// Copyright 2015 The go-ethereum Authors
// This file is part of go-ethereum.
//
// go-ethereum is free software: you can redistribute it and/or modify
// it under the terms of the GNU Lesser General Public License as published by
// the Free Software Foundation, either version 3 of the License, or
// (at your option) any later version.
//
// go-ethereum is distributed in the hope that it will be useful,
// but WITHOUT ANY WARRANTY; without even the implied warranty of
// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
// GNU Lesser General Public License for more details.
//
// You should have received a copy of the GNU Lesser General Public License
// along with go-ethereum. If not, see <http://www.gnu.org/licenses/>.
package fetcher
import (
"errors"
"math/big"
"sync"
"sync/atomic"
"testing"
"time"
"github.com/ethereum/go-ethereum/common"
"github.com/ethereum/go-ethereum/core"
"github.com/ethereum/go-ethereum/core/types"
"github.com/ethereum/go-ethereum/ethdb"
)
var (
testdb, _ = ethdb.NewMemDatabase()
genesis = core.GenesisBlockForTesting(testdb, common.Address{}, big.NewInt(0))
unknownBlock = types.NewBlock(&types.Header{}, nil, nil, nil)
)
// makeChain creates a chain of n blocks starting at and including parent.
// the returned hash chain is ordered head->parent.
func makeChain(n int, seed byte, parent *types.Block) ([]common.Hash, map[common.Hash]*types.Block) {
blocks := core.GenerateChain(parent, testdb, n, func(i int, gen *core.BlockGen) {
gen.SetCoinbase(common.Address{seed})
})
hashes := make([]common.Hash, n+1)
hashes[len(hashes)-1] = parent.Hash()
blockm := make(map[common.Hash]*types.Block, n+1)
blockm[parent.Hash()] = parent
for i, b := range blocks {
hashes[len(hashes)-i-2] = b.Hash()
blockm[b.Hash()] = b
}
return hashes, blockm
}
// fetcherTester is a test simulator for mocking out local block chain.
type fetcherTester struct {
fetcher *Fetcher
hashes []common.Hash // Hash chain belonging to the tester
blocks map[common.Hash]*types.Block // Blocks belonging to the tester
lock sync.RWMutex
}
// newTester creates a new fetcher test mocker.
func newTester() *fetcherTester {
tester := &fetcherTester{
hashes: []common.Hash{genesis.Hash()},
blocks: map[common.Hash]*types.Block{genesis.Hash(): genesis},
}
tester.fetcher = New(tester.getBlock, tester.verifyBlock, tester.broadcastBlock, tester.chainHeight, tester.insertChain, tester.dropPeer)
tester.fetcher.Start()
return tester
}
// getBlock retrieves a block from the tester's block chain.
func (f *fetcherTester) getBlock(hash common.Hash) *types.Block {
f.lock.RLock()
defer f.lock.RUnlock()
return f.blocks[hash]
}
// verifyBlock is a nop placeholder for the block header verification.
func (f *fetcherTester) verifyBlock(block *types.Block, parent *types.Block) error {
return nil
}
// broadcastBlock is a nop placeholder for the block broadcasting.
func (f *fetcherTester) broadcastBlock(block *types.Block, propagate bool) {
}
// chainHeight retrieves the current height (block number) of the chain.
func (f *fetcherTester) chainHeight() uint64 {
f.lock.RLock()
defer f.lock.RUnlock()
return f.blocks[f.hashes[len(f.hashes)-1]].NumberU64()
}
// insertChain injects a new blocks into the simulated chain.
func (f *fetcherTester) insertChain(blocks types.Blocks) (int, error) {
f.lock.Lock()
defer f.lock.Unlock()
for i, block := range blocks {
// Make sure the parent in known
if _, ok := f.blocks[block.ParentHash()]; !ok {
return i, errors.New("unknown parent")
}
// Discard any new blocks if the same height already exists
if block.NumberU64() <= f.blocks[f.hashes[len(f.hashes)-1]].NumberU64() {
return i, nil
}
// Otherwise build our current chain
f.hashes = append(f.hashes, block.Hash())
f.blocks[block.Hash()] = block
}
return 0, nil
}
// dropPeer is a nop placeholder for the peer removal.
func (f *fetcherTester) dropPeer(peer string) {
}
// peerFetcher retrieves a fetcher associated with a simulated peer.
