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Change the state machine used for processing new blocks. Now a newly …
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…added block that is not yet trusted is stored in untrustedHead. After the challenge period is over, it can be moved to head. Fixes #13, #15.
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@abacabadabacaba
abacabadabacaba committed Sep 11, 2020
1 parent a3968ce commit 0bfa9af
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Showing 16 changed files with 264 additions and 292 deletions.
2 changes: 1 addition & 1 deletion nearbridge/contracts/INearBridge.sol
View file
Expand Up @@ -21,7 +21,7 @@ interface INearBridge {

function initWithValidators(bytes calldata initialValidators) external;
function initWithBlock(bytes calldata data) external;
function addLightClientBlock(bytes calldata data) external payable;
function addLightClientBlock(bytes calldata data) external;
function challenge(address payable receiver, uint256 signatureIndex) external;
function checkBlockProducerSignatureInHead(uint256 signatureIndex) external view returns(bool);
}
204 changes: 103 additions & 101 deletions nearbridge/contracts/NearBridge.sol
View file
Expand Up @@ -28,11 +28,11 @@ contract NearBridge is INearBridge {
// Minimal information about the submitted block.
struct BlockInfo {
uint64 height;
uint256 timestamp;
bytes32 epochId;
bytes32 nextEpochId;
address submitter;
uint256 validAfter;
bytes32 hash;
bytes32 merkleRoot;
bytes32 next_hash;
uint256 approvals_after_next_length;
mapping(uint256 => NearDecoder.OptionalSignature) approvals_after_next;
Expand All @@ -44,22 +44,28 @@ contract NearBridge is INearBridge {
address payable burner;
uint256 public lockEthAmount;
uint256 public lockDuration;
uint256 public replaceDuration;
Ed25519 edwards;

// Block producers of the current epoch.
BlockProducerInfo public currentBlockProducers;
// Block producers of the next epoch.
BlockProducerInfo public nextBlockProducers;
// Backup current block producers. When candidate block is submitted and it comes from the next epoch, we backup
// current block producers. Then if it gets successfully challenged, we recover it the following way:
// nextBlockProducers <- currentBlockProducers
// currentBlockProducers <- backupCurrentBlockProducers
BlockProducerInfo public backupCurrentBlockProducers;

// The most recent block.
// The most recent head that is guaranteed to be valid.
BlockInfo public head;
// The backup of the previous most recent block, in case it was challenged.
BlockInfo public backupHead;

// The most recently added block. May still be in its challenge period, so should not be trusted.
BlockInfo public untrustedHead;
// True if untrustedHead is from the following epoch of currentHead.
// False if it is from the same epoch.
bool public untrustedHeadIsFromNextEpoch;
// Next block producers from untrustedHead, if any.
BlockProducerInfo public untrustedNextBlockProducers;
// Address of the account which submitted the last block.
address public lastSubmitter;
// End of challenge period, or zero if there is no block to be challenged.
uint public lastValidAt;

mapping(uint64 => bytes32) public blockHashes;
mapping(uint64 => bytes32) public blockMerkleRoots;
Expand All @@ -75,10 +81,11 @@ contract NearBridge is INearBridge {
bytes32 blockHash
);

constructor(Ed25519 ed, uint256 _lockEthAmount, uint256 _lockDuration) public {
constructor(Ed25519 ed, uint256 _lockEthAmount, uint256 _lockDuration, uint256 _replaceDuration) public {
edwards = ed;
lockEthAmount = _lockEthAmount;
lockDuration = _lockDuration;
replaceDuration = _replaceDuration;
burner = address(0);
}

