Support SO_LINGER socket option.

When SO_LINGER option is enabled, the close will not return until all the
queued messages are sent and acknowledged for the socket or linger timeout is
reached. If the option is not set, close will return immediately. This option
is mainly supported for connection oriented protocols such as TCP.

PiperOrigin-RevId: 328350576

2 files changed, 263 insertions, 0 deletions

diff --git a/test/packetimpact/tests/BUILD b/test/packetimpact/tests/BUILD
index 74658fea0..7a7152fa5 100644
--- a/test/packetimpact/tests/BUILD
+++ b/test/packetimpact/tests/BUILD
@@ -308,3 +308,13 @@ packetimpact_go_test(
         "@org_golang_x_sys//unix:go_default_library",
     ],
 )
+
+packetimpact_go_test(
+    name = "tcp_linger",
+    srcs = ["tcp_linger_test.go"],
+    deps = [
+        "//pkg/tcpip/header",
+        "//test/packetimpact/testbench",
+        "@org_golang_x_sys//unix:go_default_library",
+    ],
+)
diff --git a/test/packetimpact/tests/tcp_linger_test.go b/test/packetimpact/tests/tcp_linger_test.go
new file mode 100644
index 000000000..913e49e06
--- /dev/null
+++ b/test/packetimpact/tests/tcp_linger_test.go
@@ -0,0 +1,253 @@
+// 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 tcp_linger_test
+
+import (
+	"context"
+	"flag"
+	"syscall"
+	"testing"
+	"time"
+
+	"golang.org/x/sys/unix"
+	"gvisor.dev/gvisor/pkg/tcpip/header"
+	"gvisor.dev/gvisor/test/packetimpact/testbench"
+)
+
+func init() {
+	testbench.RegisterFlags(flag.CommandLine)
+}
+
+func createSocket(t *testing.T, dut testbench.DUT) (int32, int32, testbench.TCPIPv4) {
+	listenFD, remotePort := dut.CreateListener(t, unix.SOCK_STREAM, unix.IPPROTO_TCP, 1)
+	conn := testbench.NewTCPIPv4(t, testbench.TCP{DstPort: &remotePort}, testbench.TCP{SrcPort: &remotePort})
+	conn.Connect(t)
+	acceptFD, _ := dut.Accept(t, listenFD)
+	return acceptFD, listenFD, conn
+}
+
+func closeAll(t *testing.T, dut testbench.DUT, listenFD int32, conn testbench.TCPIPv4) {
+	conn.Close(t)
+	dut.Close(t, listenFD)
+	dut.TearDown()
+}
+
+// lingerDuration is the timeout value used with SO_LINGER socket option.
+const lingerDuration = 3 * time.Second
+
+// TestTCPLingerZeroTimeout tests when SO_LINGER is set with zero timeout. DUT
+// should send RST-ACK when socket is closed.
+func TestTCPLingerZeroTimeout(t *testing.T) {
+	// Create a socket, listen, TCP connect, and accept.
+	dut := testbench.NewDUT(t)
+	acceptFD, listenFD, conn := createSocket(t, dut)
+	defer closeAll(t, dut, listenFD, conn)
+
+	dut.SetSockLingerOption(t, acceptFD, 0, true)
+	dut.Close(t, acceptFD)
+
+	// If the linger timeout is set to zero, the DUT should send a RST.
+	if _, err := conn.Expect(t, testbench.TCP{Flags: testbench.Uint8(header.TCPFlagRst | header.TCPFlagAck)}, time.Second); err != nil {
+		t.Errorf("expected RST-ACK packet within a second but got none: %s", err)
+	}
+	conn.Send(t, testbench.TCP{Flags: testbench.Uint8(header.TCPFlagAck)})
+}
+
+// TestTCPLingerOff tests when SO_LINGER is not set. DUT should send FIN-ACK
+// when socket is closed.
+func TestTCPLingerOff(t *testing.T) {
+	// Create a socket, listen, TCP connect, and accept.
+	dut := testbench.NewDUT(t)
+	acceptFD, listenFD, conn := createSocket(t, dut)
+	defer closeAll(t, dut, listenFD, conn)
+
+	dut.Close(t, acceptFD)
+
+	// If SO_LINGER is not set, DUT should send a FIN-ACK.
