aboutsummaryrefslogtreecommitdiffstats
path: root/eth/fetcher/fetcher_test.go
blob: d594d830c83f18031bd12c42d9212eeea92bfbca (plain) (blame)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
404
405
406
407
408
409
410
411
412
413
414
415
416
417
418
419
420
421
422
423
424
425
426
427
428
429
430
431
432
433
434
435
436
437
438
439
440
package fetcher

import (
    "encoding/binary"
    "errors"
    "math/big"
    "sync"
    "sync/atomic"
    "testing"
    "time"

    "github.com/ethereum/go-ethereum/common"
    "github.com/ethereum/go-ethereum/core/types"
)

var (
    knownHash   = common.Hash{1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1}
    unknownHash = common.Hash{2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2}
    bannedHash  = common.Hash{3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3}

    genesis = createBlock(1, common.Hash{}, knownHash)
)

// idCounter is used by the createHashes method the generate deterministic but unique hashes
var idCounter = int64(2) // #1 is the genesis block

// createHashes generates a batch of hashes rooted at a specific point in the chain.
func createHashes(amount int, root common.Hash) (hashes []common.Hash) {
    hashes = make([]common.Hash, amount+1)
    hashes[len(hashes)-1] = root

    for i := 0; i < len(hashes)-1; i++ {
        binary.BigEndian.PutUint64(hashes[i][:8], uint64(idCounter))
        idCounter++
    }
    return
}

// createBlock assembles a new block at the given chain height.
func createBlock(i int, parent, hash common.Hash) *types.Block {
    header := &types.Header{Number: big.NewInt(int64(i))}
    block := types.NewBlockWithHeader(header)
    block.HeaderHash = hash
    block.ParentHeaderHash = parent
    return block
}

// copyBlock makes a deep copy of a block suitable for local modifications.
func copyBlock(block *types.Block) *types.Block {
    return createBlock(int(block.Number().Int64()), block.ParentHeaderHash, block.HeaderHash)
}

// createBlocksFromHashes assembles a collection of blocks, each having a correct
// place in the given hash chain.
func createBlocksFromHashes(hashes []common.Hash) map[common.Hash]*types.Block {
    blocks := make(map[common.Hash]*types.Block)
    for i := 0; i < len(hashes); i++ {
        parent := knownHash
        if i < len(hashes)-1 {
            parent = hashes[i+1]
        }
        blocks[hashes[i]] = createBlock(len(hashes)-i, parent, hashes[i])
    }
    return blocks
}

// 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{knownHash},
        blocks: map[common.Hash]*types.Block{knownHash: 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 {
    // Copy all the blocks to ensure they are not tampered with
    closure := make(map[common.Hash]*types.Block)
    for hash, block := range blocks {
        closure[hash] = copyBlock(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
    }
}

// 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 := 24
    hashes := createHashes(targetBlocks, knownHash)
    blocks := createBlocksFromHashes(hashes)

    tester := newTester()
    fetcher := tester.makeFetcher(blocks)

    // Iteratively announce blocks until all are imported
    for i := len(hashes) - 1; i >= 0; i-- {
        tester.fetcher.Notify("valid", hashes[i], time.Now().Add(-arriveTimeout), fetcher)
        time.Sleep(50 * time.Millisecond)
    }
    if imported := len(tester.blocks); imported != targetBlocks+1 {
        t.Fatalf("synchronised block mismatch: have %v, want %v", imported, targetBlocks+1)
    }
}

// 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 := 24
    hashes := createHashes(targetBlocks, knownHash)
    blocks := createBlocksFromHashes(hashes)

    // 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
    for i := len(hashes) - 1; 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)

        time.Sleep(50 * time.Millisecond)
    }
    if imported := len(tester.blocks); imported != targetBlocks+1 {
        t.Fatalf("synchronised block mismatch: have %v, want %v", imported, targetBlocks+1)
    }
    // 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 := 24
    hashes := createHashes(targetBlocks, knownHash)
    blocks := createBlocksFromHashes(hashes)

    tester := newTester()
    fetcher := tester.makeFetcher(blocks)

    // Iteratively announce blocks, but overlap them continuously
    delay, overlap := 50*time.Millisecond, time.Duration(5)
    for i := len(hashes) - 1; i >= 0; i-- {
        tester.fetcher.Notify("valid", hashes[i], time.Now().Add(-arriveTimeout+overlap*delay), fetcher)
        time.Sleep(delay)
    }
    time.Sleep(overlap * delay)

    if imported := len(tester.blocks); imported != targetBlocks+1 {
        t.Fatalf("synchronised block mismatch: have %v, want %v", imported, targetBlocks+1)
    }
}

