phase 10

internal/storage/store.go

@@ -9,6 +9,7 @@ import (
 	"path/filepath"
 	"strings"
 	"time"
+	"unicode"
 )
 
 // ErrNotFound is returned when the requested interface does not exist.
@@ -35,6 +36,21 @@ func New(storageDir string) (*Store, error) {
 	return &Store{dir: dir}, nil
 }
 
+// validateID returns an error if id could be used for path traversal or is
+// otherwise unsafe.  Valid IDs contain only letters, digits, hyphens, and
+// underscores.
+func validateID(id string) error {
+	if id == "" {
+		return fmt.Errorf("interface ID must not be empty")
+	}
+	for _, r := range id {
+		if !unicode.IsLetter(r) && !unicode.IsDigit(r) && r != '-' && r != '_' {
+			return fmt.Errorf("invalid character %q in interface ID", r)
+		}
+	}
+	return nil
+}
+
 func (s *Store) filePath(id string) string {
 	return filepath.Join(s.dir, id+".xml")
 }
@@ -85,6 +101,9 @@ func (s *Store) readMeta(id string) (InterfaceMeta, error) {
 
 // Get returns the raw XML bytes for the interface with the given ID.
 func (s *Store) Get(id string) ([]byte, error) {
+	if err := validateID(id); err != nil {
+		return nil, fmt.Errorf("%w: %v", ErrNotFound, err)
+	}
 	data, err := os.ReadFile(s.filePath(id))
 	if errors.Is(err, os.ErrNotExist) {
 		return nil, ErrNotFound
@@ -114,6 +133,9 @@ func (s *Store) Create(xmlData []byte) (string, error) {
 
 // Update replaces the XML for an existing interface.
 func (s *Store) Update(id string, xmlData []byte) error {
+	if err := validateID(id); err != nil {
+		return ErrNotFound
+	}
 	if _, err := os.Stat(s.filePath(id)); errors.Is(err, os.ErrNotExist) {
 		return ErrNotFound
 	}
@@ -122,6 +144,9 @@ func (s *Store) Update(id string, xmlData []byte) error {
 
 // Delete removes the interface with the given ID.
 func (s *Store) Delete(id string) error {
+	if err := validateID(id); err != nil {
+		return ErrNotFound
+	}
 	err := os.Remove(s.filePath(id))
 	if errors.Is(err, os.ErrNotExist) {
 		return ErrNotFound
@@ -131,6 +156,9 @@ func (s *Store) Delete(id string) error {
 
 // Clone duplicates an interface, assigning a new unique ID.
 func (s *Store) Clone(srcID string) (string, error) {
+	if err := validateID(srcID); err != nil {
+		return "", ErrNotFound
+	}
 	data, err := s.Get(srcID)
 	if err != nil {
 		return "", err