EIP-7594: PeerDAS explicit csc integer size

specs/_features/eip7594/das-core.md

@@ -105,7 +105,7 @@ class MatrixEntry(Container):
 ### `get_custody_columns`
 
 ```python
-def get_custody_columns(node_id: NodeID, custody_subnet_count: uint64) -> Sequence[ColumnIndex]:
+def get_custody_columns(node_id: NodeID, custody_subnet_count: uint8) -> Sequence[ColumnIndex]:
     assert custody_subnet_count <= DATA_COLUMN_SIDECAR_SUBNET_COUNT
 
     subnet_ids: List[uint64] = []
@@ -222,7 +222,7 @@ def get_data_column_sidecars(signed_block: SignedBeaconBlock,
 
 Each node downloads and custodies a minimum of `CUSTODY_REQUIREMENT` subnets per slot. The particular subnets that the node is required to custody are selected pseudo-randomly (more on this below).
 
-A node *may* choose to custody and serve more than the minimum honesty requirement. Such a node explicitly advertises a number greater than `CUSTODY_REQUIREMENT` via the peer discovery mechanism -- for example, in their ENR (e.g. `custody_subnet_count: 4` if the node custodies `4` subnets each slot) -- up to a `DATA_COLUMN_SIDECAR_SUBNET_COUNT` (i.e. a super-full node).
+A node *may* choose to custody and serve more than the minimum honesty requirement. Such a node explicitly advertises a number greater than `CUSTODY_REQUIREMENT` via the peer discovery mechanism -- for example, in their ENR (e.g. `custody_subnet_count` as known as `csc: 4` if the node custodies `4` subnets each slot) -- up to a `DATA_COLUMN_SIDECAR_SUBNET_COUNT` (i.e. a super-full node).
 
 A node stores the custodied columns for the duration of the pruning period and responds to peer requests for samples on those columns.
 

specs/_features/eip7594/p2p-interface.md

@@ -119,14 +119,14 @@ The `MetaData` stored locally by clients is updated with an additional field to
   seq_number: uint64
   attnets: Bitvector[ATTESTATION_SUBNET_COUNT]
   syncnets: Bitvector[SYNC_COMMITTEE_SUBNET_COUNT]
-  custody_subnet_count: uint64
+  csc: uint8
 )
 ```
 
 Where
 
 - `seq_number`, `attnets`, and `syncnets` have the same meaning defined in the Altair document.
-- `custody_subnet_count` represents the node's custody subnet count. Clients MAY reject ENRs with a value less than `CUSTODY_REQUIREMENT`.
+- `csc` represents the node's custody subnet count. Clients MAY reject ENRs with a value less than `CUSTODY_REQUIREMENT`.
 
 ### The gossip domain: gossipsub
 
@@ -322,6 +322,6 @@ Requests the MetaData of a peer, using the new `MetaData` definition given above
 
 A new field is added to the ENR under the key `csc` to facilitate custody data column discovery.
 
-| Key    | Value                                    |
-|--------|------------------------------------------|
-| `csc`  | Custody subnet count, big endian integer |
+| Key    | Value                               |
+|--------|-------------------------------------|
+| `csc`  | Custody subnet count, uint8 integer |

tests/core/pyspec/eth2spec/test/eip7594/unittests/test_custody.py

@@ -4,6 +4,7 @@
     single_phase,
     with_eip7594_and_later,
 )
+from eth2spec.utils.ssz.ssz_typing import uint8
 
 
 def run_get_custody_columns(spec, peer_count, custody_subnet_count):
@@ -51,3 +52,10 @@ def test_get_custody_columns_custody_size_more_than_number_of_columns(spec):
     node_id = 1
     custody_subnet_count = spec.config.DATA_COLUMN_SIDECAR_SUBNET_COUNT + 1
     expect_assertion_error(lambda: spec.get_custody_columns(node_id, custody_subnet_count))
+
+
+@with_eip7594_and_later
+@spec_test
+@single_phase
+def test_custody_subnet_count_int_bitlength(spec, custody_subnet_count):
+    assert uint8(custody_subnet_count) == custody_subnet_count