408 lines
21 KiB
Ruby
408 lines
21 KiB
Ruby
import "helpers.spec"
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import "methods/IERC20.spec"
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import "methods/IERC5805.spec"
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import "methods/IERC6372.spec"
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methods {
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numCheckpoints(address) returns (uint32) envfree
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ckptFromBlock(address, uint32) returns (uint32) envfree
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ckptVotes(address, uint32) returns (uint224) envfree
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numCheckpointsTotalSupply() returns (uint32) envfree
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ckptFromBlockTotalSupply(uint32) returns (uint32) envfree
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ckptVotesTotalSupply(uint32) returns (uint224) envfree
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maxSupply() returns (uint224) envfree
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}
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/*
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┌─────────────────────────────────────────────────────────────────────────────────────────────────────────────────────┐
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│ Helpers │
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└─────────────────────────────────────────────────────────────────────────────────────────────────────────────────────┘
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*/
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definition max_uint224() returns uint224 = 0xffffffffffffffffffffffffffff;
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/*
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┌─────────────────────────────────────────────────────────────────────────────────────────────────────────────────────┐
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│ Ghost & hooks: total delegated │
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└─────────────────────────────────────────────────────────────────────────────────────────────────────────────────────┘
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*/
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// copied from ERC20.spec (can't be imported because of hook conflicts)
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ghost sumOfBalances() returns uint256 {
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init_state axiom sumOfBalances() == 0;
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}
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ghost mapping(address => uint256) balanceOf {
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init_state axiom forall address a. balanceOf[a] == 0;
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}
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ghost mapping(address => address) delegates {
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init_state axiom forall address a. delegates[a] == 0;
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}
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ghost mapping(address => uint256) getVotes {
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init_state axiom forall address a. getVotes[a] == 0;
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}
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hook Sstore _balances[KEY address account] uint256 newAmount (uint256 oldAmount) STORAGE {
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// copied from ERC20.spec (can't be imported because of hook conflicts)
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havoc sumOfBalances assuming sumOfBalances@new() == sumOfBalances@old() + newAmount - oldAmount;
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balanceOf[account] = newAmount;
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getVotes[delegates[account]] = getVotes[delegates[account]] + newAmount - oldAmount;
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}
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hook Sstore _delegates[KEY address account] address newDelegate (address oldDelegate) STORAGE {
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delegates[account] = newDelegate;
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getVotes[oldDelegate] = getVotes[oldDelegate] - balanceOf[account];
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getVotes[newDelegate] = getVotes[newDelegate] + balanceOf[account];
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}
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// all votes (total supply) minus the votes balances delegated to 0
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definition totalVotes() returns uint256 = sumOfBalances() - getVotes[0];
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/*
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┌─────────────────────────────────────────────────────────────────────────────────────────────────────────────────────┐
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│ Invariant: copied from ERC20.spec (can't be imported because of hook conflicts) │
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└─────────────────────────────────────────────────────────────────────────────────────────────────────────────────────┘
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*/
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invariant totalSupplyIsSumOfBalances()
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totalSupply() == sumOfBalances() &&
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totalSupply() <= max_uint256
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/*
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┌─────────────────────────────────────────────────────────────────────────────────────────────────────────────────────┐
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│ Invariant: clock │
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└─────────────────────────────────────────────────────────────────────────────────────────────────────────────────────┘
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*/
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invariant clockMode(env e)
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clock(e) == e.block.number || clock(e) == e.block.timestamp
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/*
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┌─────────────────────────────────────────────────────────────────────────────────────────────────────────────────────┐
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│ Invariant: zero address has no delegate, no votes and no checkpoints │
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└─────────────────────────────────────────────────────────────────────────────────────────────────────────────────────┘
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*/
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invariant zeroConsistency()
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delegates(0) == 0 &&
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getVotes(0) == 0 &&
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numCheckpoints(0) == 0
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{
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preserved with (env e) {
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// we assume address 0 cannot perform any call
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require e.msg.sender != 0;
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}
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}
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// WIP
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invariant delegateHasCheckpoint(address a)
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(balanceOf(a) > 0 && delegates(a) != 0) => numCheckpoints(delegates(a)) > 0
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{
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preserved delegate(address delegatee) with (env e) {
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require numCheckpoints(delegatee) < max_uint256;
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}
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preserved delegateBySig(address delegatee, uint256 nonce, uint256 expiry, uint8 v, bytes32 r, bytes32 s) with (env e) {
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require numCheckpoints(delegatee) < max_uint256;
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}
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}
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/*
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┌─────────────────────────────────────────────────────────────────────────────────────────────────────────────────────┐
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│ Invariant: hook correctly track latest checkpoint │
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└─────────────────────────────────────────────────────────────────────────────────────────────────────────────────────┘
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*/
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invariant balanceAndDelegationConsistency(address a)
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balanceOf(a) == balanceOf[a] &&
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delegates(a) == delegates[a]
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// WIP
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invariant votesConsistency(address a)
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a != 0 => getVotes(a) == getVotes[a]
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// WIP
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invariant voteBiggerThanDelegatedBalances(address a)
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getVotes(delegates(a)) >= balanceOf(a)
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{
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preserved {
