ERC20 watcher based on eth_call (#165)

* Implement eth_call for ERC20 totalSupply.

* Use eth_call for erc20-watcher.

* Implement fallback for ERC20 symbol method call.

* Implement fallback for ERC20 name and totalSupply.

* implement fallback for erc20 decimals method.

* Lint fixes.

Co-authored-by: nabarun <nabarun@deepstacksoft.com>

packages/erc20-watcher/environments/local.toml

@@ -1,6 +1,7 @@
 [server]
   host = "127.0.0.1"
   port = 3001
+  mode = "eth_call"
 
 [database]
   type = "postgres"
@@ -25,6 +26,7 @@
   [upstream.ethServer]
     gqlApiEndpoint = "http://127.0.0.1:8082/graphql"
     gqlPostgraphileEndpoint = "http://127.0.0.1:5000/graphql"
+    rpcProviderEndpoint = "http://127.0.0.1:8545"
 
   [upstream.cache]
     name = "requests"

packages/erc20-watcher/src/artifacts/ERC20NameBytes.json

@@ -0,0 +1,17 @@
+[
+  {
+    "constant": true,
+    "inputs": [],
+    "name": "name",
+    "outputs": [
+      {
+        "internalType": "bytes32",
+        "name": "",
+        "type": "bytes32"
+      }
+    ],
+    "payable": false,
+    "stateMutability": "view",
+    "type": "function"
+  }
+]

packages/erc20-watcher/src/artifacts/ERC20SymbolBytes.json

@@ -0,0 +1,17 @@
+[
+  {
+    "constant": true,
+    "inputs": [],
+    "name": "symbol",
+    "outputs": [
+      {
+        "internalType": "bytes32",
+        "name": "",
+        "type": "bytes32"
+      }
+    ],
+    "payable": false,
+    "stateMutability": "view",
+    "type": "function"
+  }
+]

packages/erc20-watcher/src/entity/Allowance.ts

@@ -21,6 +21,6 @@ export class Allowance {
   @Column('numeric')
   value!: bigint;
 
-  @Column('text')
+  @Column('text', { nullable: true })
   proof!: string;
 }

packages/erc20-watcher/src/entity/Balance.ts

@@ -18,6 +18,6 @@ export class Balance {
   @Column('numeric')
   value!: bigint;
 
-  @Column('text')
+  @Column('text', { nullable: true })
   proof!: string;
 }

packages/erc20-watcher/src/events.ts

@@ -39,11 +39,11 @@ export class EventWatcher {
           if (isWatchedContract) {
             // TODO: Move processing to background task runner.
 
-            const { ethTransactionCidByTxId: { ethHeaderCidByHeaderId: { blockHash } } } = receipt;
+            const { ethTransactionCidByTxId: { ethHeaderCidByHeaderId: { blockHash, blockNumber } } } = receipt;
             await this._indexer.getEvents(blockHash, contractAddress, null);
 
             // Trigger other indexer methods based on event topic.
-            await this._indexer.processEvent(blockHash, contractAddress, receipt, logIndex);
+            await this._indexer.processEvent(blockHash, blockNumber, contractAddress, receipt, logIndex);
           }
         }
       }

packages/erc20-watcher/src/indexer.ts

@@ -4,7 +4,8 @@ import { invert } from 'lodash';
 import { JsonFragment } from '@ethersproject/abi';
 import { DeepPartial } from 'typeorm';
 import JSONbig from 'json-bigint';
-import { ethers } from 'ethers';
+import { BigNumber, ethers } from 'ethers';
+import { BaseProvider } from '@ethersproject/providers';
 import { PubSub } from 'apollo-server-express';
 
 import { EthClient, topictoAddress } from '@vulcanize/ipld-eth-client';
@@ -12,9 +13,12 @@ import { getEventNameTopics, getStorageValue, GetStorageAt, StorageLayout } from
 
 import { Database } from './database';
 import { Event } from './entity/Event';
+import { fetchTokenDecimals, fetchTokenName, fetchTokenSymbol, fetchTokenTotalSupply } from './utils';
 
 const log = debug('vulcanize:indexer');
 
