@0x/contracts-extensions: Maximum gas price contract

contracts/extensions/CHANGELOG.json

@@ -1,4 +1,13 @@
 [
+    {
+        "version": "6.2.0",
+        "changes": [
+            {
+                "note": "Add MaximumGasPrice contract, tooling, and unit tests",
+                "pr": 2511
+            }
+        ]
+    },
     {
         "timestamp": 1583220306,
         "version": "6.1.5",

contracts/extensions/contracts/src/MaximumGasPrice.sol

@@ -0,0 +1,52 @@
+/*
+
+  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 ^0.5.16;
+pragma experimental ABIEncoderV2;
+
+
+contract MaximumGasPrice {
+    // 20 Gwei
+    uint256 constant private DEFAULT_MAX_GAS_PRICE = 20 * (10 ** 9);
+
+    /// @dev Checks that the current transaction's gas price is less than
+    ///      the default maximum value of 20 Gwei.
+    function checkGasPrice()
+        external
+        view
+    {
+        require(
+            tx.gasprice <= DEFAULT_MAX_GAS_PRICE,
+            "MaximumGasPrice/GAS_PRICE_EXCEEDS_20_GWEI"
+        );
+    }
+
+    /// @dev Checks that the current transaction's gas price is less than
+    ///      the specified maximum value.
+    /// @param data Encodes the maximum gas price.
+    function checkGasPrice(bytes calldata data)
+        external
+        view
+    {
+        (uint256 maxGasPrice) = abi.decode(data, (uint256));
+        require(
+            tx.gasprice <= maxGasPrice,
+            "MaximumGasPrice/GAS_PRICE_EXCEEDS_MAXIMUM"
+        );
+    }
+}

contracts/extensions/package.json

@@ -38,7 +38,7 @@
         "docs:json": "typedoc --excludePrivate --excludeExternals --excludeProtected --ignoreCompilerErrors --target ES5 --tsconfig typedoc-tsconfig.json --json $JSON_FILE_PATH $PROJECT_FILES"
     },
     "config": {
-        "abis": "./test/generated-artifacts/@(LibAssetDataTransfer|LibAssetDataTransferRichErrors|LibWethUtilsRichErrors|MixinWethUtils).json",
+        "abis": "./test/generated-artifacts/@(LibAssetDataTransfer|LibAssetDataTransferRichErrors|LibWethUtilsRichErrors|MaximumGasPrice|MixinWethUtils).json",
         "abis:comment": "This list is auto-generated by contracts-gen. Don't edit manually."
     },
     "repository": {

contracts/extensions/src/artifacts.ts

@@ -8,9 +8,11 @@ import { ContractArtifact } from 'ethereum-types';
 import * as LibAssetDataTransfer from '../generated-artifacts/LibAssetDataTransfer.json';
 import * as LibAssetDataTransferRichErrors from '../generated-artifacts/LibAssetDataTransferRichErrors.json';
 import * as LibWethUtilsRichErrors from '../generated-artifacts/LibWethUtilsRichErrors.json';
+import * as MaximumGasPrice from '../generated-artifacts/MaximumGasPrice.json';
 import * as MixinWethUtils from '../generated-artifacts/MixinWethUtils.json';
 export const artifacts = {
     LibAssetDataTransfer: LibAssetDataTransfer as ContractArtifact,
+    MaximumGasPrice: MaximumGasPrice as ContractArtifact,
     MixinWethUtils: MixinWethUtils as ContractArtifact,
     LibAssetDataTransferRichErrors: LibAssetDataTransferRichErrors as ContractArtifact,
     LibWethUtilsRichErrors: LibWethUtilsRichErrors as ContractArtifact,

contracts/extensions/src/index.ts

@@ -29,3 +29,4 @@ export {
     TupleDataItem,
     StateMutability,
 } from 'ethereum-types';
+export * from './max_gas_price_utils';

