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LinkToken
pragma solidity ^0.4.16;
/**
* @title SafeMath
* @dev Math operations with safety checks that throw on error
*/
library SafeMath {
function mul(uint256 a, uint256 b) internal constant returns (uint256) {
uint256 c = a * b;
assert(a == 0 || c / a == b);
return c;
}
function div(uint256 a, uint256 b) internal constant returns (uint256) {
// assert(b > 0); // Solidity automatically throws when dividing by 0
uint256 c = a / b;
// assert(a == b * c + a % b); // There is no case in which this doesn't hold
return c;
}
function sub(uint256 a, uint256 b) internal constant returns (uint256) {
assert(b <= a);
return a - b;
}
function add(uint256 a, uint256 b) internal constant returns (uint256) {
uint256 c = a + b;
assert(c >= a);
return c;
}
}
/**
* @title ERC20Basic
* @dev Simpler version of ERC20 interface
* @dev see https://github.com/ethereum/EIPs/issues/179
*/
contract ERC20Basic {
uint256 public totalSupply;
function balanceOf(address who) constant returns (uint256);
function transfer(address to, uint256 value) returns (bool);
event Transfer(address indexed from, address indexed to, uint256 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 (uint256);
function transferFrom(address from, address to, uint256 value) returns (bool);
function approve(address spender, uint256 value) returns (bool);
event Approval(address indexed owner, address indexed spender, uint256 value);
}
contract ERC677 is ERC20 {
function transferAndCall(address to, uint value, bytes data) returns (bool success);
event Transfer(address indexed from, address indexed to, uint value, bytes data);
}
contract ERC677Receiver {
function onTokenTransfer(address _sender, uint _value, bytes _data);
}
/**
* @title Basic token
* @dev Basic version of StandardToken, with no allowances.
*/
contract BasicToken is ERC20Basic {
using SafeMath for uint256;
mapping(address => uint256) balances;
/**
* @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, uint256 _value) returns (bool) {
balances[msg.sender] = balances[msg.sender].sub(_value);
balances[_to] = balances[_to].add(_value);
Transfer(msg.sender, _to, _value);
return true;
}
/**
* @dev Gets the balance of the specified address.
* @param _owner The address to query the the balance of.
* @return An uint256 representing the amount owned by the passed address.
*/
function balanceOf(address _owner) constant returns (uint256 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 ERC20, BasicToken {
mapping (address => mapping (address => uint256)) allowed;
/**
* @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 uint256 the amount of tokens to be transferred
*/
function transferFrom(address _from, address _to, uint256 _value) returns (bool) {
var _allowance = allowed[_from][msg.sender];
// Check is not needed because sub(_allowance, _value) will already throw if this condition is not met
// require (_value <= _allowance);
balances[_from] = balances[_from].sub(_value);
balances[_to] = balances[_to].add(_value);
allowed[_from][msg.sender] = _allowance.sub(_value);
Transfer(_from, _to, _value);
return true;
}
/**
* @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, uint256 _value) returns (bool) {
allowed[msg.sender][_spender] = _value;
Approval(msg.sender, _spender, _value);
return true;
}
/**
* @dev Function to check the amount of tokens that 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 uint256 specifying the amount of tokens still available for the spender.
*/
function allowance(address _owner, address _spender) constant returns (uint256 remaining) {
return allowed[_owner][_spender];
}
/*
* approve should be called when allowed[_spender] == 0. To increment
* allowed value is better to use this function to avoid 2 calls (and wait until
* the first transaction is mined)
* From MonolithDAO Token.sol
*/
function increaseApproval (address _spender, uint _addedValue)
returns (bool success) {
allowed[msg.sender][_spender] = allowed[msg.sender][_spender].add(_addedValue);
Approval(msg.sender, _spender, allowed[msg.sender][_spender]);
return true;
}
function decreaseApproval (address _spender, uint _subtractedValue)
returns (bool success) {
uint oldValue = allowed[msg.sender][_spender];
if (_subtractedValue > oldValue) {
allowed[msg.sender][_spender] = 0;
} else {
allowed[msg.sender][_spender] = oldValue.sub(_subtractedValue);
}
Approval(msg.sender, _spender, allowed[msg.sender][_spender]);
return true;
}
}
contract ERC677Token is ERC677 {
/**
* @dev transfer token to a contract address with additional data if the recipient is a contact.
* @param _to The address to transfer to.
* @param _value The amount to be transferred.
* @param _data The extra data to be passed to the receiving contract.
*/
function transferAndCall(address _to, uint _value, bytes _data)
public
returns (bool success)
{
super.transfer(_to, _value);
Transfer(msg.sender, _to, _value, _data);
if (isContract(_to)) {
contractFallback(_to, _value, _data);
}
return true;
}
// PRIVATE
function contractFallback(address _to, uint _value, bytes _data)
private
{
ERC677Receiver receiver = ERC677Receiver(_to);
receiver.onTokenTransfer(msg.sender, _value, _data);
}
function isContract(address _addr)
private
returns (bool hasCode)
{
uint length;
assembly { length := extcodesize(_addr) }
return length > 0;
}
}
contract LinkToken is StandardToken, ERC677Token {
uint public constant totalSupply = 10**27;
string public constant name = 'ChainLink Token';
uint8 public constant decimals = 18;
string public constant symbol = 'LINK';
function LinkToken()
public
{
balances[msg.sender] = totalSupply;
}
/**
* @dev transfer token to a specified address with additional data if the recipient is a contract.
* @param _to The address to transfer to.
* @param _value The amount to be transferred.
* @param _data The extra data to be passed to the receiving contract.
*/
function transferAndCall(address _to, uint _value, bytes _data)
public
validRecipient(_to)
returns (bool success)
{
return super.transferAndCall(_to, _value, _data);
}
/**
* @dev transfer token to a specified address.
* @param _to The address to transfer to.
* @param _value The amount to be transferred.
*/
function transfer(address _to, uint _value)
public
validRecipient(_to)
returns (bool success)
{
return super.transfer(_to, _value);
}
/**
* @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, uint256 _value)
public
validRecipient(_spender)
returns (bool)
{
return super.approve(_spender, _value);
}
/**
* @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 uint256 the amount of tokens to be transferred
*/
function transferFrom(address _from, address _to, uint256 _value)
public
validRecipient(_to)
returns (bool)
{
return super.transferFrom(_from, _to, _value);
}
// MODIFIERS
modifier validRecipient(address _recipient) {
require(_recipient != address(0) && _recipient != address(this));
_;
}
}
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