pbft.go

package pbft

import (
	"bytes"
	"errors"
	"io"
	"math/big"
_	"math/rand"
	"sync"
	"time"
    "runtime"
    "fmt"
    "sort"
    "strings"

	"github.com/ethereum/go-ethereum/accounts"
	"github.com/ethereum/go-ethereum/common"
_	"github.com/ethereum/go-ethereum/common/hexutil"
	"github.com/ethereum/go-ethereum/consensus"
	"github.com/ethereum/go-ethereum/consensus/misc"
	"github.com/ethereum/go-ethereum/core/state"
	"github.com/ethereum/go-ethereum/core/types"
_	"github.com/ethereum/go-ethereum/crypto"
	"github.com/ethereum/go-ethereum/ethdb"
    "github.com/ethereum/go-ethereum/log"
	"github.com/ethereum/go-ethereum/params"
	"github.com/ethereum/go-ethereum/rlp"
	"github.com/ethereum/go-ethereum/rpc"
_	"github.com/hashicorp/golang-lru"
	"golang.org/x/crypto/sha3"
)
var (
	extraVanity = 32 // Fixed number of extra-data prefix bytes reserved for signer vanity
	extraSeal   = 65 // Fixed number of extra-data suffix bytes reserved for signer seal
    maxClients = 4
	uncleHash = types.CalcUncleHash(nil) // Always Keccak256(RLP([])) as uncles are meaningless outside of PoW.
)

var (
	// errUnknownBlock is returned when the list of signers is requested for a block
	// that is not part of the local blockchain.
	errUnknownBlock = errors.New("unknown block")
	// errUnauthorizedSigner is returned if a header is signed by a non-authorized entity.
	errUnauthorizedSigner = errors.New("unauthorized signer")
	// errMissingVanity is returned if a block's extra-data section is shorter than
	// 32 bytes, which is required to store the signer vanity.
	errMissingVanity = errors.New("extra-data 32 byte vanity prefix missing")
	// errMissingSignature is returned if a block's extra-data section doesn't seem
	// to contain a 65 byte secp256k1 signature.
	errMissingSignature = errors.New("extra-data 65 byte signature suffix missing")
	// errInvalidMixDigest is returned if a block's mix digest is non-zero.
	errInvalidMixDigest = errors.New("non-zero mix digest")
	// errInvalidUncleHash is returned if a block contains an non-empty uncle list.
	errInvalidUncleHash = errors.New("non empty uncle hash")
)

func trace() {
    pc := make([]uintptr, 10)  // at least 1 entry needed
    runtime.Callers(2, pc)
    f := runtime.FuncForPC(pc[0])
    file, line := f.FileLine(pc[0])
    fmt.Printf("%s:%d %s\n", file, line, f.Name())
}

type SignerFn func(accounts.Account, string, []byte) ([]byte, error)

type PbftClients []common.Address
func (s PbftClients) Len() int           { return len(s) }
func (s PbftClients) Less(i, j int) bool { return strings.Compare(string(s[i].Bytes()), string(s[j].Bytes())) < 0 }
func (s PbftClients) Swap(i, j int)      { s[i], s[j] = s[j], s[i] }

type Pbft struct {
	config *params.PbftConfig // Consensus engine configuration parameters
	db     ethdb.Database       // Database to store and retrieve snapshot checkpoints

    clients PbftClients //signer list - should be ordered

	signer common.Address // Ethereum address of the signing key
	signFn SignerFn       // Signer function to authorize hashes with
	lock   sync.RWMutex   // Protects the signer fields
}

func New(config *params.PbftConfig, db ethdb.Database) *Pbft {
    trace()
	// Set any missing consensus parameters to their defaults
	conf := *config

	return &Pbft{
		config:     &conf,
		db:         db,
        clients: make([]common.Address, 0), //signer list - should be ordered
	}
}

func (p *Pbft) AddClient(client common.Address) bool {
    trace()
    if len(p.clients) == maxClients {
        return false
    }
    if len(p.clients)+1 == cap(p.clients) {
        clients := make([]common.Address, len(p.clients), len(p.clients)+1)
        copy(clients, p.clients)
        p.clients = clients
    }
    p.clients = append(p.clients, client)
    sort.Sort(p.clients)

    fmt.Printf("===============%x\n",p.clients)
    return true
}

func (p *Pbft) IsPrimary(producer common.Address, blockNumber uint64) bool {
    trace()
    fmt.Printf("===============%x\n",blockNumber)
    fmt.Printf("===============%x\n",producer)
    fmt.Printf("===============%x\n",p.clients)
    fmt.Printf("===============%x\n",len(p.clients))
    peerCount := len(p.clients)
    if p.clients[blockNumber % uint64(peerCount)] == producer {
        if peerCount == 1 {
            return true
        } else {
            if p.clients[blockNumber % uint64(peerCount)] == producer {
                return true
            }
        }
    }
    return false
}

func PbftRLP(header *types.Header) []byte {
    trace()
	b := new(bytes.Buffer)
	encodeSigHeader(b, header)
	return b.Bytes()
}

func encodeSigHeader(w io.Writer, header *types.Header) {
    trace()
	err := rlp.Encode(w, []interface{}{
		header.ParentHash,
		header.UncleHash,
		header.Coinbase,
		header.Root,
		header.TxHash,
		header.ReceiptHash,
		header.Bloom,
		header.Difficulty,
		header.Number,
		header.GasLimit,
		header.GasUsed,
		header.Time,
		header.Extra[:len(header.Extra)-65], // Yes, this will panic if extra is too short
		header.MixDigest,
		header.Nonce,
	})
	if err != nil {
		panic("can't encode: " + err.Error())
	}
}

