Read-Only mode in proxy

contracts/staking/contracts/src/ReadOnlyProxy.sol

@@ -0,0 +1,107 @@
+/*
+
+  Copyright 2019 ZeroEx Intl.
+
+  Licensed under the Apache License, Version 2.0 (the "License");
+  you may not use this file except in compliance with the License.
+  You may obtain a copy of the License at
+
+    http://www.apache.org/licenses/LICENSE-2.0
+
+  Unless required by applicable law or agreed to in writing, software
+  distributed under the License is distributed on an "AS IS" BASIS,
+  WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+  See the License for the specific language governing permissions and
+  limitations under the License.
+
+*/
+
+pragma solidity ^0.5.9;
+
+import "./immutable/MixinStorage.sol";
+
+
+contract ReadOnlyProxy is
+    MixinStorage
+{
+
+    /// @dev Executes a read-only call to the staking contract, via `revertDelegateCall`.
+    ///      By routing through `revertDelegateCall` any state changes are reverted.
+    // solhint-disable no-complex-fallback
+    function ()
+        external
+    {
+        address thisAddress = address(this);
+        bytes4 revertDelegateCallSelector = this.revertDelegateCall.selector;
+
+        assembly {
+            // store selector of destination function
+            mstore(0x0, revertDelegateCallSelector)
+
+            // copy calldata to memory
+            calldatacopy(
+                0x4,
+                0x0,
+                calldatasize()
+            )
+
+            // delegate call into staking contract
+            let success := delegatecall(
+                gas,                        // forward all gas
+                thisAddress,                // calling staking contract
+                0x0,                        // start of input (calldata)
+                add(calldatasize(), 4),     // length of input (calldata)
+                0x0,                        // write output over input
+                0                           // length of output is unknown
+            )
+
+            // copy return data to memory and *return*
+            returndatacopy(
+                0x0,
+                0x0,
+                returndatasize()
+            )
+
+            return(0, returndatasize())
+        }
+    }
+
+    /// @dev Executes a delegate call to the staking contract, if it is set.
+    ///      This function always reverts with the return data.
+    function revertDelegateCall()
+        external
+    {
+        address _readOnlyProxyCallee = readOnlyProxyCallee;
+        if (_readOnlyProxyCallee == address(0)) {
+            return;
+        }
+
+        assembly {
+            // copy calldata to memory
+            calldatacopy(
+                0x0,
+                0x4,
+                calldatasize()
+            )
+
+            // delegate call into staking contract
+            let success := delegatecall(
+                gas,                        // forward all gas
+                _readOnlyProxyCallee,       // calling staking contract
+                0x0,                        // start of input (calldata)
+                sub(calldatasize(), 4),     // length of input (calldata)
+                0x0,                        // write output over input
+                0                           // length of output is unknown
+            )
+
+            // copy return data to memory and *revert*
+            returndatacopy(
+                0x0,
+                0x0,
+                returndatasize()
+            )
+
+            revert(0, returndatasize())
+        }
+    }
+}

contracts/staking/contracts/src/StakingProxy.sol

@@ -31,11 +31,13 @@ contract StakingProxy is
 
     /// @dev Constructor.
     /// @param _stakingContract Staking contract to delegate calls to.
-    constructor(address _stakingContract)
+    constructor(address _stakingContract, address _readOnlyProxy)
         public
         MixinStorage()
     {
         stakingContract = _stakingContract;
+        readOnlyProxyCallee = _stakingContract;
+        readOnlyProxy = _readOnlyProxy;
     }
 
     /// @dev Delegates calls to the staking contract, if it is set.
@@ -92,6 +94,7 @@ contract StakingProxy is
         onlyOwner
     {
         stakingContract = _stakingContract;
+        readOnlyProxyCallee = _stakingContract;
         emit StakingContractAttachedToProxy(_stakingContract);
     }
 
@@ -104,4 +107,18 @@ contract StakingProxy is
         stakingContract = NIL_ADDRESS;
         emit StakingContractDetachedFromProxy();
     }
+
+    /// @dev Set read-only mode (state cannot be changed).
+    function setReadOnlyMode(bool readOnlyMode)
+        external
+        onlyOwner
+    {
+        if (readOnlyMode) {
+            stakingContract = readOnlyProxy;
+        } else {
+            stakingContract = readOnlyProxyCallee;
+        }
+
+        emit ReadOnlyModeSet(readOnlyMode);
+    }
 }

contracts/staking/contracts/src/immutable/MixinStorage.sol

@@ -41,6 +41,12 @@ contract MixinStorage is
     // address of staking contract
     address internal stakingContract;
 
