Adjust get_block_header function to allow getting headers of past blocks

consensus/src/consensus.rs

@@ -92,7 +92,7 @@ impl<R: ConsensusRpc> ConsensusClient<R> {
         } else if slot == finalized_slot {
             self.store.finalized_header.clone().hash_tree_root()?
         } else {
-            return Err(ConsensusError::PayloadNotFound(slot).into());
+            self.rpc.get_header(slot).await?.message.hash_tree_root()?
         };
 
         if verified_block_hash != block_hash {

consensus/src/rpc/mock_rpc.rs

@@ -1,7 +1,7 @@
 use std::{fs::read_to_string, path::PathBuf};
 
 use super::ConsensusRpc;
-use crate::types::{BeaconBlock, Bootstrap, FinalityUpdate, OptimisticUpdate, Update};
+use crate::types::{BeaconBlock, BeaconHeader, Bootstrap, FinalityUpdate, OptimisticUpdate, Update};
 use async_trait::async_trait;
 use eyre::Result;
 pub struct MockRpc {
@@ -42,6 +42,11 @@ impl ConsensusRpc for MockRpc {
         Ok(serde_json::from_str(&block)?)
     }
 
+    async fn get_header(&self, _slot: u64) -> Result<BeaconHeader> {
+        let header = read_to_string(self.testdata.join("headers.json"))?;
+        Ok(serde_json::from_str(&header)?)
+    }
+
     async fn chain_id(&self) -> Result<u64> {
         eyre::bail!("not implemented")
     }

consensus/src/rpc/mod.rs

@@ -4,7 +4,7 @@ pub mod nimbus_rpc;
 use async_trait::async_trait;
 use eyre::Result;
 
-use crate::types::{BeaconBlock, Bootstrap, FinalityUpdate, OptimisticUpdate, Update};
+use crate::types::{BeaconBlock, BeaconHeader, Bootstrap, FinalityUpdate, Header, OptimisticUpdate, Update};
 
 // implements https://github.com/ethereum/beacon-APIs/tree/master/apis/beacon/light_client
 #[cfg_attr(not(target_arch = "wasm32"), async_trait)]
@@ -16,5 +16,6 @@ pub trait ConsensusRpc {
     async fn get_finality_update(&self) -> Result<FinalityUpdate>;
     async fn get_optimistic_update(&self) -> Result<OptimisticUpdate>;
     async fn get_block(&self, slot: u64) -> Result<BeaconBlock>;
+    async fn get_header(&self, slot: u64) -> Result<BeaconHeader>;
     async fn chain_id(&self) -> Result<u64>;
 }

consensus/src/rpc/nimbus_rpc.rs

@@ -6,6 +6,7 @@ use super::ConsensusRpc;
 use crate::constants::MAX_REQUEST_LIGHT_CLIENT_UPDATES;
 use crate::types::*;
 use common::errors::RpcError;
+use common::types::Bytes32;
 
 #[derive(Debug)]
 pub struct NimbusRpc {
@@ -97,6 +98,19 @@ impl ConsensusRpc for NimbusRpc {
         Ok(res.data.message)
     }
 
+    async fn get_header(&self, slot: u64) -> Result<BeaconHeader> {
+        let req = format!("{}/eth/v1/beacon/headers/{}", self.rpc, slot);
+        let res = reqwest::get(req)
+            .await
+            .map_err(|e| RpcError::new("headers", e))?
+            .json::<BeaconHeaderResponse>()
+            .await
+            .map_err(|e| RpcError::new("headers", e))?;
+
+        Ok(res.data.header)
+    }
+
+
     async fn chain_id(&self) -> Result<u64> {
         let req = format!("{}/eth/v1/config/spec", self.rpc);
         let res = reqwest::get(req)
@@ -110,6 +124,12 @@ impl ConsensusRpc for NimbusRpc {
     }
 }
 
+#[derive(serde::Deserialize, Debug)]
+struct BeaconHeaderResponse {
+    data: BeaconHeaderData,
+    execution_optimistic: bool,
+}
+
 #[derive(serde::Deserialize, Debug)]
 struct BeaconBlockResponse {
     data: BeaconBlockData,
@@ -120,6 +140,14 @@ struct BeaconBlockData {
     message: BeaconBlock,
 }
 
+#[derive(serde::Deserialize, Debug)]
+struct BeaconHeaderData {
+    #[serde(deserialize_with = "bytes32_deserialize")]
+    root: Bytes32,
+    header: BeaconHeader,
+    canonical: bool,
+}
+
 type UpdateResponse = Vec<UpdateData>;
 
 #[derive(serde::Deserialize, Debug)]

consensus/src/types.rs

@@ -24,6 +24,13 @@ pub struct BeaconBlock {
     pub body: BeaconBlockBody,
 }
 
+#[derive(serde::Deserialize, Debug, Default, SimpleSerialize, Clone)]
+pub struct BeaconHeader {
+    pub message: Header,
+    #[serde(deserialize_with = "signature_deserialize")]
+    signature: SignatureBytes,
+}
+
 #[derive(serde::Deserialize, Debug, Default, SimpleSerialize, Clone)]
 pub struct BeaconBlockBody {
     #[serde(deserialize_with = "signature_deserialize")]
@@ -395,7 +402,7 @@ where
     Ok(U256::from_bytes_le(x_bytes))
 }
 
-fn bytes32_deserialize<'de, D>(deserializer: D) -> Result<Bytes32, D::Error>
+pub fn bytes32_deserialize<'de, D>(deserializer: D) -> Result<Bytes32, D::Error>
 where
     D: serde::Deserializer<'de>,
 {