// SealHash returns the hash of a block prior to it being sealed.
func SealHash(header *types.Header) (hash common.Hash) {
    trace()
	hasher := sha3.NewLegacyKeccak256()
	encodeSigHeader(hasher, header)
	hasher.Sum(hash[:0])
	return hash
}

func (p *Pbft) Authorize(signer common.Address, signFn SignerFn) {
    trace()
	p.lock.Lock()
	defer p.lock.Unlock()

	p.signer = signer
	p.signFn = signFn
}

// Author retrieves the Ethereum address of the account that minted the given
// block, which may be different from the header's coinbase if a consensus
// engine is based on signatures.
func (p *Pbft) Author(header *types.Header) (common.Address, error) {
    trace()
    return header.Coinbase, nil
}

// VerifyHeader checks whether a header conforms to the consensus rules of a
// given engine. Verifying the seal may be done optionally here, or explicitly
// via the VerifySeal method.
func (p *Pbft) VerifyHeader(chain consensus.ChainReader, header *types.Header, seal bool) error {
    trace()
	return p.verifyHeader(chain, header, nil)
}
func (p *Pbft) verifyHeader(chain consensus.ChainReader, header *types.Header, parents []*types.Header) error {
    trace()
	if header.Number == nil {
		return errUnknownBlock
	}
	number := header.Number.Uint64()

	// Don't waste time checking blocks from the future
	if header.Time > uint64(time.Now().Unix()) {
		return consensus.ErrFutureBlock
	}
/*
	// Nonces must be 0x00..0 or 0xff..f, zeroes enforced on checkpoints
	if !bytes.Equal(header.Nonce[:], nonceAuthVote) && !bytes.Equal(header.Nonce[:], nonceDropVote) {
		return errInvalidVote
	}
	if checkpoint && !bytes.Equal(header.Nonce[:], nonceDropVote) {
		return errInvalidCheckpointVote
	}
*/
	// Check that the extra-data contains both the vanity and signature
	if len(header.Extra) < extraVanity {
		return errMissingVanity
	}
	if len(header.Extra) < extraVanity+extraSeal {
		return errMissingSignature
	}
/*
	// Ensure that the extra-data contains a signer list on checkpoint, but none otherwise
	signersBytes := len(header.Extra) - extraVanity - extraSeal
	if !checkpoint && signersBytes != 0 {
		return errExtraSigners
	}
	if checkpoint && signersBytes%common.AddressLength != 0 {
		return errInvalidCheckpointSigners
	}
*/
	// Ensure that the mix digest is zero as we don't have fork protection currently
	if header.MixDigest != (common.Hash{}) {
		return errInvalidMixDigest
	}
	// Ensure that the block doesn't contain any uncles which are meaningless in PoA
	if header.UncleHash != uncleHash {
		return errInvalidUncleHash
	}
/*
	// Ensure that the block's difficulty is meaningful (may not be correct at this point)
	if number > 0 {
		if header.Difficulty == nil || (header.Difficulty.Cmp(diffInTurn) != 0 && header.Difficulty.Cmp(diffNoTurn) != 0) {
			return errInvalidDifficulty
		}
	}
*/
	// If all checks passed, validate any special fields for hard forks
	if err := misc.VerifyForkHashes(chain.Config(), header, false); err != nil {
		return err
	}
	// All basic checks passed, verify cascading fields
    if ok := p.IsPrimary(header.Coinbase, number); !ok {
        fmt.Printf("c===Out turn",p.clients)
		return errUnauthorizedSigner
	}
    fmt.Printf("c===good pass",p.clients)
	return nil
}

// VerifyHeaders is similar to VerifyHeader, but verifies a batch of headers
// concurrently. The method returns a quit channel to abort the operations and
// a results channel to retrieve the async verifications (the order is that of
// the input slice).
func (p *Pbft) VerifyHeaders(chain consensus.ChainReader, headers []*types.Header, seals []bool) (chan<- struct{}, <-chan error) {
    trace()
	abort := make(chan struct{})
	results := make(chan error, len(headers))

	go func() {
		for i, header := range headers {
			err := p.verifyHeader(chain, header, headers[:i])

			select {
			case <-abort:
				return
			case results <- err:
			}
		}
	}()
	return abort, results
}

// VerifyUncles verifies that the given block's uncles conform to the consensus
// rules of a given engine.
func (p *Pbft) VerifyUncles(chain consensus.ChainReader, block *types.Block) error {
    trace()
	return nil
}

