File loader: Check file extensions without resolving symlinks (#7255)

https://github.com/XTLS/Xray-core/pull/7255#issuecomment-6481194940
https://github.com/XTLS/Xray-core/pull/7250#issuecomment-6398816842

Fixes https://github.com/XTLS/Xray-core/issues/7239#issuecomment-6356122816

---------

Co-authored-by: Eljees <3.14hell@gmail.com>

common/platform/filesystem/file.go

@@ -5,6 +5,7 @@ import (
 	"io"
 	"os"
 	"path/filepath"
+	"strings"
 
 	"github.com/xtls/xray-core/common/buf"
 	"github.com/xtls/xray-core/common/platform"
@@ -26,14 +27,6 @@ func ReadFile(path string) ([]byte, error) {
 	return buf.ReadAllToBytes(reader)
 }
 
-func ReadAsset(file string) ([]byte, error) {
-	path, _, err := getAssetFileLocation(file)
-	if err != nil {
-		return nil, err
-	}
-	return ReadFile(path)
-}
-
 func OpenAsset(file string) (io.ReadCloser, int64, error) {
 	path, info, err := getAssetFileLocation(file)
 	if err != nil {
@@ -43,11 +36,6 @@ func OpenAsset(file string) (io.ReadCloser, int64, error) {
 	return r, info.Size(), err
 }
 
-func StatAsset(file string) (os.FileInfo, error) {
-	_, info, err := getAssetFileLocation(file)
-	return info, err
-}
-
 func ResolveAsset(file string) (string, error) {
 	path, _, err := getAssetFileLocation(file)
 	return path, err
@@ -79,17 +67,29 @@ func ReadCert(file string) ([]byte, error) {
 	return ReadFile(platform.GetCertLocation(file))
 }
 
-func CopyFile(dst string, src string) error {
-	bytes, err := ReadFile(src)
-	if err != nil {
-		return err
+// ResolveLuaFile finds a local .lua script and returns its absolute path.
+// Relative paths: XRAY_LOCATION_CONFDIR > XRAY_LOCATION_CONFIG > working dir > executable dir.
+func ResolveLuaFile(path string) (string, error) {
+	if !strings.EqualFold(filepath.Ext(path), ".lua") {
+		return "", errors.New("Lua file extension must be .lua")
 	}
-	f, err := os.OpenFile(dst, os.O_CREATE|os.O_WRONLY, 0o644)
-	if err != nil {
-		return err
+	if filepath.IsAbs(path) {
+		return path, nil
 	}
-	defer f.Close()
-
-	_, err = f.Write(bytes)
-	return err
+	for _, dir := range []string{
+		platform.GetConfDirPath(),
+		platform.NewEnvFlag(platform.ConfigLocation).GetValue(func() string { return "" }),
+		".",
+		platform.GetExecutableDir(),
+	} {
+		if dir != "" {
+			resolved := filepath.Join(dir, path)
+			if _, err := os.Stat(resolved); err == nil {
+				return filepath.Abs(resolved)
+			} else if !os.IsNotExist(err) {
+				return "", err
+			}
+		}
+	}
+	return "", os.ErrNotExist
 }

common/platform/filesystem/file_test.go

@@ -1,13 +1,17 @@
 package filesystem_test
 
 import (
+	"errors"
+	"os"
 	"path/filepath"
 	"testing"
 
+	"github.com/xtls/xray-core/common"
+	"github.com/xtls/xray-core/common/platform"
 	. "github.com/xtls/xray-core/common/platform/filesystem"
 )
 
-func TestStatAssetRejectsInvalidPath(t *testing.T) {
+func TestResolveAssetRejectsInvalidPath(t *testing.T) {
 	for _, file := range []string{
 		"",
 		".",
@@ -25,8 +29,49 @@ func TestStatAssetRejectsInvalidPath(t *testing.T) {
 		`nested\..\geoip.dat`,
 		filepath.Join(t.TempDir(), "geoip.dat"),
 	} {
-		if _, err := StatAsset(file); err == nil {
+		if _, err := ResolveAsset(file); err == nil {
 			t.Fatalf("expected error for %q", file)
 		}
 	}
 }
+
+func TestResolveLuaFile(t *testing.T) {
+	t.Chdir(t.TempDir())
+	workingDir, err := os.Getwd()
+	common.Must(err)
+	executable, err := os.Executable()
+	common.Must(err)
+	file, err := os.CreateTemp(filepath.Dir(executable), "lua-*.lua")
+	common.Must(err)
+	common.Must(file.Close())
+	defer os.Remove(file.Name())
+
+	name := filepath.Base(file.Name())
+	paths := []string{
+		filepath.Join(t.TempDir(), name),
+		filepath.Join(t.TempDir(), name),
+		filepath.Join(workingDir, name),
+		file.Name(),
+	}
+	t.Setenv(platform.ConfdirLocation, filepath.Dir(paths[0]))
+	t.Setenv(platform.ConfigLocation, filepath.Dir(paths[1]))
+	for _, path := range paths[:3] {
+		common.Must(os.WriteFile(path, nil, 0o600))
+	}
+	if got, err := ResolveLuaFile(paths[2]); err != nil || got != paths[2] {
+		t.Fatalf("absolute path = %q, %v; want %q", got, err, paths[2])
+	}
+	for i, want := range paths {
+		if i == 2 {
+			t.Setenv(platform.ConfdirLocation, "")
+			t.Setenv(platform.ConfigLocation, "")
+		}
+		if got, err := ResolveLuaFile(name); err != nil || got != want {
+			t.Fatalf("resolved path = %q, %v; want %q", got, err, want)
+		}
+		common.Must(os.Remove(want))
+	}
+	if _, err := ResolveLuaFile(name); !errors.Is(err, os.ErrNotExist) {
+		t.Fatalf("missing file error = %v", err)
+	}
+}

