[squid-users] IPv4 addresses go missing - markAsBad wrong?

Tue Jan 16 14:37:54 UTC 2024

On 2024-01-16 06:01, Stephen Borrill wrote:
> The problem is no different with 6.6. Is there any more debugging I can 
> provide, Alex?

Yes, but I need to give you a patch that adds that (temporary) debugging 
first (assuming I fail to reproduce the problem in the lab). The ball is 
on my side (unless somebody else steps in). Unfortunately, I do not have 
any free time for any of that right now. If you do not hear from me 
sooner, please ping me again on or after February 8, 2024.

Thank you,

Alex.

> On 10/01/2024 12:40, Stephen Borrill wrote:
>> On 09/01/2024 15:42, Alex Rousskov wrote:
>>> On 2024-01-09 05:56, Stephen Borrill wrote:
>>>> On 09/01/2024 09:51, Stephen Borrill wrote:
>>>>> On 09/01/2024 03:41, Alex Rousskov wrote:
>>>>>> 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.
>>>
>>>> ipcache.cc(990) have: [2001:4860:4802:32::78]:443 at 0 in 
>>>> 216.239.38.120 #1/2-0
>>>
>>>
>>> Thank you for sharing more debugging info!
>>
>> The following seemed odd to. It finds an IPv4 address (this host does 
>> not have IPv6), puts it in the cache and then says "No DNS records":
>>
>> 2024/01/09 12:31:24.020 kid1| 14,4| ipcache.cc(617) nbgethostbyname: 
>> schoolbase.online
>> 2024/01/09 12:31:24.020 kid1| 14,3| ipcache.cc(313) ipcacheRelease: 
>> ipcacheRelease: Releasing entry for 'schoolbase.online'
>> 2024/01/09 12:31:24.020 kid1| 14,5| ipcache.cc(670) 
>> ipcache_nbgethostbyname_: ipcache_nbgethostbyname: MISS for 
>> 'schoolbase.online'
>> 2024/01/09 12:31:24.020 kid1| 14,3| ipcache.cc(480) ipcacheParse: 1 
>> answers for schoolbase.online
>> 2024/01/09 12:31:24.020 kid1| 14,7| ipcache.cc(995) have:  no 
>> 20.54.32.34 in [no cached IPs]
>> 2024/01/09 12:31:24.020 kid1| 14,7| ipcache.cc(995) have:  no 
>> 20.54.32.34 in [no cached IPs]
>> 2024/01/09 12:31:24.020 kid1| 14,5| ipcache.cc(549) updateTtl: use 
>> first 69 from RR TTL 69
>> 2024/01/09 12:31:24.020 kid1| 14,3| ipcache.cc(535) addGood: 
>> schoolbase.online #1 20.54.32.34
>> 2024/01/09 12:31:24.020 kid1| 14,7| ipcache.cc(253) forwardIp: 
>> 20.54.32.34
>> 2024/01/09 12:31:24.020 kid1| 44,2| peer_select.cc(1174) handlePath: 
>> PeerSelector72389 found conn564274 local=0.0.0.0 
>> remote=20.54.32.34:443 HIER_DIRECT flags=1, destination #1 for 
>> schoolbase.online:443
>> 2024/01/09 12:31:24.020 kid1| 14,3| ipcache.cc(459) latestError: 
>> ERROR: DNS failure while resolving schoolbase.online: No DNS records
>> 2024/01/09 12:31:24.020 kid1| 14,3| ipcache.cc(586) 
>> ipcacheHandleReply: done with schoolbase.online: 20.54.32.34 #1/1-0
>> 2024/01/09 12:31:24.020 kid1| 14,7| ipcache.cc(236) finalCallback: 
>> 0x1b7381f38  lookup_err=No DNS records
>>
>> It seemed to happen about the same time as the other failure, so 
>> perhaps another symptom of the same.
>>
>>> The above log line is self-contradictory AFAICT: It says that the 
>>> cache has both IPv6-looking and IPv4-looking address at the same 
>>> cache position (0) and, judging by the corresponding code, those two 
>>> IP addresses are equal. This is not possible (for those specific IP 
>>> address values). The subsequent Squid behavior can be explained by 
>>> this (unexplained) conflict.
>>>
>>> I assume you are running official Squid v6.5 code.
>>
>> Yes, compiled from source on NetBSD. I have the patch I refer to here 
>> applied too:
