Adding synthetix staking rewards protocol;

contracts/connectors/synthetix.sol

@@ -0,0 +1,85 @@
+pragma solidity ^0.6.0;
+
+// import files from common directory
+import { Stores } from "../common/stores.sol";
+// import { DSMath } from "../common/math.sol";
+import { TokenInterface } from "../common/interfaces.sol";
+
+interface IStakingRewards {
+  function stake(uint256 amount) public;
+  function exit() external;
+}
+
+contract Helper is Stores {
+  function getSynthetixStakingAddr(address token) internal view returns(address){
+    if (token == address(0x075b1bb99792c9E1041bA13afEf80C91a1e70fB3)){
+      return 0x13c1542a468319688b89e323fe9a3be3a90ebb27;
+    }else if (token == address(0xC25a3A3b969415c80451098fa907EC722572917F)){
+      return 0xdcb6a51ea3ca5d3fd898fd6564757c7aaec3ca92;
+    }else{
+      revert("token-not-found");
+    }
+  }
+}
+
+contract SynthetixStakingRewardsProtocol is Helper {
+
+  // Events
+  event LogStake(
+    address stakeAddr,
+    uint256 stakeAmt
+  );
+  event LogExit(
+    address stakeAddr
+  );
+
+  /**
+  * @dev Stake Token.
+  * @param stakeAddr staking token address.
+  * @param stakeAmt staking token amount.
+  */
+  function stake(
+    address stakeAddr,
+    uint stakeAmt,
+    uint getId,
+  ) external {
+    uint _stakeAmt = getUint(getId, stakeAmt);
+    IStakingRewards rewardPool = IStakingRewards(getSynthetixStakingAddr(stakeAddr));
+    TokenInterface _stakeToken = TokenInterface(stakeAddr);
+    _stakeAmt = _stakeAmt == uint(-1) ? _stakeToken.balanceOf(address(this)) : _stakeAmt;
+    _stakeToken.approve(address(rewardPool), _stakeAmt);
+
+    rewardPool.stake(_stakeAmt);
+
+    emit LogStake(address(this), _stakeAmt);
+    bytes32 _eventCode = keccak256("LogStake(address,uint256)");
+    bytes memory _eventParam = abi.encode(stakeAddr, _stakeAmt);
+    emitEvent(_eventCode, _eventParam);
+  }
+
+  /**
+  * @dev Exit Token.
+  * @param token token address.
+  * @param amt token amount.
+  * @param unitAmt unit amount of curve_amt/token_amt with slippage.
+  * @param getId Get token amount at this ID from `InstaMemory` Contract.
+  * @param setId Set token amount at this ID in `InstaMemory` Contract.
+  */
+  function exit(
+    address stakeAddr
+  ) external {
+    IStakingRewards rewardPool = IStakingRewards(getSynthetixStakingAddr(stakeAddr));
+
+    rewardPool.exit();
+
+    emit LogExit(stakeAddr);
+    bytes32 _eventCode = keccak256("LogExit(address)");
+    bytes memory _eventParam = abi.encode(stakeAddr);
+    emitEvent(_eventCode, _eventParam);
+  }
+
+}
+
+contract ConnectSynthetixStakingRewardsProtocol is SynthetixStakingRewardsProtocol {
+  string public name = "synthetix-staking-v1";
+}