aboutsummaryrefslogtreecommitdiffstats
path: root/eth/downloader/downloader_test.go
blob: e66a90264343c5bf1f3a745abc882e66d68bab86 (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
441
442
443
444
445
446
447
448
449
450
451
452
453
454
455
456
457
458
459
460
461
462
463
464
465
466
467
468
469
470
471
472
473
474
475
476
477
478
479
480
481
482
483
484
485
486
487
488
489
490
491
492
493
494
495
496
497
498
499
500
501
502
503
504
505
506
507
508
509
510
511
512
513
514
515
516
517
518
519
520
521
522
523
524
525
526
527
528
529
530
531
532
533
534
535
536
537
538
539
540
541
542
543
544
545
546
547
548
549
550
551
552
553
554
555
556
557
558
559
560
561
562
563
564
565
566
567
568
569
570
571
572
573
574
575
576
577
578
579
580
581
582
583
584
585
586
587
588
589
590
591
592
593
594
595
596
597
598
599
600
601
602
603
604
605
606
607
608
609
610
611
612
613
614
615
616
617
618
619
620
621
622
623
624
625
626
627
628
629
630
631
632
633
634
635
636
637
638
639
640
641
642
643
644
645
646
647
648
649
650
651
652
653
654
655
656
657
658
659
660
661
662
663
664
665
666
667
668
669
670
671
672
673
674
675
676
677
678
679
680
681
682
683
684
685
686
687
688
689
690
691
692
693
694
695
696
697
698
699
700
701
702
703
704
705
706
707
708
709
710
711
712
713
714
715
716
717
718
719
720
721
722
723
724
725
726
727
728
729
730
731
732
733
734
735
736
737
738
739
740
741
742
743
744
745
746
747
748
749
750
751
752
753
754
755
756
757
758
759
760
761
762
763
764
765
766
767
768
769
770
771
772
773
774
775
776
777
778
779
780
781
782
783
784
785
786
787
788
789
790
791
792
793
794
795
796
797
798
799
800
801
802
803
804
805
806
807
808
809
810
811
812
813
814
815
816
817
818
819
820
821
822
823
824
825
826
827
828
829
830
831
832
833
834
835
836
837
838
839
840
841
842
843
844
845
846
847
848
849
850
851
852
853
854
855
856
857
858
859
860
861
862
863
864
865
866
867
868
869
870
871
872
873
874
875
876
877
878
879
880
881
882
883
884
885
886
887
888
889
890
891
892
893
894
895
896
897
898
899
900
901
902
903
904
905
906
907
908
909
910
911
912
913
914
915
916
917
918
919
920
921
922
923
924
925
926
927
928
929
930
931
932
933
934
935
936
937
938
939
940
941
942
943
944
945
946
947
948
949
950
951
952
953
954
955
956
957
958
959
960
961
962
963
964
965
966
967
968
969
970
971
972
973
974
975
976
977
978
979
980
981
982
983
984
985
986
987
988
989
990
991
992
993
994
995
996
997
998
999
1000
1001
1002
1003
1004
1005
1006
1007
1008
1009
1010
1011
1012
1013
1014
1015
1016
1017
1018
1019
1020
1021
1022
1023
1024
1025
1026
1027
1028
1029
1030
1031
1032
1033
1034
1035
1036
1037
1038
1039
1040
1041
1042
1043
1044
1045
1046
1047
1048
1049
1050
1051
1052
1053
1054
1055
1056
1057
1058
1059
1060
1061
1062
1063
1064
1065
1066
1067
1068
1069
1070
1071
1072
1073
1074
1075
1076
1077
1078
1079
1080
1081
1082
1083
1084
1085
1086
1087
1088
1089
1090
1091
1092
1093
1094
1095
1096
1097
1098
1099
1100
1101
1102
1103
1104
1105
1106
1107
1108
1109
1110
1111
1112
1113
1114
1115
1116
1117
1118
1119
1120
1121
1122
1123
1124
1125
1126
1127
1128
1129
1130
1131
1132
1133
1134
1135
1136
1137
1138
1139
1140
1141
1142
1143
1144
1145
1146
1147
1148
1149
1150
1151
1152
1153
1154
1155
1156
1157
1158
1159
1160
1161
1162
1163
1164
1165
1166
1167
1168
1169
1170
1171
1172
1173
1174
1175
1176
1177
1178
1179
1180
1181
1182
1183
1184
1185
1186
1187
1188
1189
1190
1191
1192
1193
1194
1195
1196
1197
1198
1199
1200
1201
1202
1203
1204
1205
1206
1207
1208
1209
1210
1211
1212
1213
1214
1215
1216
1217
1218
1219
1220
1221
1222
1223
1224
1225
1226
1227
1228
1229
1230
1231
1232
1233
1234
1235
1236
1237
1238
1239
1240
1241
1242
1243
1244
1245
1246
1247
1248
1249
1250
1251
1252
1253
1254
1255
1256
1257
1258
1259
1260
1261
1262
1263
1264
1265
1266
1267
1268
1269
1270
1271
1272
1273
1274
1275
1276
1277
1278
1279
1280
1281
1282
1283
1284
1285
1286
1287
1288
1289
1290
1291
1292
1293
1294
1295
1296
1297
1298
1299
1300
1301
1302
1303
1304
1305
1306
1307
1308
1309
1310
1311
1312
1313
1314
1315
1316
1317
1318
1319
1320
1321
1322
1323
1324
1325
1326
1327
1328
1329
1330
1331
1332
1333
1334
1335
1336
1337
1338
1339
1340
1341
1342
1343
1344
1345
1346
1347
1348
1349
1350
1351
1352
1353
1354
1355
1356
1357
1358
1359
1360
1361
1362
1363
1364
1365
1366
1367
1368
1369
1370
1371
1372
1373
1374
1375
1376
1377
1378
1379
1380
1381
1382
1383
1384
1385
1386
1387
1388
1389
1390
1391
1392
1393
1394
1395
1396
1397
1398
1399
1400
1401
1402
1403
1404
1405
1406
1407
1408
1409
1410
1411
1412
1413
1414
1415
1416
1417
1418
1419
1420
1421
1422
1423
1424
1425
1426
1427
1428
1429
1430
1431
1432
1433
1434
1435
1436
1437
1438
1439
1440
1441
1442
1443
1444
1445
1446
1447
1448
1449
1450
1451
1452
1453
1454
1455
1456
1457
1458
1459
1460
1461
1462
1463
1464
1465
1466
1467
1468
1469
1470
1471
1472
1473
1474
1475
1476
1477
1478
1479
1480
1481
1482
1483
1484
1485
1486
1487
1488
1489
1490
1491
1492
1493
1494
1495
1496
1497
1498
1499
1500
1501
1502
1503
1504
1505
1506
1507
1508
1509
1510
1511
1512
1513
1514
1515
1516
1517
1518
1519
1520
1521
1522
1523
1524
1525
1526
1527
1528
1529
1530
1531
1532
1533
1534
1535
1536
1537
1538
1539
1540
1541
1542
1543
1544
1545
1546
1547
1548
1549
1550
1551
1552
1553
1554
1555
1556
1557
1558
1559
1560
1561
1562
1563
1564
1565
1566
1567
1568
1569
1570
1571
1572
1573
1574
1575
1576
1577
1578
1579
1580
1581
1582
1583
1584
1585
1586
1587
1588
1589
1590
1591
1592
1593
1594
1595
1596
1597
1598
1599
1600
1601
1602
1603
1604
1605
1606
1607
1608
1609
1610
1611
1612
1613
1614
1615
1616
1617
1618
1619
1620
1621
1622
1623
1624
1625
1626
1627
// Copyright 2015 The go-ethereum Authors
// This file is part of the go-ethereum library.
//
// The go-ethereum library 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.
//
// The go-ethereum library 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 the go-ethereum library. If not, see <http://www.gnu.org/licenses/>.

package downloader

import (
    "errors"
    "fmt"
    "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/state"
    "github.com/ethereum/go-ethereum/core/types"
    "github.com/ethereum/go-ethereum/crypto"
    "github.com/ethereum/go-ethereum/ethdb"
    "github.com/ethereum/go-ethereum/event"
    "github.com/ethereum/go-ethereum/params"
    "github.com/ethereum/go-ethereum/trie"
)

var (
    testdb, _   = ethdb.NewMemDatabase()
    testKey, _  = crypto.HexToECDSA("b71c71a67e1177ad4e901695e1b4b9ee17ae16c6668d313eac2f96dbcda3f291")
    testAddress = crypto.PubkeyToAddress(testKey.PublicKey)
    genesis     = core.GenesisBlockForTesting(testdb, testAddress, big.NewInt(1000000000))
)

// Reduce the block cache limit, otherwise the tests will be very heavy.
func init() {
    blockCacheLimit = 1024
}

// makeChain creates a chain of n blocks starting at and including parent.
// the returned hash chain is ordered head->parent. In addition, every 3rd block
// contains a transaction and every 5th an uncle to allow testing correct block
// reassembly.
func makeChain(n int, seed byte, parent *types.Block, parentReceipts types.Receipts) ([]common.Hash, map[common.Hash]*types.Header, map[common.Hash]*types.Block, map[common.Hash]types.Receipts) {
    // Generate the block chain
    blocks, receipts := core.GenerateChain(parent, testdb, n, func(i int, block *core.BlockGen) {
        block.SetCoinbase(common.Address{seed})

        // If the block number is multiple of 3, send a bonus transaction to the miner
        if parent == genesis && i%3 == 0 {
            tx, err := types.NewTransaction(block.TxNonce(testAddress), common.Address{seed}, big.NewInt(1000), params.TxGas, nil, nil).SignECDSA(testKey)
            if err != nil {
                panic(err)
            }
            block.AddTx(tx)
        }
        // If the block number is a multiple of 5, add a bonus uncle to the block
        if i > 0 && i%5 == 0 {
            block.AddUncle(&types.Header{
                ParentHash: block.PrevBlock(i - 1).Hash(),
                Number:     big.NewInt(block.Number().Int64() - 1),
            })
        }
    })
    // Convert the block-chain into a hash-chain and header/block maps
    hashes := make([]common.Hash, n+1)
    hashes[len(hashes)-1] = parent.Hash()

    headerm := make(map[common.Hash]*types.Header, n+1)
    headerm[parent.Hash()] = parent.Header()

    blockm := make(map[common.Hash]*types.Block, n+1)
    blockm[parent.Hash()] = parent

    receiptm := make(map[common.Hash]types.Receipts, n+1)
    receiptm[parent.Hash()] = parentReceipts

    for i, b := range blocks {
        hashes[len(hashes)-i-2] = b.Hash()
        headerm[b.Hash()] = b.Header()
        blockm[b.Hash()] = b
        receiptm[b.Hash()] = receipts[i]
    }
    return hashes, headerm, blockm, receiptm
}

