2 files changed, 124 insertions, 0 deletions
diff --git a/test/packetimpact/tests/BUILD b/test/packetimpact/tests/BUILD
index 3a0e9cb07..e2a320159 100644
--- a/test/packetimpact/tests/BUILD
+++ b/test/packetimpact/tests/BUILD
@@ -16,6 +16,19 @@ packetimpact_go_test(
 )
 
 packetimpact_go_test(
+    name = "ipv4_id_uniqueness",
+    srcs = ["ipv4_id_uniqueness_test.go"],
+    # TODO(b/157506701) Fix netstack then remove the line below.
+    expect_netstack_failure = True,
+    deps = [
+        "//pkg/abi/linux",
+        "//pkg/tcpip/header",
+        "//test/packetimpact/testbench",
+        "@org_golang_x_sys//unix:go_default_library",
+    ],
+)
+
+packetimpact_go_test(
     name = "udp_recv_multicast",
     srcs = ["udp_recv_multicast_test.go"],
     # TODO(b/152813495): Fix netstack then remove the line below.
diff --git a/test/packetimpact/tests/ipv4_id_uniqueness_test.go b/test/packetimpact/tests/ipv4_id_uniqueness_test.go
new file mode 100644
index 000000000..49e481d0b
--- /dev/null
+++ b/test/packetimpact/tests/ipv4_id_uniqueness_test.go
@@ -0,0 +1,111 @@
+// Copyright 2020 The gVisor Authors.
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+package ipv4_id_uniqueness_test
+
+import (
+	"context"
+	"flag"
+	"fmt"
+	"testing"
+	"time"
+
+	"golang.org/x/sys/unix"
+	"gvisor.dev/gvisor/pkg/abi/linux"
+	"gvisor.dev/gvisor/pkg/tcpip/header"
+	tb "gvisor.dev/gvisor/test/packetimpact/testbench"
+)
+
+func init() {
+	tb.RegisterFlags(flag.CommandLine)
+}
+
+func recvTCPSegment(conn *tb.TCPIPv4, expect *tb.TCP, expectPayload *tb.Payload) (uint16, error) {
+	layers, err := conn.ExpectData(expect, expectPayload, time.Second)
+	if err != nil {
+		return 0, fmt.Errorf("failed to receive TCP segment: %s", err)
+	}
+	if len(layers) < 2 {
+		return 0, fmt.Errorf("got packet with layers: %v, expected to have at least 2 layers (link and network)", layers)
+	}
+	ipv4, ok := layers[1].(*tb.IPv4)
+	if !ok {
+		return 0, fmt.Errorf("got network layer: %T, expected: *IPv4", layers[1])
+	}
+	if *ipv4.Flags&header.IPv4FlagDontFragment != 0 {
+		return 0, fmt.Errorf("got IPv4 DF=1, expected DF=0")
+	}
+	return *ipv4.ID, nil
+}
+
+// RFC 6864 section 4.2 states: "The IPv4 ID of non-atomic datagrams MUST NOT
+// be reused when sending a copy of an earlier non-atomic datagram."
+//
+// This test creates a TCP connection, uses the IP_MTU_DISCOVER socket option
+// to force the DF bit to be 0, and checks that a retransmitted segment has a
+// different IPv4 Identification value than the original segment.
+func TestIPv4RetransmitIdentificationUniqueness(t *testing.T) {
+	dut := tb.NewDUT(t)
+	defer dut.TearDown()
+
+	listenFD, remotePort := dut.CreateListener(unix.SOCK_STREAM, unix.IPPROTO_TCP, 1)
+	defer dut.Close(listenFD)
+
+	conn := tb.NewTCPIPv4(t, tb.TCP{DstPort: &remotePort}, tb.TCP{SrcPort: &remotePort})
+	defer conn.Close()
+
+	conn.Handshake()
+	remoteFD, _ := dut.Accept(listenFD)
+	defer dut.Close(remoteFD)
+
+	dut.SetSockOptInt(remoteFD, unix.IPPROTO_TCP, unix.TCP_NODELAY, 1)
+
+	// TODO(b/129291778) The following socket option clears the DF bit on
+	// IP packets sent over the socket, and is currently not supported by
+	// gVisor. gVisor by default sends packets with DF=0 anyway, so the
+	// socket option being not supported does not affect the operation of
+	// this test. Once the socket option is supported, the following call
+	// can be changed to simply assert success.
+	ret, errno := dut.SetSockOptIntWithErrno(context.Background(), remoteFD, unix.IPPROTO_IP, linux.IP_MTU_DISCOVER, linux.IP_PMTUDISC_DONT)
+	if ret == -1 && errno != unix.ENOTSUP {
+		t.Fatalf("failed to set IP_MTU_DISCOVER socket option to IP_PMTUDISC_DONT: %s", errno)
+	}
+
+	sampleData := []byte("Sample Data")
+	samplePayload := &tb.Payload{Bytes: sampleData}
+
+	dut.Send(remoteFD, sampleData, 0)
+	if _, err := conn.ExpectData(&tb.TCP{}, samplePayload, time.Second); err != nil {
+		t.Fatalf("failed to receive TCP segment sent for RTT calculation: %s", err)
+	}
+	// Let the DUT estimate RTO with RTT from the DATA-ACK.
+	// TODO(gvisor.dev/issue/2685) Estimate RTO during handshake, after which
+	// we can skip sending this ACK.
+	conn.Send(tb.TCP{Flags: tb.Uint8(header.TCPFlagAck)})
+
+	expectTCP := &tb.TCP{SeqNum: tb.Uint32(uint32(*conn.RemoteSeqNum()))}
+	dut.Send(remoteFD, sampleData, 0)
+	originalID, err := recvTCPSegment(&conn, expectTCP, samplePayload)
+	if err != nil {
+		t.Fatalf("failed to receive TCP segment: %s", err)
+	}
+
+	retransmitID, err := recvTCPSegment(&conn, expectTCP, samplePayload)
+	if err != nil {
+		t.Fatalf("failed to receive retransmitted TCP segment: %s", err)
+	}
+	if originalID == retransmitID {
+		t.Fatalf("unexpectedly got retransmitted TCP segment with same IPv4 ID field=%d", originalID)
+	}
+}