[ruby-core:94401] [Ruby master Feature#9925] rsock_addrinfo uses DNS family AF_UNSPEC for lookup causing high IPv6 AAAA volume
From:
aaron@...
Date:
2019-08-17 16:07:35 UTC
List:
ruby-core #94401
Issue #9925 has been updated by aaron@serendipity.cx (Aaron Stone).
Thank you Craig! Since your patch was accepted, this ticket is now resolved for me. I'll also mark my Ruby Github PR as resolved by your PR.
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Feature #9925: rsock_addrinfo uses DNS family AF_UNSPEC for lookup causing high IPv6 AAAA volume
https://bugs.ruby-lang.org/issues/9925#change-80822
* Author: aaron@serendipity.cx (Aaron Stone)
* Status: Open
* Priority: Normal
* Assignee:
* Target version:
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In ext/socket/raddrinfo.c, the function `rsock_addrinfo()` always uses `AF_UNSPEC` for DNS queries. This is causing me a very high volume of IPv6 DNS lookups. `rsock_addrinfo()` is used by TCPSocket (and all other Socket base classes, e.g. Socket and UDPSocket), and TCPSocket is used by Net::HTTP.
Remember that DNS does not do negative caching - if a hostname does not have a AAAA record, then DNS will _always_ try to look up that record again!
I propose that the following code should have some way to force IPv4 or IPv6 lookups:
http://rxr.whitequark.org/mri/source/ext/socket/raddrinfo.c
~~~c
378 struct addrinfo*
379 rsock_addrinfo(VALUE host, VALUE port, int socktype, int flags)
380 {
381 struct addrinfo hints;
382
383 MEMZERO(&hints, struct addrinfo, 1);
384 hints.ai_family = AF_UNSPEC;
385 hints.ai_socktype = socktype;
386 hints.ai_flags = flags;
387 return rsock_getaddrinfo(host, port, &hints, 1);
388 }
~~~
For example, an environment variable named something like `RUBY_GAI` could be set to "INET" or "INET6" to switch the `hints.ai_family` away from `AF_UNSPEC`.
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