Contract Name:
CryptoCities
Contract Source Code:
// ___ _ ___ _ _ _
// / __\_ __ _ _ _ __ | |_ ___ / __\(_)| |_ (_) ___ ___
// / / | '__|| | | || '_ \ | __|/ _ \ / / | || __|| | / _ \/ __|
// / /___| | | |_| || |_) || |_| (_) |/ /___ | || |_ | || __/\__ \
// \____/|_| \__, || .__/ \__|\___/ \____/ |_| \__||_| \___||___/
// |___/ |_|
//
// CryptoCities is an ERC721 compliant smart contract for this project:
// (https://cryptocities.net)
//
// In addition to a standard ERC721 interface it also includes:
// - a maker / taker off-chain marketplace which executes final trades here
// - batch functions for most token read functions
// - a limited supply of 25000 tokens
//
// Discord:
// https://discord.gg/Y4mhwWg
//
// Bug Bounty:
// Please see the details of our bug bounty program below.
// https://cryptocities.net/bug_bounty
//
// Disclaimer:
// We take the greatest of care when making our smart contracts but this is crypto and the future
// is always unknown. Even if it is exciting and full of wonderful possibilities, anything can happen,
// blockchains will evolve, vulnerabilities can arise, and markets can go up and down. CryptoCities and its
// owners accept no liability for any issues relating to the use of this contract or any losses that may occur.
// Please see our full terms here:
// https://cryptocities.net/terms
// SPDX-License-Identifier: MIT
pragma solidity 0.8.7;
import "./base/ERC721Batchable.sol";
contract CryptoCities is ERC721Batchable
{
// there can only ever be a max of this many tokens in the contract
uint public constant tokenLimit = 25000;
// the base url used for all meta data
// likely to be stored on IPFS over time
string private _baseTokenURI;
// the opensea proxy registry contract (can be changed if this registry ever moves to a new contract)
// 0xa5409ec958C83C3f309868babACA7c86DCB077c1 mainnet
// 0xF57B2c51dED3A29e6891aba85459d600256Cf317 rinkeby
// 0x0000000000000000000000000000000000000000 local
address private _proxyRegistryAddress;
// only authorized minters can mint tokens
// this will originally be set to a swapping contract to allow users to swap their tokens to this new contract
mapping (address => bool) public isMinter;
// pausing the market disables the built-in maker/taker offer system
// it does not affect normal ERC721 transfers
bool public marketPaused;
// the marketplace fee for any internal paid trades (stored in basis points eg. 250 = 2.5% fee)
uint16 public marketFee;
// the marketplace witness is used to validate marketplace offers
address private _marketWitness;
// offer that can no longer be used any more
mapping (bytes32 => bool) private _cancelledOrCompletedOffers;
// support for ERC2981
uint16 private _royaltyFee;
address private _royaltyReciever;
constructor(address _owner, address _recovery, address proxyRegistryAddress) ERC721("CryptoCities", unicode"⬢City")
{
// set the owner, recovery & treasury addresses
transferOwnership(_owner);
treasury = _owner;
recovery = _recovery;
// set the meta base url
_baseTokenURI = "https://cryptocities.net/meta/";
// set the open sea proxy registry address
_proxyRegistryAddress = proxyRegistryAddress;
// market starts disabled
marketPaused = true;
marketFee = 250;
}
/// BASE URI
// base uri is where the metadata lives
// only the owner can change this
function setBaseURI(string memory baseTokenURI) external onlyOwner {
_baseTokenURI = baseTokenURI;
}
function _baseURI() internal view virtual override returns (string memory) {
return _baseTokenURI;
}
function contractURI() public pure returns (string memory) {
return "https://cryptocities.net/meta/cities_contract";
}
/// PROXY REGISTRY
// registers a proxy address for OpenSea or others
// can only be changed by the contract owner
// setting address to 0 will disable the proxy
function setProxyRegistry(address proxyRegistry) external onlyOwner {
// check the contract address is correct (will revert if not)
if(proxyRegistry!= address(0)) {
ProxyRegistry(proxyRegistry).proxies(address(0));
}
_proxyRegistryAddress = proxyRegistry;
}
// this override allows us to whitelist user's OpenSea proxy accounts to enable gas-less listings
function isApprovedForAll(address token_owner, address operator) public view override returns (bool)
{
// whitelist OpenSea proxy contract for easy trading.
if(_proxyRegistryAddress!= address(0)) {
ProxyRegistry proxyRegistry = ProxyRegistry(_proxyRegistryAddress);
if (address(proxyRegistry.proxies(token_owner)) == operator) {
return true;
}
}
return super.isApprovedForAll(token_owner, operator);
}
/// MINTING
// only authorized minters can mint
// can't mint more tokens than the token limit
// ERC721 standard checks:
// can't mint while the contract is paused (checked in _beforeTokenTransfer())
// token id's can't already exist
// cant mint to address(0)
// if 'to' refers to a smart contract, it must implement {IERC721Receiver-onERC721Received}, which is called upon a safe transfer.
// emitted when a minter's authorization changes
event MinterSet(address indexed minter, bool auth);
// only allows an authorized minter to call the function
modifier onlyMinters()
{
require(isMinter[_msgSender()]==true, "caller not a minter");
_;
}
// changes a minter's authorization
function setMinter(address minter, bool authorized) external onlyOwner
{
isMinter[minter] = authorized;
emit MinterSet(minter, authorized);
}
// mint a single token
function mint(address to, uint256 tokenId) external onlyMinters
{
require(totalSupply()<tokenLimit, "token limit reached");
_safeMint(to, tokenId);
}
// mint a batch of tokens
// (gas: this function can run out of gas if too many id's are provided
// limiting to 25 will currently fit in the block gas limit but this may change in future)
function mintBatch(address to, uint256[] memory tokenIds) external onlyMinters
{
require(tokenIds.length <= 25, "more than 25 ids");
require(totalSupply()+tokenIds.length <= tokenLimit, "batch exceeds token limit");
for (uint256 i = 0; i < tokenIds.length; i++) {
// we safe mint the first token
if(i==0) _safeMint(to, tokenIds[i]);
// then we assume the rest are safe because they are going to the same receiver
else _mint(to, tokenIds[i]);
}
}
/// BURNING
// only the contract owner can burn tokens it owns
// the contract owner can't burn someone elses tokens
// normal users can't burn tokens
// ERC721 standard checks:
// can't burn while the contract is paused (checked in _beforeTokenTransfer())
// the token id must exist
function burn(uint256 tokenId) external onlyOwner
{
require(ownerOf(tokenId) == owner(), "token owner not contract owner");
_burn(tokenId);
}
/// MARKETPLACE
// this contract includes a maker / taker offerplace
// (similar to those seen in OpenSea, 0x Protocol and other NFT projects)
//
// offers are made by makers off-chain and filled by callers on-chain
// makers do this by signing their offer with their wallet
// smart contracts can't be makers because they can't sign messages
// if a witness address is set then it must sign the offer hash too (eg. the website marketplace)
// there are two types of offers depending on whether the maker specifies a taker in their offer:
// maker / taker (peer-to-peer offer: two users agreeing to trade items)
// maker / no taker (open offer: one user listing their items in the marketplace)
// if eth is paid then it will always be on the taker side (the maker never pays eth in this simplified model)
// a market fee is charged if eth is paid
// trading tokens with no eth is free and no fee is deducted
// allowed exchanges:
// maker tokens > < eth (maker sells their tokens to anyone)
// maker tokens > (maker gives their tokens away to anyone)
