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QRC20X.sol
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QRC20X.sol
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// SPDX-License-Identifier: MIT
pragma solidity ^0.8.0; // Note: You must have a version of SolidityX to compile this contract.
/**
* @dev Implementation of the {IERC20} interface for cross-chain transfers.
*
* This implementation is agnostic to the way tokens are created. This means
* that a supply mechanism has to be added in a derived contract using {_mint}.
* For a generic mechanism see {ERC20PresetMinterPauser}.
*
* We have followed general OpenZeppelin Contracts guidelines: functions revert
* instead returning `false` on failure. This behavior is nonetheless
* conventional and does not conflict with the expectations of ERC20
* applications.
*
* Additionally, an {Approval} event is emitted on calls to {transferFrom}.
* This allows applications to reconstruct the allowance for all accounts just
* by listening to said events. Other implementations of the EIP may not emit
* these events, as it isn't required by the specification.
*
* Finally, the non-standard {decreaseAllowance} and {increaseAllowance}
* functions have been added to mitigate the well-known issues around setting
* allowances. See {IERC20-approve}.
*/
contract QRC20 {
mapping(address => uint256) private _balances;
mapping(address => mapping(address => uint256)) private _allowances;
// List of external token contracts that can send tokens to users on this chain
address[12] public ApprovedAddresses;
uint256 private _totalSupply;
string private _name;
string private _symbol;
address private _deployer;
mapping(uint8 => uint8) public PrefixToLocation;
mapping(uint8 => bool) public ValidPrefixes;
/**
* @dev Emitted when `value` tokens are moved from one account (`from`) to
* another (`to`).
*
* Note that `value` may be zero.
*/
event Transfer(address indexed from, address indexed to, uint256 value);
event ExternalTransfer(address indexed from, address indexed to, uint256 value);
/**
* @dev Emitted when the allowance of a `spender` for an `owner` is set by
* a call to {approve}. `value` is the new allowance.
*/
event Approval(address indexed owner, address indexed spender, uint256 value);
/**
* @dev Sets the values for {name} and {symbol}.
*
* The default value of {decimals} is 18. To select a different value for
* {decimals} you should overload it.
*
* All two of these values are immutable: they can only be set once during
* construction.
*/
constructor(string memory name_, string memory symbol_, uint256 initialSupply_) {
_name = name_;
_symbol = symbol_;
_deployer = msg.sender;
_mint(_deployer, initialSupply_);
PrefixToLocation[0] = 0; // zone 0-0 // cyprus1
PrefixToLocation[1] = 1; // zone 0-1 // cyprus2
PrefixToLocation[2] = 2; // zone 0-2 // cyprus3
PrefixToLocation[16] = 3; // zone 1-0 // paxos1
PrefixToLocation[17] = 4; // zone 1-1 // paxos2
PrefixToLocation[18] = 5; // zone 1-2 // paxos3
PrefixToLocation[32] = 6; // zone 2-0 // hydra1
PrefixToLocation[33] = 7; // zone 2-1 // hydra2
PrefixToLocation[34] = 8; // zone 2-2 // hydra3
ValidPrefixes[0] = true;
ValidPrefixes[1] = true;
ValidPrefixes[2] = true;
ValidPrefixes[16] = true;
ValidPrefixes[17] = true;
ValidPrefixes[18] = true;
ValidPrefixes[32] = true;
ValidPrefixes[33] = true;
ValidPrefixes[34] = true;
}
/**
* @dev Returns the name of the token.
*/
function name() public view returns (string memory) {
return _name;
}
/**
* @dev Returns the symbol of the token, usually a shorter version of the
* name.
*/
function symbol() public view returns (string memory) {
return _symbol;
}
/**
* @dev Returns the number of decimals used to get its user representation.
* For example, if `decimals` equals `2`, a balance of `505` tokens should
* be displayed to a user as `5.05` (`505 / 10 ** 2`).
*
* Tokens usually opt for a value of 18, imitating the relationship between
* Ether and Wei. This is the value {ERC20} uses, unless this function is
* overridden;
*
* NOTE: This information is only used for _display_ purposes: it in
* no way affects any of the arithmetic of the contract, including
* {IERC20-balanceOf} and {IERC20-transfer}.
*/
function decimals() public view returns (uint8) {
return 18;
}
/**
* @dev See {IERC20-totalSupply}.
