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TetherToken.sol - Tether.to USD
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pragma solidity ^0.4.11; | |
/** | |
* Math operations with safety checks | |
*/ | |
library SafeMath { | |
function mul(uint a, uint b) internal returns (uint) { | |
uint c = a * b; | |
assert(a == 0 || c / a == b); | |
return c; | |
} | |
function div(uint a, uint b) internal returns (uint) { | |
// assert(b > 0); // Solidity automatically throws when dividing by 0 | |
uint c = a / b; | |
// assert(a == b * c + a % b); // There is no case in which this doesn't hold | |
return c; | |
} | |
function sub(uint a, uint b) internal returns (uint) { | |
assert(b <= a); | |
return a - b; | |
} | |
function add(uint a, uint b) internal returns (uint) { | |
uint c = a + b; | |
assert(c >= a); | |
return c; | |
} | |
function max64(uint64 a, uint64 b) internal constant returns (uint64) { | |
return a >= b ? a : b; | |
} | |
function min64(uint64 a, uint64 b) internal constant returns (uint64) { | |
return a < b ? a : b; | |
} | |
function max256(uint256 a, uint256 b) internal constant returns (uint256) { | |
return a >= b ? a : b; | |
} | |
function min256(uint256 a, uint256 b) internal constant returns (uint256) { | |
return a < b ? a : b; | |
} | |
function assert(bool assertion) internal { | |
if (!assertion) { | |
throw; | |
} | |
} | |
} | |
/** | |
* @title Ownable | |
* @dev The Ownable contract has an owner address, and provides basic authorization control | |
* functions, this simplifies the implementation of "user permissions". | |
*/ | |
contract Ownable { | |
address public owner; | |
/** | |
* @dev The Ownable constructor sets the original `owner` of the contract to the sender | |
* account. | |
*/ | |
function Ownable() { | |
owner = msg.sender; | |
} | |
/** | |
* @dev Throws if called by any account other than the owner. | |
*/ | |
modifier onlyOwner() { | |
if (msg.sender != owner) { | |
throw; | |
} | |
_; | |
} | |
/** | |
* @dev Allows the current owner to transfer control of the contract to a newOwner. | |
* @param newOwner The address to transfer ownership to. | |
*/ | |
function transferOwnership(address newOwner) onlyOwner { | |
if (newOwner != address(0)) { | |
owner = newOwner; | |
} | |
} | |
} | |
/** | |
* @title Pausable | |
* @dev Base contract which allows children to implement an emergency stop mechanism. | |
*/ | |
contract Pausable is Ownable { | |
event Pause(); | |
event Unpause(); | |
bool public paused = false; | |
/** | |
* @dev modifier to allow actions only when the contract IS paused | |
*/ | |
modifier whenNotPaused() { | |
if (paused) throw; | |
_; | |
} | |
/** | |
* @dev modifier to allow actions only when the contract IS NOT paused | |
*/ | |
modifier whenPaused { | |
if (!paused) throw; | |
_; | |
} | |
/** | |
* @dev called by the owner to pause, triggers stopped state | |
*/ | |
function pause() onlyOwner whenNotPaused returns (bool) { | |
paused = true; | |
Pause(); | |
return true; | |
} | |
/** | |
* @dev called by the owner to unpause, returns to normal state | |
*/ | |
function unpause() onlyOwner whenPaused returns (bool) { | |
paused = false; | |
Unpause(); | |
return true; | |
} | |
} | |
/** | |
* @title ERC20Basic | |
* @dev Simpler version of ERC20 interface | |
* @dev see https://github.com/ethereum/EIPs/issues/20 | |
*/ | |
contract ERC20Basic { | |
uint public _totalSupply; | |
function totalSupply() constant returns (uint); | |
function balanceOf(address who) constant returns (uint); | |
function transfer(address to, uint value); | |
event Transfer(address indexed from, address indexed to, uint value); | |
} | |
/** | |
* @title ERC20 interface | |
* @dev see https://github.com/ethereum/EIPs/issues/20 | |
*/ | |
contract ERC20 is ERC20Basic { | |
function allowance(address owner, address spender) constant returns (uint); | |
function transferFrom(address from, address to, uint value); | |
function approve(address spender, uint value); | |
event Approval(address indexed owner, address indexed spender, uint value); | |
} | |
/** | |
* @title Basic token | |
* @dev Basic version of StandardToken, with no allowances. | |
*/ | |
contract BasicToken is Ownable, ERC20Basic { | |
using SafeMath for uint; | |
mapping(address => uint) balances; | |
// additional variables for use if transaction fees ever became necessary | |
uint public basisPointsRate = 0; | |
