feat: add event kind blacklist

Adds a list to the config where you can specify which event kinds to blacklist.
The blacklist check will run right after verifying that the pubkey is allowed
to post events to the relay.

config.toml

@@ -100,6 +100,11 @@ reject_future_seconds = 1800
 # backpressure to senders if writes are slow.
 #event_persist_buffer = 4096
 
+# Event kind blacklist. Events with these kinds will be discarded.
+#event_kind_blacklist = [
+#    70202,
+#]
+
 [authorization]
 # Pubkey addresses in this array are whitelisted for event publishing.
 # Only valid events by these authors will be accepted, if the variable

src/config.rs

@@ -60,6 +60,7 @@ pub struct Limits {
     pub max_ws_frame_bytes: Option<usize>,
     pub broadcast_buffer: usize, // events to buffer for subscribers (prevents slow readers from consuming memory)
     pub event_persist_buffer: usize, // events to buffer for database commits (block senders if database writes are too slow)
+    pub event_kind_blacklist: Option<Vec<u64>>
 }
 
 #[derive(Debug, Clone, Serialize, Deserialize)]
@@ -225,6 +226,7 @@ impl Default for Settings {
                 max_ws_frame_bytes: Some(2 << 17),   // 128K
                 broadcast_buffer: 16384,
                 event_persist_buffer: 4096,
+                event_kind_blacklist: None,
             },
             authorization: Authorization {
                 pubkey_whitelist: None, // Allow any address to publish

src/db.rs

@@ -232,6 +232,24 @@ pub async fn db_writer(
                 }
             }
 
+            // Check that event kind isn't blacklisted
+            let kinds_blacklist = &settings.limits.event_kind_blacklist.clone();
+            if let Some(event_kind_blacklist) = kinds_blacklist {
+                if event_kind_blacklist.contains(&event.kind) {
+                    info!(
+                        "Rejecting event {}, blacklisted kind",
+                        &event.get_event_id_prefix()
+                    );
+                    notice_tx
+                        .try_send(Notice::blocked(
+                            event.id,
+                            "event kind is blocked by relay"
+                        ))
+                        .ok();
+                    continue;
+                }
+            }
+
             // send any metadata events to the NIP-05 verifier
             if nip05_active && event.is_kind_metadata() {
                 // we are sending this prior to even deciding if we