+    // address of read-only proxy
+    address internal readOnlyProxy;
+
+    // address for read-only proxy to call
+    address internal readOnlyProxyCallee;
+
     // mapping from Owner to Amount of Active Stake
     // (access using _loadAndSyncBalance or _loadUnsyncedBalance)
     mapping (address => IStructs.StoredBalance) internal activeStakeByOwner;

contracts/staking/contracts/src/interfaces/IStakingProxy.sol

@@ -31,6 +31,11 @@ interface IStakingProxy /* is IStaking */
     /// @dev Emitted by StakingProxy when a staking contract is detached.
     event StakingContractDetachedFromProxy();
 
+    /// @dev Emitted by StakingProxy when read-only mode is set.
+    event ReadOnlyModeSet(
+        bool readOnlyMode
+    );
+
     /// @dev Delegates calls to the staking contract, if it is set.
     // solhint-disable no-complex-fallback
     function ()

contracts/staking/package.json

@@ -37,7 +37,7 @@
     },
     "config": {
         "abis:comment": "This list is auto-generated by contracts-gen. Don't edit manually.",
-        "abis": "./generated-artifacts/@(EthVault|IEthVault|IStaking|IStakingEvents|IStakingPoolRewardVault|IStakingProxy|IStructs|IVaultCore|IWallet|IZrxVault|LibEIP712Hash|LibFixedMath|LibFixedMathRichErrors|LibSafeDowncast|LibSignatureValidator|LibStakingRichErrors|MixinConstants|MixinDeploymentConstants|MixinEthVault|MixinExchangeFees|MixinExchangeManager|MixinScheduler|MixinStake|MixinStakeBalances|MixinStakeStorage|MixinStakingPool|MixinStakingPoolRewardVault|MixinStakingPoolRewards|MixinStorage|MixinVaultCore|MixinZrxVault|Staking|StakingPoolRewardVault|StakingProxy|TestCobbDouglas|TestLibFixedMath|TestStorageLayout|ZrxVault).json"
+        "abis": "./generated-artifacts/@(EthVault|IEthVault|IStaking|IStakingEvents|IStakingPoolRewardVault|IStakingProxy|IStructs|IVaultCore|IWallet|IZrxVault|LibEIP712Hash|LibFixedMath|LibFixedMathRichErrors|LibSafeDowncast|LibSignatureValidator|LibStakingRichErrors|MixinConstants|MixinDeploymentConstants|MixinEthVault|MixinExchangeFees|MixinExchangeManager|MixinScheduler|MixinStake|MixinStakeBalances|MixinStakeStorage|MixinStakingPool|MixinStakingPoolRewardVault|MixinStakingPoolRewards|MixinStorage|MixinVaultCore|MixinZrxVault|ReadOnlyProxy|Staking|StakingPoolRewardVault|StakingProxy|TestCobbDouglas|TestLibFixedMath|TestStorageLayout|ZrxVault).json"
     },
     "repository": {
         "type": "git",

contracts/staking/src/artifacts.ts

@@ -36,6 +36,7 @@ import * as MixinStakingPoolRewardVault from '../generated-artifacts/MixinStakin
 import * as MixinStorage from '../generated-artifacts/MixinStorage.json';
 import * as MixinVaultCore from '../generated-artifacts/MixinVaultCore.json';
 import * as MixinZrxVault from '../generated-artifacts/MixinZrxVault.json';
+import * as ReadOnlyProxy from '../generated-artifacts/ReadOnlyProxy.json';
 import * as Staking from '../generated-artifacts/Staking.json';
 import * as StakingPoolRewardVault from '../generated-artifacts/StakingPoolRewardVault.json';
 import * as StakingProxy from '../generated-artifacts/StakingProxy.json';
@@ -44,6 +45,7 @@ import * as TestLibFixedMath from '../generated-artifacts/TestLibFixedMath.json'
 import * as TestStorageLayout from '../generated-artifacts/TestStorageLayout.json';
 import * as ZrxVault from '../generated-artifacts/ZrxVault.json';
 export const artifacts = {
+    ReadOnlyProxy: ReadOnlyProxy as ContractArtifact,
     Staking: Staking as ContractArtifact,
     StakingProxy: StakingProxy as ContractArtifact,
     MixinExchangeFees: MixinExchangeFees as ContractArtifact,

