create I2NP tunnel message for first fragment

libi2pd/SSU2Session.cpp

@@ -1766,8 +1766,8 @@ namespace transport
 
 	void SSU2Session::HandleFirstFragment (const uint8_t * buf, size_t len)
 	{
+		auto msg = (buf[0] == eI2NPTunnelData) ? NewI2NPTunnelMessage (true) : NewI2NPShortMessage ();
 		uint32_t msgID; memcpy (&msgID, buf + 1, 4);
-		auto msg = NewI2NPShortMessage ();
 		// same format as I2NP message block
 		msg->len = msg->offset + len + 7;
 		memcpy (msg->GetNTCP2Header (), buf, len);