stETH

Lido协议是一个流动性质押协议，进行代币质押会得到对应的stToken, 比如质押ETH得到stETH，原生质押会把ETH锁到beacon chain上，而stToken具有流动性，可以参与交易，借贷等。

每天Lido的预言机都会报告beacon chain上的ETH数量以更新stETH的余额。stETH的更新会自动反馈到所有相关联的地址。

Lido还发行一种wstETH，都是ERC20，区别在于stETH会增发, wstETH不会。在任何时候，任何数量的 stETH 都可以通过trustless wrapper转换为wstETH，反之亦然，因此代币有效地共享流动性。例如，Maker 上抵押不足的 wstETH 头寸可以通过解包 wstETH 并将其换成 Curve 上的以太币来清算。

beacon chain oracle

当前有5个DAO选举的oracle每日监控beacon chain的变化，3/5的数目决定是否更新stETH，所有的余额增减都会反映到stETH, 所以通过stETH质押并不保证不会slash，只是不会将slash具体到个人而是平均到所有持有者，可以通过oracle dashboard查看Oracle状态。

Oracle operators: Stakefish, Certus One, Chorus One, Staking Facilities, P2P Validator.

shares计算公式：

1shares[account] = balanceOf(account) * totalShares / totalPooledEther

shares

建议集成dapp时存储和操作shares, 而不stETH余额，因为余额会变动，而shares不会。

shares通过 getSharesByPooledEth(uint256)获取. 逆操作getPooledEthByShares。 如果使用变化的stETH不合适，可以集成wstETH。

staking 集成

使用lido contract的submit(_referral)方法，传入奖励接收地址，同时包含以太币即可参与质押。

1import Web3 from "web3";
2
3// using partial ABI for simplicity
4const LIDO_ABI =  [
5    {
6        constant: false,
7        inputs: [{ name: "_referral", type: "address" }],
8        name: "submit",
9        outputs: [{ name: "", type: "uint256" }],
10        payable: true,
11        stateMutability: "payable",
12        type: "function"
13    }
14];
15
16const LIDO_ADDRESS = "0xae7ab96520DE3A18E5e111B5EaAb095312D7fE84"
17
18const MY_REWARDS_ADDRESS = "YOUR_REWARDS_ADDRESS"
19
20async function stakeWithLido() {
21    // enable provider
22    const [user] = await window.ethereum.request({
23        method: "eth_requestAccounts"
24    });
25
26    // init web3
27    const web3 = new Web3(window.ethereum);
28    web3.eth.Contract.setProvider(web3);
29
30    // init Lido
31    const lidoContract = new web3.eth.Contract(LIDO_ABI, LIDO_ADDRESS);
32
33    // stake
34    const tx = await lidoContract.methods
35        .submit(MY_REWARDS_ADDRESS)
36        .send({ from: user, value: web3.utils.toWei("0.1") });
37
38    console.log(tx);
39}

相关链上事件：

1Submitted (address sender, uint256 amount, address referral),
2Transfer (address from, address to, uint256 value),
3TransferShares (address from, address to, uint256 sharesValue).

合约里的 _submit function

1/**
2* @dev Process user deposit, mints liquid tokens and increase the pool buffer
3* @param _referral address of referral.
4* @return amount of StETH shares generated
5*/
6function _submit(address _referral) internal returns (uint256) {
7    require(msg.value != 0, "ZERO_DEPOSIT");
8
9    StakeLimitState.Data memory stakeLimitData = STAKING_STATE_POSITION.getStorageStakeLimitStruct();
10    require(!stakeLimitData.isStakingPaused(), "STAKING_PAUSED");
11
12    // 检查是否超过每日stake limit
13    if (stakeLimitData.isStakingLimitSet()) {
14        uint256 currentStakeLimit = stakeLimitData.calculateCurrentStakeLimit();
15
16        require(msg.value <= currentStakeLimit, "STAKE_LIMIT");
17
18        STAKING_STATE_POSITION.setStorageStakeLimitStruct(
19            stakeLimitData.updatePrevStakeLimit(currentStakeLimit - msg.value)
20        );
21    }
22
23    uint256 sharesAmount = getSharesByPooledEth(msg.value);
24    if (sharesAmount == 0) {
25        // 首次stake, shares : eth = 1 : 1
26        sharesAmount = msg.value;
27    }
28
29    _mintShares(msg.sender, sharesAmount);
30
31    BUFFERED_ETHER_POSITION.setStorageUint256(_getBufferedEther().add(msg.value));
32    emit Submitted(msg.sender, msg.value, _referral);
33
34    _emitTransferAfterMintingShares(msg.sender, sharesAmount);
35    return sharesAmount;
36}

reference

lido-contract lido-js-sdk