[OpenAFS] Strange DNS SRV traffic resulting from stat() in 1.8.13.2

[Ryan C. Underwood]

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Hi openafs-info,

I recently tried out the 1.8.13.2 client on my Ubuntu laptop,
upgrading from a somewhat older client version.  Historically, I have
used @sys-based components in PATH as a way of centrally managing
CLI tools without having to distribute them to every system I use.
However, this has become problematic in the following way.

Immediately after system startup, all is well, my shell profile loads
immediately and CLI commands also return immediately.  However, after
some time of system utilization, not necessarily including any heavy
AFS usage, doing anything within my shell profile slows to a crawl.
The reason is because of the AFS-based PATH component.  Instead of
stat() calls returning immediately, at this point each one creates
many DNS roundtrips fetching some very strange SRV records that I do
not recall seeing before, and which are perhaps malformed:

12:52:12.101148 IP 192.168.8.248.46167 > 192.168.8.1.53: 25095+ AFSDB?  ice=
quake.net/users/nemesis/bin/bash. (53)
12:52:12.245481 IP 192.168.8.1.53 > 192.168.8.248.46167: 25095 NXDomain 0/1=
/0 (128)
12:52:12.246822 IP 192.168.8.248.57487 > 192.168.8.1.53: 46166+ AFSDB?  ice=
quake.net/users/nemesis/bin/bash.icequake.net. (66)
12:52:12.407925 IP 192.168.8.1.53 > 192.168.8.248.57487: 46166 NXDomain* 0/=
1/0 (134)
12:52:12.408765 IP 192.168.8.248.60842 > 192.168.8.1.53: 45806+ SRV?  _afs3=
-vlserver._udp.icequake.net/users/nemesis/bin/bash. (73)
12:52:12.612530 IP 192.168.8.1.53 > 192.168.8.248.60842: 45806 NXDomain 0/1=
/0 (148)
12:52:12.613264 IP 192.168.8.248.33038 > 192.168.8.1.53: 54461+ SRV?  _afs3=
-vlserver._udp.icequake.net/users/nemesis/bin/bash.icequake.net.  (86)
12:52:12.817311 IP 192.168.8.1.53 > 192.168.8.248.33038: 54461 NXDomain* 0/=
1/0 (154)
12:52:12.817829 IP 192.168.8.248.33177 > 192.168.8.1.53: 53983+ SRV?  _afs3=
-vlserver._udp.icequake.net/users/nemesis/bin/bash. (73)
12:52:12.958650 IP 192.168.8.1.53 > 192.168.8.248.33177: 53983 NXDomain 0/1=
/0 (148)
12:52:12.959152 IP 192.168.8.248.50256 > 192.168.8.1.53: 12967+ SRV?  _afs3=
-vlserver._udp.icequake.net/users/nemesis/bin/bash.icequake.net.  (86)
12:52:13.124390 IP 192.168.8.1.53 > 192.168.8.248.50256: 12967 NXDomain* 0/=
1/0 (154)
12:52:13.125189 IP 192.168.8.248.47935 > 192.168.8.1.53: 56862+ AFSDB?  ice=
quake.net/users/nemesis/bin/bash. (53)
12:52:13.329797 IP 192.168.8.1.53 > 192.168.8.248.47935: 56862 NXDomain 0/1=
/0 (128)
12:52:13.330370 IP 192.168.8.248.58386 > 192.168.8.1.53: 55085+ AFSDB?  ice=
quake.net/users/nemesis/bin/bash.icequake.net. (66)
12:52:13.537502 IP 192.168.8.1.53 > 192.168.8.248.58386: 55085 NXDomain* 0/=
1/0 (134)
12:52:13.540776 IP 192.168.8.248.41895 > 192.168.8.1.53: 6729+ SRV?  _afs3-=
vlserver._udp.icequake.net/users/nemesis/@sys/bin/bash. (78)
12:52:13.740662 IP 192.168.8.1.53 > 192.168.8.248.41895: 6729 NXDomain 0/1/=
0 (153)
12:52:13.741143 IP 192.168.8.248.37102 > 192.168.8.1.53: 33110+ SRV?  _afs3=
-vlserver._udp.icequake.net/users/nemesis/@sys/bin/bash.icequake.net.  (91)
12:52:14.159513 IP 192.168.8.1.53 > 192.168.8.248.37102: 33110 NXDomain* 0/=
1/0 (159)
12:52:14.160055 IP 192.168.8.248.58652 > 192.168.8.1.53: 64126+ SRV?  _afs3=
-vlserver._udp.icequake.net/users/nemesis/@sys/bin/bash. (78)
12:52:14.731726 IP 192.168.8.1.53 > 192.168.8.248.58652: 64126 NXDomain 0/1=
/0 (153)
12:52:14.732197 IP 192.168.8.248.41774 > 192.168.8.1.53: 19149+ SRV?  _afs3=
-vlserver._udp.icequake.net/users/nemesis/@sys/bin/bash.icequake.net.  (91)
[...]

Can someone explain what is going on here?  Whatever is happening, it
is bypassing the cache manager because the same strange queries are
issued repeatedly as the shell profile executes.  It's additionally
painful in the case of my laptop, since the ultimate DNS server is on
the other end of a VPN link.

I believe the previous version I was using (without this new behavior)
was 1.8.10, but don't quote me on that.

Thanks,
Ryan

--=20
Ryan C. Underwood, <nemesis@icequake.net>

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