feat: add 4844 header fields and consensus checks (#3972)

crates/consensus/auto-seal/src/lib.rs

@@ -269,6 +269,8 @@ impl StorageInner {
             nonce: 0,
             base_fee_per_gas,
             extra_data: Default::default(),
+            blob_gas_used: None,
+            excess_blob_gas: None,
         };
 
         header.transactions_root = if transactions.is_empty() {

crates/consensus/common/src/validation.rs

@@ -1,8 +1,13 @@
 //! Collection of methods for block validation.
 use reth_interfaces::{consensus::ConsensusError, Result as RethResult};
 use reth_primitives::{
-    constants, BlockNumber, ChainSpec, Hardfork, Header, InvalidTransactionError, SealedBlock,
-    SealedHeader, Transaction, TransactionSignedEcRecovered, TxEip1559, TxEip2930, TxLegacy,
+    blobfee::calculate_excess_blob_gas,
+    constants::{
+        self,
+        eip4844::{DATA_GAS_PER_BLOB, MAX_DATA_GAS_PER_BLOCK},
+    },
+    BlockNumber, ChainSpec, Hardfork, Header, InvalidTransactionError, SealedBlock, SealedHeader,
+    Transaction, TransactionSignedEcRecovered, TxEip1559, TxEip2930, TxLegacy,
 };
 use reth_provider::{AccountReader, HeaderProvider, WithdrawalsProvider};
 use std::collections::{hash_map::Entry, HashMap};
@@ -38,6 +43,15 @@ pub fn validate_header_standalone(
         return Err(ConsensusError::WithdrawalsRootUnexpected)
     }
 
+    // Ensures that EIP-4844 fields are valid once cancun is active.
+    if chain_spec.fork(Hardfork::Cancun).active_at_timestamp(header.timestamp) {
+        validate_4844_header_standalone(header)?;
+    } else if header.blob_gas_used.is_some() {
+        return Err(ConsensusError::BlobGasUsedUnexpected)
+    } else if header.excess_blob_gas.is_some() {
+        return Err(ConsensusError::ExcessBlobGasUnexpected)
+    }
+
     Ok(())
 }
 
@@ -291,6 +305,11 @@ pub fn validate_header_regarding_parent(
         }
     }
 
+    // ensure that the blob gas fields for this block
+    if chain_spec.fork(Hardfork::Cancun).active_at_timestamp(child.timestamp) {
+        validate_4844_header_with_parent(parent, child)?;
+    }
+
     Ok(())
 }
 
@@ -376,6 +395,72 @@ pub fn full_validation<Provider: HeaderProvider + AccountReader + WithdrawalsPro
     Ok(())
 }
 
+/// Validates that the EIP-4844 header fields are correct with respect to the parent block. This
+/// ensures that the `blob_gas_used` and `excess_blob_gas` fields exist in the child header, and
+/// that the `excess_blob_gas` field matches the expected `excess_blob_gas` calculated from the
+/// parent header fields.
+pub fn validate_4844_header_with_parent(
+    parent: &SealedHeader,
+    child: &SealedHeader,
+) -> Result<(), ConsensusError> {
+    // From [EIP-4844](https://eips.ethereum.org/EIPS/eip-4844#header-extension):
+    //
+    // > For the first post-fork block, both parent.blob_gas_used and parent.excess_blob_gas
+    // > are evaluated as 0.
+    //
+    // This means in the first post-fork block, calculate_excess_blob_gas will return 0.
+    let parent_blob_gas_used = parent.blob_gas_used.unwrap_or(0);
+    let parent_excess_blob_gas = parent.excess_blob_gas.unwrap_or(0);
+
+    if child.blob_gas_used.is_none() {
+        return Err(ConsensusError::BlobGasUsedMissing)
+    }
+    let excess_blob_gas = child.excess_blob_gas.ok_or(ConsensusError::ExcessBlobGasMissing)?;
+
+    let expected_excess_blob_gas =
+        calculate_excess_blob_gas(parent_excess_blob_gas, parent_blob_gas_used);
+    if expected_excess_blob_gas != excess_blob_gas {
+        return Err(ConsensusError::ExcessBlobGasDiff {
+            expected: expected_excess_blob_gas,
+            got: excess_blob_gas,
+            parent_excess_blob_gas,
+            parent_blob_gas_used,
+        })
+    }
+
+    Ok(())
+}
+
+/// Validates that the EIP-4844 header fields exist and conform to the spec. This ensures that:
+///
+///  * `blob_gas_used` exists as a header field
+///  * `excess_blob_gas` exists as a header field
+///  * `blob_gas_used` is less than or equal to `MAX_DATA_GAS_PER_BLOCK`
+///  * `blob_gas_used` is a multiple of `DATA_GAS_PER_BLOB`
+pub fn validate_4844_header_standalone(header: &SealedHeader) -> Result<(), ConsensusError> {
+    let blob_gas_used = header.blob_gas_used.ok_or(ConsensusError::BlobGasUsedMissing)?;
+
+    if header.excess_blob_gas.is_none() {
+        return Err(ConsensusError::ExcessBlobGasMissing)
+    }
+
+    if blob_gas_used > MAX_DATA_GAS_PER_BLOCK {
+        return Err(ConsensusError::BlobGasUsedExceedsMaxBlobGasPerBlock {
+            blob_gas_used,
+            max_blob_gas_per_block: MAX_DATA_GAS_PER_BLOCK,
+        })
+    }
+
+    if blob_gas_used % DATA_GAS_PER_BLOB != 0 {
+        return Err(ConsensusError::BlobGasUsedNotMultipleOfBlobGasPerBlob {
+            blob_gas_used,
+            blob_gas_per_blob: DATA_GAS_PER_BLOB,
+        })
+    }
+
+    Ok(())
+}
+
 #[cfg(test)]
 mod tests {
     use super::*;
@@ -530,6 +615,8 @@ mod tests {
             nonce: 0x0000000000000000,
             base_fee_per_gas: 0x28f0001df.into(),
             withdrawals_root: None,
+            blob_gas_used: None,
+            excess_blob_gas: None,
         };
         // size: 0x9b5
 