// maker tokens > taker (maker gives their tokens to a specific taker)
// maker tokens > < taker tokens .. for specific tokens back
// maker tokens > < taker tokens & eth .. for specific tokens and eth back
// maker tokens > < taker eth .. for eth only
// maker < taker tokens (taker gives their tokens to the maker)
// maker < taker tokens & eth .. and with eth
event OfferAccepted(bytes32 indexed hash, address indexed maker, address indexed taker, uint[] makerIds, uint[] takerIds, uint takerWei, uint marketFee);
event OfferCancelled(bytes32 indexed hash);
struct Offer {
address maker;
address taker;
uint256[] makerIds;
uint256[] takerIds;
uint256 takerWei;
uint256 expiry;
uint256 nonce;
}
// pausing the market will stop offers from being able to be accepted (they can still be generated or cancelled)
function pauseMarket(bool pauseTrading) external onlyOwner {
marketPaused = pauseTrading;
}
// the market fee is set in basis points (eg. 250 basis points = 2.5%)
function setMarketFee(uint16 basisPoints) external onlyOwner {
require(basisPoints <= 10000);
marketFee = basisPoints;
}
// if a market witness is set then it will need to sign all offers too (set to 0 to disable)
function setMarketWitness(address newWitness) external onlyOwner {
_marketWitness = newWitness;
}
// recovers the signer address from a offer hash and signature
function signerOfHash(bytes32 offer_hash, bytes memory signature) public pure returns (address signer){
require(signature.length == 65, "sig wrong length");
bytes32 geth_modified_hash = keccak256(abi.encodePacked("\x19Ethereum Signed Message:\n32", offer_hash));
bytes32 r;
bytes32 s;
uint8 v;
assembly {
r := mload(add(signature, 32))
s := mload(add(signature, 64))
v := byte(0, mload(add(signature, 96)))
}
if (v < 27) {
v += 27;
}
require(v == 27 || v == 28, "bad sig v");
return ecrecover(geth_modified_hash, v, r, s);
}
// this generates a hash of an offer that can then be signed by a maker
// the offer has to have basic validity before it can be hashed
// if checking ids then the tokens need to be owned by the parties too
function hashOffer(Offer memory offer, bool checkIds) public view returns (bytes32){
// the maker can't be 0
require(offer.maker!=address(0), "maker is 0");
// maker and taker can't be the same
require(offer.maker!=offer.taker, "same maker / taker");
// the offer must not be expired yet
require(block.timestamp < offer.expiry, "expired");
// token id must be in the offer
require(offer.makerIds.length>0 || offer.takerIds.length>0, "no ids");
// if checking ids then maker must own the maker token ids
if(checkIds){
for(uint i=0; i<offer.makerIds.length; i++){
require(ownerOf(offer.makerIds[i])==offer.maker, "bad maker ids");
}
}
// if no taker has been specified (open offer - i.e. typical marketplace listing)
if(offer.taker==address(0)){
// then there can't be taker token ids in the offer
require(offer.takerIds.length==0, "taker ids with no taker");
}
// if a taker has been specified (peer-to-peer offer - i.e. direct trade between two users)
else{
if(checkIds){
// then the taker must own all the taker token ids
for(uint i=0; i<offer.takerIds.length; i++){
require(ownerOf(offer.takerIds[i])==offer.taker, "bad taker ids");
}
}
}
// now return the hash
return keccak256(abi.encode(
offer.maker,
offer.taker,
keccak256(abi.encodePacked(offer.makerIds)),
keccak256(abi.encodePacked(offer.takerIds)),
offer.takerWei,
offer.expiry,
offer.nonce,
address(this) // including the contract address prevents cross-contract replays
));
}
// an offer is valid if:
// it's maker / taker details are valid
// it has been signed by the maker
// it has not been cancelled or completed yet
// the parties own their tokens (if checking ids)
// the witness has signed it (if witnessing is enabled)
// the trade is valid (if requested)
function validOffer(Offer memory offer, bytes memory signature, bytes memory witnessSignature, bool checkIds, bool checkTradeValid, uint checkValue) external view returns (bool){
// will revert if the offer or signer is not valid or checks fail
bytes32 _offer_hash = _getValidOfferHash(offer, signature, checkIds, checkTradeValid, checkValue);
// check the witness if needed
_validWitness(_offer_hash, witnessSignature);
return true;
}
// if a market witness is set then they need to sign the offer hash too
function _validWitness(bytes32 _offer_hash, bytes memory witnessSignature) internal view {
if(_marketWitness!=address(0)){
require(_marketWitness == signerOfHash(_offer_hash, witnessSignature), "wrong witness");
}
}
// gets the hash of an offer and checks that it has been signed by the maker
function _getValidOfferHash(Offer memory offer, bytes memory signature, bool checkIds, bool checkTradeValid, uint checkValue) internal view returns (bytes32){
// get the offer signer
bytes32 _offer_hash = hashOffer(offer, checkIds);
address _signer = signerOfHash(_offer_hash, signature);
// the signer must be the maker
require(offer.maker==_signer, "maker not signer");
// the offer can't be cancelled or completed already
require(_cancelledOrCompletedOffers[_offer_hash]!=true, "offer cancelled or completed");
// if checking the trade then we need to check the taker side too
if(checkTradeValid){
address caller = _msgSender();
// no trading when paused
require(!marketPaused, "marketplace paused");
// caller can't be the maker
require(caller!=offer.maker, "caller is the maker");
// if there is a taker specified then they must be the caller
require(caller==offer.taker || offer.taker==address(0), "caller not the taker");
// check the correct wei has been provided by the taker (can be 0)
require(checkValue==offer.takerWei, "wrong payment sent");
}
return _offer_hash;
}
// (gas: these functions can run out of gas if too many id's are provided
// not limiting them here because block gas limits change over time and we don't know what they will be in future)
// stops the offer hash from being usable in future
// can only be cancelled by the maker or the contract owner
function cancelOffer(Offer memory offer) external {
address caller = _msgSender();
require(caller == offer.maker || caller == owner(), "caller not maker or contract owner");
// get the offer hash
bytes32 _offer_hash = hashOffer(offer, false);
// set the offer hash as cancelled
_cancelledOrCompletedOffers[_offer_hash]=true;
emit OfferCancelled(_offer_hash);
}
// fills an offer
// offers can't be traded when the market is paused or the contract is paused
// offers must be valid and signed by the maker
// the caller has to be the taker or can be an unknown party if no taker is set
// eth may or may not be required by the offer
// tokens must belong to the makers and takers
function acceptOffer(Offer memory offer, bytes memory signature, bytes memory witnessSignature) external payable reentrancyGuard {
// CHECKS
// will revert if the offer or signer is not valid
// will also check token ids to make sure they belong to the parties
// will check the caller and eth matches the offer taker details
bytes32 _offer_hash = _getValidOfferHash(offer, signature, true, true, msg.value);
// check the witness if needed
_validWitness(_offer_hash, witnessSignature);
// EFFECTS
address caller = _msgSender();
// transfer the maker tokens to the caller
for(uint i=0; i<offer.makerIds.length; i++){
_safeTransfer(offer.maker, caller, offer.makerIds[i], "");
}
// transfer the taker tokens to the maker
for(uint i=0; i<offer.takerIds.length; i++){
_safeTransfer(caller, offer.maker, offer.takerIds[i], "");
}
// set the offer has as completed (stops the offer from being reused)
_cancelledOrCompletedOffers[_offer_hash]=true;
// INTERACTIONS