contracts/extensions/src/max_gas_price_utils.ts

@@ -0,0 +1,44 @@
+import { constants } from '@0x/contracts-test-utils';
+import { assetDataUtils } from '@0x/order-utils';
+import { StaticCallAssetData } from '@0x/types';
+import { AbiEncoder, BigNumber } from '@0x/utils';
+
+const maxGasPriceEncoder = AbiEncoder.create([{ name: 'maxGasPrice', type: 'uint256' }]);
+const customGasPriceEncoder = AbiEncoder.createMethod('checkGasPrice', [{ name: 'data', type: 'bytes' }]);
+const defaultGasPriceEncoder = AbiEncoder.createMethod('checkGasPrice', []);
+
+const ONE_GWEI = new BigNumber(10 ** 9);
+export const TWENTY_GWEI = ONE_GWEI.times(20);
+
+/**
+ * Encodes the given stop limit data parameters into StaticCall asset data so that it can be used
+ * in a 0x order.
+ */
+export function encodeMaxGasPriceStaticCallData(maxGasPriceContractAddress: string, maxGasPrice?: BigNumber): string {
+    const staticCallData =
+        maxGasPrice === undefined
+            ? defaultGasPriceEncoder.encode({})
+            : customGasPriceEncoder.encode({
+                  data: maxGasPriceEncoder.encode({ maxGasPrice }),
+              });
+    return assetDataUtils.encodeStaticCallAssetData(
+        maxGasPriceContractAddress,
+        staticCallData,
+        constants.KECCAK256_NULL,
+    );
+}
+
+/**
+ * Decodes the maxGasPrice StaticCall asset data.
+ */
+export function decodeMaxGasPriceStaticCallData(assetData: string): BigNumber {
+    // tslint:disable-next-line:no-unnecessary-type-assertion
+    const { staticCallData } = assetDataUtils.decodeAssetDataOrThrow(assetData) as StaticCallAssetData;
+    try {
+        const { maxGasPrice } = maxGasPriceEncoder.decode(customGasPriceEncoder.strictDecode<string>(staticCallData));
+        return maxGasPrice;
+    } catch (e) {
+        defaultGasPriceEncoder.strictDecode(staticCallData);
+        return TWENTY_GWEI;
+    }
+}

contracts/extensions/src/wrappers.ts

@@ -6,4 +6,5 @@
 export * from '../generated-wrappers/lib_asset_data_transfer';
 export * from '../generated-wrappers/lib_asset_data_transfer_rich_errors';
 export * from '../generated-wrappers/lib_weth_utils_rich_errors';
+export * from '../generated-wrappers/maximum_gas_price';
 export * from '../generated-wrappers/mixin_weth_utils';

contracts/extensions/test/artifacts.ts

@@ -8,9 +8,11 @@ import { ContractArtifact } from 'ethereum-types';
 import * as LibAssetDataTransfer from '../test/generated-artifacts/LibAssetDataTransfer.json';
 import * as LibAssetDataTransferRichErrors from '../test/generated-artifacts/LibAssetDataTransferRichErrors.json';
 import * as LibWethUtilsRichErrors from '../test/generated-artifacts/LibWethUtilsRichErrors.json';
+import * as MaximumGasPrice from '../test/generated-artifacts/MaximumGasPrice.json';
 import * as MixinWethUtils from '../test/generated-artifacts/MixinWethUtils.json';
 export const artifacts = {
     LibAssetDataTransfer: LibAssetDataTransfer as ContractArtifact,
+    MaximumGasPrice: MaximumGasPrice as ContractArtifact,
     MixinWethUtils: MixinWethUtils as ContractArtifact,
     LibAssetDataTransferRichErrors: LibAssetDataTransferRichErrors as ContractArtifact,
     LibWethUtilsRichErrors: LibWethUtilsRichErrors as ContractArtifact,

