sane-ip-check: implement a retry loop

pkgs/additional/sane-scripts/src/sane-ip-check

@@ -14,11 +14,16 @@ import logging
 import requests
 import subprocess
 import sys
+import time
 
 from sane_ssdp import get_any_wan
 
 logger = logging.getLogger(__name__)
 
+# retry on failure to get IP address until this much time has elapsed.
+# not a strict deadline/timeout
+MAX_DURATION = 45.0
+
 def get_wan_fallback():
     "untrusted method in which to get the WAN IP"
     r = requests.get("https://ipinfo.io/ip")
@@ -29,13 +34,28 @@ def get_wan_fallback():
     else:
         return ip
 
-def main(format: str, try_upnp: bool, expect: str|None) -> None:
+def try_get_once(try_upnp: bool) -> tuple[str|None, str]:
     upnp_details = get_any_wan() if try_upnp else None
     if upnp_details:
         root_dev, _lan_ip, wan_ip = upnp_details
     else:
         root_dev, wan_ip = "", get_wan_fallback()
 
+    return root_dev, wan_ip
+
+def get_fault_tolerant(try_upnp: bool) -> tuple[str|None, str]:
+    start = time.time()
+    while True:
+        try:
+            return try_get_once(try_upnp)
+        except Exception as e:
+            logger.warn(e)
+            if time.time() - start > MAX_DURATION:
+                raise
+
+def main(format: str, try_upnp: bool, expect: str|None) -> None:
+    root_dev, wan_ip = get_fault_tolerant(try_upnp)
+
     if expect:
         assert wan_ip == expect, f"actual IP {wan_ip} != expected IP {expect}"