contracts/staking/src/wrappers.ts

@@ -34,6 +34,7 @@ export * from '../generated-wrappers/mixin_staking_pool_rewards';
 export * from '../generated-wrappers/mixin_storage';
 export * from '../generated-wrappers/mixin_vault_core';
 export * from '../generated-wrappers/mixin_zrx_vault';
+export * from '../generated-wrappers/read_only_proxy';
 export * from '../generated-wrappers/staking';
 export * from '../generated-wrappers/staking_pool_reward_vault';
 export * from '../generated-wrappers/staking_proxy';

contracts/staking/test/catastrophy_test.ts

@@ -0,0 +1,89 @@
+import { ERC20ProxyContract, ERC20Wrapper } from '@0x/contracts-asset-proxy';
+import { DummyERC20TokenContract } from '@0x/contracts-erc20';
+import { blockchainTests, describe, expect, provider, web3Wrapper } from '@0x/contracts-test-utils';
+import { BigNumber } from '@0x/utils';
+import { LogWithDecodedArgs } from 'ethereum-types';
+import * as _ from 'lodash';
+
+import { StakingProxyReadOnlyModeSetEventArgs } from '../src';
+
+import { StakingWrapper } from './utils/staking_wrapper';
+
+// tslint:disable:no-unnecessary-type-assertion
+blockchainTests.resets('Catastrophy Tests', () => {
+    // constants
+    const ZRX_TOKEN_DECIMALS = new BigNumber(18);
+    const ZERO = new BigNumber(0);
+    // tokens & addresses
+    let accounts: string[];
+    let owner: string;
+    let actors: string[];
+    let zrxTokenContract: DummyERC20TokenContract;
+    let erc20ProxyContract: ERC20ProxyContract;
+    // wrappers
+    let stakingWrapper: StakingWrapper;
+    let erc20Wrapper: ERC20Wrapper;
+    // tests
+    before(async () => {
+        // create accounts
+        accounts = await web3Wrapper.getAvailableAddressesAsync();
+        owner = accounts[0];
+        actors = accounts.slice(2, 5);
+        // deploy erc20 proxy
+        erc20Wrapper = new ERC20Wrapper(provider, accounts, owner);
+        erc20ProxyContract = await erc20Wrapper.deployProxyAsync();
+        // deploy zrx token
+        [zrxTokenContract] = await erc20Wrapper.deployDummyTokensAsync(1, ZRX_TOKEN_DECIMALS);
+        await erc20Wrapper.setBalancesAndAllowancesAsync();
+        // deploy staking contracts
+        stakingWrapper = new StakingWrapper(provider, owner, erc20ProxyContract, zrxTokenContract, accounts);
+        await stakingWrapper.deployAndConfigureContractsAsync();
+    });
+
+    describe('Read-Only Mode', () => {
+        it('should be able to change state by default', async () => {
+            // stake some zrx and assert the balance
+            const amountToStake = StakingWrapper.toBaseUnitAmount(10);
+            await stakingWrapper.stakeAsync(actors[0], amountToStake);
+            const activeStakeBalance = await stakingWrapper.getActiveStakeAsync(actors[0]);
+            expect(activeStakeBalance.currentEpochBalance).to.be.bignumber.equal(amountToStake);
+        });
+        it('should not change state when in read-only mode', async () => {
+            // set to read-only mode
+            await stakingWrapper.setReadOnlyModeAsync(true);
+            // try to stake
+            const amountToStake = StakingWrapper.toBaseUnitAmount(10);
+            await stakingWrapper.stakeAsync(actors[0], amountToStake);
+            const activeStakeBalance = await stakingWrapper.getActiveStakeAsync(actors[0]);
+            expect(activeStakeBalance.currentEpochBalance).to.be.bignumber.equal(ZERO);
+        });
+        it('should read values correctly when in read-only mode', async () => {
+            // stake some zrx
+            const amountToStake = StakingWrapper.toBaseUnitAmount(10);
+            await stakingWrapper.stakeAsync(actors[0], amountToStake);
+            // set to read-only mode
+            await stakingWrapper.setReadOnlyModeAsync(true);
+            // read stake balance in read-only mode
+            const activeStakeBalanceReadOnly = await stakingWrapper.getActiveStakeAsync(actors[0]);
+            expect(activeStakeBalanceReadOnly.currentEpochBalance).to.be.bignumber.equal(amountToStake);
+        });
+        it('should exit read-only mode', async () => {
+            // set to read-only mode
+            await stakingWrapper.setReadOnlyModeAsync(true);
+            await stakingWrapper.setReadOnlyModeAsync(false);
+            // try to stake
+            const amountToStake = StakingWrapper.toBaseUnitAmount(10);
+            await stakingWrapper.stakeAsync(actors[0], amountToStake);
+            const activeStakeBalance = await stakingWrapper.getActiveStakeAsync(actors[0]);
+            expect(activeStakeBalance.currentEpochBalance).to.be.bignumber.equal(amountToStake);
+        });
+        it('should emit event when setting read-only mode', async () => {
+            // set to read-only mode
+            const txReceipt = await stakingWrapper.setReadOnlyModeAsync(true);
+            expect(txReceipt.logs.length).to.be.equal(1);
+            const trueLog = txReceipt.logs[0] as LogWithDecodedArgs<StakingProxyReadOnlyModeSetEventArgs>;
+            expect(trueLog.args.readOnlyMode).to.be.true();
+        });
+    });
+});
+// tslint:enable:no-unnecessary-type-assertion

