NFTs owned by ENS names

ERCOver9000.sol

pragma solidity ^0.4.23;


interface ENS {

    // Logged when the owner of a node assigns a new owner to a subnode.
    event NewOwner(bytes32 indexed node, bytes32 indexed label, address owner);

    // Logged when the owner of a node transfers ownership to a new account.
    event Transfer(bytes32 indexed node, address owner);

    // Logged when the resolver for a node changes.
    event NewResolver(bytes32 indexed node, address resolver);

    // Logged when the TTL of a node changes
    event NewTTL(bytes32 indexed node, uint64 ttl);


    function setSubnodeOwner(bytes32 node, bytes32 label, address owner) public;
    function setResolver(bytes32 node, address resolver) public;
    function setOwner(bytes32 node, address owner) public;
    function setTTL(bytes32 node, uint64 ttl) public;
    function owner(bytes32 node) public view returns (address);
    function resolver(bytes32 node) public view returns (address);
    function ttl(bytes32 node) public view returns (uint64);

}


contract ERCOver9000 {

    using SafeMath for uint256;
    using Address for address;

    ENS ens = ENS(0xENSaDdREsS0000000);

    // Equals to `bytes4(keccak256("onERC721Received(address,address,uint256,bytes)"))`
    // which can be also obtained as `IERC721Receiver(0).onERC721Received.selector`
    bytes4 private constant ERCOver9000_RECEIVED = 0x150b7a02;

    // Mapping from token ID to owning ENS name
    mapping (uint256 => bytes32) internal tokenOwner;

    // Mapping from token ID to approved name
    mapping (uint256 => bytes32) internal tokenApprovals;

    // Mapping from owner to number of owned token
    mapping (bytes32 => uint256) internal ownedTokensCount;

    // Mapping from owner to operator approvals
    mapping (bytes32 => mapping (bytes32 => bool)) internal operatorApprovals;

    function ERCOver9000() public {
        // register the supported interfaces to conform to ERC721 via ERC165
        _registerInterface(InterfaceId_ERC721);
    }

    /**
     * @dev Gets the balance of the specified address
     * @param _owner address to query the balance of
     * @return uint256 representing the amount owned by the passed address
     */
    function balanceOf(bytes32 _owner) public view returns (uint256) {
        require(ens.owner(_owner) != address(0));
        return ownedTokensCount[_owner];
    }

    /**
     * @dev Gets the owner of the specified token ID
     * @param _tokenId uint256 ID of the token to query the owner of
     * @return owner address currently marked as the owner of the given token ID
     */
    function ownerOf(uint256 _tokenId) public view returns (bytes32) {
        bytes32 owner = tokenOwner[_tokenId];
        require(ens.owner(owner) != address(0));
        return owner;
    }

    /**
     * @dev Approves another address to transfer the given token ID
     * The zero address indicates there is no approved address.
     * There can only be one approved address per token at a given time.
     * Can only be called by the token owner or an approved operator.
     * @param _to address to be approved for the given token ID
     * @param _tokenId uint256 ID of the token to be approved
     */
    function approve(bytes32 _to, uint256 _tokenId) public {
        bytes32 owner = ownerOf(_tokenId);
        require(_to != owner);
        require(msg.sender == ens.owner(owner) || isApprovedForAll(owner, msg.sender));

        tokenApprovals[_tokenId] = _to;
        emit Approval(owner, _to, _tokenId);
    }

    /**
     * @dev Gets the approved address for a token ID, or zero if no address set
     * @param _tokenId uint256 ID of the token to query the approval of
     * @return address currently approved for the given token ID
     */
    function getApproved(uint256 _tokenId) public view returns (bytes32) {
        return tokenApprovals[_tokenId];
    }

    /**
     * @dev Sets or unsets the approval of a given operator
     * An operator is allowed to transfer all tokens of the sender on their behalf
     * @param _to operator address to set the approval
     * @param _approved representing the status of the approval to be set
     */
    function setApprovalForAll(bytes32 _from, bytes32 _to, bool _approved) public {
        require(msg.sender == ens.owner(_from));
        require(ens.owner(_to) != msg.sender);
        operatorApprovals[_from][_to] = _approved;
        emit ApprovalForAll(msg.sender, _to, _approved);
    }

    /**
     * @dev Tells whether an operator is approved by a given owner
     * @param _owner owner address which you want to query the approval of
     * @param _operator operator address which you want to query the approval of
     * @return bool whether the given operator is approved by the given owner
     */
    function isApprovedForAll(
        bytes32 _owner,
        bytes32 _operator
        )
        public
        view
        returns (bool)
        {
            return operatorApprovals[_owner][_operator];
        }

