以太坊ERC20代币在线钱包对接-python版

前面实验了一下ETH对接的接口，今天打算试一下ERC20代币的对接，说白了就是将以太坊区块中的transtraction数据解析出来，单纯ETH的转账很简单，所有的信息都是明文（以太坊现在据称是支持了零知识证明，不知道那种记录长啥样，暂时无法分析）。

在私链中转移一个代币，根据返回的tx号，我们到console中得到完整信息如下

ERC20代币transaction

前面ETH转账时，from、to、value即为转账双方和金额，这里对了一下信息
form：事务发起者
to：合约地址
查询了一下资料，https://github.com/ethereum/wiki/wiki/Ethereum-Contract-ABI 这里有对合约数据的详细说明，也就是这里的input，大意是前10个字节是合约函数的hash，后面是输入参数经过编码后拼接起来的，wiki中讲述了每种格式的编码规则，按照这个规则即可实现编解码。

JS版本解码

js不愧是web3支持的最好的，可以参考如下资料
https://lab.miguelmota.com/ethereum-input-data-decoder/example/ -- 在线解析input数据
https://github.com/ConsenSys/abi-decoder -- 一个解析input数据的js库

python版本

由于平时是使用python居多，去看了web3.py，没有找到解析input的函数，倒是有个decode_abi，可以将参数解析出来，函数名无法得到，后面想了想还是根据js的版本改写一个python版本吧，如果有其他的朋友正好需要可以拿去使用，上代码

# -*- coding: utf-8 -*- 
from web3 import HTTPProvider  
from web3 import Web3
from eth_abi import decode_abi

ETH_HTTP_PROVIDER_DB="http://127.0.0.1:8200"
ETH_HTTP_PROVIDER_ACCOUNT="http://127.0.0.1:8200"