func (f *fetcherTester) makeFetcher(blocks map[common.Hash]*types.Block) blockRequesterFn {
closure := make(map[common.Hash]*types.Block)
for hash, block := range blocks {
closure[hash] = block
}
// Create a function that returns blocks from the closure
return func(hashes []common.Hash) error {
// Gather the blocks to return
blocks := make([]*types.Block, 0, len(hashes))
for _, hash := range hashes {
if block, ok := closure[hash]; ok {
blocks = append(blocks, block)
}
}
// Return on a new thread
go f.fetcher.Filter(blocks)
return nil
}
}
// verifyImportEvent verifies that one single event arrive on an import channel.
func verifyImportEvent(t *testing.T, imported chan *types.Block) {
select {
case <-imported:
case <-time.After(time.Second):
t.Fatalf("import timeout")
}
}
// verifyImportCount verifies that exactly count number of events arrive on an
// import hook channel.
func verifyImportCount(t *testing.T, imported chan *types.Block, count int) {
for i := 0; i < count; i++ {
select {
case <-imported:
case <-time.After(time.Second):
t.Fatalf("block %d: import timeout", i)
}
}
verifyImportDone(t, imported)
}
// verifyImportDone verifies that no more events are arriving on an import channel.
func verifyImportDone(t *testing.T, imported chan *types.Block) {
select {
case <-imported:
t.Fatalf("extra block imported")
case <-time.After(50 * time.Millisecond):
}
}
// Tests that a fetcher accepts block announcements and initiates retrievals for
// them, successfully importing into the local chain.
func TestSequentialAnnouncements(t *testing.T) {
// Create a chain of blocks to import
targetBlocks := 4 * hashLimit
hashes, blocks := makeChain(targetBlocks, 0, genesis)
tester := newTester()
fetcher := tester.makeFetcher(blocks)
// Iteratively announce blocks until all are imported
imported := make(chan *types.Block)
tester.fetcher.importedHook = func(block *types.Block) { imported <- block }
for i := len(hashes) - 2; i >= 0; i-- {
tester.fetcher.Notify("valid", hashes[i], time.Now().Add(-arriveTimeout), fetcher)
verifyImportEvent(t, imported)
}
verifyImportDone(t, imported)
}
// Tests that if blocks are announced by multiple peers (or even the same buggy
// peer), they will only get downloaded at most once.
func TestConcurrentAnnouncements(t *testing.T) {
// Create a chain of blocks to import
targetBlocks := 4 * hashLimit
hashes, blocks := makeChain(targetBlocks, 0, genesis)
// Assemble a tester with a built in counter for the requests
tester := newTester()
fetcher := tester.makeFetcher(blocks)
counter := uint32(0)
wrapper := func(hashes []common.Hash) error {
atomic.AddUint32(&counter, uint32(len(hashes)))
return fetcher(hashes)
}
// Iteratively announce blocks until all are imported
imported := make(chan *types.Block)
tester.fetcher.importedHook = func(block *types.Block) { imported <- block }
for i := len(hashes) - 2; i >= 0; i-- {
tester.fetcher.Notify("first", hashes[i], time.Now().Add(-arriveTimeout), wrapper)
tester.fetcher.Notify("second", hashes[i], time.Now().Add(-arriveTimeout+time.Millisecond), wrapper)
tester.fetcher.Notify("second", hashes[i], time.Now().Add(-arriveTimeout-time.Millisecond), wrapper)
verifyImportEvent(t, imported)
}
verifyImportDone(t, imported)
// Make sure no blocks were retrieved twice
if int(counter) != targetBlocks {
t.Fatalf("retrieval count mismatch: have %v, want %v", counter, targetBlocks)
}
}
// Tests that announcements arriving while a previous is being fetched still
// results in a valid import.
func TestOverlappingAnnouncements(t *testing.T) {
// Create a chain of blocks to import
targetBlocks := 4 * hashLimit
hashes, blocks := makeChain(targetBlocks, 0, genesis)
tester := newTester()
fetcher := tester.makeFetcher(blocks)
// Iteratively announce blocks, but overlap them continuously
fetching := make(chan []common.Hash)
imported := make(chan *types.Block, len(hashes)-1)
tester.fetcher.fetchingHook = func(hashes []common.Hash) { fetching <- hashes }
tester.fetcher.importedHook = func(block *types.Block) { imported <- block }
for i := len(hashes) - 2; i >= 0; i-- {
tester.fetcher.Notify("valid", hashes[i], time.Now().Add(-arriveTimeout), fetcher)
select {
case <-fetching:
case <-time.After(time.Second):
t.Fatalf("hash %d: announce timeout", len(hashes)-i)
}
}
// Wait for all the imports to complete and check count
verifyImportCount(t, imported, len(hashes)-1)
}
// Tests that announces already being retrieved will not be duplicated.
