Execution requests with prefix (#6801)

* Exclude empty requests and add back prefix

* cleanup

* fix after rebase

consensus/types/src/execution_requests.rs

@@ -43,10 +43,29 @@ impl<E: EthSpec> ExecutionRequests<E> {
     /// Returns the encoding according to EIP-7685 to send
     /// to the execution layer over the engine api.
     pub fn get_execution_requests_list(&self) -> Vec<Bytes> {
-        let deposit_bytes = Bytes::from(self.deposits.as_ssz_bytes());
-        let withdrawal_bytes = Bytes::from(self.withdrawals.as_ssz_bytes());
-        let consolidation_bytes = Bytes::from(self.consolidations.as_ssz_bytes());
-        vec![deposit_bytes, withdrawal_bytes, consolidation_bytes]
+        let mut requests_list = Vec::new();
+        if !self.deposits.is_empty() {
+            requests_list.push(Bytes::from_iter(
+                [RequestType::Deposit.to_u8()]
+                    .into_iter()
+                    .chain(self.deposits.as_ssz_bytes()),
+            ));
+        }
+        if !self.withdrawals.is_empty() {
+            requests_list.push(Bytes::from_iter(
+                [RequestType::Withdrawal.to_u8()]
+                    .into_iter()
+                    .chain(self.withdrawals.as_ssz_bytes()),
+            ));
+        }
+        if !self.consolidations.is_empty() {
+            requests_list.push(Bytes::from_iter(
+                [RequestType::Consolidation.to_u8()]
+                    .into_iter()
+                    .chain(self.consolidations.as_ssz_bytes()),
+            ));
+        }
+        requests_list
     }
 
     /// Generate the execution layer `requests_hash` based on EIP-7685.
@@ -55,9 +74,8 @@ impl<E: EthSpec> ExecutionRequests<E> {
     pub fn requests_hash(&self) -> Hash256 {
         let mut hasher = DynamicContext::new();
 
-        for (i, request) in self.get_execution_requests_list().iter().enumerate() {
+        for request in self.get_execution_requests_list().iter() {
             let mut request_hasher = DynamicContext::new();
-            request_hasher.update(&[i as u8]);
             request_hasher.update(request);
             let request_hash = request_hasher.finalize();
 
@@ -68,16 +86,16 @@ impl<E: EthSpec> ExecutionRequests<E> {
     }
 }
 
-/// This is used to index into the `execution_requests` array.
+/// The prefix types for `ExecutionRequest` objects.
 #[derive(Debug, Copy, Clone)]
-pub enum RequestPrefix {
+pub enum RequestType {
     Deposit,
     Withdrawal,
     Consolidation,
 }
 
-impl RequestPrefix {
-    pub fn from_prefix(prefix: u8) -> Option<Self> {
+impl RequestType {
+    pub fn from_u8(prefix: u8) -> Option<Self> {
         match prefix {
             0 => Some(Self::Deposit),
             1 => Some(Self::Withdrawal),
@@ -85,6 +103,13 @@ impl RequestPrefix {
             _ => None,
         }
     }
+    pub fn to_u8(&self) -> u8 {
+        match self {
+            Self::Deposit => 0,
+            Self::Withdrawal => 1,
+            Self::Consolidation => 2,
+        }
+    }
 }
 
 #[cfg(test)]

consensus/types/src/lib.rs

@@ -172,7 +172,7 @@ pub use crate::execution_payload_header::{
     ExecutionPayloadHeaderDeneb, ExecutionPayloadHeaderElectra, ExecutionPayloadHeaderFulu,
     ExecutionPayloadHeaderRef, ExecutionPayloadHeaderRefMut,
 };
-pub use crate::execution_requests::{ExecutionRequests, RequestPrefix};
+pub use crate::execution_requests::{ExecutionRequests, RequestType};
 pub use crate::fork::Fork;
 pub use crate::fork_context::ForkContext;
 pub use crate::fork_data::ForkData;