feat: implement eip-7918 (#4142)

gabrocheleau · holgerd77 · web-flow · commit 0dce642ab725 · 2025-10-09T09:49:26.000-04:00
* feat: implement eip-7918 (draft)

* chore: fix type errors

* chore: fix implementation

* chore: adjust naming

* test: fix test

* test: fix test

* chore: fix test case

* chore: fix test case

* chore: reset submodule

* chore: address review

---------

Co-authored-by: Holger Drewes &lt;Holger.Drewes@gmail.com&gt;
diff --git a/packages/block/src/header/header.ts b/packages/block/src/header/header.ts
@@ -560,15 +560,32 @@ export class BlockHeader {
    * Calculates the excess blob gas for next (hopefully) post EIP 4844 block.
    */
   public calcNextExcessBlobGas(childCommon: Common): bigint {
-    // The validation of the fields and 4844 activation is already taken care in BlockHeader constructor
-    const targetGasConsumed = (this.excessBlobGas ?? BIGINT_0) + (this.blobGasUsed ?? BIGINT_0)
-    const targetBlobGasPerBlock = childCommon.param('targetBlobGasPerBlock')
+    const excessBlobGas = this.excessBlobGas ?? BIGINT_0
+    const blobGasUsed = this.blobGasUsed ?? BIGINT_0
 
-    if (targetGasConsumed <= targetBlobGasPerBlock) {
-      return BIGINT_0
-    } else {
-      return targetGasConsumed - targetBlobGasPerBlock
+    const targetPerBlock = childCommon.param('targetBlobGasPerBlock')
+    const maxPerBlock = childCommon.param('maxBlobGasPerBlock')
+
+    // Early exit (strictly < per spec)
+    if (excessBlobGas + blobGasUsed < targetPerBlock) {
+      return 0n
+    }
+
+    // EIP-7918 reserve price check
+    if (childCommon.isActivatedEIP(7918)) {
+      const blobBaseCost = childCommon.param('blobBaseCost')
+      const gasPerBlob = childCommon.param('blobGasPerBlob')
+      const baseFee = this.baseFeePerGas ?? 0n
+      const blobFee = this.getBlobGasPrice()
+
+      if (blobBaseCost * baseFee > gasPerBlob * blobFee) {
+        const increase = (blobGasUsed * (maxPerBlock - targetPerBlock)) / maxPerBlock
+        return excessBlobGas + increase
+      }
     }
+
+    // Original 4844 path
+    return excessBlobGas + blobGasUsed - targetPerBlock
   }
 
