add relay blocking option

relay.yaml.example

@@ -20,4 +20,5 @@ ap:
   whitelist_enabled: false
   whitelist:
   - 'good-instance.example.com'
-  - 'another.good-instance.example.com'
+  - 'another.good-instance.example.com'
+  block_relays: false

relay/__init__.py

@@ -23,6 +23,7 @@ def load_config():
             'port': int(yaml_file.get('port', 8080)),
             'note': yaml_file.get('note', 'Make a note about your instance here.'),
             'ap': {
+                'block_relays': yaml_file['ap'].get('block_relays', False),
                 'blocked_instances': yaml_file['ap'].get('blocked_instances', []),
                 'host': yaml_file['ap'].get('host', 'localhost'),
                 'whitelist': yaml_file['ap'].get('whitelist', []),

relay/actor.py

@@ -103,6 +103,12 @@ async def push_message_to_actor(actor, message, our_key_id):
             logging.info('Caught %r while pushing to %r.', e, inbox)
 
 
+async def fetch_nodeinfo(domain):
+    nodeinfo_data = await fetch_actor(f'https://{domain}/nodeinfo/2.0.json')
+    software = nodeinfo_data.get('software')
+    return software.get('name') if software else None
+
+
 async def follow_remote_actor(actor_uri):
     actor = await fetch_actor(actor_uri)
     
@@ -235,6 +241,7 @@ async def handle_follow(actor, data, request):
     following = DATABASE.get('relay-list', [])
     inbox = get_actor_inbox(actor)
 
+
     if urlsplit(inbox).hostname in AP_CONFIG['blocked_instances']:
         return
 
@@ -294,6 +301,12 @@ async def inbox(request):
     data = await request.json()
     instance = urlsplit(data['actor']).hostname
 
+    if AP_CONFIG['block_relays']:
+        software = await fetch_nodeinfo(instance)
+
+        if software and 'relay' in software.lower():
+            raise aiohttp.web.HTTPUnauthorized(body='relays have been blocked', content_type='text/plain')
+
     if 'actor' not in data or not request['validated']:
         raise aiohttp.web.HTTPUnauthorized(body='access denied', content_type='text/plain')