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
1628
1629
1630
1631
1632
1633
1634
1635
1636
1637
1638
1639
1640
1641
1642
1643
1644
1645
1646
1647
1648
1649
1650
1651
1652
1653
1654
1655
1656
1657
1658
1659
1660
1661
1662
1663
1664
1665
1666
1667
1668
1669
1670
1671
1672
1673
1674
1675
1676
1677
1678
1679
1680
1681
1682
1683
1684
1685
1686
1687
1688
1689
1690
1691
1692
1693
1694
1695
1696
1697
1698
1699
1700
1701
1702
1703
1704
1705
1706
1707
1708
1709
1710
1711
1712
1713
1714
1715
1716
1717
1718
1719
1720
1721
1722
1723
1724
1725
1726
1727
1728
1729
1730
1731
1732
1733
1734
1735
1736
1737
1738
1739
1740
1741
1742
1743
1744
1745
1746
1747
1748
1749
1750
1751
1752
1753
1754
1755
1756
1757
1758
1759
1760
1761
1762
1763
1764
1765
1766
1767
1768
1769
1770
1771
1772
1773
1774
1775
1776
1777
1778
1779
1780
1781
1782
1783
1784
1785
1786
1787
1788
1789
1790
1791
1792
1793
1794
1795
1796
1797
1798
1799
1800
1801
1802
1803
1804
1805
1806
1807
1808
1809
1810
1811
1812
1813
1814
1815
1816
1817
1818
1819
1820
1821
1822
1823
1824
1825
1826
1827
1828
1829
1830
1831
1832
1833
1834
1835
1836
1837
1838
1839
1840
1841
1842
1843
1844
1845
1846
1847
1848
1849
1850
1851
1852
1853
1854
1855
1856
1857
1858
1859
1860
1861
1862
1863
1864
1865
1866
1867
1868
1869
1870
1871
1872
1873
1874
1875
1876
1877
1878
1879
1880
1881
1882
1883
1884
1885
1886
1887
1888
1889
1890
1891
1892
1893
1894
1895
1896
1897
1898
1899
1900
1901
1902
1903
1904
1905
1906
1907
1908
1909
1910
1911
1912
1913
1914
1915
1916
1917
1918
1919
1920
1921
1922
1923
1924
1925
1926
1927
1928
1929
1930
1931
1932
1933
1934
1935
1936
1937
1938
1939
1940
1941
1942
1943
1944
1945
1946
1947
1948
1949
1950
1951
1952
1953
1954
1955
1956
1957
1958
1959
1960
1961
1962
1963
1964
1965
1966
1967
1968
1969
1970
1971
1972
1973
1974
1975
1976
1977
1978
1979
1980
1981
1982
1983
1984
1985
1986
1987
1988
1989
1990
1991
1992
1993
1994
1995
1996
1997
1998
1999
2000
2001
2002
2003
2004
2005
2006
2007
2008
2009
2010
2011
2012
2013
2014
2015
2016
2017
2018
2019
2020
2021
2022
2023
2024
2025
2026
2027
2028
2029
2030
2031
2032
2033
2034
2035
2036
2037
2038
2039
2040
2041
2042
2043
2044
2045
2046
2047
2048
2049
2050
2051
2052
2053
2054
2055
2056
2057
2058
2059
2060
2061
2062
2063
2064
2065
2066
2067
2068
2069
2070
2071
2072
2073
2074
2075
2076
2077
2078
2079
2080
2081
2082
2083
2084
2085
2086
2087
2088
2089
2090
2091
2092
2093
2094
2095
2096
2097
2098
2099
2100
2101
2102
2103
2104
2105
2106
2107
2108
2109
2110
2111
2112
2113
2114
2115
2116
2117
2118
2119
2120
2121
2122
2123
2124
2125
2126
2127
2128
2129
2130
2131
2132
2133
2134
2135
2136
2137
2138
2139
2140
2141
2142
2143
2144
2145
2146
2147
2148
2149
2150
2151
2152
2153
2154
2155
2156
2157
2158
2159
2160
2161
2162
2163
2164
2165
2166
2167
2168
2169
2170
2171
2172
2173
2174
2175
2176
2177
2178
2179
2180
2181
2182
2183
2184
2185
2186
2187
2188
2189
2190
2191
2192
2193
2194
2195
2196
2197
2198
2199
2200
2201
2202
2203
2204
2205
2206
2207
2208
2209
2210
2211
2212
2213
2214
2215
2216
2217
2218
2219
2220
2221
2222
2223
2224
2225
2226
2227
2228
2229
2230
2231
2232
2233
2234
2235
2236
2237
2238
2239
2240
2241
2242
2243
2244
2245
2246
2247
2248
2249
2250
2251
2252
2253
2254
2255
2256
2257
2258
2259
2260
2261
2262
2263
2264
2265
2266
2267
2268
2269
2270
2271
2272
2273
2274
2275
2276
2277
2278
2279
2280
2281
2282
2283
2284
2285
2286
2287
2288
2289
2290
2291
2292
2293
2294
2295
2296
2297
2298
2299
2300
2301
2302
2303
2304
2305
2306
2307
2308
2309
2310
2311
2312
2313
2314
2315
2316
2317
2318
2319
2320
2321
2322
2323
2324
2325
2326
2327
2328
2329
2330
2331
2332
2333
2334
2335
2336
2337
2338
2339
2340
2341
2342
2343
2344
2345
2346
2347
2348
2349
2350
2351
2352
2353
2354
2355
2356
2357
2358
2359
2360
2361
2362
2363
2364
2365
2366
2367
2368
2369
2370
2371
2372
2373
2374
2375
2376
2377
2378
2379
2380
2381
2382
2383
2384
2385
2386
2387
2388
2389
2390
2391
2392
2393
2394
2395
2396
2397
2398
2399
2400
2401
2402
2403
2404
2405
2406
2407
2408
2409
2410
2411
2412
2413
2414
2415
2416
2417
2418
2419
2420
2421
2422
2423
2424
2425
2426
2427
2428
2429
2430
2431
2432
2433
2434
2435
2436
2437
|
// Copyright (c) 2012 The Chromium Authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.
#include "net/dns/host_resolver_impl.h"
#include <utility>
#if defined(OS_WIN)
#include <Winsock2.h>
#elif defined(OS_POSIX)
#include <netdb.h>
#endif
#include <cmath>
#include <utility>
#include <vector>
#include "base/bind.h"
#include "base/bind_helpers.h"
#include "base/callback.h"
#include "base/compiler_specific.h"
#include "base/debug/debugger.h"
#include "base/debug/stack_trace.h"
#include "base/macros.h"
#include "base/memory/scoped_ptr.h"
#include "base/metrics/field_trial.h"
#include "base/metrics/histogram_macros.h"
#include "base/metrics/sparse_histogram.h"
#include "base/profiler/scoped_tracker.h"
#include "base/single_thread_task_runner.h"
#include "base/stl_util.h"
#include "base/strings/string_util.h"
#include "base/strings/utf_string_conversions.h"
#include "base/thread_task_runner_handle.h"
#include "base/threading/worker_pool.h"
#include "base/time/time.h"
#include "base/values.h"
#include "net/base/address_family.h"
#include "net/base/address_list.h"
#include "net/base/host_port_pair.h"
#include "net/base/ip_endpoint.h"
#include "net/base/net_errors.h"
#include "net/base/net_util.h"
#include "net/dns/address_sorter.h"
#include "net/dns/dns_client.h"
#include "net/dns/dns_config_service.h"
#include "net/dns/dns_protocol.h"
#include "net/dns/dns_reloader.h"
#include "net/dns/dns_response.h"
#include "net/dns/dns_transaction.h"
#include "net/dns/dns_util.h"
#include "net/dns/host_resolver_proc.h"
#include "net/log/net_log.h"
#include "net/socket/client_socket_factory.h"
#include "net/udp/datagram_client_socket.h"
#include "url/url_canon_ip.h"
#if defined(OS_WIN)
#include "net/base/winsock_init.h"
#endif
namespace net {
namespace {
// Limit the size of hostnames that will be resolved to combat issues in
// some platform's resolvers.
const size_t kMaxHostLength = 4096;
// Default TTL for successful resolutions with ProcTask.
const unsigned kCacheEntryTTLSeconds = 60;
// Default TTL for unsuccessful resolutions with ProcTask.
const unsigned kNegativeCacheEntryTTLSeconds = 0;
// Minimum TTL for successful resolutions with DnsTask.
const unsigned kMinimumTTLSeconds = kCacheEntryTTLSeconds;
// Time between IPv6 probes, i.e. for how long results of each IPv6 probe are
// cached.
const int kIPv6ProbePeriodMs = 1000;
// Google DNS address used for IPv6 probes.
const uint8_t kIPv6ProbeAddress[] =
{ 0x20, 0x01, 0x48, 0x60, 0x48, 0x60, 0x00, 0x00,
0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x88, 0x88 };
// We use a separate histogram name for each platform to facilitate the
// display of error codes by their symbolic name (since each platform has
// different mappings).
const char kOSErrorsForGetAddrinfoHistogramName[] =
#if defined(OS_WIN)
"Net.OSErrorsForGetAddrinfo_Win";
#elif defined(OS_MACOSX)
"Net.OSErrorsForGetAddrinfo_Mac";
#elif defined(OS_LINUX)
"Net.OSErrorsForGetAddrinfo_Linux";
#else
"Net.OSErrorsForGetAddrinfo";
#endif
// Gets a list of the likely error codes that getaddrinfo() can return
// (non-exhaustive). These are the error codes that we will track via
// a histogram.
std::vector<int> GetAllGetAddrinfoOSErrors() {
int os_errors[] = {
#if defined(OS_POSIX)
#if !defined(OS_FREEBSD)
#if !defined(OS_ANDROID)
// EAI_ADDRFAMILY has been declared obsolete in Android's and
// FreeBSD's netdb.h.
EAI_ADDRFAMILY,
#endif
// EAI_NODATA has been declared obsolete in FreeBSD's netdb.h.
EAI_NODATA,
#endif
EAI_AGAIN,
EAI_BADFLAGS,
EAI_FAIL,
EAI_FAMILY,
EAI_MEMORY,
EAI_NONAME,
EAI_SERVICE,
EAI_SOCKTYPE,
EAI_SYSTEM,
#elif defined(OS_WIN)
// See: http://msdn.microsoft.com/en-us/library/ms738520(VS.85).aspx
WSA_NOT_ENOUGH_MEMORY,
WSAEAFNOSUPPORT,
WSAEINVAL,
WSAESOCKTNOSUPPORT,
WSAHOST_NOT_FOUND,
WSANO_DATA,
WSANO_RECOVERY,
WSANOTINITIALISED,
WSATRY_AGAIN,
WSATYPE_NOT_FOUND,
// The following are not in doc, but might be to appearing in results :-(.
WSA_INVALID_HANDLE,
#endif
};
// Ensure all errors are positive, as histogram only tracks positive values.
for (size_t i = 0; i < arraysize(os_errors); ++i) {
os_errors[i] = std::abs(os_errors[i]);
}
return base::CustomHistogram::ArrayToCustomRanges(os_errors,
arraysize(os_errors));
}
enum DnsResolveStatus {
RESOLVE_STATUS_DNS_SUCCESS = 0,
RESOLVE_STATUS_PROC_SUCCESS,
RESOLVE_STATUS_FAIL,
RESOLVE_STATUS_SUSPECT_NETBIOS,
RESOLVE_STATUS_MAX
};
// ICANN uses this localhost address to indicate a name collision.