// Tests that announces already being retrieved will not be duplicated.
func TestPendingDeduplication(t *testing.T) {
    // Create a hash and corresponding block
    hashes := createHashes(1, knownHash)
    blocks := createBlocksFromHashes(hashes)

    // 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 := 24
    hashes := createHashes(targetBlocks, knownHash)
    blocks := createBlocksFromHashes(hashes)
    skip := targetBlocks / 2

    tester := newTester()
    fetcher := tester.makeFetcher(blocks)

    // Iteratively announce blocks, skipping one entry
    for i := len(hashes) - 1; i >= 0; i-- {
        if i != skip {
            tester.fetcher.Notify("valid", hashes[i], time.Now().Add(-arriveTimeout), fetcher)
            time.Sleep(50 * time.Millisecond)
        }
    }
    // Finally announce the skipped entry and check full import
    tester.fetcher.Notify("valid", hashes[skip], time.Now().Add(-arriveTimeout), fetcher)
    time.Sleep(50 * time.Millisecond)

    if imported := len(tester.blocks); imported != targetBlocks+1 {
        t.Fatalf("synchronised block mismatch: have %v, want %v", imported, targetBlocks+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 := 24
    hashes := createHashes(targetBlocks, knownHash)
    blocks := createBlocksFromHashes(hashes)
    skip := targetBlocks / 2

    tester := newTester()
    fetcher := tester.makeFetcher(blocks)

    // Iteratively announce blocks, skipping one entry
    for i := len(hashes) - 1; i >= 0; i-- {
        if i != skip {
            tester.fetcher.Notify("valid", hashes[i], time.Now().Add(-arriveTimeout), fetcher)
            time.Sleep(50 * time.Millisecond)
        }
    }
    // Fill the missing block directly as if propagated
    tester.fetcher.Enqueue("valid", blocks[hashes[skip]])
    time.Sleep(50 * time.Millisecond)

    if imported := len(tester.blocks); imported != targetBlocks+1 {
        t.Fatalf("synchronised block mismatch: have %v, want %v", imported, targetBlocks+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 := createHashes(2, knownHash)
    blocks := createBlocksFromHashes(hashes)

    // 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)
    }
    // Announce the duplicating block, wait for retrieval, and also propagate directly
    tester.fetcher.Notify("valid", hashes[0], time.Now().Add(-arriveTimeout), fetcher)
    time.Sleep(50 * time.Millisecond)

    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]])
    time.Sleep(50 * time.Millisecond)

    if imported := len(tester.blocks); imported != 3 {
        t.Fatalf("synchronised block mismatch: have %v, want %v", imported, 3)
    }
    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 := createHashes(3*maxQueueDist, knownHash)
    blocks := createBlocksFromHashes(hashes)

    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 TestAnnounceMemoryExhaustionAttack(t *testing.T) {
    tester := newTester()

    // Create a valid chain and an infinite junk chain
    hashes := createHashes(announceLimit+2*maxQueueDist, knownHash)
    blocks := createBlocksFromHashes(hashes)
    valid := tester.makeFetcher(blocks)

    attack := createHashes(announceLimit+2*maxQueueDist, unknownHash)
    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)-1-i], time.Now().Add(arriveTimeout/2), valid)
        }
        tester.fetcher.Notify("attacker", attack[i], time.Now().Add(arriveTimeout/2), attacker)
    }
    if len(tester.fetcher.announced) != announceLimit+maxQueueDist {
        t.Fatalf("queued announce count mismatch: have %d, want %d", len(tester.fetcher.announced), announceLimit+maxQueueDist)
    }
    // Wait for synchronisation to complete and check success for the valid peer
    time.Sleep(2 * arriveTimeout)
    if imported := len(tester.blocks); imported != maxQueueDist {
        t.Fatalf("partial synchronised block mismatch: have %v, want %v", imported, maxQueueDist)
    }
    // Feed the remaining valid hashes to ensure DOS protection state remains clean
    for i := len(hashes) - maxQueueDist; i >= 0; {
        for j := 0; j < maxQueueDist && i >= 0; j++ {
            tester.fetcher.Notify("valid", hashes[i], time.Now().Add(time.Millisecond), valid)
            i--
        }
        time.Sleep(256 * time.Millisecond)
    }
    time.Sleep(256 * time.Millisecond)
    if imported := len(tester.blocks); imported != len(hashes) {
        t.Fatalf("fully synchronised block mismatch: have %v, want %v", imported, len(hashes))
    }
}