// makeChainFork creates two chains of length n, such that h1[:f] and
// h2[:f] are different but have a common suffix of length n-f.
func makeChainFork(n, f int, parent *types.Block, parentReceipts types.Receipts) ([]common.Hash, []common.Hash, map[common.Hash]*types.Header, map[common.Hash]*types.Header, map[common.Hash]*types.Block, map[common.Hash]*types.Block, map[common.Hash]types.Receipts, map[common.Hash]types.Receipts) {
    // Create the common suffix
    hashes, headers, blocks, receipts := makeChain(n-f, 0, parent, parentReceipts)

    // Create the forks
    hashes1, headers1, blocks1, receipts1 := makeChain(f, 1, blocks[hashes[0]], receipts[hashes[0]])
    hashes1 = append(hashes1, hashes[1:]...)

    hashes2, headers2, blocks2, receipts2 := makeChain(f, 2, blocks[hashes[0]], receipts[hashes[0]])
    hashes2 = append(hashes2, hashes[1:]...)

    for hash, header := range headers {
        headers1[hash] = header
        headers2[hash] = header
    }
    for hash, block := range blocks {
        blocks1[hash] = block
        blocks2[hash] = block
    }
    for hash, receipt := range receipts {
        receipts1[hash] = receipt
        receipts2[hash] = receipt
    }
    return hashes1, hashes2, headers1, headers2, blocks1, blocks2, receipts1, receipts2
}

// downloadTester is a test simulator for mocking out local block chain.
type downloadTester struct {
    stateDb    ethdb.Database
    downloader *Downloader

    ownHashes   []common.Hash                  // Hash chain belonging to the tester
    ownHeaders  map[common.Hash]*types.Header  // Headers belonging to the tester
    ownBlocks   map[common.Hash]*types.Block   // Blocks belonging to the tester
    ownReceipts map[common.Hash]types.Receipts // Receipts belonging to the tester
    ownChainTd  map[common.Hash]*big.Int       // Total difficulties of the blocks in the local chain

    peerHashes   map[string][]common.Hash                  // Hash chain belonging to different test peers
    peerHeaders  map[string]map[common.Hash]*types.Header  // Headers belonging to different test peers
    peerBlocks   map[string]map[common.Hash]*types.Block   // Blocks belonging to different test peers
    peerReceipts map[string]map[common.Hash]types.Receipts // Receipts belonging to different test peers
    peerChainTds map[string]map[common.Hash]*big.Int       // Total difficulties of the blocks in the peer chains

    lock sync.RWMutex
}

// newTester creates a new downloader test mocker.
func newTester() *downloadTester {
    tester := &downloadTester{
        ownHashes:    []common.Hash{genesis.Hash()},
        ownHeaders:   map[common.Hash]*types.Header{genesis.Hash(): genesis.Header()},
        ownBlocks:    map[common.Hash]*types.Block{genesis.Hash(): genesis},
        ownReceipts:  map[common.Hash]types.Receipts{genesis.Hash(): nil},
        ownChainTd:   map[common.Hash]*big.Int{genesis.Hash(): genesis.Difficulty()},
        peerHashes:   make(map[string][]common.Hash),
        peerHeaders:  make(map[string]map[common.Hash]*types.Header),
        peerBlocks:   make(map[string]map[common.Hash]*types.Block),
        peerReceipts: make(map[string]map[common.Hash]types.Receipts),
        peerChainTds: make(map[string]map[common.Hash]*big.Int),
    }
    tester.stateDb, _ = ethdb.NewMemDatabase()
    tester.stateDb.Put(genesis.Root().Bytes(), []byte{0x00})

    tester.downloader = New(tester.stateDb, new(event.TypeMux), tester.hasHeader, tester.hasBlock, tester.getHeader,
        tester.getBlock, tester.headHeader, tester.headBlock, tester.headFastBlock, tester.commitHeadBlock, tester.getTd,
        tester.insertHeaders, tester.insertBlocks, tester.insertReceipts, tester.rollback, tester.dropPeer)

    return tester
}

// sync starts synchronizing with a remote peer, blocking until it completes.
func (dl *downloadTester) sync(id string, td *big.Int, mode SyncMode) error {
    dl.lock.RLock()
    hash := dl.peerHashes[id][0]
    // If no particular TD was requested, load from the peer's blockchain
    if td == nil {
        td = big.NewInt(1)
        if diff, ok := dl.peerChainTds[id][hash]; ok {
            td = diff
        }
    }
    dl.lock.RUnlock()
    return dl.downloader.synchronise(id, hash, td, mode)
}

// hasHeader checks if a header is present in the testers canonical chain.
func (dl *downloadTester) hasHeader(hash common.Hash) bool {
    return dl.getHeader(hash) != nil
}

// hasBlock checks if a block and associated state is present in the testers canonical chain.
func (dl *downloadTester) hasBlock(hash common.Hash) bool {
    block := dl.getBlock(hash)
    if block == nil {
        return false
    }
    _, err := dl.stateDb.Get(block.Root().Bytes())
    return err == nil
}

// getHeader retrieves a header from the testers canonical chain.
func (dl *downloadTester) getHeader(hash common.Hash) *types.Header {
    dl.lock.RLock()
    defer dl.lock.RUnlock()

    return dl.ownHeaders[hash]
}

// getBlock retrieves a block from the testers canonical chain.
func (dl *downloadTester) getBlock(hash common.Hash) *types.Block {
    dl.lock.RLock()
    defer dl.lock.RUnlock()

    return dl.ownBlocks[hash]
}

// headHeader retrieves the current head header from the canonical chain.
func (dl *downloadTester) headHeader() *types.Header {
    dl.lock.RLock()
    defer dl.lock.RUnlock()

    for i := len(dl.ownHashes) - 1; i >= 0; i-- {
        if header := dl.ownHeaders[dl.ownHashes[i]]; header != nil {
            return header
        }
    }
    return genesis.Header()
}

// headBlock retrieves the current head block from the canonical chain.
func (dl *downloadTester) headBlock() *types.Block {
    dl.lock.RLock()
    defer dl.lock.RUnlock()

    for i := len(dl.ownHashes) - 1; i >= 0; i-- {
        if block := dl.ownBlocks[dl.ownHashes[i]]; block != nil {
            if _, err := dl.stateDb.Get(block.Root().Bytes()); err == nil {
                return block
            }
        }
    }
    return genesis
}

// headFastBlock retrieves the current head fast-sync block from the canonical chain.
func (dl *downloadTester) headFastBlock() *types.Block {
    dl.lock.RLock()
    defer dl.lock.RUnlock()

    for i := len(dl.ownHashes) - 1; i >= 0; i-- {
        if block := dl.ownBlocks[dl.ownHashes[i]]; block != nil {
            return block
        }
    }
    return genesis
}

// commitHeadBlock manually sets the head block to a given hash.
func (dl *downloadTester) commitHeadBlock(hash common.Hash) error {
    // For now only check that the state trie is correct
    if block := dl.getBlock(hash); block != nil {
        _, err := trie.NewSecure(block.Root(), dl.stateDb)
        return err
    }
    return fmt.Errorf("non existent block: %x", hash[:4])
}

// getTd retrieves the block's total difficulty from the canonical chain.
func (dl *downloadTester) getTd(hash common.Hash) *big.Int {
    dl.lock.RLock()
    defer dl.lock.RUnlock()

    return dl.ownChainTd[hash]
}

// insertHeaders injects a new batch of headers into the simulated chain.
func (dl *downloadTester) insertHeaders(headers []*types.Header, checkFreq int) (int, error) {
    dl.lock.Lock()
    defer dl.lock.Unlock()

    // Do a quick check, as the blockchain.InsertHeaderChain doesn't insert anything in case of errors
    if _, ok := dl.ownHeaders[headers[0].ParentHash]; !ok {
        return 0, errors.New("unknown parent")
    }
    for i := 1; i < len(headers); i++ {
        if headers[i].ParentHash != headers[i-1].Hash() {
            return i, errors.New("unknown parent")
        }
    }
    // Do a full insert if pre-checks passed
    for i, header := range headers {
        if _, ok := dl.ownHeaders[header.Hash()]; ok {
            continue
        }
        if _, ok := dl.ownHeaders[header.ParentHash]; !ok {
            return i, errors.New("unknown parent")
        }
        dl.ownHashes = append(dl.ownHashes, header.Hash())
        dl.ownHeaders[header.Hash()] = header
        dl.ownChainTd[header.Hash()] = new(big.Int).Add(dl.ownChainTd[header.ParentHash], header.Difficulty)
    }
    return len(headers), nil
}

// insertBlocks injects a new batch of blocks into the simulated chain.
func (dl *downloadTester) insertBlocks(blocks types.Blocks) (int, error) {
    dl.lock.Lock()
    defer dl.lock.Unlock()

    for i, block := range blocks {
        if parent, ok := dl.ownBlocks[block.ParentHash()]; !ok {
            return i, errors.New("unknown parent")
        } else if _, err := dl.stateDb.Get(parent.Root().Bytes()); err != nil {
            return i, fmt.Errorf("unknown parent state %x: %v", parent.Root(), err)
        }
        if _, ok := dl.ownHeaders[block.Hash()]; !ok {
            dl.ownHashes = append(dl.ownHashes, block.Hash())
            dl.ownHeaders[block.Hash()] = block.Header()
        }
        dl.ownBlocks[block.Hash()] = block
        dl.stateDb.Put(block.Root().Bytes(), []byte{0x00})
        dl.ownChainTd[block.Hash()] = new(big.Int).Add(dl.ownChainTd[block.ParentHash()], block.Difficulty())
    }
    return len(blocks), nil
}

// insertReceipts injects a new batch of blocks into the simulated chain.
func (dl *downloadTester) insertReceipts(blocks types.Blocks, receipts []types.Receipts) (int, error) {
    dl.lock.Lock()
    defer dl.lock.Unlock()

    for i := 0; i < len(blocks) && i < len(receipts); i++ {
        if _, ok := dl.ownHeaders[blocks[i].Hash()]; !ok {
            return i, errors.New("unknown owner")
        }
        if _, ok := dl.ownBlocks[blocks[i].ParentHash()]; !ok {
            return i, errors.New("unknown parent")
        }
        dl.ownBlocks[blocks[i].Hash()] = blocks[i]
        dl.ownReceipts[blocks[i].Hash()] = receipts[i]
    }
    return len(blocks), nil
}