//
// The policy in Chromium is to fail host resolving if it resolves to
// this special address.
//
// Not however that IP literals are exempt from this policy, so it is still
// possible to navigate to http://127.0.53.53/ directly.
//
// For more details: https://www.icann.org/news/announcement-2-2014-08-01-en
const unsigned char kIcanNameCollisionIp[] = {127, 0, 53, 53};
void UmaAsyncDnsResolveStatus(DnsResolveStatus result) {
UMA_HISTOGRAM_ENUMERATION("AsyncDNS.ResolveStatus",
result,
RESOLVE_STATUS_MAX);
}
bool ResemblesNetBIOSName(const std::string& hostname) {
return (hostname.size() < 16) && (hostname.find('.') == std::string::npos);
}
// True if |hostname| ends with either ".local" or ".local.".
bool ResemblesMulticastDNSName(const std::string& hostname) {
DCHECK(!hostname.empty());
const char kSuffix[] = ".local.";
const size_t kSuffixLen = sizeof(kSuffix) - 1;
const size_t kSuffixLenTrimmed = kSuffixLen - 1;
if (hostname[hostname.size() - 1] == '.') {
return hostname.size() > kSuffixLen &&
!hostname.compare(hostname.size() - kSuffixLen, kSuffixLen, kSuffix);
}
return hostname.size() > kSuffixLenTrimmed &&
!hostname.compare(hostname.size() - kSuffixLenTrimmed, kSuffixLenTrimmed,
kSuffix, kSuffixLenTrimmed);
}
// Attempts to connect a UDP socket to |dest|:53.
bool IsGloballyReachable(const IPAddressNumber& dest,
const BoundNetLog& net_log) {
// TODO(eroman): Remove ScopedTracker below once crbug.com/455942 is fixed.
tracked_objects::ScopedTracker tracking_profile_1(
FROM_HERE_WITH_EXPLICIT_FUNCTION("455942 IsGloballyReachable"));
scoped_ptr<DatagramClientSocket> socket(
ClientSocketFactory::GetDefaultFactory()->CreateDatagramClientSocket(
DatagramSocket::DEFAULT_BIND,
RandIntCallback(),
net_log.net_log(),
net_log.source()));
int rv = socket->Connect(IPEndPoint(dest, 53));
if (rv != OK)
return false;
IPEndPoint endpoint;
rv = socket->GetLocalAddress(&endpoint);
if (rv != OK)
return false;
DCHECK_EQ(ADDRESS_FAMILY_IPV6, endpoint.GetFamily());
const IPAddressNumber& address = endpoint.address();
bool is_link_local = (address[0] == 0xFE) && ((address[1] & 0xC0) == 0x80);
if (is_link_local)
return false;
const uint8_t kTeredoPrefix[] = {0x20, 0x01, 0, 0};
bool is_teredo = std::equal(kTeredoPrefix,
kTeredoPrefix + arraysize(kTeredoPrefix),
address.begin());
if (is_teredo)
return false;
return true;
}
// Provide a common macro to simplify code and readability. We must use a
// macro as the underlying HISTOGRAM macro creates static variables.
#define DNS_HISTOGRAM(name, time) UMA_HISTOGRAM_CUSTOM_TIMES(name, time, \
base::TimeDelta::FromMilliseconds(1), base::TimeDelta::FromHours(1), 100)
// A macro to simplify code and readability.
#define DNS_HISTOGRAM_BY_PRIORITY(basename, priority, time) \
do { \
switch (priority) { \
case HIGHEST: DNS_HISTOGRAM(basename "_HIGHEST", time); break; \
case MEDIUM: DNS_HISTOGRAM(basename "_MEDIUM", time); break; \
case LOW: DNS_HISTOGRAM(basename "_LOW", time); break; \
case LOWEST: DNS_HISTOGRAM(basename "_LOWEST", time); break; \
case IDLE: DNS_HISTOGRAM(basename "_IDLE", time); break; \
default: NOTREACHED(); break; \
} \
DNS_HISTOGRAM(basename, time); \
} while (0)
// Record time from Request creation until a valid DNS response.
void RecordTotalTime(bool had_dns_config,
bool speculative,
base::TimeDelta duration) {
if (had_dns_config) {
if (speculative) {
DNS_HISTOGRAM("AsyncDNS.TotalTime_speculative", duration);
} else {
DNS_HISTOGRAM("AsyncDNS.TotalTime", duration);
}
} else {
if (speculative) {
DNS_HISTOGRAM("DNS.TotalTime_speculative", duration);
} else {
DNS_HISTOGRAM("DNS.TotalTime", duration);
}
}
}
void RecordTTL(base::TimeDelta ttl) {
UMA_HISTOGRAM_CUSTOM_TIMES("AsyncDNS.TTL", ttl,
base::TimeDelta::FromSeconds(1),
base::TimeDelta::FromDays(1), 100);
}
bool ConfigureAsyncDnsNoFallbackFieldTrial() {
const bool kDefault = false;
// Configure the AsyncDns field trial as follows:
// groups AsyncDnsNoFallbackA and AsyncDnsNoFallbackB: return true,
// groups AsyncDnsA and AsyncDnsB: return false,
// groups SystemDnsA and SystemDnsB: return false,
// otherwise (trial absent): return default.
std::string group_name = base::FieldTrialList::FindFullName("AsyncDns");
if (!group_name.empty()) {
return base::StartsWith(group_name, "AsyncDnsNoFallback",
base::CompareCase::INSENSITIVE_ASCII);
}
return kDefault;
}
//-----------------------------------------------------------------------------
AddressList EnsurePortOnAddressList(const AddressList& list, uint16_t port) {
if (list.empty() || list.front().port() == port)
return list;
return AddressList::CopyWithPort(list, port);
}
// Returns true if |addresses| contains only IPv4 loopback addresses.
bool IsAllIPv4Loopback(const AddressList& addresses) {
for (unsigned i = 0; i < addresses.size(); ++i) {
const IPAddressNumber& address = addresses[i].address();
switch (addresses[i].GetFamily()) {
case ADDRESS_FAMILY_IPV4:
if (address[0] != 127)
return false;
break;
case ADDRESS_FAMILY_IPV6:
return false;
default:
NOTREACHED();
return false;
}
}
return true;
}
// Creates NetLog parameters when the resolve failed.
scoped_ptr<base::Value> NetLogProcTaskFailedCallback(
uint32_t attempt_number,
int net_error,
int os_error,
NetLogCaptureMode /* capture_mode */) {
scoped_ptr<base::DictionaryValue> dict(new base::DictionaryValue());
if (attempt_number)
dict->SetInteger("attempt_number", attempt_number);
dict->SetInteger("net_error", net_error);
if (os_error) {
dict->SetInteger("os_error", os_error);
#if defined(OS_POSIX)
dict->SetString("os_error_string", gai_strerror(os_error));
#elif defined(OS_WIN)
// Map the error code to a human-readable string.
LPWSTR error_string = NULL;
FormatMessage(FORMAT_MESSAGE_ALLOCATE_BUFFER | FORMAT_MESSAGE_FROM_SYSTEM,
0, // Use the internal message table.
os_error,
0, // Use default language.
(LPWSTR)&error_string,
0, // Buffer size.
0); // Arguments (unused).
dict->SetString("os_error_string", base::WideToUTF8(error_string));
LocalFree(error_string);
#endif
}
return std::move(dict);
}
// Creates NetLog parameters when the DnsTask failed.
scoped_ptr<base::Value> NetLogDnsTaskFailedCallback(
int net_error,
int dns_error,
NetLogCaptureMode /* capture_mode */) {
scoped_ptr<base::DictionaryValue> dict(new base::DictionaryValue());
dict->SetInteger("net_error", net_error);
if (dns_error)
dict->SetInteger("dns_error", dns_error);
return std::move(dict);
};
// Creates NetLog parameters containing the information in a RequestInfo object,
// along with the associated NetLog::Source.
scoped_ptr<base::Value> NetLogRequestInfoCallback(
const HostResolver::RequestInfo* info,
NetLogCaptureMode /* capture_mode */) {
scoped_ptr<base::DictionaryValue> dict(new base::DictionaryValue());
dict->SetString("host", info->host_port_pair().ToString());
dict->SetInteger("address_family",
static_cast<int>(info->address_family()));
dict->SetBoolean("allow_cached_response", info->allow_cached_response());
dict->SetBoolean("is_speculative", info->is_speculative());
return std::move(dict);
}
// Creates NetLog parameters for the creation of a HostResolverImpl::Job.
scoped_ptr<base::Value> NetLogJobCreationCallback(
const NetLog::Source& source,
const std::string* host,
NetLogCaptureMode /* capture_mode */) {
scoped_ptr<base::DictionaryValue> dict(new base::DictionaryValue());
source.AddToEventParameters(dict.get());
dict->SetString("host", *host);
return std::move(dict);
}
// Creates NetLog parameters for HOST_RESOLVER_IMPL_JOB_ATTACH/DETACH events.
scoped_ptr<base::Value> NetLogJobAttachCallback(
const NetLog::Source& source,
RequestPriority priority,
NetLogCaptureMode /* capture_mode */) {
scoped_ptr<base::DictionaryValue> dict(new base::DictionaryValue());
source.AddToEventParameters(dict.get());
dict->SetString("priority", RequestPriorityToString(priority));
return std::move(dict);
}
// Creates NetLog parameters for the DNS_CONFIG_CHANGED event.
scoped_ptr<base::Value> NetLogDnsConfigCallback(
const DnsConfig* config,
NetLogCaptureMode /* capture_mode */) {
return make_scoped_ptr(config->ToValue());
}
scoped_ptr<base::Value> NetLogIPv6AvailableCallback(
bool ipv6_available,
bool cached,
NetLogCaptureMode /* capture_mode */) {
scoped_ptr<base::DictionaryValue> dict(new base::DictionaryValue());
dict->SetBoolean("ipv6_available", ipv6_available);
dict->SetBoolean("cached", cached);
return std::move(dict);
}
// The logging routines are defined here because some requests are resolved
// without a Request object.
// Logs when a request has just been started.
void LogStartRequest(const BoundNetLog& source_net_log,
const HostResolver::RequestInfo& info) {
source_net_log.BeginEvent(
NetLog::TYPE_HOST_RESOLVER_IMPL_REQUEST,
base::Bind(&NetLogRequestInfoCallback, &info));
}
// Logs when a request has just completed (before its callback is run).
void LogFinishRequest(const BoundNetLog& source_net_log,
const HostResolver::RequestInfo& info,
int net_error) {
source_net_log.EndEventWithNetErrorCode(
NetLog::TYPE_HOST_RESOLVER_IMPL_REQUEST, net_error);
}
// Logs when a request has been cancelled.
void LogCancelRequest(const BoundNetLog& source_net_log,
const HostResolverImpl::RequestInfo& info) {
source_net_log.AddEvent(NetLog::TYPE_CANCELLED);
source_net_log.EndEvent(NetLog::TYPE_HOST_RESOLVER_IMPL_REQUEST);
}
//-----------------------------------------------------------------------------
// Keeps track of the highest priority.
class PriorityTracker {
public:
explicit PriorityTracker(RequestPriority initial_priority)
: highest_priority_(initial_priority), total_count_(0) {
memset(counts_, 0, sizeof(counts_));
}
RequestPriority highest_priority() const {
return highest_priority_;
}
size_t total_count() const {
return total_count_;
}
void Add(RequestPriority req_priority) {
++total_count_;
++counts_[req_priority];
if (highest_priority_ < req_priority)
highest_priority_ = req_priority;
}
void Remove(RequestPriority req_priority) {
DCHECK_GT(total_count_, 0u);
DCHECK_GT(counts_[req_priority], 0u);
--total_count_;
--counts_[req_priority];
size_t i;
for (i = highest_priority_; i > MINIMUM_PRIORITY && !counts_[i]; --i);
highest_priority_ = static_cast<RequestPriority>(i);
// In absence of requests, default to MINIMUM_PRIORITY.
if (total_count_ == 0)
DCHECK_EQ(MINIMUM_PRIORITY, highest_priority_);
}
private:
RequestPriority highest_priority_;
size_t total_count_;
size_t counts_[NUM_PRIORITIES];
};
} // namespace
//-----------------------------------------------------------------------------
const unsigned HostResolverImpl::kMaximumDnsFailures = 16;
// Holds the data for a request that could not be completed synchronously.
