Merge pull request #2334 from nspcc-dev/extendable-validators

Extendable validators

docs/node-configuration.md

@@ -197,6 +197,7 @@ protocol-related settings described in the table below.
 
 | Section | Type | Default value | Description | Notes |
 | --- | --- | --- | --- | --- |
+| CommitteeHistory | map[uint32]int | none | Number of committee members after given height, for example `{0: 1, 20: 4}` sets up a chain with one committee member since the genesis and then changes the setting to 4 committee members at the height of 20. `StandbyCommittee` committee setting must have the number of keys equal or exceeding the highest value in this option. Blocks numbers where the change happens must be divisble by the old and by the new values simultaneously. If not set, committee size is derived from the `StandbyCommittee` setting and never changes. |
 | KeepOnlyLatestState | `bool` | `false` | Specifies if MPT should only store latest state. If true, DB size will be smaller, but older roots won't be accessible. This value should remain the same for the same database. |
 | Magic | `uint32` | `0` | Magic number which uniquely identifies NEO network. |
 | MaxBlockSize | `uint32` | `262144` | Maximum block size in bytes. |
@@ -216,6 +217,7 @@ protocol-related settings described in the table below.
 | StandbyCommittee | `[]string` | [] | List of public keys of standby committee validators are chosen from. |
 | StateRootInHeader | `bool` | `false` | Enables storing state root in block header. | Experimental protocol extension! |
 | StateSyncInterval | `int` | `40000` | The number of blocks between state heights available for MPT state data synchronization. | `P2PStateExchangeExtensions` should be enabled to use this setting.  |
-| ValidatorsCount | `int` | `0` | Number of validators. |
+| ValidatorsCount | `int` | `0` | Number of validators set for the whole network lifetime, can't be set if `ValidatorsHistory` setting is used. |
+| ValidatorsHistory | map[uint32]int | none | Number of consensus nodes to use after given height (see `CommitteeHistory` also). Heights where the change occurs must be divisible by the number of committee members at that height. Can't be used with `ValidatorsCount` not equal to zero. |
 | VerifyBlocks | `bool` | `false` | Denotes whether to verify received blocks. |
 | VerifyTransactions | `bool` | `false` | Denotes whether to verify transactions in received blocks. |

internal/fakechain/fakechain.go

@@ -300,16 +300,6 @@ func (chain *FakeChain) GetValidators() ([]*keys.PublicKey, error) {
 	panic("TODO")
 }
 
-// GetStandByCommittee implements Blockchainer interface.
-func (chain *FakeChain) GetStandByCommittee() keys.PublicKeys {
-	panic("TODO")
-}
-
-// GetStandByValidators implements Blockchainer interface.
-func (chain *FakeChain) GetStandByValidators() keys.PublicKeys {
-	panic("TODO")
-}
-
 // GetEnrollments implements Blockchainer interface.
 func (chain *FakeChain) GetEnrollments() ([]state.Validator, error) {
 	panic("TODO")

pkg/config/config.go

@@ -6,7 +6,6 @@ import (
 	"os"
 
 	"github.com/nspcc-dev/neo-go/pkg/config/netmode"
-	"github.com/nspcc-dev/neo-go/pkg/core/native/nativenames"
 	"github.com/nspcc-dev/neo-go/pkg/rpc"
 	"gopkg.in/yaml.v2"
 )
@@ -63,10 +62,9 @@ func LoadFile(configPath string) (Config, error) {
 		return Config{}, fmt.Errorf("failed to unmarshal config YAML: %w", err)
 	}
 
-	for name := range config.ProtocolConfiguration.NativeUpdateHistories {
-		if !nativenames.IsValid(name) {
-			return Config{}, fmt.Errorf("NativeActivations configuration section contains unexpected native contract name: %s", name)
-		}
+	err = config.ProtocolConfiguration.Validate()
+	if err != nil {
+		return Config{}, err
 	}
 
 	return config, nil

pkg/config/protocol_config.go

@@ -1,15 +1,22 @@
 package config
 
 import (
+	"errors"
+	"fmt"
+	"sort"
+
 	"github.com/nspcc-dev/neo-go/pkg/config/netmode"
+	"github.com/nspcc-dev/neo-go/pkg/core/native/nativenames"
 	"github.com/nspcc-dev/neo-go/pkg/encoding/fixedn"
 )
 
 // ProtocolConfiguration represents the protocol config.
 type (
 	ProtocolConfiguration struct {
-		Magic       netmode.Magic `yaml:"Magic"`
-		MemPoolSize int           `yaml:"MemPoolSize"`
+		// CommitteeHistory stores committee size change history (height: size).
+		CommitteeHistory map[uint32]int `yaml:"CommitteeHistory"`
+		Magic            netmode.Magic  `yaml:"Magic"`
+		MemPoolSize      int            `yaml:"MemPoolSize"`
 
