filter: add kind blacklist filter

Signed-off-by: William Casarin <jb55@jb55.com>

README.md

@@ -14,15 +14,22 @@ You can add any new filter you want by implementing the `NoteFilter` trait and r
 The `pipeline` config specifies the order in which filters are run. When the first `reject` or `shadowReject` action is hit, then the pipeline stops and returns the rejection error.
 
 ```toml
-pipeline = ["protected_events", "whitelist", "ratelimit"]
+pipeline = ["protected_events", "kinds", "whitelist", "ratelimit"]
 
 [filters.ratelimit]
 posts_per_minute = 8
 whitelist = ["127.0.0.1"]
 
 [filters.whitelist]
-pubkeys = ["32e1827635450ebb3c5a7d12c1f8e7b2b514439ac10a67eef3d9fd9c5c68e245"]
-ips = ["127.0.0.1", "127.0.0.2"]
+pubkeys = ["16c21558762108afc34e4ff19e4ed51d9a48f79e0c34531efc423d21ab435e93"]
+ips = ["127.0.0.1"]
+
+[filters.kinds]
+kinds = [30065, 1064]
+
+[filters.kinds.messages]
+30065 = "blocked: files on nostr is dumb"
+1064 = "blocked: files on nostr is dumb"
 
 [filters.protected_events]
 ```
@@ -57,6 +64,27 @@ The whitelist filter only allows notes to pass if it matches a particular pubkey
 
 Either criteria can match
 
+### Kinds
+
+* name: `kinds`
+
+A filter that blacklists certain kinds
+
+- `kinds`: a list of kind integers to block
+
+- `kinds.messages` *optional*: a map of kinds to message to deliver when the kind is blocked
+
+Example:
+
+```toml
+[filters.kinds]
+kinds = [30065, 1064]
+
+[filters.kinds.messages]
+30065 = "blocked: files on nostr is dumb"
+1064 = "blocked: files on nostr is dumb"
+```
+
 ### Protected Events
 
 See [nip70]

noteguard.toml

@@ -1,5 +1,5 @@
 
-pipeline = ["protected_events", "whitelist", "ratelimit"]
+pipeline = ["protected_events", "kinds", "whitelist", "ratelimit"]
 
 [filters.ratelimit]
 posts_per_minute = 8
@@ -9,4 +9,13 @@ whitelist = ["127.0.0.1"]
 pubkeys = ["16c21558762108afc34e4ff19e4ed51d9a48f79e0c34531efc423d21ab435e93"]
 ips = ["127.0.0.1"]
 
+[filters.kinds]
+kinds = [30065, 1064, 34550, 4550]
+
+[filters.kinds.messages]
+30065 = "blocked: files on nostr is dumb"
+1064 = "blocked: files on nostr is dumb"
+34550 = "blocked: please use a dedicated relay for moderated communities"
+4550 = "blocked: please use a dedicated relay for moderated communities"
+
 [filters.protected_events]

src/filters/kinds.rs

@@ -0,0 +1,29 @@
+use crate::{Action, InputMessage, NoteFilter, OutputMessage};
+use serde::Deserialize;
+use std::collections::HashMap;
+
+#[derive(Deserialize, Default)]
+pub struct Kinds {
+    kinds: Vec<i64>,
+    messages: Option<HashMap<String, String>>,
+}
+
+impl NoteFilter for Kinds {
+    fn filter_note(&mut self, input: &InputMessage) -> OutputMessage {
+        let kind = input.event.kind;
+        if self.kinds.contains(&kind) {
+            let msg = self
+                .messages
+                .as_ref()
+                .and_then(|msgs| msgs.get(&kind.to_string()).cloned())
+                .unwrap_or_else(|| "blocked: note kind is not allowed here".to_string());
+            OutputMessage::new(input.event.id.clone(), Action::Reject, Some(msg))
+        } else {
+            OutputMessage::new(input.event.id.clone(), Action::Accept, None)
+        }
+    }
+
+    fn name(&self) -> &'static str {
+        "kinds"
+    }
+}

src/filters/mod.rs

@@ -1,7 +1,9 @@
+mod kinds;
 mod protected_events;
 mod ratelimit;
 mod whitelist;
 
+pub use kinds::Kinds;
 pub use protected_events::ProtectedEvents;
 pub use ratelimit::RateLimit;
 pub use whitelist::Whitelist;

src/main.rs

@@ -1,4 +1,4 @@
-use noteguard::filters::{ProtectedEvents, RateLimit, Whitelist};
+use noteguard::filters::{Kinds, ProtectedEvents, RateLimit, Whitelist};
 use noteguard::{Action, InputMessage, NoteFilter, OutputMessage};
 use serde::de::DeserializeOwned;
 use serde::Deserialize;
@@ -43,6 +43,7 @@ impl Noteguard {
         self.register_filter::<RateLimit>();
         self.register_filter::<Whitelist>();
         self.register_filter::<ProtectedEvents>();
+        self.register_filter::<Kinds>();
     }
 
     /// Run the loaded filters. You must call `load_config` before calling this, otherwise