common/platform/others.go

@@ -14,7 +14,7 @@ func LineSeparator() string {
 
 // GetAssetLocation searches for `file` in the env dir, the executable dir, and certain locations
 func GetAssetLocation(file string) string {
-	assetPath := NewEnvFlag(AssetLocation).GetValue(getExecutableDir)
+	assetPath := NewEnvFlag(AssetLocation).GetValue(GetExecutableDir)
 	defPath := filepath.Join(assetPath, file)
 	for _, p := range []string{
 		defPath,
@@ -36,6 +36,6 @@ func GetAssetLocation(file string) string {
 
 // GetCertLocation searches for `file` in the env dir and the executable dir
 func GetCertLocation(file string) string {
-	certPath := NewEnvFlag(CertLocation).GetValue(getExecutableDir)
+	certPath := NewEnvFlag(CertLocation).GetValue(GetExecutableDir)
 	return filepath.Join(certPath, file)
 }

common/platform/platform.go

@@ -1,8 +1,6 @@
 package platform // import "github.com/xtls/xray-core/common/platform"
 
 import (
-	"errors"
-	"fmt"
 	"os"
 	"path/filepath"
 	"strconv"
@@ -74,7 +72,7 @@ func NormalizeEnvName(name string) string {
 	return strings.ReplaceAll(strings.ToUpper(strings.TrimSpace(name)), ".", "_")
 }
 
-func getExecutableDir() string {
+func GetExecutableDir() string {
 	exec, err := os.Executable()
 	if err != nil {
 		return ""
@@ -83,7 +81,7 @@ func getExecutableDir() string {
 }
 
 func GetConfigurationPath() string {
-	configPath := NewEnvFlag(ConfigLocation).GetValue(getExecutableDir)
+	configPath := NewEnvFlag(ConfigLocation).GetValue(GetExecutableDir)
 	return filepath.Join(configPath, "config.json")
 }
 
@@ -92,64 +90,3 @@ func GetConfDirPath() string {
 	configPath := NewEnvFlag(ConfdirLocation).GetValue(func() string { return "" })
 	return configPath
 }
-
-// ResolveLuaFile finds a local .lua script and returns its resolved absolute path.
-// Relative paths: XRAY_LOCATION_CONFDIR > XRAY_LOCATION_CONFIG > working dir > executable dir.
-func ResolveLuaFile(path string) (string, error) {
-	if path == "" {
-		return "", errors.New("Lua file path is empty")
-	}
-	paths := []string{path}
-	if !filepath.IsAbs(path) {
-		paths = nil
-		for _, dir := range []string{
-			GetConfDirPath(),
-			NewEnvFlag(ConfigLocation).GetValue(func() string { return "" }),
-			".",
-			getExecutableDir(),
-		} {
-			if dir != "" {
-				paths = append(paths, filepath.Join(dir, path))
-			}
-		}
-	}
-	path, err := resolveFile(paths)
-	if err != nil {
-		return "", err
-	}
-	return resolveLuaTarget(path)
-}
-
-func resolveLuaTarget(path string) (string, error) {
-	path, err := filepath.EvalSymlinks(path)
-	if err != nil {
-		return "", fmt.Errorf("failed to resolve Lua file symlinks: %w", err)
-	}
-	if filepath.Ext(path) != ".lua" {
-		return "", errors.New("Lua file extension must be .lua")
-	}
-	return path, nil
-}
-
-func resolveFile(paths []string) (string, error) {
-	var tried []string
-	for _, path := range paths {
-		path, err := filepath.Abs(path)
-		if err != nil {
-			return "", fmt.Errorf("failed to resolve file path: %w", err)
-		}
-		tried = append(tried, path)
-		info, err := os.Stat(path)
-		if errors.Is(err, os.ErrNotExist) {
-			continue
-		}
-		if err != nil {
-			return "", fmt.Errorf("failed to inspect file %q: %w", path, err)
-		}
-		if !info.Mode().IsRegular() {
-			return "", fmt.Errorf("file is not a regular file: %s", path)
-		}
-		return path, nil
-	}
-	return "", fmt.Errorf("file not found; tried %q: %w", tried, os.ErrNotExist)
-}

common/platform/platform_test.go

@@ -1,11 +1,9 @@
 package platform_test
 
 import (
-	"errors"
 	"os"
 	"path/filepath"
 	"runtime"
-	"strings"
 	"testing"
 
