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review.blissroms.org / platform_packages_modules_DnsResolver / 2ddb630136ae8199debc2faa3586ba80e7ad5100
commit2ddb630136ae8199debc2faa3586ba80e7ad5100[log] [tgz]
authorBernie Innocenti <codewiz@google.com>Wed Jan 15 20:57:16 2020 +0900
committerBernie Innocenti <codewiz@google.com>Wed Jan 22 16:30:09 2020 +0900
tree0fb4cf6d2a18c36e239fb05e0fb8a693066f18de
parentc484a71a2cf3f514b99b8e89f70b2bce4067b4ca [diff]
Fix harmless cache key bug in res_cache

The resolver's cache is keyed by a hash of the query, excluding certain
sections such as the query ID and a few others. However, a loop bug
caused the entire packet to be hashed to the end after the first
invocation of _dnsPacket_hashBytes() in _dnsPacket_hashQuery().

The bug predates the inclusion of this code in Bionic in 2009, and was
likely harmless: since _dnsPacket_hashBytes() adjusts the cursor to
the end of the packet, the subsequent calls to _dnsPacket_readInt16()
fail, returning return -1, which causes the loops to execute 0 times.

This whole oldschool code could use a good rewrite into safer C++ and,
while we're at it, also switch to a proper hash function. For now,
let's start with a conservative bugfix, so at least it behaves the way
it reads.

Test: cd packages/modules/DnsResolver && atest .
Change-Id: I9368115bc16373fd64989f2a37f1dcd8f3e71b94
1 file changed
tree: 0fb4cf6d2a18c36e239fb05e0fb8a693066f18de
  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. getaddrinfo.cpp
  37. getaddrinfo.h
  38. gethnamaddr.cpp
  39. gethnamaddr.h
  40. hostent.h
  41. IDnsTlsSocket.h
  42. IDnsTlsSocketFactory.h
  43. IDnsTlsSocketObserver.h
  44. libnetd_resolv.map.txt
  45. LockedQueue.h
  46. NOTICE
  47. OWNERS
  48. params.h
  49. PREUPLOAD.cfg
  50. PrivateDnsConfiguration.cpp
  51. PrivateDnsConfiguration.h
  52. README-DoT.md
  53. README.md
  54. res_cache.cpp
  55. res_comp.cpp
  56. res_debug.cpp
  57. res_debug.h
  58. res_init.cpp
  59. res_init.h
  60. res_mkquery.cpp
  61. res_query.cpp
  62. res_send.cpp
  63. res_send.h
  64. res_stats.cpp
  65. resolv_cache.h
  66. resolv_cache_unit_test.cpp
  67. resolv_callback_unit_test.cpp
  68. resolv_private.h
  69. resolv_tls_unit_test.cpp
  70. resolv_unit_test.cpp
  71. ResolverController.cpp
  72. ResolverController.h
  73. ResolverEventReporter.cpp
  74. ResolverEventReporter.h
  75. ResolverStats.h
  76. sethostent.cpp
  77. stats.h
  78. stats.proto
  79. TEST_MAPPING
  80. util.cpp
  81. 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.