From 63532b2c9bac673bf7d32e77c05a80831e055d81 Mon Sep 17 00:00:00 2001
From: Arvid Norberg <arvid@libtorrent.org>
Date: Sat, 20 Oct 2012 14:53:54 +0000
Subject: [PATCH] the sack header needs to be removed from a nagle packet or a
 re-sent packet if there are no longer any unordered incoming packets

---
 src/utp_stream.cpp | 4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

diff --git a/src/utp_stream.cpp b/src/utp_stream.cpp
index f54a88139..8216b748b 100644
--- a/src/utp_stream.cpp
+++ b/src/utp_stream.cpp
@@ -1710,7 +1710,9 @@ bool utp_socket_impl::send_pkt(int flags)
 		if (h->extension == 1)
 		{
 			sack = ptr[1];
-			if (m_inbuf.size() == 0 && h->ack_nr != m_ack_nr)
+			// if we no longer have any out-of-order packets waiting
+			// to be delivered, there's no selective ack to be sent.
+			if (m_inbuf.size() == 0)
 			{
 				// we need to remove the sack header
 				remove_sack_header(p);