// transfer the payment if one is present
uint _fee = 0;
if(msg.value>0){
// calculate the marketplace fee (stored as basis points)
// eg. 250 basis points is 2.5% (250/10000)
_fee = msg.value * marketFee / 10000;
uint _earned = msg.value - _fee;
// safety check (should never be hit)
assert(_fee>=0 && _earned>=0 && _earned<= msg.value && _fee+_earned==msg.value);
// send the payment to the maker
// security note: calls to a maker should only revert if insufficient gas is sent by the caller/taker
// makers can't be smart contracts because makers need to sign the offer hash for us
// - currently only EOA's (externally owned accounts) can sign a message on the ethereum network
// - smart contracts don't have a private key and can't sign a message, so they can't be makers here
// - offers for specific makers can be blacklisted in the marketplace if required
(bool success, ) = offer.maker.call{value:_earned}("");
require(success, "payment to maker failed");
}
emit OfferAccepted(_offer_hash, offer.maker, caller, offer.makerIds, offer.takerIds, offer.takerWei, _fee);
}
/// ERC2981 support
function supportsInterface(bytes4 interfaceId) public view virtual override returns (bool) {
return interfaceId == 0x2a55205a // ERC2981
|| super.supportsInterface(interfaceId);
}
function royaltyInfo(uint256, uint256 salePrice) external view returns (address receiver, uint256 royaltyAmount)
{
return (_royaltyReciever, (salePrice * _royaltyFee) / 10000);
}
// the royalties fee is set in basis points (eg. 250 basis points = 2.5%)
function setRoyalties(address newReceiver, uint16 basisPoints) external onlyOwner {
require(basisPoints <= 10000);
_royaltyReciever = newReceiver;
_royaltyFee = basisPoints;
}
}
// used to whitelist proxy accounts of OpenSea users so that they are automatically able to trade any item on OpenSea
contract OwnableDelegateProxy {}
contract ProxyRegistry {
mapping(address => OwnableDelegateProxy) public proxies;
}
// SPDX-License-Identifier: MIT
pragma solidity 0.8.7;
import "@openzeppelin/contracts/token/ERC721/extensions/ERC721Enumerable.sol";
import "@openzeppelin/contracts/security/Pausable.sol";
import "../base/OwnableRecoverable.sol";
// ERC721Batchable wraps multiple commonly used base contracts into a single contract
//
// it includes:
// ERC721 with Enumerable
// contract ownership & recovery
// contract pausing
// treasury
// batching
abstract contract ERC721Batchable is ERC721Enumerable, Pausable, OwnableRecoverable
{
// the treasure address that can make withdrawals from the contract balance
address public treasury;
constructor()
{
}
// used to stop a contract function from being reentrant-called
bool private _reentrancyLock = false;
modifier reentrancyGuard {
require(!_reentrancyLock, "ReentrancyGuard: reentrant call");
_reentrancyLock = true;
_;
_reentrancyLock = false;
}
/// PAUSING
// only the contract owner can pause and unpause
// can't pause if already paused
// can't unpause if already unpaused
// disables minting, burning, transfers (including marketplace accepted offers)
function pause() external virtual onlyOwner {
_pause();
}
function unpause() external virtual onlyOwner {
_unpause();
}
// this hook is called by _mint, _burn & _transfer
// it allows us to block these actions while the contract is paused
// also prevent transfers to the contract address
function _beforeTokenTransfer(address from, address to, uint256 tokenId) internal virtual override {
require(to != address(this), "cant transfer to the contract address");
super._beforeTokenTransfer(from, to, tokenId);
require(!paused(), "token transfer while contract paused");
}
/// TREASURY
// can only be called by the contract owner
// withdrawals can only be made to the treasury account
// allows for a dedicated address to be used for withdrawals
function setTreasury(address newTreasury) external onlyOwner {
require(newTreasury!=address(0), "cant be 0 address");
treasury = newTreasury;
}
// funds can be withdrawn to the treasury account for safe keeping
function treasuryOut(uint amount) external onlyOwner reentrancyGuard {
// can withdraw any amount up to the account balance (0 will withdraw everything)
uint balance = address(this).balance;
if(amount == 0 || amount > balance) amount = balance;
// make the withdrawal
(bool success, ) = treasury.call{value:amount}("");
require(success, "transfer failed");
}
// the owner can pay funds in at any time although this is not needed
// perhaps the contract needs to hold a certain balance in future for some external requirement
function treasuryIn() external payable onlyOwner {
}
/// BATCHING
// all normal ERC721 read functions can be batched
// this allows for any user or app to look up all their tokens in a single call or via paging
function tokenByIndexBatch(uint256[] memory indexes) public view virtual returns (uint256[] memory) {
uint256[] memory batch = new uint256[](indexes.length);
for (uint256 i = 0; i < indexes.length; i++) {
batch[i] = tokenByIndex(indexes[i]);
}
return batch;
}
function balanceOfBatch(address[] memory owners) external view virtual returns (uint256[] memory) {
uint256[] memory batch = new uint256[](owners.length);
for (uint256 i = 0; i < owners.length; i++) {
batch[i] = balanceOf(owners[i]);
}
return batch;
}
function ownerOfBatch(uint256[] memory tokenIds) external view virtual returns (address[] memory) {
address[] memory batch = new address[](tokenIds.length);
for (uint256 i = 0; i < tokenIds.length; i++) {
batch[i] = ownerOf(tokenIds[i]);
}
return batch;
}
function tokenURIBatch(uint256[] memory tokenIds) external view virtual returns (string[] memory) {
string[] memory batch = new string[](tokenIds.length);
for (uint256 i = 0; i < tokenIds.length; i++) {
batch[i] = tokenURI(tokenIds[i]);
}
return batch;
}
function getApprovedBatch(uint256[] memory tokenIds) external view virtual returns (address[] memory) {
address[] memory batch = new address[](tokenIds.length);
for (uint256 i = 0; i < tokenIds.length; i++) {
batch[i] = getApproved(tokenIds[i]);
}
return batch;
}
function tokenOfOwnerByIndexBatch(address owner_, uint256[] memory indexes) external view virtual returns (uint256[] memory) {
uint256[] memory batch = new uint256[](indexes.length);
for (uint256 i = 0; i < indexes.length; i++) {
batch[i] = tokenOfOwnerByIndex(owner_, indexes[i]);
}
return batch;
}
}
// SPDX-License-Identifier: MIT
pragma solidity 0.8.7;
import "@openzeppelin/contracts/utils/Context.sol";
/**
* This is a modified version of the standard OpenZeppelin Ownable contract that allows for a recovery address to be used to recover ownership
*
*
* @dev Contract module which provides a basic access control mechanism, where
* there is an account (an owner) that can be granted exclusive access to
* specific functions.
*
* By default, the owner account will be the one that deploys the contract. This
* can later be changed with {transferOwnership}.
*
* This module is used through inheritance. It will make available the modifier
* `onlyOwner`, which can be applied to your functions to restrict their use to
* the owner.
*/
abstract contract OwnableRecoverable is Context {
address private _owner;
// the recovery address can be used to recover ownership if the owner wallet is ever lost
// it should be a cold-storage wallet stored in a vault and never used for any other operation
// it should be set in the parent constructor
// if ownership moves to a new organization then the recovery address should be moved too
address public recovery;
// initializes the contract setting the deployer as the initial owner.
constructor () {
_setOwner(_msgSender());
}
/**
* @dev Returns the address of the current owner.