 		// InitialGASSupply is the amount of GAS generated in the genesis block.
 		InitialGASSupply fixedn.Fixed8 `yaml:"InitialGASSupply"`
@@ -53,9 +60,123 @@ type (
 		// It is valid only if P2PStateExchangeExtensions are enabled.
 		StateSyncInterval int `yaml:"StateSyncInterval"`
 		ValidatorsCount   int `yaml:"ValidatorsCount"`
+		// Validators stores history of changes to consensus node number (height: number).
+		ValidatorsHistory map[uint32]int `yaml:"ValidatorsHistory"`
 		// Whether to verify received blocks.
 		VerifyBlocks bool `yaml:"VerifyBlocks"`
 		// Whether to verify transactions in received blocks.
 		VerifyTransactions bool `yaml:"VerifyTransactions"`
 	}
 )
+
+// heightNumber is an auxiliary structure for configuration checks.
+type heightNumber struct {
+	h uint32
+	n int
+}
+
+// Validate checks ProtocolConfiguration for internal consistency and returns
+// error if anything inappropriate found. Other methods can rely on protocol
+// validity after this.
+func (p *ProtocolConfiguration) Validate() error {
+	var err error
+
+	for name := range p.NativeUpdateHistories {
+		if !nativenames.IsValid(name) {
+			return fmt.Errorf("NativeActivations configuration section contains unexpected native contract name: %s", name)
+		}
+	}
+	if p.ValidatorsCount != 0 && len(p.ValidatorsHistory) != 0 {
+		return errors.New("configuration should either have ValidatorsCount or ValidatorsHistory, not both")
+	}
+	if len(p.StandbyCommittee) < p.ValidatorsCount {
+		return errors.New("validators count can't exceed the size of StandbyCommittee")
+	}
+	var arr = make([]heightNumber, 0, len(p.CommitteeHistory))
+	for h, n := range p.CommitteeHistory {
+		if int(n) > len(p.StandbyCommittee) {
+			return fmt.Errorf("too small StandbyCommittee for required number of committee members at %d", h)
+		}
+		arr = append(arr, heightNumber{h, n})
+	}
+	if len(arr) != 0 {
+		err = sortCheckZero(arr, "CommitteeHistory")
+		if err != nil {
+			return err
+		}
+		for i, hn := range arr[1:] {
+			if int64(hn.h)%int64(hn.n) != 0 || int64(hn.h)%int64(arr[i].n) != 0 {
+				return fmt.Errorf("invalid CommitteeHistory: bad %d height for %d and %d committee", hn.h, hn.n, arr[i].n)
+			}
+		}
+	}
+	arr = arr[:0]
+	for h, n := range p.ValidatorsHistory {
+		if int(n) > len(p.StandbyCommittee) {
+			return fmt.Errorf("too small StandbyCommittee for required number of validators at %d", h)
+		}
+		arr = append(arr, heightNumber{h, n})
+	}
+	if len(arr) != 0 {
+		err = sortCheckZero(arr, "ValidatorsHistory")
+		if err != nil {
+			return err
+		}
+		for _, hn := range arr {
+			if int64(hn.n) > int64(p.GetCommitteeSize(hn.h)) {
+				return fmt.Errorf("requested number of validators is too big: %d at %d", hn.n, hn.h)
+			}
+			if int64(hn.h)%int64(p.GetCommitteeSize(hn.h)) != 0 {
+				return fmt.Errorf("validators number change is not aligned with committee change at %d", hn.h)
+			}
+		}
+	}
+	return nil
+}
+
+// sortCheckZero sorts heightNumber array and checks for zero height presence.
+func sortCheckZero(arr []heightNumber, field string) error {
+	sort.Slice(arr, func(i, j int) bool {
+		return arr[i].h < arr[j].h
+	})
+	if arr[0].h != 0 {
+		return fmt.Errorf("invalid %s: no height 0 specified", field)
+	}
+	return nil
+}
+
+// GetCommitteeSize returns the committee size for the given height. It implies
+// valid configuration file.
+func (p *ProtocolConfiguration) GetCommitteeSize(height uint32) int {
+	if len(p.CommitteeHistory) == 0 {
+		return len(p.StandbyCommittee)
+	}
+	return getBestFromMap(p.CommitteeHistory, height)
+}
+
+func getBestFromMap(dict map[uint32]int, height uint32) int {
+	var res int
+	var bestH = uint32(0)
+	for h, n := range dict {
+		if h >= bestH && h <= height {
+			res = n
+			bestH = h
+		}
+	}
+	return res
+}
+
+// GetNumOfCNs returns the number of validators for the given height.
+// It implies valid configuration file.
+func (p *ProtocolConfiguration) GetNumOfCNs(height uint32) int {
+	if len(p.ValidatorsHistory) == 0 {
+		return p.ValidatorsCount
+	}
+	return getBestFromMap(p.ValidatorsHistory, height)
+}
+
+// ShouldUpdateCommitteeAt answers the question of whether the committee
+// should be updated at the given height.
+func (p *ProtocolConfiguration) ShouldUpdateCommitteeAt(height uint32) bool {
+	return height%uint32(p.GetCommitteeSize(height)) == 0
+}

