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fixedoracle.go
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fixedoracle.go
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// Package eligibility defines fixed size oracle used for node testing
package eligibility
import (
"encoding/binary"
"hash/fnv"
"sync"
"github.com/spacemeshos/go-spacemesh/common/types"
"github.com/spacemeshos/go-spacemesh/log"
)
// FixedRolacle is an eligibility simulator with pre-determined honest and faulty participants.
type FixedRolacle struct {
honest map[string]struct{}
faulty map[string]struct{}
emaps map[uint32]map[string]struct{}
mutex sync.Mutex
mapRW sync.RWMutex
}
// New initializes the oracle with no participants.
func New() *FixedRolacle {
rolacle := &FixedRolacle{}
rolacle.honest = make(map[string]struct{})
rolacle.faulty = make(map[string]struct{})
rolacle.emaps = make(map[uint32]map[string]struct{})
return rolacle
}
// IsIdentityActiveOnConsensusView is use to satisfy the API, currently always returns true.
func (fo *FixedRolacle) IsIdentityActiveOnConsensusView(edID string, layer types.LayerID) (bool, error) {
return true, nil
}
// Export creates a map with the eligible participants for id and committee size.
func (fo *FixedRolacle) Export(id uint32, committeeSize int) map[string]struct{} {
fo.mapRW.RLock()
total := len(fo.honest) + len(fo.faulty)
fo.mapRW.RUnlock()
// normalize committee size
size := committeeSize
if committeeSize > total {
log.Warning("committee size bigger than the number of clients. Expected %v<=%v", committeeSize, total)
size = total
}
fo.mapRW.Lock()
// generate if not exist for the requested K
if _, exist := fo.emaps[id]; !exist {
fo.emaps[id] = fo.generateEligibility(size)
}
m := fo.emaps[id]
fo.mapRW.Unlock()
return m
}
func (fo *FixedRolacle) update(m map[string]struct{}, client string) {
fo.mutex.Lock()
if _, exist := m[client]; exist {
fo.mutex.Unlock()
return
}
m[client] = struct{}{}
fo.mutex.Unlock()
}
// Register adds a participant to the eligibility map. can be honest or faulty.
func (fo *FixedRolacle) Register(isHonest bool, client string) {
if isHonest {
fo.update(fo.honest, client)
} else {
fo.update(fo.faulty, client)
}
}
// Unregister removes a participant from the eligibility map. can be honest or faulty.
// TODO: just remove from both instead of specifying.
func (fo *FixedRolacle) Unregister(isHonest bool, client string) {
fo.mutex.Lock()
if isHonest {
delete(fo.honest, client)
} else {
delete(fo.faulty, client)
}
fo.mutex.Unlock()
}
func cloneMap(m map[string]struct{}) map[string]struct{} {
c := make(map[string]struct{}, len(m))
for k, v := range m {
c[k] = v
}
return c
}
func pickUnique(pickCount int, orig map[string]struct{}, dest map[string]struct{}) {
i := 0
for k := range orig { // randomly pass on clients
if i == pickCount { // pick exactly size
break
}
dest[k] = struct{}{}
delete(orig, k) // unique pick
i++
}
}
func (fo *FixedRolacle) generateEligibility(expCom int) map[string]struct{} {
emap := make(map[string]struct{}, expCom)
if expCom == 0 {
return emap
}
expHonest := expCom/2 + 1
if expHonest > len(fo.honest) {
log.Warning("Not enough registered honest. Expected %v<=%v", expHonest, len(fo.honest))
expHonest = len(fo.honest)
}
hon := cloneMap(fo.honest)
pickUnique(expHonest, hon, emap)
expFaulty := expCom - expHonest
if expFaulty > len(fo.faulty) {
if len(fo.faulty) > 0 { // not enough
log.Debug("Not enough registered dishonest to pick from. Expected %v<=%v. Picking %v instead", expFaulty, len(fo.faulty), len(fo.faulty))
} else { // no faulty at all - acceptable
log.Debug("No registered dishonest to pick from. Picking honest instead")
}
expFaulty = len(fo.faulty)
}
if expFaulty > 0 { // pick faulty if you need
fau := cloneMap(fo.faulty)
pickUnique(expFaulty, fau, emap)
}
rem := expCom - expHonest - expFaulty
if rem > 0 { // need to pickUnique the remaining from honest
pickUnique(rem, hon, emap)
}
return emap
}
func hashLayerAndRound(instanceID types.LayerID, round int32) uint32 {
kInBytes := make([]byte, 4)
binary.LittleEndian.PutUint32(kInBytes, uint32(round))
h := fnv.New32()
_, err := h.Write(instanceID.ToBytes())
_, err2 := h.Write(kInBytes)
if err != nil || err2 != nil {
log.Error("Errors trying to create a hash %v, %v", err, err2)
}
return h.Sum32()
}
// Eligible returns whether the specific NodeID is eligible for layer in roudn and committee size.
func (fo *FixedRolacle) Eligible(layer types.LayerID, round int32, committeeSize int, id types.NodeID, sig []byte) (bool, error) {
fo.mapRW.RLock()
total := len(fo.honest) + len(fo.faulty) // safe since len >= 0
fo.mapRW.RUnlock()
// normalize committee size
size := committeeSize
if committeeSize > total {
log.Warning("committee size bigger than the number of clients. Expected %v<=%v", committeeSize, total)
size = total
}
instID := hashLayerAndRound(layer, round)
fo.mapRW.Lock()
// generate if not exist for the requested K
if _, exist := fo.emaps[instID]; !exist {
fo.emaps[instID] = fo.generateEligibility(size)
}
fo.mapRW.Unlock()
// get eligibility result
_, exist := fo.emaps[instID][id.Key]
return exist, nil
}
// Proof generates a proof for the round. used to satisfy interface.
func (fo *FixedRolacle) Proof(layer types.LayerID, round int32) ([]byte, error) {
kInBytes := make([]byte, 4)
binary.LittleEndian.PutUint32(kInBytes, uint32(round))
hash := fnv.New32()
_, err := hash.Write(kInBytes)
if err != nil {
log.Error("Error writing hash err: %v", err)
}
hashBytes := make([]byte, 4)
binary.LittleEndian.PutUint32(hashBytes, uint32(hash.Sum32()))
return hashBytes, nil
}