e0e5f74776
TestMadeupParentBlockChainAttack has been deleted because it was too hard to port and the attack that it checks the prevention of is being averted in a different way (through a protocol change).
488 lines
17 KiB
Go
488 lines
17 KiB
Go
package fetcher
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import (
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"errors"
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"math/big"
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"sync"
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"sync/atomic"
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"testing"
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"time"
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"github.com/ethereum/go-ethereum/common"
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"github.com/ethereum/go-ethereum/core"
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"github.com/ethereum/go-ethereum/core/types"
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"github.com/ethereum/go-ethereum/ethdb"
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)
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var (
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testdb, _ = ethdb.NewMemDatabase()
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genesis = core.GenesisBlockForTesting(testdb, common.Address{}, big.NewInt(0))
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unknownBlock = types.NewBlock(&types.Header{}, nil, nil, nil)
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)
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// makeChain creates a chain of n blocks starting at and including parent.
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// the returned hash chain is ordered head->parent.
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func makeChain(n int, seed byte, parent *types.Block) ([]common.Hash, map[common.Hash]*types.Block) {
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blocks := core.GenerateChain(parent, testdb, n, func(i int, gen *core.BlockGen) {
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gen.SetCoinbase(common.Address{seed})
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})
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hashes := make([]common.Hash, n+1)
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hashes[len(hashes)-1] = parent.Hash()
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blockm := make(map[common.Hash]*types.Block, n+1)
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blockm[parent.Hash()] = parent
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for i, b := range blocks {
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hashes[len(hashes)-i-2] = b.Hash()
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blockm[b.Hash()] = b
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}
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return hashes, blockm
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}
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// fetcherTester is a test simulator for mocking out local block chain.
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type fetcherTester struct {
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fetcher *Fetcher
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hashes []common.Hash // Hash chain belonging to the tester
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blocks map[common.Hash]*types.Block // Blocks belonging to the tester
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lock sync.RWMutex
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}
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// newTester creates a new fetcher test mocker.
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func newTester() *fetcherTester {
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tester := &fetcherTester{
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hashes: []common.Hash{genesis.Hash()},
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blocks: map[common.Hash]*types.Block{genesis.Hash(): genesis},
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}
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tester.fetcher = New(tester.getBlock, tester.verifyBlock, tester.broadcastBlock, tester.chainHeight, tester.insertChain, tester.dropPeer)
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tester.fetcher.Start()
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return tester
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}
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// getBlock retrieves a block from the tester's block chain.
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func (f *fetcherTester) getBlock(hash common.Hash) *types.Block {
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f.lock.RLock()
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defer f.lock.RUnlock()
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return f.blocks[hash]
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}
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// verifyBlock is a nop placeholder for the block header verification.
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func (f *fetcherTester) verifyBlock(block *types.Block, parent *types.Block) error {
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return nil
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}
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// broadcastBlock is a nop placeholder for the block broadcasting.
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func (f *fetcherTester) broadcastBlock(block *types.Block, propagate bool) {
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}
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// chainHeight retrieves the current height (block number) of the chain.
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func (f *fetcherTester) chainHeight() uint64 {
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f.lock.RLock()
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defer f.lock.RUnlock()
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return f.blocks[f.hashes[len(f.hashes)-1]].NumberU64()
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}
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// insertChain injects a new blocks into the simulated chain.
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func (f *fetcherTester) insertChain(blocks types.Blocks) (int, error) {
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f.lock.Lock()
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defer f.lock.Unlock()
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for i, block := range blocks {
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// Make sure the parent in known
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if _, ok := f.blocks[block.ParentHash()]; !ok {
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return i, errors.New("unknown parent")
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}
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// Discard any new blocks if the same height already exists
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if block.NumberU64() <= f.blocks[f.hashes[len(f.hashes)-1]].NumberU64() {
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return i, nil
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}
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// Otherwise build our current chain
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f.hashes = append(f.hashes, block.Hash())
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f.blocks[block.Hash()] = block
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}
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return 0, nil
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}
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// dropPeer is a nop placeholder for the peer removal.