+const ETH_CALL_MODE = 'eth_call';
+
 interface Artifacts {
   abi: JsonFragment[];
   storageLayout: StorageLayout;
@@ -22,7 +26,7 @@ interface Artifacts {
 
 export interface ValueResult {
   value: string | bigint;
-  proof: {
+  proof?: {
     data: string;
   }
 }
@@ -36,7 +40,7 @@ type EventsResult = Array<{
     value?: BigInt;
     __typename: string;
   }
-  proof: string;
+  proof?: string;
 }>
 
 export class Indexer {
@@ -44,12 +48,14 @@ export class Indexer {
   _ethClient: EthClient
   _pubsub: PubSub
   _getStorageAt: GetStorageAt
+  _ethProvider: BaseProvider
 
   _abi: JsonFragment[]
   _storageLayout: StorageLayout
   _contract: ethers.utils.Interface
+  _serverMode: string
 
-  constructor (db: Database, ethClient: EthClient, pubsub: PubSub, artifacts: Artifacts) {
+  constructor (db: Database, ethClient: EthClient, ethProvider: BaseProvider, pubsub: PubSub, artifacts: Artifacts, serverMode: string) {
     assert(db);
     assert(ethClient);
     assert(pubsub);
@@ -62,8 +68,10 @@ export class Indexer {
 
     this._db = db;
     this._ethClient = ethClient;
+    this._ethProvider = ethProvider;
     this._pubsub = pubsub;
     this._getStorageAt = this._ethClient.getStorageAt.bind(this._ethClient);
+    this._serverMode = serverMode;
 
     this._abi = abi;
     this._storageLayout = storageLayout;
@@ -76,10 +84,18 @@ export class Indexer {
   }
 
   async totalSupply (blockHash: string, token: string): Promise<ValueResult> {
-    const result = await this._getStorageValue(blockHash, token, '_totalSupply');
+    let result: ValueResult;
+
+    if (this._serverMode === ETH_CALL_MODE) {
+      const value = await fetchTokenTotalSupply(this._ethProvider, token);
+
+      result = { value };
+    } else {
+      result = await this._getStorageValue(blockHash, token, '_totalSupply');
+    }
 
     // https://github.com/GoogleChromeLabs/jsbi/issues/30#issuecomment-521460510
-    // log(JSONbig.stringify(result, null, 2));
+    log(JSONbig.stringify(result, null, 2));
 
     return result;
   }
@@ -96,9 +112,25 @@ export class Indexer {
     }
 
     log('balanceOf: db miss, fetching from upstream server');
-    const result = await this._getStorageValue(blockHash, token, '_balances', owner);
+    let result: ValueResult;
 
-    // log(JSONbig.stringify(result, null, 2));
+    if (this._serverMode === ETH_CALL_MODE) {
+      const contract = new ethers.Contract(token, this._abi, this._ethProvider);
+      const { block } = await this._ethClient.getBlockByHash(blockHash);
+      const { number } = block;
+      const blockNumber = BigNumber.from(number).toNumber();
+
+      // eth_call doesnt support calling method by blockHash https://eth.wiki/json-rpc/API#the-default-block-parameter
+      const value = await contract.balanceOf(owner, { blockTag: blockNumber });
+
+      result = {
+        value: BigInt(value.toString())
+      };
+    } else {
+      result = await this._getStorageValue(blockHash, token, '_balances', owner);
+    }
+
+    log(JSONbig.stringify(result, null, 2));
 
     const { value, proof } = result;
     await this._db.saveBalance({ blockHash, token, owner, value: BigInt(value), proof: JSONbig.stringify(proof) });
@@ -118,7 +150,21 @@ export class Indexer {
     }
 
     log('allowance: db miss, fetching from upstream server');
-    const result = await this._getStorageValue(blockHash, token, '_allowances', owner, spender);
+    let result: ValueResult;
+
+    if (this._serverMode === ETH_CALL_MODE) {
+      const contract = new ethers.Contract(token, this._abi, this._ethProvider);
+      const { block } = await this._ethClient.getBlockByHash(blockHash);
+      const { number } = block;
+      const blockNumber = BigNumber.from(number).toNumber();
+      const value = await contract.allowance(owner, spender, { blockTag: blockNumber });
+
+      result = {
+        value: BigInt(value.toString())
+      };
+    } else {
+      result = await this._getStorageValue(blockHash, token, '_allowances', owner, spender);
+    }
 
