Wormhole资产跨链项目代码解析

Posted 2021-10-02 mutourend

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1. 引言

Wormhole支持基于Solana与多个链进行资产转移，开源代码为：

https://github.com/certusone/wormhole/tree/main

当前已上线V1，已支持：

未来V2将支持：

2. 关键代码解析

支持的chain_id命名及支持的action类型有：

	ActionGuardianSetUpdate Action = 0x01
	ActionContractUpgrade   Action = 0x02
	ActionTransfer          Action = 0x10

	// ChainIDSolana is the ChainID of Solana
	ChainIDSolana = 1
	// ChainIDEthereum is the ChainID of Ethereum
	ChainIDEthereum = 2
	// ChainIDTerra is the ChainID of Terra
	ChainIDTerra = 3

以 0x22557d54dfc8adb1a888478258f89abb4a11a7069c983e6db1bc14de6d6e7946 lockAssets交易为例：
会将相应的token发送到black hole: 0x0000000000000000000000000000000000000000 中 burn掉：

		if (isWrappedAsset[asset]) {
            WrappedAsset(asset).burn(msg.sender, amount);
            asset_chain = WrappedAsset(asset).assetChain();
            asset_address = WrappedAsset(asset).assetAddress();
        }

Solana端Wrapped Ether (Wormhole) token地址为：FeGn77dhg1KXRRFeSwwMiykZnZPw5JXW6naf2aQgZDQf

Solana端Wormhole合约中的mint交易为：https://solscan.io/tx/wwwFsn2cx69HPEg64iRErNHaUx4GbLt48vGSgFguAfgDBZtiYjFsXc6eH7CzEJuMv8RQ1UD41JZ1iMy5CYW5Hvr

以太坊端Wormhole:Solana Bridge合约地址为：

https://etherscan.io/address/0xf92cd566ea4864356c5491c177a430c222d7e678

Solana端Wormhole合约地址为：

WormT3McKhFJ2RkiGpdw9GKvNCrB2aB54gb2uV9MfQC

以太坊端Wormhole:Solana Bridge合约关键函数有：

（1）submitVAA()，若action为0x10，即ActionTransfer，则将Solana中的资产通过Wormhole:Solana Bridge合约转移出来，对应的target_chain应设置为以太坊，若资产为以太坊ERC20 token（即token_chain=2），则直接将Solana Bridge合约中的ERC20 token转移到指定账号即可；若资产为其他链上的值，则在以太坊上根据token_chain和token_address在以太坊上创建相应的wrapped合约，往该合约mint或burn。

	if (token_chain != CHAIN_ID) {
            bytes32 token_address = data.toBytes32(71);
            bytes32 asset_id = keccak256(abi.encodePacked(token_chain, token_address));

            // if yes: mint to address
            // if no: create and mint
            address wrapped_asset = wrappedAssets[asset_id];
            if (wrapped_asset == address(0)) {
                uint8 asset_decimals = data.toUint8(103);
                wrapped_asset = deployWrappedAsset(asset_id, token_chain, token_address, asset_decimals);
            }

            WrappedAsset(wrapped_asset).mint(target_address, amount);
        } else {
            address token_address = data.toAddress(71 + 12);

            uint8 decimals = ERC20(token_address).decimals();

            // Readjust decimals if they've previously been truncated
            if (decimals > 9) {
                amount = amount.mul(10 ** uint256(decimals - 9));
            }
            IERC20(token_address).safeTransfer(target_address, amount);
        }

（2）LockAssets()，用于将以太坊上的资产转移至Solana。

		if (isWrappedAsset[asset]) { //非以太坊上发行的token，通过wrapped合约销毁
            WrappedAsset(asset).burn(msg.sender, amount);
            asset_chain = WrappedAsset(asset).assetChain();
            asset_address = WrappedAsset(asset).assetAddress();
        } else { //以太坊上的ERC20 token，直接将相应金额转入本Solana Bridge合约。
            uint256 balanceBefore = IERC20(asset).balanceOf(address(this));
            IERC20(asset).safeTransferFrom(msg.sender, address(this), amount);
            uint256 balanceAfter = IERC20(asset).balanceOf(address(this));

            // The amount that was transferred in is the delta between balance before and after the transfer.
            // This is to properly handle tokens that charge a fee on transfer.
            amount = balanceAfter.sub(balanceBefore);