// rollback removes some recently added elements from the chain.
func (dl *downloadTester) rollback(hashes []common.Hash) {
    dl.lock.Lock()
    defer dl.lock.Unlock()

    for i := len(hashes) - 1; i >= 0; i-- {
        if dl.ownHashes[len(dl.ownHashes)-1] == hashes[i] {
            dl.ownHashes = dl.ownHashes[:len(dl.ownHashes)-1]
        }
        delete(dl.ownChainTd, hashes[i])
        delete(dl.ownHeaders, hashes[i])
        delete(dl.ownReceipts, hashes[i])
        delete(dl.ownBlocks, hashes[i])
    }
}

// newPeer registers a new block download source into the downloader.
func (dl *downloadTester) newPeer(id string, version int, hashes []common.Hash, headers map[common.Hash]*types.Header, blocks map[common.Hash]*types.Block, receipts map[common.Hash]types.Receipts) error {
    return dl.newSlowPeer(id, version, hashes, headers, blocks, receipts, 0)
}

// newSlowPeer registers a new block download source into the downloader, with a
// specific delay time on processing the network packets sent to it, simulating
// potentially slow network IO.
func (dl *downloadTester) newSlowPeer(id string, version int, hashes []common.Hash, headers map[common.Hash]*types.Header, blocks map[common.Hash]*types.Block, receipts map[common.Hash]types.Receipts, delay time.Duration) error {
    dl.lock.Lock()
    defer dl.lock.Unlock()

    var err error
    switch version {
    case 61:
        err = dl.downloader.RegisterPeer(id, version, hashes[0], dl.peerGetRelHashesFn(id, delay), dl.peerGetAbsHashesFn(id, delay), dl.peerGetBlocksFn(id, delay), nil, nil, nil, nil, nil)
    case 62:
        err = dl.downloader.RegisterPeer(id, version, hashes[0], nil, nil, nil, dl.peerGetRelHeadersFn(id, delay), dl.peerGetAbsHeadersFn(id, delay), dl.peerGetBodiesFn(id, delay), nil, nil)
    case 63:
        err = dl.downloader.RegisterPeer(id, version, hashes[0], nil, nil, nil, dl.peerGetRelHeadersFn(id, delay), dl.peerGetAbsHeadersFn(id, delay), dl.peerGetBodiesFn(id, delay), dl.peerGetReceiptsFn(id, delay), dl.peerGetNodeDataFn(id, delay))
    case 64:
        err = dl.downloader.RegisterPeer(id, version, hashes[0], nil, nil, nil, dl.peerGetRelHeadersFn(id, delay), dl.peerGetAbsHeadersFn(id, delay), dl.peerGetBodiesFn(id, delay), dl.peerGetReceiptsFn(id, delay), dl.peerGetNodeDataFn(id, delay))
    }
    if err == nil {
        // Assign the owned hashes, headers and blocks to the peer (deep copy)
        dl.peerHashes[id] = make([]common.Hash, len(hashes))
        copy(dl.peerHashes[id], hashes)

        dl.peerHeaders[id] = make(map[common.Hash]*types.Header)
        dl.peerBlocks[id] = make(map[common.Hash]*types.Block)
        dl.peerReceipts[id] = make(map[common.Hash]types.Receipts)
        dl.peerChainTds[id] = make(map[common.Hash]*big.Int)

        genesis := hashes[len(hashes)-1]
        if header := headers[genesis]; header != nil {
            dl.peerHeaders[id][genesis] = header
            dl.peerChainTds[id][genesis] = header.Difficulty
        }
        if block := blocks[genesis]; block != nil {
            dl.peerBlocks[id][genesis] = block
            dl.peerChainTds[id][genesis] = block.Difficulty()
        }

        for i := len(hashes) - 2; i >= 0; i-- {
            hash := hashes[i]

            if header, ok := headers[hash]; ok {
                dl.peerHeaders[id][hash] = header
                if _, ok := dl.peerHeaders[id][header.ParentHash]; ok {
                    dl.peerChainTds[id][hash] = new(big.Int).Add(header.Difficulty, dl.peerChainTds[id][header.ParentHash])
                }
            }
            if block, ok := blocks[hash]; ok {
                dl.peerBlocks[id][hash] = block
                if _, ok := dl.peerBlocks[id][block.ParentHash()]; ok {
                    dl.peerChainTds[id][hash] = new(big.Int).Add(block.Difficulty(), dl.peerChainTds[id][block.ParentHash()])
                }
            }
            if receipt, ok := receipts[hash]; ok {
                dl.peerReceipts[id][hash] = receipt
            }
        }
    }
    return err
}

// dropPeer simulates a hard peer removal from the connection pool.
func (dl *downloadTester) dropPeer(id string) {
    dl.lock.Lock()
    defer dl.lock.Unlock()

    delete(dl.peerHashes, id)
    delete(dl.peerHeaders, id)
    delete(dl.peerBlocks, id)
    delete(dl.peerChainTds, id)

    dl.downloader.UnregisterPeer(id)
}

// peerGetRelHashesFn constructs a GetHashes function associated with a specific
// peer in the download tester. The returned function can be used to retrieve
// batches of hashes from the particularly requested peer.
func (dl *downloadTester) peerGetRelHashesFn(id string, delay time.Duration) func(head common.Hash) error {
    return func(head common.Hash) error {
        time.Sleep(delay)

        dl.lock.RLock()
        defer dl.lock.RUnlock()

        // Gather the next batch of hashes
        hashes := dl.peerHashes[id]
        result := make([]common.Hash, 0, MaxHashFetch)
        for i, hash := range hashes {
            if hash == head {
                i++
                for len(result) < cap(result) && i < len(hashes) {
                    result = append(result, hashes[i])
                    i++
                }
                break
            }
        }
        // Delay delivery a bit to allow attacks to unfold
        go func() {
            time.Sleep(time.Millisecond)
            dl.downloader.DeliverHashes(id, result)
        }()
        return nil
    }
}

// peerGetAbsHashesFn constructs a GetHashesFromNumber function associated with
// a particular peer in the download tester. The returned function can be used to
// retrieve batches of hashes from the particularly requested peer.
func (dl *downloadTester) peerGetAbsHashesFn(id string, delay time.Duration) func(uint64, int) error {
    return func(head uint64, count int) error {
        time.Sleep(delay)

        dl.lock.RLock()
        defer dl.lock.RUnlock()

        // Gather the next batch of hashes
        hashes := dl.peerHashes[id]
        result := make([]common.Hash, 0, count)
        for i := 0; i < count && len(hashes)-int(head)-1-i >= 0; i++ {
            result = append(result, hashes[len(hashes)-int(head)-1-i])
        }
        // Delay delivery a bit to allow attacks to unfold
        go func() {
            time.Sleep(time.Millisecond)
            dl.downloader.DeliverHashes(id, result)
        }()
        return nil
    }
}

// peerGetBlocksFn constructs a getBlocks function associated with a particular
// peer in the download tester. The returned function can be used to retrieve
// batches of blocks from the particularly requested peer.
func (dl *downloadTester) peerGetBlocksFn(id string, delay time.Duration) func([]common.Hash) error {
    return func(hashes []common.Hash) error {
        time.Sleep(delay)

        dl.lock.RLock()
        defer dl.lock.RUnlock()

        blocks := dl.peerBlocks[id]
        result := make([]*types.Block, 0, len(hashes))
        for _, hash := range hashes {
            if block, ok := blocks[hash]; ok {
                result = append(result, block)
            }
        }
        go dl.downloader.DeliverBlocks(id, result)

        return nil
    }
}

// peerGetRelHeadersFn constructs a GetBlockHeaders function based on a hashed
// origin; associated with a particular peer in the download tester. The returned
// function can be used to retrieve batches of headers from the particular peer.
func (dl *downloadTester) peerGetRelHeadersFn(id string, delay time.Duration) func(common.Hash, int, int, bool) error {
    return func(origin common.Hash, amount int, skip int, reverse bool) error {
        // Find the canonical number of the hash
        dl.lock.RLock()
        number := uint64(0)
        for num, hash := range dl.peerHashes[id] {
            if hash == origin {
                number = uint64(len(dl.peerHashes[id]) - num - 1)
                break
            }
        }
        dl.lock.RUnlock()

        // Use the absolute header fetcher to satisfy the query
        return dl.peerGetAbsHeadersFn(id, delay)(number, amount, skip, reverse)
    }
}

// peerGetAbsHeadersFn constructs a GetBlockHeaders function based on a numbered
// origin; associated with a particular peer in the download tester. The returned
// function can be used to retrieve batches of headers from the particular peer.
func (dl *downloadTester) peerGetAbsHeadersFn(id string, delay time.Duration) func(uint64, int, int, bool) error {
    return func(origin uint64, amount int, skip int, reverse bool) error {
        time.Sleep(delay)

        dl.lock.RLock()
        defer dl.lock.RUnlock()

        // Gather the next batch of headers
        hashes := dl.peerHashes[id]
        headers := dl.peerHeaders[id]
        result := make([]*types.Header, 0, amount)
        for i := 0; i < amount && len(hashes)-int(origin)-1-i >= 0; i++ {
            if header, ok := headers[hashes[len(hashes)-int(origin)-1-i]]; ok {
                result = append(result, header)
            }
        }
        // Delay delivery a bit to allow attacks to unfold
        go func() {
            time.Sleep(time.Millisecond)
            dl.downloader.DeliverHeaders(id, result)
        }()
        return nil
    }
}

