Re: [patch] resolv.conf.5 add "single-request-reopen" option

[Todd Lewis <utoddl-vEoVa6Jh+/J4piUD7e9S/g@public.gmane.org>]

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Well, this is embarrassing. It turns out RedHat has this documented in
their RHEL series, but not in Fedora. It's also not in the man-pages
project. The attached patch has a better explanation of the option than
the one I submitted earlier today. This text comes from RedHat.

On 09/11/2012 02:35 PM, Todd Lewis sent:
> The attached "diff -u" formatted patch applies to
> http://git.kernel.org/?p=docs/man-pages/man-pages.git;a=blob_plain;f=man5/resolv.conf.5;hb=HEAD
> as it existed on 2012-09-11--14:31.
> 
> It adds documentation for the "single-request-reopen" option. This
> information was found in the changelog notes
> (http://sourceware.org/ml/libc-alpha/2009-10/msg00063.html) from Ulrich
> Drepper. The issue and solution were both brought to my attention by a
> discussion on our internal mailing list which mentioned this undocumented
> feature. Several users indicated they have been suffering from slow DNS
> resolutions on machines behind certain firewalls and that this solved
> their problems. Seems like others would like to know about it.

-- 
   +--------------------------------------------------------------+
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--- /tmp/man5_resolv.conf.5-orig	2012-09-11 14:25:26.406461617 -0400
+++ /tmp/man5_resolv.conf.5	2012-09-11 16:21:48.264137192 -0400
@@ -168,6 +168,13 @@
 (currently 2, see \fI<resolv.h>\fP).
 The value for this option is silently capped to 5.
 .TP
+.BR single-request-reopen " (since glibc 2.9)"
+The resolver uses the same socket for the A and AAAA requests.  Some hardware
+mistakenly only sends back one reply.  When that happens the client sytem will
+sit and wait for the second reply.  Turning this option on changes this behavior
+so that if two requests from the same port are not handled correctly it will
+close the  socket and open a new one before sending the second request.
+.TP
 .B rotate
 .\" Since glibc 2.2
 sets