*/
function owner() public view virtual returns (address) {
return _owner;
}
/**
* @dev Throws if called by any account other than the owner.
*/
modifier onlyOwner() {
require(owner() == _msgSender(), "caller is not the owner");
_;
}
modifier onlyOwnerOrRecovery() {
require(_msgSender() == owner() || _msgSender() == recovery, "caller is not the owner or recovery");
_;
}
/**
* @dev Transfers ownership of the contract to a new account (`newOwner`).
* Can only be called by the current owner.
*/
function transferOwnership(address newOwner) public virtual onlyOwnerOrRecovery {
require(newOwner != address(0), "cant use 0 address");
_setOwner(newOwner);
}
function _setOwner(address newOwner) private {
_owner = newOwner;
}
// the recovery address can be changed by the owner or the recovery address
function setRecovery(address newRecovery) public virtual onlyOwnerOrRecovery {
require(newRecovery != address(0), "cant use 0 address");
recovery = newRecovery;
}
}
// SPDX-License-Identifier: MIT
pragma solidity ^0.8.0;
import "../utils/Context.sol";
/**
* @dev Contract module which allows children to implement an emergency stop
* mechanism that can be triggered by an authorized account.
*
* This module is used through inheritance. It will make available the
* modifiers `whenNotPaused` and `whenPaused`, which can be applied to
* the functions of your contract. Note that they will not be pausable by
* simply including this module, only once the modifiers are put in place.
*/
abstract contract Pausable is Context {
/**
* @dev Emitted when the pause is triggered by `account`.
*/
event Paused(address account);
/**
* @dev Emitted when the pause is lifted by `account`.
*/
event Unpaused(address account);
bool private _paused;
/**
* @dev Initializes the contract in unpaused state.
*/
constructor() {
_paused = false;
}
/**
* @dev Returns true if the contract is paused, and false otherwise.
*/
function paused() public view virtual returns (bool) {
return _paused;
}
/**
* @dev Modifier to make a function callable only when the contract is not paused.
*
* Requirements:
*
* - The contract must not be paused.
*/
modifier whenNotPaused() {
require(!paused(), "Pausable: paused");
_;
}
/**
* @dev Modifier to make a function callable only when the contract is paused.
*
* Requirements:
*
* - The contract must be paused.
*/
modifier whenPaused() {
require(paused(), "Pausable: not paused");
_;
}
/**
* @dev Triggers stopped state.
*
* Requirements:
*
* - The contract must not be paused.
*/
function _pause() internal virtual whenNotPaused {
_paused = true;
emit Paused(_msgSender());
}
/**
* @dev Returns to normal state.
*
* Requirements:
*
* - The contract must be paused.
*/
function _unpause() internal virtual whenPaused {
_paused = false;
emit Unpaused(_msgSender());
}
}
// SPDX-License-Identifier: MIT
pragma solidity ^0.8.0;
import "./IERC721.sol";
import "./IERC721Receiver.sol";
import "./extensions/IERC721Metadata.sol";
import "../../utils/Address.sol";
import "../../utils/Context.sol";
import "../../utils/Strings.sol";
import "../../utils/introspection/ERC165.sol";
/**
* @dev Implementation of https://eips.ethereum.org/EIPS/eip-721[ERC721] Non-Fungible Token Standard, including
* the Metadata extension, but not including the Enumerable extension, which is available separately as
* {ERC721Enumerable}.
*/
contract ERC721 is Context, ERC165, IERC721, IERC721Metadata {
using Address for address;
using Strings for uint256;
// Token name
string private _name;
// Token symbol
string private _symbol;
// Mapping from token ID to owner address
mapping(uint256 => address) private _owners;
// Mapping owner address to token count
mapping(address => uint256) private _balances;
// Mapping from token ID to approved address
mapping(uint256 => address) private _tokenApprovals;
// Mapping from owner to operator approvals
mapping(address => mapping(address => bool)) private _operatorApprovals;
/**
* @dev Initializes the contract by setting a `name` and a `symbol` to the token collection.
*/
constructor(string memory name_, string memory symbol_) {
_name = name_;
_symbol = symbol_;
}
/**
* @dev See {IERC165-supportsInterface}.
*/
function supportsInterface(bytes4 interfaceId) public view virtual override(ERC165, IERC165) returns (bool) {
return
interfaceId == type(IERC721).interfaceId ||
interfaceId == type(IERC721Metadata).interfaceId ||
super.supportsInterface(interfaceId);
}
/**
* @dev See {IERC721-balanceOf}.
*/
function balanceOf(address owner) public view virtual override returns (uint256) {
require(owner != address(0), "ERC721: balance query for the zero address");
return _balances[owner];
}
/**
* @dev See {IERC721-ownerOf}.
*/
function ownerOf(uint256 tokenId) public view virtual override returns (address) {
address owner = _owners[tokenId];
require(owner != address(0), "ERC721: owner query for nonexistent token");
return owner;
}
/**
* @dev See {IERC721Metadata-name}.
*/
function name() public view virtual override returns (string memory) {
return _name;
}
/**
* @dev See {IERC721Metadata-symbol}.
*/
function symbol() public view virtual override returns (string memory) {
return _symbol;
}
/**
* @dev See {IERC721Metadata-tokenURI}.
*/
function tokenURI(uint256 tokenId) public view virtual override returns (string memory) {
require(_exists(tokenId), "ERC721Metadata: URI query for nonexistent token");
string memory baseURI = _baseURI();
return bytes(baseURI).length > 0 ? string(abi.encodePacked(baseURI, tokenId.toString())) : "";
}
/**
* @dev Base URI for computing {tokenURI}. If set, the resulting URI for each
* token will be the concatenation of the `baseURI` and the `tokenId`. Empty
* by default, can be overriden in child contracts.
*/
function _baseURI() internal view virtual returns (string memory) {
return "";
}
/**
* @dev See {IERC721-approve}.
*/
function approve(address to, uint256 tokenId) public virtual override {
address owner = ERC721.ownerOf(tokenId);
require(to != owner, "ERC721: approval to current owner");
require(
_msgSender() == owner || isApprovedForAll(owner, _msgSender()),
"ERC721: approve caller is not owner nor approved for all"
);
_approve(to, tokenId);
}
/**
* @dev See {IERC721-getApproved}.
*/
function getApproved(uint256 tokenId) public view virtual override returns (address) {
require(_exists(tokenId), "ERC721: approved query for nonexistent token");
return _tokenApprovals[tokenId];
}
/**
* @dev See {IERC721-setApprovalForAll}.
*/
function setApprovalForAll(address operator, bool approved) public virtual override {
require(operator != _msgSender(), "ERC721: approve to caller");
_operatorApprovals[_msgSender()][operator] = approved;
emit ApprovalForAll(_msgSender(), operator, approved);
}
/**
* @dev See {IERC721-isApprovedForAll}.
*/
function isApprovedForAll(address owner, address operator) public view virtual override returns (bool) {
return _operatorApprovals[owner][operator];
}
/**
* @dev See {IERC721-transferFrom}.
*/
function transferFrom(
address from,
address to,
uint256 tokenId
) public virtual override {
//solhint-disable-next-line max-line-length
require(_isApprovedOrOwner(_msgSender(), tokenId), "ERC721: transfer caller is not owner nor approved");
_transfer(from, to, tokenId);
}
/**
* @dev See {IERC721-safeTransferFrom}.
