2 files changed, 31 insertions, 4 deletions
diff --git a/test/packetimpact/testbench/connections.go b/test/packetimpact/testbench/connections.go
index bafc45d3b..8ad9040ff 100644
--- a/test/packetimpact/testbench/connections.go
+++ b/test/packetimpact/testbench/connections.go
@@ -823,6 +823,27 @@ func (conn *TCPIPv4) LocalAddr(t *testing.T) *unix.SockaddrInet4 {
 	return sa
 }
 
+// GenerateOTWSeqSegment generates a segment with
+// seqnum = RCV.NXT + RCV.WND + seqNumOffset, the generated segment is only
+// acceptable when seqNumOffset is 0, otherwise an ACK is expected from the
+// receiver.
+func GenerateOTWSeqSegment(t *testing.T, conn *TCPIPv4, seqNumOffset seqnum.Size, windowSize seqnum.Size) TCP {
+	t.Helper()
+	lastAcceptable := conn.LocalSeqNum(t).Add(windowSize)
+	otwSeq := uint32(lastAcceptable.Add(seqNumOffset))
+	return TCP{SeqNum: Uint32(otwSeq), Flags: TCPFlags(header.TCPFlagAck)}
+}
+
+// GenerateUnaccACKSegment generates a segment with
+// acknum = SND.NXT + seqNumOffset, the generated segment is only acceptable
+// when seqNumOffset is 0, otherwise an ACK is expected from the receiver.
+func GenerateUnaccACKSegment(t *testing.T, conn *TCPIPv4, seqNumOffset seqnum.Size, windowSize seqnum.Size) TCP {
+	t.Helper()
+	lastAcceptable := conn.RemoteSeqNum(t)
+	unaccAck := uint32(lastAcceptable.Add(seqNumOffset))
+	return TCP{AckNum: Uint32(unaccAck), Flags: TCPFlags(header.TCPFlagAck)}
+}
+
 // IPv4Conn maintains the state for all the layers in a IPv4 connection.
 type IPv4Conn struct {
 	Connection
diff --git a/test/packetimpact/testbench/dut.go b/test/packetimpact/testbench/dut.go
index f4c83ab96..eabdc8cb3 100644
--- a/test/packetimpact/testbench/dut.go
+++ b/test/packetimpact/testbench/dut.go
@@ -773,16 +773,19 @@ func (dut *DUT) SetSockLingerOption(t *testing.T, sockfd int32, timeout time.Dur
 // Shutdown calls shutdown on the DUT and causes a fatal test failure if it
 // doesn't succeed. If more control over the timeout or error handling is
 // needed, use ShutdownWithErrno.
-func (dut *DUT) Shutdown(t *testing.T, fd, how int32) error {
+func (dut *DUT) Shutdown(t *testing.T, fd, how int32) {
 	t.Helper()
 
 	ctx, cancel := context.WithTimeout(context.Background(), RPCTimeout)
 	defer cancel()
-	return dut.ShutdownWithErrno(ctx, t, fd, how)
+	ret, err := dut.ShutdownWithErrno(ctx, t, fd, how)
+	if ret != 0 {
+		t.Fatalf("failed to shutdown(%d, %d): %s", fd, how, err)
+	}
 }
 
 // ShutdownWithErrno calls shutdown on the DUT.
-func (dut *DUT) ShutdownWithErrno(ctx context.Context, t *testing.T, fd, how int32) error {
+func (dut *DUT) ShutdownWithErrno(ctx context.Context, t *testing.T, fd, how int32) (int32, error) {
 	t.Helper()
 
 	req := &pb.ShutdownRequest{
@@ -793,5 +796,8 @@ func (dut *DUT) ShutdownWithErrno(ctx context.Context, t *testing.T, fd, how int
 	if err != nil {
 		t.Fatalf("failed to call Shutdown: %s", err)
 	}
-	return unix.Errno(resp.GetErrno_())
+	if resp.GetErrno_() == 0 {
+		return resp.GetRet(), nil
+	}
+	return resp.GetRet(), unix.Errno(resp.GetErrno_())
 }