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| pragma solidity 0.4.21; | ||
| pragma experimental "v0.5.0"; | ||
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| import { ReentrancyGuard } from "zeppelin-solidity/contracts/ReentrancyGuard.sol"; | ||
| import { SafeMath } from "zeppelin-solidity/contracts/math/SafeMath.sol"; | ||
| import { ERC721Token } from "zeppelin-solidity/contracts/token/ERC721/ERC721Token.sol"; | ||
| import { Margin } from "../Margin.sol"; | ||
| import { TokenInteract } from "../../lib/TokenInteract.sol"; | ||
| import { ForceRecoverCollateralDelegator } from "../interfaces/ForceRecoverCollateralDelegator.sol"; | ||
| import { LoanOwner } from "../interfaces/LoanOwner.sol"; | ||
| import { MarginCallDelegator } from "../interfaces/MarginCallDelegator.sol"; | ||
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| /** | ||
| * @title ERC721MarginLoan | ||
| * @author dYdX | ||
| * | ||
| * Contract used to tokenize margin loans as ERC721-compliant non-fungible tokens. Holding the | ||
| * token allows the holder to margin-call the position and be entitled to all payouts. Functionality | ||
| * is added to let users approve other addresses margin-call positions for them. Allows any position | ||
| * to be force-recovered by anyone as long as the payout goes to the owner of the token. | ||
| */ | ||
| /* solium-disable-next-line */ | ||
| contract ERC721MarginLoan is | ||
| ERC721Token, | ||
| MarginCallDelegator, | ||
| ForceRecoverCollateralDelegator, | ||
| ReentrancyGuard | ||
| { | ||
| using SafeMath for uint256; | ||
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| // ============ Events ============ | ||
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| event MarginCallerApproval( | ||
| address indexed lender, | ||
| address indexed approved, | ||
| bool isApproved | ||
| ); | ||
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| event OwedTokenWithdrawn( | ||
| bytes32 indexed positionId, | ||
| address indexed lender, | ||
| address owedToken, | ||
| uint256 owedTokenWithdrawn | ||
| ); | ||
|
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| // ============ State Variables ============ | ||
|
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| // Mapping from an address to other addresses that are approved to be margin-callers | ||
| mapping (address => mapping (address => bool)) public approvedCallers; | ||
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| // Mapping from a positionId to the value of totalOwedTokensRepaidToLender for the position when | ||
| // it was initially transferred to this address. | ||
| mapping (bytes32 => uint256) public owedTokensRepaidSinceLastWithdraw; | ||
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| // Mapping from a positionId to the address of the owedToken of that position. Needed because | ||
| // margin erases this information when the position is closed. | ||
| mapping (bytes32 => address) public owedTokenForPosition; | ||
|
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| // ============ Constructor ============ | ||
|
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| function ERC721MarginLoan( | ||
| address margin | ||
| ) | ||
| public | ||
| ERC721Token("dYdX Margin Loans", "DYDX-Loan") | ||
| MarginCallDelegator(margin) | ||
| ForceRecoverCollateralDelegator(margin) | ||
| { | ||
| } | ||
|
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| // ============ Token-Holder functions ============ | ||
|
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| /** | ||
| * Approves any address to margin-call any of the positions owned by the sender. | ||
| * | ||
| * @param caller Address of the margin-caller | ||
| * @param isApproved True if approving the caller, false if revoking approval | ||
| */ | ||
| function approveCaller( | ||
| address caller, | ||
| bool isApproved | ||
| ) | ||
| external | ||
| nonReentrant | ||
| { | ||
| // cannot approve self since any address can already close its own positions | ||
| require(caller != msg.sender); | ||
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| if (approvedClosers[msg.sender][caller] != isApproved) { | ||
| approvedClosers[msg.sender][caller] = isApproved; | ||
| emit CallerApproval( | ||
| msg.sender, | ||
| caller, | ||
| isApproved | ||
| ); | ||
| } | ||
| } | ||
|
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| /** | ||
| * Transfer ownership of the loan externally to this contract, thereby burning the token. | ||
| * | ||
| * @param positionId Unique ID of the position | ||
| * @param to Address to transfer loan ownership to | ||
| * @param safely If true, requires that there is no owedToken held in this contract for | ||
| * the loan being transferred. Once the loan is untokenized, there is no way | ||
| * for the lender to withdraw the tokens from this contract. | ||
| */ | ||
| function untokenizeLoan( | ||
| bytes32 positionId, | ||
| address to, | ||
| bool safely | ||
| ) | ||
| external | ||
| nonReentrant | ||
| { | ||
| uint256 tokenId = uint256(positionId); | ||
| require(msg.sender == ownerOf(tokenId)); | ||
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| if (safely) { | ||
| uint256 totalRepaid = Margin(DYDX_MARGIN).getTotalOwedTokensRepaidToLender(positionId); | ||
| require(totalRepaid == owedTokensRepaidSinceLastWithdraw[positionId]); | ||
| } | ||
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| _burn(msg.sender, tokenId); // requires msg.sender to be owner | ||
| Margin(DYDX_MARGIN).transferLoan(positionId, to); | ||
| } | ||
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| /** | ||
| * Helper to allow withdrawal for multiple positions in one call | ||
| * | ||
| * @param who Array of positions to withdraw for | ||
| */ | ||
| function withdrawMultiple( | ||
| bytes32[] positionIds | ||
| ) | ||
| external | ||
| nonReentrant | ||
| { | ||
| for (uint256 i = 0; i < positionIds.length; i++) { | ||
| withdrawImpl(positionIds[i]); | ||
| } | ||
| } | ||
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| /** | ||