false=False
true=True
abi=[{"constant":false,"inputs":[{"name":"newSellPrice","type":"uint256"},{"name":"newBuyPrice","type":"uint256"}],"name":"setPrices","outputs":[],"payable":false,"stateMutability":"nonpayable","type":"function"},{"constant":true,"inputs":[],"name":"name","outputs":[{"name":"","type":"string"}],"payable":false,"stateMutability":"view","type":"function"},{"constant":false,"inputs":[{"name":"_spender","type":"address"},{"name":"_value","type":"uint256"}],"name":"approve","outputs":[{"name":"success","type":"bool"}],"payable":false,"stateMutability":"nonpayable","type":"function"},{"constant":true,"inputs":[],"name":"totalSupply","outputs":[{"name":"","type":"uint256"}],"payable":false,"stateMutability":"view","type":"function"},{"constant":false,"inputs":[{"name":"_from","type":"address"},{"name":"_to","type":"address"},{"name":"_value","type":"uint256"}],"name":"transferFrom","outputs":[{"name":"success","type":"bool"}],"payable":false,"stateMutability":"nonpayable","type":"function"},{"constant":true,"inputs":[],"name":"decimals","outputs":[{"name":"","type":"uint8"}],"payable":false,"stateMutability":"view","type":"function"},{"constant":false,"inputs":[{"name":"_value","type":"uint256"}],"name":"burn","outputs":[{"name":"success","type":"bool"}],"payable":false,"stateMutability":"nonpayable","type":"function"},{"constant":true,"inputs":[],"name":"sellPrice","outputs":[{"name":"","type":"uint256"}],"payable":false,"stateMutability":"view","type":"function"},{"constant":true,"inputs":[{"name":"","type":"address"}],"name":"balanceOf","outputs":[{"name":"","type":"uint256"}],"payable":false,"stateMutability":"view","type":"function"},{"constant":false,"inputs":[{"name":"target","type":"address"},{"name":"mintedAmount","type":"uint256"}],"name":"mintToken","outputs":[],"payable":false,"stateMutability":"nonpayable","type":"function"},{"constant":false,"inputs":[{"name":"_from","type":"address"},{"name":"_value","type":"uint256"}],"name":"burnFrom","outputs":[{"name":"success","type":"bool"}],"payable":false,"stateMutability":"nonpayable","type":"function"},{"constant":true,"inputs":[],"name":"buyPrice","outputs":[{"name":"","type":"uint256"}],"payable":false,"stateMutability":"view","type":"function"},{"constant":true,"inputs":[],"name":"owner","outputs":[{"name":"","type":"address"}],"payable":false,"stateMutability":"view","type":"function"},{"constant":true,"inputs":[],"name":"symbol","outputs":[{"name":"","type":"string"}],"payable":false,"stateMutability":"view","type":"function"},{"constant":false,"inputs":[],"name":"buy","outputs":[{"name":"amount","type":"uint256"}],"payable":true,"stateMutability":"payable","type":"function"},{"constant":false,"inputs":[{"name":"_to","type":"address"},{"name":"_value","type":"uint256"}],"name":"transfer","outputs":[],"payable":false,"stateMutability":"nonpayable","type":"function"},{"constant":true,"inputs":[{"name":"","type":"address"}],"name":"frozenAccount","outputs":[{"name":"","type":"bool"}],"payable":false,"stateMutability":"view","type":"function"},{"constant":false,"inputs":[{"name":"_spender","type":"address"},{"name":"_value","type":"uint256"},{"name":"_extraData","type":"bytes"}],"name":"approveAndCall","outputs":[{"name":"success","type":"bool"}],"payable":false,"stateMutability":"nonpayable","type":"function"},{"constant":false,"inputs":[{"name":"_from","type":"address"},{"name":"_to","type":"address"},{"name":"_value","type":"uint256"}],"name":"ptransfer","outputs":[],"payable":false,"stateMutability":"nonpayable","type":"function"},{"constant":true,"inputs":[{"name":"","type":"address"},{"name":"","type":"address"}],"name":"allowance","outputs":[{"name":"","type":"uint256"}],"payable":false,"stateMutability":"view","type":"function"},{"constant":false,"inputs":[{"name":"amount","type":"uint256"}],"name":"sell","outputs":[],"payable":false,"stateMutability":"nonpayable","type":"function"},{"constant":false,"inputs":[{"name":"target","type":"address"},{"name":"freeze","type":"bool"}],"name":"freezeAccount","outputs":[],"payable":false,"stateMutability":"nonpayable","type":"function"},{"constant":false,"inputs":[{"name":"newOwner","type":"address"}],"name":"transferOwnership","outputs":[],"payable":false,"stateMutability":"nonpayable","type":"function"},{"inputs":[{"name":"initialSupply","type":"uint256"},{"name":"tokenName","type":"string"},{"name":"decimalUnits","type":"uint8"},{"name":"tokenSymbol","type":"string"}],"payable":false,"stateMutability":"nonpayable","type":"constructor"},{"payable":true,"stateMutability":"payable","type":"fallback"},{"anonymous":false,"inputs":[{"indexed":false,"name":"target","type":"address"},{"indexed":false,"name":"frozen","type":"bool"}],"name":"FrozenFunds","type":"event"},{"anonymous":false,"inputs":[{"indexed":false,"name":"target","type":"address"},{"indexed":false,"name":"val","type":"uint256"},{"indexed":false,"name":"from","type":"address"},{"indexed":false,"name":"balance","type":"uint256"}],"name":"PayETHEvent","type":"event"},{"anonymous":false,"inputs":[{"indexed":false,"name":"target","type":"address"},{"indexed":false,"name":"val","type":"uint256"},{"indexed":false,"name":"from","type":"address"},{"indexed":false,"name":"balance","type":"uint256"}],"name":"BuyEvent","type":"event"},{"anonymous":false,"inputs":[{"indexed":false,"name":"target","type":"address"},{"indexed":false,"name":"val","type":"uint256"},{"indexed":false,"name":"amount","type":"uint256"}],"name":"BuyEventCalc","type":"event"},{"anonymous":false,"inputs":[{"indexed":false,"name":"target","type":"address"},{"indexed":false,"name":"amount","type":"uint256"},{"indexed":false,"name":"balance","type":"uint256"},{"indexed":false,"name":"calc","type":"uint256"}],"name":"SellEvent","type":"event"},{"anonymous":false,"inputs":[{"indexed":true,"name":"from","type":"address"},{"indexed":true,"name":"to","type":"address"},{"indexed":false,"name":"value","type":"uint256"}],"name":"Transfer","type":"event"},{"anonymous":false,"inputs":[{"indexed":true,"name":"from","type":"address"},{"indexed":false,"name":"value","type":"uint256"}],"name":"Burn","type":"event"}]
input="0xa9059cbb000000000000000000000000855ecc6b1c1cd332ea87e0f77189e8318deadc9d000000000000000000000000000000000000000000000000000000000000c350"
contract_address="0x9650bd781FbbE71bC65583B5205E2Fe69B1611c2"

web3=Web3(HTTPProvider(ETH_HTTP_PROVIDER_ACCOUNT))
contract=web3.eth.contract(abi,contract_address)

def getFunctionHashes(web3,abi):
    hashes = [];
    for i in range(0,len(abi)):
        item = abi[i]
        if (item['type'] != "function"):
            continue
        signature = item['name'] + "(" + ",".join(map(lambda input:input['type'],item['inputs'])) + ")"
        hash = web3.sha3(signature.encode("hex"))
        hashes.append({'name': item['name'], 'hash': hash, 'inputs':[(x['name'],x['type']) for x in item['inputs']]})
  
    return hashes

def findFunctionByHash(hashes, functionHash):
    for i in range(0,len(hashes)):
        if hashes[i]['hash'][:10] == functionHash[:10]:
            return hashes[i]['name'],hashes[i]['inputs']
    return None,None

if __name__=="__main__":
    hashes=getFunctionHashes(web3,abi)
    func,name_and_type=findFunctionByHash(hashes,input)
    print func,decode_abi([x[1] for x in name_and_type], input[10:].decode('hex'))
    print func,zip([x[0] for x in name_and_type],decode_abi([x[1] for x in name_and_type], input[10:].decode('hex')))

运行结果如下

图片.png

可以看到，这个transaction对应的函数以及参数，后面要做的就是自己的入账处理了，这里不再啰嗦了