func TestPendingDeduplication(t *testing.T) {
// Create a hash and corresponding block
hashes, blocks := makeChain(1, 0, genesis)
// Assemble a tester with a built in counter and delayed fetcher
tester := newTester()
fetcher := tester.makeFetcher(blocks)
delay := 50 * time.Millisecond
counter := uint32(0)
wrapper := func(hashes []common.Hash) error {
atomic.AddUint32(&counter, uint32(len(hashes)))
// Simulate a long running fetch
go func() {
time.Sleep(delay)
fetcher(hashes)
}()
return nil
}
// Announce the same block many times until it's fetched (wait for any pending ops)
for tester.getBlock(hashes[0]) == nil {
tester.fetcher.Notify("repeater", hashes[0], time.Now().Add(-arriveTimeout), wrapper)
time.Sleep(time.Millisecond)
}
time.Sleep(delay)
// Check that all blocks were imported and none fetched twice
if imported := len(tester.blocks); imported != 2 {
t.Fatalf("synchronised block mismatch: have %v, want %v", imported, 2)
}
if int(counter) != 1 {
t.Fatalf("retrieval count mismatch: have %v, want %v", counter, 1)
}
}
// Tests that announcements retrieved in a random order are cached and eventually
// imported when all the gaps are filled in.
func TestRandomArrivalImport(t *testing.T) {
// Create a chain of blocks to import, and choose one to delay
targetBlocks := maxQueueDist
hashes, blocks := makeChain(targetBlocks, 0, genesis)
skip := targetBlocks / 2
tester := newTester()
fetcher := tester.makeFetcher(blocks)
// Iteratively announce blocks, skipping one entry
imported := make(chan *types.Block, len(hashes)-1)
tester.fetcher.importedHook = func(block *types.Block) { imported <- block }
for i := len(hashes) - 1; i >= 0; i-- {
if i != skip {
tester.fetcher.Notify("valid", hashes[i], time.Now().Add(-arriveTimeout), fetcher)
time.Sleep(time.Millisecond)
}
}
// Finally announce the skipped entry and check full import
tester.fetcher.Notify("valid", hashes[skip], time.Now().Add(-arriveTimeout), fetcher)
verifyImportCount(t, imported, len(hashes)-1)
}
// Tests that direct block enqueues (due to block propagation vs. hash announce)
// are correctly schedule, filling and import queue gaps.
func TestQueueGapFill(t *testing.T) {
// Create a chain of blocks to import, and choose one to not announce at all
targetBlocks := maxQueueDist
hashes, blocks := makeChain(targetBlocks, 0, genesis)
skip := targetBlocks / 2
tester := newTester()
fetcher := tester.makeFetcher(blocks)
// Iteratively announce blocks, skipping one entry
imported := make(chan *types.Block, len(hashes)-1)
tester.fetcher.importedHook = func(block *types.Block) { imported <- block }
for i := len(hashes) - 1; i >= 0; i-- {
if i != skip {
tester.fetcher.Notify("valid", hashes[i], time.Now().Add(-arriveTimeout), fetcher)
time.Sleep(time.Millisecond)
}
}
// Fill the missing block directly as if propagated
tester.fetcher.Enqueue("valid", blocks[hashes[skip]])
verifyImportCount(t, imported, len(hashes)-1)
}
// Tests that blocks arriving from various sources (multiple propagations, hash
// announces, etc) do not get scheduled for import multiple times.
func TestImportDeduplication(t *testing.T) {
// Create two blocks to import (one for duplication, the other for stalling)
hashes, blocks := makeChain(2, 0, genesis)
// Create the tester and wrap the importer with a counter
tester := newTester()
fetcher := tester.makeFetcher(blocks)
counter := uint32(0)
tester.fetcher.insertChain = func(blocks types.Blocks) (int, error) {
atomic.AddUint32(&counter, uint32(len(blocks)))
return tester.insertChain(blocks)
}
// Instrument the fetching and imported events
fetching := make(chan []common.Hash)
imported := make(chan *types.Block, len(hashes)-1)
tester.fetcher.fetchingHook = func(hashes []common.Hash) { fetching <- hashes }
tester.fetcher.importedHook = func(block *types.Block) { imported <- block }
// Announce the duplicating block, wait for retrieval, and also propagate directly
tester.fetcher.Notify("valid", hashes[0], time.Now().Add(-arriveTimeout), fetcher)
<-fetching
tester.fetcher.Enqueue("valid", blocks[hashes[0]])
tester.fetcher.Enqueue("valid", blocks[hashes[0]])
tester.fetcher.Enqueue("valid", blocks[hashes[0]])
// Fill the missing block directly as if propagated, and check import uniqueness
tester.fetcher.Enqueue("valid", blocks[hashes[1]])
verifyImportCount(t, imported, 2)
if counter != 2 {
t.Fatalf("import invocation count mismatch: have %v, want %v", counter, 2)
}
}
// Tests that blocks with numbers much lower or higher than out current head get
// discarded no prevent wasting resources on useless blocks from faulty peers.