contracts/extensions/test/max_gas_price_test.ts

@@ -0,0 +1,71 @@
+import { blockchainTests, constants, expect, getRandomInteger } from '@0x/contracts-test-utils';
+import { AbiEncoder } from '@0x/utils';
+
+import {
+    decodeMaxGasPriceStaticCallData,
+    encodeMaxGasPriceStaticCallData,
+    TWENTY_GWEI,
+} from '../src/max_gas_price_utils';
+
+import { artifacts } from './artifacts';
+import { MaximumGasPriceContract } from './wrappers';
+
+blockchainTests.resets('MaximumGasPrice unit tests', env => {
+    let maxGasPriceContract: MaximumGasPriceContract;
+    const maxGasPriceEncoder = AbiEncoder.create([{ name: 'maxGasPrice', type: 'uint256' }]);
+
+    before(async () => {
+        maxGasPriceContract = await MaximumGasPriceContract.deployFrom0xArtifactAsync(
+            artifacts.MaximumGasPrice,
+            env.provider,
+            env.txDefaults,
+            artifacts,
+        );
+    });
+
+    describe('Contract functionality', () => {
+        it('does not revert if tx.gasprice < default maximum', async () => {
+            await maxGasPriceContract.checkGasPrice1().callAsync({ gasPrice: TWENTY_GWEI.minus(1) });
+        });
+        it('does not revert if tx.gasprice = default maximum', async () => {
+            await maxGasPriceContract.checkGasPrice1().callAsync({ gasPrice: TWENTY_GWEI });
+        });
+        it('reverts if tx.gasPrice > default maximum', async () => {
+            const tx = maxGasPriceContract.checkGasPrice1().callAsync({ gasPrice: TWENTY_GWEI.plus(1) });
+            return expect(tx).to.revertWith('MaximumGasPrice/GAS_PRICE_EXCEEDS_20_GWEI');
+        });
+        it('does not revert if tx.gasprice < custom maximum', async () => {
+            const maxGasPrice = getRandomInteger(0, TWENTY_GWEI.times(2));
+            await maxGasPriceContract
+                .checkGasPrice2(maxGasPriceEncoder.encode({ maxGasPrice }))
+                .callAsync({ gasPrice: maxGasPrice.minus(1) });
+        });
+        it('does not revert if tx.gasprice = default maximum', async () => {
+            const maxGasPrice = getRandomInteger(0, TWENTY_GWEI.times(2));
+            await maxGasPriceContract
+                .checkGasPrice2(maxGasPriceEncoder.encode({ maxGasPrice }))
+                .callAsync({ gasPrice: maxGasPrice });
+        });
+        it('reverts if tx.gasPrice > default maximum', async () => {
+            const maxGasPrice = getRandomInteger(0, TWENTY_GWEI.times(2));
+            const tx = maxGasPriceContract
+                .checkGasPrice2(maxGasPriceEncoder.encode({ maxGasPrice }))
+                .callAsync({ gasPrice: maxGasPrice.plus(1) });
+            return expect(tx).to.revertWith('MaximumGasPrice/GAS_PRICE_EXCEEDS_MAXIMUM');
+        });
+    });
+
+    describe('Data encoding/decoding tools', () => {
+        it('correctly decodes default maximum gas price', async () => {
+            const encoded = encodeMaxGasPriceStaticCallData(maxGasPriceContract.address);
+            const decoded = decodeMaxGasPriceStaticCallData(encoded);
+            expect(decoded).to.bignumber.equal(TWENTY_GWEI);
+        });
+        it('correctly decodes custom maximum gas price', async () => {
+            const maxGasPrice = getRandomInteger(0, constants.MAX_UINT256);
+            const encoded = encodeMaxGasPriceStaticCallData(maxGasPriceContract.address, maxGasPrice);
+            const decoded = decodeMaxGasPriceStaticCallData(encoded);
+            expect(decoded).to.bignumber.equal(maxGasPrice);
+        });
+    });
+});

contracts/extensions/test/wrappers.ts

@@ -6,4 +6,5 @@
 export * from '../test/generated-wrappers/lib_asset_data_transfer';
 export * from '../test/generated-wrappers/lib_asset_data_transfer_rich_errors';
 export * from '../test/generated-wrappers/lib_weth_utils_rich_errors';
+export * from '../test/generated-wrappers/maximum_gas_price';
 export * from '../test/generated-wrappers/mixin_weth_utils';

contracts/extensions/tsconfig.json

@@ -6,10 +6,12 @@
         "generated-artifacts/LibAssetDataTransfer.json",
         "generated-artifacts/LibAssetDataTransferRichErrors.json",
         "generated-artifacts/LibWethUtilsRichErrors.json",
+        "generated-artifacts/MaximumGasPrice.json",
         "generated-artifacts/MixinWethUtils.json",
         "test/generated-artifacts/LibAssetDataTransfer.json",
         "test/generated-artifacts/LibAssetDataTransferRichErrors.json",
         "test/generated-artifacts/LibWethUtilsRichErrors.json",
+        "test/generated-artifacts/MaximumGasPrice.json",
         "test/generated-artifacts/MixinWethUtils.json"
     ],
     "exclude": ["./deploy/solc/solc_bin"]