pkg/config/protocol_config_test.go

@@ -0,0 +1,130 @@
+package config
+
+import (
+	"testing"
+
+	"github.com/stretchr/testify/require"
+)
+
+func TestProtocolConfigurationValidation(t *testing.T) {
+	p := &ProtocolConfiguration{
+		ValidatorsCount: 1,
+	}
+	require.Error(t, p.Validate())
+	p = &ProtocolConfiguration{
+		NativeUpdateHistories: map[string][]uint32{
+			"someContract": {0, 10},
+		},
+	}
+	require.Error(t, p.Validate())
+	p = &ProtocolConfiguration{
+		StandbyCommittee: []string{
+			"02b3622bf4017bdfe317c58aed5f4c753f206b7db896046fa7d774bbc4bf7f8dc2",
+			"02103a7f7dd016558597f7960d27c516a4394fd968b9e65155eb4b013e4040406e",
+		},
+		ValidatorsCount: 3,
+	}
+	require.Error(t, p.Validate())
+	p = &ProtocolConfiguration{
+		StandbyCommittee: []string{
+			"02b3622bf4017bdfe317c58aed5f4c753f206b7db896046fa7d774bbc4bf7f8dc2",
+			"02103a7f7dd016558597f7960d27c516a4394fd968b9e65155eb4b013e4040406e",
+			"03d90c07df63e690ce77912e10ab51acc944b66860237b608c4f8f8309e71ee699",
+			"02a7bc55fe8684e0119768d104ba30795bdcc86619e864add26156723ed185cd62",
+		},
+		ValidatorsCount:   4,
+		ValidatorsHistory: map[uint32]int{0: 4},
+	}
+	require.Error(t, p.Validate())
+	p = &ProtocolConfiguration{
+		StandbyCommittee: []string{
+			"02b3622bf4017bdfe317c58aed5f4c753f206b7db896046fa7d774bbc4bf7f8dc2",
+			"02103a7f7dd016558597f7960d27c516a4394fd968b9e65155eb4b013e4040406e",
+			"03d90c07df63e690ce77912e10ab51acc944b66860237b608c4f8f8309e71ee699",
+			"02a7bc55fe8684e0119768d104ba30795bdcc86619e864add26156723ed185cd62",
+		},
+		CommitteeHistory:  map[uint32]int{0: 4},
+		ValidatorsHistory: map[uint32]int{0: 4, 1000: 5},
+	}
+	require.Error(t, p.Validate())
+	p = &ProtocolConfiguration{
+		StandbyCommittee: []string{
+			"02b3622bf4017bdfe317c58aed5f4c753f206b7db896046fa7d774bbc4bf7f8dc2",
+			"02103a7f7dd016558597f7960d27c516a4394fd968b9e65155eb4b013e4040406e",
+			"03d90c07df63e690ce77912e10ab51acc944b66860237b608c4f8f8309e71ee699",
+			"02a7bc55fe8684e0119768d104ba30795bdcc86619e864add26156723ed185cd62",
+		},
+		CommitteeHistory:  map[uint32]int{0: 4, 1000: 5},
+		ValidatorsHistory: map[uint32]int{0: 4},
+	}
+	require.Error(t, p.Validate())
+	p = &ProtocolConfiguration{
+		StandbyCommittee: []string{
+			"02b3622bf4017bdfe317c58aed5f4c753f206b7db896046fa7d774bbc4bf7f8dc2",
+			"02103a7f7dd016558597f7960d27c516a4394fd968b9e65155eb4b013e4040406e",
+			"03d90c07df63e690ce77912e10ab51acc944b66860237b608c4f8f8309e71ee699",
+			"02a7bc55fe8684e0119768d104ba30795bdcc86619e864add26156723ed185cd62",
+		},
+		CommitteeHistory:  map[uint32]int{0: 1, 999: 4},
+		ValidatorsHistory: map[uint32]int{0: 1},
+	}
+	require.Error(t, p.Validate())
+	p = &ProtocolConfiguration{
+		StandbyCommittee: []string{
+			"02b3622bf4017bdfe317c58aed5f4c753f206b7db896046fa7d774bbc4bf7f8dc2",
+			"02103a7f7dd016558597f7960d27c516a4394fd968b9e65155eb4b013e4040406e",
+			"03d90c07df63e690ce77912e10ab51acc944b66860237b608c4f8f8309e71ee699",
+			"02a7bc55fe8684e0119768d104ba30795bdcc86619e864add26156723ed185cd62",
+		},
+		CommitteeHistory:  map[uint32]int{0: 1, 1000: 4},
+		ValidatorsHistory: map[uint32]int{0: 1, 999: 4},
+	}
+	require.Error(t, p.Validate())
+	p = &ProtocolConfiguration{
+		StandbyCommittee: []string{
+			"02b3622bf4017bdfe317c58aed5f4c753f206b7db896046fa7d774bbc4bf7f8dc2",
+			"02103a7f7dd016558597f7960d27c516a4394fd968b9e65155eb4b013e4040406e",
+			"03d90c07df63e690ce77912e10ab51acc944b66860237b608c4f8f8309e71ee699",
+			"02a7bc55fe8684e0119768d104ba30795bdcc86619e864add26156723ed185cd62",
+		},
+		CommitteeHistory:  map[uint32]int{0: 1, 100: 4},
+		ValidatorsHistory: map[uint32]int{0: 4, 100: 4},
+	}
+	require.Error(t, p.Validate())
+	p = &ProtocolConfiguration{
+		StandbyCommittee: []string{
+			"02b3622bf4017bdfe317c58aed5f4c753f206b7db896046fa7d774bbc4bf7f8dc2",
+			"02103a7f7dd016558597f7960d27c516a4394fd968b9e65155eb4b013e4040406e",
+			"03d90c07df63e690ce77912e10ab51acc944b66860237b608c4f8f8309e71ee699",
+			"02a7bc55fe8684e0119768d104ba30795bdcc86619e864add26156723ed185cd62",
+		},
+		CommitteeHistory:  map[uint32]int{0: 1, 100: 4},
+		ValidatorsHistory: map[uint32]int{0: 1, 100: 4},
+	}
+	require.NoError(t, p.Validate())
+}
+
+func TestGetCommitteeAndCNs(t *testing.T) {
+	p := &ProtocolConfiguration{
+		StandbyCommittee: []string{
+			"02b3622bf4017bdfe317c58aed5f4c753f206b7db896046fa7d774bbc4bf7f8dc2",
+			"02103a7f7dd016558597f7960d27c516a4394fd968b9e65155eb4b013e4040406e",
+			"03d90c07df63e690ce77912e10ab51acc944b66860237b608c4f8f8309e71ee699",
+			"02a7bc55fe8684e0119768d104ba30795bdcc86619e864add26156723ed185cd62",
+		},
+		CommitteeHistory:  map[uint32]int{0: 1, 100: 4},
+		ValidatorsHistory: map[uint32]int{0: 1, 200: 4},
+	}
+	require.Equal(t, 1, p.GetCommitteeSize(0))
+	require.Equal(t, 1, p.GetCommitteeSize(99))
+	require.Equal(t, 4, p.GetCommitteeSize(100))
+	require.Equal(t, 4, p.GetCommitteeSize(101))
+	require.Equal(t, 4, p.GetCommitteeSize(200))
+	require.Equal(t, 4, p.GetCommitteeSize(201))
+	require.Equal(t, 1, p.GetNumOfCNs(0))
+	require.Equal(t, 1, p.GetNumOfCNs(100))
+	require.Equal(t, 1, p.GetNumOfCNs(101))
+	require.Equal(t, 1, p.GetNumOfCNs(199))
+	require.Equal(t, 4, p.GetNumOfCNs(200))
+	require.Equal(t, 4, p.GetNumOfCNs(201))
+}

pkg/consensus/consensus.go

@@ -16,7 +16,6 @@ import (
 	"github.com/nspcc-dev/neo-go/pkg/core/blockchainer"
 	"github.com/nspcc-dev/neo-go/pkg/core/interop"
 	"github.com/nspcc-dev/neo-go/pkg/core/mempool"
-	"github.com/nspcc-dev/neo-go/pkg/core/native"
 	"github.com/nspcc-dev/neo-go/pkg/core/transaction"
 	"github.com/nspcc-dev/neo-go/pkg/crypto/hash"
 	"github.com/nspcc-dev/neo-go/pkg/crypto/keys"
@@ -48,6 +47,7 @@ const Category = "dBFT"
 type Ledger interface {
 	AddBlock(block *coreb.Block) error
 	ApplyPolicyToTxSet([]*transaction.Transaction) []*transaction.Transaction
+	GetConfig() config.ProtocolConfiguration
 	GetMemPool() *mempool.Pool
 	GetNextBlockValidators() ([]*keys.PublicKey, error)
 	GetStateModule() blockchainer.StateRoot
@@ -676,7 +676,8 @@ func (s *service) newBlockFromContext(ctx *dbft.Context) block.Block {
 
 	var validators keys.PublicKeys
 	var err error
-	if native.ShouldUpdateCommittee(ctx.BlockIndex, s.Chain) {
+	cfg := s.Chain.GetConfig()
+	if cfg.ShouldUpdateCommitteeAt(ctx.BlockIndex) {
 		validators, err = s.Chain.GetValidators()
 	} else {
 		validators, err = s.Chain.GetNextBlockValidators()
@@ -684,7 +685,7 @@ func (s *service) newBlockFromContext(ctx *dbft.Context) block.Block {
 	if err != nil {
 		s.log.Fatal(fmt.Sprintf("failed to get validators: %s", err.Error()))
 	}
-	script, err := smartcontract.CreateMultiSigRedeemScript(s.dbft.Context.M(), validators)
+	script, err := smartcontract.CreateDefaultMultiSigRedeemScript(validators)
 	if err != nil {
 		s.log.Fatal(fmt.Sprintf("failed to create multisignature script: %s", err.Error()))
 	}

pkg/consensus/consensus_test.go

@@ -88,7 +88,8 @@ func initServiceNextConsensus(t *testing.T, newAcc *wallet.Account, offset uint3
 	require.NoError(t, bc.PoolTx(tx))
 	srv.dbft.OnTimeout(timer.HV{Height: srv.dbft.Context.BlockIndex})
 
