Use unix sockets on Windows

server.go

@@ -8,14 +8,12 @@ import (
 	"crypto/tls"
 	"crypto/x509"
 	"encoding/base64"
-	"errors"
 	"fmt"
 	"io"
 	"net"
 	"os"
 	"os/signal"
 	"os/user"
-	"runtime"
 	"sort"
 	"strconv"
 	"strings"
@@ -502,18 +500,18 @@ func Serve(opts *ServeConfig) {
 	}
 	select {
 	case <-ctx.Done():
-		// Cancellation. We can stop the server by closing the listener.
-		// This isn't graceful at all but this is currently only used by
-		// tests and its our only way to stop.
-		_ = listener.Close()
-
 		// If this is a grpc server, then we also ask the server itself to
 		// end which will kill all connections. There isn't an easy way to do
 		// this for net/rpc currently but net/rpc is more and more unused.
 		if s, ok := server.(*GRPCServer); ok {
 			s.Stop()
 		}
 
+		// Cancellation. We can stop the server by closing the listener.
+		// This isn't graceful at all but this is currently only used by
+		// tests and its our only way to stop.
+		_ = listener.Close()
+
 		// Wait for the server itself to shut down
 		<-doneCh
 
@@ -525,56 +523,6 @@ func Serve(opts *ServeConfig) {
 	}
 }
 
-func serverListener(unixSocketCfg UnixSocketConfig) (net.Listener, error) {
-	if runtime.GOOS == "windows" {
-		return serverListener_tcp()
-	}
-
-	return serverListener_unix(unixSocketCfg)
-}
-
-func serverListener_tcp() (net.Listener, error) {
-	envMinPort := os.Getenv("PLUGIN_MIN_PORT")
-	envMaxPort := os.Getenv("PLUGIN_MAX_PORT")
-
-	var minPort, maxPort int64
-	var err error
-
-	switch {
-	case len(envMinPort) == 0:
-		minPort = 0
-	default:
-		minPort, err = strconv.ParseInt(envMinPort, 10, 32)
-		if err != nil {
-			return nil, fmt.Errorf("couldn't get value from PLUGIN_MIN_PORT: %v", err)
-		}
-	}
-
-	switch {
-	case len(envMaxPort) == 0:
-		maxPort = 0
-	default:
-		maxPort, err = strconv.ParseInt(envMaxPort, 10, 32)
-		if err != nil {
-			return nil, fmt.Errorf("couldn't get value from PLUGIN_MAX_PORT: %v", err)
-		}
-	}
-
-	if minPort > maxPort {
-		return nil, fmt.Errorf("PLUGIN_MIN_PORT value of %d is greater than PLUGIN_MAX_PORT value of %d", minPort, maxPort)
-	}
-
-	for port := minPort; port <= maxPort; port++ {
-		address := fmt.Sprintf("127.0.0.1:%d", port)
-		listener, err := net.Listen("tcp", address)
-		if err == nil {
-			return listener, nil
-		}
-	}
-
-	return nil, errors.New("couldn't bind plugin TCP listener")
-}
-
 func serverListener_unix(unixSocketCfg UnixSocketConfig) (net.Listener, error) {
 	tf, err := os.CreateTemp(unixSocketCfg.socketDir, "plugin")
 	if err != nil {

server_test.go

@@ -9,7 +9,7 @@ import (
 	"log"
 	"net"
 	"os"
-	"path"
+	"path/filepath"
 	"runtime"
 	"strings"
 	"testing"
@@ -68,6 +68,21 @@ func TestServer_testMode(t *testing.T) {
 	if err := client.Ping(); err != nil {
 		t.Fatalf("should not err: %s", err)
 	}
+	// Grab the impl
+	raw, err := client.Dispense("test")
+	if err != nil {
+		t.Fatalf("err should be nil, got %s", err)
+	}
+
+	tester, ok := raw.(testInterface)
+	if !ok {
+		t.Fatalf("bad: %#v", raw)
+	}
+
+	n := tester.Double(3)
+	if n != 6 {
+		t.Fatal("invalid response", n)
+	}
 
