bolster BlobSidecar syncing on incomplete responses (#5766)

Avoid marking blocks invalid when corresponding `blobSidecarsByRange`
returns an incomplete / incorrect response while syncing. The block
itself may still be valid in that scenario.

Author: etan-status

beacon_chain/gossip_processing/gossip_validation.nim

@@ -179,17 +179,11 @@ func check_attestation_subnet(
 
   ok()
 
-# https://github.com/ethereum/consensus-specs/blob/v1.4.0-beta.4/specs/deneb/p2p-interface.md#verify_blob_sidecar_inclusion_proof
-func verify_blob_sidecar_inclusion_proof(
+func check_blob_sidecar_inclusion_proof(
     blob_sidecar: deneb.BlobSidecar): Result[void, ValidationError] =
-  let gindex = kzg_commitment_inclusion_proof_gindex(blob_sidecar.index)
-  if not is_valid_merkle_branch(
-      hash_tree_root(blob_sidecar.kzg_commitment),
-      blob_sidecar.kzg_commitment_inclusion_proof,
-      KZG_COMMITMENT_INCLUSION_PROOF_DEPTH,
-      get_subtree_index(gindex),
-      blob_sidecar.signed_block_header.message.body_root):
-    return errReject("BlobSidecar: inclusion proof not valid")
+  let res = blob_sidecar.verify_blob_sidecar_inclusion_proof()
+  if res.isErr:
+    return errReject(res.error)
 
   ok()
 
@@ -361,7 +355,7 @@ proc validateBlobSidecar*(
   # [REJECT] The sidecar's inclusion proof is valid as verified by
   # `verify_blob_sidecar_inclusion_proof(blob_sidecar)`.
   block:
-    let v = verify_blob_sidecar_inclusion_proof(blob_sidecar)
+    let v = check_blob_sidecar_inclusion_proof(blob_sidecar)
     if v.isErr:
       return dag.checkedReject(v.error)
 

beacon_chain/spec/helpers.nim

@@ -211,6 +211,19 @@ func has_flag*(flags: ParticipationFlags, flag_index: TimelyFlag): bool =
   let flag = ParticipationFlags(1'u8 shl ord(flag_index))
   (flags and flag) == flag
 
+# https://github.com/ethereum/consensus-specs/blob/v1.4.0-beta.4/specs/deneb/p2p-interface.md#check_blob_sidecar_inclusion_proof
+func verify_blob_sidecar_inclusion_proof*(
+    blob_sidecar: BlobSidecar): Result[void, string] =
+  let gindex = kzg_commitment_inclusion_proof_gindex(blob_sidecar.index)
+  if not is_valid_merkle_branch(
+      hash_tree_root(blob_sidecar.kzg_commitment),
+      blob_sidecar.kzg_commitment_inclusion_proof,
+      KZG_COMMITMENT_INCLUSION_PROOF_DEPTH,
+      get_subtree_index(gindex),
+      blob_sidecar.signed_block_header.message.body_root):
+    return err("BlobSidecar: inclusion proof not valid")
+  ok()
+
 func create_blob_sidecars*(
     forkyBlck: deneb.SignedBeaconBlock,
     kzg_proofs: KzgProofs,

beacon_chain/sync/sync_manager.nim

@@ -193,8 +193,9 @@ proc shouldGetBlobs[A, B](man: SyncManager[A, B], e: Epoch): bool =
   (wallEpoch < man.MIN_EPOCHS_FOR_BLOB_SIDECARS_REQUESTS or
    e >=  wallEpoch - man.MIN_EPOCHS_FOR_BLOB_SIDECARS_REQUESTS)
 