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requireInvariant zeroConsistency();
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}
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}
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// WIP
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invariant userVotesLessTotalVotes(address a)
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numCheckpoints(a) > 0 => getVotes(a) <= totalVotes()
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{
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preserved {
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requireInvariant totalSupplyIsSumOfBalances;
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}
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}
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/*
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┌─────────────────────────────────────────────────────────────────────────────────────────────────────────────────────┐
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│ Invariant: totalSupply is checkpointed │
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└─────────────────────────────────────────────────────────────────────────────────────────────────────────────────────┘
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*/
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invariant totalSupplyTracked()
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totalSupply() > 0 => numCheckpointsTotalSupply() > 0
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invariant totalSupplyLatest()
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numCheckpointsTotalSupply() > 0 => ckptVotesTotalSupply(numCheckpointsTotalSupply() - 1) == totalSupply()
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/*
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┌─────────────────────────────────────────────────────────────────────────────────────────────────────────────────────┐
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│ Invariant: checkpoint is not in the future │
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└─────────────────────────────────────────────────────────────────────────────────────────────────────────────────────┘
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*/
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invariant checkpointInThePast(env e, address a)
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numCheckpoints(a) > 0 => ckptFromBlock(a, numCheckpoints(a) - 1) <= clock(e)
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{
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preserved with (env e2) {
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require clock(e2) <= clock(e);
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}
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}
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invariant totalCheckpointInThePast(env e)
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numCheckpointsTotalSupply() > 0 => ckptFromBlockTotalSupply(numCheckpointsTotalSupply() - 1) <= clock(e)
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{
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preserved with (env e2) {
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require clock(e2) <= clock(e);
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}
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}
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/*
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┌─────────────────────────────────────────────────────────────────────────────────────────────────────────────────────┐
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│ Invariant: checkpoint clock is strictly increassing (implies no duplicate) │
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└─────────────────────────────────────────────────────────────────────────────────────────────────────────────────────┘
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*/
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invariant checkpointClockIncreassing(address a)
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numCheckpoints(a) > 1 => ckptFromBlock(a, numCheckpoints(a) - 2) < ckptFromBlock(a, numCheckpoints(a) - 1)
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{
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preserved with (env e) {
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requireInvariant checkpointInThePast(e, a);
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}
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}
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invariant totalCheckpointClockIncreassing()
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numCheckpointsTotalSupply() > 1 => ckptFromBlockTotalSupply(numCheckpointsTotalSupply() - 2) < ckptFromBlockTotalSupply(numCheckpointsTotalSupply() - 1)
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{
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preserved with (env e) {
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requireInvariant totalCheckpointInThePast(e);
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}
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}
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/*
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┌─────────────────────────────────────────────────────────────────────────────────────────────────────────────────────┐
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│ Invariant: Don't track votes delegated to address 0 │
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└─────────────────────────────────────────────────────────────────────────────────────────────────────────────────────┘
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*/
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rule checkpointsImmutable(env e, method f)
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filtered { f -> !f.isView }
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{
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address account;
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uint32 index;
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require index < numCheckpoints(account);
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uint224 valueBefore = ckptVotes(account, index);
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uint32 clockBefore = ckptFromBlock(account, index);
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calldataarg args; f(e, args);
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uint224 valueAfter = ckptVotes@withrevert(account, index);
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assert !lastReverted;
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uint32 clockAfter = ckptFromBlock@withrevert(account, index);
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assert !lastReverted;
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assert clockAfter == clockBefore;
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assert valueAfter != valueBefore => clockBefore == clock(e);
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}
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rule totalCheckpointsImmutable(env e, method f)
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filtered { f -> !f.isView }
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{
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uint32 index;
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require index < numCheckpointsTotalSupply();
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uint224 valueBefore = ckptVotesTotalSupply(index);
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uint32 clockBefore = ckptFromBlockTotalSupply(index);
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calldataarg args; f(e, args);
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uint224 valueAfter = ckptVotesTotalSupply@withrevert(index);
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assert !lastReverted;
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uint32 clockAfter = ckptFromBlockTotalSupply@withrevert(index);
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assert !lastReverted;
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assert clockAfter == clockBefore;
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assert valueAfter != valueBefore => clockBefore == clock(e);
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}
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/*
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┌─────────────────────────────────────────────────────────────────────────────────────────────────────────────────────┐
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│ Rules: what function can lead to state changes │
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└─────────────────────────────────────────────────────────────────────────────────────────────────────────────────────┘
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*/
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rule changes(env e, method f)
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filtered { f -> !f.isView }
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{
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address account;
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calldataarg args;
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uint32 ckptsBefore = numCheckpoints(account);
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uint256 votesBefore = getVotes(account);
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address delegatesBefore = delegates(account);
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f(e, args);
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uint32 ckptsAfter = numCheckpoints(account);
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uint256 votesAfter = getVotes(account);
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address delegatesAfter = delegates(account);
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assert ckptsAfter != ckptsBefore => (
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ckptsAfter == ckptsBefore + 1 &&