*/
function totalSupply() public view returns (uint256) {
return _totalSupply;
}
/**
* @dev See {IERC20-balanceOf}.
*/
function balanceOf(address account) public view returns (uint256) {
return _balances[account];
}
/**
* @dev See {IERC20-transfer}.
*
* Requirements:
*
* - `to` cannot be the zero address or an external address.
* - the caller must have a balance of at least `amount`.
*/
function transfer(address to, uint256 amount) public returns (bool) {
_transfer(msg.sender, to, amount);
return true;
}
/**
* This function sends tokens to an address on another chain by creating an external transaction (ETX).
* This function uses opETX which constructs an external transaction and adds it to the block.
* The ETX will make its way over to the destination and automatically execute when the given base fee is correct.
* `to` must be an address on a different chain. The chain of a given address is determined by the first byte of the address.
* gasLimit, minerTip and basefee are for executing the transaction on the destination chain. Choose these carefully.
* The base fee and miner tip are in Wei and may not be the same as they are on your current chain.
* If the base fee or miner tip are too low, the ETX will wait in the destination chain until they are high enough to be added in a block.
* You must send a value with the function call equal to the following amount: (baseFee + minerTip) * gasLimit
*/
function crossChainTransfer(address to, uint256 amount, uint256 gasLimit, uint256 minerTip, uint256 baseFee) public payable {
bool isInternal;
assembly {
isInternal := isaddrinternal(to)
}
require(!isInternal, "Address is not external");
_burn(msg.sender, amount);
address toAddr = ApprovedAddresses[getAddressLocation(to)];
require(toAddr != address(0), "Token is not available on the destination chain");
uint totalGas = (baseFee + minerTip) * gasLimit;
require(msg.value >= totalGas, string(abi.encodePacked("Not enough gas sent, need at least ", uint2str(totalGas), " wei")));
bytes memory encoded = abi.encodeWithSignature("incomingTransfer(address,uint256)", to, amount);
bool success; // this is not used. opETX only returns false if there was an error in creating the ETX, not executing it.
assembly {
success := etx(
0, // temp variable, can be anything (unused)
toAddr, // address to send to
0, // amount to send in wei
gasLimit, // gas limit (entire gas limit will be consumed and sent to destination)
minerTip, // miner tip in wei
baseFee, // base fee in wei
add(encoded, 0x20), // input offset in memory (the first 32 byte number is just the size of the array)
mload(encoded), // input size in memory (loading the first number gives the size)
0, // accesslist offset in memory
0 // accesslist size in memory
)
}
emit ExternalTransfer(msg.sender, to, amount);
}
/**
* This function is used by an emitted ETX to send tokens to the sender.
* The sending contract must be an approved token contract for its respective chain.
*/
function incomingTransfer(address to, uint256 amount) public {
require(ApprovedAddresses[getAddressLocation(msg.sender)] == msg.sender, string(abi.encodePacked("Sender ", abi.encodePacked(msg.sender), " not approved")));
_mint(to, amount);
}
/**
* @dev See {IERC20-allowance}.
*/
function allowance(address owner, address spender) public view returns (uint256) {
return _allowances[owner][spender];
}
/**
* @dev See {IERC20-approve}.
*
* NOTE: If `amount` is the maximum `uint256`, the allowance is not updated on
* `transferFrom`. This is semantically equivalent to an infinite approval.
*
* Requirements:
*
* - `spender` cannot be the zero address.
*/
function approve(address spender, uint256 amount) public returns (bool) {
_approve(msg.sender, spender, amount);
return true;
}
/**
* @dev See {IERC20-transferFrom}.
*
* Emits an {Approval} event indicating the updated allowance. This is not
* required by the EIP. See the note at the beginning of {ERC20}.
*
* NOTE: Does not update the allowance if the current allowance
* is the maximum `uint256`.
*
* Requirements:
*
* - `from` and `to` cannot be the zero address.
* - `from` must have a balance of at least `amount`.
* - the caller must have allowance for ``from``'s tokens of at least
* `amount`.
*/
function transferFrom(
address from,
address to,
uint256 amount
) public returns (bool) { // TODO: Allow this to work cross-chain (crossChainTransferFrom)
_spendAllowance(from, msg.sender, amount);
_transfer(from, to, amount);
return true;
}
/**
* @dev Atomically increases the allowance granted to `spender` by the caller.
