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