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func (f *fetcherTester) dropPeer(peer string) {
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}
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// peerFetcher retrieves a fetcher associated with a simulated peer.
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func (f *fetcherTester) makeFetcher(blocks map[common.Hash]*types.Block) blockRequesterFn {
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closure := make(map[common.Hash]*types.Block)
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for hash, block := range blocks {
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closure[hash] = block
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}
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// Create a function that returns blocks from the closure
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return func(hashes []common.Hash) error {
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// Gather the blocks to return
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blocks := make([]*types.Block, 0, len(hashes))
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for _, hash := range hashes {
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if block, ok := closure[hash]; ok {
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blocks = append(blocks, block)
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}
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}
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// Return on a new thread
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go f.fetcher.Filter(blocks)
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return nil
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}
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}
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// verifyImportEvent verifies that one single event arrive on an import channel.
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func verifyImportEvent(t *testing.T, imported chan *types.Block) {
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select {
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case <-imported:
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case <-time.After(time.Second):
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t.Fatalf("import timeout")
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}
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}
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// verifyImportCount verifies that exactly count number of events arrive on an
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// import hook channel.
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func verifyImportCount(t *testing.T, imported chan *types.Block, count int) {
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for i := 0; i < count; i++ {
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select {
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case <-imported:
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case <-time.After(time.Second):
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t.Fatalf("block %d: import timeout", i)
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}
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}
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verifyImportDone(t, imported)
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}
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// verifyImportDone verifies that no more events are arriving on an import channel.
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func verifyImportDone(t *testing.T, imported chan *types.Block) {
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select {
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case <-imported:
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t.Fatalf("extra block imported")
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case <-time.After(50 * time.Millisecond):
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}
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}
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// Tests that a fetcher accepts block announcements and initiates retrievals for
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// them, successfully importing into the local chain.
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func TestSequentialAnnouncements(t *testing.T) {
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// Create a chain of blocks to import
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targetBlocks := 4 * hashLimit
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hashes, blocks := makeChain(targetBlocks, 0, genesis)
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tester := newTester()
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fetcher := tester.makeFetcher(blocks)
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// Iteratively announce blocks until all are imported
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imported := make(chan *types.Block)
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tester.fetcher.importedHook = func(block *types.Block) { imported <- block }
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for i := len(hashes) - 2; i >= 0; i-- {
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tester.fetcher.Notify("valid", hashes[i], time.Now().Add(-arriveTimeout), fetcher)
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verifyImportEvent(t, imported)
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}
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verifyImportDone(t, imported)
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}
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// Tests that if blocks are announced by multiple peers (or even the same buggy
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// peer), they will only get downloaded at most once.
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func TestConcurrentAnnouncements(t *testing.T) {
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// Create a chain of blocks to import
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targetBlocks := 4 * hashLimit
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hashes, blocks := makeChain(targetBlocks, 0, genesis)
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// Assemble a tester with a built in counter for the requests
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tester := newTester()
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fetcher := tester.makeFetcher(blocks)
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counter := uint32(0)
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wrapper := func(hashes []common.Hash) error {
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atomic.AddUint32(&counter, uint32(len(hashes)))
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return fetcher(hashes)
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}
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// Iteratively announce blocks until all are imported
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imported := make(chan *types.Block)
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tester.fetcher.importedHook = func(block *types.Block) { imported <- block }
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for i := len(hashes) - 2; i >= 0; i-- {
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tester.fetcher.Notify("first", hashes[i], time.Now().Add(-arriveTimeout), wrapper)
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tester.fetcher.Notify("second", hashes[i], time.Now().Add(-arriveTimeout+time.Millisecond), wrapper)
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tester.fetcher.Notify("second", hashes[i], time.Now().Add(-arriveTimeout-time.Millisecond), wrapper)
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verifyImportEvent(t, imported)
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}
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verifyImportDone(t, imported)
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// Make sure no blocks were retrieved twice
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if int(counter) != targetBlocks {
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t.Fatalf("retrieval count mismatch: have %v, want %v", counter, targetBlocks)
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}
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}
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// Tests that announcements arriving while a previous is being fetched still
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// results in a valid import.
