104 lines
3.5 KiB
Solidity
104 lines
3.5 KiB
Solidity
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/*
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Copyright 2020 ZeroEx Intl.
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Licensed under the Apache License, Version 2.0 (the "License");
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you may not use this file except in compliance with the License.
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You may obtain a copy of the License at
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http://www.apache.org/licenses/LICENSE-2.0
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Unless required by applicable law or agreed to in writing, software
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distributed under the License is distributed on an "AS IS" BASIS,
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WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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See the License for the specific language governing permissions and
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limitations under the License.
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*/
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pragma solidity ^0.5.9;
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pragma experimental ABIEncoderV2;
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import "@0x/contracts-erc20/contracts/src/interfaces/IERC20Token.sol";
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import "@0x/contracts-erc20/contracts/src/LibERC20Token.sol";
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import "@0x/contracts-exchange-libs/contracts/src/IWallet.sol";
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import "@0x/contracts-utils/contracts/src/DeploymentConstants.sol";
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import "../interfaces/IERC20Bridge.sol";
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import "../interfaces/IBalancerPool.sol";
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contract CreamBridge is
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IERC20Bridge,
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IWallet,
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DeploymentConstants
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{
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/// @dev Callback for `IERC20Bridge`. Tries to buy `amount` of
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/// `toTokenAddress` tokens by selling the entirety of the `fromTokenAddress`
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/// token encoded in the bridge data, then transfers the bought
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/// tokens to `to`.
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/// @param toTokenAddress The token to buy and transfer to `to`.
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/// @param from The maker (this contract).
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/// @param to The recipient of the bought tokens.
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/// @param amount Minimum amount of `toTokenAddress` tokens to buy.
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/// @param bridgeData The abi-encoded addresses of the "from" token and Balancer pool.
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/// @return success The magic bytes if successful.
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function bridgeTransferFrom(
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address toTokenAddress,
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address from,
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address to,
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uint256 amount,
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bytes calldata bridgeData
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)
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external
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returns (bytes4 success)
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{
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// Decode the bridge data.
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(address fromTokenAddress, address poolAddress) = abi.decode(
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bridgeData,
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(address, address)
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);
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require(toTokenAddress != fromTokenAddress, "CreamBridge/INVALID_PAIR");
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uint256 fromTokenBalance = IERC20Token(fromTokenAddress).balanceOf(address(this));
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// Grant an allowance to the exchange to spend `fromTokenAddress` token.
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LibERC20Token.approveIfBelow(fromTokenAddress, poolAddress, fromTokenBalance);
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// Sell all of this contract's `fromTokenAddress` token balance.
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(uint256 boughtAmount,) = IBalancerPool(poolAddress).swapExactAmountIn(
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fromTokenAddress, // tokenIn
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fromTokenBalance, // tokenAmountIn
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toTokenAddress, // tokenOut
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amount, // minAmountOut
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uint256(-1) // maxPrice
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);
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// Transfer the converted `toToken`s to `to`.
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LibERC20Token.transfer(toTokenAddress, to, boughtAmount);
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emit ERC20BridgeTransfer(
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fromTokenAddress,
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toTokenAddress,
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fromTokenBalance,
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boughtAmount,
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from,
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to
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);
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return BRIDGE_SUCCESS;
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}
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/// @dev `SignatureType.Wallet` callback, so that this bridge can be the maker
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/// and sign for itself in orders. Always succeeds.
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/// @return magicValue Magic success bytes, always.
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function isValidSignature(
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bytes32,
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bytes calldata
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)
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external
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view
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returns (bytes4 magicValue)
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{
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return LEGACY_WALLET_MAGIC_VALUE;
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}
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}
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