// It is owned by a Job. Canceled Requests are only marked as canceled rather
// than removed from the Job's |requests_| list.
class HostResolverImpl::Request {
public:
Request(const BoundNetLog& source_net_log,
const RequestInfo& info,
RequestPriority priority,
const CompletionCallback& callback,
AddressList* addresses)
: source_net_log_(source_net_log),
info_(info),
priority_(priority),
job_(NULL),
callback_(callback),
addresses_(addresses),
request_time_(base::TimeTicks::Now()) {}
// Mark the request as canceled.
void MarkAsCanceled() {
job_ = NULL;
addresses_ = NULL;
callback_.Reset();
}
bool was_canceled() const {
return callback_.is_null();
}
void set_job(Job* job) {
DCHECK(job);
// Identify which job the request is waiting on.
job_ = job;
}
// Prepare final AddressList and call completion callback.
void OnComplete(int error, const AddressList& addr_list) {
DCHECK(!was_canceled());
if (error == OK)
*addresses_ = EnsurePortOnAddressList(addr_list, info_.port());
CompletionCallback callback = callback_;
MarkAsCanceled();
callback.Run(error);
}
Job* job() const {
return job_;
}
// NetLog for the source, passed in HostResolver::Resolve.
const BoundNetLog& source_net_log() {
return source_net_log_;
}
const RequestInfo& info() const {
return info_;
}
RequestPriority priority() const { return priority_; }
base::TimeTicks request_time() const { return request_time_; }
private:
const BoundNetLog source_net_log_;
// The request info that started the request.
const RequestInfo info_;
// TODO(akalin): Support reprioritization.
const RequestPriority priority_;
// The resolve job that this request is dependent on.
Job* job_;
// The user's callback to invoke when the request completes.
CompletionCallback callback_;
// The address list to save result into.
AddressList* addresses_;
const base::TimeTicks request_time_;
DISALLOW_COPY_AND_ASSIGN(Request);
};
//------------------------------------------------------------------------------
// Calls HostResolverProc on the WorkerPool. Performs retries if necessary.
//
// Whenever we try to resolve the host, we post a delayed task to check if host
// resolution (OnLookupComplete) is completed or not. If the original attempt
// hasn't completed, then we start another attempt for host resolution. We take
// the results from the first attempt that finishes and ignore the results from
// all other attempts.
//
// TODO(szym): Move to separate source file for testing and mocking.
//
class HostResolverImpl::ProcTask
: public base::RefCountedThreadSafe<HostResolverImpl::ProcTask> {
public:
typedef base::Callback<void(int net_error,
const AddressList& addr_list)> Callback;
ProcTask(const Key& key,
const ProcTaskParams& params,
const Callback& callback,
const BoundNetLog& job_net_log)
: key_(key),
params_(params),
callback_(callback),
task_runner_(base::ThreadTaskRunnerHandle::Get()),
attempt_number_(0),
completed_attempt_number_(0),
completed_attempt_error_(ERR_UNEXPECTED),
had_non_speculative_request_(false),
net_log_(job_net_log) {
if (!params_.resolver_proc.get())
params_.resolver_proc = HostResolverProc::GetDefault();
// If default is unset, use the system proc.
if (!params_.resolver_proc.get())
params_.resolver_proc = new SystemHostResolverProc();
}
void Start() {
DCHECK(task_runner_->BelongsToCurrentThread());
net_log_.BeginEvent(NetLog::TYPE_HOST_RESOLVER_IMPL_PROC_TASK);
StartLookupAttempt();
}
// Cancels this ProcTask. It will be orphaned. Any outstanding resolve
// attempts running on worker threads will continue running. Only once all the
// attempts complete will the final reference to this ProcTask be released.
void Cancel() {
DCHECK(task_runner_->BelongsToCurrentThread());
if (was_canceled() || was_completed())
return;
callback_.Reset();
net_log_.EndEvent(NetLog::TYPE_HOST_RESOLVER_IMPL_PROC_TASK);
}
void set_had_non_speculative_request() {
DCHECK(task_runner_->BelongsToCurrentThread());
had_non_speculative_request_ = true;
}
bool was_canceled() const {
DCHECK(task_runner_->BelongsToCurrentThread());
return callback_.is_null();
}
bool was_completed() const {
DCHECK(task_runner_->BelongsToCurrentThread());
return completed_attempt_number_ > 0;
}
private:
friend class base::RefCountedThreadSafe<ProcTask>;
~ProcTask() {}
void StartLookupAttempt() {
DCHECK(task_runner_->BelongsToCurrentThread());
base::TimeTicks start_time = base::TimeTicks::Now();
++attempt_number_;
// Dispatch the lookup attempt to a worker thread.
if (!base::WorkerPool::PostTask(
FROM_HERE,
base::Bind(&ProcTask::DoLookup, this, start_time, attempt_number_),
true)) {
NOTREACHED();
// Since we could be running within Resolve() right now, we can't just
// call OnLookupComplete(). Instead we must wait until Resolve() has
// returned (IO_PENDING).
task_runner_->PostTask(FROM_HERE,
base::Bind(&ProcTask::OnLookupComplete,
this,
AddressList(),
start_time,
attempt_number_,
ERR_UNEXPECTED,
0));
return;
}
net_log_.AddEvent(NetLog::TYPE_HOST_RESOLVER_IMPL_ATTEMPT_STARTED,
NetLog::IntCallback("attempt_number", attempt_number_));
// If we don't get the results within a given time, RetryIfNotComplete
// will start a new attempt on a different worker thread if none of our
// outstanding attempts have completed yet.
if (attempt_number_ <= params_.max_retry_attempts) {
task_runner_->PostDelayedTask(
FROM_HERE,
base::Bind(&ProcTask::RetryIfNotComplete, this),
params_.unresponsive_delay);
}
}
// WARNING: This code runs inside a worker pool. The shutdown code cannot
// wait for it to finish, so we must be very careful here about using other
// objects (like MessageLoops, Singletons, etc). During shutdown these objects
// may no longer exist. Multiple DoLookups() could be running in parallel, so
// any state inside of |this| must not mutate .
void DoLookup(const base::TimeTicks& start_time,
const uint32_t attempt_number) {
AddressList results;
int os_error = 0;
// Running on the worker thread
int error = params_.resolver_proc->Resolve(key_.hostname,
key_.address_family,
key_.host_resolver_flags,
&results,
&os_error);
// Fail the resolution if the result contains 127.0.53.53. See the comment
// block of kIcanNameCollisionIp for details on why.
for (const auto& it : results) {
const IPAddressNumber& cur = it.address();
if (cur.size() == arraysize(kIcanNameCollisionIp) &&
0 == memcmp(&cur.front(), kIcanNameCollisionIp, cur.size())) {
error = ERR_ICANN_NAME_COLLISION;
break;
}
}
task_runner_->PostTask(FROM_HERE,
base::Bind(&ProcTask::OnLookupComplete,
this,
results,
start_time,
attempt_number,
error,
os_error));
}
// Makes next attempt if DoLookup() has not finished (runs on task runner
// thread).
void RetryIfNotComplete() {
DCHECK(task_runner_->BelongsToCurrentThread());
if (was_completed() || was_canceled())
return;
params_.unresponsive_delay *= params_.retry_factor;
StartLookupAttempt();
}
// Callback for when DoLookup() completes (runs on task runner thread).
void OnLookupComplete(const AddressList& results,
const base::TimeTicks& start_time,
const uint32_t attempt_number,
int error,
const int os_error) {
DCHECK(task_runner_->BelongsToCurrentThread());
// If results are empty, we should return an error.
bool empty_list_on_ok = (error == OK && results.empty());
UMA_HISTOGRAM_BOOLEAN("DNS.EmptyAddressListAndNoError", empty_list_on_ok);
if (empty_list_on_ok)
error = ERR_NAME_NOT_RESOLVED;
bool was_retry_attempt = attempt_number > 1;
// Ideally the following code would be part of host_resolver_proc.cc,
// however it isn't safe to call NetworkChangeNotifier from worker threads.
// So we do it here on the IO thread instead.
if (error != OK && NetworkChangeNotifier::IsOffline())
error = ERR_INTERNET_DISCONNECTED;
// If this is the first attempt that is finishing later, then record data
// for the first attempt. Won't contaminate with retry attempt's data.
if (!was_retry_attempt)
RecordPerformanceHistograms(start_time, error, os_error);
RecordAttemptHistograms(start_time, attempt_number, error, os_error);
if (was_canceled())
return;
NetLog::ParametersCallback net_log_callback;
if (error != OK) {
net_log_callback = base::Bind(&NetLogProcTaskFailedCallback,
attempt_number,
error,
os_error);
} else {
net_log_callback = NetLog::IntCallback("attempt_number", attempt_number);
}
net_log_.AddEvent(NetLog::TYPE_HOST_RESOLVER_IMPL_ATTEMPT_FINISHED,
net_log_callback);
if (was_completed())
return;
// Copy the results from the first worker thread that resolves the host.
results_ = results;
completed_attempt_number_ = attempt_number;
completed_attempt_error_ = error;
if (was_retry_attempt) {
// If retry attempt finishes before 1st attempt, then get stats on how
// much time is saved by having spawned an extra attempt.
retry_attempt_finished_time_ = base::TimeTicks::Now();
}
if (error != OK) {
net_log_callback = base::Bind(&NetLogProcTaskFailedCallback,
0, error, os_error);
} else {
net_log_callback = results_.CreateNetLogCallback();
}
net_log_.EndEvent(NetLog::TYPE_HOST_RESOLVER_IMPL_PROC_TASK,
net_log_callback);
callback_.Run(error, results_);
}
void RecordPerformanceHistograms(const base::TimeTicks& start_time,
const int error,
const int os_error) const {
DCHECK(task_runner_->BelongsToCurrentThread());
enum Category { // Used in UMA_HISTOGRAM_ENUMERATION.
RESOLVE_SUCCESS,
RESOLVE_FAIL,
RESOLVE_SPECULATIVE_SUCCESS,
RESOLVE_SPECULATIVE_FAIL,
RESOLVE_MAX, // Bounding value.