     // log(JSONbig.stringify(result, null, 2));
 
@@ -129,7 +175,15 @@ export class Indexer {
   }
 
   async name (blockHash: string, token: string): Promise<ValueResult> {
-    const result = await this._getStorageValue(blockHash, token, '_name');
+    let result: ValueResult;
+
+    if (this._serverMode === ETH_CALL_MODE) {
+      const value = await fetchTokenName(this._ethProvider, token);
+
+      result = { value };
+    } else {
+      result = await this._getStorageValue(blockHash, token, '_name');
+    }
 
     // log(JSONbig.stringify(result, null, 2));
 
@@ -137,18 +191,35 @@ export class Indexer {
   }
 
   async symbol (blockHash: string, token: string): Promise<ValueResult> {
-    const result = await this._getStorageValue(blockHash, token, '_symbol');
+    let result: ValueResult;
+
+    if (this._serverMode === ETH_CALL_MODE) {
+      const value = await fetchTokenSymbol(this._ethProvider, token);
+
+      result = { value };
+    } else {
+      result = await this._getStorageValue(blockHash, token, '_symbol');
+    }
 
     // log(JSONbig.stringify(result, null, 2));
 
     return result;
   }
 
-  async decimals (): Promise<void> {
+  async decimals (blockHash: string, token: string): Promise<ValueResult> {
-    // Not a state variable, uses hardcoded return value in contract function.
+    let result: ValueResult;
-    // See https://github.com/OpenZeppelin/openzeppelin-contracts/blob/master/contracts/token/ERC20/ERC20.sol#L86
 
-    throw new Error('Not implemented.');
+    if (this._serverMode === ETH_CALL_MODE) {
+      const value = await fetchTokenDecimals(this._ethProvider, token);
+
+      result = { value };
+    } else {
+      // Not a state variable, uses hardcoded return value in contract function.
+      // See https://github.com/OpenZeppelin/openzeppelin-contracts/blob/master/contracts/token/ERC20/ERC20.sol#L86
+      throw new Error('Not implemented.');
+    }
+
+    return result;
   }
 
   async getEvents (blockHash: string, token: string, name: string | null): Promise<EventsResult> {
@@ -206,7 +277,7 @@ export class Indexer {
     return result;
   }
 
-  async triggerIndexingOnEvent (blockHash: string, token: string, receipt: any, logIndex: number): Promise<void> {
+  async triggerIndexingOnEvent (blockHash: string, blockNumber: number, token: string, receipt: any, logIndex: number): Promise<void> {
     const topics = [];
 
     // We only care about the event type for now.
@@ -257,9 +328,9 @@ export class Indexer {
     });
   }
 
-  async processEvent (blockHash: string, token: string, receipt: any, logIndex: number): Promise<void> {
+  async processEvent (blockHash: string, blockNumber: number, token: string, receipt: any, logIndex: number): Promise<void> {
     // Trigger indexing of data based on the event.
-    await this.triggerIndexingOnEvent(blockHash, token, receipt, logIndex);
+    await this.triggerIndexingOnEvent(blockHash, blockNumber, token, receipt, logIndex);
 
     // Also trigger downstream event watcher subscriptions.
     await this.publishEventToSubscribers(blockHash, token, logIndex);

packages/erc20-watcher/src/resolvers.ts

@@ -62,7 +62,7 @@ export const createResolvers = async (indexer: Indexer): Promise<any> => {
 
       decimals: (_: any, { blockHash, token }: { blockHash: string, token: string }) => {
         log('decimals', blockHash, token);
-        return indexer.decimals();
+        return indexer.decimals(blockHash, token);
       },
 
       events: async (_: any, { blockHash, token, name }: { blockHash: string, token: string, name: string }) => {

packages/erc20-watcher/src/server.ts

@@ -7,6 +7,7 @@ import { hideBin } from 'yargs/helpers';
 import debug from 'debug';
 import 'graphql-import-node';
 import { createServer } from 'http';
+import { getDefaultProvider } from 'ethers';
 
 import { getCache } from '@vulcanize/cache';
 import { EthClient } from '@vulcanize/ipld-eth-client';
@@ -37,7 +38,7 @@ export const main = async (): Promise<any> => {
 
   assert(config.server, 'Missing server config');
 