            // Decimal adjust amount - we keep the dust
            if (decimals > 9) {
                uint256 original_amount = amount;
                amount = amount.div(10 ** uint256(decimals - 9));

                if (refund_dust) {
                    IERC20(asset).safeTransfer(msg.sender, original_amount.mod(10 ** uint256(decimals - 9)));
                }

                decimals = 9;
            }

            require(balanceAfter.div(10 ** uint256(ERC20(asset).decimals() - 9)) <= MAX_UINT64, "bridge balance would exceed maximum");

            asset_address = bytes32(uint256(asset));
        }

以太坊Wormhole:Solana Bridge合约guardian set更新交易为：
0x833e7bec034d9904713d6a7dc13d197ec41af2d0611122603289a1e69ae72c43
更新Guardianset的submitVAA(bytes calldata vaa)调用数据为：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

3. Solana中HUSD转移至以太坊HUSD ERC20 token示例

	{
      "chainId": 101,
      "address": "BybpSTBoZHsmKnfxYG47GDhVPKrnEKX31CScShbrzUhX",
      "symbol": "wHUSD",
      "name": "HUSD Stablecoin (Wormhole)",
      "decimals": 8,
      "logoURI": "https://raw.githubusercontent.com/solana-labs/token-list/main/assets/mainnet/BybpSTBoZHsmKnfxYG47GDhVPKrnEKX31CScShbrzUhX/logo.png",
      "tags": [
        "wrapped",
        "wormhole"
      ],
      "extensions": {
        "website": "https://www.stcoins.com/",
        "address": "0xdf574c24545e5ffecb9a659c229253d4111d87e1",
        "bridgeContract": "https://etherscan.io/address/0xf92cD566Ea4864356C5491c177A430C222d7e678",
        "assetContract": "https://etherscan.io/address/0xdf574c24545e5ffecb9a659c229253d4111d87e1",
        "coingeckoId": "husd"
      }
    }

将Solana中的HUSD转移至以太坊中的HUSD ERC20 token示例为：

以太坊端的交易为：https://etherscan.io/tx/0x4e3a1f0ab7f6551ae6e50598ff3c89c8933d7fa6a233d9f509d7b93379b0c96b
Solana端的交易为：https://explorer.solana.com/tx/5UapTG2W81XBUMTLEEcwKmqmwEoyww5ZvF4F3S2aLnkNyXRWvVF637rAEjyPVsEjXiPVNmHT7KPrExd2HXq2MBDt

以太坊接收地址为：0xe0b2026e3db1606ef0beb764ccdf7b3cee30db4a
Solana端发送地址为：EH4Ee8SikRZzWWujY88wwXSaAv2AosgdurgjEvS32P4K（Owner为：CaBptTpgdBjhiLfdPjJzz7rRWuwNhaZXhvygM8zxuuyk）

HUSD资产由Solana端转移出时，详细的流程为：

1）将相应的转出金额授权给Wormhole合约的账号：9zyPU1mjgzaVyQsYwKJJ7AhVz5bgx5uc1NPABvAcUXsT
2）由发起转出账号将手续费（0.02046048 SOL）发给Wormhole合约的账号
3）调用Wormhole合约的Transfer Assets Out函数，其中在Instruction Data中包含了接收资产的以太坊地址：

– 3.1）由转出账号创建相应的Wormhole合约账号：

– 3.2）将转出账号的相应资产由 1）中授权的账号进行Burn销毁：

完整的log为：

Program TokenkegQfeZyiNwAJbNbGKPFXCWuBvf9Ss623VQ5DA invoke [1]
Instruction: Approve
Program TokenkegQfeZyiNwAJbNbGKPFXCWuBvf9Ss623VQ5DA consumed 2297 of 200000 compute units
Program TokenkegQfeZyiNwAJbNbGKPFXCWuBvf9Ss623VQ5DA success
Program 11111111111111111111111111111111 invoke [1]
Program 11111111111111111111111111111111 success
Program WormT3McKhFJ2RkiGpdw9GKvNCrB2aB54gb2uV9MfQC invoke [1]
Instruction: TransferOut
wrapped transfer out
deriving key
deploying contract
Program 11111111111111111111111111111111 invoke [2]
Program 11111111111111111111111111111111 success
Program TokenkegQfeZyiNwAJbNbGKPFXCWuBvf9Ss623VQ5DA invoke [2]
Instruction: Burn
Program TokenkegQfeZyiNwAJbNbGKPFXCWuBvf9Ss623VQ5DA consumed 2886 of 136268 compute units
Program TokenkegQfeZyiNwAJbNbGKPFXCWuBvf9Ss623VQ5DA success
Program WormT3McKhFJ2RkiGpdw9GKvNCrB2aB54gb2uV9MfQC consumed 67592 of 200000 compute units
Program WormT3McKhFJ2RkiGpdw9GKvNCrB2aB54gb2uV9MfQC success

