protocol/auth_verification.go

   1 package protocol
   2
   3 import (
   4         "fmt"
   5
   6         log "github.com/sirupsen/logrus"
   7
   8         "github.com/bytom/bytom/consensus"
   9         "github.com/bytom/bytom/protocol/bc"
  10         "github.com/bytom/bytom/protocol/bc/types"
  11         "github.com/bytom/bytom/protocol/state"
  12 )
  13
  14 // AuthVerification verify whether the Verification is legal.
  15 // the status of source checkpoint must justified, and an individual validator ν must not publish two distinct Verification
  16 // ⟨ν,s1,t1,h(s1),h(t1)⟩ and ⟨ν,s2,t2,h(s2),h(t2)⟩, such that either:
  17 // h(t1) = h(t2) OR h(s1) < h(s2) < h(t2) < h(t1)
  18 func (c *Casper) AuthVerification(v *Verification) error {
  19         if err := validate(v); err != nil {
  20                 return err
  21         }
  22
  23         c.mu.Lock()
  24         defer c.mu.Unlock()
  25
  26         // root of tree is the last finalized checkpoint
  27         if v.TargetHeight < c.tree.checkpoint.Height {
  28                 // discard the verification message which height of target less than height of last finalized checkpoint
  29                 // is for simplify check the vote within the span of its other votes
  30                 return nil
  31         }
  32
  33         targetNode, err := c.tree.nodeByHash(v.TargetHash)
  34         if err != nil {
  35                 c.verificationCache.Add(verificationCacheKey(v.TargetHash, v.PubKey), v)
  36                 return nil
  37         }
  38
  39         validators, err := c.Validators(&v.TargetHash)
  40         if err != nil {
  41                 return err
  42         }
  43
  44         if _, ok := validators[v.PubKey]; !ok {
  45                 return errPubKeyIsNotValidator
  46         }
  47
  48         if targetNode.checkpoint.ContainsVerification(validators[v.PubKey].Order, &v.SourceHash) {
  49                 return nil
  50         }
  51
  52         oldBestHash := c.bestChain()
  53         if err := c.authVerification(v, targetNode.checkpoint, validators); err != nil {
  54                 return err
  55         }
  56
  57         return c.tryRollback(oldBestHash)
  58 }
  59
  60 func (c *Casper) authVerification(v *Verification, target *state.Checkpoint, validators map[string]*state.Validator) error {
  61         validator := validators[v.PubKey]
  62         if err := c.verifyVerification(v, validator.Order, true); err != nil {
  63                 return err
  64         }
  65
  66         checkpoints, err := c.addVerificationToCheckpoint(target, validators, v)
  67         if err != nil {
  68                 return err
  69         }
  70
  71         if err := c.store.SaveCheckpoints(checkpoints); err != nil {
  72                 return err
  73         }
  74
  75         return c.saveVerificationToHeader(v, validator.Order)
  76 }
  77
  78 func (c *Casper) addVerificationToCheckpoint(target *state.Checkpoint, validators map[string]*state.Validator, verifications ...*Verification) ([]*state.Checkpoint, error) {
  79         affectedCheckpoints := []*state.Checkpoint{target}
  80         for _, v := range verifications {
  81                 source, err := c.store.GetCheckpoint(&v.SourceHash)
  82                 if err != nil {
  83                         return nil, err
  84                 }
  85
  86                 supLink := target.AddVerification(v.SourceHash, v.SourceHeight, validators[v.PubKey].Order, v.Signature)
  87                 if target.Status != state.Unjustified || !supLink.IsMajority(len(validators)) || source.Status == state.Finalized {
  88                         continue
  89                 }
  90
  91                 c.setJustified(source, target)
  92                 affectedCheckpoints = append(affectedCheckpoints, source)
  93         }
  94         return affectedCheckpoints, nil
  95 }
  96
  97 func (c *Casper) saveVerificationToHeader(v *Verification, validatorOrder int) error {
  98         blockHeader, err := c.store.GetBlockHeader(&v.TargetHash)
  99         if err != nil {
 100                 return err
 101         }
 102
 103         blockHeader.SupLinks.AddSupLink(v.SourceHeight, v.SourceHash, v.Signature, validatorOrder)
 104         return c.store.SaveBlockHeader(blockHeader)
 105 }
 106
 107 // source status is justified, and exist a super majority link from source to target
 108 func (c *Casper) setJustified(source, target *state.Checkpoint) {
 109         target.Status = state.Justified
 110         // must direct child
 111         if target.ParentHash == source.Hash {
 112                 c.setFinalized(source)
 113         }
 114 }
 115
 116 func (c *Casper) setFinalized(checkpoint *state.Checkpoint) {
 117         checkpoint.Status = state.Finalized
 118         newRoot, err := c.tree.nodeByHash(checkpoint.Hash)
 119         if err != nil {
 120                 log.WithField("err", err).Error("source checkpoint before the last finalized checkpoint")
 121                 return
 122         }
 123
 124         // update the checkpoint state in memory
 125         newRoot.checkpoint.Status = state.Finalized
 126         c.tree = newRoot
 127 }
 128
 129 func (c *Casper) tryRollback(oldBestHash bc.Hash) error {
 130         if newBestHash := c.bestChain(); oldBestHash != newBestHash {
 131                 msg := &rollbackMsg{bestHash: newBestHash, reply: make(chan error)}
 132                 c.rollbackCh <- msg
 133                 return <-msg.reply
