miscelaneous fixes on syncing, rpc and responding to peer's sync related requests (#3827)

- there was a bug in responding range blob requests where we would incorrectly label the first slot of an epoch as a non-skipped slot if it were skipped. this bug did not exist in the code for responding to block range request because the logic error was mitigated by defensive coding elsewhere
- there was a bug where a block received during range sync without a corresponding blob (and vice versa) was incorrectly interpreted as a stream termination
- RPC size limit fixes.
- Our blob cache was dead locking so I removed use of it for now.
- Because of our change in finalized sync batch size from 2 to 1 and our transition to using exact epoch boundaries for batches (rather than one slot past the epoch boundary), we need to sync finalized sync to 2 epochs + 1 slot past our peer's finalized slot in order to finalize the chain locally.
- use fork context bytes in rpc methods on both the server and client side

beacon_node/lighthouse_network/src/rpc/codec/ssz_snappy.rs

@@ -298,8 +298,8 @@ impl<TSpec: EthSpec> Decoder for SSZSnappyOutboundCodec<TSpec> {
             .rpc_response_limits::<TSpec>(&self.fork_context);
         if ssz_limits.is_out_of_bounds(length, self.max_packet_size) {
             return Err(RPCError::InvalidData(format!(
-                "RPC response length is out of bounds, length {}",
-                length
+                "RPC response length is out of bounds, length {}, max {}, min {}",
+                length, ssz_limits.max, ssz_limits.min
             )));
         }
         // Calculate worst case compression length for given uncompressed length
@@ -439,6 +439,9 @@ fn context_bytes<T: EthSpec>(
                     SignedBeaconBlock::Base { .. } => Some(fork_context.genesis_context_bytes()),
                 };
             }
+            if let RPCResponse::BlobsByRange(_) | RPCResponse::BlobsByRoot(_) = rpc_variant {
+                return fork_context.to_context_bytes(ForkName::Eip4844);
+            }
         }
     }
     None

beacon_node/lighthouse_network/src/rpc/protocol.rs

@@ -107,6 +107,12 @@ lazy_static! {
     .as_ssz_bytes()
     .len();
 
+    pub static ref BLOBS_SIDECAR_MIN: usize = BlobsSidecar::<MainnetEthSpec>::empty().as_ssz_bytes().len();
+    pub static ref BLOBS_SIDECAR_MAX: usize = BlobsSidecar::<MainnetEthSpec>::max_size();
+
+    //FIXME(sean) these are underestimates
+    pub static ref SIGNED_BLOCK_AND_BLOBS_MIN: usize = *BLOBS_SIDECAR_MIN + *SIGNED_BEACON_BLOCK_BASE_MIN;
+    pub static ref SIGNED_BLOCK_AND_BLOBS_MAX: usize =*BLOBS_SIDECAR_MAX + *SIGNED_BEACON_BLOCK_EIP4844_MAX;
 }
 
 /// The maximum bytes that can be sent across the RPC pre-merge.
@@ -358,11 +364,10 @@ impl ProtocolId {
             Protocol::Goodbye => RpcLimits::new(0, 0), // Goodbye request has no response
             Protocol::BlocksByRange => rpc_block_limits_by_fork(fork_context.current_fork()),
             Protocol::BlocksByRoot => rpc_block_limits_by_fork(fork_context.current_fork()),
-
-            //FIXME(sean) add blob sizes
-            Protocol::BlobsByRange => rpc_block_limits_by_fork(fork_context.current_fork()),
-            Protocol::BlobsByRoot => rpc_block_limits_by_fork(fork_context.current_fork()),
-
+            Protocol::BlobsByRange => RpcLimits::new(*BLOBS_SIDECAR_MIN, *BLOBS_SIDECAR_MAX),
+            Protocol::BlobsByRoot => {
+                RpcLimits::new(*SIGNED_BLOCK_AND_BLOBS_MIN, *SIGNED_BLOCK_AND_BLOBS_MAX)
+            }
             Protocol::Ping => RpcLimits::new(
                 <Ping as Encode>::ssz_fixed_len(),
                 <Ping as Encode>::ssz_fixed_len(),
@@ -381,13 +386,16 @@ impl ProtocolId {
     /// Returns `true` if the given `ProtocolId` should expect `context_bytes` in the
     /// beginning of the stream, else returns `false`.
     pub fn has_context_bytes(&self) -> bool {
-        if self.version == Version::V2 {
-            match self.message_name {
+        match self.version {
+            Version::V2 => match self.message_name {
                 Protocol::BlocksByRange | Protocol::BlocksByRoot => return true,
                 _ => return false,
-            }
+            },
+            Version::V1 => match self.message_name {
+                Protocol::BlobsByRange | Protocol::BlobsByRoot => return true,
+                _ => return false,
+            },
         }
-        false
     }
 }