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func TestOverlappingAnnouncements(t *testing.T) {
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// Create a chain of blocks to import
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targetBlocks := 4 * hashLimit
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hashes, blocks := makeChain(targetBlocks, 0, genesis)
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tester := newTester()
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fetcher := tester.makeFetcher(blocks)
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// Iteratively announce blocks, but overlap them continuously
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fetching := make(chan []common.Hash)
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imported := make(chan *types.Block, len(hashes)-1)
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tester.fetcher.fetchingHook = func(hashes []common.Hash) { fetching <- hashes }
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tester.fetcher.importedHook = func(block *types.Block) { imported <- block }
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for i := len(hashes) - 2; i >= 0; i-- {
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tester.fetcher.Notify("valid", hashes[i], time.Now().Add(-arriveTimeout), fetcher)
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select {
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case <-fetching:
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case <-time.After(time.Second):
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t.Fatalf("hash %d: announce timeout", len(hashes)-i)
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}
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}
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// Wait for all the imports to complete and check count
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verifyImportCount(t, imported, len(hashes)-1)
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}
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// Tests that announces already being retrieved will not be duplicated.
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func TestPendingDeduplication(t *testing.T) {
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// Create a hash and corresponding block
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hashes, blocks := makeChain(1, 0, genesis)
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// Assemble a tester with a built in counter and delayed fetcher
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tester := newTester()
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fetcher := tester.makeFetcher(blocks)
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delay := 50 * time.Millisecond
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counter := uint32(0)
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wrapper := func(hashes []common.Hash) error {
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atomic.AddUint32(&counter, uint32(len(hashes)))
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// Simulate a long running fetch
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go func() {
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time.Sleep(delay)
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fetcher(hashes)
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}()
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return nil
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}
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// Announce the same block many times until it's fetched (wait for any pending ops)
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for tester.getBlock(hashes[0]) == nil {
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tester.fetcher.Notify("repeater", hashes[0], time.Now().Add(-arriveTimeout), wrapper)
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time.Sleep(time.Millisecond)
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}
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time.Sleep(delay)
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// Check that all blocks were imported and none fetched twice
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if imported := len(tester.blocks); imported != 2 {
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t.Fatalf("synchronised block mismatch: have %v, want %v", imported, 2)
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}
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if int(counter) != 1 {
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t.Fatalf("retrieval count mismatch: have %v, want %v", counter, 1)
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}
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}
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// Tests that announcements retrieved in a random order are cached and eventually
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// imported when all the gaps are filled in.
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func TestRandomArrivalImport(t *testing.T) {
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// Create a chain of blocks to import, and choose one to delay
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targetBlocks := maxQueueDist
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hashes, blocks := makeChain(targetBlocks, 0, genesis)
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skip := targetBlocks / 2
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tester := newTester()
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fetcher := tester.makeFetcher(blocks)
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// Iteratively announce blocks, skipping one entry
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imported := make(chan *types.Block, len(hashes)-1)
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tester.fetcher.importedHook = func(block *types.Block) { imported <- block }
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for i := len(hashes) - 1; i >= 0; i-- {
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if i != skip {
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tester.fetcher.Notify("valid", hashes[i], time.Now().Add(-arriveTimeout), fetcher)
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time.Sleep(time.Millisecond)
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}
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}
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// Finally announce the skipped entry and check full import
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tester.fetcher.Notify("valid", hashes[skip], time.Now().Add(-arriveTimeout), fetcher)
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verifyImportCount(t, imported, len(hashes)-1)
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}
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// Tests that direct block enqueues (due to block propagation vs. hash announce)
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// are correctly schedule, filling and import queue gaps.
