Expose and test validator set precompiles

packages/celotool/src/e2e-tests/governance_tests.ts

@@ -3,10 +3,11 @@ import { assert } from 'chai'
 import Web3 from 'web3'
 import { strip0x } from '../lib/utils'
 import {
+  assertRevert,
   erc20Abi,
+  getContext,
   getContractAddress,
   getEnode,
-  getHooks,
   importGenesis,
   initAndStartGeth,
   sleep,
@@ -167,6 +168,39 @@ const validatorsAbi = [
     stateMutability: 'nonpayable',
     type: 'function',
   },
+  {
+    constant: true,
+    inputs: [
+      {
+        name: 'index',
+        type: 'uint256',
+      },
+    ],
+    name: 'validatorAddressFromCurrentSet',
+    outputs: [
+      {
+        name: '',
+        type: 'address',
+      },
+    ],
+    payable: false,
+    stateMutability: 'view',
+    type: 'function',
+  },
+  {
+    constant: true,
+    inputs: [],
+    name: 'numberValidatorsInCurrentSet',
+    outputs: [
+      {
+        name: '',
+        type: 'uint256',
+      },
+    ],
+    payable: false,
+    stateMutability: 'view',
+    type: 'function',
+  },
 ]
 
 describe('governance tests', () => {
@@ -181,21 +215,21 @@ describe('governance tests', () => {
     ],
   }
 
-  const hooks: any = getHooks(gethConfig)
+  const context: any = getContext(gethConfig)
   let web3: any
   let lockedGold: any
   let validators: any
   let goldToken: any
 
   before(async function(this: any) {
     this.timeout(0)
-    await hooks.before()
+    await context.hooks.before()
   })
 
-  after(hooks.after)
+  after(context.hooks.after)
 
   const restart = async () => {
-    await hooks.restart()
+    await context.hooks.restart()
     web3 = new Web3('http://localhost:8545')
     lockedGold = new web3.eth.Contract(lockedGoldAbi, await getContractAddress('LockedGoldProxy'))
     goldToken = new web3.eth.Contract(erc20Abi, await getContractAddress('GoldTokenProxy'))
@@ -289,6 +323,147 @@ describe('governance tests', () => {
     return tx.send({ from: account, ...txOptions, gas })
   }
 
+  describe('Validators.numberValidatorsInCurrentSet()', () => {
+    before(async function() {
+      this.timeout(0)
+      await restart()
+      validators = new web3.eth.Contract(validatorsAbi, await getContractAddress('ValidatorsProxy'))
+    })
+
+    it('should return the validator set size', async () => {
+      const numberValidators = await validators.methods.numberValidatorsInCurrentSet().call()
+
+      assert.equal(numberValidators, 5)
+    })
+
+    describe('after the validator set changes', () => {
+      before(async function() {
+        this.timeout(0)
+        await restart()
+        const [groupAddress, groupPrivateKey] = await getValidatorGroupKeys()
+        const epoch = 10
+
+        const groupInstance = {
+          name: 'validatorGroup',
+          validating: false,
+          syncmode: 'full',
+          port: 30325,
+          wsport: 8567,
+          privateKey: groupPrivateKey.slice(2),
+          peers: [await getEnode(8545)],
+        }
+        await initAndStartGeth(context.hooks.gethBinaryPath, groupInstance)
+        const groupWeb3 = new Web3('ws://localhost:8567')
+        validators = new groupWeb3.eth.Contract(
+          validatorsAbi,
+          await getContractAddress('ValidatorsProxy')
+        )
+        // Give the node time to sync.
+        await sleep(15)
+        const members = await getValidatorGroupMembers()
+        await removeMember(groupWeb3, groupAddress, members[0])
+        await sleep(epoch * 2)
+      })
+
+      it('should return the reduced validator set size', async () => {
+        const numberValidators = await validators.methods.numberValidatorsInCurrentSet().call()
+
+        assert.equal(numberValidators, 4)
+      })
+    })
+  })
+
+  describe('Validators.validatorAddressFromCurrentSet()', () => {
+    before(async function() {
+      this.timeout(0)
+      await restart()
+      validators = new web3.eth.Contract(validatorsAbi, await getContractAddress('ValidatorsProxy'))
+    })
+
+    it('should return the first validator', async () => {
+      const resultAddress = await validators.methods.validatorAddressFromCurrentSet(0).call()
+
+      assert.equal(strip0x(resultAddress), context.validators[0].address)
+    })
+
+    it('should return the third validator', async () => {
+      const resultAddress = await validators.methods.validatorAddressFromCurrentSet(2).call()
+
+      assert.equal(strip0x(resultAddress), context.validators[2].address)
+    })
+
+    it('should return the fifth validator', async () => {
+      const resultAddress = await validators.methods.validatorAddressFromCurrentSet(4).call()
+
+      assert.equal(strip0x(resultAddress), context.validators[4].address)
+    })
+
+    it('should revert when asked for an out of bounds validator', async function(this: any) {
+      this.timeout(0) // Disable test timeout
+      await assertRevert(
+        validators.methods.validatorAddressFromCurrentSet(5).send({
+          from: `0x${context.validators[0].address}`,
+        })
+      )
+    })
+
+    describe('after the validator set changes', () => {
+      before(async function() {
+        this.timeout(0)
+        await restart()
+        const [groupAddress, groupPrivateKey] = await getValidatorGroupKeys()
+        const epoch = 10
+
+        const groupInstance = {
+          name: 'validatorGroup',
+          validating: false,
+          syncmode: 'full',
+          port: 30325,
+          wsport: 8567,
+          privateKey: groupPrivateKey.slice(2),
+          peers: [await getEnode(8545)],
+        }
+        await initAndStartGeth(context.hooks.gethBinaryPath, groupInstance)
+        const groupWeb3 = new Web3('ws://localhost:8567')
+        validators = new groupWeb3.eth.Contract(
+          validatorsAbi,
+          await getContractAddress('ValidatorsProxy')
+        )
+        // Give the node time to sync.
+        await sleep(15)
+        const members = await getValidatorGroupMembers()
+        await removeMember(groupWeb3, groupAddress, members[0])
+        await sleep(epoch * 2)
+
+        validators = new web3.eth.Contract(
+          validatorsAbi,
+          await getContractAddress('ValidatorsProxy')
+        )
+      })
+
+      it('should return the second validator in the first place', async () => {
+        const resultAddress = await validators.methods.validatorAddressFromCurrentSet(0).call()
+
+        assert.equal(strip0x(resultAddress), context.validators[1].address)
+      })
+
+      it('should return the last validator in the fourth place', async () => {
+        const resultAddress = await validators.methods.validatorAddressFromCurrentSet(3).call()
+
+        assert.equal(strip0x(resultAddress), context.validators[4].address)
+      })
+
+      it('should revert when asked for an out of bounds validator', async function(this: any) {
+        this.timeout(0)
+        await assertRevert(
+          validators.methods.validatorAddressFromCurrentSet(4).send({
+            from: `0x${context.validators[0].address}`,
+          })
+        )
+      })
+    })
+  })
+
   describe('when the validator set is changing', () => {
     const epoch = 10
     const expectedEpochMembership = new Map()
@@ -306,7 +481,7 @@ describe('governance tests', () => {
         privateKey: groupPrivateKey.slice(2),
         peers: [await getEnode(8545)],
       }
-      await initAndStartGeth(hooks.gethBinaryPath, groupInstance)
+      await initAndStartGeth(context.hooks.gethBinaryPath, groupInstance)
       const groupWeb3 = new Web3('ws://localhost:8567')
       validators = new groupWeb3.eth.Contract(
         validatorsAbi,
@@ -377,7 +552,7 @@ describe('governance tests', () => {
         rpcport: 8567,
         privateKey: 'f2f48ee19680706196e2e339e5da3491186e0c4c5030670656b0e0164837257d',
       }
-      await initAndStartGeth(hooks.gethBinaryPath, delegateInstance)
+      await initAndStartGeth(context.hooks.gethBinaryPath, delegateInstance)
       // Note that we don't need to create an account or make a commitment as this has already been
       // done in the migration.
       await delegateRewards(account, delegate)