uint public maximumFee = 0; | |
/** | |
* @dev Fix for the ERC20 short address attack. | |
*/ | |
modifier onlyPayloadSize(uint size) { | |
if(msg.data.length < size + 4) { | |
throw; | |
} | |
_; | |
} | |
/** | |
* @dev transfer token for a specified address | |
* @param _to The address to transfer to. | |
* @param _value The amount to be transferred. | |
*/ | |
function transfer(address _to, uint _value) onlyPayloadSize(2 * 32) { | |
uint fee = (_value.mul(basisPointsRate)).div(10000); | |
if (fee > maximumFee) { | |
fee = maximumFee; | |
} | |
uint sendAmount = _value.sub(fee); | |
balances[msg.sender] = balances[msg.sender].sub(_value); | |
balances[_to] = balances[_to].add(sendAmount); | |
balances[owner] = balances[owner].add(fee); | |
Transfer(msg.sender, _to, sendAmount); | |
Transfer(msg.sender, owner, fee); | |
} | |
/** | |
* @dev Gets the balance of the specified address. | |
* @param _owner The address to query the the balance of. | |
* @return An uint representing the amount owned by the passed address. | |
*/ | |
function balanceOf(address _owner) constant returns (uint balance) { | |
return balances[_owner]; | |
} | |
} | |
/** | |
* @title Standard ERC20 token | |
* | |
* @dev Implementation of the basic standard token. | |
* @dev https://github.com/ethereum/EIPs/issues/20 | |
* @dev Based on code by FirstBlood: https://github.com/Firstbloodio/token/blob/master/smart_contract/FirstBloodToken.sol | |
*/ | |
contract StandardToken is BasicToken, ERC20 { | |
mapping (address => mapping (address => uint)) allowed; | |
uint constant MAX_UINT = 2**256 - 1; | |
/** | |
* @dev Transfer tokens from one address to another | |
* @param _from address The address which you want to send tokens from | |
* @param _to address The address which you want to transfer to | |
* @param _value uint the amount of tokens to be transferred | |
*/ | |
function transferFrom(address _from, address _to, uint _value) onlyPayloadSize(3 * 32) { | |
var _allowance = allowed[_from][msg.sender]; | |
// Check is not needed because sub(_allowance, _value) will already throw if this condition is not met | |
// if (_value > _allowance) throw; | |
uint fee = (_value.mul(basisPointsRate)).div(10000); | |
if (fee > maximumFee) { | |
fee = maximumFee; | |
} | |
uint sendAmount = _value.sub(fee); | |
balances[_to] = balances[_to].add(sendAmount); | |
balances[owner] = balances[owner].add(fee); | |
balances[_from] = balances[_from].sub(_value); | |
if (_allowance < MAX_UINT) { | |
allowed[_from][msg.sender] = _allowance.sub(_value); | |
} | |
Transfer(_from, _to, sendAmount); | |
Transfer(_from, owner, fee); | |
} | |
/** | |
* @dev Approve the passed address to spend the specified amount of tokens on behalf of msg.sender. | |
* @param _spender The address which will spend the funds. | |
* @param _value The amount of tokens to be spent. | |
*/ | |
function approve(address _spender, uint _value) onlyPayloadSize(2 * 32) { | |
// To change the approve amount you first have to reduce the addresses` | |
// allowance to zero by calling `approve(_spender, 0)` if it is not | |
// already 0 to mitigate the race condition described here: | |
// https://github.com/ethereum/EIPs/issues/20#issuecomment-263524729 | |
if ((_value != 0) && (allowed[msg.sender][_spender] != 0)) throw; | |
allowed[msg.sender][_spender] = _value; | |
Approval(msg.sender, _spender, _value); | |
} | |
/** | |
* @dev Function to check the amount of tokens than an owner allowed to a spender. | |
* @param _owner address The address which owns the funds. | |
* @param _spender address The address which will spend the funds. | |
* @return A uint specifying the amount of tokens still available for the spender. | |
*/ | |
function allowance(address _owner, address _spender) constant returns (uint remaining) { | |
return allowed[_owner][_spender]; | |
} | |
} | |
contract UpgradedStandardToken is StandardToken{ | |
// those methods are called by the legacy contract | |
// and they must ensure msg.sender to be the contract address | |
function transferByLegacy(address from, address to, uint value); | |
function transferFromByLegacy(address sender, address from, address spender, uint value); | |
function approveByLegacy(address from, address spender, uint value); | |
} | |
/// @title - Tether Token Contract - Tether.to | |
/// @author Enrico Rubboli - <enrico@bitfinex.com> | |
