Make API implementation of eth_feeHistory compliant with the spec

core/lib/eth_client/src/clients/http/query.rs

@@ -112,6 +112,18 @@ where
                 .with_arg("block", &chunk_end)
                 .await?;
 
+            // Check that the lengths are the same.
+            // Per specification, the values should always be provided, and must be 0 for blocks
+            // prior to EIP-4844.
+            // https://ethereum.github.io/execution-apis/api-documentation/
+            if fee_history.base_fee_per_gas.len() != fee_history.base_fee_per_blob_gas.len() {
+                tracing::warn!(
+                    "base_fee_per_gas and base_fee_per_blob_gas have different lengths: {} and {}",
+                    fee_history.base_fee_per_gas.len(),
+                    fee_history.base_fee_per_blob_gas.len()
+                );
+            }
+
             for (base, blob) in fee_history
                 .base_fee_per_gas
                 .into_iter()

core/node/api_server/src/web3/namespaces/eth.rs

@@ -688,15 +688,19 @@ impl EthNamespace {
             base_fee_per_gas.len()
         ]);
 
+        // We do not support EIP-4844, but per API specification we should return 0 for pre EIP-4844 blocks.
+        let base_fee_per_blob_gas = vec![U256::zero(); base_fee_per_gas.len()];
+        let blob_gas_used_ratio = vec![0.0; base_fee_per_gas.len()];
+
         // `base_fee_per_gas` for next L2 block cannot be calculated, appending last fee as a placeholder.
         base_fee_per_gas.push(*base_fee_per_gas.last().unwrap());
         Ok(FeeHistory {
             oldest_block: web3::BlockNumber::Number(oldest_block.into()),
             base_fee_per_gas,
             gas_used_ratio,
             reward,
-            base_fee_per_blob_gas: vec![],
-            blob_gas_used_ratio: vec![],
+            base_fee_per_blob_gas,
+            blob_gas_used_ratio,
         })
     }