Add data columns sidecars debug beacon API (#7591)

Squashed commit of the following:

commit 80fbbc8
Author: Jimmy Chen <jchen.tc@gmail.com>
Date:   Thu Jun 12 11:25:33 2025 +0200

    Fix lint and incorrect condition.

commit 74eec85
Author: Jimmy Chen <jchen.tc@gmail.com>
Date:   Thu Jun 12 10:29:34 2025 +0200

    Add data columns sidecars debug beacon API.

Author: jimmygchen

beacon_node/http_api/src/block_id.rs

@@ -1,14 +1,16 @@
+use crate::version::inconsistent_fork_rejection;
 use crate::{state_id::checkpoint_slot_and_execution_optimistic, ExecutionOptimistic};
 use beacon_chain::kzg_utils::reconstruct_blobs;
 use beacon_chain::{BeaconChain, BeaconChainError, BeaconChainTypes, WhenSlotSkipped};
 use eth2::types::BlobIndicesQuery;
 use eth2::types::BlockId as CoreBlockId;
+use eth2::types::DataColumnIndicesQuery;
 use std::fmt;
 use std::str::FromStr;
 use std::sync::Arc;
 use types::{
-    BlobSidecarList, EthSpec, FixedBytesExtended, Hash256, SignedBeaconBlock,
-    SignedBlindedBeaconBlock, Slot,
+    BlobSidecarList, DataColumnSidecarList, EthSpec, FixedBytesExtended, ForkName, Hash256,
+    SignedBeaconBlock, SignedBlindedBeaconBlock, Slot,
 };
 use warp::Rejection;
 
@@ -19,6 +21,13 @@ pub struct BlockId(pub CoreBlockId);
 
 type Finalized = bool;
 
+type DataColumnsResponse<T> = (
+    DataColumnSidecarList<<T as BeaconChainTypes>::EthSpec>,
+    ForkName,
+    ExecutionOptimistic,
+    Finalized,
+);
+
 impl BlockId {
     pub fn from_slot(slot: Slot) -> Self {
         Self(CoreBlockId::Slot(slot))
@@ -260,6 +269,47 @@ impl BlockId {
         }
     }
 
+    pub fn get_data_columns<T: BeaconChainTypes>(
+        &self,
+        query: DataColumnIndicesQuery,
+        chain: &BeaconChain<T>,
+    ) -> Result<DataColumnsResponse<T>, Rejection> {
+        let (root, execution_optimistic, finalized) = self.root(chain)?;
+        let block = BlockId::blinded_block_by_root(&root, chain)?.ok_or_else(|| {
+            warp_utils::reject::custom_not_found(format!("beacon block with root {}", root))
+        })?;
+
+        if !chain.spec.is_peer_das_enabled_for_epoch(block.epoch()) {
+            return Err(warp_utils::reject::custom_bad_request(
+                "block is pre-Fulu and has no data columns".to_string(),
+            ));
+        }
+
+        let data_column_sidecars = if let Some(indices) = query.indices {
+            indices
+                .iter()
+                .filter_map(|index| chain.get_data_column(&root, index).transpose())
+                .collect::<Result<DataColumnSidecarList<T::EthSpec>, _>>()
+                .map_err(warp_utils::reject::unhandled_error)?
+        } else {
+            chain
+                .get_data_columns(&root)
+                .map_err(warp_utils::reject::unhandled_error)?
+                .unwrap_or_default()
+        };
+
+        let fork_name = block
+            .fork_name(&chain.spec)
+            .map_err(inconsistent_fork_rejection)?;
+
+        Ok((
+            data_column_sidecars,
+            fork_name,
+            execution_optimistic,
+            finalized,
+        ))
+    }
+
     #[allow(clippy::type_complexity)]
     pub fn get_blinded_block_and_blob_list_filtered<T: BeaconChainTypes>(
         &self,

beacon_node/http_api/src/lib.rs

@@ -2883,6 +2883,55 @@ pub fn serve<T: BeaconChainTypes>(
      * debug
      */
 
+    // GET debug/beacon/data_column_sidecars/{block_id}
+    let get_debug_data_column_sidecars = eth_v1
+        .and(warp::path("debug"))
+        .and(warp::path("beacon"))
+        .and(warp::path("data_column_sidecars"))
+        .and(block_id_or_err)
+        .and(warp::path::end())
+        .and(multi_key_query::<api_types::DataColumnIndicesQuery>())
+        .and(task_spawner_filter.clone())
+        .and(chain_filter.clone())
+        .and(warp::header::optional::<api_types::Accept>("accept"))
+        .then(
+            |block_id: BlockId,
+             indices_res: Result<api_types::DataColumnIndicesQuery, warp::Rejection>,
+             task_spawner: TaskSpawner<T::EthSpec>,
+             chain: Arc<BeaconChain<T>>,
+             accept_header: Option<api_types::Accept>| {
+                task_spawner.blocking_response_task(Priority::P1, move || {
+                    let indices = indices_res?;
+                    let (data_columns, fork_name, execution_optimistic, finalized) =
+                        block_id.get_data_columns(indices, &chain)?;
+
+                    match accept_header {
+                        Some(api_types::Accept::Ssz) => Response::builder()
+                            .status(200)
+                            .body(data_columns.as_ssz_bytes().into())
+                            .map(|res: Response<Body>| add_ssz_content_type_header(res))
+                            .map_err(|e| {
+                                warp_utils::reject::custom_server_error(format!(
+                                    "failed to create response: {}",
+                                    e
+                                ))
+                            }),
+                        _ => {
+                            // Post as a V2 endpoint so we return the fork version.
+                            let res = execution_optimistic_finalized_beacon_response(
+                                ResponseIncludesVersion::Yes(fork_name),
+                                execution_optimistic,
+                                finalized,
+                                &data_columns,
+                            )?;
+                            Ok(warp::reply::json(&res).into_response())
+                        }
+                    }
+                    .map(|resp| add_consensus_version_header(resp, fork_name))
+                })
+            },
+        );
+
     // GET debug/beacon/states/{state_id}
     let get_debug_beacon_states = any_version
         .and(warp::path("debug"))
@@ -4950,6 +4999,7 @@ pub fn serve<T: BeaconChainTypes>(
                 .uor(get_config_spec)
                 .uor(get_config_deposit_contract)
                 .uor(get_debug_beacon_states)
+                .uor(get_debug_data_column_sidecars)
                 .uor(get_debug_beacon_heads)
                 .uor(get_debug_fork_choice)
                 .uor(get_node_identity)

common/eth2/src/types.rs

@@ -701,6 +701,13 @@ pub struct BlobIndicesQuery {
     pub indices: Option<Vec<u64>>,
 }
 
+#[derive(Clone, Deserialize)]
+#[serde(deny_unknown_fields)]
+pub struct DataColumnIndicesQuery {
+    #[serde(default, deserialize_with = "option_query_vec")]
+    pub indices: Option<Vec<u64>>,
+}
+
 #[derive(Clone, Serialize, Deserialize)]
 #[serde(transparent)]
 pub struct ValidatorIndexData(#[serde(with = "serde_utils::quoted_u64_vec")] pub Vec<u64>);