/// @author Will Harborne - <will@ethfinex.com> | |
contract TetherToken is Pausable, StandardToken { | |
string public name; | |
string public symbol; | |
uint public decimals; | |
address public upgradedAddress; | |
bool public deprecated; | |
// The contract can be initialized with a number of tokens | |
// All the tokens are deposited to the owner address | |
// | |
// @param _balance Initial supply of the contract | |
// @param _name Token Name | |
// @param _symbol Token symbol | |
// @param _decimals Token decimals | |
function TetherToken(uint _initialSupply, string _name, string _symbol, uint _decimals){ | |
_totalSupply = _initialSupply; | |
name = _name; | |
symbol = _symbol; | |
decimals = _decimals; | |
balances[owner] = _initialSupply; | |
deprecated = false; | |
} | |
// Forward ERC20 methods to upgraded contract if this one is deprecated | |
function transfer(address _to, uint _value) whenNotPaused { | |
if (deprecated) { | |
return UpgradedStandardToken(upgradedAddress).transferByLegacy(msg.sender, _to, _value); | |
} else { | |
return super.transfer(_to, _value); | |
} | |
} | |
// Forward ERC20 methods to upgraded contract if this one is deprecated | |
function transferFrom(address _from, address _to, uint _value) whenNotPaused { | |
if (deprecated) { | |
return UpgradedStandardToken(upgradedAddress).transferFromByLegacy(msg.sender, _from, _to, _value); | |
} else { | |
return super.transferFrom(_from, _to, _value); | |
} | |
} | |
// Forward ERC20 methods to upgraded contract if this one is deprecated | |
function balanceOf(address who) constant returns (uint){ | |
if (deprecated) { | |
return UpgradedStandardToken(upgradedAddress).balanceOf(who); | |
} else { | |
return super.balanceOf(who); | |
} | |
} | |
// Forward ERC20 methods to upgraded contract if this one is deprecated | |
function approve(address _spender, uint _value) onlyPayloadSize(2 * 32) { | |
if (deprecated) { | |
return UpgradedStandardToken(upgradedAddress).approveByLegacy(msg.sender, _spender, _value); | |
} else { | |
return super.approve(_spender, _value); | |
} | |
} | |
// Forward ERC20 methods to upgraded contract if this one is deprecated | |
function allowance(address _owner, address _spender) constant returns (uint remaining) { | |
if (deprecated) { | |
return StandardToken(upgradedAddress).allowance(_owner, _spender); | |
} else { | |
return super.allowance(_owner, _spender); | |
} | |
} | |
// deprecate current contract in favour of a new one | |
function deprecate(address _upgradedAddress) onlyOwner { | |
deprecated = true; | |
upgradedAddress = _upgradedAddress; | |
Deprecate(_upgradedAddress); | |
} | |
// deprecate current contract if favour of a new one | |
function totalSupply() constant returns (uint){ | |
if (deprecated) { | |
return StandardToken(upgradedAddress).totalSupply(); | |
} else { | |
return _totalSupply; | |
} | |
} | |
// Issue a new amount of tokens | |
// these tokens are deposited into the owner address | |
// | |
// @param _amount Number of tokens to be issued | |
function issue(uint amount) onlyOwner { | |
if (_totalSupply + amount < _totalSupply) throw; | |
if (balances[owner] + amount < balances[owner]) throw; | |
balances[owner] += amount; | |
_totalSupply += amount; | |
Issue(amount); | |
} | |
// Redeem tokens. | |
// These tokens are withdrawn from the owner address | |
// if the balance must be enough to cover the redeem | |
// or the call will fail. | |
// @param _amount Number of tokens to be issued | |
function redeem(uint amount) onlyOwner { | |
if (_totalSupply < amount) throw; | |
if (balances[owner] < amount) throw; | |
_totalSupply -= amount; | |
balances[owner] -= amount; | |
Redeem(amount); | |
} | |
function setParams(uint newBasisPoints, uint newMaxFee) onlyOwner { | |
// Ensure transparency by hardcoding limit beyond which fees can never be added | |
if (newBasisPoints > 20) throw; | |
if (newMaxFee > 50) throw; | |
basisPointsRate = newBasisPoints; | |
maximumFee = newMaxFee.mul(10**decimals); | |
Params(basisPointsRate, maximumFee); | |
} | |
// Called when new token are issued | |
event Issue(uint amount); | |
// Called when tokens are redeemed | |
event Redeem(uint amount); | |
// Called when contract is deprecated | |
event Deprecate(address newAddress); | |
// Called if contract ever adds fees | |
event Params(uint feeBasisPoints, uint maxFee); | |
} |
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