};
int category = RESOLVE_MAX; // Illegal value for later DCHECK only.
base::TimeDelta duration = base::TimeTicks::Now() - start_time;
if (error == OK) {
if (had_non_speculative_request_) {
category = RESOLVE_SUCCESS;
DNS_HISTOGRAM("DNS.ResolveSuccess", duration);
} else {
category = RESOLVE_SPECULATIVE_SUCCESS;
DNS_HISTOGRAM("DNS.ResolveSpeculativeSuccess", duration);
}
// Log DNS lookups based on |address_family|. This will help us determine
// if IPv4 or IPv4/6 lookups are faster or slower.
switch(key_.address_family) {
case ADDRESS_FAMILY_IPV4:
DNS_HISTOGRAM("DNS.ResolveSuccess_FAMILY_IPV4", duration);
break;
case ADDRESS_FAMILY_IPV6:
DNS_HISTOGRAM("DNS.ResolveSuccess_FAMILY_IPV6", duration);
break;
case ADDRESS_FAMILY_UNSPECIFIED:
DNS_HISTOGRAM("DNS.ResolveSuccess_FAMILY_UNSPEC", duration);
break;
}
} else {
if (had_non_speculative_request_) {
category = RESOLVE_FAIL;
DNS_HISTOGRAM("DNS.ResolveFail", duration);
} else {
category = RESOLVE_SPECULATIVE_FAIL;
DNS_HISTOGRAM("DNS.ResolveSpeculativeFail", duration);
}
// Log DNS lookups based on |address_family|. This will help us determine
// if IPv4 or IPv4/6 lookups are faster or slower.
switch(key_.address_family) {
case ADDRESS_FAMILY_IPV4:
DNS_HISTOGRAM("DNS.ResolveFail_FAMILY_IPV4", duration);
break;
case ADDRESS_FAMILY_IPV6:
DNS_HISTOGRAM("DNS.ResolveFail_FAMILY_IPV6", duration);
break;
case ADDRESS_FAMILY_UNSPECIFIED:
DNS_HISTOGRAM("DNS.ResolveFail_FAMILY_UNSPEC", duration);
break;
}
UMA_HISTOGRAM_CUSTOM_ENUMERATION(kOSErrorsForGetAddrinfoHistogramName,
std::abs(os_error),
GetAllGetAddrinfoOSErrors());
}
DCHECK_LT(category, static_cast<int>(RESOLVE_MAX)); // Be sure it was set.
UMA_HISTOGRAM_ENUMERATION("DNS.ResolveCategory", category, RESOLVE_MAX);
}
void RecordAttemptHistograms(const base::TimeTicks& start_time,
const uint32_t attempt_number,
const int error,
const int os_error) const {
DCHECK(task_runner_->BelongsToCurrentThread());
bool first_attempt_to_complete =
completed_attempt_number_ == attempt_number;
bool is_first_attempt = (attempt_number == 1);
if (first_attempt_to_complete) {
// If this was first attempt to complete, then record the resolution
// status of the attempt.
if (completed_attempt_error_ == OK) {
UMA_HISTOGRAM_ENUMERATION(
"DNS.AttemptFirstSuccess", attempt_number, 100);
} else {
UMA_HISTOGRAM_ENUMERATION(
"DNS.AttemptFirstFailure", attempt_number, 100);
}
}
if (error == OK)
UMA_HISTOGRAM_ENUMERATION("DNS.AttemptSuccess", attempt_number, 100);
else
UMA_HISTOGRAM_ENUMERATION("DNS.AttemptFailure", attempt_number, 100);
// If first attempt didn't finish before retry attempt, then calculate stats
// on how much time is saved by having spawned an extra attempt.
if (!first_attempt_to_complete && is_first_attempt && !was_canceled()) {
DNS_HISTOGRAM("DNS.AttemptTimeSavedByRetry",
base::TimeTicks::Now() - retry_attempt_finished_time_);
}
if (was_canceled() || !first_attempt_to_complete) {
// Count those attempts which completed after the job was already canceled
// OR after the job was already completed by an earlier attempt (so in
// effect).
UMA_HISTOGRAM_ENUMERATION("DNS.AttemptDiscarded", attempt_number, 100);
// Record if job is canceled.
if (was_canceled())
UMA_HISTOGRAM_ENUMERATION("DNS.AttemptCancelled", attempt_number, 100);
}
base::TimeDelta duration = base::TimeTicks::Now() - start_time;
if (error == OK)
DNS_HISTOGRAM("DNS.AttemptSuccessDuration", duration);
else
DNS_HISTOGRAM("DNS.AttemptFailDuration", duration);
}
// Set on the task runner thread, read on the worker thread.
Key key_;
// Holds an owning reference to the HostResolverProc that we are going to use.
// This may not be the current resolver procedure by the time we call
// ResolveAddrInfo, but that's OK... we'll use it anyways, and the owning
// reference ensures that it remains valid until we are done.
ProcTaskParams params_;
// The listener to the results of this ProcTask.
Callback callback_;
// Used to post ourselves onto the task runner thread.
scoped_refptr<base::SingleThreadTaskRunner> task_runner_;
// Keeps track of the number of attempts we have made so far to resolve the
// host. Whenever we start an attempt to resolve the host, we increase this
// number.
uint32_t attempt_number_;
// The index of the attempt which finished first (or 0 if the job is still in
// progress).
uint32_t completed_attempt_number_;
// The result (a net error code) from the first attempt to complete.
int completed_attempt_error_;
// The time when retry attempt was finished.
base::TimeTicks retry_attempt_finished_time_;
// True if a non-speculative request was ever attached to this job
// (regardless of whether or not it was later canceled.
// This boolean is used for histogramming the duration of jobs used to
// service non-speculative requests.
bool had_non_speculative_request_;
AddressList results_;
BoundNetLog net_log_;
DISALLOW_COPY_AND_ASSIGN(ProcTask);
};
//-----------------------------------------------------------------------------
// Wraps a call to HaveOnlyLoopbackAddresses to be executed on the WorkerPool as
// it takes 40-100ms and should not block initialization.
class HostResolverImpl::LoopbackProbeJob {
public:
explicit LoopbackProbeJob(const base::WeakPtr<HostResolverImpl>& resolver)
: resolver_(resolver),
result_(false) {
DCHECK(resolver.get());
const bool kIsSlow = true;
base::WorkerPool::PostTaskAndReply(
FROM_HERE,
base::Bind(&LoopbackProbeJob::DoProbe, base::Unretained(this)),
base::Bind(&LoopbackProbeJob::OnProbeComplete, base::Owned(this)),
kIsSlow);
}
virtual ~LoopbackProbeJob() {}
private:
// Runs on worker thread.
void DoProbe() {
result_ = HaveOnlyLoopbackAddresses();
}
void OnProbeComplete() {
if (!resolver_.get())
return;
resolver_->SetHaveOnlyLoopbackAddresses(result_);
}
// Used/set only on task runner thread.
base::WeakPtr<HostResolverImpl> resolver_;
bool result_;
DISALLOW_COPY_AND_ASSIGN(LoopbackProbeJob);
};
//-----------------------------------------------------------------------------
// Resolves the hostname using DnsTransaction.
// TODO(szym): This could be moved to separate source file as well.
class HostResolverImpl::DnsTask : public base::SupportsWeakPtr<DnsTask> {
public:
class Delegate {
public:
virtual void OnDnsTaskComplete(base::TimeTicks start_time,
int net_error,
const AddressList& addr_list,
base::TimeDelta ttl) = 0;
// Called when the first of two jobs succeeds. If the first completed
// transaction fails, this is not called. Also not called when the DnsTask
// only needs to run one transaction.
virtual void OnFirstDnsTransactionComplete() = 0;
protected:
Delegate() {}
virtual ~Delegate() {}
};
DnsTask(DnsClient* client,
const Key& key,
Delegate* delegate,
const BoundNetLog& job_net_log)
: client_(client),
key_(key),
delegate_(delegate),
net_log_(job_net_log),
num_completed_transactions_(0),
task_start_time_(base::TimeTicks::Now()) {
DCHECK(client);
DCHECK(delegate_);
}
bool needs_two_transactions() const {
return key_.address_family == ADDRESS_FAMILY_UNSPECIFIED;
}
bool needs_another_transaction() const {
return needs_two_transactions() && !transaction_aaaa_;
}
void StartFirstTransaction() {
DCHECK_EQ(0u, num_completed_transactions_);
net_log_.BeginEvent(NetLog::TYPE_HOST_RESOLVER_IMPL_DNS_TASK);
if (key_.address_family == ADDRESS_FAMILY_IPV6) {
StartAAAA();
} else {
StartA();
}
}
void StartSecondTransaction() {
DCHECK(needs_two_transactions());
StartAAAA();
}
private:
void StartA() {
DCHECK(!transaction_a_);
DCHECK_NE(ADDRESS_FAMILY_IPV6, key_.address_family);
transaction_a_ = CreateTransaction(ADDRESS_FAMILY_IPV4);
transaction_a_->Start();
}
void StartAAAA() {
DCHECK(!transaction_aaaa_);
DCHECK_NE(ADDRESS_FAMILY_IPV4, key_.address_family);
transaction_aaaa_ = CreateTransaction(ADDRESS_FAMILY_IPV6);
transaction_aaaa_->Start();
}
scoped_ptr<DnsTransaction> CreateTransaction(AddressFamily family) {
DCHECK_NE(ADDRESS_FAMILY_UNSPECIFIED, family);
return client_->GetTransactionFactory()->CreateTransaction(
key_.hostname,
family == ADDRESS_FAMILY_IPV6 ? dns_protocol::kTypeAAAA :
dns_protocol::kTypeA,
base::Bind(&DnsTask::OnTransactionComplete, base::Unretained(this),
base::TimeTicks::Now()),
net_log_);
}
void OnTransactionComplete(const base::TimeTicks& start_time,
DnsTransaction* transaction,
int net_error,
const DnsResponse* response) {
DCHECK(transaction);
base::TimeDelta duration = base::TimeTicks::Now() - start_time;
if (net_error != OK) {
DNS_HISTOGRAM("AsyncDNS.TransactionFailure", duration);
OnFailure(net_error, DnsResponse::DNS_PARSE_OK);
return;
}
DNS_HISTOGRAM("AsyncDNS.TransactionSuccess", duration);
switch (transaction->GetType()) {
case dns_protocol::kTypeA:
DNS_HISTOGRAM("AsyncDNS.TransactionSuccess_A", duration);
break;
case dns_protocol::kTypeAAAA:
DNS_HISTOGRAM("AsyncDNS.TransactionSuccess_AAAA", duration);
break;
}
AddressList addr_list;
base::TimeDelta ttl;
DnsResponse::Result result = response->ParseToAddressList(&addr_list, &ttl);
UMA_HISTOGRAM_ENUMERATION("AsyncDNS.ParseToAddressList",
result,
DnsResponse::DNS_PARSE_RESULT_MAX);
if (result != DnsResponse::DNS_PARSE_OK) {
// Fail even if the other query succeeds.
OnFailure(ERR_DNS_MALFORMED_RESPONSE, result);
return;
}
++num_completed_transactions_;
if (num_completed_transactions_ == 1) {
ttl_ = ttl;
} else {
ttl_ = std::min(ttl_, ttl);
}
if (transaction->GetType() == dns_protocol::kTypeA) {
DCHECK_EQ(transaction_a_.get(), transaction);
// Place IPv4 addresses after IPv6.
addr_list_.insert(addr_list_.end(), addr_list.begin(), addr_list.end());
} else {
DCHECK_EQ(transaction_aaaa_.get(), transaction);
// Place IPv6 addresses before IPv4.
addr_list_.insert(addr_list_.begin(), addr_list.begin(), addr_list.end());
}
if (needs_two_transactions() && num_completed_transactions_ == 1) {
// No need to repeat the suffix search.
key_.hostname = transaction->GetHostname();
delegate_->OnFirstDnsTransactionComplete();
return;
}
if (addr_list_.empty()) {
// TODO(szym): Don't fallback to ProcTask in this case.
