Implement configuration management, drag-and-drop functionality, and logging utilities for WebDrop Bridge

src/webdrop_bridge/core/validator.py

@@ -0,0 +1,97 @@
+"""Path validation for secure file operations."""
+
+from pathlib import Path
+from typing import List
+
+
+class ValidationError(Exception):
+    """Raised when path validation fails."""
+
+    pass
+
+
+class PathValidator:
+    """Validates file paths against security whitelist.
+
+    Ensures that only files within allowed root directories can be accessed.
+    All paths are resolved to absolute form before validation to prevent
+    directory traversal attacks.
+    """
+
+    def __init__(self, allowed_roots: List[Path]):
+        """Initialize validator with allowed root directories.
+
+        Args:
+            allowed_roots: List of Path objects representing allowed root dirs
+
+        Raises:
+            ValidationError: If any root doesn't exist or isn't a directory
+        """
+        self.allowed_roots = []
+
+        for root in allowed_roots:
+            root_path = Path(root).resolve()
+            if not root_path.exists():
+                raise ValidationError(
+                    f"Allowed root '{root}' does not exist"
+                )
+            if not root_path.is_dir():
+                raise ValidationError(
+                    f"Allowed root '{root}' is not a directory"
+                )
+            self.allowed_roots.append(root_path)
+
+    def validate(self, path: Path) -> bool:
+        """Validate that path is within an allowed root directory.
+
+        Args:
+            path: File path to validate
+
+        Returns:
+            True if path is valid and accessible
+
+        Raises:
+            ValidationError: If path fails validation
+        """
+        try:
+            # Resolve to absolute path (handles symlinks, .., etc)
+            file_path = Path(path).resolve()
+        except (OSError, ValueError) as e:
+            raise ValidationError(f"Cannot resolve path '{path}': {e}") from e
+
+        # Check file exists
+        if not file_path.exists():
+            raise ValidationError(f"File does not exist: {path}")
+
+        # Check it's a regular file (not directory, symlink to dir, etc)
+        if not file_path.is_file():
+            raise ValidationError(f"Path is not a regular file: {path}")
+
+        # Check path is within an allowed root
+        for allowed_root in self.allowed_roots:
+            try:
+                # This raises ValueError if file_path is not relative to root
+                file_path.relative_to(allowed_root)
+                return True
+            except ValueError:
+                continue
+
+        # Not in any allowed root
+        raise ValidationError(
+            f"Path '{file_path}' is not within allowed roots: "
+            f"{self.allowed_roots}"
+        )
+
+    def is_valid(self, path: Path) -> bool:
+        """Check if path is valid without raising exception.
+
+        Args:
+            path: File path to check
+
+        Returns:
+            True if valid, False otherwise
+        """
+        try:
+            return self.validate(path)
+        except ValidationError:
+            return False