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91 lines
2.6 KiB
91 lines
2.6 KiB
pragma solidity ^0.4.24;
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import "../../math/SafeMath.sol";
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import "./FinalizableCrowdsale.sol";
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import "../../payment/escrow/RefundEscrow.sol";
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/**
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* @title RefundableCrowdsale
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* @dev Extension of Crowdsale contract that adds a funding goal, and
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* the possibility of users getting a refund if goal is not met.
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* WARNING: note that if you allow tokens to be traded before the goal
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* is met, then an attack is possible in which the attacker purchases
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* tokens from the crowdsale and when they sees that the goal is
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* unlikely to be met, they sell their tokens (possibly at a discount).
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* The attacker will be refunded when the crowdsale is finalized, and
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* the users that purchased from them will be left with worthless
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* tokens. There are many possible ways to avoid this, like making the
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* the crowdsale inherit from PostDeliveryCrowdsale, or imposing
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* restrictions on token trading until the crowdsale is finalized.
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* This is being discussed in
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* https://github.com/OpenZeppelin/openzeppelin-solidity/issues/877
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* This contract will be updated when we agree on a general solution
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* for this problem.
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*/
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contract RefundableCrowdsale is FinalizableCrowdsale {
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using SafeMath for uint256;
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// minimum amount of funds to be raised in weis
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uint256 private _goal;
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// refund escrow used to hold funds while crowdsale is running
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RefundEscrow private _escrow;
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/**
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* @dev Constructor, creates RefundEscrow.
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* @param goal Funding goal
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*/
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constructor(uint256 goal) internal {
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require(goal > 0);
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_escrow = new RefundEscrow(wallet());
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_goal = goal;
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}
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/**
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* @return minimum amount of funds to be raised in wei.
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*/
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function goal() public view returns(uint256) {
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return _goal;
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}
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/**
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* @dev Investors can claim refunds here if crowdsale is unsuccessful
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* @param refundee Whose refund will be claimed.
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*/
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function claimRefund(address refundee) public {
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require(finalized());
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require(!goalReached());
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_escrow.withdraw(refundee);
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}
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/**
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* @dev Checks whether funding goal was reached.
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* @return Whether funding goal was reached
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*/
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function goalReached() public view returns (bool) {
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return weiRaised() >= _goal;
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}
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/**
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* @dev escrow finalization task, called when finalize() is called
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*/
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function _finalization() internal {
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if (goalReached()) {
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_escrow.close();
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_escrow.beneficiaryWithdraw();
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} else {
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_escrow.enableRefunds();
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}
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super._finalization();
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}
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/**
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* @dev Overrides Crowdsale fund forwarding, sending funds to escrow.
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*/
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function _forwardFunds() internal {
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_escrow.deposit.value(msg.value)(msg.sender);
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}
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}
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