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func TestQueueGapFill(t *testing.T) {
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// Create a chain of blocks to import, and choose one to not announce at all
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targetBlocks := maxQueueDist
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hashes, blocks := makeChain(targetBlocks, 0, genesis)
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skip := targetBlocks / 2
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tester := newTester()
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fetcher := tester.makeFetcher(blocks)
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// Iteratively announce blocks, skipping one entry
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imported := make(chan *types.Block, len(hashes)-1)
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tester.fetcher.importedHook = func(block *types.Block) { imported <- block }
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for i := len(hashes) - 1; i >= 0; i-- {
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if i != skip {
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tester.fetcher.Notify("valid", hashes[i], time.Now().Add(-arriveTimeout), fetcher)
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time.Sleep(time.Millisecond)
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}
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}
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// Fill the missing block directly as if propagated
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tester.fetcher.Enqueue("valid", blocks[hashes[skip]])
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verifyImportCount(t, imported, len(hashes)-1)
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}
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// Tests that blocks arriving from various sources (multiple propagations, hash
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// announces, etc) do not get scheduled for import multiple times.
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func TestImportDeduplication(t *testing.T) {
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// Create two blocks to import (one for duplication, the other for stalling)
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hashes, blocks := makeChain(2, 0, genesis)
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// Create the tester and wrap the importer with a counter
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tester := newTester()
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fetcher := tester.makeFetcher(blocks)
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counter := uint32(0)
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tester.fetcher.insertChain = func(blocks types.Blocks) (int, error) {
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atomic.AddUint32(&counter, uint32(len(blocks)))
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return tester.insertChain(blocks)
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}
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// Instrument the fetching and imported events
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fetching := make(chan []common.Hash)
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imported := make(chan *types.Block, len(hashes)-1)
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tester.fetcher.fetchingHook = func(hashes []common.Hash) { fetching <- hashes }
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tester.fetcher.importedHook = func(block *types.Block) { imported <- block }
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// Announce the duplicating block, wait for retrieval, and also propagate directly
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tester.fetcher.Notify("valid", hashes[0], time.Now().Add(-arriveTimeout), fetcher)
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<-fetching
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tester.fetcher.Enqueue("valid", blocks[hashes[0]])
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tester.fetcher.Enqueue("valid", blocks[hashes[0]])
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tester.fetcher.Enqueue("valid", blocks[hashes[0]])
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// Fill the missing block directly as if propagated, and check import uniqueness
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tester.fetcher.Enqueue("valid", blocks[hashes[1]])
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verifyImportCount(t, imported, 2)
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if counter != 2 {
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t.Fatalf("import invocation count mismatch: have %v, want %v", counter, 2)
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}
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}
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// Tests that blocks with numbers much lower or higher than out current head get
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// discarded no prevent wasting resources on useless blocks from faulty peers.
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func TestDistantDiscarding(t *testing.T) {
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// Create a long chain to import
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hashes, blocks := makeChain(3*maxQueueDist, 0, genesis)
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head := hashes[len(hashes)/2]
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// Create a tester and simulate a head block being the middle of the above chain
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tester := newTester()
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tester.hashes = []common.Hash{head}
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tester.blocks = map[common.Hash]*types.Block{head: blocks[head]}
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// Ensure that a block with a lower number than the threshold is discarded
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tester.fetcher.Enqueue("lower", blocks[hashes[0]])
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time.Sleep(10 * time.Millisecond)
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if !tester.fetcher.queue.Empty() {
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t.Fatalf("fetcher queued stale block")
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}
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// Ensure that a block with a higher number than the threshold is discarded
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tester.fetcher.Enqueue("higher", blocks[hashes[len(hashes)-1]])
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time.Sleep(10 * time.Millisecond)
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if !tester.fetcher.queue.Empty() {
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t.Fatalf("fetcher queued future block")
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}
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}
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// Tests that a peer is unable to use unbounded memory with sending infinite
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// block announcements to a node, but that even in the face of such an attack,
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// the fetcher remains operational.