>> https://lists.squid-cache.org/pipermail/squid-users/2023-November/026279.html
>>
>>> I can suggest the following two steps for going forward:
>>>
>>> 1. Upgrade to the latest Squid v6 in hope that the problem goes away.
>>
>> I have just upgraded to 6.6.
>>
>>> 2. If the problem is still there, patch the latest Squid v6 to add 
>>> more debugging in hope to explain what is going on. This may take a 
>>> few iterations, and it will take me some time to produce the 
>>> necessary debugging patch.
>>
>> Unfortunately, I don't have a test case that will cause the problem so 
>> I need to run this at a customer's production site that is 
>> particularly affected by it. Luckily, the problem recurs pretty quickly.
>>
>> Here's a run with 6.6 where the number of destinations drops from 2 to 
>> 1 before reverting. Not seen this before - usually once it has dropped 
>> to 1 (the IPv6 address), it stays there until a restart (and this did 
>> happen about a minute after this log fragment). Happy to test out any 
>> debugging patch.
>>
>> 2024/01/10 11:55:49.849 kid1| 14,4| ipcache.cc(617) nbgethostbyname: 
>> forcesafesearch.google.com
>> 2024/01/10 11:55:49.849 kid1| 14,3| Address.cc(389) lookupHostIP: 
>> Given Non-IP 'forcesafesearch.google.com': hostname or servname not 
>> provided or not known
>> 2024/01/10 11:55:49.849 kid1| 14,4| ipcache.cc(657) 
>> ipcache_nbgethostbyname_: ipcache_nbgethostbyname: HIT for 
>> 'forcesafesearch.google.com'
>> 2024/01/10 11:55:49.849 kid1| 14,7| ipcache.cc(253) forwardIp: 
>> [2001:4860:4802:32::78]
>> 2024/01/10 11:55:49.849 kid1| 44,2| peer_select.cc(1174) handlePath: 
>> PeerSelector300176 found conn2388484 local=[::] 
>> remote=[2001:4860:4802:32::78]:443 HIER_DIRECT flags=1, destination #1 
>> for forcesafesearch.google.com:443
>> 2024/01/10 11:55:49.849 kid1| 44,2| peer_select.cc(1180) handlePath: 
>> always_direct = ALLOWED
>> 2024/01/10 11:55:49.849 kid1| 44,2| peer_select.cc(1181) handlePath: 
>> never_direct = DENIED
>> 2024/01/10 11:55:49.849 kid1| 44,2| peer_select.cc(1182) handlePath: 
>> timedout = 0
>> 2024/01/10 11:55:49.849 kid1| 14,7| ipcache.cc(253) forwardIp: 
>> 216.239.38.120
>> 2024/01/10 11:55:49.849 kid1| 44,2| peer_select.cc(1174) handlePath: 
>> PeerSelector300176 found conn2388485 local=0.0.0.0 
>> remote=216.239.38.120:443 HIER_DIRECT flags=1, destination #2 for 
>> forcesafesearch.google.com:443
>> 2024/01/10 11:55:49.849 kid1| 44,2| peer_select.cc(1180) handlePath: 
>> always_direct = ALLOWED
>> 2024/01/10 11:55:49.849 kid1| 44,2| peer_select.cc(1181) handlePath: 
>> never_direct = DENIED
>> 2024/01/10 11:55:49.849 kid1| 44,2| peer_select.cc(1182) handlePath: 
>> timedout = 0
>> 2024/01/10 11:55:49.849 kid1| 14,7| ipcache.cc(236) finalCallback: 
>> 0x12208e038
>> 2024/01/10 11:55:49.849 kid1| 44,2| peer_select.cc(479) 
>> resolveSelected: PeerSelector300176 found all 2 destinations for 
>> forcesafesearch.google.com:443
>> 2024/01/10 11:55:49.849 kid1| 44,2| peer_select.cc(480) 
>> resolveSelected:    always_direct = ALLOWED
>> 2024/01/10 11:55:49.849 kid1| 44,2| peer_select.cc(481) 
>> resolveSelected:     never_direct = DENIED
>> 2024/01/10 11:55:49.849 kid1| 44,2| peer_select.cc(482) 
>> resolveSelected:         timedout = 0
>> 2024/01/10 11:55:49.849 kid1| 14,7| ipcache.cc(990) have: 
>> [2001:4860:4802:32::78]:443 at 0 in [2001:4860:4802:32::78] #2/2-0
>> 2024/01/10 11:55:49.849 kid1| 14,2| ipcache.cc(1031) markAsBad: 