   /**
@@ -635,9 +652,7 @@ export class BlockHeader {
    */
   hash(): Uint8Array {
     if (Object.isFrozen(this)) {
-      if (!this.cache.hash) {
-        this.cache.hash = this.keccakFunction(RLP.encode(this.raw())) as Uint8Array
-      }
+      this.cache.hash ??= this.keccakFunction(RLP.encode(this.raw())) as Uint8Array
       return this.cache.hash
     }
     return this.keccakFunction(RLP.encode(this.raw()))
diff --git a/packages/block/src/params.ts b/packages/block/src/params.ts
@@ -74,6 +74,7 @@ export const paramsBlock: ParamsDict = {
     blobGasPriceUpdateFraction: 3338477, // The denominator used in the exponential when calculating a blob gas price
     // gasPrices
     minBlobGas: 1, // The minimum fee per blob gas
+    blobBaseCost: 8192, // EIP-7918: Blob base fee bounded by execution cost (2^13)
   },
   /**
    * Delaying Difficulty Bomb to mid-September 2022
diff --git a/packages/block/test/eip4844block.spec.ts b/packages/block/test/eip4844block.spec.ts
@@ -161,6 +161,105 @@ describe('blob gas tests', () => {
     const nextBlobGas = highGasHeader.calcNextBlobGasPrice(common)
     assert.strictEqual(nextBlobGas, BigInt(7)) // TODO verify that this is correct
   })
+
+  describe('EIP-7918: Blob base fee bounded by execution cost', () => {
+    const osakaCommon = createCommonFromGethGenesis(eip4844GethGenesis, {
+      chain: 'customChain',
+      hardfork: Hardfork.Cancun,
+      params: paramsBlock,
+      customCrypto: { kzg },
+      eips: [7918],
+    })
+
+    it('applies reserve price when exec cost dominates', () => {
+      const highBaseFee = 1_000_000_000_000_000n
+      const target = osakaCommon.param('targetBlobGasPerBlock')
+      const max = osakaCommon.param('maxBlobGasPerBlock')
+      const BLOB_BASE_COST = osakaCommon.param('blobBaseCost')
+      const GAS_PER_BLOB = osakaCommon.param('blobGasPerBlob')
+
+      const header = createBlockHeader(
+        {
+          number: 1,
+          baseFeePerGas: highBaseFee,
+          excessBlobGas: 0n,
+          blobGasUsed: target,
+        },
+        { common: osakaCommon, skipConsensusFormatValidation: true },
+      )
+
+      assert.isTrue(BLOB_BASE_COST * highBaseFee > GAS_PER_BLOB * header.getBlobGasPrice())
+
+      const got = header.calcNextExcessBlobGas(osakaCommon)
+      const expected = (target * (max - target)) / max
+      assert.strictEqual(got, expected)
+    })
+
+    it('should use original EIP-4844 logic when reserve price condition is not met', () => {
+      // Create a header with low base fee and high blob gas price
+      const lowBaseFee = 1n // Very low base fee (1 wei)
+
+      // Set excessBlobGas to a high value to get high blob gas price
+      const highExcessBlobGas = 1000000000n
+      const header = createBlockHeader(
+        {
+          number: 1,
+          baseFeePerGas: lowBaseFee,
+          excessBlobGas: highExcessBlobGas,
+          blobGasUsed: blobGasPerBlob * 2n, // 2 blobs used
+        },
+        { common: osakaCommon, skipConsensusFormatValidation: true },
+      )
+
+      const excessBlobGas = header.calcNextExcessBlobGas(osakaCommon)
+
+      // Should use original EIP-4844 logic
+      const blobBaseCost = osakaCommon.param('blobBaseCost')
+      const currentBlobGasPrice = header.getBlobGasPrice()
+
+      // Check that reserve price condition is not met
+      assert.isTrue(
+        blobBaseCost * lowBaseFee <= blobGasPerBlob * currentBlobGasPrice,
+        'reserve price condition should not be met',
+      )
+
+      const targetGasConsumed = highExcessBlobGas + blobGasPerBlob * 2n
+      const targetBlobGasPerBlock = osakaCommon.param('targetBlobGasPerBlock')
+      const expectedExcessBlobGas = targetGasConsumed - targetBlobGasPerBlock
+
+      assert.strictEqual(
+        excessBlobGas,
+        expectedExcessBlobGas,
+        'should use original EIP-4844 logic when reserve price condition is not met',
+      )
+    })
+
+    it('should not apply EIP-7918 logic when EIP is not activated', () => {
+      // Use Cancun hardfork where EIP-7918 is not activated
+      const header = createBlockHeader(
+        {
+          number: 1,
+          baseFeePerGas: 1000000000n,
+          excessBlobGas: 1000000n,
+          blobGasUsed: blobGasPerBlob,
+        },
+        { common, skipConsensusFormatValidation: true },
+      )
+
+      const excessBlobGas = header.calcNextExcessBlobGas(common)
+
+      // Should use original EIP-4844 logic since EIP-7918 is not activated
+      const targetGasConsumed = 1000000n + blobGasPerBlob
+      const targetBlobGasPerBlock = common.param('targetBlobGasPerBlock')
+      const expectedExcessBlobGas = targetGasConsumed - targetBlobGasPerBlock
+
+      assert.strictEqual(
+        excessBlobGas,
+        expectedExcessBlobGas,
+        'should use original EIP-4844 logic when EIP-7918 is not activated',
+      )
+    })
+  })
 })
 
 describe('transaction validation tests', () => {
diff --git a/packages/common/README.md b/packages/common/README.md
@@ -364,6 +364,7 @@ The following EIPs are currently supported:
 - [EIP-7516](https://eips.ethereum.org/EIPS/eip-7516) - BLOBBASEFEE opcode (Cancun)
 - [EIP-7623](https://eips.ethereum.org/EIPS/eip-7623) - Increase calldata cost (Prague)
 - [EIP-7685](https://eips.ethereum.org/EIPS/eip-7685) - General purpose execution layer requests (Prague)
+- [EIP-7918](https://eips.ethereum.org/EIPS/eip-7918) - Blob base fee bounded by execution cost (Osaka)
 - [EIP-7691](https://eips.ethereum.org/EIPS/eip-7691) - Blob throughput increase (Prague)
 - [EIP-7692](https://eips.ethereum.org/EIPS/eip-7692) - EVM Object Format (EOF) v1 (`experimental`)
 - [EIP-7702](https://eips.ethereum.org/EIPS/eip-7702) - Set EOA account code (Prague)
diff --git a/packages/common/src/eips.ts b/packages/common/src/eips.ts
@@ -442,6 +442,15 @@ export const eipsDict: EIPsDict = {
     minimumHardfork: Hardfork.Paris,
     requiredEIPs: [4844],
   },
+  /**
+   * Description : Blob base fee bounded by execution cost
+   * URL         : https://eips.ethereum.org/EIPS/eip-7918
+   * Status      : Last Call
+   */
+  7918: {
+    minimumHardfork: Hardfork.Paris,
+    requiredEIPs: [4844],
+  },
   /**
    * Description : EVM Object Format (EOFv1) Meta
    * URL         : https://github.com/ethereum/EIPs/blob/4153e95befd0264082de3c4c2fe3a85cc74d3152/EIPS/eip-7692.md
diff --git a/packages/common/src/hardforks.ts b/packages/common/src/hardforks.ts
@@ -166,7 +166,7 @@ export const hardforksDict: HardforksDict = {
    * Status     : Draft
    */
   osaka: {
-    eips: [7594, 7823, 7825, 7883, 7939, 7951],
+    eips: [7594, 7823, 7825, 7883, 7939, 7951, 7918],
   },
   /**
    * Description: Next feature hardfork after osaka, internally used for verkle testing/implementation (incomplete/experimental)
