From e3be45ec50c930b65ccc7cdb1fec8dd8694051ec Mon Sep 17 00:00:00 2001
From: orignal <i2porignal@yandex.ru>
Date: Wed, 9 Sep 2026 10:45:52 -0400
Subject: [PATCH] receive I2P_PEX messages

---
 libi2pd_client/Torrents.cpp | 33 +++++++++++++++++++++++++++++++--
 libi2pd_client/Torrents.h   |  5 ++++-
 2 files changed, 35 insertions(+), 3 deletions(-)

diff --git a/libi2pd_client/Torrents.cpp b/libi2pd_client/Torrents.cpp
index cd95c260..26599ed2 100644
--- a/libi2pd_client/Torrents.cpp
+++ b/libi2pd_client/Torrents.cpp
@@ -932,8 +932,8 @@ namespace torrents
 		m_IsHandshakeSent (false), m_IsEstablished (false), m_IsChoked (true), m_IsRemoteChoked (true),
 		m_IsInterested (false), m_IsRemoteInterested (false), m_LastReceiveTime (0), m_LastSendTime (0),
 		m_NumRequests (0), m_NumPieces (0), m_LastRequestedPieceIndex (-1),
-		m_RemoteMsgIDUtMetadata (0), m_RemoteMetadataSize (0), m_IsFast (false),
-		m_SuggestedPieceIndex (-1), m_Downloaded (0), m_Uploaded (0)
+		m_RemoteMsgIDUtMetadata (0), m_RemoteMsgIDI2PPEX (0), m_RemoteMetadataSize (0),
+		m_IsFast (false), m_SuggestedPieceIndex (-1), m_Downloaded (0), m_Uploaded (0)
 	{
 		ResetStats ();
 	}
@@ -1830,6 +1830,11 @@ namespace torrents
 			m_ExtendedMessageHandlers.emplace (EXTENSION_MSGID_UT_METADATA, &PeerConnection::HandleUtMetadataExtension);
 			m_RemoteMsgIDUtMetadata = msgID;
 		}
+		else if (extensionName == EXTENSION_NAME_I2P_PEX)
+		{
+			m_ExtendedMessageHandlers.emplace (EXTENSION_MSGID_I2P_PEX, &PeerConnection::HandleI2PPEXExtension);
+			m_RemoteMsgIDI2PPEX = msgID;
+		}
 	}
 
 	void PeerConnection::SendExtendedMsg (uint8_t extendedMsgID, std::string_view payload, std::string_view data)
@@ -1839,6 +1844,7 @@ namespace torrents
 		{
 			str = CreateDictionary ({
 				{ "m", CreateDictionary ({
+					{ EXTENSION_NAME_I2P_PEX, CreateInteger (EXTENSION_MSGID_I2P_PEX) },
 					{ EXTENSION_NAME_UT_METADATA, CreateInteger (EXTENSION_MSGID_UT_METADATA) }
 										  }) },
 				{ "metadata_size",  CreateInteger (m_Torrent->GetInfo ().size ()) },
@@ -1902,6 +1908,7 @@ namespace torrents
 				}
 				case 1: // data
 				{
+					if (m_Torrent->GetLength ()) break; // we have info
 					size_t offset = piece*REQUEST_BLOCK_SIZE;
 					if (offset > m_RemoteMetadataSize) break;
 					size_t size = m_RemoteMetadataSize - offset;
@@ -1938,6 +1945,28 @@ namespace torrents
 		}
 	}
 
+	void PeerConnection::HandleI2PPEXExtension (const uint8_t * buf, size_t len)
+	{
+		std::unordered_set<i2p::data::IdentHash> newPeers;
+		ParseDictionary (std::string_view ((const char *)buf, len),
+			[&newPeers](std::string_view key, std::string_view buf)->size_t
+			{
+				if (key == "added")
+				{
+					auto [idents, l] = ExtractByteString (buf);
+					if (l && !(l & 0x20))
+						while (!idents.empty ())
+						{
+							newPeers.emplace (i2p::data::IdentHash ((const uint8_t *)idents.substr (0, i2p::data::IdentHash::len).data ()));
+							idents = idents.substr (i2p::data::IdentHash::len);
+						};
+					return l;
+				}
+				return 0;
+			});
+		LogPrint (eLogDebug, "Torrents: I2P_PEX ", newPeers.size (), " added peers received");
+	}
+
 	std::optional<RequestedBlock> PeerConnection::GetNextBlockToRequest ()
 	{
 		auto block = m_Torrent->GetNextBlockToRequest (shared_from_this (), true); // skip already requested pieces
diff --git a/libi2pd_client/Torrents.h b/libi2pd_client/Torrents.h
index e6f1b555..91fce6c2 100644
--- a/libi2pd_client/Torrents.h
+++ b/libi2pd_client/Torrents.h
@@ -64,6 +64,8 @@ namespace torrents
 	// extensions
 	constexpr std::string_view EXTENSION_NAME_UT_METADATA { "ut_metadata" };
 	constexpr uint8_t EXTENSION_MSGID_UT_METADATA = 1;
+	constexpr std::string_view EXTENSION_NAME_I2P_PEX { "i2p_pex" };
+	constexpr uint8_t EXTENSION_MSGID_I2P_PEX = 2;
 
 	enum MessageType
 	{
@@ -354,6 +356,7 @@ namespace torrents
 			void SendExtendedMsg (uint8_t extendedMsgID = 0, std::string_view payload = "", std::string_view data = "");
 			void AddExtendedMsgHandler (std::string_view extensionName, int64_t msgID);
 			void HandleUtMetadataExtension (const uint8_t * buf, size_t len); // BEP9
+			void HandleI2PPEXExtension (const uint8_t * buf, size_t len); // BEP11
 
 			std::optional<RequestedBlock> GetNextBlockToRequest ();
 			bool RequestNextBlocks ();
@@ -378,7 +381,7 @@ namespace torrents
 			std::unique_ptr<boost::asio::steady_timer> m_HandshakeReceiveTimer;
 			// BEP10
 			std::unordered_map<uint8_t, PeerConnection::ExtendedMessageHandler> m_ExtendedMessageHandlers;
-			uint8_t m_RemoteMsgIDUtMetadata;
+			uint8_t m_RemoteMsgIDUtMetadata, m_RemoteMsgIDI2PPEX;
 			// BEP9
 			size_t m_RemoteMetadataSize;
 			std::vector<uint8_t> m_RemoteMetadata;