Support token migration (#224)

* Filter transfer event in token swap in Oracle
* Support token swap in monitor

commons/constants.js

@@ -17,8 +17,11 @@ const FEE_MANAGER_MODE = {
   UNDEFINED: 'UNDEFINED'
 }
 
+const ZERO_ADDRESS = '0x0000000000000000000000000000000000000000'
+
 module.exports = {
   BRIDGE_MODES,
   ERC_TYPES,
-  FEE_MANAGER_MODE
+  FEE_MANAGER_MODE,
+  ZERO_ADDRESS
 }

contracts

@@ -1 +1 @@
-Subproject commit 39910b771b1a93a10db829a0b3dddd074c9e1b4e
+Subproject commit cc7718284d8a35cf74f6ec6847fd7dc7ed1ca885

monitor/utils/events.js

@@ -11,7 +11,8 @@ const {
   ERC20_ABI,
   ERC677_BRIDGE_TOKEN_ABI,
   getTokenType,
-  getPastEvents
+  getPastEvents,
+  ZERO_ADDRESS
 } = require('../../commons')
 const { normalizeEventInformation } = require('./message')
 
@@ -87,7 +88,7 @@ async function main(mode) {
   })).map(normalizeEvent)
   if (isExternalErc20) {
     logger.debug("calling erc20Contract.getPastEvents('Transfer')")
-    const transferEvents = (await getPastEvents(erc20Contract, {
+    let transferEvents = (await getPastEvents(erc20Contract, {
       event: 'Transfer',
       fromBlock: MONITOR_FOREIGN_START_BLOCK,
       toBlock: foreignBlockNumber,
@@ -96,8 +97,47 @@ async function main(mode) {
       }
     })).map(normalizeEvent)
 
+    let directTransfers = transferEvents
+    const tokensSwappedAbiExists = FOREIGN_ABI.filter(e => e.type === 'event' && e.name === 'TokensSwapped')[0]
+    if (tokensSwappedAbiExists) {
+      const tokensSwappedEvents = await getPastEvents(foreignBridge, {
+        event: 'TokensSwapped',
+        fromBlock: MONITOR_FOREIGN_START_BLOCK,
+        toBlock: foreignBlockNumber
+      })
+
+      // Get token swap events emitted by foreign bridge
+      const bridgeTokensSwappedEvents = tokensSwappedEvents.filter(e => e.address === COMMON_FOREIGN_BRIDGE_ADDRESS)
+
+      // Get transfer events for each previous erc20
+      const uniqueTokenAddresses = [...new Set(bridgeTokensSwappedEvents.map(e => e.returnValues.from))]
+      await Promise.all(
+        uniqueTokenAddresses.map(async tokenAddress => {
+          const previousERC20 = new web3Foreign.eth.Contract(ERC20_ABI, tokenAddress)
+
+          const previousTransferEvents = (await getPastEvents(previousERC20, {
+            event: 'Transfer',
+            fromBlock: MONITOR_FOREIGN_START_BLOCK,
+            toBlock: foreignBlockNumber,
+            options: {
+              filter: { to: COMMON_FOREIGN_BRIDGE_ADDRESS }
+            }
+          })).map(normalizeEvent)
+          transferEvents = [...previousTransferEvents, ...transferEvents]
+        })
+      )
+
+      // filter transfer that is part of a token swap
+      directTransfers = transferEvents.filter(
+        e =>
+          bridgeTokensSwappedEvents.findIndex(
+            t => t.transactionHash === e.referenceTx && e.recipient === ZERO_ADDRESS
+          ) === -1
+      )
+    }
+
     // Get transfer events that didn't have a UserRequestForAffirmation event in the same transaction
-    const directTransfers = transferEvents.filter(
+    directTransfers = directTransfers.filter(
       e => foreignToHomeRequests.findIndex(t => t.referenceTx === e.referenceTx) === -1
     )
 

oracle/src/events/processTransfers/index.js

@@ -1,7 +1,7 @@
 require('../../../env')
 const promiseLimit = require('promise-limit')
 const { HttpListProviderError } = require('http-list-provider')
-const { BRIDGE_VALIDATORS_ABI } = require('../../../../commons')
+const { BRIDGE_VALIDATORS_ABI, ZERO_ADDRESS } = require('../../../../commons')
 const rootLogger = require('../../services/logger')
 const { web3Home, web3Foreign } = require('../../services/web3')
 const { AlreadyProcessedError, AlreadySignedError, InvalidValidatorError } = require('../../utils/errors')
@@ -17,7 +17,9 @@ function processTransfersBuilder(config) {
   const userRequestForAffirmationAbi = config.foreignBridgeAbi.filter(
     e => e.type === 'event' && e.name === 'UserRequestForAffirmation'
   )[0]
+  const tokensSwappedAbi = config.foreignBridgeAbi.filter(e => e.type === 'event' && e.name === 'TokensSwapped')[0]
   const userRequestForAffirmationHash = web3Home.eth.abi.encodeEventSignature(userRequestForAffirmationAbi)
+  const tokensSwappedHash = tokensSwappedAbi ? web3Home.eth.abi.encodeEventSignature(tokensSwappedAbi) : '0x'
 
   return async function processTransfers(transfers) {
     const txToSend = []
@@ -42,6 +44,7 @@ function processTransfersBuilder(config) {
         logger.info({ from, value }, `Processing transfer ${transfer.transactionHash}`)
 
         const receipt = await web3Foreign.eth.getTransactionReceipt(transfer.transactionHash)
+
         const existsAffirmationEvent = receipt.logs.some(
           e => e.address === config.foreignBridgeAddress && e.topics[0] === userRequestForAffirmationHash
         )
@@ -55,6 +58,17 @@ function processTransfersBuilder(config) {
           return
         }
 
+        const existsTokensSwappedEvent = tokensSwappedAbi
+          ? receipt.logs.some(e => e.address === config.foreignBridgeAddress && e.topics[0] === tokensSwappedHash)
+          : false
+
+        if (from === ZERO_ADDRESS && existsTokensSwappedEvent) {
+          logger.info(
+            `Transfer event discarded because token swap is detected in transaction ${transfer.transactionHash}`
+          )
+          return
+        }
+
         let gasEstimate
         try {
           logger.debug('Estimate gas')