OnFailure(ERR_NAME_NOT_RESOLVED, DnsResponse::DNS_PARSE_OK);
return;
}
// If there are multiple addresses, and at least one is IPv6, need to sort
// them. Note that IPv6 addresses are always put before IPv4 ones, so it's
// sufficient to just check the family of the first address.
if (addr_list_.size() > 1 &&
addr_list_[0].GetFamily() == ADDRESS_FAMILY_IPV6) {
// Sort addresses if needed. Sort could complete synchronously.
client_->GetAddressSorter()->Sort(
addr_list_,
base::Bind(&DnsTask::OnSortComplete,
AsWeakPtr(),
base::TimeTicks::Now()));
} else {
OnSuccess(addr_list_);
}
}
void OnSortComplete(base::TimeTicks start_time,
bool success,
const AddressList& addr_list) {
if (!success) {
DNS_HISTOGRAM("AsyncDNS.SortFailure",
base::TimeTicks::Now() - start_time);
OnFailure(ERR_DNS_SORT_ERROR, DnsResponse::DNS_PARSE_OK);
return;
}
DNS_HISTOGRAM("AsyncDNS.SortSuccess",
base::TimeTicks::Now() - start_time);
// AddressSorter prunes unusable destinations.
if (addr_list.empty()) {
LOG(WARNING) << "Address list empty after RFC3484 sort";
OnFailure(ERR_NAME_NOT_RESOLVED, DnsResponse::DNS_PARSE_OK);
return;
}
OnSuccess(addr_list);
}
void OnFailure(int net_error, DnsResponse::Result result) {
DCHECK_NE(OK, net_error);
net_log_.EndEvent(
NetLog::TYPE_HOST_RESOLVER_IMPL_DNS_TASK,
base::Bind(&NetLogDnsTaskFailedCallback, net_error, result));
delegate_->OnDnsTaskComplete(task_start_time_, net_error, AddressList(),
base::TimeDelta());
}
void OnSuccess(const AddressList& addr_list) {
net_log_.EndEvent(NetLog::TYPE_HOST_RESOLVER_IMPL_DNS_TASK,
addr_list.CreateNetLogCallback());
delegate_->OnDnsTaskComplete(task_start_time_, OK, addr_list, ttl_);
}
DnsClient* client_;
Key key_;
// The listener to the results of this DnsTask.
Delegate* delegate_;
const BoundNetLog net_log_;
scoped_ptr<DnsTransaction> transaction_a_;
scoped_ptr<DnsTransaction> transaction_aaaa_;
unsigned num_completed_transactions_;
// These are updated as each transaction completes.
base::TimeDelta ttl_;
// IPv6 addresses must appear first in the list.
AddressList addr_list_;
base::TimeTicks task_start_time_;
DISALLOW_COPY_AND_ASSIGN(DnsTask);
};
//-----------------------------------------------------------------------------
// Aggregates all Requests for the same Key. Dispatched via PriorityDispatch.
class HostResolverImpl::Job : public PrioritizedDispatcher::Job,
public HostResolverImpl::DnsTask::Delegate {
public:
// Creates new job for |key| where |request_net_log| is bound to the
// request that spawned it.
Job(const base::WeakPtr<HostResolverImpl>& resolver,
const Key& key,
RequestPriority priority,
const BoundNetLog& source_net_log)
: resolver_(resolver),
key_(key),
priority_tracker_(priority),
had_non_speculative_request_(false),
had_dns_config_(false),
num_occupied_job_slots_(0),
dns_task_error_(OK),
creation_time_(base::TimeTicks::Now()),
priority_change_time_(creation_time_),
net_log_(BoundNetLog::Make(source_net_log.net_log(),
NetLog::SOURCE_HOST_RESOLVER_IMPL_JOB)) {
source_net_log.AddEvent(NetLog::TYPE_HOST_RESOLVER_IMPL_CREATE_JOB);
net_log_.BeginEvent(
NetLog::TYPE_HOST_RESOLVER_IMPL_JOB,
base::Bind(&NetLogJobCreationCallback,
source_net_log.source(),
&key_.hostname));
}
~Job() override {
if (is_running()) {
// |resolver_| was destroyed with this Job still in flight.
// Clean-up, record in the log, but don't run any callbacks.
if (is_proc_running()) {
proc_task_->Cancel();
proc_task_ = NULL;
}
// Clean up now for nice NetLog.
KillDnsTask();
net_log_.EndEventWithNetErrorCode(NetLog::TYPE_HOST_RESOLVER_IMPL_JOB,
ERR_ABORTED);
} else if (is_queued()) {
// |resolver_| was destroyed without running this Job.
// TODO(szym): is there any benefit in having this distinction?
net_log_.AddEvent(NetLog::TYPE_CANCELLED);
net_log_.EndEvent(NetLog::TYPE_HOST_RESOLVER_IMPL_JOB);
}
// else CompleteRequests logged EndEvent.
// Log any remaining Requests as cancelled.
for (const scoped_ptr<Request>& req : requests_) {
if (req->was_canceled())
continue;
DCHECK_EQ(this, req->job());
LogCancelRequest(req->source_net_log(), req->info());
}
}
// Add this job to the dispatcher. If "at_head" is true, adds at the front
// of the queue.
void Schedule(bool at_head) {
DCHECK(!is_queued());
PrioritizedDispatcher::Handle handle;
if (!at_head) {
handle = resolver_->dispatcher_->Add(this, priority());
} else {
handle = resolver_->dispatcher_->AddAtHead(this, priority());
}
// The dispatcher could have started |this| in the above call to Add, which
// could have called Schedule again. In that case |handle| will be null,
// but |handle_| may have been set by the other nested call to Schedule.
if (!handle.is_null()) {
DCHECK(handle_.is_null());
handle_ = handle;
}
}
void AddRequest(scoped_ptr<Request> req) {
DCHECK_EQ(key_.hostname, req->info().hostname());
req->set_job(this);
priority_tracker_.Add(req->priority());
req->source_net_log().AddEvent(
NetLog::TYPE_HOST_RESOLVER_IMPL_JOB_ATTACH,
net_log_.source().ToEventParametersCallback());
net_log_.AddEvent(
NetLog::TYPE_HOST_RESOLVER_IMPL_JOB_REQUEST_ATTACH,
base::Bind(&NetLogJobAttachCallback,
req->source_net_log().source(),
priority()));
// TODO(szym): Check if this is still needed.
if (!req->info().is_speculative()) {
had_non_speculative_request_ = true;
if (proc_task_.get())
proc_task_->set_had_non_speculative_request();
}
requests_.push_back(std::move(req));
UpdatePriority();
}
// Marks |req| as cancelled. If it was the last active Request, also finishes
// this Job, marking it as cancelled, and deletes it.
void CancelRequest(Request* req) {
DCHECK_EQ(key_.hostname, req->info().hostname());
DCHECK(!req->was_canceled());
// Don't remove it from |requests_| just mark it canceled.
req->MarkAsCanceled();
LogCancelRequest(req->source_net_log(), req->info());
priority_tracker_.Remove(req->priority());
net_log_.AddEvent(NetLog::TYPE_HOST_RESOLVER_IMPL_JOB_REQUEST_DETACH,
base::Bind(&NetLogJobAttachCallback,
req->source_net_log().source(),
priority()));
if (num_active_requests() > 0) {
UpdatePriority();
} else {
// If we were called from a Request's callback within CompleteRequests,
// that Request could not have been cancelled, so num_active_requests()
// could not be 0. Therefore, we are not in CompleteRequests().
CompleteRequestsWithError(OK /* cancelled */);
}
}
// Called from AbortAllInProgressJobs. Completes all requests and destroys
// the job. This currently assumes the abort is due to a network change.
// TODO This should not delete |this|.
void Abort() {
DCHECK(is_running());
CompleteRequestsWithError(ERR_NETWORK_CHANGED);
}
// If DnsTask present, abort it and fall back to ProcTask.
void AbortDnsTask() {
if (dns_task_) {
KillDnsTask();
dns_task_error_ = OK;
StartProcTask();
}
}
// Called by HostResolverImpl when this job is evicted due to queue overflow.
// Completes all requests and destroys the job.
void OnEvicted() {
DCHECK(!is_running());
DCHECK(is_queued());
handle_.Reset();
net_log_.AddEvent(NetLog::TYPE_HOST_RESOLVER_IMPL_JOB_EVICTED);
// This signals to CompleteRequests that this job never ran.
CompleteRequestsWithError(ERR_HOST_RESOLVER_QUEUE_TOO_LARGE);
}
// Attempts to serve the job from HOSTS. Returns true if succeeded and
// this Job was destroyed.
bool ServeFromHosts() {
DCHECK_GT(num_active_requests(), 0u);
AddressList addr_list;
if (resolver_->ServeFromHosts(key(),
requests_.front()->info(),
&addr_list)) {
// This will destroy the Job.
CompleteRequests(
HostCache::Entry(OK, MakeAddressListForRequest(addr_list)),
base::TimeDelta());
return true;
}
return false;
}
const Key& key() const { return key_; }
bool is_queued() const {
return !handle_.is_null();
}
bool is_running() const {
return is_dns_running() || is_proc_running();
}
private:
void KillDnsTask() {
if (dns_task_) {
ReduceToOneJobSlot();
dns_task_.reset();
}
}
// Reduce the number of job slots occupied and queued in the dispatcher
// to one. If the second Job slot is queued in the dispatcher, cancels the
// queued job. Otherwise, the second Job has been started by the
// PrioritizedDispatcher, so signals it is complete.
void ReduceToOneJobSlot() {
DCHECK_GE(num_occupied_job_slots_, 1u);
if (is_queued()) {
resolver_->dispatcher_->Cancel(handle_);
handle_.Reset();
} else if (num_occupied_job_slots_ > 1) {
resolver_->dispatcher_->OnJobFinished();
--num_occupied_job_slots_;
}
DCHECK_EQ(1u, num_occupied_job_slots_);
}
void UpdatePriority() {
if (is_queued()) {
if (priority() != static_cast<RequestPriority>(handle_.priority()))
priority_change_time_ = base::TimeTicks::Now();
handle_ = resolver_->dispatcher_->ChangePriority(handle_, priority());
}
}
AddressList MakeAddressListForRequest(const AddressList& list) const {
if (requests_.empty())
return list;
return AddressList::CopyWithPort(list, requests_.front()->info().port());
}
// PriorityDispatch::Job:
void Start() override {
DCHECK_LE(num_occupied_job_slots_, 1u);
handle_.Reset();
++num_occupied_job_slots_;
if (num_occupied_job_slots_ == 2) {
StartSecondDnsTransaction();
return;
}
DCHECK(!is_running());
net_log_.AddEvent(NetLog::TYPE_HOST_RESOLVER_IMPL_JOB_STARTED);
had_dns_config_ = resolver_->HaveDnsConfig();
base::TimeTicks now = base::TimeTicks::Now();
base::TimeDelta queue_time = now - creation_time_;
base::TimeDelta queue_time_after_change = now - priority_change_time_;
if (had_dns_config_) {
DNS_HISTOGRAM_BY_PRIORITY("AsyncDNS.JobQueueTime", priority(),
queue_time);
DNS_HISTOGRAM_BY_PRIORITY("AsyncDNS.JobQueueTimeAfterChange", priority(),
queue_time_after_change);
} else {
DNS_HISTOGRAM_BY_PRIORITY("DNS.JobQueueTime", priority(), queue_time);
DNS_HISTOGRAM_BY_PRIORITY("DNS.JobQueueTimeAfterChange", priority(),
queue_time_after_change);
}
bool system_only =
(key_.host_resolver_flags & HOST_RESOLVER_SYSTEM_ONLY) != 0;
// Caution: Job::Start must not complete synchronously.
