forked from ChainSafe/ChainBridge
/
listener.go
217 lines (187 loc) 路 6.95 KB
/
listener.go
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// Copyright 2020 ChainSafe Systems
// SPDX-License-Identifier: LGPL-3.0-only
package ethereum
import (
"context"
"errors"
"fmt"
"math/big"
"time"
"github.com/PolkaFoundry/ChainBridge/bindings/Bridge"
"github.com/PolkaFoundry/ChainBridge/bindings/ERC20Handler"
"github.com/PolkaFoundry/ChainBridge/bindings/ERC721Handler"
"github.com/PolkaFoundry/ChainBridge/bindings/GenericHandler"
"github.com/PolkaFoundry/ChainBridge/chains"
utils "github.com/PolkaFoundry/ChainBridge/shared/ethereum"
"github.com/PolkaFoundry/chainbridge-utils/blockstore"
metrics "github.com/PolkaFoundry/chainbridge-utils/metrics/types"
"github.com/PolkaFoundry/chainbridge-utils/msg"
"github.com/ChainSafe/log15"
eth "github.com/ethereum/go-ethereum"
"github.com/ethereum/go-ethereum/accounts/abi/bind"
ethcommon "github.com/ethereum/go-ethereum/common"
)
var BlockRetryInterval = time.Second * 5
var BlockRetryLimit = 5
var ErrFatalPolling = errors.New("listener block polling failed")
type listener struct {
cfg Config
conn Connection
router chains.Router
bridgeContract *Bridge.Bridge // instance of bound bridge contract
erc20HandlerContract *ERC20Handler.ERC20Handler
erc721HandlerContract *ERC721Handler.ERC721Handler
genericHandlerContract *GenericHandler.GenericHandler
log log15.Logger
blockstore blockstore.Blockstorer
stop <-chan int
sysErr chan<- error // Reports fatal error to core
latestBlock metrics.LatestBlock
metrics *metrics.ChainMetrics
blockConfirmations *big.Int
}
// NewListener creates and returns a listener
func NewListener(conn Connection, cfg *Config, log log15.Logger, bs blockstore.Blockstorer, stop <-chan int, sysErr chan<- error, m *metrics.ChainMetrics) *listener {
return &listener{
cfg: *cfg,
conn: conn,
log: log,
blockstore: bs,
stop: stop,
sysErr: sysErr,
latestBlock: metrics.LatestBlock{LastUpdated: time.Now()},
metrics: m,
blockConfirmations: cfg.blockConfirmations,
}
}
// setContracts sets the listener with the appropriate contracts
func (l *listener) setContracts(bridge *Bridge.Bridge, erc20Handler *ERC20Handler.ERC20Handler, erc721Handler *ERC721Handler.ERC721Handler, genericHandler *GenericHandler.GenericHandler) {
l.bridgeContract = bridge
l.erc20HandlerContract = erc20Handler
l.erc721HandlerContract = erc721Handler
l.genericHandlerContract = genericHandler
}
// sets the router
func (l *listener) setRouter(r chains.Router) {
l.router = r
}
// start registers all subscriptions provided by the config
func (l *listener) start() error {
l.log.Debug("Starting listener...")
go func() {
err := l.pollBlocks()
if err != nil {
l.log.Error("Polling blocks failed", "err", err)
}
}()
return nil
}
// pollBlocks will poll for the latest block and proceed to parse the associated events as it sees new blocks.
