fix(relay): reject events containing NUL characters at validation time

crates/buzz-relay/src/handlers/ingest.rs

@@ -1754,6 +1754,21 @@ fn validate_not_before(tag_value: &str) -> Result<u64, &'static str> {
     Ok(value)
 }
 
+/// Postgres cannot store NUL in `text`/`jsonb` columns, so an event carrying
+/// `\u0000` in its content or tag values would otherwise pass validation and
+/// then fail at insert time as an internal database error.
+fn validate_no_nul_bytes(event: &Event) -> Result<(), &'static str> {
+    if event.content.contains('\0') {
+        return Err("content contains a NUL character");
+    }
+    for tag in event.tags.iter() {
+        if tag.as_slice().iter().any(|value| value.contains('\0')) {
+            return Err("tag value contains a NUL character");
+        }
+    }
+    Ok(())
+}
+
 /// Validate the public tag envelope of a NIP-ER `kind:30300` event before it
 /// reaches NIP-33 parameterized replacement.
 ///
@@ -2020,6 +2035,10 @@ async fn ingest_event_inner(
         )));
     }
 
+    if let Err(e) = validate_no_nul_bytes(&event) {
+        return Err(IngestError::Rejected(format!("invalid: {e}")));
+    }
+
     let is_gift_wrap = kind_u32 == KIND_GIFT_WRAP;
     if event.pubkey != *auth.pubkey() && !is_gift_wrap {
         return Err(IngestError::AuthFailed(
@@ -3957,6 +3976,43 @@ mod tests {
         }
     }
 
+    #[test]
+    fn nul_validation_rejects_content_with_nul() {
+        let event = make_event_with_tags(KIND_STREAM_MESSAGE, "hello\0world", &[]);
+        assert_eq!(
+            validate_no_nul_bytes(&event),
+            Err("content contains a NUL character")
+        );
+    }
+
+    #[test]
+    fn nul_validation_rejects_tag_value_with_nul() {
+        let event = make_event_with_tags(KIND_STREAM_MESSAGE, "hello", &[&["title", "a\0b"]]);
+        assert_eq!(
+            validate_no_nul_bytes(&event),
+            Err("tag value contains a NUL character")
+        );
+    }
+
+    #[test]
+    fn nul_validation_rejects_tag_name_with_nul() {
+        let event = make_event_with_tags(KIND_STREAM_MESSAGE, "hello", &[&["ti\0tle", "a"]]);
+        assert_eq!(
+            validate_no_nul_bytes(&event),
+            Err("tag value contains a NUL character")
+        );
+    }
+
+    #[test]
+    fn nul_validation_accepts_clean_event() {
+        let event = make_event_with_tags(
+            KIND_STREAM_MESSAGE,
+            "hello world",
+            &[&["title", "greeting"]],
+        );
+        assert!(validate_no_nul_bytes(&event).is_ok());
+    }
+
     fn make_dummy_event() -> Event {
         let keys = nostr::Keys::generate();
         nostr::EventBuilder::new(nostr::Kind::Custom(9), "")