add a bunch of blob coupling boiler plate, add a blobs by root request

consensus/types/src/signed_block_and_blobs.rs

@@ -1,7 +1,9 @@
+use std::sync::Arc;
 use serde_derive::{Deserialize, Serialize};
+use ssz::{Decode, DecodeError};
 use ssz_derive::{Decode, Encode};
 use tree_hash_derive::TreeHash;
-use crate::{BlobsSidecar, EthSpec, SignedBeaconBlock};
+use crate::{BlobsSidecar, EthSpec, SignedBeaconBlock, SignedBeaconBlockEip4844};
 
 #[derive(Debug, Clone, Serialize, Deserialize, Encode, TreeHash, PartialEq)]
 #[serde(bound = "T: EthSpec")]
@@ -10,9 +12,26 @@ pub struct SignedBeaconBlockAndBlobsSidecar<T: EthSpec> {
     pub blobs_sidecar: BlobsSidecar<T>,
 }
 
-impl<T: EthSpec> SignedBeaconBlockAndBlobsSidecar<T> {
-    /// SSZ decode with fork variant determined by slot.
-    pub fn from_ssz_bytes(bytes: &[u8], spec: &ChainSpec) -> Result<Self, ssz::DecodeError> {
-        SignedBeaconBlock::from_ssz_bytes(bytes, spec)
+impl <T: EthSpec>Decode for SignedBeaconBlockAndBlobsSidecar<T> {
+    fn is_ssz_fixed_len() -> bool {
+        todo!()
+    }
+
+    fn from_ssz_bytes(bytes: &[u8]) -> Result<Self, DecodeError> {
+        todo!()
+    }
+}
+
+pub enum BlockMaybeBlobs<T: EthSpec> {
+    Block(Arc<SignedBeaconBlock<T>>),
+    BlockAndBlobs(Arc<SignedBeaconBlockAndBlobsSidecar<T>>),
+}
+
+impl <T: EthSpec> BlockMaybeBlobs<T> {
+    pub fn blobs(&self) -> Option<&BlobsSidecar<T>>{
+        match self {
+            Self::Block(_) => None,
+            Self::BlockAndBlobs(block_and_blobs) => Some(&block_and_blobs.blobs_sidecar)
+        }
     }
 }