block: moved DAO extra data check logic to dedicated function, added …

…two DAO HF extra data block creation tests

packages/block/src/header.ts

@@ -13,9 +13,6 @@ import { Blockchain, BlockHeaderData, BufferLike, ChainOptions, PrefixedHexStrin
 import { Buffer } from 'buffer'
 import { Block } from './block'
 
-const DAO_ExtraData = Buffer.from('64616f2d686172642d666f726b', 'hex')
-const DAO_ForceExtraDataRange = 9 // force extra data be DAO_ExtraData for X blocks after DAO activation block (see: https://blog.slock.it/hard-fork-specification-24b889e70703)
-
 /**
  * An object that represents the block header
  */
@@ -136,19 +133,7 @@ export class BlockHeader {
     ]
     defineProperties(this, fields, data)
 
-    if (this._common.hardforkIsActiveOnChain('dao')) {
-      // verify the extraData field.
-      const blockNumber = new BN(this.number)
-      const DAOActivationBlock = new BN(this._common.hardforkBlock('dao'))
-      if (blockNumber.gte(DAOActivationBlock)) {
-        const drift = blockNumber.sub(DAOActivationBlock)
-        if (drift.lten(DAO_ForceExtraDataRange)) {
-          if (!this.extraData.equals(DAO_ExtraData)) {
-            throw new Error("extraData should be 'dao-hard-fork'")
-          }
-        }
-      }
-    }
+    this._checkDAOExtraData()
   }
 
   /**
@@ -374,4 +359,27 @@ export class BlockHeader {
       return undefined
     }
   }
+
+  /**
+   * Force extra data be DAO_ExtraData for DAO_ForceExtraDataRange blocks after DAO
+   * activation block (see: https://blog.slock.it/hard-fork-specification-24b889e70703)
+   */
+  private _checkDAOExtraData() {
+    const DAO_ExtraData = Buffer.from('64616f2d686172642d666f726b', 'hex')
+    const DAO_ForceExtraDataRange = 9
+
+    if (this._common.hardforkIsActiveOnChain('dao')) {
+      // verify the extraData field.
+      const blockNumber = new BN(this.number)
+      const DAOActivationBlock = new BN(this._common.hardforkBlock('dao'))
+      if (blockNumber.gte(DAOActivationBlock)) {
+        const drift = blockNumber.sub(DAOActivationBlock)
+        if (drift.lten(DAO_ForceExtraDataRange)) {
+          if (!this.extraData.equals(DAO_ExtraData)) {
+            throw new Error("extraData should be 'dao-hard-fork'")
+          }
+        }
+      }
+    }
+  }
 }

packages/block/test/block.spec.ts

@@ -144,4 +144,26 @@ tape('[Block]: block functions', function (t) {
     st.equal(typeof block.toJSON(true), 'object')
     st.end()
   })
+
+  t.test('DAO hardfork', function (st) {
+    const blockData: any = rlp.decode(testData2.blocks[0].rlp)
+    // Set block number from test block to mainnet DAO fork block 1920000
+    blockData[0][8] = Buffer.from('1D4C00', 'hex')
+
+    const common = new Common('mainnet', 'dao')
+    st.throws(
+      function () {
+        new Block(blockData, { common: common })
+      },
+      /Error: extraData should be 'dao-hard-fork'$/,
+      'should throw on DAO HF block with wrong extra data',
+    ) // eslint-disable-line
+
+    // Set extraData to dao-hard-fork
+    blockData[0][12] = Buffer.from('64616f2d686172642d666f726b', 'hex')
+    st.doesNotThrow(function () {
+      new Block(blockData, { common: common })
+    }, 'should not throw on DAO HF block with correct extra data')
+    st.end()
+  })
 })