-	for i := srv.dbft.BlockIndex; !native.ShouldUpdateCommittee(i+offset, bc); i++ {
+	cfg := bc.GetConfig()
+	for i := srv.dbft.BlockIndex; !cfg.ShouldUpdateCommitteeAt(i + offset); i++ {
 		srv.dbft.OnTimeout(timer.HV{Height: srv.dbft.Context.BlockIndex})
 	}
 

pkg/core/blockchain.go

@@ -152,8 +152,6 @@ type Blockchain struct {
 	// Block's transactions are passed via mempool.
 	postBlock []func(func(*transaction.Transaction, *mempool.Pool, bool) bool, *mempool.Pool, *block.Block)
 
-	sbCommittee keys.PublicKeys
-
 	log *zap.Logger
 
 	lastBatch *storage.MemBatch
@@ -162,8 +160,11 @@ type Blockchain struct {
 
 	extensible atomic.Value
 
+	// knownValidatorsCount is the latest known validators count used
+	// for defaultBlockWitness.
+	knownValidatorsCount atomic.Value
 	// defaultBlockWitness stores transaction.Witness with m out of n multisig,
-	// where n = ValidatorsCount.
+	// where n = knownValidatorsCount.
 	defaultBlockWitness atomic.Value
 
 	stateRoot *stateroot.Module
@@ -244,10 +245,6 @@ func NewBlockchain(s storage.Store, cfg config.ProtocolConfiguration, log *zap.L
 				zap.Int("StateSyncInterval", cfg.StateSyncInterval))
 		}
 	}
-	committee, err := committeeFromConfig(cfg)
-	if err != nil {
-		return nil, err
-	}
 	if len(cfg.NativeUpdateHistories) == 0 {
 		cfg.NativeUpdateHistories = map[string][]uint32{}
 		log.Info("NativeActivations are not set, using default values")
@@ -259,7 +256,6 @@ func NewBlockchain(s storage.Store, cfg config.ProtocolConfiguration, log *zap.L
 		stopCh:      make(chan struct{}),
 		runToExitCh: make(chan struct{}),
 		memPool:     mempool.New(cfg.MemPoolSize, 0, false),
-		sbCommittee: committee,
 		log:         log,
 		events:      make(chan bcEvent),
 		subCh:       make(chan interface{}),
@@ -1177,7 +1173,7 @@ func (bc *Blockchain) storeBlock(block *block.Block, txpool *mempool.Pool) error
 }
 
 func (bc *Blockchain) updateExtensibleWhitelist(height uint32) error {
-	updateCommittee := native.ShouldUpdateCommittee(height, bc)
+	updateCommittee := bc.config.ShouldUpdateCommitteeAt(height)
 	stateVals, sh, err := bc.contracts.Designate.GetDesignatedByRole(bc.dao, noderoles.StateValidator, height)
 	if err != nil {
 		return err
@@ -1787,14 +1783,17 @@ func (bc *Blockchain) ApplyPolicyToTxSet(txes []*transaction.Transaction) []*tra
 	}
 	maxBlockSize := bc.config.MaxBlockSize
 	maxBlockSysFee := bc.config.MaxBlockSystemFee
+	oldVC := bc.knownValidatorsCount.Load()
 	defaultWitness := bc.defaultBlockWitness.Load()
-	if defaultWitness == nil {
-		m := smartcontract.GetDefaultHonestNodeCount(bc.config.ValidatorsCount)
+	curVC := bc.config.GetNumOfCNs(bc.BlockHeight() + 1)
+	if oldVC == nil || oldVC != curVC {
+		m := smartcontract.GetDefaultHonestNodeCount(curVC)
 		verification, _ := smartcontract.CreateDefaultMultiSigRedeemScript(bc.contracts.NEO.GetNextBlockValidatorsInternal())
 		defaultWitness = transaction.Witness{
 			InvocationScript:   make([]byte, 66*m),
 			VerificationScript: verification,
 		}
+		bc.knownValidatorsCount.Store(curVC)
 		bc.defaultBlockWitness.Store(defaultWitness)
 	}
 	var (
@@ -2083,16 +2082,6 @@ func (bc *Blockchain) PoolTxWithData(t *transaction.Transaction, data interface{
 	return bc.verifyAndPoolTx(t, mp, feer, data)
 }
 
-// GetStandByValidators returns validators from the configuration.
-func (bc *Blockchain) GetStandByValidators() keys.PublicKeys {
-	return bc.sbCommittee[:bc.config.ValidatorsCount].Copy()
-}
-
-// GetStandByCommittee returns standby committee from the configuration.
-func (bc *Blockchain) GetStandByCommittee() keys.PublicKeys {
-	return bc.sbCommittee.Copy()
-}
-
 // GetCommittee returns the sorted list of public keys of nodes in committee.
 func (bc *Blockchain) GetCommittee() (keys.PublicKeys, error) {
 	pubs := bc.contracts.NEO.GetCommitteeMembers()

pkg/core/blockchain_test.go

@@ -1828,6 +1828,81 @@ func TestBlockchain_InitWithIncompleteStateJump(t *testing.T) {
 	}
 }
 
