ryerraguntla commented on code in PR #4258:
URL: https://github.com/apache/iggy/pull/4258#discussion_r4093329062
##########
gateways/kafka/src/protocol/handlers/metadata.rs:
##########
@@ -53,23 +73,271 @@ pub async fn handle(state: &GatewayState, api_version:
i16, body: Bytes) -> Hand
);
return HandleOutcome::Close;
}
- match decode_topics(api_version, body, state.max_frame_size) {
- Ok(topics) => respond_or_close(
- encode_response(api_version, &topics, &state.broker, ERROR_NONE),
- "Metadata",
- ),
+
+ let Some(bridge) = &state.bridge else {
+ return match decode_topics(api_version, body, state.max_frame_size) {
+ Ok(topics) => respond_or_close(
+ encode_response(api_version, &topics, &state.broker,
ERROR_NONE),
+ "Metadata",
+ ),
+ Err(error) => {
+ // Metadata has no top-level error field; a malformed body
cannot carry
+ // INVALID_REQUEST in a version-correct way for every client.
Close.
+ // debug!, not warn!: attacker-controlled, not
operator-actionable.
+ tracing::debug!(
+ %error,
+ api_version,
+ "Failed to decode Metadata request; closing connection"
+ );
+ HandleOutcome::Close
+ }
+ };
+ };
+
+ let requested = match decode_requested_topics(api_version, body,
state.max_frame_size) {
+ Ok(requested) => requested,
Err(error) => {
- // Metadata has no top-level error field; a malformed body cannot
carry
- // INVALID_REQUEST in a version-correct way for every client.
Close.
- // debug!, not warn!: attacker-controlled, not operator-actionable.
tracing::debug!(
%error,
api_version,
"Failed to decode Metadata request; closing connection"
);
- HandleOutcome::Close
+ return HandleOutcome::Close;
}
+ };
+
+ let results = match requested {
+ None => match bridge.list_kafka_topics().await {
+ Ok(topics) => {
+ let results: Vec<TopicResult> =
topics.into_iter().map(found_result).collect();
+ truncate_all_topics_to_frame_budget(results,
state.max_frame_size)
+ }
+ Err(error) => {
+ // Same "no top-level error field" constraint as a decode
failure: there is no
+ // way to answer "the bridge itself is unreachable" for an
all-topics request
+ // that doesn't also falsely claim zero topics exist.
+ tracing::warn!(%error, "Failed to list Kafka topics from the
Iggy bridge; closing connection");
+ return HandleOutcome::Close;
+ }
+ },
+ Some(names) => resolve_requested_named_topics(bridge, &names).await,
+ };
+
+ // `bounds_guard` cannot see this: it charges the projected response by
*requested* element
+ // (one topic name), but one real topic can carry up to Iggy's own
per-topic partition cap
+ // (1000) - a handful of names can still expand into a response
`bounds_guard` never had the
+ // information to price in before this bridge round trip returned. The
all-topics arm is
+ // pre-truncated to this same budget above
(`truncate_all_topics_to_frame_budget`) since its
+ // size is server-side, not client-controllable - closing over it would
take down every
+ // client's bootstrap Metadata call, permanently, the moment the catalog
grows past the
+ // trip point. This check is what still enforces the budget for the
named-lookup arm, where
+ // the cap (100 distinct topics) bounds the request but not what each one
costs to answer.
+ let total_bytes: usize =
results.iter().map(estimated_response_bytes).sum();
+ if response_would_exceed_frame_size(total_bytes, state.max_frame_size) {
+ tracing::warn!(
+ total_bytes,
+ max_frame_size = state.max_frame_size,
+ "Metadata response would exceed max_frame_size; closing connection"
+ );
+ return HandleOutcome::Close;
}
+
+ respond_or_close(
+ encode_real_response(api_version, &results, &state.broker),
+ "Metadata",
+ )
+}
+
+/// Resolves a named-lookup Metadata request's topics: dedupes first so every
path below (cap,
+/// deadline, success) builds its response from the distinct set rather than
one entry per
+/// request occurrence - real Kafka answers a topic named more than once with
one response entry,
+/// not one per repeat, and re-expanding to match the request let a handful of
repeats of one
+/// large topic name amplify a response sized off the repeat count instead of
the distinct count.
+async fn resolve_requested_named_topics(
+ bridge: &IggyBridge,
+ names: &[StrBytes],
+) -> Vec<TopicResult> {
+ let distinct = dedup_topic_names(names);
+ if distinct.len() > MAX_BRIDGE_BACKED_TOPICS {
Review Comment:
removed. Added IggyBridge::get_kafka_topics, which batches by the stream
each name resolves to rather than by name count — a long-lived Java producer
whose ProducerMetadata cumulative topic set crosses 100 no longer gets
permanently bricked.
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