Reserve supports multiple exchanges

packages/protocol/contracts/stability/Reserve.sol

@@ -55,6 +55,8 @@ contract Reserve is
   uint256 public frozenReserveGoldStartDay;
   uint256 public frozenReserveGoldDays;
 
+  mapping(address => bool) public isExchangeSpender;
+
   event TobinTaxStalenessThresholdSet(uint256 value);
   event DailySpendingRatioSet(uint256 ratio);
   event TokenAdded(address indexed token);
@@ -67,6 +69,8 @@ contract Reserve is
   event ReserveGoldTransferred(address indexed spender, address indexed to, uint256 value);
   event TobinTaxSet(uint256 value);
   event TobinTaxReserveRatioSet(uint256 value);
+  event ExchangeSpenderAdded(address indexed exchangeSpender);
+  event ExchangeSpenderRemoved(address indexed exchangeSpender);
 
   modifier isStableToken(address token) {
     require(isToken[token], "token addr was never registered");
@@ -78,7 +82,7 @@ contract Reserve is
    * @return The storage, major, minor, and patch version of the contract.
    */
   function getVersionNumber() external pure returns (uint256, uint256, uint256, uint256) {
-    return (1, 1, 1, 0);
+    return (1, 1, 2, 0);
   }
 
   function() external payable {} // solhint-disable no-empty-blocks
@@ -306,6 +310,16 @@ contract Reserve is
     emit SpenderRemoved(spender);
   }
 
+  function addExchangeSpender(address spender) external onlyOwner {
+    isExchangeSpender[spender] = true;
+    emit ExchangeSpenderAdded(spender);
+  }
+
+  function removeExchangeSpender(address spender) external onlyOwner {
+    isExchangeSpender[spender] = false;
+    emit ExchangeSpenderRemoved(spender);
+  }
+
   /**
    * @notice Transfer gold to a whitelisted address subject to reserve spending limits.
    * @param to The address that will receive the gold.
@@ -347,9 +361,12 @@ contract Reserve is
    */
   function transferExchangeGold(address payable to, uint256 value)
     external
-    onlyRegisteredContract(EXCHANGE_REGISTRY_ID)
-    returns (bool)
+    returns (
+      // onlyRegisteredContract(EXCHANGE_REGISTRY_ID)
+      bool
+    )
   {
+    require(isExchangeSpender[msg.sender], "can't send to a non-exchange");
     return _transferGold(to, value);
   }
 

packages/protocol/migrations/08_reserve.ts

@@ -80,5 +80,7 @@ module.exports = deploymentForCoreContract<ReserveInstance>(
     >(CeloContractName.ReserveSpenderMultiSig, artifacts)
     console.info(`Marking ${reserveSpenderMultiSig.address} as a reserve spender`)
     await reserve.addSpender(reserveSpenderMultiSig.address)
+
+    // await reserve.addExchangeSpender(exchange?)
   }
 )

packages/protocol/test/stability/reserve.ts

@@ -7,13 +7,13 @@ import {
 } from '@celo/protocol/lib/test-utils'
 import { fromFixed, toFixed } from '@celo/utils/lib/fixidity'
 import BigNumber from 'bignumber.js'
-import BN = require('bn.js')
 import {
   MockSortedOraclesInstance,
   MockStableTokenInstance,
   RegistryInstance,
   ReserveInstance,
 } from 'types'
+import BN = require('bn.js')
 
 const Registry: Truffle.Contract<RegistryInstance> = artifacts.require('Registry')
 const Reserve: Truffle.Contract<ReserveInstance> = artifacts.require('Reserve')
@@ -48,6 +48,7 @@ contract('Reserve', (accounts: string[]) => {
     mockSortedOracles = await MockSortedOracles.new()
     await registry.setAddressFor(CeloContractName.SortedOracles, mockSortedOracles.address)
     await registry.setAddressFor(CeloContractName.Exchange, exchangeAddress)
+    // await reserve.transferExchangeGold(nonOwner, aValue, { from: exchangeAddress })
     await reserve.initialize(
       registry.address,
       aTobinTaxStalenessThreshold,
@@ -283,6 +284,42 @@ contract('Reserve', (accounts: string[]) => {
     })
   })
 
+  describe('addExchangeSpender & removeExchangeSpender', () => {
+    it('emits on add', async () => {
+      const addExchangeSpenderTx = await reserve.addExchangeSpender(exchangeAddress)
+
+      const addExchangeSpenderTxLogs = addExchangeSpenderTx.logs.filter(
+        (x) => x.event === 'ExchangeSpenderAdded'
+      )
+      assert(addExchangeSpenderTxLogs.length === 1, 'Did not receive event')
+    })
+
+    it('emits on remove', async () => {
+      const addExchangeSpenderTx = await reserve.removeExchangeSpender(exchangeAddress)
+
+      const addExchangeSpenderTxLogs = addExchangeSpenderTx.logs.filter(
+        (x) => x.event === 'ExchangeSpenderRemoved'
+      )
+      assert(addExchangeSpenderTxLogs.length === 1, 'Did not receive event')
+    })
+  })
+
+  describe('addSpender & removeSpender', () => {
+    it('emits on add', async () => {
+      const addSpenderTx = await reserve.addSpender(spender)
+
+      const addExchangeSpenderTxLogs = addSpenderTx.logs.filter((x) => x.event === 'SpenderAdded')
+      assert(addExchangeSpenderTxLogs.length === 1, 'Did not receive event')
+    })
+
+    it('emits on remove', async () => {
+      const addSpenderTx = await reserve.removeSpender(spender)
+
+      const addExchangeSpenderTxLogs = addSpenderTx.logs.filter((x) => x.event === 'SpenderRemoved')
+      assert(addExchangeSpenderTxLogs.length === 1, 'Did not receive event')
+    })
+  })
+
   describe('#transferExchangeGold()', () => {
     const aValue = 10000
     let otherReserveAddress: string = ''
@@ -291,6 +328,7 @@ contract('Reserve', (accounts: string[]) => {
       await web3.eth.sendTransaction({ to: reserve.address, value: aValue, from: accounts[0] })
       await reserve.addSpender(spender)
       await reserve.addOtherReserveAddress(otherReserveAddress)
+      await reserve.addExchangeSpender(exchangeAddress)
     })
 
     it('should allow a exchange to call transferExchangeGold', async () => {
@@ -305,6 +343,11 @@ contract('Reserve', (accounts: string[]) => {
       await assertRevert(reserve.transferExchangeGold(nonOwner, aValue, { from: nonOwner }))
     })
 
+    it('should not allow removed removed exchange spender addresses to call transferExchangeGold', async () => {
+      await reserve.removeExchangeSpender(exchangeAddress)
+      await assertRevert(reserve.transferExchangeGold(nonOwner, aValue, { from: nonOwner }))
+    })
+
     it('should not allow freezing more gold than is available', async () => {
       await assertRevert(reserve.setFrozenGold(aValue + 1, 1))
     })