+func TestChainWithVolatileNumOfValidators(t *testing.T) {
+	bc := newTestChainWithCustomCfg(t, func(c *config.Config) {
+		c.ProtocolConfiguration.ValidatorsCount = 0
+		c.ProtocolConfiguration.CommitteeHistory = map[uint32]int{
+			0:  1,
+			4:  4,
+			24: 6,
+		}
+		c.ProtocolConfiguration.ValidatorsHistory = map[uint32]int{
+			0: 1,
+			4: 4,
+		}
+		require.NoError(t, c.ProtocolConfiguration.Validate())
+	})
+	require.Equal(t, uint32(0), bc.BlockHeight())
+
+	priv0 := testchain.PrivateKeyByID(0)
+
+	vals, err := bc.GetValidators()
+	require.NoError(t, err)
+	script, err := smartcontract.CreateDefaultMultiSigRedeemScript(vals)
+	require.NoError(t, err)
+	curWit := transaction.Witness{
+		VerificationScript: script,
+	}
+	for i := 1; i < 26; i++ {
+		comm, err := bc.GetCommittee()
+		require.NoError(t, err)
+		if i < 5 {
+			require.Equal(t, 1, len(comm))
+		} else if i < 25 {
+			require.Equal(t, 4, len(comm))
+		} else {
+			require.Equal(t, 6, len(comm))
+		}
+		// Mimic consensus.
+		if bc.config.ShouldUpdateCommitteeAt(uint32(i)) {
+			vals, err = bc.GetValidators()
+		} else {
+			vals, err = bc.GetNextBlockValidators()
+		}
+		require.NoError(t, err)
+		if i < 4 {
+			require.Equalf(t, 1, len(vals), "at %d", i)
+		} else {
+			require.Equalf(t, 4, len(vals), "at %d", i)
+		}
+		require.NoError(t, err)
+		script, err := smartcontract.CreateDefaultMultiSigRedeemScript(vals)
+		require.NoError(t, err)
+		nextWit := transaction.Witness{
+			VerificationScript: script,
+		}
+		b := &block.Block{
+			Header: block.Header{
+				NextConsensus: nextWit.ScriptHash(),
+				Script:        curWit,
+			},
+		}
+		curWit = nextWit
+		b.PrevHash = bc.GetHeaderHash(i - 1)
+		b.Timestamp = uint64(time.Now().UTC().Unix())*1000 + uint64(i)
+		b.Index = uint32(i)
+		b.RebuildMerkleRoot()
+		if i < 5 {
+			signa := priv0.SignHashable(uint32(bc.config.Magic), b)
+			b.Script.InvocationScript = append([]byte{byte(opcode.PUSHDATA1), byte(len(signa))}, signa...)
+		} else {
+			b.Script.InvocationScript = testchain.Sign(b)
+		}
+		err = bc.AddBlock(b)
+		require.NoErrorf(t, err, "at %d", i)
+	}
+}
+
 func setSigner(tx *transaction.Transaction, h util.Uint160) {
 	tx.Signers = []transaction.Signer{{
 		Account: h,

pkg/core/blockchainer/blockchainer.go

@@ -56,8 +56,6 @@ type Blockchainer interface {
 	GetNotaryContractScriptHash() util.Uint160
 	GetNotaryBalance(acc util.Uint160) *big.Int
 	GetValidators() ([]*keys.PublicKey, error)
-	GetStandByCommittee() keys.PublicKeys
-	GetStandByValidators() keys.PublicKeys
 	GetStateModule() StateRoot
 	GetStorageItem(id int32, key []byte) state.StorageItem
 	GetStorageItems(id int32) ([]state.StorageItemWithKey, error)

pkg/core/interop/context.go

@@ -15,7 +15,6 @@ import (
 	"github.com/nspcc-dev/neo-go/pkg/core/state"
 	"github.com/nspcc-dev/neo-go/pkg/core/transaction"
 	"github.com/nspcc-dev/neo-go/pkg/crypto/hash"
-	"github.com/nspcc-dev/neo-go/pkg/crypto/keys"
 	"github.com/nspcc-dev/neo-go/pkg/io"
 	"github.com/nspcc-dev/neo-go/pkg/smartcontract/callflag"
 	"github.com/nspcc-dev/neo-go/pkg/smartcontract/manifest"
@@ -42,8 +41,6 @@ type Ledger interface {
 	GetBlock(hash util.Uint256) (*block.Block, error)
 	GetConfig() config.ProtocolConfiguration
 	GetHeaderHash(int) util.Uint256
-	GetStandByCommittee() keys.PublicKeys
-	GetStandByValidators() keys.PublicKeys
 	GetStoragePrice() int64
 }
 

pkg/core/native/native_gas.go

@@ -10,6 +10,7 @@ import (
 	"github.com/nspcc-dev/neo-go/pkg/core/state"
 	"github.com/nspcc-dev/neo-go/pkg/core/transaction"
 	"github.com/nspcc-dev/neo-go/pkg/crypto/hash"
+	"github.com/nspcc-dev/neo-go/pkg/crypto/keys"
 	"github.com/nspcc-dev/neo-go/pkg/smartcontract"
 	"github.com/nspcc-dev/neo-go/pkg/util"
 )
@@ -135,7 +136,12 @@ func (g *GAS) BalanceOf(d dao.DAO, acc util.Uint160) *big.Int {
 }
 
 func getStandbyValidatorsHash(ic *interop.Context) (util.Uint160, error) {
-	s, err := smartcontract.CreateDefaultMultiSigRedeemScript(ic.Chain.GetStandByValidators())
+	cfg := ic.Chain.GetConfig()
+	committee, err := keys.NewPublicKeysFromStrings(cfg.StandbyCommittee)
+	if err != nil {
+		return util.Uint160{}, err
+	}
+	s, err := smartcontract.CreateDefaultMultiSigRedeemScript(committee[:cfg.GetNumOfCNs(0)])
 	if err != nil {
 		return util.Uint160{}, err
 	}

pkg/core/native/native_neo.go

@@ -10,6 +10,7 @@ import (
 	"strings"
 	"sync/atomic"
 
+	"github.com/nspcc-dev/neo-go/pkg/config"
 	"github.com/nspcc-dev/neo-go/pkg/core/dao"
 	"github.com/nspcc-dev/neo-go/pkg/core/interop"
 	"github.com/nspcc-dev/neo-go/pkg/core/interop/runtime"
@@ -54,6 +55,10 @@ type NEO struct {
 	// It is set in state-modifying methods only and read in `PostPersist` thus is not protected
 	// by any mutex.
 	gasPerVoteCache map[string]big.Int
+	// Configuration and standby keys are set during initialization and then
+	// only read from.
+	cfg         config.ProtocolConfiguration
+	standbyKeys keys.PublicKeys
 }
 
 const (
@@ -190,6 +195,10 @@ func newNEO() *NEO {
 
 // Initialize initializes NEO contract.
 func (n *NEO) Initialize(ic *interop.Context) error {
+	err := n.initConfigCache(ic.Chain)
+	if err != nil {
+		return nil
+	}
 	if err := n.nep17TokenNative.Initialize(ic); err != nil {
 		return err
 	}
@@ -199,9 +208,9 @@ func (n *NEO) Initialize(ic *interop.Context) error {
 		return errors.New("already initialized")
 	}
 
-	committee := ic.Chain.GetStandByCommittee()
-	cvs := toKeysWithVotes(committee)
-	err := n.updateCache(cvs, ic.Chain)
+	committee0 := n.standbyKeys[:n.cfg.GetCommitteeSize(ic.Block.Index)]
+	cvs := toKeysWithVotes(committee0)
+	err = n.updateCache(cvs, ic.Chain)
 	if err != nil {
 		return err
 	}
@@ -244,6 +253,10 @@ func (n *NEO) Initialize(ic *interop.Context) error {
 // Cache initialisation should be done apart from Initialize because Initialize is
 // called only when deploying native contracts.
 func (n *NEO) InitializeCache(bc interop.Ledger, d dao.DAO) error {
+	err := n.initConfigCache(bc)
+	if err != nil {
+		return nil
+	}
 	var committee = keysWithVotes{}
 	si := d.GetStorageItem(n.ID, prefixCommittee)
 	if err := committee.DecodeBytes(si); err != nil {
@@ -263,6 +276,14 @@ func (n *NEO) InitializeCache(bc interop.Ledger, d dao.DAO) error {
 	return nil
 }
 
