Make max_blobs_per_block a config parameter (#6329)

* First pass

* Add restrictions to RuntimeVariableList api

* Use empty_uninitialized and fix warnings

* Fix some todos

* Merge branch 'unstable' into max-blobs-preset

* Fix take impl on RuntimeFixedList

* cleanup

* Fix test compilations

* Fix some more tests

* Fix test from unstable

* Merge branch 'unstable' into max-blobs-preset

* Merge remote-tracking branch 'origin/unstable' into max-blobs-preset

* Remove footgun function

* Minor simplifications

* Move from preset to config

* Fix typo

* Revert "Remove footgun function"

This reverts commit de01f923c7.

* Try fixing tests

* Thread through ChainSpec

* Fix release tests

* Move RuntimeFixedVector into module and rename

* Add test

* Remove empty RuntimeVarList awefullness

* Fix tests

* Simplify BlobSidecarListFromRoot

* Merge remote-tracking branch 'origin/unstable' into max-blobs-preset

* Bump quota to account for new target (6)

* Remove clone

* Fix issue from review

* Try to remove ugliness

* Merge branch 'unstable' into max-blobs-preset

* Fix max value

* Fix doctest

* Fix formatting

* Fix max check

* Delete hardcoded max_blobs_per_block in RPC limits

* Merge remote-tracking branch 'origin/unstable' into max-blobs-preset

beacon_node/network/src/sync/network_context.rs

@@ -67,6 +67,15 @@ pub enum RangeRequestId {
     },
 }
 
+impl RangeRequestId {
+    pub fn batch_id(&self) -> BatchId {
+        match self {
+            RangeRequestId::RangeSync { batch_id, .. } => *batch_id,
+            RangeRequestId::BackfillSync { batch_id, .. } => *batch_id,
+        }
+    }
+}
+
 #[derive(Debug)]
 pub enum RpcEvent<T> {
     StreamTermination,
@@ -445,11 +454,14 @@ impl<T: BeaconChainTypes> SyncNetworkContext<T> {
                 (None, None)
             };
 
+        // TODO(pawan): this would break if a batch contains multiple epochs
+        let max_blobs_len = self.chain.spec.max_blobs_per_block(epoch);
         let info = RangeBlockComponentsRequest::new(
             expected_blobs,
             expects_columns,
             num_of_column_req,
             requested_peers,
+            max_blobs_len as usize,
         );
         self.range_block_components_requests
             .insert(id, (sender_id, info));
@@ -950,12 +962,23 @@ impl<T: BeaconChainTypes> SyncNetworkContext<T> {
     ) -> Option<RpcResponseResult<FixedBlobSidecarList<T::EthSpec>>> {
         let response = self.blobs_by_root_requests.on_response(id, rpc_event);
         let response = response.map(|res| {
-            res.and_then(
-                |(blobs, seen_timestamp)| match to_fixed_blob_sidecar_list(blobs) {
-                    Ok(blobs) => Ok((blobs, seen_timestamp)),
-                    Err(e) => Err(e.into()),
-                },
-            )
+            res.and_then(|(blobs, seen_timestamp)| {
+                if let Some(max_len) = blobs
+                    .first()
+                    .map(|blob| self.chain.spec.max_blobs_per_block(blob.epoch()) as usize)
+                {
+                    match to_fixed_blob_sidecar_list(blobs, max_len) {
+                        Ok(blobs) => Ok((blobs, seen_timestamp)),
+                        Err(e) => Err(e.into()),
+                    }
+                } else {
+                    Err(RpcResponseError::VerifyError(
+                        LookupVerifyError::InternalError(
+                            "Requested blobs for a block that has no blobs".to_string(),
+                        ),
+                    ))
+                }
+            })
         });
         if let Some(Err(RpcResponseError::VerifyError(e))) = &response {
             self.report_peer(peer_id, PeerAction::LowToleranceError, e.into());
@@ -1150,8 +1173,9 @@ impl<T: BeaconChainTypes> SyncNetworkContext<T> {
 
 fn to_fixed_blob_sidecar_list<E: EthSpec>(
     blobs: Vec<Arc<BlobSidecar<E>>>,
+    max_len: usize,
 ) -> Result<FixedBlobSidecarList<E>, LookupVerifyError> {
-    let mut fixed_list = FixedBlobSidecarList::default();
+    let mut fixed_list = FixedBlobSidecarList::new(vec![None; max_len]);
     for blob in blobs.into_iter() {
         let index = blob.index as usize;
         *fixed_list