test nic state link api

backend/src/utilities/interface_bridge_helpers.py

@@ -1,4 +1,4 @@
-from typing import List, Dict, Optional
+from typing import List, Optional
 import logging
 import os
 
@@ -30,6 +30,49 @@ def check_interface_up(iface: str) -> bool:
         return False
 
 
+def _read_sysfs_text(path: str) -> Optional[str]:
+    """Read one sysfs file and return stripped text, or `None` if unavailable."""
+    try:
+        with open(path, "r") as f:
+            return f.read().strip()
+    except FileNotFoundError:
+        return None
+    except Exception:
+        logger.exception("Error reading sysfs path %s", path)
+        return None
+
+
+def read_interface_operstate(iface: str) -> Optional[str]:
+    """Return the kernel operstate string for an interface."""
+    return _read_sysfs_text(f"/sys/class/net/{iface}/operstate")
+
+
+def read_interface_carrier(iface: str) -> Optional[bool]:
+    """Return the carrier state for an interface if available."""
+    value = _read_sysfs_text(f"/sys/class/net/{iface}/carrier")
+    if value is None:
+        return None
+
+    try:
+        return int(value, 10) == 1
+    except ValueError:
+        logger.warning("Unexpected carrier value for %s: %r", iface, value)
+        return None
+
+
+def read_interface_admin_up(iface: str) -> Optional[bool]:
+    """Return whether the interface has the IFF_UP flag set."""
+    value = _read_sysfs_text(f"/sys/class/net/{iface}/flags")
+    if value is None:
+        return None
+
+    try:
+        return bool(int(value, 0) & 0x1)
+    except ValueError:
+        logger.warning("Unexpected flags value for %s: %r", iface, value)
+        return None
+
+
 def _read_bridge_ports_from_sysfs(bridge: str) -> List[str]:
     """
     Read bridge member interfaces from sysfs. Internal helper that always reads.