*/
function safeTransferFrom(
address from,
address to,
uint256 tokenId
) public virtual override {
safeTransferFrom(from, to, tokenId, "");
}
/**
* @dev See {IERC721-safeTransferFrom}.
*/
function safeTransferFrom(
address from,
address to,
uint256 tokenId,
bytes memory _data
) public virtual override {
require(_isApprovedOrOwner(_msgSender(), tokenId), "ERC721: transfer caller is not owner nor approved");
_safeTransfer(from, to, tokenId, _data);
}
/**
* @dev Safely transfers `tokenId` token from `from` to `to`, checking first that contract recipients
* are aware of the ERC721 protocol to prevent tokens from being forever locked.
*
* `_data` is additional data, it has no specified format and it is sent in call to `to`.
*
* This internal function is equivalent to {safeTransferFrom}, and can be used to e.g.
* implement alternative mechanisms to perform token transfer, such as signature-based.
*
* Requirements:
*
* - `from` cannot be the zero address.
* - `to` cannot be the zero address.
* - `tokenId` token must exist and be owned by `from`.
* - If `to` refers to a smart contract, it must implement {IERC721Receiver-onERC721Received}, which is called upon a safe transfer.
*
* Emits a {Transfer} event.
*/
function _safeTransfer(
address from,
address to,
uint256 tokenId,
bytes memory _data
) internal virtual {
_transfer(from, to, tokenId);
require(_checkOnERC721Received(from, to, tokenId, _data), "ERC721: transfer to non ERC721Receiver implementer");
}
/**
* @dev Returns whether `tokenId` exists.
*
* Tokens can be managed by their owner or approved accounts via {approve} or {setApprovalForAll}.
*
* Tokens start existing when they are minted (`_mint`),
* and stop existing when they are burned (`_burn`).
*/
function _exists(uint256 tokenId) internal view virtual returns (bool) {
return _owners[tokenId] != address(0);
}
/**
* @dev Returns whether `spender` is allowed to manage `tokenId`.
*
* Requirements:
*
* - `tokenId` must exist.
*/
function _isApprovedOrOwner(address spender, uint256 tokenId) internal view virtual returns (bool) {
require(_exists(tokenId), "ERC721: operator query for nonexistent token");
address owner = ERC721.ownerOf(tokenId);
return (spender == owner || getApproved(tokenId) == spender || isApprovedForAll(owner, spender));
}
/**
* @dev Safely mints `tokenId` and transfers it to `to`.
*
* Requirements:
*
* - `tokenId` must not exist.
* - If `to` refers to a smart contract, it must implement {IERC721Receiver-onERC721Received}, which is called upon a safe transfer.
*
* Emits a {Transfer} event.
*/
function _safeMint(address to, uint256 tokenId) internal virtual {
_safeMint(to, tokenId, "");
}
/**
* @dev Same as {xref-ERC721-_safeMint-address-uint256-}[`_safeMint`], with an additional `data` parameter which is
* forwarded in {IERC721Receiver-onERC721Received} to contract recipients.
*/
function _safeMint(
address to,
uint256 tokenId,
bytes memory _data
) internal virtual {
_mint(to, tokenId);
require(
_checkOnERC721Received(address(0), to, tokenId, _data),
"ERC721: transfer to non ERC721Receiver implementer"
);
}
/**
* @dev Mints `tokenId` and transfers it to `to`.
*
* WARNING: Usage of this method is discouraged, use {_safeMint} whenever possible
*
* Requirements:
*
* - `tokenId` must not exist.
* - `to` cannot be the zero address.
*
* Emits a {Transfer} event.
*/
function _mint(address to, uint256 tokenId) internal virtual {
require(to != address(0), "ERC721: mint to the zero address");
require(!_exists(tokenId), "ERC721: token already minted");
_beforeTokenTransfer(address(0), to, tokenId);
_balances[to] += 1;
_owners[tokenId] = to;
emit Transfer(address(0), to, tokenId);
}
/**
* @dev Destroys `tokenId`.
* The approval is cleared when the token is burned.
*
* Requirements:
*
* - `tokenId` must exist.
*
* Emits a {Transfer} event.
*/
function _burn(uint256 tokenId) internal virtual {
address owner = ERC721.ownerOf(tokenId);
_beforeTokenTransfer(owner, address(0), tokenId);
// Clear approvals
_approve(address(0), tokenId);
_balances[owner] -= 1;
delete _owners[tokenId];
emit Transfer(owner, address(0), tokenId);
}
/**
* @dev Transfers `tokenId` from `from` to `to`.
* As opposed to {transferFrom}, this imposes no restrictions on msg.sender.
*
* Requirements:
*
* - `to` cannot be the zero address.
* - `tokenId` token must be owned by `from`.
*
* Emits a {Transfer} event.
*/
function _transfer(
address from,
address to,
uint256 tokenId
) internal virtual {
require(ERC721.ownerOf(tokenId) == from, "ERC721: transfer of token that is not own");
require(to != address(0), "ERC721: transfer to the zero address");
_beforeTokenTransfer(from, to, tokenId);
// Clear approvals from the previous owner
_approve(address(0), tokenId);
_balances[from] -= 1;
_balances[to] += 1;
_owners[tokenId] = to;
emit Transfer(from, to, tokenId);
}
/**
* @dev Approve `to` to operate on `tokenId`
*
* Emits a {Approval} event.
*/
function _approve(address to, uint256 tokenId) internal virtual {
_tokenApprovals[tokenId] = to;
emit Approval(ERC721.ownerOf(tokenId), to, tokenId);
}
/**
* @dev Internal function to invoke {IERC721Receiver-onERC721Received} on a target address.
* The call is not executed if the target address is not a contract.
*
* @param from address representing the previous owner of the given token ID
* @param to target address that will receive the tokens
* @param tokenId uint256 ID of the token to be transferred
* @param _data bytes optional data to send along with the call
* @return bool whether the call correctly returned the expected magic value
*/
function _checkOnERC721Received(
address from,
address to,
uint256 tokenId,
bytes memory _data
) private returns (bool) {
if (to.isContract()) {
try IERC721Receiver(to).onERC721Received(_msgSender(), from, tokenId, _data) returns (bytes4 retval) {
return retval == IERC721Receiver.onERC721Received.selector;
} catch (bytes memory reason) {
if (reason.length == 0) {
revert("ERC721: transfer to non ERC721Receiver implementer");
} else {
assembly {
revert(add(32, reason), mload(reason))
}
}
}
} else {
return true;
}
}
/**
* @dev Hook that is called before any token transfer. This includes minting
* and burning.
*
* Calling conditions:
*
* - When `from` and `to` are both non-zero, ``from``'s `tokenId` will be
* transferred to `to`.
* - When `from` is zero, `tokenId` will be minted for `to`.
* - When `to` is zero, ``from``'s `tokenId` will be burned.
* - `from` and `to` are never both zero.
*
* To learn more about hooks, head to xref:ROOT:extending-contracts.adoc#using-hooks[Using Hooks].
*/
function _beforeTokenTransfer(
address from,
address to,
uint256 tokenId
) internal virtual {}
}
// SPDX-License-Identifier: MIT
pragma solidity ^0.8.0;
import "../../utils/introspection/IERC165.sol";
/**
* @dev Required interface of an ERC721 compliant contract.
*/
interface IERC721 is IERC165 {
/**
* @dev Emitted when `tokenId` token is transferred from `from` to `to`.