// peerGetBodiesFn constructs a getBlockBodies method associated with a particular
// peer in the download tester. The returned function can be used to retrieve
// batches of block bodies from the particularly requested peer.
func (dl *downloadTester) peerGetBodiesFn(id string, delay time.Duration) func([]common.Hash) error {
    return func(hashes []common.Hash) error {
        time.Sleep(delay)

        dl.lock.RLock()
        defer dl.lock.RUnlock()

        blocks := dl.peerBlocks[id]

        transactions := make([][]*types.Transaction, 0, len(hashes))
        uncles := make([][]*types.Header, 0, len(hashes))

        for _, hash := range hashes {
            if block, ok := blocks[hash]; ok {
                transactions = append(transactions, block.Transactions())
                uncles = append(uncles, block.Uncles())
            }
        }
        go dl.downloader.DeliverBodies(id, transactions, uncles)

        return nil
    }
}

// peerGetReceiptsFn constructs a getReceipts method associated with a particular
// peer in the download tester. The returned function can be used to retrieve
// batches of block receipts from the particularly requested peer.
func (dl *downloadTester) peerGetReceiptsFn(id string, delay time.Duration) func([]common.Hash) error {
    return func(hashes []common.Hash) error {
        time.Sleep(delay)

        dl.lock.RLock()
        defer dl.lock.RUnlock()

        receipts := dl.peerReceipts[id]

        results := make([][]*types.Receipt, 0, len(hashes))
        for _, hash := range hashes {
            if receipt, ok := receipts[hash]; ok {
                results = append(results, receipt)
            }
        }
        go dl.downloader.DeliverReceipts(id, results)

        return nil
    }
}

// peerGetNodeDataFn constructs a getNodeData method associated with a particular
// peer in the download tester. The returned function can be used to retrieve
// batches of node state data from the particularly requested peer.
func (dl *downloadTester) peerGetNodeDataFn(id string, delay time.Duration) func([]common.Hash) error {
    return func(hashes []common.Hash) error {
        time.Sleep(delay)

        dl.lock.RLock()
        defer dl.lock.RUnlock()

        results := make([][]byte, 0, len(hashes))
        for _, hash := range hashes {
            if data, err := testdb.Get(hash.Bytes()); err == nil {
                results = append(results, data)
            }
        }
        go dl.downloader.DeliverNodeData(id, results)

        return nil
    }
}

// assertOwnChain checks if the local chain contains the correct number of items
// of the various chain components.
func assertOwnChain(t *testing.T, tester *downloadTester, length int) {
    assertOwnForkedChain(t, tester, 1, []int{length})
}

// assertOwnForkedChain checks if the local forked chain contains the correct
// number of items of the various chain components.
func assertOwnForkedChain(t *testing.T, tester *downloadTester, common int, lengths []int) {
    // Initialize the counters for the first fork
    headers, blocks := lengths[0], lengths[0]

    minReceipts, maxReceipts := lengths[0]-fsMinFullBlocks-fsPivotInterval, lengths[0]-fsMinFullBlocks
    if minReceipts < 0 {
        minReceipts = 1
    }
    if maxReceipts < 0 {
        maxReceipts = 1
    }
    // Update the counters for each subsequent fork
    for _, length := range lengths[1:] {
        headers += length - common
        blocks += length - common

        minReceipts += length - common - fsMinFullBlocks - fsPivotInterval
        maxReceipts += length - common - fsMinFullBlocks
    }
    switch tester.downloader.mode {
    case FullSync:
        minReceipts, maxReceipts = 1, 1
    case LightSync:
        blocks, minReceipts, maxReceipts = 1, 1, 1
    }
    if hs := len(tester.ownHeaders); hs != headers {
        t.Fatalf("synchronised headers mismatch: have %v, want %v", hs, headers)
    }
    if bs := len(tester.ownBlocks); bs != blocks {
        t.Fatalf("synchronised blocks mismatch: have %v, want %v", bs, blocks)
    }
    if rs := len(tester.ownReceipts); rs < minReceipts || rs > maxReceipts {
        t.Fatalf("synchronised receipts mismatch: have %v, want between [%v, %v]", rs, minReceipts, maxReceipts)
    }
    // Verify the state trie too for fast syncs
    if tester.downloader.mode == FastSync {
        index := 0
        if pivot := int(tester.downloader.queue.fastSyncPivot); pivot < common {
            index = pivot
        } else {
            index = len(tester.ownHashes) - lengths[len(lengths)-1] + int(tester.downloader.queue.fastSyncPivot)
        }
        if index > 0 {
            if statedb, err := state.New(tester.ownHeaders[tester.ownHashes[index]].Root, tester.stateDb); statedb == nil || err != nil {
                t.Fatalf("state reconstruction failed: %v", err)
            }
        }
    }
}

// Tests that simple synchronization against a canonical chain works correctly.
// In this test common ancestor lookup should be short circuited and not require
// binary searching.
func TestCanonicalSynchronisation61(t *testing.T)      { testCanonicalSynchronisation(t, 61, FullSync) }
func TestCanonicalSynchronisation62(t *testing.T)      { testCanonicalSynchronisation(t, 62, FullSync) }
func TestCanonicalSynchronisation63Full(t *testing.T)  { testCanonicalSynchronisation(t, 63, FullSync) }
func TestCanonicalSynchronisation63Fast(t *testing.T)  { testCanonicalSynchronisation(t, 63, FastSync) }
func TestCanonicalSynchronisation64Full(t *testing.T)  { testCanonicalSynchronisation(t, 64, FullSync) }
func TestCanonicalSynchronisation64Fast(t *testing.T)  { testCanonicalSynchronisation(t, 64, FastSync) }
func TestCanonicalSynchronisation64Light(t *testing.T) { testCanonicalSynchronisation(t, 64, LightSync) }

func testCanonicalSynchronisation(t *testing.T, protocol int, mode SyncMode) {
    t.Parallel()

    // Create a small enough block chain to download
    targetBlocks := blockCacheLimit - 15
    hashes, headers, blocks, receipts := makeChain(targetBlocks, 0, genesis, nil)

    tester := newTester()
    tester.newPeer("peer", protocol, hashes, headers, blocks, receipts)

    // Synchronise with the peer and make sure all relevant data was retrieved
    if err := tester.sync("peer", nil, mode); err != nil {
        t.Fatalf("failed to synchronise blocks: %v", err)
    }
    assertOwnChain(t, tester, targetBlocks+1)
}

// Tests that if a large batch of blocks are being downloaded, it is throttled
// until the cached blocks are retrieved.
func TestThrottling61(t *testing.T)     { testThrottling(t, 61, FullSync) }
func TestThrottling62(t *testing.T)     { testThrottling(t, 62, FullSync) }
func TestThrottling63Full(t *testing.T) { testThrottling(t, 63, FullSync) }
func TestThrottling63Fast(t *testing.T) { testThrottling(t, 63, FastSync) }
func TestThrottling64Full(t *testing.T) { testThrottling(t, 64, FullSync) }
func TestThrottling64Fast(t *testing.T) { testThrottling(t, 64, FastSync) }

func testThrottling(t *testing.T, protocol int, mode SyncMode) {
    // Create a long block chain to download and the tester
    targetBlocks := 8 * blockCacheLimit
    hashes, headers, blocks, receipts := makeChain(targetBlocks, 0, genesis, nil)

    tester := newTester()
    tester.newPeer("peer", protocol, hashes, headers, blocks, receipts)

    // Wrap the importer to allow stepping
    blocked, proceed := uint32(0), make(chan struct{})
    tester.downloader.chainInsertHook = func(results []*fetchResult) {
        atomic.StoreUint32(&blocked, uint32(len(results)))
        <-proceed
    }
    // Start a synchronisation concurrently
    errc := make(chan error)
    go func() {
        errc <- tester.sync("peer", nil, mode)
    }()
    // Iteratively take some blocks, always checking the retrieval count
    for {
        // Check the retrieval count synchronously (! reason for this ugly block)
        tester.lock.RLock()
        retrieved := len(tester.ownBlocks)
        tester.lock.RUnlock()
        if retrieved >= targetBlocks+1 {
            break
        }
        // Wait a bit for sync to throttle itself
        var cached, frozen int
        for start := time.Now(); time.Since(start) < 3*time.Second; {
            time.Sleep(25 * time.Millisecond)

            tester.lock.Lock()
            tester.downloader.queue.lock.Lock()
            cached = len(tester.downloader.queue.blockDonePool)
            if mode == FastSync {
                if receipts := len(tester.downloader.queue.receiptDonePool); receipts < cached {
                    if tester.downloader.queue.resultCache[receipts].Header.Number.Uint64() < tester.downloader.queue.fastSyncPivot {
                        cached = receipts
                    }
                }
            }
            frozen = int(atomic.LoadUint32(&blocked))
            retrieved = len(tester.ownBlocks)
            tester.downloader.queue.lock.Unlock()
            tester.lock.Unlock()

            if cached == blockCacheLimit || retrieved+cached+frozen == targetBlocks+1 {
                break
            }
        }
        // Make sure we filled up the cache, then exhaust it
        time.Sleep(25 * time.Millisecond) // give it a chance to screw up

        tester.lock.RLock()
        retrieved = len(tester.ownBlocks)
        tester.lock.RUnlock()
        if cached != blockCacheLimit && retrieved+cached+frozen != targetBlocks+1 {
            t.Fatalf("block count mismatch: have %v, want %v (owned %v, blocked %v, target %v)", cached, blockCacheLimit, retrieved, frozen, targetBlocks+1)
        }
        // Permit the blocked blocks to import
        if atomic.LoadUint32(&blocked) > 0 {
            atomic.StoreUint32(&blocked, uint32(0))
            proceed <- struct{}{}
        }
    }
    // Check that we haven't pulled more blocks than available
    assertOwnChain(t, tester, targetBlocks+1)
    if err := <-errc; err != nil {
        t.Fatalf("block synchronization failed: %v", err)
    }
}

// Tests that simple synchronization against a forked chain works correctly. In
// this test common ancestor lookup should *not* be short circuited, and a full
// binary search should be executed.
func TestForkedSynchronisation61(t *testing.T)      { testForkedSynchronisation(t, 61, FullSync) }
func TestForkedSynchronisation62(t *testing.T)      { testForkedSynchronisation(t, 62, FullSync) }
func TestForkedSynchronisation63Full(t *testing.T)  { testForkedSynchronisation(t, 63, FullSync) }
func TestForkedSynchronisation63Fast(t *testing.T)  { testForkedSynchronisation(t, 63, FastSync) }
func TestForkedSynchronisation64Full(t *testing.T)  { testForkedSynchronisation(t, 64, FullSync) }
func TestForkedSynchronisation64Fast(t *testing.T)  { testForkedSynchronisation(t, 64, FastSync) }
func TestForkedSynchronisation64Light(t *testing.T) { testForkedSynchronisation(t, 64, LightSync) }

func testForkedSynchronisation(t *testing.T, protocol int, mode SyncMode) {
    t.Parallel()

    // Create a long enough forked chain
    common, fork := MaxHashFetch, 2*MaxHashFetch
    hashesA, hashesB, headersA, headersB, blocksA, blocksB, receiptsA, receiptsB := makeChainFork(common+fork, fork, genesis, nil)

    tester := newTester()
    tester.newPeer("fork A", protocol, hashesA, headersA, blocksA, receiptsA)
    tester.newPeer("fork B", protocol, hashesB, headersB, blocksB, receiptsB)

    // Synchronise with the peer and make sure all blocks were retrieved
    if err := tester.sync("fork A", nil, mode); err != nil {
        t.Fatalf("failed to synchronise blocks: %v", err)
    }
    assertOwnChain(t, tester, common+fork+1)

