path: root/ethchain/block_chain.go

package ethchain

import (
    "bytes"
    "github.com/ethereum/eth-go/ethutil"
    "github.com/ethereum/eth-go/ethwire"
    "log"
    "math"
    "math/big"
)

type BlockChain struct {
    Ethereum EthManager
    // The famous, the fabulous Mister GENESIIIIIIS (block)
    genesisBlock *Block
    // Last known total difficulty
    TD *big.Int

    LastBlockNumber uint64

    CurrentBlock  *Block
    LastBlockHash []byte
}

func NewBlockChain(ethereum EthManager) *BlockChain {
    bc := &BlockChain{}
    bc.genesisBlock = NewBlockFromData(ethutil.Encode(Genesis))
    bc.Ethereum = ethereum

    bc.setLastBlock()

    return bc
}

func (bc *BlockChain) Genesis() *Block {
    return bc.genesisBlock
}

func (bc *BlockChain) NewBlock(coinbase []byte, txs []*Transaction) *Block {
    var root interface{}
    var lastBlockTime int64
    hash := ZeroHash256

    if bc.CurrentBlock != nil {
        root = bc.CurrentBlock.state.trie.Root
        hash = bc.LastBlockHash
        lastBlockTime = bc.CurrentBlock.Time
    }
    block := CreateBlock(
        root,
        hash,
        coinbase,
        ethutil.BigPow(2, 32),
        nil,
        "",
        txs)

    if bc.CurrentBlock != nil {
        var mul *big.Int
        if block.Time < lastBlockTime+42 {
            mul = big.NewInt(1)
        } else {
            mul = big.NewInt(-1)
        }

        diff := new(big.Int)
        diff.Add(diff, bc.CurrentBlock.Difficulty)
        diff.Div(diff, big.NewInt(1024))
        diff.Mul(diff, mul)
        diff.Add(diff, bc.CurrentBlock.Difficulty)
        block.Difficulty = diff
    }

    return block
}

func (bc *BlockChain) HasBlock(hash []byte) bool {
    data, _ := ethutil.Config.Db.Get(hash)
    return len(data) != 0
}

// TODO: At one point we might want to save a block by prevHash in the db to optimise this...
func (bc *BlockChain) HasBlockWithPrevHash(hash []byte) bool {
    block := bc.CurrentBlock

    for ; block != nil; block = bc.GetBlock(block.PrevHash) {
        if bytes.Compare(hash, block.PrevHash) == 0 {
            return true
        }
    }
    return false
}

func (bc *BlockChain) CalculateBlockTD(block *Block) *big.Int {
    blockDiff := new(big.Int)

    for _, uncle := range block.Uncles {
        blockDiff = blockDiff.Add(blockDiff, uncle.Difficulty)
    }
    blockDiff = blockDiff.Add(blockDiff, block.Difficulty)

    return blockDiff
}

// Is tasked by finding the CanonicalChain and resetting the chain if we are not the Conical one
func (bc *BlockChain) FindCanonicalChain(msg *ethwire.Msg, commonBlockHash []byte) {
    // 1. Calculate TD of the current chain
    // 2. Calculate TD of the new chain
    // Reset state to the correct one

    chainDifficulty := new(big.Int)

    // Calculate the entire chain until the block we both have
    // Start with the newest block we got, all the way back to the common block we both know
    for i := 0; i < (msg.Data.Len() - 1); i++ {
        block := NewBlockFromRlpValue(msg.Data.Get(i))
        if bytes.Compare(block.Hash(), commonBlockHash) == 0 {
            log.Println("[BCHAIN] We have found the common parent block, breaking")
            break
        }
        chainDifficulty.Add(chainDifficulty, bc.CalculateBlockTD(block))
    }

    log.Println("[BCHAIN] Incoming chain difficulty:", chainDifficulty)

    curChainDifficulty := new(big.Int)
    block := bc.CurrentBlock

    for ; block != nil; block = bc.GetBlock(block.PrevHash) {
        if bytes.Compare(block.Hash(), commonBlockHash) == 0 {
            log.Println("[BCHAIN] We have found the common parent block, breaking")
            break
        }
        curChainDifficulty.Add(curChainDifficulty, bc.CalculateBlockTD(block))
    }

    log.Println("[BCHAIN] Current chain difficulty:", curChainDifficulty)
    if chainDifficulty.Cmp(curChainDifficulty) == 1 {
        log.Println("[BCHAIN] The incoming Chain beat our asses, resetting")
        bc.ResetTillBlockHash(commonBlockHash)
    } else {
        log.Println("[BCHAIN] Our chain showed the incoming chain who is boss. Ignoring.")
    }
}
func (bc *BlockChain) ResetTillBlockHash(hash []byte) error {
    lastBlock := bc.CurrentBlock
    returnTo := bc.GetBlock(hash)

