dbft: use Governance contract for validators calculations

A part of #14.

Signed-off-by: Anna Shaleva <[email protected]>

Author: AnnaShaleva

consensus/dbft/dbft.go

@@ -28,6 +28,7 @@ import (
 	"math"
 	"math/big"
 	"sort"
+	"strings"
 	"sync"
 	"sync/atomic"
 	"time"
@@ -243,6 +244,11 @@ func New(config *params.DBFTConfig, _ ethdb.Database) (*DBFT, error) {
 	copy(conf.StandByValidators, config.StandByValidators)
 	slices.SortFunc(conf.StandByValidators, common.Address.Cmp)
 
+	govABI, err := abi.JSON(strings.NewReader(systemcontracts.GovernanceABI))
+	if err != nil {
+		return nil, fmt.Errorf("failed to parse Governance contract ABI")
+	}
+
 	c := &DBFT{
 		config:     &conf,
 		blockQueue: newBlockQueue(),
@@ -253,6 +259,8 @@ func New(config *params.DBFTConfig, _ ethdb.Database) (*DBFT, error) {
 
 		quit:     make(chan struct{}),
 		finished: make(chan struct{}),
+
+		governanceABI: govABI,
 	}
 
 	logger, _ := zap.NewDevelopment()
@@ -1375,6 +1383,7 @@ func payloadFromMessage(ep *dbftproto.Message) *Payload {
 
 func (c *DBFT) validatePayload(p *Payload) bool {
 	h := c.chain.CurrentBlock()
+	// TODO: need validators cache at least for payloads verification, otherwise we'll end up in endless state-dependent computations.
 	validators, err := c.getNextBlockValidators(h.Hash(), h.Number.Uint64(), false)
 	if err != nil {
 		return false
@@ -1593,7 +1602,8 @@ func (c *DBFT) APIs(chain consensus.ChainHeaderReader) []rpc.API {
 // to be sorted by bytes order (even if returned from governance contract).
 func (c *DBFT) getNextBlockValidators(blockHash common.Hash, blockNum uint64, compute bool) ([]common.Address, error) {
 	// Currently we don't have governance contract, thus, always return standby set.
-	if true {
+	// TODO: to be removed.
+	if blockNum == 0 {
 		return c.config.StandByValidators, nil
 	}
 
@@ -1603,13 +1613,20 @@ func (c *DBFT) getNextBlockValidators(blockHash common.Hash, blockNum uint64, co
 
 	// Once we have governance contract, we don't need StandByValidators in the dBFT's
 	// config, governance contract will handle it internally.
-	blockNr := rpc.BlockNumberOrHashWithHash(blockHash, false)
+	blockNr := rpc.BlockNumberOrHashWithNumber(rpc.BlockNumber(blockNum))
 
 	// Different values depending on dBFT epoch.
-	method := "getNextBlockValidators" // current epoch validators
-	if compute {
-		method = "computeNextBlockValidators" // current epoch validators for the middle of dBFT epoch and next epoch validators for the last block in epoch
-	}
+	method := "getCurrentConsensus" // current epoch validators
+	/*if compute {
+		// TODO: given time-dependent `EPOCH_DURATION`, calculation of next consensus becomes complicated. We need
+		// `getNextConsensus` API to be presented in Governance contract since `getConsensus` is not enough.
+		// `getConsensus` calculates consensus based on the current state, even if epoch is not finished yet. What we need
+		// is `getNextConsensus` that returns current epoch validators for the middle of dBFT epoch and next epoch validators
+		// for the last block in the epoch. We can organize this at the code-level, but it complicates getNextBlockValidators call, so
+		// why not to move it to the contract level where it costs nothing.
+		// @roman-khimov, agree?
+		method = "getNextConsensus" // current epoch validators for the middle of dBFT epoch and next epoch validators for the last block in epoch
+	}*/
 
 	ctx, cancel := context.WithCancel(context.Background())
 	// Cancel when we are finished consuming integers
@@ -1621,7 +1638,7 @@ func (c *DBFT) getNextBlockValidators(blockHash common.Hash, blockNum uint64, co
 	}
 	// do smart contract call
 	msgData := (hexutil.Bytes)(data)
-	toAddress := common.HexToAddress(systemcontracts.GovernanceContract)
+	toAddress := common.HexToAddress(systemcontracts.GovernanceHash)
 	gas := (hexutil.Uint64)(uint64(math.MaxUint64 / 2))
 	result, err := c.ethAPI.Call(ctx, ethapi.TransactionArgs{
 		Gas:  &gas,
@@ -1634,6 +1651,10 @@ func (c *DBFT) getNextBlockValidators(blockHash common.Hash, blockNum uint64, co
 
 	var valSet []common.Address
 	err = c.governanceABI.UnpackIntoInterface(&valSet, method, result)
+
+	// TODO: roman-khimov, we've agreed that validators are sorted using lexicographic order, but in contract they are
+	// sorted by votes. Need to come to some single solution.
+	slices.SortFunc(valSet, common.Address.Cmp)
 	return valSet, err
 }