    // Synchronise with the second peer and make sure that fork is pulled too
    if err := tester.sync("fork B", nil, mode); err != nil {
        t.Fatalf("failed to synchronise blocks: %v", err)
    }
    assertOwnForkedChain(t, tester, common+1, []int{common + fork + 1, common + fork + 1})
}

// Tests that an inactive downloader will not accept incoming hashes and blocks.
func TestInactiveDownloader61(t *testing.T) {
    t.Parallel()
    tester := newTester()

    // Check that neither hashes nor blocks are accepted
    if err := tester.downloader.DeliverHashes("bad peer", []common.Hash{}); err != errNoSyncActive {
        t.Errorf("error mismatch: have %v, want %v", err, errNoSyncActive)
    }
    if err := tester.downloader.DeliverBlocks("bad peer", []*types.Block{}); err != errNoSyncActive {
        t.Errorf("error mismatch: have %v, want %v", err, errNoSyncActive)
    }
}

// Tests that an inactive downloader will not accept incoming block headers and
// bodies.
func TestInactiveDownloader62(t *testing.T) {
    t.Parallel()
    tester := newTester()

    // Check that neither block headers nor bodies are accepted
    if err := tester.downloader.DeliverHeaders("bad peer", []*types.Header{}); err != errNoSyncActive {
        t.Errorf("error mismatch: have %v, want %v", err, errNoSyncActive)
    }
    if err := tester.downloader.DeliverBodies("bad peer", [][]*types.Transaction{}, [][]*types.Header{}); err != errNoSyncActive {
        t.Errorf("error mismatch: have %v, want %v", err, errNoSyncActive)
    }
}

// Tests that an inactive downloader will not accept incoming block headers,
// bodies and receipts.
func TestInactiveDownloader63(t *testing.T) {
    t.Parallel()
    tester := newTester()

    // Check that neither block headers nor bodies are accepted
    if err := tester.downloader.DeliverHeaders("bad peer", []*types.Header{}); err != errNoSyncActive {
        t.Errorf("error mismatch: have %v, want %v", err, errNoSyncActive)
    }
    if err := tester.downloader.DeliverBodies("bad peer", [][]*types.Transaction{}, [][]*types.Header{}); err != errNoSyncActive {
        t.Errorf("error mismatch: have %v, want %v", err, errNoSyncActive)
    }
    if err := tester.downloader.DeliverReceipts("bad peer", [][]*types.Receipt{}); err != errNoSyncActive {
        t.Errorf("error mismatch: have %v, want %v", err, errNoSyncActive)
    }
}

// Tests that a canceled download wipes all previously accumulated state.
func TestCancel61(t *testing.T)      { testCancel(t, 61, FullSync) }
func TestCancel62(t *testing.T)      { testCancel(t, 62, FullSync) }
func TestCancel63Full(t *testing.T)  { testCancel(t, 63, FullSync) }
func TestCancel63Fast(t *testing.T)  { testCancel(t, 63, FastSync) }
func TestCancel64Full(t *testing.T)  { testCancel(t, 64, FullSync) }
func TestCancel64Fast(t *testing.T)  { testCancel(t, 64, FastSync) }
func TestCancel64Light(t *testing.T) { testCancel(t, 64, LightSync) }

func testCancel(t *testing.T, protocol int, mode SyncMode) {
    t.Parallel()

    // Create a small enough block chain to download and the tester
    targetBlocks := blockCacheLimit - 15
    if targetBlocks >= MaxHashFetch {
        targetBlocks = MaxHashFetch - 15
    }
    if targetBlocks >= MaxHeaderFetch {
        targetBlocks = MaxHeaderFetch - 15
    }
    hashes, headers, blocks, receipts := makeChain(targetBlocks, 0, genesis, nil)

    tester := newTester()
    tester.newPeer("peer", protocol, hashes, headers, blocks, receipts)

    // Make sure canceling works with a pristine downloader
    tester.downloader.cancel()
    if !tester.downloader.queue.Idle() {
        t.Errorf("download queue not idle")
    }
    // Synchronise with the peer, but cancel afterwards
    if err := tester.sync("peer", nil, mode); err != nil {
        t.Fatalf("failed to synchronise blocks: %v", err)
    }
    tester.downloader.cancel()
    if !tester.downloader.queue.Idle() {
        t.Errorf("download queue not idle")
    }
}

// Tests that synchronisation from multiple peers works as intended (multi thread sanity test).
func TestMultiSynchronisation61(t *testing.T)      { testMultiSynchronisation(t, 61, FullSync) }
func TestMultiSynchronisation62(t *testing.T)      { testMultiSynchronisation(t, 62, FullSync) }
func TestMultiSynchronisation63Full(t *testing.T)  { testMultiSynchronisation(t, 63, FullSync) }
func TestMultiSynchronisation63Fast(t *testing.T)  { testMultiSynchronisation(t, 63, FastSync) }
func TestMultiSynchronisation64Full(t *testing.T)  { testMultiSynchronisation(t, 64, FullSync) }
func TestMultiSynchronisation64Fast(t *testing.T)  { testMultiSynchronisation(t, 64, FastSync) }
func TestMultiSynchronisation64Light(t *testing.T) { testMultiSynchronisation(t, 64, LightSync) }

func testMultiSynchronisation(t *testing.T, protocol int, mode SyncMode) {
    t.Parallel()

    // Create various peers with various parts of the chain
    targetPeers := 8
    targetBlocks := targetPeers*blockCacheLimit - 15
    hashes, headers, blocks, receipts := makeChain(targetBlocks, 0, genesis, nil)

    tester := newTester()
    for i := 0; i < targetPeers; i++ {
        id := fmt.Sprintf("peer #%d", i)
        tester.newPeer(id, protocol, hashes[i*blockCacheLimit:], headers, blocks, receipts)
    }
    if err := tester.sync("peer #0", nil, mode); err != nil {
        t.Fatalf("failed to synchronise blocks: %v", err)
    }
    assertOwnChain(t, tester, targetBlocks+1)
}

// Tests that synchronisations behave well in multi-version protocol environments
// and not wreak havoc on other nodes in the network.
func TestMultiProtoSynchronisation61(t *testing.T)      { testMultiProtoSync(t, 61, FullSync) }
func TestMultiProtoSynchronisation62(t *testing.T)      { testMultiProtoSync(t, 62, FullSync) }
func TestMultiProtoSynchronisation63Full(t *testing.T)  { testMultiProtoSync(t, 63, FullSync) }
func TestMultiProtoSynchronisation63Fast(t *testing.T)  { testMultiProtoSync(t, 63, FastSync) }
func TestMultiProtoSynchronisation64Full(t *testing.T)  { testMultiProtoSync(t, 64, FullSync) }
func TestMultiProtoSynchronisation64Fast(t *testing.T)  { testMultiProtoSync(t, 64, FastSync) }
func TestMultiProtoSynchronisation64Light(t *testing.T) { testMultiProtoSync(t, 64, LightSync) }

func testMultiProtoSync(t *testing.T, protocol int, mode SyncMode) {
    t.Parallel()

    // Create a small enough block chain to download
    targetBlocks := blockCacheLimit - 15
    hashes, headers, blocks, receipts := makeChain(targetBlocks, 0, genesis, nil)

    // Create peers of every type
    tester := newTester()
    tester.newPeer("peer 61", 61, hashes, nil, blocks, nil)
    tester.newPeer("peer 62", 62, hashes, headers, blocks, nil)
    tester.newPeer("peer 63", 63, hashes, headers, blocks, receipts)
    tester.newPeer("peer 64", 64, hashes, headers, blocks, receipts)

    // Synchronise with the requested peer and make sure all blocks were retrieved
    if err := tester.sync(fmt.Sprintf("peer %d", protocol), nil, mode); err != nil {
        t.Fatalf("failed to synchronise blocks: %v", err)
    }
    assertOwnChain(t, tester, targetBlocks+1)

    // Check that no peers have been dropped off
    for _, version := range []int{61, 62, 63, 64} {
        peer := fmt.Sprintf("peer %d", version)
        if _, ok := tester.peerHashes[peer]; !ok {
            t.Errorf("%s dropped", peer)
        }
    }
}

// Tests that if a block is empty (e.g. header only), no body request should be
// made, and instead the header should be assembled into a whole block in itself.
func TestEmptyShortCircuit62(t *testing.T)      { testEmptyShortCircuit(t, 62, FullSync) }
func TestEmptyShortCircuit63Full(t *testing.T)  { testEmptyShortCircuit(t, 63, FullSync) }
func TestEmptyShortCircuit63Fast(t *testing.T)  { testEmptyShortCircuit(t, 63, FastSync) }
func TestEmptyShortCircuit64Full(t *testing.T)  { testEmptyShortCircuit(t, 64, FullSync) }
func TestEmptyShortCircuit64Fast(t *testing.T)  { testEmptyShortCircuit(t, 64, FastSync) }
func TestEmptyShortCircuit64Light(t *testing.T) { testEmptyShortCircuit(t, 64, LightSync) }

func testEmptyShortCircuit(t *testing.T, protocol int, mode SyncMode) {
    t.Parallel()

    // Create a block chain to download
    targetBlocks := 2*blockCacheLimit - 15
    hashes, headers, blocks, receipts := makeChain(targetBlocks, 0, genesis, nil)

    tester := newTester()
    tester.newPeer("peer", protocol, hashes, headers, blocks, receipts)

    // Instrument the downloader to signal body requests
    bodiesHave, receiptsHave := int32(0), int32(0)
    tester.downloader.bodyFetchHook = func(headers []*types.Header) {
        atomic.AddInt32(&bodiesHave, int32(len(headers)))
    }
    tester.downloader.receiptFetchHook = func(headers []*types.Header) {
        atomic.AddInt32(&receiptsHave, int32(len(headers)))
    }
    // Synchronise with the peer and make sure all blocks were retrieved
    if err := tester.sync("peer", nil, mode); err != nil {
        t.Fatalf("failed to synchronise blocks: %v", err)
    }
    assertOwnChain(t, tester, targetBlocks+1)

    // Validate the number of block bodies that should have been requested
    bodiesNeeded, receiptsNeeded := 0, 0
    for _, block := range blocks {
        if mode != LightSync && block != genesis && (len(block.Transactions()) > 0 || len(block.Uncles()) > 0) {
            bodiesNeeded++
        }
    }
    for hash, receipt := range receipts {
        if mode == FastSync && len(receipt) > 0 && headers[hash].Number.Uint64() <= tester.downloader.queue.fastSyncPivot {
            receiptsNeeded++
        }
    }
    if int(bodiesHave) != bodiesNeeded {
        t.Errorf("body retrieval count mismatch: have %v, want %v", bodiesHave, bodiesNeeded)
    }
    if int(receiptsHave) != receiptsNeeded {
        t.Errorf("receipt retrieval count mismatch: have %v, want %v", receiptsHave, receiptsNeeded)
    }
}