-proc getBlobSidecars*[A, B](man: SyncManager[A, B], peer: A,
-                      req: SyncRequest): Future[BlobSidecarsRes] {.async.} =
+proc getBlobSidecars[A, B](man: SyncManager[A, B], peer: A,
+                           req: SyncRequest
+                          ): Future[BlobSidecarsRes] {.async.} =
   mixin getScore, `==`
 
   logScope:
@@ -241,30 +242,46 @@ func groupBlobs*[T](req: SyncRequest[T],
                     blocks: seq[ref ForkedSignedBeaconBlock],
                     blobs: seq[ref BlobSidecar]):
                       Result[seq[BlobSidecars], string] =
-  var grouped = newSeq[BlobSidecars](len(blocks))
-  var blobCursor = 0
-  var i = 0
-  for blck in blocks:
-    let slot = blck[].slot
-    if blobCursor == len(blobs):
-      # reached end of blobs, have more blobless blocks
-      break
-    for blob in blobs[blobCursor..len(blobs)-1]:
-      if blob.signed_block_header.message.slot < slot:
-        return Result[seq[BlobSidecars], string].err "invalid blob sequence"
-      if blob.signed_block_header.message.slot == slot:
-        grouped[i].add(blob)
-        blobCursor = blobCursor + 1
-    i = i + 1
-
-  if blobCursor != len(blobs):
+  var
+    grouped = newSeq[BlobSidecars](len(blocks))
+    blob_cursor = 0
+  for block_idx, blck in blocks:
+    withBlck(blck[]):
+      when consensusFork >= ConsensusFork.Deneb:
+        template kzgs: untyped = forkyBlck.message.body.blob_kzg_commitments
+        if kzgs.len == 0:
+          continue
+        # Clients MUST include all blob sidecars of each block from which they include blob sidecars.
+        # The following blob sidecars, where they exist, MUST be sent in consecutive (slot, index) order.
+        # https://github.com/ethereum/consensus-specs/blob/v1.4.0-beta.5/specs/deneb/p2p-interface.md#blobsidecarsbyrange-v1
+        let header = forkyBlck.toSignedBeaconBlockHeader()
+        for blob_idx, kzg_commitment in kzgs:
+          if blob_cursor >= blobs.len:
+            return err("BlobSidecar: response too short")
+          let blob_sidecar = blobs[blob_cursor]
+          if blob_sidecar.index != BlobIndex blob_idx:
+            return err("BlobSidecar: unexpected index")
+          if blob_sidecar.kzg_commitment != kzg_commitment:
+            return err("BlobSidecar: unexpected kzg_commitment")
+          if blob_sidecar.signed_block_header != header:
+            return err("BlobSidecar: unexpected signed_block_header")
+          grouped[block_idx].add(blob_sidecar)
+          inc blob_cursor
+
+  if blob_cursor != len(blobs):
     # we reached end of blocks without consuming all blobs so either
     # the peer we got too few blocks in the paired request, or the
     # peer is sending us spurious blobs.
     Result[seq[BlobSidecars], string].err "invalid block or blob sequence"
   else:
     Result[seq[BlobSidecars], string].ok grouped
 
+func checkBlobs(blobs: seq[BlobSidecars]): Result[void, string] =
+  for blob_sidecars in blobs:
+    for blob_sidecar in blob_sidecars:
+      ? blob_sidecar[].verify_blob_sidecar_inclusion_proof()
+  ok()
+
 proc syncStep[A, B](man: SyncManager[A, B], index: int, peer: A) {.async.} =
   logScope:
     peer_score = peer.getScore()
@@ -454,30 +471,24 @@ proc syncStep[A, B](man: SyncManager[A, B], index: int, peer: A) {.async.} =
             return
         let groupedBlobs = groupBlobs(req, blockData, blobData)
         if groupedBlobs.isErr():
+          peer.updateScore(PeerScoreNoValues)
+          man.queue.push(req)
+          info "Received blobs sequence is inconsistent",
+            blobs_map = getShortMap(req, blobData), request = req, msg=groupedBlobs.error()
+          return
+        if (let checkRes = groupedBlobs.get.checkBlobs(); checkRes.isErr):
           peer.updateScore(PeerScoreBadResponse)
           man.queue.push(req)
           warn "Received blobs sequence is invalid",
-            blobs_map = getShortMap(req, blobData), request = req, msg=groupedBlobs.error()
+            blobs_count = len(blobData),
+            blobs_map = getShortMap(req, blobData),
+            request = req,
+            msg = checkRes.error
           return
         Opt.some(groupedBlobs.get())
       else:
         Opt.none(seq[BlobSidecars])
 
