使用web3.py实现ERC20 Token空投

前言

随着一些交易所搞的上币排名的活动开展,也带来了空投的火爆,当然也给以太坊整个网络带来了很大的考验(极其拥堵、交易费水涨船高),本篇文章还是从技术上来看看实现空投的一种通用方案。

关于空投的实现需要提前了解一下 ERC20 标准中的下面几个函数:

  • approve(_spender, value):该函数表示允许 _spender 多次取回调用此函数的的账户中的 token,最高为 value 个 token,后面再次调用此函数会覆盖之前设置的余额;
  • allowance(_owner, _spender):返回 _spender 仍然可以从 _owner 中提取的 token 余额;
  • transferFrom(_from, _to, _value): 该方法主要用于允许 contract 来自动执行转账流程,并代表所有者发送 _value 个 token;

实现流程

流程说明:

  • 1.账户 A 创建和部署 ERC20 Token SOT
  • 2.账户 B 创建和部署空投合约 Airdrop
  • 3.需要空投的账户 C(如运营人员账户)授信合约账户 Airdrop 使用其账户上拥有的一定数额的 SOT token;
  • 4.授信成功后,通过调用 Airdrop 的空投方法 drop 实现给账户 a,b,c 发送 SOT token;
  • 5.在 Airdrop 的方法 drop 内部通过调用 SOTtransferFrom 方法实现转账;

环境准备

  • python3
  • web3.py
  • solc
  • 测试网络 Ropsten(Rinkeby 也可以)已同步

用于部署合约的程序

如下为使用 web3.py 部署合约(deploy_contract.py)的代码:

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#!/usr/bin/python3
# -*- coding:utf-8 -*-

import sys
import json

from web3 import Web3
from web3 import HTTPProvider
from solc import compile_source


def load_contract_source_code(source_code_file):
contract_source_code = ''
with open(source_code_file) as f:
for line in f:
contract_source_code += line + '\n'
return contract_source_code


def main(argv):
"""deploy_contract <contract name> <contract code path> <account address> <gas price, unit: Gwei>
"""
code = load_contract_source_code(argv[2])
compiled_sol = compile_source(code)
contract_interface = compiled_sol['<stdin>:' + argv[1]]
account_address = argv[3]
gas_price = int(argv[4]) * 10 ** 9

w3 = Web3(HTTPProvider("http://127.0.0.1:8545"))
contract = w3.eth.contract(abi=contract_interface['abi'], bytecode=contract_interface['bin'])
tx_param = {
'from': account_address,
'gasPrice': gas_price,
}
tx_hash = contract.deploy(transaction=tx_param)
print("deploying, tx_hash {}".format(Web3.toHex(tx_hash)))

tx_receipt = w3.eth.waitForTransactionReceipt(tx_hash)
print("receipt: ", tx_receipt)

编写合约 Airdrop

这里的合约代码实现逻辑是先将:

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pragma solidity ^0.4.22;

contract ERC20Token {
uint256 public totalSupply;
function balanceOf(address _owner) public constant returns (uint256 balance);
function transfer(address _to, uint256 _value) public returns (bool success);
function transferFrom(address _from, address _to, uint256 _value) public returns (bool success);
function approve(address _spender, uint256 _value) public returns (bool success);
function allowance(address _owner, address _spender) public constant returns (uint256 remaining);
event Transfer(address indexed _from, address indexed _to, uint256 _value);
event Approval(address indexed _owner, address indexed _spender, uint256 _value);
}

contract FutureEdgeAirdrop {
function drop(address tokenAddr, address[] dests, uint256 value) public payable {
uint256 valuePerCount = value / dests.length;
for (uint i = 0; i < dests.length; i++) {
ERC20Token(tokenAddr).transferFrom(msg.sender, dests[i], valuePerCount);
}
}
}

部署合约 Airdrop

使用之前的 deploy_contract 来部署合约,提供合约名称、合约代码文件、以及部署合约的账号名和 GasPrice,如下:

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$ deploy FutureEdgeAirdrop FutureEdgeAirdrop.sol 0xEcD3E082Df97E509D83c71e660b9Fd5EfCB92345 120
account: 0xEcD3E082Df97E509D83c71e660b9Fd5EfCB92345
deploying, tx_hash is 0x3852944e009b1acbe556b78516dbfdadd1080429cf723f6f71c78e669b299d42
tx_receipt: {"blockHash": "0x9e2c321dbfaa1236adbd0b5eef2ee14577c951573c6ca665758ab7f1dabe7ea7", "contractAddress": "0xd3D476033145a976fF0304de7CAD767Ba2DBa1F4", "cumulativeGasUsed": 209681, "from": "0xecd3e082df97e509d83c71e660b9fd5efcb92345", "status": 1, "transactionHash": "0x5387e031881b2f3a49b917ed3bdeb76691c9d845d9f3f72ad00a1530b3a4347e", "to": null}

按照其中的 transaction hash 查询 etherscan 如下:

新创建的 Airdrop 合约地址为: 0xd3D476033145a976fF0304de7CAD767Ba2DBa1F4

授信合约账号

账号 C(我们测试环境使用的账号是 0xEfd0367D44bf23159599Fc525e797c9b79B6dEEC)授权给 Airdrop 合约账号可以提取其中的 6666 个 SOT token(地址为: 0x814f06FFaD575cb9F13A62C835bc505394CB4678),代码实现如下:

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def approve(account_addr, token_addr, spender, token_count, gas_price):
w3 = Web3(HTTPProvider("http://127.0.0.1:8545"))
w3.defaultAccount = account_addr
token = w3.eth.contract(address=token_addr, abi=erc20_abi)
tx_hash = token.functions.approve(spender, token_count).transact({
"from": account_addr,
"gasPrice": gas_price * 10 ** 9
})
tx_receipt = w3.eth.waitForTransactionReceipt(tx_hash)
print("receipt: ", tx_receipt)

针对上面的需求,相应的参数分别为: - account_addr: 这里为 C; - token_addrSOT 的合约地址,其中用于生成相应的 contract 类实例; - spender:这里被授权的是 Airdrop 合约地址; - token_count:被授权使用的 token 数;

调用执行后如下:

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$ acctexplorer approve 0xEfd0367D44bf23159599Fc525e797c9b79B6dEEC 0x814f06FFaD575cb9F13A62C835bc505394CB4678 0xd3D476033145a976fF0304de7CAD767Ba2DBa1F4 6666000000000000000000 30
Commit approve, txhash 0x5800e276f887c7a0f5d73fb9db31f95be7bb609270ba49c29eb5473a51fe61ce, waiting receipt ...
------ approve ------
account: 0xEfd0367D44bf23159599Fc525e797c9b79B6dEEC
token: 0x814f06FFaD575cb9F13A62C835bc505394CB4678(StevenOceanToken) SOT
spender: 0xd3D476033145a976fF0304de7CAD767Ba2DBa1F4
count: 6666000000000000000000
----- receipt -----
{
"blockHash": "0xe9f6f93965cc7640e92e9fc83a81e446e53ba89219f2b4bdf6c749a212179e8e",
"contractAddress": null,
"cumulativeGasUsed": 120369,
"from": "0xefd0367d44bf23159599fc525e797c9b79b6deec",
"status": 1,
"transactionHash": "0xccdc1f637e92d34e39282a0358cdea4810c15f5036ea2cd72f749a3279c6cfc3",
"to": "0x814f06ffad575cb9f13a62c835bc505394cb4678"
}
--------------------

通过 allowance 来查看被授权的信息,代码实现如下:

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def allowance(account_addr, token_addr, spender):
w3 = Web3(HTTPProvider("http://127.0.0.1:8545"))
token_instance = w3.eth.contract(address=token_addr, abi=erc20_abi, ContractFactoryClass=ConciseContract)
allow_token_count = token_instance.allowance(account_addr, spender)
print("------ allowance ------")
print("token: {}({}) {}".format(token_addr, token_instance.name(), token_instance.symbol()))
print("owner: {}".format(account_addr))
print("spender: {}".format(spender))
print("allowence count: {}".format(allow_token_count))
print("--------------------")