-  const { host, port } = config.server;
+  const { host, port, mode } = config.server;
 
   const { upstream, database: dbConfig } = config;
 
@@ -47,7 +48,7 @@ export const main = async (): Promise<any> => {
   await db.init();
 
   assert(upstream, 'Missing upstream config');
-  const { ethServer: { gqlApiEndpoint, gqlPostgraphileEndpoint }, cache: cacheConfig } = upstream;
+  const { ethServer: { gqlApiEndpoint, gqlPostgraphileEndpoint, rpcProviderEndpoint }, cache: cacheConfig } = upstream;
   assert(gqlApiEndpoint, 'Missing upstream ethServer.gqlApiEndpoint');
   assert(gqlPostgraphileEndpoint, 'Missing upstream ethServer.gqlPostgraphileEndpoint');
 
@@ -58,10 +59,12 @@ export const main = async (): Promise<any> => {
     cache
   });
 
+  const ethProvider = getDefaultProvider(rpcProviderEndpoint);
+
   // Note: In-memory pubsub works fine for now, as each watcher is a single process anyway.
   // Later: https://www.apollographql.com/docs/apollo-server/data/subscriptions/#production-pubsub-libraries
   const pubsub = new PubSub();
-  const indexer = new Indexer(db, ethClient, pubsub, artifacts);
+  const indexer = new Indexer(db, ethClient, ethProvider, pubsub, artifacts, mode);
 
   const eventWatcher = new EventWatcher(ethClient, indexer);
   await eventWatcher.start();

packages/erc20-watcher/src/utils/index.ts

@@ -0,0 +1,110 @@
+import { Contract, utils } from 'ethers';
+import { BaseProvider } from '@ethersproject/providers';
+
+import { abi } from '../artifacts/ERC20.json';
+import ERC20SymbolBytesABI from '../artifacts/ERC20SymbolBytes.json';
+import ERC20NameBytesABI from '../artifacts/ERC20NameBytes.json';
+import { StaticTokenDefinition } from './static-token-definition';
+
+export const fetchTokenSymbol = async (ethProvider: BaseProvider, tokenAddress: string): Promise<string> => {
+  const contract = new Contract(tokenAddress, abi, ethProvider);
+  const contractSymbolBytes = new Contract(tokenAddress, ERC20SymbolBytesABI, ethProvider);
+  let symbolValue = 'unknown';
+
+  // Try types string and bytes32 for symbol.
+  try {
+    const result = await contract.symbol();
+    symbolValue = result;
+  } catch (error) {
+    try {
+      const result = await contractSymbolBytes.symbol();
+
+      // For broken pairs that have no symbol function exposed.
+      if (!isNullEthValue(result)) {
+        symbolValue = utils.parseBytes32String(result);
+      } else {
+        // Try with the static definition.
+        const staticTokenDefinition = StaticTokenDefinition.fromAddress(tokenAddress);
+
+        if (staticTokenDefinition !== null) {
+          symbolValue = staticTokenDefinition.symbol;
+        }
+      }
+    } catch (error) {
+      // symbolValue is unknown if the calls revert.
+    }
+  }
+
+  return symbolValue;
+};
+
+export const fetchTokenName = async (ethProvider: BaseProvider, tokenAddress: string): Promise<string> => {
+  const contract = new Contract(tokenAddress, abi, ethProvider);
+  const contractNameBytes = new Contract(tokenAddress, ERC20NameBytesABI, ethProvider);
+  let nameValue = 'unknown';
+
+  // Try types string and bytes32 for name.
+  try {
+    const result = await contract.name();
+    nameValue = result;
+  } catch (error) {
+    try {
+      const result = await contractNameBytes.name();
+
+      // For broken pairs that have no name function exposed.
+      if (!isNullEthValue(result)) {
+        nameValue = utils.parseBytes32String(result);
+      } else {
+        // Try with the static definition.
+        const staticTokenDefinition = StaticTokenDefinition.fromAddress(tokenAddress);
+
+        if (staticTokenDefinition !== null) {
+          nameValue = staticTokenDefinition.name;
+        }
+      }
+    } catch (error) {
+      // nameValue is unknown if the calls revert.
+    }
+  }
+
+  return nameValue;
+};
+
+export const fetchTokenTotalSupply = async (ethProvider: BaseProvider, tokenAddress: string): Promise<bigint> => {
+  const contract = new Contract(tokenAddress, abi, ethProvider);
+  let totalSupplyValue = null;
+
+  try {
+    const result = await contract.totalSupply();
+    totalSupplyValue = result.toString();
+  } catch (error) {
+    totalSupplyValue = 0;
+  }
+
+  return BigInt(totalSupplyValue);
+};
+
+export const fetchTokenDecimals = async (ethProvider: BaseProvider, tokenAddress: string): Promise<bigint> => {
+  const contract = new Contract(tokenAddress, abi, ethProvider);
+
+  // Try types uint8 for decimals.
+  let decimalValue = null;
+
+  try {
+    const result = await contract.decimals();
+    decimalValue = result.toString();
+  } catch (error) {
+    // Try with the static definition.
+    const staticTokenDefinition = StaticTokenDefinition.fromAddress(tokenAddress);
+
+    if (staticTokenDefinition != null) {
+      return staticTokenDefinition.decimals;
+    }
+  }
+
+  return BigInt(decimalValue);
+};
+
+const isNullEthValue = (value: string): boolean => {
+  return value === '0x0000000000000000000000000000000000000000000000000000000000000001';
+};

