bsc

Brief Description

The LightNode.sol contract is an custom implementation of BSC light client on map chain. basis for implementation

The LightNodeProxy.sol contract is an proxy contract of LightNode.sol.

The MPTVerify.sol contract is receipt MerklePatriciaProof verify util.

Main interfaces explanation

the light node implementation principle is to verify the legitimacy of the block header by tracking validatorSet changes.

If we want to validate a transaction, we need to validate the block header that the transaction is in,to validate a block header and we need to validate the signature of the block header.

by tracking validatorSet changes light node can verify all bsc transations.

Here are some important public interfaces.

• Initialize the light client

   function initialize(
          uint256 _chainId,
          uint256 _minEpochBlockExtraDataLen,
          address _controller,
          address _mptVerify,
          Verify.BlockHeader[2] memory _headers
      ) public initializer 

  to set _chainId for bsc mainnet or testnet , and pre set two consecutively epoch validatorSet. this initialization data can verify everyone.

• syncing block header

   function updateBlockHeader(bytes memory _blockHeadersBytes)
          external
          override
          whenNotPaused
  // _blockHeadersBytes: abi.encode(_blockHeaders)  BlockHeader[] memory _blockHeaders
  

  submit epoch block header to keep track of validatorSet changes for each epoch.To prove epoch block header legitimacy, (validatorSet length / 2) block headers need to be submitted consecutively. If consecutive blockheaders are signed by different signers in validatorSet we don't believe it was forged

• verify transaction receipt

  struct ProofData {
          Verify.BlockHeader[] headers;
          Verify.ReceiptProof receiptProof;
   }
  function verifyProofData(bytes memory _receiptProof)
          external
          view
          override
          returns (
              bool success,
              string memory message,
              bytes memory logs
          )
  // _receiptProof: abi.encode(_receiptProof)  ProofData memory _proof

  verify transaction receipt and return receipt logs if succeed.

• get verifiable range

  function verifiableHeaderRange() external view returns (uint256, uint256);
  

  returns the range of the execution layer block header number between which you can verify the proof through the above interface verifyProofData.

Contract Deployment Workflow

Pre-requirement

Since all of the contracts are developed in Hardhat development environment, developers need to install Hardhat before working through our contracts. The hardhat installation tutorial can be found herehardhat

install

npm install

create an .env file and fill following in the contents

#your ethereum account private key
PRIVATE_KEY = 
# bsc rpc url
BSCURI = 
# mainnet 56 testnet 97
CHAINID = 
// 0 - for latest  block number start to syncing
START_SYNCY_BLOCK = 0
# bsc mainnet 317 testnet 197
MinEpochBlockExtraDataLen = 317

Compiling contracts

We can simply use hardhat built-in compile task to compile our contract in the contracts folder.

$ npx hardhat compile
Compiling...
Compiled 1 contract successfully

The compiled artifacts will be saved in the artifacts/ directory by default

Testing contracts

$ npx hardhat test
Compiled 19 Solidity files successfully


  lightNode
    Deployment
Implementation deployed to ..... 0x5FbDB2315678afecb367f032d93F642f64180aa3
lightNodeProxy deployed to ..... 0x9fE46736679d2D9a65F0992F2272dE9f3c7fa6e0
      √ initWithValidators must owner (721ms)
      √ initWithBlock must owner (441ms)
      √ init should be ok (573ms)
      √ Implementation upgradle must admin (102ms)
      √ Implementation upgradle ok (128ms)
      √ change admin  (78ms)
      √ trigglePause  only admin  (111ms)
      √ updateBlockHeader ... paused  (504ms)


  8 passing (3s)

Deploy contracts

The deploy script is located in deploy folder . We can run the following command to deploy.

//deploy MPTVerify
npx hardhat deploy --tags MPTVerify

//deploy MPTVerify on makalu network
npx hardhat deploy --tags MPTVerify --network makalu

//deploy lightNode implementation
npx hardhat deploy --tags LightNode

//deploy lightNode implementation on makalu network
npx hardhat deploy --tags LightNode --network makalu

//deploy lightNode proxy 
npx hardhat deploy --tags Proxy

//deploy lightNode proxy on makalu network
npx hardhat deploy --tags Proxy --network makalu

// upgrade 
npx hardhat deploy --tags Upgrade --network makalu

more details about hardhat-deploy are available

makalu faucet