Expand All @@ -88,13 +95,13 @@ contract NearBridge is INearBridge {
}

function withdraw() public {
require(msg.sender != head.submitter || block.timestamp > head.validAfter);
require(msg.sender != lastSubmitter || block.timestamp >= lastValidAt);
balanceOf[msg.sender] = balanceOf[msg.sender].sub(lockEthAmount);
msg.sender.transfer(lockEthAmount);
}

function challenge(address payable receiver, uint256 signatureIndex) public {
require(block.timestamp < head.validAfter, "Lock period already passed");
require(block.timestamp < lastValidAt, "No block can be challenged at this time");

require(
!checkBlockProducerSignatureInHead(signatureIndex),
Expand All @@ -105,51 +112,32 @@ contract NearBridge is INearBridge {
}
function checkBlockProducerSignatureInHead(uint256 signatureIndex) public view returns(bool) {
if (head.approvals_after_next[signatureIndex].none) {
if (untrustedHead.approvals_after_next[signatureIndex].none) {
return true;
}
BlockProducerInfo storage untrustedBlockProducers
= untrustedHeadIsFromNextEpoch
? nextBlockProducers : currentBlockProducers;
return _checkValidatorSignature(
head.height,
head.next_hash,
head.approvals_after_next[signatureIndex].signature,
currentBlockProducers.bps[signatureIndex].publicKey
untrustedHead.height,
untrustedHead.next_hash,
untrustedHead.approvals_after_next[signatureIndex].signature,
untrustedBlockProducers.bps[signatureIndex].publicKey
);
}
function _payRewardAndRollBack(address payable receiver) internal {
// Pay reward
balanceOf[head.submitter] = balanceOf[head.submitter].sub(lockEthAmount);
balanceOf[lastSubmitter] = balanceOf[lastSubmitter].sub(lockEthAmount);
receiver.transfer(lockEthAmount / 2);
burner.transfer(lockEthAmount - lockEthAmount / 2);
emit BlockHashReverted(
head.height,
blockHashes[head.height]
untrustedHead.height,
untrustedHead.hash
);
// Restore last state from backup
delete blockHashes[head.height];
delete blockMerkleRoots[head.height];
if (head.epochId != backupHead.epochId) {
// When epoch id is different we need to modify the backed up block producers.
// nextBlockProducers <- currentBlockProducers
nextBlockProducers = currentBlockProducers;
for (uint i = 0; i < nextBlockProducers.bpsLength; i++) {
nextBlockProducers.bps[i] = currentBlockProducers.bps[i];
}
// currentBlockProducers <- backupCurrentBlockProducers
currentBlockProducers = backupCurrentBlockProducers;
for (uint i = 0; i < currentBlockProducers.bpsLength; i++) {
currentBlockProducers.bps[i] = backupCurrentBlockProducers.bps[i];
}
}
// Finally we restore the head.
head = backupHead;
for (uint i = 0; i < head.approvals_after_next_length; i++) {
head.approvals_after_next[i] = backupHead.approvals_after_next[i];
}
lastValidAt = 0;
}
// The first part of initialization -- setting the validators of the current epoch.
Expand Down Expand Up @@ -182,7 +170,11 @@ contract NearBridge is INearBridge {
Borsh.Data memory borsh = Borsh.from(data);
NearDecoder.LightClientBlock memory nearBlock = borsh.decodeLightClientBlock();
require(borsh.finished(), "NearBridge: only light client block should be passed as first argument");
_setHead(nearBlock, data, true);
require(!nearBlock.next_bps.none, "NearBridge: The first block of the epoch should contain next_bps.");
setBlockInfo(nearBlock, head, nextBlockProducers);
blockHashes[head.height] = head.hash;
blockMerkleRoots[head.height] = head.merkleRoot;
}
function _checkBp(NearDecoder.LightClientBlock memory nearBlock, BlockProducerInfo storage bpInfo) internal {
Expand All @@ -200,15 +192,22 @@ contract NearBridge is INearBridge {
require(votedFor > bpInfo.totalStake.mul(2).div(3), "NearBridge: Less than 2/3 voted by the block after next");
}
function addLightClientBlock(bytes memory data) public payable {
