Start writing headers/block_id endpoint

beacon_node/http_api/src/lib.rs

@@ -358,6 +358,35 @@ pub fn serve<T: BeaconChainTypes>(
             },
         );
 
+    // beacon/headers/{block_id}
+    let beacon_headers_block_id = base_path
+        .and(warp::path("beacon"))
+        .and(warp::path("headers"))
+        .and(warp::path::param::<BlockId>())
+        .and(chain_filter.clone())
+        .and_then(|block_id: BlockId, chain: Arc<BeaconChain<T>>| {
+            blocking_json_task(move || {
+                let root = block_id.root(&chain)?;
+                let block = BlockId::from_root(root).block(&chain)?;
+
+                let canonical = chain
+                    .block_root_at_slot(block.slot())
+                    .map_err(crate::reject::beacon_chain_error)?
+                    .map_or(false, |canonical| root == canonical);
+
+                let data = api_types::BlockHeaderData {
+                    root,
+                    canonical,
+                    header: api_types::BlockHeaderAndSignature {
+                        message: block.message.block_header(),
+                        signature: block.signature.into(),
+                    },
+                };
+
+                Ok(api_types::GenericResponse::from(data))
+            })
+        });
+
     /*
      * beacon/blocks/{block_id}
      */
@@ -390,6 +419,7 @@ pub fn serve<T: BeaconChainTypes>(
         .or(beacon_state_validators_id)
         .or(beacon_state_committees)
         .or(beacon_headers)
+        .or(beacon_headers_block_id)
         .or(beacon_block_root)
         .recover(crate::reject::handle_rejection);
 

common/eth2/src/lib.rs

@@ -219,6 +219,24 @@ impl BeaconNodeClient {
         self.get_opt(path).await
     }
 
+    /// `GET beacon/headers/{block_id}`
+    ///
+    /// Returns `Ok(None)` on a 404 error.
+    pub async fn beacon_headers_block_id(
+        &self,
+        block_id: BlockId,
+    ) -> Result<Option<GenericResponse<Vec<BlockHeaderData>>>, Error> {
+        let mut path = self.server.clone();
+
+        path.path_segments_mut()
+            .expect("path is base")
+            .push("beacon")
+            .push("headers")
+            .push(&block_id.to_string());
+
+        self.get_opt(path).await
+    }
+
     /// `GET beacon/blocks/{block_id}/root`
     ///
     /// Returns `Ok(None)` on a 404 error.