+	if _, err := conn.Expect(t, testbench.TCP{Flags: testbench.Uint8(header.TCPFlagFin | header.TCPFlagAck)}, time.Second); err != nil {
+		t.Errorf("expected FIN-ACK packet within a second but got none: %s", err)
+	}
+	conn.Send(t, testbench.TCP{Flags: testbench.Uint8(header.TCPFlagAck)})
+}
+
+// TestTCPLingerNonZeroTimeout tests when SO_LINGER is set with non-zero timeout.
+// DUT should close the socket after timeout.
+func TestTCPLingerNonZeroTimeout(t *testing.T) {
+	for _, tt := range []struct {
+		description string
+		lingerOn    bool
+	}{
+		{"WithNonZeroLinger", true},
+		{"WithoutLinger", false},
+	} {
+		t.Run(tt.description, func(t *testing.T) {
+			// Create a socket, listen, TCP connect, and accept.
+			dut := testbench.NewDUT(t)
+			acceptFD, listenFD, conn := createSocket(t, dut)
+			defer closeAll(t, dut, listenFD, conn)
+
+			dut.SetSockLingerOption(t, acceptFD, lingerDuration, tt.lingerOn)
+
+			// Increase timeout as Close will take longer time to
+			// return when SO_LINGER is set with non-zero timeout.
+			timeout := lingerDuration + 1*time.Second
+			ctx, cancel := context.WithTimeout(context.Background(), timeout)
+			defer cancel()
+			start := time.Now()
+			dut.CloseWithErrno(ctx, t, acceptFD)
+			end := time.Now()
+			diff := end.Sub(start)
+
+			if tt.lingerOn && diff < lingerDuration {
+				t.Errorf("expected close to return after %v seconds, but returned sooner", lingerDuration)
+			} else if !tt.lingerOn && diff > 1*time.Second {
+				t.Errorf("expected close to return within a second, but returned later")
+			}
+
+			if _, err := conn.Expect(t, testbench.TCP{Flags: testbench.Uint8(header.TCPFlagFin | header.TCPFlagAck)}, time.Second); err != nil {
+				t.Errorf("expected FIN-ACK packet within a second but got none: %s", err)
+			}
+			conn.Send(t, testbench.TCP{Flags: testbench.Uint8(header.TCPFlagAck)})
+		})
+	}
+}
+
+// TestTCPLingerSendNonZeroTimeout tests when SO_LINGER is set with non-zero
+// timeout and send a packet. DUT should close the socket after timeout.
+func TestTCPLingerSendNonZeroTimeout(t *testing.T) {
+	for _, tt := range []struct {
+		description string
+		lingerOn    bool
+	}{
+		{"WithSendNonZeroLinger", true},
+		{"WithoutLinger", false},
+	} {
+		t.Run(tt.description, func(t *testing.T) {
+			// Create a socket, listen, TCP connect, and accept.
+			dut := testbench.NewDUT(t)
+			acceptFD, listenFD, conn := createSocket(t, dut)
+			defer closeAll(t, dut, listenFD, conn)
+
+			dut.SetSockLingerOption(t, acceptFD, lingerDuration, tt.lingerOn)
+
+			// Send data.
+			sampleData := []byte("Sample Data")
+			dut.Send(t, acceptFD, sampleData, 0)
+
+			// Increase timeout as Close will take longer time to
+			// return when SO_LINGER is set with non-zero timeout.
+			timeout := lingerDuration + 1*time.Second
+			ctx, cancel := context.WithTimeout(context.Background(), timeout)
+			defer cancel()
+			start := time.Now()
+			dut.CloseWithErrno(ctx, t, acceptFD)
+			end := time.Now()
+			diff := end.Sub(start)
+
+			if tt.lingerOn && diff < lingerDuration {
+				t.Errorf("expected close to return after %v seconds, but returned sooner", lingerDuration)
+			} else if !tt.lingerOn && diff > 1*time.Second {
+				t.Errorf("expected close to return within a second, but returned later")
+			}
+
+			samplePayload := &testbench.Payload{Bytes: sampleData}
+			if _, err := conn.ExpectData(t, &testbench.TCP{}, samplePayload, time.Second); err != nil {
+				t.Fatalf("expected a packet with payload %v: %s", samplePayload, err)
+			}
+
+			if _, err := conn.Expect(t, testbench.TCP{Flags: testbench.Uint8(header.TCPFlagFin | header.TCPFlagAck)}, time.Second); err != nil {
+				t.Errorf("expected FIN-ACK packet within a second but got none: %s", err)
+			}
+			conn.Send(t, testbench.TCP{Flags: testbench.Uint8(header.TCPFlagAck)})
+		})
+	}
+}
+
+// TestTCPLingerShutdownZeroTimeout tests SO_LINGER with shutdown() and zero
+// timeout. DUT should send RST-ACK when socket is closed.