*
* This is an alternative to {approve} that can be used as a mitigation for
* problems described in {IERC20-approve}.
*
* Emits an {Approval} event indicating the updated allowance.
*
* Requirements:
*
* - `spender` cannot be the zero address.
*/
function increaseAllowance(address spender, uint256 addedValue) public returns (bool) {
address owner = msg.sender;
_approve(owner, spender, allowance(owner, spender) + addedValue);
return true;
}
/**
* @dev Atomically decreases the allowance granted to `spender` by the caller.
*
* This is an alternative to {approve} that can be used as a mitigation for
* problems described in {IERC20-approve}.
*
* Emits an {Approval} event indicating the updated allowance.
*
* Requirements:
*
* - `spender` cannot be the zero address.
* - `spender` must have allowance for the caller of at least
* `subtractedValue`.
*/
function decreaseAllowance(address spender, uint256 subtractedValue) public returns (bool) {
address owner = msg.sender;
uint256 currentAllowance = allowance(owner, spender);
require(currentAllowance >= subtractedValue, "ERC20: decreased allowance below zero");
unchecked {
_approve(owner, spender, currentAllowance - subtractedValue);
}
return true;
}
/**
* @dev Moves `amount` of tokens from `from` to `to`.
*
* This internal function is equivalent to {transfer}, and can be used to
* e.g. implement automatic token fees, slashing mechanisms, etc.
*
* Emits a {Transfer} event.
*
* Requirements:
*
* - `from` cannot be the zero address.
* - `to` cannot be the zero address.
* - `from` must have a balance of at least `amount`.
*/
function _transfer(
address from,
address to,
uint256 amount
) internal {
bool isInternal;
assembly {
isInternal := isaddrinternal(to) // This opcode returns true if an address is internal
}
require(isInternal, "Address is external. Use cross-chain transfer function.");
require(from != address(0), "ERC20: transfer from the zero address");
require(to != address(0), "ERC20: transfer to the zero address");
_beforeTokenTransfer(from, to, amount);
uint256 fromBalance = _balances[from];
require(fromBalance >= amount, "ERC20: transfer amount exceeds balance");
unchecked {
_balances[from] = fromBalance - amount;
// Overflow not possible: the sum of all balances is capped by totalSupply, and the sum is preserved by
// decrementing then incrementing.
_balances[to] += amount;
}
emit Transfer(from, to, amount);
_afterTokenTransfer(from, to, amount);
}
/** @dev Creates `amount` tokens and assigns them to `account`, increasing
* the total supply.
*
* Emits a {Transfer} event with `from` set to the zero address.
*
* Requirements:
*
* - `account` cannot be the zero address.
*/
function _mint(address account, uint256 amount) internal {
require(account != address(0), "ERC20: mint to the zero address");
_beforeTokenTransfer(address(0), account, amount);
_totalSupply += amount;
unchecked {
// Overflow not possible: balance + amount is at most totalSupply + amount, which is checked above.
_balances[account] += amount;
}
emit Transfer(address(0), account, amount);
_afterTokenTransfer(address(0), account, amount);
}
/**
* @dev Destroys `amount` tokens from `account`, reducing the
* total supply.
*
* Emits a {Transfer} event with `to` set to the zero address.
*
* Requirements:
*
* - `account` cannot be the zero address.
* - `account` must have at least `amount` tokens.
*/
function _burn(address account, uint256 amount) internal {
require(account != address(0), "ERC20: burn from the zero address");
_beforeTokenTransfer(account, address(0), amount);
uint256 accountBalance = _balances[account];
require(accountBalance >= amount, "ERC20: burn amount exceeds balance");
unchecked {
_balances[account] = accountBalance - amount;
// Overflow not possible: amount <= accountBalance <= totalSupply.
_totalSupply -= amount;
}
emit Transfer(account, address(0), amount);
_afterTokenTransfer(account, address(0), amount);
}
/**
* @dev Sets `amount` as the allowance of `spender` over the `owner` s tokens.
*
* This internal function is equivalent to `approve`, and can be used to
* e.g. set automatic allowances for certain subsystems, etc.
*
* Emits an {Approval} event.
*
* Requirements:
*
* - `owner` cannot be the zero address.