 134         }
 135         return nil
 136 }
 137
 138 func (c *Casper) authVerificationLoop() {
 139         for blockHash := range c.newEpochCh {
 140                 validators, err := c.Validators(&blockHash)
 141                 if err != nil {
 142                         log.WithField("err", err).Error("get validators when auth verification")
 143                         continue
 144                 }
 145
 146                 for _, validator := range validators {
 147                         key := verificationCacheKey(blockHash, validator.PubKey)
 148                         verification, ok := c.verificationCache.Get(key)
 149                         if !ok {
 150                                 continue
 151                         }
 152
 153                         v := verification.(*Verification)
 154                         target, err := c.store.GetCheckpoint(&v.TargetHash)
 155                         if err != nil {
 156                                 log.WithField("err", err).Error("get target checkpoint")
 157                                 c.verificationCache.Remove(key)
 158                                 continue
 159                         }
 160
 161                         c.mu.Lock()
 162                         if err := c.authVerification(v, target, validators); err != nil {
 163                                 log.WithField("err", err).Error("auth verification in cache")
 164                         }
 165                         c.mu.Unlock()
 166
 167                         c.verificationCache.Remove(key)
 168                 }
 169         }
 170 }
 171
 172 func (c *Casper) verifyVerification(v *Verification, validatorOrder int, trackEvilValidator bool) error {
 173         if err := c.verifySameHeight(v, validatorOrder, trackEvilValidator); err != nil {
 174                 return err
 175         }
 176
 177         return c.verifySpanHeight(v, validatorOrder, trackEvilValidator)
 178 }
 179
 180 // a validator must not publish two distinct votes for the same target height
 181 func (c *Casper) verifySameHeight(v *Verification, validatorOrder int, trackEvilValidator bool) error {
 182         checkpoints, err := c.store.GetCheckpointsByHeight(v.TargetHeight)
 183         if err != nil {
 184                 return err
 185         }
 186
 187         for _, checkpoint := range checkpoints {
 188                 for _, supLink := range checkpoint.SupLinks {
 189                         if len(supLink.Signatures[validatorOrder]) != 0 && checkpoint.Hash != v.TargetHash {
 190                                 if trackEvilValidator {
 191                                         c.evilValidators[v.PubKey] = []*Verification{v, makeVerification(supLink, checkpoint, v.PubKey, validatorOrder)}
 192                                 }
 193                                 return errSameHeightInVerification
 194                         }
 195                 }
 196         }
 197         return nil
 198 }
 199
 200 // a validator must not vote within the span of its other votes.
 201 func (c *Casper) verifySpanHeight(v *Verification, validatorOrder int, trackEvilValidator bool) error {
 202         if c.tree.findOnlyOne(func(checkpoint *state.Checkpoint) bool {
 203                 if checkpoint.Height == v.TargetHeight {
 204                         return false
 205                 }
 206
 207                 for _, supLink := range checkpoint.SupLinks {
 208                         if len(supLink.Signatures[validatorOrder]) != 0 {
 209                                 if (checkpoint.Height < v.TargetHeight && supLink.SourceHeight > v.SourceHeight) ||
 210                                         (checkpoint.Height > v.TargetHeight && supLink.SourceHeight < v.SourceHeight) {
 211                                         if trackEvilValidator {
 212                                                 c.evilValidators[v.PubKey] = []*Verification{v, makeVerification(supLink, checkpoint, v.PubKey, validatorOrder)}
 213                                         }
 214                                         return true
 215                                 }
 216                         }
 217                 }
 218                 return false
 219         }) != nil {
 220                 return errSpanHeightInVerification
 221         }
 222         return nil
 223 }
 224
 225 func makeVerification(supLink *types.SupLink, checkpoint *state.Checkpoint, pubKey string, validatorOrder int) *Verification {
 226         return &Verification{
 227                 SourceHash:   supLink.SourceHash,
 228                 TargetHash:   checkpoint.Hash,
 229                 SourceHeight: supLink.SourceHeight,
 230                 TargetHeight: checkpoint.Height,
 231                 Signature:    supLink.Signatures[validatorOrder],
 232                 PubKey:       pubKey,
 233         }
 234 }
 235
 236 func validate(v *Verification) error {
 237         blocksOfEpoch := consensus.ActiveNetParams.BlocksOfEpoch
 238         if v.SourceHeight%blocksOfEpoch != 0 || v.TargetHeight%blocksOfEpoch != 0 {
 239                 return errVoteToGrowingCheckpoint
 240         }
 241
 242         if v.SourceHeight == v.TargetHeight {
 243                 return errVoteToSameCheckpoint
 244         }
 245
 246         return v.VerifySignature()
 247 }
 248
 249 func verificationCacheKey(blockHash bc.Hash, pubKey string) string {
 250         return fmt.Sprintf("%s:%s", blockHash.String(), pubKey)
 251 }