+func (n *NEO) initConfigCache(bc interop.Ledger) error {
+	var err error
+
+	n.cfg = bc.GetConfig()
+	n.standbyKeys, err = keys.NewPublicKeysFromStrings(n.cfg.StandbyCommittee)
+	return err
+}
+
 func (n *NEO) updateCache(cvs keysWithVotes, bc interop.Ledger) error {
 	n.committee.Store(cvs)
 
@@ -273,7 +294,7 @@ func (n *NEO) updateCache(cvs keysWithVotes, bc interop.Ledger) error {
 	}
 	n.committeeHash.Store(hash.Hash160(script))
 
-	nextVals := committee[:bc.GetConfig().ValidatorsCount].Copy()
+	nextVals := committee[:n.cfg.GetNumOfCNs(bc.BlockHeight()+1)].Copy()
 	sort.Sort(nextVals)
 	n.nextValidators.Store(nextVals)
 	return nil
@@ -298,16 +319,15 @@ func (n *NEO) updateCommittee(ic *interop.Context) error {
 	return ic.DAO.PutStorageItem(n.ID, prefixCommittee, cvs.Bytes())
 }
 
-// ShouldUpdateCommittee returns true if committee is updated at block h.
-func ShouldUpdateCommittee(h uint32, bc interop.Ledger) bool {
-	cfg := bc.GetConfig()
-	r := len(cfg.StandbyCommittee)
-	return h%uint32(r) == 0
-}
-
 // OnPersist implements Contract interface.
 func (n *NEO) OnPersist(ic *interop.Context) error {
-	if ShouldUpdateCommittee(ic.Block.Index, ic.Chain) {
+	if n.cfg.ShouldUpdateCommitteeAt(ic.Block.Index) {
+		oldKeys := n.nextValidators.Load().(keys.PublicKeys)
+		oldCom := n.committee.Load().(keysWithVotes)
+		if n.cfg.GetNumOfCNs(ic.Block.Index) != len(oldKeys) ||
+			n.cfg.GetCommitteeSize(ic.Block.Index) != len(oldCom) {
+			n.votesChanged.Store(true)
+		}
 		if err := n.updateCommittee(ic); err != nil {
 			return err
 		}
@@ -319,16 +339,16 @@ func (n *NEO) OnPersist(ic *interop.Context) error {
 func (n *NEO) PostPersist(ic *interop.Context) error {
 	gas := n.GetGASPerBlock(ic.DAO, ic.Block.Index)
 	pubs := n.GetCommitteeMembers()
-	committeeSize := len(ic.Chain.GetConfig().StandbyCommittee)
+	committeeSize := n.cfg.GetCommitteeSize(ic.Block.Index)
 	index := int(ic.Block.Index) % committeeSize
 	committeeReward := new(big.Int).Mul(gas, bigCommitteeRewardRatio)
 	n.GAS.mint(ic, pubs[index].GetScriptHash(), committeeReward.Div(committeeReward, big100), false)
 
-	if ShouldUpdateCommittee(ic.Block.Index, ic.Chain) {
+	if n.cfg.ShouldUpdateCommitteeAt(ic.Block.Index) {
 		var voterReward = new(big.Int).Set(bigVoterRewardRatio)
 		voterReward.Mul(voterReward, gas)
 		voterReward.Mul(voterReward, big.NewInt(voterRewardFactor*int64(committeeSize)))
-		var validatorsCount = ic.Chain.GetConfig().ValidatorsCount
+		var validatorsCount = n.cfg.GetNumOfCNs(ic.Block.Index)
 		voterReward.Div(voterReward, big.NewInt(int64(committeeSize+validatorsCount)))
 		voterReward.Div(voterReward, big100)
 
@@ -938,14 +958,15 @@ func (n *NEO) getAccountState(ic *interop.Context, args []stackitem.Item) stacki
 
 // ComputeNextBlockValidators returns an actual list of current validators.
 func (n *NEO) ComputeNextBlockValidators(bc interop.Ledger, d dao.DAO) (keys.PublicKeys, error) {
-	if vals := n.validators.Load().(keys.PublicKeys); vals != nil {
+	numOfCNs := n.cfg.GetNumOfCNs(bc.BlockHeight() + 1)
+	if vals := n.validators.Load().(keys.PublicKeys); vals != nil && numOfCNs == len(vals) {
 		return vals.Copy(), nil
 	}
 	result, _, err := n.computeCommitteeMembers(bc, d)
 	if err != nil {
 		return nil, err
 	}
-	result = result[:bc.GetConfig().ValidatorsCount]
+	result = result[:numOfCNs]
 	sort.Sort(result)
 	n.validators.Store(result)
 	return result, nil
@@ -1006,8 +1027,9 @@ func (n *NEO) computeCommitteeMembers(bc interop.Ledger, d dao.DAO) (keys.Public
 	_, totalSupply := n.getTotalSupply(d)
 	voterTurnout := votersCount.Div(votersCount, totalSupply)
 
-	sbVals := bc.GetStandByCommittee()
-	count := len(sbVals)
+	count := n.cfg.GetCommitteeSize(bc.BlockHeight() + 1)
+	// Can be sorted and/or returned to outside users, thus needs to be copied.
+	sbVals := keys.PublicKeys(n.standbyKeys[:count]).Copy()
 	cs, err := n.getCandidates(d, false)
 	if err != nil {
 		return nil, nil, err

pkg/core/native/native_test/neo_test.go

@@ -50,8 +50,9 @@ func TestNEO_Vote(t *testing.T) {
 	neoValidatorsInvoker := neoCommitteeInvoker.WithSigners(neoCommitteeInvoker.Validator)
 	e := neoCommitteeInvoker.Executor
 
-	committeeSize := len(neoValidatorsInvoker.Chain.GetConfig().StandbyCommittee)
-	validatorsCount := neoCommitteeInvoker.Chain.GetConfig().ValidatorsCount
+	cfg := e.Chain.GetConfig()
+	committeeSize := cfg.GetCommitteeSize(0)
+	validatorsCount := cfg.GetNumOfCNs(0)
 	freq := validatorsCount + committeeSize
 	advanceChain := func(t *testing.T) {
 		for i := 0; i < freq; i++ {
@@ -59,7 +60,9 @@ func TestNEO_Vote(t *testing.T) {
 		}
 	}
 