4）Validator会监听3）中的Burn操作，详细代码见：wormhole/bridge/pkg/solana/client.go：

					accounts, err := rpcClient.GetProgramAccounts(rCtx, s.bridge, &rpc.GetProgramAccountsOpts{
						Commitment: rpc.CommitmentMax, // TODO: deprecated, use Finalized
						Filters: []rpc.RPCFilter{
							{
								DataSize: 1184, // Search for TransferOutProposal accounts
							},
							{
								Memcmp: &rpc.RPCFilterMemcmp{
									Offset: 1140,                      // Offset of VaaTime
									Bytes:  solana.Base58{0, 0, 0, 0}, // VAA time is 0 when no VAA is present
								},
							},
						},
					})
 					// 相应结果的proposal解析结果为：
 					lock := &common.ChainLock{
							TxHash:        txHash,
							Timestamp:     proposal.LockupTime,
							Nonce:         proposal.Nonce,
							SourceAddress: proposal.SourceAddress,
							TargetAddress: proposal.ForeignAddress,
							SourceChain:   vaa.ChainIDSolana,
							TargetChain:   proposal.ToChainID,
							TokenChain:    proposal.Asset.Chain,
							TokenAddress:  proposal.Asset.Address,
							TokenDecimals: proposal.Asset.Decimals,
							Amount:        proposal.Amount,
						}

Validator提交通过SubmitVAA提交Unlock Sig，详细交易见：https://explorer.solana.com/tx/5SKH9ppMdPQJn5EtvNdW9jztmzf5y3YZdxX25UXPaFU1yFcYCmUkmGuz4D32iaWBMMpSivg4zjzh3qkzHsUqXBjF，详细代码见：wormhole/solana/agent/src/main.rs中的post_vaa() 函数：

		VAABody::Transfer(t) => {
            if t.source_chain == CHAIN_ID_SOLANA {
                // Solana (any) -> Ethereum (any)
                let transfer_key = Bridge::derive_transfer_id(
                    program_id,
                    &bridge_key,
                    t.asset.chain,
                    t.asset.address,
                    t.target_chain,
                    t.target_address,
                    t.source_address,
                    t.nonce,
                )?;
                accounts.push(AccountMeta::new(transfer_key, false))
            } 
            ......
        }

5）用户Agent监听4）中的Unlock签名，然后Aggregates & Publish Signatures 向以太坊发起SubmitVAA()交易。详细代码见：wormhole/bridge/pkg/solana/submitter.go。

// handleObservation processes a remote VAA observation, verifies it, checks whether the VAA has met quorum,
// and assembles and submits a valid VAA if possible.
func (p *Processor) handleObservation(ctx context.Context, m *gossipv1.SignedObservation) {
	// SECURITY: at this point, observations received from the p2p network are fully untrusted (all fields!)
	//
	// Note that observations are never tied to the (verified) p2p identity key - the p2p network
	// identity is completely decoupled from the guardian identity, p2p is just transport.
.......
}

				timeout, cancel := context.WithTimeout(ctx, 120*time.Second)
				res, err := c.SubmitVAA(timeout, &agentv1.SubmitVAARequest{Vaa: vaaBytes, SkipPreflight: e.skipPreflight})

具体交易见：
https://etherscan.io/tx/0x4e3a1f0ab7f6551ae6e50598ff3c89c8933d7fa6a233d9f509d7b93379b0c96b