*/
event Transfer(address indexed from, address indexed to, uint256 indexed tokenId);
/**
* @dev Emitted when `owner` enables `approved` to manage the `tokenId` token.
*/
event Approval(address indexed owner, address indexed approved, uint256 indexed tokenId);
/**
* @dev Emitted when `owner` enables or disables (`approved`) `operator` to manage all of its assets.
*/
event ApprovalForAll(address indexed owner, address indexed operator, bool approved);
/**
* @dev Returns the number of tokens in ``owner``'s account.
*/
function balanceOf(address owner) external view returns (uint256 balance);
/**
* @dev Returns the owner of the `tokenId` token.
*
* Requirements:
*
* - `tokenId` must exist.
*/
function ownerOf(uint256 tokenId) external view returns (address owner);
/**
* @dev Safely transfers `tokenId` token from `from` to `to`, checking first that contract recipients
* are aware of the ERC721 protocol to prevent tokens from being forever locked.
*
* Requirements:
*
* - `from` cannot be the zero address.
* - `to` cannot be the zero address.
* - `tokenId` token must exist and be owned by `from`.
* - If the caller is not `from`, it must be have been allowed to move this token by either {approve} or {setApprovalForAll}.
* - If `to` refers to a smart contract, it must implement {IERC721Receiver-onERC721Received}, which is called upon a safe transfer.
*
* Emits a {Transfer} event.
*/
function safeTransferFrom(
address from,
address to,
uint256 tokenId
) external;
/**
* @dev Transfers `tokenId` token from `from` to `to`.
*
* WARNING: Usage of this method is discouraged, use {safeTransferFrom} whenever possible.
*
* Requirements:
*
* - `from` cannot be the zero address.
* - `to` cannot be the zero address.
* - `tokenId` token must be owned by `from`.
* - If the caller is not `from`, it must be approved to move this token by either {approve} or {setApprovalForAll}.
*
* Emits a {Transfer} event.
*/
function transferFrom(
address from,
address to,
uint256 tokenId
) external;
/**
* @dev Gives permission to `to` to transfer `tokenId` token to another account.
* The approval is cleared when the token is transferred.
*
* Only a single account can be approved at a time, so approving the zero address clears previous approvals.
*
* Requirements:
*
* - The caller must own the token or be an approved operator.
* - `tokenId` must exist.
*
* Emits an {Approval} event.
*/
function approve(address to, uint256 tokenId) external;
/**
* @dev Returns the account approved for `tokenId` token.
*
* Requirements:
*
* - `tokenId` must exist.
*/
function getApproved(uint256 tokenId) external view returns (address operator);
/**
* @dev Approve or remove `operator` as an operator for the caller.
* Operators can call {transferFrom} or {safeTransferFrom} for any token owned by the caller.
*
* Requirements:
*
* - The `operator` cannot be the caller.
*
* Emits an {ApprovalForAll} event.
*/
function setApprovalForAll(address operator, bool _approved) external;
/**
* @dev Returns if the `operator` is allowed to manage all of the assets of `owner`.
*
* See {setApprovalForAll}
*/
function isApprovedForAll(address owner, address operator) external view returns (bool);
/**
* @dev Safely transfers `tokenId` token from `from` to `to`.
*
* Requirements:
*
* - `from` cannot be the zero address.
* - `to` cannot be the zero address.
* - `tokenId` token must exist and be owned by `from`.
* - If the caller is not `from`, it must be approved to move this token by either {approve} or {setApprovalForAll}.
* - If `to` refers to a smart contract, it must implement {IERC721Receiver-onERC721Received}, which is called upon a safe transfer.
*
* Emits a {Transfer} event.
*/
function safeTransferFrom(
address from,
address to,
uint256 tokenId,
bytes calldata data
) external;
}
// SPDX-License-Identifier: MIT
pragma solidity ^0.8.0;
/**
* @title ERC721 token receiver interface
* @dev Interface for any contract that wants to support safeTransfers
* from ERC721 asset contracts.
*/
interface IERC721Receiver {
/**
* @dev Whenever an {IERC721} `tokenId` token is transferred to this contract via {IERC721-safeTransferFrom}
* by `operator` from `from`, this function is called.
*
* It must return its Solidity selector to confirm the token transfer.
* If any other value is returned or the interface is not implemented by the recipient, the transfer will be reverted.
*
* The selector can be obtained in Solidity with `IERC721.onERC721Received.selector`.
*/
function onERC721Received(
address operator,
address from,
uint256 tokenId,
bytes calldata data
) external returns (bytes4);
}
// SPDX-License-Identifier: MIT
pragma solidity ^0.8.0;
import "../ERC721.sol";
import "./IERC721Enumerable.sol";
/**
* @dev This implements an optional extension of {ERC721} defined in the EIP that adds
* enumerability of all the token ids in the contract as well as all token ids owned by each
* account.
*/
abstract contract ERC721Enumerable is ERC721, IERC721Enumerable {
// Mapping from owner to list of owned token IDs
mapping(address => mapping(uint256 => uint256)) private _ownedTokens;
// Mapping from token ID to index of the owner tokens list
mapping(uint256 => uint256) private _ownedTokensIndex;
// Array with all token ids, used for enumeration
uint256[] private _allTokens;
// Mapping from token id to position in the allTokens array
mapping(uint256 => uint256) private _allTokensIndex;
/**
* @dev See {IERC165-supportsInterface}.
*/
function supportsInterface(bytes4 interfaceId) public view virtual override(IERC165, ERC721) returns (bool) {
return interfaceId == type(IERC721Enumerable).interfaceId || super.supportsInterface(interfaceId);
}
/**
* @dev See {IERC721Enumerable-tokenOfOwnerByIndex}.
*/
function tokenOfOwnerByIndex(address owner, uint256 index) public view virtual override returns (uint256) {
require(index < ERC721.balanceOf(owner), "ERC721Enumerable: owner index out of bounds");
return _ownedTokens[owner][index];
}
/**
* @dev See {IERC721Enumerable-totalSupply}.
*/
function totalSupply() public view virtual override returns (uint256) {
return _allTokens.length;
}
/**
* @dev See {IERC721Enumerable-tokenByIndex}.
*/
function tokenByIndex(uint256 index) public view virtual override returns (uint256) {
require(index < ERC721Enumerable.totalSupply(), "ERC721Enumerable: global index out of bounds");
return _allTokens[index];
}
/**
* @dev Hook that is called before any token transfer. This includes minting
* and burning.
*
* Calling conditions:
*
* - When `from` and `to` are both non-zero, ``from``'s `tokenId` will be
* transferred to `to`.
* - When `from` is zero, `tokenId` will be minted for `to`.
* - When `to` is zero, ``from``'s `tokenId` will be burned.
* - `from` cannot be the zero address.
* - `to` cannot be the zero address.
*
* To learn more about hooks, head to xref:ROOT:extending-contracts.adoc#using-hooks[Using Hooks].
*/
function _beforeTokenTransfer(
address from,
address to,
uint256 tokenId
) internal virtual override {
super._beforeTokenTransfer(from, to, tokenId);
if (from == address(0)) {
_addTokenToAllTokensEnumeration(tokenId);
} else if (from != to) {
_removeTokenFromOwnerEnumeration(from, tokenId);
}
if (to == address(0)) {
_removeTokenFromAllTokensEnumeration(tokenId);
} else if (to != from) {
_addTokenToOwnerEnumeration(to, tokenId);
}
}
/**
* @dev Private function to add a token to this extension's ownership-tracking data structures.
