Add an integration test for istio like redirect.

Updates #6441,#6317

PiperOrigin-RevId: 404872327

pkg/tcpip/adapters/gonet/gonet.go

@@ -19,6 +19,7 @@ import (
 	"bytes"
 	"context"
 	"errors"
+	"fmt"
 	"io"
 	"net"
 	"time"
@@ -471,9 +472,9 @@ func DialTCP(s *stack.Stack, addr tcpip.FullAddress, network tcpip.NetworkProtoc
 	return DialContextTCP(context.Background(), s, addr, network)
 }
 
-// DialContextTCP creates a new TCPConn connected to the specified address
-// with the option of adding cancellation and timeouts.
-func DialContextTCP(ctx context.Context, s *stack.Stack, addr tcpip.FullAddress, network tcpip.NetworkProtocolNumber) (*TCPConn, error) {
+// DialTCPWithBind creates a new TCPConn connected to the specified
+// remoteAddress with its local address bound to localAddr.
+func DialTCPWithBind(ctx context.Context, s *stack.Stack, localAddr, remoteAddr tcpip.FullAddress, network tcpip.NetworkProtocolNumber) (*TCPConn, error) {
 	// Create TCP endpoint, then connect.
 	var wq waiter.Queue
 	ep, err := s.NewEndpoint(tcp.ProtocolNumber, network, &wq)
@@ -494,7 +495,14 @@ func DialContextTCP(ctx context.Context, s *stack.Stack, addr tcpip.FullAddress,
 	default:
 	}
 
-	err = ep.Connect(addr)
+	// Bind before connect if requested.
+	if localAddr != (tcpip.FullAddress{}) {
+		if err = ep.Bind(localAddr); err != nil {
+			return nil, fmt.Errorf("ep.Bind(%+v) = %s", localAddr, err)
+		}
+	}
+
+	err = ep.Connect(remoteAddr)
 	if _, ok := err.(*tcpip.ErrConnectStarted); ok {
 		select {
 		case <-ctx.Done():
@@ -510,14 +518,20 @@ func DialContextTCP(ctx context.Context, s *stack.Stack, addr tcpip.FullAddress,
 		return nil, &net.OpError{
 			Op:   "connect",
 			Net:  "tcp",
-			Addr: fullToTCPAddr(addr),
+			Addr: fullToTCPAddr(remoteAddr),
 			Err:  errors.New(err.String()),
 		}
 	}
 
 	return NewTCPConn(&wq, ep), nil
 }
 
+// DialContextTCP creates a new TCPConn connected to the specified address
+// with the option of adding cancellation and timeouts.
+func DialContextTCP(ctx context.Context, s *stack.Stack, addr tcpip.FullAddress, network tcpip.NetworkProtocolNumber) (*TCPConn, error) {
+	return DialTCPWithBind(ctx, s, tcpip.FullAddress{} /* localAddr */, addr /* remoteAddr */, network)
+}
+
 // A UDPConn is a wrapper around a UDP tcpip.Endpoint that implements
 // net.Conn and net.PacketConn.
 type UDPConn struct {

pkg/tcpip/header/ipv4.go

@@ -208,6 +208,15 @@ var IPv4EmptySubnet = func() tcpip.Subnet {
 	return subnet
 }()
 
+// IPv4LoopbackSubnet is the loopback subnet for IPv4.
+var IPv4LoopbackSubnet = func() tcpip.Subnet {
+	subnet, err := tcpip.NewSubnet(tcpip.Address("\x7f\x00\x00\x00"), tcpip.AddressMask("\xff\x00\x00\x00"))
+	if err != nil {
+		panic(err)
+	}
+	return subnet
+}()
+
 // IPVersion returns the version of IP used in the given packet. It returns -1
 // if the packet is not large enough to contain the version field.
 func IPVersion(b []byte) int {

pkg/tcpip/tests/integration/BUILD

@@ -143,3 +143,25 @@ go_test(
         "@com_github_google_go_cmp//cmp:go_default_library",
     ],
 )
+
+go_test(
+    name = "istio_test",
+    size = "small",
+    srcs = ["istio_test.go"],
+    deps = [
+        "//pkg/context",
+        "//pkg/rand",
+        "//pkg/sync",
+        "//pkg/tcpip",
+        "//pkg/tcpip/adapters/gonet",
+        "//pkg/tcpip/header",
+        "//pkg/tcpip/link/loopback",
+        "//pkg/tcpip/link/pipe",
+        "//pkg/tcpip/link/sniffer",
+        "//pkg/tcpip/network/ipv4",
+        "//pkg/tcpip/stack",
+        "//pkg/tcpip/testutil",
+        "//pkg/tcpip/transport/tcp",
+        "@com_github_google_go_cmp//cmp:go_default_library",
+    ],
+)