-	standBySorted := e.Chain.GetStandByValidators()
+	standBySorted, err := keys.NewPublicKeysFromStrings(e.Chain.GetConfig().StandbyCommittee)
+	require.NoError(t, err)
+	standBySorted = standBySorted[:validatorsCount]
 	sort.Sort(standBySorted)
 	pubs, err := e.Chain.GetValidators()
 	require.NoError(t, err)
@@ -250,7 +253,8 @@ func TestNEO_CommitteeBountyOnPersist(t *testing.T) {
 	neoCommitteeInvoker := newNeoCommitteeClient(t, 0)
 	e := neoCommitteeInvoker.Executor
 
-	hs := e.Chain.GetStandByCommittee()
+	hs, err := keys.NewPublicKeysFromStrings(e.Chain.GetConfig().StandbyCommittee)
+	require.NoError(t, err)
 	committeeSize := len(hs)
 
 	const singleBounty = 50000000

pkg/core/native/notary.go

@@ -392,9 +392,10 @@ func (n *Notary) GetMaxNotValidBeforeDelta(dao dao.DAO) uint32 {
 // setMaxNotValidBeforeDelta is Notary contract method and sets the maximum NotValidBefore delta.
 func (n *Notary) setMaxNotValidBeforeDelta(ic *interop.Context, args []stackitem.Item) stackitem.Item {
 	value := toUint32(args[0])
-	maxInc := ic.Chain.GetConfig().MaxValidUntilBlockIncrement
-	if value > maxInc/2 || value < uint32(ic.Chain.GetConfig().ValidatorsCount) {
-		panic(fmt.Errorf("MaxNotValidBeforeDelta cannot be more than %d or less than %d", maxInc/2, ic.Chain.GetConfig().ValidatorsCount))
+	cfg := ic.Chain.GetConfig()
+	maxInc := cfg.MaxValidUntilBlockIncrement
+	if value > maxInc/2 || value < uint32(cfg.GetNumOfCNs(ic.Chain.BlockHeight())) {
+		panic(fmt.Errorf("MaxNotValidBeforeDelta cannot be more than %d or less than %d", maxInc/2, cfg.GetNumOfCNs(ic.Chain.BlockHeight())))
 	}
 	if !n.NEO.checkCommittee(ic) {
 		panic("invalid committee signature")

pkg/core/util.go

@@ -1,7 +1,6 @@
 package core
 
 import (
-	"errors"
 	"time"
 
 	"github.com/nspcc-dev/neo-go/pkg/config"
@@ -50,26 +49,11 @@ func createGenesisBlock(cfg config.ProtocolConfiguration) (*block.Block, error)
 }
 
 func validatorsFromConfig(cfg config.ProtocolConfiguration) ([]*keys.PublicKey, error) {
-	vs, err := committeeFromConfig(cfg)
+	vs, err := keys.NewPublicKeysFromStrings(cfg.StandbyCommittee)
 	if err != nil {
 		return nil, err
 	}
-	return vs[:cfg.ValidatorsCount], nil
-}
-
-func committeeFromConfig(cfg config.ProtocolConfiguration) ([]*keys.PublicKey, error) {
-	if len(cfg.StandbyCommittee) < cfg.ValidatorsCount {
-		return nil, errors.New("validators count can be less than the size of StandbyCommittee")
-	}
-	validators := make([]*keys.PublicKey, len(cfg.StandbyCommittee))
-	for i := range validators {
-		pubKey, err := keys.NewPublicKeyFromString(cfg.StandbyCommittee[i])
-		if err != nil {
-			return nil, err
-		}
-		validators[i] = pubKey
-	}
-	return validators, nil
+	return vs[:cfg.GetNumOfCNs(0)], nil
 }
 
 func getNextConsensusAddress(validators []*keys.PublicKey) (val util.Uint160, err error) {

pkg/crypto/keys/publickey.go

@@ -32,6 +32,20 @@ type PublicKeys []*PublicKey
 var big0 = big.NewInt(0)
 var big3 = big.NewInt(3)
 
+// NewPublicKeysFromStrings converts an array of string-encoded P256 public keys
+// into an array of PublicKeys.
+func NewPublicKeysFromStrings(ss []string) (PublicKeys, error) {
+	arr := make([]*PublicKey, len(ss))
+	for i := range ss {
+		pubKey, err := NewPublicKeyFromString(ss[i])
+		if err != nil {
+			return nil, err
+		}
+		arr[i] = pubKey
+	}
+	return PublicKeys(arr), nil
+}
+
 func (keys PublicKeys) Len() int      { return len(keys) }
 func (keys PublicKeys) Swap(i, j int) { keys[i], keys[j] = keys[j], keys[i] }
 func (keys PublicKeys) Less(i, j int) bool {

pkg/network/server.go

@@ -14,7 +14,6 @@ import (
 	"time"
 
 	"github.com/nspcc-dev/neo-go/pkg/config"
-	"github.com/nspcc-dev/neo-go/pkg/config/netmode"
 	"github.com/nspcc-dev/neo-go/pkg/core/block"
 	"github.com/nspcc-dev/neo-go/pkg/core/mempool"
 	"github.com/nspcc-dev/neo-go/pkg/core/mempoolevent"
@@ -89,10 +88,8 @@ type (
 		// id also known as the nonce of the server.
 		id uint32
 
-		// Network's magic number for correct message decoding.
-		network netmode.Magic
-		// stateRootInHeader specifies if block header contain state root.
-		stateRootInHeader bool
+		// A copy of the Ledger's config.
+		config config.ProtocolConfiguration
 
 		transport         Transporter
 		discovery         Discoverer
@@ -166,27 +163,26 @@ func newServerFromConstructors(config ServerConfig, chain Ledger, stSync StateSy
 	}
 
