Contract Source Code:
File 1 of 1 : WeToken
pragma solidity ^0.4.13;
contract Receiver {
function tokenFallback(address from, uint value, bytes data);
}
/*
* ERC20 interface
* see https://github.com/ethereum/EIPs/issues/20
*/
contract ERC20 {
uint public totalSupply;
function balanceOf(address who) public constant returns (uint);
function allowance(address owner, address spender) public constant returns (uint);
function transfer(address to, uint value) public returns (bool ok);
function transferFrom(address from, address to, uint value) public returns (bool ok);
function approve(address spender, uint value) public returns (bool ok);
event Transfer(address indexed from, address indexed to, uint value);
event Approval(address indexed owner, address indexed spender, uint value);
}
/**
* Math operations with safety checks
*/
contract SafeMath {
function safeMul(uint a, uint b) internal returns (uint) {
uint c = a * b;
assert(a == 0 || c / a == b);
return c;
}
function safeDiv(uint a, uint b) internal returns (uint) {
assert(b > 0);
uint c = a / b;
assert(a == b * c + a % b);
return c;
}
function safeSub(uint a, uint b) internal returns (uint) {
assert(b <= a);
return a - b;
}
function safeAdd(uint a, uint b) internal returns (uint) {
uint c = a + b;
assert(c>=a && c>=b);
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) {
revert();
}
}
}
/**
* Standard ERC20 token with Short Hand Attack and approve() race condition mitigation.
*
* Based on code by FirstBlood:
* https://github.com/Firstbloodio/token/blob/master/smart_contract/FirstBloodToken.sol
*/
contract StandardToken is ERC20, SafeMath {
event Transfer(address indexed from, address indexed to, uint indexed value, bytes data);
/* Token supply got increased and a new owner received these tokens */
event Minted(address receiver, uint amount);
/* Actual balances of token holders */
mapping(address => uint) balances;
/* approve() allowances */
mapping (address => mapping (address => uint)) allowed;
/**
*
* Fix for the ERC20 short address attack
*
* http://vessenes.com/the-erc20-short-address-attack-explained/
*/
modifier onlyPayloadSize(uint size) {
if(msg.data.length != size + 4) {
revert();
}
_;
}
function transfer(address _to, uint _value) onlyPayloadSize(2 * 32) public returns (bool success) {
bytes memory _empty;
return transfer(_to, _value, _empty);
}
function transfer(address _to, uint _value, bytes _data) public returns (bool success) {
balances[msg.sender] = safeSub(balances[msg.sender], _value);
balances[_to] = safeAdd(balances[_to], _value);
Transfer(msg.sender, _to, _value, _data);
Transfer(msg.sender, _to, _value);
if (isContract(_to)) {
Receiver(_to).tokenFallback(msg.sender, _value, _data);
}
return true;
}
// ERC223 fetch contract size (must be nonzero to be a contract)
function isContract( address _addr ) private returns (bool) {
uint length;
_addr = _addr;
assembly { length := extcodesize(_addr) }
return (length > 0);
}
function transferFrom(address _from, address _to, uint _value) public returns (bool success) {
uint _allowance = allowed[_from][msg.sender];
// Check is not needed because safeSub(_allowance, _value) will already throw if this condition is not met
// if (_value > _allowance) revert();
balances[_to] = safeAdd(balances[_to], _value);
balances[_from] = safeSub(balances[_from], _value);
allowed[_from][msg.sender] = safeSub(_allowance, _value);
Transfer(_from, _to, _value);
return true;
}
function balanceOf(address _owner) public constant returns (uint balance) {
return balances[_owner];
}
function approve(address _spender, uint _value) public returns (bool success) {
// 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)) revert();
allowed[msg.sender][_spender] = _value;
Approval(msg.sender, _spender, _value);
return true;
}
function allowance(address _owner, address _spender) public constant returns (uint remaining) {
return allowed[_owner][_spender];
}
/**
* Atomic increment of approved spending
*
* Works around https://github.com/ethereum/EIPs/issues/20#issuecomment-263524729
*
*/
function addApproval(address _spender, uint _addedValue) public
onlyPayloadSize(2 * 32)
returns (bool success) {
uint oldValue = allowed[msg.sender][_spender];
allowed[msg.sender][_spender] = safeAdd(oldValue, _addedValue);
Approval(msg.sender, _spender, allowed[msg.sender][_spender]);
return true;
}
/**
* Atomic decrement of approved spending.