crates/interfaces/src/consensus.rs

@@ -113,6 +113,27 @@ pub enum ConsensusError {
     WithdrawalIndexInvalid { got: u64, expected: u64 },
     #[error("Missing withdrawals")]
     BodyWithdrawalsMissing,
+    #[error("Missing blob gas used")]
+    BlobGasUsedMissing,
+    #[error("Unexpected blob gas used")]
+    BlobGasUsedUnexpected,
+    #[error("Missing excess blob gas")]
+    ExcessBlobGasMissing,
+    #[error("Unexpected excess blob gas")]
+    ExcessBlobGasUnexpected,
+    #[error("Blob gas used {blob_gas_used} exceeds maximum allowance {max_blob_gas_per_block}")]
+    BlobGasUsedExceedsMaxBlobGasPerBlock { blob_gas_used: u64, max_blob_gas_per_block: u64 },
+    #[error(
+        "Blob gas used {blob_gas_used} is not a multiple of blob gas per blob {blob_gas_per_blob}"
+    )]
+    BlobGasUsedNotMultipleOfBlobGasPerBlob { blob_gas_used: u64, blob_gas_per_blob: u64 },
+    #[error("Invalid excess blob gas. Expected: {expected}, got: {got}. Parent excess blob gas: {parent_excess_blob_gas}, parent blob gas used: {parent_blob_gas_used}.")]
+    ExcessBlobGasDiff {
+        expected: u64,
+        got: u64,
+        parent_excess_blob_gas: u64,
+        parent_blob_gas_used: u64,
+    },
     /// Error for a transaction that violates consensus.
     #[error(transparent)]
     InvalidTransaction(#[from] InvalidTransactionError),

crates/net/eth-wire/src/types/blocks.rs

@@ -258,6 +258,8 @@ mod test {
                     nonce: 0x0000000000000000u64,
                     base_fee_per_gas: None,
                     withdrawals_root: None,
+                    blob_gas_used: None,
+                    excess_blob_gas: None,
                 },
             ]),
         }.encode(&mut data);
@@ -289,6 +291,8 @@ mod test {
                     nonce: 0x0000000000000000u64,
                     base_fee_per_gas: None,
                     withdrawals_root: None,
+                    blob_gas_used: None,
+                    excess_blob_gas: None,
                 },
             ]),
         };
@@ -401,6 +405,8 @@ mod test {
                             nonce: 0x0000000000000000u64,
                             base_fee_per_gas: None,
                             withdrawals_root: None,
+                            blob_gas_used: None,
+                            excess_blob_gas: None,
                         },
                     ],
                     withdrawals: None,
@@ -485,6 +491,8 @@ mod test {
                             nonce: 0x0000000000000000u64,
                             base_fee_per_gas: None,
                             withdrawals_root: None,
+                            blob_gas_used: None,
+                            excess_blob_gas: None,
                         },
                     ],
                     withdrawals: None,

crates/payload/basic/src/lib.rs

@@ -714,6 +714,8 @@ fn build_payload<Pool, Client>(
             difficulty: U256::ZERO,
             gas_used: cumulative_gas_used,
             extra_data: extra_data.into(),
+            blob_gas_used: None,
+            excess_blob_gas: None,
         };
 
         // seal the block
@@ -785,6 +787,8 @@ where
         difficulty: U256::ZERO,
         gas_used: 0,
         extra_data: extra_data.into(),
+        blob_gas_used: None,
+        excess_blob_gas: None,
     };
 
     let block = Block { header, body: vec![], ommers: vec![], withdrawals };

crates/primitives/src/blobfee.rs

@@ -0,0 +1,12 @@
+//! Helpers for working with EIP-4844 blob fee
+
+use crate::constants::eip4844::TARGET_DATA_GAS_PER_BLOCK;
+
+/// Calculates the excess data gas for the next block, after applying the current set of blobs on
+/// top of the excess data gas.
+///
+/// Specified in [EIP-4844](https://eips.ethereum.org/EIPS/eip-4844#header-extension)
+pub fn calculate_excess_blob_gas(parent_excess_blob_gas: u64, parent_blob_gas_used: u64) -> u64 {
+    let excess_blob_gas = parent_excess_blob_gas + parent_blob_gas_used;
+    excess_blob_gas.saturating_sub(TARGET_DATA_GAS_PER_BLOCK)
+}