function addLightClientBlock(bytes memory data) public {
require(initialized, "NearBridge: Contract is not initialized.");
require(balanceOf[msg.sender] >= lockEthAmount, "Balance is not enough");
require(block.timestamp >= head.validAfter, "Wait until last block become valid");
Borsh.Data memory borsh = Borsh.from(data);
NearDecoder.LightClientBlock memory nearBlock = borsh.decodeLightClientBlock();
require(borsh.finished(), "NearBridge: only light client block should be passed");
if (block.timestamp >= lastValidAt) {
if (lastValidAt != 0) {
commitBlock();
}
} else {
require(nearBlock.inner_lite.timestamp >= untrustedHead.timestamp.add(replaceDuration), "NearBridge: can only replace with a sufficiently newer block");
}
// 1. The height of the block is higher than the height of the current head
require(
nearBlock.inner_lite.height > head.height,
Expand Down Expand Up @@ -247,70 +246,73 @@ contract NearBridge is INearBridge {
);
}
_setHead(nearBlock, data, false);
setBlockInfo(nearBlock, untrustedHead, untrustedNextBlockProducers);
untrustedHeadIsFromNextEpoch = nearBlock.inner_lite.epoch_id == head.nextEpochId;
lastSubmitter = msg.sender;
lastValidAt = block.timestamp.add(lockDuration);
}
function _setHead(NearDecoder.LightClientBlock memory nearBlock, bytes memory data, bool init) internal {
// If block is from the next epoch or it is initialization then update block producers.
if (init || nearBlock.inner_lite.epoch_id == head.nextEpochId) {
// If block from the next epoch then it should contain next_bps.
require(!nearBlock.next_bps.none, "NearBridge: The first block of the epoch should contain next_bps.");
// If this is initialization then no need for the backup.
if (!init) {
// backupCurrentBlockProducers <- currentBlockProducers
backupCurrentBlockProducers = currentBlockProducers;
for (uint i = 0; i < backupCurrentBlockProducers.bpsLength; i++) {
backupCurrentBlockProducers.bps[i] = currentBlockProducers.bps[i];
}
// currentBlockProducers <- nextBlockProducers
currentBlockProducers = nextBlockProducers;
for (uint i = 0; i < currentBlockProducers.bpsLength; i++) {
currentBlockProducers.bps[i] = nextBlockProducers.bps[i];
}
}
// nextBlockProducers <- new block producers
nextBlockProducers.bpsLength = nearBlock.next_bps.validatorStakes.length;
uint256 totalStake = 0;
for (uint i = 0; i < nextBlockProducers.bpsLength; i++) {
nextBlockProducers.bps[i] = BlockProducer({
publicKey: nearBlock.next_bps.validatorStakes[i].public_key,
stake: nearBlock.next_bps.validatorStakes[i].stake
});
totalStake = totalStake.add(nearBlock.next_bps.validatorStakes[i].stake);
}
nextBlockProducers.totalStake = totalStake;
function setBlockInfo(
NearDecoder.LightClientBlock memory src,
BlockInfo storage destBlock,
BlockProducerInfo storage destBPs
)
internal
{
destBlock.height = src.inner_lite.height;
destBlock.timestamp = src.inner_lite.timestamp;
destBlock.epochId = src.inner_lite.epoch_id;
destBlock.nextEpochId = src.inner_lite.next_epoch_id;
destBlock.hash = src.hash;
destBlock.merkleRoot = src.inner_lite.block_merkle_root;
destBlock.next_hash = src.next_hash;
destBlock.approvals_after_next_length = src.approvals_after_next.length;
for (uint i = 0; i < src.approvals_after_next.length; i++) {
destBlock.approvals_after_next[i] = src.approvals_after_next[i];
}
if (!init) {
// Backup the head. No need to backup if it is initialization.
backupHead = head;
for (uint i = 0; i < head.approvals_after_next_length; i++) {
backupHead.approvals_after_next[i] = head.approvals_after_next[i];
if (src.next_bps.none) {
destBPs.bpsLength = 0;
destBPs.totalStake = 0;
} else {
destBPs.bpsLength = src.next_bps.validatorStakes.length;
uint256 totalStake = 0;
for (uint i = 0; i < src.next_bps.validatorStakes.length; i++) {
