[uClibc 0000660]: getaddrinfo() queries are redundant and in odd order
bugs at busybox.net
bugs at busybox.net
Sat Nov 1 23:26:26 UTC 2008
A NOTE has been added to this issue.
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http://busybox.net/bugs/view.php?id=660
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Reported By: akvadrako
Assigned To: uClibc
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Project: uClibc
Issue ID: 660
Category: Networking Support
Reproducibility: always
Severity: minor
Priority: normal
Status: assigned
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Date Submitted: 01-25-2006 16:52 PST
Last Modified: 11-01-2008 16:26 PDT
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Summary: getaddrinfo() queries are redundant and in odd order
Description:
I have IPv6 support enabled and three DNS servers listed in
/etc/resolv.conf. I'm looking up a hostname that only has an A record.
uClibc's getaddrinfo() looks up the records by trying each nameserver in
order then trying again two more times. When the family is AF_UNSPEC, it
completes this process for AAAA records then A records.
So in my case, to get the A record, I have to wait for 9 queries to fail
first. Since they timeout in ten seconds, this is unacceptably long if
some of the DNS servers are down.
To make the situation worse, getaddrinfo() doesn't trust query responses
with no answers. Instead it treats them as an error, and repeats the
query, even to the same host.
RFC1035 recommends retransmissions (but not timeouts) every 2-5 seconds.
I suggest three changes to the current lookup method:
* trust the first response without an error, even if negative
* ask for both type of records in each query (adds negligable size)
* retransmit every 5 seconds, not every 10
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vapier - 01-25-06 19:04
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can you try the patch in Bug 473:
http://busybox.net/bugs/file_download.php?file_id=389&type=bug
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akvadrako - 01-25-06 21:10
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Patch 389 is not relevant to this issue. This issue does not deal with
search domains or invalid encoding of domain names. The problems
discussed in this issue apply to queries of all domain names.
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vda - 11-01-08 16:26
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Revision 23895 contains a fix to not treat negative responses as errors.
Issue History
Date Modified Username Field Change
======================================================================
01-25-06 16:52 akvadrako New Issue
01-25-06 16:52 akvadrako Status new => assigned
01-25-06 16:52 akvadrako Assigned To => uClibc
01-25-06 19:04 vapier Note Added: 0001005
01-25-06 21:10 akvadrako Note Added: 0001006
07-25-06 14:34 dcostako Issue Monitored: dcostako
11-01-08 16:26 vda Note Added: 0014804
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