packages/celotool/src/e2e-tests/utils.ts

@@ -385,7 +385,7 @@ export async function initAndStartGeth(gethBinaryPath: string, instance: GethIns
   return startGeth(gethBinaryPath, instance)
 }
 
-export function getHooks(gethConfig: GethTestConfig) {
+export function getContext(gethConfig: GethTestConfig) {
   const mnemonic =
     'jazz ripple brown cloth door bridge pen danger deer thumb cable prepare negative library vast'
   const validatorInstances = gethConfig.instances.filter((x: any) => x.validating)
@@ -449,7 +449,14 @@ export function getHooks(gethConfig: GethTestConfig) {
 
   const after = () => killGeth()
 
-  return { before, after, restart, gethBinaryPath }
+  return {
+    validators,
+    hooks: { before, after, restart, gethBinaryPath },
+  }
+}
+
+export function getHooks(gethConfig: GethTestConfig) {
+  return getContext(gethConfig).hooks
 }
 
 export async function assertRevert(promise: any, errorMessage: string = '') {

packages/protocol/contracts/governance/Validators.sol

@@ -24,6 +24,9 @@ contract Validators is IValidators, Ownable, ReentrancyGuard, Initializable, Usi
   using SafeMath for uint256;
   using BytesLib for bytes;
 
+  // Address of the getValidator precompiled contract
+  address constant public GET_VALIDATOR_ADDRESS = address(0xfa);
+
   // TODO(asa): These strings should be modifiable
   struct ValidatorGroup {
     string identifier;
@@ -543,6 +546,45 @@ contract Validators is IValidators, Ownable, ReentrancyGuard, Initializable, Usi
     return true;
   }
 
+  function validatorAddressFromCurrentSet(uint256 index) external view returns (address) {
+    address validatorAddress;
+    assembly {
+      let newCallDataPosition := mload(0x40)
+      mstore(newCallDataPosition, index)
+      let success := staticcall(
+        5000,
+        0xfa,
+        newCallDataPosition,
+        32,
+        0,
+        0
+      )
+      returndatacopy(add(newCallDataPosition, 64), 0, 32)
+      validatorAddress := mload(add(newCallDataPosition, 64))
+    }
+
+    return validatorAddress;
+  }
+
+  function numberValidatorsInCurrentSet() external view returns (uint256) {
+    uint256 numberValidators;
+    assembly {
+      let success := staticcall(
+        5000,
+        0xf9,
+        0,
+        0,
+        0,
+        0
+      )
+      let returnData := mload(0x40)
+      returndatacopy(returnData, 0, 32)
+      numberValidators := mload(returnData)
+    }
+
+    return numberValidators;
+  }
+
   /**
    * @notice Returns validator information.
    * @param account The account that registered the validator.

packages/protocol/truffle.js

@@ -38,6 +38,7 @@ const networks = {
     ...defaultConfig,
     from: DEVELOPMENT_FROM,
     gasPrice: 0,
+    gas: 7000000,
     defaultBalance: 1000000,
     mnemonic: 'concert load couple harbor equip island argue ramp clarify fence smart topic',
   },