// Polling begins at the block defined in `l.cfg.startBlock`. Failed attempts to fetch the latest block or parse
// a block will be retried up to BlockRetryLimit times before continuing to the next block.
func (l *listener) pollBlocks() error {
var currentBlock = l.cfg.startBlock
l.log.Info("Polling Blocks...", "block", currentBlock)
var retry = BlockRetryLimit
for {
select {
case <-l.stop:
return errors.New("polling terminated")
default:
// No more retries, goto next block
if retry == 0 {
l.log.Error("Polling failed, retries exceeded")
l.sysErr <- ErrFatalPolling
return nil
}
latestBlock, err := l.conn.LatestBlock()
if err != nil {
l.log.Error("Unable to get latest block", "block", currentBlock, "err", err)
retry--
time.Sleep(BlockRetryInterval)
continue
}
if l.metrics != nil {
l.metrics.LatestKnownBlock.Set(float64(latestBlock.Int64()))
}
// Sleep if the difference is less than BlockDelay; (latest - current) < BlockDelay
if big.NewInt(0).Sub(latestBlock, currentBlock).Cmp(l.blockConfirmations) == -1 {
l.log.Debug("Block not ready, will retry", "target", currentBlock, "latest", latestBlock)
time.Sleep(BlockRetryInterval)
continue
}
// Parse out events
err = l.getDepositEventsForBlock(currentBlock)
if err != nil {
l.log.Error("Failed to get events for block", "block", currentBlock, "err", err)
retry--
continue
}
// Write to block store. Not a critical operation, no need to retry
err = l.blockstore.StoreBlock(currentBlock)
if err != nil {
l.log.Error("Failed to write latest block to blockstore", "block", currentBlock, "err", err)
}
if l.metrics != nil {
l.metrics.BlocksProcessed.Inc()
l.metrics.LatestProcessedBlock.Set(float64(latestBlock.Int64()))
}
l.latestBlock.Height = big.NewInt(0).Set(latestBlock)
l.latestBlock.LastUpdated = time.Now()
// Goto next block and reset retry counter
currentBlock.Add(currentBlock, big.NewInt(1))
retry = BlockRetryLimit
}
}
}
// getDepositEventsForBlock looks for the deposit event in the latest block
func (l *listener) getDepositEventsForBlock(latestBlock *big.Int) error {
l.log.Debug("Querying block for deposit events", "block", latestBlock)
query := buildQuery(l.cfg.bridgeContract, utils.Deposit, latestBlock, latestBlock)
// querying for logs
logs, err := l.conn.Client().FilterLogs(context.Background(), query)
if err != nil {
return fmt.Errorf("unable to Filter Logs: %w", err)
}
// read through the log events and handle their deposit event if handler is recognized
for _, log := range logs {
var m msg.Message
destId := msg.ChainId(log.Topics[1].Big().Uint64())
rId := msg.ResourceIdFromSlice(log.Topics[2].Bytes())
nonce := msg.Nonce(log.Topics[3].Big().Uint64())
addr, err := l.bridgeContract.ResourceIDToHandlerAddress(&bind.CallOpts{From: l.conn.Keypair().CommonAddress()}, rId)
if err != nil {
return fmt.Errorf("failed to get handler from resource ID %x", rId)
}
if addr == l.cfg.erc20HandlerContract {
m, err = l.handleErc20DepositedEvent(destId, nonce)
} else if addr == l.cfg.erc721HandlerContract {
m, err = l.handleErc721DepositedEvent(destId, nonce)
} else if addr == l.cfg.genericHandlerContract {
m, err = l.handleGenericDepositedEvent(destId, nonce)
} else {
l.log.Error("event has unrecognized handler", "handler", addr.Hex())
return nil
}
if err != nil {
return err
}
err = l.router.Send(m)
if err != nil {
l.log.Error("subscription error: failed to route message", "err", err)
}
}
return nil
}
// buildQuery constructs a query for the bridgeContract by hashing sig to get the event topic
func buildQuery(contract ethcommon.Address, sig utils.EventSig, startBlock *big.Int, endBlock *big.Int) eth.FilterQuery {
query := eth.FilterQuery{
FromBlock: startBlock,
ToBlock: endBlock,
Addresses: []ethcommon.Address{contract},
Topics: [][]ethcommon.Hash{
{sig.GetTopic()},
},
}
return query
}