contracts/staking/test/utils/staking_wrapper.ts

@@ -10,6 +10,7 @@ import * as _ from 'lodash';
 import {
     artifacts,
     EthVaultContract,
+    ReadOnlyProxyContract,
     StakingContract,
     StakingPoolRewardVaultContract,
     StakingProxyContract,
@@ -33,6 +34,7 @@ export class StakingWrapper {
     private _zrxVaultContractIfExists?: ZrxVaultContract;
     private _ethVaultContractIfExists?: EthVaultContract;
     private _rewardVaultContractIfExists?: StakingPoolRewardVaultContract;
+    private _readOnlyProxyContractIfExists?: ReadOnlyProxyContract;
     public static toBaseUnitAmount(amount: BigNumber | number): BigNumber {
         const decimals = 18;
         const amountAsBigNumber = typeof amount === 'number' ? new BigNumber(amount) : amount;
@@ -97,6 +99,13 @@ export class StakingWrapper {
         return this._rewardVaultContractIfExists as StakingPoolRewardVaultContract;
     }
     public async deployAndConfigureContractsAsync(): Promise<void> {
+        // deploy read-only proxy
+        this._readOnlyProxyContractIfExists = await ReadOnlyProxyContract.deployFrom0xArtifactAsync(
+            artifacts.ReadOnlyProxy,
+            this._provider,
+            txDefaults,
+            artifacts,
+        );
         // deploy zrx vault
         this._zrxVaultContractIfExists = await ZrxVaultContract.deployFrom0xArtifactAsync(
             artifacts.ZrxVault,
@@ -142,6 +151,7 @@ export class StakingWrapper {
             txDefaults,
             artifacts,
             this._stakingContractIfExists.address,
+            this._readOnlyProxyContractIfExists.address,
         );
         // set staking proxy contract in zrx vault
         await this._zrxVaultContractIfExists.setStakingContract.awaitTransactionSuccessAsync(
@@ -176,6 +186,12 @@ export class StakingWrapper {
             await this._web3Wrapper.sendTransactionAsync(setStakingPoolRewardVaultTxData),
         );
     }
+    public async setReadOnlyModeAsync(readOnlyMode: boolean): Promise<TransactionReceiptWithDecodedLogs> {
+        const txReceipt = await this.getStakingProxyContract().setReadOnlyMode.awaitTransactionSuccessAsync(
+            readOnlyMode,
+        );
+        return txReceipt;
+    }
     public async getEthBalanceAsync(owner: string): Promise<BigNumber> {
         const balance = this._web3Wrapper.getBalanceInWeiAsync(owner);
         return balance;

contracts/staking/tsconfig.json

@@ -34,6 +34,7 @@
         "generated-artifacts/MixinStorage.json",
         "generated-artifacts/MixinVaultCore.json",
         "generated-artifacts/MixinZrxVault.json",
+        "generated-artifacts/ReadOnlyProxy.json",
         "generated-artifacts/Staking.json",
         "generated-artifacts/StakingPoolRewardVault.json",
         "generated-artifacts/StakingProxy.json",