// Tests that headers are enqueued continuously, preventing malicious nodes from
// stalling the downloader by feeding gapped header chains.
func TestMissingHeaderAttack62(t *testing.T)      { testMissingHeaderAttack(t, 62, FullSync) }
func TestMissingHeaderAttack63Full(t *testing.T)  { testMissingHeaderAttack(t, 63, FullSync) }
func TestMissingHeaderAttack63Fast(t *testing.T)  { testMissingHeaderAttack(t, 63, FastSync) }
func TestMissingHeaderAttack64Full(t *testing.T)  { testMissingHeaderAttack(t, 64, FullSync) }
func TestMissingHeaderAttack64Fast(t *testing.T)  { testMissingHeaderAttack(t, 64, FastSync) }
func TestMissingHeaderAttack64Light(t *testing.T) { testMissingHeaderAttack(t, 64, LightSync) }

func testMissingHeaderAttack(t *testing.T, protocol int, mode SyncMode) {
    t.Parallel()

    // Create a small enough block chain to download
    targetBlocks := blockCacheLimit - 15
    hashes, headers, blocks, receipts := makeChain(targetBlocks, 0, genesis, nil)

    tester := newTester()

    // Attempt a full sync with an attacker feeding gapped headers
    tester.newPeer("attack", protocol, hashes, headers, blocks, receipts)
    missing := targetBlocks / 2
    delete(tester.peerHeaders["attack"], hashes[missing])

    if err := tester.sync("attack", nil, mode); err == nil {
        t.Fatalf("succeeded attacker synchronisation")
    }
    // Synchronise with the valid peer and make sure sync succeeds
    tester.newPeer("valid", protocol, hashes, headers, blocks, receipts)
    if err := tester.sync("valid", nil, mode); err != nil {
        t.Fatalf("failed to synchronise blocks: %v", err)
    }
    assertOwnChain(t, tester, targetBlocks+1)
}

// Tests that if requested headers are shifted (i.e. first is missing), the queue
// detects the invalid numbering.
func TestShiftedHeaderAttack62(t *testing.T)      { testShiftedHeaderAttack(t, 62, FullSync) }
func TestShiftedHeaderAttack63Full(t *testing.T)  { testShiftedHeaderAttack(t, 63, FullSync) }
func TestShiftedHeaderAttack63Fast(t *testing.T)  { testShiftedHeaderAttack(t, 63, FastSync) }
func TestShiftedHeaderAttack64Full(t *testing.T)  { testShiftedHeaderAttack(t, 64, FullSync) }
func TestShiftedHeaderAttack64Fast(t *testing.T)  { testShiftedHeaderAttack(t, 64, FastSync) }
func TestShiftedHeaderAttack64Light(t *testing.T) { testShiftedHeaderAttack(t, 64, LightSync) }

func testShiftedHeaderAttack(t *testing.T, protocol int, mode SyncMode) {
    // Create a small enough block chain to download
    targetBlocks := blockCacheLimit - 15
    hashes, headers, blocks, receipts := makeChain(targetBlocks, 0, genesis, nil)

    tester := newTester()

    // Attempt a full sync with an attacker feeding shifted headers
    tester.newPeer("attack", protocol, hashes, headers, blocks, receipts)
    delete(tester.peerHeaders["attack"], hashes[len(hashes)-2])
    delete(tester.peerBlocks["attack"], hashes[len(hashes)-2])
    delete(tester.peerReceipts["attack"], hashes[len(hashes)-2])

    if err := tester.sync("attack", nil, mode); err == nil {
        t.Fatalf("succeeded attacker synchronisation")
    }
    // Synchronise with the valid peer and make sure sync succeeds
    tester.newPeer("valid", protocol, hashes, headers, blocks, receipts)
    if err := tester.sync("valid", nil, mode); err != nil {
        t.Fatalf("failed to synchronise blocks: %v", err)
    }
    assertOwnChain(t, tester, targetBlocks+1)
}

// Tests that upon detecting an invalid header, the recent ones are rolled back
// for various failure scenarios. Afterwards a full sync is attempted to make
// sure no state was corrupted.
func TestInvalidHeaderRollback63Fast(t *testing.T)  { testInvalidHeaderRollback(t, 63, FastSync) }
func TestInvalidHeaderRollback64Fast(t *testing.T)  { testInvalidHeaderRollback(t, 64, FastSync) }
func TestInvalidHeaderRollback64Light(t *testing.T) { testInvalidHeaderRollback(t, 64, LightSync) }

func testInvalidHeaderRollback(t *testing.T, protocol int, mode SyncMode) {
    // Create a small enough block chain to download
    targetBlocks := 3*fsHeaderSafetyNet + fsMinFullBlocks
    hashes, headers, blocks, receipts := makeChain(targetBlocks, 0, genesis, nil)

    tester := newTester()

    // Attempt to sync with an attacker that feeds junk during the fast sync phase.
    // This should result in the last fsHeaderSafetyNet headers being rolled back.
    tester.newPeer("fast-attack", protocol, hashes, headers, blocks, receipts)
    missing := fsHeaderSafetyNet + MaxHeaderFetch + 1
    delete(tester.peerHeaders["fast-attack"], hashes[len(hashes)-missing])

    if err := tester.sync("fast-attack", nil, mode); err == nil {
        t.Fatalf("succeeded fast attacker synchronisation")
    }
    if head := tester.headHeader().Number.Int64(); int(head) > MaxHeaderFetch {
        t.Errorf("rollback head mismatch: have %v, want at most %v", head, MaxHeaderFetch)
    }
    // Attempt to sync with an attacker that feeds junk during the block import phase.
    // This should result in both the last fsHeaderSafetyNet number of headers being
    // rolled back, and also the pivot point being reverted to a non-block status.
    tester.newPeer("block-attack", protocol, hashes, headers, blocks, receipts)
    missing = 3*fsHeaderSafetyNet + MaxHeaderFetch + 1
    delete(tester.peerHeaders["block-attack"], hashes[len(hashes)-missing])

    if err := tester.sync("block-attack", nil, mode); err == nil {
        t.Fatalf("succeeded block attacker synchronisation")
    }
    if head := tester.headHeader().Number.Int64(); int(head) > 2*fsHeaderSafetyNet+MaxHeaderFetch {
        t.Errorf("rollback head mismatch: have %v, want at most %v", head, 2*fsHeaderSafetyNet+MaxHeaderFetch)
    }
    if mode == FastSync {
        if head := tester.headBlock().NumberU64(); head != 0 {
            t.Errorf("fast sync pivot block #%d not rolled back", head)
        }
    }
    // Attempt to sync with an attacker that withholds promised blocks after the
    // fast sync pivot point. This could be a trial to leave the node with a bad
    // but already imported pivot block.
    tester.newPeer("withhold-attack", protocol, hashes, headers, blocks, receipts)
    missing = 3*fsHeaderSafetyNet + MaxHeaderFetch + 1

    tester.downloader.noFast = false
    tester.downloader.syncInitHook = func(uint64, uint64) {
        for i := missing; i <= len(hashes); i++ {
            delete(tester.peerHeaders["withhold-attack"], hashes[len(hashes)-i])
        }
        tester.downloader.syncInitHook = nil
    }

    if err := tester.sync("withhold-attack", nil, mode); err == nil {
        t.Fatalf("succeeded withholding attacker synchronisation")
    }
    if head := tester.headHeader().Number.Int64(); int(head) > 2*fsHeaderSafetyNet+MaxHeaderFetch {
        t.Errorf("rollback head mismatch: have %v, want at most %v", head, 2*fsHeaderSafetyNet+MaxHeaderFetch)
    }
    if mode == FastSync {
        if head := tester.headBlock().NumberU64(); head != 0 {
            t.Errorf("fast sync pivot block #%d not rolled back", head)
        }
    }
    // Synchronise with the valid peer and make sure sync succeeds. Since the last
    // rollback should also disable fast syncing for this process, verify that we
    // did a fresh full sync. Note, we can't assert anything about the receipts
    // since we won't purge the database of them, hence we can't use assertOwnChain.
    tester.newPeer("valid", protocol, hashes, headers, blocks, receipts)
    if err := tester.sync("valid", nil, mode); err != nil {
        t.Fatalf("failed to synchronise blocks: %v", err)
    }
    if hs := len(tester.ownHeaders); hs != len(headers) {
        t.Fatalf("synchronised headers mismatch: have %v, want %v", hs, len(headers))
    }
    if mode != LightSync {
        if bs := len(tester.ownBlocks); bs != len(blocks) {
            t.Fatalf("synchronised blocks mismatch: have %v, want %v", bs, len(blocks))
        }
    }
}

// Tests that a peer advertising an high TD doesn't get to stall the downloader
// afterwards by not sending any useful hashes.
func TestHighTDStarvationAttack61(t *testing.T)      { testHighTDStarvationAttack(t, 61, FullSync) }
func TestHighTDStarvationAttack62(t *testing.T)      { testHighTDStarvationAttack(t, 62, FullSync) }
func TestHighTDStarvationAttack63Full(t *testing.T)  { testHighTDStarvationAttack(t, 63, FullSync) }
func TestHighTDStarvationAttack63Fast(t *testing.T)  { testHighTDStarvationAttack(t, 63, FastSync) }
func TestHighTDStarvationAttack64Full(t *testing.T)  { testHighTDStarvationAttack(t, 64, FullSync) }
func TestHighTDStarvationAttack64Fast(t *testing.T)  { testHighTDStarvationAttack(t, 64, FastSync) }
func TestHighTDStarvationAttack64Light(t *testing.T) { testHighTDStarvationAttack(t, 64, LightSync) }

func testHighTDStarvationAttack(t *testing.T, protocol int, mode SyncMode) {
    t.Parallel()

    tester := newTester()
    hashes, headers, blocks, receipts := makeChain(0, 0, genesis, nil)

    tester.newPeer("attack", protocol, []common.Hash{hashes[0]}, headers, blocks, receipts)
    if err := tester.sync("attack", big.NewInt(1000000), mode); err != errStallingPeer {
        t.Fatalf("synchronisation error mismatch: have %v, want %v", err, errStallingPeer)
    }
}