| * Withdraw the owedToken repaid for a loan | ||
| * | ||
| * @param positionId Unique ID of the position | ||
| * @return The amount of owedToken withdrawn | ||
| */ | ||
| function withdraw( | ||
| bytes32 positionId | ||
| ) | ||
| external | ||
| nonReentrant | ||
| returns (uint256) | ||
| { | ||
| return withdrawImpl(positionId); | ||
| } | ||
|
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| // ============ OnlyMargin Functions ============ | ||
|
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| /** | ||
| * Called by the Margin contract when anyone transfers ownership of a position to this contract. | ||
| * This function mints a new ERC721 Token and returns this address to | ||
| * indicate to Margin that it is willing to take ownership of the position. | ||
| * | ||
| * @param from Address of previous position owner | ||
| * @param positionId Unique ID of the position | ||
| * @return This address on success, throw otherwise | ||
| */ | ||
| function receiveLoanOwnership( | ||
| address from, | ||
| bytes32 positionId | ||
| ) | ||
| external | ||
| onlyMargin | ||
| nonReentrant | ||
| returns (address) | ||
| { | ||
| _mint(from, uint256(positionId)); | ||
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| owedTokensRepaidSinceLastWithdraw[positionId] = | ||
| Margin(DYDX_MARGIN).getTotalOwedTokensRepaidToLender(positionId); | ||
| owedTokenForPosition[positionId] = | ||
| Margin(DYDX_MARGIN).getPositionOwedToken(positionId); | ||
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| return address(this); // returning own address retains ownership of position | ||
| } | ||
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| /** | ||
| * Called by Margin when additional value is added onto a position. Rejects this addition. | ||
| * | ||
| * param from Address that added the value to the position | ||
| * param positionId Unique ID of the position | ||
| * param principalAdded Principal amount added to position | ||
| * @return False | ||
| */ | ||
| function marginLoanIncreased( | ||
| address, /* from */ | ||
| bytes32, /* positionId */ | ||
| uint256 /* principalAdded */ | ||
| ) | ||
| external | ||
| onlyMargin | ||
| nonReentrant | ||
| returns (bool) | ||
| { | ||
| return false; | ||
| } | ||
|
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| /** | ||
| * Called by Margin when another address attempts to margin-call a loan | ||
| * | ||
| * @param who Address attempting to initiate the loan call | ||
| * @param positionId Unique ID of the position | ||
| * param depositAmount (unused) | ||
| * @return True to consent to the loan being called if the initiator is a trusted | ||
| * loan caller or the owner of the loan | ||
| */ | ||
| function marginCallOnBehalfOf( | ||
| address who, | ||
| bytes32 positionId, | ||
| uint256 /* depositAmount */ | ||
| ) | ||
| external | ||
| onlyMargin | ||
| nonReentrant | ||
| returns (bool) | ||
| { | ||
| address owner = ownerOf(uint256(positionId)); | ||
| return (who == owner) || approvedCallers[owner][who]; | ||
| } | ||
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| /** | ||
| * Called by Margin when another address attempts to cancel a margin call for a loan | ||
| * | ||
| * @param who Address attempting to initiate the loan call cancel | ||
| * @param positionId Unique ID of the position | ||
| * @return True to consent to the loan call being canceled if the initiator is a | ||
| * trusted loan caller or the owner of the loan | ||
| */ | ||
| function cancelMarginCallOnBehalfOf( | ||
| address who, | ||
| bytes32 positionId | ||
| ) | ||
| external | ||
| onlyMargin | ||
| nonReentrant | ||
| returns (bool) | ||
| { | ||
| address owner = ownerOf(uint256(positionId)); | ||
| return (who == owner) || approvedCallers[owner][who]; | ||
| } | ||
|
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| /** | ||
| * Called by Margin when another address attempts to force recover the loan. Allow anyone to | ||
| * force recover the loan as long as the payout goes to the token owner. | ||
| * | ||
| * param (unused) | ||
| * @param positionId Unique ID of the position | ||
| * @param collateralRecipient Address to send the recovered tokens to | ||
| * @return True if forceRecoverCollateral() is permitted | ||
| */ | ||
| function forceRecoverCollateralOnBehalfOf( | ||
| address /* who */, | ||
| bytes32 positionId, | ||
| address collateralRecipient | ||
| ) | ||
| external | ||
| onlyMargin | ||
| nonReentrant | ||
| returns (bool) | ||
| { | ||
| return ownerOf(uint256(positionId)) == collateralRecipient; | ||
| } | ||
|
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| // ============ Helper Functions ============ | ||
|
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| /** | ||
| * Implementation of withdrawing owedToken for a particular positionId | ||
| * | ||
| * @param positionId Unique ID of the position | ||
| * @return The number of owedToken withdrawn | ||
| */ | ||
| function withdrawImpl( | ||
| bytes32 positionId | ||
| ) | ||
| internal | ||
| returns (uint256) | ||
| { | ||
| uint256 totalRepaid = Margin(DYDX_MARGIN).getTotalOwedTokensRepaidToLender(positionId); | ||
| uint256 tokensToSend = totalRepaid.sub(owedTokensRepaidSinceLastWithdraw[positionId]); | ||
|
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| if (tokensToSend == 0) { | ||
| return 0; | ||
| } | ||
|
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| owedTokensRepaidSinceLastWithdraw[positionId] = totalRepaid; | ||
|
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| address owedToken = owedTokenForPosition[positionId]; | ||
| address owner = ownerOf(uint256(positionId)); | ||
| TokenInteract.transfer(owedToken, owner, tokensToSend); | ||
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| emit OwedTokenWithdrawn( | ||
| positionId, | ||
| owner, | ||
| owedToken, | ||
| tokensToSend | ||
| ); | ||
|
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| return tokensToSend; | ||
| } | ||
| } |
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