refactor: update lib modules (common, dnsmasq, logging, network, state, nginx)

lib/common.py

@@ -6,12 +6,38 @@ deep merging, and directory creation used across all subsystem modules.
 
 import json
 import os
+import re
 import subprocess
 from copy import deepcopy
 from pathlib import Path
 from typing import Any
 
 
+def validate_interface_name(name: str) -> str:
+    """Validate a Linux network interface name.
+
+    Args:
+        name: Interface name to validate.
+
+    Returns:
+        The validated (stripped) name.
+
+    Raises:
+        ValueError: When the name is empty, contains path components,
+            or does not match Linux interface naming rules.
+    """
+    if not name or not isinstance(name, str):
+        raise ValueError("Interface name must be a non-empty string")
+    name = name.strip()
+    if not name:
+        raise ValueError("Interface name must not be blank")
+    if "/" in name or ".." in name or " " in name:
+        raise ValueError(f"Invalid interface name: {name!r}")
+    if not re.match(r"^[a-zA-Z0-9][a-zA-Z0-9._-]*$", name):
+        raise ValueError(f"Invalid interface name: {name!r}")
+    return name
+
+
 def run(
     cmd: list[str],
     check: bool = True,
@@ -134,4 +160,5 @@ __all__ = [
     "run",
     "run_proc",
     "save_json",
+    "validate_interface_name",
 ]