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Diffstat (limited to 'contracts/extensions/contracts/src/DutchAuction/DutchAuction.sol')
| -rw-r--r-- | contracts/extensions/contracts/src/DutchAuction/DutchAuction.sol | 205 |
1 files changed, 205 insertions, 0 deletions
diff --git a/contracts/extensions/contracts/src/DutchAuction/DutchAuction.sol b/contracts/extensions/contracts/src/DutchAuction/DutchAuction.sol new file mode 100644 index 000000000..7631880c0 --- /dev/null +++ b/contracts/extensions/contracts/src/DutchAuction/DutchAuction.sol @@ -0,0 +1,205 @@ +/* + + Copyright 2018 ZeroEx Intl. + + Licensed under the Apache License, Version 2.0 (the "License"); + you may not use this file except in compliance with the License. + You may obtain a copy of the License at + + http://www.apache.org/licenses/LICENSE-2.0 + + Unless required by applicable law or agreed to in writing, software + distributed under the License is distributed on an "AS IS" BASIS, + WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. + See the License for the specific language governing permissions and + limitations under the License. + +*/ + +pragma solidity 0.4.24; +pragma experimental ABIEncoderV2; + +import "@0x/contracts-exchange/contracts/src/interfaces/IExchange.sol"; +import "@0x/contracts-exchange-libs/contracts/src/LibOrder.sol"; +import "@0x/contracts-erc20/contracts/src/interfaces/IERC20Token.sol"; +import "@0x/contracts-utils/contracts/src/LibBytes.sol"; +import "@0x/contracts-utils/contracts/src/SafeMath.sol"; + + +contract DutchAuction is + SafeMath +{ + using LibBytes for bytes; + + // solhint-disable var-name-mixedcase + IExchange internal EXCHANGE; + + struct AuctionDetails { + uint256 beginTimeSeconds; // Auction begin unix timestamp: sellOrder.makerAssetData + uint256 endTimeSeconds; // Auction end unix timestamp: sellOrder.expiryTimeSeconds + uint256 beginAmount; // Auction begin amount: sellOrder.makerAssetData + uint256 endAmount; // Auction end amount: sellOrder.takerAssetAmount + uint256 currentAmount; // Calculated amount given block.timestamp + uint256 currentTimeSeconds; // block.timestamp + } + + constructor (address _exchange) + public + { + EXCHANGE = IExchange(_exchange); + } + + /// @dev Matches the buy and sell orders at an amount given the following: the current block time, the auction + /// start time and the auction begin amount. The sell order is a an order at the lowest amount + /// at the end of the auction. Excess from the match is transferred to the seller. + /// Over time the price moves from beginAmount to endAmount given the current block.timestamp. + /// sellOrder.expiryTimeSeconds is the end time of the auction. + /// sellOrder.takerAssetAmount is the end amount of the auction (lowest possible amount). + /// sellOrder.makerAssetData is the ABI encoded Asset Proxy data with the following data appended + /// buyOrder.makerAssetData is the buyers bid on the auction, must meet the amount for the current block timestamp + /// (uint256 beginTimeSeconds, uint256 beginAmount). + /// This function reverts in the following scenarios: + /// * Auction has not started (auctionDetails.currentTimeSeconds < auctionDetails.beginTimeSeconds) + /// * Auction has expired (auctionDetails.endTimeSeconds < auctionDetails.currentTimeSeconds) + /// * Amount is invalid: Buy order amount is too low (buyOrder.makerAssetAmount < auctionDetails.currentAmount) + /// * Amount is invalid: Invalid begin amount (auctionDetails.beginAmount > auctionDetails.endAmount) + /// * Any failure in the 0x Match Orders + /// @param buyOrder The Buyer's order. This order is for the current expected price of the auction. + /// @param sellOrder The Seller's order. This order is for the lowest amount (at the end of the auction). + /// @param buySignature Proof that order was created by the buyer. + /// @param sellSignature Proof that order was created by the seller. + /// @return matchedFillResults amounts filled and fees paid by maker and taker of matched orders. + function matchOrders( + LibOrder.Order memory buyOrder, + LibOrder.Order memory sellOrder, + bytes memory buySignature, + bytes memory sellSignature + ) + public + returns (LibFillResults.MatchedFillResults memory matchedFillResults) + { + AuctionDetails memory auctionDetails = getAuctionDetails(sellOrder); + // Ensure the auction has not yet started + require( + auctionDetails.currentTimeSeconds >= auctionDetails.beginTimeSeconds, + "AUCTION_NOT_STARTED" + ); + // Ensure the auction has not expired. This will fail later in 0x but we can save gas by failing early + require( + sellOrder.expirationTimeSeconds > auctionDetails.currentTimeSeconds, + "AUCTION_EXPIRED" + ); + // Validate the buyer amount