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func TestHashMemoryExhaustionAttack(t *testing.T) {
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// Create a tester with instrumented import hooks
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tester := newTester()
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imported := make(chan *types.Block)
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tester.fetcher.importedHook = func(block *types.Block) { imported <- block }
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// Create a valid chain and an infinite junk chain
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targetBlocks := hashLimit + 2*maxQueueDist
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hashes, blocks := makeChain(targetBlocks, 0, genesis)
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valid := tester.makeFetcher(blocks)
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attack, _ := makeChain(targetBlocks, 0, unknownBlock)
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attacker := tester.makeFetcher(nil)
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// Feed the tester a huge hashset from the attacker, and a limited from the valid peer
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for i := 0; i < len(attack); i++ {
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if i < maxQueueDist {
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tester.fetcher.Notify("valid", hashes[len(hashes)-2-i], time.Now(), valid)
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}
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tester.fetcher.Notify("attacker", attack[i], time.Now(), attacker)
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}
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if len(tester.fetcher.announced) != hashLimit+maxQueueDist {
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t.Fatalf("queued announce count mismatch: have %d, want %d", len(tester.fetcher.announced), hashLimit+maxQueueDist)
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}
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// Wait for fetches to complete
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verifyImportCount(t, imported, maxQueueDist)
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// Feed the remaining valid hashes to ensure DOS protection state remains clean
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for i := len(hashes) - maxQueueDist - 2; i >= 0; i-- {
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tester.fetcher.Notify("valid", hashes[i], time.Now().Add(-arriveTimeout), valid)
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verifyImportEvent(t, imported)
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}
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verifyImportDone(t, imported)
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}
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// Tests that blocks sent to the fetcher (either through propagation or via hash
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// announces and retrievals) don't pile up indefinitely, exhausting available
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// system memory.
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func TestBlockMemoryExhaustionAttack(t *testing.T) {
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// Create a tester with instrumented import hooks
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tester := newTester()
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imported := make(chan *types.Block)
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tester.fetcher.importedHook = func(block *types.Block) { imported <- block }
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// Create a valid chain and a batch of dangling (but in range) blocks
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targetBlocks := hashLimit + 2*maxQueueDist
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hashes, blocks := makeChain(targetBlocks, 0, genesis)
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attack := make(map[common.Hash]*types.Block)
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for i := byte(0); len(attack) < blockLimit+2*maxQueueDist; i++ {
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hashes, blocks := makeChain(maxQueueDist-1, i, unknownBlock)
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for _, hash := range hashes[:maxQueueDist-2] {
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attack[hash] = blocks[hash]
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}
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}
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// Try to feed all the attacker blocks make sure only a limited batch is accepted
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for _, block := range attack {
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tester.fetcher.Enqueue("attacker", block)
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}
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time.Sleep(200 * time.Millisecond)
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if queued := tester.fetcher.queue.Size(); queued != blockLimit {
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t.Fatalf("queued block count mismatch: have %d, want %d", queued, blockLimit)
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}
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// Queue up a batch of valid blocks, and check that a new peer is allowed to do so
|
|
for i := 0; i < maxQueueDist-1; i++ {
|
|
tester.fetcher.Enqueue("valid", blocks[hashes[len(hashes)-3-i]])
|
|
}
|
|
time.Sleep(100 * time.Millisecond)
|
|
if queued := tester.fetcher.queue.Size(); queued != blockLimit+maxQueueDist-1 {
|
|
t.Fatalf("queued block count mismatch: have %d, want %d", queued, blockLimit+maxQueueDist-1)
|
|
}
|
|
// Insert the missing piece (and sanity check the import)
|
|
tester.fetcher.Enqueue("valid", blocks[hashes[len(hashes)-2]])
|
|
verifyImportCount(t, imported, maxQueueDist)
|
|
|
|
// Insert the remaining blocks in chunks to ensure clean DOS protection
|
|
for i := maxQueueDist; i < len(hashes)-1; i++ {
|
|
tester.fetcher.Enqueue("valid", blocks[hashes[len(hashes)-2-i]])
|
|
verifyImportEvent(t, imported)
|
|
}
|
|
verifyImportDone(t, imported)
|
|
}
|