4. 以太坊HUSD ERC20 token转移至Solana中HUSD示例

以太坊端交易为：https://etherscan.io/tx/0xffb94e1578a44730baac95782bf8f436ca7bdc5d6ca28c7b0811eb139a45fd83，转出账号为：0x47ed57f375d3dddae2ded7a6de522c35bc9419af。
Solana端交易为：https://explorer.solana.com/tx/4pn6CxjXYuA4nRUdUjXTK5yivwxSRSgDJJ9Rg37KNo5tQnKq61RWfxVmsmsqroUdS18NnQ7R1mz3yZbNajamS8SZ，转入账号为：CUAqsZjcsoaHJPfQTPLLvJRHpQuegguBwEzKehdztovT。

详细流程为：
1）用户调用LockAssets()将以太坊ERC20 token转移至Wormhole: Solana Bridge合约。
2）Validator监听LogTokensLocked event，并对其进行签名。

LogTokensLocked (uint8 target_chain, uint8 token_chain, uint8 token_decimals, index_topic_1 bytes32 token, index_topic_2 bytes32 sender, bytes32 recipient, uint256 amount, uint32 nonce)View Source
具体值为：
target_chain :
1
token_chain :
2
token_decimals :
8
recipient :
AA665DFB6CDD379DACB27DCCABDB9888128F6B47709FDA8809E72F1CA300901C
amount :
1709034375
nonce :
1409

// handleLockup processes a lockup received from a chain and instantiates our deterministic copy of the VAA. A lockup
// event may be received multiple times until it has been successfully completed.
func (p *Processor) handleLockup(ctx context.Context, k *common.ChainLock) {
	......
	// All nodes will create the exact same VAA and sign its digest.
	// Consensus is established on this digest.

	v := &vaa.VAA{
		Version:          vaa.SupportedVAAVersion,
		GuardianSetIndex: p.gs.Index,
		Signatures:       nil,
		Timestamp:        k.Timestamp,
		Payload: &vaa.BodyTransfer{
			Nonce:         k.Nonce,
			SourceChain:   k.SourceChain,
			TargetChain:   k.TargetChain,
			SourceAddress: k.SourceAddress,
			TargetAddress: k.TargetAddress,
			Asset: &vaa.AssetMeta{
				Chain:    k.TokenChain,
				Address:  k.TokenAddress,
				Decimals: k.TokenDecimals,
			},
			Amount: k.Amount,
		},
	}

	// Generate digest of the unsigned VAA.
	digest, err := v.SigningMsg()
	if err != nil {
		panic(err)
	}

	// Sign the digest using our node's guardian key.
	s, err := crypto.Sign(digest.Bytes(), p.gk)
	if err != nil {
		panic(err)
	}
	......
	p.broadcastSignature(v, s)
}

3）提交post_vaa()给Solana转账。

			else {
                // Foreign (native) -> Solana (wrapped)
                let wrapped_key = Bridge::derive_wrapped_asset_id(
                    program_id,
                    &bridge_key,
                    t.asset.chain,
                    t.asset.decimals,
                    t.asset.address,
                )?;
                let wrapped_meta_key =
                    Bridge::derive_wrapped_meta_id(program_id, &bridge_key, &wrapped_key)?;
                accounts.push(AccountMeta::new_readonly(spl_token::id(), false));
                accounts.push(AccountMeta::new(wrapped_key, false));
                accounts.push(AccountMeta::new(Pubkey::new(&t.target_address), false));
                accounts.push(AccountMeta::new(wrapped_meta_key, false));
            }

相应的log为：

Program WormT3McKhFJ2RkiGpdw9GKvNCrB2aB54gb2uV9MfQC invoke [1]
Instruction: PostVAA
Program TokenkegQfeZyiNwAJbNbGKPFXCWuBvf9Ss623VQ5DA invoke [2]
Instruction: MintTo
Program TokenkegQfeZyiNwAJbNbGKPFXCWuBvf9Ss623VQ5DA consumed 2779 of 104301 compute units
Program TokenkegQfeZyiNwAJbNbGKPFXCWuBvf9Ss623VQ5DA success
deriving key
deploying contract
Program 11111111111111111111111111111111 invoke [2]
Program 11111111111111111111111111111111 success
Program WormT3McKhFJ2RkiGpdw9GKvNCrB2aB54gb2uV9MfQC consumed 124268 of 200000 compute units
Program WormT3McKhFJ2RkiGpdw9GKvNCrB2aB54gb2uV9MfQC success

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