这里传入 C 的账户地址(account_addr),SOT 的合约地址(token_addr),以及被授信的 Airdrop 合约地址(spender) 之后,结果如下:

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$ acctexplorer allowance 0xEfd0367D44bf23159599Fc525e797c9b79B6dEEC 0x814f06FFaD575cb9F13A62C835bc505394CB4678 0xd3D476033145a976fF0304de7CAD767Ba2DBa1F4
------ allowance ------
token: 0x814f06FFaD575cb9F13A62C835bc505394CB4678(StevenOceanToken) SOT
owner: 0xEfd0367D44bf23159599Fc525e797c9b79B6dEEC
spender: 0xd3D476033145a976fF0304de7CAD767Ba2DBa1F4
allowence count: 6666000000000000000000
--------------------

执行空投

上面账号 C 授信成功之后,可以通过 C 来执行 Airdrop 合约的 drop 方法来实现给账号 a, b, c 发送 SOT token,如下代码:

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def airdrop(account_addr, token_addr, token_count, gas_price, dest_account_addrs):
w3 = Web3(HTTPProvider("http://127.0.0.1:8545"))
contract_instance = w3.eth.contract(address=AIRDROP_ADDR, abi=AIRDROP_ABI)
tx_hash = contract_instance.functions.drop(token_addr, dest_account_addrs, token_count).transact({
"from": account_addr,
"gasPrice": gas_price * 10 ** 9
})
print("Commit airdrop, txhash {}, waiting receipt ...".format(Web3.toHex(tx_hash)))
tx_receipt = w3.eth.waitForTransactionReceipt(tx_hash)
print("receipt: ", tx_receipt)
  • 代码中的 AIRDROP_ADDR 为 Airdrop 的合约地址,AIRDROP_ABI 为 Airdrop 合约的 ABI(具体生成方法可以参考之前的文章);

这里通过 contract_instance 中的 functions.drop 来访问相应合约中的 drop 方法,这里演示了同时给两个账号各空投 256 个 SOT token(0x19f87671E1BFd859B203816e54fA19F464c9A155, 0x37a6e30c37fbe6af220a99a029a60e5848745AE9)。

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$ acctexplorer airdrop 0xEfd0367D44bf23159599Fc525e797c9b79B6dEEC 0x814f06FFaD575cb9F13A62C835bc505394CB4678 789000000000000000000 30 0x19f87671E1BFd859B203816e54fA19F464c9A155 0x37a6e30c37fbe6af220a99a029a60e5848745AE9
Commit airdrop, txhash 0x178eb4ad81d3160433b36cfc1357d50f2ef0ce758b4a7026d3cc72f42dd60dee, waiting receipt ...
------ airdrop ------
account: 0xEfd0367D44bf23159599Fc525e797c9b79B6dEEC
token: 0x814f06FFaD575cb9F13A62C835bc505394CB4678(StevenOceanToken) SOT
dest account: 0x37a6e30c37fbe6af220a99a029a60e5848745AE9
count: 512000000000000000000
----- receipt -----
{
"blockHash": "0x6e452edabcaf7e2e33433e4e243922fcb59dda5e6caa2852de0a2f3547ce4981",
"contractAddress": null,
"cumulativeGasUsed": 200618,
"from": "0xefd0367d44bf23159599fc525e797c9b79b6deec",
"status": 1,
"transactionHash": "0x3f371728058e3a1ca32408c6c9613801ba0559ade91b6b63a3a389f985b5b658",
"to": "0xd3d476033145a976ff0304de7cad767ba2dba1f4"
}
--------------------

我们可以查一下对应的 transaction 记录,如下:

转自: Steven Hu《使用web3.py实现ERC20 Token空投》

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