destBPs.bps[i] = BlockProducer({
publicKey: src.next_bps.validatorStakes[i].public_key,
stake: src.next_bps.validatorStakes[i].stake
});
totalStake = totalStake.add(src.next_bps.validatorStakes[i].stake);
}
destBPs.totalStake = totalStake;
}
// Update the head.
head = BlockInfo({
height: nearBlock.inner_lite.height,
epochId: nearBlock.inner_lite.epoch_id,
nextEpochId: nearBlock.inner_lite.next_epoch_id,
submitter: msg.sender,
validAfter: init ? 0 : block.timestamp.add(lockDuration),
hash: keccak256(data),
next_hash: nearBlock.next_hash,
approvals_after_next_length: nearBlock.approvals_after_next.length
});
for (uint i = 0; i < nearBlock.approvals_after_next.length; i++) {
head.approvals_after_next[i] = nearBlock.approvals_after_next[i];
emit BlockHashAdded(
src.inner_lite.height,
src.hash
);
}
function commitBlock() public {
require(lastValidAt != 0 && block.timestamp >= lastValidAt, "Nothing to commit");
head = untrustedHead;
if (untrustedHeadIsFromNextEpoch) {
copyBlockProducers(nextBlockProducers, currentBlockProducers);
copyBlockProducers(untrustedNextBlockProducers, nextBlockProducers);
}
lastValidAt = 0;
blockHashes[nearBlock.inner_lite.height] = nearBlock.hash;
blockMerkleRoots[nearBlock.inner_lite.height] = nearBlock.inner_lite.block_merkle_root;
blockHashes[head.height] = head.hash;
blockMerkleRoots[head.height] = head.merkleRoot;
}
emit BlockHashAdded(
nearBlock.inner_lite.height,
blockHashes[nearBlock.inner_lite.height]
);
function copyBlockProducers(BlockProducerInfo storage src, BlockProducerInfo storage dest) internal {
dest.bpsLength = src.bpsLength;
dest.totalStake = src.totalStake;
for (uint i = 0; i < src.bpsLength; i++) {
dest.bps[i] = src.bps[i];
}
}
function _checkValidatorSignature(
Expand Down
2 changes: 1 addition & 1 deletion nearbridge/dist/INearBridge.full.abi
View file
@@ -1 +1 @@
[{"anonymous":false,"inputs":[{"indexed":true,"internalType":"uint64","name":"height","type":"uint64"},{"indexed":false,"internalType":"bytes32","name":"blockHash","type":"bytes32"}],"name":"BlockHashAdded","type":"event"},{"anonymous":false,"inputs":[{"indexed":true,"internalType":"uint64","name":"height","type":"uint64"},{"indexed":false,"internalType":"bytes32","name":"blockHash","type":"bytes32"}],"name":"BlockHashReverted","type":"event"},{"constant":false,"inputs":[{"internalType":"bytes","name":"data","type":"bytes"}],"name":"addLightClientBlock","outputs":[],"payable":true,"stateMutability":"payable","type":"function"},{"constant":true,"inputs":[{"internalType":"address","name":"wallet","type":"address"}],"name":"balanceOf","outputs":[{"internalType":"uint256","name":"","type":"uint256"}],"payable":false,"stateMutability":"view","type":"function"},{"constant":true,"inputs":[{"internalType":"uint64","name":"blockNumber","type":"uint64"}],"name":"blockHashes","outputs":[{"internalType":"bytes32","name":"","type":"bytes32"}],"payable":false,"stateMutability":"view","type":"function"},{"constant":true,"inputs":[{"internalType":"uint64","name":"blockNumber","type":"uint64"}],"name":"blockMerkleRoots","outputs":[{"internalType":"bytes32","name":"","type":"bytes32"}],"payable":false,"stateMutability":"view","type":"function"},{"constant":false,"inputs":[{"internalType":"address