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fix: adjust EIP-7742 to latest spec #1713

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Merged
mattsse merged 1 commit into from
Nov 30, 2024
Merged

fix: adjust EIP-7742 to latest spec #1713

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28 changes: 2 additions & 26 deletions crates/consensus/src/block/header.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -221,18 +221,9 @@ impl Header {
///
/// Returns `None` if `excess_blob_gas` is None.
///
/// If [`Self::target_blobs_per_block`] is [`Some`], uses EIP-7742 formula for calculating
/// the blob gas price, otherwise uses EIP-4844 formula.
///
/// See also [Self::next_block_excess_blob_gas]
pub fn next_block_blob_fee(&self) -> Option<u128> {
let next_block_excess_blob_gas = self.next_block_excess_blob_gas()?;

if self.target_blobs_per_block().is_none() {
Some(eip4844::calc_blob_gasprice(next_block_excess_blob_gas))
} else {
Some(eip7742::calc_blob_gasprice(next_block_excess_blob_gas))
}
Some(eip4844::calc_blob_gasprice(self.next_block_excess_blob_gas()?))
}

/// Calculate base fee for next block according to the EIP-1559 spec.
Expand All @@ -253,9 +244,6 @@ impl Header {
/// If [`Self::target_blobs_per_block`] is [`Some`], uses EIP-7742 formula for calculating
/// the excess blob gas, otherwise uses EIP-4844 formula.
///
/// Note: this function will return incorrect (unnormalized, lower) value at EIP-7742 activation
/// block. If this is undesired, consider using [`eip7742::calc_excess_blob_gas_at_transition`].
///
/// Returns a `None` if no excess blob gas is set, no EIP-4844 support
pub fn next_block_excess_blob_gas(&self) -> Option<u64> {
let excess_blob_gas = self.excess_blob_gas?;
Expand Down Expand Up @@ -691,9 +679,6 @@ pub trait BlockHeader {
/// If [`BlockHeader::target_blobs_per_block`] is [`Some`], uses EIP-7742 formula for
/// calculating the excess blob gas, otherwise uses EIP-4844 formula.
///
/// Note: this function will return incorrect (unnormalized, lower) value at EIP-7742 activation
/// block. If this is undesired, consider using [`eip7742::calc_excess_blob_gas_at_transition`].
///
/// Returns a `None` if no excess blob gas is set, no EIP-4844 support
fn next_block_excess_blob_gas(&self) -> Option<u64> {
let excess_blob_gas = self.excess_blob_gas()?;
Expand All @@ -715,18 +700,9 @@ pub trait BlockHeader {
///
/// Returns `None` if `excess_blob_gas` is None.
///
/// If this header has `target_blobs_per_block` set, uses EIP-7742 formula for calculating
/// the blob gas price, otherwise uses EIP-4844 formula.
///
/// See also [BlockHeader::next_block_excess_blob_gas]
fn next_block_blob_fee(&self) -> Option<u128> {
let next_block_excess_blob_gas = self.next_block_excess_blob_gas()?;

if self.target_blobs_per_block().is_none() {
Some(eip4844::calc_blob_gasprice(next_block_excess_blob_gas))
} else {
Some(eip7742::calc_blob_gasprice(next_block_excess_blob_gas))
}
Some(eip4844::calc_blob_gasprice(self.next_block_excess_blob_gas()?))
}

/// Calculate base fee for next block according to the EIP-1559 spec.
Expand Down
56 changes: 5 additions & 51 deletions crates/eips/src/eip7742.rs
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Original file line number Diff line number Diff line change
@@ -1,64 +1,18 @@
//! Contains constants and utility functions for [EIP-7742](https://eips.ethereum.org/EIPS/eip-7742)

use crate::eip4844::{self, fake_exponential, BLOB_TX_MIN_BLOB_GASPRICE, DATA_GAS_PER_BLOB};

/// Controls the update rate of the blob base fee based on `target_blobs_per_block`.
pub const BLOB_BASE_FEE_UPDATE_FRACTION_PER_TARGET_BLOB: u128 = 1112825;

/// Controls the update rate of the blob base fee based on `target_blobs_per_block`.
pub const EXCESS_BLOB_GAS_NORMALIZATION_TARGET: u64 = 128;

/// Same as [`eip4844::BLOB_GASPRICE_UPDATE_FRACTION`], but normalized for the target of 128
/// blobs.
pub const BLOB_BASE_FEE_UPDATE_FRACTION_NORMALIZED: u128 =
BLOB_BASE_FEE_UPDATE_FRACTION_PER_TARGET_BLOB * EXCESS_BLOB_GAS_NORMALIZATION_TARGET as u128;

/// Calculates the `excess_blob_gas` for the header of the block enabling EIP-7742.
///
/// Normalizes the parent's excess blob gas as per EIP-7742.
#[inline]
pub const fn calc_excess_blob_gas_at_transition(
parent_excess_blob_gas: u64,
parent_blob_gas_used: u64,
) -> u64 {
let normalized_parent_excess_blob_gas = parent_excess_blob_gas
* EXCESS_BLOB_GAS_NORMALIZATION_TARGET
/ eip4844::TARGET_BLOBS_PER_BLOCK;

calc_excess_blob_gas(
normalized_parent_excess_blob_gas,
parent_blob_gas_used,
eip4844::TARGET_BLOBS_PER_BLOCK,
)
}
use crate::eip4844;

/// Calculates the `excess_blob_gas` from the parent header's `blob_gas_used`, `excess_blob_gas` and
/// `target_blobs_per_block`.
///
/// Note: this function assumes that the parent block's excess blob gas is normalized as per
/// EIP-7742.
/// Similar to [`eip4844::calc_excess_blob_gas`], but uses the `target_blobs_per_block` to calculate
/// the target gas usage.
#[inline]
pub const fn calc_excess_blob_gas(
parent_excess_blob_gas: u64,
parent_blob_gas_used: u64,
parent_target_blobs_per_block: u64,
) -> u64 {
let normalized_blob_gas_used =
parent_blob_gas_used * EXCESS_BLOB_GAS_NORMALIZATION_TARGET / parent_target_blobs_per_block;
let normalized_target_blob_gas = DATA_GAS_PER_BLOB * EXCESS_BLOB_GAS_NORMALIZATION_TARGET;

(parent_excess_blob_gas + normalized_blob_gas_used).saturating_sub(normalized_target_blob_gas)
}

/// Calculates the blob gas price from the header's excess blob gas field.
///
/// Similar to [crate::eip4844::calc_blob_gasprice], but adjusts the update rate based on
/// `target_blobs_per_block`.
#[inline]
pub fn calc_blob_gasprice(excess_blob_gas: u64) -> u128 {
fake_exponential(
BLOB_TX_MIN_BLOB_GASPRICE,
excess_blob_gas as u128,
BLOB_BASE_FEE_UPDATE_FRACTION_NORMALIZED,
)
(parent_excess_blob_gas + parent_blob_gas_used)
.saturating_sub(parent_target_blobs_per_block * eip4844::DATA_GAS_PER_BLOB)
}