 	// Kill which should do nothing
 	c.Kill()
@@ -309,9 +324,10 @@ func TestServer_testStdLogger(t *testing.T) {
 
 func TestUnixSocketDir(t *testing.T) {
 	if runtime.GOOS == "windows" {
-		t.Skip("go-plugin doesn't support unix sockets on Windows")
+		if !isSupportUnix() {
+			t.Skip("go-plugin doesn't support unix sockets on Windows")
+		}
 	}
-
 	tmpDir := t.TempDir()
 	t.Setenv(EnvUnixSocketDir, tmpDir)
 
@@ -344,8 +360,8 @@ func TestUnixSocketDir(t *testing.T) {
 		t.Fatal("should've received reattach")
 	}
 
-	actualDir := path.Clean(path.Dir(cfg.Addr.String()))
-	expectedDir := path.Clean(tmpDir)
+	actualDir := filepath.Clean(filepath.Dir(cfg.Addr.String()))
+	expectedDir := filepath.Clean(tmpDir)
 	if actualDir != expectedDir {
 		t.Fatalf("Expected socket in dir: %s, but was in %s", expectedDir, actualDir)
 	}

server_unix.go

@@ -0,0 +1,13 @@
+// Copyright (c) HashiCorp, Inc.
+// SPDX-License-Identifier: MPL-2.0
+
+//go:build !windows
+// +build !windows
+
+package plugin
+
+var serverListener = serverListener_unix
+
+func isSupportUnix() bool {
+	return true
+}

server_windows.go

@@ -0,0 +1,72 @@
+// Copyright (c) HashiCorp, Inc.
+// SPDX-License-Identifier: MPL-2.0
+
+//go:build windows
+// +build windows
+
+package plugin
+
+import (
+	"errors"
+	"fmt"
+	"net"
+	"os"
+	"strconv"
+
+	"golang.org/x/sys/windows"
+)
+
+func serverListener(unixSocketCfg UnixSocketConfig) (net.Listener, error) {
+	if isSupportUnix() {
+		unixSocketCfg.Group = ""
+		return serverListener_unix(unixSocketCfg)
+	}
+	return serverListener_tcp()
+}
+
+func serverListener_tcp() (net.Listener, error) {
+	envMinPort := os.Getenv("PLUGIN_MIN_PORT")
+	envMaxPort := os.Getenv("PLUGIN_MAX_PORT")
+
+	var minPort, maxPort int64
+	var err error
+
+	switch {
+	case len(envMinPort) == 0:
+		minPort = 0
+	default:
+		minPort, err = strconv.ParseInt(envMinPort, 10, 32)
+		if err != nil {
+			return nil, fmt.Errorf("couldn't get value from PLUGIN_MIN_PORT: %v", err)
+		}
+	}
+
+	switch {
+	case len(envMaxPort) == 0:
+		maxPort = 0
+	default:
+		maxPort, err = strconv.ParseInt(envMaxPort, 10, 32)
+		if err != nil {
+			return nil, fmt.Errorf("couldn't get value from PLUGIN_MAX_PORT: %v", err)
+		}
+	}
+
+	if minPort > maxPort {
+		return nil, fmt.Errorf("PLUGIN_MIN_PORT value of %d is greater than PLUGIN_MAX_PORT value of %d", minPort, maxPort)
+	}
+
+	for port := minPort; port <= maxPort; port++ {
+		address := fmt.Sprintf("127.0.0.1:%d", port)
+		listener, err := net.Listen("tcp", address)
+		if err == nil {
+			return listener, nil
+		}
+	}
+
+	return nil, errors.New("couldn't bind plugin TCP listener")
+}
+
+func isSupportUnix() bool {
+	major, _, build := windows.RtlGetNtVersionNumbers()
+	return major >= 10 && build >= 17063
+}