packages/erc20-watcher/src/utils/static-token-definition.ts

@@ -0,0 +1,94 @@
+import { utils } from 'ethers';
+
+// Initialize a Token Definition with the attributes.
+export class StaticTokenDefinition {
+  address : string
+  symbol: string
+  name: string
+  decimals: bigint
+
+  // Initialize a Token Definition with its attributes.
+  constructor (address: string, symbol: string, name: string, decimals: bigint) {
+    this.address = address;
+    this.symbol = symbol;
+    this.name = name;
+    this.decimals = decimals;
+  }
+
+  // Get all tokens with a static defintion
+  static getStaticDefinitions (): Array<StaticTokenDefinition> {
+    const staticDefinitions = new Array<StaticTokenDefinition>(6);
+
+    // Add DGD.
+    const tokenDGD = new StaticTokenDefinition(
+      utils.getAddress('0xe0b7927c4af23765cb51314a0e0521a9645f0e2a'),
+      'DGD',
+      'DGD',
+      BigInt(9)
+    );
+    staticDefinitions.push(tokenDGD);
+
+    // Add AAVE.
+    const tokenAAVE = new StaticTokenDefinition(
+      utils.getAddress('0x7fc66500c84a76ad7e9c93437bfc5ac33e2ddae9'),
+      'AAVE',
+      'Aave Token',
+      BigInt(18)
+    );
+    staticDefinitions.push(tokenAAVE);
+
+    // Add LIF.
+    const tokenLIF = new StaticTokenDefinition(
+      utils.getAddress('0xeb9951021698b42e4399f9cbb6267aa35f82d59d'),
+      'LIF',
+      'Lif',
+      BigInt(18)
+    );
+    staticDefinitions.push(tokenLIF);
+
+    // Add SVD.
+    const tokenSVD = new StaticTokenDefinition(
+      utils.getAddress('0xbdeb4b83251fb146687fa19d1c660f99411eefe3'),
+      'SVD',
+      'savedroid',
+      BigInt(18)
+    );
+    staticDefinitions.push(tokenSVD);
+
+    // Add TheDAO.
+    const tokenTheDAO = new StaticTokenDefinition(
+      utils.getAddress('0xbb9bc244d798123fde783fcc1c72d3bb8c189413'),
+      'TheDAO',
+      'TheDAO',
+      BigInt(16)
+    );
+    staticDefinitions.push(tokenTheDAO);
+
+    // Add HPB.
+    const tokenHPB = new StaticTokenDefinition(
+      utils.getAddress('0x38c6a68304cdefb9bec48bbfaaba5c5b47818bb2'),
+      'HPB',
+      'HPBCoin',
+      BigInt(18)
+    );
+    staticDefinitions.push(tokenHPB);
+
+    return staticDefinitions;
+  }
+
+  // Helper for hardcoded tokens.
+  static fromAddress (tokenAddress: string) : StaticTokenDefinition | null {
+    const staticDefinitions = this.getStaticDefinitions();
+
+    // Search the definition using the address.
+    for (let i = 0; i < staticDefinitions.length; i++) {
+      const staticDefinition = staticDefinitions[i];
+      if (utils.getAddress(staticDefinition.address) === utils.getAddress(tokenAddress)) {
+        return staticDefinition;
+      }
+    }
+
+    // If not found, return null.
+    return null;
+  }
+}