if (!system_only && had_dns_config_ &&
!ResemblesMulticastDNSName(key_.hostname)) {
StartDnsTask();
} else {
StartProcTask();
}
}
// TODO(szym): Since DnsTransaction does not consume threads, we can increase
// the limits on |dispatcher_|. But in order to keep the number of WorkerPool
// threads low, we will need to use an "inner" PrioritizedDispatcher with
// tighter limits.
void StartProcTask() {
DCHECK(!is_dns_running());
proc_task_ = new ProcTask(
key_,
resolver_->proc_params_,
base::Bind(&Job::OnProcTaskComplete, base::Unretained(this),
base::TimeTicks::Now()),
net_log_);
if (had_non_speculative_request_)
proc_task_->set_had_non_speculative_request();
// Start() could be called from within Resolve(), hence it must NOT directly
// call OnProcTaskComplete, for example, on synchronous failure.
proc_task_->Start();
}
// Called by ProcTask when it completes.
void OnProcTaskComplete(base::TimeTicks start_time,
int net_error,
const AddressList& addr_list) {
DCHECK(is_proc_running());
if (!resolver_->resolved_known_ipv6_hostname_ &&
net_error == OK &&
key_.address_family == ADDRESS_FAMILY_UNSPECIFIED) {
if (key_.hostname == "www.google.com") {
resolver_->resolved_known_ipv6_hostname_ = true;
bool got_ipv6_address = false;
for (size_t i = 0; i < addr_list.size(); ++i) {
if (addr_list[i].GetFamily() == ADDRESS_FAMILY_IPV6) {
got_ipv6_address = true;
break;
}
}
UMA_HISTOGRAM_BOOLEAN("Net.UnspecResolvedIPv6", got_ipv6_address);
}
}
if (dns_task_error_ != OK) {
base::TimeDelta duration = base::TimeTicks::Now() - start_time;
if (net_error == OK) {
DNS_HISTOGRAM("AsyncDNS.FallbackSuccess", duration);
if ((dns_task_error_ == ERR_NAME_NOT_RESOLVED) &&
ResemblesNetBIOSName(key_.hostname)) {
UmaAsyncDnsResolveStatus(RESOLVE_STATUS_SUSPECT_NETBIOS);
} else {
UmaAsyncDnsResolveStatus(RESOLVE_STATUS_PROC_SUCCESS);
}
UMA_HISTOGRAM_SPARSE_SLOWLY("AsyncDNS.ResolveError",
std::abs(dns_task_error_));
resolver_->OnDnsTaskResolve(dns_task_error_);
} else {
DNS_HISTOGRAM("AsyncDNS.FallbackFail", duration);
UmaAsyncDnsResolveStatus(RESOLVE_STATUS_FAIL);
}
}
base::TimeDelta ttl =
base::TimeDelta::FromSeconds(kNegativeCacheEntryTTLSeconds);
if (net_error == OK)
ttl = base::TimeDelta::FromSeconds(kCacheEntryTTLSeconds);
// Don't store the |ttl| in cache since it's not obtained from the server.
CompleteRequests(
HostCache::Entry(net_error, MakeAddressListForRequest(addr_list)),
ttl);
}
void StartDnsTask() {
DCHECK(resolver_->HaveDnsConfig());
dns_task_.reset(new DnsTask(resolver_->dns_client_.get(), key_, this,
net_log_));
dns_task_->StartFirstTransaction();
// Schedule a second transaction, if needed.
if (dns_task_->needs_two_transactions())
Schedule(true);
}
void StartSecondDnsTransaction() {
DCHECK(dns_task_->needs_two_transactions());
dns_task_->StartSecondTransaction();
}
// Called if DnsTask fails. It is posted from StartDnsTask, so Job may be
// deleted before this callback. In this case dns_task is deleted as well,
// so we use it as indicator whether Job is still valid.
void OnDnsTaskFailure(const base::WeakPtr<DnsTask>& dns_task,
base::TimeDelta duration,
int net_error) {
DNS_HISTOGRAM("AsyncDNS.ResolveFail", duration);
if (dns_task == NULL)
return;
dns_task_error_ = net_error;
// TODO(szym): Run ServeFromHosts now if nsswitch.conf says so.
// http://crbug.com/117655
// TODO(szym): Some net errors indicate lack of connectivity. Starting
// ProcTask in that case is a waste of time.
if (resolver_->fallback_to_proctask_) {
KillDnsTask();
StartProcTask();
} else {
UmaAsyncDnsResolveStatus(RESOLVE_STATUS_FAIL);
CompleteRequestsWithError(net_error);
}
}
// HostResolverImpl::DnsTask::Delegate implementation:
void OnDnsTaskComplete(base::TimeTicks start_time,
int net_error,
const AddressList& addr_list,
base::TimeDelta ttl) override {
DCHECK(is_dns_running());
base::TimeDelta duration = base::TimeTicks::Now() - start_time;
if (net_error != OK) {
OnDnsTaskFailure(dns_task_->AsWeakPtr(), duration, net_error);
return;
}
DNS_HISTOGRAM("AsyncDNS.ResolveSuccess", duration);
// Log DNS lookups based on |address_family|.
switch(key_.address_family) {
case ADDRESS_FAMILY_IPV4:
DNS_HISTOGRAM("AsyncDNS.ResolveSuccess_FAMILY_IPV4", duration);
break;
case ADDRESS_FAMILY_IPV6:
DNS_HISTOGRAM("AsyncDNS.ResolveSuccess_FAMILY_IPV6", duration);
break;
case ADDRESS_FAMILY_UNSPECIFIED:
DNS_HISTOGRAM("AsyncDNS.ResolveSuccess_FAMILY_UNSPEC", duration);
break;
}
UmaAsyncDnsResolveStatus(RESOLVE_STATUS_DNS_SUCCESS);
RecordTTL(ttl);
resolver_->OnDnsTaskResolve(OK);
base::TimeDelta bounded_ttl =
std::max(ttl, base::TimeDelta::FromSeconds(kMinimumTTLSeconds));
CompleteRequests(
HostCache::Entry(net_error, MakeAddressListForRequest(addr_list), ttl),
bounded_ttl);
}
void OnFirstDnsTransactionComplete() override {
DCHECK(dns_task_->needs_two_transactions());
DCHECK_EQ(dns_task_->needs_another_transaction(), is_queued());
// No longer need to occupy two dispatcher slots.
ReduceToOneJobSlot();
// We already have a job slot at the dispatcher, so if the second
// transaction hasn't started, reuse it now instead of waiting in the queue
// for the second slot.
if (dns_task_->needs_another_transaction())
dns_task_->StartSecondTransaction();
}
// Performs Job's last rites. Completes all Requests. Deletes this.
void CompleteRequests(const HostCache::Entry& entry,
base::TimeDelta ttl) {
CHECK(resolver_.get());
// This job must be removed from resolver's |jobs_| now to make room for a
// new job with the same key in case one of the OnComplete callbacks decides
// to spawn one. Consequently, the job deletes itself when CompleteRequests
// is done.
scoped_ptr<Job> self_deleter(this);
resolver_->RemoveJob(this);
if (is_running()) {
if (is_proc_running()) {
DCHECK(!is_queued());
proc_task_->Cancel();
proc_task_ = NULL;
}
KillDnsTask();
// Signal dispatcher that a slot has opened.
resolver_->dispatcher_->OnJobFinished();
} else if (is_queued()) {
resolver_->dispatcher_->Cancel(handle_);
handle_.Reset();
}
if (num_active_requests() == 0) {
net_log_.AddEvent(NetLog::TYPE_CANCELLED);
net_log_.EndEventWithNetErrorCode(NetLog::TYPE_HOST_RESOLVER_IMPL_JOB,
OK);
return;
}
net_log_.EndEventWithNetErrorCode(NetLog::TYPE_HOST_RESOLVER_IMPL_JOB,
entry.error);
DCHECK(!requests_.empty());
if (entry.error == OK) {
// Record this histogram here, when we know the system has a valid DNS
// configuration.
UMA_HISTOGRAM_BOOLEAN("AsyncDNS.HaveDnsConfig",
resolver_->received_dns_config_);
}
bool did_complete = (entry.error != ERR_NETWORK_CHANGED) &&
(entry.error != ERR_HOST_RESOLVER_QUEUE_TOO_LARGE);
if (did_complete)
resolver_->CacheResult(key_, entry, ttl);
// Complete all of the requests that were attached to the job.
for (const scoped_ptr<Request>& req : requests_) {
if (req->was_canceled())
continue;
DCHECK_EQ(this, req->job());
// Update the net log and notify registered observers.
LogFinishRequest(req->source_net_log(), req->info(), entry.error);
if (did_complete) {
// Record effective total time from creation to completion.
RecordTotalTime(had_dns_config_, req->info().is_speculative(),
base::TimeTicks::Now() - req->request_time());
}
req->OnComplete(entry.error, entry.addrlist);
// Check if the resolver was destroyed as a result of running the
// callback. If it was, we could continue, but we choose to bail.
if (!resolver_.get())
return;
}
}
// Convenience wrapper for CompleteRequests in case of failure.
void CompleteRequestsWithError(int net_error) {
CompleteRequests(HostCache::Entry(net_error, AddressList()),
base::TimeDelta());
}
RequestPriority priority() const {
return priority_tracker_.highest_priority();
}
// Number of non-canceled requests in |requests_|.
size_t num_active_requests() const {
return priority_tracker_.total_count();
}
bool is_dns_running() const {
return dns_task_.get() != NULL;
}
bool is_proc_running() const {
return proc_task_.get() != NULL;
}
base::WeakPtr<HostResolverImpl> resolver_;
Key key_;
// Tracks the highest priority across |requests_|.
PriorityTracker priority_tracker_;
bool had_non_speculative_request_;
// Distinguishes measurements taken while DnsClient was fully configured.
bool had_dns_config_;
// Number of slots occupied by this Job in resolver's PrioritizedDispatcher.
unsigned num_occupied_job_slots_;
// Result of DnsTask.
int dns_task_error_;
const base::TimeTicks creation_time_;
base::TimeTicks priority_change_time_;
BoundNetLog net_log_;
// Resolves the host using a HostResolverProc.
scoped_refptr<ProcTask> proc_task_;
// Resolves the host using a DnsTransaction.
scoped_ptr<DnsTask> dns_task_;
// All Requests waiting for the result of this Job. Some can be canceled.
std::vector<scoped_ptr<Request>> requests_;
// A handle used in |HostResolverImpl::dispatcher_|.