// Tests that misbehaving peers are disconnected, whilst behaving ones are not.
func TestBlockHeaderAttackerDropping61(t *testing.T) { testBlockHeaderAttackerDropping(t, 61) }
func TestBlockHeaderAttackerDropping62(t *testing.T) { testBlockHeaderAttackerDropping(t, 62) }
func TestBlockHeaderAttackerDropping63(t *testing.T) { testBlockHeaderAttackerDropping(t, 63) }
func TestBlockHeaderAttackerDropping64(t *testing.T) { testBlockHeaderAttackerDropping(t, 64) }

func testBlockHeaderAttackerDropping(t *testing.T, protocol int) {
    // Define the disconnection requirement for individual hash fetch errors
    tests := []struct {
        result error
        drop   bool
    }{
        {nil, false},                   // Sync succeeded, all is well
        {errBusy, false},               // Sync is already in progress, no problem
        {errUnknownPeer, false},        // Peer is unknown, was already dropped, don't double drop
        {errBadPeer, true},             // Peer was deemed bad for some reason, drop it
        {errStallingPeer, true},        // Peer was detected to be stalling, drop it
        {errNoPeers, false},            // No peers to download from, soft race, no issue
        {errTimeout, true},             // No hashes received in due time, drop the peer
        {errEmptyHashSet, true},        // No hashes were returned as a response, drop as it's a dead end
        {errEmptyHeaderSet, true},      // No headers were returned as a response, drop as it's a dead end
        {errPeersUnavailable, true},    // Nobody had the advertised blocks, drop the advertiser
        {errInvalidChain, true},        // Hash chain was detected as invalid, definitely drop
        {errInvalidBlock, false},       // A bad peer was detected, but not the sync origin
        {errInvalidBody, false},        // A bad peer was detected, but not the sync origin
        {errInvalidReceipt, false},     // A bad peer was detected, but not the sync origin
        {errCancelHashFetch, false},    // Synchronisation was canceled, origin may be innocent, don't drop
        {errCancelBlockFetch, false},   // Synchronisation was canceled, origin may be innocent, don't drop
        {errCancelHeaderFetch, false},  // Synchronisation was canceled, origin may be innocent, don't drop
        {errCancelBodyFetch, false},    // Synchronisation was canceled, origin may be innocent, don't drop
        {errCancelReceiptFetch, false}, // Synchronisation was canceled, origin may be innocent, don't drop
        {errCancelProcessing, false},   // Synchronisation was canceled, origin may be innocent, don't drop
    }
    // Run the tests and check disconnection status
    tester := newTester()
    for i, tt := range tests {
        // Register a new peer and ensure it's presence
        id := fmt.Sprintf("test %d", i)
        if err := tester.newPeer(id, protocol, []common.Hash{genesis.Hash()}, nil, nil, nil); err != nil {
            t.Fatalf("test %d: failed to register new peer: %v", i, err)
        }
        if _, ok := tester.peerHashes[id]; !ok {
            t.Fatalf("test %d: registered peer not found", i)
        }
        // Simulate a synchronisation and check the required result
        tester.downloader.synchroniseMock = func(string, common.Hash) error { return tt.result }

        tester.downloader.Synchronise(id, genesis.Hash(), big.NewInt(1000), FullSync)
        if _, ok := tester.peerHashes[id]; !ok != tt.drop {
            t.Errorf("test %d: peer drop mismatch for %v: have %v, want %v", i, tt.result, !ok, tt.drop)
        }
    }
}

// Tests that synchronisation progress (origin block number, current block number
// and highest block number) is tracked and updated correctly.
func TestSyncProgress61(t *testing.T)      { testSyncProgress(t, 61, FullSync) }
func TestSyncProgress62(t *testing.T)      { testSyncProgress(t, 62, FullSync) }
func TestSyncProgress63Full(t *testing.T)  { testSyncProgress(t, 63, FullSync) }
func TestSyncProgress63Fast(t *testing.T)  { testSyncProgress(t, 63, FastSync) }
func TestSyncProgress64Full(t *testing.T)  { testSyncProgress(t, 64, FullSync) }
func TestSyncProgress64Fast(t *testing.T)  { testSyncProgress(t, 64, FastSync) }
func TestSyncProgress64Light(t *testing.T) { testSyncProgress(t, 64, LightSync) }

func testSyncProgress(t *testing.T, protocol int, mode SyncMode) {
    t.Parallel()

    // Create a small enough block chain to download
    targetBlocks := blockCacheLimit - 15
    hashes, headers, blocks, receipts := makeChain(targetBlocks, 0, genesis, nil)

    // Set a sync init hook to catch progress changes
    starting := make(chan struct{})
    progress := make(chan struct{})

    tester := newTester()
    tester.downloader.syncInitHook = func(origin, latest uint64) {
        starting <- struct{}{}
        <-progress
    }
    // Retrieve the sync progress and ensure they are zero (pristine sync)
    if origin, current, latest, _, _ := tester.downloader.Progress(); origin != 0 || current != 0 || latest != 0 {
        t.Fatalf("Pristine progress mismatch: have %v/%v/%v, want %v/%v/%v", origin, current, latest, 0, 0, 0)
    }
    // Synchronise half the blocks and check initial progress
    tester.newPeer("peer-half", protocol, hashes[targetBlocks/2:], headers, blocks, receipts)
    pending := new(sync.WaitGroup)
    pending.Add(1)

    go func() {
        defer pending.Done()
        if err := tester.sync("peer-half", nil, mode); err != nil {
            t.Fatalf("failed to synchronise blocks: %v", err)
        }
    }()
    <-starting
    if origin, current, latest, _, _ := tester.downloader.Progress(); origin != 0 || current != 0 || latest != uint64(targetBlocks/2+1) {
        t.Fatalf("Initial progress mismatch: have %v/%v/%v, want %v/%v/%v", origin, current, latest, 0, 0, targetBlocks/2+1)
    }
    progress <- struct{}{}
    pending.Wait()

    // Synchronise all the blocks and check continuation progress
    tester.newPeer("peer-full", protocol, hashes, headers, blocks, receipts)
    pending.Add(1)

    go func() {
        defer pending.Done()
        if err := tester.sync("peer-full", nil, mode); err != nil {
            t.Fatalf("failed to synchronise blocks: %v", err)
        }
    }()
    <-starting
    if origin, current, latest, _, _ := tester.downloader.Progress(); origin != uint64(targetBlocks/2+1) || current != uint64(targetBlocks/2+1) || latest != uint64(targetBlocks) {
        t.Fatalf("Completing progress mismatch: have %v/%v/%v, want %v/%v/%v", origin, current, latest, targetBlocks/2+1, targetBlocks/2+1, targetBlocks)
    }
    progress <- struct{}{}
    pending.Wait()

    // Check final progress after successful sync
    if origin, current, latest, _, _ := tester.downloader.Progress(); origin != uint64(targetBlocks/2+1) || current != uint64(targetBlocks) || latest != uint64(targetBlocks) {
        t.Fatalf("Final progress mismatch: have %v/%v/%v, want %v/%v/%v", origin, current, latest, targetBlocks/2+1, targetBlocks, targetBlocks)
    }
}

// Tests that synchronisation progress (origin block number and highest block
// number) is tracked and updated correctly in case of a fork (or manual head
// revertal).
func TestForkedSyncProgress61(t *testing.T)      { testForkedSyncProgress(t, 61, FullSync) }
func TestForkedSyncProgress62(t *testing.T)      { testForkedSyncProgress(t, 62, FullSync) }
func TestForkedSyncProgress63Full(t *testing.T)  { testForkedSyncProgress(t, 63, FullSync) }
func TestForkedSyncProgress63Fast(t *testing.T)  { testForkedSyncProgress(t, 63, FastSync) }
func TestForkedSyncProgress64Full(t *testing.T)  { testForkedSyncProgress(t, 64, FullSync) }
func TestForkedSyncProgress64Fast(t *testing.T)  { testForkedSyncProgress(t, 64, FastSync) }
func TestForkedSyncProgress64Light(t *testing.T) { testForkedSyncProgress(t, 64, LightSync) }

func testForkedSyncProgress(t *testing.T, protocol int, mode SyncMode) {
    t.Parallel()

    // Create a forked chain to simulate origin revertal
    common, fork := MaxHashFetch, 2*MaxHashFetch
    hashesA, hashesB, headersA, headersB, blocksA, blocksB, receiptsA, receiptsB := makeChainFork(common+fork, fork, genesis, nil)

    // Set a sync init hook to catch progress changes
    starting := make(chan struct{})
    progress := make(chan struct{})

    tester := newTester()
    tester.downloader.syncInitHook = func(origin, latest uint64) {
        starting <- struct{}{}
        <-progress
    }
    // Retrieve the sync progress and ensure they are zero (pristine sync)
    if origin, current, latest, _, _ := tester.downloader.Progress(); origin != 0 || current != 0 || latest != 0 {
        t.Fatalf("Pristine progress mismatch: have %v/%v/%v, want %v/%v/%v", origin, current, latest, 0, 0, 0)
    }
    // Synchronise with one of the forks and check progress
    tester.newPeer("fork A", protocol, hashesA, headersA, blocksA, receiptsA)
    pending := new(sync.WaitGroup)
    pending.Add(1)

    go func() {
        defer pending.Done()
        if err := tester.sync("fork A", nil, mode); err != nil {
            t.Fatalf("failed to synchronise blocks: %v", err)
        }
    }()
    <-starting
    if origin, current, latest, _, _ := tester.downloader.Progress(); origin != 0 || current != 0 || latest != uint64(len(hashesA)-1) {
        t.Fatalf("Initial progress mismatch: have %v/%v/%v, want %v/%v/%v", origin, current, latest, 0, 0, len(hashesA)-1)
    }
    progress <- struct{}{}
    pending.Wait()

    // Simulate a successful sync above the fork
    tester.downloader.syncStatsChainOrigin = tester.downloader.syncStatsChainHeight

    // Synchronise with the second fork and check progress resets
    tester.newPeer("fork B", protocol, hashesB, headersB, blocksB, receiptsB)
    pending.Add(1)

    go func() {
        defer pending.Done()
        if err := tester.sync("fork B", nil, mode); err != nil {
            t.Fatalf("failed to synchronise blocks: %v", err)
        }
    }()
    <-starting
    if origin, current, latest, _, _ := tester.downloader.Progress(); origin != uint64(common) || current != uint64(len(hashesA)-1) || latest != uint64(len(hashesB)-1) {
        t.Fatalf("Forking progress mismatch: have %v/%v/%v, want %v/%v/%v", origin, current, latest, common, len(hashesA)-1, len(hashesB)-1)
    }
    progress <- struct{}{}
    pending.Wait()

