From 951f13c2fdf24585444b994c96a20fcb48b03fef Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Levente=20M=C3=A9sz=C3=A1ros?= <levy@omnetpp.org>
Date: Tue, 23 Jan 2024 07:00:37 -0800
Subject: [PATCH] tcp: (fixes #987) Fix retransmission of wrong segment

---
 src/internet/model/tcp-socket-base.cc | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/src/internet/model/tcp-socket-base.cc b/src/internet/model/tcp-socket-base.cc
index c305f278d..1cbf3d9d5 100644
--- a/src/internet/model/tcp-socket-base.cc
+++ b/src/internet/model/tcp-socket-base.cc
@@ -1689,7 +1689,8 @@ TcpSocketBase::EnterRecovery(uint32_t currentDelivered)
     }
 
     // (4.3) Retransmit the first data segment presumed dropped
-    DoRetransmit();
+    uint32_t sz = SendDataPacket(m_highRxAckMark, m_tcb->m_segmentSize, true);
+    NS_ASSERT_MSG(sz > 0, "SendDataPacket returned zero, indicating zero bytes were sent");
     // (4.4) Run SetPipe ()
     // (4.5) Proceed to step (C)
     // these steps are done after the ProcessAck function (SendPendingData)