>> [2001:4860:4802:32::78]:443 of forcesafesearch.google.com
>> 2024/01/10 11:55:49.855 kid1| 14,7| ipcache.cc(990) have: 
>> 216.239.38.120:443 at 0 in [2001:4860:4802:32::78] #2/2-1
>> 2024/01/10 11:55:49.855 kid1| 14,2| ipcache.cc(1055) forgetMarking: 
>> 216.239.38.120:443 of forcesafesearch.google.com
>> 2024/01/10 11:55:49.877 kid1| 14,3| Address.cc(389) lookupHostIP: 
>> Given Non-IP 'forcesafesearch.google.com': hostname or servname not 
>> provided or not known
>> 2024/01/10 11:55:49.877 kid1| 44,2| peer_select.cc(460) 
>> resolveSelected: Find IP destination for: 
>> forcesafesearch.google.com:443' via forcesafesearch.google.com
>> 2024/01/10 11:55:49.877 kid1| 14,4| ipcache.cc(617) nbgethostbyname: 
>> forcesafesearch.google.com
>> 2024/01/10 11:55:49.877 kid1| 14,3| Address.cc(389) lookupHostIP: 
>> Given Non-IP 'forcesafesearch.google.com': hostname or servname not 
>> provided or not known
>> 2024/01/10 11:55:49.877 kid1| 14,4| ipcache.cc(657) 
>> ipcache_nbgethostbyname_: ipcache_nbgethostbyname: HIT for 
>> 'forcesafesearch.google.com'
>> 2024/01/10 11:55:49.877 kid1| 14,7| ipcache.cc(253) forwardIp: 
>> [2001:4860:4802:32::78]
>> 2024/01/10 11:55:49.877 kid1| 44,2| peer_select.cc(1174) handlePath: 
>> PeerSelector300177 found conn2388493 local=[::] 
>> remote=[2001:4860:4802:32::78]:443 HIER_DIRECT flags=1, destination #1 
>> for forcesafesearch.google.com:443
>> 2024/01/10 11:55:49.877 kid1| 44,2| peer_select.cc(1180) handlePath: 
>> always_direct = ALLOWED
>> 2024/01/10 11:55:49.877 kid1| 44,2| peer_select.cc(1181) handlePath: 
>> never_direct = DENIED
>> 2024/01/10 11:55:49.877 kid1| 44,2| peer_select.cc(1182) handlePath: 
>> timedout = 0
>> 2024/01/10 11:55:49.877 kid1| 14,7| ipcache.cc(253) forwardIp: 
>> 216.239.38.120
>> 2024/01/10 11:55:49.877 kid1| 44,2| peer_select.cc(1174) handlePath: 
>> PeerSelector300177 found conn2388494 local=0.0.0.0 
>> remote=216.239.38.120:443 HIER_DIRECT flags=1, destination #2 for 
>> forcesafesearch.google.com:443
>> 2024/01/10 11:55:49.877 kid1| 44,2| peer_select.cc(1180) handlePath: 
>> always_direct = ALLOWED
>> 2024/01/10 11:55:49.877 kid1| 44,2| peer_select.cc(1181) handlePath: 
>> never_direct = DENIED
>> 2024/01/10 11:55:49.877 kid1| 44,2| peer_select.cc(1182) handlePath: 
>> timedout = 0
>> 2024/01/10 11:55:49.877 kid1| 14,7| ipcache.cc(236) finalCallback: 
>> 0x12208e038
>> 2024/01/10 11:55:49.877 kid1| 44,2| peer_select.cc(479) 
>> resolveSelected: PeerSelector300177 found all 2 destinations for 
>> forcesafesearch.google.com:443
>> 2024/01/10 11:55:49.877 kid1| 44,2| peer_select.cc(480) 
>> resolveSelected:    always_direct = ALLOWED
>> 2024/01/10 11:55:49.877 kid1| 44,2| peer_select.cc(481) 
>> resolveSelected:     never_direct = DENIED
>> 2024/01/10 11:55:49.877 kid1| 44,2| peer_select.cc(482) 
>> resolveSelected:         timedout = 0
>> 2024/01/10 11:55:49.877 kid1| 14,7| ipcache.cc(990) have: 
>> [2001:4860:4802:32::78]:443 at 0 in [2001:4860:4802:32::78] #2/2-0
>> 2024/01/10 11:55:49.877 kid1| 14,2| ipcache.cc(1031) markAsBad: 
>> [2001:4860:4802:32::78]:443 of forcesafesearch.google.com
>> 2024/01/10 11:55:49.882 kid1| 14,7| ipcache.cc(990) have: 
>> 216.239.38.120:443 at 0 in [2001:4860:4802:32::78] #2/2-1
>> 2024/01/10 11:55:49.882 kid1| 14,2| ipcache.cc(1055) forgetMarking: 
>> 216.239.38.120:443 of forcesafesearch.google.com
>>
> 
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