	
+
+	void SSU2Server::ProcessNextPacket (uint8_t * buf, size_t len)
+	{
+		uint64_t key = 0, connID;
+		i2p::crypto::ChaCha20 ((uint8_t *)&key, 8, i2p::context.GetNTCP2IV (), buf + (len - 24), (uint8_t *)&key); // TODO: use SSU2 intro key
+		memcpy (&connID, buf, 8);
+		connID ^= key;
+		auto it = m_Sessions.find (connID);
+		if (it != m_Sessions.end ())
+		{
+		}	
+	}	
 }
 }
diff --git a/libi2pd/SSU2.h b/libi2pd/SSU2.h
index d7200926..9897078d 100644
--- a/libi2pd/SSU2.h
+++ b/libi2pd/SSU2.h
@@ -10,6 +10,7 @@
 #define SSU2_H__
 
 #include <memory>
+#include <unordered_map>
 #include "Crypto.h"
 #include "RouterInfo.h"
 #include "TransportSession.h"
@@ -24,7 +25,8 @@ namespace transport
 	{
 		eSSU2SessionRequest = 0
 	};
-	
+
+	class SSU2Server;
 	class SSU2Session: public TransportSession, public std::enable_shared_from_this<SSU2Session>
 	{
 		union Header
@@ -42,7 +44,7 @@ namespace transport
 	
 		public:
 
-			SSU2Session (std::shared_ptr<const i2p::data::RouterInfo> in_RemoteRouter = nullptr,
+			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);
 			~SSU2Session ();
 
@@ -54,6 +56,7 @@ namespace transport
 		
 		private:
 
+			SSU2Server& m_Server;
 			std::shared_ptr<i2p::crypto::X25519Keys> m_EphemeralKeys;
 			std::unique_ptr<i2p::crypto::NoiseSymmetricState> m_NoiseState;
 			std::shared_ptr<const i2p::data::RouterInfo::Address> m_Address;
@@ -64,6 +67,24 @@ namespace transport
 				uint8_t buf[16];
 			} m_HeaderMask;
 	};
+
+	class SSU2Server
+	{
+		public:
+
+			SSU2Server (int port) {};
+			~SSU2Server () {};
+
+			void AddSession (uint64_t connID, std::shared_ptr<SSU2Session> session);
+
+		private:
+
+			void ProcessNextPacket (uint8_t * buf, size_t len);
+			
+		private:
+
+			std::unordered_map<uint64_t, std::shared_ptr<SSU2Session> > m_Sessions;
+	};	
 }
 }