 	s := &Server{
-		ServerConfig:      config,
-		chain:             chain,
-		id:                randomID(),
-		network:           chain.GetConfig().Magic,
-		stateRootInHeader: chain.GetConfig().StateRootInHeader,
-		quit:              make(chan struct{}),
-		register:          make(chan Peer),
-		unregister:        make(chan peerDrop),
-		txInMap:           make(map[util.Uint256]struct{}),
-		peers:             make(map[Peer]bool),
-		syncReached:       atomic.NewBool(false),
-		mempool:           chain.GetMemPool(),
-		extensiblePool:    extpool.New(chain, config.ExtensiblePoolSize),
-		log:               log,
-		transactions:      make(chan *transaction.Transaction, 64),
-		extensHandlers:    make(map[string]func(*payload.Extensible) error),
-		stateSync:         stSync,
+		ServerConfig:   config,
+		chain:          chain,
+		id:             randomID(),
+		config:         chain.GetConfig(),
+		quit:           make(chan struct{}),
+		register:       make(chan Peer),
+		unregister:     make(chan peerDrop),
+		txInMap:        make(map[util.Uint256]struct{}),
+		peers:          make(map[Peer]bool),
+		syncReached:    atomic.NewBool(false),
+		mempool:        chain.GetMemPool(),
+		extensiblePool: extpool.New(chain, config.ExtensiblePoolSize),
+		log:            log,
+		transactions:   make(chan *transaction.Transaction, 64),
+		extensHandlers: make(map[string]func(*payload.Extensible) error),
+		stateSync:      stSync,
 	}
 	if chain.P2PSigExtensionsEnabled() {
 		s.notaryFeer = NewNotaryFeer(chain)
-		s.notaryRequestPool = mempool.New(chain.GetConfig().P2PNotaryRequestPayloadPoolSize, 1, true)
+		s.notaryRequestPool = mempool.New(s.config.P2PNotaryRequestPayloadPoolSize, 1, true)
 		chain.RegisterPostBlock(func(isRelevant func(*transaction.Transaction, *mempool.Pool, bool) bool, txpool *mempool.Pool, _ *block.Block) {
 			s.notaryRequestPool.RemoveStale(func(t *transaction.Transaction) bool {
 				return isRelevant(t, txpool, true)
@@ -773,10 +769,10 @@ func (s *Server) handleGetDataCmd(p Peer, inv *payload.Inventory) error {
 
 // handleGetMPTDataCmd processes the received MPT inventory.
 func (s *Server) handleGetMPTDataCmd(p Peer, inv *payload.MPTInventory) error {
-	if !s.chain.GetConfig().P2PStateExchangeExtensions {
+	if !s.config.P2PStateExchangeExtensions {
 		return errors.New("GetMPTDataCMD was received, but P2PStateExchangeExtensions are disabled")
 	}
-	if s.chain.GetConfig().KeepOnlyLatestState {
+	if s.config.KeepOnlyLatestState {
 		// TODO: implement keeping MPT states for P1 and P2 height (#2095, #2152 related)
 		return errors.New("GetMPTDataCMD was received, but only latest MPT state is supported")
 	}
@@ -814,7 +810,7 @@ func (s *Server) handleGetMPTDataCmd(p Peer, inv *payload.MPTInventory) error {
 }
 
 func (s *Server) handleMPTDataCmd(p Peer, data *payload.MPTData) error {
-	if !s.chain.GetConfig().P2PStateExchangeExtensions {
+	if !s.config.P2PStateExchangeExtensions {
 		return errors.New("MPTDataCMD was received, but P2PStateExchangeExtensions are disabled")
 	}
 	return s.stateSync.AddMPTNodes(data.Nodes)
@@ -1396,10 +1392,11 @@ func (s *Server) broadcastTxHashes(hs []util.Uint256) {
 
 // initStaleMemPools initializes mempools for stale tx/payload processing.
 func (s *Server) initStaleMemPools() {
-	cfg := s.chain.GetConfig()
 	threshold := 5
-	if cfg.ValidatorsCount*2 > threshold {
-		threshold = cfg.ValidatorsCount * 2
+	// Not perfect, can change over time, but should be sufficient.
+	numOfCNs := s.config.GetNumOfCNs(s.chain.BlockHeight())
+	if numOfCNs*2 > threshold {
+		threshold = numOfCNs * 2
 	}
 
 	s.mempool.SetResendThreshold(uint32(threshold), s.broadcastTX)

pkg/network/server_test.go

@@ -813,7 +813,7 @@ func TestHandleMPTData(t *testing.T) {
 	t.Run("good", func(t *testing.T) {
 		expected := [][]byte{{1, 2, 3}, {2, 3, 4}}
 		s := newTestServer(t, ServerConfig{Port: 0, UserAgent: "/test/"})
-		s.chain.(*fakechain.FakeChain).P2PStateExchangeExtensions = true
+		s.config.P2PStateExchangeExtensions = true
 		s.stateSync = &fakechain.FakeStateSync{
 			AddMPTNodesFunc: func(nodes [][]byte) error {
 				require.Equal(t, expected, nodes)

pkg/network/tcp_peer.go

@@ -167,7 +167,7 @@ func (p *TCPPeer) handleConn() {
 	if err == nil {
 		r := io.NewBinReaderFromIO(p.conn)
 		for {
-			msg := &Message{StateRootInHeader: p.server.stateRootInHeader}
+			msg := &Message{StateRootInHeader: p.server.config.StateRootInHeader}
 			err = msg.Decode(r)
 
 			if err == payload.ErrTooManyHeaders {
@@ -207,7 +207,7 @@ func (p *TCPPeer) handleQueues() {
 	var p2pSkipCounter uint32
 	const p2pSkipDivisor = 4
 
-	var writeTimeout = time.Duration(p.server.chain.GetConfig().SecondsPerBlock) * time.Second
+	var writeTimeout = time.Duration(p.server.config.SecondsPerBlock) * time.Second
 	for {
 		var msg []byte
 

pkg/rpc/server/server.go

@@ -533,7 +533,7 @@ func (s *Server) getVersion(_ request.Params) (interface{}, *response.Error) {
 			MaxValidUntilBlockIncrement: cfg.MaxValidUntilBlockIncrement,
 			MaxTransactionsPerBlock:     cfg.MaxTransactionsPerBlock,
 			MemoryPoolMaxTransactions:   cfg.MemPoolSize,
-			ValidatorsCount:             byte(cfg.ValidatorsCount),
+			ValidatorsCount:             byte(cfg.GetNumOfCNs(s.chain.BlockHeight())),
 			InitialGasDistribution:      cfg.InitialGASSupply,
 			StateRootInHeader:           cfg.StateRootInHeader,
 		},

pkg/rpc/server/server_test.go

@@ -699,8 +699,7 @@ var rpcTestCases = map[string][]rpcTestCase{
 		{
 			params: "[]",
 			result: func(e *executor) interface{} {
-				// it's a test chain, so committee is a sorted standby committee
-				expected := e.chain.GetStandByCommittee()
+				expected, _ := e.chain.GetCommittee()
 				sort.Sort(expected)
 				return &expected
 			},

scripts/gendump/main.go

@@ -64,7 +64,9 @@ func main() {
 	bc, err := newChain()
 	handleError("can't initialize blockchain", err)
 
-	valScript, err := smartcontract.CreateDefaultMultiSigRedeemScript(bc.GetStandByValidators())
+	nbVals, err := bc.GetNextBlockValidators()
+	handleError("can't get next block validators", err)
+	valScript, err := smartcontract.CreateDefaultMultiSigRedeemScript(nbVals)
 	handleError("can't create verification script", err)
 	lastBlock, err := bc.GetBlock(bc.GetHeaderHash(int(bc.BlockHeight())))
 	handleError("can't fetch last block", err)