    // Check final progress after successful sync
    if origin, current, latest, _, _ := tester.downloader.Progress(); origin != uint64(common) || current != uint64(len(hashesB)-1) || latest != uint64(len(hashesB)-1) {
        t.Fatalf("Final progress mismatch: have %v/%v/%v, want %v/%v/%v", origin, current, latest, common, len(hashesB)-1, len(hashesB)-1)
    }
}

// Tests that if synchronisation is aborted due to some failure, then the progress
// origin is not updated in the next sync cycle, as it should be considered the
// continuation of the previous sync and not a new instance.
func TestFailedSyncProgress61(t *testing.T)      { testFailedSyncProgress(t, 61, FullSync) }
func TestFailedSyncProgress62(t *testing.T)      { testFailedSyncProgress(t, 62, FullSync) }
func TestFailedSyncProgress63Full(t *testing.T)  { testFailedSyncProgress(t, 63, FullSync) }
func TestFailedSyncProgress63Fast(t *testing.T)  { testFailedSyncProgress(t, 63, FastSync) }
func TestFailedSyncProgress64Full(t *testing.T)  { testFailedSyncProgress(t, 64, FullSync) }
func TestFailedSyncProgress64Fast(t *testing.T)  { testFailedSyncProgress(t, 64, FastSync) }
func TestFailedSyncProgress64Light(t *testing.T) { testFailedSyncProgress(t, 64, LightSync) }

func testFailedSyncProgress(t *testing.T, protocol int, mode SyncMode) {
    t.Parallel()

    // Create a small enough block chain to download
    targetBlocks := blockCacheLimit - 15
    hashes, headers, blocks, receipts := makeChain(targetBlocks, 0, genesis, nil)

    // Set a sync init hook to catch progress changes
    starting := make(chan struct{})
    progress := make(chan struct{})

    tester := newTester()
    tester.downloader.syncInitHook = func(origin, latest uint64) {
        starting <- struct{}{}
        <-progress
    }
    // Retrieve the sync progress and ensure they are zero (pristine sync)
    if origin, current, latest, _, _ := tester.downloader.Progress(); origin != 0 || current != 0 || latest != 0 {
        t.Fatalf("Pristine progress mismatch: have %v/%v/%v, want %v/%v/%v", origin, current, latest, 0, 0, 0)
    }
    // Attempt a full sync with a faulty peer
    tester.newPeer("faulty", protocol, hashes, headers, blocks, receipts)
    missing := targetBlocks / 2
    delete(tester.peerHeaders["faulty"], hashes[missing])
    delete(tester.peerBlocks["faulty"], hashes[missing])
    delete(tester.peerReceipts["faulty"], hashes[missing])

    pending := new(sync.WaitGroup)
    pending.Add(1)

    go func() {
        defer pending.Done()
        if err := tester.sync("faulty", nil, mode); err == nil {
            t.Fatalf("succeeded faulty synchronisation")
        }
    }()
    <-starting
    if origin, current, latest, _, _ := tester.downloader.Progress(); origin != 0 || current != 0 || latest != uint64(targetBlocks) {
        t.Fatalf("Initial progress mismatch: have %v/%v/%v, want %v/%v/%v", origin, current, latest, 0, 0, targetBlocks)
    }
    progress <- struct{}{}
    pending.Wait()

    // Synchronise with a good peer and check that the progress origin remind the same after a failure
    tester.newPeer("valid", protocol, hashes, headers, blocks, receipts)
    pending.Add(1)

    go func() {
        defer pending.Done()
        if err := tester.sync("valid", nil, mode); err != nil {
            t.Fatalf("failed to synchronise blocks: %v", err)
        }
    }()
    <-starting
    if origin, current, latest, _, _ := tester.downloader.Progress(); origin != 0 || current > uint64(targetBlocks/2) || latest != uint64(targetBlocks) {
        t.Fatalf("Completing progress mismatch: have %v/%v/%v, want %v/0-%v/%v", origin, current, latest, 0, targetBlocks/2, targetBlocks)
    }
    progress <- struct{}{}
    pending.Wait()

    // Check final progress after successful sync
    if origin, current, latest, _, _ := tester.downloader.Progress(); origin > uint64(targetBlocks/2) || current != uint64(targetBlocks) || latest != uint64(targetBlocks) {
        t.Fatalf("Final progress mismatch: have %v/%v/%v, want 0-%v/%v/%v", origin, current, latest, targetBlocks/2, targetBlocks, targetBlocks)
    }
}

// Tests that if an attacker fakes a chain height, after the attack is detected,
// the progress height is successfully reduced at the next sync invocation.
func TestFakedSyncProgress61(t *testing.T)      { testFakedSyncProgress(t, 61, FullSync) }
func TestFakedSyncProgress62(t *testing.T)      { testFakedSyncProgress(t, 62, FullSync) }
func TestFakedSyncProgress63Full(t *testing.T)  { testFakedSyncProgress(t, 63, FullSync) }
func TestFakedSyncProgress63Fast(t *testing.T)  { testFakedSyncProgress(t, 63, FastSync) }
func TestFakedSyncProgress64Full(t *testing.T)  { testFakedSyncProgress(t, 64, FullSync) }
func TestFakedSyncProgress64Fast(t *testing.T)  { testFakedSyncProgress(t, 64, FastSync) }
func TestFakedSyncProgress64Light(t *testing.T) { testFakedSyncProgress(t, 64, LightSync) }

func testFakedSyncProgress(t *testing.T, protocol int, mode SyncMode) {
    t.Parallel()

    // Create a small block chain
    targetBlocks := blockCacheLimit - 15
    hashes, headers, blocks, receipts := makeChain(targetBlocks+3, 0, genesis, nil)

    // Set a sync init hook to catch progress changes
    starting := make(chan struct{})
    progress := make(chan struct{})

    tester := newTester()
    tester.downloader.syncInitHook = func(origin, latest uint64) {
        starting <- struct{}{}
        <-progress
    }
    // Retrieve the sync progress and ensure they are zero (pristine sync)
    if origin, current, latest, _, _ := tester.downloader.Progress(); origin != 0 || current != 0 || latest != 0 {
        t.Fatalf("Pristine progress mismatch: have %v/%v/%v, want %v/%v/%v", origin, current, latest, 0, 0, 0)
    }
    //  Create and sync with an attacker that promises a higher chain than available
    tester.newPeer("attack", protocol, hashes, headers, blocks, receipts)
    for i := 1; i < 3; i++ {
        delete(tester.peerHeaders["attack"], hashes[i])
        delete(tester.peerBlocks["attack"], hashes[i])
        delete(tester.peerReceipts["attack"], hashes[i])
    }

    pending := new(sync.WaitGroup)
    pending.Add(1)

    go func() {
        defer pending.Done()
        if err := tester.sync("attack", nil, mode); err == nil {
            t.Fatalf("succeeded attacker synchronisation")
        }
    }()
    <-starting
    if origin, current, latest, _, _ := tester.downloader.Progress(); origin != 0 || current != 0 || latest != uint64(targetBlocks+3) {
        t.Fatalf("Initial progress mismatch: have %v/%v/%v, want %v/%v/%v", origin, current, latest, 0, 0, targetBlocks+3)
    }
    progress <- struct{}{}
    pending.Wait()

    // Synchronise with a good peer and check that the progress height has been reduced to the true value
    tester.newPeer("valid", protocol, hashes[3:], headers, blocks, receipts)
    pending.Add(1)

    go func() {
        defer pending.Done()
        if err := tester.sync("valid", nil, mode); err != nil {
            t.Fatalf("failed to synchronise blocks: %v", err)
        }
    }()
    <-starting
    if origin, current, latest, _, _ := tester.downloader.Progress(); origin != 0 || current > uint64(targetBlocks) || latest != uint64(targetBlocks) {
        t.Fatalf("Completing progress mismatch: have %v/%v/%v, want %v/0-%v/%v", origin, current, latest, 0, targetBlocks, targetBlocks)
    }
    progress <- struct{}{}
    pending.Wait()

    // Check final progress after successful sync
    if origin, current, latest, _, _ := tester.downloader.Progress(); origin > uint64(targetBlocks) || current != uint64(targetBlocks) || latest != uint64(targetBlocks) {
        t.Fatalf("Final progress mismatch: have %v/%v/%v, want 0-%v/%v/%v", origin, current, latest, targetBlocks, targetBlocks, targetBlocks)
    }
}

// This test reproduces an issue where unexpected deliveries would
// block indefinitely if they arrived at the right time.
func TestDeliverHeadersHang62(t *testing.T)      { testDeliverHeadersHang(t, 62, FullSync) }
func TestDeliverHeadersHang63Full(t *testing.T)  { testDeliverHeadersHang(t, 63, FullSync) }
func TestDeliverHeadersHang63Fast(t *testing.T)  { testDeliverHeadersHang(t, 63, FastSync) }
func TestDeliverHeadersHang64Full(t *testing.T)  { testDeliverHeadersHang(t, 64, FullSync) }
func TestDeliverHeadersHang64Fast(t *testing.T)  { testDeliverHeadersHang(t, 64, FastSync) }
func TestDeliverHeadersHang64Light(t *testing.T) { testDeliverHeadersHang(t, 64, LightSync) }

func testDeliverHeadersHang(t *testing.T, protocol int, mode SyncMode) {
    t.Parallel()
    hashes, headers, blocks, receipts := makeChain(5, 0, genesis, nil)
    fakeHeads := []*types.Header{{}, {}, {}, {}}
    for i := 0; i < 200; i++ {
        tester := newTester()
        tester.newPeer("peer", protocol, hashes, headers, blocks, receipts)
        // Whenever the downloader requests headers, flood it with
        // a lot of unrequested header deliveries.
        tester.downloader.peers.peers["peer"].getAbsHeaders = func(from uint64, count, skip int, reverse bool) error {
            deliveriesDone := make(chan struct{}, 500)
            for i := 0; i < cap(deliveriesDone); i++ {
                peer := fmt.Sprintf("fake-peer%d", i)
                go func() {
                    tester.downloader.DeliverHeaders(peer, fakeHeads)
                    deliveriesDone <- struct{}{}
                }()
            }
            // Deliver the actual requested headers.
            impl := tester.peerGetAbsHeadersFn("peer", 0)
            go impl(from, count, skip, reverse)
            // None of the extra deliveries should block.
            timeout := time.After(5 * time.Second)
            for i := 0; i < cap(deliveriesDone); i++ {
                select {
                case <-deliveriesDone:
                case <-timeout:
                    panic("blocked")
                }
            }
            return nil
        }
        if err := tester.sync("peer", nil, mode); err != nil {
            t.Errorf("sync failed: %v", err)
        }
    }
}