packages/ipld-eth-client/src/eth-queries.ts

@@ -56,15 +56,14 @@ query allEthHeaderCids($blockNumber: BigInt) {
 `;
 
 export const getBlockByHash = gql`
-query allEthHeaderCids($blockHash: Bytes32) {
+query block($blockHash: Bytes32) {
-  allEthHeaderCids(condition: { blockHash: $blockHash }) {
+  block(hash: $blockHash) {
-    nodes {
+    number
-      cid
+    hash
-      blockNumber
+    parent {
-      blockHash
+      hash
-      parentHash
-      timestamp
     }
+    timestamp
   }
 }
 `;

packages/uni-info-watcher/src/database.ts

@@ -648,7 +648,7 @@ export class Database {
   async _getPrevEntityVersion<Entity> (repo: Repository<Entity>, findOptions: { [key: string]: any }): Promise<Entity | undefined> {
     assert(findOptions.order.blockNumber);
     const { canonicalBlockNumber, blockHashes } = await this._getBranchInfo(findOptions.where.blockHash);
-    findOptions.where.blockHash = In(blockHashes)
+    findOptions.where.blockHash = In(blockHashes);
     let entity = await repo.findOne(findOptions);
 
     if (!entity) {

packages/uni-watcher/src/events.ts

@@ -47,7 +47,7 @@ export class EventWatcher {
     await this.initEventProcessingOnCompleteHandler();
   }
 
-  async watchBlocksAtChainHead () {
+  async watchBlocksAtChainHead (): Promise<void> {
     log('Started watching upstream blocks...');
     this._subscription = await this._ethClient.watchBlocks(async (value) => {
       const { blockHash, blockNumber, parentHash } = _.get(value, 'data.listen.relatedNode');
@@ -59,7 +59,7 @@ export class EventWatcher {
     });
   }
 
-  async initBlockProcessingOnCompleteHandler () {
+  async initBlockProcessingOnCompleteHandler (): Promise<void> {
     this._jobQueue.onComplete(QUEUE_BLOCK_PROCESSING, async (job) => {
       const { data: { request: { data: { blockHash, blockNumber } } } } = job;
       log(`Job onComplete block ${blockHash} ${blockNumber}`);
@@ -70,7 +70,7 @@ export class EventWatcher {
     });
   }
 
-  async initEventProcessingOnCompleteHandler () {
+  async initEventProcessingOnCompleteHandler (): Promise<void> {
     this._jobQueue.onComplete(QUEUE_EVENT_PROCESSING, async (job) => {
       const { data: { request, failed, state, createdOn } } = job;
 

packages/util/src/config.ts

@@ -12,6 +12,7 @@ export interface Config {
   server: {
     host: string;
     port: number;
+    mode: string;
   };
   database: ConnectionOptions;
   upstream: {
@@ -19,6 +20,7 @@ export interface Config {
     ethServer: {
       gqlApiEndpoint: string;
       gqlPostgraphileEndpoint: string;
+      rpcProviderEndpoint: string
     }
     traceProviderEndpoint: string;
     uniWatcher: {