github.com/ylsGit/go-ethereum@v1.6.5/consensus/clique/snapshot.go (about) 1 // Copyright 2017 The go-ethereum Authors 2 // This file is part of the go-ethereum library. 3 // 4 // The go-ethereum library is free software: you can redistribute it and/or modify 5 // it under the terms of the GNU Lesser General Public License as published by 6 // the Free Software Foundation, either version 3 of the License, or 7 // (at your option) any later version. 8 // 9 // The go-ethereum library is distributed in the hope that it will be useful, 10 // but WITHOUT ANY WARRANTY; without even the implied warranty of 11 // MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the 12 // GNU Lesser General Public License for more details. 13 // 14 // You should have received a copy of the GNU Lesser General Public License 15 // along with the go-ethereum library. If not, see <http://www.gnu.org/licenses/>. 16 17 package clique 18 19 import ( 20 "bytes" 21 "encoding/json" 22 23 "github.com/ethereum/go-ethereum/common" 24 "github.com/ethereum/go-ethereum/core/types" 25 "github.com/ethereum/go-ethereum/ethdb" 26 "github.com/ethereum/go-ethereum/params" 27 lru "github.com/hashicorp/golang-lru" 28 ) 29 30 // Vote represents a single vote that an authorized signer made to modify the 31 // list of authorizations. 32 type Vote struct { 33 Signer common.Address `json:"signer"` // Authorized signer that cast this vote 34 Block uint64 `json:"block"` // Block number the vote was cast in (expire old votes) 35 Address common.Address `json:"address"` // Account being voted on to change its authorization 36 Authorize bool `json:"authorize"` // Whether to authorize or deauthorize the voted account 37 } 38 39 // Tally is a simple vote tally to keep the current score of votes. Votes that 40 // go against the proposal aren't counted since it's equivalent to not voting. 41 type Tally struct { 42 Authorize bool `json:"authorize"` // Whether the vote it about authorizing or kicking someone 43 Votes int `json:"votes"` // Number of votes until now wanting to pass the proposal 44 } 45 46 // Snapshot is the state of the authorization voting at a given point in time. 47 type Snapshot struct { 48 config *params.CliqueConfig // Consensus engine parameters to fine tune behavior 49 sigcache *lru.ARCCache // Cache of recent block signatures to speed up ecrecover 50 51 Number uint64 `json:"number"` // Block number where the snapshot was created 52 Hash common.Hash `json:"hash"` // Block hash where the snapshot was created 53 Signers map[common.Address]struct{} `json:"signers"` // Set of authorized signers at this moment 54 Recents map[uint64]common.Address `json:"recents"` // Set of recent signers for spam protections 55 Votes []*Vote `json:"votes"` // List of votes cast in chronological order 56 Tally map[common.Address]Tally `json:"tally"` // Current vote tally to avoid recalculating 57 } 58 59 // newSnapshot create a new snapshot with the specified startup parameters. This 60 // method does not initialize the set of recent signers, so only ever use if for 61 // the genesis block. 62 func newSnapshot(config *params.CliqueConfig, sigcache *lru.ARCCache, number uint64, hash common.Hash, signers []common.Address) *Snapshot { 63 snap := &Snapshot{ 64 config: config, 65 sigcache: sigcache, 66 Number: number, 67 Hash: hash, 68 Signers: make(map[common.Address]struct{}), 69 Recents: make(map[uint64]common.Address), 70 Tally: make(map[common.Address]Tally), 71 } 72 for _, signer := range signers { 73 snap.Signers[signer] = struct{}{} 74 } 75 return snap 76 } 77 78 // loadSnapshot loads an existing snapshot from the database. 