* @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 _addTokenToOwnerEnumeration(address to, uint256 tokenId) private {
uint256 length = ERC721.balanceOf(to);
_ownedTokens[to][length] = tokenId;
_ownedTokensIndex[tokenId] = length;
}
/**
* @dev Private function to add a token to this extension's token tracking data structures.
* @param tokenId uint256 ID of the token to be added to the tokens list
*/
function _addTokenToAllTokensEnumeration(uint256 tokenId) private {
_allTokensIndex[tokenId] = _allTokens.length;
_allTokens.push(tokenId);
}
/**
* @dev Private function to remove a token from this extension's ownership-tracking data structures. Note that
* while the token is not assigned a new owner, the `_ownedTokensIndex` mapping is _not_ updated: this allows for
* gas optimizations e.g. when performing a transfer operation (avoiding double writes).
* This has O(1) time complexity, but alters the order of the _ownedTokens array.
* @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 _removeTokenFromOwnerEnumeration(address from, uint256 tokenId) private {
// To prevent a gap in from's tokens array, we store the last token in the index of the token to delete, and
// then delete the last slot (swap and pop).
uint256 lastTokenIndex = ERC721.balanceOf(from) - 1;
uint256 tokenIndex = _ownedTokensIndex[tokenId];
// When the token to delete is the last token, the swap operation is unnecessary
if (tokenIndex != lastTokenIndex) {
uint256 lastTokenId = _ownedTokens[from][lastTokenIndex];
_ownedTokens[from][tokenIndex] = lastTokenId; // Move the last token to the slot of the to-delete token
_ownedTokensIndex[lastTokenId] = tokenIndex; // Update the moved token's index
}
// This also deletes the contents at the last position of the array
delete _ownedTokensIndex[tokenId];
delete _ownedTokens[from][lastTokenIndex];
}
/**
* @dev Private function to remove a token from this extension's token tracking data structures.
* This has O(1) time complexity, but alters the order of the _allTokens array.
* @param tokenId uint256 ID of the token to be removed from the tokens list
*/
function _removeTokenFromAllTokensEnumeration(uint256 tokenId) private {
// To prevent a gap in the tokens array, we store the last token in the index of the token to delete, and
// then delete the last slot (swap and pop).
uint256 lastTokenIndex = _allTokens.length - 1;
uint256 tokenIndex = _allTokensIndex[tokenId];
// When the token to delete is the last token, the swap operation is unnecessary. However, since this occurs so
// rarely (when the last minted token is burnt) that we still do the swap here to avoid the gas cost of adding
// an 'if' statement (like in _removeTokenFromOwnerEnumeration)
uint256 lastTokenId = _allTokens[lastTokenIndex];
_allTokens[tokenIndex] = lastTokenId; // Move the last token to the slot of the to-delete token
_allTokensIndex[lastTokenId] = tokenIndex; // Update the moved token's index
// This also deletes the contents at the last position of the array
delete _allTokensIndex[tokenId];
_allTokens.pop();
}
}
// SPDX-License-Identifier: MIT
pragma solidity ^0.8.0;
import "../IERC721.sol";
/**
* @title ERC-721 Non-Fungible Token Standard, optional enumeration extension
* @dev See https://eips.ethereum.org/EIPS/eip-721
*/
interface IERC721Enumerable is IERC721 {
/**
* @dev Returns the total amount of tokens stored by the contract.
*/
function totalSupply() external view returns (uint256);
/**
* @dev Returns a token ID owned by `owner` at a given `index` of its token list.
* Use along with {balanceOf} to enumerate all of ``owner``'s tokens.
*/
function tokenOfOwnerByIndex(address owner, uint256 index) external view returns (uint256 tokenId);
/**
* @dev Returns a token ID at a given `index` of all the tokens stored by the contract.
* Use along with {totalSupply} to enumerate all tokens.
*/
function tokenByIndex(uint256 index) external view returns (uint256);
}
// SPDX-License-Identifier: MIT
pragma solidity ^0.8.0;
import "../IERC721.sol";
/**
* @title ERC-721 Non-Fungible Token Standard, optional metadata extension
* @dev See https://eips.ethereum.org/EIPS/eip-721
*/
interface IERC721Metadata is IERC721 {
/**
* @dev Returns the token collection name.
*/
function name() external view returns (string memory);
/**
* @dev Returns the token collection symbol.
*/
function symbol() external view returns (string memory);
/**
* @dev Returns the Uniform Resource Identifier (URI) for `tokenId` token.
*/
function tokenURI(uint256 tokenId) external view returns (string memory);
}
// SPDX-License-Identifier: MIT
pragma solidity ^0.8.0;
/**
* @dev Collection of functions related to the address type
*/
library Address {
/**
* @dev Returns true if `account` is a contract.
*
* [IMPORTANT]
* ====
* It is unsafe to assume that an address for which this function returns
* false is an externally-owned account (EOA) and not a contract.
*
* Among others, `isContract` will return false for the following
* types of addresses:
*
* - an externally-owned account
* - a contract in construction
* - an address where a contract will be created
* - an address where a contract lived, but was destroyed
* ====
*/
function isContract(address account) internal view returns (bool) {
// This method relies on extcodesize, which returns 0 for contracts in
// construction, since the code is only stored at the end of the
// constructor execution.
uint256 size;
assembly {
size := extcodesize(account)
}
return size > 0;
}
/**
* @dev Replacement for Solidity's `transfer`: sends `amount` wei to
* `recipient`, forwarding all available gas and reverting on errors.
*
* https://eips.ethereum.org/EIPS/eip-1884[EIP1884] increases the gas cost
* of certain opcodes, possibly making contracts go over the 2300 gas limit
* imposed by `transfer`, making them unable to receive funds via
* `transfer`. {sendValue} removes this limitation.
*
* https://diligence.consensys.net/posts/2019/09/stop-using-soliditys-transfer-now/[Learn more].
*
* IMPORTANT: because control is transferred to `recipient`, care must be
* taken to not create reentrancy vulnerabilities. Consider using
* {ReentrancyGuard} or the
* https://solidity.readthedocs.io/en/v0.5.11/security-considerations.html#use-the-checks-effects-interactions-pattern[checks-effects-interactions pattern].
*/
function sendValue(address payable recipient, uint256 amount) internal {
require(address(this).balance >= amount, "Address: insufficient balance");
(bool success, ) = recipient.call{value: amount}("");
require(success, "Address: unable to send value, recipient may have reverted");
}
/**
* @dev Performs a Solidity function call using a low level `call`. A
* plain `call` is an unsafe replacement for a function call: use this
* function instead.
*
* If `target` reverts with a revert reason, it is bubbled up by this
* function (like regular Solidity function calls).
*
* Returns the raw returned data. To convert to the expected return value,
* use https://solidity.readthedocs.io/en/latest/units-and-global-variables.html?highlight=abi.decode#abi-encoding-and-decoding-functions[`abi.decode`].
*
* Requirements:
*
* - `target` must be a contract.
* - calling `target` with `data` must not revert.
*
* _Available since v3.1._
*/
function functionCall(address target, bytes memory data) internal returns (bytes memory) {
return functionCall(target, data, "Address: low-level call failed");
}
/**
* @dev Same as {xref-Address-functionCall-address-bytes-}[`functionCall`], but with
* `errorMessage` as a fallback revert reason when `target` reverts.