PrioritizedDispatcher::Handle handle_;
};
//-----------------------------------------------------------------------------
HostResolverImpl::ProcTaskParams::ProcTaskParams(
HostResolverProc* resolver_proc,
size_t max_retry_attempts)
: resolver_proc(resolver_proc),
max_retry_attempts(max_retry_attempts),
unresponsive_delay(base::TimeDelta::FromMilliseconds(6000)),
retry_factor(2) {
// Maximum of 4 retry attempts for host resolution.
static const size_t kDefaultMaxRetryAttempts = 4u;
if (max_retry_attempts == HostResolver::kDefaultRetryAttempts)
max_retry_attempts = kDefaultMaxRetryAttempts;
}
HostResolverImpl::ProcTaskParams::~ProcTaskParams() {}
HostResolverImpl::HostResolverImpl(const Options& options, NetLog* net_log)
: max_queued_jobs_(0),
proc_params_(NULL, options.max_retry_attempts),
net_log_(net_log),
received_dns_config_(false),
num_dns_failures_(0),
use_local_ipv6_(false),
last_ipv6_probe_result_(true),
resolved_known_ipv6_hostname_(false),
additional_resolver_flags_(0),
fallback_to_proctask_(true),
weak_ptr_factory_(this),
probe_weak_ptr_factory_(this) {
if (options.enable_caching)
cache_ = HostCache::CreateDefaultCache();
PrioritizedDispatcher::Limits job_limits = options.GetDispatcherLimits();
dispatcher_.reset(new PrioritizedDispatcher(job_limits));
max_queued_jobs_ = job_limits.total_jobs * 100u;
DCHECK_GE(dispatcher_->num_priorities(), static_cast<size_t>(NUM_PRIORITIES));
#if defined(OS_WIN)
EnsureWinsockInit();
#endif
#if defined(OS_POSIX) && !defined(OS_MACOSX) && !defined(OS_ANDROID)
new LoopbackProbeJob(weak_ptr_factory_.GetWeakPtr());
#endif
NetworkChangeNotifier::AddIPAddressObserver(this);
NetworkChangeNotifier::AddDNSObserver(this);
#if defined(OS_POSIX) && !defined(OS_MACOSX) && !defined(OS_OPENBSD) && \
!defined(OS_ANDROID)
EnsureDnsReloaderInit();
#endif
{
DnsConfig dns_config;
NetworkChangeNotifier::GetDnsConfig(&dns_config);
received_dns_config_ = dns_config.IsValid();
// Conservatively assume local IPv6 is needed when DnsConfig is not valid.
use_local_ipv6_ = !dns_config.IsValid() || dns_config.use_local_ipv6;
}
fallback_to_proctask_ = !ConfigureAsyncDnsNoFallbackFieldTrial();
}
HostResolverImpl::~HostResolverImpl() {
// Prevent the dispatcher from starting new jobs.
dispatcher_->SetLimitsToZero();
// It's now safe for Jobs to call KillDsnTask on destruction, because
// OnJobComplete will not start any new jobs.
STLDeleteValues(&jobs_);
NetworkChangeNotifier::RemoveIPAddressObserver(this);
NetworkChangeNotifier::RemoveDNSObserver(this);
}
void HostResolverImpl::SetMaxQueuedJobs(size_t value) {
DCHECK_EQ(0u, dispatcher_->num_queued_jobs());
DCHECK_GT(value, 0u);
max_queued_jobs_ = value;
}
int HostResolverImpl::Resolve(const RequestInfo& info,
RequestPriority priority,
AddressList* addresses,
const CompletionCallback& callback,
RequestHandle* out_req,
const BoundNetLog& source_net_log) {
DCHECK(addresses);
DCHECK(CalledOnValidThread());
DCHECK_EQ(false, callback.is_null());
// Check that the caller supplied a valid hostname to resolve.
std::string labeled_hostname;
if (!DNSDomainFromDot(info.hostname(), &labeled_hostname))
return ERR_NAME_NOT_RESOLVED;
LogStartRequest(source_net_log, info);
IPAddressNumber ip_number;
IPAddressNumber* ip_number_ptr = nullptr;
if (ParseIPLiteralToNumber(info.hostname(), &ip_number))
ip_number_ptr = &ip_number;
// Build a key that identifies the request in the cache and in the
// outstanding jobs map.
Key key = GetEffectiveKeyForRequest(info, ip_number_ptr, source_net_log);
int rv = ResolveHelper(key, info, ip_number_ptr, addresses, source_net_log);
if (rv != ERR_DNS_CACHE_MISS) {
LogFinishRequest(source_net_log, info, rv);
RecordTotalTime(HaveDnsConfig(), info.is_speculative(), base::TimeDelta());
return rv;
}
// Next we need to attach our request to a "job". This job is responsible for
// calling "getaddrinfo(hostname)" on a worker thread.
JobMap::iterator jobit = jobs_.find(key);
Job* job;
if (jobit == jobs_.end()) {
job =
new Job(weak_ptr_factory_.GetWeakPtr(), key, priority, source_net_log);
job->Schedule(false);
// Check for queue overflow.
if (dispatcher_->num_queued_jobs() > max_queued_jobs_) {
Job* evicted = static_cast<Job*>(dispatcher_->EvictOldestLowest());
DCHECK(evicted);
evicted->OnEvicted(); // Deletes |evicted|.
if (evicted == job) {
rv = ERR_HOST_RESOLVER_QUEUE_TOO_LARGE;
LogFinishRequest(source_net_log, info, rv);
return rv;
}
}
jobs_.insert(jobit, std::make_pair(key, job));
} else {
job = jobit->second;
}
// Can't complete synchronously. Create and attach request.
scoped_ptr<Request> req(new Request(
source_net_log, info, priority, callback, addresses));
if (out_req)
*out_req = reinterpret_cast<RequestHandle>(req.get());
job->AddRequest(std::move(req));
// Completion happens during Job::CompleteRequests().
return ERR_IO_PENDING;
}
int HostResolverImpl::ResolveHelper(const Key& key,
const RequestInfo& info,
const IPAddressNumber* ip_number,
AddressList* addresses,
const BoundNetLog& source_net_log) {
// The result of |getaddrinfo| for empty hosts is inconsistent across systems.
// On Windows it gives the default interface's address, whereas on Linux it
// gives an error. We will make it fail on all platforms for consistency.
if (info.hostname().empty() || info.hostname().size() > kMaxHostLength)
return ERR_NAME_NOT_RESOLVED;
int net_error = ERR_UNEXPECTED;
if (ResolveAsIP(key, info, ip_number, &net_error, addresses))
return net_error;
if (ServeFromCache(key, info, &net_error, addresses)) {
source_net_log.AddEvent(NetLog::TYPE_HOST_RESOLVER_IMPL_CACHE_HIT);
return net_error;
}
// TODO(szym): Do not do this if nsswitch.conf instructs not to.
// http://crbug.com/117655
if (ServeFromHosts(key, info, addresses)) {
source_net_log.AddEvent(NetLog::TYPE_HOST_RESOLVER_IMPL_HOSTS_HIT);
return OK;
}
if (ServeLocalhost(key, info, addresses))
return OK;
return ERR_DNS_CACHE_MISS;
}
int HostResolverImpl::ResolveFromCache(const RequestInfo& info,
AddressList* addresses,
const BoundNetLog& source_net_log) {
DCHECK(CalledOnValidThread());
DCHECK(addresses);
// Update the net log and notify registered observers.
LogStartRequest(source_net_log, info);
IPAddressNumber ip_number;
IPAddressNumber* ip_number_ptr = nullptr;
if (ParseIPLiteralToNumber(info.hostname(), &ip_number))
ip_number_ptr = &ip_number;
Key key = GetEffectiveKeyForRequest(info, ip_number_ptr, source_net_log);
int rv = ResolveHelper(key, info, ip_number_ptr, addresses, source_net_log);
LogFinishRequest(source_net_log, info, rv);
return rv;
}
void HostResolverImpl::CancelRequest(RequestHandle req_handle) {
DCHECK(CalledOnValidThread());
Request* req = reinterpret_cast<Request*>(req_handle);
DCHECK(req);
Job* job = req->job();
DCHECK(job);
job->CancelRequest(req);
}
void HostResolverImpl::SetDnsClientEnabled(bool enabled) {
DCHECK(CalledOnValidThread());
#if defined(ENABLE_BUILT_IN_DNS)
if (enabled && !dns_client_) {
SetDnsClient(DnsClient::CreateClient(net_log_));
} else if (!enabled && dns_client_) {
SetDnsClient(scoped_ptr<DnsClient>());
}
#endif
}
HostCache* HostResolverImpl::GetHostCache() {
return cache_.get();
}
base::Value* HostResolverImpl::GetDnsConfigAsValue() const {
// Check if async DNS is disabled.
if (!dns_client_.get())
return NULL;
// Check if async DNS is enabled, but we currently have no configuration
// for it.
const DnsConfig* dns_config = dns_client_->GetConfig();
if (dns_config == NULL)
return new base::DictionaryValue();
return dns_config->ToValue();
}
bool HostResolverImpl::ResolveAsIP(const Key& key,
const RequestInfo& info,
const IPAddressNumber* ip_number,
int* net_error,
AddressList* addresses) {
DCHECK(addresses);
DCHECK(net_error);
if (ip_number == nullptr)
return false;
DCHECK_EQ(key.host_resolver_flags &
~(HOST_RESOLVER_CANONNAME | HOST_RESOLVER_LOOPBACK_ONLY |
HOST_RESOLVER_DEFAULT_FAMILY_SET_DUE_TO_NO_IPV6),
0) << " Unhandled flag";
*net_error = OK;
AddressFamily family = GetAddressFamily(*ip_number);
if (key.address_family != ADDRESS_FAMILY_UNSPECIFIED &&
key.address_family != family) {
// Don't return IPv6 addresses for IPv4 queries, and vice versa.
*net_error = ERR_NAME_NOT_RESOLVED;
} else {
*addresses = AddressList::CreateFromIPAddress(*ip_number, info.port());
if (key.host_resolver_flags & HOST_RESOLVER_CANONNAME)
addresses->SetDefaultCanonicalName();
}
return true;
}
bool HostResolverImpl::ServeFromCache(const Key& key,
const RequestInfo& info,
int* net_error,
AddressList* addresses) {
DCHECK(addresses);
DCHECK(net_error);
if (!info.allow_cached_response() || !cache_.get())
return false;
const HostCache::Entry* cache_entry = cache_->Lookup(
key, base::TimeTicks::Now());
if (!cache_entry)
return false;
*net_error = cache_entry->error;
if (*net_error == OK) {
if (cache_entry->has_ttl())
RecordTTL(cache_entry->ttl);
*addresses = EnsurePortOnAddressList(cache_entry->addrlist, info.port());
}
return true;
}
bool HostResolverImpl::ServeFromHosts(const Key& key,
const RequestInfo& info,
AddressList* addresses) {
DCHECK(addresses);
if (!HaveDnsConfig())
return false;
addresses->clear();
// HOSTS lookups are case-insensitive.
std::string hostname = base::ToLowerASCII(key.hostname);
const DnsHosts& hosts = dns_client_->GetConfig()->hosts;
// If |address_family| is ADDRESS_FAMILY_UNSPECIFIED other implementations
// (glibc and c-ares) return the first matching line. We have more
// flexibility, but lose implicit ordering.