    // TODO: REFACTOR TO FUNCTION, Used multiple times
    bc.CurrentBlock = returnTo
    bc.LastBlockHash = returnTo.Hash()
    info := bc.BlockInfo(returnTo)
    bc.LastBlockNumber = info.Number
    // END TODO

    bc.Ethereum.StateManager().PrepareDefault(returnTo)
    err := ethutil.Config.Db.Delete(lastBlock.Hash())
    if err != nil {
        return err
    }

    var block *Block
    for ; block != nil; block = bc.GetBlock(block.PrevHash) {
        if bytes.Compare(block.Hash(), hash) == 0 {
            log.Println("[CHAIN] We have arrived at the the common parent block, breaking")
            break
        }
        err = ethutil.Config.Db.Delete(block.Hash())
        if err != nil {
            return err
        }
    }
    log.Println("[CHAIN] Split chain deleted and reverted to common parent block.")
    return nil
}

func (bc *BlockChain) GenesisBlock() *Block {
    return bc.genesisBlock
}

// Get chain return blocks from hash up to max in RLP format
func (bc *BlockChain) GetChainFromHash(hash []byte, max uint64) []interface{} {
    var chain []interface{}
    // Get the current hash to start with
    currentHash := bc.CurrentBlock.Hash()
    // Get the last number on the block chain
    lastNumber := bc.BlockInfo(bc.CurrentBlock).Number
    // Get the parents number
    parentNumber := bc.BlockInfoByHash(hash).Number
    // Get the min amount. We might not have max amount of blocks
    count := uint64(math.Min(float64(lastNumber-parentNumber), float64(max)))
    startNumber := parentNumber + count

    num := lastNumber
    for ; num > startNumber; currentHash = bc.GetBlock(currentHash).PrevHash {
        num--
    }
    for i := uint64(0); bytes.Compare(currentHash, hash) != 0 && num >= parentNumber && i < count; i++ {
        // Get the block of the chain
        block := bc.GetBlock(currentHash)
        currentHash = block.PrevHash

        chain = append(chain, block.Value().Val)

        num--
    }

    return chain
}

func (bc *BlockChain) GetChain(hash []byte, amount int) []*Block {
    genHash := bc.genesisBlock.Hash()

    block := bc.GetBlock(hash)
    var blocks []*Block

    for i := 0; i < amount && block != nil; block = bc.GetBlock(block.PrevHash) {
        blocks = append([]*Block{block}, blocks...)

        if bytes.Compare(genHash, block.Hash()) == 0 {
            break
        }
        i++
    }

    return blocks
}

func AddTestNetFunds(block *Block) {
    for _, addr := range []string{
        "8a40bfaa73256b60764c1bf40675a99083efb075", // Gavin
        "e6716f9544a56c530d868e4bfbacb172315bdead", // Jeffrey
        "1e12515ce3e0f817a4ddef9ca55788a1d66bd2df", // Vit
        "1a26338f0d905e295fccb71fa9ea849ffa12aaf4", // Alex
        "2ef47100e0787b915105fd5e3f4ff6752079d5cb", // Maran
    } {
        //log.Println("2^200 Wei to", addr)
        codedAddr := ethutil.FromHex(addr)
        addr := block.state.GetAccount(codedAddr)
        addr.Amount = ethutil.BigPow(2, 200)
        block.state.UpdateAccount(codedAddr, addr)
    }
}

func (bc *BlockChain) setLastBlock() {
    data, _ := ethutil.Config.Db.Get([]byte("LastBlock"))
    if len(data) != 0 {
        block := NewBlockFromBytes(data)
        info := bc.BlockInfo(block)
        bc.CurrentBlock = block
        bc.LastBlockHash = block.Hash()
        bc.LastBlockNumber = info.Number

        log.Printf("[CHAIN] Last known block height #%d\n", bc.LastBlockNumber)
    } else {
        AddTestNetFunds(bc.genesisBlock)

        bc.genesisBlock.state.trie.Sync()
        // Prepare the genesis block
        bc.Add(bc.genesisBlock)

        //log.Printf("root %x\n", bm.bc.genesisBlock.State().Root)
        //bm.bc.genesisBlock.PrintHash()
    }

    // Set the last know difficulty (might be 0x0 as initial value, Genesis)
    bc.TD = ethutil.BigD(ethutil.Config.Db.LastKnownTD())

    log.Printf("Last block: %x\n", bc.CurrentBlock.Hash())
}

func (bc *BlockChain) SetTotalDifficulty(td *big.Int) {
    ethutil.Config.Db.Put([]byte("LastKnownTotalDifficulty"), td.Bytes())
    bc.TD = td
}

// Add a block to the chain and record addition information
func (bc *BlockChain) Add(block *Block) {
    bc.writeBlockInfo(block)
    // Prepare the genesis block

    bc.CurrentBlock = block
    bc.LastBlockHash = block.Hash()

    encodedBlock := block.RlpEncode()
    ethutil.Config.Db.Put(block.Hash(), encodedBlock)
    ethutil.Config.Db.Put([]byte("LastBlock"), encodedBlock)
}

func (bc *BlockChain) GetBlock(hash []byte) *Block {
    data, _ := ethutil.Config.Db.Get(hash)
    if len(data) == 0 {
        return nil
    }

    return NewBlockFromData(data)
}

func (bc *BlockChain) BlockInfoByHash(hash []byte) BlockInfo {
    bi := BlockInfo{}
    data, _ := ethutil.Config.Db.Get(append(hash, []byte("Info")...))
    bi.RlpDecode(data)

    return bi
}

func (bc *BlockChain) BlockInfo(block *Block) BlockInfo {
    bi := BlockInfo{}
    data, _ := ethutil.Config.Db.Get(append(block.Hash(), []byte("Info")...))
    bi.RlpDecode(data)

    return bi
}

// Unexported method for writing extra non-essential block info to the db
func (bc *BlockChain) writeBlockInfo(block *Block) {
    bc.LastBlockNumber++
    bi := BlockInfo{Number: bc.LastBlockNumber, Hash: block.Hash(), Parent: block.PrevHash}

    // For now we use the block hash with the words "info" appended as key
    ethutil.Config.Db.Put(append(block.Hash(), []byte("Info")...), bi.RlpEncode())
}

func (bc *BlockChain) Stop() {
    if bc.CurrentBlock != nil {
        log.Println("[CHAIN] Stopped")
    }
}