Add CHAINID opcode for istanbul (eip-1344)

lib/evm/eei.ts

@@ -262,6 +262,14 @@ export default class EEI {
     return new BN(this._env.block.header.gasLimit)
   }
 
+  /**
+   * Returns the chain ID for current chain. Introduced for the
+   * CHAINID opcode proposed in [EIP-1344](https://eips.ethereum.org/EIPS/eip-1344).
+   */
+  getChainId(): BN {
+    return new BN(this._common.chainId())
+  }
+
   /**
    * Returns Gets the hash of one of the 256 most recent complete blocks.
    * @param num - Number of block

lib/evm/opFns.ts

@@ -456,6 +456,13 @@ export const handlers: { [k: string]: OpHandler } = {
   GASLIMIT: function(runState: RunState) {
     runState.stack.push(runState.eei.getBlockGasLimit())
   },
+  CHAINID: function(runState: RunState) {
+    if (!runState._common.gteHardfork('istanbul')) {
+      trap(ERROR.INVALID_OPCODE)
+    }
+
+    runState.stack.push(runState.eei.getChainId())
+  },
   // 0x50 range - 'storage' and execution
   POP: function(runState: RunState) {
     runState.stack.pop()

lib/evm/opcodes.ts

@@ -66,6 +66,7 @@ const codes: any = {
   0x43: ['NUMBER', 2, true],
   0x44: ['DIFFICULTY', 2, true],
   0x45: ['GASLIMIT', 2, true],
+  0x46: ['CHAINID', 2, false],
 
   // 0x50 range - 'storage' and execution
   0x50: ['POP', 2, false],

tests/api/istanbul/eip-1344.js

@@ -0,0 +1,38 @@
+const tape = require('tape')
+const BN = require('bn.js')
+const Common = require('ethereumjs-common').default
+const VM = require('../../../dist/index').default
+const { ERROR } = require('../../../dist/exceptions')
+
+const testCases = [
+  { chain: 'mainnet', hardfork: 'istanbul', chainId: new BN(1) },
+  { chain: 'mainnet', hardfork: 'constantinople', err: ERROR.INVALID_OPCODE },
+  { chain: 'ropsten', hardfork: 'istanbul', chainId: new BN(3) }
+]
+
+// CHAINID PUSH8 0x00 MSTORE8 PUSH8 0x01 PUSH8 0x00 RETURN
+const code = ['46', '60', '00', '53', '60', '01', '60', '00', 'f3']
+tape('Istanbul: EIP-1344 CHAINID', async (t) => {
+  const runCodeArgs = {
+    code: Buffer.from(code.join(''), 'hex'),
+    gasLimit: new BN(0xffff)
+  }
+
+  for (const testCase of testCases) {
+    const common = new Common(testCase.chain, testCase.hardfork)
+    const vm = new VM({ common })
+    try {
+      const res = await vm.runCode(runCodeArgs)
+      if (testCase.err) {
+        t.equal(res.exceptionError.error, testCase.err)
+      } else {
+        t.assert(res.exceptionError === undefined)
+        t.assert(testCase.chainId.eq(new BN(res.returnValue)))
+      }
+    } catch (e) {
+      t.fail(e.message)
+    }
+  }
+
+  t.end()
+})