From c26ae503427043780e5d827f106f57023a820a69 Mon Sep 17 00:00:00 2001
From: Agnish Ghosh <iamagnix@gmail.com>
Date: Tue, 10 Dec 2024 15:07:00 +0530
Subject: [PATCH] rewrite: response checking from RequestManager for blobs

---
 beacon_chain/spec/helpers.nim         | 19 +++++++++++++++++
 beacon_chain/sync/request_manager.nim | 30 ++++++++++++++++++---------
 2 files changed, 39 insertions(+), 10 deletions(-)

diff --git a/beacon_chain/spec/helpers.nim b/beacon_chain/spec/helpers.nim
index e1df9ee2b3..92c3c605d2 100644
--- a/beacon_chain/spec/helpers.nim
+++ b/beacon_chain/spec/helpers.nim
@@ -10,6 +10,7 @@
 # Uncategorized helper functions from the spec
 
 import
+  std/sequtils,
   # Status libraries
   stew/[byteutils, endians2, objects],
   nimcrypto/sha2,
@@ -251,6 +252,24 @@ func create_blob_sidecars*(
     res.add(sidecar)
   res
 
+func search_sidecar_identifier*(
+    data: seq[BlobIdentifier] | seq[DataColumnIdentifier], 
+    target: ref BlobSidecar | ref DataColumnSidecar): int =
+  var
+    low_pt = 0
+    high_pt = data.high
+
+  while low_pt <= high_pt:
+    let mid = (low_pt + high_pt) div 2
+    if data[mid].index == target.index:
+      return mid  # Target found at index `mid`
+    elif data[mid].index < target.index:
+      low_pt = mid + 1
+    else:
+      high_pt = mid - 1
+
+  -1  # Target not found
+
 # https://github.com/ethereum/consensus-specs/blob/v1.5.0-alpha.5/specs/altair/light-client/sync-protocol.md#is_sync_committee_update
 template is_sync_committee_update*(update: SomeForkyLightClientUpdate): bool =
   when update is SomeForkyLightClientUpdateWithSyncCommittee:
diff --git a/beacon_chain/sync/request_manager.nim b/beacon_chain/sync/request_manager.nim
index 964e9fd799..a0fef50c22 100644
--- a/beacon_chain/sync/request_manager.nim
+++ b/beacon_chain/sync/request_manager.nim
@@ -104,19 +104,29 @@ proc checkResponse(roots: openArray[Eth2Digest],
 
 proc checkResponse(idList: seq[BlobIdentifier],
                    blobs: openArray[ref BlobSidecar]): bool =
-  if len(blobs) > len(idList):
+  if blobs.len > idList.len:
     return false
-  for blob in blobs:
-    let block_root = hash_tree_root(blob.signed_block_header.message)
-    var found = false
-    for id in idList:
-      if id.block_root == block_root and id.index == blob.index:
-        found = true
-        break
-    if not found:
+  
+  var i = 0
+  while i < blobs.len:
+    let
+      block_root = hash_tree_root(blobs[i].signed_block_header.message)
+      id = idList[i]
+    
+    # Check if the blob response is a subset
+    if search_sidecar_identifier(idList, blobs[i]) == -1:
+      i = if i != blobs.len - 1: i + 2 else: i + 1
+      continue
+
+    # Verify block_root and index match
+    if id.block_root != block_root or id.index != blobs[i].index:
       return false
-    blob[].verify_blob_sidecar_inclusion_proof().isOkOr:
+
+    # Verify inclusion proof
+    blobs[i][].verify_blob_sidecar_inclusion_proof().isOkOr:
       return false
+
+    inc i
   true
 
 proc requestBlocksByRoot(rman: RequestManager, items: seq[Eth2Digest]) {.async: (raises: [CancelledError]).} =