# Nimbus # Copyright (c) 2018 Status Research & Development GmbH # Licensed under either of # * Apache License, version 2.0, ([LICENSE-APACHE](LICENSE-APACHE) or # http://www.apache.org/licenses/LICENSE-2.0) # * MIT license ([LICENSE-MIT](LICENSE-MIT) or # http://opensource.org/licenses/MIT) # at your option. This file may not be copied, modified, or distributed except # according to those terms. ## ## Votes Management for Clique PoA Consensus Protocol ## ================================================= ## ## For details see ## `EIP-225 `_ ## and ## `go-ethereum `_ ## import std/[sequtils, tables], ../clique_helpers, eth/common type Vote* = object ## Vote represent single votes that an authorized signer made to modify ## the list of authorizations. signer*: EthAddress ## authorized signer that cast this vote address*: EthAddress ## account being voted on to change its ## authorization type (`true` or `false`) blockNumber*: BlockNumber ## block number the vote was cast in ## (expire old votes) authorize*: bool ## authorization type, whether to authorize or ## deauthorize the voted account Tally = object authorize: bool signers: Table[EthAddress,Vote] Ballot* = object votes: Table[EthAddress,Tally] ## votes by account -> signer authSig: Table[EthAddress,bool] ## currently authorised signers authRemoved: bool ## last `addVote()` action was removing an ## authorised signer from the `authSig` list {.push raises: [].} # ------------------------------------------------------------------------------ # Public debugging/pretty-printer support # ------------------------------------------------------------------------------ proc votesInternal*(t: var Ballot): seq[(EthAddress,EthAddress,Vote)] = for account,tally in t.votes.pairs: for signer,vote in tally.signers.pairs: result.add (account, signer, vote) # ------------------------------------------------------------------------------ # Public constructor # ------------------------------------------------------------------------------ proc initBallot*(t: var Ballot) = ## Ininialise an empty `Ballot` descriptor. t.votes = initTable[EthAddress,Tally]() t.authSig = initTable[EthAddress,bool]() proc initBallot*(t: var Ballot; signers: openArray[EthAddress]) = ## Ininialise `Ballot` with a given authorised signers list t.initBallot for a in signers: t.authSig[a] = true # ------------------------------------------------------------------------------ # Public getters # ------------------------------------------------------------------------------ proc authSigners*(t: var Ballot): seq[EthAddress] = ## Sorted ascending list of authorised signer addresses toSeq(t.authSig.keys).sorted(EthAscending) proc authSignersLen*(t: var Ballot): int = ## Returns the number of currently known authorised signers. t.authSig.len proc isAuthSignersListShrunk*(t: var Ballot): bool = ## Check whether the authorised signers list was shrunk recently after ## appying `addVote()` t.authRemoved proc authSignersThreshold*(t: var Ballot): int = ## Returns the minimum number of authorised signers needed for authorising ## a addres for voting. This is currently ## :: ## 1 + half of the number of authorised signers ## 1 + (t.authSig.len div 2) # ------------------------------------------------------------------------------ # Public functions # ------------------------------------------------------------------------------ proc isAuthSigner*(t: var Ballot; addresses: var seq[EthAddress]): bool = ## Check whether all `addresses` entries are authorised signers. ## ## Using this function should be preferable over `authSigners()` which has ## complexity `O(log n)` while this function runs with `O(n)`. for a in addresses: if a notin t.authSig: return false true proc isAuthSigner*(t: var Ballot; address: EthAddress): bool = ## Check whether `address` is an authorised signer address in t.authSig proc delVote*(t: var Ballot; signer, address: EthAddress) {. gcsafe, raises: [KeyError].} = ## Remove a particular previously added vote. if address in t.votes: if signer in t.votes[address].signers: if t.votes[address].signers.len <= 1: t.votes.del(address) else: t.votes[address].signers.del(signer) proc flushVotes*(t: var Ballot) = ## Reset/flush pending votes, authorised signers remain the same. t.votes.clear # clique/snapshot.go(141): func (s *Snapshot) validVote(address [..] proc isValidVote*(t: var Ballot; address: EthAddress; authorize: bool): bool = ## Check whether voting would have an effect in `addVote()` if address in t.authSig: not authorize else: authorize proc addVote*(t: var Ballot; vote: Vote) {. gcsafe, raises: [KeyError].} = ## Add a new vote collecting the signers for the particular voting address. ## ## Unless it is the first vote for this address, the authorisation type ## `true` or `false` of the vote must match the previous one. For the first ## vote, the authorisation type `true` is accepted if the address is not an ## authorised signer, and `false` if it is an authorised signer. Otherwise ## the vote is ignored. ## ## If the number of signers for the particular address are at least ## `authSignersThreshold()`, the status of this address will change as ## follows. ## * If the authorisation type is `true`, the address is added ## to the list of authorised signers. ## * If the authorisation type is `false`, the address is removed ## from the list of authorised signers. t.authRemoved = false var numVotes = 0 authOk = vote.authorize # clique/snapshot.go(147): if !s.validVote(address, [..] if not t.isValidVote(vote.address, vote.authorize): # Corner case: touch votes for this account if t.votes.hasKey(vote.address): let refVote = t.votes[vote.address] numVotes = refVote.signers.len authOk = refVote.authorize elif not t.votes.hasKey(vote.address): # Collect inital vote t.votes[vote.address] = Tally( authorize: vote.authorize, signers: {vote.signer: vote}.toTable) numVotes = 1 elif t.votes[vote.address].authorize == vote.authorize: # Collect additional vote t.votes[vote.address].signers[vote.signer] = vote numVotes = t.votes[vote.address].signers.len else: return # clique/snapshot.go(262): if tally := snap.Tally[header.Coinbase]; [..] # Vote passed, update the list of authorised signers if enough votes if numVotes < t.authSignersThreshold: return var obsolete = @[vote.address] if authOk: # Has minimum votes, so add it t.authSig[vote.address] = true else: # clique/snapshot.go(266): delete(snap.Signers, [..] t.authSig.del(vote.address) t.authRemoved = true # Not a signer anymore => remove it everywhere for key,value in t.votes.mpairs: if vote.address in value.signers: if 1 < value.signers.len: value.signers.del(vote.address) else: obsolete.add key for key in obsolete: t.votes.del(key) # ------------------------------------------------------------------------------ # End # ------------------------------------------------------------------------------