*
* Works around https://github.com/ethereum/EIPs/issues/20#issuecomment-263524729
*/
function subApproval(address _spender, uint _subtractedValue) public
onlyPayloadSize(2 * 32)
returns (bool success) {
uint oldVal = allowed[msg.sender][_spender];
if (_subtractedValue > oldVal) {
allowed[msg.sender][_spender] = 0;
} else {
allowed[msg.sender][_spender] = safeSub(oldVal, _subtractedValue);
}
Approval(msg.sender, _spender, allowed[msg.sender][_spender]);
return true;
}
}
contract BurnableToken is StandardToken {
address public constant BURN_ADDRESS = 0;
/** How many tokens we burned */
event Burned(address burner, uint burnedAmount);
/**
* Burn extra tokens from a balance.
*
*/
function burn(uint burnAmount) public {
address burner = msg.sender;
balances[burner] = safeSub(balances[burner], burnAmount);
totalSupply = safeSub(totalSupply, burnAmount);
Burned(burner, burnAmount);
}
}
/**
* Upgrade agent interface inspired by Lunyr.
*
* Upgrade agent transfers tokens to a new contract.
* Upgrade agent itself can be the token contract, or just a middle man contract doing the heavy lifting.
*/
contract UpgradeAgent {
uint public originalSupply;
/** Interface marker */
function isUpgradeAgent() public constant returns (bool) {
return true;
}
function upgradeFrom(address _from, uint256 _value) public;
}
/**
* A token upgrade mechanism where users can opt-in amount of tokens to the next smart contract revision.
*
* First envisioned by Golem and Lunyr projects.
*/
contract UpgradeableToken is StandardToken {
/** Contract / person who can set the upgrade path. This can be the same as team multisig wallet, as what it is with its default value. */
address public upgradeMaster;
/** The next contract where the tokens will be migrated. */
UpgradeAgent public upgradeAgent;
/** How many tokens we have upgraded by now. */
uint256 public totalUpgraded;
/**
* Upgrade states.
*
* - NotAllowed: The child contract has not reached a condition where the upgrade can bgun
* - WaitingForAgent: Token allows upgrade, but we don't have a new agent yet
* - ReadyToUpgrade: The agent is set, but not a single token has been upgraded yet
* - Upgrading: Upgrade agent is set and the balance holders can upgrade their tokens
*
*/
enum UpgradeState {Unknown, NotAllowed, WaitingForAgent, ReadyToUpgrade, Upgrading}
/**
* Somebody has upgraded some of his tokens.
*/
event Upgrade(address indexed _from, address indexed _to, uint256 _value);
/**
* New upgrade agent available.
*/
event UpgradeAgentSet(address agent);
/**
* Do not allow construction without upgrade master set.
*/
function UpgradeableToken(address _upgradeMaster) public {
upgradeMaster = _upgradeMaster;
}
/**
* Allow the token holder to upgrade some of their tokens to a new contract.
*/
function upgrade(uint256 value) public {
UpgradeState state = getUpgradeState();
if(!(state == UpgradeState.ReadyToUpgrade || state == UpgradeState.Upgrading)) {
// Called in a bad state
revert();
}
// Validate input value.
if (value == 0) revert();
balances[msg.sender] = safeSub(balances[msg.sender], value);
// Take tokens out from circulation
totalSupply = safeSub(totalSupply, value);
totalUpgraded = safeAdd(totalUpgraded, value);
// Upgrade agent reissues the tokens
upgradeAgent.upgradeFrom(msg.sender, value);
Upgrade(msg.sender, upgradeAgent, value);
}
/**
* Set an upgrade agent that handles
*/
function setUpgradeAgent(address agent) external {
if(!canUpgrade()) {
// The token is not yet in a state that we could think upgrading
revert();
}
if (agent == 0x0) revert();
// Only a master can designate the next agent
if (msg.sender != upgradeMaster) revert();
// Upgrade has already begun for an agent
if (getUpgradeState() == UpgradeState.Upgrading) revert();
upgradeAgent = UpgradeAgent(agent);
// Bad interface
if(!upgradeAgent.isUpgradeAgent()) revert();
// Make sure that token supplies match in source and target
if (upgradeAgent.originalSupply() != totalSupply) revert();
UpgradeAgentSet(upgradeAgent);
}
/**
* Get the state of the token upgrade.
