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android / platform / packages / modules / DnsResolver / refs/tags/android-r-beta-2
tag1eae18f4e6abb52f79ab0437f9bb899e900e1c3e
taggerThe Android Open Source Project <initial-contribution@android.com>Tue Jul 14 15:07:09 2020 -0700
object61d17267051d7ffaf8cd3457207936da93e6d374 
Android R Beta 2
commit61d17267051d7ffaf8cd3457207936da93e6d374[log] [tgz]
authorMike Yu <yumike@google.com>Sat Feb 15 18:56:22 2020 +0800
committerMike Yu <yumike@google.com>Tue Jul 14 02:53:08 2020 +0000
tree4b881041db658114a62c3ed8be98b74e00b92744
parent6ce587d2c38bcc7dc90985bb7ba687cf27aa1e8e [diff]
Support prioritizing DNS servers

The change introduces a way to prioritize DNS servers on the basis of
DNS query response time, which aims to replace the current design that
is biased towards using the first DNS server assigned from networks.

The quality is evaluated based on the heuristics:
  - The more latency it is, the less likely it is used.
  - The longer time it is not used, the more likely it is used.

Compared to the current design, the proposed method detects bad DNS
servers more quickly. For instance, a server which is unreachable or
times out can be detected and deprioritized with few trials by backoff
penalty and abnormal latency.

Similar to the current design, a server which has been regarded as bad
quality can be used again, but it depends on how much worse it is. A
counter is used to count how many times a DNS server not being used,
which avoids from constantly using the same DNS server.

This change comprises:

[1] Allow the resolver to sort DNS servers on the basis of DNS query
    response time.
[2] Add an experiment flag to enable/disable the sorting.
[3] Show the result of the quantified quality of DNS servers in
    dumpsys dnsresolver.
[4] Add unit tests for DnsStats::getSortedServers().
[5] Revise the integration tests which are sensitive to the nameserver
    sorting, including two big changes in SkipBadServersDueToInternalError
    and SkipBadServersDueToTimeout and some minor changes.

Bug: 137169582
Test: ran resolv_unit_test
      ran resolv_integration_test with the sorting enabled
      ran resolv_integration_test with the sorting disabled
Change-Id: I24b6a317f135a942ce0ea310c81dfe658bada6a7
8 files changed
tree: 4b881041db658114a62c3ed8be98b74e00b92744
  1. aidl_api/
  2. apex/
  3. binder/
  4. include/
  5. tests/
  6. .clang-format ⇨ ../../../build/soong/scripts/system-clang-format
  7. .editorconfig
  8. Android.bp
  9. Dns64Configuration.cpp
  10. Dns64Configuration.h
  11. DnsProxyListener.cpp
  12. DnsProxyListener.h
  13. DnsQueryLog.cpp
  14. DnsQueryLog.h
  15. DnsQueryLogTest.cpp
  16. DnsResolver.cpp
  17. DnsResolver.h
  18. DnsResolverService.cpp
  19. DnsResolverService.h
  20. DnsStats.cpp
  21. DnsStats.h
  22. DnsStatsTest.cpp
  23. DnsTlsDispatcher.cpp
  24. DnsTlsDispatcher.h
  25. DnsTlsQueryMap.cpp
  26. DnsTlsQueryMap.h
  27. DnsTlsServer.cpp
  28. DnsTlsServer.h
  29. DnsTlsSessionCache.cpp
  30. DnsTlsSessionCache.h
  31. DnsTlsSocket.cpp
  32. DnsTlsSocket.h
  33. DnsTlsSocketFactory.h
  34. DnsTlsTransport.cpp
  35. DnsTlsTransport.h
  36. Experiments.cpp
  37. Experiments.h
  38. ExperimentsTest.cpp
  39. getaddrinfo.cpp
  40. getaddrinfo.h
  41. gethnamaddr.cpp
  42. gethnamaddr.h
  43. hostent.h
  44. IDnsTlsSocket.h
  45. IDnsTlsSocketFactory.h
  46. IDnsTlsSocketObserver.h
  47. libnetd_resolv.map.txt
  48. LockedQueue.h
  49. NOTICE
  50. OWNERS
  51. params.h
  52. PREUPLOAD.cfg
  53. PrivateDnsConfiguration.cpp
  54. PrivateDnsConfiguration.h
  55. README-DoT.md
  56. README.md
  57. res_cache.cpp
  58. res_comp.cpp
  59. res_comp.h
  60. res_debug.cpp
  61. res_debug.h
  62. res_init.cpp
  63. res_init.h
  64. res_mkquery.cpp
  65. res_query.cpp
  66. res_send.cpp
  67. res_send.h
  68. res_stats.cpp
  69. resolv_cache.h
  70. resolv_cache_unit_test.cpp
  71. resolv_callback_unit_test.cpp
  72. resolv_private.h
  73. resolv_test_config_template.xml
  74. resolv_tls_unit_test.cpp
  75. resolv_unit_test.cpp
  76. ResolverController.cpp
  77. ResolverController.h
  78. ResolverEventReporter.cpp
  79. ResolverEventReporter.h
  80. ResolverStats.h
  81. sethostent.cpp
  82. stats.h
  83. stats.proto
  84. TEST_MAPPING
  85. util.cpp
  86. util.h
README.md

Logging

This code uses LOG(X) for logging. Log levels are VERBOSE,DEBUG,INFO,WARNING and ERROR. The default setting is WARNING and logs relate to WARNING and ERROR will be shown. If you want to enable the DEBUG level logs, using following command. adb shell service call dnsresolver 10 i32 1 VERBOSE 0 DEBUG 1 INFO 2 WARNING 3 ERROR 4 Verbose resolver logs could contain PII -- do NOT enable in production builds.