is greater than the current auction amount + require( + buyOrder.makerAssetAmount >= auctionDetails.currentAmount, + "INVALID_AMOUNT" + ); + // Match orders, maximally filling `buyOrder` + matchedFillResults = EXCHANGE.matchOrders( + buyOrder, + sellOrder, + buySignature, + sellSignature + ); + // The difference in sellOrder.takerAssetAmount and current amount is given as spread to the matcher + // This may include additional spread from the buyOrder.makerAssetAmount and the currentAmount. + // e.g currentAmount is 30, sellOrder.takerAssetAmount is 10 and buyOrder.makerAssetamount is 40. + // 10 (40-30) is returned to the buyer, 20 (30-10) sent to the seller and 10 has previously + // been transferred to the seller during matchOrders + uint256 leftMakerAssetSpreadAmount = matchedFillResults.leftMakerAssetSpreadAmount; + if (leftMakerAssetSpreadAmount > 0) { + // ERC20 Asset data itself is encoded as follows: + // + // | Area | Offset | Length | Contents | + // |----------|--------|---------|-------------------------------------| + // | Header | 0 | 4 | function selector | + // | Params | | 1 * 32 | function parameters: | + // | | 4 | 12 | 1. token address padding | + // | | 16 | 20 | 2. token address | + bytes memory assetData = sellOrder.takerAssetData; + address token = assetData.readAddress(16); + // Calculate the excess from the buy order. This can occur if the buyer sends in a higher + // amount than the calculated current amount + uint256 buyerExcessAmount = safeSub(buyOrder.makerAssetAmount, auctionDetails.currentAmount); + uint256 sellerExcessAmount = safeSub(leftMakerAssetSpreadAmount, buyerExcessAmount); + // Return the difference between auctionDetails.currentAmount and sellOrder.takerAssetAmount + // to the seller + if (sellerExcessAmount > 0) { + IERC20Token(token).transfer(sellOrder.makerAddress, sellerExcessAmount); + } + // Return the difference between buyOrder.makerAssetAmount and auctionDetails.currentAmount + // to the buyer + if (buyerExcessAmount > 0) { + IERC20Token(token).transfer(buyOrder.makerAddress, buyerExcessAmount); + } + } + return matchedFillResults; + } + + /// @dev Calculates the Auction Details for the given order + /// @param order The sell order + /// @return AuctionDetails + function getAuctionDetails( + LibOrder.Order memory order + ) + public + returns (AuctionDetails memory auctionDetails) + { + uint256 makerAssetDataLength = order.makerAssetData.length; + // It is unknown the encoded data of makerAssetData, we assume the last 64 bytes + // are the Auction Details encoding. + // Auction Details is encoded as follows: + // + // | Area | Offset | Length | Contents | + // |----------|--------|---------|-------------------------------------| + // | Params | | 2 * 32 | parameters: | + // | | -64 | 32 | 1. auction begin unix timestamp | + // | | -32 | 32 | 2. auction begin begin amount | + // ERC20 asset data length is 4+32, 64 for auction details results in min length 100 + require( + makerAssetDataLength >= 100, + "INVALID_ASSET_DATA" + ); + uint256 auctionBeginTimeSeconds = order.makerAssetData.readUint256(makerAssetDataLength - 64); + uint256 auctionBeginAmount = order.makerAssetData.readUint256(makerAssetDataLength - 32); + // Ensure the auction has a valid begin time + require( + order.expirationTimeSeconds > auctionBeginTimeSeconds, + "INVALID_BEGIN_TIME" + ); + uint256 auctionDurationSeconds = order.expirationTimeSeconds-auctionBeginTimeSeconds; + // Ensure the auction goes from high to low + uint256 minAmount = order.takerAssetAmount; + require( + auctionBeginAmount > minAmount, + "INVALID_AMOUNT" + ); + uint256 amountDelta = auctionBeginAmount-minAmount; + // solhint-disable-next-line not-rely-on-time + uint256 timestamp = block.timestamp; + auctionDetails.beginTimeSeconds = auctionBeginTimeSeconds; + auctionDetails.endTimeSeconds = order.expirationTimeSeconds; + auctionDetails.beginAmount = auctionBeginAmount; + auctionDetails.endAmount = minAmount; + auctionDetails.currentTimeSeconds = timestamp; + + uint256 remainingDurationSeconds = order.expirationTimeSeconds-timestamp; + if (timestamp < auctionBeginTimeSeconds) { + // If the auction has not yet begun the current amount is the auctionBeginAmount + auctionDetails.currentAmount = auctionBeginAmount; + } else if (timestamp >= order.expirationTimeSeconds) { + // If the auction has ended the current amount is the minAmount. + // Auction end time is guaranteed by 0x Exchange due to the order expiration + auctionDetails.currentAmount = minAmount; + } else { + auctionDetails.currentAmount = safeAdd( + minAmount, + safeDiv( + safeMul(remainingDurationSeconds, amountDelta), + auctionDurationSeconds + ) + ); + } + return auctionDetails; + } +} |