Add installer patch for VM bridge guard

scripts/patch_vm_network_guard.py

@@ -0,0 +1,53 @@
+#!/usr/bin/env python3
+from pathlib import Path
+import sys
+
+app_path = Path(sys.argv[1]) if len(sys.argv) > 1 else Path('/opt/virtuality/web/app.py')
+if not app_path.exists():
+    raise SystemExit(f'app.py not found: {app_path}')
+
+text = app_path.read_text()
+changed = []
+
+helper = '''
+
+def bridge_exists(name: str) -> bool:
+    if not name or not re.fullmatch(r"[a-zA-Z0-9_.:-]+", name):
+        return False
+    return run_cmd(["ip", "link", "show", name], timeout=5)["ok"]
+'''
+
+if 'def bridge_exists(name: str) -> bool:' not in text:
+    marker = '\n\ndef default_network_mode() -> str:'
+    if marker not in text:
+        raise SystemExit('default_network_mode marker not found')
+    text = text.replace(marker, helper + marker, 1)
+    changed.append('bridge_exists helper added')
+else:
+    changed.append('bridge_exists helper already present')
+
+old_validation = '''    elif network_mode == "bridge" and (not bridge or not re.fullmatch(r"[a-zA-Z0-9_.:-]+", bridge)):
+        error = "Некорректное имя bridge."
+    else:
+        iso = Path(iso_path).resolve()
+'''
+new_validation = '''    elif network_mode == "bridge" and (not bridge or not re.fullmatch(r"[a-zA-Z0-9_.:-]+", bridge)):
+        error = "Некорректное имя bridge."
+    elif network_mode == "bridge" and not bridge_exists(bridge):
+        error = f"Bridge {bridge} не найден на сервере. Для VPS выбери режим NAT Router — virtuality-nat, либо сначала создай bridge {bridge}."
+    else:
+        iso = Path(iso_path).resolve()
+'''
+
+if old_validation in text:
+    text = text.replace(old_validation, new_validation, 1)
+    changed.append('bridge existence validation added')
+elif new_validation in text:
+    changed.append('bridge existence validation already present')
+else:
+    raise SystemExit('bridge validation marker not found')
+
+app_path.write_text(text)
+print('vm network guard patch applied:')
+for item in changed:
+    print(f'- {item}')