From 200b61b08b5c87d24abb3f5bac3813be2b6a5979 Mon Sep 17 00:00:00 2001
From: Matthias Seitz <matthias.seitz@outlook.de>
Date: Thu, 28 Mar 2024 00:23:58 +0100
Subject: [PATCH] feat: set max fee per blob gas with pending block fees

---
 crates/provider/src/layers/gas.rs | 28 ++++++++++++++++++++++++----
 crates/rpc-types/src/eth/block.rs | 27 +++++++++++++++++++++++++++
 2 files changed, 51 insertions(+), 4 deletions(-)

diff --git a/crates/provider/src/layers/gas.rs b/crates/provider/src/layers/gas.rs
index 6651ea410b9..4daa40969e3 100644
--- a/crates/provider/src/layers/gas.rs
+++ b/crates/provider/src/layers/gas.rs
@@ -4,6 +4,7 @@ use crate::{
 use alloy_json_rpc::RpcError;
 use alloy_network::{Network, TransactionBuilder};
 use alloy_primitives::U256;
+use alloy_rpc_types::BlockNumberOrTag;
 use alloy_transport::{Transport, TransportError, TransportResult};
 use async_trait::async_trait;
 use futures::FutureExt;
@@ -153,11 +154,27 @@ where
     /// * `eth_feeHistory`: Returns the same info as for the EIP-1559 fees.
     /// * retrieving it from the "pending" block directly.
     ///
-    /// At the time of this writing support for EIP-4844 fees is lacking, hence we're defaulting to requesting the fee from the "pending" block.
-    async fn handle_eip4844_tx(&self, tx: &mut N::TransactionRequest) -> Result<(), TransportError> {
-        // TODO fetch block and set blob fee
+    /// At the time of this writing support for EIP-4844 fees is lacking, hence we're defaulting to
+    /// requesting the fee from the "pending" block.
+    async fn handle_eip4844_tx(
+        &self,
+        tx: &mut N::TransactionRequest,
+    ) -> Result<(), TransportError> {
+        // TODO this can be optimized together with 1559 dynamic fees once blob fee support on
+        // eth_feeHistory is more widely supported
+        if tx.get_blob_sidecar().is_some() && tx.max_fee_per_blob_gas().is_none() {
+            let next_blob_fee = self
+                .inner
+                .get_block_by_number(BlockNumberOrTag::Latest, false)
+                .await?
+                .ok_or(RpcError::NullResp)?
+                .header
+                .next_block_blob_fee()
+                .ok_or(RpcError::UnsupportedFeature("eip4844"))?;
+            tx.set_max_fee_per_blob_gas(U256::from(next_blob_fee));
+        }
 
-        todo!()
+        Ok(())
     }
 }
 
@@ -182,6 +199,9 @@ where
             // Populate the following gas_limit, max_fee_per_gas and max_priority_fee_per_gas fields
             // if unset.
             self.handle_eip1559_tx(&mut tx).await?;
+            // TODO: this can be done more elegantly once we can set EIP-1559 and EIP-4844 fields
+            // with a single eth_feeHistory request
+            self.handle_eip4844_tx(&mut tx).await?;
         } else {
             // Assume its a legacy tx
             // Populate only the gas_limit field if unset.
diff --git a/crates/rpc-types/src/eth/block.rs b/crates/rpc-types/src/eth/block.rs
index faca627c323..be394ecccc2 100644
--- a/crates/rpc-types/src/eth/block.rs
+++ b/crates/rpc-types/src/eth/block.rs
@@ -3,6 +3,7 @@
 #![allow(unknown_lints, non_local_definitions)]
 
 use crate::{other::OtherFields, Transaction, Withdrawal};
+use alloy_eips::{calc_blob_gasprice, calc_excess_blob_gas};
 use alloy_primitives::{
     ruint::ParseError, Address, BlockHash, BlockNumber, Bloom, Bytes, B256, B64, U256, U64,
 };
@@ -117,6 +118,32 @@ pub struct Header {
     pub parent_beacon_block_root: Option<B256>,
 }
 
+impl Header {
+    /// Returns the blob fee for _this_ block according to the EIP-4844 spec.
+    ///
+    /// Returns `None` if `excess_blob_gas` is None
+    pub fn blob_fee(&self) -> Option<u128> {
+        self.excess_blob_gas.map(|gas| calc_blob_gasprice(gas.to()))
+    }
+
+    /// Returns the blob fee for the next block according to the EIP-4844 spec.
+    ///
+    /// Returns `None` if `excess_blob_gas` is None.
+    ///
+    /// See also [Self::next_block_excess_blob_gas]
+    pub fn next_block_blob_fee(&self) -> Option<u128> {
+        self.next_block_excess_blob_gas().map(calc_blob_gasprice)
+    }
+
+    /// Calculate excess blob gas for the next block according to the EIP-4844
+    /// spec.
+    ///
+    /// Returns a `None` if no excess blob gas is set, no EIP-4844 support
+    pub fn next_block_excess_blob_gas(&self) -> Option<u64> {
+        Some(calc_excess_blob_gas(self.excess_blob_gas?.to(), self.blob_gas_used?.to()))
+    }
+}
+
 /// Block Transactions depending on the boolean attribute of `eth_getBlockBy*`,
 /// or if used by `eth_getUncle*`
 #[derive(Debug, Clone, Eq, PartialEq, Serialize, Deserialize)]