79 func loadSnapshot(config *params.CliqueConfig, sigcache *lru.ARCCache, db ethdb.Database, hash common.Hash) (*Snapshot, error) { 80 blob, err := db.Get(append([]byte("clique-"), hash[:]...)) 81 if err != nil { 82 return nil, err 83 } 84 snap := new(Snapshot) 85 if err := json.Unmarshal(blob, snap); err != nil { 86 return nil, err 87 } 88 snap.config = config 89 snap.sigcache = sigcache 90 91 return snap, nil 92 } 93 94 // store inserts the snapshot into the database. 95 func (s *Snapshot) store(db ethdb.Database) error { 96 blob, err := json.Marshal(s) 97 if err != nil { 98 return err 99 } 100 return db.Put(append([]byte("clique-"), s.Hash[:]...), blob) 101 } 102 103 // copy creates a deep copy of the snapshot, though not the individual votes. 104 func (s *Snapshot) copy() *Snapshot { 105 cpy := &Snapshot{ 106 config: s.config, 107 sigcache: s.sigcache, 108 Number: s.Number, 109 Hash: s.Hash, 110 Signers: make(map[common.Address]struct{}), 111 Recents: make(map[uint64]common.Address), 112 Votes: make([]*Vote, len(s.Votes)), 113 Tally: make(map[common.Address]Tally), 114 } 115 for signer := range s.Signers { 116 cpy.Signers[signer] = struct{}{} 117 } 118 for block, signer := range s.Recents { 119 cpy.Recents[block] = signer 120 } 121 for address, tally := range s.Tally { 122 cpy.Tally[address] = tally 123 } 124 copy(cpy.Votes, s.Votes) 125 126 return cpy 127 } 128 129 // cast adds a new vote into the tally. 130 func (s *Snapshot) cast(address common.Address, authorize bool) bool { 131 // Ensure the vote is meaningful 132 _, signer := s.Signers[address] 133 if (signer && authorize) || (!signer && !authorize) { 134 return false 135 } 136 // Cast the vote into an existing or new tally 137 if old, ok := s.Tally[address]; ok { 138 old.Votes++ 139 s.Tally[address] = old 140 } else { 141 s.Tally[address] = Tally{Authorize: authorize, Votes: 1} 142 } 143 return true 144 } 145 146 // uncast removes a previously cast vote from the tally. 147 func (s *Snapshot) uncast(address common.Address, authorize bool) bool { 148 // If there's no tally, it's a dangling vote, just drop 149 tally, ok := s.Tally[address] 150 if !ok { 151 return false 152 } 153 // Ensure we only revert counted votes 154 if tally.Authorize != authorize { 155 return false 156 } 157 // Otherwise revert the vote 158 if tally.Votes > 1 { 159 tally.Votes-- 160 s.Tally[address] = tally 161 } else { 162 delete(s.Tally, address) 163 } 164 return true 165 } 166 167 // apply creates a new authorization snapshot by applying the given headers to 168 // the original one. 169 func (s *Snapshot) apply(headers []*types.Header) (*Snapshot, error) { 170 // Allow passing in no headers for cleaner code 171 if len(headers) == 0 { 172 return s, nil 173 } 174 // Sanity check that the headers can be applied 175 for i := 0; i < len(headers)-1; i++ { 176 if headers[i+1].Number.Uint64() != headers[i].Number.Uint64()+1 { 177 return nil, errInvalidVotingChain 178 } 179 } 180 if headers[0].Number.Uint64() != s.Number+1 { 181 return nil, errInvalidVotingChain 182 } 183 // Iterate through the headers and create a new snapshot 184 snap := s.copy() 185 186 for _, header := range headers { 187 // Remove any votes on checkpoint blocks 188 number := header.Number.Uint64() 189 if number%s.config.Epoch == 0 { 190 snap.Votes = nil 191 snap.Tally = make(map[common.Address]Tally) 192 } 193 // Delete the oldest signer from the recent list to allow it signing