// VerifySeal checks whether the crypto seal on a header is valid according to
// the consensus rules of the given engine.
func (p *Pbft) VerifySeal(chain consensus.ChainReader, header *types.Header) error {
    trace()
	return nil
}

func CalcDifficulty() *big.Int {
	return big.NewInt(10)
}

// Prepare initializes the consensus fields of a block header according to the
// rules of a particular engine. The changes are executed inline.
func (p *Pbft) Prepare(chain consensus.ChainReader, header *types.Header) error {
    trace()
	// If the block isn't a checkpoint, cast a random vote (good enough for now)
	//header.Coinbase = common.Address{}
	header.Nonce = types.BlockNonce{}

	number := header.Number.Uint64()

	// Set the correct difficulty
	header.Difficulty = CalcDifficulty()

	// Ensure the extra data has all it's components
	if len(header.Extra) < extraVanity {
		header.Extra = append(header.Extra, bytes.Repeat([]byte{0x00}, extraVanity-len(header.Extra))...)
	}
	header.Extra = header.Extra[:extraVanity]

	header.Extra = append(header.Extra, make([]byte, extraSeal)...)

	// Mix digest is reserved for now, set to empty
	header.MixDigest = common.Hash{}

	// Ensure the timestamp has the correct delay
	parent := chain.GetHeader(header.ParentHash, number-1)
	if parent == nil {
		return consensus.ErrUnknownAncestor
	}
	header.Time = parent.Time + p.config.Period
	if header.Time < uint64(time.Now().Unix()) {
		header.Time = uint64(time.Now().Unix())
	}
	return nil
}

// Finalize runs any post-transaction state modifications (e.g. block rewards)
// and assembles the final block.
// Note: The block header and state database might be updated to reflect any
// consensus rules that happen at finalization (e.g. block rewards).
func (p *Pbft) Finalize(chain consensus.ChainReader, header *types.Header, state *state.StateDB, txs []*types.Transaction, uncles []*types.Header, receipts []*types.Receipt) (*types.Block, error) {
    trace()
	// No block rewards in PoA, so the state remains as is and uncles are dropped
	header.Root = state.IntermediateRoot(chain.Config().IsEIP158(header.Number))
	header.UncleHash = types.CalcUncleHash(nil)

	// Assemble and return the final block for sealing
	return types.NewBlock(header, txs, nil, receipts), nil
}

// Seal generates a new sealing request for the given input block and pushes
// the result into the given channel.
//
// Note, the method returns immediately and will send the result async. More
// than one result may also be returned depending on the consensus algorithm.
func (p *Pbft) Seal(chain consensus.ChainReader, block *types.Block, results chan<- *types.Block, stop <-chan struct{}) error {
    trace()
	header := block.Header()

	// Sealing the genesis block is not supported
	number := header.Number.Uint64()
	if number == 0 {
		return errUnknownBlock
	}
	// For 0-period chains, refuse to seal empty blocks (no reward but would spin sealing)
	if p.config.Period == 0 && len(block.Transactions()) == 0 {
		log.Info("Sealing paused, waiting for transactions")
		return nil
	}
	// Don't hold the signer fields for the entire sealing procedure
	p.lock.RLock()
	signer, signFn := p.signer, p.signFn
	p.lock.RUnlock()

    if ok := p.IsPrimary(signer, number); !ok {
        fmt.Printf("Out turn  %x\n",number)
		return errUnauthorizedSigner
	}

	// Sweet, the protocol permits us to sign the block, wait for our time
	delay := time.Unix(int64(header.Time), 0).Sub(time.Now()) // nolint: gosimple

	// Sign all the things!
	sighash, err := signFn(accounts.Account{Address: signer}, accounts.MimetypePbft, PbftRLP(header))
	if err != nil {
		return err
	}
	log.Trace("Waiting for slot to sign and propagate", "delay", common.PrettyDuration(delay))
	copy(header.Extra[len(header.Extra)-extraSeal:], sighash)
	go func() {
		select {
		case <-stop:
			return
		case <-time.After(delay):
		}

		select {
		case results <- block.WithSeal(header):
		default:
			log.Warn("Sealing result is not read by miner", "sealhash", SealHash(header))
		}
	}()

	return nil
}

// SealHash returns the hash of a block prior to it being sealed.
func (p *Pbft) SealHash(header *types.Header) common.Hash {
    trace()
	return SealHash(header)
}

// CalcDifficulty is the difficulty adjustment algorithm. It returns the difficulty
// that a new block should have.
func (p *Pbft) CalcDifficulty(chain consensus.ChainReader, time uint64, parent *types.Header) *big.Int {
    trace()
	return new(big.Int).Set(big.NewInt(1))
}

// APIs returns the RPC APIs this consensus engine provides.
func (p *Pbft) APIs(chain consensus.ChainReader) []rpc.API {
    trace()
	return []rpc.API{{
		Namespace: "pbft",
		Version:   "0.1",
		Service:   &API{chain: chain, pbft: p},
		Public:    false,
	}}
}

// Close terminates any background threads maintained by the consensus engine.
func (p *Pbft) Close() error {
    trace()
	return nil
}