+func TestTCPLingerShutdownZeroTimeout(t *testing.T) {
+	// Create a socket, listen, TCP connect, and accept.
+	dut := testbench.NewDUT(t)
+	acceptFD, listenFD, conn := createSocket(t, dut)
+	defer closeAll(t, dut, listenFD, conn)
+
+	dut.SetSockLingerOption(t, acceptFD, 0, true)
+	dut.Shutdown(t, acceptFD, syscall.SHUT_RDWR)
+	dut.Close(t, acceptFD)
+
+	// Shutdown will send FIN-ACK with read/write option.
+	if _, err := conn.Expect(t, testbench.TCP{Flags: testbench.Uint8(header.TCPFlagFin | header.TCPFlagAck)}, time.Second); err != nil {
+		t.Errorf("expected FIN-ACK packet within a second but got none: %s", err)
+	}
+
+	// If the linger timeout is set to zero, the DUT should send a RST.
+	if _, err := conn.Expect(t, testbench.TCP{Flags: testbench.Uint8(header.TCPFlagRst | header.TCPFlagAck)}, time.Second); err != nil {
+		t.Errorf("expected RST-ACK packet within a second but got none: %s", err)
+	}
+	conn.Send(t, testbench.TCP{Flags: testbench.Uint8(header.TCPFlagAck)})
+}
+
+// TestTCPLingerShutdownSendNonZeroTimeout tests SO_LINGER with shutdown() and
+// non-zero timeout. DUT should close the socket after timeout.
+func TestTCPLingerShutdownSendNonZeroTimeout(t *testing.T) {
+	for _, tt := range []struct {
+		description string
+		lingerOn    bool
+	}{
+		{"shutdownRDWR", true},
+		{"shutdownRDWR", false},
+	} {
+		t.Run(tt.description, func(t *testing.T) {
+			// Create a socket, listen, TCP connect, and accept.
+			dut := testbench.NewDUT(t)
+			acceptFD, listenFD, conn := createSocket(t, dut)
+			defer closeAll(t, dut, listenFD, conn)
+
+			dut.SetSockLingerOption(t, acceptFD, lingerDuration, tt.lingerOn)
+
+			// Send data.
+			sampleData := []byte("Sample Data")
+			dut.Send(t, acceptFD, sampleData, 0)
+
+			dut.Shutdown(t, acceptFD, syscall.SHUT_RDWR)
+
+			// Increase timeout as Close will take longer time to
+			// return when SO_LINGER is set with non-zero timeout.
+			timeout := lingerDuration + 1*time.Second
+			ctx, cancel := context.WithTimeout(context.Background(), timeout)
+			defer cancel()
+			start := time.Now()
+			dut.CloseWithErrno(ctx, t, acceptFD)
+			end := time.Now()
+			diff := end.Sub(start)
+
+			if tt.lingerOn && diff < lingerDuration {
+				t.Errorf("expected close to return after %v seconds, but returned sooner", lingerDuration)
+			} else if !tt.lingerOn && diff > 1*time.Second {
+				t.Errorf("expected close to return within a second, but returned later")
+			}
+
+			samplePayload := &testbench.Payload{Bytes: sampleData}
+			if _, err := conn.ExpectData(t, &testbench.TCP{}, samplePayload, time.Second); err != nil {
+				t.Fatalf("expected a packet with payload %v: %s", samplePayload, err)
+			}
+
+			if _, err := conn.Expect(t, testbench.TCP{Flags: testbench.Uint8(header.TCPFlagFin | header.TCPFlagAck)}, time.Second); err != nil {
+				t.Errorf("expected FIN-ACK packet within a second but got none: %s", err)
+			}
+			conn.Send(t, testbench.TCP{Flags: testbench.Uint8(header.TCPFlagAck)})
+		})
+	}
+}