*
* _Available since v3.1._
*/
function functionCall(
address target,
bytes memory data,
string memory errorMessage
) internal returns (bytes memory) {
return functionCallWithValue(target, data, 0, errorMessage);
}
/**
* @dev Same as {xref-Address-functionCall-address-bytes-}[`functionCall`],
* but also transferring `value` wei to `target`.
*
* Requirements:
*
* - the calling contract must have an ETH balance of at least `value`.
* - the called Solidity function must be `payable`.
*
* _Available since v3.1._
*/
function functionCallWithValue(
address target,
bytes memory data,
uint256 value
) internal returns (bytes memory) {
return functionCallWithValue(target, data, value, "Address: low-level call with value failed");
}
/**
* @dev Same as {xref-Address-functionCallWithValue-address-bytes-uint256-}[`functionCallWithValue`], but
* with `errorMessage` as a fallback revert reason when `target` reverts.
*
* _Available since v3.1._
*/
function functionCallWithValue(
address target,
bytes memory data,
uint256 value,
string memory errorMessage
) internal returns (bytes memory) {
require(address(this).balance >= value, "Address: insufficient balance for call");
require(isContract(target), "Address: call to non-contract");
(bool success, bytes memory returndata) = target.call{value: value}(data);
return verifyCallResult(success, returndata, errorMessage);
}
/**
* @dev Same as {xref-Address-functionCall-address-bytes-}[`functionCall`],
* but performing a static call.
*
* _Available since v3.3._
*/
function functionStaticCall(address target, bytes memory data) internal view returns (bytes memory) {
return functionStaticCall(target, data, "Address: low-level static call failed");
}
/**
* @dev Same as {xref-Address-functionCall-address-bytes-string-}[`functionCall`],
* but performing a static call.
*
* _Available since v3.3._
*/
function functionStaticCall(
address target,
bytes memory data,
string memory errorMessage
) internal view returns (bytes memory) {
require(isContract(target), "Address: static call to non-contract");
(bool success, bytes memory returndata) = target.staticcall(data);
return verifyCallResult(success, returndata, errorMessage);
}
/**
* @dev Same as {xref-Address-functionCall-address-bytes-}[`functionCall`],
* but performing a delegate call.
*
* _Available since v3.4._
*/
function functionDelegateCall(address target, bytes memory data) internal returns (bytes memory) {
return functionDelegateCall(target, data, "Address: low-level delegate call failed");
}
/**
* @dev Same as {xref-Address-functionCall-address-bytes-string-}[`functionCall`],
* but performing a delegate call.
*
* _Available since v3.4._
*/
function functionDelegateCall(
address target,
bytes memory data,
string memory errorMessage
) internal returns (bytes memory) {
require(isContract(target), "Address: delegate call to non-contract");
(bool success, bytes memory returndata) = target.delegatecall(data);
return verifyCallResult(success, returndata, errorMessage);
}
/**
* @dev Tool to verifies that a low level call was successful, and revert if it wasn't, either by bubbling the
* revert reason using the provided one.
*
* _Available since v4.3._
*/
function verifyCallResult(
bool success,
bytes memory returndata,
string memory errorMessage
) internal pure returns (bytes memory) {
if (success) {
return returndata;
} else {
// Look for revert reason and bubble it up if present
if (returndata.length > 0) {
// The easiest way to bubble the revert reason is using memory via assembly
assembly {
let returndata_size := mload(returndata)
revert(add(32, returndata), returndata_size)
}
} else {
revert(errorMessage);
}
}
}
}
// SPDX-License-Identifier: MIT
pragma solidity ^0.8.0;
/**
* @dev Provides information about the current execution context, including the
* sender of the transaction and its data. While these are generally available
* via msg.sender and msg.data, they should not be accessed in such a direct
* manner, since when dealing with meta-transactions the account sending and
* paying for execution may not be the actual sender (as far as an application
* is concerned).
*
* This contract is only required for intermediate, library-like contracts.
*/
abstract contract Context {
function _msgSender() internal view virtual returns (address) {
return msg.sender;
}
function _msgData() internal view virtual returns (bytes calldata) {
return msg.data;
}
}
// SPDX-License-Identifier: MIT
pragma solidity ^0.8.0;
/**
* @dev String operations.
*/
library Strings {
bytes16 private constant _HEX_SYMBOLS = "0123456789abcdef";
/**
* @dev Converts a `uint256` to its ASCII `string` decimal representation.
*/
function toString(uint256 value) internal pure returns (string memory) {
// Inspired by OraclizeAPI's implementation - MIT licence
// https://github.com/oraclize/ethereum-api/blob/b42146b063c7d6ee1358846c198246239e9360e8/oraclizeAPI_0.4.25.sol
if (value == 0) {
return "0";
}
uint256 temp = value;
uint256 digits;
while (temp != 0) {
digits++;
temp /= 10;
}
bytes memory buffer = new bytes(digits);
while (value != 0) {
digits -= 1;
buffer[digits] = bytes1(uint8(48 + uint256(value % 10)));
value /= 10;
}
return string(buffer);
}
/**
* @dev Converts a `uint256` to its ASCII `string` hexadecimal representation.
*/
function toHexString(uint256 value) internal pure returns (string memory) {
if (value == 0) {
return "0x00";
}
uint256 temp = value;
uint256 length = 0;
while (temp != 0) {
length++;
temp >>= 8;
}
return toHexString(value, length);
}
/**
* @dev Converts a `uint256` to its ASCII `string` hexadecimal representation with fixed length.
*/
function toHexString(uint256 value, uint256 length) internal pure returns (string memory) {
bytes memory buffer = new bytes(2 * length + 2);
buffer[0] = "0";
buffer[1] = "x";
for (uint256 i = 2 * length + 1; i > 1; --i) {
buffer[i] = _HEX_SYMBOLS[value & 0xf];
value >>= 4;
}
require(value == 0, "Strings: hex length insufficient");
return string(buffer);
}
}
// SPDX-License-Identifier: MIT
pragma solidity ^0.8.0;
import "./IERC165.sol";
/**
* @dev Implementation of the {IERC165} interface.
*
* Contracts that want to implement ERC165 should inherit from this contract and override {supportsInterface} to check
* for the additional interface id that will be supported. For example:
*
* ```solidity
* function supportsInterface(bytes4 interfaceId) public view virtual override returns (bool) {
* return interfaceId == type(MyInterface).interfaceId || super.supportsInterface(interfaceId);
* }
* ```
*
* Alternatively, {ERC165Storage} provides an easier to use but more expensive implementation.
*/
abstract contract ERC165 is IERC165 {
/**
* @dev See {IERC165-supportsInterface}.
*/
function supportsInterface(bytes4 interfaceId) public view virtual override returns (bool) {
return interfaceId == type(IERC165).interfaceId;
}
}
// SPDX-License-Identifier: MIT
pragma solidity ^0.8.0;
/**
* @dev Interface of the ERC165 standard, as defined in the
* https://eips.ethereum.org/EIPS/eip-165[EIP].
*
* Implementers can declare support of contract interfaces, which can then be
* queried by others ({ERC165Checker}).
*
* For an implementation, see {ERC165}.
*/
interface IERC165 {
/**
* @dev Returns true if this contract implements the interface defined by
* `interfaceId`. See the corresponding
* https://eips.ethereum.org/EIPS/eip-165#how-interfaces-are-identified[EIP section]
* to learn more about how these ids are created.
*
* This function call must use less than 30 000 gas.
*/
function supportsInterface(bytes4 interfaceId) external view returns (bool);
}