On 2024-01-08 08:31, Stephen Borrill wrote:
I'm trying to determine why squid 6.x (seen with 6.5) connected via
IPv4-only periodically fails to connect to the destination and then
requires a restart to fix it (reload is not sufficient).
The problem appears to be that a host that has one address each of IPv4
and IPv6 occasionally has its IPv4 address go missing as a destination.
On closer inspection, this appears to happen when the IPv6 address (not
the IPv4) address is marked as bad. A log fragment is as follows:
2024/01/08 13:18:39.974 kid1| 44,2| peer_select.cc(460) resolveSelected:
Find IP destination for: clientservices.googleapis.com:443' via
clientservices.googleapis.com
2024/01/08 13:18:39.974 kid1| 44,2| peer_select.cc(1174) handlePath:
PeerSelector82284 found conn696198 local=0.0.0.0
remote=142.250.187.227:443 HIER_DIRECT flags=1, destination #1 for
clientservices.googleapis.com:443
2024/01/08 13:18:39.974 kid1| 44,2| peer_select.cc(1174) handlePath:
PeerSelector82284 found conn696199 local=[::]
remote=[2a00:1450:4009:820::2003]:443 HIER_DIRECT flags=1, destination
#2 for clientservices.googleapis.com:443
2024/01/08 13:18:39.974 kid1| 44,2| peer_select.cc(479) resolveSelected:
PeerSelector82284 found all 2 destinations for
clientservices.googleapis.com:443
2024/01/08 13:18:40.245 kid1| 14,2| ipcache.cc(1031) markAsBad:
[2a00:1450:4009:820::2003]:443 of clientservices.googleapis.com
2024/01/08 13:18:40.245 kid1| 14,3| ipcache.cc(946) seekNewGood:
succeeded for clientservices.googleapis.com: [2a00:1450:4009:820::2003]
#2/2-1
2024/01/08 13:18:40.245 kid1| 14,3| ipcache.cc(978) restoreGoodness:
cleared all IPs for clientservices.googleapis.com; now back to
[2a00:1450:4009:820::2003] #2/2-1
2024/01/08 13:18:42.065 kid1| 14,3| Address.cc(389) lookupHostIP: Given
Non-IP 'clientservices.googleapis.com': hostname or servname not
provided or not known
2024/01/08 13:18:42.065 kid1| 44,2| peer_select.cc(460) resolveSelected:
Find IP destination for: clientservices.googleapis.com:443' via
clientservices.googleapis.com
2024/01/08 13:18:42.065 kid1| 14,3| Address.cc(389) lookupHostIP: Given
Non-IP 'clientservices.googleapis.com': hostname or servname not
provided or not known
2024/01/08 13:18:42.065 kid1| 44,2| peer_select.cc(1174) handlePath:
PeerSelector82372 found conn697148 local=[::]
remote=[2a00:1450:4009:820::2003]:443 HIER_DIRECT flags=1, destination
#1 for clientservices.googleapis.com:443
2024/01/08 13:18:42.065 kid1| 44,2| peer_select.cc(479) resolveSelected:
PeerSelector82372 found all 1 destinations for
clientservices.googleapis.com:443
This shows two subsequent connection attempts to
clientservices.googleapis.com. The first one has both IPv4 and IPv6
destinations. The IPv6 address is passed to markAsBad.
Yes.
After that the IPv4 address is not listed as a destination.
I do not see that. I see IPv6 address being selected as the first
destination (instead of the IPv4 address).
I cannot explain why that happens though. Moreover, a combination of
certain lines in your debug output near "seekNewGood" do not make sense
to me -- I do not see how it is possible for Squid to display those
exact debugging details, but I am probably missing something. Can you
retest and repost similar lines with 14,9 (or at least 14,7) added to
your debug_options (or share those lines privately; the more lines you
can share, the better)?
Note that there have been many connections to
clientservices.googleapis.com prior to this where markAsBad was not
called, even though IPv6 connectivity was never available.
No markAsBad() is probably normal if Squid did not try to establish an
IPv6 connection or did not wait long enough to know the result of that
attempt. However, that does not explain why Squid selected an IPv6
address as the next "good" address right after marking that IPv6 address
as bad (at "restoreGoodness" line) when there was another good IP
address available. It is as if Squid stored two identical IPv6 addresses
(and not IPv4 ones), but that should not happen either.
Alex.
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