* - `spender` cannot be the zero address.
*/
function _approve(
address owner,
address spender,
uint256 amount
) internal {
bool isInternal;
assembly {
isInternal := isaddrinternal(spender) // This opcode returns true if an address is internal
}
require(isInternal, "Spender address is external. Use cross-chain transfer function.");
require(owner != address(0), "ERC20: approve from the zero address");
require(spender != address(0), "ERC20: approve to the zero address");
_allowances[owner][spender] = amount;
emit Approval(owner, spender, amount);
}
/**
* @dev Updates `owner` s allowance for `spender` based on spent `amount`.
*
* Does not update the allowance amount in case of infinite allowance.
* Revert if not enough allowance is available.
*
* Might emit an {Approval} event.
*/
function _spendAllowance(
address owner,
address spender,
uint256 amount
) internal {
uint256 currentAllowance = allowance(owner, spender);
if (currentAllowance != type(uint256).max) {
require(currentAllowance >= amount, "ERC20: insufficient allowance");
unchecked {
_approve(owner, spender, currentAllowance - amount);
}
}
}
/**
* @dev Hook that is called before any transfer of tokens. This includes
* minting and burning.
*
* Calling conditions:
*
* - when `from` and `to` are both non-zero, `amount` of ``from``'s tokens
* will be transferred to `to`.
* - when `from` is zero, `amount` tokens will be minted for `to`.
* - when `to` is zero, `amount` of ``from``'s tokens 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 amount
) internal {}
/**
* @dev Hook that is called after any transfer of tokens. This includes
* minting and burning.
*
* Calling conditions:
*
* - when `from` and `to` are both non-zero, `amount` of ``from``'s tokens
* has been transferred to `to`.
* - when `from` is zero, `amount` tokens have been minted for `to`.
* - when `to` is zero, `amount` of ``from``'s tokens have been 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 _afterTokenTransfer(
address from,
address to,
uint256 amount
) internal {}
/**
* This function allows the deployer to add an external address for the token contract on a different chain.
* Note that the deployer can only add one address per chain and this address cannot be changed afterwards.
* Be very careful when adding an address here.
*/
function AddApprovedAddress(uint8 chain, address addr) public {
bool isInternal;
assembly {
isInternal := isaddrinternal(addr)
}
require(!isInternal, "Address is not external");
require(msg.sender == _deployer, "Sender is not deployer");
require(chain < 9, "Max 9 zones");
require(ApprovedAddresses[chain] == address(0), "The approved address for this zone already exists");
ApprovedAddresses[chain] = addr;
}
/**
* This function allows the deployer to add external addresses for the token contract on different chains.
* Note that the deployer can only add one address per chain and this address cannot be changed afterwards.
* In comparison to AddApprovedAddress, this function allows the address(es) to be internal so that the same
* approved list can be used for every instance of the contract on each chain.
* Be very careful when adding addresses here.
*/
function AddApprovedAddresses(uint8[] calldata chain, address[] calldata addr) external {
require(msg.sender == _deployer, "Sender is not deployer");
require(chain.length == addr.length, "chain and address arrays must be the same length");
for(uint8 i = 0; i < chain.length; i++) {
require(chain[i] < 9, "Max 9 zones");
require(ApprovedAddresses[chain[i]] == address(0), "The approved address for this zone already exists");
ApprovedAddresses[chain[i]] = addr[i];
}
}
// This function uses the stored prefix list to determine an address's location based on its first byte.
function getAddressLocation(address addr) public view returns (uint8) {
uint8 prefix = uint8(toBytes(addr)[0]);
if (ValidPrefixes[prefix]) {
return PrefixToLocation[prefix];
}
revert("Invalid Location");
}
function toBytes(address a) public pure returns (bytes memory) {
return abi.encodePacked(a);
}
function uint2str(uint _i) internal pure returns (string memory _uintAsString) {
if (_i == 0) {
return "0";
}
uint j = _i;
uint len;
while (j != 0) {
len++;
j /= 10;
}
bytes memory bstr = new bytes(len);
uint k = len;
while (_i != 0) {
k = k-1;
uint8 temp = (48 + uint8(_i - _i / 10 * 10));
bytes1 b1 = bytes1(temp);
bstr[k] = b1;
_i /= 10;
}
return string(bstr);
}
}