dccs: re-apply dccs consensus to master branch (ethereum#243)

consensus/dccs/api.go

@@ -56,7 +56,7 @@ func (api *API) GetSnapshotAtHash(hash common.Hash) (*Snapshot, error) {
 }
 
 // GetSigners retrieves the list of authorized signers at the specified block.
-func (api *API) GetSigners(number *rpc.BlockNumber) ([]common.Address, error) {
+func (api *API) GetSigners(number *rpc.BlockNumber) ([]Signer, error) {
 	// Retrieve the requested block number (or current if none requested)
 	var header *types.Header
 	if number == nil || *number == rpc.LatestBlockNumber {
@@ -76,7 +76,7 @@ func (api *API) GetSigners(number *rpc.BlockNumber) ([]common.Address, error) {
 }
 
 // GetSignersAtHash retrieves the list of authorized signers at the specified block.
-func (api *API) GetSignersAtHash(hash common.Hash) ([]common.Address, error) {
+func (api *API) GetSignersAtHash(hash common.Hash) ([]Signer, error) {
 	header := api.chain.GetHeaderByHash(hash)
 	if header == nil {
 		return nil, errUnknownBlock

consensus/dccs/dccs.go

@@ -463,7 +463,7 @@ func (d *Dccs) verifyCascadingFields2(chain consensus.ChainReader, header *types
 	if d.config.IsCheckpoint(number) {
 		signers := make([]byte, len(snap.Signers)*common.AddressLength)
 		for i, signer := range snap.signers2() {
-			copy(signers[i*common.AddressLength:], signer[:])
+			copy(signers[i*common.AddressLength:], signer.Address[:])
 		}
 		extraSuffix := len(header.Extra) - extraSeal
 		if !bytes.Equal(header.Extra[extraVanity:extraSuffix], signers) {
@@ -842,7 +842,7 @@ func (d *Dccs) prepare2(chain consensus.ChainReader, header *types.Header) error
 
 	if d.config.IsCheckpoint(number) {
 		for _, signer := range snap.signers2() {
-			header.Extra = append(header.Extra, signer[:]...)
+			header.Extra = append(header.Extra, signer.Address[:]...)
 		}
 	}
 	header.Extra = append(header.Extra, make([]byte, extraSeal)...)
@@ -1205,7 +1205,7 @@ func (d *Dccs) calcDelayTime(snap *Snapshot, block *types.Block, signer common.A
 	sigs := snap.signers2()
 	pos := 0
 	for seen, sig := range sigs {
-		if sig == signer {
+		if sig.Address == signer {
 			pos = seen
 		}
 	}

consensus/dccs/snapshot.go

@@ -27,7 +27,9 @@ import (
 	"github.com/ethereum/go-ethereum/ethdb"
 	"github.com/ethereum/go-ethereum/log"
 	"github.com/ethereum/go-ethereum/params"
+	"github.com/ethereum/go-ethereum/rlp"
 	lru "github.com/hashicorp/golang-lru"
+	"golang.org/x/crypto/sha3"
 )
 
 // Vote represents a single vote that an authorized signer made to modify the
@@ -66,6 +68,23 @@ func (s signersAscending) Len() int           { return len(s) }
 func (s signersAscending) Less(i, j int) bool { return bytes.Compare(s[i][:], s[j][:]) < 0 }
 func (s signersAscending) Swap(i, j int)      { s[i], s[j] = s[j], s[i] }
 
+// Signer contain data of signer's address and checkpoint block hash
+type Signer struct {
+	Hash    common.Hash
+	Address common.Address
+}
+
+// signersAscendingByHash implements the sort interface to allow sorting a list of signers by hash
+type signersAscendingByHash []Signer
+
+func (sn signersAscendingByHash) Len() int { return len(sn) }
+func (sn signersAscendingByHash) Less(i, j int) bool {
+	h1 := rlpHash(sn[i])
+	h2 := rlpHash(sn[j])
+	return bytes.Compare(h1[:], h2[:]) < 0
+}
+func (sn signersAscendingByHash) Swap(i, j int) { sn[i], sn[j] = sn[j], sn[i] }
+
 // newSnapshot creates a new snapshot with the specified startup parameters. This
 // method does not initialize the set of recent signers, so only ever use if for
 // the genesis block.
@@ -316,9 +335,14 @@ func (s *Snapshot) signers() []common.Address {
 	return sigs
 }
 
-// signers retrieves the list of authorized signers in ascending order.
-func (s *Snapshot) signers2() []common.Address {
-	return s.signers()
+// signers2 retrieves the list of authorized signers in hash ascending order.
+func (s *Snapshot) signers2() []Signer {
+	sigs := make([]Signer, 0, len(s.Signers))
+	for sig := range s.Signers {
+		sigs = append(sigs, Signer{Hash: s.Hash, Address: sig})
+	}
+	sort.Sort(signersAscendingByHash(sigs))
+	return sigs
 }
 
 // inturn returns if a signer at a given block height is in-turn or not.
@@ -341,9 +365,9 @@ func (s *Snapshot) inturn2(signer common.Address, parent *types.Header) bool {
 	return offset == 0
 }
 
-func signerPosition(signer common.Address, signers []common.Address) (int, bool) {
+func signerPosition(signer common.Address, signers []Signer) (int, bool) {
 	for i, sig := range signers {
-		if sig == signer {
+		if sig.Address == signer {
 			return i, true
 		}
 	}
@@ -408,3 +432,14 @@ func (s *Snapshot) difficulty(signer common.Address, parent *types.Header) uint6
 
 	return uint64(n - offset)
 }
+
+// rlpHash return hash of an input
+func rlpHash(s Signer) (h common.Hash) {
+	hasher := sha3.NewLegacyKeccak256()
+	rlp.Encode(hasher, []interface{}{
+		s.Address,
+		s.Hash,
+	})
+	hasher.Sum(h[:0])
+	return h
+}