Use simulated dual-stack binds when using WSL

Resolves a WSL problem where traffic from only one stack is relayed

Signed-off-by: Jason T. Greene <jason.greene@redhat.com>

cmd/rootlessport/main.go

@@ -1,3 +1,6 @@
+//go:build linux
+// +build linux
+
 package main
 
 import (
@@ -307,11 +310,11 @@ func exposePorts(pm rkport.Manager, portMappings []types.PortMapping, childIP st
 					ChildPort:  int(port.ContainerPort + i),
 					ChildIP:    childIP,
 				}
-				if err := rkportutil.ValidatePortSpec(spec, nil); err != nil {
-					return err
-				}
-				if _, err := pm.AddPort(ctx, spec); err != nil {
-					return err
+
+				for _, spec = range splitDualStackSpecIfWsl(spec) {
+					if err := validateAndAddPort(ctx, pm, spec); err != nil {
+						return err
+					}
 				}
 			}
 		}
@@ -319,6 +322,17 @@ func exposePorts(pm rkport.Manager, portMappings []types.PortMapping, childIP st
 	return nil
 }
 
+func validateAndAddPort(ctx context.Context, pm rkport.Manager, spec rkport.Spec) error {
+	if err := rkportutil.ValidatePortSpec(spec, nil); err != nil {
+		return err
+	}
+	if _, err := pm.AddPort(ctx, spec); err != nil {
+		return err
+	}
+
+	return nil
+}
+
 func child() error {
 	// load the config from the parent
 	var opaque map[string]string

cmd/rootlessport/wsl.go

@@ -0,0 +1,37 @@
+package main
+
+import (
+	"net"
+	"strings"
+
+	"github.com/containers/common/pkg/machine"
+	rkport "github.com/rootless-containers/rootlesskit/pkg/port"
+)
+
+// WSL machines do not relay ipv4 traffic to dual-stack ports, simulate instead
+func splitDualStackSpecIfWsl(spec rkport.Spec) []rkport.Spec {
+	specs := []rkport.Spec{spec}
+	protocol := spec.Proto
+	if machine.MachineHostType() != machine.Wsl || strings.HasSuffix(protocol, "4") || strings.HasSuffix(protocol, "6") {
+		return specs
+	}
+
+	ip := net.ParseIP(spec.ParentIP)
+	splitLoopback := ip.IsLoopback() && ip.To4() == nil
+	// Map ::1 and 0.0.0.0/:: to ipv4 + ipv6 to simulate dual-stack
+	if ip.IsUnspecified() || splitLoopback {
+		specs = append(specs, spec)
+		specs[0].Proto = protocol + "4"
+		specs[1].Proto = protocol + "6"
+		if splitLoopback {
+			// Hacky, but we will only have one ipv4 loopback with WSL config
+			specs[0].ParentIP = "127.0.0.1"
+		}
+		if ip.IsUnspecified() {
+			specs[0].ParentIP = "0.0.0.0"
+			specs[1].ParentIP = "::"
+		}
+	}
+
+	return specs
+}

cmd/rootlessport/wsl_test.go

@@ -0,0 +1,89 @@
+package main
+
+import (
+	"testing"
+
+	"github.com/containers/common/pkg/machine"
+	"github.com/rootless-containers/rootlesskit/pkg/port"
+	"github.com/stretchr/testify/assert"
+)
+
+type SpecData struct {
+	mach        string
+	sourceProto string
+	sourceIP    string
+	expectCount int
+	expectProto string
+	expectIP    string
+	secondProto string
+	secondIP    string
+}
+
+func TestDualStackSplit(t *testing.T) {
+	//nolint
+	const (
+		IP4_ALL = "0.0.0.0"
+		IP4__LO = "127.0.0.1"
+		IP6_ALL = "::"
+		IP6__LO = "::1"
+		TCP_    = "tcp"
+		TCP4    = "tcp4"
+		TCP6    = "tcp6"
+		WSL     = "wsl"
+		___     = ""
+		IP6_REG = "2001:0db8:85a3:0000:0000:8a2e:0370:7334"
+		IP4_REG = "10.0.0.1"
+	)
+
+	tests := []SpecData{
+		// Split cases
+		{WSL, TCP_, IP4_ALL, 2, TCP4, IP4_ALL, TCP6, IP6_ALL},
+		{WSL, TCP_, IP6_ALL, 2, TCP4, IP4_ALL, TCP6, IP6_ALL},
+		{WSL, TCP_, IP6__LO, 2, TCP4, IP4__LO, TCP6, IP6__LO},
+
+		// Non-Split
+		{WSL, TCP_, IP4__LO, 1, TCP_, IP4__LO, "", ""},
+		{WSL, TCP4, IP4_ALL, 1, TCP4, IP4_ALL, "", ""},
+		{WSL, TCP6, IP6__LO, 1, TCP6, IP6__LO, "", ""},
+		{WSL, TCP_, IP4_REG, 1, TCP_, IP4_REG, "", ""},
+		{WSL, TCP_, IP6_REG, 1, TCP_, IP6_REG, "", ""},
+		{___, TCP_, IP4_ALL, 1, TCP_, IP4_ALL, "", ""},
+		{___, TCP_, IP6_ALL, 1, TCP_, IP6_ALL, "", ""},
+		{___, TCP_, IP4__LO, 1, TCP_, IP4__LO, "", ""},
+		{___, TCP_, IP6__LO, 1, TCP_, IP6__LO, "", ""},
+	}
+
+	for _, data := range tests {
+		verifySplit(t, data)
+	}
+}
+
+func verifySplit(t *testing.T, data SpecData) {
+	machine := machine.GetMachineMarker()
+	oldEnable, oldType := machine.Enabled, machine.Type
+	machine.Enabled, machine.Type = len(data.mach) > 0, data.mach
+
+	source := port.Spec{
+		Proto:      data.sourceProto,
+		ParentIP:   data.sourceIP,
+		ParentPort: 100,
+		ChildIP:    "1.1.1.1",
+		ChildPort:  200,
+	}
+	expect, second := source, source
+	specs := splitDualStackSpecIfWsl(source)
+
+	assert.Equal(t, data.expectCount, len(specs))
+
+	expect.Proto = data.expectProto
+	expect.ParentIP = data.expectIP
+	assert.Equal(t, expect, specs[0])
+
+	if data.expectCount > 1 {
+		second.Proto = data.secondProto
+		second.ParentIP = data.secondIP
+		assert.Equal(t, second, specs[1])
+	}
+
+	machine.Enabled, machine.Type = oldEnable, oldType
+}