func TestDistantDiscarding(t *testing.T) {
// Create a long chain to import
hashes, blocks := makeChain(3*maxQueueDist, 0, genesis)
head := hashes[len(hashes)/2]
// Create a tester and simulate a head block being the middle of the above chain
tester := newTester()
tester.hashes = []common.Hash{head}
tester.blocks = map[common.Hash]*types.Block{head: blocks[head]}
// Ensure that a block with a lower number than the threshold is discarded
tester.fetcher.Enqueue("lower", blocks[hashes[0]])
time.Sleep(10 * time.Millisecond)
if !tester.fetcher.queue.Empty() {
t.Fatalf("fetcher queued stale block")
}
// Ensure that a block with a higher number than the threshold is discarded
tester.fetcher.Enqueue("higher", blocks[hashes[len(hashes)-1]])
time.Sleep(10 * time.Millisecond)
if !tester.fetcher.queue.Empty() {
t.Fatalf("fetcher queued future block")
}
}
// Tests that a peer is unable to use unbounded memory with sending infinite
// block announcements to a node, but that even in the face of such an attack,
// the fetcher remains operational.
func TestHashMemoryExhaustionAttack(t *testing.T) {
// Create a tester with instrumented import hooks
tester := newTester()
imported := make(chan *types.Block)
tester.fetcher.importedHook = func(block *types.Block) { imported <- block }
// Create a valid chain and an infinite junk chain
targetBlocks := hashLimit + 2*maxQueueDist
hashes, blocks := makeChain(targetBlocks, 0, genesis)
valid := tester.makeFetcher(blocks)
attack, _ := makeChain(targetBlocks, 0, unknownBlock)
attacker := tester.makeFetcher(nil)
// Feed the tester a huge hashset from the attacker, and a limited from the valid peer
for i := 0; i < len(attack); i++ {
if i < maxQueueDist {
tester.fetcher.Notify("valid", hashes[len(hashes)-2-i], time.Now(), valid)
}
tester.fetcher.Notify("attacker", attack[i], time.Now(), attacker)
}
if len(tester.fetcher.announced) != hashLimit+maxQueueDist {
t.Fatalf("queued announce count mismatch: have %d, want %d", len(tester.fetcher.announced), hashLimit+maxQueueDist)
}
// Wait for fetches to complete
verifyImportCount(t, imported, maxQueueDist)
// Feed the remaining valid hashes to ensure DOS protection state remains clean
for i := len(hashes) - maxQueueDist - 2; i >= 0; i-- {
tester.fetcher.Notify("valid", hashes[i], time.Now().Add(-arriveTimeout), valid)
verifyImportEvent(t, imported)
}
verifyImportDone(t, imported)
}
// Tests that blocks sent to the fetcher (either through propagation or via hash
// announces and retrievals) don't pile up indefinitely, exhausting available
// system memory.
func TestBlockMemoryExhaustionAttack(t *testing.T) {
// Create a tester with instrumented import hooks
tester := newTester()
imported := make(chan *types.Block)
tester.fetcher.importedHook = func(block *types.Block) { imported <- block }
// Create a valid chain and a batch of dangling (but in range) blocks
targetBlocks := hashLimit + 2*maxQueueDist
hashes, blocks := makeChain(targetBlocks, 0, genesis)
attack := make(map[common.Hash]*types.Block)
for i := byte(0); len(attack) < blockLimit+2*maxQueueDist; i++ {
hashes, blocks := makeChain(maxQueueDist-1, i, unknownBlock)
for _, hash := range hashes[:maxQueueDist-2] {
attack[hash] = blocks[hash]
}
}
// Try to feed all the attacker blocks make sure only a limited batch is accepted
for _, block := range attack {
tester.fetcher.Enqueue("attacker", block)
}
time.Sleep(200 * time.Millisecond)
if queued := tester.fetcher.queue.Size(); queued != blockLimit {
t.Fatalf("queued block count mismatch: have %d, want %d", queued, blockLimit)
}
// 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)
}