payable","name":"receiver","type":"address"},{"internalType":"uint256","name":"signatureIndex","type":"uint256"}],"name":"challenge","outputs":[],"payable":false,"stateMutability":"nonpayable","type":"function"},{"constant":true,"inputs":[{"internalType":"uint256","name":"signatureIndex","type":"uint256"}],"name":"checkBlockProducerSignatureInHead","outputs":[{"internalType":"bool","name":"","type":"bool"}],"payable":false,"stateMutability":"view","type":"function"},{"constant":false,"inputs":[],"name":"deposit","outputs":[],"payable":true,"stateMutability":"payable","type":"function"},{"constant":false,"inputs":[{"internalType":"bytes","name":"data","type":"bytes"}],"name":"initWithBlock","outputs":[],"payable":false,"stateMutability":"nonpayable","type":"function"},{"constant":false,"inputs":[{"internalType":"bytes","name":"initialValidators","type":"bytes"}],"name":"initWithValidators","outputs":[],"payable":false,"stateMutability":"nonpayable","type":"function"},{"constant":false,"inputs":[],"name":"withdraw","outputs":[],"payable":false,"stateMutability":"nonpayable","type":"function"}]
[{"anonymous":false,"inputs":[{"indexed":true,"internalType":"uint64","name":"height","type":"uint64"},{"indexed":false,"internalType":"bytes32","name":"blockHash","type":"bytes32"}],"name":"BlockHashAdded","type":"event"},{"anonymous":false,"inputs":[{"indexed":true,"internalType":"uint64","name":"height","type":"uint64"},{"indexed":false,"internalType":"bytes32","name":"blockHash","type":"bytes32"}],"name":"BlockHashReverted","type":"event"},{"constant":false,"inputs":[{"internalType":"bytes","name":"data","type":"bytes"}],"name":"addLightClientBlock","outputs":[],"payable":false,"stateMutability":"nonpayable","type":"function"},{"constant":true,"inputs":[{"internalType":"address","name":"wallet","type":"address"}],"name":"balanceOf","outputs":[{"internalType":"uint256","name":"","type":"uint256"}],"payable":false,"stateMutability":"view","type":"function"},{"constant":true,"inputs":[{"internalType":"uint64","name":"blockNumber","type":"uint64"}],"name":"blockHashes","outputs":[{"internalType":"bytes32","name":"","type":"bytes32"}],"payable":false,"stateMutability":"view","type":"function"},{"constant":true,"inputs":[{"internalType":"uint64","name":"blockNumber","type":"uint64"}],"name":"blockMerkleRoots","outputs":[{"internalType":"bytes32","name":"","type":"bytes32"}],"payable":false,"stateMutability":"view","type":"function"},{"constant":false,"inputs":[{"internalType":"address payable","name":"receiver","type":"address"},{"internalType":"uint256","name":"signatureIndex","type":"uint256"}],"name":"challenge","outputs":[],"payable":false,"stateMutability":"nonpayable","type":"function"},{"constant":true,"inputs":[{"internalType":"uint256","name":"signatureIndex","type":"uint256"}],"name":"checkBlockProducerSignatureInHead","outputs":[{"internalType":"bool","name":"","type":"bool"}],"payable":false,"stateMutability":"view","type":"function"},{"constant":false,"inputs":[],"name":"deposit","outputs":[],"payable":true,"stateMutability":"payable","type":"function"},{"constant":false,"inputs":[{"internalType":"bytes","name":"data","type":"bytes"}],"name":"initWithBlock","outputs":[],"payable":false,"stateMutability":"nonpayable","type":"function"},{"constant":false,"inputs":[{"internalType":"bytes","name":"initialValidators","type":"bytes"}],"name":"initWithValidators","outputs":[],"payable":false,"stateMutability":"nonpayable","type":"function"},{"constant":false,"inputs":[],"name":"withdraw","outputs":[],"payable":false,"stateMutability":"nonpayable","type":"function"}]
2 changes: 1 addition & 1 deletion nearbridge/dist/INearBridge.full.sol
View file
Expand Up @@ -24,7 +24,7 @@ interface INearBridge {

function initWithValidators(bytes calldata initialValidators) external;
function initWithBlock(bytes calldata data) external;
function addLightClientBlock(bytes calldata data) external payable;
function addLightClientBlock(bytes calldata data) external;
function challenge(address payable receiver, uint256 signatureIndex) external;
function checkBlockProducerSignatureInHead(uint256 signatureIndex) external view returns(bool);
}

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