common: allow specifying eip-7840 blobSchedule via geth genesis (#3835)

* common: allow specifying eip-7840 blobSchedule via geth genesis

* add test and fix the hardforkchanges override issue

* add to spell dict

* update cspell.ts

* common: update checks for blobs and add tests

* common: remove old code

---------

Co-authored-by: Jochem Brouwer <[email protected]>

Author: g11tech

config/cspell-ts.json

@@ -629,6 +629,7 @@
     "Unsnappy",
     "unsnappy",
     "ethportal",
-    "bytevector"
+    "bytevector",
+    "blobschedule"
   ]
 }

packages/common/src/common.ts

@@ -66,8 +66,9 @@ export class Common {
     // Assign hardfork changes in the sequence of the applied hardforks
     this.HARDFORK_CHANGES = this.hardforks().map((hf) => [
       hf.name,
-      hardforksDict[hf.name] ??
-        (this._chainParams.customHardforks && this._chainParams.customHardforks[hf.name]),
+      // Allow to even override an existing hardfork specification
+      (this._chainParams.customHardforks && this._chainParams.customHardforks[hf.name]) ??
+        hardforksDict[hf.name],
     ])
     this._hardfork = this.DEFAULT_HARDFORK
     this._params = opts.params ? JSON.parse(JSON.stringify(opts.params)) : {} // copy
@@ -322,7 +323,7 @@ export class Common {
           this._mergeWithParamsCache(this._params[eip] ?? {})
         }
       }
-      // Parameter-inlining HF config (e.g. for istanbul)
+      // Parameter-inlining HF config (e.g. for istanbul or custom blobSchedule)
       this._mergeWithParamsCache(hfChanges[1].params ?? {})
       if (hfChanges[0] === hardfork) break
     }

packages/common/src/utils.ts

@@ -2,7 +2,9 @@ import { intToHex, isHexString, stripHexPrefix } from '@ethereumjs/util'
 
 import { Holesky, Kaustinen6, Mainnet, Sepolia } from './chains.js'
 import { Hardfork } from './enums.js'
+import { hardforksDict } from './hardforks.js'
 
+import type { HardforksDict } from './types.js'
 import type { PrefixedHexString } from '@ethereumjs/util'
 
 type ConfigHardfork =
@@ -83,6 +85,42 @@ function parseGethParams(json: any) {
     )
   }
 
+  let customHardforks: HardforksDict | undefined = undefined
+  if (config.blobSchedule !== undefined) {
+    customHardforks = {}
+    const blobGasPerBlob = 131072
+    for (const [hfKey, hfSchedule] of Object.entries(config.blobSchedule)) {
+      const hfConfig = hardforksDict[hfKey]
+      if (hfConfig === undefined) {
+        throw new Error(`unknown hardfork=${hfKey} specified in blobSchedule`)
+      }
+      const {
+        target,
+        max,
+        baseFeeUpdateFraction: blobGasPriceUpdateFraction,
+      } = hfSchedule as { target?: number; max?: number; baseFeeUpdateFraction?: undefined }
+      if (target === undefined || max === undefined || blobGasPriceUpdateFraction === undefined) {
+        throw new Error(
+          `undefined target, max or baseFeeUpdateFraction specified in blobSchedule for hardfork=${hfKey}`,
+        )
+      }
+
+      // copy current hardfork info to custom and add blob config
+      const customHfConfig = JSON.parse(JSON.stringify(hfConfig))
+      customHfConfig.params = {
+        ...customHardforks.params,
+        // removes blobGasPriceUpdateFraction key to prevent undefined overriding if undefined
+        ...{
+          targetBlobGasPerBlock: blobGasPerBlob * target,
+          maxBlobGasPerBlock: blobGasPerBlob * max,
+          blobGasPriceUpdateFraction,
+        },
+      }
+
+      customHardforks[hfKey] = customHfConfig
+    }
+  }
+
   const params = {
     name,
     chainId,
@@ -101,6 +139,7 @@ function parseGethParams(json: any) {
     },
     hardfork: undefined as string | undefined,
     hardforks: [] as ConfigHardfork[],
+    customHardforks,
     bootstrapNodes: [],
     consensus:
       config.clique !== undefined

