From eb561bb0c2e0e343670f91735dbdd3ec6470f24e Mon Sep 17 00:00:00 2001
From: orignal <i2porignal@yandex.ru>
Date: Fri, 1 Apr 2022 15:09:35 -0400
Subject: [PATCH] handle Ack ranges

---
 libi2pd/SSU2.cpp | 27 +++++++++++++++++++++++----
 libi2pd/SSU2.h   |  1 +
 2 files changed, 24 insertions(+), 4 deletions(-)

diff --git a/libi2pd/SSU2.cpp b/libi2pd/SSU2.cpp
index efdd54bc..98ab2f1b 100644
--- a/libi2pd/SSU2.cpp
+++ b/libi2pd/SSU2.cpp
@@ -794,17 +794,36 @@ namespace transport
 	void SSU2Session::HandleAck (const uint8_t * buf, size_t len)
 	{
 		if (m_SentPackets.empty ()) return;
+		if (len < 5) return; 
+		// acnt
 		uint32_t ackThrough = bufbe32toh (buf);
-		uint32_t firstPacketNum = ackThrough > buf[4] ? ackThrough - buf[4] : 0; // acnt
+		uint32_t firstPacketNum = ackThrough > buf[4] ? ackThrough - buf[4] : 0; 
+		HandleAckRange (firstPacketNum, ackThrough); // acnt
+		// ranges
+		len -= 5;
+		const uint8_t * ranges = buf + 5;
+		while (len > 0 && firstPacketNum)
+		{
+			uint32_t lastPacketNum = firstPacketNum - 1;
+			if (*ranges > lastPacketNum) break;
+			lastPacketNum -= *ranges; ranges++; // nacks
+			if (*ranges > lastPacketNum) break;
+			firstPacketNum -= *ranges; ranges++; // acks
+			len -= 2;
+			HandleAckRange (firstPacketNum, lastPacketNum);
+		}	
+	}
+
+	void SSU2Session::HandleAckRange (uint32_t firstPacketNum, uint32_t lastPacketNum)
+	{
 		auto it = m_SentPackets.begin ();
 		while (it != m_SentPackets.end () && it->first < firstPacketNum) it++; // find first acked packet
 		if (it == m_SentPackets.end ()) return; // not found
 		auto it1 = it;
-		while (it1 != m_SentPackets.end () && it1->first <= ackThrough) it1++;
+		while (it1 != m_SentPackets.end () && it1->first <= lastPacketNum) it1++;
 		it1--;
 		m_SentPackets.erase (it, it1);
-		// TODO: handle ranges
-	}
+	}	
 		
 	bool SSU2Session::ExtractEndpoint (const uint8_t * buf, size_t size, boost::asio::ip::udp::endpoint& ep)
 	{
diff --git a/libi2pd/SSU2.h b/libi2pd/SSU2.h
index f50aa7b4..f7f73ec2 100644
--- a/libi2pd/SSU2.h
+++ b/libi2pd/SSU2.h
@@ -153,6 +153,7 @@ namespace transport
 			
 			bool HandlePayload (const uint8_t * buf, size_t len); // returns true is contains data
 			void HandleAck (const uint8_t * buf, size_t len);
+			void HandleAckRange (uint32_t firstPacketNum, uint32_t lastPacketNum);
 			bool ExtractEndpoint (const uint8_t * buf, size_t size, boost::asio::ip::udp::endpoint& ep);
 			std::shared_ptr<const i2p::data::RouterInfo> ExtractRouterInfo (const uint8_t * buf, size_t size);
 			void CreateNonce (uint64_t seqn, uint8_t * nonce);