*/
function getUpgradeState() public constant returns(UpgradeState) {
if(!canUpgrade()) return UpgradeState.NotAllowed;
else if(address(upgradeAgent) == 0x00) return UpgradeState.WaitingForAgent;
else if(totalUpgraded == 0) return UpgradeState.ReadyToUpgrade;
else return UpgradeState.Upgrading;
}
/**
* Change the upgrade master.
*
* This allows us to set a new owner for the upgrade mechanism.
*/
function setUpgradeMaster(address master) public {
if (master == 0x0) revert();
if (msg.sender != upgradeMaster) revert();
upgradeMaster = master;
}
/**
* Child contract can enable to provide the condition when the upgrade can begun.
*/
function canUpgrade() public constant returns(bool) {
return true;
}
}
contract WeToken is BurnableToken, UpgradeableToken {
string public name;
string public symbol;
uint public decimals;
address public owner;
bool public mintingFinished = false;
mapping(address => uint) public previligedBalances;
/** List of agents that are allowed to create new tokens */
mapping(address => bool) public mintAgents;
event MintingAgentChanged(address addr, bool state);
modifier onlyOwner() {
if(msg.sender != owner) revert();
_;
}
modifier onlyMintAgent() {
// Only crowdsale contracts are allowed to mint new tokens
if(!mintAgents[msg.sender]) revert();
_;
}
/** Make sure we are not done yet. */
modifier canMint() {
if(mintingFinished) revert();
_;
}
modifier onlyNotSame(address _from, address _to) {
if(_from == _to) revert();
_;
}
function transferOwnership(address newOwner) public onlyOwner {
if (newOwner != address(0)) {
owner = newOwner;
}
}
function WeToken(address _owner, string _name, string _symbol, uint _totalSupply, uint _decimals) public UpgradeableToken(_owner) {
name = _name;
symbol = _symbol;
decimals = _decimals;
totalSupply = _totalSupply * 10 ** uint(decimals);
// Allocate initial balance to the owner
balances[_owner] = totalSupply;
// save the owner
owner = _owner;
}
function mintingFinish() public onlyOwner {
mintingFinished = true;
}
// privileged transfer
function transferPrivileged(address _to, uint _value) public onlyOwner returns (bool success) {
balances[msg.sender] = safeSub(balances[msg.sender], _value);
balances[_to] = safeAdd(balances[_to], _value);
previligedBalances[_to] = safeAdd(previligedBalances[_to], _value);
Transfer(msg.sender, _to, _value);
return true;
}
// get priveleged balance
function getPrivilegedBalance(address _owner) public constant returns (uint balance) {
return previligedBalances[_owner];
}
// admin only can transfer from the privileged accounts
function transferFromPrivileged(address _from, address _to, uint _value) public onlyOwner onlyNotSame(_from, _to) returns (bool success) {
uint availablePrevilegedBalance = previligedBalances[_from];
balances[_from] = safeSub(balances[_from], _value);
balances[_to] = safeAdd(balances[_to], _value);
previligedBalances[_from] = safeSub(availablePrevilegedBalance, _value);
Transfer(_from, _to, _value);
return true;
}
/**
* Create new tokens and allocate them to an address..
*
* Only callably by a crowdsale contract (mint agent).
*/
function mint(address receiver, uint amount) onlyMintAgent canMint public {
amount *= 10 ** uint(decimals);
totalSupply = safeAdd(totalSupply, amount);
balances[receiver] = safeAdd(balances[receiver], amount);
// This will make the mint transaction apper in EtherScan.io
// We can remove this after there is a standardized minting event
Transfer(0, receiver, amount);
}
/**
* Owner can allow a crowdsale contract to mint new tokens.
*/
function setMintAgent(address addr, bool state) onlyOwner canMint public {
mintAgents[addr] = state;
MintingAgentChanged(addr, state);
}
}