packages/common/test/utils.spec.ts

@@ -79,7 +79,7 @@ describe('[Utils/Parse]', () => {
 
   it('should correctly parse deposit contract address', async () => {
     // clone json out to not have side effects
-    const customData = postMergeHardforkData
+    const customData = JSON.parse(JSON.stringify(postMergeHardforkData))
     Object.assign(customData.config, {
       depositContractAddress: '0x4242424242424242424242424242424242424242',
     })
@@ -122,4 +122,137 @@ describe('[Utils/Parse]', () => {
       -1,
     )
   })
+
+  it('should assign correct blob schedule', () => {
+    // clone json out to not have side effects
+    const customData = JSON.parse(JSON.stringify(postMergeHardforkData))
+    const customConfigData = {
+      chainId: 3151908,
+      homesteadBlock: 0,
+      eip150Block: 0,
+      eip155Block: 0,
+      eip158Block: 0,
+      byzantiumBlock: 0,
+      constantinopleBlock: 0,
+      petersburgBlock: 0,
+      istanbulBlock: 0,
+      berlinBlock: 0,
+      londonBlock: 0,
+      mergeNetsplitBlock: 0,
+      depositContractAddress: '0x4242424242424242424242424242424242424242',
+      terminalTotalDifficulty: 0,
+      terminalTotalDifficultyPassed: true,
+      shanghaiTime: 0,
+      cancunTime: 0,
+      blobSchedule: {
+        prague: {
+          target: 61,
+          max: 91,
+          baseFeeUpdateFraction: 13338477,
+        },
+      },
+      pragueTime: 1736942378,
+    }
+    Object.assign(customData.config, customConfigData)
+
+    const common = createCommonFromGethGenesis(customData, {
+      chain: 'customChain',
+    })
+    const paramsTx = {
+      4844: {
+        blobCommitmentVersionKzg: 1, // The number indicated a versioned hash is a KZG commitment
+        blobGasPerBlob: 131072, // The base fee for blob gas per blob
+        maxBlobGasPerBlock: 786432, // The max blob gas allowable per block
+        blobGasPriceUpdateFraction: 3338477,
+        targetBlobGasPerBlock: 393216,
+      },
+      7691: {
+        maxBlobGasPerBlock: 1179648, // The max blob gas allowable per block
+      },
+    }
+    common.updateParams(paramsTx)
+
+    const blobGasPerBlob = common.param('blobGasPerBlob')
+
+    const testCases = [
+      // should be picked from eip params
+      [Hardfork.Cancun, blobGasPerBlob * BigInt(3), blobGasPerBlob * BigInt(6), 3338477n],
+      // from the genesis blobschedule
+      [
+        Hardfork.Prague,
+        blobGasPerBlob * BigInt(customConfigData.blobSchedule.prague.target),
+        blobGasPerBlob * BigInt(customConfigData.blobSchedule.prague.max),
+        13338477,
+      ],
+    ]
+    for (const [testHf, testTarget, testMax, testUpdateFraction] of testCases) {
+      common.setHardfork(testHf as Hardfork)
+
+      const targetBlobGasPerBlock = common.param('targetBlobGasPerBlock')
+      const maxBlobGasPerBlock = common.param('maxBlobGasPerBlock')
+      const blobGasPriceUpdateFraction = common.param('blobGasPriceUpdateFraction')
+
+      assert.equal(targetBlobGasPerBlock, testTarget, 'target blob gas should match')
+      assert.equal(maxBlobGasPerBlock, testMax, 'max blob gas should match')
+      assert.equal(blobGasPriceUpdateFraction, testUpdateFraction, 'update fraction should match')
+    }
+  })
+
+  it('should throw on invalid blob schedules', () => {
+    const customData = JSON.parse(JSON.stringify(postMergeHardforkData))
+    const customConfigData = {
+      chainId: 3151908,
+      homesteadBlock: 0,
+      eip150Block: 0,
+      eip155Block: 0,
+      eip158Block: 0,
+      byzantiumBlock: 0,
+      constantinopleBlock: 0,
+      petersburgBlock: 0,
+      istanbulBlock: 0,
+      berlinBlock: 0,
+      londonBlock: 0,
+      mergeNetsplitBlock: 0,
+      depositContractAddress: '0x4242424242424242424242424242424242424242',
+      terminalTotalDifficulty: 0,
+      terminalTotalDifficultyPassed: true,
+      shanghaiTime: 0,
+      cancunTime: 0,
+      pragueTime: 1736942378,
+      blobSchedule: undefined,
+    }
+    Object.assign(customData.config, customConfigData)
+    const invalidBlobSchedules = [
+      {
+        prague: {
+          max: 91,
+          baseFeeUpdateFraction: 13338477,
+        },
+      },
+      {
+        prague: {
+          target: 61,
+          baseFeeUpdateFraction: 13338477,
+        },
+      },
+      {
+        prague: {
+          target: 61,
+          max: 91,
+        },
+      },
+      {
+        unknownHardfork: {
+          target: 61,
+          max: 91,
+          baseFeeUpdateFraction: 13338477,
+        },
+      },
+    ]
+
+    for (const schedule of invalidBlobSchedules) {
+      customData.config.blobSchedule = schedule
+      assert.throws(() => createCommonFromGethGenesis(customData, {}))
+    }
+  })
 })