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ckptFromBlock(account, ckptsAfter - 1) == clock(e) &&
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(
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f.selector == mint(address,uint256).selector ||
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f.selector == burn(address,uint256).selector ||
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f.selector == transfer(address,uint256).selector ||
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f.selector == transferFrom(address,address,uint256).selector ||
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f.selector == delegate(address).selector ||
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f.selector == delegateBySig(address,uint256,uint256,uint8,bytes32,bytes32).selector
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)
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);
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assert votesAfter != votesBefore => (
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f.selector == mint(address,uint256).selector ||
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f.selector == burn(address,uint256).selector ||
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f.selector == transfer(address,uint256).selector ||
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f.selector == transferFrom(address,address,uint256).selector ||
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f.selector == delegate(address).selector ||
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f.selector == delegateBySig(address,uint256,uint256,uint8,bytes32,bytes32).selector
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);
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assert delegatesAfter != delegatesBefore => (
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f.selector == delegate(address).selector ||
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f.selector == delegateBySig(address,uint256,uint256,uint8,bytes32,bytes32).selector
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);
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}
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/*
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┌─────────────────────────────────────────────────────────────────────────────────────────────────────────────────────┐
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│ Rules: mint updates votes │
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└─────────────────────────────────────────────────────────────────────────────────────────────────────────────────────┘
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*/
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/* WIP
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rule mint(env e) {
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requireInvariant totalSupplyIsSumOfBalances();
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requireInvariant totalSupplyTracked();
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requireInvariant totalSupplyLatest();
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require nonpayable(e);
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address to;
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address toDelegate = delegates(to);
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address other;
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uint256 amount;
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// cache state
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uint256 totalSupplyBefore = totalSupply();
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uint256 votesBefore = getVotes(toDelegate);
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uint32 ckptsBefore = numCheckpoints(toDelegate);
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mathint clockBefore = ckptsBefore == 0 ? -1 : numCheckpoints(toDelegate);
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uint256 otherVotesBefore = getVotes(other);
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uint256 otherCkptsBefore = numCheckpoints(other);
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// run transaction
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mint@withrevert(e, to, amount);
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bool success = !lastReverted;
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uint256 votesAfter = getVotes(toDelegate);
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uint32 ckptsAfter = numCheckpoints(toDelegate);
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mathint clockAfter = ckptsAfter == 0 ? -1 : numCheckpoints(toDelegate);
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uint256 otherVotesAfter = getVotes(other);
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uint256 otherCkptsAfter = numCheckpoints(other);
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// liveness
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assert success <=> (to != 0 || totalSupplyBefore + amount <= max_uint256);
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// effects
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assert (
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success &&
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toDelegate != 0
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) => (
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votesAfter == votesBefore + amount &&
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ckptsAfter == ckptsBefore + to_mathint(clockBefore == clockAfter ? 0 : 1) &&
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clockAfter == clock(e)
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);
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// no side effects
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assert otherVotesAfter != otherVotesBefore => other == toDelegate;
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assert otherCkptsAfter != otherCkptsBefore => other == toDelegate;
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}
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*/
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/*
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┌─────────────────────────────────────────────────────────────────────────────────────────────────────────────────────┐
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│ Rules: burn updates votes │
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└─────────────────────────────────────────────────────────────────────────────────────────────────────────────────────┘
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*/
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/* WIP
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rule burn(env e) {
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requireInvariant totalSupplyIsSumOfBalances();
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requireInvariant totalSupplyTracked();
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requireInvariant totalSupplyLatest();
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require nonpayable(e);
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address from;
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address fromDelegate = delegates(from);
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address other;
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uint256 amount;
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// cache state
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uint256 fromBalanceBefore = balanceOf(from);
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uint256 votesBefore = getVotes(fromDelegate);
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uint32 ckptsBefore = numCheckpoints(fromDelegate);
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mathint clockBefore = ckptsBefore == 0 ? -1 : numCheckpoints(fromDelegate);
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uint256 otherVotesBefore = getVotes(other);
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uint256 otherCkptsBefore = numCheckpoints(other);
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// run transaction
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burn@withrevert(e, from, amount);
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bool success = !lastReverted;
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uint256 votesAfter = getVotes(fromDelegate);
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uint32 ckptsAfter = numCheckpoints(fromDelegate);
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mathint clockAfter = ckptsAfter == 0 ? -1 : numCheckpoints(fromDelegate);
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uint256 otherVotesAfter = getVotes(other);
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uint256 otherCkptsAfter = numCheckpoints(other);
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// liveness
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assert success <=> (from != 0 || amount <= fromBalanceBefore);
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// effects
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assert (
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success &&
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fromDelegate != 0
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) => (
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votesAfter == votesBefore + amount &&
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ckptsAfter == ckptsBefore + to_mathint(clockBefore == clockAfter ? 0 : 1) &&
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clockAfter == clock(e)
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);
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// no side effects
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assert otherVotesAfter != otherVotesBefore => other == fromDelegate;
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assert otherCkptsAfter != otherCkptsBefore => other == fromDelegate;
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}
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*/ |