again 194 if limit := uint64(len(snap.Signers)/2 + 1); number >= limit { 195 delete(snap.Recents, number-limit) 196 } 197 // Resolve the authorization key and check against signers 198 signer, err := ecrecover(header, s.sigcache) 199 if err != nil { 200 return nil, err 201 } 202 if _, ok := snap.Signers[signer]; !ok { 203 return nil, errUnauthorized 204 } 205 for _, recent := range snap.Recents { 206 if recent == signer { 207 return nil, errUnauthorized 208 } 209 } 210 snap.Recents[number] = signer 211 212 // Header authorized, discard any previous votes from the signer 213 for i, vote := range snap.Votes { 214 if vote.Signer == signer && vote.Address == header.Coinbase { 215 // Uncast the vote from the cached tally 216 snap.uncast(vote.Address, vote.Authorize) 217 218 // Uncast the vote from the chronological list 219 snap.Votes = append(snap.Votes[:i], snap.Votes[i+1:]...) 220 break // only one vote allowed 221 } 222 } 223 // Tally up the new vote from the signer 224 var authorize bool 225 switch { 226 case bytes.Compare(header.Nonce[:], nonceAuthVote) == 0: 227 authorize = true 228 case bytes.Compare(header.Nonce[:], nonceDropVote) == 0: 229 authorize = false 230 default: 231 return nil, errInvalidVote 232 } 233 if snap.cast(header.Coinbase, authorize) { 234 snap.Votes = append(snap.Votes, &Vote{ 235 Signer: signer, 236 Block: number, 237 Address: header.Coinbase, 238 Authorize: authorize, 239 }) 240 } 241 // If the vote passed, update the list of signers 242 if tally := snap.Tally[header.Coinbase]; tally.Votes > len(snap.Signers)/2 { 243 if tally.Authorize { 244 snap.Signers[header.Coinbase] = struct{}{} 245 } else { 246 delete(snap.Signers, header.Coinbase) 247 248 // Signer list shrunk, delete any leftover recent caches 249 if limit := uint64(len(snap.Signers)/2 + 1); number >= limit { 250 delete(snap.Recents, number-limit) 251 } 252 // Discard any previous votes the deauthorized signer cast 253 for i := 0; i < len(snap.Votes); i++ { 254 if snap.Votes[i].Signer == header.Coinbase { 255 // Uncast the vote from the cached tally 256 snap.uncast(snap.Votes[i].Address, snap.Votes[i].Authorize) 257 258 // Uncast the vote from the chronological list 259 snap.Votes = append(snap.Votes[:i], snap.Votes[i+1:]...) 260 261 i-- 262 } 263 } 264 } 265 // Discard any previous votes around the just changed account 266 for i := 0; i < len(snap.Votes); i++ { 267 if snap.Votes[i].Address == header.Coinbase { 268 snap.Votes = append(snap.Votes[:i], snap.Votes[i+1:]...) 269 i-- 270 } 271 } 272 delete(snap.Tally, header.Coinbase) 273 } 274 } 275 snap.Number += uint64(len(headers)) 276 snap.Hash = headers[len(headers)-1].Hash() 277 278 return snap, nil 279 } 280 281 // signers retrieves the list of authorized signers in ascending order. 282 func (s *Snapshot) signers() []common.Address { 283 signers := make([]common.Address, 0, len(s.Signers)) 284 for signer := range s.Signers { 285 signers = append(signers, signer) 286 } 287 for i := 0; i < len(signers); i++ { 288 for j := i + 1; j < len(signers); j++ { 289 if bytes.Compare(signers[i][:], signers[j][:]) > 0 { 290 signers[i], signers[j] = signers[j], signers[i] 291 } 292 } 293 } 294 return signers 295 } 296 297 // inturn returns if a signer at a given block height is in-turn or not. 298 func (s *Snapshot) inturn(number uint64, signer common.Address) bool { 299 signers, offset := s.signers(), 0 300 for offset < len(signers) && signers[offset] != signer { 301 offset++ 302 } 303 return (number % uint64(len(signers))) == uint64(offset) 304 }