// We prefer IPv6 because "happy eyeballs" will fall back to IPv4 if
// necessary.
if (key.address_family == ADDRESS_FAMILY_IPV6 ||
key.address_family == ADDRESS_FAMILY_UNSPECIFIED) {
DnsHosts::const_iterator it = hosts.find(
DnsHostsKey(hostname, ADDRESS_FAMILY_IPV6));
if (it != hosts.end())
addresses->push_back(IPEndPoint(it->second, info.port()));
}
if (key.address_family == ADDRESS_FAMILY_IPV4 ||
key.address_family == ADDRESS_FAMILY_UNSPECIFIED) {
DnsHosts::const_iterator it = hosts.find(
DnsHostsKey(hostname, ADDRESS_FAMILY_IPV4));
if (it != hosts.end())
addresses->push_back(IPEndPoint(it->second, info.port()));
}
// If got only loopback addresses and the family was restricted, resolve
// again, without restrictions. See SystemHostResolverCall for rationale.
if ((key.host_resolver_flags &
HOST_RESOLVER_DEFAULT_FAMILY_SET_DUE_TO_NO_IPV6) &&
IsAllIPv4Loopback(*addresses)) {
Key new_key(key);
new_key.address_family = ADDRESS_FAMILY_UNSPECIFIED;
new_key.host_resolver_flags &=
~HOST_RESOLVER_DEFAULT_FAMILY_SET_DUE_TO_NO_IPV6;
return ServeFromHosts(new_key, info, addresses);
}
return !addresses->empty();
}
bool HostResolverImpl::ServeLocalhost(const Key& key,
const RequestInfo& info,
AddressList* addresses) {
AddressList resolved_addresses;
if (!ResolveLocalHostname(key.hostname, info.port(), &resolved_addresses))
return false;
addresses->clear();
for (const auto& address : resolved_addresses) {
// Include the address if:
// - caller didn't specify an address family, or
// - caller specifically asked for the address family of this address, or
// - this is an IPv6 address and caller specifically asked for IPv4 due
// to lack of detected IPv6 support. (See SystemHostResolverCall for
// rationale).
if (key.address_family == ADDRESS_FAMILY_UNSPECIFIED ||
key.address_family == address.GetFamily() ||
(address.GetFamily() == ADDRESS_FAMILY_IPV6 &&
key.address_family == ADDRESS_FAMILY_IPV4 &&
(key.host_resolver_flags &
HOST_RESOLVER_DEFAULT_FAMILY_SET_DUE_TO_NO_IPV6))) {
addresses->push_back(address);
}
}
return true;
}
void HostResolverImpl::CacheResult(const Key& key,
const HostCache::Entry& entry,
base::TimeDelta ttl) {
if (cache_.get())
cache_->Set(key, entry, base::TimeTicks::Now(), ttl);
}
void HostResolverImpl::RemoveJob(Job* job) {
DCHECK(job);
JobMap::iterator it = jobs_.find(job->key());
if (it != jobs_.end() && it->second == job)
jobs_.erase(it);
}
void HostResolverImpl::SetHaveOnlyLoopbackAddresses(bool result) {
if (result) {
additional_resolver_flags_ |= HOST_RESOLVER_LOOPBACK_ONLY;
} else {
additional_resolver_flags_ &= ~HOST_RESOLVER_LOOPBACK_ONLY;
}
}
HostResolverImpl::Key HostResolverImpl::GetEffectiveKeyForRequest(
const RequestInfo& info,
const IPAddressNumber* ip_number,
const BoundNetLog& net_log) {
HostResolverFlags effective_flags =
info.host_resolver_flags() | additional_resolver_flags_;
AddressFamily effective_address_family = info.address_family();
if (info.address_family() == ADDRESS_FAMILY_UNSPECIFIED) {
if (!use_local_ipv6_ &&
// When resolving IPv4 literals, there's no need to probe for IPv6.
// When resolving IPv6 literals, there's no benefit to artificially
// limiting our resolution based on a probe. Prior logic ensures
// that this query is UNSPECIFIED (see info.address_family()
// check above) so the code requesting the resolution should be amenable
// to receiving a IPv6 resolution.
ip_number == nullptr) {
if (!IsIPv6Reachable(net_log)) {
effective_address_family = ADDRESS_FAMILY_IPV4;
effective_flags |= HOST_RESOLVER_DEFAULT_FAMILY_SET_DUE_TO_NO_IPV6;
}
}
}
return Key(info.hostname(), effective_address_family, effective_flags);
}
bool HostResolverImpl::IsIPv6Reachable(const BoundNetLog& net_log) {
base::TimeTicks now = base::TimeTicks::Now();
bool cached = true;
if ((now - last_ipv6_probe_time_).InMilliseconds() > kIPv6ProbePeriodMs) {
IPAddressNumber address(kIPv6ProbeAddress,
kIPv6ProbeAddress + arraysize(kIPv6ProbeAddress));
last_ipv6_probe_result_ = IsGloballyReachable(address, net_log);
last_ipv6_probe_time_ = now;
cached = false;
}
net_log.AddEvent(NetLog::TYPE_HOST_RESOLVER_IMPL_IPV6_REACHABILITY_CHECK,
base::Bind(&NetLogIPv6AvailableCallback,
last_ipv6_probe_result_, cached));
return last_ipv6_probe_result_;
}
void HostResolverImpl::AbortAllInProgressJobs() {
// In Abort, a Request callback could spawn new Jobs with matching keys, so
// first collect and remove all running jobs from |jobs_|.
std::vector<scoped_ptr<Job>> jobs_to_abort;
for (JobMap::iterator it = jobs_.begin(); it != jobs_.end(); ) {
Job* job = it->second;
if (job->is_running()) {
jobs_to_abort.push_back(make_scoped_ptr(job));
jobs_.erase(it++);
} else {
DCHECK(job->is_queued());
++it;
}
}
// Pause the dispatcher so it won't start any new dispatcher jobs while
// aborting the old ones. This is needed so that it won't start the second
// DnsTransaction for a job in |jobs_to_abort| if the DnsConfig just became
// invalid.
PrioritizedDispatcher::Limits limits = dispatcher_->GetLimits();
dispatcher_->SetLimits(
PrioritizedDispatcher::Limits(limits.reserved_slots.size(), 0));
// Life check to bail once |this| is deleted.
base::WeakPtr<HostResolverImpl> self = weak_ptr_factory_.GetWeakPtr();
// Then Abort them.
for (size_t i = 0; self.get() && i < jobs_to_abort.size(); ++i) {
jobs_to_abort[i]->Abort();
ignore_result(jobs_to_abort[i].release());
}
if (self)
dispatcher_->SetLimits(limits);
}
void HostResolverImpl::AbortDnsTasks() {
// Pause the dispatcher so it won't start any new dispatcher jobs while
// aborting the old ones. This is needed so that it won't start the second
// DnsTransaction for a job if the DnsConfig just changed.
PrioritizedDispatcher::Limits limits = dispatcher_->GetLimits();
dispatcher_->SetLimits(
PrioritizedDispatcher::Limits(limits.reserved_slots.size(), 0));
for (JobMap::iterator it = jobs_.begin(); it != jobs_.end(); ++it)
it->second->AbortDnsTask();
dispatcher_->SetLimits(limits);
}
void HostResolverImpl::TryServingAllJobsFromHosts() {
if (!HaveDnsConfig())
return;
// TODO(szym): Do not do this if nsswitch.conf instructs not to.
// http://crbug.com/117655
// Life check to bail once |this| is deleted.
base::WeakPtr<HostResolverImpl> self = weak_ptr_factory_.GetWeakPtr();
for (JobMap::iterator it = jobs_.begin(); self.get() && it != jobs_.end();) {
Job* job = it->second;
++it;
// This could remove |job| from |jobs_|, but iterator will remain valid.
job->ServeFromHosts();
}
}
void HostResolverImpl::OnIPAddressChanged() {
resolved_known_ipv6_hostname_ = false;
last_ipv6_probe_time_ = base::TimeTicks();
// Abandon all ProbeJobs.
probe_weak_ptr_factory_.InvalidateWeakPtrs();
if (cache_.get())
cache_->clear();
#if defined(OS_POSIX) && !defined(OS_MACOSX) && !defined(OS_ANDROID)
new LoopbackProbeJob(probe_weak_ptr_factory_.GetWeakPtr());
#endif
AbortAllInProgressJobs();
// |this| may be deleted inside AbortAllInProgressJobs().
}
void HostResolverImpl::OnInitialDNSConfigRead() {
UpdateDNSConfig(false);
}
void HostResolverImpl::OnDNSChanged() {
UpdateDNSConfig(true);
}
void HostResolverImpl::UpdateDNSConfig(bool config_changed) {
DnsConfig dns_config;
NetworkChangeNotifier::GetDnsConfig(&dns_config);
if (net_log_) {
net_log_->AddGlobalEntry(
NetLog::TYPE_DNS_CONFIG_CHANGED,
base::Bind(&NetLogDnsConfigCallback, &dns_config));
}
// TODO(szym): Remove once http://crbug.com/137914 is resolved.
received_dns_config_ = dns_config.IsValid();
// Conservatively assume local IPv6 is needed when DnsConfig is not valid.
use_local_ipv6_ = !dns_config.IsValid() || dns_config.use_local_ipv6;
num_dns_failures_ = 0;
// We want a new DnsSession in place, before we Abort running Jobs, so that
// the newly started jobs use the new config.
if (dns_client_.get()) {
dns_client_->SetConfig(dns_config);
if (dns_client_->GetConfig()) {
UMA_HISTOGRAM_BOOLEAN("AsyncDNS.DnsClientEnabled", true);
// If we just switched DnsClients, restart jobs using new resolver.
// TODO(pauljensen): Is this necessary?
config_changed = true;
}
}
if (config_changed) {
// If the DNS server has changed, existing cached info could be wrong so we
// have to drop our internal cache :( Note that OS level DNS caches, such
// as NSCD's cache should be dropped automatically by the OS when
// resolv.conf changes so we don't need to do anything to clear that cache.
if (cache_.get())
cache_->clear();
// Life check to bail once |this| is deleted.
base::WeakPtr<HostResolverImpl> self = weak_ptr_factory_.GetWeakPtr();
// Existing jobs will have been sent to the original server so they need to
// be aborted.
AbortAllInProgressJobs();
// |this| may be deleted inside AbortAllInProgressJobs().
if (self.get())
TryServingAllJobsFromHosts();
}
}
bool HostResolverImpl::HaveDnsConfig() const {
// Use DnsClient only if it's fully configured and there is no override by
// ScopedDefaultHostResolverProc.
// The alternative is to use NetworkChangeNotifier to override DnsConfig,
// but that would introduce construction order requirements for NCN and SDHRP.
return (dns_client_.get() != NULL) && (dns_client_->GetConfig() != NULL) &&
!(proc_params_.resolver_proc.get() == NULL &&
HostResolverProc::GetDefault() != NULL);
}
void HostResolverImpl::OnDnsTaskResolve(int net_error) {
DCHECK(dns_client_);
if (net_error == OK) {
num_dns_failures_ = 0;
return;
}
++num_dns_failures_;
if (num_dns_failures_ < kMaximumDnsFailures)
return;
// Disable DnsClient until the next DNS change. Must be done before aborting
// DnsTasks, since doing so may start new jobs.
dns_client_->SetConfig(DnsConfig());
// Switch jobs with active DnsTasks over to using ProcTasks.
AbortDnsTasks();
UMA_HISTOGRAM_BOOLEAN("AsyncDNS.DnsClientEnabled", false);
UMA_HISTOGRAM_SPARSE_SLOWLY("AsyncDNS.DnsClientDisabledReason",
std::abs(net_error));
}
void HostResolverImpl::SetDnsClient(scoped_ptr<DnsClient> dns_client) {
// DnsClient and config must be updated before aborting DnsTasks, since doing
// so may start new jobs.
dns_client_ = std::move(dns_client);
if (dns_client_ && !dns_client_->GetConfig() &&
num_dns_failures_ < kMaximumDnsFailures) {
DnsConfig dns_config;
NetworkChangeNotifier::GetDnsConfig(&dns_config);
dns_client_->SetConfig(dns_config);
num_dns_failures_ = 0;
if (dns_client_->GetConfig())
UMA_HISTOGRAM_BOOLEAN("AsyncDNS.DnsClientEnabled", true);
}
AbortDnsTasks();
}
} // namespace net
|