-    if blobData.isSome:
-      let blobs = blobData.get()
-      if len(blobs) != len(blockData):
-        peer.updateScore(PeerScoreNoValues)
-        man.queue.push(req)
-        info "block and blobs have different lengths", blobs=len(blobs), blocks=len(blockData)
-        return
-      for i, blk in blockData:
-        if len(blobs[i]) > 0 and blk[].slot !=
-            blobs[i][0].signed_block_header.message.slot:
-          peer.updateScore(PeerScoreNoValues)
-          man.queue.push(req)
-          debug "block and blobs data have inconsistent slots"
-          return
-
     if len(blockData) == 0 and man.direction == SyncQueueKind.Backward and
         req.contains(man.getSafeSlot()):
       # The sync protocol does not distinguish between:

tests/test_sync_manager.nim

@@ -12,7 +12,6 @@ import unittest2
 import chronos
 import ../beacon_chain/gossip_processing/block_processor,
        ../beacon_chain/sync/sync_manager,
-       ../beacon_chain/spec/datatypes/phase0,
        ../beacon_chain/spec/forks
 
 type
@@ -66,16 +65,36 @@ suite "SyncManager test suite":
     var res = newSeq[ref ForkedSignedBeaconBlock](count)
     var curslot = start
     for item in res.mitems():
-      item = new ForkedSignedBeaconBlock
-      item[].phase0Data.message.slot = curslot
+      item = newClone ForkedSignedBeaconBlock(kind: ConsensusFork.Deneb)
+      item[].denebData.message.slot = curslot
       curslot = curslot + 1'u64
     res
 
-  func createBlobs(slots: seq[Slot]): seq[ref BlobSidecar] =
+  func createBlobs(
+      blocks: var seq[ref ForkedSignedBeaconBlock], slots: seq[Slot]
+  ): seq[ref BlobSidecar] =
     var res = newSeq[ref BlobSidecar](len(slots))
-    for (i, item) in res.mpairs():
-      item = new BlobSidecar
-      item[].signed_block_header.message.slot = slots[i]
+    for blck in blocks:
+      withBlck(blck[]):
+        when consensusFork >= ConsensusFork.Deneb:
+          template kzgs: untyped = forkyBlck.message.body.blob_kzg_commitments
+          for i, slot in slots:
+            if slot == forkyBlck.message.slot:
+              doAssert kzgs.add default(KzgCommitment)
+          if kzgs.len > 0:
+            forkyBlck.root = hash_tree_root(forkyBlck.message)
+            var
+              kzg_proofs: KzgProofs
+              blobs: Blobs
+            for _ in kzgs:
+              doAssert kzg_proofs.add default(KzgProof)
+              doAssert blobs.add default(Blob)
+            let sidecars = forkyBlck.create_blob_sidecars(kzg_proofs, blobs)
+            var sidecarIdx = 0
+            for i, slot in slots:
+              if slot == forkyBlck.message.slot:
+                res[i] = newClone sidecars[sidecarIdx]
+                inc sidecarIdx
     res
 
   proc getSlice(chain: openArray[ref ForkedSignedBeaconBlock], startSlot: Slot,
@@ -1064,8 +1083,8 @@ suite "SyncManager test suite":
       checkResponse(r21, @[slots[3]]) == false
 
   test "[SyncManager] groupBlobs() test":
-    var blobs = createBlobs(@[Slot(11), Slot(11), Slot(12), Slot(14)])
     var blocks = createChain(Slot(10), Slot(15))
+    var blobs = createBlobs(blocks, @[Slot(11), Slot(11), Slot(12), Slot(14)])
 
     let req = SyncRequest[SomeTPeer](slot: Slot(10))
     let groupedRes = groupBlobs(req, blocks, blobs)
@@ -1095,8 +1114,8 @@ suite "SyncManager test suite":
       len(grouped[5]) == 0
 
     # Add block with a gap from previous block.
-    let block17 = new (ref ForkedSignedBeaconBlock)
-    block17[].phase0Data.message.slot = Slot(17)
+    let block17 = newClone ForkedSignedBeaconBlock(kind: ConsensusFork.Deneb)
+    block17[].denebData.message.slot = Slot(17)
     blocks.add(block17)
     let groupedRes2 = groupBlobs(req, blocks, blobs)