    /**
     * @dev Transfers the ownership of a given token ID to another address
     * Usage of this method is discouraged, use `safeTransferFrom` whenever possible
     * Requires the msg sender to be the owner, approved, or operator
     * @param _from current owner of the token
     * @param _to address to receive the ownership of the given token ID
     * @param _tokenId uint256 ID of the token to be transferred
    */
    function transferFrom(
        bytes32 _from,
        bytes32 _to,
        uint256 _tokenId
        )
        public
        {
            require(isApprovedOrOwner(msg.sender, _tokenId));
            require(ens.owner(_to) != address(0));

            clearApproval(_from, _tokenId);
            removeTokenFrom(_from, _tokenId);
            addTokenTo(_to, _tokenId);

            emit Transfer(_from, _to, _tokenId);
        }

    /**
     * @dev Safely transfers the ownership of a given token ID to another address
     * If the target address is a contract, it must implement `onERC721Received`,
     * which is called upon a safe transfer, and return the magic value
     * `bytes4(keccak256("onERC721Received(address,address,uint256,bytes)"))`; otherwise,
     * the transfer is reverted.
     *
     * Requires the msg sender to be the owner, approved, or operator
     * @param _from current owner of the token
     * @param _to address to receive the ownership of the given token ID
     * @param _tokenId uint256 ID of the token to be transferred
    */
    function safeTransferFrom(
        bytes32 _from,
        bytes32 _to,
        uint256 _tokenId
        )
        public
        {
            // solium-disable-next-line arg-overflow
            safeTransferFrom(_from, _to, _tokenId, "");
        }

    /**
     * @dev Safely transfers the ownership of a given token ID to another address
     * If the target address is a contract, it must implement `onERC721Received`,
     * which is called upon a safe transfer, and return the magic value
     * `bytes4(keccak256("onERC721Received(address,address,uint256,bytes)"))`; otherwise,
     * the transfer is reverted.
     * Requires the msg sender to be the owner, approved, or operator
     * @param _from current owner of the token
     * @param _to address to receive the ownership of the given token ID
     * @param _tokenId uint256 ID of the token to be transferred
     * @param _data bytes data to send along with a safe transfer check
     */
    function safeTransferFrom(
        bytes32 _from,
        bytes32 _to,
        uint256 _tokenId,
        bytes _data
        )
        public
        {
            transferFrom(_from, _to, _tokenId);
            // solium-disable-next-line arg-overflow
            require(checkAndCallSafeTransfer(_from, _to, _tokenId, _data));
        }

    /**
     * @dev Returns whether the specified token exists
     * @param _tokenId uint256 ID of the token to query the existence of
     * @return whether the token exists
     */
    function _exists(uint256 _tokenId) internal view returns (bool) {
        bytes32 owner = tokenOwner[_tokenId];
        return ens.owner(owner) != address(0); // TODO: What is zero value of bytes32?
    }

    /**
     * @dev Returns whether the given spender can transfer a given token ID
     * @param _spender address of the spender to query
     * @param _tokenId uint256 ID of the token to be transferred
     * @return bool whether the msg.sender is approved for the given token ID,
     *  is an operator of the owner, or is the owner of the token
     */
    function isApprovedOrOwner(
        bytes32 _spender,
        uint256 _tokenId
        )
        internal
        view
        returns (bool)
        {
            bytes32 owner = ownerOf(_tokenId);
            // Disable solium check because of
            // https://github.com/duaraghav8/Solium/issues/175
            // solium-disable-next-line operator-whitespace
            return (
        _spender == owner ||
        getApproved(_tokenId) == _spender ||
        isApprovedForAll(owner, _spender)
        );
        }

    /**
     * @dev Internal function to mint a new token
     * Reverts if the given token ID already exists
     * @param _to The address that will own the minted token
     * @param _tokenId uint256 ID of the token to be minted by the msg.sender
     */
    function _mint(bytes32 _to, uint256 _tokenId) internal {
        require(_to != address(0));
        addTokenTo(_to, _tokenId);
        emit Transfer(address(0), _to, _tokenId);
    }

    /**
     * @dev Internal function to burn a specific token
     * Reverts if the token does not exist
     * @param _tokenId uint256 ID of the token being burned by the msg.sender
     */
    function _burn(bytes32 _owner, uint256 _tokenId) internal {
        clearApproval(_owner, _tokenId);
        removeTokenFrom(_owner, _tokenId);
        emit Transfer(_owner, address(0), _tokenId);
    }

    /**
     * @dev Internal function to clear current approval of a given token ID
     * Reverts if the given address is not indeed the owner of the token
     * @param _owner owner of the token
     * @param _tokenId uint256 ID of the token to be transferred
     */
    function clearApproval(bytes32 _owner, uint256 _tokenId) internal {
        require(ownerOf(_tokenId) == _owner);
        if (tokenApprovals[_tokenId] != address(0)) {
            tokenApprovals[_tokenId] = address(0);
        }
    }

    /**
     * @dev Internal function to add a token ID to the list of a given address
     * @param _to address representing the new owner of the given token ID
     * @param _tokenId uint256 ID of the token to be added to the tokens list of the given address
     */
    function addTokenTo(bytes32 _to, uint256 _tokenId) internal {
        require(tokenOwner[_tokenId] == 0); // TODO: What is zero value of bytes32?
        tokenOwner[_tokenId] = _to;
        ownedTokensCount[_to] = ownedTokensCount[_to].add(1);
    }

    /**
     * @dev Internal function to remove a token ID from the list of a given address
     * @param _from address representing the previous owner of the given token ID
     * @param _tokenId uint256 ID of the token to be removed from the tokens list of the given address
     */
    function removeTokenFrom(bytes32 _from, uint256 _tokenId) internal {
        require(ownerOf(_tokenId) == _from);
        ownedTokensCount[_from] = ownedTokensCount[_from].sub(1);
        tokenOwner[_tokenId] = 0; // TODO: What is zero value of bytes32?
    }
}