Add webhook + IFTTT example (#16817)

* Add webhook + IFTTT example

* Abort if not externally accessible

* Abort on local url

* Add description to create entry

* Make body optional

* Allow ifttt setup without config

* Add tests

* Lint

* Fix Lint + Tests

* Fix typing

homeassistant/components/auth/indieauth.py

@@ -1,24 +1,13 @@
 """Helpers to resolve client ID/secret."""
 import asyncio
+from ipaddress import ip_address
 from html.parser import HTMLParser
-from ipaddress import ip_address, ip_network
 from urllib.parse import urlparse, urljoin
 
 import aiohttp
 from aiohttp.client_exceptions import ClientError
 
-# IP addresses of loopback interfaces
-ALLOWED_IPS = (
-    ip_address('127.0.0.1'),
-    ip_address('::1'),
-)
-
-# RFC1918 - Address allocation for Private Internets
-ALLOWED_NETWORKS = (
-    ip_network('10.0.0.0/8'),
-    ip_network('172.16.0.0/12'),
-    ip_network('192.168.0.0/16'),
-)
+from homeassistant.util.network import is_local
 
 
 async def verify_redirect_uri(hass, client_id, redirect_uri):
@@ -185,9 +174,7 @@ def _parse_client_id(client_id):
         # Not an ip address
         pass
 
-    if (address is None or
-            address in ALLOWED_IPS or
-            any(address in network for network in ALLOWED_NETWORKS)):
+    if address is None or is_local(address):
         return parts
 
     raise ValueError('Hostname should be a domain name or local IP address')