templates: add ip_in_networks test

src/capport/api/app.py

@@ -7,4 +7,5 @@ app = MyQuartApp(__name__)
 __import__('capport.api.setup')
 __import__('capport.api.proxy_fix')
 __import__('capport.api.lang')
+__import__('capport.api.template_filters')
 __import__('capport.api.views')

src/capport/api/template_filters.py

@@ -0,0 +1,16 @@
+from __future__ import annotations
+
+import ipaddress
+import typing
+
+from .app import app
+
+
+@app.add_template_test
+def ip_in_networks(ip_s: str, networks: typing.Iterable[str]) -> bool:
+    ip = ipaddress.ip_address(ip_s)
+    for network in networks:
+        net = ipaddress.ip_network(network)
+        if ip in net:
+            return True
+    return False