From 8c89c8368af4d8739024956f5d63096f2e6f637b Mon Sep 17 00:00:00 2001
From: orignal <i2porignal@yandex.ru>
Date: Tue, 24 Jun 2025 22:06:36 -0400
Subject: [PATCH] handle Datagram3

---
 libi2pd/Datagram.cpp | 22 +++++++++++++++++++++-
 libi2pd/Datagram.h   |  2 ++
 2 files changed, 23 insertions(+), 1 deletion(-)

diff --git a/libi2pd/Datagram.cpp b/libi2pd/Datagram.cpp
index 1903f7ae..de4b5674 100644
--- a/libi2pd/Datagram.cpp
+++ b/libi2pd/Datagram.cpp
@@ -129,6 +129,11 @@ namespace datagram
 	void DatagramDestination::HandleDatagram3 (uint16_t fromPort, uint16_t toPort, const uint8_t * buf, size_t len,
 		i2p::garlic::ECIESX25519AEADRatchetSession * from)
 	{
+		if (len < 34)
+		{
+			LogPrint (eLogWarning, "Datagram: datagram3 is too short ", len);
+			return;
+		}	
 		if (from)
 		{
 			i2p::data::IdentHash ident(buf);
@@ -142,7 +147,22 @@ namespace datagram
 					auto session = ObtainSession (ident);
 					session->SetRemoteLeaseSet (ls);
 					session->Ack ();
-					// TODO:
+					auto r = FindReceiver(toPort);
+					if (r)
+					{
+						uint16_t flags = bufbe16toh (buf + 32);
+						size_t offset = 34;
+						if (flags & DATAGRAM3_FLAG_OPTIONS)
+							offset += bufbe16toh (buf + offset) + 2;
+						if (offset > len)
+						{
+							LogPrint (eLogWarning, "Datagram: datagram3 is too short ", len, " expected ", offset);
+							return;
+						}	
+						r(*ls->GetIdentity (), fromPort, toPort, buf + offset, len - offset);
+					}	
+					else
+						LogPrint (eLogWarning, "Datagram: no receiver for port ", toPort);
 				}	
 				else
 					LogPrint (eLogError, "Datagram: Remote LeaseSet static key mismatch for datagram3 from ", ident.ToBase32 ());
diff --git a/libi2pd/Datagram.h b/libi2pd/Datagram.h
index d68bdd07..a293c84b 100644
--- a/libi2pd/Datagram.h
+++ b/libi2pd/Datagram.h
@@ -45,6 +45,8 @@ namespace datagram
 	const uint64_t DATAGRAM_MAX_FLUSH_INTERVAL = 5; // in milliseconds
 	const int DATAGRAM_SESSION_ACK_REQUEST_INTERVAL = 5500; // in milliseconds
 
+	constexpr uint16_t DATAGRAM3_FLAG_OPTIONS = 0x10;
+	
 	class DatagramSession : public std::enable_shared_from_this<DatagramSession>
 	{