 	"github.com/xtls/xray-core/common"
@@ -66,89 +64,3 @@ func TestGetAssetLocation(t *testing.T) {
 		}
 	}
 }
-
-func TestResolveLuaFile(t *testing.T) {
-	workingDir := t.TempDir()
-	t.Chdir(workingDir)
-	executable, err := os.Executable()
-	common.Must(err)
-	file, err := os.CreateTemp(filepath.Dir(executable), "lua-*.lua")
-	common.Must(err)
-	common.Must(file.Close())
-	defer os.Remove(file.Name())
-
-	name := filepath.Base(file.Name())
-	paths := []string{
-		filepath.Join(t.TempDir(), name),
-		filepath.Join(t.TempDir(), name),
-		filepath.Join(workingDir, name),
-		file.Name(),
-	}
-	t.Setenv(ConfdirLocation, filepath.Dir(paths[0]))
-	t.Setenv(ConfigLocation, filepath.Dir(paths[1]))
-	for _, path := range paths[:3] {
-		common.Must(os.WriteFile(path, nil, 0o600))
-	}
-	for i, path := range paths {
-		paths[i], err = filepath.EvalSymlinks(path)
-		common.Must(err)
-	}
-	if got, err := ResolveLuaFile(paths[2]); err != nil || got != paths[2] {
-		t.Fatalf("absolute path = %q, %v; want %q", got, err, paths[2])
-	}
-	for i, want := range paths {
-		if i == 2 {
-			t.Setenv(ConfdirLocation, "")
-			t.Setenv(ConfigLocation, "")
-		}
-		if got, err := ResolveLuaFile(name); err != nil || got != want {
-			t.Fatalf("resolved path = %q, %v; want %q", got, err, want)
-		}
-		common.Must(os.Remove(want))
-	}
-	if _, err := ResolveLuaFile(name); !errors.Is(err, os.ErrNotExist) {
-		t.Fatalf("missing file error = %v", err)
-	}
-
-	t.Setenv(ConfdirLocation, filepath.Dir(paths[0]))
-	t.Setenv(ConfigLocation, filepath.Dir(paths[1]))
-	common.Must(os.Mkdir(paths[0], 0o700))
-	common.Must(os.WriteFile(paths[1], nil, 0o600))
-	for _, path := range []string{"", name, filepath.Join(t.TempDir(), name)} {
-		if _, err := ResolveLuaFile(path); err == nil {
-			t.Fatalf("accepted invalid path %q", path)
-		}
-	}
-}
-
-func TestResolveLuaFileSymlink(t *testing.T) {
-	for _, tc := range []struct {
-		link, target string
-		valid        bool
-	}{
-		{"alias.lua", "data.dat", false},
-		{"alias.dat", "script.lua", true},
-	} {
-		t.Run(tc.link, func(t *testing.T) {
-			dir, err := filepath.EvalSymlinks(t.TempDir())
-			common.Must(err)
-			target := filepath.Join(dir, tc.target)
-			common.Must(os.WriteFile(target, nil, 0o600))
-			link := filepath.Join(dir, tc.link)
-			if err := os.Symlink(tc.target, link); err != nil {
-				if runtime.GOOS == "windows" {
-					t.Skipf("cannot create symlinks: %v", err)
-				}
-				t.Fatal(err)
-			}
-			got, err := ResolveLuaFile(link)
-			if tc.valid {
-				if err != nil || got != target {
-					t.Fatalf("ResolveLuaFile(%q) = %q, %v; want %q", link, got, err, target)
-				}
-			} else if err == nil || got != "" || !strings.Contains(err.Error(), "Lua file extension must be .lua") {
-				t.Fatalf("ResolveLuaFile(%q) = %q, %v; want .lua extension error", link, got, err)
-			}
-		})
-	}
-}

common/platform/windows.go

@@ -11,12 +11,12 @@ func LineSeparator() string {
 
 // GetAssetLocation searches for `file` in the env dir and the executable dir
 func GetAssetLocation(file string) string {
-	assetPath := NewEnvFlag(AssetLocation).GetValue(getExecutableDir)
+	assetPath := NewEnvFlag(AssetLocation).GetValue(GetExecutableDir)
 	return filepath.Join(assetPath, file)
 }
 
 // GetCertLocation searches for `file` in the env dir and the executable dir
 func GetCertLocation(file string) string {
-	certPath := NewEnvFlag(CertLocation).GetValue(getExecutableDir)
+	certPath := NewEnvFlag(CertLocation).GetValue(GetExecutableDir)
 	return filepath.Join(certPath, file)
 }